1.1 – Responses to Public Comments on General Comments

This file contains responses to public comments on general comments (comment codes

1000 to 1390).  This section includes comments on the terminology and definitions used

in the rule, the proposed regulatory text, the need for flexibility or stringency, and other

general comments on geologic sequestration.  

Note that most comments on regulatory text (comment code 1240) are not included

here but are presented in other sections to which they pertain (e.g., comments on the

rule language for mechanical integrity testing are in section 2.5). However, a few

comments on the regulatory text are included here in section 1.1.1.3 because they do

not pertain to any other aspects of the rule.

The table below presents all of the EPA‐assigned comment codes that are included in

this section of the comment and response summary.  Use the bookmarks in the PDF to

move among the comment codes.   

Topics included in this summary and associated comment codes

Topic Code

1. General and Administrative Comments 1000

1.1 General comments about the rulemaking 1200

1.1.1 Comments about the proposed rule 1210

1.1.1.1 Terminology and definitions 1220

1.1.1.2 General comments on the regulatory text 1230

1.1.1.3 Suggested changes/edits to rule language 1240

1.1.1.4 Flexibility is needed (performance‐based standards) 1250

1.1.1.5 More certainty/stringency is needed 1260

1.1.2 Comments on other rules/issues 1270

1.1.2.1 General comments on climate change/ global warming 1280

1.1.2.2 Comments that EPA should regulate CO2 as a pollutant 1290

1.1.2.3 Comments on other aspects of CCS (capture, transport) 1300

1.1.2.4 Comments on other "out of scope" issues, e.g., pore space ownership 1310

1.1.3 General comments about GS 1320

1.1.3.1 Support use of GS in general 1330

1.1.3.2 Oppose use of GS in general 1340

1.1.3.3 Comments on the need for GS technology 1350

1.1.3.4 Effectiveness of trapping mechanisms 1360

1.1.3.5 US storage capacity 1370

1.1.3.6 Deployment of GS 1380

1.1.4 Comments on materials in the rulemaking docket (No comments were submitted for

this topic.)

1390

Every comment on these topic areas and the associated response is included in this

summary; there is some repetition where multiple commenters made the same

comment.
Responses to letters from individual commenters or organizations are also available in

the rulemaking docket.

  
Comment Code: 1000 1. General and Administrative Comments 

Individual Comments 

Other EPA Comment Codes and Descriptions: 1330 1.1.3.1 Support use of GS in general 

Comment: ODEC supports the comments of the Carbon Capture and Sequestration Alliance 

(CCS, or the Alliance) on the proposed UIC regulations. The CCS Alliance is a 

coalition of entities, spanning a number of economic sectors, that share a 

common interest in removing impediments to investment in and development of CCS, 

as well as mitigating the potential risks associated with the deployment ofthis 

technology.[l] Its purpose is to promote development of policy by the states and 

the federal government to appropriately address risks and potential liabilities, 

thereby enabling the further development and increased deployment of CCS. The 

CCS Alliance believes these technologies can be developed while protecting 

underground water resources, significantly reducing global and U.S. greenhouse 

gas ("GHG") emissions, and enhancing u.s. energy security. The Alliance's 

purpose is to consider ways ofpromoting the development and use ofCCS 

technologies and to support effOlis by the private sector, states, the federal 

government, non- governmental organizations and others, to help ensure that 

these technologies can be developed and widely, efficiently and cost-effectively 

deployed. 

Response: EPA clarifies that the purpose of the UIC GS regulation is to ensure that GS is conducted in 

a manner that protects USDWs from endangerment. EPA agrees that GS is one technology in a portfolio 

of options, including energy conservation, efficiency improvements, and the use of alternative fuels and 

renewable energy sources, that could be deployed to reduce CO2 emissions. 

Please see the remainder of EPA’s responses to this comment, and CCS Alliance’s comment for further 

details. For additional information on EPA’s final regulatory approach, please see the final rule and 

preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1330 1.1.3.1 Support use of GS in general 

Comment: To whom it may concern: 

I appreciate the opportunity to provide comments on the proposed rules for 

federal management of geologic sequestration of CO2 in Docket ID No. EPA-HQOW-2008-0390. This is a unique opportunity to broaden our national public policy 

foundation by melding new federal energy policy with responsible natural 

resource policy and, in so-doing, expand economic opportunities and potentially 

reduce the amount of CO2 that is introduced into the atmosphere. As currently 

written, provisions of the proposed rules related to the suitability of specific 

reinjection locations cause serious concern. 

Wyoming has been proactive in its stewardship of all state resources and we 

Commenter Name: Kenneth Alexander Letter ID: 0146

Commenter Organization: Old Dominion Electric Cooperative (ODEC) Comment ID: 21726

Commenter Name: Dave Freudenthal Letter ID: 0150

Commenter Organization: State of Wyoming Comment ID: 22216

1
recognize the need for environmental regulation. Over the years we have 

demonstrated our regulatory capability by meeting and often exceeding EPA 

standards in managing activities that impact public health, public safety and 

all public resources. We are eager to collaborate with the federal government 

yet again, to craft rules that work not only for the interests of the nation but 

that also work directly for the people of Wyoming. Within the framework of this 

collaborative undertaking, the importance of including local expertise and 

knowledge into the regulation of CO2 sequestration is necessary to ensure public 

safety while also providing new growth opportunities for a vibrant new 

industry. 

Response: EPA recognizes the importance of states having primacy for GS wells given the variety of 

geologic settings in which GS will be applied. EPA recognizes that State, Tribal, Territorial, and DI UIC 

program Directors are in the best position to evaluate the unique issues related to well depth, geology, 

and hydrogeology that are posed by a Class VI well. Some degree of flexibility is needed for Class VI 

wells because each decision made will be site-specific and conditions will differ from state to state. The 

GS rule balances the need for these site-specific decisions with the need for minimum Federal 

requirements to ensure national consistency while ensuring the protection of USDWs. 

EPA also believes that providing states the flexibility to obtain primacy for Class VI wells 

independently of other well classes can help foster effective management of CCS. EPA believes that 

allowing independent Class VI primacy may encourage states to take responsibility for implementation 

of Class VI regulations and provide for a more comprehensive approach to managing CCS projects by 

promoting the integration of GS activities under SDWA into a broader framework for managing CCS. 

Furthermore, GS operations involve ancillary activities (e.g., pipeline operations, pore space ownership, 

land use rights, and surface access) for which states can call upon other authorities that exist at the state 

level (but outside UIC authority) to provide a more comprehensive CCS management approach. The 

Agency will allow independent primacy for Class VI wells under §145.1(i) of the final GS rule. 

For additional information on EPA's final regulatory approach, please see the final rule and preamble as 

well as the rulemaking docket. EPA is using an adaptive approach to regulating GS. 

Comment: Geologists, geochemists and geophysicists from both the public and private 

sectors have been researching and analyzing Wyoming geology for nearly a 

century. Their work provides a rich database and a solid foundation of specific 

attributes for underground geologic structures and systems. Our reliance on 

natural resource development in Wyoming has closely tied our economic livelihood 

to these endeavors, and there is a wealth of local expertise and knowledge about 

Wyoming geology which should be factored into any federal rulemaking regarding 

CO2 sequestration. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. EPA is using an adaptive approach to 

regulating GS. 

Commenter Name: Dave Freudenthal Letter ID: 0150

Commenter Organization: State of Wyoming Comment ID: 22217

Commenter Name: Dave Freudenthal Letter ID: 0150

2
Comment: For economic and regulatory purposes, the regulations as proposed will make 

geological sequestration of CO2 nearly impossible. Overarching CO2 sequestration 

regulations which do not provide an opportunity to use Rocky Mountain Laramide 

geology will make it extremely difficult to mitigate the effects of greenhouse 

emissions on climate change in the West. I ask that you adopt the 

recommendations of the WSGS, and if you have further questions regarding the 

WSGS recommendations, please contact Ron Surdam, the Wyoming State Geologist 

(phone: 307.766.2286). 

I look forward to a strong and effective partnership with the EPA in order to 

promulgate regulations governing CO2 sequestration that meet both the interests 

of the federal government and the state of Wyoming. Thank you for your careful 

consideration of our comments regarding the proposed rules and their importance. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: The MGA would like to address a few areas of the proposed rule within the 

context of the goals and objectives of the Platform. The MGA goals include: 

• A model regional regulatory framework for CCS by 2010; 

• A multi-jurisdictional pipeline sited and permitted to transport CO2 from a 

source to an appropriate reservoir for use in an EOR project by 2012; 

• At least 7 pre and post-combustion coal plants with CCS in operation by 2015; 

• All new coal gasification and coal combustion plants will capture and store 

CO2 emissions by 2020; and 

• The region’s fleet of coal plants will have transitioned to CCS by 2050. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

EPA clarifies that permitting of coal plans and pipelines is outside the scope of the GS rulemaking. 

Rather, the purpose of the GS regulation is to ensure consistency in permitting underground injection of 

CO2 at GS operations across the United States and provide requirements to prevent endangerment of 

USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Comment: Thank you for your efforts to facilitate geologic sequestration. We respectfully 

request your consideration of our comments. 

Commenter Organization: State of Wyoming Comment ID: 22220

Commenter Name: M. Michael Rounds Letter ID: 0159

Commenter Organization: Midwestern Governors Association (MGA) Comment ID: 22225

Commenter Name: M. Michael Rounds Letter ID: 0159

Commenter Organization: Midwestern Governors Association (MGA) Comment ID: 22232

3
Sincerely, 

M. Michael Rounds, Governor of South Dakota and Chair, Midwestern Governors Association 

Jennifer Granholm, Governor of Michigan and Vice Chair, Midwestern Governors Association 

cc: Lee Whitehurst, Office of Ground Water & Drinking Water 

444 North Capitol Street, NW Suite 401 Washington, DC 20001-1512 

Tel:202.624.5460 Fax: 202.624.5452 

Regional Office 701 East 22nd Street Suite 110 

Lombard, Illinois 60148 Tel: 630.925.1922 Fax: 630.925.1930 

www.midwesterngovernors.org 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: It appears that GS of CO2 from fossil-fueled power plants will be a necessary 

part of any national strategy to control green house gas emissions. San Miguel, 

operates coal-fired power plants and these plants are likely to be directly 

affected by new GS regulations. The regulations could have significant financial 

and operational impacts on San Miguel and we ask EPA to carefully consider our 

comments because of the significant stake we have in the outcome of this 

important rulemaking. San Miguel is a member of the National Rural Electric 

Cooperative Association ("NRECA"). NRECA will also be submitting comments on the 

proposed UIC rules. San Miguel supports NRECA’s comments, and incorporates them 

here by reference. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment and NRECA’s comments for further details. For additional information on EPA's final 

regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

EPA agrees that GS is one technology in a portfolio of options, including solar, wind, biomass, and 

geothermal, that could be deployed to reduce CO2 emissions; however these technologies are outside 

the scope of the UIC GS rulemaking. The Class VI GS requirements are designed to ensure consistency 

in permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. 

Other EPA Comment Codes and Descriptions: 5400 2.9 Proposed Financial Responsibility and 

Commenter Name: Joseph Eutizi Letter ID: 0161

Commenter Organization: San Miguel Electric Cooperative, Inc Comment ID: 21282

Commenter Name: James Stine Letter ID: 0163

Commenter Organization: National Rural Electric Cooperative Association 

(NRECA)

Comment ID: 

21318

4
Long-Term Care Requirements 

Comment: Principles for Managing Liability 

NRECA is a member of the Carbon Capture and Storage Alliance (CCS or the 

Alliance) and this group is planning to submit comments on the proposed UIC 

rules for GS of CO2. 

The CCS Alliance is a coalition of entities, spanning a number of economic 

sectors that share a common interest in removing impediments to investment in 

and development of carbon capture and storage ("CCS"), as well as mitigating the 

potential risks associated with the deployment of this technology. Its purpose 

is to promote development of policy by the states and the federal government to 

appropriately address risks and potential liabilities, thereby enabling the 

further development and increased deployment of CCS. The CCS Alliance believes 

these technologies can be developed while protecting underground water 

resources, significantly reducing global and U.S. greenhouse gas ("GHG") 

emissions, and enhancing U.S. energy security. The Alliance’s purpose is to 

consider ways of promoting the development and use of CCS technologies and to 

support efforts by the private sector, states, the federal government, nongovernmental organizations and others, to help ensure that these technologies 

can be developed and widely, efficiently and cost-effectively deployed. 

We support the comments of the Alliance and incorporate them here by reference. 

NRECA is relying on the Alliance and USWAG to provide EPA with specific comments 

on the Financial Assurance and Long Term Liability issues discussed in the 

proposal. We are not experts on these matters, however we do believe that the 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, including 

financial responsibility for GS wells, please see the final rule and preamble as well as the rulemaking 

docket. 

Comment: APPA appreciates the opportunity to comment on this important rulemaking 

initiative and looks forward to working with EPA on this effort. APPA has also 

filed comments on the EPA ANPR in response to many questions that the EPA has 

asked on geologic sequestration. It is critical that the EPA’s air, water and 

policy offices understand that while APPA will offer reasons why geologic 

sequestration should not be presumed to be Clean Air Act technological choices 

under MACT, BACT, LAER, or for NSPS compliance etc., we do strongly want the 

U.S. EPA to have a Class VI regulatory system that would allow for these 

demonstration (and later commercial scale plants) plants. APPA would be pleased 

to meet with the EPA regarding these issues. We would additionally be pleased to 

include in any EPA meeting our partners, the American Water Works Association 

(AWWA) which represents the public and private water utilities who have "front 

line" drinking water protection obligations. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23436

5
the final rule and preamble as well as the rulemaking docket. 

EPA clarifies that technologies considered under Clean Air Act regulations are outside the scope of the 

GS rulemaking. Rather, the purpose of the GS regulation is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Please see the discussion, “How Does This Rulemaking Relate to the Greenhouse Gas (GHG) Reporting 

Program?” in the preamble. 

Comment: It appears that GS of CO2 from fossil-fueled power plants will be a necessary 

part of any national strategy to control green house gas emissions. GRE operates 

coal-fired power plants and these plants are likely to be directly affected by 

new GS regulations. The regulations could have significant financial and 

operational impacts on GRE and we ask EPA to carefully consider our comments 

because of the significant stake we have in the outcome of this important 

rulemaking. GRE is a member of the National Rural Electric Cooperative 

Association ("NRECA") and the Utility Solid Waste Activity Group (USWAG). Both 

groups will also be submitting comments on the proposed UIC rules. GRE supports 

the comments of both NRECA and USWAG, and incorporates them here by reference. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, including 

financial responsibility, please see the final rule and preamble as well as the rulemaking docket. 

EPA agrees that GS is one technology in a portfolio of options, including solar, wind, biomass, and 

geothermal, that could be deployed to reduce CO2 emissions; however, these technologies are outside 

the scope of the UIC GS rulemaking. The Class VI GS requirements are designed to ensure consistency 

in permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. 

Other EPA Comment Codes and Descriptions: 5400 2.9 Proposed Financial Responsibility and 

Long-Term Care Requirements 

Comment: Comments Regarding Liability and Risk Management 

GRE supports the comments of the Carbon Capture and Sequestration Alliance (CCS, 

or the Alliance) on the proposed UIC regulations. The CCS Alliance is a 

coalition of entities, spanning a number of economic sectors, that share a 

common interest in removing impediments to investment in and development of 

carbon capture and storage ("CCS"), as well as mitigating the potential risks 

associated with the deployment of this technology.(Footnote 1) Its purpose is to 

promote development of policy by the states and the federal government to 

appropriately address risks and potential liabilities, thereby enabling the 

further development and increased deployment of CCS. The CCS Alliance believes 

these technologies can be developed while protecting underground water 

Commenter Name: Erik Silvola Letter ID: 0171

Commenter Organization: Great River Energy Comment ID: 23438

Commenter Name: Erik Silvola Letter ID: 0171

Commenter Organization: Great River Energy Comment ID: 23446

6
resources, significantly reducing global and U.S. greenhouse gas ("GHG") 

emissions, and enhancing U.S. energy security. The Alliance’s purpose is to 

consider ways of promoting the development and use of CCS technologies and to 

support efforts by the private sector, states, the federal government, nongovernmental organizations and others, to help ensure that these technologies 

can be developed and widely, efficiently and cost-effectively deployed. 

We support the comments of the Alliance and incorporate them here by reference. 

GRE is relying on NRECA and the Alliance to provide EPA with specific comments 

on the Financial Assurance and Long Term Liability issues discussed in the 

proposal. We are not experts on these issues, however we ask EPA to consider the 

Footnote 1: MidAmerican Energy Holdings Company, National Mining Association, 

National Rural Electric Cooperative Association, NRG Energy, Inc., PacifiCorp 

and Zurich North America. 

Response: The goal of financial responsibility is to ensure that financial resources are available to 

prevent or remediate the endangerment of USDWs from improper plugging, remediation, and 

management of wells in the event that the owner or operator experiences financial difficulties. EPA 

agrees that assuring financial responsibility for corrective action on wells in the AoR, injection well 

plugging, PISC and site closure, and emergency and remedial response at GS sites is an important 

component of ensuring that USDWs are protected. See the final rule and preamble for further discussion 

of EPA's final approach to financial responsibility. 

Please see EPA's responses to the CCS Alliance's comment for additional information. 

Comment: Dominion has participated in the development of industry comments and positions 

with the Edison Electric Institute (EEI) and the Utility Solid Waste Activities 

Group (USWAG), and supports the views expressed therein. Additionally, Dominion 

is a member of the American Gas Association (AGA) and Interstate Natural Gas 

Association of America (INGAA) and shares many of the concerns and opinions of 

these organizations. 

While supportive of the comments of our industry peers and associations, 

Dominion's comments are shaped by several factors unique to Dominion: 

(a) Dominion has substantial coal fired assets in the northeast U.S. where 

geology is less conducive to GS into conventional formations; 

(b) Dominion has extensive underground natural gas storage assets in West 

Virginia, Ohio, Pennsylvania and New York; and, 

(c) Likely target formations for GS in Dominion's regulated territory are 

unmineable coal seams and depleted coal bed methane wells, including enhanced 

gas recovery from coal seams. These target formations, while representing only a 

small fraction of the total US projected storage capacity, are the most viable 

target formation for a signifIcant portion of Dominion's CO2 sources. 

Commenter Name: Pamela Faggert Letter ID: 0175

Commenter Organization: Dominion Comment ID: 23512

7
Response: EPA acknowledges that depleted oil and gas reservoirs associated with ER operations may 

be used for CO2 storage and that these sites may be some of the first sites where commercial-scale GS is 

deployed. The rule clarifies that Class VI requirements apply to any CO2 injection project (regardless of 

formation type) when the purpose of the project is long-term storage. Please see the remainder of EPA's 

responses to this comment, EEI’s comment, AGA’s comment, and USWAG’s comment for further 

details. For additional information on EPA's final regulatory approach please see the final rule and the 

discussion of site-selection criteria and target formations for GS in the preamble as well as the 

rulemaking docket. 

Comment: Representative of our efforts, SSEB manages the Southeast Regional Carbon 

Sequestration Partnership (SECARB), a research program established in 2003 with 

the primary goals of identifying major sources of carbon emissions, 

characterizing the geology of a 13-state region, determining the most promising 

options for commercial deployment of carbon sequestration technologies in the 

South, and validating the technology options through carefully executed field 

testing. SECARB is one of seven regional carbon sequestration partnerships 

nationwide, co-funded by the United States Department of Energy. SECARB’s 

membership is comprised of more than 100 active industry, government, academic, 

and non-profit participants. 

Regarding injection issues, our areas of common interest within the partnership 

include: 

- aquifer exemptions and prohibition on injection above underground sources of 

drinking water (USDWs) (e.g. coal seams); 

- credit for storage in enhanced oil recovery (EOR)-related applications; and 

- transitioning from Class II EOR activities to storage only. 

SSEB offers the following comments, which represent a consensus of thoughts 

shared by many of the SECARB technical partners and stakeholders. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble, including the discussion of aquifer exemptions and the repermitting of Class 

II/EOR wells for GS, as well as the rulemaking docket. 

EPA clarifies that carbon crediting and green house gas accounting are outside the scope of the UIC GS 

rulemaking. The Class VI GS rule is designed to ensure consistency in permitting underground injection 

of CO2 at GS operations across the United States and provide requirements to prevent endangerment of 

USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Comment: The Edison Electric Institute (EEI) [FN1] submits these comments on the 

Environmental Protection Agency (EPA or Agency)‘s proposed regulations for the 

injection and geologic storage (GS) of carbon dioxide (CO2) under the authority 

of the Safe Drinking Water Act (SDWA)'s underground injection control (UIC) 

Commenter Name: Kenneth Nemeth Letter ID: 0176

Commenter Organization: Southern States Energy Board Comment ID: 23534

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23560

8
program, issued in July 2008 (Docket ID No. EPA-HQ-OW-2008-0390), 73 Fed. Reg. 

43492 (July 25, 2008). EEI submitted pre-rulemaking comments to the Agency on 

May 15, 2008, and provided oral and written testimony at EPA‘s September 30, 

2008, public hearing on the proposed rules. These comments and testimony are 

incorporated by reference herein. 

[FN1] EEI is the national association of shareholder-owned electric utilities 

in the U.S. Our members represent about 70 percent of the U.S. electric power 

industry and serve 95 percent of the ultimate customers in the industry‘s 

investor-owned segment. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: With the above general principles in mind, EEI provides below specific comments 

on several aspects of the proposed rules, focusing in particular on the 

following categories of issues: 

- Siting, including the definition of USDW, and secondary containment. 

- AOR and provisions for periodic reevaluation thereof. 

- Monitoring and use of tracers. 

- Closure and post-injection site care. 

- Financial assurance. 

- Grandfathering. 

- Public participation. 

- State primacy. 

- Potential issues relating to the characterization of CO2 and arising under 

other environmental laws. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, including 

site selection criteria, AoR, monitoring, financial responsibility, and state primacy, please see the final 

rule and preamble as well as the rulemaking docket. Also, please see the discussion, “How Does This 

Rulemaking Relate to the Greenhouse Gas (GHG) Reporting Program?” in the preamble. 

Comment: These comments are filed on behalf of the Independent Petroleum Association of 

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23574

Commenter Name: Lee O. Fuller Letter ID: 0179

Commenter Organization: Independent Petroleum Association of America et al. Comment ID: 23609

9
America (IPAA), the International Association of Drilling Contractors (IADC), 

the International Association of Geophysical Contractors (IAGC), the National 

Stripper Well Association (NSWA), the Petroleum Equipment Suppliers Association 

(PESA), the US Oil & Gas Association (USOGA) and the following organizations: 

Arkansas Independent Petroleum and Royalty Owners Association 

California Independent Petroleum Association 

Coalbed Methane Association of Alabama 

Colorado Oil & Gas Association 

East Texas Producers & Royalty Owners Association 

Eastern Kansas Oil & Gas Association 

Florida Independent Petroleum Association 

Illinois Oil & Gas Association 

Independent Oil & Gas Association of New York 

Independent Oil & Gas Association of Pennsylvania 

Independent Oil & Gas Association of West Virginia 

Independent Oil Producers Agency 

Independent Oil Producers Association Tri-State 

Independent Petroleum Association of Mountain States 

Independent Petroleum Association of New Mexico 

Indiana Oil & Gas Association 

Kansas Independent Oil & Gas Association 

Kentucky Oil & Gas Association 

Louisiana Independent Oil & Gas Association 

Michigan Oil & Gas Association 

Mississippi Independent Producers & Royalty Association 

Montana Petroleum Association 

National Association of Royalty Owners 

Nebraska Independent Oil & Gas Association 

New Mexico Oil & Gas Association 

New York State Oil Producers Association 

North Dakota Petroleum Council 

Northern Alliance of Independent Producers 

Ohio Oil & Gas Association 

Oklahoma Independent Petroleum Association 

Panhandle Producers & Royalty Owners Association 

Pennsylvania Oil & Gas Association 

Permian Basin Petroleum Association 

Petroleum Association of Wyoming 

Southeastern Ohio Oil & Gas Association 

Tennessee Oil & Gas Association 

Texas Alliance of Energy Producers 

Texas Independent Producers and Royalty Owners Association 

Virginia Oil and Gas Association 

Wyoming Independent Producers Association 

Collectively, these groups represent the thousands of independent oil and 

natural gas explorers and producers that will be the most significantly affected 

by the proposed actions in these regulatory actions. Independent producers have 

the knowhow to drill and complete wells to depths beneath America’s USDWs. They 

drill about 90 percent of American oil and natural gas wells, produce over 65 

10
percent of American oil, and more than 80 percent of American natural gas. 

In addition to the specific comments made herein, we support those comments 

submitted separately by the participants in these comments. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: The proposed Class VI regulations represent an important step in ensuring that 

USDWs are protected during geological carbon sequestration operations. Clearly, 

very significant efforts have been made, and input has been received on many 

issues to craft the draft regulations. The comment process now underway offers 

an important opportunity to review the proposed regulations and address 

specifics that remain to be dealt with. With respect to suggested modifications, 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: APS would like to go on record voicing its support of the USWAG comments and 

urge EPA to carefully consider USWAG's comments as it develops this program. In 

particular, APS would like to emphasize the following points, which are 

discussed in detail in the USWAG comments together with comments on several 

other key issues associated with the proposal. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment and USWAG’s comment for further details. For additional information on EPA's final 

regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: NiSource would also like to make the point that we support the comments made on 

the behalf of natural gas utility members by the American Gas Association (AGA). 

In particular, we would like to echo the AGA's concerns regarding the protection 

of geologic natural gas storage. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment and AGA’s comments for further details. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23616

Commenter Name: Scott Davis Letter ID: 0187

Commenter Organization: Arizona Public Service Company Comment ID: 25219

Commenter Name: Daniel Plath Letter ID: 0188

Commenter Organization: NiSource, Inc. Comment ID: 25227

Commenter Name: G. Graham Holden Letter ID: 0189

Commenter Organization: Oglethorpe Power Corporation Comment ID: 25241

11
Comment: will also be submitting comments on the proposed UIC rules. Oglethorpe Power 

supports NRECA’s comments, and through this document incorporates those comments 

by reference. 

We support the comments of the CCS Alliance and incorporate them here by 

reference. In addition, Oglethorpe Power defers to NRECA and the CCS Alliance to 

provide EPA with specific comments on the Financial Assurance and Long Term 

Liability issues discussed in the proposal. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment, CCS Alliance’s comment, and NRECA’s comment for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: CSC has participated in the development of the multi-stakeholder discussion 

(MSD) process leading to the submission of a joint letter to EPA. We join the 

other participants in expressing our appreciation for EPA’s extension of the 

public comment period that allowed us to make substantial progress in expanding 

our shared understanding on the relevant issues and to reach significant 

agreement on how these issues can be addressed and resolved by EPA. CSC supports 

all of the recommendations presented in that letter, which are submitted with 

the request that the recommendations be considered as a whole because the 

recommendations were developed in combination to accurately reflect our shared 

understanding. 

In addition, we are committed to continuing the MSD process and to inviting 

others to participate with an objective of developing additional specific 

recommendations for improvement of a final rule that could be adopted by EPA’s 

scheduled date in late 2010 or early 2011, including development of the 

requirements to be applied to oil and gas reservoir geologic sequestration that 

is not conducted in conjunction with enhanced oil and gas production operations. 

We will be working with the other MSD participants toward submission of 

additional recommendations by February 28, 2009. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this letter 

and those of other participants of the MSD process for further details. For additional information on 

EPA's final regulatory approach, including involving the public in permitting decisions, please see the 

final rule and preamble as well as the rulemaking docket. 

Comment: In addition to the Multi-Stakeholder Discussion Group mentioned above, 

ConocoPhillips has formulated our specific perspective on EPA rulemaking working 

with organizations including the American Petroleum Institute, the CO2 Capture 

and Storage (CCS) Contact Group (VanVoorhees/Bryan Cave). We support the 

consensus of these groups, taken in their entirety. Our company's comments 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24314

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23886

12
Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment, American Petroleum Institute’s comment, and CCS’s comment for further details. For 

additional information on EPA's final regulatory approach, please see the final rule and preamble as well 

as the rulemaking docket. 

Comment: this sneaky kind of document from american electric power is the type of 

document that should not be accepted by this agency at all for publi comment. 

since it is NOT public comment. it attempts to do an end run around open 

goverment. i very much believe this agency needs a new policy of destroying any 

letters sent like this that are secret. obviously this profiteer does not want the 

public to know the sneaky stuff they are proposing. i think that is not open govt or 

democratic at all. start a policy with this document of denying such 

communications at all. if it isnt public, it should not be accepted as a comment. 

sneaky company -its disgusting to try to close govt. 

Response: EPA addresses all comments received. Some information submitted, such as copyrighted 

material, is not placed on the Internet and will be publicly available only in hard copy form. Publicly 

available docket materials are available either electronically through www.regulations.gov or in hard 

copy at the OW Docket, EPA/DC, EPA West, Room 3334, 1301 Constitution Ave., NW, Washington, 

DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding 

legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the 

telephone number for the OW Docket is (202) 566-2426. 

Comment: we just had a big scandal in nj where the lab that tests the water was lying on est 

results. how does the public protect itself from that. it is clear that some system 

needs to be set up to check the labs which need watching since they obviousy 

are turning in fake water health reports. 

Response: EPA clarifies that the regulation of drinking water laboratories is outside the scope of the GS 

rulemaking. Rather, the purpose of the GS regulation is to ensure consistency in permitting underground 

injection of CO2 at GS operations across the United States and provide requirements to prevent 

endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Comment: Ameren is a member of the Utility Solid Waste Activities Group ("USWAG"), the 

Edison Electric Institute ("EEI"), and the Electric Power Research Institute 

("EPRI)". We endorse the comments filed by USWAG, EEI, and EPRI. In addition, I 

provided oral and written testimony on behalf of USWAG at EPA’s October 2, 2008, 

public hearing on the proposed rules 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment, USWAG’s comment, EEI’s comment, and EPRI’s comment for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble as well as the 

Commenter Name: Anonymous5 Letter ID: 0194

Comment ID: 23918

Commenter Name: Anonymous6 Letter ID: 0195

Comment ID: 23919

Commenter Name: Paul Pike Letter ID: 0198

Commenter Organization: Ameren Corporation Comment ID: 23937

13
rulemaking docket. 

Comment: Southern Company submits these comments on the Proposal of the Environmental 

Protection Agency ("EPA" or "the Agency") to establish a regulatory framework 

for geologic sequestration ("GS") of carbon dioxide ("C02") under the 

Underground Injection Control ("UIC") Program pursuant to the Safe Drinking 

Water Act ("SDWA"). 73 Fed. Reg. 43492 (July 25, 2008). [FN1 Southern Company 

also endorses the comments filed on this Proposal by the Utility Solid Waste 

Activities Group, Edison Electric Institute, and the Carbon Sequestration 

Council Carbon Capture and Sequestration Contact Group.] Southern Company (NYSE: 

SO) is a super-regional energy company with more than 42,000 megawatts of 

electric generating capacity in the Southeast. Southern Company is one of the 

largest producers of electricity in the country, supplying energy to a 120,000- 

square mile service territory spanning most of Georgia and Alabama, southeastern 

Mississippi, and the panhandle region of Florida and serving nearly 4.4 million 

customers. Southern Company is ranked number 166 on the latest Fortune 500 

listing of the largest United States corporations, with approximately 26,000 

employees and reported earnings in 2007 of $1.73 billion. Southern Company owns 

four regulated retail electric utilities: Georgia Power, Alabama Power, Gulf 

Power, and Mississippi Power. 

In addition, Southern Company is a leader in environmental research. Through 

2007, Southern Company has invested approximately $4.6 billion in environmental 

controls and plans to spend an additional $3.9 billion through 2010 to further 

reduce emissions. Southern Company is committed to the deployment of a variety 

of energy sources including renewable energy. Southern Company has already begun 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this letter 

for further details. For additional information on EPA's final regulatory approach, please see the final 

rule and preamble as well as the rulemaking docket. 

Comment: In addition to the following comments, Duke Energy supports the comments 

submitted by the Utility Solid Waste Activities Group, the Edison Electric 

Institute, the Electric Power Research Institute, and the Gasification 

Technologies Council. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment and USWAG’s comment, Edison Electric Institute’s comment, Electric Power Research 

Institute’s comment, and the Gasification Technologies Council comment for further details. For 

additional information on EPA's final regulatory approach, please see the final rule and preamble as well 

as the rulemaking docket. 

Commenter Name: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22152

Commenter Name: Michael Stroben Letter ID: 0209

Commenter Organization: Duke Energy Comment ID: 22678

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 23041

14
Comment: Regulatory Group (USWAG). Tampa Electric endorses the comments filed by EEI and 

USWAG in this docket. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment, USWAG’s comment, and Edison Electric Institute’s comment for further details. For 

additional information on EPA's final regulatory approach, please see the final rule and preamble as well 

as the rulemaking docket. 

Comment: NDEP also supports the comments submitted by the Association of State Drinking 

Water Administrators. Thank you for the opportunity to comment on this proposed 

rule. If you need any additional information, please contact me. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment and ASDWA’s comment for further details. For additional information on EPA's final 

regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: Our comments address the following important topics: (A) Enhanced Oil Recovery 

or Enhanced Gas Recovery ("EOR/EGR") and CO2 Storage; (B) Wells, Monitoring & 

Operations; (C) Site Closure Period; and (D) Financial Assurance. HEI further 

joins in the comments submitted by the American Petroleum Institute. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment and API’s comments for further details. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble, including Class II/EOR wells, testing and monitoring, 

operating requirements, post-injection site care, site closure, and financial assurance, as well as the 

rulemaking docket. 

Comment: Significantly, this technology does not start on a blank slate. The Oil & Gas 

industry has extensive, relevant experience with injection into the subsurface 

that can inform this rulemaking. Moreover, BP is a leader in studies and 

demonstration projects conducted around the world regarding geologic 

sequestration of CO2. The comments submitted here are in large measure based 

upon this significant experience and technical knowledge. We would be pleased 

to review our comments and/or any questions that EPA may have regarding our 

comments at EPA’s convenience. HEI also welcomes the opportunity to provide 

additional information or input to EPA as EPA continues its evaluation and study 

of comments, scientific papers/studies or other information submitted or 

considered in this rulemaking process. 

Response: EPA acknowledges the comment. EPA recognizes that the oil and gas industry has decades 

of experience injecting CO2 for the purpose of EOR. The GS rulemaking builds upon existing

Commenter Name: Jonathon Palm Letter ID: 0222

Commenter Organization: Nevada Division of Environmental Protection, Bureau of

Water Pollution Control

Comment ID: 

21645

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21649

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21703

15
experience and knowledge about safe injection practices in EOR and other injection industries, with 

tailored requirements that address the unique nature of CO2 injection for GS. 

Please see the remainder of EPA's responses to this comment for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble, including the 

discussion of the repermitting of Class II EOR wells for GS, as well as the rulemaking docket. 

Comment: Significantly, this technology does not start on a blank slate. The Oil & Gas 

industry has extensive, relevant experience with injection into the subsurface 

that can inform this rulemaking. Moreover, BP is a leader in studies and 

demonstration projects conducted around the world regarding geologic 

sequestration of CO2. The comments submitted here are in large measure based 

upon BP’s significant experience and technical knowledge. We would be pleased to 

review our comments and/or any questions that EPA may have regarding our 

comments at EPA’s convenience. BP also welcomes the opportunity to provide 

additional information or input to EPA as EPA continues its evaluation and study 

of comments, scientific papers/studies or other information submitted or 

considered in this rulemaking process. 

Response: EPA recognizes that the oil and gas industry has decades of experience injecting CO2 for the 

purpose of EOR. The GS rulemaking builds upon existing experience and knowledge about safe 

injection practices in EOR and other injection industries, with tailored requirements that address the 

unique nature of CO2 injection for GS. 

EPA acknowledges the comment. Please see the remainder of EPA's responses to this comment for 

further details. For additional information on EPA's final regulatory approach, please see the final rule 

and preamble, including the discussion of the repermitting of Class II EOR wells for GS, as well as the 

rulemaking docket. 

Comment: Gas storage fields in the United States can be divided into two major types: 

porous rock reservoirs and salt caverns. Gas storage has been developed in many 

of the major sedimentary basins throughout the U.S. Because many of the areas 

and geologic formations considered for GS will be in the same basins and will 

occur in the geologic section either above, below, or in some cases, within the 

same formation as natural gas storage fields, there is a potential for natural 

gas storage fields to be directly or indirectly impacted by GS. Gas storage is 

a very important part of natural gas supply in the U.S., because it provides up 

to 50% of the winter heating season peak consumption of 50 Bcf per day to 

residential and commercial customers when there is typically not enough flowing 

capacity in pipelines to meet the winter surge in demand. 

We ask EPA to address the potential impacts on gas storage operations in 

crafting the final rule with respect to the following issues. 

Response: EPA clarifies that the Class VI requirements apply only to wells that are injecting CO2 into 

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21764

Commenter Name: Pamela A. Lacey Letter ID: 0228

Commenter Organization: American Gas Association Comment ID: 21802

16
the subsurface for the purpose of GS, and not to natural gas storage operations, and that natural gas 

storage operations are out of the scope of the UIC program's authority. 

Please see the remainder of EPA's responses to this comment for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: Id. at 49 (citing NAS, Prospective Evaluation). We offer the foregoing comments 

in an effort to help ensure the safety and effectiveness of geologic carbon 

sequestration when it is located in or near natural gas storage fields, and to 

ensure that the interaction of the GS well and the natural gas storage field 

does not pose a threat to underground sources of drinking water. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1852 1.4.2.1 DOE Regional Carbon Sequestration 

Partnerships 

Comment: Introduction and Background 

This document summarizes review and comments from Battelle researchers’ under 

he regulatory work of Midwest Regional Carbon Sequestration Partnership’s 

(MRCSP) on the USEPA Proposed Rule- Federal Requirements under UIC Program for 

CO2 Geologic Sequestration Wells (Docket ID No. EPA-HQ-OW2008-390). These 

comments reflect our experience in permitting and implementing three Phase II 

CO2 injection tests and the MRCSP Phase III project, as well as work on several 

other research projects during last 12 years of CCS research at Battelle: 

Table [see PDF Docket ID EPA-HQ-OW-2008-390-0229.1] 

The analysis also reflects Battelle experience with the UIC permitting of the 

AEP Mountaineer CO2 storage project, which is targeting 4 years of injection of 

over 100,000 metric tons CO2/yr at the AEP Mountaineer plant in New Haven, WV. 

While the MRCSP includes over 30 different members, the comments expressed 

herein do not necessarily reflect opinions of the individual members of the 

MRCSP. 

The MRCSP is one of seven partnerships in a nationwide effort to determine 

regionally-appropriate carbon sequestration options and opportunities. These 

partnerships are part of an overall effort by the U.S. Department of Energy’s 

National Energy Technology Laboratory (DOE/NETL) to develop robust strategies 

for mitigating carbon dioxide emissions. The MRCSP was formed to assess the 

technical potential, economic viability, and public acceptability of carbon 

sequestration within its Region. 

Commenter Name: Pamela A. Lacey Letter ID: 0228

Commenter Organization: American Gas Association Comment ID: 21808

Commenter Name: Neeraj Gupta Letter ID: 0229

Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21809

17
The MRCSP region consists of eight contiguous states: Indiana, Kentucky, 

Maryland, Michigan, New York, Ohio, Pennsylvania, and West Virginia. The MRCSP 

includes over 30 organizations from the research community, energy industry, 

universities, non-government, and government organizations. In the first phase 

of research, which took place over a two year period ending in September 2005, 

the MRCSP characterized carbon sequestration opportunities in the region. MRCSP 

is now involved in a four year Phase II effort that began in October 2005. This 

phase will conduct several small-scale field tests of sequestration in different 

locations around the region to evaluate various sequestration options in realworld settings. The MRCSP Phase III project will involve sequestration of more 

than 1 million metric tons CO2. 

Response: EPA acknowledges the value of the DOE pilot projects and resultant data and information 

generated by such projects. EPA has evaluated permits and reviewed operational data and information 

associated with the seven RCSPs funded by the U.S. Department of Energy and coordinated through the 

National Energy Technology Laboratory (NETL). In addition to the information cited in the preamble to 

the proposed rule, EPA published a Notice of Data Availability and Request for Comment on August 31, 

2009 (74 FR 44802), in which the Agency described the results of research at three DOE partnership 

sites: the Escatawpa, Mississippi project; the Aneth Field project in Paradox Basin, Southeast Utah; and 

the Pump Canyon Site, New Mexico. The Agency will continue to track GS project developments and 

evaluate new and ongoing research and information to ensure USDW protection, including those 

performed by the MRCSP. 

EPA is using an adaptive approach to regulating GS under the UIC Program. Even after finalizing the 

rule, the Agency plans to collect and review data every six years on GS projects, including data 

generated by the partnerships, to determine whether the appropriate amount and types of information 

and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. 

Comment: Enhanced oil recovery offers the potential to vastly expand domestic crude oil 

reserves and production, while simultaneously providing a positive answer to CO2 

emissions based on a commercial, value added sequestration solution. Carbon 

dioxide injection into mature oil fields is a proven oil recovery method that 

has been safely and successfully utilized for 35 years. In fact CO2 EOR was 

growing in the U.S. even before the recent crude oil price run-up, when oil was 

selling for $20 per barrel. The technique now accounts for about 4% of U.S. oil 

production. 

Crude oil production has been declining in the U.S. since the early 1970’s (see 

Figure 1 below). Current production is about 5.2 million barrels per day 

(excluding natural gas condensates and other liquid by-products). Leading 

experts estimate that an additional 3.0 million daily barrels per day of 

American crude can be produced using CO2, ultimately increasing domestic oil 

output by more than 50%. As an indicator of this potential, CO2 EOR has already 

stimulated rising oil production in Mississippi and Wyoming, where adequate, low 

cost sources of CO2 have been available to support growth. Unfortunately, there 

are substantial CO2 shortages in most U.S. oil basins that constrain the growth 

Commenter Name: A. James Mayer Letter ID: 0230

Commenter Organization: A. J. Mayer International on behalf of the American 

Energy Security Initiative

Comment ID: 

21871

18
of CO2 EOR. The prospect of capturing and utilizing additional and substantial 

low cost CO2 supplies from the gasification of American coal, petroleum coke, 

municipal solid waste, and biomass represents the ultimate economic and 

environmental leveraging of our strategic domestic energy resources. 

Gasification clearly offers a "next generation" in energy efficiency, emissions 

control, and fuel and chemical product manufacturing flexibility. Gasification 

plants can be configured to make one or a portfolio of transportation fuels, 

chemicals, fertilizers, natural gas substitutes, and electricity, while at the 

same time capturing a large percentage of CO2 generated by the processes. These 

large new CO2 product streams represent a valuable commodity that can be 

utilized to restore the vitality of many of America’s mature oil fields, 

facilitating a rapid increase in domestic production from stranded oil (as 

described below), and substantial economic and national security benefits. 

Figure 1: US Oil Production Has Been Declining Since 1970 

[see PDF Docket ID EPA-HQ-OW-2008-0390-0230] 

The United States has Vast EOR Potential that is Geographically Diverse 

In terms of resource base, the U.S. CO2 EOR "prize" is tremendous, with 

technically recoverable reserves estimated at more than 88 billion additional 

barrels of oil from declining oil fields (see the attached Department of Energy 

fact sheet) in ten major basins. [SEE EPA-HQ-OW-2008-0390-0230.PDF FOR FACT 

SHEETS] In addition, experts are currently assessing another tremendous CO2 EOR 

target--a new class of virgin oil resources being referred to as "residual oil 

zones" or "transition zones." Residual oil zones ("ROZs") are untapped oilbearing geologic units beneath some main pay zones from which the easy oil has 

been displaced by natural underground water movement over the geological past (a 

process analogous to oil industry water flooding, also know as secondary 

recovery). CO2 injection (tertiary recovery) into ROZs is a promising method to 

mobilize enough of the remaining "stranded oil" to justify development of a 

number of these formations. 

Although somewhat difficult to quantify at this early stage, residual oil zone 

resources are believed to be in the billions of barrels, offering the potential 

to significantly increase the 88+ billion barrel CO2 EOR reserve base (see the 

attached DOE fact sheet for more details). Several very significant commercial 

residual oil zone projects are already in production in the U.S., including an 

operation at the Hess Seminole Field and one at Occidental Petroleum’s Wasson 

field - both in West Texas. Other fields with substantial ROZ resources await 

CO2 availability for exploitation. The total EOR prize is believed to total or 

exceed 100 billion barrels of oil, including existing commercial oil reservoirs 

and new residual oil zones. 

For comparative purposes, ANWR represents approximately 10.4 billion barrels of 

technically recoverable oil, with an estimated production potential of about 1.4 

million barrels per day. In contrast, U.S. CO2 EOR offers the potential to add 

almost three times the daily production of ANWR, and 10+ times the oil reserves, 

while at the same time creating very large markets and geologic sequestration 

"sinks" for billions of tons of CO2. 

19
The graphic below (Figure 2) is a simplified diagram of the CO2 EOR process. In 

commercial operations carbon dioxide is transported under pressure to the 

project area by pipeline in what the industry refers to as the CO2 dense phase. 

The compressed CO2 is then sent underground into a targeted underground oil "pay 

zone" through injector wells where it acts as a solvent reducing the oil 

viscosity and surface tension, thus freeing the oil to be "swept" to production 

wells. A CO2 injection well is typically surrounded by a number of production 

wells organized in a "pattern". Any CO2 produced with the oil is separated and 

reinjected. The CO2 that is not recycled is effectively trapped within the 

formation in dead-end pores and channels. When the EOR project is complete all 

wells are plugged with cement and the CO2 is permanently sequestered 

underground. 

In current practices, the amount of CO2 injected to mobilize oil is carefully 

controlled due to the cost of the CO2. The yield of a CO2 EOR project typically 

varies from two to four barrels of oil produced from every ton of CO2 purchased. 

CO2 EOR has not seen wider application because of the high project capital 

costs, historically low oil prices, and limited supplies of low cost, pure CO2. 

But in today’s high oil price environment, the main constraint is a shortage of 

CO2. Enhanced oil recovery operators are currently paying between $10 and $30 

per ton for CO2, when they can find it. The market is there. The challenge is to 

provide incentives for more CO2 generators to capture their carbon dioxide 

streams, and developers to build CO2 pipelines from CO2 sources to the oil and 

methane fields that need it. Today’s supplies of CO2 are a combination of 

naturally occurring deposits tapped by underground wells and man made 

("anthropgenic") sources captured from some natural gas processing, coal 

gasification, ethanol production, and other operations. 

Figure 2: Enhanced Oil Recovery Process with CO2 Injection 

[see PDF Docket ID EPA-HQ-OW-2008-0390-0230] 

Other emerging carbon dioxide application/sequestration technologies are also 

worth mentioning. These include the enhanced production of natural gas, coalbed 

methane, and agricultural products (including algae for fuel production) with 

CO2. These and other technologies promise to create additional markets for CO2 

but require more research and development efforts to reach commercial viability. 

In contrast, CO2 Enhanced Oil Recovery is already commercial and can be quickly 

expanded. 

Rapid expansion of Enhanced Oil Recovery provides an excellent foundation from 

which to advance American Energy Security, stimulate and grow the economy, and 

protect the environment. This can and should be followed by the rapid 

development and deployment of other productive uses of CO2, to enhance natural 

gas, algae growth for biofuels, etc. Conversely, the current focus on the 

passive, costly sequestration of CO2 in deep saline formations will increase the 

price of all U.S. energy products and thus impose a significant burden on our 

economy and our society. 

Commercial sequestration will enable the next generation of domestic energy 

production. CO2 occurs naturally in the subsurface and it is no stranger to 

geologists who attempt to understand fluid migration and subsurface 

20
accumulations. The fact that CO2 can be trapped in subsurface formations for 

geologic times is known and accepted; and we will undoubtedly find more of these 

locations. Oil and gas "traps" are considered by recognized petroleum engineers 

and geologist to be excellent final resting place for CO2. These traps have 

already demonstrated the ability to hold oil and gas safely undergroud for 

hundreds of millions of years. 

Response: EPA recognizes that the oil and gas industry has decades of experience injecting CO2 for the 

purpose of EOR. The GS rulemaking builds upon existing experience and knowledge about safe 

injection practices in EOR and other injection industries, with tailored requirements that address the 

unique nature of CO2 injection for GS. 

The Agency clarifies that the final GS rule does not require owners or operators to use GS technologies, 

nor does it impact business as usual for Class II owners or operators that are injecting CO2 to enhance 

production of oil or gas. Those owners or operators that choose to transition from enhanced recovery to 

GS may do so, provided they meet the requirements for Class VI wells. EPA adds that the intent of the 

GS rule is not to address the deployment of GS or the use of CO2 for ER. Rather, the purpose of the GS 

regulation is to ensure consistency in permitting underground injection of CO2 at GS operations across 

the United States and provide requirements to prevent endangerment of USDWs in anticipation of the 

eventual use of GS to reduce CO2 emissions. 

Please see the remainder of EPA's responses to this comment letter for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble, including the 

discussion of the repermitting of Class II EOR wells for GS, as well as the rulemaking docket. 

Comment: 2. We generally agree with and endorse the Texas Carbon Capture and Storage 

Association (TxCCSA) comments to the Proposed Rule. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter and TxCCSA’s comment letter for further details. For additional information on EPA's 

final regulatory approach, please see the final rule and preamble, as well as the rulemaking docket. 

Comment: Re: Docket ID No. EPA-HQ-OW-2008-0390 (Proposed Federal Requirements Under the 

Underground Injection Control Program for Carbon Dioxide Geologic Sequestration 

Wells) 

The Oil and Gas Conservation Division of the Oklahoma Corporation Commission 

regulates oil and gas exploration and production activities and administers the 

Class II Underground Injection Control (UIC) program in the State of Oklahoma. 

The division has followed the stakeholder discussions concerning the referenced 

proposal with keen interest, particularly regarding those portions of the 

proposal that may affect the management and regulation of the states oil and 

gas resources. 

Commenter Name: A. James Mayer Letter ID: 0230

Commenter Organization: A. J. Mayer International on behalf of the American 

Energy Security Initiative

Comment ID: 

21873

Commenter Name: Lori Wrotenbery Letter ID: 0247

Commenter Organization: Oklahoma Corporation Commission Comment ID: 22233

21
Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble, including the discussion of the repermitting of Class II EOR wells for 

GS, as well as the rulemaking docket. 

Comment: To Whom Concerns: 

On July 25, 2008, the Environmental Protection Agency (EPA) published in the 

Federal Register, a proposed rule setting forth new requirements under the Safe 

Drinking Water Act (SDWA) for the underground injection of carbon dioxide (CO2) 

for the purpose of long-term storage, or geologic sequestration (GS). The 

regulation is proposed under the authority of the SDWA to ensure protection of 

underground sources of drinking water from injection related activities. EPA 

views the capture and injection of CO2 produced by human activities for longterm storage as one of a portfolio of options that can reduce CO2 emissions into 

the atmosphere and help mitigate climate change. 

WEST Associates (Western Energy Supply and Transmission Associates, or "WEST") 

respectfully submits its comments and recommendations, herein. 

WEST Associates is comprised of 16 investor and publicly owned electric 

utilities serving the rapidly growing 11 western states and North Dakota. In 

recent years, WEST Associates has worked with other stakeholders to advocate 

development of environmental laws and regulations that are based on sound 

science and achieve state and national environmental goals in a rational and 

cost effective manner. WEST Associates’ members own and operate coal and gasfired electric generating facilities and are also involved in the planning and 

development of additional new electric generating facilities. 

WEST Associates Policy Comments: 

WEST’s comments on this rulemaking address EPA’s proposed Alternative 3 which 

would create a new class of injection wells (Class VI) and proposes minimum 

technical criteria for geologic site characterization, fluid movement, area of 

review (AoR) and corrective action, well construction, operation, mechanical 

integrity testing, monitoring, well plugging, post injection site-care, and site 

closure for the purposes of protecting underground sources of drinking water 

(USDWs). The proposal is based on the existing Underground Injection Control 

(UIC) regulatory framework, with modifications to address the unique nature of 

CO2 injection for GS. WEST's comments set forth several policy level concerns 

and recommendations, followed by some comments and recommendations concerning 

the specific aspects of the proposed rulemaking. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble, including sections on site characterization, AoR, construction, operation, 

testing and monitoring, and site closure, as well as the rulemaking docket. 

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission Associates Comment ID: 22237

22
Comment: WEST Associates sincerely appreciates this opportunity to comment and provide 

recommendations on EPA’s proposed rule regarding UIC for CO2 Geological 

Sequestration. 

Should you have any questions or need further information, please do not 

hesitate to contact David Steele at (520) 321-1111. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble as well as the rulemaking docket. 

Comment: I am writing, on behalf of the multi-sector membership of the Western Business 

Roundtable (the "Roundtable"), in response to the Environmental Protection 

Agency’s (the "Agency’s") request for public comments regarding its proposed 

rulemaking to implement federal requirements under the Safe Drinking Water Act 

("SDWA") Underground Injection Control (UIC) Program for carbon dioxide (CO2) 

geologic sequestration wells (73 Federal Register 43492, August 28, 2008). 

The whole issue of CO2 management has tremendous macro-economic, 

consumerpocketbook, environmental and national security implications. Extensive 

Congressionaland regulatory reviews are underway regarding the efficacy of 

mandatory carbon regulations. A necessary predicate to any such regime must be a 

clear understanding of: 

“ The effectiveness of sequestration and storage options; 

“ Hurdles to the efficient implementation of those options; 

“ CO2 transportation system challenges; and 

“ Liability issues associated with both transportation and storage of CO2. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

EPA clarifies that climate change policy, evaluating the barriers to CO2 storage, and CO2 transport are 

outside the scope of the GS rulemaking. Rather, the purpose of the GS regulation is to ensure 

consistency in permitting underground injection of CO2 at GS operations across the United States and 

provide requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to 

reduce CO2 emissions. 

Comment: The Western Business Roundtable is a broad-based coalition of companies doing 

business inthe Western United States. Our members are engaged in a wide array of 

enterprises, including: manufacturing; retail energy sales; mining; electric 

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission Associates Comment ID: 22251

Commenter Name: James T. Sims Letter ID: 0249

Commenter Organization: Western Business Roundtable Comment ID: 22253

Commenter Name: James T. Sims Letter ID: 0249

Commenter Organization: Western Business Roundtable Comment ID: 22256

23
power generation and transmission; energy infrastructure development; and oil 

and gas exploration, development, transportation and distribution. We work to 

defend the interests of the West and support policies that encourage economic 

growth and opportunity, freedom of enterprise and a common-sense, balanced 

approach to conservation and environmental stewardship. 

Most of our members are centrally involved in the development, transportation 

and processing of a wide variety of energy resources -- fossil, renewable and 

nuclear -- as well as the generation and distribution of electricity across the 

West and technologies that facilitate greater energy conservation and 

efficiency. Roundtable members also are on the cutting edge of technology 

development related to the management of CO2 emissions. 

I hope you will find the broad perspective and expertise reflected in this 

letter helpful as the Agency moves forward with its deliberations on this 

important policy issue. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble, as well as the rulemaking docket. 

Comment: CONCLUSION 

On behalf of the many member organizations of the Western Business Roundtable, 

thank you for the opportunity to provide our input on this crucially important 

public policy issue, the implications of which are so pivotal to the continued 

vitality of the West. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this letter 

for further details. 

Comment: We therefore are pleased to submit these comments on EPA’s proposed rules 

concerning "Federal Requirements Under the Underground Injection Control (UIC) 

Program for Carbon Dioxide (CO2) Geologic Sequestration (GS) Wells, 73 Fed. 

Reg.43492 (July 28, 2008). 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: F. Conclusion 

Commenter Name: James T. Sims Letter ID: 0249

Commenter Organization: Western Business Roundtable Comment ID: 22268

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22276

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22328

24
Our Environmental NGO Group appreciates the opportunity to provide comments to 

EPA on this most important rulemaking effort. A final rule will represent a 

significant step forward in combating global climate change, and the time is 

more than ripe for the U.S. to take such steps. When EPA issues its final rule, 

we feel it must be both technically sound and adaptive to reflect learning from 

experience with GS projects in as seamless a manner as is possible. We very much 

look forward to continuing to work with the Agency on this rule, as well as 

other efforts under the Agency’s existing authority to address the significant 

problem of climate change in the near term. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble as well as the rulemaking docket. 

Comment: Comments of: 

Clean Air Task Force 

Clean Water Action 

Environmental Defense Fund 

Natural Resources Defense Council 

Western Resource Advocates 

A. Introduction 

The Clean Air Task Force, Clean Water Action, Environmental Defense Fund, 

Natural Resources Defense Council, and Western Resource Advocates (Environmental 

NGO Group) thank EPA for the opportunity to comment on the Proposed Rule on 

carbon dioxide sequestration wells under the Underground Injection Control (UIC) 

Program. 

Founded in 1996, the Clean Air Task Force (CATF) is a nonprofit organization 

dedicated to restoring clean air and healthy environments through scientific 

research, public education, and legal advocacy. 

Founded in 1972, Clean Water Action (CWA) has 1.2 million members and offices in 

20 states. Clean Water Action works to improve public health and environmental 

protection through grassroots organizing, policy research and advocacy. 

Environmental Defense Fund (EDF), founded in 1967, is a non-profit organization 

that represents more than 500,000 members. EDF links science, economics and law 

to create innovative, equitable and cost-effective solutions to society’s most 

urgent environmental problems. 

The Natural Resources Defense Council (NRDC) is a national, nonprofit 

organization of scientists, lawyers and environmental specialists dedicated to 

protecting public health and the environment. Founded in 1970, NRDC has more 

than 1.2 million members and online activists nationwide, served from offices in 

New York, Washington D.C., San Francisco, Los Angeles, Chicago and Beijing. 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 24726

25
Western Resource Advocates (WRA) is a regional non-profit organization using 

law, economics and policy analysis to protect the land, air and water of the 

Interior Western United States. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter as well as the comments of EDF, and NRDC for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: General Comments 

While CCGS is only one technology in a portfolio of many that will need to be 

implemented to achieve carbon emissions stabilization, it is most amenable to 

mitigating the emissions from large stationary CO2 sources, particularly carbonbased fossil fuel power plants which account for nearly 80% of the cumulative 

total CO2 emissions from large stationary sources (IPCC, 2005). Furthermore, 

CCGS has been identified as the critical enabling technology for reducing CO2 

emissions significantly while allowing the use of carbon-based fossil fuels, 

especially coal, to meet the world's energy demands (The Future of Coal, 2007). 

Meeting carbon emissions stabilization goals will be more easily achieved if 

mitigative measures are implemented sooner rather than later. Therefore, while 

the enabling CCGS legal and regulatory framework must provide for the protection 

of ground water and other natural resources, it must not contain elements that 

would hinder the timely deployment of commercial scale CCGS projects. 

Response: EPA acknowledges the comment. EPA agrees that GS is one technology in a portfolio of 

options, including solar, wind, biomass, and geothermal, that could be deployed to reduce CO2 

emissions; however these technologies are outside the scope of the UIC GS rulemaking. EPA clarifies 

that the GS regulation does not promote or encourage the use of GS; rather it is designed to ensure 

consistency in permitting underground injection of CO2 at GS operations across the United States and 

provide requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to 

reduce CO2 emissions. EPA clarifies that mitigating climate change is outside the scope of the GS 

rulemaking. Please see the remainder of EPA's responses to this comment for further details. For 

additional information on EPA's final regulatory approach, please see the final rule and preamble as well 

as the rulemaking docket. 

Comment: 

Specific Comments on Topics 

In the preamble to the proposed rule, EPA asked for comments on approximately 50 

topics. Following are our comments on some of those topics. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Commenter Name: Walter L. Baker Letter ID: 0253

Commenter Organization: Utah Division of Water Quality Comment ID: 22337

Commenter Name: Walter L. Baker Letter ID: 0253

Commenter Organization: Utah Division of Water Quality Comment ID: 22340

26
Comment: References Cited Federal Actions Will Greatly Affect the Viability of Carbon 

Capture and Storage As a Key Mitigation Option, Report to the Chairman of the 

Select Committee on Energy Independence and Global Warming, House of 

Representatives, U.S. Government Accountability Office (GAO), September, 2008. 

IPCC, 2005: IPCC Special Report on Carbon Dioxide Capture and Storage. Prepared 

by Working Group III of the Intergovernmental Panel on Climate Change [Metz, B., 

O.Davidson, H.C. de Coninck, M. Loos, and L.A. Meyer (eds.)]. Cambridge 

University Press, Cambridge, United Kingdom and New York, NY, USA, 442 pp. 

The Future of Coal: Options for a Carbon-Constrained World, An Interdisciplinary 

MIT Study, 2007 

IOGCC. 2007. Storage of Carbon Dioxide in Geologic Structures; A Legal and 

Regulatory Guide for States and Provinces. Prepared by the Interstate Oil and 

Gas Compact Commission. September 25, 2007. 

The Liability of Carbon Dioxide Storage, Mark Anthony de Figueiredo, MIT Ph.D 

Thesis, February 2007. 

Response: PA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: Discussion 

Our remarks focus on the following areas: (1) location of CO2 injection (a.k.a. 

"Siting"); (2) liability under RCRA and CERCLA; (3) post closure care; and (4) 

dual purpose wells and grandfathering of certain Class II wells. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach (including 

site characterization, post-injection site care, and the repermitting of Class II/EOR wells for GS), please 

see the final rule and preamble as well as the rulemaking docket. 

Comment: Conclusion 

The Foundation appreciates EPA's initiative to commence this rulemaking to 

provide regulatory clarity for GS of CO2 and welcomes this and future 

opportunities to provide input on the project. We respectfully request that EPA 

Commenter Name: Walter L. Baker Letter ID: 0253

Commenter Organization: Utah Division of Water Quality Comment ID: 22357

Commenter Name: Mike Nasi Letter ID: 0254

Commenter Organization: Clean Coal Technology Foundation of Texas Comment ID: 22361

Commenter Name: Mike Nasi Letter ID: 0254

Commenter Organization: Clean Coal Technology Foundation of Texas Comment ID: 22368

27
carefully consider the comments set out above as the final rule and preamble are 

prepared. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: Introduction & Background 

The Clean Coal Technology Foundation of Texas ("CCTF" or "Foundation") 

appreciates the opportunity to submit comments to the U.S. Environmental 

Protection Agency ("EPA") regarding the proposed Federal requirements for 

underground injection of carbon dioxide ("CO2") for the purpose of geologic 

sequestration ("GS"). The Foundation was founded in January, 2004, as a nonprofit entity to support the mission of the Governor's Clean Coal Technology 

Council (Council). The Foundation exists to promote the use and development of 

clean coal technologies that will result in reliable, low cost, and 

environmentally responsible energy for Texas. 

The Foundation views the regulatory framework that will govern CO2 GS as one of 

the key bridges on the road to widespread carbon capture because project 

developers will not be willing to take the financial and technology risk 

associated with CO2 capture if they do not see a storage option that is free of 

regulatory pitfalls. The regulatory regime governing CO2 GS could stand in the 

way of widespread carbon capture if it is perceived as confusing, too 

bureaucratic, or structured in a way that creates undue risk of statutory 

environmental liability. The comments that follow are focused on the aspects of 

the proposed rules that the Foundation believes could impair our efforts to 

speed the commercialization of carbon capture technology. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

EPA clarifies that the intent of the GS rule is not to promote or encourage the use of GS; rather, its 

purpose is to ensure consistency in permitting underground injection of CO2 at GS operations across the 

United States and provide requirements to prevent endangerment of USDWs in anticipation of the 

eventual use of GS to reduce CO2 emissions. 

Other EPA Comment Codes and Descriptions: 1200 1.1 General comments about the rulemaking 

Comment: In conclusion, ExxonMobil is committed to working with the EPA individually 

and through the API and other groups to develop scientifically sound, 

performance based regulations for the geologic storage of C02. Each of the areas 

of concern we have identified are more fully addressed in API's comments. 

Commenter Name: Mike Nasi Letter ID: 0254

Commenter Organization: Clean Coal Technology Foundation of Texas Comment ID: 24728

Commenter Name: Ken Miller Letter ID: 0257

Commenter Organization: ExxonMobil Production Company Comment ID: 22371

28
Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment and API’s comment for further details. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: To Whom It May Concern: 

ExxonMobil Production Company (a Division of ExxonMobil Corporation) appreciates 

the opportunity to submit comments on the Environmental Protection Agency's (EPA) 

proposed rules for Geologic Storage of Carbon Dioxide (GS) under the Safe 

Drinking Water Act (SDWA) Underground Injection Control Program. Exxon Mobil 

Corporation is a fully integrated oil and gas company with world-wide operations. 

Exxon Mobil Corporation has significant experience in operations directly related 

to geologic storage such as carbon dioxide (CO2) based enhanced oil recovery 

(EOR), separation of CO2 from natural gas streams, acid gas injection, geologic 

imaging and modeling, injection well integrity management, as well as an 

industry leading research and development program which includes carbon 

management technologies. 

ExxonMobil would like to compliment the EPA on the open and transparent process 

they have followed in developing these draft rules. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: The NAM appreciates the opportunity to comment on this proposal. Manufacturers 

look forward to working with federal officials to craft a comprehensive 

framework that will promote the commercial viability of CCS. For more 

information related to the NAM’s position on CCS technology, please contact 

Bryan Brendle at (202) 637-3176. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

EPA clarifies that the intent of the GS rule is not to promote or encourage the use of GS; rather, its 

purpose is to ensure consistency in permitting underground injection of CO2 at GS operations across the 

United States and provide requirements to prevent endangerment of USDWs in anticipation of the 

eventual use of GS to reduce CO2 emissions. 

Comment: Rule Provision: Part 144 

Commenter Name: Ken Miller Letter ID: 0257

Commenter Organization: ExxonMobil Production Company Comment ID: 24729

Commenter Name: Keith McCoy Letter ID: 0258

Commenter Organization: National Association of Manufacturers Comment ID: 22376

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24831

29
EPA Proposal:1. The authority citation for part 144 continues to read as 

follows: 

Authority: 42 U.S.C. 300f et seq.; Resource Conservation and Recovery Act, 42 

U.S.C. 6901 et seq. 

GWPC Recommendations: No comment necessary 

Response: EPA acknowledges the comment. The final rule retains this text. 

Comment: The IPCC's 2005 report on "Carbon Capture and Storage" notes that mature 

sedimentary basins such as the Williston Basin in the upper Great Plains are 

"prime targets for CO2 storage because: (1) they have well-known 

characteristics; (2) hydrocarbon pools and/or coal beds have been discovered and 

produced; (3) some petroleum reservoirs might be already depleted, nearing 

depletion or abandoned as uneconomic without advanced production systems such as 

EOR: (4) the infrastructure needed for CO2 transport and injection may already be 

in place." [FN1] Use of CO2 for EOR often adds an additional 7-23% of incremental oil 

recovery from a field, and depleted oil fields have advantages for CO2 

sequestration because "the oil and gas that originally accumulated in traps 

(structural and stratigraphic) did not escape (in some cases for many millions 

of years), demonstrating their integrity and safety," and because "the 

geological structure and physical properties of most oil and gas fields have 

been extensively studied and characterized." [FN2] IPCC's 2005 "Carbon Capture and 

Storage" Report also recognizes that Basin Electric's DGC/Weyburn project, 

"despite the presence of many hundreds of existing wells, after four years of 

CO2 injection there has been no measurable leakage (Strutt et al., 2003)."[FN3] 

Thus, EOR is an established option for CO2 sequestration in the Williston Basin, 

and geological formations are holding sequestered CO2 without leakage. There is 

an identified need for additional CO2 for EOR in the Williston Basin when the 

technology becomes mature enough to provide it at a reasonable cost to 

customers. Basin Electric's AVS Post-Combustion CO2 Capture Project is an 

attempt to move that technology forward. 

In addition to EOR options, saline aquifers have been identified in the 

Mississippian Madison geological formation of the Williston Basin with the 

capacity to store approximately 60 gigatons (i.e., 60 billion tons) of CO2, 

which is enough capacity, for example, to store all of the CO2 emitted from a 

facility emitting 3 million tons of CO2 per year for 20,000 years. 

IPCC's 2005 report on "Carbon Capture and Storage" also says that most scenarios 

project that the supply of primary energy used by humans will continue to be 

dominated by fossil fuels until the middle of the 21st-century.[FN4] The IPCC 

notes that stabilizing CO2 levels in the atmosphere will not likely be achieved 

with a single technological option, but CO2 capture and storage (CCS) in 

geological formations is one of the most important technologies that may make 

such stabilization possible" [FN5] 

Commenter Name: Claire Olson Letter ID: 0260

Commenter Organization: Basin Electric Power Cooperative Comment ID: 22384

30
"[T]he global capacity to store CO2 deep underground is large. Depleted oil and 

gas reservoirs are estimated to have a storage capacity of 675-900 [metric 

gigatons of] CO2. Deep saline formations are very likely to have a storage 

capacity of at least 1000 [metric gigatons of] CO2 and some studies suggest it 

may be an order of magnitude greater than this, but quantification of the upper 

range is difficult until additional studies are undertaken."[FN6] 

The IPCC "Carbon Capture and Storage" Report acknowledges that natural 

underground accumulation of CO2 is "a widespread geological phenomenon," and 

that '[w]hile there are differences between natural accumulations and engineered 

storage, injecting CO2 into deep geological formations at carefully selected 

sites can store it underground for long periods of time: it is considered likely 

that 99% or more of the injected CO2 will be retained for 1000 years."[FN7] 

Response: EPA acknowledges the comment. EPA reviewed the IPCC report, as well as more recent 

information on GS and Carbon Capture and Storage while developing the final GS rule. Please see the 

remainder of EPA's responses to this letter for further details. For additional information on EPA's final 

regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: IV. Comments on Identified Issues 

The following comments are directed to the specific questions raised in the 

proposed rule. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this letter 

for further details. For additional information on EPA's final regulatory approach, please see the final 

rule and preamble as well as the rulemaking docket. 

Comment: In an effort to reduce possible duplicate comments, we have reviewed the 

comments prepared by industry groups to which we belong and agree generally with 

the conclusions and approach of those comments. Those groups are as follows : 

Carbon Capture and Storage Alliance 

FutureGen Industrial Alliance 

Coal Utilization Research Council 

Gasification Technologies Council 

North American Caron Capture and Storage Association 

Western Business Roundtable 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter and response to comments from the Carbon Capture and Storage Alliance, FutureGen 

Industrial Alliance, Coal Utilization Research Council, Gasification Technologies Council, North 

American Carbon Capture and Storage Association, and Western Business Roundtable for further 

details. For additional information on EPA's final regulatory approach, please see the final rule and 

preamble as well as the rulemaking docket. 

Commenter Name: Claire Olson Letter ID: 0260

Commenter Organization: Basin Electric Power Cooperative Comment ID: 22387

Commenter Name: Dianna Tickner Letter ID: 0262

Commenter Organization: Peabody Energy Comment ID: 22994

31
Comment: Metropolitan appreciates this opportunity to provide comment and asks that EPA 

carefully consider these comments as well as those by AWWA and other drinking 

water concerns. Please contact me at (213) 217-5696 if you have any questions, 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter and AWWA’s comment for further details. For additional information on EPA's final 

regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: Fasken Oil and Ranch, Ltd. has reviewed the Western Business Roundtable's 

comments concerning these proposed regulations and fully supports their 

comments. Any questions concerning our comments can be directed to me at the 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment and Western Business Roundtable’s comment for further details. For additional information on 

EPA's final regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: [FN:1] The recommendations presented in this letter reflect a consensus among 

the signatories on the specific issues addressed; however, some of the 

signatories note that their participation should not be interpreted as an 

express or implied change in views on other issues that may be related to the 

issues addressed. In particular, CATF, EDF and NRDC reserve the respective views 

they have expressed regarding the appropriate legal authority for the rule, the 

definition of geologic sequestration, and necessary requirements needed if 

injection is to be allowed above the lowermost underground source of drinking 

water (see comments to EPA dated December 24, 2008 and letters dated March 17, 

2009). 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter and responses to comments from CATF, EDF, and NRDC for further details. For 

additional information on EPA's final regulatory approach, please see the final rule and preamble as well 

as the rulemaking docket. 

Comment: The organizations identified below request that the Environmental Protection 

Agency (EPA) extend from November 24, 2008 to December 19,2008 the public 

comment period on the proposed rule for geologic sequestration of carbon dioxide 

under the Safe Drinking Water Act (SDWA). "Federal Requirements Under the 

Underground Injection Control (UIC) Program for Carbon Dioxide (C02) Geologic 

Sequestration (GS) Wells", 73 Fed. Reg. 43491-541 July 25, 2008). The 

Commenter Name: Mic Stewart Letter ID: 0279

Commenter Organization: Metropolitan Water District of Southern California Comment ID: 24096

Commenter Name: Jimmy Carlile Letter ID: 0281

Commenter Organization: Fasken Oil & Ranch Comment ID: 24115

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25305

Commenter Name: Kyle Isakower Letter ID: 0298

Commenter Organization: American Petroleum Institute Comment ID: 29317

32
organizations supporting this request represent a broad array of interests in 

the issues associated with this rulemaking and many of us have been discussing 

these interests and issues in an effort to reach consensus or at least narrow 

our differences. We request this extension so we can continue efforts toward 

submission of recommendations reflecting common views on a number of the major 

issues in this rulemaking on which EPA expressly requested comment and several 

other issues that have arisen during our dialogue on this rulemaking. 

Initially facilitated by EPA's technical workshops to develop understanding and 

helpful public meetings to discuss EPA's rulemaking approach, our discussions 

have been enhanced by the efforts of the Ground Water Protection Council, the 

Interstate Oil and Gas Compact Commission and the World Resources Institute, in 

which many of our organizations have participated. They have been further 

informed by the ongoing research efforts of the Regional Carbon Sequestration 

Partnerships under the support of the Department of Energy and a number of other 

research activities and meetings conducted by academic and other institutions 

actively involved in technical research and information exchanges on the issues 

underlying this rulemaking, in which representatives or members of our 

organizations have participated. As a result of EPA's proposal, dialogue on 

these issues has expanded, become more focused and achieved substantial progress 

in reaching agreement on a number of issues that should better inform EPA's 

development of its final rule. 

We have already agreed that EPA's proposal provides a solid foundation on which 

to develop the regulatory framework for geologic sequestration on issues within 

the purview of the SDWA and that development of this rule should proceed with 

EPA's proposal as the starting point. The issues on which we believe additional 

time would be helpful to development of common views or understanding include: 

- The establishment of injection pressure limitations for geologic sequestration 

injection wells; 

- How various types of target formations should be addressed within the underground 

injection control (UIC) program, including requirements for geologic sequestration 

in oil and gas reservoirs; 

- The process and criteria for achieving closure of geologic sequestration projects; 

- Consideration of current and potential future source waters in areas with constrained 

water resources; and 

- Addressing issues relating to public water systems in proximity to geologic 

sequestration projects. 

We believe that the requested limited extension of the public comment period 

will allow time for continuation of diligent efforts to reach consolidation of 

shared understanding on these issues and possibly submission of recommendations 

reflecting that understanding and significant agreement on how these issues can 

be addressed and resolved. The undersigned submit this request on behalf of the 

listed organizations that have authorized submission of their names as 

supporters of this request. 

33
Response: Robert F. Van Voorhees 

Partner, Environmental Group 

Bryan Cave LLP 

700 Thirteenth Street, N.W. 

Suite 700 

Washington, D.C. 20005-3960 

Dear Mr. Van Voorhees: 

Thank you for your letter of November 17,2008 to Stephen L. Johnson, 

Administrator of the U.S. Environmental Protection Agency (EPA), transmitting a 

request from multiple organizations seeking an extension on EPA's proposed rule for 

geologic sequestration under the Safe Drinking Water Act (SDWA). I have been asked 

to respond to your letter. 

In response to your request, Assistant Administrator Benjamin Grumbles 

extended the comment period for the notice through December 24,2008. This was 

announced in a Federal Register notice on November 21,2008. 

We are pleased to see that the signatory organizations to the letter are working 

together to understand each other's perspective and work through issues of concern. We 

hope that the additional time afforded by the extension will result in comments that will 

help the Agency develop a rule that will allow the technology to move forward while also 

ensuring protection of underground sources of drinking water. 

Thank you again for your letter. Please share this information with the supporters 

of the request. If you have any questions, please contact me or Steve Heare, Director of 

the Drinking Water Protection Division, at 202-564-3751. 

Sincerely, 

Cynthia C. Dougherty, Director 

Office of Ground Water and Drinking Water 

Comment Code: 1200 1.1 General comments about the rulemaking 

Individual Comments 

Comment: The EPA’s proposed rule to regulate CO2 injection pursuant to the Safe Drinking 

Water Act is well researched and thorough, and contains important technical 

review and information for the effective storage and regulation of storage 

facilities for CO2 streams. This rulemaking will thus provide important 

regulatory consistency for CO2 capture, injection, and storage, which will in 

Commenter Name: Victor B. Flatt Letter ID: 0103

Commenter Organization: The Center of Environment, Energy & Natural Resources 

Law (EENR Center), University of Houston Law Center

Comment ID: 

22489

34
turn facilitate further and more efficient deployment of CCS technologies and 

projects. 

Response: EPA acknowledges the comment. The purpose of the rule is to ensure consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. Please see the remainder of EPA's responses to this comment for further details. For 

additional information on EPA's final regulatory approach, please see the final rule and preamble as well 

as the rulemaking docket. 

Comment: CIBO notes generally that the proposed rule raises many questions for facilities 

that are potentially regulated under this rule. In fact, it is unclear from the 

proposal what facilities may be regulated directly and even more unclear what 

facilities may ultimately shoulder some liability for the obligations outlined 

in the proposal. Throughout the proposal EPA identifies significant areas 

Response: EPA clarifies that the GS rule applies to owners or operators of wells that will be used to 

inject CO2 into the subsurface for the purpose of long-term storage. 

Please see the remainder of EPA's responses to this comment for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: - Page 43497 under what are the "Potential USDW Impacts." Please consider adding 

at the very end of this section a sentence that reaffirms for the reader that 

the fundamental purpose of the proposed Class VI rule is to make sure that the 

bad things above enumerated do not occur. 

- Page 43502, third sentence under "How Would this Proposal Affect Existing 

Injection Wells Under the UIC Program?" Please consider being specific as to 

what kind of "production" is being discussed here. From the context of this 

sentence it would seem to be "production of oil" or perhaps "production of 

hydrocarbons" but it would not seem to cover "production of brackish waters for 

the purpose of desalination to provide potable water." The phrase "any 

production seems overly vauge. 

- Page 43505 within the discussion of CO2 storage in coal seams. It is 

incorrect to state that "the process of CO2 adsorption to the coal has not been 

proven." This is well established. I think what USEPA intended to say was 

something like "the commercial application of coal-based CO2 storage has not 

been proven." The fundamental principle of CO2 adsorbing on the coal surface is 

established. Whether this is going to work in situ and at commercial scale has 

not been established / proven. Please consider rewording. 

Commenter Name: Robert Bessette Letter ID: 0139

Commenter Organization: Council of Industrial Boiler Owners (CIBO) Comment ID: 23079

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific 

Northwest National Laboratory

Comment ID: 

22674

35
- Page 43516. "Simulations discussed in the manual confirm seismic and - What 

- manual"? It is not clear what is being discussed here. 

Response: In response to the comment regarding production, EPA clarifies that this discussion refers to 

Class II wells, which are associated with the recovery of oil and or gas. The purpose of the discussion is 

to distinguish injection (which is regulated under the UIC regulations) from production (which is not). 

In response to the comment regarding CO2 adsorption to the coal, EPA clarifies that GS in unmineable 

coal seams has been the subject of less research than saline formations or depleted oil and gas reservoirs. 

EPA acknowledges that site-suitability for GS is dependent on a number of factors and that many 

formation types may be suitable for GS. The final GS rule does not preclude injection into unmineable 

coal seams (or any formation type) provided owners or operators can demonstrate that GS can be 

performed in a manner that protects USDWs from endangerment. The Agency anticipates that in the 

near-term, most GS in unmineable coal seams will continue to be experimental. Such projects may be 

permitted as Class V experimental technology wells if they are of an experimental nature (i.e., to test GS 

technologies and collect data). 

The "manual" referenced on page 43516 is the GEO-SEQ Best Practices Manual. Geologic Carbon 

Dioxide Sequestration: Site Evaluation to Implementation. Lawrence Berkeley National Laboratory. 

Paper LBNL-56623. The GEO-SEQ Best Practices Manual is available at: 

http://www.netl.doe.gov/technologies/carbon_seq/refshelf/GEO-SEQ_BestPract_Rev1-1.pdf. 

Please see the remainder of EPA's responses to this comment for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: Concern #12: EPA's schedule for promulgation of its proposed UIC regulation 

(Page 43499 Sec. E3) 

We reference the following statement from the preamble section of the proposed 

rule : "During the Deployment Phase (2008-2017), the [RCSP] partnerships will 

conduct large volume carbon storage tests to demonstrate that large-scale CO2 

injection and storage can be achieved safely and economically. EPA will use the 

data collected from these projects to support decisions in the final GS rule." 

This statement suggests that a final GS rule may not be issued until 2017. We 

believe that this is too late to clear the regulatory uncertainty that CCS 

project developers are facing today. If this reflects EPA's intention, we 

recommend that EPA abandon a prescriptive approach and instead, favor general 

and performance- based requirements until these demonstration tests are 

completed. 

Response: EPA believes that sufficient data have been collected to inform the final GS rule. 

Nevertheless, EPA anticipates that future experimental and full-scale projects will continue to inform the 

technology, and is therefore using an adaptive rulemaking approach. EPA plans, every six years, to 

collect and review data on GS projects to determine whether the appropriate amount and types of 

information and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. 

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23767

36
Other EPA Comment Codes and Descriptions: 5400 2.9 Proposed Financial Responsibility and 

Long-Term Care Requirements 

Comment: SUMMARY 

San Miguel applauds the efforts EPA has taken thus far to instill "certainty" 

and "transparency" into the future Class VI CO2 regulatory regime, 73 Fed. Reg. 

at 43496. The challenge EPA faces is to craft a Final Rule for commercial CO2 

injection appropriate for activities that will largely be conducted in the 

future. EPA has had to confront many technical uncertainties regarding the 

establishment and operation of GS wells. Because many of the technical aspects 

are unknown, it is also very difficult to develop a clear understanding of 

project risks and liabilities. As long as risks and liabilities are largely 

unknown and open-ended, private companies will not step forward to offer 

insurance and other risk management products, and it will not be possible to 

obtain the level of financing needed to undertake a costly GS operation. We hope 

the pilot carbon capture and sequestration (CCS) projects conducted by DOE and 

other entities will help resolve some of these uncertainties. 

Response: To address concerns about certainty, EPA has specified acceptable financial responsibility 

instruments and requirements in the final regulation at §146.85. Additionally, EPA is developing 

guidance (available on EPA's website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm) that describes the types of financial 

instruments that owners or operators can use to meet financial responsibility requirements for GS wells. 

EPA adds that it anticipates that, as GS is deployed, particularly if there are early successful uses of 

these financial instruments, owners or operators will demand and carriers will offer third-party GS 

financial instruments in greater numbers. See the final rule and preamble for further discussion of EPA's 

final approach to financial responsibility. 

Other EPA Comment Codes and Descriptions: 5400 2.9 Proposed Financial Responsibility and 

Long-Term Care Requirements 

Comment: SUMMARY 

NRECA applauds the efforts EPA has taken thus far to instill "certainty" and 

"transparency" into the future Class VI CO2 regulatory regime. 73 Fed. Reg. at 

43496. The obvious challenge confronting EPA is to craft a Final Rule for 

commercial CO2 injection activities when large-scale commercial operations are 

only at the nascent stage. In the process of developing regulations for 

activities that will largely be conducted in the future, EPA has had to confront 

many technical uncertainties regarding the establishment and operation of GS 

wells. Because many of the technical aspects are unknown, it is also very 

difficult to develop a clear understanding of project risks and liabilities. As 

long as risks and liabilities are largely unknown and open-ended, private 

companies will not step forward to offer insurance and other risk management 

products, and it will not be possible to obtain the level of financing needed to 

Commenter Name: Joseph Eutizi Letter ID: 0161

Commenter Organization: San Miguel Electric Cooperative, Inc Comment ID: 21283

Commenter Name: James Stine Letter ID: 0163

Commenter Organization: National Rural Electric Cooperative Association 

(NRECA)

Comment ID: 

21311

37
undertake a costly GS operation. 

Response: To address concerns about certainty, EPA has specified acceptable financial responsibility 

instruments and requirements in the final regulation at §146.85. Additionally, EPA is developing 

guidance (available on EPA's website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm) that describes the types of financial 

instruments that owners or operators can use to meet financial responsibility requirements for GS wells. 

EPA anticipates that the availability of third-party GS financial instruments will grow in response to 

demand for such instruments by GS well owners or operators as deployment of GS technology increases 

in the future. In addition, EPA plans to allow owners or operators to choose from a variety of financial 

instruments to meet their financial responsibility needs, thereby allowing owners or operators flexibility. 

See the final rule and preamble for further discussion of EPA's final approach to financial responsibility. 

EPA is using an adaptive approach to regulating GS. 

Comment: 4. APPA strongly encourages the EPA to recognize the inextricable link between 

energy and water use. Water demand for power production remains intense, and may 

grow concurrently with demand growth and population growth. APPA recommends the 

Desalination and Water Purification Technology Roadmap developed by Sandia 

National Labs in 2003 as a summary of the water-energy issues. [FN2] 

[FN2] This document can be downloaded at 

http://www.sandia.gov/water/desal/docs/DesalRdmap04a.pdf 

Response: EPA clarifies that the linkage of water and energy issues is outside the scope of the GS 

rulemaking; the purpose of the GS regulation is to ensure consistency in permitting underground 

injection of CO2 at GS operations across the United States and provide requirements to prevent 

endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Other EPA Comment Codes and Descriptions: 1435 1.2.1.3 EPA should develop guidance 

Comment: EPA asked for comments on financial guidance on any aspect of the final rule 

(for example, clarification of requirements for financial assurance mechanisms). 

APPA thinks that this might be an area where the EPA might call for a "second 

bite at the apple" after we know more from the preliminary carbon sequestration 

projects and "scaling up" projects. We agree with Utility Solid Waste Activities 

Group (USWAG) and others who have suggested that that guidance must be developed 

in accordance with OMB’s Good Guidance Practices Bulletin, which directs that 

notice and comment be provided for the development of "significant" and 

"economically significant" guidance documents. 

Response: The GS rule contains minimum technical criteria for the permitting, geologic site 

characterization, AoR and corrective action, well construction, operation, mechanical integrity testing, 

monitoring, financial responsibility, injection well plugging, post-injection site care, and site closure of 

GS wells, which will ensure that USDWs are protected from endangerment. 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23376

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23395

38
To promote consistency while providing the Director with an appropriate level of discretion, EPA is 

developing guidances for states and tribes that describe the process of applying for and receiving 

primacy for GS Class VI wells under Section 1422 of SDWA, as well as the technical and administrative 

issues associated with developing GS regulations that are the equivalent of minimum federal criteria and 

requirements. These are available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA intends to take OMB’s Good Guidance Manual into consideration as financial responsibility 

guidance is developed. OMB’s Good Guidance Manual establishes policies and procedures for the 

development, issuance, and use of significant guidance documents by Executive Branch departments 

and agencies. 

EPA agrees that an adaptive and flexible approach is appropriate. To protect USDWs from 

endangerment and meet the potentially fast pace of GS deployment, EPA is using an adaptive approach 

to regulating CO2 injection for GS. The Agency plans to, every six years, collect and review data on GS 

projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. An adaptive approach will allow regulatory development to proceed in time to meet the 

current and future demands for Class VI permits while EPA continues to gather data from pilot projects 

and other research as it becomes available. 

Comment: API commends EPA on their effort in drafting rules for the long-term storage of 

carbon dioxide. API is very supportive of the fact that EPA has recognized the 

integrity of the existing regulatory framework for CO2-based enhanced oil and gas 

recovery, of EPA's recognition that storage may occur during activities 

conducted under a Class II permit without requiring the well to obtain a Class VI permit, of the amount 

of flexibility 

operators have in meeting the requirements in most parts of the proposed rule, 

and of the use of performance-based standards aimed at protecting underground 

sources of drinking water (USDWs). 

API also appreciated EPA extending the comment period. During that time, API has 

Response: EPA acknowledges the comment. EPA recognizes that the oil and gas industry has decades 

of experience injecting CO2 for the purpose of EOR. The GS rulemaking builds upon existing 

experience and knowledge about safe injection practices in EOR and other injection industries, with 

tailored requirements that address the unique nature of CO2 injection for GS. Please see the remainder 

of EPA's responses to this comment for further details. For additional information on EPA's final 

regulatory approach, please see the final rule and preamble, including the discussion of the repermitting 

of Class II EOR wells for GS, as well as the rulemaking docket. 

Comment: GRE applauds the efforts EPA has taken thus far to instill "certainty" and 

"transparency" into the future Class VI CO2 regulatory regime, 73 Fed. Reg. at 

43496. The challenge EPA faces is to craft a Final Rule for commercial CO2 

injection appropriate for activities that will largely be conducted in the 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24117

Commenter Name: Erik Silvola Letter ID: 0171

Commenter Organization: Great River Energy Comment ID: 23439

39
future. EPA has had to confront many technical uncertainties regarding the 

establishment and operation of GS wells. Because many of the technical aspects 

are unknown, it is also very difficult to develop a clear understanding of 

project risks and liabilities. As long as risks and liabilities are largely 

unknown and open-ended, private companies will not step forward to offer 

insurance and other risk management products, and it will not be possible to 

obtain the level of financing needed to undertake a costly GS operation. We hope 

the pilot carbon capture and sequestration (CCS) projects conducted by DOE and 

other entities will help resolve some of these uncertainties. 

EPA needs to establish clear, reasonable regulations that are environmentally 

protective and cover a range of operations for which the technology will not be 

commercially deployed for a number of years. To the extent practicable, EPA 

needs to establish a single, clear, reasonable and protective liability regime 

for an activity where the nature of the risks are different from many other 

industrial activities and the full extent of possible risks from full scale CSS 

operations are presently unknown. 

Response: EPA agrees that flexibility is important for GS projects. The GS rule requires owners or 

operators to submit, and Directors to consider, extensive site-specific data, specified at §146.82, to 

demonstrate that a site is suitable for GS. Additionally, many of the permit requirements for GS wells 

are established through individualized site-specific plans for AoR and corrective action, testing and 

monitoring, and injection well plugging and post-injection site care and site closure. EPA adds that the 

final GS rule includes a balance of specific criteria to be met by the owner or operator and areas of 

Director discretion. The Agency believes this balance allows for GS projects to be designed and 

permitted to address the unique, site-specific aspects of each project, while providing consistency in 

permitting across the U.S. 

Please see the remainder of EPA's responses to this comment for further details. For additional 

information on EPA's final regulatory approach, including the adaptive rulemaking approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: • While directorial discretion is a useful mechanism to ensure flexibility in 

the Final Rule, such discretion must be clearly defined and limited. 

Response: To promote consistency while providing the Director with an appropriate level of discretion, 

EPA is developing guidances for States, Tribes, and Territories that describe the process of applying for 

and receiving primacy for GS Class VI wells under Section 1422 of SDWA. EPA is also developing 

guidance on the technical and administrative issues associated with developing GS regulations that are 

the equivalent of minimum federal criteria and requirements. This guidance will be available on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. Please see the remainder 

of EPA's responses to this comment for further details. For additional information on EPA's final 

regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: With that being said, this rulemaking can resolve some important policy and 

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23467

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23472

40
legal issues and, in doing so, help foster the development of a practical, 

commercially deployable CCS regulatory program. For example, the Final Rule can 

provide much needed clarity regarding (1) the potential for liability under RCRA 

and CERCLA resulting from CO2 injection and GS activities, and (2) the options 

for addressing long-term liability for Class VI wells. GAO Report 

at 39-42. As discussed below, there are practical regulatory and legislative 

options available to resolve these uncertainties that will help assure the 

public and the regulated community that CO2 UIC activities can be conducted in a 

manner that is both safe and effective. 

Response: Please see the remainder of EPA's responses to this comment for further details. For 

additional information on EPA's final regulatory approach, please see the final rule and preamble, 

including the discussions of RCRA/CERCLA and long-term liability, as well as the rulemaking docket. 

Comment: Promotion of CCS 

The Agency rightly acknowledges that CCS is a key climate change mitigation 

technology, and the proposed rules should support its development. The UIC rules 

should be designed to facilitate, and not hinder, the successful commercial 

scale deployment of CCS. As such the rulemaking necessitates a host of 

regulatory approaches: recognition that early adopters are likely to be EOR 

operators; grandfathering of existing wells which facilitates development of GS 

wells; appropriate characterization of CO2 and potential risks; avoidance of 

unnecessary stigmatization of GS; a recognition of the diversity of target 

formations (including especially unmineable coal seam formations); an 

appreciation for the consequences of public perception; avoidance of one-size 

fits-all approaches; and regulatory certainty through limits and guidelines to 

Directors' discretion. Furthermore, a successful CCS regime requires the 

avoidance of conflicts to the extent possible. Accordingly, GS should be 

promoted at sites where it has minimal risk to other uses of underground 

formations, such as natural gas storage. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

EPA clarifies that the intent of the GS rule is not to promote or encourage the use of GS; rather, its 

purpose is to ensure consistency in permitting underground injection of CO2 at GS operations across the 

United States and provide requirements to prevent endangerment of USDWs in anticipation of the 

eventual use of GS to reduce CO2 emissions. 

Comment: The potential environmental benefits of deploying CCS technologies, in terms of 

avoided or sequestered CO2 emissions, should be weighed against potential 

requirements that might delay or compromise the ability to achieve commercialscale CCS. Key issues include balancing state and federal interests, 

Commenter Name: Pamela Faggert Letter ID: 0175

Commenter Organization: Dominion Comment ID: 23514

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23550

41
appropriate characterization of CO2, appropriate risk management approaches and 

maintaining needed flexibility. To this end, EEI has provided comments on nine 

areas of concern, briefly summarized below. 

Response: Please see the remainder of EPA's responses to this comment for further details. For 

additional information on EPA's final regulatory approach, please see the final rule and preamble, 

including site selection criteria, emergency and remedial response, and the adaptive rulemaking 

approach, as well as the rulemaking docket. 

EPA clarifies that the intent of the GS rule is not to promote or encourage the use of GS; rather, its 

purpose is to ensure consistency in permitting underground injection of CO2 at GS operations across the 

United States and provide requirements to prevent endangerment of USDWs in anticipation of the 

eventual use of GS to reduce CO2 emissions. 

Other EPA Comment Codes and Descriptions: 1330 1.1.3.1 Support use of GS in general 

Comment: EEI's views are guided by several general principles applicable to any federal 

legislative or regulatory effort on CCS, which are described below and discussed 

more fully in the context of specific comments: 

1. Promotion of CCS. As EPA acknowledges in the preamble, CCS is a key climate 

change mitigation technology, and the proposed rules are intended to support its 

development.[FN2] Likewise, any EPA regulatory regime related to CCS developed 

under the authority of SDWA (or any other statute) should be designed to 

facilitate, and not unduly hinder, the successful commercial-scale deployment of 

CCS. The potential environmental benefits of such deployment in terms of 

reduced or avoided GHG emissions should be weighed against potential 

requirements that might delay or compromise the ability to achieve commercialscale CCS. Issues the Agency should consider in connection with this principle 

include: 

[FN2] 73 Fed. Reg. 43495, col.1. 

Response: EPA clarifies that the intent of the GS rule is not to promote or encourage the use of GS; 

rather, its purpose is to ensure consistency in permitting underground injection of CO2 at GS operations 

across the United States and provide requirements to prevent endangerment of USDWs in anticipation of

the eventual use of GS to reduce CO2 emissions. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: a. Reasonable regulatory approaches. Regulations proposed for injection and 

storage should be carefully tailored to fit injection and storage projects and 

the true nature of the risks that they may pose, but should not be unduly 

burdensome for the regulated community. In particular, the following issues 

Response: EPA believes that the final GS rule includes a balance of specific criteria to be met by the 

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23562

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23563

42
owner or operator and areas of Director discretion. The Agency believes this balance allows for GS 

projects to be designed and permitted to address the unique, site-specific aspects of each project, while 

providing consistency in permitting across the U.S. 

Other EPA Comment Codes and Descriptions: 1400 1.2 Comments on EPA's Authority to Regulate 

Injection of CO2 

Comment: 5. Anticipation of related developments. On the other hand, the Agency should 

strive to anticipate future statutory and regulatory developments in the climate 

change arena so that any rulemaking has a reasonable chance of melding with such 

developments. For instance, while it is clear that SDWA does not authorize the 

Agency to develop rules that specify any kind of "credit" system for capture and 

storage of CO2, the Agency can and should consider how its UIC rulemaking will 

fit with foreseeable features of potential future regimes and how rules can be 

drafted to complement such features to the extent possible. 

Response: EPA acknowledges that GS falls within the broader context of CCS and the need for 

regulatory clarity to ensure that USDWs are protected from endangerment. In developing the final GS 

rule, the Office of Water coordinated with other Agency program offices and across federal agencies 

(e.g., with the Department of Energy; United States Geological Survey; Bureau of Ocean Energy 

Management, Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of 

Land Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

Comment: If promulgated as currently proposed, the Proposed Rule will have a significant 

and direct impact on the interests of the members of the CCS Alliance and their 

customers. The CCS Alliance believes the Proposed Rule is helpful in many ways, 

but also that it can be improved in a manner that will both promote good risk 

management and reduce barriers to CCS deployment. 

Response: EPA acknowledges the comment. The purpose of the rule is to ensure consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. Please see the remainder of EPA's responses to this comment for further details. For 

additional information on EPA's final regulatory approach, please see the final rule and preamble as well 

as the rulemaking docket. 

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23573

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23795

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23797

43
Comment: As the only significant technology to reduce atmospheric CO2 emissions from 

coal, CCS is indispensable to reducing GHG emissions while meeting energy demand 

and achieving energy security. It is true, as EPA notes, that underground 

storage of CO2 is "only one of a portfolio of options," including efficiency 

improvements, and the use of alternative and renewable energy sources. However, 

these other tools are not a substitute for baseload power generation, which 

comes primarily from fossil fuels. All GHG emission reduction options will need 

to be pursued to meet proposed emission reduction targets. The CCS Alliance 

urges that EPA, and those concerned with the Proposed Rule, consider the 

importance of CCS in the context of climate risk mitigation. 

The U.S. population is expected to grow by 60 million by 2030. During that time, 

electricity demand is projected to increase by approximately 30 percent.[FN5] 

Without rapid deployment of technologies that have begun to show promise, such 

as CCS, it will not be possible to meet the GHG emission reduction goals being 

discussed by IPCC and others now for attainment by mid-century. While the thrust 

of this rulemaking is to protect and preserve USDWs, such environmental 

objectives should neither be viewed in isolation nor divorced from other 

environmental and policy considerations - including energy security, economic 

stability and trade considerations. A rational, comprehensive approach to the 

management of CO2 emissions from GHG-emitting facilities must be undertaken if 

we are to simultaneously preserve economic stability, ensure returns on invested 

capital, enhance U.S. energy security, and mitigate the predicted effects of 

climate change. 

[FN5] Energy Information Administration, Annual Energy Outlook 2008 (June 2008), 

http://www.eia.doe.gov/oiaf/aeo/electricity,html; U.S. Census Bureau, 

Projections of the Population by Age and Sex for the United States: 2010 to 

2050 (Aug. 2008), 

http://www.census.gov/population/www/projections/files/nation/summary/np2008-12.xls. 

Response: EPA clarifies that mitigating climate change is outside the scope of the GS rulemaking. 

Rather, the purpose of the GS regulation is to ensure consistency in permitting underground injection of 

CO2 at GS operations across the United States and provide requirements to prevent endangerment of 

USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Comment: Conclusion 

We appreciate the opportunity to provide these comments. CO2 use in EOR offers 

America the opportunity to produce billions of barrels of oil that would 

otherwise be imported from foreign nations. These are existing American 

subsurface assets we should strive to optimize and America deserves these dual 

benefits of its own resources. EPA’s search for a regulatory structure to manage 

the geologic sequestration of CO2 in the context of carbon capture initiatives 

has resulted in its proposal to create a new UIC category - Class VI. This 

approach reflects the reality that GS wells do not fall readily under the 

current UIC classes. Because of CO2 use in EOR, EPA’s proposal must be balanced 

against any risk it poses to limit the use of CO2 EOR. We have identified three 

Commenter Name: Lee O. Fuller Letter ID: 0179

Commenter Organization: Independent Petroleum Association of America et al. Comment ID: 23615

44
specific concerns in these comments; others may be similarly significant. 

However, we believe that these three items - the relationship between Class II 

operations and the new Class VI GS wells, the threat of new liability risks and 

the federal-state relationship - must be positively addressed to assure that 

American can effectively produce its oil resources. If there are questions 

regarding these comments or if additional information is required, please 

contact Lee Fuller at IPAA, 202-857-4722. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, including 

the discussion of the repermitting of Class II/EOR wells for GS, please see the final rule and preamble 

as well as the rulemaking docket. 

Comment: - Protection of underground sources of drinking water (USDWs) should be the 

highest priority - water should trump everything! 

- Prevention of unintended consequences is of utmost importance; 

Response: EPA agrees that protecting USDWs is a high priority. The purpose of the GS regulation is to 

ensure consistency in permitting underground injection of CO2 at GS operations across the United 

States and provide requirements to prevent endangerment of USDWs in anticipation of the eventual use 

of GS to reduce CO2 emissions. Please see the remainder of EPA's responses to this comment for further 

details. For additional information on EPA's final regulatory approach, please see the final rule and 

preamble as well as the rulemaking docket. 

Comment: - If USDW water quality is degraded by a GS project, the owner/operator of that 

projects is responsible for any costs born by drinking water utilities due to 

increased treatment requirements for that ground water or replacement of lost 

capacity; and, 

Response: As described above, EPA clarifies that the purpose of the GS regulation is to ensure 

consistency in permitting underground injection of CO2 at GS operations across the United States and 

provide requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to 

reduce CO2 emissions. 

Comment: In its comments, AWWA makes several recommendations for the following specific 

items to be included in the final regulation: 

- Requirement to consult with the state environmental department and affected 

water utilities to determine which aquifers currently not classified as USDWs 

might be considered as future drinking water sources; 

Response: As part of the UIC permit review process in 40 CFR §124, the UIC Program Director is 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23643

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23646

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23648

45
required to notify certain stakeholders of any public hearings and the availability of the draft permit. 

EPA has added a requirement at §124.10(c)(1)(xi) that state and local oil and gas regulatory agencies 

and state agencies regulating mineral exploration and recovery, the PWSS Program Director, and all 

agencies that oversee injection wells in the state must be notified as part of the public notice process for 

a Class VI permit. For additional information on EPA's final regulatory approach, please see the final 

rule and preamble as well as the rulemaking docket. 

Comment: AWWA appreciates the opportunity to comment on the proposed requirements for 

geologic sequestration wells as published in the July 25th, 2008 Federal 

Register (73 FR 43491). Protection of underground sources of drinking water 

(USDWs) should be a key priority of any geologic carbon sequestration regulation 

developed as part of the Underground Injection Control (UIC) Program. 

Response: EPA agrees that protecting USDWs is a high priority. The purpose of the GS regulation is to 

ensure consistency in permitting underground injection of CO2 at GS operations across the United 

States and provide requirements to prevent endangerment of USDWs in anticipation of the eventual use 

of GS to reduce CO2 emissions. Please see the remainder of EPA's responses to this comment for further 

details. For additional information on EPA's final regulatory approach, please see the final rule and 

preamble as well as the rulemaking docket. 

Comment: I. GENERAL COMMENTS 

In 2007, approximately 78% of 52,000 community water systems in the United 

States were supplied by groundwater and these systems served 90.5 million 

people. In addition, many surface water utilities are currently looking at 

conjunctive use and/or groundwater development as adaptation measures (supply 

portfolio diversification/new storage) to combat climate change. Each of these 

utilities could potentially be impacted by geologic carbon sequestration, simply 

by the fact that these utilities utilize groundwater resources. 

The proposed regulation is a good technical starting point given the evolving 

state of geologic sequestration; however, the proposed rule has many limitations 

that could allow for the endangerment of underground sources of drinking water 

(USDWs). Many of the requirements are based on faith, and not a lot of data, and 

the drinking water community is being asked trust that geologic sequestration 

technology will work even though there is very little experience with this 

technology on a large scale. For example, the requirements for determining the 

direction of carbon dioxide plume migration, predicting confining layer 

containment potential, and identifying necessary geo-chemical monitoring are 

based on modeling exercises, with limited monitoring data to validate these 

models and limited real-life data to support the requirements. There is the 

possibility for unintended consequences to occur with geologic sequestration is 

very real, similar to what was observed with the use of MTBE. MTBE is the fuel 

additive that was meant to solve an air pollution problem but its use resulted 

in unanticipated drinking water pollution problems. Carbon dioxide is an energy 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23659

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23660

46
production/use byproduct that causes air pollution/climate problem but whose 

mitigation (using geologic sequestration) could cause drinking water 

contamination and other (supply) problems. EPA needs to draw on the lessons 

learned from the MTBE situation, and do everything possible to prevent a similar 

situation from occurring with geologic sequestration. Prevention is the key word 

here. AWWA will address these issues, as well as some other important concerns, 

in this section of general comments. 

Response: EPA disagrees that GS is analogous to the MTBE situation. EPA believes that large scale GS 

can be done safely. The final rule is based on the most recent GS-related data, information, and scientific 

research available. EPA intends to continue to collect data on GS and to incorporate such data as it 

implements its adaptive approach to GS rulemaking to incorporate new research, data, and information 

about GS. An adaptive approach provides Class VI owners or operators the flexibility to use and apply 

newly developed technologies for GS as they become available in the future. 

The GS regulation builds upon the long-standing, protective regulatory framework of the UIC program, 

which has been regulating the injection of fluids for decades. The GS regulation enhances this existing 

framework with tailored requirements for Class VI GS wells to address the unique nature of large scale 

GS of CO2. These protective requirements include extensive geologic testing, detailed computational 

modeling of the AoR and periodic re-evaluations, detailed requirements for monitoring and tracking the 

CO2 plume and pressure front, and extended post-injection monitoring and site care. 

Other EPA Comment Codes and Descriptions: 1600 1.3 Risk Associated with CO2 GS 

Comment: E. EPA Should Ensure that the Regulations for GS Are Not More Stringent or 

Prescriptive than Necessary to Protect USDWs. 

EPA has recognized that it has two goals for the proposed rules for geologic 

storage of carbon dioxide: the protection of underground sources of drinking 

water [FN2/] and the promotion of the development of carbon capture and 

storage.[FN3/] EPA Administrator Stephen Johnson noted when he announced the 

proposal that ""[t]oday's proposal paves the way for technologies that would 

protect public health and help reduce the effects of climate change. With proper 

site selection and management, geologic sequestration could play a major role in 

reducing emissions of carbon dioxide into the atmosphere."[FN4/] We urge EPA to 

keep both of these goals in mind and to work to ensure that the regulatory 

regime that is ultimately adopted is designed to facilitate - not delay or 

discourage - the successful commercial-scale development of carbon capture and 

storage. The potential emissions benefits of commercial-scale carbon storage are 

too large and too important to ignore in the context of these regulations. 

[FN2/: 73 Fed. Reg 43492 (July 25, 2008) ("It proposes a new class of well and 

minimum technical criteria for the geologic site characterization, fluid 

movement, area of review (AoR) and corrective action, well construction, 

operation, mechanical integrity testing, monitoring, well plugging, postinjection site care, and site closure for the purposes of protecting underground 

sources of drinking water (USDWs).").] 

[FN3/: EPA Press Release, "EPA Lays Groundwork for Promising Technologies to 

Help Mitigate Climate Change" (July 15, 2008), 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24326

47
http://www.epa.gov/safewater/uic/wells_sequestration.html ("EPA is proposing a 

rule that supports promising technologies to prevent industrial emissions of 

carbon dioxide. Secure, long-term underground storage of the greenhouse gas is 

one way scientific innovation could lessen the effects of climate change. . . . 

Carbon capture and storage is part of a portfolio of technologies available to 

reduce greenhouse gas emissions. EPA is coordinating with the Department of 

Energy on carbon sequestration research and development."); EPA Press Release, 

"EPA To Develop Regulations for Geologic Sequestration of Carbon Dioxide" 

(October 7, 2007) Id.] 

[FN4/: EPA Press Release (July 15, 2008).] 

Unfortunately, in its effort to ensure protection of USDWs, EPA has exhibited a 

zeal that could materially impede, overburden, and effectively stigmatize GS. 

The preamble to the proposed rule repeatedly overstates the risks posed by CO2 

injection while systematically understating the extent of knowledge and 

experience industry and regulators have gained through decades of practical 

experience with a wide range of injection well operations. As a result, the 

preamble presents an exhaustive review of every imaginable risk with respect to 

CO2 injection, but fails to disclose that many of these theoretical risks relate 

to implausible scenarios or concerns that - based on decades of robust 

operational and regulatory experience - are well understood and relatively easy 

to address. The scale of GS operations will certainly be larger than many 

previous CO2 injection operations, but it is not as though we do not have 

extensive experience with CO2 injection or that there is any fundamental lack of 

understanding about what happens when CO2 is injected underground. After all, 

there are already thousands of existing CO2 injection wells in operation that 

have injected hundreds of millions of tons of CO2 largely without incident. 

Rather than provide appropriate context for the development of Class VI 

regulations, however, the proposed rule gives the impression that GS is an 

adventure into entirely uncharted seas. The proposed rule - having started by 

framing the issues in this way - then employs a regulatory approach that errs on 

the side of including excessively prescriptive, overly-burdensome, and often 

redundant requirements. 

Response: EPA disagrees that the GS requirements are excessive. The Agency believes that injecting 

large volumes of CO2 for GS poses unique challenges that, if not properly managed, could endanger 

drinking water sources or have other adverse impacts. EPA believes that caution is warranted and has, as 

a result, developed a new well class with requirements tailored to address the unique challenges posed 

by GS and potential risks associated with long-term injection of CO2. These requirements include the 

tailored AoR delineation process per §146.84, monitoring that is appropriate to GS projects per §146.90, 

and extended post-injection site care per §146.93. 

EPA acknowledges that industry has decades of experience with well construction and operation. For 

example, the oil and gas industry has experience drilling and cementing wells in very deep formations, 

in a variety of environments (e.g., high-pressure and low-pressure formations), and for a variety of uses 

(e.g., injection, oil and gas production, monitoring). EPA believes that this experience has led to the 

development of well materials and construction and operating procedures that are applicable to Class VI 

wells. 

As part of its adaptive rulemaking approach, the Agency plans, every six years, to collect and review 

data on GS projects to determine whether the appropriate amount and types of information and 

48
appropriate documentation are being collected, and to determine if modifications to the requirements are 

appropriate or necessary. 

EPA clarifies that the GS rule does not promote GS in specific settings, nor does it limit injection 

activities to any specific type of formation, geographic region, or depth. The focus of the GS rule is to 

ensure that, where GS is deployed, it is conducted in a manner that is protective of USDWs. 

Other EPA Comment Codes and Descriptions: 1600 1.3 Risk Associated with CO2 GS 

Comment: 1. The Proposed Class VI Requirements Are Far More Burdensome than Necessary to 

Protect USDWs. 

As the preamble acknowledges, the actual human health and ecological risks 

associated with GS are relatively remote and can be addressed effectively 

through measures implemented to protect USDWs. 73 Fed. Reg. at 43497-98. 

Unfortunately, having started with an exaggerated sense of the risks involved 

and an inadequate recognition of the value of existing regulatory and 

operational experience relevant to CO2 injection, the proposed rule seems to 

proceed from the premise that the most strict UIC regulations in existence - 

those for hazardous waste injection - should serve as the starting point for the 

development of the Class VI regulations. This is not a logical or appropriate 

regulatory approach, because CO2 - which is found in abundance both in ambient 

air and in the subsurface - is nothing like hazardous waste and plainly does not 

warrant the same level of regulation. In fact, the principal issues with respect 

to CO2 injection for GS relate primarily to the mobility of CO2 and the sheer 

magnitude of the injection operations involved; these are not issues that the 

requirements for hazardous waste injection are particularly well suited to 

address. 

The more logical starting point for development of the Class VI regulations is 

the Class II regulations. As the proposed rule recognizes, CO2 injection 

operations have been conducted pursuant to the Class II regulations for many 

years, and experience with thousands of wells injecting hundreds of millions of 

tons of CO2 demonstrates that the Class II regulations - as applied to CO2 

injection - are adequate to protect USDWs. This is certainly true with respect 

to the basic construction, operating, monitoring, and mechanical integrity 

testing requirements for injection wells; after all, what "works" in terms of 

the construction and operation of a CO2 injection well does not depend on the 

purpose for which CO2 is being injected. Accordingly, there is no reason why the 

Class VI requirements addressing issues such as well construction and mechanical 

integrity testing should be any different than the Class II requirements. 

Unfortunately, the proposed Class VI requirements are far more stringent than 

the Class II requirements, a fact that creates a need to "grandfather" Class II 

CO2 injection wells that remain in service for GS purposes after EOR/EGR 

operations cease. Rather than resembling the Class II requirements, the proposed 

Class VI requirements are as stringent as those for hazardous waste injection in 

most respects. Indeed, many of the construction, mechanical integrity, 

monitoring and financial assurance requirements proposed for Class VI wells are 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24327

49
even more comprehensive and more strict than those for hazardous waste injection 

wells. While some of these more burdensome requirements are legitimately related 

to concerns about the mobility of CO2 or the anticipated scale of GS operations, 

many - as discussed in Part III of these comments - are not. 

Response: EPA disagrees that the GS requirements are excessive or are based on exaggerated risks; the 

Agency believes that injecting large volumes of CO2 for GS poses unique challenges that, if not 

properly managed, could endanger drinking water sources or have other adverse impacts. EPA believes 

that caution is warranted and has, as a result, developed a new well class with requirements tailored to 

address the unique challenges posed by GS and potential risks associated with long-term injection of 

CO2. These requirements include the tailored AoR delineation process per §146.84, monitoring that is 

appropriate to GS projects per §146.90, and extended post-injection site care per §146.93. 

EPA believes that the nature of CO2 injection for long-term storage is different from Class II CO2 

injection for ER, and that tailored requirements for Class VI wells are appropriate and necessary to 

protect USDWs from endangerment. For this reason, the Agency tailored UIC requirements for Class VI 

wells that address the general risks deep injection may pose to USDWs and specifically address the 

unique nature of CO2 GS (i.e., very large volumes, very long time-periods, and reservoir pressure 

conditions). 

Other EPA Comment Codes and Descriptions: 1680 1.3.8 Don't overstate risk, don't stigmatize CO2 

Comment: 2. Rules that Stigmatize GS or Burden it Excessively Would Not be in the Public 

Interest. 

The magnitude of the regulatory burdens imposed by the proposed Class VI 

requirements are of concern for several reasons. First, unnecessary regulatory 

burdens would act as a direct impediment and disincentive to the development of 

GS projects. Less directly, the imposition of unreasonably stringent regulatory 

requirements - particularly requirements for multiple layers of requirements 

addressing the same basic risks - inherently magnify the impression of risk and 

could thus stigmatize GS and discourage investment in GS projects. EPA should 

recognize that "more regulation" - particularly the "belt-and-suspenders plus 

more belts and more suspenders" approach reflected in the proposed rule - is not 

"better regulation" in the GS context. To the contrary, overly-burdensome 

regulation - to the extent it effectively impedes or deters use of a promising 

technology - could prove counterproductive. 

We understand the importance of public perception when it comes to the siting 

and permitting of needed infrastructure, and believe strongly in the need to 

ensure that the public has accurate information. To facilitate the public’s 

appreciation of the merits of GS, we urge EPA to ensure that it does not 

overstate the risks associated with CO2 injection or understate the justified 

confidence with which many potential issues and concerns can be addressed. 

Similarly, we urge EPA to avoid the imposition of regulatory requirements that 

are so disproportionate to the risks involved that they may do more to incite 

than address public concerns. To this end, EPA should scale back its regulatory 

requirements to more accurately reflect the magnitude of actual risks and to 

ensure that any requirements imposed are truly necessary for the protection of 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24328

50
USDWs. 

EPA should also consider the effect its regulations might have on the ability to 

secure critical financial backing for GS projects. Any exaggerated impression of 

the risks involved in GS could adversely influence financial institutions and 

impede efforts to obtain financing. The recent turmoil in the financial markets 

highlights how challenging the financing of new technologies may become. In a 

credit-constrained world, investors will be wary of putting their limited funds 

behind GS projects if they believe they are likely to endanger the environment 

or public health. Accordingly, EPA should recognize the importance of the 

messages that it sends the financial world through the regulations it imposes. 

Permanent storage of CO2 can be accomplished safely and without harm to the 

environment as long as we apply the right knowledge base, detailed site-specific 

information, technical expertise, and sound management practices. However, we 

cannot implement an effective regulatory program for sequestering CO2 if the 

rules are based on the erroneous premise that CO2 represents an extreme hazard. 

It is therefore important that EPA send accurate messages about the nature of 

CO2 and the actual magnitude of the risks associated with GS. It is also 

critical that EPA strike an appropriate balance by addressing the risks 

associated with GS without creating a regime that effectively hinders or deters 

use of this key technology for reduction of carbon emissions. 

Response: EPA disagrees that the GS regulation overstates the risk of CO2 injection. EPA recognizes 

that injecting large volumes of CO2 for GS poses unique challenges that, if not properly managed, could 

endanger drinking water sources and have other adverse impacts. However, with proper site selection, 

the final, tailored, Class VI requirements address the large volumes of CO2 injected, its buoyancy, 

potential corrosivity in the presence of water, and potential impurities in the CO2 stream. In addition, 

EPA expects the tailored permitting, siting, construction, operation, monitoring, and post-injection site 

care requirements in the GS rule to prevent leakage from injection formations and protect USDWs. 

EPA does not believe that the tailored requirements will create a negative public perception of GS. The 

Agency believes that a demonstration to the public that GS projects are meeting the GS rule's tailored 

requirements will likely improve confidence in the project and help address public questions and 

concerns. 

Regarding the ability of owners or operators to secure financial backing for GS projects, EPA believes 

that, like the public, financing entities will have improved confidence in projects that incorporate 

multiple protective requirements. Please see the discussion of financial responsibility in the preamble to 

the final GS rule. 

Comment: period of the project. CCS is a developing technology and additional data and 

research findings will be available regularly. Therefore, we recommend that EPA 

have a plan to update the regulation on a regular basis as well. Having a permit 

Response: The final rule is based on the most recent GS-related data, information, and scientific 

research available. EPA plans, every six years, to collect and review data on GS projects to determine 

Commenter Name: Diane VanDe Hei Letter ID: 0206

Commenter Organization: Association of Metropolitan Water Agencies 

(AMWA)

Comment ID: 

22212

51
whether the appropriate amount and types of information and appropriate documentation are being 

collected, and to determine if modifications to the requirements are appropriate or necessary. An 

adaptive approach provides Class VI owners or operators the flexibility to use and apply newly 

developed technologies for GS as they become available in the future. 

Please see the remainder of EPA's responses to this comment for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: It is important to recognize at the outset the development of a viable, largescale commercial CCS program requires resolution of technical, policy, legal, 

and liability issues providing necessary regulatory certainty that may be beyond 

the scope of this specific rulemaking. 

Response: EPA acknowledges that GS falls within the broader context of CCS and the need for 

regulatory clarity to ensure that USDWs are protected from endangerment. In developing the final GS 

rule, the Office of Water coordinated with other Agency program offices and across federal agencies 

(e.g., with the Department of Energy; United States Geological Survey; Bureau of Ocean Energy 

Management, Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of 

Land Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

Other EPA Comment Codes and Descriptions: 1630 1.3.3 RCRA/hazardous waste issues (seeking 

comment); 1640 1.3.4 CERCLA issues (seeking comment) 

Comment: This rulemaking can resolve some important policy and legal issues and, in doing 

so, help foster the development of a practical, commercially deployable CCS 

regulatory program. For example, the Final Rule can provide much needed clarity 

regarding (1) the potential for liability under the Resource Conservation and 

Recovery Act ("RCRA") and the Comprehensive Environmental Response, 

Compensation, and Liability Act ("CERCLA") resulting from CO2 injection and GS 

activities, and (2) the options for addressing long-term post-injection 

liability for Class VI wells. As discussed below, there are practical regulatory 

and legislative options available to resolve these uncertainties that will help 

assure the public and the regulated community that CO2 UIC activities can be 

conducted in a manner that is both safe and effective. 

Response: EPA agrees that regulatory clarity is important. With respect to RCRA and need for 

regulatory clarity, EPA has decided to initiate a separate proposed rulemaking specifically to examine 

the issue of RCRA applicability to CO2 streams being geologically sequestered, including the possible 

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 22896

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 22897

52
option of a conditional exemption from the RCRA requirements for CO2 GS in Class VI wells. EPA 

will consider these comments as part of its development of that proposal. The Agency will consider 

issues particular to RCRA in the context of that separate rulemaking, and recommends that the 

commenter read that proposed rule when it is published. The Agency notes that commenters who wish 

to submit comments on the RCRA proposal will need to do so during the comment period for that rule. 

Finally, EPA also notes that the final GS rule, which adds new regulations for Class VI wells under the 

Safe Drinking Water Act (SDWA), is not making any changes to the RCRA regulations. 

Comment: As a mining company, NAC is very aware that geology varies throughout the 

country and within regions and locales. This heterogeneous mix of subsurface 

conditions makes it challenging to develop a regulatory program that can 

adequately address all situations and conditions that will be encountered. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble, including the discussions of site characterization and target formations for 

GS, as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1435 1.2.1.3 EPA should develop guidance 

Comment: 2. Reconsider shifting the burden to the States when not enough information is 

available. It appears that much research is needed to ensure that geologic 

sequestration can be conducted in a safe manner. When research data is not 

available, or when EPA is uncertain of the best way to address a situation, the 

burden of addressing the issue is shifted to the states. Examples include 

corrective action methodology for abandoned wells, materials used in 

construction of the wells, and the use of tracers among other issues. Oklahoma 

DEQ recommends that EPA prepare guidance documents to address the above 

concerns. 

Response: EPA clarifies that such decisions would be made by the state, if the well is located in a state 

with Class VI primacy. Any state that wishes to obtain primacy for Class VI wells will need to describe 

in their program description the criteria that would be used to make determinations on topics the 

commenter mentions. See §145.23. EPA adds that it is developing guidance for states and tribes that 

describes the process of applying for and receiving primacy for GS Class VI wells under Section 1422 

of SDWA, as well as the technical and administrative issues associated with developing GS regulations 

that are the equivalent of minimum federal criteria and requirements. These are available on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5600 2.11 Comments related to UIC Program primacy 

for Class VI wells 

Commenter Name: Dennis R. James Letter ID: 0214

Commenter Organization: North American Coal Corporation (NAC) Comment ID: 22958

Commenter Name: Saba Tahmassebi Letter ID: 0218

Commenter Organization: Oklahoma Department of Environmental Quality 

(DEQ)

Comment ID: 

21563

Commenter Name: Jonathon Palm Letter ID: 0222

Commenter Organization: Nevada Division of Environmental Protection, Bureau of

Water Pollution Control

Comment ID: 

21644

53
Comment: 5. In implementing this rule, the state will be encumbered with increased 

financial and resource burdens in assessing the geologic sequestration permit 

submissions, evaluating the technical models, and making permitting 

determinations. Financial resource considerations should accompany eventual 

promulgation of the rule in order to ensure adequate funding for these various 

tasks. 

Response: EPA acknowledges that there may be technical and administrative challenges including 

resource concerns, and will work closely with the states to assist them in resolving funding issues or 

acquiring the resources, personnel, and training needed to address the unique technical challenges 

associated with GS. 

EPA will also incorporate Class VI wells into the UIC Program's grant allocation process. The 

States/Tribes/Territories must also demonstrate that they have adequate resources to implement the 

program through matching resources against those allocated by the UIC Program's grant allocation 

formula. Currently, primacy programs are required to meet a minimum of 25 percent matching 

requirement. 

Comment: CURC has concerns about EPA’s proposed rule. CURC believes that the final rule 

should be modified to provide: (a) greater regulatory certainty for CO2 storage 

in geologic formations, (b) balance between reducing the risk of potential 

impacts of injected CO2 on underground sources of drinking water (or USDW), and 

increasing the likelihood that overly stringent UIC rules could lead to delays 

in the commercial adoption of CCS technology and ultimately less CO2 mitigation, 

(c) a regulatory design that accommodates greater flexibility in permitting CO2 

injection, (d) interim guidance for GS projects for the period that precedes 

promulgation of the final UIC rule, and (e) no interference with ongoing 

regulatory programs that govern the commercial injection of CO2 for enhanced oil 

or methane recovery. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

EPA clarifies that the GS rule does not promote or encourage the use of GS; rather it is designed to 

ensure consistency in permitting underground injection of CO2 at GS operations across the United 

States and provide requirements to prevent endangerment of USDWs in anticipation of the eventual use 

of GS to reduce CO2 emissions. EPA adds that the final GS rule includes a balance of specific criteria to 

be met by the owner or operator and areas of Director discretion. The Agency believes this balance 

allows for GS projects to be designed and permitted to address the unique, site-specific aspects of each 

project, while providing consistency in permitting across the United States. 

Other EPA Comment Codes and Descriptions: 2400 1.8 Comments on EPA's adaptive rulemaking 

process 

Comment: EPA’s proposed rule includes a number of requirements that could create 

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21779

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21781

54
significant uncertainty as CCS project developers initiate projects. These 

requirements will serve as barriers to CCS project developers who will need a 

clear idea of their environmental obligations and financial exposures before 

such projects are initiated. In general, we believe that the "adaptive" 

regulatory approach, as set forth in Section III.B. of the Preamble, will lead 

to regulatory uncertainty. Specifically, the NOPR states that "EPA will track 

implementation of the final GS rule to determine whether these requirements 

continue to meet SDWA objectives and, if not, revise them as needed." 

Formulating regulations on the best available scientific information available 

is appropriate but these NOPR statements signal an intent that the regulations 

could be modified before, during or after the initial regulations are 

promulgated. This ability to exercise such broad discretion will discourage 

entities considering CCS projects from moving forward. It is important for EPA 

to retain discretion to amend its rules, but to limit such discretion to be 

exercised within stated criteria; to provide notice and opportunity for comment; 

and to apply any modifications prospectively, allowing projects already 

operating under valid permits to continue to operate pursuant to regulations in 

place at the time such permits were issued. 

Response: EPA acknowledges that the UIC GS adaptive rulemaking approach introduces a degree of 

uncertainty—given that the GS requirements may change in the future. However, the Agency believes 

that there is also a need to proceed with regulatory development at a pace that can meet the current and 

future demands for Class VI permits, and allow early projects to be permitted under the tailored Class VI 

regulatory approach. 

EPA believes that an adaptive approach to regulating CO2 injection for GS will allow regulatory 

development to proceed and ensure USDW protection from endangerment while EPA continues to 

gather data from pilot projects and other research as it becomes available. Additionally, the Agency 

believes that there is a need to have regulations in place during the earliest phases of GS deployment. 

Finalizing requirements at this time will allow early GS wells to be permitted in a manner that addresses 

the unique characteristics of CO2 injection for GS and allow early projects to demonstrate successful 

confinement of CO2 in a manner that is protective of USDWs. EPA also believes that an adaptive 

approach enables the Agency to make changes to the program as necessary to incorporate new research, 

data, and information about GS and associated technologies (e.g., modeling and well construction). This 

new information may increase protectiveness, streamline implementation, or otherwise inform the 

requirements for GS injection of CO2. Any revisions that will be made to the GS requirements in the 

future will go through public notice and comment as required by the SDWA. 

Regarding the comment that projects operating under valid permits should be able to continue to operate 

pursuant to regulations in place at the time of permit issuance, EPA notes that changes to the GS 

regulation may trigger permit modifications under existing regulations at 40 CFR 144.39(c), which may 

trigger public notice and comment procedures under Part 124. EPA adds that the final GS rule allows the 

construction of existing Class I, Class II, or Class V experimental technology wells to be grandfathered, 

at §146.81(c), provided the owner or operator can demonstrate to the Director that the wells were 

engineered and constructed to meet the requirements at §146.86(a) and ensure protection of USDWs, in 

lieu of requirements at §§146.86(b) and 146.87(a). 

Comment: B. The Need for Balanced Regulation 

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21786

55
We agree that a regulatory structure for GS wells is urgently required for CO2 

injection outside of applications for enhanced recovery of stranded oil and 

methane. Most important, the final rules must insure the primacy of protecting 

our nation’s drinking water as we begin a program to sequester CO2. However, the 

UIC regulations must not inadvertently create uncertainty or establish a 

regulatory program that actually discourages the geologically and geographically 

diverse commercial deployment of CCS. We appreciate the level of certainty that 

the proposed rule seeks to achieve for CCS project developers in light of the 

need to protect drinking water, yet there are several areas of the proposed rule 

that we believe require the EPA to document the need for the level of proposed 

stringency, or to consider reducing that stringency. This need for explanation 

or modification applies to the following elements of the proposed rule: 

Response: EPA clarifies that the GS rule does not promote or encourage the use of GS; rather it is 

designed to ensure consistency in permitting underground injection of CO2 at GS operations across the 

United States and provide requirements to prevent endangerment of USDWs in anticipation of the 

eventual use of GS to reduce CO2 emissions. EPA believes that the GS regulation will provide 

regulatory certainty and oversight that operators have requested, and allow for the deployment of this 

key climate change mitigation technology that could be deployed to reduce CO2 emissions. EPA adds 

that the GS regulation builds upon the long-standing protective framework of the UIC Program, which 

has been regulating the injection of billions of gallons of fluids for decades, including wells used for 

enhanced oil recovery. 

Other EPA Comment Codes and Descriptions: 1435 1.2.1.3 EPA should develop guidance 

Comment: D. Interim Program Recommendations 

CURC proposes that EPA consider issuing guidance to create an interim program 

that would provide a regulatory framework for CCS projects prior to the 

promulgation of a final rule. Our concern rests with the possibility that the 

final rules may not be issued for some time in the future. For example, a 

section in the preamble to the NOPR states: 

During the Deployment Phase (1008-1017), the [RCSP] partnerships will 

conduct large volume carbon storage tests to demonstrate that large-scale 

CO2 injection and storage can be achieved safely and economically. EPA 

will use the data collected from these projects to support decisions in the 

final GS rule. 

This statement suggests that a final GS rule may not be issued until 2017 or 

that rules issued earlier than that date could be modified and changed later. 

While we ascribe to a belief that any final rule should be informed by the 

findings and data collected through RCSP partnerships, we are concerned that 

regulatory uncertainty will delay CCS project development; hence the need for an 

interim program. 

Projects issued permits under this guidance would collect data and technological 

experience that could contribute information necessary to establish a viable 

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21794

56
working framework for a long term permitting and liability regime for geologic 

CO2 storage activities. The program might be limited to a maximum number of 

projects, or cumulative amount of CO2 injection, and it should be designed to be 

compatible with anticipated financial incentives for "early adopters" of CCS 

technology. Projects permitted under this interim guidance should be 

grandfathered from the final UIC rule. 

Specific limiting provisions could be required in order to ease any concerns 

regarding the endangerment of USDW under such an interim program. Since proper 

site characterization is the most effective risk management tool for GS wells, 

EPA could require applicants under this program to use geologically superior 

sites, or provide alternative requirements for sites with significantly superior 

characteristics. The World Resource Institute (WRI) CCS Guidelines [FN5] and 

IOGCC model rules include provisions for selecting storage sites that have a 

high probability of retaining injected CO2. [FN6] An interim program would 

recognize the same goals sought by EPA when it issued its guidance for DOE 

Regional Partnership pilot projects designed to evaluate the technical issues 

associated with CO2 injection as Class V experimental technology wells. [FN7] 

[FN5: World Resource Institute, "CCS Guidelines: Guidelines for Carbon Capture, 

Transport and Storage" (2008). The WRI Guidelines also offer a comprehensive 

regulatory approach to CCS that goes beyond the regulation of GS wells. 

However, in the guideline’s discussion of site closure, the WRI acknowledges a 

need for proper incentives so as not to impede the deployment of CCS technology 

as private companies may be reluctant to engage in storage operations if 

required to carry a financial commitment and liability out into the indefinite 

future. Id. at 104.] 

[FN6: The IOGCC model rules premise approval of a GS storage site on four 

findings: (1) the facility and reservoir are suitable and feasible for injection 

and storage; (2) that a good faith effort has been made to obtain the consent of 

a majority of the owners having property interests affected by the storage 

facility, and that the operator intends to acquire any remaining interest by 

eminent domain or otherwise allowed by statute; (3) that the use of the storage 

facility will not contaminate other formations containing fresh water, oil, gas, 

coal or other mineral deposits; and (4) that the proposed storage will not 

unduly endanger human health and the environment and is in the public interest. 

See IOGCC Model Rules, supra note 5 at Appendix I.] 

[FN7: Envtl. Protection Agency, Office of Ground Water and Drinking Water, UIC 

Program Guidance #83, Using Class V Experimental Technology Well Classification 

for Pilot Geologic Sequestration Projects (2007).] 

Response: EPA disagrees that an interim program is necessary. EPA believes that sufficient data have 

been collected to inform the final GS rule. In addition to laboratory studies and modeling research that 

provide relevant information on GS, the Agency is also collecting and analyzing GS project data and 

permit information from a variety of sources. Most notably, EPA has evaluated permits and reviewed 

operational data and information associated with the seven regional carbon sequestration partnerships 

funded by the U.S. Department of Energy and coordinated through the National Energy Technology 

Laboratory. EPA believes that these projects form a solid basis for finalizing the GS requirements, and 

there is no reason to wait until all phases of the DOE demonstration tests are complete. Nevertheless, 

EPA anticipates that future experimental and full-scale projects will continue to inform the technology, 

and is therefore using an adaptive rulemaking approach. The Agency plans to, every six years, collect 

57
and review data on GS projects to determine whether the appropriate amount and types of information 

and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. EPA believes that the completion of the DOE pilots in 2017 

will allow the incorporation of results of these projects into the first review of the rule. 

EPA clarifies that this rule does not allow grandfathering. However, under §146.81 owners or operators 

seeking to convert existing Class I, Class II, or Class V experimental wells to Class VI geologic 

sequestration wells must demonstrate to the Director that the wells were engineered and constructed to 

meet the requirements at §146.86(a) and ensure protection of USDWs, in lieu of requirements at 

§146.86(b) and §146.87(a). 

Comment: E. Conclusion 

CURC understands EPA’s position that the SDWA does not provide EPA with the 

authority to develop regulations for all questions and issues related to GS. 

While a full regulatory framework is necessary for CCS projects to move forward, 

CURC recommends that EPA work within the UIC program to create necessary 

regulatory certainty for early CCS projects. EPA should acknowledge that overly 

Response: EPA clarifies that the GS rule does not promote or encourage the use of GS; rather it is 

designed to ensure consistency in permitting underground injection of CO2 at GS operations across the 

United States and provide requirements to prevent endangerment of USDWs in anticipation of the 

eventual use of GS to reduce CO2 emissions. EPA believes that the GS regulation will provide 

regulatory certainty and oversight that operators have requested, and allow for the deployment of this 

key climate change mitigation technology that could be deployed to reduce CO2 emissions. Please see 

the remainder of EPA's responses to this comment for further details. 

Other EPA Comment Codes and Descriptions: 1435 1.2.1.3 EPA should develop guidance 

Comment: proposed. Lastly, CURC recommends that EPA issue guidance for an interim Class 

VI program for CCS projects that predate the final UIC rule. 

Response: In advance of the GS rulemaking, EPA developed UIC Program Guidance # 83: Using the 

Class V Experimental Technology Well Classification for Pilot Carbon GS Projects (USEPA, 2007), 

which provides recommendations for permit writers regarding the use of the UIC Class V experimental 

technology well classification at demonstration GS projects while ensuring USDW protection. 

EPA disagrees that an interim program is necessary. EPA believes that sufficient data have been 

collected to inform the final GS rule. In addition to laboratory studies and modeling research that 

provide relevant information on GS, the Agency is also collecting and analyzing GS project data and 

permit information from a variety of sources. Most notably, EPA has evaluated permits and reviewed 

operational data and information associated with the seven regional carbon sequestration partnerships 

funded by the U.S. Department of Energy and coordinated through the National Energy Technology 

Laboratory. EPA believes that these projects form a solid basis for finalizing the GS requirements, and 

there is no reason to wait until all phases of the DOE demonstration tests are complete. Nevertheless, 

EPA anticipates that future experimental and full-scale projects will continue to inform the technology, 

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21795

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21801

58
and is therefore using an adaptive rulemaking approach. The Agency plans to, every six years, collect 

and review data on GS projects to determine whether the appropriate amount and types of information 

and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. EPA believes that the completion of the DOE pilots in 2017 

will allow the incorporation of results of these projects into the first review of the rule. 

EPA clarifies that this rule does not allow grandfathering. However, under §146.81 owners or operators 

seeking to convert existing Class I, Class II, or Class V experimental wells to Class VI geologic 

sequestration wells must demonstrate to the Director that the wells were engineered and constructed to 

meet the requirements at §146.86(a) and ensure protection of USDWs, in lieu of requirements at 

§146.86(b) and §146.87(a). 

EPA clarifies that following finalization of the GS rule, all GS projects that are not for experimental 

purposes must be re-permitted as Class VI wells and be subject to the final GS rule requirements. 

Other EPA Comment Codes and Descriptions: 1500 1.2.2.2.4 Some other agency should regulate GS 

Comment: As noted in our joint comments with USWAG, many complex technical and legal 

issues will have to be resolved before geologic sequestration of CO2 can become 

a reality, and this will require a cooperative effort among several federal 

agencies, including EPA, the Department of Transportation, and the Federal 

Energy Regulatory Commission. The General Accounting Office ("GAO") recently 

issued a report entitled "Climate Change - Federal Actions Will Greatly Affect 

the Viability of Carbon Capture and Storage As a Key Mitigation Option" 

(GAO-08-1080, September 2008) ("GAO Report"), which emphasizes that significant 

technological barriers involving CO2 capture technologies, as well as regulatory 

and legal uncertainties involving CO2 storage, leakage, and ownership issues, 

must be resolved before a successful CO2 CCS program of the scale envisioned by 

policymakers can be achieved. GAO Report at 3-5. A National Academy of Sciences 

Response: Regarding the need for a CCS agency to coordinate across agencies, EPA is coordinating 

with and will continue to facilitate communication among federal and state agencies during the 

implementation phase of the GS regulation. 

Comment: 9. The proposed rules for Class VI GS wells are more stringent than the other 

UIC well classes (73 FR 43524-43525) yet they do not comprehensively manage 

issues of concern for GS. With this limitation, the proposed rules run the risk 

of locking in a regulatory framework that ultimately inhibits widespread 

commercial deployment of CCS. 

Response: EPA clarifies that the GS rule does not promote or encourage the use of GS; rather, it ensures 

consistency in permitting underground injection of CO2 at GS operations across the United States and 

provides requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to 

reduce CO2 emissions. EPA believes that the GS regulation will provide the regulatory certainty and 

oversight that operators have requested, and allow for the deployment of this key climate change 

Commenter Name: Pamela A. Lacey Letter ID: 0228

Commenter Organization: American Gas Association Comment ID: 21806

Commenter Name: M. Granger Morgan Letter ID: 0233

Commenter Organization: Carnegie Mellon University on behalf of the CCS Reg 

Project

Comment ID: 

21900

59
mitigation technology that could be deployed to reduce CO2 emissions. Please see the remainder of 

EPA's responses to this comment for further details. 

Comment: Conclusion 

26. The CCS Regulatory Project shares EPA's commitment, and that of other 

participants in the national discussion, to advancing the potential for safe and 

effective geological sequestration of carbon dioxide. To that end, the agency's 

draft rules are, subject to the specific concerns raised in our comments, a 

laudable effort to define a regulatory framework for assuring that carbon 

capture and sequestration proceed in a manner that is calculated to protect the 

nation's water supply. But, in our judgment, the objectives we share with EPA 

are best served by a regulatory scheme that takes into account, and ultimately 

advances, the full range of environmental imperatives that drive the development 

of CCS in the first place. With the impending advent of a new administration and 

a new Congress, both of which are expected to be attentive to issues related to 

climate change, the potential for near-term legislative action is relatively 

high. In these circumstances, EPA should consider using existing regulatory 

authority under the UIC program to license the first few CCS projects, but wait 

to finalize rules for GS wells until they can be drafted under the authority of 

new or amended legislation that enables more comprehensive regulation. 

Response: The final rule is based on the most recent GS-related data, information, and scientific 

research available. EPA believes that sufficient data have been collected to inform the final GS rule. 

Nevertheless, EPA anticipates that future experimental and full-scale projects will continue to inform the 

technology, and is therefore using an adaptive rulemaking approach. EPA plans, every six years, to 

collect and review data on GS projects to determine whether the appropriate amount and types of 

information and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. 

Comment: Indiana is a member of the Interstate Oil and Gas Compact Commission (IOGCC). In 

2002, the IOGCC established a Geological C02 Sequestration Task Force chaired by 

Lawrence Bengal, Director of the Arkansas Oil and Gas Commission. Its membership 

initially included representatives from IOGCC member states and international 

affiliate provinces, state and provincial oil and gas agencies, DOE, DOEsponsored Regional Carbon Sequestration Partnerships, the Association of 

American State Geologists (AASG), and the oil and natural gas industry. Later on 

the Task Force added representatives from EPA, and the U.S. Bureau of Land 

Management (BLM) attended as observers. This Task Force engaged in a thorough 

examination of the technical, policy, and regulatory issues related to the safe 

and effective storage of C02 in subsurface geological media (oil and natural gas 

fields, coal seams, and deep saline formations) for both enhanced hydrocarbon 

recovery and long-term C02 storage. 

Commenter Name: M. Granger Morgan Letter ID: 0233

Commenter Organization: Carnegie Mellon University on behalf of the CCS Reg 

Project

Comment ID: 

21918

Commenter Name: Robert E. Carter Jr. Letter ID: 0236

Commenter Organization: Indiana Department of Natural Resources (IDNR) Comment ID: 23203

60
The products of the Task Force efforts were the following two reports: 

1. "Final Report" for DOE Aware No. DE-FC26-03NT41994, Amendment No. AOOO, dated 

January 24, 2005. This report contained an assessment of the current regulatory 

framework applicable to carbon capture and geologic storage and recommended 

regulatory guidelines and guidance documents for the states and provinces. 

2. "Storage of Carbon Dioxide in Geologic Structures - A Legal and Regulatory 

Guide for States and Provinces" dated September 25,2007. A thorough assessment 

of property rights issues relating to the underground space used for CCGS, and 

an overview of model general rules and regulations for CCGS along with a Model 

Statute and a Model General Rules and Regulations for CCGS were included in this 

report. 

We believe these two reports present the most practical and workable models for 

the regulation of CCGS and we encourage EPA to strongly consider them as it 

continues its process of finalizing the Class VI CCGS rule. We have not included 

them as attachments to our comments as we know they have already been submitted 

to EPA. 

Additionally, we also know that detailed comments on the above referenced rules 

have been prepared and submitted to EPA on behalf of the IOGCC. IDNR supports 

the IOGCC comments and strongly encourages EPA to take them into consideration 

as the final rules are being considered. Except for a few specific comments on 

topics that we believe do warrant extra emphasis, we do not think it necessary 

to restate every issue already addressed through the IOGCC comments. 

Response: EPA acknowledges the comment. EPA adds that it has reviewed the IOGCC's reports and 

that information provided by IOGCC throughout the rulemaking process has informed many technical 

aspects of the rule. EPA appreciates the input and effort that IOGCC has provided, as well as those from 

other state and private stakeholder consortia. 

Please see the remainder of EPA's responses to this comment and IOGCC’s comment for further details. 

For additional information on EPA's final regulatory approach, please see the final rule and preamble as 

well as the rulemaking docket. 

Comment: A. The OCD has participated in preparing, and is generally supportive of, the 

comments presented by the Interstate Oil and Gas Compact Commission (IOGCC) and 

the Ground Water Protection Council (GWPC). 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment and comments from IOGCC and GWPC for further details. For additional information on 

EPA's final regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: Overall, the proposed rule makes good strides at addressing some of the key 

Commenter Name: Mark E. Fesmire Letter ID: 0237

Commenter Organization: New Mexico Oil Conservation Division (NMOCD) Comment ID: 23208

Commenter Name: Kristin Henry Letter ID: 0242

Commenter Organization: Sierra Environmental Law Program, Sierra Club Comment ID: 23308

61
issues for geological sequestration. However, there are several areas that need 

improvement as we discuss below. First we briefly provide background on the 

infancy of large-scale CCS deployment, technical complexities, and the import of 

rapid development of CCS to tackle the global warming crisis 

Response: EPA acknowledges the comment. The final rule is based on the most recent GS-related data, 

information, and scientific research available. EPA intends to continue to collect data on GS and to 

incorporate such data as it implements its adaptive approach to GS rulemaking to incorporate new 

research, data, and information about GS. An adaptive approach provides Class VI owners or operators 

the flexibility to use and apply newly developed technologies for GS as they become available in the 

future. Please see the remainder of EPA's responses to this comment for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: A Few Critical Changes Are Needed in the Proposed Rule 

EPA must be applauded for taking a critical step toward climate change goals by 

proposing the first rule to regulate carbon injection and storage. However, the 

proposed rule does not fully reflect the current emerging state of CCS 

technology. EPA recognizes the rule must strengthen science, technology, and 

institutions in order to support a strategy to address climate change. [FN14] 

The suggestions outlined below would do just that: 

[FN14: Proposed rule at p. 23.] 

Response: The final rule is based on the most recent GS-related data, information, and scientific 

research available. EPA intends to continue to collect data on GS and to incorporate such data as it 

implements its adaptive approach to GS rulemaking to incorporate new research, data, and information 

about GS. An adaptive approach provides Class VI owners or operators the flexibility to use and apply 

newly developed technologies for GS as they become available in the future. EPA clarifies that the 

intent of the GS rule is not to promote or encourage the use of GS; rather, its purpose is to ensure 

consistency in permitting underground injection of CO2 at GS operations across the United States and 

provide requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to 

reduce CO2 emissions. 

Comment: The rule also lacks opportunities for public participation, ignores the very 

important question of liability, and requires a few definition tweaks. Finally, 

Response: EPA acknowledges the comment and disagrees that the rule lacks opportunities for public 

participation. GS permitting authorities must follow the existing public participation requirements for 

UIC permits as specified in 40 CFR 25 and 40 CFR Part 124. These regulations lay out the procedures 

for decision making and include requirements such as requiring the Director to notify the public 

regarding the availability of the draft permit and allow him or her to request a public hearing on the draft 

permit. Encouraging public participation allows the permitting authority to understand public 

viewpoints, preferences, and concerns about the project, which might help avoid public misperceptions 

Commenter Name: Kristin Henry Letter ID: 0242

Commenter Organization: Sierra Environmental Law Program, Sierra Club Comment ID: 23313

Commenter Name: Kristin Henry Letter ID: 0242

Commenter Organization: Sierra Environmental Law Program, Sierra Club Comment ID: 23316

62
about the nature and safety of GS projects and forestall resistance later in the permitting effort.

Please see the remainder of EPA's responses to this comment for further details. For additional 

information on EPA's final regulatory approach, including the discussion of the public participation 

requirements and long-term liability, please see the final rule and preamble as well as the rulemaking 

docket. 

Other EPA Comment Codes and Descriptions: 1310 1.1.2.4 Comments on other "out of scope" 

issues, e.g., pore space ownership 

Comment: WEST Associates Comments on the Proposed Rule 

The following are WEST's comments on the Preamble and proposed rule, which we 

believe will clarify and strengthen the proposal: 

– Under the proposed UIC regulation, siting UIC wells for GS in the west will 

likely involve a challenging set of national agencies, states, and tribal sets 

of regional and sub-regional regulation that will require streamlining in order 

to site UIC wells and pipelines to transfer super critical CO2 to GS sites 

located at some distances away from coal fired power plants. Such projects will 

cross over many jurisdictions and involve a patchwork of regulatory 

requirements. This will require coordination among federal and tribal 

jurisdictions since it is highly likely that most western projects will impact 

federal lands, including tribal lands. EPA should immediately start working 

towards building support and consensus among the federal land managers and BIA 

for the UIC regulatory program. 

Response: EPA understands that the CO2 plumes for large GS projects may cross State, Tribal, 

Territorial, EPA Regional, or national boundaries. The final GS rule, at §146.82(a)(2), requires the 

owner or operator to identify all State, Tribal, and Territorial boundaries within the AoR. Based on this 

information, the Director must provide written notification to all States, Tribes, and Territories to inform 

them of the permit application §146.82(b) and ensure that they are involved in any necessary processes 

(e.g., development of the emergency and remedial response plan (§146.94)). The Agency encourages 

transparency in the permitting process and anticipates that State-State/State-Tribal communication on 

GS permitting will facilitate information sharing and encourage safe, protective projects. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission Associates Comment ID: 22240

63
Other EPA Comment Codes and Descriptions: 1530 1.2.3.1 State regulatory efforts on GS (seeking 

comment) 

Comment: – EPA needs to design the UIC program to facilitate GS sites that can be 

utilized by many individual power plants that may not have ready access to 

geologically suitable GS sites in proximity to such plants. What will be needed 

is state, tribal and federal cooperation to develop regional storage sites that 

could accommodate CO2 from sources in several states. Development of such 

regional storage sites would allow critically needed sharing pore space in 

states that have the most favorable geology. 

Response: EPA encourages owners and operators and permitting authorities to coordinate where 

multiple injection operations are planned, but notes that the rule does not require such coordination. 

EPA notes that the impacts of multiple operators injecting into hydraulically connected formations must 

be accounted for in the AoR modeling required at §146.84, which must be based on detailed site-specific 

geologic data collected during the site characterization process including consideration of existing 

conditions (e.g., current injection activities). Please see the discussion of AoR and Corrective Action in 

the preamble to the final rule for additional information. 

EPA adds that regulation of pore space ownership is outside the scope of this rulemaking. 

Comment: Clearly, a viable large-scale commercial CCS program requires resolution of a 

broad range of technical, policy and legal questions, most of which are beyond 

the scope of this rulemaking. A good synopsis of those challenges was 

documented in the recent General Accounting Office ("GAO") report, "Climate 

Change - Federal Actions Will Greatly Affect the Viability of Carbon Capture and 

Storage as a Key Mitigation Option" (GAO-08-1080, September, 2008). That said, 

we think EPA’s efforts here are an important first step and will set the tone 

for how EPA and other federal and state regulatory bodies will approach CCS 

going forward. 

This rulemaking will also set the tone for how the public perceives CCS. Public 

acceptance is a crucial linchpin to any meaningful CCS program. This point was 

emphasized in a 2007 National Academy of Sciences report, which noted that a 

large-scale CCS program cannot be successful "if a significant fraction of the 

public views it as dangerous or unacceptable." (National Research Council, NAS, 

Prospective Evaluation of Applied Energy Research and Development of DOE (Phase 

Two) (2007). 

Response: The GS regulation will provide certainty to industry and the public by providing consistency 

in requirements across the U.S. and transparency about what requirements apply to owners or operators. 

Furthermore, the tailored requirements in the GS rule will help allay public concerns about the 

technology and its impacts on USDWs and, in turn, promote acceptance of GS projects. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission Associates Comment ID: 22241

Commenter Name: James T. Sims Letter ID: 0249

Commenter Organization: Western Business Roundtable Comment ID: 22255

64
ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; and the Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research, and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

Comment: One of the biggest impediments to commercial-scale CCS projects today is 

regulatory uncertainty. Meaningful investments in CCS will only occur in the 

presence of clear, carefully tailored regulatory constructs that help encourage 

early and robust development of projects and which aid in eliminating liability 

risk for such early investments. In that regard, we appreciate EPA’s statement, 

in the rule’s preamble, that it recognizes CCS as a key climate change 

mitigation technology and that the rule is intended to support its development. 

With that goal in mind, we would offer the Agency the following thoughts on how 

the proposed regulations might be clarified and strengthened: 

Response: EPA believes that the GS regulation will provide regulatory certainty and oversight that 

operators have requested, and allow for the deployment of this key climate change mitigation 

technology that could be deployed to reduce CO2 emissions. EPA adds that the GS rule does not 

promote or encourage the use of GS; rather, it is designed to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Please see the remainder of EPA's responses to this comment letter for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Other EPA Comment Codes and Descriptions: 2020 1.5.1 Support Class VI designation 

Comment: D. General Comments 

Timing of promulgation 

The proposed rule is based on a risk management approach and is written in a way 

that should avoid unintended consequences to USDWs. It is important to bear in 

mind that CO2 injection projects can already be permitted today. While this may 

be adequate to protect USDWs in certain cases, it is in the interests of the 

public (and the regulated industry) to have a new injection class, designed from 

Commenter Name: James T. Sims Letter ID: 0249

Commenter Organization: Western Business Roundtable Comment ID: 22258

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22282

65
the outset with the particular characteristics of GS in mind, as soon as 

possible. This is necessary in order provide certainty and adequately safeguard 

public health and the environment. If the final rule incorporates changes 

concerning the adaptive nature of the rule and permits, as our Environmental NGO 

Group suggests, the Agency, and its state counterparts, will be able to deal 

with such unintended consequences to USDWs through the rule’s performancebased 

provisions, review and a possible reissuance of permits if necessary, and by 

revising the rule text if appropriate. 

Response: EPA agrees that the tailored requirements for Class VI wells, pursuant to the final GS 

rulemaking, are necessary to address the unique nature of injecting large volumes of CO2 and to ensure 

that USDWs are protected from endangerment, and that a new well Class specific to GS is appropriate. 

The GS rule contains tailored requirements for the permitting, geologic site characterization, AoR and 

corrective action, well construction, operation, mechanical integrity testing, monitoring, well plugging, 

post-injection site care, and site closure of GS wells that directly address issues unique to the nature of 

large-scale CO2 injection for GS. 

EPA adds that it continues to monitor research being conducted on GS and will use this to inform its 

adaptive rulemaking approach. EPA plans, every six years, to collect and review data on GS projects to 

determine whether the appropriate amount and types of information and appropriate documentation are 

being collected, and to determine if modifications to the requirements are appropriate or necessary. 

Other EPA Comment Codes and Descriptions: 1640 1.3.4 CERCLA issues (seeking comment); 2020 

1.5.1 Support Class VI designation 

Comment: We consider the Phase III Deployment Phase of the Department of Energy’s (DOE) 

Regional Partnership Program to be very worthwhile, but we do not consider the 

completion of this program to be a prerequisite for either commercial 

implementation of CCS or for the promulgation of a sound and protective rule. 

The DOE’s program has limited funds available through appropriations, and its 

demonstration projects will be of limited scale and duration. In addition, it 

focuses as much or more on the optimum way to apply existing technologies as it 

does on fundamental research or even demonstrations that particular technologies 

"work." Our scientific and practical understanding and experience in GS itself, 

as well as in related underground injection activities, is sufficient to 

construct and operate the first large-scale, commercial plants in the U.S., 

provided they are regulated adequately. In that respect, we do not consider the 

proposed rule premature, but a very timely and necessary development. 

The rule itself, rather than individual permits, should assure that Class VI 

permits do not allow responsible parties to avoid CERCLA liability on grounds 

that a release constitutes a "federally permitted release" 

Response: EPA agrees that tailored requirements for Class VI wells are necessary to address the unique 

nature of injecting large volumes of CO2 and to ensure that USDWs are protected from endangerment. 

The GS rule contains tailored requirements for the permitting, geologic site characterization, AoR and 

corrective action, well construction, operation, mechanical integrity testing, monitoring, well plugging, 

post-injection site care, and site closure of GS wells that directly address issues unique to the nature of 

large-scale CO2 injection for GS. 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22283

66
EPA believes, as supported by the rule's administrative record, that sufficient data and experience 

currently exist to develop UIC regulations for GS wells. The GS rulemaking builds upon decades of 

knowledge about safe injection practices. While developing the GS regulation, EPA has evaluated 

relevant GS research, including projects conducted by the seven regional carbon sequestration 

partnerships funded by the U.S. Department of Energy and coordinated through the National Energy 

Technology Laboratory (NETL), and several international projects. Additionally, EPA's Office of Water 

continues to fund research at the Lawrence Berkeley National Laboratory examining the effects of CO2 

interaction with ground water aquifers and any potential mobilization of trace elements that may occur.

CERCLA exempts from liability, under CERCLA section 107, 42 U.S.C. 9607, certain "federally 

permitted releases" (FPR) as defined in CERCLA, 42 U.S.C. 9601(10). Therefore, Class VI 

requirements and permits will need to be carefully structured to ensure that they do not 'authorize' 

inappropriate releases, and would need to prevent potential releases from the well which are outside the 

scope of the Class VI permit. Furthermore, EPA is promulgating the GS rule under the authority of the 

SDWA. To the extent the commenter is seeking interpretations of CERCLA and its related provisions, 

such as the definition of a federally permitted release, such interpretations are beyond the scope of this 

rulemaking. 

The UIC program Director has authority under SDWA §1423 to address potential compliance issues 

(e.g., potential releases that may endanger USDWs) resulting from injection violations in the unlikely 

event that a remedial response is necessary. Although EPA anticipates that the need for emergency or 

remedial actions at GS sites will be rare, the GS rule requires, at §146.94, that emergency and remedial 

response plans be developed and updated to address such events and that owners or operators 

demonstrate that financial resources are set aside to implement the plans if necessary, per §146.85. 

Regarding long term liability, once an owner or operator has met all regulatory requirements under Part 

146 for Class VI wells and the Director has approved site closure pursuant to requirements at §146.93, 

the owner or operator will generally no longer be subject to enforcement for regulatory noncompliance. 

Furthermore, their financial instrument as required under §146.85 will be released if it was not used. 

However, even if a site closure is approved under §146.93, an owner or operator may be held liable for 

regulatory noncompliance (including violation of 40 CFR 144.12) in certain circumstances. For 

example, an owner or operator may be held liable for regulatory noncompliance even after site closure 

was approved if the Director relied on erroneous information (e.g., erroneous modeling data) provided 

by the owner or operator when approving site closure. 

Separate from EPA's authority to enforce regulatory compliance, an owner or operator may be subject to 

a §1431 response order even after proper site closure is approved under §146.93. Under §1431 the 

Administrator may require an owner or operator to take necessary response measures if he or she 

receives information that a contaminant is present or is likely to enter a public water system or an 

USDW, which may present an imminent and substantial endangerment to the health of persons, and the 

appropriate State and local authorities have not acted to protect the health of such persons. The action 

may include issuing administrative orders or commencing a civil action for appropriate relief against the 

owner or operator of a Class VI well. If the owner or operator fails to comply with the order, they may 

be subject to a civil penalty for each day in which such violation occurs or failure to comply continues. 

Furthermore, after site closure an owner or operator may remain liable under tort and other remedies, or 

under other federal statutes including, but not limited to, Clean Air Act, 42 U.S.C. §§7401-7671; 

CERCLA, 42 U.S.C. §9601-9675; and RCRA, 42 U.S.C. §6901-6992. EPA does not have authority to 

transfer SDWA or other legal liability for Class VI wells to the State or federal government or a thirdparty fund. See the final rule preamble for further discussion of EPA's final approach. 

67
EPA recognizes the significant amount of data generated by the DOE partnerships and agrees that 

sufficient data have been collected to inform the final GS rule. EPA has evaluated permits and reviewed 

operational data and information associated with the seven regional carbon sequestration partnerships 

funded by the U.S. Department of Energy and coordinated through the National Energy Technology 

Laboratory. EPA believes that these projects form a solid basis for finalizing the GS requirements, and 

agrees there is no reason to wait until all phases of the DOE demonstration tests are complete. 

Comment: Process for permit review by experts 

We recommend that EPA consider establishing a process to collect input from 

experts to help inform EPA and states on evolving GS technology and appropriate 

policy and regulatory responses. Participants in the process should be 

independent, non-partisan, unbiased experts in the field, We recommend that the 

participants not be convened under the Federal Advisory Committee Act. Their 

opinions would be non-binding. Obtaining such input would help regulators 

improve their permitting decisions and would be complementary to the objectives 

of increased funding and resources for the UIC Program, outlined below. 

Response: The final rule is based on the most recent GS-related data, information, and scientific 

research available. EPA believes that sufficient data have been collected to inform the final GS rule. 

Nevertheless, EPA anticipates that future experimental and full-scale projects will continue to inform the 

technology, and is therefore using an adaptive rulemaking approach. EPA plans, every six years, to 

collect and review data on GS projects to determine whether the appropriate amount and types of 

information and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. 

Please see the remainder of EPA's responses to this comment letter for further details. For additional 

information on EPA's final regulatory approach, including the discussion of the public participation 

requirements, please see the final rule and preamble as well as the rulemaking docket. 

Comment: Carbon sequestration is a unique type of injection undertaken for a unique and 

critical purpose. It is not hydrocarbon storage nor is it industrial hazardous 

waste disposal. A hybrid approach should be taken in the development of rules 

that will facilitate the expeditious deployment of CCGS technology on a large 

and commercial scale. The development of rules for Class VI CO2 injection wells 

should logically begin with the existing rules for Class II enhanced oil 

recovery (EOR) wells using CO2 thereby building on the experience of 30+ years 

during which these type of CO2 wells have been in operation. From this starting 

point, CCGS rules can be tailored to account for the unique features of 

geologically sequestered CO2; namely large volumes, reactivity of CO2 in the 

presence of water, buoyancy, mobility, and extremely long time period of 

sequestration. Beginning with existing rules for Class I industrial wells as a 

reference for the proposed rule (page 43503 of the federal register notice) 

sends the message that injection of CO2 for geologic sequestration is akin to 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22286

Commenter Name: Walter L. Baker Letter ID: 0253

Commenter Organization: Utah Division of Water Quality Comment ID: 22338

68
industrial waste disposal rather than management of the major greenhouse gas it 

is. 

Response: EPA clarifies that the GS rule does not promote or encourage the use of GS; rather it ensures 

consistency in permitting underground injection of CO2 at GS operations across the United States and 

provide requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to 

reduce CO2 emissions. EPA adds that the GS regulation builds upon the long-standing protective 

framework of the UIC Program, which has been regulating the injection of billions of gallons of fluids 

for decades, including wells used for enhanced oil recovery. It includes requirements that address the 

unique technical criteria for permitting GS wells that are tailored the existing UIC regulatory framework 

to address the unique nature of CO2 injection for GS. 

Please see the remainder of EPA's responses to this comment letter for further details. For additional 

information on EPA's final regulatory approach, including the discussion of how this rulemaking affect 

existing injection wells under the UIC Program, please see the final rule and preamble as well as the 

rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1680 1.3.8 Don't overstate risk, don't stigmatize CO2 

Comment: ExxonMobil has participated extensively in the preparation of the comments 

submitted by the American Petroleum Institute (API) on this proposed rule and 

endorses their comments. We share the concerns raised by the API in their 

comments. Specific concerns are with use of the Class I UIC (Industrial/Hazardous 

Waste) program as the basis for the proposed rules, the proposed prohibition of 

injection above the lowermost underground source of drinking water, and the 

proposed 50 year post closure monitoring period. In each of these cases, the EPA 

has not fully leveraged on industry's successful experience with the Class II EOR 

program and instead, by building on the Class I program, is proposing 

requirements that are overly restrictive and could have a significant chilling 

effect on the commercial scale implementation of GS. It is our position Ihat 

ExxonMobil's and industry's experience with CO2 based EOR provides a sound basis 

from which to form an environmentally sound regulatory framework for GS. 

Response: EPA disagrees that the GS regulation is overly restrictive. EPA recognizes that injecting 

large volumes of CO2 for GS poses unique challenges that, if not properly managed, could endanger 

drinking water sources and have other adverse impacts. However, with proper site selection, the final, 

tailored, Class VI requirements address the large volumes of CO2 injected, its buoyancy, potential 

corrosivity in the presence of water, and potential impurities in the CO2 stream. In addition, EPA 

expects the tailored permitting, siting, construction, operation, monitoring, and post-injection site care 

requirements in the GS rule to prevent leakage from injection formations and protect USDWs. 

While EPA recognizes that industry has decades of experience injecting CO2 for ER, EPA believes that 

injection for the primary purpose of long term storage is sufficiently different from Class II ER 

operations and warrants tailored requirements. For example, the volume of CO2 anticipated to be 

injected in Class VI wells is significantly greater than for Class II wells. Reservoir pressure conditions 

will also be different, with Class VI injection operations involving large volumes of CO2 and likely 

having higher pressures within their storage formations than Class II ER projects. 

EPA adds that the intent of the GS rule is not to promote CCS; rather, the purpose of the rule is to ensure 

Commenter Name: Ken Miller Letter ID: 0257

Commenter Organization: ExxonMobil Production Company Comment ID: 22369

69
that, where deployed, GS performed in a manner that protects USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 1000 1. General and Administrative Comments 

Comment: In conclusion, ExxonMobil is committed to working with the EPA individually 

and through the API and other groups to develop scientifically sound, 

performance based regulations for the geologic storage of C02. Each of the areas 

of concern we have identified are more fully addressed in API's comments. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment and API’s comment for further details. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: The NAM also supports establishment of a single and transparent regulatory 

structure that applies to CCS rather than a patchwork of regulatory and 

liability statutes that were designed to regulate activities completely 

unrelated to CCS. To this end, the NAM would support a continued dialogue with 

EPA and other regulators in order to craft a new and modern structure specific 

to CCS, and established in such a manner that will expedite its deployment, 

while not hindering the refinement and improvement of the process. 

Response: EPA acknowledges that GS falls within the broader context of CCS and the need for 

regulatory clarity to ensure that USDWs are protected from endangerment. In developing the final GS 

rule, the Office of Water coordinated with other Agency program offices and across federal agencies 

(e.g., with the Department of Energy; United States Geological Survey; Bureau of Ocean Energy 

Management, Regulation, and Enforcement, formerly the Minerals Management Service; and the 

Bureau of Land Management). The Agency continues to evaluate areas of potential applicability of other 

Federal environmental statutes including, but not limited to: the Clean Air Act; the Resource 

Conservation and Recovery Act; the Comprehensive Environmental Response, Compensation, and 

Liability Act; and the Marine Protection, Research, and Sanctuaries Act to various aspects of GS and 

CCS. The Agency will continue to coordinate on GS- and CCS-related issues to minimize redundancy 

and maximize efficiencies for owners or operators. For additional information, please see the discussion 

entitled "How Does This Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" 

in the preamble to the final GS rule. 

Comment: First we stress again the importance of promulgating adequate regulations for GS 

in a timely fashion. GS has an important role to play in reducing carbon dioxide 

emissions in the U.S. and, although projects can be permitted under existing 

rules, a dedicated set of regulations is needed both to increase certainty 

further but also adequately to safeguard human health and the environment. 

Therefore, in considering whether a Notice of Data Availability (NODA) is 

needed, we urge EPA to choose the most expeditious option that is accountable, 

transparent, legally robust and defensible, and also to ensure that whichever 

Commenter Name: Ken Miller Letter ID: 0257

Commenter Organization: ExxonMobil Production Company Comment ID: 22371

Commenter Name: Keith McCoy Letter ID: 0258

Commenter Organization: National Association of Manufacturers Comment ID: 22375

Commenter Name: George Peridas Letter ID: 0291

Commenter Organization: Natural Resources Defense Council Comment ID: 25285

70
option is chosen does not delay the promulgation of the rule. 

Response: EPA clarifies that the GS rule does not promote or encourage the use of GS; rather it is 

designed to ensure consistency in permitting underground injection of CO2 at GS operations across the 

United States and provide requirements to prevent endangerment of USDWs in anticipation of the 

eventual use of GS to reduce CO2 emissions. EPA believes that the GS regulation will provide 

regulatory certainty and oversight that operators have requested, and allow for the deployment of this 

key climate change mitigation technology that could be deployed to reduce CO2 emissions. 

Please see the remainder of EPA's responses to this comment letter for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: The Sierra Club will be submitting comments, written comments to the EPA 

addressing more specifics about this type of permit. But in closing, we want to 

urge the EPA to look at this in a more holistic manner and not piecemeal this 

into just a drinking water issue. The entire purpose of this permit, according 

to U.S. EPA is to keep CO2 emissions out of the atmosphere. Thank you. 

Response: EPA acknowledges that GS falls within the broader context of CCS and the need for 

regulatory clarity to ensure that USDWs are protected from endangerment. In developing the final GS 

rule, the Office of Water coordinated with other Agency program offices and across federal agencies 

(e.g., with the Department of Energy; United States Geological Survey; Bureau of Ocean Energy 

Management, Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of 

Land Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

Please see the remainder of EPA's responses to this comment and to Sierra Club's written comment for 

further details. For additional information on EPA's final regulatory approach, please see the final rule 

and preamble as well as the rulemaking docket. 

Comment: I wanted to make a few points this afternoon. First, I wanted to ask that the 

comment period be extended. These are very complicated issues for IGCC and for 

carbon capture and sequestration. I notice that EPA's six to nine months late in 

doing its due diligence on this topic and because of the complication of the 

process and the complication of the science and of course, the public is even 

less able to comprehend these issues than EPA is so I am asking you today, to 

give us a six month extension for public comment on this. It does not seem fair 

to ask us to do the hustle to respond in thirty days. 

Commenter Name: Becki Clayborn Letter ID: 0509

Commenter Organization: Sierra Club Comment ID: 21205

Commenter Name: Becky English Letter ID: 0524

Commenter Organization: Sierra Club Comment ID: 21482

71
I was wondering if this might have been part of a pattern that some of us have 

noticed at EPA for some hurry up processing before the Bush administration runs 

out. Some of us frankly do not quite trust Administrator Johnson's motives in 

this and we think we need to have some time to digest this process. 

Congress has been in a continuing resolution mode producing anyway and there is 

new information coming out as I know you are even more aware of than I am about 

some actual leaks of CO2 in process and these, of course, would need to be 

considered not only by EPA, but by the public and so I do not know if this is a 

discursive mode, but I want to ask you a question of process. Is my requesting 

this extension, does that mean it will happen or do we need to file a formal 

extension request? 

Response: EPA acknowledges the comment. EPA did extend the comment period for the proposed rule 

by an additional 30 days. Please see the remainder of EPA's responses to this comment and to Sierra 

Club's written comment for further details. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment Code: 1210 1.1.1 Comments about the proposed rule 

Individual Comments 

Other EPA Comment Codes and Descriptions: 1310 1.1.2.4 Comments on other "out of scope" 

issues, e.g., pore space ownership 

Comment: We believe the following issues warrant additional review by the 

Environmental Protection Agency: 

1. The potential negative impact to large CO2 deep saline formation geologic 

sequestration projects resulting from the reference in these regulations to 

storage rather than disposal, implying the CO2 may have value or is even 

actually a commodity. Large projects could have a CO2 plume covering many square 

miles. The reference to storage may result in the operator having to rent or pay 

for the use of pore space for storage, which may involve dealing with numerous 

parties, considerable legal work and considerable costs. 

2. The potential adverse impact to Class I industrial waste disposal well 

program that could result from the concept of storage described in above item 

#1. 

Response: EPA acknowledges that issues such as pore space ownership and surface and subsurface 

property rights are important issues that need to be addressed; however, these are generally addressed 

though state regulations and are outside of the UIC program’s authority under the Safe Drinking Water 

Act (SDWA). EPA adds that the requirements apply to owners or operators of injection wells used to 

Commenter Name: Michael H. Cochran Letter ID: 0108

Commenter Organization: Bureau of Water, Division of Environment, Kansas 

Department of Health & Environment (KDHE)

Comment ID: 

21942

72
inject CO2 for permanent storage, and do not apply to owners or operators of Class I wells.

EPA believes that developing a consistent regulatory framework will ensure that there is adequate 

opportunity for public involvement on the permitting process and that all USDWs are protected from 

endangerment. 

Comment: Dialogue between the Regulated and Regulator Isn’t Obvious The draft Class VI 

rule and especially the preamble assert numerous times that a key to ensuring 

the safety and efficacy of geologic sequestration is a well functioning dialogue 

between the regulated entity and the regulatory agency. There are at least 

three intertwined concerns I have with the way the current draft Class VI rule 

is written that if left unresolved would hamper a robust, meaningful dialogue 

between the regulated entity and the regulator has been created by this rule. 

1) The concept that there is "working" relationship between the permitee and the 

permit-granting agency doesn’t really come through here. This seems like a very 

arms length relationship. 

2) The draft rule never establishes that the process of moving from initial site 

selection to permitting, to operations to renewal of permits to closure is an 

iterative one between the operator and the EPA or state permit writer (acting as 

stewards of the public’s welfare) as new data are generated and incorporated 

into the site management plan. That is, the rule could do a much better job of 

explaining that the permittee and the regulator should be learning a great deal 

about how a particular geostorage field is operating in practice and that this 

knowledge will be factored into how the field is regulated in the future 

(including decisions about post closure). 

3) Data is collected but it is not clear how it is used by the regulator nor is 

it clear who has access to this data. In particular, there appears to be only 

two instances (one at the very earliest stages of site selection and the other 

before site closure) where the public is invited to learn and comment on a GS 

project. 

Given that humanity is in the early days/decades of CCS deployment, it seems to 

me that much could be learned by having closer and more frequent communication 

between the regulator and owner/operator of a GS project, and allowing for some 

dissemination of the massive amount of data generated by these projects. A more 

transparent and meaningful dialogue between these two parties would also help 

with stakeholder acceptance of CCS. 

Response: EPA agrees that communication and coordination between owners or operators and 

permitting authorities are important. The GS rule incorporates a flexible approach, where operators of 

GS projects develop and implement site-specific plans for delineating the AoR, performing corrective 

action, testing and monitoring, and post-injection site care. EPA believes that the plans—which will be 

reviewed and approved by the Director and periodically updated throughout the life of the project—

promote an ongoing dialogue between the operator and the Director that will encourage use of the most 

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific 

Northwest National Laboratory

Comment ID: 

22643

73
appropriate technologies for a particular project and that GS projects are permitted sited, constructed, 

operated, and closed in a manner that avoids releases of CO2 into USDWs. 

EPA is developing a number of technical guidances and implementation materials to assist owners or 

operators and Directors in the permitting process. These guidances will address how to perform many of 

the activities necessary for applying for a permit, including developing all required plans and conducting 

site characterizations that meet the requirements of §146.82. The guidances will be available on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm 

Comment: Who has access to reports on an ongoing GS project? 

o Page 43517. It is asserted that the requirement for "monitoring, testing, 

AOR, and corrective action" plans will help establish "an ongoing dialogue 

between the operator and the permitting authority." This reviewer just doesn’t 

see this "dialogue" in this rule. There is no discussion of how these plans are 

used and therefore this looks like a very distant and at arms length process. I 

am 100% in support of there being an ongoing dialogue between the operator and 

the regulator and I believe that these additional plans are a wise requirement 

for Class VI GS wells. 

Response: EPA believes that the plans site-specific plans for delineating the AoR, performing corrective 

action, testing and monitoring, and post-injection site care —which will be reviewed and approved by 

the Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project and that GS projects are permitted sited, constructed, operated, and closed in a manner 

that avoids releases of CO2 into USDWs. 

EPA is developing a number of technical guidances and implementation materials to assist owners or 

operators and Directors, including a guidance that describes recommended approaches for developing, 

reviewing, and updating the GS project plans. The guidances will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: - Page 43497. To the extent that EPA will revise this preamble language, please 

consider ending the section on "Potential USDW Impacts" with a new sentence that 

reaffirms that the purpose of this proposed rule is to put in place regulations, 

best practices, enforcement mechanisms, etc. to ensure that all of the 

previously mentioned bad things that could go wrong with a CO2 storage project 

do not take place. This reviewer thinks that given the negative tone of much of 

the material in this section it is appropriate for the USEPA to reinforce the 

point that the purpose of this rule is to ensure that CO2 storage is done safely 

thus significantly reducing if not eliminating the extent to which any of these 

things actually happen. 

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific 

Northwest National Laboratory

Comment ID: 

22649

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific 

Northwest National Laboratory

Comment ID: 

22655

74
- Page 43495 under "Why is Geologic Sequestration Under Consideration". Please 

change sentence which says in part "he capture and storage of CO2 would enable 

the continued use of coal in a manner that" The first deployments of CCS are 

not going to be at coal fired electric power plants. There is no reason for 

this rule to be overly focused on coal based CCS applications and is not 

appropriate for this Class VI UIC rule since it is bounded by the SDWA which 

means that the source of CO2 is not a critical aspect of this rule. Focusing on 

coal can also bring in a lot of ancillary (although important) issues 

surrounding the use of coal like mining practices that do not need to be 

discussed within the boundaries of a proposed Class VI UIC rule. CCS is more 

than just coal. 

Response: EPA clarifies that the intent of the Class VI GS requirements are designed to ensure that, 

where deployed, GS is conducted in a manner that protects USDWs from endangerment. Please see the 

final rule and preamble for additional information on EPA's final approach. 

Comment: establishment of the new Class VI well category for CO2 injection but advises 

EPA not to adapt more restrictions on it than found in the Class I hazardous 

waste wells. Many of the construction, mechanical integrity, monitoring and 

financial assurance provisions for Class VI are more comprehensive and more 

strict that those for Class I. EEI comments on the topic suggest: "EPA should 

avoid risk management approaches that discourage CCS deployment or create 

additional uncertainty, and to seek where possible to bring greater certainty to 

the long term obligations and risks associated with a GS project. " As a 

Response: EPA disagrees that the requirements in the GS rule are overly stringent. 

The Agency believes that all of the requirements for GS wells are necessary to ensure that GS is 

conducted in a manner that protects USDWs from endangerment. 

EPA developed the Class VI regulations in recognition that the risks posed by GS to USDWs are 

fundamentally different than those associated with current injection practices regulated by the UIC 

program, including Class I hazardous waste injection wells. For example, CO2 is more buoyant, less 

viscous (i.e., more mobile), and in some cases more corrosive than fluids injected into Class I hazardous 

waste wells. In addition, the large injection volumes anticipated for GS will likely be much greater than 

current injection practices. Lastly, CO2 movement in the subsurface is not as well understood as fluids 

currently injected under the Class I program. 

Please see the remainder of EPA’s responses to this comment for further details related to construction, 

mechanical integrity, monitoring and financial responsibility for Class VI wells. 

Comment: DIRECTOR DISCRETION 

USWAG advises; "While directorial discretion is a useful mechanism to ensure 

flexibility in the Final Rule, such discretion must be clearly defined and 

limited." DTE Energy endorses this comment and also acknowledges that we have 

Commenter Name: Skiles Boyd Letter ID: 0160

Commenter Organization: DTE Energy Comment ID: 21274

Commenter Name: Skiles Boyd Letter ID: 0160

Commenter Organization: DTE Energy Comment ID: 21276

75
had reasonable interactions with our state and regional regulators on other UIC 

wells. We do recognize this is one mechanism to ensure that needed flexibility 

but there should be some boundaries and limitations as to the extent of 

discretion provided the Director. 

Response: EPA is developing guidances for States that describe the process of applying for and 

receiving primary enforcement authority (primacy) for GS Class VI wells under Section 1422 of 

SDWA, as well as the technical and administrative issues on developing GS regulations that are the 

equivalent of minimum federal criteria and requirements. The guidance will describe areas of Directorial 

discretion and considerations for how that discretion would be exercised. This guidance will be available 

on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: API has serious concerns with several sections of the proposed rule, including 

the lowermost USDW restriction, the 50-year post-injection site care 

requirement, the well construction and operation requirements and the 

definitions of Geological Sequestration Project and Area of Review which we 

ddress below. API also offers detailed revisions to address these issues and 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this letter 

for further details. 

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells 

(seeking comment) 

Comment: API offers many technical clarifications to the rule based on industry's 

experience with well design, construction, and operation. Some are minor 

clarifications but others are important revisions. For example, EPA is proposing 

the use of down-hole shut-off valves (see proposed §146.88(e) at 73 FR 43539), 

saying they would "isolate the injectate below USDWs, rather than just below the 

surface" (73 FR 43511) when in fact, down-hole shut-off valves would not 

actually address this concern since they are not designed to provide the type of 

isolation envisioned by the EPA. 

Response: After evaluating the risks and benefits of down-hole shut-off systems and considering 

additional research, EPA will not require automatic down-hole shut-off devices for onshore Class VI 

wells since it is not necessary in all cases to ensure protection of USDWs from endangerment. Instead, 

the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells install 

automatic surface shut-off devices. The rule affords Director's discretion to mandate automatic downhole shut-off devices in onshore situations that may warrant their use. However, the Agency believes 

that offshore Class VI wells present unique construction and operational conditions, including isolation 

from shorelines and the need to construct wells through the water column and the subsurface, which 

may delay response time in the event of well difficulties. The rule requires, at §146.88(e)(3), that owners 

or operators of offshore wells within State territorial waters install automatic down-hole shut-off 

systems. EPA believes that these requirements at §146.88(e) ensure that proper precautions are taken to 

prevent subsurface fluid movement and ensure protection of USDWs. 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24118

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24119

76
EPA clarifies that down-hole shut-off devices are currently used in situations where loss of well 

integrity could result in damage to the well or harm to humans (e.g., near high-density population areas, 

or in onshore acid gas injection; IEA, 2003). EPA has identified examples of documented logging 

techniques, including ultrasonic and temperature logs, that can be performed with an automatic downhole device emplaced (Julian et al., 2007; Somaschini et al., 2009). They are also used in high pressure, 

high temperature onshore wells and in permafrost areas. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82) 

Comment: EPA should be aware that some provisions seem to be based on data and 

information that would actually be generated by the permitted activity and 

therefore would not be available at the time of submittal of the permit 

application. For example §146.82(c) requests data from wells that cannot be 

drilled until the permit is received. EPA proposed rules appear to contemplate 

delineation and evaluation activities prior to submittal of an application for 

GS wells/projects. It is not clear to API under what authority and regulatory 

framework these activities would be conducted since most Class VI projects will 

not be oil and gas related and so would not fall under oil and gas rules. 

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be 

available at the time the owner or operator develops their initial permit application. In response to 

comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this 

subpart so that the final regulation specifies separate requirements for information to be submitted with 

the permit application and before well construction is approved (at §146.82(a)) and information to be 

submitted before operation of the well is authorized (at §146.82(c)). 

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of 

information to be submitted. In addition, section §146.82 in the final rule is similar to the permit 

application requirements for other injection well classes, which could help avoid confusion about how to 

meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to 

be submitted before operation of the well is authorized are very similar to those for Class I wells, with 

modifications and additions that address the unique challenges and types of data collected for GS wells.

Comment: Monitoring, Corrective Action, Record Keeping, and Long-Term Liability 

Guidelines Needed: 

It would be helpful if additional guidelines were included in the rule to 

provide state regulatory authorities with the ability to determine requirements 

for monitoring, corrective action, record keeping, and liability of carbon 

sequestration injection well sites. Guidelines are needed to help states 

consider baseline geochemical analysis and monitoring data, as well as 

corrective action plans, in the event that a USDW becomes affected by an 

injection well site. Guidelines are also needed to ensure that the long-term 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24120

Commenter Name: James Taft Letter ID: 0172

Commenter Organization: Association of State Drinking Water Administrators 

(ASDWA)

Comment ID: 

23455

77
financial responsibility of owners/operators of injection wells adequately cover 

the potential costs of site closure and stewardship. While the rule should 

provide some minimum requirements for record keeping and the frequency of 

reporting, the rule should also be flexible enough to allow states to address 

site-specific conditions in determining these requirements. Common assumptions 

will need to be tested under the unique conditions of individual sites in order 

to avoid unintended consequences. 

Response: EPA believes that the Class VI requirements balance site-specific flexibility with USDW 

protection. Rather than setting performance or technology-based standards for GS projects, EPA is 

adopting a flexible approach, where operators of GS projects would develop and implement site-specific 

plans for delineating the AoR, testing and monitoring the site, performing corrective action, and postinjection site care. EPA believes that the plans—which would be reviewed and approved by the Director 

and periodically updated throughout the life of the project—promote an ongoing dialogue between the 

operator and the Director that will encourage use of the most appropriate technologies for a particular 

project. 

EPA is developing guidances for States that describe the process of applying for and receiving primary 

enforcement authority (primacy) for GS Class VI wells under Section 1422 of SDWA, as well as the 

technical and administrative issues on developing GS regulations that are the equivalent of minimum 

federal criteria and requirements. The guidance will describe areas of Directorial discretion and 

considerations for how that discretion would be exercised. This guidance will be available on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3140 2.1.4 Comments that the proposed geologic data 

requirements are too stringent 

Comment: • In many instances the proposed requirements for Class VI CO2 GS wells are 

unnecessarily more stringent than existing requirements for other well classes 

under the UIC Program. While it is essential that the Final Rule be protective 

of underground sources of drinking water ("USDWs"), many of the more rigorous 

requirements proposed for Class VI wells are not warranted by findings of unique 

risks posed by CO2 GS wells. The Final Rule should craft requirements that 

protect USDWs while avoiding the imposition of unnecessary costs or the creation 

of an unfounded negative public perception of CO2 GS projects. 

Response: EPA disagrees that the requirements at §146.82 are too stringent and believes that a detailed 

geological site characterization is essential to evaluating the presence and adequacy of the various 

geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic 

site characterization are based on a long standing UIC regulatory framework developed to address 

specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are 

appropriate for the unique nature of injecting large volumes of CO2 into a variety of geological 

formations for long-term storage. 

The mission of the UIC program and the goal of the GS regulation is to protect USDWs from 

endangerment, and every aspect of the GS rule is designed toward that end. Therefore, EPA disagrees 

that any of these protective requirements are unnecessary, and clarifies that waiving any of the 

requirements would not be acceptable. The GS regulation allows flexibility where appropriate. Certain 

requirements (e.g., the need to characterize additional confining layers) are at the Director's discretion 

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23460

78
(§146.83(b)), based on his or her understanding of a particular site. 

EPA disagrees that the requirements would negatively affect public perception of CO2 GS projects. 

Rather, EPA believes that a demonstration to the public that extensive data have been collected and 

evaluated would likely improve confidence in the project and help address public questions and 

concerns. 

Other EPA Comment Codes and Descriptions: 2020 1.5.1 Support Class VI designation 

Comment: The proposed Federal requirements under the Safe Drinking Water Act (SDWA) for 

underground injection of carbon dioxide for the purpose of geologic 

sequestration is a step forward. SSEB supports the establishment of a new Class 

VI designation specifically dealing with GS. A new class of wells with minimum 

technical criteria for the geologic site characterization, fluid movement, area 

of review (AoR) and corrective action, well construction, operation, mechanical 

integrity testing, monitoring, well plugging, post-injection site care, and site 

closure for the purposes of protecting USDWs will advance GS projects. The 

proposed rule will help to ensure consistency in permitting of underground 

injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual 

use of GS to reduce CO2 emissions. EPA’s regulatory provisions should accurately 

reflect the low risk profile that exists for CO2 exposure from a GS project. 

Response: EPA agrees that tailored requirements for Class VI wells are necessary to address the unique 

nature of injecting large volumes of CO2 and to ensure that USDWs are protected from endangerment. 

The GS rule contains tailored requirements for the permitting, geologic site characterization, AoR and 

corrective action, well construction, operation, mechanical integrity testing, monitoring, well plugging, 

post-injection site care, and site closure of GS wells that directly address issues unique to the nature of 

large-scale CO2 injection for GS. 

Comment: Site-Specific Approach 

Policy regarding GS siting should reflect that conditions affecting risk differ 

by site and should be tailored to risks presented by specific sites. For 

example, CO2 has been injected underground for several decades for EOR. This 

technique is well developed and there is now a history through which its risks 

can be assessed. This differs from injection for long-term storage in deep 

saline formations or unmineable coal seams, with which there is limited 

experience, particularly on the massive scale -- a million or more tons per year 

per site -- envisioned for the future. Policy must encourage development of new 

data, technology, and practices while recognizing that existing technology is 

readily applicable. It also should reflect that some long term injection 

practices such as natural gas storage and EOR already are known to pose little 

risk. Sites also will differ based on reservoir and confinement geological 

details, proximity to USDWs and other resources, and other factors. In addition, 

Commenter Name: Kenneth Nemeth Letter ID: 0176

Commenter Organization: Southern States Energy Board Comment ID: 23535

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23801

79
Response: EPA agrees that permitting decisions for GS wells should be based on site-specific factors. 

The GS rule requires owners or operators to submit, and Directors to consider, extensive site-specific 

data, specified at §146.82, to demonstrate that a site is suitable for GS. Additionally, many of the permit 

requirements for GS wells are established through individualized site-specific plans for AoR and 

corrective action, testing and monitoring, and injection well plugging and post-injection site care and 

site closure. EPA adds that the final GS rule includes a balance of specific criteria to be met by the 

owner or operator and areas of Directorial discretion. The Agency believes this balance allows for GS 

projects to be designed and permitted to address the unique, site-specific aspects of each project, while 

providing consistency in permitting across the U.S. 

EPA adds that the GS rule does not categorically preclude injection of CO2 into any formation types. 

The purpose of the GS rule is to ensure protection of USDWs from endangerment, and the rule requires 

that owners or operators demonstrate that wells are sited in suitable systems with geologic formations to 

receive and confine injected CO2, required at §146.83 of the GS rule. 

Other EPA Comment Codes and Descriptions: 1400 1.2 Comments on EPA's Authority to Regulate 

Injection of CO2 

Comment: The ELPC’s primary objection to the proposed regulation is that regulation of 

geologic sequestration under the SDWA is too narrow in focus to ensure that 

carbon capture and sequestration ("CCS") fulfills its potential to be "a key 

mitigation technology for achieving domestic [greenhouse gas] emissions 

reductions." 73 Fed. Reg. at 43,496. EPA is proposing to regulate GS by 

creating a new category of injection well ("Class VI") for GS under its existing 

UIC program under the SDWA. As EPA acknowledges, however, its authority under 

the SDWA is limited. See 42 U.S.C. 300h(a)-(b)(1), (d); 73 Fed. Reg. at 43,495. 

Other rules and regulations are needed to address CCS issues falling outside the 

scope of the SDWA (e.g., establishing mechanisms for protecting private drinking 

water supplies, funding costs and damages associated with injury to persons 

and/or water supplies despite compliance with the UIC regulations, accidental 

releases of CO2 to the atmosphere, and compensation for and remediation of harm 

to public health or the environment other than the endangerment of underground 

sources of drinking water ("USDWs")). See infra Part III(c)(1)(b); 73 Fed. Reg. 

at 43,495, 43,497, 43,520, 43,522 (discussing EPA’s view of CCS issues that fall 

outside purview of SDWA). Other issues related to the capture and transport of 

CO2 also need to be considered and addressed. 

Many of these issues are of critical importance and will likely need to be 

addressed before large-scale industry investment in CCS will take place. See, 

e.g., infra Part III(C)(1)(b)(ii) (discussing industry’s need for a clear and 

comprehensive long-term liability scheme). Piecemeal regulation of CCS is 

likely to cause confusion, inefficiency, potentially conflicting requirements or 

policies, and other problems that could be avoided by a comprehensive approach 

to regulation of CCS. Although ELPC and ETIP believe comprehensive regulations 

addressing CCS would more likely ensure that CCS becomes a successful climate 

change mitigation technology, we recognize that Congress may need to enact 

legislation enabling EPA (or another federal agency) to take such a 

comprehensive approach. 

Commenter Name: Wendy Jacobs Letter ID: 0183

Commenter Organization: Harvard Law School Environmental Law and Policy 

Center

Comment ID: 

25137

80
Response: EPA received a number of comments indicating that the Agency should further explore 

environmental and regulatory issues beyond the scope of the GS rule as proposed. This comment is 

outside the scope of this rulemaking. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

Other EPA Comment Codes and Descriptions: 3800 2.3 Proposed Injection Well Construction 

Requirements (40 CFR 146.86) 

Comment: ELPC and ETIP commend EPA for including precautionary measures for Class VI 

wells above and beyond what is required for other classes of wells. The 

proposed regulation allows the owner or operator the flexibility to choose 

particular cements or metal well components for Class VI wells while still 

requiring that such materials meet or exceed the standards developed by the 

American Petroleum Institute, ASTM International or comparable standards 

acceptable to the Director. 73 Fed. Reg. at 43,537 (proposed 40 C.F.R. § 

146.86(b)(1)). By doing so, the proposed regulation addresses the potential 

corrosion of cement and metal well components by the CO2 stream (plus water 

impurities) that can compromise the structure of the well and result in leaks of 

stored CO2. ELPC and ETIP laud other precautionary measures required in the 

proposed regulation, including down-hole shut off valves, continuous and 

frequent monitoring of the integrity of the internal and external portions of 

the well, tracking the plume and pressure front, and detailed electronic record 

keeping. Id. at 43,511, 43,538-40 (proposed 40 C.F.R. §§ 146.88-.91). The 

requirements in the proposed regulation reflect EPA’s understanding of and 

sensitivity to the challenges posed by CCS. Because CO2 GS entails new 

technology with a potentially large impact and lasting duration, ELPC and ETIP 

support these precautionary measures. 

Response: EPA acknowledges the comment and agrees that protection of USDWs from endangerment 

and prevention of fluid movement between formations is paramount. Appropriately designed and 

constructed wells are necessary to prevent endangerment to USDWs and maintain integrity of the well 

throughout the lifetime of a GS project. This is the foundation of the requirements for construction and 

pre-operational testing of Class VI wells at §§146.86 and 146.87. 

Commenter Name: Wendy Jacobs Letter ID: 0183

Commenter Organization: Harvard Law School Environmental Law and Policy 

Center

Comment ID: 

25139

81
Please see the remainder of EPA's responses to this comment and the final rule and preamble for further 

details. 

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performance-based 

standards); 1420 1.2.1.1 Support the GS rulemaking 

Comment: Protection of U.S. Drinking Water (USDW) sources is paramount and a central 

requirement of the Safe Drinking Water Act and ConocoPhillips wholeheartedly 

supports high standards for protection of current and potential future USDWs. We 

believe that maintaining focus on several key principles can ensure rulemaking 

that is protective and flexible to allow site specific considerations while 

maintaining cost-effective operations. We applaud EPA's work to that end. We 

support most concepts, elements and details in the proposed requirements, and 

provide our comments to reinforce and amplify a few issues which we believe flow 

from the following important key principles: 

o All UIC well classes have requirements fully designed to protect USDW's. 

o The oil and gas industry's experience with CO2 injection for enhanced oil 

recovery (EOR) provides a track record of USDW protection that can enhance EPA's 

rulemaking. 

Response: EPA believes that the creation of a new injection well class (VI) under the existing UIC 

Program is necessary to enable the use of GS as a climate change mitigation technology in a manner that 

protects USDWs from endangerment. EPA agrees that the UIC Program, under the authority of the 

SDWA, provides a strong framework for regulating injection of CO2 for GS and adds that the GS 

regulation tailors the UIC requirements to address the unique issues associated with large-scale GS 

including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, 

the potential presence of impurities in captured CO2, and its mobility within subsurface geologic 

formations. 

EPA recognizes that the oil and gas industry has decades of experience injecting CO2 for the purpose of 

ER, and that sites used for ER may be suitable for GS and may be among the first GS sites. Some of the 

research that informs the final GS rule was conducted at ER sites. EPA also recognizes that a by-product 

of ER activities is that a certain percentage of the CO2 is trapped in the receiving formation. 

Other EPA Comment Codes and Descriptions: 1260 1.1.1.5 More certainty/stringency is needed 

Comment: Issue 2. Under the proposed rule, full-scale implementation can begin after 

finalization. 

The EPA is encouraged to consider limiting the scale of projects initially in 

order to identify issues that may crop up that are currently unanticipated. The 

early large scale projects should be extensively monitored in order to validate 

concepts that can be applied to other locations. This early work should include 

validation of appropriate modeling techniques capable of reliably predicting 

system responses. This early proof of concept work should also address issues of 

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23887

Commenter Name: Andy Horn Letter ID: 0196

Commenter Organization: Colorado Ground Water Association (CGWA) Comment ID: 23922

82
heterogeneity in reservoir and confining zones. 

Response: EPA clarifies that the intent of the GS rule is not to set or control the pace at which GS is 

deployed. Rather, the purpose of the GS regulation is to ensure that GS, where deployed, is conducted in 

a manner that protects USDWs from endangerment. The Class VI GS requirements are one way in 

which the Agency can achieve this goal. EPA does not intend to limit the scale of initial GS projects; 

each project will be evaluated based on site-specific information about the ability of the geologic 

formations to safely receive and confine injected CO2. However, the Agency agrees that a protective 

initial approach is appropriate and additional safeguards are necessary, given the uncertainty associated 

with the long-term effects of CO2 GS. EPA plans, every six years, to collect and review data on GS 

projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Comment: 12. EPA’s implied 2017 date for completion of the final UIC regulations is too 

late to provide regulatory clarity faced by CCS project developers today. These 

are the details supporting these concerns and recommendations: 

Response: EPA believes that sufficient data have been collected to inform the final GS rule. In addition 

to laboratory studies and modeling research that provide relevant information on GS, the Agency is also 

collecting and analyzing GS project data and permit information from a variety of sources. Most 

notably, EPA has evaluated permits and reviewed operational data and information associated with the 

seven regional carbon sequestration partnerships funded by the U.S. Department of Energy and 

coordinated through the National Energy Technology Laboratory. EPA believes that these projects form 

a solid basis for finalizing the GS requirements, and there is no reason to wait until all phases of the 

DOE demonstration tests are complete. Nevertheless, EPA anticipates that future experimental and fullscale projects will continue to inform the technology, and is therefore using an adaptive rulemaking 

approach. EPA plans, every six years, to collect and review data on GS projects to determine whether 

the appropriate amount and types of information and appropriate documentation are being collected, and 

to determine if modifications to the requirements are appropriate or necessary. EPA believes that the 

completion of the DOE pilots in 2017 will allow the incorporation of results of these projects into the 

first review of the rule. 

Comment: Concern #12: EPA’s schedule for promulgation of its proposed UIC regulation. 

(Page 43499 Sec. E3) 

We reference the following statement from the preamble section of the proposed 

rule: "During the Deployment Phase (2008-2017), the [RCSP] partnerships will 

conduct large volume carbon storage tests to demonstrate that large-scale CO2 

injection and storage can be achieved safely and economically. EPA will use the 

data collected from these projects to support decisions in the final GS rule." 

This statement suggests that a final GS rule may not be issued until 2017. We 

believe that this is too late to clear the regulatory uncertainty that CCS 

project developers are facing today. If this reflects EPA’s intention, we 

recommend that EPA abandon a prescriptive approach and instead, favor general 

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22703

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22718

83
and performance-based requirements until these demonstration tests are 

completed. Other concerns expressed by our membership and recommendations for 

improvement of the proposed rulemaking are given in Appendix A. Should the EPA 

have further questions, please fell free to contact me. 

Response: EPA believes that sufficient data have been collected to inform the final GS rule. In addition 

to laboratory studies and modeling research that provide relevant information on GS, the Agency is also 

collecting and analyzing GS project data and permit information from a variety of sources. Most 

notably, EPA has evaluated permits and reviewed operational data and information associated with the 

seven regional carbon sequestration partnerships funded by the U.S. Department of Energy and 

coordinated through the National Energy Technology Laboratory. EPA believes that these projects form 

a solid basis for finalizing the GS requirements, and there is no reason to wait until all phases of the 

DOE demonstration tests are complete. Nevertheless, EPA anticipates that future experimental and fullscale projects will continue to inform the technology, and is therefore using an adaptive rulemaking 

approach. EPA plans, every six years, to collect and review data on GS projects to determine whether 

the appropriate amount and types of information and appropriate documentation are being collected, and 

to determine if modifications to the requirements are appropriate or necessary. EPA believes that the 

completion of the DOE pilots in 2017 will allow the incorporation of results of these projects into the 

first review of the rule. 

Other EPA Comment Codes and Descriptions: 2064 1.5.3.2 Grandfathering construction of Class II 

wells (seeking comment) 

Comment: C. The Proposed Class VI Requirements Are Far More Burdensome than Necessary to 

Protect USDWs. 

As the preamble acknowledges, the actual human health and ecological risks 

associated with GS are relatively remote and can be addressed effectively 

through measures implemented to protect USDWs. 73 Fed. Reg. at 43497-98. 

Unfortunately, the proposed rule seems to proceed from the premise that the 

strictest UIC regulations in existence - those for hazardous waste injection - 

should serve as the starting point for the development of the Class VI 

regulations. Given the vast knowledge and experience developed through the 

handling of CO2 in different operations, SEPCo contends that the more logical 

starting point for development of the Class VI regulations is the Class II 

regulations. 

As the proposed rule recognizes, CO2 injection operations have been conducted 

pursuant to the Class II regulations for many years, and experience with 

thousands of wells injecting hundreds of millions of tons of CO2 demonstrates 

that the Class II regulations - as applied to CO2 injection - are adequate to 

protect USDWs This is certainly true with respect to the basic construction, 

operating, monitoring, and mechanical integrity testing requirements for 

injection wells; we believe that what "works" in terms of the construction and 

operation of a CO2 injection well does not depend on the purpose for which CO2 

is being injected. 

Unfortunately, the proposed Class VI requirements are far more stringent than 

the Class II requirements, a fact that gives rise - under the proposed rule - to 

Commenter Name: John King Letter ID: 0211

Commenter Organization: Shell Exploration and Production Company (SEPCo) Comment ID: 22759

84
the need to "grandfather" Class II CO2 injection wells that remain in service 

for GS purposes after oil or gas production has ceased. Rather than resembling 

the Class II requirements, the proposed Class VI requirements are as stringent 

as those for hazardous waste injection in most respects. Indeed, many of the 

construction, mechanical integrity, and monitoring and financial assurance 

requirements proposed for Class VI wells are even more comprehensive and 

stricter than those for hazardous waste injection wells. While some of these 

more burdensome requirements are legitimately related to concerns about the 

mobility of CO2 or the anticipated scale of GS operations, many - as discussed 

in Part III of these comments - are not. 

Recommendation: 

The Class VI requirements addressing issues such as well construction and 

mechanical integrity testing should be no different than the Class II 

requirements. 

Response: EPA agrees that many Class I, Class II, and Class V experimental technology wells are 

designed and constructed to withstand exposure to CO2. The final GS rule provides for the construction 

of these wells to be grandfathered per §146.81(c), provided the owner or operator can demonstrate to the 

Director that the wells were engineered and constructed to meet the requirements at §146.86(a) and 

ensure protection of USDWs, in lieu of requirements at §146.86(b) and §146.87(a). 

EPA disagrees that other requirements (e.g., MITs, siting, monitoring, operational, and AoR 

requirements) should also be grandfathered. Following re-permitting of the well as Class VI, many of 

the unique factors of GS sites (e.g., increased reservoir pressures associated with large volumes of stored 

CO2 and the corrosivity of CO2 in the presence of water) will result in an increased risk profile, 

warranting the specific requirements in the final GS rule. Therefore, following re-permitting as Class VI 

wells, these projects must be subject to the operational, MIT, monitoring, reporting, plugging, and postinjection site care and site closure requirements in the final GS rule. See the discussion of EPA's final 

regulatory approach in the preamble to the GS rule for additional detail on these requirements. 

Other EPA Comment Codes and Descriptions: 1680 1.3.8 Don't overstate risk, don't stigmatize CO2 

Comment: - In many instances the proposed requirements for Class VI CO2 GS wells are 

unnecessarily more stringent than existing requirements for other well classes 

under the UIC Program. While it is essential that the Final Rule be protective 

of USDWs, many of the more rigorous requirements proposed for Class VI wells are 

not warranted by findings of unique risks posed by CO2 GS wells. The Final Rule 

should craft requirements that protect USDWs while avoiding the imposition of 

unnecessary costs or the inappropriate creation of a negative public perception 

of CO2 GS projects. 

Response: EPA disagrees that the GS regulation overstates the risk of CO2 injection or that it is 

unnecessarily stringent. EPA recognizes that injecting large volumes of CO2 for GS poses unique 

challenges that, if not properly managed, could endanger drinking water sources and have other adverse 

impacts. However, with proper site selection, the final, tailored, Class VI requirements address the large 

volumes of CO2 injected, its buoyancy, potential corrosivity in the presence of water, and potential 

impurities in the CO2 stream. In addition, EPA expects the tailored permitting, siting, construction, 

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 22904

85
operation, monitoring, and post-injection site care requirements in the GS rule to prevent leakage from 

injection formations and protect USDWs. 

EPA does not believe that the tailored requirements will create a negative public perception of GS. The 

Agency believes that a demonstration to the public that GS projects are meeting the GS rule's tailored 

requirements will likely improve confidence in the project and help address public questions and 

concerns. 

Comment: AMWA also recommends that EPA commit to update the rule regularly as more 

becomes known about CCS technology and the behavior of CO2 injected into the 

subsurface. AMWA recommends that EPA work to update the rule every three to five 

years for the foreseeable future, as this technology will become more prevalent 

and injection methods and other sequestration techniques will likely improve. 

In developing this proposal, EPA has demonstrated its ability to quickly bring 

staff up to speed on this technology and AMWA believes the Agency must continue 

chnological advances. 

Response: EPA agrees that an adaptive approach to the UIC GS rulemaking is appropriate. The Agency 

will use such an approach to ensure that USDWs are protected from endangerment and meet the 

potentially fast pace of GS deployment. EPA believes that an adaptive approach will allow regulatory 

development to proceed in time to meet the current and future demand for Class VI permits while 

recognizing the need to: continue to gather data from pilot projects and other research as it becomes 

available; and to enhance understanding of the technical and administrative aspects of GS deployment, 

operation, and technology developments. EPA plans, every six years, to collect and review data on GS 

projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Comment: I. INTRODUCTION -- AND A SUGGESTED COMPLEMENTARY APPROACH 

The Proposed Rule is appropriately viewed as part of EPA’s broader effort to 

address atmospheric emissions of CO2 and other greenhouse gases ("GHG").[FN1] 

Analysts worldwide have identified carbon capture and storage "CCS" as one of 

the essential components of any successful strategy for lowering such 

emissions.[FN2] Within this broader context the Proposed Rule is thus intended 

to encourage the safe and effective development of geologic storage or 

sequestration of CO2 which is in addition to existing injection and incidental 

storage of CO2 in enhanced oil or gas recovery operations ("EOR" or "EGR," 

respectively)) through Class II wells. In many respects, the Proposed Rule 

appears well-suited to advance that objective and EPA deserves credit for having 

developed a comprehensive approach to a complex set of issues. In other 

respects, however, the Proposed Rule appears to misapprehend certain core facts 

relating to the physical properties and behavior of CO2 in some underground 

formations, the scale of existing CO2 storage operations incidental to EOR 

Commenter Name: Diane VanDe Hei Letter ID: 0213

Commenter Organization: Association of Metropolitan Water Agencies 

(AMWA)

Comment ID: 

22955

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24271

86
operations over the last four decades, and the practical fruits of that 

experience. 

As a result, the Proposed Rule includes a number of requirements that long 

experience has shown are unnecessary for the protection of underground sources 

of drinking water ("USDWs") and a few that would even prove counterproductive. 

[1] See generally Regulating Greenhouse Gas Emissions Under the Clean Air Act, 

Advanced Notice of Proposed Rulemaking, EPA-HQ-OAR-2008-0318, 73 Fed. Reg. 

44,354, 44,397-44,440 (July 30, 2008) (discussing CO2 emission issues under the 

Clean Air Act and generally soliciting public comment on how to respond to the 

U.S. Supreme Court’s decision in Massachusetts v. EPA, 549 U.S. 497, 127 S. Ct. 

1438 (2007) . 

[2] See, e.g., Intergovernmental Panel on Climate Change, Special Report on 

Carbon Dioxide Capture and Storage, 208 (Bert, Metz, et al., eds., 2005) (at 13, 

45) ("IPCC Special Report on CCS") (showing potential contribution of CCS in 

reducing emissions). 

Response: EPA disagrees that any of the requirements in the GS rule are unnecessary. Rather, the GS 

regulation tailors the UIC requirements to address the unique issues associated with large-scale GS, 

including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, 

the potential presence of impurities in captured CO2, and its mobility within subsurface geologic 

formations. 

The Agency agrees that GS is a key climate change mitigation technology that is part of a portfolio of 

options that could be deployed to reduce CO2 emissions. Other options include efficiency improvements 

and the use of alternative fuels and renewable energy sources. EPA clarifies that the purpose of the GS 

regulation is to ensure that GS is conducted in a manner that protects USDWs from endangerment and 

only applies to owners or operators of wells injecting CO2 for the purpose of long-term storage. 

Please see the remainder of EPA's responses to this comment and the final rule and preamble for further 

details. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: In addition, the Proposed Rule appears to view CO2 injection activity as a 

static activity in which CO2 is injected one time and never leaves the storage 

formation. In contrast, actual experience since 1972 reveals a far more dynamic 

process in which individual wells may serve as CO2 injection wells, production 

wells producing oil and/or CO2, or indeed multiple use wells (i.e., injection of 

CO2, injection of brine, brine disposal, and production). The locational value 

of injected CO2 is likely to vary over time as energy and CO2 markets evolve and 

it may well become valuable for a Class II EOR well to transition from Class II 

to Class VI and then to return to Class II EOR activity. The Proposed Rules do 

not seem well suited to deal with such dynamic changes in the various 

interrelated markets for CO2, oil and natural gas. 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24272

87
Response: EPA clarifies that the Class VI requirements in the GS rule are for CO2 injection for longterm storage of large volumes of CO2. EPA acknowledges that multiple wells may interact at a given 

GS site. EPA also believes that requiring separate permit applications for each GS well will ensure 

sufficient review and that the public has an opportunity to provide input on each well in the field as it is 

constructed or brought online. Comments related to the economics of Class II EOR projects 

transitioning to Class VI projects is outside the scope of this rulemaking. The purpose of this rule is to 

ensure that GS is conducted in a manner that is protective of USDWs from endangerment. 

EPA is developing guidance on transitioning permits from Class II to Class VI. The guidance will assist 

Directors in determining whether an injection project should be transitioned from Class II, where the 

primary purpose is oil and gas production, to Class VI, where the primary purpose is long-term storage 

of large volumes of CO2. The guidance describes the methods available for the Director to determine 

changes in risk to USDWs from projects, and how the Director may determine whether a project should 

be regulated within the Class II or Class VI UIC program. This guidance will be available on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. For more information, 

please see the discussion on transition of Class II wells in the preamble to the final GS rule. 

Comment: TxCCSA Perspectives on the EPA's Proposed Rule for Geologic Sequestration 

While the EPA's Proposed Rule represents a significant step in the development 

of Carbon Capture and Storage (CCS) as an emissions reduction strategy, the 

Proposed Rule assumes that sequestration or geologic storage [FN1] is defined as 

injection without simultaneous extraction of hydrocarbons, as in the case 

of enhanced oil recovery (EOR) or enhanced gas recovery (EGR) (e.g., enhanced 

coal bed methane or ECBM). The Proposed Rule focuses on sequestration outside 

the context of commercial product extraction and effectively separates CO2 

injection into two classes: sequestration in saline or other non· hydrocarbon 

related target formations and hydrocarbon related sequestration. In general, 

this focus reveals several concerns reflected in the Proposed Rule that the 

TxCCSA hopes to address, including: 1) the lack of clarification of the injectate 

stream which could lead to the stream being considered a waste; 2) the absence 

of a system for qualifying storage sites; 3) a lack of understanding or the 

number of wellbores required for scaled operations; 4) the attribution of harmful 

characteristics to the concept of buoyancy; 5) the lack of consideration for 

simultaneous storage and hydrocarbon production; 6) the post-injection site care 

timeframe; and 7) multi·state jurisdictional issues. 

1 While the term sequestration and storage may be used interchangeably, we 

prefer the term "storage," as it contemplates recovery of injected CO2 for 

beneficial use. 

2 See Regulatory Determination for Oil and Gas and Geothermal Exploration, 

Development, and Production Wastes; Regulatory Determination, 53 Fed. Reg. 25445 

(July 6, 1988) 

3 See the work of Dr. Steven Bryant, director of the Geologic CO2 Storage Joint 

Industry Project in the Center of Petroleum and Geosystems Engineering at the 

University of Texas. 

4 See 73 Fed. Reg. at 43503. 

5 ~ Id at 43524. 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23955

88
6 See Intergovernmental Panel on Climate Change, Special Report on Carbon 

Dioxide Capture und Storage, 208 (Bert, Metz, et al. eds., 2005); see also Sally 

M. Benson, Carbon Dioxide Capture and Storage: Research Pathways, Progress and 

Potential, Global Climate & Energy Project Annual Symposium, October 2007, 

available at 

http://pangea.stanford.edulresearctv'bensonlab/presentations/Carbon%20Dioxide%20 

CaptureYa20and%20Storage%2OY020ResearchO/020Palhways%20Progress'Y020and%20Potential.pdf. 

7 Chiara Trabucchi and Lindene Patton, Storing Carbon: Optionsfor Liability 

Risk. Management, Financial Responsibility, Daily Environment Report, Bureau 

of National Affairs, pg. 8 (Sept. 3, 2008). 

8 See IPCC 2005 Repon, supra, at 208; see also Benson 

9 See Task Force on Carbon Capture and Geologic Storage, The Interstate Oil and 

Gas Compact Commission, Storage of Carbon Dioxide in Geologic Structures: A Legal 

and Regulatory Guide for States and Provinces (Sept. 25,2007) available at 

http://iogcc.mysbopify.comlcollectionslfrontpagelproductslco2-storage-a 

·Legal·andregulatory-guide-for-states-2008. 

10 See 73 Fed. Reg. at 43510. 

Response: The Agency acknowledges the comment and agrees that GS is a key climate change 

mitigation technology that is part of a portfolio of options that could be deployed to reduce CO2 

emissions. EPA clarifies that the purpose of the GS regulation is to ensure that GS is conducted in a 

manner that protects USDWs from endangerment and only applies to owners or operators of wells 

injecting CO2 for the purpose of long-term storage. 

Please see the remainder of EPA's responses to this comment and the final rule and preamble for further 

details. 

Other EPA Comment Codes and Descriptions: 1630 1.3.3 RCRA/hazardous waste issues (seeking 

comment) 

Comment: 25. Perverse incentives: The stringency of the Class VI rules (relative to the 

other UIC well classes) may create perverse incentives. For example, an operator 

could add hydrogen sulfide to the carbon dioxide stream and then seek a Class I 

permit with less stringent area of review, monitoring, post-injection and 

closure requirements than a Class VI permit. Thus, EPA should review the 

requirements and applicability of Class I wells in conjunction with the proposed 

rulemaking for Class VI wells. 

Response: EPA disagrees with this comment and does not anticipate this type of scenario will take place 

because under the final GS rule, owners or operators must determine whether the CO2 stream is 

hazardous under EPA’s RCRA regulations; If so, any injection of the hazardous CO2 stream may only 

occur in a Class I hazardous waste injection well under 40 CFR Part 146 Subpart G. For Class I 

hazardous wells, owners or operators are required under 40 CFR 286.6 to demonstrate, to a reasonable 

degree of certainty, that there will be no migration of hazardous constituents from the disposal unit or 

injection zone for as long as the wastes remain hazardous or for 10,000 years via a fluid flow no 

migration petition. EPA anticipates that this may be very difficult to demonstrate for long-term storage 

of CO2 at anticipated volumes. Conversely, Class VI wells cannot be used for the co-injection of RCRA 

Commenter Name: M. Granger Morgan Letter ID: 0233

Commenter Organization: Carnegie Mellon University on behalf of the CCS Reg 

Project

Comment ID: 

21917

89
hazardous wastes (i.e., hazardous wastes that are injected along with the CO2 stream). 

EPA received many comments related to RCRA applicability to GS sites and has decided to initiate a 

separate proposed rulemaking specifically to examine the issue of RCRA applicability to CO2 streams 

being geologically sequestered, including the possible option of a conditional exemption from the 

RCRA requirements for CO2 GS in Class VI wells. EPA will consider these comments as part of its 

development of that proposal. The Agency will consider issues particular to RCRA in the context of that 

separate rulemaking, and recommends that the commenter read that proposed rule when it is published. 

The Agency notes that commenters who wish to submit comments on the RCRA proposal will need to 

do so during the comment period for that rule. 

EPA adds that revising the requirements for other classes of wells is outside the scope of the GS 

rulemaking. 

Comment: The proposal sets forth a complex regulatory requirement that appears to start 

under the framework of a Class 1 UIC well, rather than the more appropriate 

Class 2 UIC well framework, and adds layers of additional regulatory 

requirements. While we understand that protection of human health and the 

environment is the mission of EPA, EPA should strive to avoid overly stringent 

regulatory requirements that could have the impact of preventing the development 

of carbon capture technology due to regulatory burdens associated with dealing 

with the carbon once it is captured. 

Response: EPA disagrees that any of the requirements in the GS rule are unnecessary. Rather, the GS 

regulation tailors the UIC requirements to address the unique issues associated with large-scale GS 

including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, 

the potential presence of impurities in captured CO2, and its mobility within subsurface geologic 

formations. 

Please see the remainder of EPA's responses to this comment and the final rule and preamble for further 

details. 

Comment: While Peabody Energy is generally supportive of the proposed rule, we believe 

the final rule should be modified to provide greater certainty for CCS projects 

that would like to proceed in the interim prior to promulgation of the final 

rule. The rule should also provide more certainty and flexibility to convert 

Response: EPA recognizes the importance of providing clear, flexible, scalable, and appropriate 

regulations. EPA believes that the GS regulation will provide certainty to industry and the public by 

providing consistency in requirements across the U.S. and transparency about what requirements apply 

to owners or operators. 

Please see the remainder of EPA's responses to this comment and the final rule and preamble for further 

details. 

Commenter Name: Mike Nasi Letter ID: 0254

Commenter Organization: Clean Coal Technology Foundation of Texas Comment ID: 22359

Commenter Name: Dianna Tickner Letter ID: 0262

Commenter Organization: Peabody Energy Comment ID: 22991

90
Other EPA Comment Codes and Descriptions: 1400 1.2 Comments on EPA's Authority to Regulate 

Injection of CO2 

Comment: B. Definition of GS 

Geologic sequestration and authority 

In the proposed rule, EPA has defined geologic sequestration as follows [FR p. 

43535, §146.81(d)]: 

"Geologic sequestration means the long-term containment of a gaseous, 

liquid or supercritical carbon dioxide stream in subsurface geologic 

formations. This term does not apply to its capture or transport." 

The proposed rule has cited authority for EPA to regulate GS under the Safe 

Drinking Water Act. However, we believe that EPA should exercise its authority 

under the Clean Air Act as well to regulate GS for the added purpose of 

preventing releases to the atmosphere, and not just for the purpose of 

protecting USDWs. Under such authority, the Agency should ensure that any wells 

permitted for the purposes of GS meet an adequate permanence standard, such as 

that already promulgated in the UIC rules by the state of Washington, which was 

based on the IPCC’s findings in its Special Report on Carbon Capture and 

Storage [FN1]: 

"Permanent sequestration means the retention of greenhouse gases in a 

containment system using a method that is in accordance with standards approved 

by the department and that creates a high degree of confidence that 

substantially ninety nine percent of the greenhouse gases will remain contained 

for at least one thousand years." [FN2] 

Under this added authority, EPA should ensure that Class VI is adequate for the 

purposes of protecting USDWs and for preventing releases of CO2 to the 

atmosphere. 

Other wells permitted for GS, whether for that sole purpose or for GS and other 

purposes, should also be subject to regulatory requirements sufficient both to 

protect USDWs and to prevent releases of CO2 to the atmosphere. Such 

requirements include, but are not limited to, adequate site characterization, 

monitoring, modeling, corrective and remedial action and closure standards, as 

well as other requirements that EPA has proposed for Class VI. We cannot endorse 

the classification of either Class II (as was proposed or as modified by some 

other commenters) wells or Class VI wells as proposed by EPA in the rule, as the 

definition only covers protection of USDWs. 

[FN1] In its technical summary, IPCC’s Special Report on Carbon Capture and 

Storage states that "With regard to global risks, based on observations and 

analysis of current CO2 storage sites, natural systems, engineering systems and 

models, the fraction retained in appropriately selected and managed reservoirs 

is very likely to exceed 99% over 100 years, and is likely to exceed 99% over 

1000 years. Similar fractions retained are likely for even longer periods of 

Commenter Name: David Hawkins Letter ID: 0272

Commenter Organization: Natural Resources Defense Council Comment ID: 24076

91
time, as the risk of leakage is expected to decrease over time as other 

mechanisms provide additional trapping." 

[FN2] WAC 173-407-110 Definitions to Part II. 

Response: EPA clarifies that the scope of the GS regulation is limited to injection of CO2, and that all 

requirements in the GS rule are designed for the purpose of protecting USDWs from endangerment. 

Consequently, this comment is outside the scope of the rulemaking. The SDWA does not provide the 

UIC Program with the authority to develop regulations for all areas related to GS, such as releases to the 

atmosphere. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

Comment: Our most significant concerns from review of the proposed requirements are 

organized in four broad programmatic areas: 

(1) Appropriate level of regulation; 

(2) Appropriate financial assurance for long post-injection timeframes; 

(3) Flexibility and streamlining in Class VI program primacy considerations; 

and, 

(4)Resource needs for regulation of the proposed new class of wells. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment Code: 1220 1.1.1.1 Terminology and definitions 

Commenter Name: Mark Vickery Letter ID: 0280

Commenter Organization: Texas Commission on Environmental Quality Comment ID: 24097

92
Individual Comments 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: For the definition of AoR it needs to be realized that the AoR could be quite 

sizeable potentially covering many square miles. We suggest using the criteria 

for the AoR as found in existing 146.6 and for the Pressure Front definition. 

Otherwise, the AoR as defined could make it impractical to accomplish the work 

required. 

For Geologic Sequestration Project definition, our comments for the AoR 

definition apply also. 

Response: The Agency has carefully considered all comments on the AoR definition at 146.84(a) and 

modified it to read as follows: The region surrounding the geologic sequestration project where USDWs 

may be endangered by the injection activity. The area of review is delineated using computational 

modeling that accounts for the physical and chemical properties of all phases of the injected CO2 stream 

and is based on available site characterization, monitoring, and operational data. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: Geologic sequestration project means an injection well or wells used to 

emplace a CO2 stream beneath the lowermost formation containing a USDW, OR 

ANOTHER FORMATION, IF THE DIRECTOR DETERMINES THAT INJECTION INTO THE 

OTHER 

FORMATION WILL NOT ENDANGER USDWS. It includes the subsurface 3-D extent of 

the carbon dioxide plume, associated pressure front, and displaced brine, as 

well as the surface area above that delineated region. 

{RRC suggests adding to the end of the first sentence of the definition of 

Geologic sequestration project, "or another formation, if the Director 

determines that injection into the other formation will not endanger USDWs." } 

Response: EPA disagrees with the suggested edit. However, the Agency has modified the final 

definition of geologic sequestration project at §146.81(d) to read as follows: “[A]n injection well or 

wells used to emplace a carbon dioxide stream beneath the lowermost formation containing a USDW; 

or, wells used for geologic sequestration of carbon dioxide that have been granted a waiver of the 

injection depth requirements pursuant to requirements at §146.95; or, wells used for geologic 

sequestration of carbon dioxide that have received an aquifer exemption expansion. It includes the 

subsurface three-dimensional extent of the carbon dioxide plume, associated pressure front, and 

displaced brine, as well as the surface area above that delineated region.” 

EPA adds that the final rule contains a new provision for owners or operators to seek a waiver from the 

injection depth requirements, at §146.95. Based on its evaluation of all public comments and input on 

the proposed rule and the Notice of Data Availability and Request for Comment, EPA has made many

Commenter Name: Michael H. Cochran Letter ID: 0108

Commenter Organization: Bureau of Water, Division of Environment, Kansas 

Department of Health & Environment (KDHE)

Comment ID: 

21961

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24759

93
revisions to the Class VI GS rule. Please see the final rule and preamble for additional information. 

Comment: Pressure front means the zone of elevated pressure that is created by the 

injection of carbon dioxide into the subsurface. For the purposes of this 

subpart, the pressure front of a carbon dioxide plume refers to a zone where 

there is a pressure differential sufficient to cause the movement of 

injected fluids or formation fluids into a USDW. 

{Why does this definition need to be different?} 

Response: The definition of a pressure front is unique to the Class VI GS requirements and Subpart H to 

address the unique nature of CO2 injection for GS, including the potential impact a pressure front may 

have on USDWs. The final definition of pressure front at §146.81(d) is unchanged, and reads as follows: 

“[T]he zone of elevated pressure that is created by the injection of carbon dioxide into the subsurface. 

For the purposes of this subpart, the pressure front of a carbon dioxide plume refers to a zone where 

there is a pressure differential sufficient to cause the movement of injected fluids or formation fluids into 

a USDW.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: Transmissive fault or fracture means a fault or fracture that has sufficient 

permeability and vertical extent to allow fluids to move between formations. 

{Recommend that the fault or fracture be "known."} 

Response: EPA disagrees with the suggested edit. The final definition of transmissive fault or fracture at 

§146.81(d) is unchanged and reads as follows: “[A] fault or fracture that has sufficient permeability and 

vertical extent to allow fluids to move between formations.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: (e) A tabulation of all wells within the AOR which penetrate the injection or 

confining zone(s). Such data must include a description of each well's type, 

construction, date drilled, location, depth, record of plugging and/or 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24760

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24761

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24763

94
completion, and any additional information the Director may require; 

{Definition of confining zone includes multiple formations. Do not 

imply that multiple confining zones are preferable to one (good) 

confining zone.} 

Response: EPA disagrees with the suggested edit. The final language in §146.82 is unchanged. EPA 

retains the requirement to identify additional containment/confining zones, if required by the Director, 

as proposed in §146.83(b). EPA acknowledges that such additional zones may not be needed in all 

circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her 

understanding of a particular site. EPA believes that, in some situations, the presence of additional 

confining and containment zones above the primary (i.e., lowermost) confining zone can improve 

USDW protection. These layers could further impede vertical fluid movement and allow for pressure 

dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's 

decision is supported by commenters representing states, water associations, and an electric utility who 

assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and 

permitting a site for GS projects, and would improve understanding of the project as a whole and 

promote better modeling of the site. 

Additionally, the Agency has modified the final definition of confining zone to read as follows: “[A] 

geologic formation, group of formations, or part of a formation stratigraphically overlying the injection 

zone that acts as barrier to fluid movement. For Class VI wells operating under an injection depth 

waiver, confining zone means a geologic formation, group of formations, or part of a formation 

stratigraphically overlying and underlying the injection zone.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 4543 2.5.2.1 MIT procedures and methods for GS 

(seeking comment) 

Comment: Proposed Mechanical Integrity Testing Requirements 

-"Section 146.89 Mechanical integrity. (a) A Class VI well has mechanical 

integrity if: 

(1) There is no significant leak in the casing, tubing or packer; and (2) 

There is no significant fluid movement into a USDW through channels adjacent to 

the injection well bore. 

(b) To evaluate the absence of significant leaks under paragraph (a)(1) of 

this section, owners or operators must...." 

There is no definition of "significant" in the document. A definition should be 

included that explains how the term will be defined, such as some measurement 

around a mean, a variance interval, etc. Too often the term is used without an 

understanding of its technical meaning. This will also help the permittee to 

understand what is expectated. 

Commenter Name: John Hanger Letter ID: 0130

Commenter Organization: Pennsylvania Dept. of Env. Protection Comment ID: 21508

95
-‘De minimus’ CO2 leakage values should be determined and defined, as well as 

the acceptable measurement methodology and verification practices. 

Response: A properly designed and operated well should have no leakage in the casing, tubing, or 

packer and no fluid movement into a USDW through channels adjacent to the wellbore. While the intent 

of MITs is to detect these types of problems as early as possible, the goal of the well design and 

construction requirements at §146.86 is the complete absence of such problems. EPA clarifies that the 

purpose of the "significant leakage" language in this narrow context is simply to avoid triggering 

corrective actions for essentially de minimis situations. Determining whether a MIT result should trigger 

follow-up action is necessarily a case and site-specific situation; as a result, EPA does not believe it is 

appropriate to define the term "significant leakage" in the context of MITs. In addition, EPA has not 

defined this term for purposes of other injection well classes and this has not been shown to hinder 

permitting authorities' and owners or operators' ability to assess whether injection wells have adequate 

mechanical integrity. EPA believes that this approach allows states flexibility, will not interfere with the 

implementation of existing UIC programs, and maintains protection of USDWs from endangerment. 

In keeping with its adaptive rulemaking approach, the Agency plans to collect and review data every six 

years on early GS projects, including MIT data, to determine whether the appropriate amount and types 

of information and appropriate documentation are being collected, and to determine if modifications to 

the requirements are appropriate or necessary. 

Other EPA Comment Codes and Descriptions: 3200 2.2 Proposed Area of Review and Corrective 

Action Requirements (40 CFR 146.84) 

Comment: I. Technical Definitions 

Area of Review and Fluid Movement: Adopt the specific language used by the adhoc CO2 workgroup in its Recommendation 3.1 for determining the parameters of 

each Area of Review, i.e. -- "based on generally accepted and site relevant 

techniques, such as modeling, that define, in three dimensions, the maximum 

extent of the modeled CO2 plume [inclusive of free phase and water- dissolved 

CO2]and associated pressure front." 

Response: Based on review of all public comments on the AoR definition at 146.84(a), the Agency has 

modified it to read as follows: The region surrounding the geologic sequestration project where USDWs 

may be endangered by the injection activity. The area of review is delineated using computational 

modeling that accounts for the physical and chemical properties of all phases of the injected CO2 stream 

and is based on available site characterization, monitoring, and operational data. The definition in the 

proposed rule accounted for the varying physical and chemical properties of the CO2 including freephase and water-dissolved CO2, as the commenter suggests. The definition in the final rule will continue 

to do so. 

The UIC regulations, including the Class VI regulations, are designed to ensure protection of USDWs 

from endangerment. The Agency believes that the AoR needs to incorporate not only the CO2 itself—

Commenter Name: Anonymous2 Letter ID: 

0133

Commenter Organization: Sierra Club National Global Warming and Energy 

Committee and Sierra Club California-Nevada Regional Conservation Committee on 

Energy and Climate Change

Comment ID: 

21578

96
regardless of saturation or phase—but also the area of increased pressure ahead of the CO2 plume, 

which can potentially displace saline, native fluids (i.e., naturally occurring salty water) into USDWs. 

This pressure front would typically encompass an area larger than the plume itself, including any areas 

of small scale fingering or heterogeneities or where CO2 saturation is less than 100 percent. 

Comment: Mechanical Integrity: Include the term Mechanical Integrity under the phrases 

originally defined at 40 CFR 146.81(d). 

Response: EPA clarifies that mechanical integrity is defined at §146.89(a) as the absence (1) of 

significant leak in the casing, tubing, or packer and (2) of significant fluid movement into a USDW 

through channels adjacent to the injection wellbore. 

Other EPA Comment Codes and Descriptions: 2120 1.6.1 Deep saline formations; 4400 2.4.4.3 

Allowing injection above or between USDWs (seeking comment) 

Comment: USDWs and Exempted Aquifers: Re-evaluate the UIC program's current definition of 

Underground Source of Drinking Water (at 40 CFR 146.3), as applied to Criteria 

for Exempted Aquifers (at 40 CFR 146.4), in regards to the EPA's total dissolved 

solids (TDS) standard of <10,000 mg/L. 

Response: The Agency acknowledges commenter concerns about water resources and future water 

resource availability. However, modifying the definition of a USDW is outside the scope of the GS 

rulemaking. USDWs are defined as aquifers currently being used as sources of drinking water or those 

capable of supplying a public water system and they have a total dissolved solids (TDS) content of 

10,000 milligrams per liter or less (§144.3). 

The primary goal of the UIC Program under the SDWA is to protect USDWs in order to ensure a 

reliable supply of drinking water for the American public. The GS rule, as part of the UIC program 

regulations, continues the program’s statutory mandate of ensuring the protection of USDWs. The 

permitting, siting, construction, operation, monitoring, and post-injection site care requirements in the 

GS rule built on a long-standing protective regulatory framework, tailored to the unique characteristics 

of CO2 GS. 

EPA recognizes that there is increasing demand for water resources and that technology improvements 

may make high TDS aquifers viable drinking water sources. EPA believes these potential resources 

should be considered when injection depth waivers are sought. Therefore, the final GS rule at §146.95

(b) requires the Director to consider these issues in determining whether an injection depth waiver is 

appropriate. Specifically, the Director must consider whether alternative injection sites are available; 

community needs, demands, and supply from drinking water resources; planned needs, potential and/or 

future use of USDWs and non-USDWs in the area; and a plan for securing alternative resources or 

Commenter Name: Anonymous2 Letter ID: 

0133

Commenter Organization: Sierra Club National Global Warming and Energy 

Committee and Sierra Club California-Nevada Regional Conservation Committee on 

Energy and Climate Change

Comment ID: 

21579

Commenter Name: Anonymous2 Letter ID: 

0133

Commenter Organization: Sierra Club National Global Warming and Energy 

Committee and Sierra Club California-Nevada Regional Conservation Committee on 

Energy and Climate Change

Comment ID: 

21580

97
treating USDW formation waters in the event of contamination related to the Class VI injection activity. 

Comment: B. Mechanical Integrity 

Recommendation B: Include the term Mechanical Integrity under the phrases 

originally defined at 40 CFR 146.81(d). 

Although Mechanical Integrity is defined later in the Class VI regulations under 

its own heading [at 146.89(a)], it would be helpful to include it as a term 

within the Definitions section at the beginning of the permitting rules. 

Response: EPA clarifies that mechanical integrity is defined at §146.89(a) as the absence (1) of 

significant leak in the casing, tubing, or packer and (2) of significant fluid movement into a USDW 

through channels adjacent to the injection wellbore. 

Comment: A. Owner/Operator Liability 

The proposed regulations affect owners and operators of injection wells that 

will be used to inject CO2 into the subsurface for purposes of geological 

sequestration. Owners and operators will be responsible for numerous siting, 

construction, testing, and monitoring requirements enumerated in the 

regulations, as well as long-term maintenance and financial requirements not yet 

wholly defined by the proposed regulations. The current regulations define 

"owner or operator" as "the owner or operator of any 'facility or activity' 

subject to regulation under the UIC program." [FN2 40 C.F.R. §144.3] The current 

definitions are insufficient to provide certainty on the key question of what 

activities are subject to regulation, or could impose some future liability. For 

example, does "activity" include any pipelines, pumps, or other infrastructure 

used to deliver CO2 to the injection well? 

Response: The final Class VI GS regulations apply to owners or operators of injection wells that will be 

used to inject CO2 into the subsurface for the purposes of GS. Generators and transporters of CO2 are 

not affected by the Class VI GS rule. The UIC program’s authority under the SDWA focuses on 

ensuring that GS projects are permitted, sited, constructed, operated, monitored, and closed in a manner 

that protects USDWs from endangerment. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Commenter Name: Anonymous2 Letter ID: 

0133

Commenter Organization: Sierra Club National Global Warming and Energy 

Committee and Sierra Club California-Nevada Regional Conservation Committee on 

Energy and Climate Change

Comment ID: 

21604

Commenter Name: Robert Bessette Letter ID: 0139

Commenter Organization: Council of Industrial Boiler Owners (CIBO) Comment ID: 23979

Commenter Name: Christine Reimer Letter ID: 0142

98
Other EPA Comment Codes and Descriptions: 4400 2.4.4.3 Allowing injection above or between 

USDWs (seeking comment) 

Comment: Definition of Underground Sources of Drinking Water 

NGWA recommends that US. EPA reevaluate the appropriateness of the definition of 

an underground source of drinking water (USDW) as one containing less than 

10,000 ppm total dissolved solids prior to large-scale licensing of carbon 

capture and storage (CCS) sites to ensure future drinking water supplies are not 

unintentionally degraded. For example, a recent article reported that deep 

brackish ground water, approximately 12,000 TDS, is under consideration as a 

water source for a development in Sandoval County, New Mexico. The article 

notes that the cost of water treatment is expected to be less than obtaining 

existing water rights (Sengebush, 2008) In 2003, water managers in 36 states 

anticipated shortages in localities, regions, or statewide in the next ten years 

(U.S. General Accounting Office, 2003). The potential for the increased use of 

brackish ground water for water supplies must be anticipated and considered. 

Sengebush, Robert M., INTERA, Inc. Deep Brackish Water Considered for New 

Mexico Development. Southwest Hydrology, March/April 2008, p. 8. 

U.S. General Accounting Office. Freshwater Supply: States’ Views of House 

Federal Agencies Could Help Them Meet the Challenges of Expected Shortages 

(GAO-03-514). July 2003, p. 1. 

Response: EPA is not changing the USDW definition; changing the definition of a USDW is outside the 

scope of the GS rulemaking. The GS rule focuses on ensuring protection of USDWs, as required under 

the SDWA, by establishing regulations to ensure the safe injection of CO2 for long-term storage. 

EPA recognizes that there is increasing demand for water resources and that technology improvements 

may make high TDS aquifers viable drinking water sources. EPA believes these potential resources 

should be considered when injection depth waivers are sought. Therefore, the final GS rule at §146.95

(b) requires the Director to consider these issues in determining whether an injection depth waiver is 

appropriate. Specifically, the Director must consider whether alternative injection sites are available; 

community needs, demands, and supply from drinking water resources; planned needs, potential and/or 

future use of USDWs and non-USDWs in the area; and a plan for securing alternative resources or 

treating USDW formation waters in the event of contamination related to the Class VI injection activity. 

Comment: Proposed Rule: 146.81(d) [Definition - Area of review] 

Proposed Revision: Area of review means the region surrounding the geologic 

sequestration project that may be impacted by the injection activity. The area 

of review is based on computational modeling that accounts for the physical and 

chemical properties of all phases of the injected carbon dioxide stream and the 

zone of increased pressure created by the injection. 

Rationale: The AOR needs to be based on both the CO2 plume and the associated 

pressure front in order to completely identify the areas that may be affected by 

Commenter Organization: National Ground Water Association Comment ID: 22549

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22589

99
the injection 

Proposed Rule: 146.81(d) [Definition - Geologic sequestration project] 

Proposed Revision: Geologic sequestration project means an injection well or 

wells used to emplace a carbon dioxide stream. It includes the subsurface threedimensional extent of the carbon dioxide plume, associated pressure front, and 

displaced brine, as well as all USDWs and the surface area above that delineated 

region. 

Rationale: See Section 144.6(f). If an exemption is provided, USDWs below the 

CO2 plume or pressure front should be included in the AOR specifically. 

Response: EPA agrees that the AoR definition should account for the impact of the CO2 plume on 

USDWs. The Agency has carefully considered all comments on the AoR definition at §146.84(a) and 

modified it to read as follows: “[T]he region surrounding the geologic sequestration project where 

USDWs may be endangered by the injection activity. The area of review is delineated using 

computational modeling that accounts for the physical and chemical properties of all phases of the 

injected CO2 stream and is based on available site characterization, monitoring, and operational data.” 

The Agency has also modified the final definition of geologic sequestration project to read as follows: 

“Geologic sequestration project means an injection well or wells used to emplace a carbon dioxide 

stream beneath the lowermost formation containing a USDW; or, wells used for geologic sequestration 

of carbon dioxide that have been granted a waiver of the injection depth requirements pursuant to 

requirements at §146.95; or, wells used for geologic sequestration of carbon dioxide that have received 

an aquifer exemption expansion. It includes the subsurface three-dimensional extent of the carbon 

dioxide plume, associated pressure front, and displaced brine, as well as the surface area above that 

delineated region.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 4543 2.5.2.1 MIT procedures and methods for GS 

(seeking comment) 

Comment: 1. EPA Should Define "Significant Leakage" Within The Context Of Endangerment. 

EPA has defined mechanical integrity as "no significant leakage" and "no 

significant fluid movement into a USDW through channels adjacent to the 

injection well bore." While Spectra agrees with EPA’s general approach here, 

we are concerned that the absence of a definition regarding what constitutes 

"significant" could create ambiguity that could be construed against the 

owner/operator and beyond authority granted under SDWA. Therefore, we would 

strongly recommend that the Agency define what constitutes "significant" or, 

alternatively, clarify under what conditions significant leakage might be 

construed. Toward this end, we believe that the term should be defined and 

construed within the statutorily defined concept of "endangerment" [2] under SDWA, 

i.e., significant leakage would be defined as any leakage that could 

Commenter Name: Brianne Metzger Letter ID: 0151

Commenter Organization: Spectra Energy Corp Comment ID: 21834

100
potentially endanger a USDW. As one court has held, Congress’ established no 

specific metric for measuring endangerment and thus the Agency has the 

discretion to develop UIC requirements based on varied geology, Miami-Dade 

County v. EPA, 529 F.3d 1049 (11th Cir. 2008) (court upheld EPA’s rule 

eliminating the non-endangerment finding requirement for Class I municipal 

injection wells). The amount of leakage and what constitutes significant may 

vary depending upon the geologic formations and proximity to USDWs. 

2 Endangerment is defined as follows: Underground injection endangers drinking 

water sources if such injection may result in the presence in underground water 

which supplies or can reasonably be expected to supply any public water system 

of any contaminant, and if the presence of such contaminant may result in such 

system’s not complying with any national primary drinking water regulation or 

may otherwise adversely affect the health of persons. 42 U.S.C. § 300h(d). 

Response: A properly designed and operated well should have no leakage in the casing, tubing, or 

packer and no fluid movement into a USDW through channels adjacent to the wellbore. While the intent 

of MITs is to detect these types of problems as early as possible, the goal of the well design and 

construction requirements at §146.86 is the complete absence of such problems. EPA clarifies that the 

purpose of the "significant leakage" language in this narrow context is simply to avoid triggering 

corrective actions for essentially de minimis situations. Determining whether a MIT result should trigger 

follow-up action is necessarily a case- and site-specific situation; as a result, EPA does not believe it is 

appropriate to define the term "significant leakage" in the context of MITs. In addition, EPA has not 

defined this term for purposes of other injection well classes and this has not been shown to hinder 

permitting authorities' and owners' or operators' ability to assess whether injection wells have adequate 

mechanical integrity. EPA believes that this approach allows states flexibility, will not interfere with the 

implementation of existing UIC programs, and maintains protection of USDWs from endangerment. 

In keeping with its adaptive rulemaking approach, the Agency plans to collect and review data every six 

years on early GS projects, including MIT data, to determine whether the appropriate amount and types 

of information and appropriate documentation are being collected, and to determine if modifications to 

the requirements are appropriate or necessary. 

Other EPA Comment Codes and Descriptions: 4540 2.5.2 Proposed external MIT requirements 

Comment: EPA is also proposing that an owner/operator demonstrate "external mechanical 

integrity pursuant to § 146.89(c) at least once per year." 40 C.F.R. 146.90(e). 

External mechanical integrity is not defined. Therefore, we would ask EPA to 

clarify what is meant by this term. 

Response: EPA clarifies that mechanical integrity refers to the absence (1) of significant leak in the 

casing, tubing, or packer and (2) of significant fluid movement into a USDW through channels adjacent 

to the injection wellbore. The second half of this definition refers to external mechanical integrity. 

EPA adds that a properly designed and operated well should have no leakage in the casing, tubing, or 

packer and no fluid movement into a USDW through channels adjacent to the wellbore. While the intent 

of MITs is to detect these types of problems as early as possible, the goal of the well design and 

construction requirements at §146.86 is the complete absence of such problems. For additional 

Commenter Name: Brianne Metzger Letter ID: 0151

Commenter Organization: Spectra Energy Corp Comment ID: 21842

101
information, please see the discussion of MITs in the final rule preamble.

Comment: 4. EPA's definition of geologic formation relies on "layers" of rock as 

distinguished by its properties. Because appropriate sites may not, indeed, be 

layered, the term "body" of rock, as used by geologists, is more appropriate 

and responsive to findings that differing sites may be suitable to geologic 

sequestration. 

Response: EPA disagrees with the suggested edit. The final definitions of confining zone and injection 

zone at §146.81(d) continue to use the terms “geologic formation, group of formations, or part of a 

formation.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Comment: 5. EPA's definition of"mechanical integrity" including lack of "significant 

leakage" may leave the environment and, possibly, safety at risk due to 

differing interpretations of significance. Small amounts of leakage accumulating 

over time may become significant. "Significant leakage" requires a definition. 

Response: A properly designed and operated well should have no leakage in the casing, tubing, or 

packer and no fluid movement into a USDW through channels adjacent to the wellbore. While the intent 

of MITs is to detect these types of problems as early as possible, the goal of the well design and 

construction requirements at §146.86 is the complete absence of such problems. EPA clarifies that the 

purpose of the "significant leakage" language in this narrow context is simply to avoid triggering 

corrective actions for essentially de minimis situations. Determining whether a MIT result should trigger 

follow-up action is necessarily a case and site-specific situation; as a result, EPA does not believe it is 

appropriate to define the term "significant leakage" in the context of MITs. In addition, EPA has not 

defined this term for purposes of other injection well classes and this has not been shown to hinder 

permitting authorities' and owners or operators' ability to assess whether injection wells have adequate 

mechanical integrity. EPA believes that this approach allows states flexibility, will not interfere with the 

implementation of existing UIC programs, and maintains protection of USDWs from endangerment. 

The final definition of mechanical integrity is unchanged. EPA clarifies that mechanical integrity is 

defined at §146.89(a) as the absence (1) of significant leak in the casing, tubing, or packer and (2) of 

significant fluid movement into a USDW through channels adjacent to the injection wellbore. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality 

(MDEQ)

Comment ID: 

22104

Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality 

(MDEQ)

Comment ID: 

22105

102
Comment: (d) - Definitions - Area of review - as defined, is equivalent of Class II Radii 

of Influence - since this is calculated instead of established as a fixed radius 

as set by a lot of states' regulations, this will relieve a lot of confusion, 

especially for the use of horizontal wells 

- Geologic sequestration - subsurface emplacement of CO2 - good specification in 

definition as some more local organizations refer to "carbon sequestration" as 

also putting CO2 in wetlands and/or planting trees in surface. If states have to 

establish their own regulations, this definition could help differentiate the 

surficial aspect from subsurface sequestration 

Response: EPA believes that the use of computational modeling required at §146.84(c)(1), rather than 

relying on a fixed radius or simple computation, is necessary to account for the complexity of GS 

projects. EPA believes that predicting the complex multiphase, buoyant flow of the CO2, co-injectates, 

and compounds that may be mobilized due to injection requires the sophistication of computational 

models. Models can predict CO2 fate and transport, as well as changes in formation pressure, in three 

dimensions, as a function of time in order to delineate the subsurface storage site and the AoR. Models 

can account for site-specific and predicted operating conditions as well as geologic heterogeneities and 

potential migration through faults, fractures, and artificial penetrations. 

The Agency has carefully considered all comments on the AoR definition at §146.84(a) and modified it 

to read as follows: “[T]he region surrounding the geologic sequestration project where USDWs may be 

endangered by the injection activity. The area of review is delineated using computational modeling that 

accounts for the physical and chemical properties of all phases of the injected CO2 stream and is based 

on available site characterization, monitoring, and operational data.” 

The Agency has modified the definition of geologic sequestration project at §146.81(d) to read as 

follows: “[A]n injection well or wells used to emplace a carbon dioxide stream beneath the lowermost 

formation containing a USDW; or, wells used for geologic sequestration of carbon dioxide that have 

been granted a waiver of the injection depth requirements pursuant to requirements at § 146.95; or, wells 

used for geologic sequestration of carbon dioxide that have received an aquifer exemption expansion. It 

includes the subsurface three-dimensional extent of the carbon dioxide plume, associated pressure front, 

and displaced brine, as well as the surface area above that delineated region.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Comment: In the actual text of the proposed rule’s definition of key terms (page 43535), 

a geologic storage project is specifically defined as one in which wells are 

used to "emplace a carbon dioxide stream beneath the lowermost USDW." Was this 

intentional to rule out these other practices that are mentioned in the preamble 

as items that are still under discussion, by defining a GS project in this 

narrow manner in the draft rule language? 

Commenter Name: Steven Pirner Letter ID: 0153

Commenter Organization: South Dakota Department of Environment and Natural 

Resources

Comment ID: 

22143

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific 

Northwest National Laboratory

Comment ID: 

22627

103
Response: EPA disagrees with the suggested edit and retains the language: "emplace a carbon dioxide 

stream beneath the lowermost USDW." EPA has modified the definition of geologic sequestration 

project to read as follows: “Geologic sequestration project means an injection well or wells used to 

emplace a carbon dioxide stream beneath the lowermost formation containing a USDW; or, wells used 

for geologic sequestration of carbon dioxide that have been granted a waiver of the injection depth 

requirements pursuant to requirements at §146.95; or, wells used for geologic sequestration of carbon 

dioxide that have received an aquifer exemption expansion. It includes the subsurface three-dimensional 

extent of the carbon dioxide plume, associated pressure front, and displaced brine, as well as the surface 

area above that delineated region.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Comment: Lack of Clarity throughout Draft Rule with respect to the "CO2 Stream" 

Page 43493 and 43535. The draft Class VI rule has not adequately specified the 

critical concept of the "CO2 Stream." There are many instances in the rule where 

critical decisions are made with respect to the "CO2 stream," but this term 

itself is not well defined nor does it seem to be consistently used. 

o Page 43497. Under "Potential USDW Impacts" the text says that the "CO2 stream" 

may contain other impurities and lists as an example H2S. 

o Page 43493. The Definition of "Geologic Sequestration" only speaks to CO2 

being injected. 

o Page 43496 contains a discussion about whether CO2 is a commodity or a 

pollutant. This issue of whether CO2 is a commodity or a pollutant is a red 

herring as far as this Class VI GS rule is concerned and EPA should be commended 

for saying that its ability to regulate CO2 injection under the SDWA is not 

contingent on determining whether it is a commodity or a pollutant. However, 

the rule is never very clear about what an acceptable "CO2 stream" is. 

o Pages 43503 and 43504. Are a bit clearer on what is and is not a "CO2 stream" 

in the context of a Class VI well but it still is not clear what is allowed and 

what is not. 

o Page 43535. Defines the "carbon dioxide stream" as CO2 from an anthropogenic 

source "plus incidental associated substances derived from the source materials 

and the capture process" as well as any tracers. This is more precise as it 

clearly would rule out the intentional comingling of other gaseous waste 

products that were not derived from the primary anthropogenic CO2 point source. 

Yet it still hinges on the rather vague concept of "incidental". 

Response: The final definition of carbon dioxide stream at §146.81(d) remains unchanged from the rule 

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific 

Northwest National Laboratory

Comment ID: 

22631

104
proposal and reads as follows: “Carbon dioxide that has been captured from an emission source (e.g., a 

power plant), plus incidental associated substances derived from the source materials and the capture 

process, and any substances added to the stream to enable or improve the injection process. This subpart 

does not apply to any carbon dioxide stream that meets the definition of a hazardous waste under 40 

CFR part 261.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1614 1.3.1.2 Impurities in captured CO2; purity 

standards for CO2 

Comment: The issue of how pure the "CO2 stream" needs to be and whether trace or more 

significant quantities of other gases or liquids can be injected into a Class VI 

well is a critical issue that will influence the overall economics of CCS and 

could impact the safety and efficacy of GS. Greater clarity on this issue 

(while still allowing for some site-specific flexibility) would help the 

business community better understand what the cost of using CCS will be. The 

USEPA is encouraged to continue trying to narrow the definition of the "CO2 

stream" in subsequent versions of the draft rule. While this is a difficult 

issue and there is no obvious "correct answer", USEPA is encouraged to continue 

research and dialogues with various stakeholders to see if a narrower definition 

of what degree of co-injection is allowable for a Class VI well. It is possible 

that it could take many years maybe even decades to finalize this but it is 

important to begin pursuing it now. 

Response: EPA understands that many CO2 streams may be relatively pure, and research indicates that 

the estimated amounts of impurities in a CO2 stream are likely to be low. However, these estimates are 

based on limited information, and uncertainties remain about the expected concentrations of impurities 

from the various types of CO2 streams. The concentrations of minor and trace elements in CO2 streams 

for GS projects are likely to vary by facility, coal composition, plant operating conditions, and pollution 

removal technologies. 

The GS rule does not set generic purity standards for CO2 injectate streams (e.g., a percent CO2). 

Instead, the GS rule addresses the quality and quantity of impurities by requiring owners or operators to 

submit information on the source of the CO2 and its physical and chemical properties. Specifically, the 

GS rule requires the owner or operator to submit data about the site, including an analysis of the 

chemical and physical characteristics of the CO2 stream, as required at §146.82(a)(7)(iv), and 

information on the compatibility of the CO2 stream with fluids in the injection zone and minerals in 

both the injection and the confining zones and the materials used to construct the well, per §146.82(c)

(3). This information can help the Director determine the potential for geochemical reactions between 

the injectate (CO2) and the host geologic formations, which could result in the plugging of pore spaces 

or the dissolution of formation minerals. 

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific 

Northwest National Laboratory

Comment ID: 

22632

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific Comment ID: 

105
Comment: - Page 43493, in the "Definitions." Consideration should be given to breaking 

the definition of EOR/EGR into two different short paragraphs. The physical 

processes as well as economic drivers involved in EOR and EGR are not strictly 

similar and it is not clear that these should be lumped together in something 

like a federal regulation. 

Response: EPA disagrees with the suggested edit. The final definition of enhanced oil or gas recovery 

(EOR/EGR) remains unchanged. The Agency clarifies that the final Class VI GS rule does not require 

owners or operators to use GS technologies, nor does it impact business as usual for Class II owners or 

operators that are injecting CO2 to enhance production of oil or gas. Additionally, EPA clarifies that the 

intent of the Class VI GS rule is not to address the use of CO2 for EOR or EGR. Rather, the purpose of 

the Class VI GS regulation is to ensure that, where deployed, GS is conducted in a manner that protects 

USDWs from endangerment. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: §146.93 Post-injection site care and site closure (b)(3) "Prior to authorization 

for site closure, the owner or operator must submit to the Director a 

demonstration, based on monitoring and other site-specific data, that the carbon 

dioxide plume and pressure front have stabilized and that no additional 

monitoring is needed to assure that the geologic sequestration project does not 

pose an endangerment to USDWs." 

Clarification of the term "stabilized" is needed. We recommend that the term 

"stabilized" does not necessarily mean the plume and pressure front are no 

longer moving, but that the rate and direction as defined by confinement zones 

no longer place an USDW at risk. Long-term monitoring should have an "end point" 

defined. Often termed an "exit strategy", this is a key point that is agreed 

upon by all parties about what is a "stable condition". Monitoring data includes 

a prescribed amount of error, thus statistics or other analyses may be required 

to define a "stable condition". 

Response: EPA acknowledges that many site-specific factors will influence the determination of when 

the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for this reason 

that EPA believes that individual UIC Directors, in consultation with operators, will be in the best 

position to determine whether additional post-injection site care is needed. EPA expects this decision to 

be made based on relevant site data and in consultation with all potentially impacted parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time 

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that a 

complete cessation of plume movement is not required, only a demonstration that the plume and 

pressure front no longer pose a risk of endangerment to USDWs. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

Northwest National Laboratory 22671

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23777

106
care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will assist 

Directors in evaluating proposed well plugging plans and post-injection site care and site closure plans 

under §146.92 and §146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells; perform post-injection monitoring; demonstrate non 

endangerment; and perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Definition of Geological Sequestration Project (GSP) and Area of Review (AoR) 

EPA's definitions of GSP and AoR require alignment. 

Currently the GSP and AoR definitions confusingly use different wording to 

describe similar concepts. It is API's view that these definitions should be 

essentially the same. API offers languages in our detailed edits that achieve 

this. 

Response: Based on review of all public comments on the AoR definition at 146.84(a), the Agency has 

modified it to read as follows: The region surrounding the geologic sequestration project where USDWs 

may be endangered by the injection activity. The area of review is delineated using computational 

modeling that accounts for the physical and chemical properties of all phases of the injected CO2 stream 

and is based on available site characterization, monitoring, and operational data. The definition in the 

proposed rule accounted for the varying physical and chemical properties of the CO2, including freephase and water-dissolved CO2. The definition in the final rule will continue to do so. 

EPA is developing guidance on AoR and corrective action at GS Class VI sites to assist owners or 

operators and Directors in evaluating requirements and proposed AoR and corrective action plans under 

146.84. The guidance describes EPA's recommended approaches for the data to be considered in an 

initial AoR delineation, how to apply computational modeling to delineate the AoR, performing 

corrective action at GS sites, and, when appropriate, completing AoR reevaluations. The guidance will 

be available on EPA's web site at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: [In this document, the text in all 

CAPS denotes added text. For redline strikeout version of this attachment see 

PDF Docket ID EPA-HQ-OW-2008-0390-0170.] 

Rule Provision: 144.3 

API Comments: ENHANCED OIL RECOVERY (EOR) OR ENHANCED GAS RECOVERY (EGR) 

MEANS 

ANY ACTIVITY THAT USES FLUIDS, GASES OR OTHER MEANS TO IMPROVE OR 

INCREASE 

EXTRACTION OF HYDROCARBONS. 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24130

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24133

107
Rationale: The definition of EOR is necessary to support further comments and 

discussion below. 

Response: EPA included the following definition for Enhanced Oil or Gas Recovery in the preamble to 

the rule: typically, the process of injecting a fluid (e.g., water, brine, or CO2) into an oil or gas bearing 

formation to recover residual oil or natural gas. The injected fluid thins (decreases the viscosity) and/or 

displaces small amounts of extractable oil and gas, which is then available for recovery. This is also 

known as secondary or tertiary recovery. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment); 4400 2.4.4.3 

Allowing injection above or between USDWs (seeking comment) 

Comment: Rule Provision: 144.6 

API Comments: Sections 144.6 - Classification of Wells: 

(b) Class II. Wells which inject fluids:... 

(4) FOR ENHANCED RECOVERY OF OIL OR NATURAL GAS WHERE GEOLOGIC 

SEQUESTRATION IS 

OCCURRING DURING OR IN CONNECTION WITH ENHANCED RECOVERY OF OIL OR 

NATURAL GAS 

PROVIDED (I) THERE IS REASONABLE EXPECTATION OF MORE THAN INSIGNIFICANT 

FUTURE 

PRODUCTION VOLUMES OR RATES AS A RESULT OF CARBON DIOXIDE INJECTION AND 

(II) 

OPERATING PRESSURES ARE NO HIGHER THAN REASONABLY NECESSARY TO PRODUCE 

SUCH 

VOLUMES OR RATES; AND 

(5) FOR GEOLOGIC SEQUESTRATION IN OIL AND GAS FORMATIONS AND WHERE THE 

CRITERIA 

OF PARAGRAPH (B)(4) ARE NOT MET 

(f) Class VI. Wells used EXCLUSIVELY for geologic sequestration of carbon 

dioxide STREAMS. beneath the lowermost formation containing a USDW WELLS 

WHERE GEOLOGIC SEQUESTRATION OF CO2 STREAMS OCCURS DURING OR IN 

CONNECTION WITH 

EOR OR EGR ARE REGULATED UNDER CLASS II. 

Rationale: Additionally, there should not be a blanket prohibition concerning 

injection above USDW’s or at specific depths. This is especially true given the 

possibility of changes in the definition of a USDW to include formations greater 

than 10,000 parts per million Total Dissolved Solids. This requirement is not 

necessary for the protection of USDWs and would remove a vast number of viable 

formations from consideration. Industry has shown that it can operate CO2 

injection wells in an EOR context without endangering USDWs that are located 

below the injection zone. An excellent example is the Salt Creek EOR project in 

Wyoming, which has a USDW below the injection zone. Moreover, under the proposed 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24134

108
rule, there are other measures that would provide real assurance of formation 

integrity and require operators to demonstrate that their project will not 

endanger USDWs, making the lowermost USDW restriction unnecessary. 

Response: EPA did not make the suggested change. EPA clarifies that the final rule requires that 

injection for GS be into non-USDWs below the lowermost USDW; however, owners or operators may 

apply for a waiver from this requirement, as described in §146.95. For more information, see the 

discussion of waivers in the preamble to the final rule. 

The Agency disagrees that wells injecting CO2 for the primary purpose of long-term storage should be 

regulated under Class II requirements. The Agency believes that the nature and risks of CO2 injection 

for the primary purpose of long-term storage pose different risks than injection for the primary purpose 

of ER, and therefore has developed new Class VI regulations to address these unique risks. For example, 

the volume of CO2 anticipated to be injected for long-term storage is significantly greater than for ER 

operations. Reservoir pressure conditions will also be different, with Class VI injection operations 

involving large volumes of CO2 and likely having higher pressures within their storage formations than 

Class II ER projects. 

The final Class VI regulations require that any owner or operator injecting CO2 for the primary purpose 

of long term storage obtain a Class VI permit with some special consideration for the fact that they are 

transitioning from a well not originally designed to meet Class VI requirements. The Director has the 

authority to determine at what point a Class VI permit is required for those projects that are transitioning 

from the primary purpose of EOR to long term storage of CO2. The final regulation provides a set of 

technical factors for the Director to evaluate in making this determination, at §144.19. EPA believes that 

this approach provides sufficient protection of USDWs when there is an increased risk to USDWs as 

compared to traditional Class II operations while allowing for site-specific flexibility. For more 

information, please see the discussion on transition of Class II wells in the preamble to the final GS rule.

EPA is developing guidance on transitioning permits from Class II to Class VI. The guidance will assist 

Directors in determining whether an injection project should be transitioned from Class II, where the 

primary purpose is oil and gas production, to Class VI, where the primary purpose is long-term storage 

of large volumes of CO2. The guidance describes the recommended methods the Director may use to 

determine changes in risk to USDWs from projects, and how the Director may determine whether a 

project should be regulated within the Class II or Class VI UIC program. This guidance will be available 

on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment); 4324 2.4.4.1.2 

Comments opposed to requiring injection below the lowermost USDW 

Comment: Rule Provision: 144.80 

API Comments: b) Class II. Wells which inject fluids:...... (4) FOR ENHANCED 

RECOVERY OF OIL OR NATURAL GAS WHERE GEOLOGIC SEQUESTRATION IS 

OCCURRING DURING 

OR IN CONNECTION WITH ENHANCED RECOVERY OF OIL OR NATURAL GAS PROVIDED 

(I) THERE 

IS REASONABLE EXPECTATION OF MORE THAN INSIGNIFICANT FUTURE PRODUCTION 

VOLUMES 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24137

109
OR RATES AS A RESULT OF CARBON DIOXIDE INJECTION AND (II) OPERATING 

PRESSURES 

ARE NO HIGHER THAN REASONABLY NECESSARY TO PRODUCE SUCH VOLUMES OR 

RATES; AND 

(5) FOR GEOLOGIC SEQUESTRATION IN OIL AND GAS FORMATIONS AND WHERE THE 

CRITERIA 

OF PARAGRAPH (B)(4) ARE NOT MET 

(f) Class VI. Wells used EXCLUSIVELY for geologic sequestration of carbon 

dioxide STREAMS. WELLS WHERE GEOLOGIC SEQUESTRATION OF CO2 STREAMS 

OCCURS DURING 

OR IN CONNECTION WITH EOR OR EGR ARE REGULATED UNDER CLASS II. 

Rationale: See 144.6 

Response: As described above regarding the suggested edit at 144.6, EPA did not make the suggested 

change. The Agency disagrees that wells injecting CO2 for the primary purpose of long-term storage 

should be regulated under Class II requirements. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment); 4324 2.4.4.1.2 

Comments opposed to requiring injection below the lowermost USDW 

Comment: Rule Provision: 146.5 

API Comments: b) Class II. Wells which inject fluids:...... (4) FOR ENHANCED 

RECOVERY OF OIL OR NATURAL GAS WHERE GEOLOGIC SEQUESTRATION IS 

OCCURRING DURING 

OR IN CONNECTION WITH ENHANCED RECOVERY OF OIL OR NATURAL GAS PROVIDED 

(I) THERE 

IS REASONABLE EXPECTATION OF MORE THAN INSIGNIFICANT FUTURE PRODUCTION 

VOLUMES 

OR RATES AS A RESULT OF CARBON DIOXIDE INJECTION AND (II) OPERATING 

PRESSURES 

ARE NO HIGHER THAN REASONABLY NECESSARY TO PRODUCE SUCH VOLUMES OR 

RATES; AND 

(5) FOR GEOLOGIC SEQUESTRATION IN OIL AND GAS FORMATIONS AND WHERE THE 

CRITERIA 

OF PARAGRAPH (B)(4) ARE NOT MET 

(f) Class VI. Wells used EXCLUSIVELY for geologic sequestration of carbon 

dioxide STREAMS. Beneath the lowermost formation containing an underground 

source of drinking water (USDW). WELLS WHERE GEOLOGIC SEQUESTRATION OF CO2 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24138

110
STREAMS OCCURS DURING OR IN CONNECTION WITH EOR OR EGR ARE REGULATED 

UNDER CLASS 

II. 

Rationale: See 144.6 

Response: As described above regarding the suggested edit at 144.6, EPA did not make the suggested 

change. The Agency disagrees that wells injecting CO2 for the primary purpose of long-term storage 

should be regulated under Class II requirements. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

EPA clarifies that the final rule requires that injection for GS be into non-USDWs below the lowermost 

USDW; however, owners or operators may apply for a waiver from this requirement, as described in 

§146.95. For more information, see the discussion of waivers in the preamble to the final rule. 

EPA acknowledges that there are limited circumstances where injection above the lowermost USDW 

can be performed in a manner that protects USDWs from endangerment, as long as appropriate 

protections are in place. However, EPA disagrees with the suggested addition to the regulation. The final 

GS rule at §146.95 establishes a process by which owners or operators can seek a waiver of the Class VI 

injection depth requirements for injection into non-USDW formations above and/or between USDWs. It 

establishes: 1) requirements specifying information that owners or operators must submit, and Directors 

must consider, in consultation with PWSS Directors; 2) procedures for public notice of a waiver 

application and for Director-Regional Administrator communication; 3) the waiver issuance process; 

and, 4) additional requirements that apply to owners or operators of Class VI wells granted a waiver of 

the injection depth requirements to ensure USDW protection above and below the injection zone. 

Other EPA Comment Codes and Descriptions: 3200 2.2 Proposed Area of Review and Corrective 

Action Requirements (40 CFR 146.84) 

Comment: Rule Provision: 146.81(d) [Definition - Area of review] 

API Comments: Area of review means the region surrounding the geologic 

Sequestration project that may be impacted by the injection activity. The area 

of review is based on computational modeling that accounts for the physical and 

chemical properties of all phases of the injected carbon dioxide stream. 

SUBSURFACE THREE-DIMENSIONAL EXTENT OF THE CARBON DIOXIDE PLUME, 

ASSOCIATED 

PRESSURE FRONT, AS WELL AS THE OVERLYING FORMATIONS AND SURFACE AREA 

ABOVE THAT 

DELINEATED REGION. 

Rationale: Defining the AOR based on the extent of the CO2 plume and its 

associated pressure front is a more direct approach, rather than the approach 

offered by the EPA. The EPA definition suggests that the computational approach 

defines the AOR rather than the potential risks of the injection activity. 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24142

111
Response: EPA disagrees that the AoR definition needs to specifically include the overlying formations 

and surface area above the delineated region. The intent of the AoR, a long-standing concept within the 

UIC Program, is to delineate the surface area and all subsurface formations below it that may potentially 

be impacted by injection activity. Acceptable delineation models will provide predictions of CO2 fate 

and transport, as well as changes in formation pressure in three dimensions as a function of time that can 

be used to delineate the subsurface storage site and the AoR. Although EPA disagrees with the 

commenter's suggested change, the Agency has carefully considered all comments on the AoR definition 

at 146.84(a) and modified it to read as follows: The region surrounding the geologic sequestration 

project where USDWs may be endangered by the injection activity. The area of review is delineated 

using computational modeling that accounts for the physical and chemical properties of all phases of the 

injected CO2 stream and is based on available site characterization, monitoring, and operational data. 

EPA believes that this definition is sufficiently broad and describes both the intent of the computational 

modeling and the relationship of the AoR to areas that are subject to the risks associated with injection. 

Other EPA Comment Codes and Descriptions: 1630 1.3.3 RCRA/hazardous waste issues (seeking 

comment) 

Comment: Rule Provision: 146.81(d) [Definition - Carbon dioxide stream] 

API Comments: Carbon dioxide stream means carbon dioxide, IN ANY PHYSICAL STATE 

OR FORM, AND ANY ASSOCIATED substances derived from the that has been captured 

from an emission source (e.g., a power plant), plus incidental associated 

substances derived from the source materials and the capture process, and any, 

ITS PROCESSING, OR substances added to enable or improve the injection process. 

This subpart does not apply to any carbon dioxide stream that meets the 

definition of a hazardous waste under 40 CFR part 261. 

Rationale: Source of CO2 is not an issue in the context of defining the CO2 

stream. The rule applies to the injection of CO2 and should not address the 

origins of the materials since that is beyond the scope of this regulation. 

Original text would have precluded injection of CO2 from some sources. 

Response: The final GS rule retains the definition of a CO2 stream as proposed. The GS regulation 

applies to injection of CO2 for the purpose of GS, regardless of the source of the CO2. It is beyond the 

scope of the GS rule and the UIC Program’s authority to require or set standards for upstream generators 

of CO2 or purification facilities. For purposes of GS, the UIC program’s authority under the SDWA is 

limited to ensuring that GS projects are sited, constructed, operated, and closed in a manner that protects 

USDWs. 

Comment: Rule Provision: 146.81(d) [Definition - Geologic sequestration] 

API Comments: Geologic sequestration means the long-term containment of a 

gaseous, liquid or supercritical carbon dioxide stream in subsurface geologic 

formations. This term does not apply to its capture or transport. 

Rationale: Added to definition of carbon dioxide stream, so not needed here. 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24143

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24144

112
Response: EPA disagrees with the suggested edit; the final definition of geologic sequestration at 

§146.81(d) reads as follows: “[T]he long-term containment of a gaseous, liquid, or supercritical carbon 

dioxide stream in subsurface geologic formations. This term does not apply to carbon dioxide capture or 

transport.” 

The final definition of carbon dioxide stream also remains unchanged. Carbon dioxide stream is defined 

at §146.81(d) as: “[C]arbon dioxide that has been captured from an emission source (e.g., a power 

plant), plus incidental associated substances derived from the source materials and the capture process, 

and any substances added to the stream to enable or improve the injection process. This subpart does not 

apply to any carbon dioxide stream that meets the definition of a hazardous waste under 40 CFR part 

261.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 4324 2.4.4.1.2 Comments opposed to requiring 

injection below the lowermost USDW 

Comment: Rule Provision: 146.81(d) [Definition - Geologic sequestration project] 

API Comments: Geologic sequestration project means an injection well or wells 

used to emplace a carbon dioxide stream beneath the lowermost formation 

containing a USDW INTO AN INJECTION ZONE EXCLUSIVELY FOR THE PURPOSE OF 

GEOLOGIC SEQUESTRATION. It includes the subsurface three-dimensional extent of 

the carbon dioxide plume, associated pressure front, and displaced brine, as 

well as the surface area above that delineated region. 

Rationale: There should not be a blanket prohibition concerning injection above 

USDW’s or at specific depths. This requirement is not necessary for the 

protection of USDWs and would remove a vast number of viable formations from 

consideration. Industry has shown that it can operate CO2 injection wells in an 

EOR context without endangering USDWs that are located below the injection zone. 

An excellent example is the Salt Creek EOR project in Wyoming, which has a USDW 

below the injection zone. Moreover, under the proposed rule, there are other 

measures that would provide real assurance of formation integrity and require 

operators to demonstrate that their project will not endanger USDWs, making the 

lowermost USDW restriction unnecessary. 

Response: EPA acknowledges that there are limited circumstances where injection above the lowermost 

USDW can be performed in a manner that protects USDWs from endangerment, as long as appropriate 

protections are in place. However, EPA disagrees with the suggested change. For additional information, 

please see the final rule at §146.95 and the preamble, as well as EPA's responses to comments on the 

Notice of Data Availability and Request for Comment. 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24145

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24146

113
Comment: Rule Provision: 146.81(d) [Definition - Injection zone] 

API Comments: Injection zone means a geologic formation, group of formations, or 

part of a formation that is of sufficient areal extent, thickness, porosity, 

and permeability to receive carbon dioxide RECEIVING FLUIDS through a well 

or wells associated with a geologic sequestration project 

Rationale: Existing definition in the CFR is sufficient and does not need to be 

changed. Furthermore, adding the sufficiency requirement is not a definitional 

issue and should be dealt with elsewhere. 

Response: EPA disagrees with the suggested edit. The final definition of injection zone at §146.81(d) 

remains unchanged, and reads as follows: “[A] geologic formation, group of formations, or part of a 

formation that is of sufficient areal extent, thickness, porosity, and permeability to receive carbon 

dioxide through a well or wells associated with a geologic sequestration project.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: Rule Provision: 146.81(d) [Definition - Post-injection site care] 

API Comments: Post-injection site care means appropriate monitoring and 

other actions (including corrective action) needed following cessation of 

injection to assure that USDWs are not endangered, AS REQUIRED UNDER 

§146.93. 

Rationale: Deleted "appropriate" because the definition of it is not clear. 

Deleted USDW phrase because it is incorporated in 146 requirements. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. EPA adds that the owner or operator must 

monitor as specified in the post-injection site care and site closure plan for at least 50 years or for the 

duration of the alternative timeframe approved by the Director pursuant to requirements in §146.93(c), 

unless the owner or operator can make a demonstration earlier that the geologic sequestration project no 

longer poses a risk of endangerment to USDWs. 

Comment: Rule Provision: 146.81(d) [Definition - Pressure front] 

API Comments: Pressure front means the zone of elevated pressure that is created 

by the injection of the carbon dioxide STREAM into the subsurface, For the 

purposes of this subpart, the pressure front of a carbon dioxide plume refers to 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24147

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24148

114
a zone where there is a pressure differential sufficient to cause movement of 

injected fluids THE CARBON DIOXIDE STREAM or formation fluids FROM THE 

INJECTION ZONE into a USDW. 

Rationale: Clarification. 

Response: EPA disagrees with the suggested edit. The final definition of pressure front at §146.81(d) 

remains unchanged, and reads as follows: “[T]he zone of elevated pressure that is created by the 

injection of carbon dioxide into the subsurface. For the purposes of this subpart, the pressure front of a 

carbon dioxide plume refers to a zone where there is a pressure differential sufficient to cause the 

movement of injected fluids or formation fluids into a USDW.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: Rule Provision: 146.81(d) [Definition - Site closure] 

API Comments: Site closure MEANS the point/time, as determined by the Director 

following the requirements under §146.93, at which the owner or operator of a GS 

site PROJECT is released from post-injection site care responsibilities. 

Rationale: "GS project" is consistent with other definitions. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: Rule Provision: 146.81(d) [Definition - Transmissive fault or fracture] 

API Comments: Transmissive fault or fracture means a fault or fracture that has 

sufficient permeability and vertical extent to allow fluids to move between 

formations BEYOND THE CONFINING ZONE. 

Rationale: The term "between formations" is inaccurate since there can be 

multiple formations within a injection zone. The critical factor for 

transmissivity is movement of injected or displaced fluids beyond the confining 

zone. 

Response: EPA acknowledges the comment but is retaining the requirement in the final rule as 

originally proposed under §146.81(d). EPA has retained the definition in the final rule, which is the 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24149

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24150

115
same as the existing definition at §148.2, to address transmissive faults and fractures that extend beyond 

the confining zone. 

Other EPA Comment Codes and Descriptions: 4400 2.4.4.3 Allowing injection above or between 

USDWs (seeking comment) 

Comment: Potential USDW Above 10,000 TDS: 

Since states and water utilities in many areas of the U.S. are currently 

addressing drought and water rights and availability issues, the proposed rule 

should provide for states to include protections for well sites with potentially 

viable sources of drinking water, such as saline aquifers and aquifers above 

10,000 (mg/L) total dissolved solids (TDS) level that might serve as a viable 

drinking water source. ASDWA recommends that states be allowed regulatory 

flexibility to consider these aquifers as potential drinking water sources. 

Please note that there is some variance among states with regard to this issue. 

While some states would like Congress to consider changing the current Safe 

Drinking Water Act (SDWA) language to preclude these aquifers as potential 

sequestration sites, other states are actively looking for additional 

sequestration sites and would prefer that the proposed regulation and the 

current Safe Drinking Water Act (SDWA) language keep the current 10,000 TDS 

(mg/L) definition for a USDW. Thus, we recommend state-specific flexibility on 

this matter. 

Response: EPA is not changing the USDW definition; changing the definition of a USDW is outside the 

scope of the GS rulemaking. The GS rule focuses on ensuring protection of USDWs, as required under 

the SDWA, by establishing regulations to ensure the safe injection of CO2 for long-term storage. 

EPA recognizes that there is increasing demand for water resources and that technology improvements 

may make high TDS aquifers viable drinking water sources. EPA believes these potential resources 

should be considered when injection depth waivers are sought. Therefore, the final GS rule at §146.95

(b) requires the Director to consider these issues in determining whether an injection depth waiver is 

appropriate. Specifically, the Director must consider whether alternative injection sites are available; 

community needs, demands, and supply from drinking water resources; planned needs, potential and/or 

future use of USDWs and non-USDWs in the area; and a plan for securing alternative resources or 

treating USDW formation waters in the event of contamination related to the Class VI injection activity. 

For additional information on the waiver approach, please see the final rule and preamble, as well as 

EPA's responses to comments on the Notice of Data Availability and Request for Comment. 

Other EPA Comment Codes and Descriptions: 3200 2.2 Proposed Area of Review and Corrective 

Action Requirements (40 CFR 146.84) 

Comment: Corrective action - As a threshold matter, USWAG believes that the terminology 

used in the Proposal is problematic; use of the phrase "corrective action" to 

describe well plugging and repair risks confusion with the concept of corrective 

action under either RCRA or CERCLA. As the GAO Report cautions, public 

Commenter Name: James Taft Letter ID: 0172

Commenter Organization: Association of State Drinking Water Administrators 

(ASDWA)

Comment ID: 

23451

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23487

116
perception is critical to the development of a commercially viable CO2 GS 

program. GAO Report at 49. To avoid any unintended and unwarranted negative 

associations with the phrase "corrective action," USWAG suggests the Final Rule 

abandon this phrase and instead use a phrase such as "well plugging and repair." 

Response: EPA notes that the term "corrective action" at 146.84(d) has been used to describe the 

process of addressing improperly plugged wells in the AoR of injection wells since the inception of the 

UIC Program, e.g., at 146.7 and 146.64. While EPA is aware that the term has a different meaning under 

RCRA and CERCLA, this has not caused confusion in the past. The alternative term, "well plugging," 

suggested by the commenter is reserved for injection well plugging (as indicated at 146.92). 

Other EPA Comment Codes and Descriptions: 4400 2.4.4.3 Allowing injection above or between 

USDWs (seeking comment) 

Comment: A related issue is how USDW are to be defined under the proposed rules. Current 

UIC regulations, as well as the preamble to the proposed rules, define USDW as: 

An aquifer or portion of an aquifer that supplies any public water 

system or that contains a sufficient quantity of ground water to supply 

a public water system, and currently supplies drinking water for human 

consumption, or that contains fewer than 10,000 mg/l total dissolved 

solids and is not an exempted aquifer. 

EEI recommends that the Agency work within the current definition of USDW, in 

particular its maximum total dissolved solids (TDS) provision, for purposes of 

CO2 injection and storage. Any change in the definition of USDW would likely 

require a statutory amendment. The legislative history of SDWA identifies the 

10,000 TDS standard as one sufficient to ensure that potential drinking water 

sources that may be tapped in the future are protected,[FN6] and EPA has long 

recognized this standard in its regulations without any serious suggestion over 

the long and successful history of the UIC program that the standard is 

inadequate. Thus, any potential alteration to that standard (which implicates a 

range of public policy issues) should be left to Congress. Some have called for 

potential revision to this standard, but EEI is unaware of any analysis 

supporting the establishment of an alternative standard. Nor is EEI aware of 

any evaluation of the implications of changing this standard for long-standing 

UIC activities, much less on the practicability of CCS as a critical GHG 

mitigation tool. In short, even if Congress‘s original expression of the 10,000 

mg/l standard did not constrain EPA‘s ability to change this standard by 

regulation, EEI is unaware of any foundation in the administrative record that 

would allow EPA to provide reasoned support for such a change. 

[FN6] See H.R. Rep. 93-1185 (1974), reprinted in 1974 U.S.C.C.A.N. 6454, 6484. 

Response: EPA is not changing the USDW definition; changing the definition of a USDW is outside the 

scope of the GS rulemaking. The GS rule focuses on ensuring protection of USDWs, as required under 

the SDWA, by establishing regulations to ensure the safe injection of CO2 for long-term storage. 

EPA recognizes that there is increasing demand for water resources and that technology improvements 

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23582

117
may make high TDS aquifers viable drinking water sources. EPA believes these potential resources 

should be considered when injection depth waivers are sought. Therefore, the final GS rule at §146.95

(b) requires the Director to consider these issues in determining whether an injection depth waiver is 

appropriate. Specifically, the Director must consider whether alternative injection sites are available; 

community needs, demands, and supply from drinking water resources; planned needs, potential and/or 

future use of USDWs and non-USDWs in the area; and a plan for securing alternative resources or 

treating USDW formation waters in the event of contamination related to the Class VI injection activity. 

For additional information on the waiver approach, please see the final rule and preamble, as well as 

EPA's responses to comments on the Notice of Data Availability and Request for Comment. 

Other EPA Comment Codes and Descriptions: 1230 1.1.1.2 General comments on the regulatory text 

Comment: G. VAGUE LANGUAGE AND DEFINITIONAL PROBLEMS 

There are many words and phrases in the draft regulations that are not well 

defined, and the meaning of which ought to be expanded upon. For instance, what 

might constitute "significant leakage" in the context of mechanical integrity 

testing should be identified. 

Response: A properly designed and operated well should have no leakage in the casing, tubing, or 

packer and no fluid movement into a USDW through channels adjacent to the wellbore. While the intent 

of MITs is to detect these types of problems as early as possible, the goal of the well design and 

construction requirements at §146.86 is the complete absence of such problems. EPA clarifies that the 

purpose of the "significant leakage" language in this narrow context is simply to avoid triggering 

corrective actions for essentially de minimis situations. Determining whether a MIT result should trigger 

follow-up action is necessarily a case and site-specific situation; as a result, EPA does not believe it is 

appropriate to define the term "significant leakage" in the context of MITs. In addition, EPA has not 

defined this term for purposes of other injection well classes and this has not been shown to hinder 

permitting authorities' and owners or operators' ability to assess whether injection wells have adequate 

mechanical integrity. EPA believes that this approach allows states flexibility, will not interfere with the 

implementation of existing UIC programs, and maintains protection of USDWs from endangerment. 

The final definition of mechanical integrity is unchanged. EPA clarifies that mechanical integrity is 

defined at §146.89(a) as the absence (1) of significant leak in the casing, tubing, or packer and (2) of 

significant fluid movement into a USDW through channels adjacent to the injection wellbore. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: EPA defines "area of review" as "the region surrounding the geologic 

sequestration project that may be impacted by the injection activity. The area 

of review is based on computational modeling that accounts for the physical and 

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23820

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23874

118
chemical properties of all phases of the injected carbon dioxide stream." The 

phrase "may be impacted" is too vague, The AoR delineation should be based on or 

limited by certain risk criteria; otherwise, an AoR could cover an 

inappropriately large area that could be expensive to review and characterize. 

Response: EPA agrees with commenters that further clarity is needed with regard to the boundaries of 

the AoR. After considering the public comments on the proposed GS regulation, EPA has augmented 

the definition of AoR to better encompass the area that may be impacted by the injection activity (i.e., 

the "surrounding area" to which the commenter refers). The Agency has modified the AoR definition at 

146.84(a) to read as follows: The region surrounding the geologic sequestration project where USDWs 

may be endangered by the injection activity. The area of review is delineated using computational 

modeling that accounts for the physical and chemical properties of all phases of the injected CO2 stream 

and is based on available site characterization, monitoring, and operational data. 

EPA is developing guidance on AoR and corrective action at GS Class VI sites to assist owners or 

operators and Directors in evaluating requirements and proposed AoR and corrective action plans under 

146.84. The guidance describes EPA's recommended approaches for the data to be considered in an 

initial AoR delineation, how to apply computational modeling to delineate the AoR, performing 

corrective action at GS sites, and, when appropriate, completing AoR reevaluations. The guidance will 

be available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: The term "geological sequestration project" is defined as an injection well or 

wells used to emplace a CO2 stream beneath the lowermost formation containing a 

USDW, including the subsurface three-dimensional extent of the CO2 plume, 

associated pressure front, and displaced brine, as well as the surface area 

above that delineated region. We recommend removing the phrase "beneath the 

lowermost formation containing a USDW to reflect our comment suggesting that EPA 

permit CCS projects above USDWs where feasible. The AoR definition includes 

additional area that might be impacted and is not defined in terms of the extent 

of this area. 

Response: EPA agrees that the geological sequestration project definition should account for the limited 

circumstances where injection above the lowermost USDW can be performed in a manner that protects 

USDWs. The Agency has modified the final definition of geologic sequestration project to read as 

follows: “Geologic sequestration project means an injection well or wells used to emplace a carbon 

dioxide stream beneath the lowermost formation containing a USDW; or, wells used for geologic 

sequestration of carbon dioxide that have been granted a waiver of the injection depth requirements 

pursuant to requirements at §146.95; or, wells used for geologic sequestration of carbon dioxide that 

have received an aquifer exemption expansion. It includes the subsurface three-dimensional extent of the 

carbon dioxide plume, associated pressure front, and displaced brine, as well as the surface area above 

that delineated region.” 

The final Class VI GS rule at §146.95 establishes a process by which owners or operators can seek a 

waiver of the Class VI injection depth requirements. The waiver approach requires the submission of 

extensive, site-specific information (in conjunction with the permit application submission) to 

demonstrate that injection of CO2 into a non-USDW that is above or between USDWs can be done in a 

manner that is protective of USDWs. The requirements are designed to ensure that the owner or 

operator, the Director, and the Regional Administrator consider, on a site specific basis, the 

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23875

119
implications, benefits, and challenges associated with GS and ensuring water availability and USDW 

protection. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 4500 2.5 Proposed Mechanical Integrity Testing 

(MIT) Requirements (40 CFR 146.89) 

Comment: EPA defines "mechanical integrity" as "the absence of significant leakage within 

the injection tubing, casing, or packer (known as internal mechanical 

integrity), or outside of the casing (known as external mechanical integrity)." 

The term "significant leakage" is not defined. An overly broad interpretation 

could result in a finding that mechanical integrity is not being maintained, 

notwithstanding the absence of any leakage that calls into question the safety 

of the project or threatens USDWs. EPA should characterize what constitutes 

"significant" or clarify under what conditions significant leakage might be 

construed. We suggest defining and construing the term within the statutorily 

defined concept of "endangerment"[FN52] under SDWA, i.e., significant leakage 

would be defined as any leakage that could potentially endanger a USDW. The 

amount of leakage and what constitutes significant may vary depending upon the 

geologic formations and proximity to USDWs.[FN53] 

[FN52] Endangerment is defined as follows: 

Underground injection endangers drinking water sources if such injection 

may result in the presence in underground water which supplies or can 

reasonably be expected to supply any public water system of any 

contaminant, and if the presence of such contaminant may result in such 

system's not complying with any national primary drinking water 

regulation or may otherwise adversely affect the health of persons. 32 

U.S.C. $ 300h(d). 

[FN53] Miami-Dade County. EPA, 529 F.3d 1049 (11th Cir. 2008) (upholding 

EPA's rule eliminating the non-endangerment finding requirement for Class I 

municipal injection wells). 

Response: A properly designed and operated well should have no leakage in the casing, tubing, or 

packer and no fluid movement into a USDW through channels adjacent to the wellbore. While the intent 

of MITs is to detect these types of problems as early as possible, the goal of the well design and 

construction requirements at §146.86 is the complete absence of such problems. EPA clarifies that the 

purpose of the "significant leakage" language in this narrow context is simply to avoid triggering 

corrective actions for essentially de minimis situations. Determining whether a MIT result should trigger 

follow-up action is necessarily a case and site-specific situation; as a result, EPA does not believe it is 

appropriate to define the term "significant leakage" in the context of MITs. In addition, EPA has not 

defined this term for purposes of other injection well classes and this has not been shown to hinder 

permitting authorities' and owners or operators' ability to assess whether injection wells have adequate 

mechanical integrity. EPA believes that this approach allows states flexibility, will not interfere with the 

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23876

120
implementation of existing UIC programs, and maintains protection of USDWs from endangerment. 

In keeping with its adaptive rulemaking approach, the Agency plans to collect and review data every six 

years on early GS projects, including MIT data, to determine whether the appropriate amount and types 

of information and appropriate documentation are being collected, and to determine if modifications to 

the requirements are appropriate or necessary. For additional information, please see the discussion of 

MITs in the final rule preamble. 

Other EPA Comment Codes and Descriptions: 4400 2.4.4.3 Allowing injection above or between 

USDWs (seeking comment) 

Comment: - The 10,000 mg/l TDS limit for classifying USDWs for the siting of Class VI 

wells needs to be revised upward. 

Response: EPA is not changing the USDW definition; changing the definition of a USDW is outside the 

scope of the GS rulemaking. The GS rule focuses on ensuring protection of USDWs, as required under 

the SDWA, by establishing regulations to ensure the safe injection of CO2 for long-term storage. 

Comment: In its comments, AWWA makes several recommendations for the following specific 

items to be included in the final regulation: 

- Definition of "endangerment" that includes water quality impacts beyond those 

contaminants with MCLs; 

Response: EPA disagrees that endangerment should be defined in the context of the Class VI GS rule. 

Rather, the Agency clarifies that the purpose of the Class VI GS regulation, promulgated under authority 

of the SDWA, is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs 

from endangerment. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 4400 2.4.4.3 Allowing injection above or between 

USDWs (seeking comment) 

Comment: USDW Classification: The best sources of drinking water are already being used 

by utilities. In many areas, population growth is forcing utilities to look 

further or to look at more challenging sources. With the potential impacts from 

climate change, drinking water utilities are facing an even more limited supply 

of fresh drinking water. As a result, many utilities are turning to more 

challenging groundwater sources such as those that are very deep or have high 

salinity concentrations. Additionally, the pumping costs for these deep wells 

are no longer prohibitive given the lack of sufficient water sources. Some of 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23647

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23649

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23661

121
these new sources could fall outside of the current definition of a USDW, in 

that the aquifer has a TDS concentration higher than 10,000 ppm. The proposed 

rule promises protection of USDWs from endangerment, in that the activity does 

not cause a primary drinking water Maximum Contaminant Level (MCL) to be 

exceeded in an USDW or affect human health. There are no anti-degradation 

provisions in the proposed regulation to protect other groundwater supplies, 

such as those aquifers that are not classified as a USDW but have been, or may 

be, identified as a future drinking water source. The definition of a USDW was 

written at a time when many advanced water treatment technologies were generally 

cost prohibitive, and the general thinking that the high-salinity aquifers would 

never be utilized as drinking water sources. 

Technological advances in the area of desalination have reduced many of the 

treatment costs, making it more and more accessible. Many utilities have no 

other choice for new water sources. Ever increasing population and water demands 

have utilities using non-traditional and poorer water sources (see Table 1-1 for 

examples; note that this is not meant to be a comprehensive list of all 

desalination plants in the United States). 

Table 1-1: Water Utilities with More Challenging Water Sources 

[The information below was originally presented as a table. See Docket PDF EPAHQ-OW-2008-0390-0181 to see a copy of the original table.] 

Utility Name: El Paso Water Utilities and Ft.Bliss, Texas 

Water Source: Hueco Bolson Basin 

Usage: 27.5 mgd 

TDS Concentrations: 600 to 4,900 mg/l 

Utility Name: Tampa Bay Water, Florida 

Water Source: Seawater 

Usage: 25 mgd 

TDS Concentrations: 18,000 - 32,000 mg/L 

Utility Name: Yuma Desalting Plant, Arizona 

Water Source: Drainage water 

Usage: 22 mgd 

TDS Concentrations: 3,200 mg/L 

Utility Name: Miami-Dade County, Florida 

Water Source: Florida Aquifer 

Usage: 17.5 mgd (currently under design) 

TDS Concentrations: 1,000 - 5,000 mg/L 

Utility Name: Temescal Desalter Project, California 

Water Source: Temescal Basin 

Usage: 15 mgd 

TDS Concentrations: 700 mg/L 

Utility Name: City of Abilene, Texas 

122
Water Source: Surface water 

Usage: 8.0 mgd 

TDS Concentrations: 1,200 mg/L 

Utility Name: City of Sherman, Texas 

Water Source: Surface water 

Usage: 7.5 mgd 

TDS Concentrations: 900 - 1500 mg/L 

Utility Name: Southmost Regional Water Authority, Texas 

Water Source: Groundwater 

Usage: 6.75 mgd 

TDS Concentrations: 3,500 mg/L 

Utility Name: Lake Granbury SWATS,Texas 

Water Source: Surface water 

Usage: 6.0 mgd 

TDS Concentrations: 1,800 mg/L 

Utility Name: City of Fort Stockton, Texas 

Water Source: Groundwater 

Usage: 6.0 mgd 

TDS Concentrations: 1485 mg/L 

Utility Name: Newport News WTP, Virginia 

Water Source: Lower and Middle Potomac Aquifers 

Usage: 5.7 mgd 

TDS Concentrations: 3600 mg/L 

Utility Name: Alameda County Water District, California 

Water Source: Niles Cone Groundwater Basin 

Usage: 5.0 mgd with expansion to 10 mgd 

TDS Concentrations: 1,100 - 2,400 mg/L 

Utility Name: Pascagoula, Mississippi 

Water Source: Groundwater 

Usage: 4.5 mgd 

TDS Concentrations: 1,000 mg/L 

Utility Name: Dare County North WTP, North Carolina 

Water Source: Groundwater 

Usage: 3.0 mgd 

TDS Concentrations: 4,300 mg/L 

Utility Name: Port Hueneme Brackish Water Facility, California 

Water Source: Groundwater 

Usage: 3.0 mgd 

TDS Concentrations: 1,300 mg/L 

Utility Name: James City Service Authority, Virginia 

Water Source: Middle and Lower Potomac Aquifers 

123
Usage: 2.5 mgd 

TDS Concentrations: 1,000 - 2,400 mg/L 

Utility Name: Buxton, North Carolina 

Water Source: Groundwater 

Usage: 2.0 mgd 

TDS Concentrations: 13,200 mg/L 

Utility Name: Cape May, New Jersey 

Water Source: Groundwater 

Usage: 2.0 mgd 

TDS Concentrations: 2,100 mg/L 

Utility Name: Dare County Cape Hatteras WP, North Carolina 

Water Source: Groundwater 

Usage: 2.0 mgd 

TDS Concentrations: 11,200 mg/L 

Utility Name: Las Animas, Colorado 

Water Source: Groundwater 

Usage: 1.18 mgd 

TDS Concentrations: 3,500 mg/L 

Utility Name: VA Medical Center, Ft. Lyon, Colorado 

Water Source: Groundwater 

Usage: 0.24 mgd 

TDS Concentrations: 800 mg/L 

The use of very deep and/or high salinity groundwater becoming more commonplace 

is only a matter of time. Therefore, we believe the 10,000 mg/L TDS USDW 

definition is no longer appropriate. Given that this regulation does not 

currently extend protection to non-traditional and poorer water sources, AWWA 

believes that these aquifers may be adversely impacted by this rulemaking. These 

aquifers, which have not been previously used as a drinking water source, may be 

in the future, and it is important to make sure that they are adequately 

protected. AWWA recommends that EPA consider the "green-effect" and that, in 

many cases, the overall least cost alternative may be to treat brackish 

groundwater using desalination technology instead of trying to obtain surface 

water as the drinking water source. While the surface water may be less 

expensive to treat, if the utility is located in a dry environment, such as 

Arizona or New Mexico, the pumping costs to transport that water over a large 

distance may be much larger than the cost to treat a brackish groundwater. EPA 

should also consider that as technology evolves, utilities will be able to treat 

a much different set of waters than is currently being treated. Several 

utilities are using sea water or brackish water as drinking water sources, which 

would not have been even remotely considered as a viable option 20 years ago, 

when the TDS limit was originally developed. 

Recognizing that it is difficult to extend protection to these aquifers due to 

the restrictions of the SDWA, AWWA recommends that the regulation be revised to 

124
mandate that, during the project planning process, the owner/operators should 

include state environmental departments as they can provide insight into what 

aquifers currently (not classified as USDWs) might be considered as future 

drinking water sources. The stakeholder process should also involve both 

regional and local planning boards, as well as the local utilities. This process 

will allow for protection to be extended to the non-traditional aquifers, which 

will be necessary given the pressures on water resources that the country will 

be facing in the upcoming century. 

Response: As described above, EPA is not changing the USDW definition; changing the definition of a 

USDW is outside the scope of the GS rulemaking. The GS rule focuses on ensuring protection of 

USDWs, as required under the SDWA, by establishing regulations to ensure the safe injection of CO2 

for long-term storage. 

Other EPA Comment Codes and Descriptions: 1610 1.3.1 Risks to USDWs; 4400 2.4.4.3 Allowing 

injection above or between USDWs (seeking comment) 

Comment: USDW Endangerment: AWWA recommends revision to the definition of "endangerment" 

in the proposed rule. The current definition of endangerment is limited to SDWA 

UIC definition of 10,000 TDS and to primary MCL contamination. Certain healtheffects can be related to concentrations in water of compounds that do not 

exceed the primary MCL. However, under the current language, these potential 

contaminants would not be covered with the protections afforded by the SDWA. 

Response: The Agency acknowledges commenter concerns about water resources and future water 

resource availability. However, modifying the definition of a USDW or “endangerment” is outside the 

scope of the GS rulemaking. USDWs are defined as aquifers currently being used as sources of drinking 

water or those capable of supplying a public water system and they have a total dissolved solids (TDS) 

content of 10,000 milligrams per liter or less as specified in §144.3. EPA adds that concerns about 

contaminants with health effects even at concentrations below the maximum contaminant level should 

be addressed as part of the review process for the national primary drinking water regulations; such 

concerns are outside the scope of this rulemaking. Please note that the definition of “endangerment” has 

been defined by Congress at SDWA §1421(d)(1)(2). 

The primary goal of the UIC Program under the SDWA is to protect USDWs from endangerment in 

order to ensure a reliable supply of drinking water for the American public. The GS rule, as part of the 

UIC program regulations, continues the program’s mandate of ensuring the protection of USDWs. EPA 

expects the tailored permitting, siting, construction, operation, monitoring, and post-injection site care 

requirements in the GS rule to prevent leakage from injection formations and protect USDWs. 

Other EPA Comment Codes and Descriptions: 4400 2.4.4.3 Allowing injection above or between 

USDWs (seeking comment) 

Comment: Safe Drinking Water Act Authority: In its February 2008 stakeholders meeting, 

EPA seemed to imply that it was restricted in what it could regulate and/or 

require under the SDWA for UIC projects to preventing "endangerment of USDW." 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23662

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23667

125
AWWA recognizes that EPA’s regulatory authority is limited by the requirements 

of the SDWA and will be advocating that several portions of the SDWA be amended 

to better protect the nation’s groundwater resources. Issues that we will be 

addressing include: 

1. The definition of a USDW is provided within the SDWA, which may require 

amendment if the quality and accessibility groundwater sources is to be 

protected. We recognize that the 10,000 mg/L TDS limit is very outdated, and 

that a new upper limit should be established and applied when siting Class VI 

wells. We hesitate to recommend any specific number at this point in time, given 

that some drinking water utilities are so stressed for water resources that they 

are investigating extremely non-traditional water sources with high TDS levels. 

2. Endangerment is defined by the SDWA and may need to be redefined to protect 

beneficial uses. The proposed rule seems to be focused on preventing brine from 

the carbon dioxide storage formations from reaching USDWs and/or preventing 

carbon dioxide from contaminating USDWs and causing exceedences of primary MCLs. 

The protective measures of the proposed rule may not be adequate from a source 

water and beneficial use protection standpoint as other changes are likely to 

occur besides exceeding primary MCLs (e.g., increased Fe/Mn, TDS, and lowered pH 

- all of which have secondary MCLs and possible increase in silica and boron, 

which do not have MCLs, but have water quality significance). EPA needs to be 

provided with the regulatory authority to protect against these other types of 

endangerment, and the SDWA should be modified to allow for these protective 

measures to be developed. 

Response: As described above, EPA is not changing the USDW definition; changing the definition of a 

USDW is outside the scope of the GS rulemaking. The GS rule focuses on ensuring protection of 

USDWs, as required under the SDWA, by establishing regulations to ensure the safe injection of CO2 

for long-term storage. 

Other EPA Comment Codes and Descriptions: 4400 2.4.4.3 Allowing injection above or between 

USDWs (seeking comment) 

Comment: IV. COMMENTS ON RULE TEXT 

Part 144.6(f): Would "lowermost USDW" include formations that are not USDW’s at 

the point of injection but become USDW’s within the extent of the expected area 

of influence of the injection plume? AWWA recommends that these types of 

formations be included within the definition of USDW based on the ability of 

carbon dioxide to easily migrate within the confines of an aquifer. 

Response: EPA clarifies that the GS rule (and all of the UIC regulations) requires the protection of all 

USDWs in the AoR of an injection activity. As part of the site characterization process and during AoR 

delineation, owners or operators must identify all USDWs within the AoR, model the full extent of the 

CO2 plume, and demonstrate that all USDWs within the AoR are protected from endangerment. This 

would include USDWs that are laterally connected to non-USDWs, as suggested by the commenter. 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23718

126
Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule 

language; 4400 2.4.4.3 Allowing injection above or between USDWs (seeking comment) 

Comment: Part 146.5(f): There is the possibility that some of the geologic sequestration 

activities will occur in areas where there are no USDWs located in the area of 

review. These wells should still be permitted as Class VI wells, and AWWA 

recommends revising the Class VI definition to: 

(f) Class VI. Wells used for geologic sequestration of carbon dioxide in the 

following applications: 

1. Where carbon dioxide is injected below the lowermost formation containing a 

USDW; and, 

2. Where carbon dioxide is injected in formations where no USDWs exist within 

the zone of elevated pressure associated with the injection well. 

Wells used for the geologic storage of carbon dioxide in formations above the 

lowermost USDW are prohibited. 

This definition would capture all wells associated with geologic carbon 

sequestration activities whether or not a USDW was present in the projected 

footprint of the project. 

Response: In the final rule EPA will allow injection into non-USDWs above or between the lowermost 

USDW where owners or operators can demonstrate that such injection can be performed in a manner 

that protects USDWs from endangerment, as long as appropriate protections are in place. 

EPA adds that, in the final rule at §144.6 (f), Class VI wells are defined as wells that are not 

experimental in nature that are used for geologic sequestration of carbon dioxide beneath the lowermost 

formation containing a USDW; or, wells used for geologic sequestration of carbon dioxide that have 

been granted a waiver of the injection depth requirements pursuant to requirements at §146.95 of this 

chapter; or, wells used for geologic sequestration of carbon dioxide that have received an expansion to 

the areal extent of an existing Class II enhanced oil recovery or enhanced gas recovery aquifer 

exemption pursuant to §§146.4 of this chapter and 144.7(d). 

Other EPA Comment Codes and Descriptions: 1614 1.3.1.2 Impurities in captured CO2; purity 

standards for CO2 

Comment: Part 146.81 AWWA recommends defining the quality of the injection stream and 

establishing a minimum concentration of carbon dioxide. This requirement for the 

injection stream will ensure that the injection of other harmful or undesirable 

gases is limited. Our initial thoughts on this topic would be that 100% of the 

injectate must come from a carbon dioxide capture process and the injectate must 

be at least 98% carbon dioxide. Owner/operators must ensure that the remaining 

2% of the injectate is not made up of compounds that would result in the 

injectate being classified as a hazardous waste. As AWWA is not an expert on 

this topic, we would suggest that EPA pursue research in association with DOE to 

develop a standard for the minimum concentration of carbon dioxide in the 

injection stream. 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23720

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23721

127
Response: As described above, the GS rule does not set generic purity standards for CO2 injectate 

streams (e.g., a percent CO2). The final GS rule retains the definition of a CO2 stream as proposed. 

Comment: Part 146.81(d) AWWA recommends revising the definition of "pressure front" to 

read: 

Pressure front means the zone of elevated pressure that is created by the 

injection of carbon dioxide into the subsurface. For the purposes of this 

subpart, the pressure front of a carbon dioxide plume refers to a zone where 

there is a pressure differential sufficient to cause the movement of injected 

fluids or formation fluids through an injection zone, and/or confining zone, and 

into a USDW. 

Part 146.81(d) AWWA recommends revising the definition of "transmissible fault or 

fracture" to read: 

transmissible fault or fracture means a fault, fracture or other discontinuity 

that has sufficient permeability and vertical extent to allow fluids to move 

between formations. 

Response: EPA disagrees with the suggested edit. The final definition of pressure front at §146.81(d) is 

unchanged and reads as follows: “[T]he zone of elevated pressure that is created by the injection of 

carbon dioxide into the subsurface. For the purposes of this subpart, the pressure front of a carbon 

dioxide plume refers to a zone where there is a pressure differential sufficient to cause the movement of 

injected fluids or formation fluids into a USDW.” 

The final definition of transmissive fault or fracture at §146.81(d) is unchanged and reads as follows: 

“[A] fault or fracture that has sufficient permeability and vertical extent to allow fluids to move between 

formations.” EPA adds that it changed the text at §146.84(c)(1)(ii) to include “other discontinuity” to 

address concern regarding the potential for migration of CO2 at GS sites. It reads as follows: "Take into 

account any geologic heterogeneities, other discontinuities, data quality, and their possible impact on 

model predictions." 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 4400 2.4.4.3 Allowing injection above or between 

USDWs (seeking comment) 

Comment: IV. EPA Should Update the Definition of USDW So that All Current and Viable 

Future Drinking Water Supplies are Protected from GS. 

EPA’s definition of what constitutes an "underground source of drinking water" 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23723

Commenter Name: Wendy Jacobs Letter ID: 0183

Commenter Organization: Harvard Law School Environmental Law and Policy 

Center

Comment ID: 

25164

128
("USDW") is critical, because non-USDWs are not protected against potential 

endangerment from GS operations under the proposed regulation.[FN14] EPA’s 

continued use of a 1980 definition for USDWs, however, means that many nowviable sources of drinking water fall outside the technical definition of 

"USDW," leaving valuable water supplies unprotected by the proposed UIC 

regulation. See 73 Fed. Reg. at 43,492, 43,494. EPA should update the definition 

of USDW to reflect the current state and foreseeable further advancement of 

desalination technology. The definition of USDW should meet the statutory goal 

of ensuring that all aquifers that "can reasonably be expected to supply any 

public water system" are protected from potential contamination. See 42 U.S.C. 

§300h (a)-(b), (d)(2). 

[FN14] 40 C.F.R. §144.3 provides: "[U]SDW means an aquifer or its portion: (a) 

(1) Which supplies any public water system; or 

(2) Which contains a sufficient quantity of ground water to supply a public 

water system; and 

(i) Currently supplies drinking water for human consumption; or 

(ii)Contains fewer than 10,000 mg/L total dissolved solids; and 

(b) Which is not an exempted aquifer." 

Thus, the definition also excludes from "USDW" any aquifer that contains fewer 

than 10,000 mg/L TDS but does not contain "a sufficient quantity of groundwater 

to supply a public water system." 

Since 1980, when EPA first promulgated the UIC regulations, "USDW" has been 

defined narrowly to exclude any aquifer with waters containing more than 10,000 

mg/L (also known as 10,000 p.p.m.) total dissolved solids (TDS). See 

Consolidated Permit Regulations and Technical Criteria and Standards; State 

Underground Injection Programs, 45 Fed. Reg. 42,472, 42,502 (June 24, 1980) 

(Final Rule for 40 C.F.R. § 146 and Amendments to § 122; 40 C.F.R. §146.03 

(1980)). This numerical limit is the creation of regulation, not statute: the 

SDWA directed EPA to protect USDWs by publishing regulations for underground 

injection control programs that include "minimum requirements for effective 

programs to prevent underground injection which endangers drinking water

sources," which the SDWA defined to mean injection which may contaminate any 

"underground water which supplies or can reasonably be expected to supply any 

public water system." See 42 U.S.C. §300h(a)-(b), (d)(2) (emphasis added). 

The legislative history supports the position that Congress intended these terms 

to be construed broadly to effectuate Congress’s "overriding intent to maximize 

protection of the public health." In a 1974 report accompanying the SDWA, the 

House Committee on Interstate and Foreign Commerce explained: 

[Section 1421 of the SDWA] . . . defines "underground injection which endangers 

drinking water sources." It is the Committee’s intent that the definition be 

liberally construed so as to effectuate the preventive and public health 

protective purposes of the bill. The Committee seeks to protect not only 

currently-used sources of drinking water, but also potential drinking water 

sources for the future. This may include water sources which presently exceed 

minimum intake water quality requirements or maximum contaminant levels or which 

are not presently accessible for use as a community drinking water supply 

source. 

129
Thus, for example, the Committee expects the [EPA] Administrator’s regulations 

at least to require States to provide protection for subsurface waters having 

less than 10,000 p.p.m. dissolved solids, as is currently done in Illinois and 

Texas, even though water containing as much as 9,000 p.p.m. would probably 

require treatment prior to human consumption. 

Further contamination of such sources should not be permitted if there is any 

easonable likelihood that these sources will be needed in the future to meet 

the public demand for drinking water and if these sources may be used for such 

purpose in the future. H. R. Rep. No. 93-1185, pt. C, at 32 (1974) (emphasis 

added). 

Thus, the House Committee offered the 10,000 mg/L standard, in 1974, as a 

reference point. Then in 1980, EPA stated that it considered alternative 

proposed concentrations to determine whether any offered "any superior

justification in terms of current State practice, human health, or technological 

considerations," but found that none did. 45 Fed. Reg. at 42,483. Accordingly, 

"[i]n the absence of any overriding argument to the contrary, the Agency will 

follow the standard in the House Committee Report accompanying the SDWA." Id. 

However, improvements in desalination technology since 1974 and 1980 provide 

"superior justification" for increasing the 10,000 mg/L standard. Water with 

TDS concentrations above 10,000 mg/L is desalinated using Reverse Osmosis (RO) 

or Distillation processes that include multistage flash evaporation (MSF), 

multiple effect distillation (MED), and vapor compression (VC). See YUAN ZHOU & 

RICHARD S.J. TOL, EVALUATING THE COSTS OF DESALINATION AND WATER 

TRANSPORT, 

WATER RESOURCES RESEARCH, VOL. 41, available at http://www.unihamburg.de/Wiss 

/FB/15/Sustainability/wrrdesalt.pdf (discussing the variety of desalting 

technologies). The cost-efficiency of these technologies vary with specific site 

characteristics. Accordingly, the cost per unit depends on size and location of 

the desalination plant and is highly linked to the price of electricity. 

"Larger plant capacity reduces the unit cost of water due to economies of scale. 

Lower energy costs and longer plant period reduce unit product water cost." Id. 

The data on desalination costs indicate that per unit cost has decreased since 

the EPA first promulgated the UIC program in 1980. The average cost of 

desalinating high TDS concentrations through RO has fallen from $3.70 per m3 in 

1979 to about $1.33 per m3 in 2001. For the MSF process, the cost has gone down 

from $3.04 m3 in 1979 to $.66 m3 in 2001. As for the ME process, the cost has 

also decreased from $3.56 m3 in 1979 to $1.21 m3 in 2001. Lastly, the average 

unit cost of VC has gone down from $3.72 m3 in 1979 to $1.50 m3 in 2001.[FN15] See 

RESEARCH UNIT SUSTAINABILITY AND GLOBAL CHANGE, HAMBURG UNIVERSITY AND 

CENTRE 

FOR MARINE AND ATMOSPHERIC SCIENCE, available at 

http://www.unihamburg.de/Wiss/FB/15/Sustainability/Models.htm cited in YUAN ZHOU 

& TOL. at 4. 

[FN15] Unit costs are given in terms of 1995 US dollars. See YUAN ZHOU & TOL, 

supra, at 4. 

130
For EPA to meet SDWA’s goal of ensuring that not only all current, but also all 

reasonably expected, sources of drinking water are protected from GS, EPA must 

update the 10,000 mg/L reference to reflect the "reasonable expectations" of 

today based on the current state and foreseeable further advancement of 

desalination technology.[FN16] 

[FN16] Going forward, EPA should consider revising the definition of USDWs on a 

rolling basis to prevent the TDS standard from becoming outdated and the 

resulting endangerment of viable sources of drinking water by GS. In this way, 

EPA will comply with its Congressional mandate to prevent endangerment of USDWs. 

In addition, ELPC and ETIP note that the proposed regulation excludes from 

protection aquifers and wells that likely would not be sufficient to supply 

water to public water systems [FN17] but that are used as a supply of water for 

smaller, private systems. At a minimum, EPA should require that owners of small 

wells be consulted and included in the planning and permitting process for GS 

wells and that provision be made to provide them with an alternative drinking 

water source if necessary. 

[FN17] "The term ‘public water system’ means a system for the provision to the 

public of piped water for human consumption, if such system has at least fifteen 

service connections or regularly serves at least twenty-five individuals." 42 

U.S.C. § 300F(4). 

Response: EPA recognizes that there is increasing demand for water resources and that technology 

improvements may make high TDS aquifers viable drinking water sources. EPA believes these potential 

resources should be considered when injection depth waivers are sought. Therefore, the final GS rule at 

§146.95(b) requires the Director to consider these issues in determining whether an injection depth 

waiver is appropriate. Specifically, the Director must consider whether alternative injection sites are 

available; community needs, demands, and supply from drinking water resources; planned needs, 

potential and/or future use of USDWs and non-USDWs in the area; and a plan for securing alternative 

resources or treating USDW formation waters in the event of contamination related to the Class VI 

injection activity. 

EPA is not changing the USDW definition; changing the definition of a USDW is outside the scope of 

the GS rulemaking. The GS rule focuses on ensuring protection of USDWs, as required under the 

SDWA, by establishing regulations to ensure the safe injection of CO2 for long-term storage. For 

additional information on the waiver approach, please see the final rule and preamble, as well as EPA's 

responses to comments on the Notice of Data Availability and Request for Comment. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: Rule Provision: 144.6(b) 

Proposed CCS Group Recommendations: Add new paragraph (b)(4) 

(4) FOR ENHANCED RECOVERY OF OIL OR NATURAL GAS WHERE GEOLOGIC 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24361

131
SEQUESTRATION IS 

OCCURRING DURING OR IN CONNECTION WITH ENHANCED RECOVERY OF OIL OR 

NATURAL GAS 

PROVIDED (I) THERE IS REASONABLE EXPECTATION OF MORE THAN INSIGNIFICANT 

FUTURE 

PRODUCTION VOLUMES OR RATES AS A RESULT OF CARBON DIOXIDE INJECTION AND 

(II) 

OPERATING PRESSURES ARE NO HIGHER THAN REASONABLY NECESSARY TO PRODUCE 

SUCH 

VOLUMES OR RATES; 

Basis for CCS Group Comments: EPA’s Proposal would continue to regulate and 

permit injection of CO2 for EOR/EGR purposes as Class II injection "as long as 

any production is occurring." EPA has asked for comment on the merits of this 

approach "since owners or operators of some Class II EOR/EGR wells may wish to 

use wells for the purposes of production and GS prior to the field being 

completely depleted." 73 Fed. Reg. at 43502. We recommend that the rules be 

clarified to provide more certainty about the applicability of Class II 

requirements where GS of CO2 occurs in connection with EOR/EGR activities. 

Specifically, the UIC rules should provide a "bright line" definition as to the 

applicable class of wells where CO2 injection for EOR/EGR production and for GS 

occur in tandem. 

The proposed language describing wells in classification (b)(4) establishes a 

"bright line" definition for wells that inject CO2 for EOR/EGR and GS and, 

consistent with EPA’s intent, should remain in Class II and be subject to the 

current requirements of Class II. We have also agreed that the wells used for GS 

in oil and gas reservoirs that do not meet the criteria of (b)(4) should be 

subject to additional requirements. 

This is the same recommendation as presented by the multi-stakeholder group, in 

which the Carbon Sequestration Council participated. 

Response: EPA did not make the suggested change. The Agency disagrees that wells injecting CO2 for 

the primary purpose of long-term storage should be regulated under Class II requirements. The Agency 

believes that the nature and risks of CO2 injection for the primary purpose of long-term storage pose 

different risks than injection for the primary purpose of EOR, and therefore has developed new Class VI 

regulations to address these unique risks. For example, the volume of CO2 anticipated to be injected for 

long-term storage is significantly greater than for EOR operations. Reservoir pressure conditions will 

also be different, with Class VI injection operations involving large volumes of CO2 and likely having 

higher pressures within their storage formations than Class II EOR projects. 

The final Class VI regulations require that any owner or operator injecting CO2 for the primary purpose 

of long term storage obtain a Class VI permit with some special consideration for the fact that they are 

transitioning from a well not originally designed to meet Class VI requirements. The Director has the 

authority to determine at what point a Class VI permit is required for those projects that are transitioning 

from the primary purpose of EOR to long term storage of CO2. The final regulation provides a set of 

technical factors for the Director to evaluate in making this determination, at §144.19. EPA believes that 

this approach provides sufficient protection of USDWs when there is an increased risk to USDWs as 

compared to traditional Class II operations while allowing for site-specific flexibility. 

132
EPA is developing guidance on transitioning permits from Class II to Class VI. The guidance will assist 

Directors in determining whether an injection project should be transitioned from Class II, where the 

primary purpose is oil and gas production, to Class VI, where the primary purpose is long-term storage 

of large volumes of CO2. The guidance describes the recommended methods the Director may use to 

evaluate changes in risk to USDWs from projects, and how the Director may determine whether a 

project should be regulated within the Class II or Class VI UIC program. This guidance will be available 

on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. For more 

information, please see the discussion on transition of Class II wells in the preamble to the final GS rule. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: Rule Provision: 144.6(f) 

Proposed CCS Group Recommendations: (f) Class VI. used for geologic 

sequestration of carbon dioxide beneath the lowermost formation containing a 

USDW. Wells INJECTING A CARBON DIOXIDE STREAM FOR GEOLOGIC SEQUESTRATION 

EXCEPT THOSE WELLS DESCRIBED IN SUBSECTION (B)(4) OF THIS SECTION OR 

OTHERWISE 

EXCLUDED FROM THIS CLASS. 

Basis for CCS Group Comments: The changes to (b) and (f) are to recognize that 

EOR can have a storage component, which is consistent with EPA’s intent as 

expressed in the preamble. It is widely recognized that CO2 based EOR can 

provide a significant early opportunity for carbon storage. As EPA correctly 

recognizes, CO2 EOR operations can have a significant storage component through 

capillary trapping or other mechanisms. Operators experience supports this 

approach as they have seen that between 1/3 to 1/2 of the injected CO2 in EOR 

operations is trapped within the receiving formation during CO2 EOR operations. 

Following abandonment of EOR operations, assuming the CO2 not trapped in the 

receiving formation, has not been produced for use in another field, essentially 

all of the CO2 that has been injected can be permanently stored. 

We recommend that all GS into basalts, coal seams, and salt domes be conducted 

under Class V as experimental wells initially and then as commercial scale Class 

V wells/projects if the experimental projects demonstrate that these sites can 

be suitable for geological sequestration while preventing endangerment of USDWs. 

Keeping these wells under Class V would allow EPA and the states to gain enough 

experience to develop suitable permitting requirements for such wells and to 

tailor those requirements at both the pilot and commercial scales until the 

agencies are ready to adapt the Class VI regulations. 

There should not be a blanket prohibition concerning injection above USDW’s or 

at specific depths. This requirement is not necessary for the protection of 

USDWs and would remove a vast number of viable formations from consideration. It 

has been shown that it is possible to operate CO2 injection wells in an EOR 

context without endangering USDWs that are located below the injection zone. An 

excellent example is the Salt Creek EOR project in Wyoming, which has a USDW 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24362

133
below the injection zone. Under the proposed rule, there are other measures that 

would provide real assurance of formation integrity and require operators to 

demonstrate that their project will not endanger USDWs, making the lowermost 

USDW restriction unnecessary. Instead, operators should be able to show adequate 

containment to prevent endangerment of USDWs both above and below the injection 

zone used for geologic sequestration. 

Response: As described above regarding the suggested edit at 144.6(b), EPA did not make the 

suggested change. The Agency disagrees that wells injecting CO2 for the primary purpose of long-term 

storage should be regulated under Class II requirements. 

Regarding injection into basalts, coal seams, and salt domes, EPA clarifies that the GS rule does not 

categorically preclude injection of CO2 into any non-USDW formation types. The purpose of the GS 

rule is to ensure protection of USDWs from endangerment, and the rule requires that owners or 

operators demonstrate that wells are sited in suitable systems with geologic formations to receive and 

confine injected CO2, as required at §146.83 of the GS rule. The Class VI siting, well construction and 

operation, monitoring and testing, and post-injection site care and site closure requirements are designed 

to ensure that injected CO2 remains within the target formation. If an owner or operator can demonstrate 

to the Director's satisfaction that GS in coal seams, basalts, salt domes, or shales can be accomplished in 

a manner that protects USDWs and meets all of the requirements of the GS rule, the project may be 

permitted as a Class VI well. 

EPA acknowledges that there may be unknown risks associated with GS, particularly regarding GS into 

formations such as coal seams, basalts, and salt domes, which have been the subject of limited 

experimental projects in the past. EPA anticipates that in the short-term, GS into these types of 

formations will continue to be experimental (i.e., if they are to test GS technologies and collect data), 

and will likely be permitted as Class V experimental technology wells and be subject to UIC Program 

Guidance #83. 

EPA is preparing an addendum to UICPG #83 that describes the use of the Class V experimental 

technology well classification to clarify permitting for Class V wells. This addendum will address 

shifting of Class V experimental projects to Class VI projects and the future use of the Class V 

experimental technology well subclass for research and testing of new GS technologies. 

EPA acknowledges that there are limited circumstances where injection above the lowermost USDW 

can be performed in a manner that protects USDWs. The final GS rule at §146.95 establishes a process 

by which owners or operators can seek a waiver of the Class VI injection depth requirements. The 

waiver approach requires the submission of extensive, site-specific information (in conjunction with the 

permit application submittal) to demonstrate that injection of CO2 into a formation that is above or 

between USDWs can be done in a manner that is protective of USDWs. The requirements are designed 

to ensure the owner or operator, the Director, and the Regional Administrator consider, on a site-specific 

basis, the implications, benefits, and challenges associated with GS and ensuring water availability and 

USDW protection. 

Other EPA Comment Codes and Descriptions: 3200 2.2 Proposed Area of Review and Corrective 

Action Requirements (40 CFR 146.84) 

Comment: Rule Provision: 146.81(d) [Definition - Area of review] 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24400

134
Proposed CCS Group Recommendations: Area of review means the region 

surrounding the geologic sequestration project that may be impacted by the 

injection activity. The area of review is based on computational modeling that 

accounts for the physical and chemical properties of all phases of the injected 

carbon dioxide stream. SUBSURFACE THREE-DIMENSIONAL EXTENT OF THE CARBON 

DIOXIDE PLUME, ASSOCIATED PRESSURE FRONT, AS WELL AS THE OVERLYING 

FORMATIONS 

AND SURFACE AREA ABOVE THAT DELINEATED REGION. 

Basis for CCS Group Comments: Defining the AOR based on the extent of the CO2 

plume and its associated pressure front is a more direct approach, rather than 

the approach offered by the EPA. 

Response: EPA disagrees that the AoR definition needs to specifically include the overlying formations 

and surface area above the delineated region. The intent of the AoR, a long-standing concept within the 

UIC Program, is to delineate the surface area and all subsurface formations below it that may potentially 

be impacted by injection activity. Acceptable delineation models will provide predictions of CO2 fate 

and transport, as well as changes in formation pressure, in three dimensions, as a function of time that 

can be used to delineate the subsurface storage site and the AoR. Although EPA disagrees with the 

commenter's suggested change, the Agency has carefully considered all comments on the AoR definition 

at 146.84(a) and modified it to read as follows: The region surrounding the geologic sequestration 

project where USDWs may be endangered by the injection activity. The area of review is delineated 

using computational modeling that accounts for the physical and chemical properties of all phases of the 

injected CO2 stream and is based on available site characterization, monitoring, and operational data. 

EPA believes that this definition is sufficiently broad and describes both the intent of the computational 

modeling and the relationship of the AoR to areas that are subject to the risks associated with injection. 

Other EPA Comment Codes and Descriptions: 1630 1.3.3 RCRA/hazardous waste issues (seeking 

comment) 

Comment: Rule Provision: 146.81(d) [Definition - Carbon dioxide stream] 

Proposed CCS Group Recommendations: Carbon dioxide stream means carbon dioxide, 

IN ANY PHYSICAL STATE OR FORM, AND ANY ASSOCIATED substances derived from the 

that has been captured from an emission source (e.g., a power plant), plus 

incidental associated substances derived from the source materials and the 

capture process, and any OR ITS PROCESSING, AND substances added to enable or 

improve the injection process. This subpart does not apply to any carbon dioxide 

stream that meets the definition of a hazardous waste under 40 CFR part 261. 

Basis for CCS Group Comments: Source of CO2 is not an issue in the context of 

defining the CO2 stream. The rule applies to the injection of CO2 and should not 

address the origins of the materials since that is beyond the scope of this 

regulation. Original text would have precluded injection of CO2 from some 

sources. 

Response: The final GS rule retains the definition of a CO2 stream as proposed. The GS regulation 

applies to injection of CO2 for the purpose of GS, regardless of the source of the CO2. It is beyond the 

scope of the GS rule and the UIC Program’s authority to require or set standards for upstream generators 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24401

135
of CO2 or purification facilities. For purposes of GS, the UIC program’s authority under the SDWA is 

limited to ensuring that GS projects are sited, constructed, operated, and closed in a manner that protects 

USDWs. 

Although the GS regulation does not apply to the source of CO2 streams, the GS rule, at §146.82(a)(7)

(iv), requires the owner or operator to submit data about the site, including an analysis of the chemical 

and physical characteristics of the CO2 stream because the concentrations of minor and trace elements 

in CO2 streams for GS projects are likely to vary by facility, coal composition, plant operating 

conditions, and pollution removal technologies. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: Rule Provision: 146.81(d) [Definition - Confining zone] 

Proposed CCS Group Recommendations: Confining zone means a geological formation, 

group of formations, or part of a formation THAT IS CAPABLE OF LIMITING FLUID 

MOVEMENT FROM AN INJECTION ZONE. 

Basis for CCS Group Comments: The current UIC program definition of confining 

zone is preferable to the proposed definition. There are no special 

circumstances for CO2 streams that warrant a change. In addition, the word 

"above" should be changed to "from" to accommodate situations where USDWs may be 

beneath as well as above the injection zone. 

Response: EPA did not change the requirement that injection occur below the lowermost USDW. 

However, the final GS rule contains a provision (at §146.95) for owners or operators to apply for 

waivers from the requirement that injection be below the lowermost USDW. EPA believes this waiver 

provision will reduce potential limitations on the re-permitting of Class II wells as Class VI wells, 

provided they meet the requirements at §146.95, while still protecting USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: Rule Provision: 146.81(d) [Definition - Corrective action] 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final GS rule retains the definition. 

Comment: Rule Provision: 146.81(d) [Definition - Geologic sequestration] 

Proposed CCS Group Recommendations: Geologic sequestration means the long-term 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24402

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24403

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24404

136
containment of a gaseous, liquid or supercritical carbon dioxide stream in 

subsurface geologic formations. This term does not apply to its capture or 

transport. 

Basis for CCS Group Comments: Added to definition of carbon dioxide stream, so 

not needed here. 

Response: EPA disagrees with the suggested edit. However, the Agency has modified the definition of 

geologic sequestration at §146.81(d) to read as follows: “[T]he long-term containment of a gaseous, 

liquid, or supercritical carbon dioxide stream in subsurface geologic formations. This term does not 

apply to carbon dioxide capture or transport.” 

The final definition of carbon dioxide stream also remains unchanged. Carbon dioxide stream is defined 

at §146.81(d) as: “[C]arbon dioxide that has been captured from an emission source (e.g., a power 

plant), plus incidental associated substances derived from the source materials and the capture process, 

and any substances added to the stream to enable or improve the injection process. This subpart does not 

apply to any carbon dioxide stream that meets the definition of a hazardous waste under 40 CFR part 

261.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 4324 2.4.4.1.2 Comments opposed to requiring 

injection below the lowermost USDW 

Comment: Rule Provision: 146.81(d) [Definition - Geologic sequestration project] 

Proposed CCS Group Recommendations: Geologic sequestration project means an 

injection well or wells used to emplace a carbon dioxide stream beneath the 

lowermost formation containing a USDW INTO AN INJECTION ZONE EXCLUSIVELY FOR 

THE PURPOSE OF GEOLOGIC SEQUESTRATION. It includes the subsurface threedimensional extent of the carbon dioxide plume, associated pressure front, and 

displaced brine, as well as the surface area above that delineated region. 

Basis for CCS Group Comments: There should not be a blanket prohibition 

concerning injection above USDW’s or at specific depths. This requirement is not 

necessary for the protection of USDWs and would remove a vast number of viable 

formations from consideration. Industry has shown that it can operate CO2 

injection wells in an EOR context without endangering USDWs that are located 

below the injection zone. An excellent example is the Salt Creek EOR project in 

Wyoming, which has a USDW below the injection zone. Moreover, under the proposed 

rule, there are other measures that would provide real assurance of formation 

integrity and require operators to demonstrate that their project will not 

endanger USDWs, making the lowermost USDW restriction unnecessary. 

Response: EPA has revised the definition of a geologic sequestration project to account for the new 

requirements to include “wells used for geologic sequestration of carbon dioxide that have been granted 

a waiver of the injection depth requirements pursuant to requirements at §146.95.” 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24405

137
Comment: Rule Provision: 146.81(d) [Definition - Injection zone] 

Proposed CCS Group Recommendations: Injection zone means a geologic formation, 

group of formations, or part of a formation that is of sufficient areal 

extent, thickness, porosity, and permeability to receive carbon dioxide 

RECEIVING FLUIDS through a well or wells associated with a geologic 

sequestration project 

Basis for CCS Group Comments: Existing definition in the CFR is sufficient and 

does not need to be changed. Furthermore, adding the sufficiency requirement is 

not a definitional issue and should be dealt with elsewhere. 

Response: EPA disagrees with the suggested edit. The final definition of injection zone at §146.81(d) is 

unchanged and reads as follows: “[A] geologic formation, group of formations, or part of a formation 

that is of sufficient areal extent, thickness, porosity, and permeability to receive carbon dioxide through 

a well or wells associated with a geologic sequestration project.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: Rule Provision: 146.81(d) [Definition - Post-injection site care] 

Proposed CCS Group Recommendations: Post-injection site care means 

appropriate monitoring and other actions (including corrective action) 

needed following cessation of injection to assure that USDWs are not 

endangered, AS REQUIRED UNDER §146.93. 

Basis for CCS Group Comments: Deleted "appropriate" because the definition of it 

is not clear. Deleted USDW phrase because it is incorporated in 146 

requirements. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. EPA adds that all post-injection site care must 

be performed pursuant to the post-injection site care and site closure plan, which must be approved by 

the Director and demonstrated to include monitoring activities that protect USDWs from endangerment. 

Comment: Rule Provision: 146.81(d) [Definition - Pressure front] 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24406

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24407

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24408

138
Proposed CCS Group Recommendations: Pressure front means the zone of elevated 

pressure that is created by the injection of the carbon dioxide STREAM into the 

subsurface, For the purposes of this subpart, the pressure front of a carbon 

dioxide plume refers to a zone where there is a pressure differential 

sufficient to cause movement of injected fluids THE CARBON DIOXIDE STREAM or 

formation fluids FROM THE INJECTION ZONE into a USDW. 

Basis for CCS Group Comments: Clarification. 

Response: EPA disagrees with the suggested edit. The final definition of pressure front at §146.81(d) 

remains unchanged, and reads as follows: “[T]he zone of elevated pressure that is created by the 

injection of carbon dioxide into the subsurface. For the purposes of this subpart, the pressure front of a 

carbon dioxide plume refers to a zone where there is a pressure differential sufficient to cause the 

movement of injected fluids or formation fluids into a USDW.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: Rule Provision: 146.81(d) [Definition - Site closure] 

Proposed CCS Group Recommendations: Site closure MEANS the point/time, as 

determined by the Director following the requirements under §146.93, at which 

the owner or operator of a GS site PROJECT is released from post-injection 

site care responsibilities. 

Basis for CCS Group Comments: "GS project" is consistent with other definitions. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: Rule Provision: 146.81(d) [Definition - transmissible fault or fracture] 

Proposed CCS Group Recommendations: transmissible fault or fracture means a fault 

or fracture that has sufficient permeability and vertical extent to allow fluids 

to move between formations BEYOND THE CONFINING ZONE. 

Basis for CCS Group Comments: The term "between formations" is inaccurate since 

there can be multiple formations within an injection zone. The critical factor 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24409

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24410

139
for transmissivity is movement of injected or displaced fluids beyond the 

confining zone. 

Response: EPA has retained the proposed definition, which is the same as the existing definition at 

§148.2, to address transmissive faults and fractures that extend beyond the confining zone. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule 

language; 1610 1.3.1 Risks to USDWs; 4400 2.4.4.3 Allowing injection above or between USDWs 

(seeking comment) 

Comment: Issue 3. The proposed regulation currently defines USDWs as zones that contain 

groundwater with a total dissolved solids (TDS) concentration of less than 

10,000 mg/L. This limit should be revised to consider geologic strata with water 

containing higher TDS concentrations, because these zones may be economic in the 

future. 

The technology for treating high TDS water for use in water supply is improving 

rapidly, and these high TDS aquifer zones may be needed in the future. In areas 

with limited water resources water providers are beginning to turn to 

groundwater sources containing in excess of 10,000 mg/L TDS (Sengebush 2008). 

It is already conceivable that in the near future sources with up to 

approximately 20,000 mg/L TDS will be considered viable as water treatment 

technology advances making such water sources economical. To protect 

groundwater resources which may be economical in the foreseeable future the rule 

should evaluate the potential that currently marginal groundwater sources will 

be usable. The repository zones should be limited to strata containing very high 

TDS concentrations that siting studies and public input indicate are not likely 

to be useable in the future, as use of a zone for CO2 sequestration will likely 

preclude recovery and use of the groundwater resource in the future. 

Sengebush, R. M. 2008, INTERA, Inc. Deep Brackish Water Considered for New 

Mexico Development. Southwest Hydrology, March/April 2008, p. 8. Available from 

http://www.swhydro.arizona.edu/archive/V7_N2/dept-ontheground.pdf. 

Response: The Agency acknowledges the commenter’s concerns about water resources and future water 

resource availability. However, modifying the definition of a USDW is outside the scope of the GS 

rulemaking. USDWs are defined as aquifers currently being used as sources of drinking water or those 

capable of supplying a public water system, with a total dissolved solids (TDS) content of 10,000 

milligrams per liter or less, as specified in §144.3. 

The primary goal of the UIC Program under the SDWA is to protect USDWs from endangerment in 

order to ensure a reliable supply of drinking water for the American public. The GS rule, as part of the 

UIC program regulations implementing the SDWA, continues the program’s mandate of ensuring the 

protection of USDWs. EPA expects that the tailored permitting, siting, construction, operation, 

monitoring, and post-injection site care requirements in the GS rule will prevent leakage from injection 

formations and protect USDWs. 

EPA recognizes that there is increasing demand for water resources and that technology improvements 

may make high TDS aquifers viable drinking water sources. EPA believes these potential resources 

Commenter Name: Andy Horn Letter ID: 0196

Commenter Organization: Colorado Ground Water Association (CGWA) Comment ID: 23923

140
should be considered when injection depth waivers are sought. Therefore, the final GS rule at §146.95

(b) requires the Director to consider these issues in determining whether an injection depth waiver is 

appropriate. Specifically, the Director must consider whether alternative injection sites are available; 

community needs, demands, and supply from drinking water resources; planned needs, potential and/or 

future use of USDWs and non-USDWs in the area; and a plan for securing alternative resources or 

treating USDW formation waters in the event of contamination related to the Class VI injection activity. 

For additional information on the waiver approach, please see the final rule and preamble, as well as 

EPA's responses to comments on the Notice of Data Availability and Request for Comment. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: Rule Provision: 144.3 

Anadarko Petroleum Corporation (APC) Comments: ENHANCED OIL RECOVERY (EOR) OR 

ENHANCED GAS RECOVERY (EGR) MEANS ANY ACTIVITY THAT USES FLUIDS, GASES 

OR OTHER 

MEANS TO IMPROVE OR INCREASE EXTRACTION OF HYDROCARBONS. 

Rationale: The definition of EOR is necessary to support further comments and 

discussion below. 

Response: EPA includes the following definition of Enhanced Oil or Gas Recovery in the preamble to 

the rule: typically, the process of injecting a fluid (e.g., water, brine, or CO2) into an oil or gas bearing 

formation to recover residual oil or natural gas. The injected fluid thins (decreases the viscosity) and/or 

displaces small amounts of extractable oil and gas, which is then available for recovery. This is also 

known as secondary or tertiary recovery. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment); 4400 2.4.4.3 

Allowing injection above or between USDWs (seeking comment) 

Comment: Rule Provision: 144.6 and 146.5 

Anadarko Petroleum Corporation (APC) Comments: (b) Class II. Wells which inject 

fluids:.... 

(4) FOR ENHANCED RECOVERY OF OIL OR NATURAL GAS WHERE GEOLOGIC 

SEQUESTRATION IS 

OCCURRING DURING OR IN CONNECTION WITH ENHANCED RECOVERY OF OIL OR 

NATURAL GAS 

PROVIDED (I) THERE IS REASONABLE EXPECTATION OF MORE THAN INSIGNIFICANT 

FUTURE 

PRODUCTION VOLUMES OR RATES AS A RESULT OF CARBON DIOXIDE INJECTION AND 

(II) 

OPERATING PRESSURES ARE NO HIGHER THAN REASONABLY NECESSARY TO PRODUCE 

SUCH 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24624

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24625

141
VOLUMES OR RATES; AND 

(5) FOR GEOLOGIC SEQUESTRATION IN SUBSURFACE GEOLOGIC FORMATIONS IN 

WHICH 

EXTRACTION OF HYDROCARBONS HAS OCCURRED, IS OCCURRING OR IS REASONABLY 

EXPECTED 

TO OCCUR AND WHERE THE CRITERIA OF PARAGRAPH (B)(4) ARE NOT MET. 

(f) Class VI. Wells used EXCLUSIVELY for geologic sequestration of carbon 

dioxide STREAMS. beneath the lowermost formation containing a USDW WELLS 

WHERE GEOLOGIC SEQUESTRATION OF CO2 STREAMS OCCURS DURING OR IN 

CONNECTION WITH 

EOR OR EGR ARE REGULATED UNDER CLASS II. 

Rationale: The changes to (b) and (f) are to recognize that EOR can have storage 

component, which is consistent with EPA’s intent as expressed in the preamble 

and API’s October 27th meeting with EPA. It is widely recognized that CO2 based 

EOR can provide a significant early opportunity for carbon storage. As EPA 

correctly recognizes, CO2 EOR operations can have a significant storage 

component through capillary trapping or other mechanisms. 

Additionally, there should not be a blanket prohibition concerning injection 

above USDW’s or at specific depths. This is especially true given the 

possibility of changes in the definition of a USDW to include formations greater 

than 10,000 parts per million Total Dissolved Solids. This requirement is not 

necessary for the protection of USDWs and would remove a vast number of viable 

formations from consideration. Industry has shown that it can operate CO2 

injection wells in an EOR context without endangering USDWs that are located 

below the injection zone. An excellent example is the Salt Creek EOR project in 

Wyoming, which has a USDW below the injection zone. Moreover, under the proposed 

rule, there are other measures that would provide real assurance of formation 

integrity and require operators to demonstrate that their project will not 

endanger USDWs, making the lowermost USDW restriction unnecessary. 

Response: EPA did not make the suggested edits. EPA believes that the nature and risks of CO2 

injection for the primary purpose of long-term storage pose different risks than injection for the primary 

purpose of ER, and has developed new Class VI regulations to address these unique risks. For example, 

the volume of CO2 anticipated to be injected for long-term storage is significantly greater than for ER. 

Reservoir pressure conditions will also be different, with Class VI injection operations involving large 

volumes of CO2 and likely having higher pressures within their storage formations than Class II ER 

projects. EPA also recognizes that a by-product of ER activities is that a certain percentage of the CO2 

is trapped in the receiving formation. 

The final Class VI regulations require that any owner or operator injecting CO2 for the primary purpose 

of long term storage obtain a Class VI permit with some special consideration for the fact that they are 

transitioning from a well not originally designed to meet Class VI requirements. The Director has the 

authority to determine at what point a Class VI permit is required for those projects that are transitioning 

from the primary purpose of EOR to long term storage of CO2. The final regulation provides a set of 

technical factors for the Director to evaluate in making this determination, at §144.19. EPA believes that 

this approach provides sufficient protection of USDWs when there is an increased risk to USDWs as 

compared to traditional Class II operations while allowing for site-specific flexibility. 

142
Regarding injection into basalts, coal seams, and salt domes, EPA clarifies that the GS rule does not 

preclude injection of CO2 into any non-USDW formation types. The purpose of the GS rule is to ensure 

protection of USDWs from endangerment, and the rule requires that owners or operators demonstrate 

that wells are sited in suitable systems with geologic formations to receive and confine injected CO2, as 

required at §146.83 of the GS rule. The Class VI siting, well construction and operation, monitoring and 

testing, and post-injection site care and site closure requirements are designed to ensure that injected 

CO2 remains within the target formation. If an owner or operator can demonstrate to the Director's 

satisfaction that GS in coal seams, basalts, salt domes, or shales can be accomplished in a manner that 

protects USDWs and meets all of the requirements of the GS rule, the project may be permitted as a 

Class VI well. 

EPA acknowledges that there may be unknown risks associated with GS, particularly regarding GS into 

formations such as coal seams, basalts, and salt domes, which have been the subject of limited 

experimental projects in the past. EPA anticipates that in the short-term, GS into these types of 

formations will continue to be experimental (i.e., to test GS technologies and collect data), and will 

likely be permitted as Class V experimental technology wells subject to UIC Program Guidance #83. 

EPA is preparing an addendum to UICPG #83 that describes the use of the Class V experimental 

technology well classification to clarify permitting for Class V wells. This addendum will address 

shifting of Class V experimental projects to full-scale GS projects and the future use of the Class V 

experimental technology well subclass for research and testing of new GS technologies. 

EPA acknowledges that there are limited circumstances where injection above the lowermost USDW 

can be performed in a manner that protects USDWs. The final GS rule at §146.95 establishes a process 

by which owners or operators can seek a waiver of the Class VI injection depth requirements. The 

waiver approach requires the submission of extensive, site-specific information (in conjunction with the 

permit application submittal) to demonstrate that injection of CO2 into a formation that is above or 

between USDWs can be done in a manner that is protective of USDWs. The requirements are designed 

to ensure the owner or operator, the Director, and the Regional Administrator consider, on a site-specific 

basis, the implications, benefits, and challenges associated with GS and ensuring water availability and 

USDW protection. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment); 4324 2.4.4.1.2 

Comments opposed to requiring injection below the lowermost USDW 

Comment: Rule Provision: 144.80 

Anadarko Petroleum Corporation (APC) Comments: (b) Class II. Wells which inject 

fluids:........(2) for enhanced recovery of oil or natural gas; (3) FOR EOR OR 

EGR, AND WHERE GEOLOGIC SEQUESTRATION OF A CARBON DIOXIDE STREAM IS 

OCCURRING 

DURING OR IN CONNECTION WITH EOR OR EGR OPERATIONS OR ACTIVITIES; and (4) For 

storage of hydrocarbons.... 

(f) Class VI. Wells used EXCLUSIVELY for geologic sequestration of carbon 

dioxide STREAMS. WELLS WHERE GEOLOGIC SEQUESTRATION OF CO2 STREAMS 

OCCURS DURING 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24628

143
OR IN CONNECTION WITH EOR OR EGR ARE REGULATED UNDER CLASS II. 

Rationale: See 144.6 

Rule Provision: 146.5 

Anadarko Petroleum Corporation (APC) Comments: b) Class II. Wells which inject 

fluids:..... (4) FOR ENHANCED RECOVERY OF OIL OR NATURAL GAS WHERE GEOLOGIC 

SEQUESTRATION IS OCCURRING DURING OR IN CONNECTION WITH ENHANCED 

RECOVERY OF OIL 

OR NATURAL GAS PROVIDED (I) THERE IS REASONABLE EXPECTATION OF MORE THAN 

INSIGNIFICANT FUTURE PRODUCTION VOLUMES OR RATES AS A RESULT OF CARBON 

DIOXIDE 

INJECTION AND (II) OPERATING PRESSURES ARE NO HIGHER THAN REASONABLY 

NECESSARY 

TO PRODUCE SUCH VOLUMES OR RATES; AND 

(5) FOR GEOLOGIC SEQUESTRATION IN SUBSURFACE GEOLOGIC FORMATIONS IN 

WHICH 

EXTRACTION OF HYDROCARBONS HAS OCCURRED, IS OCCURRING OR IS REASONABLY 

EXPECTED 

TO OCCUR AND WHERE THE CRITERIA OF PARAGRAPH (B)(4) ARE NOT MET. 

(f) Class VI. Wells used EXCLUSIVELY for geologic sequestration of carbon 

dioxide STREAMS. Beneath the lowermost formation containing an underground 

source of drinking water (USDW). WELLS WHERE GEOLOGIC SEQUESTRATION OF CO2 

STREAMS OCCURS DURING OR IN CONNECTION WITH EOR OR EGR ARE REGULATED 

UNDER CLASS 

II. 

Rationale: See 144.6 

Response: As described above in the response to comment 24625 regarding the suggested edit at 144.6, 

EPA did not make the suggested change. The Agency disagrees that wells injecting CO2 for the primary 

purpose of long-term storage should be regulated under Class II requirements. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

As described above, the final GS rule at §146.95 establishes a process by which owners or operators can 

seek a waiver of the Class VI injection depth requirements for injection into non-USDW formations 

above and/or between USDWs. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: Rule Provision: 146.25 GEOLOGIC SEQUESTRATION IN OIL OR GAS RESERVOIRS 

WITHOUT 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24630

144
ENHANCED RECOVERY OF OIL OR NATURAL GAS 

Anadarko Petroleum Corporation (APC) Comments: WELLS USED FOR GEOLOGIC 

SEQUESTRATION AND MEETING THE CLASSIFICATION CRITERIA OF SECTION 146.5(B)(5) 

SHALL BE SUBJECT TO THE FOLLOWING REQUIREMENTS: 

(A) EXISTING WELLS THAT MEET OR EXCEED THE CONSTRUCTION REQUIREMENTS OF § 

146.22 

SHALL BE SUBJECT TO PART 146, SUBPART H EXCEPT SECTIONS 146.86 AND 146.87. 

(B) NEW WELLS MUST MET THE CONSTRUCTION REQUIREMENTS OF SECTION 146.22 

AND ARE 

SUBJECT TO PART 146, SUBPART H EXCEPT SECTIONS 146.86 AND 146.87 

Rationale: Details of what would be required of "Class IIB" wells are to be 

worked out during future discussions of the Multi-Stakeholder Discussion Group 

(MSDG). However, APC offers this language which is consistent with changes APC 

had suggested before discussions with the MSDG began (see Section 146.81(c)). 

Response: As described above in the response to comment 24625 regarding the suggested edit at 144.6, 

EPA did not make the suggested change. The Agency disagrees that wells injecting CO2 for the primary 

purpose of long-term storage should be regulated under Class II requirements because Class II 

requirements do not address the unique risks posed by GS while ensuring protection of USDWs from 

endangerment. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment, EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

Other EPA Comment Codes and Descriptions: 3200 2.2 Proposed Area of Review and Corrective 

Action Requirements (40 CFR 146.84) 

Comment: Rule Provision: 146.81(d) [Definition - Area of review] 

Anadarko Petroleum Corporation (APC) Comments: Area of review means the region 

surrounding the geologic sequestration project that may be impacted by the 

injection activity. The area of review is based on computational modeling that 

accounts for the physical and chemical properties of all phases of the injected 

carbon dioxide stream. SUBSURFACE THREE-DIMENSIONAL EXTENT OF THE CARBON 

DIOXIDE PLUME, ASSOCIATED PRESSURE FRONT, AS WELL AS THE OVERLYING 

FORMATIONS 

AND SURFACE AREA ABOVE THAT DELINEATED REGION. 

Rationale: Defining the AOR based on the extent of the CO2 plume and its 

associated pressure front is a more direct approach, rather than the approach 

offered by the EPA. The EPA definition suggests that the computational approach 

defines the AOR rather than the potential risks of the injection activity. 

Response: EPA disagrees that the AoR definition needs to specifically include the overlying formations 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24633

145
and surface area above the delineated region. The intent of the AoR, a long-standing concept within the 

UIC Program, is to delineate the surface area and all subsurface formations below it that may potentially 

be impacted by injection activity. Acceptable delineation models will provide predictions of CO2 fate 

and transport, as well as changes in formation pressure, in three dimensions as a function of time that 

can be used to delineate the subsurface storage site and the AoR. Although EPA disagrees with the 

commenter's suggested change, the Agency has carefully considered all comments on the AoR definition 

at 146.84(a) and modified it to read as follows: The region surrounding the geologic sequestration 

project where USDWs may be endangered by the injection activity. The area of review is delineated 

using computational modeling that accounts for the physical and chemical properties of all phases of the 

injected CO2 stream and is based on available site characterization, monitoring, and operational data. 

EPA believes that this definition is sufficiently broad and describes both the intent of the computational 

modeling and the relationship of the AoR to areas that are subject to the risks associated with injection. 

Other EPA Comment Codes and Descriptions: 1630 1.3.3 RCRA/hazardous waste issues (seeking 

comment) 

Comment: Rule Provision: 146.81(d) [Definition - Carbon dioxide stream] 

Anadarko Petroleum Corporation (APC) Comments: Carbon dioxide stream means 

carbon dioxide, WHICH WILL BE INJECTED IN ANY PHYSICAL STATE OR DISSOLVED, AND 

ANY ASSOCIATED substances derived from the that has been captured from an 

emission source (e.g., a power plant), plus incidental associated substances 

derived from the source materials and the capture process, and any, ITS 

PROCESSING, OR substances added to enable or improve the injection process. This 

subpart does not apply to any carbon dioxide stream that meets the definition of 

a hazardous waste under 40 CFR part 261. 

Rationale: Source of CO2 is not an issue in the context of defining the CO2 

stream. The rule applies to the injection of CO2 and should not address the 

origins of the materials since that is beyond the scope of this regulation. 

Original text would have precluded injection of CO2 from some sources. 

Response: The final GS rule retains the definition of a CO2 stream as proposed. The GS regulation 

applies to injection of CO2 for the purpose of GS, regardless of the source of the CO2. It is beyond the 

scope of the GS rule and the UIC Program’s authority to require or set standards for upstream generators 

of CO2 or purification facilities. For purposes of GS, the UIC program’s authority under the SDWA is 

limited to ensuring that GS projects are sited, constructed, operated, and closed in a manner that protects 

USDWs. 

Although the GS regulation does not apply to the source of CO2 streams, the GS rule, at §146.82(a)(7)

(iv), requires the owner or operator to submit data about the site, including an analysis of the chemical 

and physical characteristics of the CO2 stream because the concentrations of minor and trace elements 

in CO2 streams for GS projects are likely to vary by facility, coal composition, plant operating 

conditions, and pollution removal technologies. 

With respect to RCRA, EPA has decided to initiate a separate proposed rulemaking specifically to 

examine the issue of RCRA applicability to CO2 streams being geologically sequestered, including the 

possible option of a conditional exemption from the RCRA requirements for CO2 GS in Class VI wells. 

EPA will consider these comments as part of its development of that proposal. The Agency will consider 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24634

146
issues particular to RCRA in the context of that separate rulemaking, and recommends that the 

commenter read that proposed rule when it is published. The Agency notes that commenters who wish 

to submit comments on the RCRA proposal will need to do so during the comment period for that rule. 

Finally, EPA also notes that the final GS rule, which adds new regulations for Class VI wells under the 

Safe Drinking Water Act (SDWA), is not making any changes to the RCRA regulations. 

Other EPA Comment Codes and Descriptions: 4324 2.4.4.1.2 Comments opposed to requiring 

injection below the lowermost USDW; 4400 2.4.4.3 Allowing injection above or between USDWs 

(seeking comment) 

Comment: Rule Provision: 146.81(d) [Definition - Geologic sequestration] 

Anadarko Petroleum Corporation (APC) Comments: Geologic sequestration project 

means an injection well or wells used to emplace a carbon dioxide stream 

beneath the lowermost formation containing a USDW INTO AN INJECTION ZONE 

EXCLUSIVELY FOR THE PURPOSE OF GEOLOGIC SEQUESTRATION. It includes the 

subsurface three-dimensional extent of the carbon dioxide plume, associated 

pressure front, and displaced brine, as well as the surface area above that 

delineated region. 

Rationale: There should not be a blanket prohibition concerning injection above 

USDW’s or at specific depths. This requirement is not necessary for the 

protection of USDWs and would remove a vast number of viable formations from 

consideration. Industry has shown that it can operate CO2 injection wells in an 

EOR context without endangering USDWs that are located below the injection zone. 

An excellent example is the Salt Creek EOR project in Wyoming, which has a USDW 

below the injection zone. Moreover, under the proposed rule, there are other 

measures that would provide real assurance of formation integrity and require 

operators to demonstrate that their project will not endanger USDWs, making the 

lowermost USDW restriction unnecessary. 

Response: EPA has revised the definition of a geologic sequestration project to account for the new 

requirements to include “wells used for geologic sequestration of carbon dioxide that have been granted 

a waiver of the injection depth requirements pursuant to requirements at §146.95.” 

Comment: Rule Provision: 146.81(d) [Definition - Injection zone] 

Anadarko Petroleum Corporation (APC) Comments: Injection zone means a geologic 

formation, group of formations, or part of a formation that is of sufficient a 

real extent, thickness, porosity, and permeability to receive carbon dioxide 

RECEIVING FLUIDS through a well or wells associated with a geologic 

sequestration project 

Rationale: Existing definition in the CFR is sufficient and does not need to be 

changed. Furthermore, adding the sufficiency requirement is not a definitional 

issue and should be dealt with elsewhere. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24635

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24636

147
Response: EPA disagrees with the suggested edit. The final definition of injection zone at §146.81(d) is 

unchanged and reads as follows: “[A] geologic formation, group of formations, or part of a formation 

that is of sufficient areal extent, thickness, porosity, and permeability to receive carbon dioxide through 

a well or wells associated with a geologic sequestration project.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: Rule Provision: 146.81(d) [Definition - Post-injection site care] 

Anadarko Petroleum Corporation (APC) Comments: Post-injection site care means 

appropriate monitoring and other actions (including corrective action) 

needed following cessation of injection to assure that USDWs are not 

endangered , as required under §146.93. 

Rationale: Deleted "appropriate" because the definition of it is not clear. 

Deleted USDW phrase because it is incorporated in 146 requirements. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. EPA adds that all post-injection site care must 

be performed pursuant to the post-injection site care and site closure plan, which must be approved by 

the Director and demonstrated to include monitoring activities that protect USDWs from endangerment. 

Comment: Rule Provision: 146.81(d) [Definition - Pressure front] 

Anadarko Petroleum Corporation (APC) Comments: Pressure front means the zone of 

elevated pressure that is created by the injection of the carbon dioxide STREAM 

into the subsurface, For the purposes of this subpart, the pressure front of a 

carbon dioxide plume refers to a zone where there is a pressure differential 

sufficient to cause movement of injected fluids THE CARBON DIOXIDE STREAM or 

formation fluids FROM THE INJECTION ZONE into a USDW. 

Rationale: Clarification. 

Response: EPA disagrees with the suggested edit. The final definition of pressure front at §146.81(d) is 

unchanged and reads as follows: “[T]he zone of elevated pressure that is created by the injection of 

carbon dioxide into the subsurface. For the purposes of this subpart, the pressure front of a carbon 

dioxide plume refers to a zone where there is a pressure differential sufficient to cause the movement of 

injected fluids or formation fluids into a USDW.” 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24637

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24638

148
Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: Rule Provision: 146.81(d) [Definition - Site closure] 

Anadarko Petroleum Corporation (APC) Comments: Site closure MEANS the 

point/time, as determined by the Director following the requirements under 

§146.93, at which the owner or operator of a GS site PROJECT is released 

from post-injection site care responsibilities. 

Rationale: "GS project" is consistent with other definitions. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: Rule Provision: 146.81(d) [Definition - Transmissive fault or fracture] 

Anadarko Petroleum Corporation (APC) Comments: Transmissive fault or fracture 

means a fault or fracture that has sufficient permeability and vertical extent 

to allow fluids to move between formations BEYOND THE CONFINING ZONE. 

Rationale: The term "between formations" is inaccurate since there can be 

multiple formations within a injection zone. The critical factor for 

transmissivity is movement of injected or displaced fluids beyond the confining 

zone. 

Response: EPA has retained the proposed definition, which is the same as the existing definition at 

§148.2, to address transmissive faults and fractures that extend beyond the confining zone. 

Comment: Corrective action - As the GAO Report observes, public perception of carbon 

sequestration will likely play a determinative role in the success of any CO2 GS 

regulatory scheme. GAO Report at 49. The use of the phrase "corrective action" 

to describe plugging and repair of Class VI wells risks confusion and possibly 

negative associations with the concept of corrective action under RCRA and 

CERCLA. We encourage EPA to replace the phrase "corrective action" with more 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24639

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24640

Commenter Name: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22169

149
appropriate terminology in the Final Rule. 

Response: EPA notes that the term "corrective action" at §146.84(d) has been used to describe the 

process of addressing improperly plugged wells in the AoR of injection wells since the inception of the 

UIC program, e.g., at §§146.7 and 146.64. While EPA is aware that the term has a different meaning 

under the UIC regulations than it does under RCRA and CERCLA, this has not caused confusion in the 

past. An alternative term, "well plugging," suggested by another commenter is reserved for injection 

well plugging, as indicated at §146.92. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Comment: §146.81 Applicability. (b) 

"This subpart applies to wells used to inject carbon dioxide specifically for 

the purpose of geologic sequestration, i.e., the long-term containment of a 

gaseous, liquid or supercritical carbon dioxide stream in subsurface geologic 

formations." 

We recommend striking out "gaseous, liquid or supercritical carbon dioxide 

stream" and replacing with "gaseous, liquid, supercritical or co-mixed carbon 

dioxide stream" This change will allow for injection of carbon dioxide that is 

pre-dissolved with water to prevent phase separation in the injection zone or 

with inclusion of flow or pumping enhancement components. 

Response: EPA disagrees with the suggested edit. The Agency has modified §146.81(b) to read as 

follows: “This subpart applies to any wells used to inject carbon dioxide specifically for the purpose of 

geologic sequestration, i.e., the long-term containment of a gaseous, liquid, or supercritical carbon 

dioxide stream in subsurface geologic formations.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: 1. AOR Definition 

The proposed rule vaguely defines the AOR as "the region surrounding" the GS 

project that "may be impacted by the injection activity." 72 Fed. Reg. at 43535 

(proposed 40 C.F.R. 146.81(d)). The definition goes on to suggest that the AOR 

is to be "based on computation modeling that accounts for the physical and 

chemical properties of all phases of the injected carbon dioxide stream." Id. 

There are two issues. 

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22719

Commenter Name: John King Letter ID: 0211

Commenter Organization: Shell Exploration and Production Company (SEPCo) Comment ID: 22767

150
First, the proposed definition suggests the need for a more complex modeling 

approach than may typically be necessary or appropriate. As experience with 

hazardous waste injection shows, it is rarely necessary to attempt to model 

chemical changes in the injectate plume. Indeed, it is typically far easier to 

model transport than chemical fate, and conservative modeling of transport 

should typically be sufficient by itself to show that USDWs will not be 

endangered. Where this is the case, it is containment of the plume -- rather 

than the precise composition of the plume -- that matters, and modeling of 

chemical changes would be unnecessary. Similarly, the preamble suggests that the 

"most sophisticated" and most "accurate" modeling should be preferred or even 

required. 73 Fed. Reg. at 43507. Again, however, the appropriate goal is to 

ensure protection of USDWs, and simpler, more conservative modeling may often be 

sufficient (and even preferable) for this purpose. 

Second, the functional purpose of the AOR is to define the area within which 

impacts of the injection activity could cause endangerment of a USDW; 

specifically, the AOR defines the area within which corrective action for 

abandoned boreholes may be necessary to prevent endangerment of USDWs. The 

language of the proposed rule (i.e., "may be impacted by the injection 

activity") is not clearly limited to impacts of the injection activity that 

could cause endangerment of USDW’s, and it should be. 

Response: EPA believes that predicting the complex multiphase, buoyant flow of the CO2, coinjectates, and compounds that may be mobilized due to injection requires the sophistication of 

computational models, as required at 146.84(c)(1). Models can predict CO2 fate and transport, as well as 

changes in formation pressure, in three dimensions, as a function of time in order to delineate the 

subsurface storage site and the AoR. Models can account for site-specific and predicted operating 

conditions as well as geologic heterogeneities and potential migration through faults, fractures, and 

artificial penetrations. 

EPA acknowledges that fine precision may not always be necessary and that many factors determine 

ultimate confidence in modeling results. However, EPA does not believe that more precision would 

result in a less protective modeling approach. EPA anticipates that the owner or operator, in consultation 

with the Director, will choose the model that is most appropriate for a particular GS project, and that this 

dialogue is a key factor in assuring that the GS site is modeled (and eventually operated and tracked) in 

a manner that protects USDWs from endangerment. EPA encourages and expects owners or operators to 

use the best multiphase, computational models available. 

Other EPA Comment Codes and Descriptions: 1616 1.3.1.3 Fluid movement 

Comment: Point #4: The use of the term "CO2 buoyancy," enumerated countless times in the 

draft rules, is misleading. The Preamble to the Proposed Rule makes very clear 

that changes to the VIC program for CO2 geologic storage are based among other 

things on the assertion that CO2 is "buoyant". This is simply incorrect. CO2 is 

a non-explosive, non-flammable, non-toxic gas that possesses different physical 

properties than some other injectates or existing formation fluids. These 

physical properties do not include any special buoyancy characteristics or 

properties. Rather, CO2 is simply more dense than some underground fluids or 

gases and less dense than others. Hence the movement of injected CO2 in a 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23961

151
reservoir, or any type of system containing different fluids or gases, will vary 

based on the relative densities of the various formation fluids or gases that 

are in the reservoir. The various formation fluids will simply segregate based 

on the relative densities of the fluids or gases, including CO2. As a result, CO2 

may be the fluid that sinks to the bottom, rises to the top, or resides 

somewhere in between the top and the bottom within the reservoir system. 

Response: EPA disagrees with the commenter. Field and laboratory studies that evaluated two deep 

wells exposed to CO2 for nearly three decades have provided evidence of upward vertical flow of CO2. 

In Carey et al (2007), a sample of well cement collected from a section of well in the confining zone at 

SACROC showed evidence of cement alteration (carbonation) due to exposure from CO2. (The study 

was not able to determine whether the alteration was due to exposure to CO2 in the presence of water, 

dry CO2, or to a CO2-brine mixture.) In Crow et al (2009), a similar study was conducted on a CO2 

production well that was drilled into and completed in a natural CO2 producing formation. This study 

concluded that CO2 had caused alteration (carbonation) of the well cement and acidification of fluids 

adjacent to the caprock. The study could not determine if the alteration was due to exposure from CO2 

diffusion up into the overlying caprock or by upward CO2 migration within wellbore system defects 

(perhaps cement-caprock and/or cement-formation interfaces). In both studies, the CO2 apparently 

moved from the underlying reservoir into the well bore section located within the overlying caprock. 

These observations, especially in conjunction with the larger CO2 volumes and higher reservoir 

pressures anticipated with GS, justify the well construction requirements in the final GS rule in order to 

prevent deterioration of the materials between the well casing and the well bore that can result in 

unacceptable fluid movement. 

EPA adds that buoyancy of CO2 is among several unique considerations for large scale GS that warrant 

the tailored construction requirements at §146.86. For example, seismic surveys at Sleipner showed that 

CO2 had migrated to the top of the 200 to 300 meter thick formation as early as 3 years after injection 

began. The overall behavior of CO2 at Sleipner is for it to migrate to the top of the formation and spread 

laterally from there (Chadwick et al 2006). Additionally, CO2 has the potential to be corrosive (in the 

presence of water or aqueous formation fluids during CO2 injection), and the volume of CO2 anticipated 

to be injected in Class VI wells is significantly greater than for Class II ER/ CO2 injection wells. 

Other EPA Comment Codes and Descriptions: 4324 2.4.4.1.2 Comments opposed to requiring 

injection below the lowermost USDW 

Comment: The TxCCSA also comments on the definition of Geologic Sequestration Project 

referenced in this section. 

Geologic sequestration project means an injection well or wells used to 

emplace a carbon dioxide stream beneath the lowermost formation 

containing a USDW. It includes the subsurface three-dimensional extent 

of the carbon dioxide plume, associated pressure front, and displaced 

brine, as well as the surface area above that delineated region. 

This definition restricts geologic sequestration projects to the lowermost 

formation containing a USDW. Restricting injection formations to the lowermost 

USDW is not necessary for the protection of USDWs and would remove a vast number 

of viable formations from consideration. The drilling industry has shown that it 

can operate CO2 injection wells in an enhanced oil recovery (EOR) context 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23968

152
without endangering USDWs that are located below the injection zone. There 

should be no blanket prohibition against injection into any approved geologic 

zone even if above the lowermost USDW. The decision should be site-specific and 

based on evaluation of local geology. We fully support the change proposed by 

the Texas Railroad Commission in its comments. 

Geologic sequestration project means an injection well or wells used to 

emplace a carbon dioxide stream beneath the lowermost formation 

containing a USDW, OR ANOTHER FORMATION, IF THE DIRECTOR DETERMINES THAT 

INJECTION INTO THE OTHER FORMATION WILL NOT ENDANGER USDWS. It includes 

the subsurface three- dimensional extent of the carbon dioxide plume, 

associated pressure front, and displaced brine, as well as the surface 

area above that delineated region. 

Response: EPA acknowledges that there are limited circumstances where injection above the lowermost 

USDW can be performed in a manner that protects USDWs from endangerment, as long as appropriate 

protections are in place. The final GS rule at §146.95 establishes a process by which owners or operators 

can seek a waiver of the Class VI injection depth requirements for injection into non-USDW formations 

above and/or between USDWs. It establishes: 1) requirements specifying information that owners or 

operators must submit, and Directors must consider, in consultation with PWSS Directors; 2) procedures 

for public notice of a waiver application and for Director-Regional Administrator communication; 3) the 

waiver issuance process; and, 4) additional requirements that apply to owners or operators of Class VI 

wells granted a waiver of the injection depth requirements to ensure USDW protection above and below 

the injection zone. 

EPA also revised the definition of a geologic sequestration project to account for the new requirements 

to include “wells used for geologic sequestration of carbon dioxide that have been granted a waiver of 

the injection depth requirements pursuant to requirements at §146.95.” 

EPA believes that these requirements will ensure USDW protection while providing flexibility to UIC 

program Directors and owners or operators who undertake CO2 injection for GS. The Agency believes 

this approach: 1) responds to concerns about local and regional geologic storage capacity limitations 

imposed by the proposed injection depth requirements; 2) allows for a more site-specific assessment of 

injection depth for GS projects; 3) accommodates injection into different formation types; 4) allows for 

injection of CO2 for GS into non-USDWs above and/or between USDWs when appropriate and where it 

can be demonstrated that USDWs will be protected; and 5) responds to concerns about the use of aquifer 

exemptions for GS. Finally, EPA’s approach to addressing injection depth variability through a waiver 

process responds to concerns about future drinking water resource availability and the need to ensure 

that high quality water remains available in sufficient quantities to supply drinking water needs. For 

additional information on the waiver approach, please see the final rule and preamble, as well as EPA's 

responses to comments on the Notice of Data Availability and Request for Comment. 

Comment: (iv) Definition of Carbon Dioxide Stream 

Section 146.81 of the Proposed Rule defines "carbon dioxide stream" as follows: 

Carbon dioxide stream means carbon dioxide that has been captured from an 

emission source (e.g., a power plant), plus incidental associated substances 

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21686

153
derived from the source materials and the capture process, and any substances 

added to the stream to enable or improve the injection process. This subpart 

does not apply to any carbon dioxide stream that meets the definition of a 

hazardous waste under 40 CFR part 261. 

By limiting the definition to "emission sources," the Class VI regulations may 

have the unintended effect of narrowing the types of sources that might inject 

CO2 for geologic sequestration. The particular source of the CO2 is not material 

in terms of protecting USDWs. Furthermore, the Final Rule should not address 

the source because it is beyond the scope of this regulation. We recommend 

deleting the phrase “has been captured from an emission source (e.g., a power 

plant)” from the definition contained in section 146.81 of the Proposed Rule so 

that the Final Rule does not inadvertently preclude other non-emission sources 

of CO2. 

Response: EPA disagrees with the suggested edit. The final definition of carbon dioxide stream at 

§146.81(d) remains unchanged and reads as follows: “[C]arbon dioxide that has been captured from an 

emission source (e.g., a power plant), plus incidental associated substances derived from the source 

materials and the capture process, and any substances added to the stream to enable or improve the 

injection process. This subpart does not apply to any carbon dioxide stream that meets the definition of a 

hazardous waste under 40 CFR part 261.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Comment: (iv) Definition of Carbon Dioxide Stream 

Section 146.81 of the Proposed Rule defines "carbon dioxide stream" as follows: 

Carbon dioxide stream means carbon dioxide that has been captured from an 

emission source (e.g., a power plant), plus incidental associated substances 

derived from the source materials and the capture process, and any substances 

added to the stream to enable or improve the injection process. This subpart 

does not apply to any carbon dioxide stream that meets the definition of a 

hazardous waste under 40 CFR part 261. 

By limiting the definition to "emission sources," the Class VI regulations may 

have the unintended effect of narrowing the types of sources that might inject 

CO2 for geologic sequestration. The particular source of the CO2 is not material 

in terms of protecting USDWs. Furthermore, the Final Rule should not address the 

source because it is beyond the scope of this regulation. We recommend deleting 

the phrase "has been captured from an emission source (e.g., a power plant)" 

from the definition contained in section 146.81 of the Proposed Rule so that the 

Final Rule does not inadvertently preclude other non-emission sources of CO2. 

Response: EPA disagrees with the suggested edit. The final definition of carbon dioxide stream at 

§146.81(d) remains unchanged and reads as: “[C]arbon dioxide that has been captured from an emission 

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21737

154
source (e.g., a power plant), plus incidental associated substances derived from the source materials and 

the capture process, and any substances added to the stream to enable or improve the injection process. 

This subpart does not apply to any carbon dioxide stream that meets the definition of a hazardous waste 

under 40 CFR part 261.” 

EPA clarifies that the Class VI GS requirements apply to owners or operators of injection wells that will 

be used to inject CO2 into the subsurface for the purposes of GS. The capture of CO2 is outside the 

scope of the final rule. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: 1. Schlumberger asks that the EPA expand the applicability of Class VI wells to 

cover wells injecting CO2 that is dissolved in water or brine. The current 

draft language for Section 146.81(b) states: 

This subpart applies to wells used to inject carbon dioxide specifically 

for the purpose of geologic sequestration, i.e., the long-term 

containment of a gaseous, liquid or supercritical carbon dioxide stream 

in subsurface geologic formations. 

We suggest that the EPA replace the current language with the following 

language: 

This subpart applies to wells used to inject carbon dioxide specifically 

for the purpose of geologic sequestration, i.e., the long-term 

containment of a gaseous, liquid or supercritical carbon dioxide stream 

or carbon dioxide dissolved in water or brine into subsurface geologic 

formations. 

While we recognize today the injection of dissolved CO2 raises economic 

challenges we feel that there may be cases where the injection of dissolved CO2 

will make sense both in terms of economics and in terms of leakage risk. 

Unlike separate phase CO2, CO2 dissolved in water is not less dense than the 

formation fluid and will not be subject to buoyancy driven leakage. 

Response: EPA disagrees with the suggested change. §146.81(b) reads as follows: “This subpart applies 

to any wells used to inject carbon dioxide specifically for the purpose of geologic sequestration, i.e., the 

long-term containment of a gaseous, liquid, or supercritical carbon dioxide stream in subsurface 

geologic formations.” Nothing in the rule precludes the injection of dissolved CO2, as long as the CO2 

does not meet the definition of a hazardous waste under 40 CFR part 261. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 23996

155
Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: Proposed Rule: Carbon dioxide stream means carbon dioxide that has been captured 

from an emission source (e.g., a power plant), plus incidental associated 

substances derived from the source materials and the capture process, and any 

substances added to the stream to enable or improve the injection process. This 

subpart does not apply to any carbon dioxide stream that meets the definition of 

a hazardous waste under 40 CFR part 261. 

Schlumberger Suggested Revision:: Carbon dioxide stream carbon dioxide that has 

been captured from an industrial process that is injected in any physical state 

or dissolved in water or brine. It includes incidental associated substances 

derived from the source materials and the capture process, and any substances 

added to the stream to enable or improve the injection process. This subpart 

does not apply to any carbon dioxide stream that meets the definition of a 

hazardous waste under 40 CFR part 261. 

Schlumberger Rationale: We want to ensure that dissolved CO2 is specifically 

allowed as it may allow a solution to the upward buoyancy drive associated with 

separate phase CO2. 

Response: EPA disagrees with the suggested edit. The final definition of carbon dioxide stream at 

§146.81(d) remains unchanged and reads as: “carbon dioxide that has been captured from an emission 

source (e.g., a power plant), plus incidental associated substances derived from the source materials and 

the capture process, and any substances added to the stream to enable or improve the injection process. 

This subpart does not apply to any carbon dioxide stream that meets the definition of a hazardous waste 

under 40 CFR part 261.” As described above, nothing in the rule precludes the injection of dissolved 

CO2, as long as the CO2 does not meet the definition of a hazardous waste under 40 CFR part 261. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment EPA has made many revisions to the GS rule. Please see the final rule and 

preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: Proposed Rule:Geologic sequestration means the long-term containment of a 

gaseous, liquid or supercritical carbon dioxide stream in subsurface geologic 

formations. This term does not apply to its capture or transport. 

Schlumberger Suggested Revision: Geologic sequestration means the long-term 

containment of a carbon dioxide stream in subsurface geologic formations. This 

term does not apply to its capture or transport. 

Schlumberger Rationale: CO2 stream was already defined and should e used here. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24010

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24011

156
Response: EPA disagrees with the suggested change. The final definition of geologic sequestration at 

§146.81(d) reads as follows: “[T]he long-term containment of a gaseous, liquid, or supercritical carbon 

dioxide stream in subsurface geologic formations. This term does not apply to carbon dioxide capture or 

transport.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: Proposed Rule: Geologic sequestration project means an injection well or wells 

used to emplace a carbon dioxide stream beneath the lowermost formation 

containing a USDW. It includes the subsurface three-dimensional extent of the 

carbon dioxide plume, associated pressure front, and displaced brine, as well as 

the surface area above that delineated region. 

Schlumberger Suggested Revision: Geologic sequestration project means an 

injection well or wells used to emplace a carbon dioxide stream into an 

injection zone. It includes the subsurface three-dimensional extent of the 

carbon dioxide plume, associated pressure front, and displaced brine, as well as 

the surface area above that delineated region. 

Schlumberger Rationale: - 

Response: The Agency has modified the definition of geologic sequestration project at §146.81(d) to 

read as follows: “Geologic sequestration project means an injection well or wells used to emplace a 

carbon dioxide stream beneath the lowermost formation containing a USDW; or, wells used for geologic 

sequestration of carbon dioxide that have been granted a waiver of the injection depth requirements 

pursuant to requirements at §146.95; or, wells used for geologic sequestration of carbon dioxide that 

have received an aquifer exemption expansion. It includes the subsurface three-dimensional extent of the 

carbon dioxide plume, associated pressure front, and displaced brine, as well as the surface area above 

that delineated region.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: Proposed Rule: Injection zone means a geologic formation, group of formations, 

or part of a formation that is of sufficient areal extent, thickness, porosity, 

and permeability to receive carbon dioxide through a well or wells associated 

with a geologic sequestration project. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24012

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24013

157
Schlumberger Suggested Revision: Injection zone means a geologic formation, 

group of formations, or part of a formation that is of sufficient areal extent, 

thickness, porosity, and permeability to receive carbon dioxide through a well 

or wells associated with a geologic sequestration project. 

Schlumberger Rationale: - 

Response: EPA disagrees with the suggested edit. The definition of injection zone at §146.81(d) 

remains unchanged and reads as follows: “[A] geologic formation, group of formations, or part of a 

formation that is of sufficient areal extent, thickness, porosity, and permeability to receive carbon 

dioxide through a well or wells associated with a geologic sequestration project.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: Proposed Rule: Pressure front means the zone of elevated pressure that is 

created by the injection of carbon dioxide into the subsurface. For the purposes 

of this subpart, the pressure front of a carbon dioxide plume refers to a zone 

where there is a pressure differential sufficient to cause the movement of 

injected fluids or formation fluids into a USDW. 

Schlumberger Suggested Revision: Pressure front means the zone of elevated 

pressure that is created by the injection of the carbon dioxide stream into the 

subsurface, where there is a pressure differential sufficient to cause movement 

of the carbon dioxide stream or formation fluids into a USDW. 

Response: EPA disagrees with the suggested edit. The final definition of pressure front at §146.81(d) is 

unchanged and reads as follows: “[T]he zone of elevated pressure that is created by the injection of 

carbon dioxide into the subsurface. For the purposes of this subpart, the pressure front of a carbon 

dioxide plume refers to a zone where there is a pressure differential sufficient to cause the movement of 

injected fluids or formation fluids into a USDW.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: Proposed Rule: Site closure the point/time, as determined by the Director 

following the requirements under §146.93, at which the owner or operator of a GS 

site is released from post-injection site care responsibilities. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24014

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24015

158
Schlumberger Suggested Revision: Site closure means the point/time, as 

determined by the Director following the requirements under §146.93, at which 

the owner or operator of a GS project is released from post-injection site care 

responsibilities. 

Schlumberger Rationale: Suggest using "GS project" to be consistent with other 

definitions 

Response: EPA disagrees with the suggested edit. The final definition of site closure at §146.81(d) is 

unchanged and reads as follows: “The point/time, as determined by the Director following the 

requirements under §146.93, at which the owner or operator of a GS site is released from post-injection 

site care responsibilities.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: Proposed Rule: Transmissive fault or fracture means a fault or fracture that has 

sufficient permeability and vertical extent to allow fluids to move between 

formations. 

Schlumberger Suggested Revision: Transmissive fault or fracture means a fault or 

fracture that has sufficient permeability and vertical extent to allow fluids to 

move beyond the confining zone. 

Schlumberger Rationale: The term between formations is insufficient as it could 

also include multiple zones within a injection zone or between two zones above 

the confining unit. 

Response: EPA disagrees with the suggested edit. The final definition of transmissive fault or fracture at 

§146.81(d) is unchanged and reads as follows: “[A] fault or fracture that has sufficient permeability and 

vertical extent to allow fluids to move between formations.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 4324 2.4.4.1.2 Comments opposed to requiring 

injection below the lowermost USDW 

Comment: 146.81(d) Geologic sequestration project should be redefined as follows: 

Geologic sequestration project means an injection well or wells used to emplace 

a carbon dioxide stream into an injection zone for geologic sequestration. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24016

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23278

159
Geologic sequestration projects should not be limited to beneath the lowermost 

formation containing a USDW. 

Response: EPA has not revised the definition of a geologic sequestration project for the final rule. 

However, as described above, EPA acknowledges that there are limited circumstances where injection 

above the lowermost USDW can be performed in a manner that protects USDWs from endangerment, as 

long as appropriate protections are in place. The final GS rule at §146.95 establishes a process by which 

owners or operators can seek a waiver of the Class VI injection depth requirements for injection into 

non-USDW formations above and/or between USDWs. 

Other EPA Comment Codes and Descriptions: 3110 2.1.1 Proposed siting requirements (i.e., 

injection/confining zones, trapping mechanism) 

Comment: 146.82(a) Overlying formations needs to be defined. Geologic information should 

be limited to the injection and confining zones. 

Response: EPA believes that a detailed geological site characterization (required under §146.82) is 

essential to evaluating the presence and adequacy of the various geologic features necessary to receive 

and confine injected CO2 for GS. The requirements for geologic site characterization are based on a 

long standing UIC regulatory framework developed to address specific risks to USDWs posed by 

injection. The Class VI GS requirements are tailored so that they are appropriate for the unique nature of 

injecting large volumes of CO2 into a variety of geological formations for long-term storage. 

EPA is developing guidance on site characterization for GS projects to assist owners or operators and 

Directors in evaluating permit requirements and applications under §146.82. The guidance provides 

recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site 

as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the 

injection and confining zone. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: The definition of "carbon dioxide stream" should not be restricted to CO2 

captured from industrial sources 

The definition of "carbon dioxide stream" in §146.81(b) includes only carbon 

dioxide "that has been captured from an emission source (e.g., a power plant)." 

Over time, the vast majority of sequestered CO2 is likely to be captured from 

such sources, but rules are also needed to govern the sequestration of naturally 

occurring CO2 produced from geologic formations. We suggest that the definition 

be revised to read as follows: 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf, starting on p. 

10, to see the original formatting.] 

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23279

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22293

160
"Carbon dioxide stream means that has been captured from an emission source 

(e.g., a power plant), carbon dioxide plus incidental associated substances 

derived from the source materials OF THE CO2 AND/OR the capture process, and 

any substances added to the stream to enable or improve the injection process. 

This subpart does not apply to any carbon dioxide stream that meets the 

definition of a hazardous waste under 40 CFR part 261." 

Response: EPA disagrees with the suggested edit. The final definition of carbon dioxide stream at 

§146.81(d) remains unchanged and reads as follows: “[C]arbon dioxide that has been captured from an 

emission source (e.g., a power plant), plus incidental associated substances derived from the source 

materials and the capture process, and any substances added to the stream to enable or improve the 

injection process. This subpart does not apply to any carbon dioxide stream that meets the definition of a 

hazardous waste under 40 CFR part 261.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: The definition of "confining zone" should not be limited to formations overlying 

the injection zone, and should focus on limiting movement through the confining 

zone rather than out the injection zone 

The proposed definition of confining zone in §146.81(d) requires that the 

formation act as "a barrier" to fluid movement, which may be unnecessarily 

strict. The definition also fails to recognize that it is movement through and 

beyond the confining zone that needs to be limited. We suggest instead that the 

definition of "confining zone" read as follows: 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Confining zone means a geologic formation, group of formations, or part of a 

formation stratigraphically overlying the injection zone that acts as a 

barrier to limit fluid movement beyond THIS FORMATION, GROUP OF FORMATIONS, OR 

PART OF A FORMATION." 

Response: EPA disagrees with the suggested edit. However, the Agency has modified the final 

definition of confining zone at §146.81(d) to read as follows: “[A] geologic formation, group of 

formations, or part of a formation stratigraphically overlying the injection zone that acts as barrier to 

fluid movement. For Class VI wells operating under an injection depth waiver, confining zone means a 

geologic formation, group of formations, or part of a formation stratigraphically overlying and 

underlying the injection zone.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22300

161
and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment: The second sentence of the definition of ‘geologic sequestration project" should 

be amended to refer more generally to formation fluids and be transferred to the 

definition of "area of review" 

We suggest the following amendment to §146.81(d) in order to be more inclusive 

on the types of fluid that could be displaced: 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"[...] It includes the subsurface three-dimensional extent of the carbon dioxide 

plume, associated pressure front, and displaced brine FORMATION FLUIDS, as 

well as the surface area above that delineated region. 

We also suggest that this second sentence of the definition of geologic 

sequestration project be transferred to the definition of area of review as 

recommended above. The language provided above reflects the change from "brine" 

to "formation fluids." 

Moreover, we suggest that the present restriction of Class VI to formations 

below the lowermost USDW is more appropriately addressed elsewhere. Accordingly, 

we recommend that geologic sequestration project be defined as follows: 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Geologic sequestration project means an injection well or wells used to emplace 

a carbon dioxide stream beneath the lowermost formation containing a USDW INTO 

AN INJECTION ZONE FOR GEOLOGIC SEQUESTRATION. It includes the subsurface threedimensional extent of the carbon dioxide plume, associated pressure front, and 

displaced brine, as well as the surface area above that delineated region." 

The term "pressure front" should be replaced with the more accurate term "area 

of elevated pressure" throughout the rule 

The term "pressure front" in 146.81(d) is likely to be scientifically inaccurate 

as it implies a front, or discontinuity in pressure, whereas in reality there 

will be a continuous pressure gradient in the formation in most cases. We 

suggest globally replacing "pressure front" with "area of elevated pressure" 

throughout the rule. 

Response: EPA disagrees with the suggested edit. However, the Agency has modified the definition of 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22301

162
geologic sequestration project at §146.81(d) to read as follows: “Geologic sequestration project means 

an injection well or wells used to emplace a carbon dioxide stream beneath the lowermost formation 

containing a USDW; or, wells used for geologic sequestration of carbon dioxide that have been granted 

a waiver of the injection depth requirements pursuant to requirements at §146.95; or, wells used for 

geologic sequestration of carbon dioxide that have received an aquifer exemption expansion. It includes 

the subsurface three-dimensional extent of the carbon dioxide plume, associated pressure front, and 

displaced brine, as well as the surface area above that delineated region.” 

The final definition of pressure front at §146.81(d) also is unchanged and reads as follows: “[T]he zone 

of elevated pressure that is created by the injection of carbon dioxide into the subsurface. For the 

purposes of this subpart, the pressure front of a carbon dioxide plume refers to a zone where there is a 

pressure differential sufficient to cause the movement of injected fluids or formation fluids into a 

USDW.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: The area of review provisions should be revised in several respects 

Surprisingly, the definition of "area of review" (AOR) in §146.81(d) fails to 

mention that elevated pressure a critical aspect of what it means for an area to 

be "impacted" by injection activity. Our Environmental NGO Group recommends 

borrowing language from the proposed definition of "geologic sequestration 

project" and reworking the "area of review" definition. 

Response: Although EPA disagrees with the commenter's suggested change, the Agency has carefully 

considered all comments on the AoR definition at 146.84(a) and modified it to read as follows: The 

region surrounding the geologic sequestration project where USDWs may be endangered by the 

injection activity. The area of review is delineated using computational modeling that accounts for the 

physical and chemical properties of all phases of the injected CO2 stream and is based on available site 

characterization, monitoring, and operational data. EPA believes that this definition is sufficiently broad 

and describes both the intent of the computational modeling and the relationship of the AoR to areas that 

are subject to the risks associated with injection. 

Other EPA Comment Codes and Descriptions: 3200 2.2 Proposed Area of Review and Corrective 

Action Requirements (40 CFR 146.84) 

Comment: Rule Provision: 146.81(d) Definitions 

EPA Proposal: (d) Definitions. The following definitions apply to this 

subpart. To the extent that these definitions conflict with those in § 146.3 

these definitions govern: 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22306

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24854

163
Area of review means the region surrounding the geologic sequestration project 

that may be impacted by the injection activity. The area of review is based on 

computational modeling that accounts for the physical and chemical properties of 

all phases of the injected carbon dioxide stream. 

GWPC Recommendations: Area of review means the subsurface three-dimensional 

extent of the carbon dioxide stream plume associated pressure front, and 

displaced brine, as well as the overlying formations and surface area above that 

delineated region. 

Rationale: Suggest removal of the second sentence and replacement with : "It 

includes the subsurface three-dimensional extent of the carbon dioxide plume, 

associated pressure front, and displaced brine, as well as the surface area 

above that delineated region." 

Comment on the inclusion of the word "surrounding" because the AoR should be coextensive with the area defined by the Carbon Sequestration Project. Inclusion 

of "surrounding" makes this definition open-ended and ambiguous. 

Response: Based on review of all public comments on the AoR definition at 146.84(a), the Agency has 

modified it to read as follows: The region surrounding the geologic sequestration project where USDWs 

may be endangered by the injection activity. The area of review is delineated using computational 

modeling that accounts for the physical and chemical properties of all phases of the injected CO2 stream 

and is based on available site characterization, monitoring, and operational data. The definition in the 

proposed rule accounted for the varying physical and chemical properties of the CO2 including freephase and water-dissolved CO2, as the commenter suggests. The definition in the final rule will continue 

to do so. 

EPA is developing guidance on AoR and corrective action at GS Class VI sites to assist owners or 

operators and Directors in evaluating requirements and proposed AoR and corrective action plans under 

146.84. The guidance describes EPA's recommended approaches for the data to be considered in an 

initial AoR delineation, how to apply computational modeling to delineate the AoR, performing 

corrective action at GS sites, and, when appropriate, completing AoR reevaluations. The guidance will 

be available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 1630 1.3.3 RCRA/hazardous waste issues (seeking 

comment) 

Comment: EPA Proposal: Carbon dioxide plume means the underground extent, in three 

dimensions, of an injected carbon dioxide stream. 

Carbon dioxide stream means carbon dioxide that has been captured from an 

emission source (e.g., a power plant), plus incidental associated substances 

derived from the source materials and the capture process, and any substances 

added to the stream to enable or improve the injection process. This subpart 

does not apply to any carbon dioxide stream that meets the definition of a 

hazardous waste under 40 CFR part 261. 

GWPC Recommendations: Carbon dioxide stream means carbon dioxide, plus 

associated substances derived from the source materials and any processing, and 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24855

164
any substances added to the stream to enable or improve the injection process. 

This subpart does not apply to any carbon dioxide stream that meets the 

definition of a hazardous waste under 40 CFR part 261. 

Source of CO2 should not be an issue in the context of defining the CO2 stream. 

Response: The final GS rule retains the definition of a CO2 stream as proposed. The GS regulation 

applies to injection of CO2 for the purpose of GS, regardless of the source of the CO2. It is beyond the 

scope of the GS rule and the UIC Program’s authority to require or set standards for upstream generators 

of CO2 or purification facilities. For purposes of GS, the UIC program’s authority under the SDWA is 

limited to ensuring that GS projects are sited, constructed, operated, and closed in a manner that protects 

USDWs. The GS rule does not apply to generators of CO2. Additionally, EPA has received numerous 

comments regarding the applicability of the RCRA regulations and statute to CO2 streams that are 

geologically sequestered under the final Class VI UIC well requirements. As a result, EPA has decided 

to initiate a separate proposed rulemaking specifically to examine the issue of RCRA applicability to 

CO2 streams being geologically sequestered, including the possible option of a conditional exemption 

from the RCRA requirements for CO2 GS in Class VI wells. EPA will consider these comments as part 

of its development of that proposal. The Agency will consider issues particular to RCRA in the context 

of that separate rulemaking, and recommends that the commenter read that proposed rule when it is 

published. The Agency notes that commenters who wish to submit comments on the RCRA proposal 

will need to do so during the comment period for that rule. Finally, EPA also notes that the final GS 

rule, which adds new regulations for Class VI wells under the Safe Drinking Water Act (SDWA), is not 

making any changes to the RCRA regulations. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rationale: Insert the definition "Computational modeling means a mathematical 

model that is appropriate to the site geometry and takes into account the 

differences between the formation and injection fluids." 

Response: The final rule does not define computational modeling. The preamble to the proposed GS 

regulation and the modeling background document "Computational Modeling of Underground Injection 

of Carbon Dioxide for Determination of Area-of-Review and Potential Risk to Underground Sources of 

Drinking Water" (cited in the proposed rule preamble as USEPA, 2008d include FR citation) discuss, in 

detail, what EPA believes constitutes a computational model. Appropriate models may incorporate 

numerical, analytical, or semi-analytical approaches. These models solve a series of governing equations 

to predict the composition and volumetric fraction of each phase state, as well as fluid pressures, as a 

function of location and time for a particular set of conditions. EPA is developing guidance on AoR and 

corrective action at GS Class VI sites to assist owners or operators and Directors in evaluating 

requirements and proposed AoR and corrective action plans under 146.84. The guidance describes the 

data that EPA recommends to be considered in an initial AoR delineation, how to apply computational 

modeling to delineate the AoR, performing corrective action at GS sites, and, when appropriate, 

completing AoR reevaluations. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24856

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24857

165
Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: EPA Proposal: Confining zone means a geologic formation, group of formations, or 

part of a formation stratigraphically overlying the injection zone that acts as 

a barrier to fluid movement. 

GWPC Recommendations: Confining zone means a geological formation, group of 

formations, or part of a formation that is capable of limiting fluid movement 

from an injection zone. 

Rationale: The current UIC program definition of confining zone is preferable to 

the proposed definition. There are no special circumstances for CO2 streams 

that warrant a change 

Response: EPA acknowledges the comment and the final rule retains this text as proposed. EPA 

believes that the definitions used for injection zone and confining zone for Class VI GS are 

appropriately tailored to address the unique risks and challenges posed by GS of CO2 streams. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: EPA Proposal: Corrective action means the use of Director approved methods to 

assure that wells within the area of review do not serve as conduits for the 

movement of fluids into underground sources of drinking water (USDW). 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final GS rule retains the definition. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: GWPC Recommendations: "Fault means a surface or zone of rock fracture along which 

there has [or has not] been displacement." 

Rationale: Add definition of fault to clarify use in other provisions. This is 

the current definition with the insertion of the words "or has not" before 

displacement to recognize that faults can exist where there has been no 

displacement. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Response to Comments EPA has made many revisions to the GS Rule. See the final rule and the 

discussion of site characterization in the preamble for further discussion on EPA's final approach. EPA 

does not define "fault" but defines "transmissive fault or fracture." EPA has retained the proposed 

definition, which is the same as the existing definition at §148.2, to address transmissive faults and 

fractures that extend beyond the confining zone. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24858

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24859

166
Comment: EPA Proposal: Geologic sequestration means the long-term containment of a 

gaseous, liquid or supercritical carbon dioxide stream in subsurface geologic 

formations. This term does not apply to its capture or transport. 

GWPC Recommendations: Geologic sequestration means the long-term containment of 

a carbon dioxide stream in subsurface geologic formations. This term does not 

apply to its capture or transport. 

Rationale: Suggest removing "gaseous, liquid or supercritical" as these terms 

are implied by the use of the term carbon dioxide. 

Response: EPA disagrees with the suggested edit. However, the Agency has modified the definition of 

geologic sequestration at §146.81(d) to read as follows: “[T]he long-term containment of a gaseous, 

liquid, or supercritical carbon dioxide stream in subsurface geologic formations. This term does not 

apply to carbon dioxide capture or transport.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 4324 2.4.4.1.2 Comments opposed to requiring 

injection below the lowermost USDW 

Comment: EPA Proposal: Geologic sequestration project means an injection well or wells 

used to emplace a carbon dioxide stream beneath the lowermost formation 

containing a USDW. It includes the subsurface three-dimensional extent of the 

carbon dioxide plume, associated pressure front, and displaced brine, as well as 

the surface area above that delineated region. 

GWPC Recommendations: Geologic sequestration project means an injection well or 

wells used to emplace a carbon dioxide stream into an injection zone for 

geologic sequestration. 

Rationale: Replace "beneath the lowermost formation containing a USDW "with 

"into an injection zone" 

Suggest moving the second sentence to the definition of AOR. 

Response: In the final rule, EPA revised the definition of a geologic sequestration project to account for 

the new requirements to include “wells used for geologic sequestration of carbon dioxide that have been 

granted a waiver of the injection depth requirements pursuant to requirements at §146.95.” 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24860

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24861

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24862

167
Comment: GWPC Recommendation: Geologic sequestration site means 

Rationale: The GWPC believes a definition for this term is needed as the term is 

referenced in later sections of the rule. 

Response: EPA disagrees that a definition of geologic sequestration site is needed. EPA notes that a 

geologic sequestration site, under §146.83(a), comprises: “(1) An injection zone of sufficient areal 

extent, thickness, porosity, and permeability to receive the total anticipated volume of the carbon 

dioxide stream; [and] (2) Confining zones free of transmissive faults or fractures and of sufficient areal 

extent and integrity to contain the injected carbon dioxide stream and displaced formation fluids and 

allow injection at proposed maximum pressures and volumes without initiating or propagating fractures 

in the confining zone(s).” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Comment: EPA Proposal: Injection zone means a geologic formation, group of formations, or 

part of a formation that is of sufficient a real extent, thickness, porosity, 

and permeability to receive carbon dioxide through a well or wells associated 

with a geologic sequestration project. 

GWPC Recommendations: Injection zone means a geological "formation", group of 

formations, or part of a formation receiving fluids through a well. 

Rationale: Existing definition in the CFR is sufficient and does not need to be 

changed. Furthermore, adding sufficiency is not a definitional issue and should 

be dealt with elsewhere. 

Response: EPA disagrees with the suggested edit. The final definition of injection zone at §146.81(d) 

remains unchanged and reads as follows: “[A] geologic formation, group of formations, or part of a 

formation that is of sufficient areal extent, thickness, porosity, and permeability to receive carbon 

dioxide through a well or wells associated with a geologic sequestration project.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA, and 

Request for Comment EPA has made many revisions to the GS rule. Please see the final rule and 

preamble for additional information. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: EPA Proposal: Post-injection site care means appropriate monitoring and other 

actions (including corrective action) needed following cessation of injection to 

assure that USDWs are not endangered as required under § 146.93. 

GWPC Recommendations: Post-injection site care means monitoring and other 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24863

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24864

168
actions (including corrective action) following cessation of injection, as 

required under 146.93. 

Rationale: The definition should explain the meaning and not impose substantive 

requirements. These requirements are already addressed in other sections. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Comment: EPA Proposal: Pressure front means the zone of elevated pressure that is created 

by the injection of carbon dioxide into the subsurface. For the purposes of 

this subpart, the pressure front of a carbon dioxide plume refers to a zone 

where there is a pressure differential sufficient to cause the movement of 

injected fluids or formation fluids into a USDW. 

GWPC Recommendations: Pressure front means the zone of elevated pressure that is 

created by the injection of the carbon dioxide stream into the subsurface, where 

there is a pressure differential sufficient to cause movement of the carbon 

dioxide stream or formation fluids from the injection zone into a USDW. 

Rationale: Proposal removes words that are unnecessary to provide clarity and 

would only serve to confuse. 

Insert "from the injection zone" for clarification. 

Response: EPA disagrees with the suggested edit. The final definition of pressure front at §146.81(d) is 

unchanged and reads as follows: “[T]he zone of elevated pressure that is created by the injection of 

carbon dioxide into the subsurface. For the purposes of this subpart, the pressure front of a carbon 

dioxide plume refers to a zone where there is a pressure differential sufficient to cause the movement of 

injected fluids or formation fluids into a USDW.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: EPA Proposal: Site closure the point/time, as determined by the Director 

following the requirements under § 146.93, at which the owner or operator of a 

GS site is released from post-injection site care responsibilities. 

GWPC Recommendations: Site closure means the point/time, as determined by the 

Director following the requirements under §146.93, at which the owner or 

operator of a GS project is released from post-injection site care 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24865

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24866

169
responsibilities. 

Rationale: Add "means" 

Suggest using "GS project" to be consistent with other definitions 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: EPA Proposal: Transmissive fault or fracture means a fault or fracture that has 

sufficient permeability and vertical extent to allow fluids to move between 

formations. 

GWPC Recommendations: Transmissive fault or fracture means a fault or fracture 

that has sufficient permeability and vertical extent to allow fluids to move 

beyond the confining zone. 

Rationale: Recommends changing "between formations" to "beyond the confining 

zone." The term between formations is insufficient as it could also include 

multiple zones within a injection zone. 

Response: EPA has retained the proposed definition, which is the same as the existing definition at 

§148.2, to address transmissive faults and fractures that extend beyond the confining zone. 

Other EPA Comment Codes and Descriptions: 4520 2.5.1 Continuous internal mechanical integrity 

monitoring (seeking comment) 

Comment: EPA (III. A. 4.) proposes "continuous monitoring" of various injection 

parameters. 

- Staff believes "continuous monitoring" is appropriate but that the 

precise definition of "continuous monitoring" may be contentious. 

Response: EPA agrees with the commenter regarding the importance of demonstrating internal 

mechanical integrity (MI) and believes that continuous pressure monitoring to demonstrate internal 

mechanical integrity of Class VI wells is important, given the potential corrosive impact of CO2 and 

impurities on well materials, the potential geomechanical impacts to well integrity due to CO2 phase 

changes, and the temperature and pressure effects associated with injecting supercritical CO2. See 

§146.89(b). EPA also believes that the technology for continuous monitoring is practicable, available, 

and is currently in fairly wide use. EPA anticipates that the owner or operator’s testing and monitoring 

plan will describe the proposed specific equipment and recording frequency. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24867

Commenter Name: Steven Chester Letter ID: 0264

Commenter Organization: Michigan Department of Environmental Quality 

(MDEQ)

Comment ID: 

22842

170
Other EPA Comment Codes and Descriptions: 4500 2.5 Proposed Mechanical Integrity Testing 

(MIT) Requirements (40 CFR 146.89) 

Comment: Definition of "Significant Leakage" 

TFI requests that EPA define the term "significant leakage" in the context 

of mechanical integrity testing and quantify amounts to avoid misinterpretations 

and to prevent de minimus CO2 leakage from falling under this term. 

Response: A properly designed and operated well should have no leakage in the casing, tubing, or 

packer and no fluid movement into a USDW through channels adjacent to the wellbore. While the intent 

of MITs is to detect these types of problems as early as possible, the goal of the well design and 

construction requirements at §146.86 is the complete absence of such problems. EPA clarifies that the 

purpose of the "significant leakage" language in this narrow context is simply to avoid triggering 

corrective actions for essentially de minimis situations. Determining whether a MIT result should trigger 

follow-up action is necessarily a case and site-specific situation; as a result, EPA does not believe it is 

appropriate to define the term "significant leakage" in the context of MITs. In addition, EPA has not 

defined this term for purposes of other injection well classes and this has not been shown to hinder 

permitting authorities' and owners or operators' ability to assess whether injection wells have adequate 

mechanical integrity. EPA believes that this approach allows states flexibility, will not interfere with the 

implementation of existing UIC programs, and maintains protection of USDWs from endangerment. 

In keeping with its adaptive rulemaking approach, the Agency plans to collect and review data every six 

years on early GS projects, including MIT data, to determine whether the appropriate amount and types 

of information and appropriate documentation are being collected, and to determine if modifications to 

the requirements are appropriate or necessary. For additional information, please see the discussion of 

MITs in the final rule preamble. 

Other EPA Comment Codes and Descriptions: 4500 2.5 Proposed Mechanical Integrity Testing 

(MIT) Requirements (40 CFR 146.89) 

Comment: 146.89 Mechanical Integrity. 

This rule uses the term "significant" in a number of places when describing 

leaks. There should be either a definition of "significant" or the wells should 

be adequately sealed so that there are no leaks. 

Response: A properly designed and operated well should have no leakage in the casing, tubing, or 

packer and no fluid movement into a USDW through channels adjacent to the wellbore. While the intent 

of MITs is to detect these types of problems as early as possible, the goal of the well design and 

construction requirements at §146.86 is the complete absence of such problems. EPA clarifies that the 

purpose of the "significant leakage" language in this narrow context is simply to avoid triggering 

corrective actions for essentially de minimis situations. Determining whether a MIT result should trigger 

follow-up action is necessarily a case and site-specific situation; as a result, EPA does not believe it is 

appropriate to define the term "significant leakage" in the context of MITs. In addition, EPA has not 

defined this term for purposes of other injection well classes and this has not been shown to hinder 

permitting authorities' and owners or operators' ability to assess whether injection wells have adequate 

mechanical integrity. EPA believes that this approach allows states flexibility, will not interfere with the 

Commenter Name: William Herz Letter ID: 0266

Commenter Organization: The Fertilizer Institute Comment ID: 22883

Commenter Name: Donn Miller Letter ID: 0270

Commenter Organization: State of Oregon, Water Resources Department Comment ID: 22888

171
implementation of existing UIC programs, and maintains protection of USDWs from endangerment. 

In keeping with its adaptive rulemaking approach, the Agency plans to collect and review data every six 

years on early GS projects, including MIT data, to determine whether the appropriate amount and types 

of information and appropriate documentation are being collected, and to determine if modifications to 

the requirements are appropriate or necessary. For additional information, please see the discussion of 

MITs in the final rule preamble. 

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment); 5280 2.8.2.4 USDW non-endangerment demonstrations 

Comment: (e) Concern exists regarding the need for (i) a standard (in concentration or 

saturation) for defining the edge of a CO2 plume, (ii) clear definition of the 

term "stabilization" as applied to fate and transport of an injected CO2 plume 

and pressure front, and (iii) a clarified specification of the performance 

standard for the necessary demonstration to enable termination of the iterative 

process of monitoring/modeling and related corrective action. If "stabilization" 

means absence of plume movement or pressure change, it is our understanding from 

CO2-GS research efforts that indefinitely long periods of monitoring, modeling, 

and corrective action may be required in contrast to the default period of fifty 

years cited in the proposed rules and preamble. A more appropriate basis for 

demonstrations of protection of underground sources of drinking water (USDW) 

would be keyed to the presence of induced pressure conditions in the injection 

zone, spatially and temporally. When and where such pressure conditions are 

insufficient to cause endangerment of a USDW through leakage pathways such as 

improperly constructed or plugged wells or transmissible faults, the required 

USDW protection should be considered to be present. Accordingly, if the 

termination of monitoring, modeling, and corrective action is ultimately 

dependent on making the subject demonstration, it is recommended that the "fifty 

year" specification be deleted from the rule. This would conform the 

requirements for post-injection site care for Class VI wells more closely to the 

post-closure care specifications and concepts existing for Class I wells. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring timeframe. 

Instead, EPA believes that such determinations are site-specific and should be described in a project 

specific post-injection site care and site closure plan. EPA also believes that periodic reviews and 

updates, where necessary, to the plan are important to ensuring that the site continues to be managed 

effectively and to determine whether shortening the monitoring timeframe is appropriate. 

EPA acknowledges that many site-specific factors will influence the determination of when the CO2 

plume and pressure front no longer pose a risk of endangerment to USDWs. It is for this reason that 

EPA believes that individual UIC Directors, in consultation with operators, will be in the best position to 

determine whether additional post-injection site care is needed. EPA expects this decision to be made 

based on relevant site data and in consultation with all potentially impacted parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time 

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that a 

complete cessation of plume movement is not required, only a demonstration that the plume and 

pressure front no longer pose a risk of endangerment to USDWs. 

Commenter Name: Mark Vickery Letter ID: 0280

Commenter Organization: Texas Commission on Environmental Quality Comment ID: 24104

172
EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist Directors 

in evaluating proposed well plugging plans and post-injection site care and site closure plans under 

146.92 and 146.93. The guidance describes recommended approaches for how an owner or operator 

could plug injection and monitoring wells; perform post-injection monitoring; demonstrate non 

endangerment; and perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: • "Geologic sequestration" should not be defined only for the purpose of 

protecting USDWs, but also for the purpose of preventing re-emissions of 

injected carbon dioxide to the atmosphere according to a defined permanence 

standard, as NRDC stated in its Dec24, 2008 comments; 

Response: EPA clarifies that atmospheric emissions monitoring and quantification are outside the scope 

of the Class VI GS rulemaking. The UIC program’s authority under the SDWA focuses on ensuring that 

GS projects are permitted, sited, constructed, operated, monitored, and closed in a manner that protects 

USDWs from endangerment. 

In a separate rulemaking under authority of the Clean Air Act, EPA is amending the Greenhouse Gas 

Reporting Program at 40 CFR Part 98 to add reporting requirements for CO2 injection and geologic 

sequestration. The greenhouse gas reporting requirements build on the Class VI requirements outlined in 

the final rule with the additional goals of verifying the amount of CO2 sequestered and collecting data 

on any CO2 emissions to the surface from Class VI GS facilities. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Comment: 3. Transmissive faults or fractures 

The proposed rule in §146.83(a)(2) requires a confining zone(s) that is free of 

transmissive faults or fractures, while §146.81 defines this term as "A fault or 

fracture that has sufficient permeability and vertical extent to allow fluids to 

move between formations". We recommend the following modification to the 

definition in §146.81(d) in order to avoid unduly restricting movement that is 

merely between formations: 

"Transmissive fault or fracture means a fault or fracture that has sufficient 

permeability and vertical extent to allow fluids to move beyond a confining 

zone." 

Response: EPA disagrees with the suggested edit. The final definition of transmissive fault or fracture at 

§146.81(d) is unchanged and reads as follows: “[A] fault or fracture that has sufficient permeability and 

vertical extent to allow fluids to move between formations.”

Commenter Name: George Peridas Letter ID: 0291

Commenter Organization: Natural Resources Defense Council Comment ID: 25289

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25310

173
The confining zone definition at §146.83(a)(2) also is unchanged and reads as follows: “Free of 

transmissive faults or fractures and of sufficient areal extent and integrity to contain the injected carbon 

dioxide stream and displaced formation fluids and allow injection at proposed maximum pressures and 

volumes without initiating or propagating fractures in the confining zone(s).” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: 4. Definition of confining zone 

The proposed definition of confining zone in §146.81(d) requires that the 

formation act as "a barrier" to fluid movement, which may be unnecessarily 

strict. The definition also fails to recognize that it is movement through and 

beyond the confining zone that needs to be limited. We recommend retaining the 

current UIC program definition of confining zone as preferable to the proposed 

definition with one revision to address the possibility that a confining zone 

for a particular project may be beneath rather than above the injection zone. 

"Confining zone means a geological formation, group of formations, or part of a 

formation that is capable of limiting fluid movement from an injection zone." 

Response: EPA acknowledges the comment and disagrees that the definition of confining zone is too 

strict. EPA clarifies that §146.83(a) requires that any GS project must have at least one confining zone 

(i.e., impermeable layer) between the injection zone and the lowermost USDW. EPA further believes 

that, in some situations, the presence of additional confining and containment zones above the primary 

(i.e., lowermost) confining zone can improve USDW protection. These layers could further impede 

vertical fluid movement and allow for pressure dissipation, and also provide additional sites for 

monitoring, mitigation, and remediation. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: 5. Area of review definition and basis 

We also suggest that the second sentence of the proposed definition of GS 

project be transferred to the definition of area of review as recommended below. 

This language also reflects a change from "brine" to "formation fluids." 

"Area of review means the subsurface three-dimensional extent of the carbon 

dioxide stream plume and the associated pressure front, as well as the overlying 

formations, [any USDWs underlying an injection zone along with any intervening 

formations,] [FN2] and the surface area above that delineated region." 

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25312

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25313

174
[FN2] The bracketed language should be included to the extent that the 

regulations authorize GS above USDWs, an issue on which the signatories have 

expressed differing views in our respective comments on the proposed rule. See 

footnote 1 above. 

In addition, we recommend that the second sentence included both in EPA’s 

proposed definition of area of review and in section 146.84(a) be dropped from 

the definition and retained in section 146.84(a) but modified to read as 

follows: 

"(a) The area of review is based on computational modeling, as well as 

monitoring and other operational data, that account for the physical and 

chemical properties of all phases of the injected carbon dioxide stream." 

The first sentence of section 146.84(a), which duplicates the definition of area 

of review, should be deleted from section 146.84(a) and retained in the 

definition with the modifications presented above. 

Response: EPA disagrees that the AoR definition needs to specifically include the overlying formations 

and surface area above the delineated region. The intent of the AoR, a long-standing concept within the 

UIC Program, is to delineate the surface area and all subsurface formations below it that may potentially 

be impacted by injection activity. Acceptable delineation models will provide predictions of CO2 fate 

and transport, as well as changes in formation pressure, in three dimensions as a function of time that 

can be used to delineate the subsurface storage site and the AoR. 

Although EPA disagrees with the commenter's suggested change, the Agency has carefully considered 

all comments on the AoR definition at 146.84(a) and modified it to read as follows: The region 

surrounding the geologic sequestration project where USDWs may be endangered by the injection 

activity. The area of review is delineated using computational modeling that accounts for the physical 

and chemical properties of all phases of the injected CO2 stream and is based on available site 

characterization, monitoring, and operational data. EPA believes that this definition is sufficiently broad 

and describes both the intent of the computational modeling and the relationship of the AoR to areas that 

are subject to the risks associated with injection. 

Comment: We're pleased that the definition of zone of elevated pressures, Section 146.81 

focuses both on the pressure that would drive CO2 through a confining zone, and 

also on the pressures that would drive fluid to a confining zone. 

Response: The Agency acknowledges the comment. The final definition of pressure front at §146.81(d) 

is unchanged, and reads as follows: “[T]he zone of elevated pressure that is created by the injection of 

carbon dioxide into the subsurface. For the purposes of this subpart, the pressure front of a carbon 

dioxide plume refers to a zone where there is a pressure differential sufficient to cause the movement of 

injected fluids or formation fluids into a USDW.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Commenter Name: Scott Anderson Letter ID: 0510

Commenter Organization: Environmental Defense Fund Comment ID: 21220

175
Comment Code: 1230 1.1.1.2 General comments on the regulatory text 

Individual Comments 

Comment: 146.82 (b): This will be an onerous task based on the proposed definition of 

AoR. Not necessary if the pressure front is calculated or determined. 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: G. VAGUE LANGUAGE AND DEFINITIONAL PROBLEMS 

There are many words and phrases in the draft regulations that are not well 

defined, and the meaning of which ought to be expanded upon. For instance, what 

might constitute "significant leakage" in the context of mechanical integrity 

testing should be identified. 

Response: A properly designed and operated well should have no leakage in the casing, tubing, or 

packer and no fluid movement into a USDW through channels adjacent to the wellbore. While the intent 

of MITs is to detect these types of problems as early as possible, the goal of the well design and 

construction requirements at §146.86 is the complete absence of such problems. EPA clarifies that the 

purpose of the "significant leakage" language in this narrow context is simply to avoid triggering 

corrective actions for essentially de minimis situations. Determining whether a MIT result should trigger 

follow-up action is necessarily a case and site-specific situation; as a result, EPA does not believe it is 

appropriate to define the term "significant leakage" in the context of MITs. In addition, EPA has not 

defined this term for purposes of other injection well classes and this has not been shown to hinder 

permitting authorities' and owners or operators' ability to assess whether injection wells have adequate 

mechanical integrity. EPA believes that this approach allows states flexibility, will not interfere with the 

implementation of existing UIC programs, and maintains protection of USDWs from endangerment. 

The final definition of mechanical integrity is unchanged. EPA clarifies that mechanical integrity is 

defined at §146.89(a) as the absence (1) of significant leak in the casing, tubing, or packer and (2) of 

significant fluid movement into a USDW through channels adjacent to the injection wellbore. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Commenter Name: Michael H. Cochran Letter ID: 0108

Commenter Organization: Bureau of Water, Division of Environment, Kansas 

Department of Health & Environment (KDHE)

Comment ID: 

21962

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23820

Commenter Name: Edward Steadman Letter ID: 0220

176
Comment: Page 43498. The example cited here (Crystal Geyser, Utah) is not associated with 

an "injection activity." It is naturally occurring CO2 that leaks via an 

improperly abandoned exploration well. 

Response: EPA agrees with the commenter that the Crystal Geyser site is not associated with injection. 

However, this incident demonstrates that abandoned or improperly plugged boreholes can serve as 

conduits for migration of fluids to USDWs. It is for this reason that the final rule includes requirements 

related to performing corrective action on all deficient wells within the AoR at §146.84, and proper 

injection well construction that meets the goals of §146.86. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: (E) ISSUES SPECIFICALLY RELATED TO OIL & GAS PRODUCTION 

EPA has appropriately restricted the applicability of Class VI regulations to 

projects that are exclusively geologic sequestration projects. Furthermore, BP 

appreciates EPA’s efforts to limit this rulemaking to the authority vested in 

EPA by Congress pursuant to the Safe Drinking Water Act ("SDWA"). BP requests 

that EPA include some of the discussion in the Preamble to the Final Rule to 

ensure that unrelated activities in the Oil & Gas industry are not impacted by 

unintended inferences or interpretations of the Proposed Rule. 

Response: EPA clarifies that the final Class VI regulations require that any owner or operator injecting 

CO2 for the primary purpose of long term storage obtain a Class VI permit with some special 

consideration for the fact that they are transitioning from a well not originally designed to meet Class VI 

requirements. The Director has the authority to determine at what point a Class VI permit is required for 

those projects that are transitioning from the primary purpose of EOR to long term storage of CO2. The 

final regulation provides a set of technical factors for the Director to evaluate in making this 

determination, at §144.19. EPA believes that this approach provides sufficient protection of USDWs 

when there is an increased risk to USDWs as compared to traditional Class II operations while allowing 

for site-specific flexibility. For more information, please see the discussion on transition of Class II 

wells in the preamble to the final GS rule. 

EPA recognizes that the oil and gas industry has decades of experience injecting CO2 for the purpose of 

ER, and that sites used for ER may be suitable for GS and may be among the first GS sites. EPA also 

believes that the nature and risks of CO2 injection for the primary purpose of long term storage poses 

different risks than injection for the primary purpose of ER, and therefore has developed new Class VI 

regulations to address these unique risks. For example, the volume of CO2 anticipated to be injected for 

long term storage is significantly greater than for ER operations. Reservoir pressure conditions will also 

be different, with Class VI injection operations involving large volumes of CO2 and likely having higher 

pressures within their storage formations than Class II ER projects. 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Commenter Organization: The Energy and Environmental Research Center at the 

University of North Dakota

Comment ID: 

21587

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21759

177
Individual Comments 

Other EPA Comment Codes and Descriptions: 2048 1.5.2.4 Oppose Class VI/ Support Class V 

experimental technology well 

Comment: 144.18: Should be reworded along the lines of: upon the effective date of these 

regulations, new Class V wells must obtain a permit prior to construction. 

Response: EPA clarifies that any owner or operator seeking to construct an injection well must obtain a 

permit before beginning injection, but not necessarily the construction of the well. Owners and operators 

of Class VI wells for long-term sequestration or Class V experimental technology wells (for 

experimental GS projects) must submit information about the well, the geology of the site, and the 

planned injection to demonstrate to the Director that the project will be operated in a manner that 

protects USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: Geologic sequestration project means an injection well or wells used to 

emplace a CO2 stream beneath the lowermost formation containing a USDW, OR 

ANOTHER FORMATION, IF THE DIRECTOR DETERMINES THAT INJECTION INTO THE 

OTHER 

FORMATION WILL NOT ENDANGER USDWS. It includes the subsurface 3-D extent of 

the carbon dioxide plume, associated pressure front, and displaced brine, as 

well as the surface area above that delineated region. 

{RRC suggests adding to the end of the first sentence of the definition of 

Geologic sequestration project, "or another formation, if the Director 

determines that injection into the other formation will not endanger USDWs." } 

Response: EPA disagrees with the suggested edit. However, the Agency has modified the final 

definition of geologic sequestration project at §146.81(d) to read as follows: “[A]n injection well or 

wells used to emplace a carbon dioxide stream beneath the lowermost formation containing a USDW; 

or, wells used for geologic sequestration of carbon dioxide that have been granted a waiver of the 

injection depth requirements pursuant to requirements at §146.95; or, wells used for geologic 

sequestration of carbon dioxide that have received an aquifer exemption expansion. It includes the 

subsurface three-dimensional extent of the carbon dioxide plume, associated pressure front, and 

displaced brine, as well as the surface area above that delineated region.” 

EPA adds that the final rule contains a new provision for owners or operators to seek a waiver from the 

injection depth requirements, at §146.95. Based on its evaluation of all public comments and input on 

the proposed rule and the Notice of Data Availability and Request for Comment, EPA has made many 

revisions to the Class VI GS rule. Please see the final rule and preamble for additional information. 

Commenter Name: Michael H. Cochran Letter ID: 0108

Commenter Organization: Bureau of Water, Division of Environment, Kansas 

Department of Health & Environment (KDHE)

Comment ID: 

21959

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24759

Commenter Name: Leslie Savage Letter ID: 0122

178
Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: Transmissive fault or fracture means a fault or fracture that has sufficient 

permeability and vertical extent to allow fluids to move between formations. 

{Recommend that the fault or fracture be "known."} 

Response: EPA disagrees with the suggested edit. The final definition of transmissive fault or fracture at 

§146.81(d) is unchanged and reads as follows: “[A] fault or fracture that has sufficient permeability and 

vertical extent to allow fluids to move between formations.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: (2) Location, orientation, and properties of known or suspected faults and 

fractures that may transect the confining zone(s) in the area of review and 

a determination that they would not interfere with containment; 

(4) Data on the depth, areal extent, thickness, mineralogy, porosity, 

permeability and capillary pressure of the injection and confining zone(s); 

including geology/facies changes based on field data which may include geologic 

cores, outcrop data, seismic surveys, well logs, and names and lithologic 

descriptions; 

Response: EPA believes that the plural for injection zone(s) should be retained in the Final Rule in 

recognition of the fact that more than one injection zone may be used at some GS sites. EPA believes 

that in some geologic settings, the presence and identification of additional confining and containment 

zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These 

formations could further impede vertical fluid movement, allow for pressure dissipation, and provide 

additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection 

of USDWs from endangerment. While other countries may not require such additional protection, EPA 

believes that providing the Director this additional discretion is an important element of assuring that GS 

activities will not endanger USDWs. 

Please see the final rule and the discussion of geologic site characterization in the preamble for 

additional information. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: (e) A tabulation of all wells within the AOR which penetrate the injection or 

confining zone(s). Such data must include a description of each well's type, 

construction, date drilled, location, depth, record of plugging and/or 

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24761

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24762

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24763

179
completion, and any additional information the Director may require; 

{Definition of confining zone includes multiple formations. Do not 

imply that multiple confining zones are preferable to one (good) 

confining zone.} 

Response: EPA disagrees with the suggested edit. The final language in §146.82 is unchanged. EPA 

retains the requirement to identify additional containment/confining zones, if required by the Director, 

as proposed in §146.83(b). EPA acknowledges that such additional zones may not be needed in all 

circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her 

understanding of a particular site. EPA believes that, in some situations, the presence of additional 

confining and containment zones above the primary (i.e., lowermost) confining zone can improve 

USDW protection. These layers could further impede vertical fluid movement and allow for pressure 

dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's 

decision is supported by commenters representing states, water associations, and an electric utility who 

assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and 

permitting a site for GS projects, and would improve understanding of the project as a whole and 

promote better modeling of the site. 

Additionally, the Agency has modified the final definition of confining zone to read as follows: “[A] 

geologic formation, group of formations, or part of a formation stratigraphically overlying the injection 

zone that acts as barrier to fluid movement. For Class VI wells operating under an injection depth 

waiver, confining zone means a geologic formation, group of formations, or part of a formation 

stratigraphically overlying and underlying the injection zone.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: (f) Maps and stratigraphic cross sections indicating the general vertical and 

lateral limits of all USDWs, water wells and springs within the area of review, 

their positions relative to the injection zone(s) and the direction of water 

movement, where known; 

{Consistency with definition and use of term in other areas of the rules.} 

Response: EPA believes that the plural for injection zone(s) should be retained in the Final Rule in 

recognition of the fact that characterizing more than one injection zone may be necessary at some GS 

sites. EPA believes that in some geologic settings, the presence and identification of additional confining 

and containment zones above the primary (i.e., lowermost) confining zone can improve USDW 

protection. These formations could further impede vertical fluid movement, allow for pressure 

dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also 

affording the greatest protection of USDWs from endangerment. EPA believes that providing the 

Director this additional discretion is an important element of assuring that GS activities will not 

endanger USDWs. 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24764

180
Please see the final rule and the discussion of geologic site characterization in the preamble for 

additional information. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: (i) The compatibility of the CO2 stream with fluids in the injection zone and 

minerals in both the injection and the confining zone(s), based on the 

results of the formation testing program, and with the materials used to 

construct the well; 

{See comment above.} 

Response: The final rule will allow the Director to require more than one confining zone; therefore, 

EPA did not make the suggested change. 

Please see the final rule and the discussion of geologic site characterization in the preamble for 

additional information. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: (m) Proposed procedure to outline steps necessary to conduct injection 

operation; 

{"Proposed procedure to outline steps" does not make sense. Recommend "Outline 

of steps ...."} 

Response: EPA disagrees that the suggested edit provides more clarity to the requirements and has 

retained the language as proposed. Additionally, similar language is used for other UIC well classes and 

the regulated community and permitting officials are familiar with the terms. 

Please see the final rule and the discussion of geologic site characterization in the preamble for 

additional information. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: (1) An injection zone of sufficient areal extent, thickness, porosity, and 

permeability to receive the total anticipated volume of the carbon dioxide 

stream; 

{Redundant - simply repeats the definition of "injection zone." Either take 

this language out of the definition or take it out of here.} 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24765

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24766

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24767

181
Response: EPA acknowledges the comment. For consistency, §146.83(a)(1) includes the definition of 

injection zone. EPA clarifies that §146.83 identifies the specific criteria that owners or operators must 

meet to demonstrate that a GS site is suitable for GS. 

Other EPA Comment Codes and Descriptions: 3110 2.1.1 Proposed siting requirements (i.e., 

injection/confining zones, trapping mechanism) 

Comment: (2) A confining zone(s) that is free of transmissive faults or fractures and 

of sufficient areal extent and integrity to contain the injected carbon dioxide 

stream and displaced formation fluids and allow injection at proposed maximum 

pressures and volumes without initiating or propagating fractures in the 

confining zone(s); and 

{Redundant. Repeats definition of "confining zone." Also, implies that the 

confining zone cannot have a single fracture, no matter how small. Much more 

stringent than for Class I hazardous wells.} 

Response: EPA believes that the plural for injection zone(s) should be retained in the Final Rule in 

recognition of the fact that characterizing more than one injection zone may be necessary at some GS 

sites. EPA believes that in some geologic settings, the presence and identification of additional confining 

and containment zones above the primary (i.e., lowermost) confining zone can improve USDW 

protection. These formations could further impede vertical fluid movement, allow for pressure 

dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also 

affording the greatest protection of USDWs from endangerment. While other countries may not require 

such additional protection, EPA believes that providing the Director this additional discretion is an 

important element of assuring that GS activities will not endanger USDWs. 

Other EPA Comment Codes and Descriptions: 3120 2.1.2 Need to identify additional confining and 

containment zones (seeking comment) 

Comment: (b) At the Director's discretion, owners or operators of Class VI wells must 

identify and characterize additional zones that will impede vertical fluid 

movement, are free of faults and fractures that may interfere with containment, 

allow for pressure dissipation, and provide additional opportunities for 

monitoring, mitigation and remediation. 

{Redundant and unnecessary. Language in definition of "confining zone."} 

Response: EPA retains the requirement to identify additional containment/confining zones, if required 

by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be 

needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on 

his or her understanding of a particular site. EPA believes that, in some situations, the presence of 

additional confining and containment zones above the primary (i.e., lowermost) confining zone can 

improve USDW protection. These layers could further impede vertical fluid movement and allow for 

pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The 

Agency's decision is supported by commenters representing states, water associations, and an electric 

utility who assert that these requirements promote a flexible, risk-based, site-specific approach to 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24768

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24769

182
characterizing and permitting a site for GS projects, and are intended to improve understanding of the 

project as a whole and promote better modeling of the site. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: §146.84 Area of review and corrective action. 

(a) The area of review is the region surrounding the geologic sequestration 

project that may be impacted by the injection activity. The area of review is 

based on computational modeling that accounts for the physical and chemical 

properties of all phases of the injected carbon dioxide stream. 

{Redundant - same as the definition of "area of review."} 

Response: Based on review of all public comments on the AoR definition at 146.84(a), the Agency has 

modified it to read as follows: The region surrounding the geologic sequestration project where USDWs 

may be endangered by the injection activity. The area of review is delineated using computational 

modeling that accounts for the physical and chemical properties of all phases of the injected CO2 stream 

and is based on available site characterization, monitoring, and operational data. 

Other EPA Comment Codes and Descriptions: 3700 2.2.5 Comments on the requirement for an AoR 

and corrective action plan 

Comment: (b) The owner or operator of a Class VI well must prepare, maintain, and comply 

with a plan to delineate the AOR for a proposed geologic sequestration project, 

periodically reevaluate the delineation, and perform corrective action that 

meets the requirements of this section AT A FREQUENCY AND IN A MANNER THAT 

and is acceptable to the Director. As a part of the permit application 

for approval by the Director, the owner or operator must submit an area of 

review and corrective action plan that includes the following information: 

Response: EPA disagrees with the suggested change, and is retaining the approach of setting a 

minimum fixed frequency for reevaluating the AoR but has, based on commenters' input, changed the 

frequency from 10 years to at least every 5 years, as specified in §146.84(e). EPA agrees with 

commenters that site-specific information is an important factor in determining an appropriate AoR 

reevaluation frequency, and adds that the owner or operator's AoR and corrective action plan must 

describe the minimum fixed frequency for reevaluating the AoR and the site-specific conditions on 

which this frequency is based. EPA adds that the Director will evaluate the proposed plan in connection 

with a review of a vast amount of geologic and proposed operating data in determining whether to 

approve the plan. EPA is developing guidance on recommended approaches for preparing all of the 

required GS project plans, which will address considerations for determining an appropriate AoR 

reevaluation schedule. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24770

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24771

Commenter Name: Leslie Savage Letter ID: 0122

183
Other EPA Comment Codes and Descriptions: 3530 2.2.3.1 AoR reevaluation frequency (seeking 

comment); 3700 2.2.5 Comments on the requirement for an AoR and corrective action plan 

Comment: (2) A description of: (i) The minimum fixed frequency, not to exceed 10 years, 

the owner or operator proposes to reevaluate the area of review; (ii) The 

monitoring and operational conditions that would warrant a reevaluation of the 

area of review prior to the next scheduled reevaluation as determined by the 

minimum fixed frequency established in paragraph (b)(2)(i) of this section. 

{Suggest that there be no minimum fixed frequency for reevaluation of the AoR, 

but that such review be based on site-specific circumstances. } 

Response: EPA believes that periodic AoR reevaluation at a set frequency of at least every 5 years is 

necessary to ensure protection of USDWs from endangerment and address the uncertainties inherent in 

predictive modeling. Periodic AoR reevaluations at §146.84(e) ensure that a deliberate effort is made to 

verify, based on monitoring and operational data, that the CO2 plume is moving within the subsurface as 

predicted. EPA believes that less frequent reevaluations may not be sufficient to appropriately model 

plume and pressure front movement, establish conditions for corrective action, and ensure protection of 

USDWs from endangerment. 

EPA clarifies that if site monitoring data agrees with the existing AoR delineation, a model recalibration 

may not be necessary, and the AoR reevaluation may consist of a demonstration that the current AoR 

delineation is adequate based on site monitoring data. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action; 3700 2.2.5 Comments 

on the requirement for an AoR and corrective action plan 

Comment: (II)(iii) How monitoring and operational data (e.g., injection rate and 

pressure) will be used to inform an area of review reevaluation; and 

(iv) How corrective action will be conducted to meet the requirements of 

paragraph (d) of this section, including what corrective action will be 

performed prior to injection and what, if any, portions of the area of review 

will have corrective action addressed on a phased basis and how the phasing will 

be determined; how corrective action will be adjusted if there are changes in 

the area of review; and how THE site WILL BE accessed will be guaranteed for 

future corrective action. 

{Word Choice. Secure rather than guarantee. } 

Response: The purpose of the corrective action requirement at §146.84(d) is to ensure that all wells in 

the AoR that have the potential to cause the movement of CO2 or other fluids into or between USDWs 

receive appropriate corrective action. In general, to meet this requirement, the owner or operator will 

mostly likely need to obtain the right of access to wells that may require corrective action, and 

demonstrate they have done this in their proposed AoR and corrective action plan. For this reason, the 

owner or operator must describe in the AoR and corrective action plan how site access will be 

guaranteed for future corrective action, as specified in §146.84(b)(2)(iv). The final rule retains the 

requirement as proposed. 

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24772

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24773

184
Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: (1) Predict, using computational modeling, the projected lateral and vertical 

migration of the carbon dioxide plume and formation fluids in the subsurface 

from the commencement of injection activities until the plume movement ceases, 

pressure differentials sufficient to cause the movement of injected fluids or 

formation fluids into a USDW are no longer present, or FOR after a fixed 

time period as determined by the Director. The modelINGmust: 

Response: EPA has clarified this language in the final rule. It now reads, “Predict, using existing site 

characterization, monitoring and operational data, and computational modeling, the projected lateral and 

vertical migration of the carbon dioxide plume and formation fluids in the subsurface from the 

commencement of injection activities until the plume movement ceases, until pressure differentials 

sufficient to cause the movement of injected fluids or formation fluids into a USDW are no longer 

present, or until the end of a fixed time period as determined by the Director.” 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: (i) Be based on detailed geologic data collected to characterize the injection 

zone AND, confining zone and any additional zones; and anticipated 

operating data, including injection pressures, rates and total volumes over the 

proposed life of the geologic sequestration project; 

(ii) Take into account RELEVANT any geologic heterogeneities AND, data 

quality, and their possible impact on model predictions; and 

(iii) Consider potential migration through KNOWN faults, fractures, and 

artificial penetrations. 

Response: The final rule retains this requirement as proposed, except that 146.84(c)(1)(ii) also requires 

owners or operators to take into account other discontinuities in addition to geologic heterogeneities. 

EPA disagrees that only the injection and confining zones should be included in AoR modeling of GS 

sites. EPA believes that the modeling should also take into account the possibility of displaced fluids or 

brines caused by a lateral and/or vertical pressure plume, and therefore it may be necessary to include 

additional zones along with the confining/injection zones to ensure the integrity of the confining zone 

and ultimately protect a USDW from endangerment. 

Other EPA Comment Codes and Descriptions: 3420 2.2.2.1 Scope of the inventory process (e.g., 

reliance on publicly available information, depth of wells) 

Comment: (2) Using methods approved by the Director, identify all KNOWN ARTIFICIAL 

penetrations THROUGH THE CONFINING ZONE, including active and abandoned wells 

and underground mines, in the area of review that may penetrate the confining 

zone. Provide a description of each well's type, construction, date drilled, 

location, depth, record of plugging and/or completion, and any additional 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24774

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24775

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24776

185
information the Director may require; and 

Response: EPA is retaining this requirement as proposed. EPA agrees with commenters that, for most 

GS sites, relying on database and other public records searches (i.e., of "known" artificial penetrations) 

will be sufficient to meet the requirements at §146.84(c)(2). However, the Agency recognizes that there 

may be situations where additional surveys or research to locate wells may be appropriate. For example, 

there may be cases where the Director may determine that ground or airborne surveys for wells are 

appropriate, e.g., if there is reason to believe, based on knowledge of the site or of available data, that 

the incompleteness of information on known wells could compromise USDW protection from 

endangerment. In order to preserve the Director's discretion to require an operator to supplement a 

records search, EPA did not make the suggested change. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: (3) Determine which abandoned wells in the AOR have been plugged in a manner 

that prevents the movement of CO2 or FORMATION associated fluids that may 

endanger USDWs. 

Response: EPA clarifies that the term "associated fluids" as proposed in §146.84(c)(3) refers to 

formation fluids, other injectates, etc. that may be present in the subsurface and affect movement of the 

CO2 plume and/or pressure front. EPA believes this terminology would incorporate any fluids in the 

subsurface that could potentially move through artificial penetrations and affect USDWs. EPA has 

revised the language at §146.84(c)(3) to read, "... carbon dioxide or other fluids that may endanger 

USDWs..." 

Other EPA Comment Codes and Descriptions: 3460 2.2.2.3 Acceptable corrective action techniques 

for GS sites (e.g., cements) 

Comment: (d) Owners or operators of Class VI wells must perform corrective action USING 

CORROSION RESISTANT MATERIAL, WHEN APPROPRIATE, on all wells IDENTIFIED IN 

§146.84(C)(2) in the AOR that are determined to need corrective action using 

methods necessary to prevent the movement of fluid into or between USDWs 

including use of corrosion resistant materials, where appropriate. 

Response: EPA revised the text at §146.84(d) to require the use of materials that are "compatible with 

the carbon dioxide stream." EPA believes this language change addresses commenters' concerns and is 

also consistent with other language regarding materials requirements in the GS rule. 

Other EPA Comment Codes and Descriptions: 3500 2.2.3 Area of Review Reevaluation (seeking 

comment) 

Comment: (f) At the minimum fixed frequency, not to exceed 10 years, as AS specified 

in the AOR and corrective action plan, or when monitoring and operational 

conditions warrant, the owner or operator must: 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24777

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24778

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24779

186
Response: EPA believes that periodic AoR reevaluation at a set frequency is necessary to ensure 

protection of USDWs from endangerment and address the uncertainties inherent in predictive modeling. 

Periodic AoR reevaluations at §146.84(e) ensure that a deliberate effort is made to verify, based on 

monitoring and operational data, that the CO2 plume is moving within the subsurface as predicted. EPA 

believes that less frequent reevaluations may not be sufficient to appropriately model plume and 

pressure front movement, establish conditions for corrective action, and ensure protection of USDWs 

from endangerment. 

EPA clarifies that if site monitoring data agrees with the existing AoR delineation, a model recalibration 

may not be necessary, and the AoR reevaluation may consist of a demonstration that the current AoR 

delineation is adequate based on site monitoring data. 

Based on the comments received (including those by water associations, an energy company, 

associations, industries, states, and environmental groups), EPA has changed the minimum frequency 

for the AoR reevaluation from 10 years to at least every 5 years. EPA believes that this revised 

frequency addresses commenters' concerns about the inherent uncertainties in modeling CO2 movement, 

the emerging nature of GS technology, risk-based targeting of monitoring activities, and the unique 

nature of CO2 GS. 

Other EPA Comment Codes and Descriptions: 3500 2.2.3 Area of Review Reevaluation (seeking 

comment) 

Comment: (4) Submit an amended AOR and corrective action plan or demonstrate to the 

Director through monitoring data and modeling results that no CHANGE amendment 

to the AOR and corrective action plan is needed. 

{Appropriate frequency of determining AoR might not be "fixed." Owner or 

operator might need to reevaluate AoR frequently at first, particularly with 

deep brine formations about which there is little history, and then at expanding 

intervals as more information is known.} 

Response: EPA agrees that site-specific factors should be considered in the reevaluation schedule, and 

notes that the AoR and corrective action plan must specify the site-specific monitoring and operational 

conditions that warrant reevaluation, as specified in §146.84(b)(2)(ii). In addition, the Director has 

discretion to require more frequent AoR reevaluation if he or she has reason to believe, based on sitespecific information, that a five-year reevaluation schedule is not sufficiently protective of USDWs. 

However, EPA believes that setting a minimum reevaluation frequency is appropriate. In the final rule, 

the Agency changed the minimum frequency for the AoR reevaluation at §146.84(e) from 10 years to at 

least every 5 years in the final GS rule. EPA believes that this revised frequency addresses commenters' 

concerns about the inherent uncertainties in modeling CO2 movement, the emerging nature of GS 

technology, risk-based targeting of monitoring activities, and the unique nature of CO2 GS. 

Other EPA Comment Codes and Descriptions: 3800 2.3 Proposed Injection Well Construction 

Requirements (40 CFR 146.86) 

Comment: §146.86 Injection well construction requirements. (a) General. The owner or 

operator must ensure that all Class VI wells are constructed and completed to: 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24780

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24781

187
(1) Prevent the ENDANGERMENT OF USDWs movement of fluids into or between USDWs 

or into any unauthorized zones; 

(2) Permit the use of appropriate testing devices and workover tools; and 

(3) Permit continuous monitoring of the annulus space between the injection 

tubing and long string casing. 

Response: EPA disagrees with the suggested edit. EPA believes that protection of USDWs from 

endangerment and prevention of fluid movement between formations is paramount, and believes that the 

language as proposed regarding preventing fluid movement is more specific and protective. 

Appropriately designed and constructed wells are necessary to prevent endangerment to USDWs and 

maintain integrity of the well throughout the lifetime of a GS project. This is the foundation of the 

requirements for construction and pre-operational testing of Class VI wells at §§146.86 and 146.87. 

Other EPA Comment Codes and Descriptions: 3860 2.3.3 Well component degradation 

Comment: (b) Casing and Cementing of Class VI Wells. 

(1) Casing and cement or other materials used in the construction of each Class 

VI well must have sufficient structural strength and be designed for the 

OPERATING life of the WELLgeologic sequestration project. All well 

materials must be compatible with fluids with which the materials may be 

expected to come into contact and meet or exceed standards developed for such 

materials by the API, ASTM International, or comparable standards acceptable to 

the Director. The casing and cementing program must be designed to prevent 

the movement of fluids into or between USDWs. In order to allow the Director 

to determine and specify casing and cementing requirements, the owner or 

operator must provide the following information: 

{The threat to the integrity of the casing and cement and other materials is 

greatest during injection, and quickly decreases as the pressure dissipates 

after cessation of injection. } 

Response: EPA disagrees that the casing, cement or other materials should only be designed for the 

period of the injection process, rather than the life of the sequestration project. GS projects are 

anticipated to have long life spans in comparison to other types of deep injection wells. Not only must 

Class VI wells be able to function safely and properly over the lifespan of the GS project, but they must 

be constructed such that USDWs remain protected after well plugging. The requirements at §146.86 will 

ensure that the well can maintain integrity throughout the proposed life span of the project, including 

after the injection well is plugged and through post-injection site care period and beyond. While the risk 

profile of a GS site will decrease following cessation of injection, EPA believes that Class VI wells must 

be designed to protect USDWs from endangerment for the life of the project. Furthermore, rigorous 

casing and cementing help ensure that the Class VI well will not serve as a conduit for movement of 

fluids associated with future injection operations. 

Other EPA Comment Codes and Descriptions: 3864 2.3.3.2 Use of corrosion-resistant cements 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24782

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24783

188
(seeking comment) 

Comment: (i) Depth to the injection zone; 

(ii) Injection pressure, external pressure, internal pressure and axial loading; 

(iii) Hole size; 

(iv) Size and grade of all casing strings (E.G., wall thickness, external 

diameter, nominal weight, length, joint specification and construction 

material); 

(v) Corrosiveness of the carbon dioxide stream, and formation fluids; 

(vi) Down-hole temperatures AND PRESSURES; 

(vii) Lithology of injection and confining zones; 

(viii) Type or grade of cement, INCLUDING ADDITIVES; and 

(ix) Quantity, chemical composition, and temperature of the CO2 stream. 

{Redundant - look at application requirements.} 

Response: EPA agrees with the suggestion that §146.86(b)(1)(viii) be revised to also address cement 

additives. In the final GS rule, the subparagraph reads as follows: "Type or grade of cement and cement 

additives." 

EPA clarifies that information on down-hole pressures is required at §146.86(b)(1)(ii). 

Other EPA Comment Codes and Descriptions: 3822 2.3.1.1 Depth of surface casing (seeking 

comment) 

Comment: (2) Surface casing must extend through the base of the lowermost USDW ABOVE THE 

INJECTION ZONE and be cemented to the surface. 

Response: EPA disagrees with the suggested edit. The final GS rule at §146.86(b)(2) requires that 

surface casing extend through the base of the lowermost USDW and be cemented to the surface through 

the use of a single string or multiple strings of casing and cement. 

EPA stresses that protection of USDWs from endangerment, regardless of their depth or the number of 

USDWs in an area, is the primary mission and mandate of the UIC program and the purpose of all 

requirements for injection wells. Any injection activity must be demonstrated to not endanger USDWs, 

regardless of their depth, and if such non-endangerment cannot be shown, the activity will not be 

allowed under UIC requirements or the SDWA. 

EPA recognizes concerns regarding construction of Class VI wells where the lowermost USDW is very 

deep. To further address comments on deep injection wells, the final GS rule at §146.95 includes 

requirements for owners or operators that seek a waiver of the injection depth requirements. Owners or 

operators of Class VI wells operating under injection depth waivers must comply with additional 

construction requirements to ensure that wells used to inject above or between USDWs are protective. 

EPA believes that, given the possibility for Class VI wells to operate under injection depth waivers, the 

requirement that surface casing must extend through the base of the lowermost USDW is important for 

USDW protection. 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24784

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24785

189
Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: (3) At least one long string casing, using a sufficient number of centralizers, 

must extend to the injection zone and must be cemented by circulating cement to 

the surface in one or more stages. 

{Circulation of cement unnecessary and more stringent that requirement for Class 

I hazardous waste wells. RRC suggests that it may not be technically feasible 

to cement the full column of one long string casing because the formations you 

likely want to inject into are low-pressure, and typically won't hold a full 

column of cement, making circulation impossible. RRC suggests a certain footage 

of cement, such as 600 ft, and require a bond log to verify it. } 

Response: EPA believes that the construction requirements at §146.86 offer flexibility to the owner or 

operator to propose well construction procedures that are appropriate to the site-specific conditions of 

the project. Section 146.86(b)(3) requires that the long-string casing extend to the injection zone and be 

cemented by circulating cement to the surface in one or more stages. It does not, however, specify how 

cementing would be accomplished, and gives flexibility to the owner or operator to propose alternate 

methods to provide a sufficient amount of cement to meet the standard that USDWs are protected from 

endangerment, subject to the approval of the Director. EPA notes that there are many potential ways to 

meet the requirement, such as the use of staged cementing. 

EPA believes that current cementing technology can address deep well cement columns or low-pressure 

bottom-of-hole formations. The oil and gas industry has experience drilling and cementing wells in very 

deep formations and in formations with low pressures. Less dense, lighter weight cement slurries that 

include nitrogen foam or lightweight microspheres (Sabins 2002; Kulakofsky et al. 2005) are used to 

prevent breakdown of the low pressure formation and loss of circulation. Another way to approach low 

formation pressure conditions is with reverse cementing (pumping the cement into the annulus and 

returning it through the casing). This method uses gravity to place the cement and bypass lost circulation 

zones. Reverse cementing can be combined with other methods such as foam cement. Ten successful 

reverse-cemented wells have been completed in a variety of onshore/offshore environments (Chase 

2008). 

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3864 2.3.3.2 Use of corrosion-resistant cements 

(seeking comment) 

Comment: (5) Cement and cement additives must be compatible with the CO2 stream and 

formation fluids and of sufficient quality and quantity to maintain integrity 

over the design life of the WELL geologic sequestration project. The 

integrity and location of the cement shall be verified using technology capable 

of evaluating cement quality radially and identifying the location of channels 

to ensure that USDWs are not endangered. 

{See comment above.} 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24786

190
Response: EPA disagrees that the casing, cement or other materials should only be designed for the 

period of the injection process, rather than the life of the sequestration project. GS projects are 

anticipated to have long life spans in comparison to other types of deep injection wells. Not only must 

Class VI wells be able to function safely and properly over the lifespan of the GS project, but they must 

be constructed such that USDWs remain protected after well plugging. The requirements at §146.86 will 

ensure that the well can maintain integrity throughout the proposed life span of the project, including 

after the injection well is plugged and through post-injection site care period and beyond. While the risk 

profile of a GS site will decrease following cessation of injection, EPA believes that Class VI wells must 

be designed to protect USDWs from endangerment for the life of the project. Furthermore, rigorous 

casing and cementing help ensure that the Class VI well will not serve as a conduit for movement of 

fluids associated with future injection operations. 

Other EPA Comment Codes and Descriptions: 3826 2.3.1.3 Packer requirements (seeking comment) 

Comment: (i) Depth of setting; 

(ii) Characteristics of the CO2 stream (chemical content, corrosiveness, 

temperature, and density); 

(iii) Injection pressure; 

(iv) Annular pressure; 

(v) Injection rate (intermittent or continuous) and volume of the CO2 stream; 

(vi) Size of casing; and 

(vii) Tubing tensile, burst, and collapse strengths. 

{Repetitive - See application requirements} 

Response: EPA acknowledges that some of the information required under §146.86(c)(3) is also 

required under §146.82(a)(7) as part of the proposed operating requirements. However, EPA notes that 

the Director needs to consider all of the data required under §146.86(c) in order to properly determine 

the tubing and packer specifications, and believes this information should be provided together. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: (c) The owner or operator must record the fluid temperature, pH, conductivity, 

reservoir pressure and the static fluid level of the injection zone(s). 

Response: The text at §146.87(d) as written requires data on the injection zone and confining zone or 

zones. This is to ensure that, if the Director requires characterization of additional 

containment/confining zones (§146.83(b)), appropriate data are collected. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: (d) At a minimum, the owner or operator must determine or calculate the 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24787

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24788

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24789

191
following information concerning the injection and confining zone(s): 

Response: The text at §146.87(d) as written requires data on the injection zone and confining zone or 

zones. This is to ensure that, if the Director requires characterization of additional 

containment/confining zones (§146.83(b)), appropriate data are collected. 

Other EPA Comment Codes and Descriptions: 4110 2.4.1.1 Injection pressure limitations 

Comment: (a) Except during stimulation, the owner or operator must ensure that injection 

pressure does not exceed 90% of the fracture pressure of the injection zone so 

as to assure that the injection does not initiate new fractures or propagate 

existing fractures in the injection zone. In no case may injection pressure 

initiate fractures in the confining zone(s) or cause the movement of 

injection or formation fluids that endangers a USDW. 

Response: EPA disagrees with the suggested edit. The rule affords the Director discretion to require 

more than one confining zone, as specified at §146.83(a)(2). Where more than one confining zone is 

required, EPA believes that each confining zone provides a layer of protection for USDWs and should 

remain intact. See the preamble discussion geologic siting requirements for additional information. 

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells 

(seeking comment) 

Comment: (e) The owner or operator must install and use continuous recording devices to 

monitor: The injection pressure; the rate, volume, and temperature of the 

carbon dioxide stream; and the pressure on the annulus between the tubing and 

the long string casing and annulus fluid volume; and must install and use alarms 

and automatic down-hole shut-off systems, designed to alert the operator and 

shut-in the well when operating parameters such as annulus pressure, injection 

rate or other parameters approved by the Director diverge beyond permitted 

ranges and/or gradients specified in the permit; 

{RRC suggests that the rule not require automatic shutdown. Experience in the 

field has been that ESDs are notorious for high maintenance, and continuous 

monitoring will sufficiently alert the operator of a need to shut down 

operations. In addition, such a requirement is more stringent than that 

required for Class I hazardous waste wells.} 

Response: After evaluating the risks and benefits of down-hole shut-off systems and considering 

additional research, EPA will not require automatic down-hole shut-off devices for onshore Class VI 

wells since it is not necessary in all cases to ensure protection of USDWs from endangerment. Instead, 

the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells install 

automatic surface shut-off devices. The rule affords Director's discretion to mandate automatic downhole shut-off devices in onshore situations that may warrant their use. The rule requires, at §146.88(e)(3) 

that owners or operators of offshore wells within State territorial waters install automatic down-hole 

shut-off systems. 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24790

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24791

192
EPA recognizes that down-hole shut-off devices may make well maintenance and operation more 

challenging. However, the buoyant nature of CO2 and the elevated injection pressures associated with 

GS increase the likelihood of an uncontrolled flow of CO2 out of the well, which may endanger 

USDWs. If CO2 does begin to flow back up an injection well, it will rapidly cool and expand as it 

moves toward the surface and can result in a stream of solid CO2 which can cause damage to the 

wellhead and other well instrumentation; such damage has been documented in CO2 ER wells (Skinner, 

2003; Duncan et al., 2008). Additionally, the Agency believes that offshore Class VI wells present 

unique construction and operational conditions, including isolation from shorelines and the need to 

construct wells through the water column and the subsurface, which may delay response time in the 

event of well difficulties. Automatic shut-off devices can help prevent further well complications, and 

EPA believes affording Director's discretion to require down-hole devices where necessary ensures that 

proper precautions are taken to prevent subsurface fluid movement and ensure protection of USDWs, 

human health, and the environment. 

EPA believes that requiring automatic surface shut-off devices instead of down-hole devices provides 

more flexibility to owners or operators when performing required mechanical integrity tests. 

Additionally, this requirement addresses concerns about risks associated with routine well workovers 

that may be complicated by the presence of down-hole devices while still maintaining USDW 

protection. 

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells 

(seeking comment) 

Comment: (f) If a down-hole automatic shutdown is triggered or a loss of mechanical 

integrity is discovered, the owner or operator must immediately investigate and 

identify as expeditiously as possible the cause of the shutoff. If, upon 

such investigation, the well appears to be lacking mechanical integrity, or if 

monitoring required under paragraph (e) of this section otherwise indicates that 

the well may be lacking mechanical integrity, the owner or operator must: 

Response: As described above, after evaluating the risks and benefits of down-hole shut-off systems 

and considering additional research, EPA will not require automatic down-hole shut-off devices for 

onshore Class VI wells since it is not necessary in all cases to ensure protection of USDWs from 

endangerment. Instead, the final rule, at §146.88(e)(2), affords Director's discretion to mandate 

automatic down-hole shut-off devices in onshore situations that may warrant their use. However, the 

Agency believes that offshore Class VI wells present unique construction and operational conditions, 

including isolation from shorelines and the need to construct wells through the water column and the 

subsurface, which may delay response time in the event of well difficulties. The rule requires, at §146.88

(e)(3), that owners or operators of offshore wells within State territorial waters install automatic downhole shut-off systems. 

Other EPA Comment Codes and Descriptions: 4520 2.5.1 Continuous internal mechanical integrity 

monitoring (seeking comment); 4720 2.7.2 Operational recordkeeping and reporting 

Comment: (b) To evaluate the absence of significant leaks under paragraph (a)(1) of 

this section, owners or operators must, following an initial annulus pressure 

test, continuously monitor injection pressure, rate, injected volumes, and 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24792

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24793

193
pressure on the annulus between tubing and long stem casing and annulus fluid 

volume as specified in §146.88(e); 

{Redundant language.} 

Response: The final rule retains this text to provide clarity about requirements for demonstrating 

internal mechanical integrity and to specify the necessary monitoring. EPA believes that continuous 

pressure monitoring to demonstrate internal mechanical integrity of Class VI wells (146.89(b)), instead 

of periodic testing (which is required for most other types of deep injection wells) is important given the 

potential corrosive impact of CO2 and impurities on well materials, the potential geomechanical impacts 

to well integrity due to CO2 phase changes, and the temperature and pressure effects associated with 

injecting supercritical CO2. 

For additional information, please see the discussion of MITs in the final rule preamble. 

Other EPA Comment Codes and Descriptions: 4660 2.6.6 Geochemical monitoring 

Comment: (d) Periodic monitoring of the ground water quality and geochemical changes 

above the confining zone(s) that may be a result of carbon dioxide movement 

through the confining zone or additional identified zones: 

Response: Regarding monitoring locations, section §146.90(d) requires periodic monitoring of the 

ground water quality and geochemical changes above the confining zone(s). EPA clarifies that this 

monitoring requirement does not include the confining layer itself. Monitoring above the confining layer 

will provide an indication of upward movement of CO2 that might endanger a USDW. The exact 

number of formations to be tested must, however, be based on site-specific characteristics and 

vulnerabilities and described in the Director-approved testing and monitoring plan. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: (e) A demonstration of external mechanical integrity pursuant to §146.89(c) at 

least once per year throughout the duration of INJECTION the geologic 

sequestration project; 

{Demonstration of external mechanical integrity should not be necessary after 

cessation of injection and (relatively immediate) dissipation of pressure near 

the wellbore resulting from injection.} 

Response: In the final rule, EPA has revised the text at §144.90(e) to specify that owners or operators 

must demonstrate internal MI at least once per year until the well is plugged. 

Other EPA Comment Codes and Descriptions: 4650 2.6.5 CO2 plume and pressure front tracking 

(seeking comment) 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24794

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24795

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24796

194
Comment: (g) Testing and monitoring to track the extent of the carbon dioxide plume and 

the position of the pressure front by either monitoring for pressure changes 

in the first formation overlying the confining zone or using indirect, 

geophysical techniques (e.g., seismic, electrical, gravity, or electromagnetic 

surveys and/or down-hole CO2 detection tools); 

{If there are changes in the first formation overlying the confining 

zone, the carbon dioxide stream has not been confined.} 

Response: The final rule, at §146.90(g), requires owners or operators to perform monitoring to track the 

extent of the CO2 plume and pressure front. The owner or operator must use direct methods to monitor 

for pressure changes in the injection zone. Indirect methods (e.g., seismic, electrical, gravity, or 

electromagnetic surveys and/or down-hole CO2 detection tools) are required unless the Director 

determines, based on site-specific geology that such methods are not appropriate 

EPA believes that pressure monitoring in the injection zone is necessary to track the development and 

movement of the pressure front and CO2 plume. When combined with information on temperature, 

pressure data provide an indication of the phase (e.g., gas, supercritical) and distribution of the injected 

CO2 (73 FR 43515). Monitoring can also identify needed remedial actions, provide inputs for AoR 

reevaluation modeling, evaluate predictions of plume movement, and target additional geochemical and 

surface monitoring needs. 

EPA adds that owners or operators may consider (or the Director may require) performing additional 

pressure monitoring in wells that are above the confining zone (e.g., in the same wells used to perform 

ground water quality monitoring required at §146.90(d)) to provide additional verification that no 

pressure changes are occurring above the confining zone due to CO2 leakage. The final rule, at §146.90

(d), also requires geochemical monitoring above the confining zone. 

Other EPA Comment Codes and Descriptions: 4670 2.6.7 Surface air monitoring and/or soil gas 

monitoring (seeking comment) 

Comment: (h) At the Director's discretion, surface air monitoring and/or soil gas 

monitoring to detect movement of carbon dioxide that could endanger a USDW. (1) 

The testing and monitoring plan must be based on potential vulnerabilities 

within the area of review; (2) The monitoring frequency and spatial distribution 

of surface air monitoring and/or soil gas monitoring must reflect baseline data 

and the monitoring plan must include how the proposed monitoring will yield 

useful information on the area of review delineation and/or compliance with 

standards under 40 CFR 144.12; 

{Any requirement for surface air monitoring and/or soil gas monitoring is not 

warranted. If the purpose is to detect "movement of carbon dioxide that could 

endanger a USDW, it would be too late if carbon dioxide were detected in the air 

or soil. In addition, levels of ambient carbon dioxide are too variable for 

this to be useful. RRC suggests eliminating any potential requirement for 

surface air or soil gas monitoring, because formation monitoring should catch 

whatever condition might reasonably be expected to be caught by surface or soil 

gas monitoring. } 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24797

195
Response: EPA acknowledges that air and soil gas monitoring to ensure USDW protection is not 

necessary at all GS sites and believes that the decision to use surface monitoring and the selection of 

monitoring methods for the purpose of USDW protection will be site-specific. In the final rule, at 

§146.90(h), the decision to require such monitoring as an additional measure to ensure USDW 

protection rests with the Director as a means of identifying leaks that may pose a risk to USDWs and 

informing emergency notification of a Class VI owner or operator and UIC Director in the event of a 

USDW endangerment, pursuant to requirements at §146.91(c). 

EPA clarifies that subsurface geochemical and pressure monitoring in the subsurface formations are the 

first line of monitoring that would allow detection of potential endangerment to USDWs from GS 

activities (this is required at all GS sites, as described at §146.90(d)). The Agency also believes that 

surface air and soil gas monitoring, when coupled with subsurface monitoring, may be appropriate at 

some GS projects to ensure USDW protection. EPA acknowledges that surface air and soil gas 

monitoring may not be suitable in all settings as a method to ensure USDW protection. However, EPA 

does not believe that this should entirely preclude their use. The decision to use surface monitoring and 

the selection of monitoring methods will be site-specific (e.g., may be influenced by geology, injection 

depth, and operational conditions) and must be based on potential risks to USDWs within the AoR. 

Other EPA Comment Codes and Descriptions: 5220 2.8.2.1 Post-injection monitoring activities 

Comment: (1) The owner or operator must submit the post-injection site care and site 

closure plan as a part of the permit application to be approved by the 

Director. 

{Redundant - See 146.82(w).} 

Response: EPA clarifies that the reference to the post-injection site care and site closure plan, in the 

final rule at §146.82(a)(17), requires that the plan be included in the attachments to the Class VI permit 

application. The details of the plan contents are included in §146.93, along with other requirements 

related to post-injection site care and site closure. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: (i) The pressure differential between pre-injection and predicted post-injection 

pressures in the injection zone; (ii) The predicted position of the carbon 

dioxide plume and associated pressure front at site closure as demonstrated in 

the AOR evaluation required under §146.84(b); (iii) A description of postinjection monitoring location, methods, and proposed frequency; and (iv) A 

proposed schedule for submitting post-injection site care monitoring results to 

the Director. 

{This should be referenced in 146.82(w).} 

Response: EPA clarifies that the reference to the post-injection site care and site closure plan, in the 

final rule at §146.82(a)(17), is to require that the plan be included in the attachments to the Class VI 

permit application. The details of the plan contents are included in §146.93 and are enforceable permit 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24798

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24799

196
conditions, along with other requirements related to post-injection site care and site closure. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: (3) Upon cessation of injection, THE OWNER OR OPERATOR MUST either submit an 

amended post-injection site care and site closure plan or demonstrate to the 

Director through monitoring data and modeling results that no amendment to the 

plan is needed. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Comment: (4) THE OWNER OR OPERATOR MAY May modify and resubmit the post-injection 

site care and site closure plan for the Director's approval within 30 days of 

such change. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 5220 2.8.2.1 Post-injection monitoring activities; 

5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: (b) THE OWNER OR OPERATOR MUST Must monitor the site following the cessation 

of injection to show the position of the carbon dioxide plume and pressure front 

and demonstrate that USDWs are not being endangered. 

(1) THE OWNER OR OPERATOR MUST Must continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site closure 

plan for THE PERIOD OF TIME at least 50 years following the cessation of 

injection . At the Director's discretion, the monitoring will continue until 

THE DIRECTOR DETERMINES THAT the geologic sequestration project no longer poses 

an endangerment to USDWs. 

Response: EPA disagrees with the suggested edits. However, EPA agrees with commenters that there 

will be circumstances where it can be demonstrated in less than 50 years that the plume and pressure 

front no longer pose a risk of endangerment to USDWs. For this reason, the final GS rule offers owners 

or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director 

discretion to shorten or lengthen the PISC timeframe during the PISC period based on site-specific data, 

pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24800

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24801

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24802

197
owner or operator to demonstrate, based on substantial data during the permitting process, that an 

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to 

requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

Other EPA Comment Codes and Descriptions: 5280 2.8.2.4 USDW non-endangerment 

demonstrations 

Comment: (3) Prior to authorization for site closure, must submit to the Director a 

demonstration, based on monitoring and other site-specific data, that the 

carbon dioxide plume and pressure front have stabilized and that no 

additional monitoring is needed to assure that the GS project does not pose an 

endangerment to USDWs. 

{The carbon dioxide plume will continue to move with other formation fluids - 

they are never static. The real test should be whether or not the pressure has 

dissipated and the pressure front stabilized to the point that there is no 

threat of endangering USDWs.} 

Response: EPA did not make the suggested change. EPA agrees that a complete cessation of plume 

movement may not occur at some sites for long time periods due to density differences, natural 

formation flow gradients and diffusion. EPA clarifies that a complete cessation of plume movement is 

not required, only a demonstration that the plume and pressure front no longer pose a risk of 

endangerment to USDWs. 

EPA acknowledges that many site-specific factors will influence the determination of when the CO2 

plume and pressure front no longer pose a risk of endangerment to USDWs. It is for this reason that 

EPA believes that individual UIC Directors, in consultation with operators, will be in the best position to 

determine whether additional post-injection site care is needed. EPA expects this decision to be made 

based on relevant site data and in consultation with all potentially impacted parties. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will assist 

Directors in evaluating proposed well plugging plans and post-injection site care and site closure plans 

under §146.92 and §146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells; perform post-injection monitoring; demonstrate non 

endangerment; and perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24803

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24804

198
Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment); 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: (4) If such a demonstration cannot be made after the 50-year period, must 

submit to the Director a plan to continue post-injection site care. 

{See comment above.} 

Response: As described above, the post-injection site care timeframe may be reduced by the Director if 

the owner or operator can demonstrate that the remaining pressure front and plume no longer pose a risk 

of endangerment to USDWs. The non-endangerment finding is left to the discretion of the Director, 

based on site-specific information such as plume movement, pressure decay, and the location of 

potential leakage pathways. As suggested by the commenter, a complete cessation of plume movement 

is not required, only a demonstration that the plume and pressure front no longer pose a risk of 

endangerment to USDWs, as specified in §146.93(b)(2-4). EPA retains this provision in the final GS 

regulation 

GS rule also offers owners or operators flexibility regarding the duration of the PISC timeframe by 

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, based on 

substantial data during the permitting process, that an alternative PISC timeframe may be appropriate if 

it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care 

Comment: (c) Notice of intent for site closure. Must notify the Director at least 120 

days before site closure. At this time, if any changes have been made to the 

original post-injection site care and site closure plan, THE OWNER OR OPERATOR 

must also provide the revised plan. At the discretion of the Director, a shorter 

notice period may be allowed. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS Rule. See the final rule and 

discussion of post-injection site care in the preamble to the rule for further discussion on EPA's final 

approach. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: (d) After the Director has authorized site closure, THE OWNER OR OPERATOR must 

plug all monitoring wells in a manner which will not allow movement of injection 

or formation fluids that endangers a USDW. 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24805

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24806

199
Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: (e) Once the Director has authorized site closure, THE OWNER OR OPERATOR must 

submit a site closure report within 90 days that must thereafter be retained at 

a location designated by the Director. The report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. Must provide a copy of 

a survey plat which has been submitted to the local zoning authority designated 

by the Director, which indicates the location of the injection well relative to 

permanently surveyed benchmarks. Must also submit a copy of the plat to the 

regional administrator of the appropriate EPA Regional Office; 

{Why is this necessary? The EPA regional office will have access to all records 

at the State. } 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on the 

deed to the facility property or other similar document examined during a title search that the land has 

been used to sequester CO2 at the time of site closure. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: (f) THE OWNER OR OPERATOR MUSTMust record a notation on the deed to the 

facility property or any other document that is normally examined during title 

search that will in perpetuity provide any potential purchaser of the property 

the following information: 

(1) The fact that land has been used to sequester carbon dioxide; 

(2) The name of the State agency, local authority, and/or tribe with which the 

survey plat was filed, as well as the address of the Regional EPA Office to 

which it was submitted; and (3) The volume of fluid injected, the injection 

zone or zones into which it was injected, and the period over which 

injection occurred. 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation that the 

land has been used to sequester CO2 on the deed to the facility property at the time of site closure. 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24807

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24808

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24809

200
Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: (g) Must retain for three years following site closure, records collected during 

the post-injection site care period. THE OWNER OR OPERATOR MUST Must 

deliver the records to the Director at the conclusion of the retention period, 

and the records must thereafter be retained at a location designated by the 

Director for that purpose. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention such 

as site closure reports. EPA believes that the requirements that the owner or operator retain for ten years 

following site closure, records collected during the post-injection site care period at §146.93(f) and 

§146.93(h) are appropriate for the post-injection and site closure period to ensure that data are available 

to support non-endangerment demonstrations and to address any concerns that may arise following site 

closure. This data will also support EPA's review of project data as part of the adaptive rulemaking 

approach. 

Other EPA Comment Codes and Descriptions: 5000 2.8 Proposed Well Plugging and Post-Injection 

Site Care Requirements 

Comment: §146.94 Emergency and remedial response. 

(a) As part of the permit application, THE OWNER OR OPERATOR must provide the 

Director with an emergency and remedial response plan that describes actions to 

be taken to address movement of the injection or formation fluids that may cause 

an endangerment to a USDW during construction, operation, closure and postclosure periods. 

{Redundant - See 146.82(X)} 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 5220 2.8.2.1 Post-injection monitoring activities; 

5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: (2) If the owner or operator can demonstrate to the satisfaction of the 

Director before 50 years, based on monitoring and other site-specific data, that 

the GS project no longer poses an endangerment to USDWs, the Director may 

approve an amendment to the post-injection site care and site closure plan to 

reduce the frequency of monitoring or may authorize site closure before the end 

of the 50-year period. 

{The period of time an owner or operator is required to conduct post-closure 

care monitoring should be based on the ability of the pressure to cause 

endangerment of USDWs. A 50-year post-closure care monitoring period is 

unprecedented and implies that CO2 presents a greater risk than it does. RRC 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24810

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24974

201
suggests that EPA strike the phrase "for at least 50 years" and make the time 

for continued monitoring be based on site specific data. } 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most 

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a review 

of research studies, industry reports, and existing environmental programs. This analysis was included in 

an EPA-prepared background document that is available in the federal docket, titled "Computational 

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and 

Potential Risk to Underground Sources of Drinking Water." EPA assessed various default timeframes 

based on additional review of research studies and evaluation of public comments. While numerous 

commenters suggested that EPA shorten the monitoring timeframe, none of the commenters provided 

sufficient data or other evidence to warrant a change in the proposed timeframe. While the 10- or 30-

year timeframe suggested by some of these commenters may be within the timeframe suggested in some 

studies, EPA believes that the potential risks of endangering USDWs will likely not decline within these 

timeframes and available data, including data submitted by commenters, do not support a different 

default timeframe. However, EPA recognizes that alternative timeframes may be appropriate under 

limited, specific circumstances, which is why EPA is providing the Director discretion to approve an 

alternative post-injection site care timeframe as long as the owner or operator can meet the requirements 

provided at §146.93(c). 

EPA acknowledges there will be circumstances where it can be demonstrated in less than 50 years that 

the plume and pressure front no longer pose a risk of endangerment to USDWs. For this reason, the GS 

rule offers owners or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing 

the Director discretion to shorten or lengthen the PISC timeframe during the post-injection period based 

on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to 

allow a Class VI well owner or operator to demonstrate, during the permitting process based on 

substantial data, that an alternative PISC timeframe may be appropriate if it ensures non-endangerment 

of USDWs pursuant to requirements at §146.93(c). 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for 

post-injection site care will be necessary in most cases. The default 50 year post-injection site care 

timeframe represents a reasonable and protective monitoring period based on a review of research 

studies, industry reports, and existing environmental programs, and evaluation of public comments. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

Comment: Technical Fix to the GS Rule to Properly Include Indian Tribes 

Finally, in reading the GS rule, the NTAA found that the EPA inadvertently 

omitted the phrase "tribal authorities" under section 146.94(c)(2). To rectify 

this omission from the section, the NTAA recommends the following language: 

Commenter Name: Sam Kitto Letter ID: 0126

Commenter Organization: National Tribal Air Association Comment ID: 23051

202
"Documentation of appropriate notification and information to such State, 

Tribal, and local authorities as have authority over drilling activities to 

enable such State, Tribal and local authorities to impose appropriate conditions 

on subsequent drilling activities that may penetrate the injection and confining 

zone(s)." 

Response: EPA presumes the commenter is referring to the final rule requirement at §146.93(f)(2). EPA 

clarifies that the text reads as follows, "Documentation of appropriate notification and information to 

such State, local and Tribal authorities as have authority over drilling activities to enable such State, 

local, and Tribal authorities to impose appropriate conditions on subsequent drilling activities that may 

penetrate the injection and confining zone(s)." 

For additional information on EPA's final regulatory approach, please see the final rule and preamble as 

well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: Fluid Movement 

The UIC regulations have, from the beginning, included two standards of 

prohibition of fluid movement that may be appropriate for geological 

sequestration of carbon dioxide. The fluid movement requirement for Class I 

injection wells states: 

The well must be constructed, operated, maintained, and plugged such 

that injection activities will not cause movement of any contaminant 

into a USDW 

The fluid movement requirement for Class V injection wells states: 

No owner or operator shall construct, operate, maintain, convert, plug, 

abandon, or conduct any other injection activity in a manner that allows 

the movement of fluid containing any contaminant into underground 

sources of drinking water, if the presence of that contaminant may cause 

a violation of any primary drinking water regulation under 40 CFR part 

142 or may otherwise adversely affect the health of persons. The 

applicant for a permit shall have the burden of showing that the 

requirements of this paragraph are met. 

The NGWA recommendation for carbon sequestration well permitting includes an 

experimental phase for each location that will be used for geological 

sequestration of carbon dioxide. Wells constructed during the experimental 

phase at each location will have extensive testing requirements and exploratory 

objectives that will not be needed during the operational phase. It will not be 

necessary or practical to apply the same standard of fluid movement to both the 

experimental phase and the operational phase of carbon sequestration. 

The NGWA recommendations also include early warning monitoring to detect 

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22553

203
movement of fluids containing carbon dioxide or contaminants before the fluids 

reach a USDW. The advantage of early warning monitoring is in the ability to 

detect fluid movement before a drinking water supply is impacted. The 

identification of a geological unit that can serve as secondary containment for 

the injected fluid is addressed in the NGWA recommendations for geologic 

characterization. It is recommended that early warning monitoring be included 

in the requirements for operation of Class V experimental carbon sequestration 

wells, as well as Class VI operational carbon sequestration wells. The 

requirement for early warning monitoring should include authorization for action 

by the regulatory agency when fluid movement is detected by the early warning 

monitoring system. 

Class V Experimental Carbon Sequestration Well: During the experimental phase 

of injection, while the well is permitted as a Class V well, the following fluid 

movement criterion should apply: 

No owner or operator shall construct, operate, maintain, convert, plug, 

abandon, or conduct any other injection activity in a manner that allows 

the movement of fluid containing carbon dioxide or any contaminant into 

underground sources of drinking water, if the presence of carbon dioxide 

or that contaminant may cause a violation of any primary drinking water 

regulation under 40 CFR part 142 or may otherwise adversely affect the 

health of persons. The applicant for a permit shall have the burden of 

showing that the requirements of this paragraph are met. 

Class VI Operational Carbon Sequestration Well: During the operational phase of 

injection, while the well is permitted as a Class VI well, the following fluid 

movement criterion should apply: 

No owner or operator shall construct, operate, maintain, convert, plug, 

abandon, or conduct any other injection activity in a manner that allows 

the movement of fluid containing carbon dioxide or any contaminant into 

underground sources of drinking water, if the presence of carbon dioxide 

or that contaminant may cause a violation of any primary drinking water 

regulation under 40 CFR part 142 or may otherwise adversely affect the 

health of persons. Additionally, no owner or operator shall construct, 

operate, maintain, convert, plug, abandon, or conduct any other 

injection activity in a manner that allows the movement of carbon 

dioxide in gaseous phase to land surface, nor limit the extraction of 

drinking water from a underground sources of drinking water by reduction 

of porosity or changes in pH or water quality due to geochemical 

reactions, or by causing a buildup of gas in the underground sources of 

drinking water. The applicant for a permit shall have the burden of 

showing that the requirements of this paragraph are met. 

If any water quality monitoring of an underground source of drinking 

water indicates the movement of any contaminant into the underground 

source of drinking water, or a violation of any part of the preceding 

paragraph, except as authorized under part 146, the Director shall 

publish a notice in newspapers of general circulation in whose service 

area the fluid movement was detected. If a meritorious request is 

204
submitted by the public, the Director shall prescribe such additional 

requirements for construction, corrective action, operation, monitoring, 

or reporting (including closure of the injection well) as are necessary 

to prevent such movement. 

Response: EPA does not agree that each GS site must first be permitted as an experimental Class V well 

before being authorized to operate a full-scale Class VI well. Following the promulgation of the final 

rule, EPA will allow the use of Class V experimental technology permits only for experimental 

purposes; i.e., to test new, unproven technologies. EPA does not consider it appropriate to permit CO2 

injection wells that are testing the injectivity or appropriateness of an individual formation (e.g., as a 

prelude to a commercial-scale operation) as Class V experimental technology wells. Such wells should 

be permitted as Class VI wells. 

The final rule at §146.90(g) requires owners or operators to track the extent of the CO2 plume and 

pressure front. The owner or operator must use direct methods to monitor for pressure changes in the 

injection zone. Indirect methods (e.g., seismic, electrical, gravity, or electromagnetic surveys and/or 

down-hole CO2 detection tools) are required unless the Director determines, based on site-specific 

geology, that such methods are not appropriate. 

EPA believes that pressure monitoring in the injection zone is necessary to track the development and 

movement of the pressure front and CO2 plume. Monitoring can also identify needed remedial actions, 

provide inputs for AoR reevaluation modeling, evaluate predictions of plume movement, and target 

additional geochemical and surface monitoring needs. Knowledge of the location of the CO2 plume and 

the associated pressure front will also assure the public that GS projects are proceeding according to 

plan, provide sufficient information to the owner or operator and Director, or allow for appropriate 

actions to address any indication that USDWs may be endangered. 

In addition to monitoring to track the movement of the CO2 plume and pressure front, EPA believes that 

monitoring above the confining layer is an important part of a rigorous monitoring program and can help 

detect potential breaches of the confining zone. Such monitoring can provide an early warning that the 

plume or other substances may be approaching a USDW. The final rule, at §146.90(d), requires periodic 

monitoring of the ground water quality and geochemical changes above the confining zone(s). 

Monitoring in additional formations, e.g., the injection zone, may also be necessary, and if the Director 

believes such monitoring is warranted he/she has the authority to require that it be included in the testing 

and monitoring plan. EPA adds that the baseline geochemical data required at §146.82(a)(6) will help 

owners or operators interpret the results of this monitoring. 

EPA acknowledges that there are potential risks associated with GS, including the potential for leakage 

of CO2 or other substances into USDWs. However, the purpose of the UIC regulations including the 

Class VI requirements is to protect USDWs from endangerment. In order to protect USDWs from 

endangerment §144.12 prohibits the movement of fluid into USDWs. Consistent with §144.12, EPA is 

finalizing the Class VI requirements in order to ensure that USDWs are protected by minimizing and 

mitigating potential/identified risks through proper site characterization, well construction, operation, 

monitoring, post-injection site care, and site closure. The GS rule accomplishes this through 

requirements tailored to address the unique nature of GS, including the large volumes of CO2 injected, 

its buoyancy and potential corrosivity in the presence of water, and impurities in the CO2 stream. 

Furthermore, if any water quality monitoring of a USDW indicates the movement of any contaminant 

into the underground source of drinking water, except as authorized under part §146, the Director shall 

prescribe such additional requirements for construction, corrective action, operation, monitoring, or 

reporting (including closure of the injection well) as are necessary to prevent such movement. 

205
Other EPA Comment Codes and Descriptions: 3440 2.2.2.2 Evaluation of wells in the AoR (e.g., 

types of data to be reviewed) 

Comment: Proposed Rule: 144.55(a) 

Proposed Revision: (a) Coverage. Applicants for Class I, II, (other than 

existing), III or VI injection well permits shall identify the location of all 

known wells within the injection well's area of review which penetrate the 

injection zone, or in the case of Class II wells operating over the fracture 

pressure of the injection formation, all known wells within the area of review 

penetrating formations affected by the increase in pressure. Applicants for 

Class VI shall perform mapping with sufficient resolution as to make a 

comprehensive effort to identify wells that are not in the public record using 

aerial photography, aerial survey, or other methods acceptable to the director 

corrective action as specified in §146.84 if needed 

Rationale: Concern about the use of the term known wells. Public records 

search may not be adequate for older oil and gas wells, for example. Some 

language should be added so that A more proactive approach is used, e.g. 

physically walk site or do aerial review. 

Response: The final rule leaves §144.55 unchanged from the existing UIC requirements; i.e., Class VI 

wells are not addressed in this provision. Based on its evaluation of all public comments and input on 

the proposed rule and NODA and Request for Comment, EPA has made many revisions to the GS Rule. 

See the final rule and preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: Proposed Rule: 146.82 

Comment: NGWA raises the question of whether a requirement should be included 

that all applications for Class VI construction permits include a certification 

that the facility was designed by an appropriately qualified professional 

engineer with an option for an appropriate qualified professional geologist to 

certify the well design (taking into consideration confinement, injectivity, 

etc). 

Proposed addition: (1) Class VI - Test/Injection Well Construction and Testing 

Permit 

Proposed addition: (a) The Director shall deny a construction permit if 

construction of the well itself may endanger the health of persons or the 

environment 

Proposed addition: (b) For construction permit approval, reasonable assurance is 

required that the project will function in compliance with this chapter. The 

Director shall require an exploratory well for those projects located in an area 

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22587

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22590

206
where available information is lacking concerning geologic or hydraulic 

confinement or existing information indicates that geologic or hydraulic 

confinement may be poor or lacking. 

Proposed addition: (c ) For a Class VI well, issuance of a construction permit 

does not obligate the Director to authorize any operation of the well, unless 

reasonable assurance has been provided that the well can operate in compliance 

with this chapter. 

Proposed addition: (d) Information required in 40 CFR 144.31 (e)(1) through (6) 

Proposed addition: (e) A map showing the injection well(s) for which a permit is 

sought and the applicable area of review. Within the area of review, the map 

must show the number, or name and location of all injection wells, producing 

wells, abandoned wells, plugged wells or dry holes, deep stratigraphic 

boreholes, State or EPA approved subsurface cleanup sites, surface bodies of 

water, springs, mines (surface and subsurface), quarries, water wells and other 

pertinent surface features including structures intended for human occupancy and 

roads. The map should also show faults, if known or suspected. Only information 

of public record is required to be included on this map; 

Proposed addition: (f) The area of review based on modeling, using data obtained 

during logging and testing of the well and the formation as required by 

paragraphs (l), (r ), and (s) of this section; 

Proposed addition: (g) Information on the geologic structure and hydrogeologic 

properties of the proposed storage site and overlying formations, including 

Proposed addition: (1) Maps and cross sections of the area of review; 

roposed addition: (2) Location, orientation, and properties of known or 

suspected faults and fractures that may transect the confining zone(s) in the 

area of review and a determination that they would not interfere with 

containment; 

Proposed addition: (3) Information on seismic history including the presence and 

depth of seismic sources and a determination that the seismicity would not 

interfere with containment; 

Proposed addition: (4) Data on the depth, areal extent, thickness, mineralogy, 

porosity, permeability and capillary pressure of the injection and confining 

zone(s); including geology/facies changes based on field data which may include 

geologic cores, outcrop data, seismic surveys, well logs, and names and 

lithologic descriptions; 

Proposed addition: (5) Geomechanical information on fractures, stress, 

ductility, rock strength, and in situ fluid pressures within the confining zone; 

and 

Proposed addition: (6) Geologic and topographic maps and cross sections 

illustrating regional geology, hydrogeology, and the geologic structure of the 

207
local area 

Proposed addition: (h) All wells within the AOR and whose total depth is greater 

than the depth to the bottom of the lowermost USDW should be compiled. However, 

preventive corrective action should be undertaken only for those wells that 

penetrate the injection and confining zone(s) 

Rationale: A substantive risk analysis can be performed only if all the (known) 

wells within the AOR and between the injection formation and the bottom of the 

USDW are described. 

Proposed addition: (i) Maps and stratigraphic cross sections indicating the 

general vertical and lateral limits of all USDWs, water wells and springs within 

the area of review, their positions relative to the injection zone(s) and the 

direction of water movement, where known; 

Proposed addition: (j) Baseline geochemical data on subsurface formations, 

including all USDWs in the area of review; 

Proposed addition: (k) Proposed operating data: 

Proposed addition: (1) Average and maximum daily rate and volume of the carbon 

dioxide stream; 

Proposed addition: (2) Average and maximum injection pressure; 

Proposed addition: (3) The source of the carbon dioxide stream; and 

Proposed addition: (4) An analysis of the chemical and physical characteristics 

of the carbon dioxide stream; 

Proposed addition: (l) The compatibility of the carbon dioxide stream with 

fluids in the injection zone and minerals in both the injection and the 

confining zone(s), based on the results of the formation testing program, and 

with the materials used to construct the well; 

Proposed addition: (m) Proposed formation testing program to obtain an analysis 

of the chemical and physical characteristics of the injection zone and confining 

zone; 

Proposed addition: (n) Proposed stimulation program and a determination that 

stimulation will not interfere with containment; 

Proposed addition: (o) Proposed formation testing program to obtain an analysis 

of the chemical, physical and radiological characteristics of and other 

information on the injection zone. 

Proposed addition: (p) Proposed procedure to outline steps necessary to conduct 

injection operation; 

Proposed addition: (q) Engineering drawings of the surface and subsurface 

208
construction details of the system, including design features for surge control 

and water hammer protection; 

Proposed addition: (r ) Injection well construction procedures that meet the 

requirements of Section 146.86; 

Proposed addition: (s) Proposed area of review and corrective action plan that 

meets the requirements under Section 146.84; 

Proposed addition: (t) The status of corrective action on wells in the area of 

review; 

Proposed addition: (u) A demonstration, satisfactory to the Director, that the 

applicant has met the financial responsibility requirements under Section 

146.85; 

Proposed addition: (v) Proposed testing and monitoring plan required by Section 

146.90 

Proposed addition: (w) Proposed injection well plugging plan required by Section 

146.92(b) 

Proposed addition: (x) Proposed post-injection site care and site closure plan 

required by Section 146.93(a) 

Proposed addition: (y) Proposed emergency and remedial response plan required by 

Section 146.94; and 

Proposed addition: (z) Any other information requested by the Director. 

Proposed addition: (2) Required Class VI operation permit information 

Proposed Rule: 146.82(a) & (b) 

Revision or Comment: Renumber 2(a) & (b) 

Proposed Rule: 146.82(d) - (h) 

Revision or Comment: Renumber 2(d) - 2(h) 

Proposed Rule: 146.82(h) 

Proposed addition: (5) Contingency plans to cope with all shut-ins or well 

failures, including emergency discharge provisions; 

No rationale provided 

Proposed Rule: 146.82(i) 

Revision or Comment: Renumber 2(i) 

209
Proposed Rule: 146.82(j) 

Proposed revision: 2(j) Results of the formation testing program to obtain an 

analysis of the chemical, physical and radiological characteristics of and other 

information on the injection zone. 

No rationale provided 

Proposed Rule: 146.82(k) - (m) 

Revision or Comment: Renumber 2(k) - 2(m) 

No rationale provided 

Proposed Rule: 146.82(n) 

Proposed revision: 2 (n) Engineering drawings of the surface and subsurface 

construction details of the system, including design features for surge control 

and water hammer protection, including the following: 

Proposed addition: (1) Record drawings, based upon inspections by the engineer 

of record or persons under his direct supervision, with all deviations noted; 

Proposed addition: (2) Copies of the mill certificates of all casings used in 

the construction of the well; 

Proposed addition: (3) Certification of completion submitted by the engineer of 

record; 

Proposed addition: (4) An operation manual including emergency procedures; 

Proposed addition: (5) Proposed monitoring program and data to be submitted; 

Proposed addition: (6) Proof that the existence of the well and any associated 

monitoring wells have been recorded with the permanent warranty deed or other 

instrument of conveyance as a two page proviso or addendum that contains 

certification of the locations of the wells (by metes and bounds) and a detailed 

sketch of the parcel that shows the location of the well. The location shall be 

measured by a certified land surveyor, and shall contain the surveyor's 

signature, registration number, official seal, and the following statement: "I 

hereby certify that this survey was made under my responsible direction and 

supervision, and is a correct representation of the land surveyed." 

No rationale provided 

Proposed Rule: 146.82(o) - (y) 

Revision or Comment: Renumber 2(o) - (y) 

Proposed Rule: 146.82 

210
Proposed addition: (3) Operational Testing 

Proposed addition: (a) For Class VI wells, the construction permit includes a 

period of temporary injection operation for the purposes of long term testing. 

Prior to commencement of operational testing: 

Proposed addition: 1. Construction of the injection well shall be complete and 

the permittee shall submit a notice of completion of construction to the 

Director. 

Proposed addition: 2. Each well shall first be tested for integrity of 

construction, and shall be followed by a short term injection test of such 

duration to allow for the prediction of the operating pressure. 

Proposed addition: 3. The permittee shall submit the following information to 

the Director, as described in the permit. 

Proposed addition: a. A copy of the borehole television survey(s) 

Proposed addition: b. Geophysical logs, 

Proposed addition: c. Mechanical integrity test data, 

Proposed addition: d. Data obtained during the short term injection testing 

conducted according to subparagraph 2. above. 

Proposed addition: e. Confining zone data, 

Proposed addition: f. Background water quality data for the injection and 

monitor zones; 

Proposed addition: g. Waste stream analysis, 

Proposed addition: h. As-built well construction specifications, and 

Proposed addition: i. Other data obtained during well construction which 

demonstrates that the well will operate in compliance with this chapter. 

Proposed addition: 4. Any corrective action required under Section 146.84, shall 

be completed. 

Proposed addition: 5. Prior to granting approval for operational testing of a 

Class VI well, the Director shall consider the following information: 

Proposed addition: a. All available logging and testing program data on the 

well; 

Proposed addition: b. A demonstration of mechanical integrity 

Proposed addition: c. The anticipated maximum pressure and flow rate at which 

the permittee will operate; 

Proposed addition: d. The results of the formation testing program; 

Proposed addition: e. The actual injection procedure; 

Proposed addition: f. The compatibility of injected waste with fluids in the 

injection zone and minerals in both the injection zone and the confining zone; 

Proposed addition: g. The status of corrective action on defective wells in the 

area of review; and 

Proposed addition: (b) Written authorization for operational testing shall be 

obtained from the Director. Authorization shall be for up to two years or the 

expiration date of the construction permit, whichever is less, and is only 

211
renewable once as described in Section 146.91. The authorization shall specify 

the conditions under which operational testing is approved. The authorization 

shall include: 

Proposed addition: 1. Injection pressure limitation, 

Proposed addition: 2. Injection flow rate limitation, 

Proposed addition: 3. Injection well monitoring requirements, 

Proposed addition: 4. Effluent monitoring requirements, 

Proposed addition: 5. Weekly ground water sampling of monitor wells, 

Proposed addition: 6. Monthly specific injectivity testing, 

Proposed addition: 7. Reporting requirements, and 

Proposed addition: 8. An expiration date for the operational testing period not 

to exceed two years. 

Proposed addition: (c ) Before authorizing operational testing, the Director 

shall conduct an inspection of the facility to determine if the conditions of 

the permit have been met. 

Proposed addition: (d) A sampling frequency and reporting of less than once per 

month shall not be allowed. 

Proposed addition: (e) For Class VI wells, the duration of the operational 

testing period shall not exceed two years or the expiration date of the 

construction permit, whichever is less. If the Director has not issued an 

intent to issue an operation permit for the einjectionwell9s) by the end of the 

operational testing period, the permittee shall cease injection. 

Proposed addition: (f) For a Class VI well, if an operation permit has not been 

obtained for the well within two years after the cessation of operational 

testing, the permittee shall submit an application to the Director to plug and 

abandon the well in accordance with Section 146.92. 

Proposed addition: (4) The Director shall conduct periodic inspections during 

construction 

No rationale provided 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS Rule. Please see the final rule and 

the discussion of geologic site characterization in the preamble for additional information. 

EPA clarifies that the final rule does not require an owner or operator to obtain a separate Class VI 

operational testing permit. However, EPA revised §146.82 so that the final regulation specifies separate 

requirements for information to be submitted with the permit application and before well construction is 

approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at 

§146.82(c)). Final information on injection zone pressures are required following drilling of the well, at 

§146.82(c)(4). 

EPA disagrees that the rule needs to specify the qualifications of owner or operator staff creating the 

permit submittals. EPA is developing a number of technical guidances and implementation materials to 

assist owners or operators and Directors in the permitting process. These guidances will provide 

212
suggestions on how to perform many of the activities necessary for applying for a permit, including 

developing all required plans and conducting site characterizations under §146.82. Technical guidances 

and implementation materials will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3560 2.2.3.2 Conditions that merit reevaluation of the 

AoR (seeking comment); 4710 2.7.1 Proposed submissions required for permit applications (seeking 

comment) 

Comment: Proposed Rule: 146.82(c) 

Revision or Comment: Proposed Revision: 2(c ) Re-evaluation of Area of Review. 

After completion of the operational testing period, the Area of Review shall be 

re-evaluated, using a calibrated, multi-phase fluid flow model. The data 

collection during operational testing must be adequate for calibration of the 

model. If a calibrated model cannot be prepared using data collected during 

operational testing, the owner or operator shall apply for a new period of 

operational testing of up to two years in order to collect the required data. 

No rationale provided 

Response: EPA agrees that AoR reevaluations should be based on the same type of modeling that is 

used to perform the initial delineation, but disagrees that the suggested change is necessary. EPA 

clarifies that all AoR modeling (including that which supports reevaluations) should be based on 

accepted, verified, and validated scientific methods. Under requirements at §146.84(b), the owner or 

operator must demonstrate in the proposed AoR and corrective action plan, to the satisfaction of the 

Director that the modeled AoR (and all updates) will be based on detailed geologic data collected on the 

site. EPA anticipates that any model that does this in a comprehensive and satisfactory manner would be 

approved by the Director. 

Other EPA Comment Codes and Descriptions: 3120 2.1.2 Need to identify additional confining and 

containment zones (seeking comment) 

Comment: Proposed Rule: 146.83(b) 

Proposed revision: (b) Owners or operators of Class VI wells must identify and 

characterize additional zones, if they exist, that will impede vertical fluid 

movement, allow for pressure dissipation, and provide additional opportunities 

for monitoring, mitigation and remediation. Vertical faults and fractures that 

transect these zones must be identified. 

Rationale: While NGWA believes that a site with a single confining can provide 

storage integrity we feel that if there are additional confining layers at the 

site they should be characterized to get a better estimate of leakage risk to 

USDWs and possibly identify additional monitoring zones. 

Response: EPA agrees with the commenter that, in some situations, the presence of additional confining

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22591

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22592

213
and containment zones above the primary (i.e., lowermost) confining zone can improve USDW 

protection from endangerment. The final regulation retains the requirement at §146.83(b) which affords 

the Director discretion to require owners or operators to identify and characterize additional zones. Any 

additional confining zones would need to be included in the geologic site characterization process, 

which the owner or operator would submit and the Director would review in determining whether to 

grant a permit. EPA is developing guidance on site characterization for GS projects to assist owners or 

operators and Directors in evaluating permit requirements and applications under §146.82. The guidance 

provides recommendations regarding characterizing the regional geology and hydrogeology of a 

proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical 

analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in 

making an objective decision about requiring additional confining layers. The guidance can be found on 

EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3530 2.2.3.1 AoR reevaluation frequency (seeking 

comment) 

Comment: Proposed Rule: 146.84(b)(2)(i) 

Proposed revision: (i) The owner or operator will reevaluate the AOR after two 

yearsof operational testing (prior to issuance of the operating permit), and 

after 5 years and then no less frequently than every 5 years for the life of the 

project; 

Rationale: NGWA believes that a frequency of every 10 years is too long to 

identify early discrepancies between the site performance and the site model. 

Seeing early difference will allow for earlier model updating and provide 

additional reduction in leakage risk. 

Response: As described above, EPA agrees that reevaluations of the AoR every ten years may not be 

sufficient to ensure protection of USDWs from endangerment, and has changed the minimum frequency 

for the AoR reevaluation at §146.84(e) from 10 years to at least every 5 years in the final GS rule. 

In addition, the Director has discretion to require more frequent AoR reevaluation if he or she has reason 

to believe, based on site-specific information, that a five-year reevaluation schedule is not sufficiently 

protective of USDWs. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Proposed Rule: 146.84(c)(1)(i) 

Proposed revision: (i) Be based on detailed geologic data collected to 

characterize the injection zone, confining zone(s), transmissive monitoring 

zones and any additional zones; and anticipated operating data, including 

injection pressures, rates and total volumes over the proposed life of the 

geological sequestration project; 

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22593

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22595

214
Rationale: NGWA proposes that if there are secondary confining units that they 

should be included in the site model along with any transmissive zones between 

the primary and secondary confining units. 

Response: EPA agrees that additional confining and containment zones should be accounted for in the 

AoR delineation if site-specific circumstances indicate a need for this. 146.84 (c)(1)(i) specifies that 

computational modeling should be based on detailed geologic data collected to characterize the injection 

zone and confining zone, as well as any additional zones. 

Other EPA Comment Codes and Descriptions: 3440 2.2.2.2 Evaluation of wells in the AoR (e.g., 

types of data to be reviewed) 

Comment: Proposed Rule: 146.84(c)(2) 

Proposed revision: (2) Using methods approved by the Director, identify all 

penetrations, including active and abandoned wells and underground mines, in the 

area whose total depth is greater than the depth to the bottom of the lowermost 

USDW, including those penetrating the confining zone. Provide a description of 

each well’s type, construction, date drilled, location, depth, record of 

plugging and/or completion, and any additional information the Director may 

require; and 

Rationale: This makes this consistent with NGWA's proposed section 146(a)(8) 

Response: EPA clarifies that any well that penetrates the confining zone, even if it does not extend all 

the way through the confining formation, is to be included in the tabulation. EPA is issuing guidance on. 

The guidance describes EPA's recommended approaches for the data to be considered in an initial AoR 

delineation, how to apply computational modeling to delineate the AoR, how to identify all wells that 

require corrective action, performing corrective action at GS sites, and, when appropriate, completing 

AoR reevaluations. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

The final rule retains the language in §146.84(c)(2) as proposed. EPA clarifies that the mapping and 

cross sections required to be submitted under §146.82(a)(3) will define the limits of the confining zone, 

which would be accounted for in the AoR delineation and corrective action evaluation required at 

§146.84(c). EPA adds that owners or operators must also, under §146.82(a)(2), submit a map of the AoR 

that shows all injection wells, producing wells, abandoned wells, plugged wells or dry holes, deep 

stratigraphic boreholes, State or EPA approved subsurface cleanup sites, surface bodies of water, 

springs, mines (surface and subsurface), quarries, water wells and other pertinent surface features 

including structures intended for human occupancy and roads. EPA believes that these requirements 

address the commenter's concerns. 

Other EPA Comment Codes and Descriptions: 3530 2.2.3.1 AoR reevaluation frequency (seeking 

comment) 

Comment: Proposed Rule: 146.84(f) 

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22596

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22597

215
Proposed revision: (f) At the minimum fixed frequency, not to exceed two years 

if under operational testing (prior to issuance of the operating permit), or 5 

years (if operating permit has been issued), as specified in the area of review 

and corrective action plan or when monitoring and operational conditions 

warrant, owners or operators must: 

Rationale: This makes this consistent with NGWA's proposed revision to Section 

146.84(b)(2)(i) 

Response: EPA agrees that reevaluations of the AoR every ten years may not be sufficient to 

appropriately model plume and pressure front movement, establish conditions for corrective action, and 

ensure protection of USDWs from endangerment. For these reasons, the Agency changed the minimum 

frequency for the AoR reevaluation at §146.84(e) from 10 years to at least every 5 years in the final GS 

rule. EPA believes that this revised frequency addresses commenters' concerns about the inherent 

uncertainties in modeling CO2 movement, the emerging nature of GS technology, risk-based targeting 

of monitoring activities, and the unique nature of CO2 GS. In addition, the Director has discretion to 

require more frequent AoR reevaluation if he or she has reason to believe, based on site-specific 

information, that a five-year reevaluation schedule is not sufficiently protective of USDWs. 

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

responsibility requirements (40 CFR 146.85) 

Comment: Proposed Rule: 146.85(b) 

Proposed revision: (b) The owner or operator must provide to the Director, at 

the same frequency as the AOR reevaluation, written updates of adjustments to 

the cost estimate to account for any amendments to the area of review and 

corrective action plan (§146.84), the injection well plugging plan (§146.92), 

and the post-injection site care and site closure plan (§146.93). 

Rationale: NGWA proposes that potential changes in the size of the AOR require 

that all site plans be reevaluated at the same frequency as the AOR. 

Response: EPA agrees that it is important to periodically update cost estimates that support financial 

responsibility determinations. EPA clarifies that the GS rule, at §146.85(c) requires the owner or 

operator to provide annual updates to the cost estimate to account for any amendments to the AoR and 

corrective action plan, the injection well plugging plan, the PISC and site closure plan, and the 

emergency and remedial response plan. See the final rule and preamble for further discussion of EPA's 

final approach to financial responsibility. EPA adds that the Director can also require the owner or 

operator to provide an adjustment of the cost estimate if the Director determines that the original 

demonstration is no longer adequate, as specified at §146.85(e). The owner or operator must also update 

the cost estimate annually to adjust for inflation under §146.85(c)(2). 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Proposed Rule: 146.87(a)(3)(ii) 

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22599

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22604

216
Proposed revision: (ii) A cement bond, variable density log, and radial cement 

evaluation log and a temperature log after the casing is set and cemented. 

Rationale: NGWA supports inclusion of a radial cement evaluation log in 

addition. The addition of this test will help identify any potential channels 

in the cement out from casing 

Response: EPA clarifies at §146.87(a)(2)(ii) that owners or operators must perform a cement bond (i.e., 

cement evaluation) log after the casing is set and cemented. 

Other EPA Comment Codes and Descriptions: 4543 2.5.2.1 MIT procedures and methods for GS 

(seeking comment) 

Comment: Proposed Rule: 146.89(c) 

Proposed revision: At least once per year, the owner or operator must use one 

of the following methods, as approved by the director, to determine the absence 

of significant fluid movement under paragraph (a)(2) of this section. 

Rationale: There was a question as to whether one of these tests individually 

would suffice in all circumstances. The change proposed is to allow the 

director to review the proposal. 

Response: EPA clarifies that all MITs the owner or operator proposes to use must be described in the 

proposed testing and monitoring plan, which must be approved by the Director. See §146.90. EPA 

believes that the MITs described in §146.89(c) of the rule (e.g., an approved tracer log or temperature or 

noise logs) are effective methods to demonstrate external MI, provide an important early warning of 

potential problems in the injection well system, and represent standard techniques that have been used 

successfully by the drilling industry and for the UIC Program for decades. The Agency notes that the 

regulations do provide the Director flexibility at §146.89(e) to approve the use of alternative MIT 

methods. 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: [In the text below, text in CAPS denotes added text.] 

Proposed Rule: 146.90(h)(1) 

Proposed revision: (1) The testing and monitoring plan must be based on 

potential RISKS within the area of review; 

Rationale: Risk is more generally accepted and understood. 

Response: The final rule at §146.90(h)(1) incorporates the suggested revision. Based on its evaluation 

of all public comments and input on the proposed rule and NODA and Request for Comment EPA has 

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22606

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22609

217
made many revisions to the GS rule. See the final rule and preamble for further discussion on EPA's 

final approach. 

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: Proposed Rule: 146.91 

Proposed addition: (1) Class VI Test/Injection Well Construction Permit 

Proposed addition: (a) The Director shall require periodic data reports and 

progress reports during construction that include: 

Proposed addition: 1. Driller's log 

Proposed addition: 2. Geophysical surveys 

Proposed addition: 3. Core analyses 

Proposed addition: 4. Lithologic logs 

Proposed addition: 5. Drill stem tests 

Proposed addition: 6. Pump tests 

Proposed addition: 7. Daily job (construction) reports 

Proposed addition: 8. Water quality analyses 

Proposed addition: (b) The frequency of reporting shall be specified in the 

individual permit 

Proposed addition: (c ) Interpretation of data is required in the data reports 

or progress reports at the completion of each significant phase of construction, 

such as completion of test well construction and testing, completion of 

injection well construction, and completion of injection well testing. 

Proposed addition: (d) The owner or operator shall submit final reports of all 

data collected from the test injection ell with interpretations to the Director 

with the application for a Class VI Test/Injection Well Construction and Testing 

Permit and a Class VI Injection Well Operation Permit shall include all 

information and data collected under Section 146.87, with appropriate 

interpretations 

Proposed addition: (2) Class VI Operational Testing Permit 

Proposed addition: (a) The owner or operator shall submit, as part of the permit 

application, the proposed methodology for collection and reporting of 

operational data, to ensure that the data is collected, correlated, and reported 

in a fashion that would enable the Director to evaluate well performance. 

Proposed addition: (b) All Class VI wells shall report monthly the following: 

Proposed addition: 1. Operating reports to the Director on: 

Proposed addition: a. The physical, chemical, and other relevant 

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22610

218
characteristics of injection fluids; 

Proposed addition: b. Daily reading of the pressure and flow for each well. For 

each Class VI sequestration well, a specific injectivity test shall be performed 

quarterly; 

Proposed addition: c. Monthly average, maximum and minimum values for injection 

pressure, flow rate and volume, and annular pressure; and 

Proposed addition: d. The results of monitoring prescribed under Section 146.90 

Proposed addition: 2. Reporting the results, within three months after the 

completion of: 

Proposed addition: a. Annular monitoring tests of mechanical integrity; 

Proposed addition: b. Any other test of the injection ell conducted by the 

permittee if required by the Director; and 

Proposed addition: c. Any well work over. 

Proposed addition: (c ) Specific injectivity testing shall be performed while 

the pumping rate to the well(s) has been set at a predetermined level and 

reported as the specific injectivity index (gpm/specific pressure (psig)). As 

part of this test, the well shall be shut-in for a period of time necessary to 

conduct a valid observation of pressure fall-off. The owner or operator shall 

propose which pumping rate will be used based on the expected flow, the design 

of the pump station including the volume of the wet well and pump type(s), and 

the type of pump controls used. The pumping rate(s) shall be included as a 

condition of the operation permit. 

Proposed addition: (d) Re-evaluation of Area of Review. After completion of the 

operatonal testing period, the Area of Review shall be re-evaluated, using a 

calibrated, multi-phase fluid flow model. The data collection during 

operational testing must be adequate for calibration of the model. If a 

calibrated model cannot be prepared using data collected during operational 

testing, the owner or operator shall apply for a new period of operational 

testing of up to two years in order to collect the required data. No more than 

two operational testing permits can be issued for any Class VI well. If the 

recalculated Area of Review includes any relevant wells or penetrations through 

the confining zone that were not reported in the permit application, a new 

tabulation of penetrations as required in Section 146.84(c)(2) and (3) shall be 

provided. Owners or operators must perform corrective action as required in 

Section 146.84(d). 

Proposed addition: (e) If physical or geochemical data such as water quality, 

pressure changes, or mechanical integrity test results indicate that fluid 

movement into or between underground sources of drinking water may be occurring, 

the permittee shall submit additional data to provide reasonable assurance that 

the injection operation is in compliance with the requirements of this chapter. 

This additional data shall be submitted with the periodic operations reports, 

219
the content and frequency of which are specified in the individual permit. 

Proposed addition: (f) A Class VI well permit shall be written to require that 

if CFR Section 146.14(a) is applicable, progress reports shall be submitted no 

later than thirty days following each interim date and the final date of 

compliance. 

Proposed addition: (3) Class VI Injection Well Operation Permit. 

Proposed addition: (a) The applicant shall submit, as part of the permit 

application, the proposed methodology for collection and reporting of 

operational data, to ensure that the data is collected, correlated, and reported 

in a fashion that would enable the Director to evaluate well performance. 

Proposed addition: (b) All Class VI wells shall report monthly the following: 

Proposed addition: 1. Operating reports to the Director on: 

Proposed addition: a. The physical, chemical, and other relevant characteristics 

of injection fluids; 

Proposed addition: b. Daily readings of the pressure and flow for each well. 

For each Class VI well, a specific injectivity test shall be performed 

quarterly; 

Proposed addition: c. Monthly average, maximum and minimum values for injection 

pressure, flow rate and volume, and annular pressure; and 

Proposed addition: d. The results of monitoring prescribed under Section 146.90 

Proposed addition: 2. Reporting the results, within three months after the 

completion of: 

Proposed addition: a. Periodic tests of mechanical integrity; 

Proposed addition: b. Any other test of the injection well conducted by the 

permittee if required by the Director; and 

Proposed addition: c. Any well work over. 

Proposed addition: (c ) Specific injectivity testing shall be performed while 

the pumping rate to the well(s) has been set at a predetermined level and 

reported as the specific injectivity index (gpm/specific pressure (psig)). As 

part of this test, the well shall be shut-in for a period of time necessary to 

conduct a valid observation of pressure fall-off. The owner or operator shall 

propose which pumping rate will be used based on the expected flow, the design 

of the pump stations including the volume of the wet well and pump type(s), and 

the type of pump controls used. The pumping rate(s) shall be included as a 

condition of the operation permit. 

(d) Re-evaluation of Area of Review. Every five years, the Area of Review shall 

220
be re-evaluated, using a calibrated, multi-phase fluid flow model. The data 

collection during operation must be adequate for calibration of the model. If a 

calibrated model cannot be prepared using data collected during operation, the 

owner or operator shall, within 90 days, apply for a new operation permit with a 

revised monitoring and testing plan designed to collect the required data. The 

re-issued Class VI operation permit shall be valid for a period of no more than 

two years. After two years of operation under a re-issued operating permit, the 

applicant shall again re- evaluate the Area of Review using a calibrated, multiphase fluid flow model and re-apply for a five-year operating permit. If the 

recalculated Area of Review includes any relevant wells or penetrations whose 

total depth is greater than the depth to the bottom of the lowermost USDW that 

were not reported in the permit application, a new tabulation of penetrations as 

required in Section 146.84(c)(2) and (3) shall be provided. Owners or operators 

must perform corrective action as required in Section 146.84(d) must perform 

corrective action as required in Section 146.84(d). 

No rationale provided 

Proposed Rule: Introductory text to 146.91 and 146.91(a)(1)-(4) 

Revision or comment: Proposed for deletion 

Rationale: Covered in proposed Section 146.91(3) and subsections 

Proposed Rule: 146.91(a)(5) 

Revision or comment: Renumber 3(e) 

Proposed Rule: 146.91(a)(6) 

Revision or comment: Renumber 3(f); delete "and" 

Proposed addition: (g) If physical or geochemical data such as water quality, 

pressure changes, or mechanical integrity test results indicate that fluid 

movement into or between underground sources of drinking water may be occurring, 

the permittee shall submit additional data to provide reasonable assurance that 

the injection operation is in compliance with the requirements of this chapter. 

This additional data shall be submitted with the periodic operations reports, 

the content and frequency of which are specified in the individual permit. 

Proposed addition: (h) A Class VI well permit shall be written to require that 

if CFR Section 146.41(a) is applicable, progress reports shall be submitted no 

later than thirty days following each interim date and the final date of 

compliance. 

No rationale provided 

Proposed Rule: 146.91(a)(7); 146.91(b)(1)-(3) 

Proposed for deletion 

221
Rationale: Covered in proposed Section 146.91(3) and subsections 

Proposed Rule: 146.91(c) 

Renumber (4) 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. EPA is developing guidances on injection well 

construction and on monitoring and testing that will assist owners or operators and Directors in 

performing the pre-operational logging and testing required at §146.86. This guidance will be available 

on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

As described above, EPA clarifies that the final rule does not require an owner or operator to obtain a 

separate Class VI operational testing permit. However, EPA revised §146.82 so that the final regulation 

specifies separate requirements for information to be submitted with the permit application and before 

well construction is approved (at §146.82(a)) and information to be submitted before operation of the 

well is authorized (at §146.82(c)). Final information on injection zone pressures are required following 

drilling of the well, at §146.82(c)(4). 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care 

Comment: Proposed Rule: 146.92(b) 

Proposed revision: (b) Well Plugging Plan. The owner or operator of a Class VI 

well must prepare; maintain; including updating on the same schedule as the 

update to the Area of Review; and comply with a plan that is acceptable to the 

Director. The requirement to maintain and implement an approved plan is 

directly... 

Rationale: The Area of Review re-evaluation should trigger a review and updating 

of all the plans (MMV, financial, plugging, emergency response...) on the same 

interval that the AOR is updated. NGWA suggests EPA check all timelines and 

make them compatible. 

Response: EPA agrees that the AoR reevaluations offer a good opportunity to promote a dialogue 

between the owner or operator and the permitting authority. Additionally, EPA recognizes that the AoR 

reevaluation has the potential to change or add important data to the other project plans and therefore the 

Agency agrees that the other Class VI plans must be updated when an AoR reevaluation takes place. The 

final GS rule, at §§146.84(c), 146.90(j), and 146.94(d), requires owners or operators to review and 

update the AoR and corrective action plan, the testing and monitoring plan, and the emergency and 

remedial response plan throughout the life of the project. Owners or operators must review each plan 

and identify necessary amendments to the plan or demonstrate to the Director that no amendment is 

needed. These reviews must be performed within one year of an AoR reevaluation, following any 

significant changes to the facility (e.g., the addition of monitoring or injection wells), or when required 

by the Director. In no case can reviews occur less often than once every five years. EPA is preparing 

guidance for owners or operators on developing and updating all of the required GS project plans. The 

guidance will be available on EPA's web site, at 

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22611

222
http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. See the final rule and preamble for 

further discussion on EPA's final approach regarding the GS project plans. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 

146.92) 

Comment: Proposed Rule: 146.92(d) 

Proposed revision: (d) Plugging Reports for Class VI Wells. Within 60 days 

after completion of plugging and abandonment of a well or well field the 

permittee shall submit to the Director a final report which includes: 

Proposed addition: (1) Certification of completion in accordance with approved 

plans and specifications by an appropriately qualified engineer of record or 

professional geologist. 

Note: It is important that the engineer and/or geologist have expertise and 

training in injection well drilling technology, reservoir characterization and 

injection well construction and operation. 

Proposed addition: (2) Evidence, such as a sealed copy or certification from the 

county clerk, that a surveyor's plot of the location of the abandoned well has 

been recorded in the county courthouse property records. 

Response: EPA agrees that appropriately qualified personnel (e.g., engineers and geologists) should be 

involved in all aspects of the GS operation, including the well plugging process. When the owner or 

operator (and/or the person who performs the plugging operation) signs the plugging report and certifies 

it as accurate; they are attesting to the fact that all required activities were performed by qualified 

personnel. This is required under §146.92(d) and is a condition of the permit that is enforceable under 

§1423 of the SDWA. EPA clarifies that, in addition to requiring appropriate well plugging, the Director 

retains the option of witnessing any plugging activity or testing at the well. 

EPA clarifies that §146.93(g) requires the owner or operator, as part of the closure process, to record a 

notation on the deed stating that the property was used for GS. In addition, §146.93(f)(1) requires 

submission of a survey plat indicating the location of the well to the local zoning authority, as well as to 

the Director. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Proposed Rule: 146.93(a) 

Proposed revision: (a) The owner or operator of a Class VI well must prepare; 

maintain; including updating on the same schedule as the update to the Area of 

Review; and comply with a plan for post-injection site care and site closure 

that meets the requirements of paragraph (a)(2) of this section and is 

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22612

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22613

223
acceptable to the Director. 

Rationale: The Area of Review re-evaluation should trigger a review and updating 

of the well plugging plan, and the post injection site care and closure plan. 

NGWA suggests EPA check all timelines and make them compatible. 

Response: EPA agrees with the commenter that, in some cases, the appropriate post-injection 

monitoring strategy may end up being different than initially projected at the time of permit application 

and there may be a need to amend the post-injection site care and site closure plan. EPA is requiring that 

upon the cessation of injection, the owner or operator submit an amended post-injection site care and 

site closure plan or demonstrate to the Director that no changes to the original post-injection site care 

and site closure plan are necessary, as specified in §146.93(a)(3). EPA is not requiring formal periodic 

review and updates to the PISC and site closure plan throughout the injection phase. EPA does not 

expect that changes to this plan would be implemented until injection operations cease. EPA envisions 

that owners or operators will take into account similar considerations that guide updates to other project 

plans, e.g., monitoring and operational data and results of AoR reevaluations. 

EPA has also added a new provision at §144.39(a)(5) requiring a modification, revocation, or reissuance 

of a Class VI permit whenever the Director determines that a change in the permit is necessary based on 

an amended AoR and corrective action plan, testing and monitoring plan, injection well plugging plan, 

post-injection site care and site closure plan, or emergency and remedial response plan is necessary. This 

would invoke the public notification procedures of 40 CFR Part 124 and the modification would be 

incorporated into the permit. EPA adds that, if any monitoring or other site data indicate a need for 

amending the post-injection site care plan, the owner or operator is expected to amend the plan 

accordingly. 

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment) 

Comment: Proposed Rule: 146.93(b)(1) 

Proposed revision: (1) The owner or operator shall continue to conduct 

monitoring as specified in the Director-approved post-injection site care and 

site closure plan for at least 30 years following the cessation of injection. 

At the Director's discretion, the monitoring will continue until the geologic 

sequestration project no longer poses an endangerment to USDWs. 

Rationale: NGWA believes some number should be included. 30 years is a number 

used in other EPA programs. The next question was whether the burden should be 

placed on the director to justify the longer number or on the operator to prove 

the site is stabilizing. It is suggested that the director be allowed to 

approve both a shorter or longer timeframe. With the next subsection, the 

burden is placed on the owner or operator to prove a shorter timeframe is 

acceptable, while allowing in this subsection the director to require monitoring 

beyond 30 years. 

Proposed Rule: 146.93(b)(2) 

Proposed revision: (2) If the owner or operator can demonstrate to the 

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22614

224
satisfaction of the Director that the geologic sequestration project no longer 

poses an endangerment to USDWs, the Director may approve an amendment to the 

post-injection site care and site closure plan to reduce the frequency of 

monitoring or may authorize site closure before the end of the 30-year period. 

Rationale: Makes this subsection compatible with 30 year timeframe proposed by 

NGWA in 146.93(b)(1) 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most 

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a review 

of research studies, industry reports, and existing environmental programs. This analysis was included in 

an EPA-prepared background document that is available in the federal docket, titled "Computational 

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and 

Potential Risk to Underground Sources of Drinking Water." EPA assessed various default timeframes 

based on additional review of research studies and evaluation of public comments. While numerous 

commenters suggested that EPA shorten the monitoring timeframe, none of the commenters provided 

sufficient data or other evidence to warrant a change in the proposed timeframe. While the 10- or 30-

year timeframe suggested by some of these commenters may be within the timeframe suggested in some 

studies, EPA believes that the potential risks of endangering USDWs will likely not decline within these 

timeframes and available data, including data submitted by commenters, do not support a different 

default timeframe. 

However, EPA recognizes that there may be sites where the 50 year post injection site care timeframe 

may be either not appropriate or more burdensome than necessary based on site-specific conditions. For 

this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC 

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the 

post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording 

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the permitting 

process based on substantial data, that an alternative PISC timeframe may be appropriate if it ensures 

non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts, as the commenter suggests. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: Proposed Rule: 146.94(a) 

Proposed revision: (a) As part of the permit application, the owner or operator 

must provide the Director with an emergency and remedial response plan that 

describes actions to be taken to address movement of the injection or formation 

fluids that may cause an endangerment to a USDW during construction, operation, 

closure and post-closure periods. The emergency and remedial response plan must 

be reviewed and updated, as necessary, on the same schedule as the update to the 

Area of Review. 

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22615

225
Rationale: Keep same update schedule as AOR 

Response: In response to comments on the duration of the emergency and remedial response plan, EPA 

clarifies that the plan will apply over the life of the GS project through the post-injection site care period 

(§146.94(a)). EPA has added a requirement at §146.94(d) that owners or operators must review their 

emergency and remedial response plan within one year of an AoR reevaluation required under §146.84 

or following significant changes to the facility. Subsequently, owners or operators must submit an 

amended plan or demonstrate to the Director that no amendment to the plan is needed based on the AoR 

reevaluation or any significant changes made to the facility. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: 146.83 (a) (1): MDEQ suggests adding the same language to (1) as is found in 

(2): "without initiating or propagating fractures in the injection zone. 

Response: EPA did not make the suggested edit to the injection zone requirement but retained similar 

language in the restriction on injection pressure at §146.88(a). 

Comment: §146.81 Applicability. (b) "This subpart applies to wells used to inject carbon 

dioxide specifically for the purpose of geologic sequestration, i.e., the longterm containment of a gaseous, liquid or supercritical carbon dioxide stream in 

subsurface geologic formations." 

We recommend striking out "gaseous, liquid or supercritical carbon dioxide 

stream" and replacing with "gaseous, liquid, supercritical or co-mixed carbon 

dioxide stream" This change will allow for injection of carbon dioxide that is 

pre-dissolved with water to prevent phase separation in the injection zone or 

with inclusion of flow or pumping enhancement components. 

Response: EPA disagrees with the suggested change. EPA believes that this paragraph, along with the 

definition of a CO2 stream at §146.81(d), appropriately convey the allowable injection activities that 

may be permitted as Class VI. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82) 

Comment: 146.82 Required Class VI permit information. (b) "A map showing the injection 

well(s) for which a permit is sought and the applicable area of review. Within 

the area of review, the map must show the number, or name and location of all 

injection wells, producing wells, abandoned wells, plugged wells or dry holes, 

Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality 

(MDEQ)

Comment ID: 

22126

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23768

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23769

226
deep stratigraphic boreholes, State or EPA approved subsurface cleanup sites, 

surface bodies of water, springs, mines (surface and subsurface), quarries, 

water wells and other pertinent surface features including structures intended 

for human occupancy and roads. The map should also show faults, if known or 

suspected. Only information of public record is required to be included on this 

map; " 

The note that "only information of public record is required to be included on 

this map" may leave out deep oil and gas wells, particularly older wells. The 

presence of such non-public but "known" information may be eligible for 

inclusion as "known" under 144.55(a). 

Response: EPA believes that a determination about whether or what information may be necessary (for 

a specific GS project) is outside of the public record will be site-specific and based on knowledge of the 

site, data availability, and data quality. For instance, in meeting the requirement to tabulate information 

on wells in the AoR, the Director has the discretion to require the owner or operator to supplement a 

data records search if there is reason to believe that the incompleteness of available information could 

compromise USDW protection from endangerment. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82) 

Comment: §146.82 Required Class VI permit information (e) "A tabulation of all wells 

within the area of review which penetrate the injection or confining zone(s). 

Such data must include a description of each well's type, construction, date 

drilled, location, depth, record of plugging and/or completion, and any 

additional information the Director may require; - 

We recommend striking out "all wells" and replacing with "all known wells". 

Requiring that all wells or other artificial penetrations into injection or 

confining zones within the AoR be identified and information on depth and 

closure be provided can be costly and sometimes accurate information is 

difficult to obtain for older wells within the AoR. EPA's assistance in 

obtaining and storing this information would be helpful to CCS operators. 

Response: The Agency believes that the requirement to provide a tabulation of wells and geologic 

information (at §146.82(a)), along with a description of each well's type, construction, date drilled, 

location, depth, record of plugging and/or completion will appropriately inform a determination of the 

risk associated with wells in the AoR. EPA believes that it is important to have information on all wells 

in the AoR. 

Other EPA Comment Codes and Descriptions: 3330 2.2.1.3 Applicability /adequacy of 

computational models (seeking comment) 

Comment: §146.84 Area of review and corrective action. (c) (1) "Predict, using 

computational modeling, the projected lateral and vertical migration of the 

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23770

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23771

227
carbon dioxide plume and formation fluids in the subsurface from the 

commencement of injection activities until the plume movement ceases, pressure 

differentials sufficient to cause the movement of injected fluids or formation 

fluids into a USDW are no longer present, or after a fixed time period as 

determined by the Director." 

We recommend striking out "Predict, using computational modeling, the protected 

lateral and vertical migration of the carbon dioxide plume" and replacing with 

"Using computational modeling, provide protected potential ranges of lateral and 

vertical migration of the carbon dioxide plume" The use of multiphase 

groundwater flow and transport models is to predict the composition and movement 

of each phase state (e.g., liquid, gas ,supercritical fluid) of CO2 in the 

subsurface, as well as fluid pressures, to define the AoR. One of the concerns 

with the use of such complex models is that the site may not be fully 

characterized with respect to hydro-geologic properties. There may be 

significant uncertainty in one or more hydraulic processes/parameters. 

Therefore, it is possible to obtain a wide-range of model outcomes from 

different model parameters. The uncertainty in model parameters and sensitivity 

of model results to parameter selection should be addressed. 

Response: EPA has clarified this language in the final rule. It now reads, “Predict, using existing site 

characterization, monitoring and operational data, and computational modeling, the projected lateral and 

vertical migration of the carbon dioxide plume and formation fluids in the subsurface from the 

commencement of injection activities until the plume movement ceases, until pressure differentials 

sufficient to cause the movement of injected fluids or formation fluids into a USDW are no longer 

present, or until the end of a fixed time period as determined by the Director.” 

EPA agrees that modeling results are prone to varied degrees of uncertainty. As discussed in the 

preamble to the proposed GS regulation and the associated background document "Computational 

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and 

Potential Risk to Underground Sources of Drinking Water" (cited in the proposed rule preamble as 

USEPA, 2008d), model predictions depend largely on the values of key parameters. Often these 

parameter values are estimated or averaged from several data sources. EPA also agrees that sensitivity 

analyses and "worst case scenario" modeling runs should be presented by the owner or operator and 

evaluated by the Director. If during the permit review, the Director determines that modeling results are 

too wide-ranging, further information will be required of the owner or operator. 

EPA clarifies that models are tools to help predict the movement of a CO2 plume over long time frames. 

However, EPA recognizes that it cannot be expected that modeling something as complex as a CO2 

plume can be done with complete certainty; therefore EPA is also requiring that the AoR be reevaluated 

to verify the CO2 plume is moving as predicted and to allow for model calibration and necessary 

revisions to the required GS project plans (e.g., AoR and corrective action, testing and monitoring, 

injection well plugging, post-injection site care and site closure, and emergency and remedial response). 

EPA believes that near-term predictions (e.g., over the subsequent 5 years) will have the highest degree 

of certainty. Periodic model calibration will allow refinement to the AoR delineation based on realworld conditions and operating data and monitoring results, and thus increase confidence in the modeled 

predictions. EPA adds that the final GS regulation includes a requirement at §146.84(e) that the AoR be 

reevaluated at least every 5 years (an adjustment from the ten year interval in the proposal), which 

should further address the commenters' concerns regarding model uncertainty. 

228
Other EPA Comment Codes and Descriptions: 3440 2.2.2.2 Evaluation of wells in the AoR (e.g., 

types of data to be reviewed) 

Comment: §146.84 Area of review and corrective action. (c) (2) "Using methods approved by 

the Director, identify all penetrations, including active and abandoned wells 

and underground mines, in the area of review that may penetrate the confining 

zone. Provide a description of each well's type, construction, date drilled, 

location, depth, record of plugging and/or completion, and any additional 

information the Director may require; and ..." 

We recommend striking out "approved" and replacing with "prescribed". We 

recommend deleting the second sentence and replacing with "Where such 

information is available or can be obtained, provide a description of each 

well's type, construction, date drilled, location depth record of plugging 

and/or completion and any additional information prescribed by the director and 

..." Acceptable methods for identifying deep wells into confining zones within 

the AoR should be prescribed by the EPA as part of the regulation. Accurate 

information is difficult to obtain for older wells within the AoR. Examples of 

other information that could be required by the Director should be clearly 

stated. 

Response: EPA is retaining the language in §146.84(c)(2) as proposed. Based on its evaluation of all 

public comments and input on the proposed rule and NODA and Request for Comment, EPA has made 

many other revisions to the GS Rule. See the final rule and preamble for further discussion on EPA's 

final approach. 

EPA acknowledges that public records may not contain data on every artificial penetration in the AoR 

(or all of the data on each well that is required for the tabulation), particularly in areas with many older 

wells. However, the Agency recognizes that there may be situations where additional surveys or 

research to locate information on wells may be appropriate. For example, there may be cases where the 

Director may determine that ground or airborne surveys for wells are appropriate, e.g., if there is reason 

to believe that the incompleteness of information on known wells could compromise USDW protection 

from endangerment. In order to preserve the Director's discretion to require an operator to supplement a 

records search, EPA did not make the suggested change. EPA adds that all corrective action must be 

performed pursuant to the approved AoR and corrective action plan, which affords the Director the 

discretion to require any additional information needed (including information that may not be 

publically available) to ensure that all necessary corrective action is performed. The guidance describes 

EPA's recommended approaches for the data to be considered in an initial AoR delineation, how to 

apply computational modeling to delineate the AoR, performing corrective action at GS sites, and, when 

appropriate, completing AoR reevaluations. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm 

Other EPA Comment Codes and Descriptions: 3822 2.3.1.1 Depth of surface casing (seeking 

comment) 

Comment: §146.86 Injection well construction requirements. (b) (2) "Surface casing must 

extend through the base of the lowermost USDW and be cemented to the surface. " 

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23772

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23773

229
We recommend striking out this requirement in its entirety. This will be 

prohibitively expensive in deep wells, and may not be necessary at all sites. 

Response: EPA disagrees that protecting deep USDWs underlying multiple, more shallow USDWs is 

unnecessary. Protection of USDWs, regardless of their depth or stratigraphic location, is the primary 

mission and mandate of the UIC program—as specified by Congress in the SDWA—and the purpose of 

all requirements for injection wells. Any injection activity must be demonstrated to not endanger 

USDWs, regardless of their depth, and if such a demonstration cannot be made, then the activity will not 

be allowed under UIC requirements or the SDWA. Water agencies commenting on the proposed rule 

noted that diminishing water supplies are requiring water utilities to use deeper and more saline sources, 

and the SDWA mandates EPA to set regulations that protect USDWs from endangerment. 

The final GS rule at §146.86(b)(2) requires that surface casing extend through the base of the lowermost 

USDW and be cemented to the surface through the use of a single string or multiple strings of casing 

and cement. It does not, however, specify how cementing must be accomplished, and it allows the owner 

or operator to propose alternate methods that provide a sufficient amount of cement to meet the standard 

that USDWs are protected from endangerment. EPA notes that there are many potential ways to meet 

the requirement, such as the use of staged cementing. 

EPA recognizes concerns regarding construction of Class VI wells where the lowermost USDW is very 

deep. To further address comments on deep injection wells, the final GS rule at §146.95 includes 

requirements for owners or operators that seek a waiver of the injection depth requirements. Owners or 

operators of wells operating under injection depth waivers must comply with additional construction 

requirements to ensure that wells used to inject above or between USDWs are protective. See the 

discussion of the waiver approach in the preamble to the final GS rule for additional information. 

Other EPA Comment Codes and Descriptions: 4400 2.4.4.3 Allowing injection above or between 

USDWs (seeking comment); 4660 2.6.6 Geochemical monitoring 

Comment: §146.90 Testing and monitoring requirements. (d) Periodic monitoring of the 

ground water quality and geochemical changes above the confining zone(s) that 

may be a result of carbon dioxide movement through the confining zone or 

additional identified zones: 

We recommend changing to "Periodic monitoring of the ground water quality and 

geochemical changes between the confining zone(s) and the USDW that may be a 

result of carbon dioxide movement through the confining zone or additional 

identified zones:" This rewording is consistent with allowing for injection 

either above or below USDWs 

Response: EPA disagrees that the GS rule should specify the zones to be monitored. EPA clarifies that 

§146.90(d) requires periodic monitoring of the ground water quality and geochemical changes above the 

confining zone(s). EPA clarifies that this monitoring requirement does not include the confining layer 

itself. Monitoring above the confining layer will provide an indication of upward movement of CO2 that 

might endanger a USDW. The exact number of formations to be tested will, however, be based on sitespecific characteristics and vulnerabilities and described in the Director-approved testing and monitoring 

plan. 

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in 

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23774

230
evaluating requirements under §146.90, including proposed monitoring plans. The guidance describes 

available technologies and recommended approaches for implementing a testing and monitoring plan, 

including pre-operational geophysical logging and testing of injection wells, MITs, injection well testing 

during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, and soil 

gas and surface air monitoring which may be required by the UIC Director for specific GS projects. The 

guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

In the final GS rule, owners or operators granted injection depth waivers are subject to additional 

requirements at §146.95(f)(3) to monitor above and below the injection zone in order to ensure 

protection of USDWs underlying and overlying the injection zone during both well operation and the 

post-injection site care period. 

For additional information on the waiver approach, please see the final rule and preamble, as well as 

EPA's responses to comments on the Notice of Data Availability and Request for Comment. 

Other EPA Comment Codes and Descriptions: 4650 2.6.5 CO2 plume and pressure front tracking 

(seeking comment) 

Comment: §146.90 Testing and monitoring requirements. (g) "Testing and monitoring to 

track the extent of the carbon dioxide plume and the position of the pressure 

front by either monitoring for pressure changes in the first formation overlying 

the confining zone or using indirect, geophysical techniques (e.g., seismic, 

electrical, gravity, or electromagnetic surveys and/or down-hole carbon dioxide 

detection tools); - 

We recommend deletion of this requirement in its entirety and replacing with 

"Testing and monitoring to track the extent of the carbon dioxide plume." 

Tracking the precise position of a moving pressure front will require a large 

number of expensive and deeply located probes. A limited number of pressure 

monitors that can provide information on pressures affecting the confinement 

layers are more valuable. The Proposed Rule also requires well owners to monitor 

periodically groundwater quality and geochemical changes above the confining 

zone. The requirements for such deep monitor wells could be costly. Requiring 

both pressure and geochemical monitoring will be costly and provide questionable 

additional information or warning. 

Response: EPA maintains that plume tracking and pressure monitoring are key components of 

monitoring at GS sites. A rigorous plume tracking and pressure monitoring scheme, such as one that 

meets the requirements at §146.90(g), is imperative for ensuring that the CO2 plume is contained within 

the injection zone. 

The final rule (at §146.90(g)) requires owners or operators to perform monitoring to track the extent of 

the CO2 plume and pressure front. The owner or operator must use direct methods to monitor for 

pressure changes in the injection zone. Indirect methods (e.g., seismic, electrical, gravity, or 

electromagnetic surveys and/or down-hole CO2 detection tools) are also required unless the Director 

determines, based on site-specific geology, that such methods are not appropriate 

Pressure monitoring in the injection zone is necessary to track the development and movement of the 

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23775

231
pressure front and CO2 plume. When combined with information on temperature, pressure data provide 

an indication of the phase (e.g., gas, supercritical) and distribution of the injected CO2 (73 FR 43515). 

Monitoring can also identify needed remedial actions, provide inputs for AoR reevaluation modeling, 

evaluate predictions of plume movement, and target additional geochemical and surface monitoring 

needs. 

EPA recognizes that installation of monitoring wells entails additional resources. However, the Agency 

believes that such monitoring is necessary to ensure that GS projects are appropriately operated and 

monitored and to protect USDWs from endangerment. EPA believes that pressure monitoring in the 

injection zone is necessary to track the development and movement of the pressure front and CO2 

plume. Monitoring can also identify needed remedial actions, provide inputs for AoR reevaluation 

modeling, evaluate predictions of plume movement, and target additional geochemical and surface 

monitoring needs. Knowledge of the location of the CO2 plume and the associated pressure front will 

assure the public that GS projects are proceeding according to plan, provide sufficient information to the 

owner or operator and Director, or allow for appropriate actions to address any indication that USDWs 

may be endangered. 

The combination of site characterization and predictive modeling will help guide the siting of 

monitoring wells and enable operators to optimize the number and position of wells. The Directorapproved testing and monitoring plan will describe the use and installation of monitoring wells at the 

site. 

EPA acknowledges the commenters' concern about the cost of pressure monitoring. However, EPA 

believes that this monitoring is essential for protection of USDWs at GS sites Although a significant cost 

in absolute terms, monitoring costs are expected to be a small fraction of site operating costs, according 

to EPA's cost analysis for the GS rulemaking (which is available in the docket). 

Other EPA Comment Codes and Descriptions: 4670 2.6.7 Surface air monitoring and/or soil gas 

monitoring (seeking comment) 

Comment: §146.90 Testing and monitoring requirements. (71) "At the Director's discretion, 

surface air monitoring and/or soil gas monitoring to detect movement of carbon 

dioxide that could endanger a USDW. " 

We recommend deletion of this requirement in its entirety. While this 

requirement may be suitable for determining potential air leakage relevant to 

monitoring of CO2 in a greenhouse gas policy context, this requirement does not 

provide any additional protection to migration to USDW as surface breakthrough 

will only occur well after the deep-surface migration of CO2 to a USDW. Surface 

monitoring to detect CO2 has high uncertainty and seasonal variability that is 

likely to result in many false positives and operational distractions. Seismic 

methods of tracking the CO2 plume are more effective than soil gas monitoring of 

CO2, which is affected by many other factors and thus is highly variable. 

Response: EPA acknowledges that surface air and soil gas measurements are subject to variability and 

may not be suitable in all settings as a method to ensure USDW protection. However, EPA does not 

believe that this should entirely preclude their use. The decision to use surface monitoring and the 

selection of monitoring methods will be site-specific (e.g., may be influenced by geology, injection 

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23776

232
depth, and operational conditions) and must be based on potential risks to USDWs within the AoR. The 

Agency believes that surface air and soil gas monitoring, when coupled with subsurface monitoring, 

may be appropriate at some GS projects to ensure USDW protection. 

The final rule at §146.90(h) retains the allowance for surface air and soil gas monitoring at the discretion 

of the Director as a means of identifying leaks that may pose a risk to USDWs and informing emergency 

notification of a Class VI owner or operator and UIC Director in the event of a USDW endangerment, 

pursuant to requirements at §146.91(c). EPA clarifies that the decision to use surface monitoring and the 

selection of monitoring methods will be site-specific (e.g., may be influenced by geology, injection 

depth, and operational conditions) and must be based on potential risks to USDWs within the AoR. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: Section 146.87 (e), Logging, Sampling, and Testing Prior to Injection Well 

Operation, FR page 43538 

It is stated that, "Upon completion, but prior to operation, the owner or operator 

must conduct the following tests to verify hydrogeologic characteristics of the 

injection zone: 

(1) A pump test; or 

(2) Injectivity tests." 

A`pump' test can be either injecting or withdrawing fluid. The following 

suggested rewrite reduces redundancy: "Upon completion, but prior to operation, 

the owner or operator must conduct pumping tests to verify the hydraulic 

properties of the injection zone. These tests can take the form of : 

(1) withdrawal tests; or 

(2) injectivity tests." 

Response: EPA retained the requirements in the final rule as proposed because existing UIC program 

requirements use similar language and the tests and their purposes are understood by the regulated 

community. Additionally, the Agency believes that verification of hydrogeologic characterization will 

generate the same information as the suggested alternative language. 

Other EPA Comment Codes and Descriptions: 5700 2.12 Comments on the proposed duration of 

Class VI permits (seeking comment) 

Comment: Rule Provision: 144.36(a) 

API Comments: (a) Permits for Class I and V wells shall be effective for a fixed 

term not to exceed 10 years. UIC Permits for Class II AND III and VI wells 

shall be issued EFFECTIVE for a period up to the operating life of the 

Commenter Name: James Devine Letter ID: 0166

Commenter Organization: United States Geological Survey (USGS) Comment ID: 21350

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24136

233
facility. PERMITS FOR CLASS VI WELLS SHALL BE EFFECTIVE FOR THE PERIOD THROUGH 

SITE CLOSURE. 

Rationale: Permits are necessary for Class VI wells through the end of the post 

closure monitoring phase, which is consistent with the term site closure in the 

amended requirement. 

Response: EPA clarifies that the final GS rule specifies that Class VI permits will be issued for the 

operating life of the facility and the post-injection site care period (144.36(a)). The rule also adds a 

requirement that the Director review each Class VI permit at least every five years to determine whether 

it should be modified, revoked and reissued, terminated, or a minor modification made as provided in 

§§144.39, 144.40, or 144.41. The Director’s review will be informed by the owners’ or operators’ 

iterative reevaluation of the project. Specifically, the final rule includes a requirement that the AoR be 

reevaluated at least every five years, and also requires owners or operators to review and update the AoR 

and corrective action plan, the testing and monitoring plan, and the emergency and remedial response 

plan throughout the life of the project (146.84(e), 146.90(j), and 146.94(d)). Owners or operators must 

review each plan and identify necessary amendments or demonstrate to the Director that no amendment 

is needed. In no case can reviews occur less often than once every five years. The iterative process and 

subsequent plan reevaluations ensure that time and resources are committed to the most critical aspects 

of the permit in preventing endangerment to USDWs. 

Other EPA Comment Codes and Descriptions: 2064 1.5.3.2 Grandfathering construction of Class II 

wells (seeking comment) 

Comment: Rule Provision: 146.25 GEOLOGIC SEQUESTRATION IN OIL OR GAS RESERVOIRS 

WITHOUT 

ENHANCED RECOVERY OF OIL OR NATURAL GAS 

API Comments: WELLS USED FOR GEOLOGIC SEQUESTRATION AND MEETING THE 

CLASSIFICATION CRITERIA OF SECTION 146.5(B)(5) SHALL BE SUBJECT TO THE 

FOLLOWING 

REQUIREMENTS: 

(A) EXISTING WELLS THAT MEET OR EXCEED THE CONSTRUCTION REQUIREMENTS OF § 

146.22 

SHALL BE SUBJECT TO PART 146, SUBPART H [AS REVISED BY API] EXCEPT SECTIONS 

146.86 AND 146.87. 

(B) NEW WELLS MUST MET THE CONSTRUCTION REQUIREMENTS OF SECTION 146.22 

AND ARE 

SUBJECT TO PART 146, SUBPART H [AS REVISED BY API] EXCEPT SECTIONS 146.86 AND 

146.87 

Rationale: Details of what would be required of "Class IIB" wells are to be 

worked out during future discussions of the Multi-Stakeholder Discussion Group 

(MSDG). However, API offers this language which is consistent with changes API 

had suggested before discussions with the MSDG began (see Section 146.81(c)). 

These suggestions are - as noted - contingent on EPA‘s adoption of API‘s changes 

to Part 146, Subpart H. 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24139

234
Response: As described above regarding the suggested edit at 144.6, EPA did not make the suggested 

change. The Agency disagrees that wells injecting CO2 for the primary purpose of long-term storage 

should be regulated under Class II requirements because Class II requirements do not address the unique 

risks posed by GS while ensuring protection of USDWs from endangerment. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: API Comments: (b) This subpart applies to wells used to inject carbon dioxide 

EXCLUSIVELY for the purpose of geologic sequestration, i.e., the long-term 

containment of a gaseous, liquid or supercritical carbon dioxide stream in 

subsurface geologic formations. IT IS RECOGNIZED THAT SOME ACTIVITIES CONDUCTED 

UNDER CLASS II, INCLUDING CO2 BASED EOR OR EGR MAY SEQUESTER A PORTION OF 

THE 

CARBON DIOXIDE STREAM USED FOR EOR OR EGR. THIS SUBPART DOES NOT APPLY TO 

INJECTION OF A CARBON DIOXIDE STREAM FOR PURPOSES OF EOR OR EGR EVEN 

THOUGH 

GEOLOGIC SEQUESTRATION OF CARBON DIOXIDE MAY OCCUR DURING OR IN 

CONNECTION WITH 

EOR OR EGR OPERATIONS AND/OR ACTIVITIES. 

Rationale: See 144.6. Deleted "gaseous, liquid or supercritical" because it was 

added to the definition of CO2 stream. 

Response: As described above regarding the suggested edit at 144.6, EPA did not make the suggested 

change. The Agency disagrees that wells injecting CO2 for the primary purpose of long-term storage 

should be regulated under Class II requirements. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: Rule Provision: 146.81(c) 

API Comments: (c) This subpart applies to owners and operators of permit or 

rule-authorized Class I industrial, Class II, or Class V experimental carbon 

dioxide injection projects who seek to apply for a Class VI geologic 

sequestration permit for their well or wells. If the Director determines that 

USDWs will not be endangered, such wells are exempt, at the Director‘s 

discretion, from the casing and cementing requirements at §§ 146.86(b) and 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24140

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24141

235
146.87(a)(1) through (3). 

Rationale: The reference to Class II wells in section 146.81(c) is no longer 

needed due to addition of 146.25 . However, if EPA were not to adopt section 

146.25, API would suggest the following revisions: 

(c) This subpart applies to owners and operators of permit or rule-authorized 

Class I industrial, Class II WHO HAVE CEASED AND WILL NO LONGER CONTINUE EOR OR 

EGR OPERATIONS OR ACTIVITIES, or Class V experimental carbon dioxide injection 

projects who seek to apply for a Class VI geologic sequestration permit for 

their well or wells. If the Director determines that USDWs will not be 

endangered, such wells are exempt, at the Director‘s discretion, from the 

casing and cementing requirements at §§ 146.86(b) and 146.87(a)(1) through 

(3). CLASS VI REQUIREMENTS. CLASS II WELLS PERMITTED FOR CO2 INJECTION AND 

THAT HAVE DEMONSTRATED MIT ARE EXEMPT FROM THE REQUIREMENTS AT §§146.86 

AND 

146.87. 

The language allows for the transition of Class II wells to Class VI operations. 

These wells should be allowed to inject CO2 for storage based on their history 

of sound performance under the Class II program as demonstrated by MIT results. 

The language also allows the Director to exercise discretion to exempt other 

Class VI requirements. 

Response: As described above, EPA disagrees that wells injecting CO2 for the primary purpose of longterm storage should be regulated under Class II requirements. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: Rule Provision: 146.82(b) 

API Comments: (b) A surface map showing the PROPOSED LOCATIONS FOR the injection 

well(s) for which a permit is sought and the applicable area of review. Within 

the area of review, the map must show the number, or name and location of all 

KNOWN injection wells, producing wells, abandoned wells, plugged wells or dry 

holes, deep STRATAGRAPHIC boreholes, State or EPA approved subsurface cleanup 

sites, surface bodies of water, springs, mines (surface and subsurface), 

quarries, water wells and other pertinent surface features including structures 

intended for human occupancy and roads. The map should also show faults, if 

known or suspected. Only information of public record is required to be 

included on this map; 

Rationale: Faults are not shown on maps unless there is a surface expression of 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24151

236
the fault. Also, faults are detailed in (d) below and this language appears 

redundant. 

The word "known" needs to be added to remove any implication that an applicant 

has to conduct studies to determine the location of wells that are not currently 

documented in some fashion. 

Response: EPA did not delete “faults” from §146.82(b) because faults may have surface expressions 

that should be presented on submitted maps to complement the required cross section data. EPA is 

developing guidance on site characterization for GS projects to assist owners or operators and Directors 

in evaluating permit requirements and applications under §146.82. The guidance provides 

recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site 

as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the 

injection and confining zone. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Please see the final rule and the discussion of geologic site characterization in the preamble for 

additional information. 

EPA acknowledges that some smaller fractures may not be detectable during the site characterization 

process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or 

suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells and sites 

can mitigate the potential impacts of unidentified fractures. These include limitations on injection 

pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and 

assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible 

CO2 movement through high-permeability regions (i.e., faults and/or fractures) not detected in the initial 

site characterization. 

EPA believes that a determination about whether or what information may be necessary (for a specific 

GS project) is outside of the public record and will be site-specific and based on knowledge of the site, 

data availability, and data quality. For instance, in meeting the requirement to tabulate information on 

wells in the AoR, the Director has the discretion to require the owner or operator to supplement a data 

records search if there is reason to believe that the incompleteness of available information could 

compromise USDW protection from endangerment. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(c) 

API Comments: (c) A MAP DELINEATING the area of review based on UPON 

modeling, using ALL AVAILABLE data INCLUDING DATA obtained during logging and 

testing of the well and the formation as required by paragraphs (l), (r), and 

(s) of this section ANY WELLS IN THE AREA OF REVIEW 

Rationale: This appears to be related to a condition where a well is already 

drilled. This does not align with requesting information to receive a permit. 

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24152

237
available at the time the owner or operator develops their initial permit application. In response to 

comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this 

subpart so that the final regulation specifies separate requirements for information to be submitted with 

the permit application and before well construction is approved (at §146.82(a)) and information to be 

submitted before operation of the well is authorized (at §146.82(c)). 

The requirement to provide the final area of review based on modeling and data obtained during logging 

and testing is in the final GS rule at §146.82(c)(1). Please see the final rule and the discussion of 

geologic site characterization in the preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: Rule Provision: 146.82(d)(1) and (2) 

API Comments: (d) KNOWN information on the geologic structure and 

hydrogeologic RESERVOIR properties of the proposed storage site and 

overlying formations, including: 

(1) ISOPACH maps and OF THE PROPOSED INJECTION AND CONFINING 

ZONE(S), A STRUCTURAL CONTOUR MAP HUNG ON THE TOP OF THE PROPOSED 

INJECTION 

ZONE, AND AT LEAST TWO GEOLOGIC cross sections of the area of review SHOWING THE 

GEOLOGIC FORMATIONS FROM THE SURFACE TO TOTAL DEPTH. 

(2) Location, orientation, and properties of known or suspected 

SUBSURFACE faults and fractures that may transect the confining zone(s) in 

the area of review and a determination that they would not interfere with 

containment; 

Rationale: If the information is not known, it cannot be reported. "Reservoir" 

and changes to (1) and (2) are technical corrections. 

Fractures generally can’t be identified until a well is drilled and 

evaluated. Even then, only fractures in the immediate vicinity of the wellbore 

can be identified. 

This responsibility is best left with EPA. 

Rule Provision: 146.82(d)(3) 

API Comments: (3) Information on seismic history THAT HAVE AFFECTED THE PROPOSED 

AREA OF REVIEW, INCLUDING KNOWLEDGE OF PREVIOUS SEISMIC EVENTS, including the 

presence and depth of seismic sources and a determination that the seismicity 

would not interfere with containment; 

Rationale: Information on seismic history should have some degree of relevance 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24153

238
to the project. This responsibility is best left with EPA. 

Rule Provision: 146.82(d)(4) 

API Comments: (4) Data on the depth, areal extent, thickness, mineralogy, 

porosity, permeability and capillary RESERVOIR pressure of the injection and 

confining zone(s) WITHIN THE AREA OF REVIEW; including geologic/facies 

changes based on field data which may include geologic cores, outcrop data, 

seismic surveys, well logs, and names and lithologic descriptions; 

Rationale: Deleted capillary pressure because it is too hard to measure outside 

of the lab. Using sidewall cores, it may be difficult to determine capillary 

pressure. Additionally, full cores are not available until after the well being 

permitted is drilled. 

Rule Provision: 146.82(d)(5) 

API Comments: (5) KNOWN geomechanical information on fractures, stress, 

ductility, rock strength, and in situ fluid pressures within the confining 

zone(s) WITHIN THE AREA OF REVIEW; and 

Rationale not provided 

Response: EPA acknowledges that some smaller fractures may not be detectable during the site 

characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit 

data on known or suspected faults and fractures (i.e., not all fractures). Other requirements for GS 

injection wells and sites can mitigate the potential impacts of unidentified fractures. These include 

limitations on injection pressures to avoid propagation of existing fractures in the confining zone 

(§146.88(a)), collection and assessments of CO2 monitoring data at the site, and AoR reevaluations 

(§146.84(e)) to assess possible CO2 movement through high-permeability regions (i.e., faults and/or 

fractures) not detected in the initial site characterization. Regarding the requirement to determine 

capillary pressure, EPA recognizes that this information may not be available until after a well has been 

drilled. EPA revised §146.82 so that the final regulation specifies separate requirements for information 

to be submitted with the permit application and before well construction is approved (at §146.82(a)) and 

information to be submitted before operation of the well is authorized (at §146.82(c)). Final information 

on injection zone pressures would be required following drilling of the well, at §146.82(c)(4). 

EPA disagrees that information submitted with Class VI permit applications should be limited to known 

(i.e., previously available) data. Site-specific conditions may affect the suitability of a proposed site. 

Therefore the owner or operator must provide to the Director the necessary preliminary information to 

support a permit decision. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(e) 

API Comments: (e) A tabulation RECORD of all wells ARTIFICIAL 

PENETRATIONS within the area of review which penetrate THAT REACH the 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24154

239
injection or confining zone(s). Such data AS AVAILABLE IN THE PUBLIC RECORD must 

include a description of each well’s PENETRATION’S type, construction, date 

drilled, location, depth, record of plugging and/ or completion, and any 

additional information the Director may require; 

Rationale: Artificial penetrations is a more inclusive term. 

Rule Provision: 146.82(f) 

API Comments: (f) Maps and stratigraphic cross sections indicating the general 

vertical and lateral limits of all USDWs, water wells and springs within the 

area of review, their positions relative to the injection zone(s) and the 

direction of water movement, where known; POTENTIOMETRIC (WATER LEVEL) SURFACE 

MAP(S) OF EXISTING AQUIFERS BEING UTILIZED AS PRIVATE OR PUBLIC WATER 

SUPPLIES 

AND THE DIRECTION OF GROUNDWATER FLOW IN THESE AQUIFERS WITHIN THE AREA 

OF 

REVIEW. AT LEAST TWO GEOLOGIC CROSS SECTIONS SHOWING THE THICKNESS AND 

GENERAL 

VERTICAL AND LATERAL LIMITS OF ALL USDWS WITHIN THE AREA OF REVIEW. 

No rationale provided 

Rule Provision: 146.82(g) 

API Comments: (g) Baseline geochemical data on subsurface formations, 

including all USDWs in the area of review COMPILATION OF AVAILABLE GEOCHEMICAL 

DATA ON THE PROPOSED INJECTION ZONE AND NEAREST POROUS AND PERMEABLE 

FORMATION 

ABOVE THE CONFINING ZONE. 

Rationale: Limits the data to be submitted to available information and to the 

injection zone and the zone immediately above the confining zone which are the 

zones most likely to be monitored for potential CO2 leakage. 

Response: As described above, EPA disagrees that the information that is submitted to support a Class 

VI permit application should be limited to known/available data. 

EPA believes that a thorough understanding of the hydrogeologic conditions of all USDWs in the AoR 

is necessary, and disagrees with the suggested edits because the GS rule, as written, affords flexibility to 

owners or operators and Directors to tailor the site characterization process to the unique features of the 

site. EPA encourages owners or operators and Directors to collaborate and consult during site 

characterization to discuss information needs and ensure that all appropriate data to assess the suitability 

of the site are collected. The Director has the authority to request additional hydrogeologic data or other 

data on USDWs as well. 

The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on 

subsurface geologic formations, including all USDWs in the AoR, is appropriate and protective of 

USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate 

and transport model development (e.g., by providing appropriate input parameters), and provide 

information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. 

240
The baseline geochemical information will allow the owner or operator and permitting authority to 

evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid 

movement. 

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all 

USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining 

system and to serve as a baseline for future monitoring. The Director has the discretion to require 

geochemical analysis of additional subsurface zones if, in the Director's opinion, they are necessary for 

the protection of USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(h) 

API Comments: (h) Proposed operating data: (1) Average and maximum daily 

INJECTION rate and volume of the carbon dioxide stream; (2) Average and maximum 

SURFACE injection pressure; 

Rationale: Technical clarifications. 

Rule Provision: 146.82(k) 

API Comments: (k) Proposed stimulation program and a determination that 

stimulation will not interfere with containment; 

Rationale: This responsibility is best left with EPA. 

Rule Provision: 146.82(n) 

API Comments: (n) A WELLBORE schematic or other appropriate drawings of the 

surface and of the subsurface construction details of the well AND SURFACE 

WELLHEAD CONSTRUCTION. 

Rationale: Technical clarification. 

Rule Provision: 146.82(q) 

API Comments: q) The ANY status of corrective action on wells in the area of 

review; 

Rationale: Clarifies that wells not needing corrective action will not have a 

corrective action status. 

Response: EPA acknowledges the commenter’s support for parts of the requirements under 146.82. 

EPA disagrees with suggested technical clarifications regarding proposed operating data, needs for the 

stimulation program, and the status of corrective action. EPA adds that it is developing guidance for 

owners or operators on the geologic site characterization, AoR, and corrective action processes. These 

guidances will provide recommendations and clarify the intent of all required elements of a permit 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24155

241
application. The guidances can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3110 2.1.1 Proposed siting requirements (i.e., 

injection/confining zones, trapping mechanism) 

Comment: Rule Provision: 146.83(a)(2) 

API Comments: (2) A confining zone(s) that is LATERALLY CONTINUOUS AND free of 

KNOWN TRANSECTING, transmissive faults or fractures and of sufficient areal 

extent and integrity to contain the injected carbon dioxide stream and displaced 

formation fluids and allow injection at proposed maximum pressures and volumes 

without initiating or propagating fractures in the confining zone(s); and OVER 

AN AREA SUFFICIENT TO PREVENT THE MOVEMENT OF INJECTED OR DISPLACED 

FLUIDS INTO 

A USDW; 

Rationale: The proposed clarification keeps the emphasis on the non-endangerment 

of USDWs and limits the requirements to that which is known or can be readily 

determined. 

Response: The Agency believes that the requirement at §146.83(a)(2) that the confining zone be free of 

transmissive faults or fractures as written is appropriate for Class VI wells and is necessary to ensure 

containment of the injectate, and that requiring the confining zone to be free of transmissive faults 

maximizes protection of USDWs from endangerment. Class I hazardous waste injection well operators 

must also meet a similar requirement that the site is free of transmissive faults or fractures; they have 

successfully made such demonstrations in the past. EPA adds that the Director must evaluate all 

geologic data on the site to ensure protection of USDWs from endangerment before approving a site for 

a GS project. 

Other EPA Comment Codes and Descriptions: 3120 2.1.2 Need to identify additional confining and 

containment zones (seeking comment) 

Comment: Rule Provision: 146.83(b) 

API Comments: (b) At the Director‘s discretion, owners or operators of Class 

VI wells must identify and characterize additional zones that will impede 

vertical fluid movement, are free of faults and fractures that may interfere 

with containment, allow for pressure dissipation, and provide additional 

opportunities for monitoring, mitigation and remediation. 

Rationale: This paragraph creates a presumption that additional confining zones 

WILL be required. It is also redundant given the previous sections. 

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, 

secondary confining zones are required when the Director determines that these zones are needed to 

maximize the protection of USDWs from endangerment. EPA retains the requirement to identify

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24156

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24157

242
additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA 

believes that, in some situations, the presence of additional confining and containment zones above the 

primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further 

impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for 

monitoring, mitigation, and remediation. The Agency believes that providing the Director discretion will 

allow consideration of a range of sites for GS, based on site-specific conditions, and ensure USDW 

protection. EPA believes that requiring appropriate site characterization by the owner or operator (under 

§146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific 

geologic data will afford the greatest protection of USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rule Provision: 146.84(a) 

API Comments: (a) The area of review is the region surrounding the geologic 

sequestration project that may be impacted by the injection activity. The area 

of review is based on computational modeling that accounts for the physical and 

chemical properties of all phases of the injected carbon dioxide stream. THE 

SUBSURFACE THREE-DIMENSIONAL EXTENT OF THE CARBON DIOXIDE PLUME, 

ASSOCIATED 

PRESSURE FRONT, AS WELL AS THE OVERLYING FORMATIONS AND SURFACE AREA 

ABOVE THAT 

DELINEATED REGION. 

Rationale: Edits make this provision consistent with the definition of "Area of 

Review", which was revised. 

Response: EPA disagrees that the AoR definition needs to specifically include the overlying formations 

and surface area above the delineated region. The intent of the AoR, a long-standing concept within the 

UIC Program, is to delineate the surface area and all subsurface formations below it that may potentially 

be impacted by injection activity. Acceptable delineation models will provide predictions of CO2 fate 

and transport, as well as changes in formation pressure, in three dimensions as a function of time that 

can be used to delineate the subsurface storage site and the AoR. Although EPA disagrees with the 

commenter's suggested change, the Agency has carefully considered all comments on the AoR definition 

at 146.84(a) and modified it to read as follows: The region surrounding the geologic sequestration 

project where USDWs may be endangered by the injection activity. The area of review is delineated 

using computational modeling that accounts for the physical and chemical properties of all phases of the 

injected CO2 stream and is based on available site characterization, monitoring, and operational data. 

EPA believes that this definition is sufficiently broad and describes both the intent of the computational 

modeling and the relationship of the AoR to areas that are subject to the risks associated with injection. 

Other EPA Comment Codes and Descriptions: 3700 2.2.5 Comments on the requirement for an AoR 

and corrective action plan 

Comment: Rule Provision: 146.84(b) 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24158

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24159

243
API Comments: (b) The owner or operator of a Class VI well must prepare, 

maintain, and comply with a plan to delineate the area of review for a proposed 

geologic sequestration project, periodically reevaluate the delineation, and 

perform corrective action that meets the requirements of this section and is 

IN A MANNER AND AT A FREQUENCY acceptable to the Director. As a part of the 

permit application, for approval by the Director the owner or operator must 

submit an area of review and corrective action plan that includes the following 

information: 

Rationale: Clarification. 

Response: EPA disagrees with the suggested change, and is retaining the approach of setting a 

minimum fixed frequency for reevaluating the AoR but has, based on commenters' input, changed the 

frequency from ten years to at least every five years, as specified in §146.84(e). EPA agrees with 

commenters that site-specific information is an important factor in determining an appropriate AoR 

reevaluation frequency, and adds that the owner or operator's AoR and corrective action plan must 

describe the minimum fixed frequency for reevaluating the AoR and the site-specific conditions on 

which this frequency is based. EPA adds that the Director will evaluate the proposed plan in connection 

with a review of a vast amount of geologic and proposed operating data in determining whether to 

approve the plan. EPA is developing guidance describing recommended approaches to preparing all of 

the required GS project plans, which will address considerations for determining an appropriate AoR 

reevaluation schedule. The guidance will be available on EPA's web site at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3500 2.2.3 Area of Review Reevaluation (seeking 

comment); 3700 2.2.5 Comments on the requirement for an AoR and corrective action plan 

Comment: Rule Provision: 146.84(b)(2) 

API Comments: (2) A description of: 

(i) The minimum fixed frequency, not to exceed 10 years, the owner or operator 

proposes to reevaluate the area of review; 

(ii) The monitoring and operational conditions that would warrant a 

reevaluation of the area of review prior to the next scheduled reevaluation as 

determined by the minimum fixed frequency established in paragraph (b)(2)(i) of 

this section. 

(iii)(I) How monitoring and operational data (e.g., injection rate and 

pressure) will be used to inform an area of review reevaluation; and 

No rationale provided 

Rule Provision: 146.84(b)(2) 

API Comments: (iv II) How corrective action will be conducted to meet the 

requirements of paragraph (d) of this section, including what corrective action 

will be performed prior to injection and what, if any, portions of the area of 

review will have corrective action addressed on a phased basis and how the 

phasing will be determined; how corrective action will be adjusted if there are 

changes in the area of review; and how site access will be guaranteed

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24160

244
ARRANGED for future corrective action. 

Rationale: Future access cannot be guaranteed for an area in advance that may 

not even be within the boundaries of the AOR/ project. 

Response: EPA disagrees with the suggested changes. Regarding reevaluation of the AoR, EPA 

believes that periodic AoR reevaluation at a set frequency of at least every five years is necessary to 

ensure protection of USDWs from endangerment and address the uncertainties inherent in predictive 

modeling. Periodic AoR reevaluations at §146.84(e) ensure that a deliberate effort is made to verify, 

based on monitoring and operational data, that the CO2 plume is moving within the subsurface as 

predicted. EPA believes that less frequent reevaluations may not be sufficient to appropriately model 

plume and pressure front movement, establish conditions for corrective action, and ensure protection of 

USDWs from endangerment. 

EPA clarifies that if site monitoring data agrees with the existing AoR delineation, a model recalibration 

may not be necessary, and the AoR reevaluation may consist of a demonstration that the current AoR 

delineation is adequate based on site monitoring data. 

To the comment on site access, EPA clarifies that the purpose of the corrective action requirement at 

§146.84(d) is to ensure that all wells in the AoR that have the potential to cause the movement of CO2 

or other fluids into or between USDWs receive appropriate corrective action. In general, to meet this 

requirement, the owner or operator will most likely need to obtain the right of access to wells that may 

require corrective action, and demonstrate they have done this in their proposed AoR and corrective 

action plan. The final rule retains the requirement as proposed. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rule Provision: 146.84(c)(1) 

API Comments: (1) Predict, using computational modeling, the projected lateral 

and vertical migration of the carbon dioxide plume and formation fluids in the 

subsurface from the commencement of injection activities until the plume 

movement ceases, pressure differentials sufficient to cause the movement of 

injected fluids or formation fluids into a USDW are no longer present, or 

after FOR a fixed time period as determined by the Director. The model 

MODELING must: 

Rationale: Clarification. 

Rule Provision: 146.84(c)(1) 

API Comments: (i) Be based on detailed geologic data collected AVAILABLE to 

characterize the injection zone, confining zone and any additional zones; 

and anticipated operating data, including injection pressures, rates and total 

volumes over the proposed life of the geological sequestration project THE 

DURATION OF INJECTION; (ii) Take into account any RELEVANT geologic 

heterogeneities, AND data quality, and their possible impact on model 

predictions; and 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24161

245
Rationale: Allows the use of all available data, not just data collected 

specifically for this permit. 

Response: EPA has clarified the language in §146.84(c)(1) for the final rule. It now reads, “Predict, 

using existing site characterization, monitoring and operational data, and computational modeling, the 

projected lateral and vertical migration of the carbon dioxide plume and formation fluids in the 

subsurface from the commencement of injection activities until the plume movement ceases, until 

pressure differentials sufficient to cause the movement of injected fluids or formation fluids into a 

USDW are no longer present, or until the end of a fixed time period as determined by the Director.” 

The final rule retains §146.84(c)(1)(ii) as proposed, except that it now requires owners or operators to 

take into account other discontinuities in addition to geologic heterogeneities when determining the 

AoR. 

EPA disagrees that only the injection and confining zones should be included in AoR modeling of GS 

sites. EPA believes that the modeling should also take into account the possibility of displaced fluids or 

brines caused by a lateral and/or vertical pressure plume, and therefore it may be necessary to include 

additional zones along with the confining/injection zones to ensure the integrity of the confining zone 

and ultimately protect a USDW from endangerment. 

Other EPA Comment Codes and Descriptions: 3420 2.2.2.1 Scope of the inventory process (e.g., 

reliance on publicly available information, depth of wells) 

Comment: Rule Provision: 146.84(c)(2) 

API Comments: (2) Using methods approved by the Director, Identify all KNOWN 

ARTIFICIAL penetrations INTO THE CONFINING ZONE AVAILABLE IN THE PUBLIC 

RECORD, 

including active and abandoned wells and underground mines, in the area of 

review that may penetrate REACH the confining zone. Provide a description of 

each well‘s type, construction, date drilled, location, depth, record of 

plugging and/or completion, and any additional information the Director may 

require; and 

Rationale: Changed for consistency with earlier language. 

Response: EPA is retaining this requirement as proposed. EPA agrees with commenters that, for most 

GS sites, relying on database and other public records searches (i.e., of "known" artificial penetrations) 

will be sufficient to meet the requirements at §146.84(c)(2). However, the Agency recognizes that there 

may be situations where additional surveys or research to locate wells may be appropriate. For example, 

there may be cases where the Director may determine that ground or airborne surveys for wells are 

appropriate, e.g., if there is reason to believe, based on knowledge of the site or of available data, that 

the incompleteness of information on known wells could compromise USDW protection from 

endangerment. In order to preserve the Director's discretion to require an operator to supplement a 

records search, EPA did not make the suggested change. 

EPA clarifies that any well that penetrates the confining zone, even if it does not extend all the way 

through the confining formation, is to be included in the tabulation. The guidance describes EPA's 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24162

246
recommended approaches for the data to be considered in an initial AoR delineation, how to apply 

computational modeling to delineate the AoR, performing corrective action at GS sites, and, when 

appropriate, completing AoR reevaluations. The guidance will be available on EPA's web site at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: Rule Provision: 146.84(c)(3) 

API Comments: (3) Determine which abandoned wells IDENTIFIED IN 146.84 (C) (2) 

in the area of review have been plugged (as required by §146.92) in a manner 

that prevents the movement of carbon dioxide or associated FORMATION fluids 

that may endanger USDWs. 

Rationale: Remove as redundant. 

Response: EPA clarifies that the term "associated fluids" as proposed in §146.84(c)(3) refers to 

formation fluids, other injectates, etc. that may be present in the subsurface and affect movement of the 

CO2 plume and/or pressure front. EPA believes this terminology would incorporate any fluids in the 

subsurface that could potentially move through artificial penetrations and affect USDWs. EPA has 

revised the language at §146.84(c)(3) to read, "... carbon dioxide or other fluids that may endanger 

USDWs..." EPA disagrees that deleting the term area of review is necessary and has retained the term in 

the final rule language. 

Other EPA Comment Codes and Descriptions: 3460 2.2.2.3 Acceptable corrective action techniques 

for GS sites (e.g., cements) 

Comment: Rule Provision: 146.84(d) 

API Comments: (d) Owners or operators of Class VI wells must perform corrective 

action USING MATERIALS SUITABLE FOR USE WITH THE CARBON DIOXIDE STREAM AND 

FORMATION FLUIDS, on all wells in the area of review IDENTIFIED IN 146.84(C) 

(2) that are determined to need corrective action". using methods necessary to 

prevent the movement of fluid into or between USDWs including use of corrosion 

resistant materials, where appropriate. 

Rationale: Experience with CO2 based EOR strongly supports the use of many 

conventional materials that might not meet the technical definition of 

"corrosion resistant". 

Response: EPA revised the text at §146.84(d) to require the use of materials that are "compatible with 

the carbon dioxide stream." EPA believes this language change addresses commenters' concerns and is 

also consistent with other language regarding materials requirements in the GS rule. 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24163

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24164

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24165

247
Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: Rule Provision: 146.84(e) 

API Comments: (e) If monitoring data indicate an endangerment to USDWs, the 

owner or operator must notify the Director and cease operations as required by § 

146.94. 

Rationale: This is not needed since §146.94 already specifies the notification 

and cessation of injection. API suggests the removal of this language as 

unnecessarily duplicative. 

Response: Based on consideration of all public comments and other information, EPA deleted this 

provision from §146.84. The final rule now contains a provision in §146.91(c) that requires the owner or 

operator to report within 24 hours any evidence that the carbon dioxide stream or associated pressure 

front may cause an endangerment to a USDW. EPA believes this change consolidates reporting 

requirements in one place and provides additional clarity. 

Other EPA Comment Codes and Descriptions: 3530 2.2.3.1 AoR reevaluation frequency (seeking 

comment) 

Comment: Rule Provision: 146.84(f) 

API Comments: (f) At the minimum fixed frequency, not to exceed 10 years, as 

specified in the approved area of review and corrective action plan, or When 

monitoring and operational conditions warrant, owners or operators must: 

Rationale: Rather than a fixed time period, API recommends following a 

performance based approach that would be based on significant changes in 

injection parameters or anomalous monitoring results. 

Response: EPA believes that periodic AoR reevaluation at a set frequency is necessary to ensure 

protection of USDWs from endangerment and address the uncertainties inherent in predictive modeling. 

Periodic AoR reevaluations at §146.84(e) ensure that a deliberate effort is made to verify, based on 

monitoring and operational data, that the CO2 plume is moving within the subsurface as predicted. EPA 

believes that less frequent reevaluations may not be sufficient to appropriately model plume and 

pressure front movement, establish conditions for corrective action, and ensure protection of USDWs 

from endangerment. 

EPA clarifies that if site monitoring data agrees with the existing AoR delineation, a model recalibration 

may not be necessary, and the AoR reevaluation may consist of a demonstration that the current AoR 

delineation is adequate based on site monitoring data. 

Based on the comments received (including those by water associations, an energy company, 

associations, industries, states, and environmental groups), EPA has changed the minimum frequency 

for the AoR reevaluation from ten years to at least every five years. EPA believes that this revised 

frequency addresses commenters' concerns about the inherent uncertainties in modeling CO2 movement, 

the emerging nature of GS technology, risk-based targeting of monitoring activities, and the unique 

nature of CO2 GS. 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24166

248
Other EPA Comment Codes and Descriptions: 3700 2.2.5 Comments on the requirement for an AoR 

and corrective action plan 

Comment: Rule Provision: 146.84(f)(4) 

API Comments: (4) Submit an amended area of review and corrective action plan or 

demonstrate to the Director through monitoring data and modeling results that no 

amendment CHANGE to the area of review and corrective action plan is needed. 

Rationale: Clarification 

Response: EPA disagrees with the suggested changes and believes the proposed text is clear as written. 

For additional information on EPA's approach to AoR and corrective action, please see the final rule and 

preamble. 

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

responsibility requirements (40 CFR 146.85) 

Comment: Rule Provision: 146.85(a)(1) 

API Comments: (1) The Director receives WELL PLUGGING REPORT IDENTIFIED IN 

146.92(D) and approves OR COMPLETION OF the completed post-injection 

site care and site closure plan AS APPROPRIATE; and 

Rationale: Maintenance of the well plugging financial obligation until site 

closure is not necessary. The Director should have the authority to release the 

obligation once the well is plugged. 

Rule Provision: 146.85(b) 

API Comments: (b) The owner or operator must provide to the Director, at a 

frequency determined by the Director, BUT NO MORE THAN ANNUALLY, written updates 

of adjustments to the cost estimate to account for any amendments CHANGE to 

the area of review and corrective action plan (§146.84), the injection well 

plugging plan (§146.92), and the post-injection site care and site closure plan 

(§146.93). 

Rationale: Updates more frequent than annual is not justified. 

Rule Provision: 146.85(c) 

API Comments: (c) The owner or operator must notify the Director of adverse 

financial conditions such as bankruptcy, that may affect the ability to carry 

out injection well plugging and post-injection site care and site closure. 

Rationale: Clarification. 

Response: Owners or operators have the flexibility to choose from a variety of financial instruments to 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24167

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24168

249
meet their financial responsibility obligations. For example, owners or operators may use one or 

multiple financial responsibility instruments for well plugging and PISC (§146.85(a)(6)). However EPA 

will not allow for a separate financial responsibility demonstration for well plugging and PISC (i.e., a 

demonstration submitted prior to well plugging and the beginning of the post-injection site care period 

rather than with the permit application). A demonstration of financial responsibility for all phases of the 

GS project will be required prior to the issuance of a Class VI permit (§146.85(a)(5)(i)). 

To ensure that financial resources are available to protect USDWs from endangerment, the GS rule (at 

§146.85) identifies qualifying financial instruments, the time frames over which financial responsibility 

must be maintained, procedures for estimating the costs of activities covered by the financial 

instruments, procedures for notifying the Director of adverse financial conditions, and requirements for 

adjusting cost estimates to reflect changes to the project plans. 

In addition, on an annual basis, the owner or operator must adjust the cost estimate for inflation, increase 

or decrease the value of the financial instrument to match the cost estimate, and provide any updated 

information related to their financial responsibility instrument(s), or at any other time deemed 

appropriate by the Director. These annual reviews provide a mechanism for revising cost estimates up or 

down to account for changes in the project, including the execution of environmental obligations as 

phases of a GS project are completed. 

Regarding the suggested edit at §146.85(a)(1), EPA clarifies that the financial instrument the owner or 

operator provided to meet the requirements under §146.85 will be released when the phase of the project 

for which the instrument was required is complete and all financial obligations for that instrument have 

been met, pursuant to §146.85(b)(2) and §146.93. 

The GS rule, at §146.85(c), requires the owner or operator to have a detailed written estimate, in current 

dollars, of the cost of: performing corrective action on wells in the AoR, plugging the injection well(s), 

PISC and site closure, and emergency and remedial response. A cost estimate must be prepared 

separately for each of these activities and be based on the costs to the owner or operator of hiring a third 

party (who is neither a parent nor a subsidiary of the owner or operator) to perform the activities. 

However, EPA is not requiring independent third-party reviews of owner or operator cost estimates. 

EPA is developing guidance on financial responsibility for GS wells. The guidance will include a 

discussion on how best to estimate costs to assist Class VI well owners or operators, third party insurers 

or providers of financial instruments, and permitting authorities in developing estimates of the costs 

associated with various GS activities. The guidance is available on EPA's website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA did not make the proposed edits at §146.85(b) and (c), but did extensively revise and clarify the 

financial responsibility requirements. See the final GS rule and preamble for additional information on 

EPA's final approach. 

Other EPA Comment Codes and Descriptions: 5432 2.9.1.1 Need to adjust financial responsibility 

mechanisms (seeking comment) 

Comment: Rule Provision: 146.85(d) 

API Comments: (d) The operator must provide an adjustment of the cost estimate 

to the Director if the Director has reason to believe that original THE MOST 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24169

250
RECENT demonstration is no longer adequate to cover the cost of injection well 

plugging (as required by §146.92) and post-injection site care and site closure 

(as required by §146.93) 

Rationale: Clarification. 

Response: EPA agrees that it is important to periodically update cost estimates that support financial 

responsibility determinations. EPA clarifies that the GS rule, at §146.85(e), requires the owner or 

operator to provide annual updates to the cost estimate to account for any amendments to the AoR and 

corrective action plan, the injection well plugging plan, and the PISC and site closure plan. See the final 

rule and preamble for further discussion of EPA's final approach to financial responsibility. 

Other EPA Comment Codes and Descriptions: 3800 2.3 Proposed Injection Well Construction 

Requirements (40 CFR 146.86) 

Comment: Rule Provision: 146.86(a)(1) 

API Comments: (1) Prevent the movement of fluid into or between USDWs or into 

any unauthorized zones; CONTAINING ANY CONTAMINANT INTO USDWS, IF THE PRESENCE 

OF THAT CONTAMINANT MAY CAUSE A VIOLATION OF ANY PRIMARY DRINKING 

WATER 

REGULATION UNDER 40 CFR PART 142 OR MAY OTHERWISE ADVERSELY AFFECT THE 

HEALTH OF 

PERSONS.; 

Rationale: The proposed changes reflect the nonendangerment standard that is the 

basis of the UIC program. 

Response: EPA disagrees that the proposed language provided in §146.86 does not reflect the nonendangerment standard as required under the SDWA. EPA believes that protection of USDWs from 

endangerment and prevention of fluid movement between formations is paramount and the language as 

proposed meets the non-endangerment standard, therefore it is not necessary to make such edits. 

Appropriately designed and constructed wells are necessary to prevent endangerment to USDWs and 

maintain integrity of the well throughout the lifetime of a GS project. This is the foundation of the 

requirements for construction and pre-operational testing of Class VI wells at §§146.86 and 146.87. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment EPA has made many revisions to the GS rule. Please see the final rule and preamble for 

additional information. 

Other EPA Comment Codes and Descriptions: 3860 2.3.3 Well component degradation 

Comment: Rule Provision: 146.86(b)(1) 

API Comments: (1) Casing and cement or other materials used in the construction 

of each Class VI well must have sufficient structural strength and be designed 

for the operating life of the geologic sequestration project WELL. All well 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24170

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24171

251
materials must be compatible SUITABLE FOR USE with the fluids with which the 

materials may be expected to come into contact and meet or exceed TEST standards 

OR PRACTICES developed for such materials by the American Petroleum Institute, 

ASTM International, or comparable standards acceptable to the Director. The 

casing and cementing program must be designed to prevent the movement of fluids 

into or between USDWs. In order to allow the Director to determine and specify 

casing and cementing requirements, the owner or operator must provide the 

following information: 

Rationale: The life of a geologic sequestration project could be different than 

the life of the well. Class VI well design should be based on the life of the 

well. 

Response: EPA disagrees that the casing, cement, or other materials should only be designed for the 

period of the injection process rather than the life of the sequestration project. GS projects are 

anticipated to have long life spans in comparison to other types of deep injection wells. Not only must 

Class VI wells be able to function safely and properly over the lifespan of the GS project, but they must 

be constructed such that USDWs remain protected after well plugging. The requirements at §146.86 will 

ensure that the well can maintain integrity throughout the proposed life span of the project, including 

after the injection well is plugged and through the post-injection site care period and beyond. While the 

risk profile of a GS site will decrease following cessation of injection, EPA believes that Class VI wells 

must be designed to protect USDWs from endangerment for the life of the project. Furthermore, 

rigorous casing and cementing help ensure that the Class VI well will not serve as a conduit for 

movement of fluids associated with future injection operations. 

Other EPA Comment Codes and Descriptions: 3864 2.3.3.2 Use of corrosion-resistant cements 

(seeking comment) 

Comment: Rule Provision: 146.86(b)(1) 

API Comments: (v) Corrosiveness COMPOSITION of the carbon dioxide stream and 

formation fluids; 

Rationale: There is no method for measurement of "corrosiveness" of a CO2 

stream. The relevant information is the composition of the CO2 stream. 

Response: EPA clarifies that, although corrosiveness does not have a unit of measure, corrosiveness can 

be technically measured and described. Procedures that can identify corrosion (or the absence of 

corrosion) in a Class VI well provide valuable operational information that the Director needs to 

determine appropriate standards for the tubing and packer. 

Other EPA Comment Codes and Descriptions: 3860 2.3.3 Well component degradation 

Comment: Rule Provision: 146.86(b)(1) 

API Comments: (vi) Down-hole temperatures AND PRESSURES; 

(viii) Type or grade of cement AND ADDITIVES; and 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24172

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24173

252
Rationale: Technical clarification. 

Response: EPA agrees with the suggestion that §146.86(b)(1)(viii) be revised to also address cement 

additives. In the final GS rule, the subparagraph reads as follows: "Type or grade of cement and cement 

additives." 

EPA clarifies that information on down-hole pressures is required at §146.86(b)(1)(ii). 

Other EPA Comment Codes and Descriptions: 3822 2.3.1.1 Depth of surface casing (seeking 

comment) 

Comment: Rule Provision: 146.86(b)(2) 

API Comments: (2) Surface casing must extend through the base of the lowermost 

USDW ABOVE THE INJECTION ZONE and be cemented to the surface. 

Rationale: In some parts of the US the USDW is very deep and this standard may 

preclude geologic sequestration in these areas. 

Response: EPA disagrees with the suggested edit or that the surface casing requirements in the GS rule 

preclude injection below deep USDWs. The final GS rule at §146.86(b)(2) requires that surface casing 

extend through the base of the lowermost USDW and be cemented to the surface through the use of 

single or multiple strings of casing and cement. It does not, however, specify how cementing must be 

accomplished, and gives flexibility to the owner or operator to propose alternate methods- to provide a 

sufficient amount of cement to meet the standard that USDWs are protected from endangerment. EPA 

notes that there are many potential ways to meet the requirement, such as the use of staged cementing. 

EPA recognizes concerns regarding construction of Class VI wells where the lowermost USDW is very 

deep. To further address comments on deep injection wells, the final GS rule at §146.95 includes 

requirements for owners or operators that seek a waiver of the injection depth requirements. Owners or 

operators of wells operating under injection depth waivers must comply with additional construction 

requirements to ensure that wells used to inject above or between USDWs are protective. See the 

discussion of the waiver approach in the preamble to the final GS rule for additional information. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: Rule Provision: 146.86(b)(3) 

API Comments: (3) At least one long string casing, using a sufficient number 

of centralizers SET IN A MANNER SO AS TO CREATE A CEMENT BOND THROUGH THE 

INJECTION AND CONFINING ZONE(S). THE LONG STRING CASING must extend to the 

injection zone and must be cemented ISOLATED by circulating cement to the 

surface in one or more stages. PLACING CEMENT AND/OR OTHER ISOLATION 

TECHNOLOGIES AS NECESSARY TO PROVIDE ADEQUATE ISOLATION OF THE INJECTION 

ZONE 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24174

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24175

253
AND PROVIDE FOR PROTECTION OF USDWS. 

Rationale: Cementing to surface is not necessary to protect USDWs, and may have 

negative consequences, as follows. Cement to surface would eliminate the ability 

to monitor pressures in this annulus and would limit flexibility of remedial 

options. As revised, the proposal would allow for application and development of 

alternative technologies. See API RP90 for description of risk-based approach 

for managing situations involving annular casing pressure. Industry experience 

with CO2 EOR under the Class II program demonstrates the effectiveness of 

existing cementing procedures. 

Rule Provision: 146.86(b)(4) 

API Comments: (4) Circulation of cement may be accomplished by staging. The 

Director may approve an alternative method of cementing in cases where the 

cement cannot be recirculated to the surface, provided the owner or operator can 

demonstrate by using logs that the cement does not allow fluid movement behind 

the well bore. 

Rationale: Same as above 

Response: EPA disagrees with the suggested edits. EPA believes that the requirements for long-string 

casing are appropriate and offer appropriate flexibility: §146.86(b)(3) requires that the long-string casing 

extend to the injection zone and be cemented by circulating cement to the surface in one or more stages. 

It does not, however, specify how cementing would be accomplished, and gives flexibility to the owner 

or operator to propose alternate methods to provide a sufficient amount of cement to meet the standard 

that USDWs are protected from endangerment, subject to the approval of the Director. 

EPA stresses that protection of USDWs is the primary mission and mandate of the UIC program and the 

purpose of all requirements for injection wells. Any injection activity must be demonstrated to not 

endanger USDWs, regardless of their depth, and if such non-endangerment cannot be shown, then the 

activity will not be allowed under UIC requirements or the SDWA. 

EPA disagrees that the requirement at §146.86(b)(4) should be deleted. Section 146.86(b)(4) of the final 

rule allows alternate methods of staging the cement, at the Director's discretion, provided the owner or 

operator can demonstrate using logs that the cement does not allow fluid movement behind the wellbore.

EPA does not believe that the cementing requirements at §146.86 would prevent monitoring, operation, 

and remediation of Class VI wells. Cementing of deep wells has been performed successfully in the past 

by owners or operators of Class I hazardous and Class I municipal waste disposal wells. Some of these 

wells, which must meet the same cementing and casing requirements as Class VI wells, are up to 12,000 

feet deep and have been successfully cemented in a manner that maintains integrity and allows for all 

required well testing, operation, and remediation (EPA, 2001). See the discussion of Class VI well 

construction requirements in the preamble to the final GS rule for additional information. Additionally, 

EPA is developing guidance on the construction of Class VI wells. This guidance will be available on 

EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3864 2.3.3.2 Use of corrosion-resistant cements 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24176

254
(seeking comment) 

Comment: Rule Provision: 146.86(b)(5) 

API Comments: (5) Cement and cement additives must be compatible SUITABLE 

FOR USE with the carbon dioxide stream and formation fluids and of sufficient 

quality and quantity to maintain integrity over the design OPERATING life of 

the geologic sequestration project WELL. The integrity and location of the 

cement shall be verified using technology capable of evaluating cement quality 

radially and identifying the location of channels to ensure that USDWs are not 

endangered. 

Rationale: Experience with CO2 EOR under the Class II program demonstrates the 

effectiveness of existing cementing materials and procedures. Standard API 

cements have been used in numerous CO2 EOR operations with no adverse 

consequences. Refer to the citations within EPA‘s proposed rule 73 FR 43532- 

43533: Carey et al., (2007), Crow et al., (2008), and Meyer, J.P (2007). 

Response: EPA disagrees that the casing, cement, or other materials should only be designed for the 

period of the injection process rather than the life of the sequestration project. GS projects are 

anticipated to have long life spans in comparison to other types of deep injection wells. Not only must 

Class VI wells be able to function safely and properly over the lifespan of the GS project, but they must 

be constructed such that USDWs remain protected after well plugging. The requirements at §146.86 will 

ensure that the well can maintain integrity throughout the proposed life span of the project, including 

after the injection well is plugged and through the post-injection site care period and beyond. While the 

risk profile of a GS site will decrease following cessation of injection, EPA believes that Class VI wells 

must be designed to protect USDWs from endangerment for the life of the project. Furthermore, 

rigorous casing and cementing help ensure that the Class VI well will not serve as a conduit for 

movement of fluids associated with future injection operations. 

EPA recognizes that the oil and gas industry has decades of experience injecting CO2 and has 

demonstrated the effectiveness of existing cementing materials and procedures. The final GS rule, at 

§146.86(b)(1), specifies that all casing and cementing or other materials used in the construction of 

Class VI wells must meet or exceed standards developed for such materials by the American Petroleum 

Institute, ASTM International, or comparable standards acceptable to the Director. This requirement 

invokes the expertise of these bodies to ensure that the requirements for construction of Class VI wells 

reflect the state of the art in well construction technology. See the discussion of Class VI well 

construction requirements in the preamble to the final GS rule for additional information. Additionally, 

EPA is developing guidance on the construction of Class VI wells. This guidance will be available on 

EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3826 2.3.1.3 Packer requirements (seeking comment) 

Comment: Rule Provision: 146.86(c)(2) 

API Comments: (ii) COMPOSITION of the carbon dioxide stream. (chemical 

content, corrosiveness, temperature, and density); 

Rationale: There is no method for measurement of "corrosiveness" of a CO2 

stream. The relevant information is the composition, not characteristics, of the 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24177

255
CO2 stream. The composition of the CO2 stream is more relevant to the design of 

a tubing and packer system. 

Rule Provision: 146.86(c)(2) 

API Comments: (iii) MAXIMUM PROPOSED Injection temperature and pressure; 

(iv) MAXIMUM PROPOSED Annular pressure; 

(v) MAXIMUM PROPOSED Injection rate (intermittent or continuous) and volume of 

the carbon dioxide stream; 

Rationale: Technical corrections. 

Response: As written, the text at §146.86(c)(3)(ii) accounts for all characteristics of the CO2 that could 

affect the performance of the tubing and packer, including the chemical content, corrosiveness, 

temperature, and density. The suggested revision to refer to CO2 "composition" would be less precise. 

EPA clarifies that, although corrosiveness does not have a unit of measure, corrosiveness can be 

technically measured and described. Procedures that can identify corrosion (or the absence of corrosion) 

in a Class VI well provide valuable operational information that the Director needs to determine 

appropriate standards for the tubing and packer. 

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA has revised §146.86(c)(3)(iii) and (iv) to reference the maximum proposed injection pressure and 

maximum proposed annular pressure, respectively. EPA has revised §146.86(c)(3)(v) to read "proposed 

injection rate (intermittent or continuous), and volume and/or mass of the carbon dioxide stream." EPA 

believes that reference to the continuous injection rate would be duplicative of the maximum rate. EPA 

believes that considering the maximum injection and annular pressure would be more protective. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a) 

API Comments: (a) During the drilling and construction of a Class VI injection 

well, the owner or operator must run appropriate logs, surveys and tests to 

determine or verify the depth, thickness, porosity, permeability, and lithology 

of, and the salinity of any formation fluids in, all relevant geologic 

formations to assure EVALUATE conformance with the injection well 

construction requirements under §146.86, and to establish accurate baseline data 

against which future measurements may be compared. The owner or operator must 

submit to the Director a descriptive report prepared by a knowledgeable log 

analyst that includes an interpretation of the results of such logs and tests. 

At a minimum, such logs and tests must include: THE DIRECTOR MAY REQUIRE 

SUCH LOGS AND TESTS AS MAY BE NEEDED AFTER TAKING INTO ACCOUNT THE 

AVAILABILITY 

OF SIMILAR DATA IN THE AREA OF THE DRILLING SITE, THE CONSTRUCTION PLAN, 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24178

256
AND THE 

NEED FOR ADDITIONAL INFORMATION THAT MAY ARISE FROM TIME TO TIME AS THE 

CONSTRUCTION OF THE WELL PROGRESSES AND THESE MAY INCLUDE THE 

FOLLOWING: 

Rationale: Obtaining the geologic information will not assure conformance 

with well construction requirements, just measure or evaluate it. 

In well defined areas, these evaluations are frequently unnecessary. The 

Director should have discretion to select the appropriate requirements necessary 

to obtain sufficient baseline data and information. For example, in an area 

where a number of wells are being drilled, the logging of surface hole yields 

little useful additional information. 

In particular, this change would allow the Director to reduce the requirements 

when multiple wells are installed for a project. 

Response: EPA believes that all logs, surveys, and tests listed at §146.87(a) are necessary to verify 

information about the injection and confining zones and ensure that the well is being drilled and cased as 

approved, and has mechanical integrity. This information is needed to demonstrate that the well can be 

operated and tested in a manner that protects USDWs from endangerment. While the tests do provide 

information on some of the same items, each test provides unique pieces of information that build on 

each other and allow for interpretations not possible with a single test. 

EPA notes that the Director has the discretion at §146.87(a)(5) to approve alternative methods that 

provide equivalent or better information, and the Director may accept information on cores of the 

injection and confining zones from nearby wells if the owner or operator can demonstrate that such 

cores are representative of conditions at the well in question and core retrieval is not possible, as 

specified at §146.87(b). EPA believes that logs and tests must be performed on each well drilled 

regardless of existing information about the area to account for the complexity of CO2 injection well 

construction and the buoyancy of CO2. Existing lithologic and geologic information may lack the details 

needed for site-specific well design and the geology needed to support protection of USDWs from 

endangerment. 

Other EPA Comment Codes and Descriptions: 4110 2.4.1.1 Injection pressure limitations 

Comment: Rule Provision: 146.88(a) 

API Comments: (a) Except during stimulation, the owner or operator must ensure 

that injection pressure does not exceed 90 percent of the fracture pressure of 

the injection zone so as to assure that the injection does not initiate new 

fractures or propagate existing fractures in the injection zone. In no case may 

injection pressure initiate fractures in the confining zone(s) or cause the 

movement of injection or formation fluids that endangers a USDW. (A) THE OWNER 

OR OPERATOR MUST COMPLY WITH A MAXIMUM INJECTION PRESSURE LIMIT 

APPROVED BY THE 

DIRECTOR AND SPECIFIED IN THE PERMIT. IN APPROVING A MAXIMUM INJECTION 

PRESSURE 

LIMIT, THE DIRECTOR SHALL CONSIDER THE RESULTS OF WELL TESTS AND, WHERE 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24180

257
APPROPRIATE, GEOMECHANICAL OR OTHER STUDIES THAT ASSESS THE RISKS OF 

TENSILE 

FAILURE AND SHEAR FAILURE. THE DIRECTOR SHALL APPROVE LIMITS THAT, WITH A 

REASONABLE DEGREE OF CERTAINTY, WILL AVOID INITIATION OR PROPAGATION OF 

FRACTURES IN THE CONFINING ZONE OR CAUSE OTHERWISE NON-TRANSMISSIVE 

FAULTS 

TRANSECTING THE CONFINING ZONE TO BECOME TRANSMISSIVE. IN NO CASE MAY 

INJECTION 

PRESSURE CAUSE MOVEMENT OF INJECTION OR FORMATION FLUIDS IN A MANNER 

PROHIBITED 

BY 40 CFR PART 144.12(A) 

Rationale: API is concerned about three aspects of proposed section 146.88(a), 

governing injection pressure limitations. First, it "restricts" fractures in the 

injection zone "except during stimulation" rather than focusing on maintaining 

the integrity of the confining zone, which is what really matters for protecting 

USDWs. Second, it fails to refer specifically to the full range of potential 

geomechanical failure modes potentially posed by operations at a particular 

site. Third, the type of geomechanical risk that is addressed (initiation or 

propagation of fractures), is dealt with in a potentially arbitrary fashion (the 

90% of fracture pressure limit), which may not be appropriate in all cases. 

The MSDG‘s recommended language addresses these concerns by focusing on 

maintaining the integrity of the confining zone and including tensile failure 

and shear failure as transmissivity concerns. It calls for additional 

geomechanical studies of tensile failure and shear failure only "where 

appropriate" because there will be locations where experience or existing 

information will provide sufficient evidence to avoid the need for additional 

studies. The need for conducting additional tests and for determining which 

tests would be acceptable is left to the Director‘s discretion. 

Response: EPA notes that because determination of the injection pressure limit is based on the fracture 

pressure of the injection zone, the limit is site-specific and not arbitrary. EPA emphasizes that injection 

pressure limits are important to protect against fracturing of the confining zone, and that the requirement 

at §146.88(a) that the pressure in the injection zone not exceed 90 percent of the fracture pressure 

provides a margin of safety in the well operation and protects USDWs from endangerment. If the 

Director determines, based on a review of the information collected as part of site characterization, that a 

lower injection pressure limitation is appropriate in order to prevent endangerment of USDWs, the 

Director has the authority to set a lower limit in the operating permit than the limit established in the 

rule. 

EPA notes that during the site characterization process, owners or operators must submit data about the 

geology of the site, as specified at §146.82(a), including data on known or suspected faults and fractures 

and geomechanical information on fractures, stress, ductility, rock strength, and in situ fluid pressures 

within the confining zone. The Director will use these data to determine appropriate limits on injection. 

In response to the concern about reopening of faults at lower pressures than 90 percent of fracture 

pressure, EPA believes that the requirement for the owner or operator to submit data on known or 

suspected faults and fractures and information on the seismic history of the site will inform the 

determination of an appropriate pressure limitation in the permit. Any sites with the potential for 

reopening or reactivation of faults or unacceptable seismic risk that could otherwise interfere with 

258
containment will not be permitted as GS sites.

EPA is developing guidance on site characterization for GS projects to assist owners or operators in 

meeting the requirements of §146.82 and to assist Directors in evaluating permit applications. The 

guidance will describe recommended approaches for characterizing the regional geology and 

hydrogeology of a proposed site and performing the necessary geochemical, geomechanical, and 

geophysical analyses of the injection and confining zone. EPA is also developing guidance for primacy 

agencies that will include recommended approaches for evaluating owner or operator-submitted data in 

setting permit conditions. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4100 2.4.1 Injection parameters 

Comment: Rule Provision: 146.88(b) 

API Comments: Injection OF THE CO2 STREAM between the outermost casing protecting USDWSs 

and the well bore is prohibited. 

Rationale: Routine injection into zones other than the target interval(s) should be prohibited; however, 

wording of this requirement is not clear as to which interval is being addressed. An absolute prohibition 

on injection into this annulus may also limit diagnostic options that could be useful. 

Response: EPA retains the provision as proposed, and clarifies that injection between the casing and the 

well bore is prohibited. This is consistent with requirements for other injection well classes. 

Other EPA Comment Codes and Descriptions: 4100 2.4.1 Injection parameters 

Comment: Rule Provision: 146.88(c) 

API Comments: (c) The owner or operator must fill the annulus between the tubing 

and the long string casing with a non-corrosive fluid approved by the Director. 

The owner or operator must maintain on the annulus a pressure that exceeds the 

operating injection pressure, unless the Director determines that such 

requirement might harm the integrity of the well. A POSITIVE PRESSURE ON THE 

ANNULUS. 

Rationale: Industry experience with the Class II UIC program does not support 

this requirement. 

Positive annular pressure that exceeds the operating injection pressure is not 

necessary because a leak from tubing to annulus does not have the same 

implications as in a Class I hazardous situation. 

Response: EPA believes that maintaining an annulus pressure that is higher than the injection pressure, 

as required at §146.88(c), will ensure that if there are leaks in the tubing, the annulus fluid will move 

into the tubing, rather than the injectate moving out of the tubing and potentially along the outside of the 

well. EPA believes this requirement is appropriate for Class VI wells given the potential high volumes 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24181

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24182

259
and supercritical nature of the CO2 injectate, potential geomechanical stresses in the wellbore, and the 

potential for movement of the CO2 in the event of a mechanical integrity loss. 

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells 

(seeking comment) 

Comment: Rule Provision: 146.88(e) 

API Comments: (e) The owner or operator must install and use continuous 

recording devices to monitor: the injection pressure; the rate, volume, and 

temperature of the carbon dioxide stream and. THE OWNER OR OPERATOR MUST 

REGULARLY MONITOR the pressure on the annulus between the tubing and the long 

string casing and annulus fluid volume and. THE OWNER OR OPERATOR must 

install and use alarms and automatic down-hole shut-off systems, designed to 

alert the operator and shutin the well when operating parameters such as 

injection rate, injection pressure, or other parameters approved by the Director 

diverge beyond ranges and/or gradients specified in the permit; 

Rationale: Over-pressure protection is best achieved by ensuring 

compatibility of the casing/tubing material design strength with the surface 

injection (compression) system. Down-hole shut-in devices are not appropriate 

for this application. These devises are installed in the tubing string and are 

typically near the surface of the well. They‘re intended to seal the tubing in 

the event of catastrophic failure of the wellhead. These devises would provide 

little if any protection to USDWs. Is not practicable to install these devises 

deep within the well (e.g. shortly above the packer). Additionally these devises 

create a restriction on running other tools like logging tools in the well and 

therefore could limit an operators ability to do required monitoring and 

diagnostic work. Lastly, these devises require periodic testing and maintenance 

which could require either pulling the device by wireline or by pulling the 

entire tubing string depending on the type of device installed. Either of these 

activities would be disruptive and costly to the overall project operations. 

A more appropriate approach would be installation of landing nipples at 

appropriate points in the tubing string which would allow use of wireline 

retrievable plugs when needed. 

Response: EPA acknowledges that proper design of the well, including appropriate materials and 

emplacement of casing and tubing, is essential to proper operation of Class VI wells. Such design, 

however, does not eliminate the possibility of failure, e.g., due to over-pressurization as suggested by the 

commenter. EPA believes that a multiple-barrier approach, which includes appropriate well design as 

required at §146.86, suitable injection pressure limits as required at §146.88(a), and automatic shut-off 

systems, as required at §146.88(e), is necessary to ensure protection of USDWs from endangerment 

from the risks associated with CO2 GS. 

Landing nipples, which are machined portions of the tubing that allow the seating of components–such 

as safety valves—at a later time, can be used to deploy safety valves after the initial well completion. 

EPA believes, however, that if the shut-off system is not deployed until the failure occurs, CO2 will be 

free to flow out of the well until the shut-off valve is deployed. Since installing the new shut-off system 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24183

260
will require getting the device to the site, setting up a rig, and deploying the device down the well, a 

significant amount of time could elapse following an adverse event before the well is sealed. EPA 

believes that the risks of uncontrolled CO2 flow are too great to be allowed for such a length of time. 

As described above, EPA will not require automatic down-hole shut-off devices for onshore Class VI 

wells since it is not necessary in all cases to ensure protection of USDWs from endangerment. Instead, 

the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells install 

automatic surface shut-off devices. The rule affords Director's discretion to mandate automatic downhole shut-off devices in onshore situations that may warrant their use. The rule requires, at §146.88(e)

(3), that owners or operators of offshore wells within State territorial waters install automatic down-hole 

shut-off systems. EPA believes that these requirements at §146.88(e) ensure that proper precautions are 

taken to prevent subsurface fluid movement and ensure protection of USDWs. 

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells 

(seeking comment) 

Comment: Rule Provision: 146.88(f) 

API Comments: (f) If aN down-hole automatic shutdown is triggered or a loss 

of mechanical integrity is discovered, the owner or operator must immediately 

investigate and identify as expeditiously as possible the cause of the 

shutoff. If, upon such investigation, the well appears to be lacking 

mechanical integrity, or if monitoring required under paragraph (e) of this 

section otherwise indicates that the well may be lacking mechanical integrity, 

the owner or operator must: 

Rationale: Technical clarification given changes above. 

Response: As described above, EPA will not require automatic down-hole shut-off devices for onshore 

Class VI wells since it is not necessary in all cases to ensure protection of USDWs from endangerment. 

Instead, the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells 

install automatic surface shut-off devices. The rule affords Director's discretion to mandate automatic 

down-hole shut-off devices in onshore situations that may warrant their use. The rule requires, at 

§146.88(e)(3), that owners or operators of offshore wells within State territorial waters install automatic 

down-hole shut-off systems. Please see the final rule and preamble for additional information on EPA's 

final approach. 

Other EPA Comment Codes and Descriptions: 4000 2.4 Proposed Injection Well Operating 

Requirements (40 CFR 146.88) 

Comment: Rule Provision: 146.88(f)(3) 

API Comments: (3) Notify the Director within 24 hours OF DISCOVERY; 

No rationale provided 

Response: The final rule text at §146.88(f) now reads, "If a shutdown (i.e., down-hole or at the surface) 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24184

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24185

261
is triggered or a loss of mechanical integrity is discovered." Therefore the notice required at §146.88(f)

(3) must be provided within 24 hours of an automatic shut-off device being triggered or a loss of 

mechanical integrity being discovered. EPA believes this provision is necessary to ensure timely 

response to potential USDW endangerment. 

Other EPA Comment Codes and Descriptions: 4520 2.5.1 Continuous internal mechanical integrity 

monitoring (seeking comment); 4720 2.7.2 Operational recordkeeping and reporting 

Comment: Rule Provision: 146.89(b) 

API Comments: (b) To evaluate the absence of significant leaks under paragraph 

(a)(1) of this section, owners or operators must, following an initial annulus 

pressure test, continuously monitor AND RECORD AT LEAST DAILY, ANNULUS PRESSURE 

AND VOLUMES OF PACKER FLUID INJECTED OR REMOVED FROM injection pressure, rate, 

injected volumes, and pressure on the annulus between THE tubing and long 

stem STRING casing and annulus fluid volume as specified in §146.88 (e); 

Rationale: Technical clarification. 

Response: EPA agrees with the commenter regarding the importance of demonstrating internal 

mechanical integrity (MI), but disagrees with the suggested changes. Class VI injection wells must be 

equipped with dedicated computer-based continuous pressure monitoring devices in concert with the 

shut-off systems required for GS wells, which typically take readings several times per second (i.e., 

more frequently than daily) and record them electronically in a computer system. See §146.88. For 

additional information, please see the discussion of MITs in the final rule preamble. 

EPA also disagrees that it is necessary to report volumes of packer fluid injected or removed. EPA 

agrees with the commenter that recording annulus fluid volume may not be appropriate. EPA believes 

that knowing annulus fluid volume (146.88(e)) is a necessary component of monitoring well mechanical 

integrity, but believes that knowing the annulus fluid volume added is sufficient to meet the intent of the 

requirement. The final GS rule requires that owners or operators use continuous recording devices to 

monitor injection pressure, rate, and volume, as well as the pressure on the annulus between the tubing 

and the long string casing. It also modifies the requirement in the proposed rule to continuously monitor 

annulus fluid volume; it now requires recording of annulus fluid volume added. See §§146.88(e); 146.89

(b); and 146.90 (b). 

The final rule includes the suggested change from “long-stem” to “long-string” casing. 

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: Rule Provision: 146.90(b) 

API Comments: (b) Installation and use, except during well workovers as defined 

in §146.868(d), of continuous recording MONITORING devices (INCLUDING DIGITAL 

DEVICES CAPTURING PERIODIC DATA) to monitor injection pressure, rate and volume; 

AND RECORD AT LEAST DAILY the pressure on the annulus between the tubing and the 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24186

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24188

262
long string casing; and the annulus fluid volume;

Rationale: §146.86(d) does not exist; perhaps §146.88(d) is what was apparently 

intended. 

There is concern regarding what constitutes continuous monitoring. Industry 

agrees that regular monitoring of the parameters identified by EPA is 

appropriate. Our experience with CO2 EOR strongly shows that daily monitoring of 

most of these parameters is adequate (exceptions to this would be on a sitespecific basis). Recording should generally be done on a daily basis and 

reporting on a semi-annually basis. 

Response: EPA believes that a monitoring regime that includes continuous pressure monitoring of GS 

wells, as required at §146.88(e), is important and appropriate because the potentially corrosive nature of 

CO2 streams in the presence of water makes it critical to immediately identify corrosion-related well 

mechanical integrity loss. 

Regarding the question of what constitutes continuous monitoring, EPA expects that Class VI injection 

wells under §146.88(e) will be equipped with dedicated computer-based continuous pressure monitoring 

devices (in concert with the Director-approved shut-off systems required for GS wells), which typically 

take readings several times per second and record them electronically in a computer system. EPA did 

not specify the types of devices in the final rule, however. 

EPA adds that the final GS rule references §146.88(e), as the commenter suggests. 

Other EPA Comment Codes and Descriptions: 4630 2.6.3 Corrosion monitoring 

Comment: Rule Provision: 146.90(c) 

API Comments: (c) WHERE CONDITIONS WARRANT, corrosion monitoring of the well 

materials for loss of mass, thickness, cracking, pitting and other signs of 

corrosion must be performed on a AND RECORDED AT LEAST quarterly basis 

WHICH MAY BE MODIFIED TO BE LESS FREQUENT AS APPROVED BY THE DIRECTOR 

BASED ON 

CONSTRUCTION MATERIALS, OPERATING CONDITIONS, AND MONITORING HISTORY to 

ensure 

that the well components meet the minimum standards for material strength and 

performance set forth in §146.86(b) by: 

Rationale: Technical correction. 

API questions the need for corrosion monitoring of most injected CO2 streams 

since they will typically be nearly pure and dry thus having no corrosive 

properties. Industry experience with production, transportation, and injection 

of dry CO2 strongly illustrates the non-corrosive nature of this type of CO2 

stream. 

Response: EPA believes that corrosion monitoring is warranted and necessary for all Class VI wells in 

order to protect USDWs. CO2 in the presence of water (including water with NOx, SOx, and H2S 

impurities) can be corrosive to well materials and cements. Thus, although a CO2 stream may be dry, 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24189

263
the potential for corrosion of well materials down-hole, where the injectate can potentially mix with 

water in the target formation, must be considered. 

Several laboratory studies and a limited number of field studies have investigated and characterized the 

effects of carbonic acid on well materials. Laboratory studies (e.g., Kutchko et al., 2007; Kutchko et al., 

2008) consistently identify alterations (typically carbonation) of cement as the result of interactions 

between cement and CO2-saturated brine. 

Currently, there are only a few analyses of cement from wells that have been in prolonged contact with 

CO2 in actual field (down-hole) conditions. Evaluation of cement from a well at the Scurry Area 

Canyon Reef Operators Committee (SACROC) site showed alteration, but did not show degradation that 

compromised the structural integrity of the cement (Carey et al., 2007). In another study, cement 

samples were collected and analyzed from a CO2 production well in a natural CO2 reservoir in 

Colorado exposed to a CO2-water down-hole environment for 30 years (Crow et al., 2008). The study 

found evidence of reaction between the CO2-rich water and the cement. 

Oil industry research also addresses the effects of corrosion of steel tubing and pipes. Lopez et al. (2003) 

noted that 60 percent of oilfield failures are related to the effects of carbonic acid from produced brines 

on carbon and low alloy steels. 

Laboratory investigation of cement alteration/degradation is an ongoing research area. Few field-based 

studies have been completed to date. The laboratory and field studies currently available suggest that 

corrosion problems can be managed; however, there is not a large enough body of research to rule out 

potential corrosion problems of steel components of injection wells. The IPCC (2005) report on carbon 

dioxide capture and storage reviewed oil and gas industry experience with gas injection wells, close 

industry analogues to CO2 injection wells. The report stated that while the design of CO2 injection wells 

will be very similar to gas injection wells, most down-hole components of the CO2 injection wells will 

“need to be upgraded for higher pressure ratings and corrosion resistance.” Given the pressure and 

corrosion considerations, anticipated long lifespan of a GS well, and the difficulties that would be 

associated with a corrosion-related well failure, EPA believes that corrosion monitoring in the downhole environment is justified. For these reasons, the final rule requires quarterly corrosion monitoring (at 

§146.90(c)). 

Other EPA Comment Codes and Descriptions: 4630 2.6.3 Corrosion monitoring 

Comment: Rule Provision: 146.90(c) 

API Comments: (1) Placing ANALYZING coupons of the well construction 

materials PLACED in contact with the carbon dioxide stream; or 

(2) Routing the carbon dioxide stream through a loop constructed with the 

material used in the well AND INSPECTING THE MATERIALS IN THE LOOP; or 

(3) Using an alternative method, MATERIALS, OR TIME PERIOD approved by the 

Director; 

Rationale: Clarifying edits. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24190

264
Other EPA Comment Codes and Descriptions: 4660 2.6.6 Geochemical monitoring 

Comment: Rule Provision: 149.90(d) 

API Comments: (d) Periodic monitoring of the ground water FORMATION FLUID 

quality and geochemical changes above IN A PERMEABLE AND POROUS FORMATION AS 

NEAR AS PRACTICABLE TO the confining zone(s) FOR GEOCHEMICAL CHANGES that may be 

a result of carbon dioxide OR DISPLACED FORMATION FLUID movement through the 

confining zone or additional identified zones: 

(1) The location and number of monitoring wells must be based on specific 

information about the geologic sequestration project, including injection rate 

and volume, geology, the presence of artificial penetrations and other RELEVANT 

factors AS WARRANTED BY A RISK-ASSESSMENT; 

(2) The monitoring frequency and spatial distribution of monitoring wells must 

be based on GEOLOGICAL, geochemical AND GEOPHYSICAL data that has been collected 

under § 146.82(a)(6) §146.82(D) and any modeling results in the area of 

review evaluation required by §146.84(b); 

Rationale: Drilling monitoring wells should be carefully considered since each 

well introduces a potential pathway for movement. In addition the cost of adding 

multiple wells could create a barrier to CCS development, while providing 

limited information on actual movement of the CO2 stream. 

Response: EPA agrees that monitoring plans and methods need to be site-specific and believes that the 

monitoring requirements for GS sites at §146.90 provide an appropriate level of flexibility in structuring 

a testing and monitoring plan that protects USDWs from endangerment, while addressing the needs 

suggested in the commenter’s proposed edits. 

Regarding monitoring locations, section §146.90(d) requires periodic monitoring of the ground water 

quality and geochemical changes above the confining zone(s). EPA clarifies that this monitoring 

requirement does not include the confining layer itself. Monitoring above the confining layer will 

provide an indication of upward movement of CO2 that might endanger a USDW. The exact number of 

formations to be tested must, however, be based on site-specific characteristics and vulnerabilities and 

described in the Director-approved testing and monitoring plan. 

To mitigate the risk of fluid movement, EPA requires owners and operators to submit a testing and 

monitoring plan that describes how the owner or operator plans to site and construct monitoring wells. 

EPA believes, however, that monitoring using wells in the injection zone, e.g., for pressure monitoring 

as required at §146.90(g)(1), can be safely performed if the wells are constructed to prevent flow 

between the injection zone and USDWs or other layers above the confining zone. Such construction 

technologies exist and have been used in the oil and gas industry for years. EPA believes that properly 

constructed monitoring wells will be a safe way to obtain the data that is essential to ensure that the 

injected CO2 remains confined in the injection zone and that pressure changes are not causing 

movement or formation of other fluids. To mitigate the risk of fluid movement, EPA requires owners 

and operators to submit a testing and monitoring plan that describes how the owner or operator plans to 

site and construct monitoring wells. EPA is developing guidance on well construction that will include 

recommendations for monitoring well construction. The guidance will be available on EPA’s website at 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24191

265
http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in 

evaluating requirements under §146.90, including proposed monitoring plans. The guidance describes 

available technologies and recommended approaches for implementing a testing and monitoring plan, 

including pre-operational geophysical logging and testing of injection wells, MITs, injection well testing 

during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, and soil 

gas and surface air monitoring which may be required by the UIC Director for specific GS projects. The 

guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA acknowledges the commenters' concern about the cost of monitoring. However, EPA believes that 

monitoring is essential for protection of USDWs at GS sites. Although a significant cost in absolute 

terms, monitoring costs are expected to be a small fraction of site operating costs, according to EPA's 

cost analysis for the GS rulemaking (which is available in the docket). 

Other EPA Comment Codes and Descriptions: 4540 2.5.2 Proposed external MIT requirements; 4543 

2.5.2.1 MIT procedures and methods for GS (seeking comment) 

Comment: Rule Provision: 146.89(c) 

API Comments: (c) At least once per year, the owner or operator must confirm the 

absence of significant fluid movement under paragraph (a)(2) of this section 

USING A METHOD ACCEPTABLE TO THE DIRECTOR (E.G. INCLUDING DIAGNOSTIC 

SURVEYS 

SUCH AS OXYGEN-ACTIVATION LOGGING OR TEMPERATURE OR NOISE LOGS). 

(1) A tracer survey such as oxygen-activation 

logging; 

(2) A temperature or noise log; or 

(3) A casing inspection log, if required by the 

Director. 

Rationale: Revised text supports a performance-based approach and allows the 

development and use of new technologies as they become available. Cement 

circulation to the surface is not necessary because having the open annulus 

above the top of cement allows regular monitoring of annular pressure which 

could indicate leakage. 

Subsection (3) was deleted because it requires the tubing to be pulled at 

significant cost and risk of uncontrolled releases. 

Response: EPA believes that the MITs described in §146.89(c) of the rule (e.g., an approved tracer log 

or temperature or noise logs) are effective methods to demonstrate external MI, provide an important 

early warning of potential problems in the injection well system, and represent standard techniques that 

have been used successfully by the drilling industry and for the UIC Program for decades. The Agency 

notes that the regulations do provide the Director the flexibility at §146.89(e) to approve the use of 

alternative MIT methods. 

EPA agrees that the casing inspection log is not an appropriate test to detect fluid movement behind the 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24192

266
casing, but clarifies that it is appropriate to be used to determine the presence or absence of corrosion of 

the long-string casing, and is required if the Director determines that it is necessary based on sitespecific information. EPA has revised the final GS rule to require that the frequency of the casing 

inspection log must be specified in the approved testing and monitoring plan. See §146.89(d). 

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: Rule Provision: 149.90(e) - (f) 

API Comments: (e) A demonstration of external mechanical integrity pursuant to 

§146.89(c) at least once per year UNTIL THE WELL IS PLUGGED; 

(f) IF CONDITIONS WARRANT, A pressure fall-off test OR OTHER EQUIVALENT TEST 

THAT IDENTIFIES RESERVOIR CONDITIONS WITH RESPECT TO FLOW DYNAMICS at least 

once 

every five years unless more frequent testing is required by the Director based 

on site specific information; 

Rationale: Technical clarifications. 

Response: Regarding pressure testing, EPA believes that pressure fall-off testing is necessary for GS 

wells. Pressure fall-off tests are designed to verify that modeled projections of reservoir pressure decline 

agree with measured pressure decline profiles. These tests can be useful in AoR calculations and 

reevaluations and may also indicate mischaracterization of site geology and the presence of leakage 

pathways. Therefore, EPA is requiring that pressure fall-off testing be conducted every five years at a 

minimum, and the final GS regulation includes this requirement at §146.90(f). Pressure fall-off tests 

may be conducted in conjunction with other well performance tests (i.e., mechanical integrity testing) to 

ensure safe and effective operations. EPA disagrees that the rule should provide specifics of the test at 

the degree suggested, however. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment, EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4650 2.6.5 CO2 plume and pressure front tracking 

(seeking comment) 

Comment: Rule Provision: 149.90(g) 

API Comments: (g) Testing and monitoring AS APPROPRIATE TO SUPPORT THE MODEL FOR 

to trackING the extent of the carbon dioxide plume and the position of the 

pressure front. by either monitoring for pressure changes in the first 

formation overlying the confining zone or using indirect, geophysical techniques 

(e.g., seismic, electrical, gravity, or electromagnetic surveys and/or down-hole 

carbon dioxide detection tools); 

Rationale: Monitoring outside of the injection zone provides little information 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24193

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24194

267
of value for tracking and monitoring the injected plume. Examples of how to test 

and monitor could be included in the Preamble but need not be included in the 

rule itself. 

Response: EPA has revised this requirement in the final rule. The final GS regulation, at §146.90(g)(1), 

requires all GS project owners or operators to monitor for pressure changes in the injection zone. EPA 

believes that pressure monitoring in the injection zone is necessary to track the development and 

movement of the pressure front and CO2 plume. 

Pressure monitoring within the injection zone is necessary because any such monitoring above the 

confining zone would not detect movement of the pressure front unless a breach of the confining zone 

occurs. EPA believes that monitoring using wells in the injection zone (i.e., that penetrate the confining 

zone) can be safely performed if the wells are constructed to prevent flow between the injection zone 

and USDWs or other layers above the confining zone. Such construction technologies exist and have 

been used in the oil and gas industry for years. EPA believes that the benefits of monitoring in the 

injection formation outweigh the manageable risk of those monitoring wells serving as conduits for fluid 

movement. EPA adds that owners or operators may consider performing additional pressure monitoring 

in wells that are above the confining zone (e.g., in the same wells used to perform ground water quality 

monitoring required at §146.90(d)) to provide additional verification that no pressure changes are 

occurring above the confining zone due to CO2 leakage. Monitoring also identifies needed remedial 

actions, provides inputs for AoR reevaluation modeling, and targets additional geochemical and surface 

monitoring needs. Knowledge of the location of the CO2 plume and the associated pressure front will 

assure the public that GS projects are proceeding according to plan, provide sufficient information to the 

owner or operator and Director, or allow for appropriate actions to address any indication that USDWs 

may be endangered. 

EPA acknowledges that, at certain sites, there may be a need for more or different monitoring schemes 

(which may include monitoring in the confining zone), and adds that it is important to balance the need 

for adequate monitoring that ensures USDW protection from endangerment against too many artificial 

penetrations which could serve as conduits for fluid migration. EPA expects site-specific testing and 

monitoring plans to describe the proposed monitoring regime, which must be approved by the Director.

Flexibility is also provided regarding how to monitor for the specific data required by the final rule. The 

testing and monitoring plan is developed by the owner or operator in consultation with the Director and 

is designed to ensure that a detailed, Director-approved document describing how monitoring will be 

conducted during the lifetime of the project exists. 

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in 

evaluating requirements under §146.90, including proposed monitoring plans. The guidance describes 

available technologies and recommended approaches for implementing a testing and monitoring plan, 

including pre-operational geophysical logging and testing of injection wells, MITs, injection well testing 

during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, and soil 

gas and surface air monitoring which may be required by the UIC Director for specific GS projects. The 

guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4670 2.6.7 Surface air monitoring and/or soil gas 

monitoring (seeking comment) 

Comment: Rule Provision: 146.90(h) 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24195

268
API Comments: (h) At the Director’s discretion BASED ON SITE-SPECIFIC CONDITIONS 

AND RISK-BASED FACTORS, surface air monitoring and/or soil gas monitoring to 

detect movement of carbon dioxide that could endanger a USDW. 

Rationale: In most situations soil and air monitoring does not provide an 

effective method of protecting USDWs. 

Response: EPA clarifies that subsurface geochemical and pressure monitoring in the subsurface 

formations are the first line of monitoring that would allow detection of potential endangerment to 

USDWs from GS activities (this is required at all GS sites, as described at §146.90(d)). The Agency also 

believes that surface air and soil gas monitoring, when coupled with subsurface monitoring, may be 

appropriate at some GS projects to ensure USDW protection. 

The final rule at §146.90(h) retains the allowance for surface air and soil gas monitoring at the discretion 

of the Director as a means of identifying leaks that may pose a risk to USDWs and informing emergency 

notification of a Class VI owner or operator and UIC Director in the event of a USDW endangerment, 

pursuant to requirements at §146.91(c). 

The selection of monitoring methods will be site-specific (e.g., may be influenced by geology, injection 

depth, and operational conditions) and must be based on potential risks to USDWs within the AoR. 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Rule Provision: 146.90(h)(1) 

API Comments: (1) The testing and monitoring plan must be based on potential 

vulnerabilities SITE-SPECIFIC GEOLOGIC FACTORS, MODELING, AND RISK-ASSESSMENT 

within the area of review; 

Rationale: Technical clarification 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS rule. See the final rule and 

preamble for further discussion on EPA's final approach. EPA anticipates that the testing and monitoring 

plan will address site-specific geologic factors, modeling, and risk-assessment. EPA is developing 

guidance on how best to develop the various required project plans, including the testing and monitoring 

plan. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Rule Provision: 146.90(i) 

API Comments: (i) Any additional monitoring, as required by the Director, BASED 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24196

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24197

269
ON SITE-SPECIFIC CONDITIONS AND RISK-BASED FACTORS, necessary to support, 

upgrade, and improve computational modeling of the area of review evaluation 

required under § 146.84(b) and to determine compliance with standards under 40 

CFR 144.12 

Rationale: Technical clarification 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS rule. See the final rule and 

preamble for further discussion on EPA's final approach. EPA agrees that any additional monitoring 

requirements would be based on site-specific geologic factors, modeling, and risk-assessment. EPA is 

developing guidance for directors that provides recommended approaches when exercising discretion to 

require additional monitoring. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4720 2.7.2 Operational recordkeeping and reporting 

Comment: Rule Provision: 146.91(a) 

API Comments: (a) Semi-annual OR LESS FREQUENT AT THE DISCRETION OF THE DIRECTOR 

reports containing: 

(1) Any SIGNIFICANT changes to the physical, chemical and other relevant 

characteristics of the carbon dioxide stream from the proposed operating data; 

Rationale: Over the life of the project, the Director may decide that less 

reporting is acceptable 

(1) Technical clarification. Significance can be determined by a statistical 

analysis of the data. Rules should recognize that there will be minor variations 

in many data sets over time. 

Rule Provision: 146.91(a) 

API Comments: (3) A description of any SIGNIFICANT event that exceeds operating 

parameters for annulus pressure or injection pressure as specified in the 

permit; 

(4) A description of any SIGNIFICANT event which triggers a shutdown device 

required pursuant to §146.88(e) and the response taken; 

Rationale: EPA should consider some significance threshold on reporting these 

events to avoid reporting events that would be of limited interest or 

consequence. 

Response: EPA disagrees that less frequent than semi-annual reporting is appropriate to protect USDWs 

from endangerment. The Agency believes semi-annual reporting is appropriate and necessary for Class 

VI wells during the operational phase of the project. EPA believes that the potentially large injection 

volumes and injection pressures associated with GS warrant more frequent reporting than for other well 

classes. See the final rule and preamble for further discussion on EPA's final approach to testing and 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24198

270
monitoring. 

EPA also retained the provision at §146.91(a)(3) as proposed. The final rule at §146.91(a)(3) requires 

reporting of all exceedances of operating parameters. EPA disagrees with the suggestion to report only 

"significant" exceedances. Making a determination as to whether an exceedance is "significant" is not 

the purpose of the requirement. EPA believes that the ability of an operator to consistently meet 

operating requirements and avoid exceedances provides evidence of a well-managed GS project that is 

in compliance with the Class VI permit. If multiple exceedances occur, the Director should be aware of 

such occurrences, determine whether these indicate problems at the site, and determine the appropriate 

course of action (e.g., a well workover, modification of operating parameters, or imposition of a 

penalty). 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: Rule Provision: 146.92(a) 

API Comments: (a) Prior to the well plugging, the owner or operator must flush 

each Class VI injection well with a buffer fluid, determine bottomhole reservoir 

pressure, and perform a final EXTERNAL mechanical integrity test OF ANY RELEVANT 

WELLBORE MATERIALS REMAINING. 

Rationale: Many of the components that would be tested by an internal MIT are 

removed or tested during the plugging process. 

Response: EPA agrees that only an external MIT is required, and has modified the GS rule at §146.92

(a) to require owners or operators to perform a final external mechanical integrity test prior to the well 

plugging. 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: Rule Provision: 146.92(b)(2) 

API Comments: (2) Appropriate testing methods to ensure FINAL EXTERNAL 

mechanical integrity as specified in §146.89(C); 

Rationale: Many of the components that would be tested by an internal MIT are 

removed or tested during the plugging process. 

Response: EPA agrees that only an external MIT is required, and has modified the GS rule at §146.92

(a) to require owners or operators to perform a final external mechanical integrity test prior to the well 

plugging. 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24199

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24200

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24201

271
Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: Rule Provision: 146.92(b)(5) 

API Comments: (5) The type and grade and quantity of material to be used in 

plugging. The material must be SUITABLE FOR USE with the carbon dioxide stream; 

and 

No rationale provided 

Response: EPA believes, considering the potentially corrosive nature of CO2 when it is in contact with 

water, that the requirement that the material must be compatible with the CO2 stream is appropriate. The 

final rule retains this requirement. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 

146.92) 

Comment: Rule Provision: 146.92(d) 

API Comments: (d) Plugging report. Within 60 days after plugging the owner or 

operator must submit a plugging report to the Director. If the semi-annual 

report is due less than 15 days after completion of plugging, then the report 

must be submitted within 60 days after plugging. The report must be certified 

as accurate by the owner or operator and by the person who performed the 

plugging operation (if other than the owner or operator.) 

Rationale: The proposed changes are suggested to simplify and clarify a 

provision that API believes is needlessly complicated. 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads, "Within 

60 days after plugging, the owner or operator must submit a plugging report to the Director." 

Other EPA Comment Codes and Descriptions: 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Rule Provision: 146.93(a)(1) 

API Comments: (1) The owner or operator must submit the postinjection site 

care and site closure plan as a part of the permit application to be approved by 

the Director. SHALL CONTINUE TO CONDUCT MONITORING AS SPECIFIED IN THE 

DIRECTOR-APPROVED POST-INJECTION SITE CARE AND SITE CLOSURE PLAN, 

PURSUANT TO 

THE PERFORMANCE BASED CRITERIA DESCRIBED IN 146.93(B)(3). 

Rationale: Revisions here reflect changes to §146.93(b)(3) 

Response: EPA disagrees with the suggested changes, and disagrees that the post-injection monitoring

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24202

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24203

272
period should be strictly performance-based. The Agency agrees that there will be limited circumstances 

where it can be demonstrated in less than 50 years that the plume and pressure front no longer pose a 

risk of endangerment to USDWs, and has included requirements in the final Class VI rule at §146.93(c) 

for an owner or operator to substantially demonstrate that an alternative time frame ensures the 

protection of USDWs. However, EPA anticipates that a default timeframe for post-injection site care 

will necessary for most GS sites to ensure the protection of USDWs. A 50-year post-injection site care 

timeframe represents a reasonable and protective monitoring period based on a review of research 

studies, industry reports, and existing environmental programs, and evaluation of public comments. For 

this reason, the final GS regulation includes a provision that the Director may, at his or her discretion, 

shorten the post-injection site care timeframe if the owner or operator can demonstrate that the GS 

project does not pose an endangerment to USDWs, as specified in §146.93(b)(2). Such a demonstration 

will be site-specific, and based on pressure monitoring and USDW impacts. 

The GS rule requires owners or operators to submit a post-injection site care and site closure plan as part 

of the permit application, as specified in §146.82(a), in order to outline how these activities will be 

performed and how non-endangerment of USDWs will be demonstrated throughout the post-injection 

site care period. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: Rule Provision: 146.93(a)(2) 

API Comments: (2) The post-injection site care and site closure plan must 

include the following information: 

(i) The pressure differential between preinjection and predicted post-injection 

pressures in the injection zone; 

(ii) The predicted position of the carbon dioxide plume and associated pressure 

front at site closure as demonstrated in the area of review evaluation required 

under § 146.84(b); 

(iii) A description of post-injection monitoring location, methods, and proposed 

frequency; and 

(iv) A proposed schedule for submitting post-injection site care monitoring 

results to the Director. 

Rationale: Revisions here reflect changes to §146.93(b)(3) 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Comment: Rule Provision: 146.93(a)(4) 

API Comments: (4) AT ANY TIME DURING THE POST-INJECTION SITE CARE PHASE, The 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24204

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24205

273
owner or operator may modify and resubmit the post-injection site care and site 

closure plan for the Director‘s approval within 30 days of such change. 

Rationale: Technical Clarification. 

Response: EPA agrees that a post-injection site care monitoring plan is an important tool for GS, and 

anticipates that, in some cases, the appropriate post-injection monitoring strategy may end up being 

different than initially projected, and there may be a need to amend the post-injection site care and site 

closure plan. EPA is requiring that upon the cessation of injection, the owner or operator submit an 

amended post-injection site care and site closure plan or demonstrate to the Director that no changes to 

the original post-injection site care and site closure plan are necessary (§146.93(a)(3)). EPA is not 

requiring formal periodic review and updates to the PISC and site closure plan throughout the injection 

phase. EPA does not expect that changes to this plan would be implemented until injection operations 

cease. EPA envisions that owners or operators would take into account similar considerations that guide 

updates to other project plans, e.g., monitoring and operational data and results of AoR reevaluations. 

EPA adds that, if any monitoring or other site data indicate a need for amending the post-injection site 

care plan, the owner or operator is expected to amend the plan accordingly. 

EPA adds that, in the final rule, it has revised the text at §146.93(a)(4) as follows: "At any time during 

the life of the geologic sequestration project, the owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval within 30 days of such change." 

EPA is issuing guidance on development and updating of the GS project plans, including the postinjection site care and site closure plan. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment) 

Comment: Rule Provision: 146.93(b) 

API Comments: (b) The owner or operator shall monitor the site following the 

cessation of injection to show the position of the carbon dioxide plume and 

pressure front and demonstrate that USDWs are not being endangered. 

(1) The owner or operator shall continue to conduct monitoring as specified in 

the Director-approved post-injection site care and site closure plan, for at 

least 50 years following the cessation of injection. At the Director‘s 

discretion, the monitoring will continue until the geologic sequestration 

project no longer poses an endangerment to USDWs. UNTIL CLOSURE IS AUTHORIZED 

PURSUANT TO §146.93(B)(3). 

(2) If The owner or operator can request and demonstrate to the satisfaction 

of the Director before 50 years, based on monitoring and other site-specific 

data, that the geologic sequestration project no longer poses an endangerment to 

USDWs, the Director may approve an amendment to THAT the post-injection site 

care and site closure plan SHOULD BE REVISED to reduce the frequency of 

monitoring or may authorize site closure before the end of the 50-year 

period. 

Rationale: API, along with the MSDG, believes there are three problems with the 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24206

274
closure standard in proposed section 146.93(b). First, the presumption that 

monitoring should continue for 50 years is unnecessary and counterproductive. A 

straight performance standard is preferable to this or any other fixed time 

period because it provides a clearer standard and an incentive to maximize the 

understanding of site and project performance and as such is more protective of 

USDWs. Second, the proposal requires a showing that the CO2 plume has 

"stabilized", which is undefined. Cessation of plume movement is not necessarily 

essential to show that a project poses no threat of endangerment to USDWs-plumes 

that are still moving may, nonetheless, remain contained. Instead, it is more 

protective to show that the plume is not expected to encounter a leakage 

pathway. Third, the required showing that "no additional monitoring is needed" 

does not provide guidance regarding how an operator is to show that no 

additional monitoring is needed. The proposal below provides specific guidance 

on what the operator must show. 

API, in concert with the MSDG, recommends the standard in the proposed 

alternative language for section 146.93(b) below because it sets forth detailed 

criteria, all of which must be satisfied, to demonstrate that the site does not 

pose an endangerment to USDWs. The specific criteria listed in our proposal will 

serve to provide the Director with the requisite information to make the 

appropriate determination. The advantage of this approach is that it establishes 

clear criteria that an operator must demonstrate before obtaining site closure 

based upon particular site characteristics and is, therefore, reasonably 

applicable to any storage site as opposed to a standard based upon a 

fixedduration. Furthermore, it is more stringent than a purely discretionary 

approach because it establishes specific criteria that must be shown before site 

closure may be granted. We believe this language, which is an extension of work 

done by the World Resources Institute and the Ground Water Protection Council, 

avoids the noted shortcomings and provides stronger protection for USDWs. 

Response: EPA disagrees with the suggested changes. As noted above, EPA disagrees that a postinjection site care timeframe of 50 years is excessive for most Class VI wells. EPA believes that a 50-

year default post-injection site care timeframe, as required at §146.93(b)(1), is not overly burdensome, 

does not exaggerate the risks associated with GS, is consistent with other environmental programs, and 

sufficiently protects USDWs from endangerment. 

EPA acknowledges the concerns of some commenters that there will be circumstances where it can be 

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of 

endangerment to USDWs. For this reason, the Class VI rule offers owners or operators flexibility 

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or 

lengthen the PISC timeframe during the PISC period based on site-specific data, pursuant to 

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or 

operator to demonstrate, based on substantial data during the permitting process, that an alternative PISC 

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at 

§146.93(c). 

EPA believes that a 50 year post-injection site care timeframe represents a reasonable and protective 

monitoring period and available data, including data submitted by commenters, do not support a 

different default timeframe. Furthermore, EPA believes that a 50-year default post-injection site care 

timeframe, as required at §146.93(b)(1), is not overly burdensome, does not exaggerate the risks 

associated with GS, is consistent with other environmental programs, and sufficiently protects USDWs 

from endangerment. 

275
EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist Directors 

in evaluating proposed well plugging plans and post-injection site care and site closure plans required 

under 146.92 and 146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells, perform post-injection monitoring, demonstrate the 

appropriateness of an alternative post-injection site care time frame, demonstrate non-endangerment, 

and perform site closure activities. This guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5280 2.8.2.4 USDW non-endangerment 

demonstrations 

Comment: Rule Provision: 146.93(b)(3) 

API Comments: (3) Prior to authorization for site closure, the owner or operator 

MUST submit to the Director a demonstration, DEMONSTRATE TO THE DIRECTOR, 

based on monitoring, and other site-specific data, AND MODELING THAT IS 

REASONABLY CONSISTENT WITH SITE PERFORMANCE that the carbon dioxide plume and 

pressure front have stabilized and that no additional monitoring is needed to 

assure that the geologic sequestration project does not AND IS NOT EXPECTED TO 

pose an endangerment to USDWs. THE DIRECTOR SHALL APPROVE CLOSURE IF THE OWNER 

OR OPERATOR DEMONSTRATES, BASED ON THE CURRENT UNDERSTANDING OF THE 

SITE, 

INCLUDING MONITORING DATA AND/OR MODELING, ALL OF THE FOLLOWING: (I) THE 

ESTIMATED MAGNITUDE AND EXTENT OF THE PROJECT FOOTPRINT (CO2 PLUME AND 

THE AREA 

OF ELEVATED PRESSURE), (II) THE ESTIMATED LOCATION OF THE DETECTABLE CO2 

PLUME; 

(III) THAT THERE IS NO SIGNIFICANT LEAKAGE OF EITHER CO2 OR DISPLACED 

FORMATION 

FLUIDS THAT IS ENDANGERING USDWS; (IV) THAT THE INJECTED OR DISPLACED 

FLUIDS ARE 

NOT EXPECTED TO MIGRATE IN THE FUTURE IN A MANNER THAT ENCOUNTERS A 

POTENTIAL 

LEAKAGE PATHWAY INTO A USDW; (V) THAT THE INJECTION WELLS AT THE SITE 

COMPLETED 

INTO OR THROUGH THE INJECTION ZONE OR CONFINING ZONE ARE PLUGGED AND 

ABANDONED 

IN ACCORDANCE WITH THESE REQUIREMENTS; AND (VI) ANY REMAINING PROJECT 

MONITORING 

WELLS AT THE SITE ARE BEING MANAGED BY A PERSON AND IN A MANNER 

ACCEPTABLE TO 

THE DIRECTOR. 

Rationale: API edits establish the performance based criteria for selecting the 

monitoring period. EPA should recognize that under any given set of site 

specific conditions some of these criteria may not be fully satisfied. EPA 

should retain the ability to waive individual monitoring criteria described here 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24208

276
to reflect that situation. 

Rule Provision: 146.93(b)(4) 

API Comments: (4) If such a demonstration cannot be made (i.e., if the carbon 

dioxide plume and pressure front have not stabilized) after the 50-year period, 

the owner or operator must submit to the Director a plan to continue postinjection site care. 

Rationale: No longer necessary given changes above. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring timeframe. 

Instead, EPA believes that such determinations are site-specific and should be described in a project 

specific post-injection site care and site closure plan. EPA also believes that periodic reviews and 

updates, where necessary, to the plan are important to ensuring that the site continues to be managed 

effectively and to determine whether shortening the monitoring timeframe is appropriate. The postinjection site care requirements in the final GS rule incorporate a combination of a fixed timeframe and 

a performance standard approach. The final GS rule offer owners or operators flexibility regarding the 

duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC 

timeframe during the post-injection period based on site-specific data, pursuant to requirements at 

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to 

demonstrate, during the permitting process based on substantial data, that an alternative PISC timeframe 

may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will assist 

Directors in evaluating proposed well plugging plans and post-injection site care and site closure plans 

under §146.92 and §146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells, perform post-injection monitoring, demonstrate the 

appropriateness of an alternative post-injection site care time frame, demonstrate non-endangerment, 

and perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment); 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(4) 

API Comments: (4) If such a demonstration cannot be made (i.e., if the carbon 

dioxide plume and pressure front have not stabilized) after the 50-year period, 

the owner or operator must submit to the Director a plan to continue postinjection site care. 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24209

277
Rationale: No longer necessary given changes above. 

Response: As described above, EPA believes that to ensure USDW protection from endangerment, a 

default timeframe for post-injection site care is necessary in most cases. A 50-year post-injection site 

care timeframe represents a reasonable and protective monitoring period for most GS projects based on 

a review of research studies, industry reports, and existing environmental programs, and evaluation of 

public comments. However, EPA recognizes that alternative timeframes may be appropriate under 

limited, specific circumstances. For this reason, the Class VI rule offers owners or operators flexibility 

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or 

lengthen the PISC timeframe during the PISC period based on site-specific data, pursuant to 

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or 

operator to demonstrate, based on substantial data during the permitting process, that an alternative PISC 

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at 

§146.93(c). 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Rule Provision: 146.93(e) 

API Comments: (e) Once the Director has authorizeSd site closure, the 

owner or operator must submit a site closure report within 90 days that must 

thereafter be retained at a location designated by the Director. AFTER 

COMPLETION OF ALL CLOSURE OPERATIONS. The report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the location 

of the injection well(S) relative to permanently surveyed benchmarks. The owner 

or operator must also submit a copy of the plat to the Regional Administrator of 

the appropriate EPA Regional Office; 

Rationale: Once the site closure report is submitted to the Director, the 

operator cease to bear responsibility for any further record retention. At this 

point, EPA becomes the steward of information for the project. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention such 

as site closure reports. EPA believes that the requirements that the owner or operator retain, for ten years 

following site closure, records collected during the post-injection site care period at §146.93(f) and 

§146.93(h) are appropriate for the post-injection and site closure period to ensure that data are available 

to support non-endangerment demonstrations and to address any concerns that may arise following site 

closure. This data will also support EPA's review of project data as part of the adaptive rulemaking 

approach. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24210

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24211

278
response (40 CFR 146.94) 

Comment: Rule Provision: 146.94(b) 

API Comments: (b) If the owner or operator obtains evidence that the injected 

carbon dioxide stream, DISPLACED FORMATION FLUIDS OR and associated pressure 

front may cause an endangerment to ENDANGERS a USDW, the owner or operator 

must: 

(1) Immediately cease injection IN A PRUDENT MANNER CONSIDERING 

CIRCUMSTANCES. 

(2) Take all steps reasonably necessary to identify and characterize THE 

ENDANGERMENT POSED; 

(3) Notify the Director or the designated representative within 24 hours OF 

BECOMING AWARE OF THE ENDANGERMENT; and 

Rationale: Technical clarifications. 

There is a slight change that immediately ceasing injection could have adverse 

impacts on other aspects of the operation. 

Response: After consideration of comments, EPA has finalized the rule language in §146.94(b) as 

proposed. In the introductory section of §146.94(b), EPA clarifies that the pressure front, as defined in 

§146.81, is a zone where the pressure differential is sufficient to cause the movement of injected fluids 

or formation fluids into a USDW. Therefore, displaced formation fluids are implicitly included in the 

requirements for §146.94. EPA also clarifies that owners or operators must take action when the CO2 

stream or pressure front may cause endangerment. In order to prevent the endangerment of USDWs, as 

required under §1421 of the SDWA, EPA expects the owner or operator to act preemptively and not 

wait until endangerment has occurred. This language is consistent with existing UIC requirements for 

other well classes and EPA’s authority under the SDWA. 

Regarding changes to the language in §146.94(b)(1), EPA believes that it is implicit that owners or 

operators should take care not to damage the well when ceasing injection. At §146.94(b)(2), EPA is 

maintaining the requirement to “characterize the release.” As currently written, the situation should be 

characterized whether or not a USDW has actually been endangered, and owners or operators are 

encouraged to discuss with the Director whether actual endangerment has occurred. Concerning 

commenters’ suggestions for §146.94(b)(3), EPA clarifies that the 24 hours begins when the owner or 

operator obtains evidence of possible endangerment. EPA believes the rule language is clear on this 

requirement. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: Rule Provision: 146.94(d) 

API Comments: (d) The owner or operator must notify the 

Director prior to conducting any well workover IN RESPONSE TO ANY CASE OF 

ENDANGERMENT. 

Rationale: In critical situations, time spent obtaining 

approval could adversely affect the ability to conduct operations or increase the level of 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24212

279
endangerment. 

Response: Since proposal, EPA has modified the final regulatory language at §146.94(d) to clarify what 

constitutes a workover to address a well failure (which invokes remedial actions) and what constitutes a 

maintenance-type workover. For maintenance-type workovers (i.e., those that are scheduled in advance), 

the owner or operator must notify and gain approval from the Director prior to beginning the workover. 

In the final GS regulation, EPA has moved this requirement to the reporting requirements at §146.91(d) 

to clarify its intent. 

Regarding concerns that notification could delay responses, EPA clarifies that the GS rule, at §146.94

(b), describes procedures owners or operators must take in emergency situations. Specifically, upon 

determining that there is a problem with the well that may endanger a USDW, the owner or operator 

must first cease injection, then take all steps reasonably necessary to identify and characterize any 

release, notify the Director, and implement the approved emergency and remedial response plan, which 

may include a well workover. EPA believes that ceasing injection (which the owner or operator would 

do immediately and before notifying the Director) is the immediate action necessary to prevent or 

mitigate endangerment of USDWs. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a)(2)(i) 

API Comments: (i) Resistivity, spontaneous potential, and caliper logs before 

the casing is installed; and 

Rationale: After a few wells are drilled in an area, these evaluations are 

frequently unnecessary and yield little new information. This is an example of 

where Director discretion may be appropriate. 

Rule Provision: 146.87(a)(2)(ii) 

API Comments: (ii) A Cement bond and variable density log, and a 

temperature log evaluation log(s) after the casing is set and cemented. 

Rationale: Unusual to run these logs in a surface hole due to uniformity of 

shallow geology. This is an example of where Director discretion may be 

appropriate. 

The proposed change provides more flexibility to select the appropriate log to 

demonstrate adequate cement bond. 

Rule Provision: 146.87(a)(3)(i) 

API Comments: Resistivity, spontaneous potential, porosity, caliper, gamma ray, 

fracture finder logs and any other logs the Director requires BASED ON SITE 

SPECIFIC CONDITIONS AND RISK-BASED FACTORS for the given geology before the 

casing is installed; and 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 29190

280
Rationale: It is acceptable to specify basic logging requirements, however, 

special logs should not be specified. Any other information from the area should 

be used instead. 

Rule Provision: 146.87(a)(3)(ii) 

API Comments: (ii) A Cement bond and variable density log, and a 

temperature log EVALUATION LOG(S) after the casing is set and cemented. 

Rationale: The proposed change provides more flexibility to select the 

appropriate log to demonstrate adequate cement bond. 

Rule Provision: 146.87(a)(4) 

API Comments: (4) A series of tests TEST(S) designed to demonstrate the 

internal and external mechanical integrity of injection wells, which may 

include: 

(i) A pressure test with liquid or gas; 

(ii) A tracer survey DIAGNOSTIC TOOLS such as oxygen-activation logging; 

(iii) A temperature or noise log; AND/OR 

(iv) A casing inspection log. if required by the Director; and 

Rationale: Technical and grammatical corrections 

In (iv), "if required by the Director" is unnecessary, as it is in subsection 

(a) 

Rule Provision: 146.87(a)(5) 

API Comments: (5) Any alternative methods that provide equivalent or better 

information and that are required of and/or approved of by the Director. 

Rationale: Same comment as above in (iv). 

Rule Provision: 146.87(b) 

API Comments: (b) The owner or operator must submit to the Director A REPORT 

DESCRIBING whole cores or sidewall cores REPRESENTATIVE of the injection zone 

and confining system and formation fluid samples from the injection zone(s). The 

Director may accept DATA FROM cores AND FLUID SAMPLES from nearby wells if the 

owner or operator can demonstrate that core retrieval is not possible and 

that such cores DATA are representative of conditions at the well IN 

THE WELLBORE. The Director may require the owner or operator to core other 

formations in the borehole. 

Rationale: The information required should be sufficient to properly describe 

the injection and confining zones. 

Response: EPA believes that all logs, surveys, and tests listed at §146.87(a) are necessary to verify 

information about the injection and confining zones and ensure that the well is being drilled and cased as 

approved, and has mechanical integrity. This information is needed to demonstrate that the well can be 

281
operated and tested in a manner that protects USDWs from endangerment. While the tests do provide 

information on some of the same items, each provides unique data that build on each other and allow for 

interpretations not possible with a single test. 

EPA notes that the Director has the discretion at §146.87(a)(5) to approve alternative methods that 

provide equivalent or better information. EPA believes that logs and tests must be performed on each 

well drilled regardless of existing information about the area to account for the complexity of CO2 

injection well construction and the buoyancy of CO2. Existing lithologic and geologic information may 

lack the details needed for site-specific well design and the geology needed to support protection of 

USDWs from endangerment. 

EPA clarifies at §146.87(a)(2)(ii) and 146.87(a)(3)(ii) that owners or operators must perform a cement 

bond (i.e., cement evaluation) log after the casing is set and cemented. 

Regarding the comment on §146.87(a)(4)(ii), EPA disagrees that allowing the use of unspecified 

"diagnostic tools" would provide the same amount of information as the requirement to perform a tracer 

survey. The track record for tracer surveys in evaluating mechanical integrity has been proven over time. 

EPA clarifies that a tracer survey is one of the mechanical integrity tests that may be required by the 

Director or used by the owner or operator. EPA agrees with the commenter about the wording of the 

casing inspection log requirement and made the suggested change to improve clarity. In the final 

regulation, §146.87(a)(iv) does not include the phrase, “if required by the Director.” 

Regarding the comment on §146.87(b), EPA clarifies that it is not the Agency's intent that physical cores 

be submitted to the Director. In the final GS rule, EPA has revised the first sentence of §146.87(b) to 

read as follows: "The owner or operator must take whole cores or sidewall cores of the injection zone 

and confining system and formation fluid samples from the injection zone(s), and must submit to the 

Director a detailed report prepared by a log analyst that includes: well log analyses (including well logs), 

core analyses, and formation fluid sample information...." 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(c) 

API Comments: (c) PRIOR TO INJECTION WELL OPERATION, the owner or operator must 

record PROVIDE REPRESENTATIVE INFORMATION ON the fluid FORMATION 

temperature, FORMATION FLUID pH and conductivity, and reservoir pressure and 

the static fluid level of the injection zone(s). 

Rationale: Technical corrections. Reservoir pressure and static fluid level are 

redundant parameters. 

The phrase "representative information" prevents the operator from having to do 

all tests in all wells. 

Rule Provision: 146.87(d) 

API Comments: (d) At a minimum, the owner or operator must determine or 

calculate the following information concerning the injection and confining

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 29200

282
zone(s): 

(1) Fracture pressure; 

(2) Other physical and chemical characteristics of the injection and confining 

zones; and 

(3) Physical and chemical characteristics of the formation fluids in the 

injection zone. 

Rationale: With the exception of calculating fracture pressure, the requirements 

of this section appear redundant to other requirements of prior sections. The 

fracture pressure requirement has been added to section 146.87(e) below. (2) and 

(3) are too vague. 

Rule Provision: 146.87(e) 

API Comments: (e) (D) Upon completion but Prior to INJECTION WELL 

operation, the owner or operator must conduct the following tests to verify 

hydrogeologic characteristics of the injection zone: 

(1) A pump test; or 

(2) Injectivity tests. 

ESTIMATE FRACTURE PRESSURES OF THE INJECTION AND CONFINING ZONES AND 

INJECTIVITY 

OF THE INJECTION ZONE. ESTIMATES SHOULD BE BASED ON REPRESENTATIVE 

HYDROGEOLOGIC 

AND GEOMECHANICAL CHARACTERISTICS OF THE INJECTION ZONE. 

Rationale: Allows the use of information such as leak off tests conducted during 

the drilling operation. 

The results of a pump test (pumping fluid from the well) have no relevance for 

an injection well. 

Deletion of the injectivity test would allow the use of non-destructive methods 

to calculate fracture pressure. 

Rule Provision: 146.87(f) 

API Comments: (f) The owner or operator must provide the Director with the 

opportunity to witness all logging and testing by this subpart. The owner or 

operator must submit a schedule of such activities to the Director 30 days 

prior to conducting the first test UPON SPUDDING THE WELL and NOTIFY THE 

DIRECTOR OF submit any changes to the schedule 30 days 48 HOURS prior to 

the next scheduled test. 

Rationale: The changes reflect the realities of flexible rig schedules and 

operations. In addition, they are fully consistent with current Class II 

requirements and practices which deal with these issues on a daily basis. 

Response: EPA disagrees that "reservoir pressure" and "static fluid level" measurements required in 

§146.87(c) are redundant parameters. Although the static fluid level is equal to the bottom hole pressure, 

this may not always be identical to the reservoir pressure. Additionally, measuring the static fluid level 

provides additional assurance that the reading is accurate (or, provides the needed information in cases 

283
where a good reading is not obtained). In addition, a static fluid level measurement provides information 

regarding the proximity to USDWs that need protection afforded to them. 

EPA believes that the requirement to provide information on the injection and confining zones in 

§146.87(d) is warranted, and that the rule provides flexibility to account for the variety of geologic 

conditions that may be encountered at GS sites. 

EPA clarifies that the owner or operator has the option of using pump tests or injectivity tests specified 

at §146.87(e) depending on which would provide the most valuable information based on site-specific 

conditions. Further, EPA disagrees that pump tests are irrelevant to determining injection zone 

properties. Depending on the characteristics or depth of knowledge of the confining and injection zone 

formations, pump tests may be necessary to prove that no hydraulic connection exists between the 

injection zone and a USDW. Additionally, EPA disagrees that the wording at §146.87(d) would lead the 

owner or operator to employ destructive testing methods for determination of fracture pressure. The 

wording "determined or calculated" allows for calculations to be performed based on non-destructive 

methods. 

EPA disagrees that the 30-day notification requirement is unreasonable. Acknowledging the developing 

nature of CO2 GS, EPA believes that involvement by the permitting authority in each project will 

provide much needed field data for assurance of USDW protection from endangerment and will help 

update and refine the permitting process. Adequate timing of notification will ensure the Director's 

ability to be involved. 

Other EPA Comment Codes and Descriptions: 4000 2.4 Proposed Injection Well Operating 

Requirements (40 CFR 146.88) 

Comment: 146.88 

(a) 

Change first line to read: "Except during stimulation and fracture breakdown 

pressure testing". 

Response: EPA clarifies that approved well stimulation is the only situation where owners and operators 

may exceed the 90 percent injection pressure limitation. The final rule at §146.91(d)(2) also requires that 

the owner or operator notify the Director 30 days before performing stimulation during injection 

operations; this will provide an opportunity for the Director to review the owner or operator's plans for 

stimulation and add other requirements as needed. EPA clarifies that UIC regulations prohibit fracturing 

of the confining zone at any time during injection or stimulation. 

Other EPA Comment Codes and Descriptions: 5700 2.12 Comments on the proposed duration of 

Class VI permits (seeking comment) 

Comment: Part 144.36(a): The geologic sequestration of carbon dioxide is not a fully 

proven technology and much is unknown about the long-term impacts, and potential 

unintended consequences of such injection. As previously stated, AWWA believes 

it would be prudent to limit the life of the Class VI permit so that necessary

Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23635

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23719

284
adjustments to the permit can be made as needed, with the opportunity for public 

comment. This will also establish a process for obtaining updated information on 

the injection operation. We would recommend a permit life of no more than 5 

years. Therefore, AWWA recommends revising this part to read: 

Permits for Class I and V wells shall be effective for a fixed term not to 

exceed 10 years. UIC Permits for Class II and III shall be issued for a period 

up to the operating life of the facility. Permits for Class VI wells shall be 

effective for a fixed term not to exceed 5 years. 

Response: The final rule maintains the lifetime permit provision and clarifies that the permit extends 

through the post-injection site care period (144.36(a)). However, it also adds a requirement that the 

Director review each Class VI permit at least every 5 years to determine whether it should be modified, 

revoked and reissued, terminated or a minor modification made as provided in §§144.39, 144.40, or 

144.41. The Director’s review will be informed by the owners’ or operators’ iterative reevaluation of the 

GS project. Specifically, the final rule includes a requirement that the AoR be reevaluated at least every 

five years, and also requires owners or operators to review and update the AoR and corrective action 

plan, the testing and monitoring plan, and the emergency and remedial response plan throughout the life 

of the project (146.84(e), 146.90(j), and 146.94(d)). Owners or operators must review each plan and 

identify necessary amendments or demonstrate to the Director that no amendment is needed. In no case 

can reviews occur less often than once every five years. The iterative process and subsequent plan 

reevaluations ensure that time and resources are committed to the most critical aspects of the permit in 

preventing endangerment to USDWs. 

EPA believes that the iterative process of developing and executing the various plans required of GS 

well operators in the final rule (e.g., for AoR and corrective action, testing and monitoring, well 

plugging, and post-injection site care, and emergency and remedial response) is tailored to the unique 

aspects of—and is more appropriate for–GS than establishing a finite permit duration (e.g., five years as 

suggested by some commenters). This is preferable to a periodic permit reapplication. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions; 4400 

2.4.4.3 Allowing injection above or between USDWs (seeking comment) 

Comment: Part 146.5(f): There is the possibility that some of the geologic sequestration 

activities will occur in areas where there are no USDWs located in the area of 

review. These wells should still be permitted as Class VI wells, and AWWA 

recommends revising the Class VI definition to: 

(f) Class VI. Wells used for geologic sequestration of carbon dioxide in the 

following applications: 

1. Where carbon dioxide is injected below the lowermost formation containing a 

USDW; and, 

2. Where carbon dioxide is injected in formations where no USDWs exist within 

the zone of elevated pressure associated with the injection well. 

Wells used for the geologic storage of carbon dioxide in formations above the 

lowermost USDW are prohibited. 

This definition would capture all wells associated with geologic carbon 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23720

285
sequestration activities whether or not a USDW was present in the projected 

footprint of the project. 

Response: In the final rule EPA will allow injection into non-USDWs above or between the lowermost 

USDW where owners or operators can demonstrate that such injection can be performed in a manner 

that protects USDWs from endangerment, as long as appropriate protections are in place. 

EPA adds that, in the final rule at §144.6 (f), Class VI wells are defined as wells that are not 

experimental in nature that are used for geologic sequestration of carbon dioxide beneath the lowermost 

formation containing a USDW; or, wells used for geologic sequestration of carbon dioxide that have 

been granted a waiver of the injection depth requirements pursuant to requirements at §146.95 of this 

chapter; or, wells used for geologic sequestration of carbon dioxide that have received an expansion to 

the areal extent of an existing Class II enhanced oil recovery or enhanced gas recovery aquifer 

exemption pursuant to §§146.4 of this chapter and 144.7(d). 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82) 

Comment: Part 146.82(b) AWWA recommends revising the second to the last sentence to read: 

The map should also show faults and other major geologic discontinuities, if 

known or suspected. 

Response: Based on its evaluation of all public comments and input on the proposed rule and the 

NODA and Request for Comment EPA has made many revisions to the GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82) 

Comment: Part 146.82(b) AWWA recommends that the last sentence be deleted from this part. 

Owner/operators should be required to go beyond the data available in the public 

record to identify some of the features listed in this requirement. For example, 

the owner/operator should be required to do its due diligence to identify all 

abandoned wells, plugged wells or old boreholes in the area of review. While 

public records may be a good starting point for the identification of these 

features, given the fact that some of the existing wells could be decades old, 

it is hard to believe that records would exist for every one of them. EPA should 

mandate that owner/operators use well identification technology to locate any 

existing wells that are not listed in the public record. 

AWWA recommends revising this part to read: 

A surface map showing the injection well(s) for which a permit is sought and the 

applicable area of review. Within the area of review, the map must show the 

number, or name and location of all injection wells, producing wells, abandoned 

wells, plugged wells or dry holes, deep stratigraphic boreholes, State or EPA 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23724

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23725

286
approved subsurface cleanup sites, surface bodies of water, springs, mines 

(surface and subsurface), quarries, water wells and other pertinent surface 

features including structures intended for human occupancy and roads. The map 

should also show faults, if known or suspected. The owner or operator must 

include all information available in the public record, as well as conducting 

independent site investigations to locate any of the above features that may not 

be identified in the public record. 

Response: EPA believes that a determination about whether data/information is outside or within the 

public record will be site-specific, and based on knowledge of the site, data availability, and data quality. 

For instance, in meeting the requirement to tabulate information on wells in the AoR, the Director has 

the discretion to require the owner or operator to supplement a data records search, including requiring 

ground or airborne surveys for wells, if there is reason to believe, based on knowledge of the site or of 

available data bases, that the incompleteness of available information could compromise USDW 

protection from endangerment. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82) 

Comment: Part 146.82 (c) AWWA recommends revising this part to read: 

A map delineating the area of review based upon modeling, using all available 

data including data obtained during geophysical logging and testing of the well 

and the formation as required by paragraphs (l), (r), and (s) of this section. 

Response: EPA clarifies that the map of the AoR must reflect the model inputs, including the extensive 

geologic information, data collected during the site characterization process (e.g., information about 

artificial penetrations), and anticipated operating parameters (e.g., injection rates) submitted with the 

permit application under 146.82. EPA adds that the final rule, at §146.82(c)(1), requires that the final 

area of review be “based on modeling, using data obtained during logging and testing of the well and the 

formation...” 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82) 

Comment: Part 146.82(d)(1) AWWA recommends revising this part to read: 

Isopach maps of the area of review, including the proposed injection and 

confining zone(s), a structural contour map hung on the top of the proposed 

injection zone, and at least two geologic cross sections of the area of review 

showing the geologic formations from the surface to total depth. 

Part 146.82(d)(2) AWWA recommends revising this part to read: 

Location, orientation, and properties of known or suspected subsurface faults, 

fractures, and other discontinuities that may transect the confining zone(s) in 

the area of review and a determination that they would not interfere with 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23726

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23727

287
containment. 

Part 146.82(d)(3) AWWA recommends revising this part to read: 

Information on the seismic history within the proposed area of review including 

presence and depth of seismic sources, knowledge of previous seismic events and 

history of these events, and a determination that the seismicity would not 

interfere with containment. 

Part 146.82(d)(4) AWWA recommends revising this part to read: 

A spreadsheet with data on the depth, areal extent, thickness, mineralogy, 

porosity, permeability, capillary and reservoir pressure of the injection and 

confining zone(s) within the area of review; including any geologic/facies 

changes based upon field data which may include geologic cores, outcrop data, 

seismic surveys, well logs, and names and lithologic descriptions. 

Part 146.82(d)(5) AWWA recommends revising this part to read: 

Geomechanical information on fractures, stress, ductility, rock strength, and in 

situ fluid pressures on the injection and confining zones within the area of 

review. 

Part 146.82(e) AWWA recommends revising the first sentence to read: 

A spreadsheet of all wells and other artificial penetrations within the area of 

review which penetrate the injection or confining zone(s). 

Part 146.82(f) AWWA recommends revising this part to read: 

Potentiometric (water level) surface maps and stratigraphic cross sections 

indicating the general vertical and lateral limits of all USDWs including 

existing aquifers not meeting the definition of a USDW that are either currently 

being utilized as private or public water supplies or are identified as a future 

water supply, water wells and springs within the area of review, their positions 

relative to the injection zone(s) and the direction and velocity of water 

movement. At least two geologic cross sections showing the thickness and general 

vertical and lateral limits of all USDWs within the area of review. 

Part 146.82(g) This part should provide a list of the formations for which 

baseline geochemical data should be obtained. AWWA recommends revising this part 

to read: 

Collection of baseline geochemical data on the subsurface formations, including 

all USDWs in the area of review. At a minimum, geochemical data should be 

provided for the injection formation, the confining zone immediately above the 

injection zone, the nearest adjacent porous and permeable formation to the 

confining zone, all USDWs in the area of review including existing aquifers not 

meeting the definition of a USDW that are either currently being utilized as 

private or public water supplies or are identified as a future water supply, as 

well as for any additional formations as required by the Director. 

288
Part 146.82(h)(1) AWWA recommends revising this part to read: 

Average and maximum daily injection rate and volume of the carbon dioxide 

stream. 

Part 146.82(h)(2) AWWA recommends revising this part to read: 

Average and maximum surface injection pressure; 

Part 146.82(k) AWWA recommends revising this part to read: 

Proposed stimulation program and a determination that stimulation will not 

interfere with or breach the confining layer. 

Part 146.82(n) AWWA recommends revising this part to read: 

Engineering drawings of the surface and subsurface construction details of the 

system, including design features for surge control and water hammer protection, 

including the following: 

(i) Record drawings, based upon inspections by the engineer of record or persons 

under his direct supervision, with al deviations noted; 

(ii) Copies of the mill certificates of all casings used in the construction of 

the well; 

(iii) Certification of completion submitted by the engineer of record; 

(iv) An operation manual including emergency procedures; 

(v) Proposed monitoring program and data to be submitted; 

(vi) Proof that the existence of the well and any associated monitoring wells 

have been recorded with the permanent warranty deed or other instrument of 

conveyance as a two page proviso or addendum that contains certification of the 

locations of the wells (by metes and bounds) and a detailed sketch of the parcel 

that shows the location of the well. The location shall be measured by a 

certified land surveyor, and shall contain the surveyor's signature, 

registration number, official seal, and the following statement: "I hereby 

certify that this survey was made under my responsible direction and 

supervision, and is a correct representation of the land surveyed." 

Part 146.82(q) As the Director should approve the corrective action plan prior 

to any activities taking place within the area of review, AWWA recommends 

revising this part to read: 

The plan for corrective action on artificial penetrations within the area of 

review and the status of any correction actions, if previously approved by the 

Director. 

Part 146.82(s) As the well should not yet be constructed when the owner/operator 

applies for the permit, the demonstration of mechanical integrity should not 

have occurred yet. Therefore, AWWA recommends revising this part to read: 

The proposed demonstration method for mechanical integrity pursuant to §146.89. 

289
Part 146.82(v) As monitoring wells may also have to be plugged, AWWA recommends 

revising this part to read: 

Proposed injection and monitoring well(s) plugging plan required by §146.92(b). 

Response: EPA disagrees that the suggested revisions are necessary. While EPA acknowledges and 

agrees with the importance of many of the specific items the commenter suggests adding to the text, the 

Agency believes that it is important to allow some flexibility to address the varied and site-specific 

conditions at GS sites. EPA anticipates that the iterative process by which owners or operators submit 

and Directors review geologic and other information to support the permit application will promote the 

most effective approach to addressing USDW endangerment. EPA adds that if the Director believes that 

additional information is needed to support a determination about the suitability of a proposed site, it is 

within his/her authority to request it. 

EPA notes that the final rule does include reference to capillary pressure in §146.82(a)(3)(iii), “Data on 

the depth, areal extent, thickness, mineralogy, porosity, permeability, and capillary pressure of the 

injection and confining zone(s); including geology/facies changes based on field data which may include 

geologic cores, outcrop data, seismic surveys, well logs, and names and lithologic descriptions.” 

EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available 

at the time the owner or operator develops their initial permit application. In response to comments and 

based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that 

the final regulation specifies separate requirements for information to be submitted with the permit 

application and before well construction is approved (at §146.82(a)) and information to be submitted 

before operation of the well is authorized (at §146.82(c)). 

EPA is developing guidance on site characterization for GS projects to assist owners or operators and 

Directors in evaluating permit requirements and applications under §146.82. The guidance provides 

recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site 

as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the 

injection and confining zone. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: Part 146.83(a)(1) AWWA recommends revising this part to read: 

An injection zone of sufficient areal extent, thickness, porosity, and 

permeability to receive the total anticipated volume of the carbon dioxide 

stream, and at a depth with sufficient overburden pressure to keep the carbon 

dioxide stream as a supercritical fluid. 

Response: EPA disagrees that the GS rule should require that the CO2 remain in a supercritical state. 

EPA believes that, in many cases CO2 will be injected at depths where it will remain supercritical. 

However, the final rule does not require that it remain in a supercritical state once it is injected; nor does 

the rule preclude the injection of gaseous CO2 into shallower non-USDWs provided that the owner or 

operator meets the Class VI requirements and ensures protection of USDWs from endangerment. 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23728

290
Other EPA Comment Codes and Descriptions: 3120 2.1.2 Need to identify additional confining and 

containment zones (seeking comment) 

Comment: Part 146.83(b) This part of the rule should a requirement, not an option that 

can be requested at the discretion of the Director. While it is possible that a 

site with a single confining can provide storage integrity, AWWA recommends that 

additional confining layers at the site be characterized to get a better 

estimate of leakage risk to USDWs and possibly identify additional monitoring 

zones. It is important to know if these zones exist, and to have adequately 

documented their characteristics, to evaluate and demonstrate the possibility of 

secondary containment. AWWA recommends revising this part to read: 

Owners or operators of Class VI wells must identify and characterize additional 

zones that will impede vertical fluid movement, are free of faults, fractures or 

other discontinuities that may interfere with containment, allow for pressure 

dissipation, and provide additional opportunities for monitoring, mitigation and 

remediation. 

Response: EPA agrees with the commenter that, in some situations, the presence of additional confining 

and containment zones above the primary (i.e., lowermost) confining zone can improve USDW 

protection from endangerment. EPA disagrees that secondary confining zones are required at all sites, 

e.g., where a primary confining zone that free of transmissive faults or fractures and of sufficient areal 

extent and integrity to contain the injected carbon dioxide stream and displaced formation fluids and 

allow injection at proposed maximum pressures and volumes without initiating or propagating fractures 

in the confining zone(s) (per §146.83(a)) is demonstrated to be present. The final regulation retains the 

requirement at §146.83(b) which affords the Director discretion to require owners or operators to 

identify and characterize additional zones. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Part 146.84 It is important to note that the carbon dioxide plume will never 

cease moving. Even deep formations have a natural flow gradient, and it is 

likely that there will always be some movement due to changes in density 

gradients and diffusion. This should be considered when defining the AoR for 

each project. 

Response: EPA agrees with the commenter that there may be cases where movement of the CO2 plume 

will never cease due to gradient, diffusion, and density gradients, but disagrees that the AoR definition 

at 146.84(a) should describe a never-ending timeframe of CO2 plume movement. The GS regulation 

recognizes that plume movement may stabilize to a point where movement of the CO2 plume slows or 

pressures in the injection zone sufficiently decline to the point that they no longer pose an endangerment 

to USDWs, although movement does not completely cease. EPA believes that in all cases, these criteria 

will be met at some point after the cessation of injection. As discussed in the preamble to the proposed 

GS regulation and the associated background document "Computational Modeling of Underground 

Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk to Underground 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23729

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23730

291
Sources of Drinking Water" (cited in the proposed rule preamble as USEPA, 2008d), research has 

shown that CO2 may continue to migrate for a period of time after injection ceases. 

For this reason, the GS regulation does not specify a timeframe over which the AoR delineation model 

should run. Rather, the model should be used to predict the ultimate plume movement up to the point the 

plume movement ceases or pressures in the injection zone sufficiently decline to the point that they no 

longer pose an endangerment to USDWs. 

EPA believes that an iterative process of AoR reevaluation is appropriate to verify that the CO2 plume 

and pressure front are moving through the subsurface as predicted, verify the accuracy of the delineation 

model (or identify needed changes), and refine testing and monitoring activities to ensure that USDWs 

are protected from endangerment and that there would be adequate warning of potential problems at the 

site before any endangerment could occur. EPA adds that the requirement at 146.93(b) for post-injection 

site care further ensures that any continued movement of the CO2 plume and pressure front will be 

addressed until it can be demonstrated that the GS operation no longer poses an endangerment risk to 

USDWs. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Part 146.84(c)(1)(iii) AWWA recommends revising this part to read: 

Consider potential migration through faults, fractures, other discontinuities 

and artificial penetrations. 

Response: EPA did not change 146.84(c)(1)(iii) but instead changed the text at 146.84(c)(1)(ii) to read 

as follows: "Take into account any geologic heterogeneities, other discontinuities, data quality, and their 

possible impact on model predictions" to address the water association commenter's concern regarding 

the potential for migration of CO2 at GS sites. 

Other EPA Comment Codes and Descriptions: 3200 2.2 Proposed Area of Review and Corrective 

Action Requirements (40 CFR 146.84) 

Comment: Part 146.84(c)(2) AWWA recommends revising the first sentence to read: 

Using methods approved by the Director, identify all penetrations, including 

active and abandoned wells and underground mines, in the area of review that may 

penetrate any portion of the confining zone. 

Response: EPA clarifies that the mapping and cross sections required to be submitted under 146.82(a)

(3) will define the limits of the confining zone, which would be accounted for in the AoR delineation 

and corrective action evaluation required at 146.84(c). EPA adds that owners or operators must also, 

under 146.82(a)(2), submit a map of the AoR that shows all injection wells, producing wells, abandoned 

wells, plugged wells or dry holes, deep stratigraphic boreholes, State or EPA approved subsurface 

cleanup sites, surface bodies of water, springs, mines (surface and subsurface), quarries, water wells and 

other pertinent surface features including structures intended for human occupancy and roads. EPA 

believes that these requirements address the commenter's concerns. 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23731

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23732

292
EPA adds that any well that penetrates the confining zone, even if it does not extend all the way through 

the confining formation, is to be included in the tabulation. EPA is issuing guidance on how to identify 

all wells that require corrective action. The guidance describes EPA's recommended approaches for the 

data to be considered in an initial AoR delineation, how to apply computational modeling to delineate 

the AoR, performing corrective action at GS sites, and, when appropriate, completing AoR 

reevaluations. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3530 2.2.3.1 AoR reevaluation frequency (seeking 

comment) 

Comment: Part 146.84(d) Based upon our comments in the previous section of this document, 

AWWA recommends revising this part to read: 

At the minimum fixed frequency, not to exceed one (1) year for the first ten 

(10) years of the operation of the carbon sequestration project and not to 

exceed five (5) years after the first ten year time period, as specified in the 

approved area of review and corrective action plan, or when monitoring and 

operational conditions warrant, owners or operators must: 

Response: EPA agrees with commenters that reevaluations of the AoR every ten years may not be 

sufficient to appropriately model plume and pressure front movement, establish conditions for corrective 

action, and ensure protection of USDWs from endangerment. For these reasons, the Agency changed the 

minimum frequency for the AoR reevaluation at §146.84(e) from 10 years to at least every 5 years in the 

final GS rule. EPA believes that this revised frequency addresses commenters' concerns about the 

inherent uncertainties in modeling CO2 movement, the emerging nature of GS technology, risk-based 

targeting of monitoring activities, and the unique nature of CO2 GS. In addition, the Director has 

discretion to require more frequent AoR reevaluation if he or she has reason to believe, based on sitespecific information, that a five-year reevaluation schedule is not sufficiently protective of USDWs. 

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

responsibility requirements (40 CFR 146.85) 

Comment: Part 146.85(b) AWWA believes that potential changes in the size of the area of 

review require that all site plans be reevaluated at the same frequency as the 

area of review. Therefore, AWWA recommends revising this part to read: 

The owner or operator must provide to the Director, at the same frequency as the 

AOR reevaluation, written updates of adjustments to the cost estimate to account 

for any amendments to the area of review and corrective action plan (§146.84), 

the testing and monitoring plan (§146.90), the injection well plugging plan 

(§146.92), the post-injection site care and site closure plan (§146.93), and the 

emergency and remedial response plan (§146.94). 

Response: EPA agrees that it is important to periodically update cost estimates that support financial 

responsibility determinations. The final GS rule, at §146.85(c), requires the owner or operator to provide 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23733

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23734

293
updates to the cost estimate within 60 days of any amendments to the AoR and corrective action plan, 

the injection well plugging plan, the PISC and site closure plan, and the emergency and remedial 

response plan. Owners or operators must also adjust the estimates for inflation annually under §146.85

(c)(2). EPA adds that the Director can also require the owner or operator to provide an adjustment of the 

cost estimate if the Director determines that the original demonstration is no longer adequate, as 

specified at §146.85(e). 

Other EPA Comment Codes and Descriptions: 3800 2.3 Proposed Injection Well Construction 

Requirements (40 CFR 146.86) 

Comment: Part 146.86(b)(1) AWWA recommends revising the second to the last sentence to 

read: 

The casing and cementing program must be designed to prevent the movement of 

fluids into or between USDWs and between the injection zone(s) and USDWs. 

Response: EPA believes that the existing language as written ensures the prohibition of fluid movement 

between the injection zone and any USDW and the suggested change is unnecessary. Based on its 

evaluation of all public comments and input on the proposed rule and NODA and Request for Comment 

EPA has made many revisions to the GS rule. Please see the final rule and preamble for additional 

information. 

Other EPA Comment Codes and Descriptions: 3862 2.3.3.1 Use of corrosion-resistant construction 

materials (seeking comment) 

Comment: Part 146.86(b)(1)(v) The corrosiveness evaluation should include the possible 

combining of the carbon dioxide stream and the injection zone water, which has a 

higher potential to corrode than the carbon dioxide alone. AWWA recommends 

revising this part to read: 

Corrosiveness, chemical compatibility and reactivity of the carbon dioxide 

stream and the formation fluids located within the injection zone. 

Response: EPA clarifies that reference to corrosiveness of the CO2 stream in §146.86 refers to the 

potential for CO2 to be corrosive in the presence of water or formation fluids. EPA believes that the risk 

of creating acidic fluids that could come in contact with well materials and cements is addressed by the 

construction requirements in §146.86 to ensure protection of USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 3864 2.3.3.2 Use of corrosion-resistant cements 

(seeking comment) 

Comment: Part 146.86(b)(1)(viii)AWWA recommends revising this part to read: 

Type or grade of cement and chemical compatibility and reactivity of cement and 

formation fluids located within the injection zone. 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23735

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23736

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23737

294
Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS rule. Please see the final rule and the 

discussion of financial responsibility in the preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Part 146.87(b) AWWA suggests that submittal of the cores to the Director is not 

very practical. The requirement should be rewritten to state that the Director 

should be provided with a summary report describing the cores and the test 

results. The operator should be required to first submit a coring plan to the 

Director listing the intervals to be cored, the coring procedures, the tests to 

be conducted and proposed storage of the core for review and consideration of 

approval by the Director. A core report, including the test results, 

geomechanical characteristics, and values calculated from the testing, such as 

fracture gradient, should be submitted to the Director. The owner/operator 

should make the cores available for inspection by the Director upon the request. 

AWWA recommends revising this part to read: 

The owner or operator must submit to the Director a report describing whole 

cores or sidewall cores representative of the injection zone and confining 

system and formation fluid samples from the injection zone(s). The Director may 

accept data from cores and fluid samples from nearby wells if the owner or 

operator can demonstrate that such data are representative of conditions at the 

well. The Director may require the owner or operator to core other formations in 

the borehole to acquire more information on the subsurface geologic 

characteristics. 

Response: EPA clarifies that it is not the Agency's intent that physical cores be submitted to the 

Director. In the final GS rule, EPA has revised the first sentence of §146.87(b) to read as follows: "The 

owner or operator must take whole cores or sidewall cores of the injection zone and confining system 

and formation fluid samples from the injection zone(s), and must submit to the Director a detailed report 

prepared by a log analyst that includes: well log analyses (including well logs), core analyses, and 

formation fluid sample information...." 

Other EPA Comment Codes and Descriptions: 4110 2.4.1.1 Injection pressure limitations 

Comment: Part 146.88(a) AWWA is concerned that the limitation on injection pressure to 

90% of the fracture pressure is not stringent enough. We heard it stated at the 

public hearing in Denver that fracturing of the injection formation can occur 

when injection pressures are below 90% of the fracture pressure. It is important 

to consider that injection pressure limitations need to take account of the 

possibility that, under certain conditions, faults can be re-activated even if 

injection pressures are kept below the level necessary to create new fractures 

or propagate existing fractures. Therefore, the regulation should provide for 

the injection pressure to be calculated based on the site geology, hydrogeology 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23738

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23739

295
and geomechanics, in combination with the injection pressure limitation. 

Injection pressures and rates should be determined by well tests and 

geomechancial studies, taking into account both formation fracture pressure and 

formation parting pressure. However, due to the amount of uncertainty associated 

with this topic, AWWA recommends that EPA research their proposed limitation in 

more detail to determine the best method for preventing possible contamination 

of USDWs. Therefore, we recommend revising this part to read: 

The owner or operator must ensure that injection pressure and rates remain 

within limits established by permit. Such permit limitations shall be based on 

well tests and geomechanical studies, including assessments of both the fracture 

pressure of the confining zone and the parting pressure of the confining zone. 

In no case may injection pressure initiate or propagate fractures in the 

confining zone, cause otherwise non-transmissive faults transecting the 

confining zone to become transmissible, otherwise degrade the integrity of the 

confining zone, or cause the movement of injection or formation fluids that 

endangers a USDW. 

Response: EPA agrees that the operator must remain within limits established by the Class VI permit. 

EPA clarifies that the owner or operator is required in §146.82(a)(7) to propose a maximum injection 

pressure as part of the permit application. The proposed injection pressure will be evaluated by the 

Director based on site-specific conditions, and be informed by data on the injection zone. During 

injection, the pressure in the injection zone must not exceed 90 percent of the fracture pressure of the 

injection zone, as specified at §146.88(a). The fracture pressure (and, therefore, the injection pressure) 

are based on site-specific geologic and geomechanical data collected during the site characterization 

process required at §146.82. If, based on this information, a lower pressure limitation is appropriate, the 

Director has the authority to set a lower limit in the operating permit. 

In response to the concern about reopening of faults at lower pressures than 90 percent of fracture 

pressure, EPA believes that the requirement for the owner or operator to submit data on known or 

suspected faults and fractures and information on the seismic history of the site will inform the 

determination of an appropriate pressure limitation in the permit. Any sites with the potential for 

reopening or reactivation of faults or unacceptable seismic risk that could otherwise interfere with 

containment will not be permitted as GS sites. 

EPA is developing guidance on site characterization for GS projects to assist owners or operators in 

meeting the requirements of §146.82 and to assist directors in evaluating permit applications. The 

guidance will describe recommended approaches for characterizing the regional geology and 

hydrogeology of a proposed site and performing the necessary geochemical, geomechanical, and 

geophysical analyses of the injection and confining zone. EPA is also developing guidance for primacy 

agencies that will include recommended approaches for evaluating owner or operator-submitted data in 

setting permit conditions. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4000 2.4 Proposed Injection Well Operating 

Requirements (40 CFR 146.88) 

Comment: Part 146.88(b) AWWA recommends revising this part to read: 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23740

296
Injection of the carbon dioxide stream between the outermost casing protecting 

USDWs and the well bore is prohibited. 

Response: EPA retains the provision as proposed, and clarifies that injection between the casing and the 

well bore is prohibited. This is consistent with requirements for other injection well classes in the UIC 

program. 

Other EPA Comment Codes and Descriptions: 4500 2.5 Proposed Mechanical Integrity Testing 

(MIT) Requirements (40 CFR 146.89) 

Comment: Part 146.89(f) AWWA recommends revising this part to read: 

The Director may require additional or alternative tests if the results 

presented by the owner or operator under paragraph (d) of this section are not 

satisfactory to the Director to demonstrate that there is no significant leak in 

the casing, tubing or packer or significant movement of fluid into or between 

USDWs, or between the injection zone(s) and USDWs, resulting from the injection 

activity as stated in paragraphs (a)(1) and (2) of this section. 

Response: EPA clarifies that the regulations at §146.89(e) allow the Director to require additional 

methods or, with the Administrator's approval, to approve the use of alternative MIT methods based on 

specific information about the site or the well. 

EPA believes that the MITs described in the rule at §146.89 are effective methods and have been used 

successfully by injection well operators for decades and provide an important early warning of potential 

problems in the injection well system. 

In addition, EPA is using an adaptive approach to regulating GS. The Agency plans to collect and 

review data every six years on GS projects to determine whether the appropriate amount and types of 

information and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Part 146.90 AWWA recommends revising this part to read: 

The owner or operator of a Class VI well must prepare, maintain, and comply with 

a testing and monitoring plan to verify that the geologic sequestration project 

is operating as permitted and is not endangering USDWs. The testing and 

monitoring plan must be submitted with the permit application, for Director 

approval, and must include a description of how the owner or operator will meet 

the requirements of this section. The testing and monitoring plan must be 

reviewed and updated, as necessary, on the same schedule as the update to the 

Area of Review. 

Response: EPA agrees that periodic updates to the plan are appropriate. EPA clarifies that the final GS 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23742

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23743

297
regulation includes a requirement that the AoR be reevaluated at least every 5 years, and it specifies at 

§146.90(j) that the operator revise the testing and monitoring plan to incorporate the results of the most 

recent AoR reevaluation and recent operational and monitoring data. Based on its evaluation of all 

public comments and input on the proposed rule and NODA and Request for Comment EPA has made 

many revisions to the GS rule. See the final rule and preamble for further discussion on EPA's final 

approach. 

EPA agrees with commenters that developing and following testing and monitoring plans is an 

important part of assuring that a GS project is operating properly and is crucial for the early detection of 

potential endangerment to USDWs. 

Other EPA Comment Codes and Descriptions: 4655 2.6.5.1 Plume tracking techniques/geophysical 

methods (seeking comment) 

Comment: Part 146.90(g) AWWA recommends revising this part to read: 

Testing and monitoring to track the extent of the carbon dioxide plume and the 

position of the pressure front by either monitoring for pressure changes in the 

confining zone, in the first formation overlying the confining zone or using 

indirect, geophysical techniques (e.g., seismic, electrical, gravity, or 

electromagnetic surveys and/or down-hole carbon dioxide detection tools); 

Response: EPA has revised the final GS regulation, at §146.90(g)(1), to require all GS project owners 

or operators to monitor for pressure changes in the injection zone. EPA believes that pressure 

monitoring in the injection zone is necessary to track the development and movement of the pressure 

front and CO2 plume. Pressure monitoring within the injection zone is necessary because any such 

monitoring above the confining zone would not detect movement of the pressure front unless a breach of

the confining zone occurs. EPA believes that monitoring using wells in the injection zone (i.e., that 

penetrate the confining zone) can be safely performed if the wells are constructed to prevent flow 

between the injection zone and USDWs or other layers above the confining zone. Such construction 

technologies exist and have been used in the oil and gas industry for years. EPA believes that the 

benefits of monitoring in the injection formation outweigh the manageable risk of those monitoring 

wells serving as conduits for fluid movement. EPA adds that owners or operators may consider and 

Directors may require performing additional pressure monitoring in wells that are above the confining 

zone (e.g., in the same wells used to perform ground water quality monitoring required at §146.90(d)) to 

provide additional verification that no pressure changes are occurring above the confining zone due to 

CO2 leakage. Monitoring also identifies needed remedial actions, provides inputs for AoR reevaluation 

modeling, and targets additional geochemical and surface monitoring needs. Knowledge of the location 

of the CO2 plume and the associated pressure front will assure the public that GS projects are 

proceeding according to plan, provide sufficient information to the owner or operator and Director, or 

allow for appropriate actions to address any indication that USDWs may be endangered. 

In addition, §146.90(g)(2) requires owners or operators to track the position of the CO2 plume using 

indirect methods (e.g., seismic, electrical, gravity, or electromagnetic surveys and/or down-hole CO2 

detection tools), unless the Director determines based on site-specific geology, that such methods are not 

appropriate. 

EPA acknowledges that, at certain sites, there may be a need for more or different monitoring schemes 

(which may include monitoring in the confining zone), and adds that it is important to balance the need 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23744

298
for adequate monitoring that ensures USDW protection from endangerment against too many artificial 

penetrations which could serve as conduits for fluid migration. Site-specific testing and monitoring plans 

must describe the proposed monitoring regime, which must be approved by the Director. 

Flexibility is also provided regarding how to monitor for the specific data required by the final rule. The 

testing and monitoring plan is developed by the owner or operator in consultation with the Director and 

is designed to ensure that a detailed, Director-approved document describing how monitoring will be 

conducted during the lifetime of the project exists. 

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in 

evaluating requirements under §146.90, including proposed monitoring plans. The guidance describes 

available technologies and recommended approaches for implementing a testing and monitoring plan, 

including pre-operational geophysical logging and testing of injection wells, MITs, injection well testing 

during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, and soil 

gas and surface air monitoring which may be required by the UIC Director for specific GS projects. The 

guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Part 146.90(h)(1) AWWA recommends revising this part to read: 

The testing and monitoring plan must be based on site-specific geologic factors, 

modeling, and a risk-assessment of potential vulnerabilities within the area of 

review; 

Response: As described above, EPA agrees that periodic updates to the plan are appropriate, and the 

final GS regulation includes a requirement that the AoR be reevaluated at least every 5 years, and it 

specifies at §146.90(j) that the operator revise the testing and monitoring plan to incorporate the results 

of the most recent AoR reevaluation and recent operational and monitoring data. Based on its evaluation 

of all public comments and input on the proposed rule and NODA and Request for Comment EPA has 

made many revisions to the GS rule. See the final rule and preamble for further discussion on EPA's 

final approach. 

Other EPA Comment Codes and Descriptions: 4760 2.7.6 Proposed reporting frequency (seeking 

comment) 

Comment: Part 146.91(11)(a) AWWA believes that the reporting frequency should be on a 

monthly basis, similar to what water and wastewater treatment plants have to do. 

The operating information for the geologic sequestration project is extremely 

important and needs to be reviewed at a frequency by the regulatory agency to 

ensure problems are identified and addressed in a timely manner. For example, 

with the way the regulation is currently structured, data collected on July 1, 

2008 would not be seen by the regulatory agency before January 15, 2009, if the 

operator is allowed 15 days to submit the report. This would allow for very 

little time to correct any potential issues in the operation of the project. As 

such, AWWA recommends revising this part to read: 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23745

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23746

299
Monthly reports, due on the 15th day of each month for the previous month’s 

activities, containing: 

Response: As described above, the final rule remains unchanged from the proposal and requires semiannual reporting of monthly average, maximum and minimum values for injection pressure, flow rate 

and volume, annular pressure, and monthly annulus fluid volume added at §146.91(a). EPA believes that 

monthly reporting of routine operational data and monitoring results would provide no additional 

protection of USDWs from endangerment. 

For additional information, please see the final rule and the preamble for a discussion of EPA's final 

approach to recordkeeping and reporting. 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: Part 146.92(b) As previously stated AWWA believes that potential changes in the 

size of the area of review require that all site plans be reevaluated at the 

same frequency as the area of review. Therefore, AWWA recommends revising this 

part to read: 

Well Plugging Plan. The owner or operator of a Class VI well must prepare, 

maintain, and comply with a plan that is acceptable to the Director. The plan 

must be reviewed and revised by the owner or operator, and submitted to the 

Director for approval, at the same frequency and time as the AOR reevaluation. 

The requirement to maintain and implement an approved plan is directly 

enforceable regardless of whether the requirement is a condition of the permit. 

The well plugging plan must be submitted as part of the permit application and 

must include the following information: 

Response: EPA agrees that developing, maintaining, and implementing an injection well plugging plan 

is important to assuring that GS wells are plugged in a manner that will ensure that the well will not 

serve as a conduit for CO2 leakage preventing endangerment of USDWs. 

EPA disagrees with the suggested change, however. The final rule requirement at §146.92(c) for the 

owner or operator to notify the Director of any changes to the injection well plugging plan at least 60 

days before plugging the well will allow the owner or operator (through communication with the 

Director) to address any issues associated with the initial well plugging plan submitted with the permit 

application. EPA is not requiring formal periodic review and updates to the injection well plugging plan 

throughout the injection phase. EPA does not expect that changes to this plan would be implemented 

until injection operations cease. EPA envisions that owners or operators will take into account similar 

considerations that guide updates to other project plans, e.g., monitoring and operational data and results 

of AoR reevaluations. 

EPA clarifies that the owner or operator's injection well plugging plan will be incorporated as a 

condition of their UIC permit and is therefore enforceable; failure to follow the approved plan would be 

considered a violation of the permit and would be subject to applicable civil, criminal, or administrative 

penalties under §1423 of the SDWA. 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23747

300
Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: Part 146.93(a) As previously stated AWWA believes that potential changes in the 

size of the area of review require that all site plans be reevaluated at the 

same frequency as the area of review. Therefore, AWWA recommends revising this 

part to read: 

The owner or operator of a Class VI well must prepare, maintain, and comply with 

a plan for post-injection site care and site closure that meets the requirements 

of paragraph (a)(2) of this section and is acceptable to the Director. The plan 

must be reviewed and revised by the owner or operator, and submitted to the 

Director for approval, at the same frequency and time as the AOR reevaluation. 

Response: As described above, the final rule requires review and revision of the post-injection and site 

care closure plan when injection ceases, as described in §146.93(a)(3). EPA is not requiring formal 

periodic review and updates to the PISC and site closure plan throughout the injection phase. EPA does 

not expect that changes to this plan would be implemented until injection operations cease. See the final 

rule and preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Part 146.93(b)(3) When addressing plume stabilization in association with site 

closure, it is important to realize that the carbon dioxide plume will never be 

completely stable. The carbon dioxide plume will continue to move by a 

combination of methods including density differences, natural formation flow 

gradients and diffusion. AWWA recommends that EPA engage in research to provide 

specific criteria on what exactly it would mean for the plume to have 

stabilized. If left up to the discretion of the various Directors, stabilization 

could be defined in many different ways. In order to have a consistent 

application of this part of the regulation, EPA should define the specific 

situations in which the plume could be considered "stable." AWWA recommends 

revising this part to read: 

Prior to authorization for site closure, the owner or operator must demonstrate 

to the Director, based on monitoring and other site-specific data that no 

additional monitoring is needed to assure that the geologic sequestration 

project does not pose an endangerment to USDWs. The demonstration must 

demonstrate all of the following: 

(i) the estimated magnitude and extent of the project footprint (CO2 plume and 

the area of elevated pressure) based on measurements and modeling; 

(ii) that CO2 movement and pressure changes match model predictions, 

(iii) the estimated location of the detectable CO2 plume based on measurement 

and modeling (measuring magnitude of saturation within the plume or mapping the 

edge of it); 

(iv) that there is no evidence of significant leakage of either CO2 or displaced 

formation fluids that endanger USDWs; 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23748

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23749

301
(v) that the CO2 plume and displaced formation fluid are not expected to migrate 

in the future in a manner that encounters a potential leakage pathway; 

(vi) that the injection wells at the site completed into or through the 

injection zone or confining zone are properly plugged and abandoned; and, 

(vii) any remaining project monitoring wells at the site are being managed by a 

person and in a manner acceptable to the Director. 

Response: EPA acknowledges that many site-specific factors will influence the determination of when 

the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for this reason 

that EPA believes that individual UIC Directors, in consultation with operators, will be in the best 

position to determine whether additional post-injection site care is needed. EPA expects this decision to 

be made based on relevant site data and in consultation with all potentially impacted parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time 

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that a 

complete cessation of plume movement is not required, only a demonstration that the plume and 

pressure front no longer pose a risk of endangerment to USDWs. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will assist 

Directors in evaluating proposed well plugging plans and post-injection site care and site closure plans 

under §146.92 and §146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells; perform post-injection monitoring; demonstrate non 

endangerment; and perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: Part 146.94(a) It is important that the emergency and remedial response plan is 

reviewed and updated on the same schedule as the area of review update. Changes 

in the area of review could affect the actions that would need to be taken in 

the event of an emergency. AWWA recommends revising this part to read: 

As part of the permit application, the owner or operator must provide the 

Director with an emergency and remedial response plan that describes actions to 

be taken to address movement of the injection or formation fluids that may cause 

an endangerment to a USDW during construction, operation, closure and postclosure periods. The emergency and remedial response plan must be reviewed and 

updated, as necessary, on the same schedule as the update to the Area of Review. 

Response: EPA has added a requirement at §146.94(d) that owners or operators must review their 

emergency and remedial response plan within one year of an AoR reevaluation required under §146.84 

or following significant changes to the facility. Subsequently, owners or operators must submit an 

amended plan or demonstrate to the Director that no amendment to the plan is needed based on the AoR 

reevaluation or any significant changes made to the facility. 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23751

302
Other EPA Comment Codes and Descriptions: 4660 2.6.6 Geochemical monitoring 

Comment: Part 146.90(d) AWWA recommends revising this part to read: 

Periodic monitoring of the ground water quality and geochemical changes within 

(if wells can be installed without adversely affecting the integrity of the 

confining zone) and above the confining zone(s) that may be a result of carbon 

dioxide movement through the confining zone or additional identified zones: 

Response: EPA clarifies that §146.90(d) requires geochemical monitoring above the confining zone. To 

mitigate the risk of fluid movement, EPA requires owners and operators to submit a testing and 

monitoring plan that describes how the owner or operator plans to site and construct monitoring wells. 

EPA believes that monitoring using wells in the injection zone, e.g., for pressure monitoring as required 

at §146.90(g)(1), can be safely performed if the wells are constructed to prevent flow between the 

injection zone and USDWs or other layers above the confining zone. Such construction technologies 

exist and have been used in the oil and gas industry for years. EPA believes that properly constructed 

monitoring wells will be a safe way to obtain the data that is essential to ensure that the injected CO2 

remains confined in the injection zone and that pressure changes are not causing movement of formation 

or other fluids. To mitigate the risk of fluid movement, EPA requires owners and operators to submit a 

testing and monitoring plan that describes how the owner or operator plans to site and construct 

monitoring wells. EPA is developing guidance on well construction that will include recommendations 

for monitoring well construction. The guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in 

evaluating requirements under §146.90, including proposed monitoring plans. The guidance describes 

available technologies and recommended approaches for implementing a testing and monitoring plan, 

including pre-operational geophysical logging and testing of injection wells, MITs, injection well testing 

during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, and soil 

gas and surface air monitoring which may be required by the UIC Director for specific GS projects. The 

guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: Part 146.90(d)(1) AWWA recommends revising this part to read: 

The location and number of monitoring wells must be based on specific 

information about the geologic sequestration project, including injection rate 

and volume, geology, the presence of natural discontinuities and artificial 

penetrations and other factors. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS rule. See the final rule and preamble 

for further discussion on EPA's final approach. 

EPA's guidance on testing and monitoring will provide guidance on monitoring well placement. The 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24332

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24339

303
guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: Part 146.92(b)(5) AWWA recommends revising this part to read: 

The type and grade and quantity of material to be used in plugging. The material 

must be compatible with the carbon dioxide stream and pre-injection formation 

conditions; and 

Response: EPA believes, considering the potentially corrosive nature of CO2 when it is in contact with 

water, that the requirement that the material must be compatible with the CO2 stream is appropriate. The 

final rule retains this requirement. 

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment) 

Comment: Part 146.93(b)(2) AWWA recommends that there should be a minimum 50 year postinjection monitoring period for all carbon sequestration projects. This time 

period is necessary to monitor the site for changes that may occur over a longer 

amount of time, such as gradual leakages, or sudden seismic shifts. After this 

time period, the owner/operator may apply to the Director for a modification or 

termination of the monitoring requirements. AWWA recommends revising this part 

to read: 

If, after the 50-year post-injection monitoring period, the owner or operator 

can demonstrate to the satisfaction of the Director, based on monitoring and 

other site-specific data, that the geologic sequestration project no longer 

poses an endangerment to USDWs, the Director may approve an amendment to the 

post-injection site care and site closure plan to reduce the frequency of 

monitoring or may authorize site closure before the end of the 50-year period. 

Response: As described above, EPA agrees with commenters that a 50 year post-injection site care 

timeframe represents a reasonable and protective post-injection site monitoring period in most cases and 

available data, including data submitted by commenters, do not support a different default timeframe. 

EPA bases this on a review of research studies, industry reports, and existing environmental programs, 

and evaluation of public comments. Furthermore, EPA believes that a 50-year default post-injection site 

care timeframe is not overly burdensome, does not exaggerate the risks associated with GS, is consistent 

with other environmental programs, and sufficiently protects USDWs from endangerment. For this 

reason, the final GS regulation retains the 50 year post-injection site care timeframe, as specified in 

§146.93(b)(1). 

However, EPA disagrees that a 50 year post-injection site care timeframe should be an absolute 

minimum. Rather, EPA believes, as some commenters suggest, that there will be circumstances where it 

can be demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24371

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24372

304
endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility regarding 

the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the 

PISC timeframe during the post-injection period based on site-specific data, pursuant to requirements at 

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to 

demonstrate, during the permitting process based on substantial data, that an alternative PISC timeframe 

may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for 

post-injection site care will be necessary in most cases. The default 50 year post-injection site care 

timeframe represents a reasonable and protective monitoring period based on a review of research 

studies, industry reports, and existing environmental programs, and evaluation of public comments. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

Other EPA Comment Codes and Descriptions: 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Part 146.93(c) AWWA recommends that this part of the rule needs to include a 

directive that the Director needs to provide approval for site closure prior to 

implementation of the site-closure plan. AWWA recommends revising this part to 

read: 

Notice of intent for site closure. The owner or operator must notify the 

Director at least 120 days before site closure. At this time, if any changes 

have been made to the original post-injection site care and site closure plan, 

the owner or operator must also provide the revised plan. The Director must 

provide approval for site closure prior to the implementation of the site 

closure plan. At the discretion of the Director, a shorter notice period may be 

allowed. 

Response: EPA considers the combination of the Director's evaluation of the data submitted to support a 

demonstration of non-endangerment of USDWs, as specified in §146.93(b)(3), and the Director's receipt 

of and agreement with the notification of intent for site closure as confirmation that GS site closure can 

proceed. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82) 

Comment: Part 146.82(d)(3) AWWA recommends revising this part to read: 

Information on the seismic history within the proposed area of review including 

presence and depth of seismic sources, knowledge of previous seismic events and 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24373

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24374

305
history of these events, and a determination that the seismicity would not 

interfere with containment. 

Response: EPA agrees that consideration of local and regional seismicity is important. This information 

is required for GS projects at §146.82(a)(3)(v). The site characterization provisions in the GS rule also 

require the owner or operator to submit data on known or suspected faults in the AoR (§146.82(a)(3)

(ii)). Beyond the AoR (the specific project area) EPA notes that the site characterization requires a 

review of the local and regional geology, and detailed review of any known or potential seismically 

active terrain in the vicinity of a proposed GS site would certainly be required in a GS site 

characterization. 

Other EPA Comment Codes and Descriptions: 3420 2.2.2.1 Scope of the inventory process (e.g., 

reliance on publicly available information, depth of wells) 

Comment: Part 146.84(d) AWWA recommends revising this part to read: 

Owners or operators of Class VI wells must perform corrective action on all 

wells and other artificial penetrations in the area of review that are 

determined to need corrective action using methods necessary to prevent the 

movement of fluid into or between USDWs and between the injection zones(s) and 

USDWs, including use of corrosion resistant materials, where appropriate. 

Response: EPA revised the text at §146.84(d) to require the use of materials that are "compatible with 

the carbon dioxide stream." EPA believes this language change addresses commenters' concerns and is 

also consistent with other language regarding materials requirements in the GS rule. EPA believes that 

meeting the requirement for preventing "movement of fluid into or between USDWs" will prevent 

movement between the injection zone and USDWs; therefore, it did not make the suggested change. 

Other EPA Comment Codes and Descriptions: 3800 2.3 Proposed Injection Well Construction 

Requirements (40 CFR 146.86) 

Comment: Part 146.86(b)(1)(i) AWWA recommends revising this part to read: 

Depth to the injection zone and overburden pressures in the injection zone. 

Response: EPA believes that the requirement in 146.86(b)(ii) to report the external pressure provides 

the same information as the requested change. Based on its evaluation of all public comments and input 

on the proposed rule and NODA and Request for Comment EPA has made many revisions to the GS 

rule. Please see the final rule and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: Part 146.83(a)(2) AWWA recommends revising this part to read: 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24375

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24376

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24377

306
A confining zone(s) that is free of transmissible faults or fractures and of 

sufficient areal extent and integrity to contain the injected carbon dioxide 

stream and displaced formation fluids and allow injection at proposed maximum 

pressures and volumes without initiating or propagating fractures in the 

injection and confining zone(s). 

Response: EPA acknowledges the importance of selecting GS sites with confining zones that are free of 

transmissive faults and fractures but disagrees that the rule should prohibit fracturing within the injection 

zone. EPA believes that, in some circumstances, fracturing is necessary (i.e., in association with an 

approved for stimulation program to improve wellbore and formation injectivity). EPA clarifies that all 

stimulation for GS must be approved by the Director pursuant to requirements at §146.91. 

Other EPA Comment Codes and Descriptions: 2048 1.5.2.4 Oppose Class VI/ Support Class V 

experimental technology well 

Comment: Rule Provision: 144.15 

Proposed CCS Group Recommendations: 4. Adding §144.15 to read as follows. 

§144.15 Prohibition of non-experimental Class V wells for geologic 

sequestration. 

The construction, operation or maintenance of any non-experimental Class V 

geologic sequestration well is prohibited. 

Basis for CCS Group Comments: This provision should be deleted if EPA does limit 

Class VI wells to injection below the lowermost USDW in the final rule to allow 

Directors to selectively authorize GS in areas with USDWs below the injection 

zone. 

Response: The text at 144.15 is retained in the final regulation; the construction, operation or 

maintenance of any non-experimental Class V GS well is prohibited under the final rule. The final rule 

contains tailored requirements for Class VI wells to ensure that GS projects are permitted, sited, 

constructed, operated, and closed in a manner that avoids releases of CO2 into USDWs. 

Comment: Rule Provision: 144.18 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA's rationale. 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24364

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24365

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24366

307
Other EPA Comment Codes and Descriptions: 5700 2.12 Comments on the proposed duration of 

Class VI permits (seeking comment) 

Comment: Rule Provision: 144.36 

Proposed CCS Group Recommendations: (a) Permits for Class I and V wells shall be 

effective for a fixed term not to exceed 10 years EXCEPT FOR WELLS USED FOR 

GEOLOGIC SEQUESTRATION. UIC Permits for Class II AND III and VI wells shall 

be issued EFFECTIVE for a period up to the operating life of the facility. 

PERMITS FOR CLASS VI WELLS AND FOR OTHER WELLS USED FOR GEOLOGIC 

SEQUESTRATION 

OF CO2 STREAMS SHALL BE EFFECTIVE FOR THE PERIOD THROUGH SITE CLOSURE. 

Basis for CCS Group Comments: Permits are necessary for geologic sequestration 

wells through the end of the post closure monitoring phase, which is consistent 

with the term site closure in the amended requirement. 

Response: EPA clarifies that the final GS rule specifies that Class VI permits will be issued for the 

operating life of the facility and the post-injection site care period (144.36(a)). EPA believes that 

including the phrase "other wells used for geologic sequestration of CO2 streams" is unnecessary, 

because all wells used to inject CO2 for the purpose of GS will be classified as Class VI wells. See also 

discussion in the preamble on grandfathered experimental Class V wells and transitioning Class II to 

Class VI wells. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 144.51(q)(1) 

Proposed CCS Group Recommendations: (q) (1) The owner or operator of a Class I, 

II, III or VI well permitted under this part shall establish mechanical 

integrity prior to commencing injection or on a schedule determined by the 

Director. Thereafter the owner or operator of Class I, II, and III wells must 

maintain mechanical integrity as defined in §146.8 and the owner or operator of 

Class VI wells must maintain mechanical integrity as defined in §146.89 of this 

chapter. 

Basis for CCS Group Comments: EPA may want to reconsider the use of the term 

"or" as this implies that an initial MIT can be optional based on Directors 

discretion which contradicts 146.89 with respect to Class VI wells. 

Alternatively, the two provisions can be read together to require an initial MIT 

and to give the Director limited discretion to allow the scheduling of the 

initial MIT after some injection has occurred, such as may be required during 

initial testing of the well and injection zone. 

Response: EPA disagrees that the suggested edit is needed, and clarifies that all owners or operators 

must demonstrate internal and external mechanical integrity prior to commencing injection as required 

at §146.87(a)(4). 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24369

308
Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: Rule Provision: 144.39 

Proposed CCS Group Recommendations: THESE SECTIONS MAY REQUIRE FURTHER 

REVISIONS 

TO PROVIDE CONFORMING LANGUAGE. 

Basis for CCS Group Comments: The multi-stakeholder group has agreed that 

proposed language describing wells in classification (b)(4) establishes a 

"bright line" definition for wells that inject CO2 for EOR/EGR and GS and, 

consistent with EPA’s intent, should remain in Class II and be subject to the 

current requirements of Class II. We have also agreed that the wells used for GS 

in oil and gas reservoirs that do not meet the criteria of (b)(4) should be 

subject to additional requirements. We have tentatively defined such wells as 

wells used "for geologic sequestration in oil and gas formations and where the 

criteria of paragraph (b)(4) are not met." But we have not yet attempted to 

define what specific requirements should apply to these wells. We are committed 

to working toward agreement on those requirements (probably within a Class II 

context) and submitting the results of that effort to EPA by February 28, 2009 

for your consideration. 

In addition, we recommend that all GS into basalts, coal seams, and salt domes 

be conducted under Class V as experimental wells initially and then as 

commercial scale Class V wells/projects if the experimental projects demonstrate 

that these sites can be suitable for geological sequestration while preventing 

endangerment of USDWs. 

Response: As described above, EPA agrees that injection of CO2 for the primary purpose of enhancing 

oil and gas recovery should remain under the Class II Program. However, the Agency disagrees that 

wells injecting CO2 for the primary purpose of long-term storage should be regulated under Class II 

requirements. EPA recognizes that the oil and gas industry has decades of experience injecting CO2 for 

the purpose of EOR, and that sites used for EOR may be suitable for GS and may be among the first GS 

sites. EPA also recognizes that a by-product of EOR activities is that a certain percentage of the CO2 is 

trapped in the receiving formation. 

The Agency believes that the nature and risks of CO2 injection for the primary purpose of long-term 

storage pose different risks than injection for the primary purpose of ER, and therefore has developed 

new Class VI regulations to address these unique risks. For example, the volume of CO2 anticipated to 

be injected for long-term storage is significantly greater than for EOR operations. Reservoir pressure 

conditions will also be different, with Class VI injection operations involving large volumes of CO2 and 

likely having higher pressures within their storage formations than Class II EOR projects. 

As described above, EPA clarifies that the GS rule does not categorically preclude injection of CO2 into 

any non-USDW formation types. If an owner or operator can demonstrate to the Director's satisfaction 

that GS in coal seams, basalts, salt domes, or shales can be accomplished in a manner that protects 

USDWs and meets all of the requirements of the GS rule, the project may be permitted as a Class VI 

well. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24370

309
The Agency anticipates that, in the near-term, most GS in unmineable coal seams will continue to be 

experimental. Such projects may be permitted as Class V experimental technology wells if they are of an 

experimental nature (i.e., to test GS technologies and collect data). EPA will continue to review data on 

early GS projects, including those in unmineable coal seams, to determine whether the appropriate 

amount and types of information and documentation are required and being collected. EPA plans, every 

six years, to collect and review data on GS projects to determine whether the appropriate amount and 

types of information and appropriate documentation are being collected, and to determine if 

modifications to the requirements are appropriate or necessary. 

Other EPA Comment Codes and Descriptions: 5900 2.14 Other administrative requirements under 40 

CFR 144 

Comment: Rule Provision: 144.52 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 5900 2.14 Other administrative requirements under 40 

CFR 144 

Comment: Rule Provision: 144.55 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: Rule Provision: 144.80 

Proposed CCS Group Recommendations: (b) Class II. Classification of Wells: (b) 

Class II. Wells which inject fluids:.......(2) for enhanced recovery of oil or 

natural gas; (3) For storage of hydrocarbons.... and 

(4) FOR ENHANCED RECOVERY OF OIL OR NATURAL GAS WHERE GEOLOGIC 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24378

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24379

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24380

310
SEQUESTRATION IS 

OCCURRING DURING OR IN CONNECTION WITH ENHANCED RECOVERY OF OIL OR 

NATURAL GAS 

PROVIDED (I) THERE IS REASONABLE EXPECTATION OF MORE THAN INSIGNIFICANT 

FUTURE 

PRODUCTION VOLUMES OR RATES AS A RESULT OF CARBON DIOXIDE INJECTION AND 

(II) 

OPERATING PRESSURES ARE NO HIGHER THAN REASONABLY NECESSARY TO PRODUCE 

SUCH 

VOLUMES OR RATES; 

Basis for CCS Group Comments: EPA’s Proposal would continue to regulate and 

permit injection of CO2 for EOR/EGR purposes as Class II injection "as long as 

any production is occurring." EPA has asked for comment on the merits of this 

approach "since owners or operators of some Class II EOR/EGR wells may wish to 

use wells for the purposes of production and GS prior to the field being 

completely depleted." 73 Fed. Reg. at 43502. We recommend that the rules be 

clarified to provide more certainty about the applicability of Class II 

requirements where GS of CO2 occurs in connection with EOR/EGR activities. 

Specifically, the UIC rules should provide a "bright line" definition as to the 

applicable class of wells where CO2 injection for EOR/EGR production and for GS 

occur in tandem. 

The proposed language describing wells in classification (b)(4) establishes a 

"bright line" definition for wells that inject CO2 for EOR/EGR and GS and, 

consistent with EPA’s intent, should remain in Class II and be subject to the 

current requirements of Class II. We have also agreed that the wells used for GS 

in oil and gas reservoirs that do not meet the criteria of (b)(4) should be 

subject to additional requirements. 

This is the same recommendation as presented by the multi-stakeholder group, in 

which the Carbon Sequestration Council participated. 

Response: As described above regarding the suggested edit at 144.6, EPA did not make the suggested 

change to 144.80. The Agency disagrees that wells injecting CO2 for the primary purpose of long-term 

storage should be regulated under Class II requirements. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment, EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

Comment: Rule Provision: 144.80(e) 

Proposed CCS Group Recommendations: Support the proposed language. 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24381

311
Other EPA Comment Codes and Descriptions: 5900 2.14 Other administrative requirements under 40 

CFR 144 

Comment: Rule Provision: Part 146 (12) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: Rule Provision: 146.5(f) 

Proposed CCS Group Recommendations: (b) Class II. Classification of Wells: (b) 

Class II. Wells which inject fluids:.......(2) for enhanced recovery of oil or 

natural gas; (3) For storage of hydrocarbons..... and 

(4) FOR ENHANCED RECOVERY OF OIL OR NATURAL GAS WHERE GEOLOGIC 

SEQUESTRATION IS 

OCCURRING DURING OR IN CONNECTION WITH ENHANCED RECOVERY OF OIL OR 

NATURAL GAS 

PROVIDED (I) THERE IS REASONABLE EXPECTATION OF MORE THAN INSIGNIFICANT 

FUTURE 

PRODUCTION VOLUMES OR RATES AS A RESULT OF CARBON DIOXIDE INJECTION AND 

(II) 

OPERATING PRESSURES ARE NO HIGHER THAN REASONABLY NECESSARY TO PRODUCE 

SUCH 

VOLUMES OR RATES; 

Basis for CCS Group Comments: EPA’s Proposal would continue to regulate and 

permit injection of CO2 for EOR/EGR purposes as Class II injection "as long as 

any production is occurring." EPA has asked for comment on the merits of this 

approach "since owners or operators of some Class II EOR/EGR wells may wish to 

use wells for the purposes of production and GS prior to the field being 

completely depleted." 73 Fed. Reg. at 43502. We recommend that the rules be 

clarified to provide more certainty about the applicability of Class II 

requirements where GS of CO2 occurs in connection with EOR/EGR activities. 

Specifically, the UIC rules should provide a "bright line" definition as to the 

applicable class of wells where CO2 injection for EOR/EGR production and for GS 

occur in tandem. 

The proposed language describing wells in classification (b)(4) establishes a 

"bright line" definition for wells that inject CO2 for EOR/EGR and GS and, 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24387

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24388

312
consistent with EPA’s intent, should remain in Class II and be subject to the 

Response: As described above, EPA did not make the suggested change. The Agency disagrees that 

wells injecting CO2 for the primary purpose of long-term storage should be regulated under Class II 

requirements. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment, EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

The Agency believes that the nature and risks of CO2 injection for the primary purpose of long-term 

storage pose different risks than injection for the primary purpose of ER, and therefore has developed 

new Class VI regulations to address these unique risks. For example, the volume of CO2 anticipated to 

be injected for long-term storage is significantly greater than for ER operations. Reservoir pressure 

conditions will also be different, with Class VI injection operations involving large volumes of CO2 and 

likely having higher pressures within their storage formations than Class II ER projects. 

Other EPA Comment Codes and Descriptions: 5900 2.14 Other administrative requirements under 40 

CFR 144 

Comment: Rule Provision: 146.5(e) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble as well as the rulemaking docket. 

Comment: Rule Provision: 146, Subpart H, List of Headings 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 2048 1.5.2.4 Oppose Class VI/ Support Class V 

experimental technology well 

Comment: Rule Provision: 146.81(b) 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24389

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24394

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24398

313
Proposed CCS Group Recommendations: (b) This subpart applies to wells used to 

inject carbon dioxide EXCLUSIVELY for the purpose of geologic sequestration, 

i.e., the long-term containment of a gaseous, liquid or supercritical carbon 

dioxide stream in subsurface geologic formations OTHER THAN OIL OR GAS 

RESERVOIRS, COAL SEAMS, BASALTS, OR SALT CAVERNS. 

Basis for CCS Group Comments: See 144.6 and the note immediately above about the 

requirement for conforming language. 

Deleted "gaseous, liquid or supercritical" because it was added to the 

definition of CO2 stream. 

Response: As described above, EPA expects that, after promulgation of the final rule, a limited number 

of experimental injection projects to test GS technology will continue, e.g., to inform the technology 

associated with GS into basalts, coal seams, and salt domes. Based on its evaluation of all public 

comments and input on the proposed rule and NODA and Request for Comment, EPA has made many 

revisions to the GS Rule. See the final rule and preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 2060 1.5.3 Comments on grandfathering of existing 

wells (seeking comment) 

Comment: Rule Provision: 146.81(c) 

Proposed CCS Group Recommendations: (c) This subpart applies to owners and 

operators of permit or rule-authorized Class I industrial, Class II WHICH HAVE 

CEASED AND WILL NO LONGER BE USED FOR ENHANCED RECOVERY OF OIL OR 

NATURAL GAS, 

or Class V experimental carbon dioxide injection projects who seek to apply for 

a Class VI geologic sequestration permit for their well or wells. If the 

Director determines that USDWs will not be endangered, such wells are exempt, at 

the Director’s discretion, from the casing and cementing requirements at §§ 

146.86(b) and 146.87(a)(1) through (3). CLASS VI REQUIREMENTS OF SUBPART H OF 

THIS PART. WELLS CONSTRUCTED IN ACCORDANCE WITH THE CLASS II 

REQUIREMENTS OF § 

146.22 AND USED IN CO2 SERVICE AND THAT HAVE DEMONSTRATED MIT ARE EXEMPT 

FROM THE 

REQUIREMENTS AT §§146.86 AND 146.87. 

Basis for CCS Group Comments: For first part, see 144.6 and the note above about 

the requirement for conforming language. 

Added language for transition of Class II wells to Class VI operations. These 

wells should be allowed based on their history of sound performance under the 

Class II program as demonstrated by MIT results. The language also allows the 

Director to exercise discretion to exempt other Class VI requirements. 

Response: EPA disagrees that other requirements (e.g., monitoring, operational, and AoR requirements) 

should also be grandfathered. Following re-permitting of the project as GS, many of the unique factors 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24399

314
of GS sites (e.g., increased reservoir pressures associated with large volumes of stored CO2 and the 

corrosivity of CO2 in the presence of water) will result in an increased risk profile, warranting the 

specific requirements in the final GS rule. Following re-permitting as Class VI wells, these projects must 

be subject to the operational, MIT, monitoring, reporting, plugging, and post-injection site care and site 

closure requirements in the final GS rule. See the discussion of EPA's final regulatory approach in the 

preamble to the GS rule for additional detail on these requirements. 

Comment: Rule Provision: 146.82 [Introductory text] 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: Rule Provision: 146.82(a) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: Rule Provision: 146.82(b) 

Proposed CCS Group Recommendations: (b) A SURFACE map showing the PROPOSED 

LOCATIONS FOR the injection well(s) for which a permit is sought and the 

applicable area of review. Within the area of review, the map must show the 

number, or name and location of all KNOWN injection wells, producing wells, 

abandoned wells, plugged wells or dry holes, deep stratigraphic boreholes, State 

or EPA approved subsurface cleanup sites, surface bodies of water, springs, 

mines (surface and subsurface), quarries, water wells and other pertinent 

surface features including structures intended for human occupancy and roads. 

The map should also show faults, if known or suspected. Only information of 

public record is required to be included on this map; 

Basis for CCS Group Comments: Faults are not shown on maps unless there is a 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24411

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24412

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24413

315
surface expression of the fault. Also, faults are detailed in (d) below and this 

language appears redundant. 

The word "known" needs to be added to remove any implication that an applicant 

has to conduct studies to determine the location of wells that are not currently 

documented in some fashion. 

Response: EPA disagrees that information submitted with Class VI permit applications should be 

limited to known (i.e., previously available) data. Site-specific conditions may affect the suitability of a 

proposed site. Therefore the owner or operator must provide to the Director the necessary preliminary 

information to support a permit decision. 

EPA did not delete “faults” from §146.82(b) because faults may have surface expressions, which should 

be presented on submitted maps in order to complement the required cross-section data. EPA is 

developing guidance on site characterization for GS projects to assist owners or operators and Directors 

in evaluating permit requirements and applications under §146.82. The guidance provides 

recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site 

as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the 

injection and confining zone. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. Please see the final rule and the 

discussion of geologic site characterization in the preamble for additional information. 

EPA believes that a determination about whether or what information may be necessary (for a specific 

GS project) is outside of the public record will be site-specific and based on knowledge of the site, data 

availability, and data quality. For instance, in meeting the requirement to tabulate information on wells 

in the AoR, the Director has the discretion to require the owner or operator to supplement a data records 

search if there is reason to believe that the incompleteness of available information could compromise 

USDW protection from endangerment. EPA acknowledges that some smaller fractures may not be 

detectable during the site characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner 

or operator to submit data on known or suspected faults and fractures (i.e., not all fractures). 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(c) 

Proposed CCS Group Recommendations: (c) A MAP DELINEATING the area of review 

based on UPON modeling, using ALL AVAILABLE data INCLUDING DATA obtained 

during logging and testing of the well and the formation as required by 

paragraphs (l), (r), and (s) of this section ANY WELLS IN THE AREA OF REVIEW 

Basis for CCS Group Comments: This appears to be related to a condition where a 

well is already drilled. This does not align with requesting information to 

receive a permit. 

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be 

available at the time the owner or operator develops their initial permit application. In response to 

comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24414

316
subpart so that the final regulation specifies separate requirements for information to be submitted with 

the permit application and before well construction is approved (at §146.82(a)) and information to be 

submitted before operation of the well is authorized (at §146.82(c)). 

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of 

information to be submitted. In addition, section §146.82 in the final rule is similar to the permit 

application requirements for other injection well classes, which could help avoid confusion about how to 

meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to 

be submitted before operation of the well is authorized are very similar to those for Class I wells, with 

modifications and additions that address the unique challenges and types of data collected for GS wells.

The requirement to provide the final area of review based on modeling and data obtained during logging 

and testing is in the final GS rule at §146.82(c)(1). Please see the final rule and the discussion of 

geologic site characterization in the preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: Rule Provision: 146.82(d) 

Proposed CCS Group Recommendations: (d) KNOWN information on the geologic 

structure and hydrogeologic RESERVOIR properties of the proposed storage 

site and overlying formations, including: 

(1) ISOPACH maps and OF THE PROPOSED INJECTION AND CONFINING ZONE(S), A 

STRUCTURAL CONTOUR MAP HUNG ON THE TOP OF THE PROPOSED INJECTION ZONE, 

AND AT 

LEAST TWO GEOLOGIC cross sections of the area of review SHOWING THE GEOLOGIC 

FORMATIONS FROM THE SURFACE TO TOTAL DEPTH. 

(2) Location, orientation, and properties of known or suspected SUBSURFACE 

faults and fractures that may transect the confining zone(s) in the area of 

review and a determination that they would not interfere with containment; 

Basis for CCS Group Comments: If the information is not known, it cannot be 

reported. 

"Reservoir" and changes to (1) and (2) are technical corrections. 

Fractures generally can't be identified until a well is drilled and evaluated. 

Even then, only fractures in the immediate vicinity of the well bore can be 

identified. 

Response: EPA acknowledges that some smaller fractures may not be detectable during the site 

characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit 

data on known or suspected faults and fractures (i.e., not all fractures). Other requirements for GS 

injection wells and sites can mitigate the potential impacts of unidentified fractures. These include 

limitations on injection pressures to avoid propagation of existing fractures in the confining zone 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24415

317
(§146.88(a)), collection and assessments of CO2 monitoring data at the site, and AoR reevaluations 

(§146.84(e)) to assess possible CO2 movement through high-permeability regions (i.e., faults and/or 

fractures) not detected in the initial site characterization. 

As described above, EPA disagrees that information submitted with Class VI permit applications should 

be limited to known (i.e., previously available) data. Site-specific conditions may affect the suitability of 

a proposed site. Therefore the owner or operator must provide to the Director the necessary preliminary 

information to support a permit decision. Please see the final rule and the discussion of geologic site 

characterization in the preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: Rule Provision: 146.82(d)(3) 

Proposed CCS Group Recommendations: (3) Information on seismic history THAT HAVE 

AFFECTED THE PROPOSED AREA OF REVIEW, INCLUDING KNOWLEDGE OF PREVIOUS 

SEISMIC 

EVENTS, including the presence and depth of seismic sources and a determination 

that the seismicity would not interfere with containment; 

Basis for CCS Group Comments: Information on seismic history should have some 

degree of relevance to the project. 

Response: EPA believes that consideration of local and regional seismicity is important and this type of 

review is relevant to every project. The site characterization provisions in the GS rule, including a 

review of the local and regional geology, and detailed review of any known or potential seismically 

active terrain in the vicinity of a proposed GS site, are necessary to minimize the potential for induced 

seismic events or the reactivation of faults, which are a known potential risk associated with 

underground injection and are addressed in all aspects of the UIC regulations. 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: Rule Provision: 146.82(d)(4) 

Proposed CCS Group Recommendations: (4) Data SUFFICIENT TO DEMONSTRATE THE 

EFFECTIVENESS OF THE INJECTION AND CONFINING ZONE(S), INCLUDING DATA ON 

THE 

DEPTH, AREAL EXTENT, THICKNESS, MINERALOGY, POROSITY, VERTICAL 

PERMEABILITY 

RESERVOIR PRESSURE AND OF THE INJECTION AND CONFINING ZONE(S) WITHIN THE 

AREA OF 

REVIEW; INCLUDING GEOLOGIC CHANGES BASED ON FIELD DATA WHICH MAY 

INCLUDE 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24416

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24417

318
GEOLOGIC CORES, OUTCROP DATA, SEISMIC SURVEYS, WELL LOGS, CAPILLARY 

PRESSURE 

TESTS AND NAMES and lithologic descriptions; 

Basis for CCS Group Comments: Capillary pressure is too hard to measure outside 

the lab; how comparable are lab results to what goes into the ground. Sidewall 

core may not be sufficient to do this, and it is difficult to core the whole of 

the confining and injection zones. Rewording keeps the usefulness of capillary 

pressure in the provision without making it a mandatory use. 

Response: EPA acknowledges that laboratory methods are standard for determining capillary pressures 

regardless of formation permeability and that in situ measurements would require drilling of a well. 

However, EPA also anticipates that test wells will be drilled to support geologic site characterization of 

the proposed GS sites and can be used to collect subsurface samples (for laboratory determination of 

capillary pressure) and take other necessary measurements. 

EPA recognizes that this information may not be available until after a well has been drilled. EPA 

revised §146.82 so that the final regulation specifies separate requirements for information to be 

submitted with the permit application and before well construction is approved (at §146.82(a)) and 

information to be submitted before operation of the well is authorized (at §146.82(c)). Final information 

on injection zone pressures would be required following drilling of the well, at §146.82(c)(4). 

EPA believes that information on capillary entry pressure is necessary and appropriate. Capillary entry 

pressure measurements on core samples can quantify the amount of buoyant force the confining zone 

can maintain before failure (World Resources Institute, 2008). 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: Rule Provision: 146.82(d)(5) 

Proposed CCS Group Recommendations: (5) KNOWN geomechanical information on 

fractures, stress, ductility, rock strength, and in situ fluid pressures within 

the confining zone(s) WITHIN THE AREA OF REVIEW; and 

Basis for CCS Group Comments: Clarification. 

Rule Provision: 146.82(d)(6) 

Proposed CCS Group Recommendations: Delete item 6 because this issue is covered 

under other sections such as (b). 

Response: EPA acknowledges the comment but did not make the suggested edits. The Agency believes 

that the site characterization requirements at §146.82, including geomechanical information and 

geologic and topographic maps and cross sections, are essential to proper siting of a GS well and are the 

foundation for a detailed understanding of the local and regional geology, and that the owner or operator 

should collect this information, regardless of whether it is known in advance of the siting process. 

Collecting and evaluating this data supports important evaluations regarding the suitability of the site to 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24418

319
receive and contain injected CO2. 

EPA recognizes that this information may not be available until after a well has been drilled. EPA 

revised §146.82 so that the final regulation specifies separate requirements for information to be 

submitted with the permit application and before well construction is approved (at §146.82(a)) and 

information to be submitted before operation of the well is authorized (at §146.82(c)). Final information 

on injection zone pressures would be required following drilling of the well, at §146.82(c)(4). 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(e) 

Proposed CCS Group Recommendations: (e) A tabulation RECORD of all wells 

ARTIFICIAL PENETRATIONS within the area of review which penetrate THAT REACH 

the injection or confining zone(s). Such data AS AVAILABLE IN THE PUBLIC RECORD 

must include a description of each well’s PENETRATION’S type, construction, 

date drilled, location, depth, record of plugging and/ or completion, and any 

additional information the Director may require; 

Basis for CCS Group Comments: "Artificial penetrations" is a more inclusive 

term. 

Rule Provision: 146.82(f) 

Proposed CCS Group Recommendations: (f) Maps and stratigraphic cross sections 

indicating the general vertical and lateral limits of all USDWs, water wells and 

springs within the area of review, their positions relative to the injection 

zone(s) and the direction of water movement, where known; POTENTIOMETRIC 

(WATER LEVEL) SURFACE MAP(S) OF EXISTING AQUIFERS BEING UTILIZED AS PRIVATE 

OR 

PUBLIC WATER SUPPLIES AND THE DIRECTION OF GROUNDWATER FLOW IN THESE 

AQUIFERS 

WITHIN THE AREA OF REVIEW. AT LEAST TWO GEOLOGIC CROSS SECTIONS SHOWING 

THE 

THICKNESS AND GENERAL VERTICAL AND LATERAL LIMITS OF ALL USDWS WITHIN 

THE AREA 

OF REVIEW. 

Basis for CCS Group Comments: This revision more accurately identifies the 

information that is needed and should be considered for permitting. 

Rule Provision: 146.82(g) 

Proposed CCS Group Recommendations: (g) Baseline geochemical data on 

subsurface formations, including all USDWs in the area of review COMPILATION 

OF AVAILABLE GEOCHEMICAL DATA ON THE PROPOSED INJECTION ZONE AND 

NEAREST POROUS 

AND PERMEABLE FORMATION ABOVE THE CONFINING ZONE. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24419

320
Basis for CCS Group Comments: Limits the data to be submitted to available 

information and to the injection zone and the zone immediately above the 

confining zone which are the zones most likely to be monitored for potential CO2 

leakage. 

Response: EPA believes that a determination of what information may be necessary for a specific Class 

VI well and what information is available in the public record will be site-specific and based on data 

availability and data quality. For instance, in meeting the requirement to tabulate information on wells in 

the AoR, the Director has the discretion to require the owner or operator to supplement a data records 

search if there is reason to believe that the incompleteness of available information could compromise 

USDW protection from endangerment. Please see the final rule and the discussion of permitting and 

geologic site characterization in the preamble for additional information. 

EPA believes that a thorough understanding of the hydrogeologic conditions of all USDWs in the AoR 

is necessary, and disagrees with the suggested edits because the GS rule, as written, affords flexibility to 

owners or operators and Directors to tailor the site characterization process to the unique features of the 

site. EPA encourages owners or operators and Directors to collaborate and consult during site 

characterization to discuss information needs and ensure that all appropriate data to assess the suitability 

of the site are collected. The Director also has the authority to request additional hydrogeologic data or 

other data on USDWs. 

The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on 

subsurface geologic formations, including all USDWs in the AoR, is appropriate and protective of 

USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate 

and transport model development (e.g., by providing appropriate input parameters), and provide 

information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. 

The baseline geochemical information will allow the owner or operator and permitting authority to 

evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid 

movement. 

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all 

USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining 

system and to serve as a baseline for future monitoring. The Director has the discretion to require 

geochemical analysis of additional subsurface zones if, in the Director's opinion, they are necessary for 

the protection of USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(h) 

Proposed CCS Group Recommendations: (h) Proposed operating data: 

(1) Average and maximum daily INJECTION rate and volume of the carbon dioxide 

stream; 

(2) Average and maximum SURFACE injection pressure; 

Clarifications 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24420

321
Basis for CCS Group Comments: Technical clarifications. 

Rule Provision: 146.82(i) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Rule Provision: 146.82(j) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Rule Provision: 146.82(k) 

Proposed CCS Group Recommendations: (k) Proposed stimulation program and a 

determination that stimulation will not compromise containment; 

Basis for CCS Group Comments: "Interfere" is too ambiguous and should be 

replaced by "compromise" which limits concerns to situations where containment 

may be lost. 

Rule Provision: 146.82(n) 

Proposed CCS Group Recommendations: (n) A WELLBORE schematic or other 

appropriate drawings of the surface and of the subsurface construction details 

of the well AND SURFACE WELLHEAD CONSTRUCTION. 

Basis for CCS Group Comments: (n) Technical clarification. 

Rule Provision: 146.82(q) 

Proposed CCS Group Recommendations: (q) The ANY status of corrective action 

on wells in the area of review; 

Basis for CCS Group Comments: Clarifies that wells not needing corrective action 

will not have a corrective action status. 

Response: EPA acknowledges the commenter’s support for portions of the subject requirements. EPA 

disagrees that the suggested technical clarifications are necessary. EPA adds that it is developing 

guidance for owners or operators on the geologic site characterization and AoR and corrective action 

processes. These guidances will provide recommendations and clarify the intent of all required elements 

of a permit application. The guidances can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24421

322
Comment: Rule Provision: 146.83(a) & (a)(1) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. 

Other EPA Comment Codes and Descriptions: 3110 2.1.1 Proposed siting requirements (i.e., 

injection/confining zones, trapping mechanism) 

Comment: Rule Provision: 146.83(a)(2) 

Proposed CCS Group Recommendations: (2) A confining zone(s) that is LATERALLY 

CONTINUOUS AND free of KNOWN TRANSECTING, transmissible faults or fractures and 

of sufficient areal extent and integrity to contain the injected carbon dioxide 

stream and displaced formation fluids and allow injection at proposed maximum 

pressures and volumes without initiating or propagating fractures in the 

confining zone(s); and OVER AN AREA SUFFICIENT TO PREVENT THE MOVEMENT OF 

INJECTED OR DISPLACED FLUIDS INTO A USDW; 

Basis for CCS Group Comments: The proposed clarification keeps the emphasis on 

the non-endangerment of USDWs and limits the requirements to that which is known 

or can be readily determined. 

Response: The Agency believes that the requirement at §146.83(a)(2) that the confining zone be free of 

transmissive faults or fractures is appropriate for Class VI wells and is necessary to ensure containment 

of the injectate and that requiring the confining zone to be free of transmissive faults maximizes 

protection of USDWs from endangerment. EPA believes that the text regarding propagation of faults 

and fractures is important to avoid the potential for fluid movement and to ensure that injection is at 

appropriate pressures. Class I hazardous waste injection well operators must also meet a similar 

requirement that the site is free of transmissive faults or fractures; they have successfully made such 

demonstrations in the past. While core samples obtained through drilling and hydraulic testing are direct 

methods to obtain such information, geophysical techniques such as seismic or electromagnetic surveys 

can also be used in many geologic settings to demonstrate the absence of or identify and characterize the 

presence of faults or fractures. EPA adds that the Director will evaluate all geologic data on the site to 

ensure protection of USDWs from endangerment before approving a site for a GS project. 

Other EPA Comment Codes and Descriptions: 3120 2.1.2 Need to identify additional confining and 

containment zones (seeking comment) 

Comment: Rule Provision: 146.83(b) 

Proposed CCS Group Recommendations: (b) At the Director’s discretion, owners 

or operators of Class VI wells must identify and characterize additional zones 

that will impede vertical fluid movement, are free of faults and fractures that 

may interfere with containment, allow for pressure dissipation, and provide 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24422

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24423

323
additional opportunities for monitoring, mitigation and remediation.

Basis for CCS Group Comments: This paragraph creates a presumption that 

additional confining zones WILL be required. It is also redundant given the 

previous sections. Providing for a confining zone that meets the requirements 

should be sufficient. Any further identification of confining zones would 

potentially eliminate zones useful for future geologic sequestration. 

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, 

secondary confining zones are required when the Director determines that these zones are needed to 

maximize the protection of USDWs from endangerment. EPA retains the requirement to identify 

additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA 

believes that, in some situations, the presence of additional confining and containment zones above the 

primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further 

impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for 

monitoring, mitigation, and remediation. The Agency's decision is supported by commenters 

representing states, water associations, and an electric utility who assert that these requirements promote 

a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and 

are intended to improve understanding of the project as a whole and promote better modeling of the site. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rule Provision: 146.84(a) 

Proposed CCS Group Recommendations: (a) The area of review is the region 

surrounding the geologic sequestration project that may be impacted by the 

injection activity. The area of review is based on computational modeling that 

accounts for the physical and chemical properties of all phases of the injected 

carbon dioxide stream. THE SUBSURFACE THREE-DIMENSIONAL EXTENT OF THE CARBON 

DIOXIDE PLUME, ASSOCIATED PRESSURE FRONT, AS WELL AS THE OVERLYING 

FORMATIONS 

AND SURFACE AREA ABOVE THAT DELINEATED REGION. 

Basis for CCS Group Comments: Edits make this provision consistent with the 

definition of "Area of Review", which was revised. 

Response: EPA disagrees that the AoR definition needs to specifically include the overlying formations 

and surface area above the delineated region. The intent of the AoR, a long-standing concept within the 

UIC Program, is to delineate the surface area and all subsurface formations below it that may potentially 

be impacted by injection activity. Acceptable delineation models will provide predictions of CO2 fate 

and transport, as well as changes in formation pressure, in three dimensions, as a function of time that 

can be used to delineate the subsurface storage site and the AoR. Although EPA disagrees with the 

commenter's suggested change, the Agency has carefully considered all comments on the AoR definition 

at 146.84(a) and modified it to read as follows: The region surrounding the geologic sequestration 

project where USDWs may be endangered by the injection activity. The area of review is delineated 

using computational modeling that accounts for the physical and chemical properties of all phases of the 

injected CO2 stream and is based on available site characterization, monitoring, and operational data. 

EPA believes that this definition is sufficiently broad and describes both the intent of the computational 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24424

324
modeling and the relationship of the AoR to areas that are subject to the risks associated with injection. 

Other EPA Comment Codes and Descriptions: 3700 2.2.5 Comments on the requirement for an AoR 

and corrective action plan 

Comment: Rule Provision: 146.84(b) 

Proposed CCS Group Recommendations: (b) The owner or operator of a Class VI well 

must prepare, maintain, and comply with a plan to delineate the area of review 

for a proposed geologic sequestration project, periodically reevaluate the 

delineation, and perform corrective action that meets the requirements of this 

section and is IN A MANNER AND AT A FREQUENCY acceptable to the Director. As a 

part of the permit application, for approval by the Director the owner or 

operator must submit an area of review and corrective action plan that includes 

the following information: 

Basis for CCS Group Comments: Clarification. 

Response: EPA disagrees with the suggested change, and is retaining the approach of setting a 

minimum fixed frequency for reevaluating the AoR but has, based on commenters' input, changed the 

frequency from ten years to at least every five years, as specified in §146.84(e). EPA agrees with 

commenters that site-specific information is an important factor in determining an appropriate AoR 

reevaluation frequency, and adds that the owner or operator's AoR and corrective action plan must 

describe the minimum fixed frequency for reevaluating the AoR and the site-specific conditions on 

which this frequency is based. EPA adds that the Director will evaluate the proposed plan in connection 

with a review of a vast amount of geologic and proposed operating data in determining whether to 

approve the plan. EPA is developing guidance describing recommended approaches to preparing all of 

the required GS project plans, which will address considerations for determining an appropriate AoR 

reevaluation schedule. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3500 2.2.3 Area of Review Reevaluation (seeking 

comment); 3700 2.2.5 Comments on the requirement for an AoR and corrective action plan 

Comment: Rule Provision: 146.84(b)(2)(i) & (ii) 

Proposed CCS Group Recommendations: (i) The minimum fixed frequency, not to 

exceed 10 years, the owner or operator proposes to reevaluate the area of 

review; (ii) The monitoring and operational conditions that would warrant a 

reevaluation of the area of review prior to the next scheduled reevaluation as 

determined by the minimum fixed frequency established in paragraph (b)(2)(i) of 

this section. 

Basis for CCS Group Comments: These provisions in (i) and (ii) are rendered 

unnecessary by the revisions to section 146.84(b). 

Response: EPA believes that periodic AoR reevaluation at a set frequency of at least every five years is 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24425

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24426

325
necessary to ensure protection of USDWs from endangerment and address the uncertainties inherent in 

predictive modeling. Periodic AoR reevaluations at §146.84(e) ensure that a deliberate effort is made to 

verify, based on monitoring and operational data, that the CO2 plume is moving within the subsurface as 

predicted. EPA believes that less frequent reevaluations may not be sufficient to appropriately model 

plume and pressure front movement, establish conditions for corrective action, and ensure protection of 

USDWs from endangerment. 

EPA clarifies that if site monitoring data agrees with the existing AoR delineation, a model recalibration 

may not be necessary, and the AoR reevaluation may consist of a demonstration that the current AoR 

delineation is adequate based on site monitoring data. 

Other EPA Comment Codes and Descriptions: 3500 2.2.3 Area of Review Reevaluation (seeking 

comment); 3700 2.2.5 Comments on the requirement for an AoR and corrective action plan 

Comment: Rule Provision: 146.84(b)(2)(iii) 

Proposed CCS Group Recommendations: iii (I) How monitoring and operational 

data (e.g., injection rate and pressure) will be used to inform an area of 

review reevaluation; and 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment and the final rule retains this provision. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: Rule Provision: 146.84(b)(2)(iv) 

Proposed CCS Group Recommendations: iv (II) How corrective action will be 

conducted to meet the requirements of paragraph (d) of this section, including 

what corrective action will be performed prior to injection and what, if any, 

portions of the area of review will have corrective action addressed on a phased 

basis and how the phasing will be determined; how corrective action will be 

adjusted if there are changes in the area of review; and how site access will be 

guaranteed ARRANGED for future corrective action. 

Basis for CCS Group Comments: Future access cannot be guaranteed for an area in 

advance that may not even be within the boundaries of the AOR/ project. 

Response: EPA is retaining this requirement as proposed. The purpose of the corrective action 

requirement at §146.84(d) is to ensure that all wells in the AoR that have the potential to cause the 

movement of CO2 or other fluids into or between USDWs receive appropriate corrective action. In 

general, to meet this requirement, the owner or operator will most likely need to obtain the right of 

access to wells that may require corrective action, and demonstrate they have done this in their proposed 

AoR and corrective action plan. In the AoR and corrective action plan, the owner or operator must 

describe how site access will be guaranteed for future corrective action as specified in §146.84(b)(2)(iv). 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24427

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24428

326
Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rule Provision: 146.84(c)(1) 

Proposed CCS Group Recommendations: (1) Predict, using computational modeling, 

the projected lateral and vertical migration of the carbon dioxide plume and 

formation fluids in the subsurface from the commencement of injection activities 

until INJECTION INDUCED plume movement ceases, pressure differentials sufficient 

to cause the movement of injected fluids or formation fluids into a USDW are no 

longer present, or after FOR a fixed time period as determined by the 

Director. The model MODELING must: 

Basis for CCS Group Comments: Clarification 

Response: Based on an evaluation of all comments received, EPA has clarified this language in the final 

rule at 146.84(c)(1). It now reads, “Predict, using existing site characterization, monitoring and 

operational data, and computational modeling, the projected lateral and vertical migration of the carbon 

dioxide plume and formation fluids in the subsurface from the commencement of injection activities 

until the plume movement ceases, until pressure differentials sufficient to cause the movement of 

injected fluids or formation fluids into a USDW are no longer present, or until the end of a fixed time 

period as determined by the Director.” 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rule Provision: 146.84(c)(1)(i) & (ii) 

Proposed CCS Group Recommendations: (i) Be based on detailed geologic data 

collected AVAILABLE to characterize the injection zone, confining zone and 

any additional zones; and anticipated operating data, including injection 

pressures, rates and total volumes over the proposed life of the geological 

sequestration project THE DURATION OF INJECTION; 

(ii) Take into account any RELEVANT geologic heterogeneities, AND data 

quality, and their possible impact on model predictions; and 

Basis for CCS Group Comments: Allows the use of all available data, not just 

data collected specifically for this permit. 

Response: EPA agrees that detailed geologic data is invaluable to modeling an accurate AoR. EPA 

clarifies that owners or operators may use existing data as well as data collected during site 

characterization to predict the AoR. The final rule retains the language in §146.84(c)(1)(i) as proposed, 

and modifies §146.84(c)(1)(ii) slightly to require owners or operators to take into account “other 

discontinuities” in addition to geologic heterogeneities when predicting the AoR. 

EPA disagrees that only the injection and confining zones should be included in AoR modeling of GS 

sites. EPA believes that the modeling should also take into account the possibility of displaced fluids or 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24429

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24430

327
brines caused by a lateral and/or vertical pressure plume, and therefore it may be necessary to include 

additional zones along with the confining/injection zones to ensure the integrity of the confining zone 

and ultimately protect a USDW from endangerment. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rule Provision: 146.84(c)(1)(iii) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final GS rule retains the provision in 

§146.84(c)(1)(iii) as proposed. 

Other EPA Comment Codes and Descriptions: 3420 2.2.2.1 Scope of the inventory process (e.g., 

reliance on publicly available information, depth of wells) 

Comment: Rule Provision: 146.84(c)(2) 

Proposed CCS Group Recommendations: (2) Using methods approved by the 

Director, Identify all KNOWN ARTIFICIAL penetrations INTO THE CONFINING ZONE 

AVAILABLE IN THE PUBLIC RECORD, including active and abandoned wells and 

underground mines, in the area of review that may penetrate REACH the 

confining zone. Provide a description of each well’s type, construction, date 

drilled, location, depth, record of plugging and/or completion, and any 

additional information the Director may require; and 

Basis for CCS Group Comments: Changed for consistency with earlier language. 

Response: EPA is retaining the requirement as proposed. EPA agrees with commenters that, for most 

GS sites, relying on database and other public records searches (i.e., of "known" artificial penetrations) 

will be sufficient to meet the requirements at §146.84(c)(2). However, the Agency recognizes that there 

may be situations where additional surveys or research to locate wells may be appropriate. For example, 

there may be cases where the Director may determine that ground or airborne surveys for wells are 

appropriate, e.g., if there is reason to believe, based on knowledge of the site or of available data, that 

the incompleteness of information on known wells could compromise USDW protection. In order to 

preserve the Director's discretion to require an operator to supplement a records search, EPA did not 

make the suggested change. 

EPA adds that all corrective action must be performed pursuant to the approved AoR and corrective 

action plan, which affords the Director the discretion to require any additional information needed 

(including information that is not publically available) to ensure that all necessary corrective action is 

performed. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24431

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24432

328
Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: Rule Provision: 146.84(c)(3) 

Proposed CCS Group Recommendations: (3) Determine which abandoned wells 

IDENTIFIED PURSUANT TO 146.84 (C) (2) in the area of review have been 

plugged (as required by §146.92) in a manner that prevents the movement of 

carbon dioxide or associated FORMATION fluids that may endanger USDWs. 

Basis for CCS Group Comments: Remove "in the area of review" as redundant. 

Response: EPA clarifies that the term "associated fluids," as proposed in §146.84(c)(3), refers to 

formation fluids, other injectates, etc., that may be present in the subsurface and affect movement of the 

CO2 plume and/or pressure front. EPA believes this terminology would incorporate any fluids in the 

subsurface that could potentially move through artificial penetrations and affect USDWs. EPA has 

revised the language at §146.84(c)(3) to read, "... carbon dioxide or other fluids that may endanger 

USDWs..." EPA disagrees that deleting the term area of review is necessary and has retained the term in 

the final rule language. 

Other EPA Comment Codes and Descriptions: 3460 2.2.2.3 Acceptable corrective action techniques 

for GS sites (e.g., cements) 

Comment: Rule Provision: 146.84(d) 

Proposed CCS Group Recommendations: Owners or operators of Class VI wells must 

perform corrective action USING MATERIALS SUITABLE FOR USE WITH THE CARBON 

DIOXIDE STREAM AND FORMATION FLUIDS, on all wells in the area of review 

IDENTIFIED IN 146.84(C)(2) that are determined to need corrective action". 

using methods necessary to prevent the movement of fluid into or between USDWs 

including use of corrosion resistant materials, where appropriate. 

Basis for CCS Group Comments: Experience with CO2 based EOR strongly supports 

the use of many conventional materials that might not meet the technical 

definition of "corrosion resistant". 

Response: EPA revised the text at §146.84(d) to require the use of materials that are "compatible with 

the carbon dioxide stream." EPA believes this language change addresses commenters' concerns and is 

also consistent with other language regarding materials requirements in the GS rule. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: Rule Provision: 146.84(e) 

Proposed CCS Group Recommendations: (e) If monitoring data indicate an 

endangerment to USDWs, the owner or operator must notify the Director and cease 

operations as required by § 146.94. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24433

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24434

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24435

329
Basis for CCS Group Comments: This is not needed since §146.94 already specifies 

the notification and cessation of injection. We suggest deletion of this 

language as unnecessarily duplicative. 

Response: Based on consideration of all public comments and other information, EPA deleted this 

provision from §146.84. The final rule now contains a provision in §146.91(c) that requires the owner or 

operator to report within 24 hours any evidence that the carbon dioxide stream or associated pressure 

front may cause an endangerment to a USDW. EPA believes this change consolidates reporting 

requirements in one place and provides additional clarity. 

Other EPA Comment Codes and Descriptions: 3500 2.2.3 Area of Review Reevaluation (seeking 

comment) 

Comment: Rule Provision: 146.84(f) 

Proposed CCS Group Recommendations: (f) At the minimum fixed frequency, not to 

exceed 10 years, as specified in the approved area of review and corrective 

action plan, or When monitoring and operational conditions warrant, owners or 

operators must: 

Basis for CCS Group Comments: Rather than a fixed time period, we recommend 

following a performance based approach that would be based on significant 

changes in injection parameters or anomalous monitoring results. 

Response: EPA agrees that site-specific factors should be considered in the reevaluation schedule, and 

notes that the AoR and corrective action plan must specify the site-specific monitoring and operational 

conditions that warrant reevaluation, as specified in §146.84(b)(2)(ii). In addition, the Director has 

discretion to require more frequent AoR reevaluation if he or she has reason to believe, based on sitespecific information, that a five-year reevaluation schedule is not sufficiently protective of USDWs. 

However, EPA believes that setting a minimum reevaluation frequency is appropriate. In the final rule, 

the Agency changed the minimum frequency for the AoR reevaluation at §146.84(e) from ten years to at 

least every five years in the final GS rule. EPA believes that this revised frequency addresses 

commenters' concerns about the inherent uncertainties in modeling CO2 movement, the emerging nature 

of GS technology, risk-based targeting of monitoring activities, and the unique nature of CO2 GS. 

Other EPA Comment Codes and Descriptions: 3700 2.2.5 Comments on the requirement for an AoR 

and corrective action plan 

Comment: Rule Provision: 146.84(f)(4) 

Proposed CCS Group Recommendations: (4) Submit an amended area of review and 

corrective action plan or demonstrate to the Director through monitoring data 

and modeling results that no amendment CHANGE to the area of review and 

corrective action plan is needed. 

Basis for CCS Group Comments: Clarification 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24436

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24437

330
Response: EPA disagrees with the suggested change and believes the proposed text is clear as written. 

For additional information on EPA's approach to AoR and corrective action, please see the final rule and 

preamble. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rule Provision: 146.84(g) 

Proposed CCS Group Recommendations: (g) The emergency and remedial response plan 

(as required by § 146.94) and a demonstration of financial responsibility (as 

described by § 146.85) must account for the entire area of review AS MODIFIED 

PURSUANT TO § 146.94(F), regardless of whether or not corrective action in the 

area of review is phased. 

Basis for CCS Group Comments: Need to add phrase to account for the periodic 

reevaluations and possible revisions that will be occurring. 

Response: EPA agrees with the commenter and has modified the final rule at §146.84(f) to require the 

emergency and remedial response plan and the demonstration of financial responsibility to take into 

account the most recently evaluated AoR. 

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

responsibility requirements (40 CFR 146.85) 

Comment: Rule Provision: 146.85(a) 

Proposed CCS Group Recommendations: (a) The owner or operator must demonstrate 

and maintain financial responsibility and resources for corrective action (that 

meets the requirements of § 146.84), injection well plugging (that meets the 

requirements of § 146.92), post-injection site care and site closure (that meets 

the requirements of § 146.93), and emergency and remedial response (that meets 

the requirements of § 146.94) in a manner prescribed by the Director until: 

(1) The Director receives WELL PLUGGING REPORT IDENTIFIED IN 146.92(D) and 

approves OR COMPLETION OF the completed post-injection site care and site 

closure plan AS APPROPRIATE; and 

Basis for CCS Group Comments: Maintenance of the well plugging financial 

obligation until site closure is not necessary. The Director should have the 

authority to release the obligation once the well is plugged. 

Response: EPA will allow owners or operators to use separate financial responsibility instruments for 

different GS activities. However, owners or operators must demonstrate adequate financial 

responsibility for all required activities, including well plugging, with their permit application, per 

§146.82(a)(14). In addition, on an annual basis, the owner or operator must adjust the cost estimate for 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24438

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24439

331
inflation, increase or decrease the value of the financial instrument to match the cost estimate, and 

provide any updated information related to their financial responsibility instrument(s), or at any other 

time deemed appropriate by the Director. These annual reviews provide a mechanism for revising cost 

estimates up or down to account for changes in the project, including the execution of environmental 

obligations as phases of a GS project are completed. 

Regarding the suggested edit at §146.85(a)(1), EPA clarifies that the owner or operator may call upon 

their financial instrument when the phase of the project for which the instrument was required is 

complete and all financial obligations for that instrument have been met, as specified in §146.85(b)(2). 

For example, when the injection well is plugged to the Director's satisfaction, the owner or operator's 

financial instrument will be released if it was not used. See the final rule and preamble for further 

discussion of EPA's final approach to financial responsibility. 

EPA is developing guidance on financial responsibility for GS wells. The guidance will include a 

discussion on how best to estimate costs to assist Class VI well owners or operators, third party insurers 

or providers of financial instruments, and permitting authorities in developing estimates of the costs 

associated with various GS activities. The guidance is available on EPA's website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

responsibility requirements (40 CFR 146.85) 

Comment: Rule Provision: 146.85(b) 

Proposed CCS Group Recommendations: (b) The owner or operator must provide to 

the Director, at a frequency determined by the Director, BUT NO MORE FREQUENTLY 

THAN ANNUALLY, written updates of adjustments to the cost estimate to account 

for any amendments CHANGE to the area of review and corrective action plan 

(§146.84), the injection well plugging plan (§146.92), and the post-injection 

site care and site closure plan (§146.93). 

Basis for CCS Group Comments: Requiring updates more frequently than annually is 

not justified and less frequent updates should be appropriate in many cases. 

Response: Cost estimates will need to be reevaluated after amendments to the area of review and 

corrective action plan, prior to well plugging or site closure, after amendments to the emergency and 

remedial response plan, or at any other time deemed appropriate by the Director. The rule will also 

require annual adjustments to the cost estimates for inflation, as specified in §146.85(c)(2). These annual 

reviews provide a mechanism for revising cost estimates up or down to account for changes in the 

project, including the execution of environmental obligations as phases of a GS project are completed. 

EPA did not make the proposed edits at §146.85(b), but did extensively revise and clarify the financial 

responsibility requirements. See the final GS rule and preamble for additional information on EPA's 

final approach. 

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24440

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24441

332
responsibility requirements (40 CFR 146.85) 

Comment: Rule Provision: 146.85(c) 

Proposed CCS Group Recommendations: (c) The owner or operator must notify the 

Director of adverse financial conditions such as bankruptcy, that may affect 

the ability to carry out injection well plugging and post-injection site care 

and site closure. 

Basis for CCS Group Comments: Clarification. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS rule. Please see the final rule and 

the discussion of financial responsibility in the preamble for additional information. 

Other EPA Comment Codes and Descriptions: 5432 2.9.1.1 Need to adjust financial responsibility 

mechanisms (seeking comment) 

Comment: Rule Provision: 146.85(d) 

Proposed CCS Group Recommendations: (d) The operator must provide an adjustment 

of the cost estimate to the Director if the Director has reason to believe that 

original THE MOST RECENT demonstration is no longer adequate to cover the 

cost of injection well plugging (as required by §146.92) and post-injection site 

care and site closure (as required by §146.93) 

Basis for CCS Group Comments: Clarification. 

Response: EPA agrees that it is important to periodically update cost estimates that support financial 

responsibility determinations. EPA clarifies that the GS rule, at §146.85(e), requires the owner or 

operator to provide annual updates to the cost estimate to account for any amendments to the AoR and 

corrective action plan, the injection well plugging plan, and the PISC and site closure plan. 

Other EPA Comment Codes and Descriptions: 3800 2.3 Proposed Injection Well Construction 

Requirements (40 CFR 146.86) 

Comment: Rule Provision: 146.86(a)(1) 

Proposed CCS Group Recommendations: (1) Prevent the movement of fluid into or 

between USDWs or into any unauthorized zones; CONTAINING ANY CONTAMINANT INTO 

USDWS, IF THE PRESENCE OF THAT CONTAMINANT MAY CAUSE A VIOLATION OF ANY 

PRIMARY 

DRINKING WATER REGULATION UNDER 40 CFR PART 142 OR MAY OTHERWISE 

ADVERSELY 

AFFECT THE HEALTH OF PERSONS; 

Basis for CCS Group Comments: The proposed changes follow the non-endangerment 

standard that is the basis of the UIC program. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24442

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24443

333
Response: EPA disagrees that §146.86 as written does not meet the non-endangerment standard as 

required under the SDWA. EPA believes that protection of USDWs from endangerment and prevention 

of fluid movement between formations is paramount and believes that the language as proposed meets 

the non-endangerment standard. Appropriately designed and constructed wells are necessary to prevent 

endangerment to USDWs and maintain integrity of the well throughout the lifetime of a GS project. This 

is the foundation of the requirements for construction and pre-operational testing of Class VI wells at 

§§146.86 and 146.87. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment, EPA has made many revisions to the GS rule. Please see the final rule and preamble for 

additional information. 

Other EPA Comment Codes and Descriptions: 3860 2.3.3 Well component degradation 

Comment: Rule Provision: 146.86(b)(1) 

Proposed CCS Group Recommendations: (1) Casing and cement or other materials 

used in the construction of each Class VI well must have sufficient structural 

strength and be designed for the operating life of the geologic sequestration 

project WELL. All well materials must be compatible SUITABLE FOR USE with 

the fluids with which the materials may be expected to come into contact and 

meet or exceed TEST standards OR PRACTICES developed for such materials by the 

American Petroleum Institute, ASTM International, or comparable standards 

acceptable to the Director. The casing and cementing program must be designed to 

prevent the movement of fluids into or between USDWs. In order to allow the 

Director to determine and specify casing and cementing requirements, the owner 

or operator must provide the following information: 

Basis for CCS Group Comments: The life of a geologic sequestration project could 

be different than the life of the well. Class VI well design should be based on 

the life of the well. 

Response: EPA disagrees that the casing, cement, or other materials should only be designed for the 

period of the injection process, rather than the life of the sequestration project. GS projects are 

anticipated to have long life spans in comparison to other types of deep injection wells. Not only must 

Class VI wells be able to function safely and properly over the lifespan of the GS project, but they must 

be constructed such that USDWs remain protected after well plugging. The requirements at §146.86 will 

ensure that the well can maintain integrity throughout the proposed life span of the project, including 

after the injection well is plugged and through the post-injection site care period and beyond. While the 

risk profile of a GS site will decrease following cessation of injection, EPA believes that Class VI wells 

must be designed to protect USDWs from endangerment for the life of the project. Furthermore, 

rigorous casing and cementing help ensure that the Class VI well will not serve as a conduit for 

movement of fluids associated with future injection operations. 

Other EPA Comment Codes and Descriptions: 3864 2.3.3.2 Use of corrosion-resistant cements 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24444

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24445

334
(seeking comment) 

Comment: Rule Provision: 146.86(b)(1)(v) 

Proposed CCS Group Recommendations: (v) Corrosiveness COMPOSITION of the 

carbon dioxide stream and formation fluids; 

Basis for CCS Group Comments: There is no method for measurement of 

"corrosiveness" of a CO2 stream. The relevant information is the composition of 

the CO2 stream. 

Response: EPA clarifies that, although corrosiveness does not have a unit of measure, corrosiveness can 

be technically measured and described. Procedures that can identify corrosion (or the absence of 

corrosion) in a Class VI well provide valuable operational information that the Director needs to 

determine appropriate standards for the tubing and packer. 

Other EPA Comment Codes and Descriptions: 3860 2.3.3 Well component degradation 

Comment: Rule Provision: 146.86(b)(1)(vi) 

Proposed CCS Group Recommendations: (vi) Down-hole temperatures AND PRESSURES; 

Basis for CCS Group Comments: Technical clarification 

Response: EPA clarifies that information on down-hole pressures is required at §146.86(b)(1)(ii). 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: Rule Provision: 146.86(b)(1)(viii) 

Proposed CCS Group Recommendations: (viii) Type or grade of cement AND 

ADDITIVES; and 

Basis for CCS Group Comments: Technical revision 

Response: EPA agrees with the suggestion that §146.86(b)(1)(viii) be revised to also address cement 

additives. In the final GS rule, the subparagraph reads as follows: "Type or grade of cement and cement 

additives." 

Other EPA Comment Codes and Descriptions: 3822 2.3.1.1 Depth of surface casing (seeking 

comment) 

Comment: Rule Provision: 146.86(b)(2) 

Proposed CCS Group Recommendations: (2) Surface casing must extend through the 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24446

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24447

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24448

335
base of the lowermost USDW ABOVE THE INJECTION ZONE and be cemented to the 

surface EXCEPT THAT THE DIRECTOR MAY APPROVE A COMBINATION OF CEMENTED 

SURFACE 

CASING AND CEMENTED LONG STRING CASING TO ACHIEVE CONTINUOUS CEMENT 

FROM THE 

SURFACE THROUGH THE BASE OF THE LOWERMOST USDW ABOVE THE INJECTION 

ZONE. 

Basis for CCS Group Comments: Surface casing need not be cemented through the 

base of the lowermost USDW if a combination of cement on the surface casing and 

long-string casing achieves continuous cement through the base of the lowermost 

USDW above the injection zone. In some parts of the US, USDWs are very deep and 

this standard may preclude geologic sequestration at otherwise appropriate sites 

in these areas. 

Response: EPA believes that the regulations allow appropriate flexibility regarding the surface casing. 

The GS final rule at §146.86(b)(2) requires that surface casing extend through the base of the lowermost 

USDW and be cemented to the surface through the use of a single or multiple strings of casing and 

cement. It does not, however, specify how cementing would be accomplished, and gives flexibility to 

the owner or operator to propose alternate methods to provide a sufficient amount of cement to meet the 

standard that USDWs are protected. EPA notes that there are many potential ways to meet the 

requirement, such as the use of staged cementing. 

The Director will evaluate the appropriateness of the owner or operator's proposed well construction 

procedures based on site-specific information about the injection project, including injection pressures, 

injection and confining zone lithology, and information about the carbon dioxide stream as provided in 

§146.86(b)(1). See the discussion of Class VI well construction requirements in the preamble to the final 

GS rule for additional information. Additionally, EPA is developing guidance on the construction of 

Class VI wells. This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

As described above, EPA recognizes concerns regarding construction of Class VI wells where the 

lowermost USDW is very deep. To further address comments on deep injection wells, the final GS rule 

at §146.95 includes requirements for owners or operators that seek a waiver of the injection depth 

requirements. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: Rule Provision: 146.86(b)(3) 

Proposed CCS Group Recommendations: (3) At least one long string casing, using 

a sufficient number of centralizers SET IN A MANNER SO AS TO CREATE A CEMENT 

BOND THROUGH THE INJECTION AND CONFINING ZONE(S). THE LONG STRING CASING 

must 

extend to the injection zone and must be cemented ISOLATED by circulating 

cement to the surface in one or more stages. PLACING CEMENT AND/OR OTHER 

ISOLATION TECHNOLOGIES AS NECESSARY TO PROVIDE ADEQUATE ISOLATION OF THE 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24449

336
INJECTION ZONE AND PROVIDE FOR PROTECTION OF USDWS. 

Basis for CCS Group Comments: Cementing of the long string casing to surface is 

not necessary to protect USDWs, and may have negative consequences. Cement to 

surface would eliminate the ability to monitor pressures in this annulus and 

would limit flexibility of remedial options. As revised, the proposal would 

allow for application and development of alternative technologies. See API RP90 

for description of risk-based approach for managing situations involving annular 

casing pressure. Industry experience with CO2 EOR under the Class II program 

demonstrates the effectiveness of existing cementing procedures. 

Response: EPA disagrees with the suggested edits. EPA believes that the requirements for long-string 

casing are appropriate and offer appropriate flexibility: §146.86(b)(3) requires that the long-string casing 

extend to the injection zone and be cemented by circulating cement to the surface in one or more stages. 

It does not, however, specify how cementing would be accomplished, and gives flexibility to the owner 

or operator to propose alternate methods to provide a sufficient amount of cement to meet the standard 

that USDWs are protected from endangerment, subject to the approval of the Director. 

EPA stresses that protection of USDWs is the primary mission and mandate of the UIC program and the 

purpose of all requirements for injection wells. Any injection activity must be demonstrated to not 

endanger USDWs, regardless of their depth, and if such non-endangerment cannot be shown, then the 

activity will not be allowed under UIC requirements or the SDWA. 

EPA does not believe that the cementing requirements at §146.86 would prevent monitoring, operation, 

and remediation of Class VI wells. Cementing of deep wells has been performed successfully in the past 

by owners or operators of Class I hazardous and Class I municipal waste disposal wells. Some of these 

wells, which must meet the same cementing and casing requirements as Class VI wells, are up to 12,000 

feet deep and have been successfully cemented in a manner that maintains integrity and allows for all 

required well testing, operation, and remediation (EPA, 2001). See the discussion of Class VI well 

construction requirements in the preamble to the final GS rule for additional information. Additionally, 

EPA is developing guidance on the construction of Class VI wells. This guidance will be available on 

EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: Rule Provision: 146.86(b)(4) 

Proposed CCS Group Recommendations: (4) Circulation of cement may be 

accomplished by staging. The Director may approve an alternative method of 

cementing in cases where the cement cannot be recirculated to the surface, 

provided the owner or operator can demonstrate by using logs that the cement 

does not allow fluid movement behind the well bore. 

Basis for CCS Group Comments: Same as above 

Response: EPA disagrees that the requirement should be deleted. Section 146.86(b)(4) of the final rule 

allows alternate methods of staging the cement, at the Director's discretion, provided the owner or 

operator can demonstrate using logs that the cement does not allow fluid movement behind the wellbore.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24450

337
See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3864 2.3.3.2 Use of corrosion-resistant cements 

(seeking comment) 

Comment: Rule Provision: 146.86(b)(5) 

Proposed CCS Group Recommendations: (5) Cement and cement additives must be 

compatible SUITABLE FOR USE with the carbon dioxide stream and formation 

fluids and of sufficient quality and quantity to maintain integrity over the 

design OPERATING life of the geologic sequestration project WELL. The 

integrity and location of the cement shall be verified using technology capable 

of evaluating cement quality radially and identifying the location of channels 

to ensure that USDWs are not endangered. 

Basis for CCS Group Comments: Experience with CO2 EOR under the Class II program 

demonstrates the effectiveness of existing cementing materials and procedures. 

Standard API cements have been used in numerous CO2 EOR operations with no 

adverse consequences. Refer to the citations within EPA’s proposed rule 73 FR 

43532-43533: Carey et al., (2007), Crow et al., (2008), and Meyer, J.P (2007). 

Response: EPA recognizes that the oil and gas industry has decades of experience injecting CO2 for the 

purpose of enhanced recovery, and that this practice has led to the development of many corrosion 

mitigation measures that would be appropriate for the design of Class VI wells. 

EPA believes that the GS rule provides flexibility: it does not specify materials to be used; rather, it 

provides owners or operators with the flexibility to choose, as long as the materials used in Class VI 

wells are compatible with fluids with which they may come into contact and meet or exceed standards 

developed for such materials by API or ASTM International, or comparable standards approved by the 

Director, as provided at §146.86(b)(1). However, EPA clarifies that each individual component of the 

well system must be described by the owner or operator and will be evaluated by the Director and must 

meet the requirements of the GS rule. 

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3826 2.3.1.3 Packer requirements (seeking comment) 

Comment: Rule Provision: 146.86(c)(2)(ii) 

Proposed CCS Group Recommendations: (ii) Characteristics COMPOSITION of the 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24451

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24452

338
carbon dioxide stream. (chemical content, corrosiveness, temperature, and 

density); 

Basis for CCS Group Comments: There is no method for measurement of 

"corrosiveness" of a CO2 stream. The relevant information is the composition, 

not characteristics, of the CO2 stream. The composition of the CO2 stream is 

more relevant to the design of a tubing and packer system. 

Rule Provision: 146.86(c)(2)(iii) - (v) 

Proposed CCS Group Recommendations: (iii) MAXIMUM PROPOSED Injection temperature 

and pressure; 

(iv) MAXIMUM PROPOSED Annular pressure; 

(v) MAXIMUM PROPOSED Injection rate (intermittent or continuous) and volume of 

the carbon dioxide stream; 

Basis for CCS Group Comments: Technical corrections. 

Response: As written, the text at §146.86(c)(3)(ii) accounts for all characteristics of the CO2 that could 

affect the performance of the tubing and packer, including the chemical content, corrosiveness, 

temperature, and density. The suggested revision to refer to CO2 "composition" would be less precise. 

EPA clarifies that, although corrosiveness does not have a unit of measure, corrosiveness can be 

technically measured and described. Procedures that can identify corrosion (or the absence of corrosion) 

in a Class VI well provide valuable operational information that the Director needs to determine 

appropriate standards for the tubing and packer. 

EPA has revised §146.86(c)(3)(iii) and (iv) to reference the maximum proposed injection pressure and 

maximum proposed annular pressure, respectively. EPA has revised §146.86(c)(3)(v) to read "proposed 

injection rate (intermittent or continuous), and volume and/or mass of the carbon dioxide stream." EPA 

believes that reference to the continuous injection rate would be duplicative of the maximum rate. EPA 

believes that considering the maximum injection and annular pressure would be more protective. 

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a) 

Proposed CCS Group Recommendations: (a) During the drilling and construction of 

a Class VI injection well, the owner or operator must run appropriate logs, 

surveys and tests to determine or verify the depth, thickness, porosity, 

permeability, and lithology of, and the salinity of any formation fluids in, all 

relevant geologic formations to assure EVALUATE conformance with the 

injection well construction requirements under §146.86, and to establish 

accurate baseline data against which future measurements may be compared. The 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24453

339
owner or operator must submit to the Director a descriptive report prepared by a 

knowledgeable log analyst that includes an interpretation of the results of such 

logs and tests. At a minimum, such logs and tests must include: THE DIRECTOR 

MAY REQUIRE SUCH LOGS AND TESTS AS MAY BE NEEDED AFTER TAKING INTO 

ACCOUNT THE 

AVAILABILITY OF SIMILAR DATA IN THE AREA OF THE DRILLING SITE, THE 

CONSTRUCTION 

PLAN, AND THE NEED FOR ADDITIONAL INFORMATION THAT MAY ARISE FROM TIME 

TO TIME 

AS THE CONSTRUCTION OF THE WELL PROGRESSES AND THESE MAY INCLUDE THE 

FOLLOWING: 

Basis for CCS Group Comments: Obtaining the geologic information will not assure 

conformance with well construction requirements, just measure or evaluate it. 

In well defined areas, these evaluations are frequently unnecessary. The 

Director should have discretion to select the appropriate requirements necessary 

to obtain sufficient baseline data and information. For example, in an area 

where a number of wells are being drilled, the logging of surface hole yields 

little useful additional information. 

In particular, this change would allow the Director to reduce the requirements 

when multiple wells are installed for a project. 

Response: EPA disagrees that the requirements for logs, surveys, and tests are unnecessary. All logs, 

surveys, and tests listed at §146.87(a) are necessary to verify information about the injection and 

confining zones and ensure that the well is being drilled and cased as approved, and has mechanical 

integrity. This information is needed to demonstrate that the well can be operated and tested in a manner 

that protects USDWs from endangerment. While the tests do provide information on some of the same 

items, each test provides unique pieces of information that build on each other and allow for 

interpretations not possible with a single test. 

EPA notes that the Director has the discretion at §146.87(a)(5) to approve alternative methods that 

provide equivalent or better information, and the Director may accept information on cores of the 

injection and confining zones from nearby wells if the owner or operator can demonstrate that such 

cores are representative of conditions at the well in question and core retrieval is not possible, as 

specified at §146.87(b). EPA believes that logs and tests must be performed on each well drilled 

regardless of existing information about the area to account for the complexity of CO2 injection well 

construction and the buoyancy of CO2. Existing lithologic and geologic information may lack the details 

needed for site-specific well design and the geology needed to support protection of USDWs from 

endangerment. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a)(1) 

Proposed CCS Group Recommendations: Support the proposed language. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24454

340
Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment and agrees that logging and testing requirements are 

appropriate and necessary. The final rule retains the requirements for deviation checks at §146.87(a)(1). 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a)(2)(i) 

Proposed CCS Group Recommendations: (i) Resistivity, spontaneous potential, and 

caliper logs before the casing is installed; and 

Basis for CCS Group Comments: After a few wells are drilled in an area, these 

evaluations are frequently unnecessary and yield little new information. This is 

an example of where modification of requirements based on Director discretion 

may be appropriate. 

Response: As described above, EPA disagrees that the requirements for logs, surveys, and tests are 

excessive or duplicative. All logs, surveys, and tests listed at §146.87(a) are necessary to verify 

information about the injection and confining zones and ensure that the well is being drilled and cased as 

approved, and has mechanical integrity. EPA notes that the Director has the discretion at §146.87(a)(5) 

to approve alternative methods that provide equivalent or better information. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a)(2)(ii) 

Proposed CCS Group Recommendations: (ii) A Cement bond and variable 

density log, and a temperature log evaluation log(s) after the casing is set 

and cemented. 

Basis for CCS Group Comments: Unusual to run these logs in a surface hole due to 

uniformity of shallow geology. This is an example of where Director discretion 

may be appropriate. 

The proposed change provides more flexibility to select the appropriate log to 

demonstrate adequate cement bond. 

Response: EPA clarifies at §146.87(a)(2)(ii) that owners or operators must perform a cement bond (i.e., 

cement evaluation) log after the casing is set and cemented. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24455

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24456

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24457

341
CFR 146.87) 

Comment: Rule Provision: 146.87(a)(3) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. The final rule retains the requirements for the logs 

required at §146.87(a)(3). 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a)(3)(i) 

Proposed CCS Group Recommendations: (i) Resistivity, spontaneous potential, 

porosity, caliper, gamma ray, fracture finder logs and any other logs the 

Director requires BASED ON SITE SPECIFIC CONDITIONS AND RISK-BASED FACTORS for 

the given geology before the casing is installed; and 

Basis for CCS Group Comments: It is acceptable to specify basic logging 

requirements, however, special logs should not be specified. Any other 

information from the area should be used instead. 

Response: EPA believes that a minimum suite of logs and tests is necessary at all Class VI wells. All 

logs, surveys, and tests listed at §146.87(a) are necessary to verify information about the injection and 

confining zones and ensure that the well is being drilled and cased as approved and has mechanical 

integrity. 

EPA notes that owners or operators will describe in their permit applications how they will construct and 

test the well, and will also submit site-specific information about the subsurface geology. The Director 

will evaluate the proposed logging activities along with site-specific geologic information to identify 

geologic data of interest. 

EPA adds that, should alternative methods be shown to provide equivalent or better information or if 

site-specific conditions and risk factors dictate that other logs are necessary, the Director has the 

discretion at §146.87(a)(5) to require further logs and tests if necessary and to approve alternative 

methods that provide equivalent or better information. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a)(3)(ii) 

Proposed CCS Group Recommendations: (ii) A Cement bond and variable 

density log, and a temperature log EVALUATION LOG(S) after the casing is set 

and cemented. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24458

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24459

342
Basis for CCS Group Comments: The proposed change provides more flexibility to 

select the appropriate log to demonstrate adequate cement bond. 

Response: EPA clarifies at 146.87(a)(3)(ii) that owners or operators must perform a cement bond (i.e., 

cement evaluation) log after the casing is set and cemented. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a)(4) 

Proposed CCS Group Recommendations: (4) A series of tests TEST(S) designed 

to demonstrate the internal and external mechanical integrity of injection 

wells, which may include: 

(i) A pressure test with liquid or gas; 

(ii) A tracer survey DIAGNOSTIC TOOLS such as oxygen-activation logging; 

(iii) A temperature or noise log; AND/OR 

(iv) A casing inspection log. if required by the Director; and 

Basis for CCS Group Comments: Technical and grammatical corrections in (4), (4) 

(ii) and (4)(iii). In (iv), "if required by the Director" is unnecessary. 

Response: EPA disagrees that allowing the use of unspecified "diagnostic tools" would provide the 

same amount of information as the requirement to perform a tracer survey. The track record for tracer 

surveys in evaluating mechanical integrity has been proven over time. The Agency clarifies that a tracer 

survey is one of the mechanical integrity tests that may be required by the Director or used by the owner 

or operator. 

EPA agrees with the commenter about the wording of the casing inspection log requirement at §146.87

(a)(4) and made the suggested change to improve clarity. In the final regulation, §146.87(a)(iv) does not 

include the phrase, “if required by the Director.” 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a)(5) 

Proposed CCS Group Recommendations: (5) Any alternative methods that provide 

equivalent or better information and that are required of and/or approved of 

by the Director. 

Basis for CCS Group Comments: We interpret that (5) applies to 146.87(a) and 

support as proposed. For deletion, same comment as above in (iv). 

Response: EPA retained the language in §146.87(a)(5) as proposed, allowing the Director discretion to 

authorize different methods in that provision, rather than moving such authority to 146.87(a), as the 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24460

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24461

343
commenter requested. EPA notes that §146.87(a)(5) affords the Director discretion to approve 

alternative methods that provide equivalent or better information, and the Director may accept 

information on cores of the injection and confining zones from nearby wells if the owner or operator can 

demonstrate that such cores are representative of conditions at the well in question and core retrieval is 

not possible, as specified at §146.87(b). 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(b) 

Proposed CCS Group Recommendations: (b) The owner or operator must submit to the 

Director A REPORT DESCRIBING whole cores or sidewall cores REPRESENTATIVE of the 

injection zone and confining system and formation fluid samples from the 

injection zone(s). The Director may accept DATA FROM cores AND FLUID SAMPLES 

from nearby wells if the owner or operator can demonstrate that core retrieval 

is not possible and that such cores DATA are representative of conditions 

at the well IN THE WELLBORE. The Director may require the owner or 

operator to core other formations in the borehole. 

Basis for CCS Group Comments: The information required should be sufficient to 

properly describe the injection and confining zones. 

Response: EPA clarifies that it is not the Agency's intent that physical cores be submitted to the 

Director. In the final GS rule, EPA has revised the first sentence of §146.87(b) to read as follows: "The 

owner or operator must take whole cores or sidewall cores of the injection zone and confining system 

and formation fluid samples from the injection zone(s), and must submit to the Director a detailed report 

prepared by a log analyst that includes: well log analyses (including well logs), core analyses, and 

formation fluid sample information...." 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(c) 

Proposed CCS Group Recommendations: (c) PRIOR TO INJECTION WELL OPERATION,the 

owner or operator must record PROVIDE REPRESENTATIVE INFORMATION ON the 

fluid FORMATION temperature, FORMATION FLUID pH and conductivity, and 

reservoir pressure and the static fluid level of the injection zone(s). 

Basis for CCS Group Comments: Technical corrections. Reservoir pressure and 

static fluid level are redundant parameters. The phrase "representative 

information" prevents the operator from having to do all tests in all wells. 

Response: EPA disagrees that "reservoir pressure" and "static fluid level" are redundant parameters. 

Although the static fluid level is equal to the bottom hole pressure, this may not always be identical to 

the reservoir pressure. Additionally, measuring the static fluid level provides additional assurance that 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24462

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24463

344
the reading is accurate (or, provides the needed information in cases where a good reading is not 

obtained). In addition, a static fluid level measurement provides information regarding the proximity to 

USDWs that need protection afforded to them. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(d) 

Proposed CCS Group Recommendations: (d) At a minimum, the owner or operator 

must determine or calculate the following information concerning the injection 

and confining zone(s): (1) Fracture pressure; (2) Other physical and chemical 

characteristics of the injection and confining zones; and (3) Physical and 

chemical characteristics of the formation fluids in the injection zone. 

Basis for CCS Group Comments: With the exception of calculating fracture 

pressure, the requirements of this section appear redundant to other 

requirements of prior sections. The fracture pressure requirement has been added 

to section 146.87(e) below. (2) and (3) are too vague. 

Response: EPA believes that the requirement to provide information on the injection and confining 

zones in §146.87(d) is warranted. As described above, the rule provides flexibility to account for the 

variety of geologic conditions that may be encountered at GS sites. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(e) 

Proposed CCS Group Recommendations: e (D) Upon completion but Prior to 

INJECTION WELL operation, the owner or operator must 

conduct the following tests to verify hydrogeologic characteristics of the 

injection zone: (1) A pump test; or (2) Injectivity tests. 

ESTIMATE FRACTURE PRESSURES OF THE INJECTION AND CONFINING ZONES AND 

INJECTIVITY 

OF THE INJECTION ZONE. ESTIMATES SHOULD BE BASED ON REPRESENTATIVE 

HYDROGEOLOGIC 

AND GEOMECHANICAL CHARACTERISTICS OF THE INJECTION ZONE. 

Basis for CCS Group Comments: Allows the use of information such as leak off 

tests conducted during the drilling operation. 

The results of a pump test (pumping fluid from the well) have no relevance for 

an injection well. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24464

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24465

345
Deletion of the injectivity test would allow the use of non-destructive methods 

to calculate fracture pressure. 

Response: EPA clarifies that the owner or operator has the option of using the pump tests or injectivity 

tests specified at §146.87(e) depending on which would provide the most valuable information based on 

site-specific conditions. Further, EPA disagrees that pump tests are irrelevant to determining injection 

zone properties. Depending on the characteristics or depth of knowledge of the confining and injection 

zone formations, pump tests may be necessary to prove that no hydraulic connection exists between the 

injection zone and a USDW. 

EPA disagrees that the wording at §146.87(d) would lead the owner or operator to employ destructive 

testing methods for determination of fracture pressure. The wording "determined or calculated" allows 

for calculations to be performed based on non-destructive methods. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(f) 

Proposed CCS Group Recommendations: (f) (e) The owner or operator must 

provide the Director with the opportunity to witness all logging and testing by 

this subpart. The owner or operator must submit a schedule of such activities to 

the Director UPON SPUDDING THE WELL and submit any changes to the schedule 48 

HOURS prior to the scheduled test. 

Basis for CCS Group Comments: The changes reflect the realities of rig 

scheduling and are fully consistent with current Class II requirements and 

practices. 

Response: EPA disagrees that the 30-day notification requirement is unreasonable. Acknowledging the 

developing nature of CO2 GS, EPA believes that involvement by the permitting authority in each project 

will provide much needed field data for assurance of USDW protection from endangerment and will 

help update and refine the permitting process. Adequate timing of notification will ensure the Director's 

ability to be involved. 

Other EPA Comment Codes and Descriptions: 4110 2.4.1.1 Injection pressure limitations 

Comment: Rule Provision: 146.88(a) 

Proposed CCS Group Recommendations: (a) Except during stimulation, the owner 

or operator must ensure that injection pressure does not exceed 90 percent of 

the fracture pressure of the injection zone so as to assure that the injection 

does not initiate new fractures or propagate existing fractures in the injection 

zone. In no case may injection pressure initiate fractures in the confining 

zone(s) or cause the movement of injection or formation fluids that endangers a 

USDW. THE OWNER OR OPERATOR MUST COMPLY WITH A MAXIMUM INJECTION 

PRESSURE 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24466

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24467

346
LIMIT APPROVED BY THE DIRECTOR AND SPECIFIED IN THE PERMIT. IN APPROVING A 

MAXIMUM INJECTION PRESSURE LIMIT, THE DIRECTOR SHALL CONSIDER THE RESULTS 

OF 

WELL TESTS AND, WHERE APPROPRIATE, GEOMECHANICAL OR OTHER STUDIES THAT 

ASSESS 

THE RISKS OF TENSILE FAILURE AND SHEAR FAILURE. THE DIRECTOR SHALL APPROVE 

LIMITS THAT, WITH A REASONABLE DEGREE OF CERTAINTY, WILL AVOID INITIATION 

OR 

PROPAGATION OF FRACTURES IN THE CONFINING ZONE OR CAUSE OTHERWISE NONTRANSMISSIVE FAULTS TRANSECTING THE CONFINING ZONE TO BECOME 

TRANSMISSIVE. IN NO 

CASE MAY INJECTION PRESSURE CAUSE MOVEMENT OF INJECTION OR FORMATION 

FLUIDS IN A 

MANNER PROHIBITED BY 40 CFR PART 144.12(A). 

Basis for CCS Group Comments: We are concerned about three aspects of proposed 

section 146.88(a), governing injection pressure limitations. First, it 

"restricts" fractures in the injection zone "except during stimulation" rather 

than focusing on maintaining the integrity of the confining zone, which is what 

really matters for protecting USDWs. Second, it fails to refer specifically to 

the full range of potential geomechanical failure modes potentially posed by 

operations at a particular site. Third, the type of geomechanical risk that is 

addressed (initiation or propagation of fractures), is dealt with in a 

potentially arbitrary fashion (the 90% of fracture pressure limit), which may 

not be appropriate in all cases. 

Our recommended language addresses these concerns by focusing on maintaining the 

integrity of the confining zone and including tensile failure and shear failure 

as transmissivity concerns. It calls for additional geomechanical studies of 

tensile failure and shear failure only "where appropriate" because there will be 

ocations where experience or existing information will provide sufficient 

evidence to avoid the need for additional studies. The need for conducting 

additional tests and for determining which tests would be acceptable is left to 

the Director’s discretion. 

This is the same recommendation as presented by the multi-stakeholder group, in 

which the Carbon Sequestration Council participated. 

Response: EPA notes that because determination of the injection pressure limit is based on the fracture 

pressure of the injection zone, the limit is site-specific and not arbitrary. EPA emphasizes that injection 

pressure limits are important to protect against fracturing of the confining zone, and that the requirement 

at §146.88(a) that the pressure in the injection zone not exceed 90 percent of the fracture pressure 

provides a margin of safety in the well operation and protects USDWs from endangerment. If the 

Director determines, based on a review of the information collected as part of site characterization, that a 

lower injection pressure limitation is appropriate in order to prevent endangerment of USDWs, the 

Director has the authority to set a lower limit in the operating permit than the limit established in the 

rule. 

EPA notes that during the site characterization process, owners or operators must submit data about the 

geology of the site, as specified at §146.82(a), including data on known or suspected faults and fractures 

and geomechanical information on fractures, stress, ductility, rock strength, and in situ fluid pressures 

347
within the confining zone. The Director will use these data to determine appropriate limits on injection. 

In response to the concern about reopening of faults at lower pressures than 90 percent of fracture 

pressure, EPA believes that the requirement for the owner or operator to submit data on known or 

suspected faults and fractures and information on the seismic history of the site will inform the 

determination of an appropriate pressure limitation in the permit. Any sites with the potential for 

reopening or reactivation of faults or unacceptable seismic risk that could otherwise interfere with 

containment will not be permitted as GS sites. 

EPA is developing guidance on site characterization for GS projects to assist owners or operators in 

meeting the requirements of §146.82 and to assist directors in evaluating permit applications. The 

guidance will describe recommended approaches for characterizing the regional geology and 

hydrogeology of a proposed site and performing the necessary geochemical, geomechanical, and 

geophysical analyses of the injection and confining zone. EPA is also developing guidance for primacy 

agencies that will include recommended approaches for evaluating owner or operator-submitted data in 

setting permit conditions. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4100 2.4.1 Injection parameters 

Comment: Rule Provision: 146.88(b) 

Proposed CCS Group Recommendations: (b) Injection OF THE CO2 STREAM between the 

outermost casing protecting USDWs and the well bore is prohibited. 

Basis for CCS Group Comments: Routine injection into zones other than the target 

interval(s) should be prohibited, however, wording of this requirement is not 

clear as to which interval is being addressed. An absolute prohibition on 

injection into this annulus may also limit diagnostic or remedial options that 

could be useful. 

Response: EPA retains the provision as proposed, and clarifies that injection between the casing and the 

well bore is prohibited. This is consistent with requirements for other injection well classes. 

Other EPA Comment Codes and Descriptions: 4100 2.4.1 Injection parameters 

Comment: Rule Provision: 146.88(c) 

Proposed CCS Group Recommendations: (c) The owner or operator must fill the 

annulus between the tubing and the long string casing with a non-corrosive fluid 

approved by the Director. The owner or operator must maintain a positive 

pressure on the annulus. 

Basis for CCS Group Comments: Industry experience with the Class II UIC program 

does not support this requirement as proposed by EPA. 

Positive annular pressure that exceeds the operating injection pressure is not 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24468

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24469

348
necessary because a leak from tubing to annulus does not have the same 

implications as in a Class I hazardous situation. 

Response: EPA believes that maintaining an annulus pressure that is higher than the injection pressure, 

as required at §146.88(c), will ensure that if there are leaks in the tubing, the annulus fluid will move 

into the tubing, rather than the injectate moving out of the tubing and potentially along the outside of the 

well. EPA believes this requirement is appropriate for Class VI wells given the potential high volumes 

and supercritical nature of the CO2 injectate, potential geomechanical stresses in the wellbore, and the 

potential for movement of the CO2 in the event of a mechanical integrity loss. 

Other EPA Comment Codes and Descriptions: 4100 2.4.1 Injection parameters 

Comment: Rule Provision: 146.88(d) 

Proposed CCS Group Recommendations: Support the proposed language.. 

Basis for CCS Group Comments: Agree with EPA’s rationale 

Response: EPA agrees that maintaining mechanical integrity is an essential component of protecting 

USDWs. The final rule retains this provision. 

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells 

(seeking comment) 

Comment: Rule Provision: 146.88(e) 

Proposed CCS Group Recommendations: (e) The owner or operator must install and 

use continuous recording devices to monitor: the injection pressure; the rate, 

volume, and temperature of the carbon dioxide stream and. THE OWNER OR 

OPERATOR MUST REGULARLY MONITOR the pressure on the annulus between the tubing 

and the long string casing and annulus fluid volume and. THE OWNER OR 

OPERATOR must install and use alarms and automatic down-hole shut-off 

systems, designed to alert the operator and shut-in the well when operating 

parameters such as injection rate, injection pressure, or other parameters 

approved by the Director diverge beyond ranges and/or gradients specified in the 

permit; 

Basis for CCS Group Comments: Over-pressure protection is best achieved by 

ensuring compatibility of the casing/tubing material design strength with the 

surface injection (compression) system. Down-hole shut-in devices are not 

appropriate for this application. These devices are installed in the tubing 

string and are typically near the surface of the well. They're intended to seal 

the tubing in the event of catastrophic failure of the wellhead. These devices 

would provide little if any protection to USDWs. Is not practicable to install 

these devices deep within the well (e.g. shortly above the packer). Additionally 

these devices create a restriction on running other tools like logging tools in 

the well and therefore could limit an operators ability to do required 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24470

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24471

349
monitoring and diagnostic work. Lastly, these devices require periodic testing 

and maintenance which could require either pulling the device by wireline or by 

pulling the entire tubing string depending on the type of device installed. 

Either of these activities would be disruptive and costly to the overall project 

operations. 

Response: EPA acknowledges that proper design of the well, including appropriate materials and 

emplacement of casing and tubing, is essential to proper operation of the well. Such design, however, 

does not eliminate the possibility of failure, e.g., due to over-pressurization as suggested by the 

commenter. EPA believes that a multiple-barrier approach, which includes appropriate well design as 

required at §146.86, suitable injection pressure limits as required at §146.88(a), and automatic shut-off 

systems, as required at §146.88(e), is necessary to ensure protection of USDWs from endangerment 

from the risks associated with CO2 GS. 

Landing nipples, which are machined portions of the tubing that allow the seating of components–such 

as safety valves—at a later time, can be used to deploy safety valves after the initial well completion. 

EPA believes, however, that if the shut-off system is not deployed until the failure occurs, CO2 will be 

free to flow out of the well until the shut-off valve is deployed. Since installing the new shut-off system 

will require getting the device to the site, setting up a rig, and deploying the device down the well, a 

significant amount of time could elapse following an adverse event before the well is sealed. EPA 

believes that the risks of uncontrolled CO2 flow are too great to be allowed for such a length of time. 

As described above, EPA will not require automatic down-hole shut-off devices for onshore Class VI 

wells since it is not necessary in all cases to ensure protection of USDWs from endangerment. Instead, 

the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells install 

automatic surface shut-off devices. The rule affords Director's discretion to mandate automatic downhole shut-off devices in onshore situations that may warrant their use. The rule requires, at §146.88(e)

(3), that owners or operators of offshore wells within State territorial waters install automatic down-hole 

shut-off systems. 

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells 

(seeking comment) 

Comment: Rule Provision: 146.88(f) 

Proposed CCS Group Recommendations: (f) If an down-hole automatic shutdown 

is triggered or a loss of mechanical integrity is discovered, the owner or 

operator must immediately investigate and identify as expeditiously as possible 

the cause of the shutoff. If, upon such investigation, the well appears to 

be lacking mechanical integrity, or if monitoring required under paragraph (e) 

of this section otherwise indicates that the well may be lacking mechanical 

integrity, the owner or operator must: 

Basis for CCS Group Comments: Revisions made here to make this subsection 

conform with changes to 146.88(e) above. 

Response: As described above, EPA will not require automatic down-hole shut-off devices for onshore 

Class VI wells since it is not necessary in all cases to ensure protection of USDWs from endangerment. 

Instead, the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24472

350
install automatic surface shut-off devices. The rule affords Director's discretion to mandate automatic 

down-hole shut-off devices in onshore situations that may warrant their use. The rule requires, at 

§146.88(e)(3), that owners or operators of offshore wells within State territorial waters install automatic 

down-hole shut-off systems. Please see the final rule and preamble for additional information on EPA's 

final approach. 

Other EPA Comment Codes and Descriptions: 4000 2.4 Proposed Injection Well Operating 

Requirements (40 CFR 146.88) 

Comment: Rule Provision: 146.88(f)(3) 

Proposed CCS Group Recommendations: (3) Notify the Director within 24 hours OF 

DISCOVERY; 

Basis for CCS Group Comments: Clarifying revision to (3) will make compliance 

feasible for operators. 

Response: The final rule text at §146.88(f) now reads, "If a shutdown (i.e., down-hole or at the surface) 

is triggered or a loss of mechanical integrity is discovered." Therefore the notice required at §146.88(f)

(3) must be provided within 24 hours of an automatic shut-off device being triggered or a loss of 

mechanical integrity being discovered. EPA believes this provision is necessary to ensure timely 

response to potential USDW endangerment. 

Other EPA Comment Codes and Descriptions: 4500 2.5 Proposed Mechanical Integrity Testing 

(MIT) Requirements (40 CFR 146.89) 

Comment: Rule Provision: 146.89(a) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment and the final rule retains the text at 146.89(a) as proposed. 

Other EPA Comment Codes and Descriptions: 4520 2.5.1 Continuous internal mechanical integrity 

monitoring (seeking comment); 4720 2.7.2 Operational recordkeeping and reporting 

Comment: Rule Provision: 146.89(b) 

Proposed CCS Group Recommendations: (b) To evaluate the absence of significant 

leaks under paragraph (a)(1) of this section, owners or operators must, 

following an initial annulus pressure test, continuously monitor AND RECORD AT 

LEAST DAILY, ANNULUS PRESSURE AND VOLUMES OF FLUID ADDED TO OR REMOVED 

FROM 

injection pressure, rate, injected volumes, and pressure on the annulus 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24473

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24474

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24475

351
between the tubing and long stem string casing and annulus fluid volume as 

specified in §146.88 (e); 

Basis for CCS Group Comments: We recommend continuous monitoring, but do not 

find continuous recording necessary as Class II requirements have proven 

sufficient. The alternative of continuous monitoring, which will alert operator 

to any problems, and daily recording to allow for daily check of wells. This is 

consistent with successful Class II operating experience. 

Response: EPA agrees with the commenter regarding the importance of demonstrating internal 

mechanical integrity (MI). Class VI injection wells will be equipped with dedicated computer-based 

continuous pressure monitoring devices, in concert with the shut-off systems required for GS wells, 

which typically take readings several times per second (i.e., more frequently than daily) and record them 

electronically in a computer system. 40 CFR §146.91(a)(2) requires that monthly averages of the 

continuous annulus monitoring be reported on a semiannual basis. 

Other EPA Comment Codes and Descriptions: 4540 2.5.2 Proposed external MIT requirements; 4543 

2.5.2.1 MIT procedures and methods for GS (seeking comment) 

Comment: Rule Provision: 146.89(c) 

Proposed CCS Group Recommendations:(c) At least once per year, the owner or 

operator must confirm the absence of significant fluid movement under paragraph 

(a)(2) of this section USING A METHOD ACCEPTABLE TO THE DIRECTOR (E.G. INCLUDING 

DIAGNOSTIC SURVEYS SUCH AS OXYGEN-ACTIVATION LOGGING OR TEMPERATURE OR 

NOISE 

LOGS). (1) A tracer survey such as oxygen-activation logging; (2) A 

temperature or noise log; or (3) A casing inspection log, if required by the 

Director. 

Basis for CCS Group Comments: Revised text supports a performance-based approach 

and allows the development and use of new technologies as they become available. 

Cement circulation to the surface is not necessary because having the open 

annulus above the top of cement allows regular monitoring of annular pressure 

which could indicate leakage. 

We recommend deletion of subsection (3) because it would require that the tubing 

be pulled at significant cost and risk of uncontrolled releases. 

Response: EPA believes that the MITs described in 146.89(c) of the rule (an approved tracer log or 

temperature or noise logs) are effective methods to demonstrate external MI, provide an important early 

warning of potential problems in the injection well system, and represent standard techniques that have 

been used successfully by the drilling industry and for the UIC Program for decades. The Agency notes 

that the regulations do provide the Director flexibility at §146.89(e) to approve the use of alternative 

MIT methods. 

EPA agrees that the casing inspection log is not an appropriate test to detect fluid movement behind the 

casing, but clarifies that it can be used to determine the presence or absence of corrosion of the longstring casing, and is required if the Director determines that it is necessary based on site-specific 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24476

352
information. EPA has revised the final GS rule to require that the frequency of the casing inspection log 

must be specified in the approved testing and monitoring plan. See §146.89(d). 

Other EPA Comment Codes and Descriptions: 4543 2.5.2.1 MIT procedures and methods for GS 

(seeking comment) 

Comment: Rule Provision: 146.89(d) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Rule Provision: 146.89(e) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Rule Provision: 146.89(f) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comments and the final rule retains the text as proposed. 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Rule Provision: 146.90 [Introductory text] 

Proposed CCS Group Recommendations: (A) BASED ON A SITE-SPECIFIC ASSESSMENT OF 

THE POTENTIAL FOR FLUID MOVEMENT FROM THE INJECTION WELL OR INJECTION 

ZONE, AND 

ON THE POTENTIAL VALUE OF MONITORING WELLS TO DETECT SUCH MOVEMENT, the 

owner or 

operator of a Class VI well must prepare, maintain, and comply with a testing 

and monitoring plan to verify that the geologic sequestration project is 

operating as permitted and is not endangering USDWs. THE TESTING AND 

MONITORING PLAN MUST BE SUBMITTED WITH THE PERMIT APPLICATION, FOR 

DIRECTOR 

APPROVAL AND INCLUDE A DESCRIPTION OF HOW THE OWNER OR OPERATOR WILL 

MEET THE 

REQUIREMENTS OF THIS SECTION; 

Basis for CCS Group Comments: Drilling monitoring wells should be carefully 

considered since each well introduces a potential pathway for fluid movement. In 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24477

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24478

353
addition the cost of adding multiple wells could create a barrier to CCS 

development, while providing limited information on actual movement of the CO2 

stream. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

EPA anticipates that the testing and monitoring plan will address site-specific geologic factors, 

modeling, and risk-assessment. EPA is developing guidance on how best to develop the various required 

project plans, including the testing and monitoring plan. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm 

EPA believes that monitoring using wells in the injection zone, e.g., for pressure monitoring as required 

at §146.90(g)(1), can be safely performed if the wells are constructed to prevent flow between the 

injection zone and USDWs or other layers above the confining zone. Such construction technologies 

exist and have been used in the oil and gas industry for years. EPA believes that properly constructed 

monitoring wells will be a safe way to obtain the data that is essential to ensure that the injected CO2 

remains confined in the injection zone and that pressure changes are not causing movement of formation 

or other fluids. To mitigate the risk of fluid movement, EPA requires owners and operators to submit a 

testing and monitoring plan that describes how the owner or operator plans to site and construct 

monitoring wells. EPA is developing guidance on well construction that will include recommendations 

for monitoring well construction. The guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: Rule Provision: 146.90(a) & (b) 

Proposed CCS Group Recommendations: (B) THE TESTING AND MONITORING PLAN MUST, AT 

A MINIMUM, INCLUDE: 

(a) (1) analysis of the carbon dioxide stream with sufficient frequency to 

yield data representative of its chemical and physical characteristics; 

(b) (2) Installation and use, except during well workovers as defined in 

section 146.88(d), of continuous monitoring devices (INCLUDING DIGITAL DEVICES 

CAPTURING PERIODIC DATA) to monitor injection pressure, rate and volume; AND 

RECORD AT LEAST DAILY the pressure on the annulus between the tubing and the 

long strong casing; 

(3) A DEMONSTRATION OF EXTERNAL MECHANICAL INTEGRITY PURSUANT TO §146.89

(C) 

UNTIL THE WELL IS PLUGGED; 

(4) MONITORING OF THE PRESSURE BUILDUP IN THE INJECTION ZONE ANNUALLY, 

INCLUDING 

AT A MINIMUM, A SHUT DOWN OF THE WELL FOR A TIME SUFFICIENT TO CONDUCT A 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24479

354
VALID 

OBSERVATION OF THE PRESSURE FALL-OFF CURVE AT LEAST ONCE EVERY FIVE 

YEARS; AND 

(5) A QUALITY ASSURANCE PLAN FOR ALL TESTING AND MONITORING 

REQUIREMENTS. 

Basis for CCS Group Comments: There is concern regarding what constitutes 

continuous monitoring. Industry agrees that regular monitoring of the parameters 

identified by EPA is appropriate. Experience with CO2 EOR strongly shows that 

daily monitoring of most of these parameters is adequate (exceptions to this 

would be on a site-specific basis). Recording should generally be done on a 

daily basis and reporting on a semi-annual basis. 

Response: EPA believes that continuous pressure monitoring of GS wells, as required at §146.88(e), is 

important and appropriate because the potentially corrosive nature of CO2 streams in the presence of 

water makes it critical to immediately identify corrosion-related well mechanical integrity loss. Class VI 

injection wells must be equipped with dedicated computer-based continuous pressure monitoring 

devices (in concert with the Director-approved shut-off systems required for GS wells), which typically 

take readings several times per second and record them electronically in a computer system.. 

EPA believes that a frequency of five years, as specified at §146.90(f), is an appropriate interval for 

pressure fall-off testing (particularly given the suite of tests operators will perform on the well and the 

site). EPA clarifies that the Director may require more frequent pressure fall-off tests at a specific 

project if necessary, based on site-specific circumstances. Pressure fall-off tests may be conducted in 

conjunction with other well performance tests (i.e., mechanical integrity testing) to ensure safe and 

effective operations. All monitoring data collected, including information from pressure fall-off tests, 

will be incorporated in AoR reevaluations at least every five years. EPA disagrees that the rule should 

provide specifics of the testing to the degree suggested, however. 

EPA clarifies that periodic MITs will not be required following plugging of the well. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment, EPA has made many revisions to the GS rule. See the final rule and preamble for further 

discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4630 2.6.3 Corrosion monitoring 

Comment: Rule Provision: 146.90(c) 

Proposed CCS Group Recommendations: (C) WHERE APPROPRIATE, THE TESTING AND 

MONITORING PLAN SHALL ALSO INCLUDE: 

(1) CONTINUOUS MONITORING FOR PRESSURE CHANGES IN AN APPROPRIATELY 

POROUS AND 

PERMEABLE FORMATION OVERLYING THE CONFINING ZONE.; 

(2) THE USE OF INDIRECT, GEOPHYSICAL TECHNIQUES TO DETERMINE THE POSITION 

OF THE 

CO2 STREAM FRONT, THE WATER QUALITY IN A DESIGNATED FORMATION, OR TO 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24480

355
PROVIDE 

OTHER SITE SPECIFIC DATA; 

(3) PERIODIC MONITORING OF WATER QUALITY IN AN APPROPRIATELY POROUS AND 

PERMEABLE FORMATION OVERLYING THE INJECTION ZONE; 

(4) PERIODIC MONITORING OF WATER QUALITY IN ONE OR MORE USDWS; 

c (5) Corrosion monitoring of the well materials for loss of mass, 

thickness, cracking, pitting and other signs of corrosion performed and recorded 

AT LEAST on a quarterly WHICH MAY BE MODIFIED TO BE LESS FREQUENT AS 

APPROVED BY THE DIRECTOR BASED ON CONSTRUCTION MATERIALS, OPERATING 

CONDITIONS, 

AND MONITORING HISTORY to ensure that the well components meet the minimum 

standards for material strength and performance set forth in §146.86(b) by: 

(1) (I) Placing ANALYZING coupons of the well construction materials 

placed in contact with the carbon dioxide stream; or 

(2) (II) Routing the carbon dioxide stream through a loop constructed with 

the material used in the well AND INSPECTING THE MATERIALS IN THE LOOP; or 

(3) (III) Using an alternative method, MATERIALS, OR TIME PERIOD approved by 

the Director; 

(6) ANY ADDITIONAL TESTING AND MONITORING NECESSARY TO SUPPORT MODELING 

THE 

EXTENT OF THE CARBON DIOXIDE PLUME AND THE POSITION OF THE PRESSURE 

FRONT; AND 

(7) ANY ADDITIONAL TESTING AND MONITORING NECESSARY TO DETERMINE 

WHETHER FLUID 

MOVEMENT IS OCCURRING INTO OR BETWEEN USDWS THAT WOULD ENDANGER A 

USDW. 

Basis for CCS Group Comments: There should be no need for corrosion monitoring 

of most injected CO2 streams because those streams will typically overwhelmingly 

CO2 and dry thus having no corrosive properties. Industry experience with 

production, transportation, and injection of dry CO2 strongly illustrates the 

non-corrosive nature of this type of CO2 stream. 

This proposal revises the provision to make it a requirement only where 

appropriate based on the materials of construction and characteristics of the 

injected CO2 stream and other factors. 

The corrosion provisions are included in subsection (c)(5). 

Response: EPA believes that quarterly corrosion monitoring of GS wells is necessary. CO2 in the 

presence of water (including water with NOx, SOx, and H2S impurities) can be corrosive to well 

materials and cements. Thus, although a CO2 stream may be dry, the potential for corrosion of well 

materials down-hole, where the injectate can potentially mix with water in the target formation, must be 

356
considered. 

Several laboratory studies and a limited number of field studies have investigated and characterized the 

effects of carbonic acid on well materials. Laboratory studies (e.g., Kutchko et al., 2007; Kutchko et al., 

2008) consistently identify alterations (typically carbonation) of cement as the result of interactions 

between cement and CO2-saturated brine. 

Currently, there are only a few analyses of cement from wells that have been in prolonged contact with 

CO2 in actual field (down-hole) conditions. Evaluation of cement from a well at the Scurry Area 

Canyon Reef Operators Committee (SACROC) site showed alteration, but did not show degradation that 

compromised the structural integrity of the cement (Carey et al., 2007). In another study, cement 

samples were collected and analyzed from a CO2 production well in a natural CO2 reservoir in 

Colorado exposed to a CO2-water down-hole environment for 30 years (Crow et al., 2008). The study 

found evidence of reaction between the CO2-rich water and the cement. 

Oil industry research also addresses the effects of corrosion of steel tubing and pipes. Lopez et al. (2003) 

noted that 60 percent of oilfield failures are related to the effects of carbonic acid from produced brines 

on carbon and low alloy steels. 

Laboratory investigation of cement alteration/degradation is an ongoing research area. Few field-based 

studies have been completed to date. The laboratory and field studies currently available suggest that 

corrosion problems can be managed; however, there is not a large enough body of research to rule out 

potential corrosion problems of steel components of injection wells. The IPCC (2005) report on carbon 

dioxide capture and storage reviewed oil and gas industry experience with gas injection wells, close 

industry analogues to CO2 injection wells. The report stated that, while the design of CO2 injection 

wells will be very similar to gas injection wells, most down-hole components of the CO2 injection wells 

will “need to be upgraded for higher pressure ratings and corrosion resistance.” Given the pressure and 

corrosion considerations, anticipated long lifespan of a GS well and the difficulties that would be 

associated with a corrosion-related well failure, EPA believes that corrosion monitoring in the downhole environment is justified. For these reasons, the final rule requires quarterly corrosion monitoring at 

§146.90(c). 

EPA maintains that plume tracking and pressure monitoring are key components of monitoring at GS 

sites. A rigorous plume tracking and pressure monitoring scheme, such as one that meets the 

requirements at §146.90(g), is imperative for ensuring that the CO2 plume is contained within the 

injection zone. Pressure monitoring in the injection zone is necessary to track the development and 

movement of the pressure front and CO2 plume. When combined with information on temperature, 

pressure data provide an indication of the phase (e.g., gas, supercritical) and distribution of the injected 

CO2. Monitoring can also identify needed remedial actions, provide inputs for AoR reevaluation 

modeling, evaluate predictions of plume movement, and target additional geochemical and surface 

monitoring needs. 

EPA also believes that the ground water geochemical monitoring outlined in §146.90(d) will maximize 

protection of USDWs from endangerment at GS sites. Direct geochemical sampling is an important part 

of a monitoring program. See the final rule and preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4660 2.6.6 Geochemical monitoring 

Comment: Rule Provision: 146.90(d) 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24481

357
Proposed CCS Group Recommendations: (d) Periodic monitoring of the ground 

water quality and geochemical changes above the confining zone(s) that may be a 

result of carbon dioxide movement through the confining zone or additional 

identified zones: 

(1) The location and number of monitoring wells must be based on specific 

information about the geologic sequestration project, including injection 

rate and volume, geology, the presence of artificial penetrations and other 

factors; 

(2) The monitoring frequency and spatial distribution of monitoring wells must 

be based on baseline geochemical data that has been collected under § 146.82(a) 

(6) and any modeling results in the area of review evaluation required by § 

146.84(b); 

Response: EPA did not make the suggested changes, but agrees that monitoring plans and methods need 

to be site-specific and based on baseline data and data collected throughout operations. EPA believes 

that the monitoring requirements for GS sites at §146.90 provide an appropriate level of flexibility in 

structuring a testing and monitoring plan that protects USDWs from endangerment. 

The final regulation provides for flexibility in: 1) methodologies used to collect these data, 2) the spatial 

resolution at which the data should be collected, and 3) how often the data should be collected. The 

number and placement of monitoring wells will be based on site-specific information such as the 

calculated AoR, injection rate and volume, site geology, baseline data, and the presence of artificial 

penetrations within the AoR. In some instances, there may be a limited number of options for complying 

with EPA's minimum requirements. For example, monitoring for geochemical changes will require use 

of monitoring wells and collection of groundwater samples for chemical analysis. Many options 

currently exist for complying with other requirements, such as tracking the position of the plume and 

pressure front within the injection zone. 

Flexibility is also provided regarding how to monitor for the specific data required by the final rule. The 

testing and monitoring plan is developed by the owner or operator in consultation with the Director and 

is designed to ensure that a detailed, Director-approved document describing how monitoring will be 

conducted during the lifetime of the project exists. EPA is developing guidance on testing and 

monitoring to assist owners or operators and Directors in evaluating requirements under §146.90, 

including proposed monitoring plans. The guidance describes available technologies and recommended 

approaches for implementing a testing and monitoring plan, including pre-operational geophysical 

logging and testing of injection wells, MITs, injection well testing during operation, groundwater quality 

monitoring, tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which 

may be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: Rule Provision: 146.90(e) & (f) 

Proposed CCS Group Recommendations: (e) A demonstration of external mechanical 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24482

358
integrity pursuant to § 146.89(c) at least once per year throughout the duration 

of the geologic sequestration project; 

(f) A pressure fall-off test at least once every five years unless more frequent 

testing is required by the Director based on site specific information; 

Basis for CCS Group Comments: Redundant to section 146.89 

These issues are addressed in recommended subsection (b)(3) and (4). 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. EPA adds that the purpose of including all 

testing and monitoring requirements in §146.90 is to clarify and to specify the content of the required 

testing and monitoring plan. 

Other EPA Comment Codes and Descriptions: 4650 2.6.5 CO2 plume and pressure front tracking 

(seeking comment) 

Comment: Rule Provision: 146.90(g) 

Proposed CCS Group Recommendations: (g) Testing and monitoring to track the 

extent of the carbon dioxide plume and the position of the pressure front by 

either monitoring for pressure changes in the first formation overlying the 

confining zone or using indirect, geophysical techniques (e.g., seismic, 

electrical, gravity, or electromagnetic surveys and/or down-hole carbon dioxide 

detection tools); 

Basis for CCS Group Comments: Monitoring outside of the injection zone provides 

little information of value for tracking and monitoring the injected plume. 

Examples of how to test and monitor could be included in the Preamble but need 

not be included in the rule itself. 

Response: EPA has revised this requirement in the final rule. The final GS regulation, at §146.90(g)(1), 

requires all GS project owners or operators to monitor for pressure changes in the injection zone. EPA 

believes that pressure monitoring in the injection zone is necessary to track the development and 

movement of the pressure front and CO2 plume. 

Pressure monitoring within the injection zone is necessary because any such monitoring above the 

confining zone would not detect movement of the pressure front unless a breach of the confining zone 

occurs. EPA believes that monitoring using wells in the injection zone (i.e., that penetrate the confining 

zone) can be safely performed if the wells are constructed to prevent flow between the injection zone 

and USDWs or other layers above the confining zone. Such construction technologies exist and have 

been used in the oil and gas industry for years. EPA believes that the benefits of monitoring in the 

injection formation outweigh the manageable risk of those monitoring wells serving as conduits for fluid 

movement. EPA adds that owners or operators may consider performing additional pressure monitoring 

in wells that are above the confining zone (e.g., in the same wells used to perform ground water quality 

monitoring required at §146.90(d)) to provide additional verification that no pressure changes are 

occurring above the confining zone due to CO2 leakage. Monitoring also identifies needed remedial 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24483

359
actions, provides inputs for AoR reevaluation modeling, and targets additional geochemical and surface 

monitoring needs. Knowledge of the location of the CO2 plume and the associated pressure front will 

assure the public that GS projects are proceeding according to plan, provide sufficient information to the 

owner or operator and Director, or allow for appropriate actions to address any indication that USDWs 

may be endangered. 

EPA acknowledges that, at certain sites, there may be a need for more or different monitoring schemes 

(which may include monitoring in the confining zone), and adds that it is important to balance the need 

for adequate monitoring that ensures USDW protection from endangerment against too many artificial 

penetrations which could serve as conduits for fluid migration. Site-specific testing and monitoring plans 

should describe the proposed monitoring regime, which must be approved by the Director. 

Flexibility is also provided regarding how to monitor for the specific data required by the final rule. The 

testing and monitoring plan is developed by the owner or operator in consultation with the Director and 

is designed to ensure that a detailed, Director-approved document describing how monitoring will be 

conducted during the lifetime of the project exists. 

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in 

evaluating requirements under §146.90, including proposed monitoring plans. The guidance describes 

available technologies and recommended approaches for implementing a testing and monitoring plan, 

including pre-operational geophysical logging and testing of injection wells, MITs, injection well testing 

during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, and soil 

gas and surface air monitoring which may be required by the UIC Director for specific GS projects. The 

guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4670 2.6.7 Surface air monitoring and/or soil gas 

monitoring (seeking comment) 

Comment: Rule Provision: 146.90(h) 

Proposed CCS Group Recommendations: (h) At the Director’s discretion, surface 

air monitoring and/or soil gas monitoring to detect movement of carbon dioxide 

that could endanger a USDW. 

(1) The testing and monitoring plan must be based on potential vulnerabilities 

within the area of review; 

(2) The monitoring frequency and spatial distribution of surface air monitoring 

and/or soil gas monitoring must reflect baseline data and the monitoring plan 

must include how the proposed monitoring will yield useful information on the 

area of review delineation and/or compliance with standards under 40 CFR 

144.12; 

Basis for CCS Group Comments: In most situations soil and air monitoring does 

not provide an effective method of protecting USDWs. 

Response: EPA acknowledges that air and soil gas monitoring to ensure USDW protection is not 

necessary at all GS sites and agrees that the decision to use surface monitoring and the selection of 

monitoring methods for the purpose of USDW protection will be site-specific. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24484

360
The Agency believes that surface air and soil gas monitoring, when coupled with subsurface monitoring, 

may be appropriate at some GS projects to ensure USDW protection. EPA also acknowledges that 

surface air and soil gas measurements are subject to variability and may not be suitable in all settings as 

a method to ensure USDW protection. However, EPA does not believe that this should entirely preclude 

their use. The decision to use surface monitoring and the selection of monitoring methods will be sitespecific (e.g., may be influenced by geology, injection depth, and operational conditions) and must be 

based on potential risks to USDWs within the AoR. 

In the final rule, at §146.90(h), the decision to require such monitoring as an additional measure to 

ensure USDW protection rests with the Director as a means of identifying leaks that may pose a risk to 

USDWs and informing emergency notification of a Class VI owner or operator and UIC Director in the 

event of a USDW endangerment, pursuant to requirements at §146.91(c). 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Rule Provision: 146.90(i) & (j) 

Proposed CCS Group Recommendations: (i) Any additional monitoring, as required 

by the Director, necessary to support, upgrade, and improve computational 

modeling of the area of review evaluation required under § 146.84(b) and to 

determine compliance with standards under 40 CFR 144.12; and 

(j) A quality assurance and surveillance plan for all testing and monitoring 

requirements. 

Basis for CCS Group Comments: These issues are addressed in subsection (c)(6) 

and (b)(5) respectively. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4760 2.7.6 Proposed reporting frequency (seeking 

comment) 

Comment: Rule Provision: 146.91(a) 

Proposed CCS Group Recommendations: (a) Semi-annual OR LESS FREQUENT AT THE 

DISCRETION OF THE DIRECTOR reports containing: 

Basis for CCS Group Comments: Over the life of the project, the Director may 

decide that less reporting is acceptable 

Response: EPA is retaining the semi-annual reporting requirement in the final rule at §146.91(a) in 

order to ensure that permitting authorities can maintain proper oversight of GS projects, particularly in 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24485

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24486

361
the early stages of rule implementation and deployment of GS technologies. The Agency also clarifies 

that permitting authorities may choose to require more frequent reporting, at the discretion of the 

Director. See the final rule and preamble for further discussion on EPA's final approach to reporting and 

recordkeeping. 

EPA is using an adaptive approach to regulating GS. The Agency plans to, every six years, collect and 

review data on GS projects, including operational data, to determine whether the appropriate amount and 

types of information and appropriate documentation are being collected, and to determine if 

modifications to the requirements are appropriate or necessary. 

Other EPA Comment Codes and Descriptions: 4720 2.7.2 Operational recordkeeping and reporting 

Comment: Rule Provision: 146.91(a)(1) 

Proposed CCS Group Recommendations: (1) Any SIGNIFICANT changes to the physical, 

chemical and other relevant characteristics of the carbon dioxide stream from 

the proposed operating data; 

Basis for CCS Group Comments: (1) Technical clarification. Significance can be 

determined by a statistical analysis of the data. Rules should recognize that 

there will be minor variations in many data sets over time. 

Response: EPA retained this provision as proposed. The final rule at §146.91(a)(3) requires reporting of 

all exceedances of operating parameters. EPA disagrees with the suggestion to report only "significant" 

exceedances. Making a determination as to whether an exceedance is "significant" is not the purpose of 

the requirement. EPA believes that the ability of an operator to consistently meet operating requirements 

and avoid exceedances provides evidence of a well-managed GS project that is in compliance with the 

Class VI permit. If multiple exceedances occur, the Director should be aware of such occurrences, and 

that information will aid in his/her determination of whether these indicate problems at the site, and 

what is the appropriate course of action (e.g., a well workover, modification of operating parameters, or 

imposition of a penalty) to remediate such problem(s). 

Other EPA Comment Codes and Descriptions: 4720 2.7.2 Operational recordkeeping and reporting 

Comment: Rule Provision: 146.91(a)(3) & (4) 

Proposed CCS Group Recommendations: (3) A description of any SIGNIFICANT event 

that exceeds operating parameters for annulus pressure or injection pressure as 

specified in the permit; 

(4) A description of any SIGNIFICANT event which triggers a shutdown device 

required pursuant to §146.88(e) and the response taken; 

Basis for CCS Group Comments: EPA should consider some significance threshold on 

reporting these events to avoid reporting events that would be of limited 

interest or consequence. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24487

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24488

362
Response: EPA retained this provision as proposed. The final rule at §146.91(a)(3) requires reporting of 

all exceedances of operating parameters. EPA disagrees with the suggestion to report only "significant" 

exceedances. Making a determination as to whether an exceedance is "significant" is not the purpose of 

the requirement. EPA believes that the ability of an operator to consistently meet operating requirements 

and avoid exceedances provides evidence of a well-managed GS project that is in compliance with the 

Class VI permit. If multiple exceedances occur, the Director should be aware of such occurrences, and 

that information will aid in his/her determination of whether these indicate problems at the site, and 

what is the appropriate course of action (e.g., a well workover, modification of operating parameters, or 

imposition of a penalty) to remediate such problem(s). 

Other EPA Comment Codes and Descriptions: 4720 2.7.2 Operational recordkeeping and reporting; 

4740 2.7.4 Electronic reporting (seeking comment) 

Comment: Rule Provision: 146.91(b) & (c) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment and the final rule retains the text as proposed. See the final 

rule and preamble for further discussion on EPA's final approach to reporting and recordkeeping. 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: Rule Provision: 146.92(a) 

Proposed CCS Group Recommendations: (a) Prior to the well plugging, the owner or 

operator must flush each Class VI injection well with a buffer fluid, determine 

bottomhole reservoir pressure, and perform a final EXTERNAL mechanical integrity 

test OF ANY RELEVANT WELLBORE MATERIALS REMAINING. 

Basis for CCS Group Comments: Many of the components that would be tested by an 

internal MIT are removed or tested during the plugging process. 

Rule Provision: 146.92(b) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Rule Provision: 146.192(b)(2) & (5) 

Proposed CCS Group Recommendations: (2) Appropriate testing methods to ensure 

FINAL EXTERNAL mechanical integrity as specified in §146.89(C); ... 

(5) The type and grade and quantity of material to be used in plugging. The 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24489

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24490

363
material must be SUITABLE FOR USE with the carbon dioxide stream; and 

Basis for CCS Group Comments: Many of the components that would be tested by an 

internal MIT are removed or tested during the plugging process. 

Response: Regarding the suggested edit at 146.92(b)(2), EPA agrees that only an external MIT is 

required, and has modified the GS rule at §146.92(a) and 146.92(b) to require owners or operators to 

perform a final external mechanical integrity test prior to the well plugging. 

Regarding the edit at 146.92(b)(5), EPA believes, considering the potentially corrosive nature of CO2 

when it is in contact with water, that the requirement that the material must be compatible with the CO2 

stream is appropriate. The final rule retains this requirement. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 

146.92) 

Comment: Rule Provision: 146.92(c) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support and the final rule retains this approach. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 

146.92) 

Comment: Rule Provision: 146.92(d) 

Proposed CCS Group Recommendations: (d) Plugging report. Within 60 days after 

plugging the owner or operator must submit a plugging report to the Director. 

If the semi-annual report is due less than 15 days after completion of 

plugging, then the report must be submitted within 60 days after plugging. The 

report must be certified as accurate by the owner or operator and by the person 

who performed the plugging operation (if other than the owner or operator.) 

Basis for CCS Group Comments: The proposed change will simplify and clarify a 

provision that is unnecessarily complicated. 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads, "Within 

60 days after plugging the owner or operator must submit a plugging report to the Director." 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24491

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24492

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24493

364
Other EPA Comment Codes and Descriptions: 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Rule Provision: 146.93(a)(1) 

Proposed CCS Group Recommendations: (1) The owner or operator must submit the 

post-injection site care and site closure plan as a part of the permit 

application to be approved by the Director. SHALL CONTINUE TO CONDUCT 

MONITORING AS SPECIFIED IN THE DIRECTOR-APPROVED POST-INJECTION SITE CARE 

AND 

SITE CLOSURE PLAN, PURSUANT TO THE PERFORMANCE BASED CRITERIA DESCRIBED 

IN 

146.93(B)(3). 

Basis for CCS Group Comments: Revisions here reflect changes to §146.93(b)(3) 

Response: EPA disagrees with the suggested changes, and disagrees that the post-injection monitoring 

period should be strictly performance-based. The Agency agrees that there will be limited circumstances 

where it can be demonstrated in less than 50 years that the plume and pressure front no longer pose a 

risk of endangerment to USDWs, and has included requirements in the final Class VI rule at §146.93(c) 

for an owner or operator to substantially demonstrate that an alternative time frame ensures the 

protection of USDWs. However, EPA anticipates that a default timeframe for post-injection site care 

will necessary for most GS sites to ensure the protection of USDWs. A 50-year post-injection site care 

timeframe represents a reasonable and protective monitoring period based on a review of research 

studies, industry reports, and existing environmental programs, and evaluation of public comments. For 

this reason, the final GS regulation includes a provision that the Director may, at his or her discretion, 

shorten the post-injection site care timeframe if the owner or operator can demonstrate that the GS 

project does not pose an endangerment to USDWs, as specified in §146.93(b)(2). Such a demonstration 

will be site-specific, and based on pressure monitoring and USDW impacts. 

The GS rule requires owners or operators to submit a post-injection site care and site closure plan as part 

of the permit application, as specified in §146.82(a), in order to outline how these activities will be 

performed and how non-endangerment of USDWs will be demonstrated throughout the post-injection 

site care period. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93); 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Rule Provision: 146.93(a)(2) 

Proposed CCS Group Recommendations: (2) The post-injection site care and site 

closure plan must include the following information: 

(i) The pressure differential between pre-injection and predicted post-injection 

pressures in the injection zone; 

(ii) The predicted position of the carbon dioxide plume and associated pressure 

front at site closure as demonstrated in the area of review evaluation required 

under § 146.84(b); 

(iii) A description of post-injection monitoring location, methods, and proposed 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24494

365
frequency; and 

(iv) A proposed schedule for submitting post-injection site care monitoring 

results to the Director. 

Basis for CCS Group Comments: Revisions here reflect changes to §146.93(b)(3) 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: Rule Provision: 146.93(a)(3) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA agrees that a post-injection site care monitoring plan is an important tool for GS and 

anticipates that, in some cases, the appropriate post-injection monitoring strategy may end up being 

different than initially projected and there may be a need to amend the post-injection site care and site 

closure plan. EPA is requiring that, upon the cessation of injection, the owner or operator submit an 

amended post-injection site care and site closure plan or demonstrate to the Director that no changes to 

the original post-injection site care and site closure plan are necessary (146.93(a)(3)). EPA is not 

requiring formal periodic review and updates to the PISC and site closure plan throughout the injection 

phase. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Comment: Rule Provision: 146.93(a)(4) 

Proposed CCS Group Recommendations: 4) AT ANY TIME DURING THE POST-INJECTION 

SITE CARE PHASE, The owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval within 30 

days of such change. 

Basis for CCS Group Comments: Technical Clarification. 

Response: EPA agrees that a post-injection site care monitoring plan is an important tool for GS and 

anticipates that, in some cases, the appropriate post-injection monitoring strategy may end up being 

different than initially projected and there may be a need to amend the post-injection site care and site 

closure plan. EPA is requiring that upon the cessation of injection, the owner or operator submit an 

amended post-injection site care and site closure plan or demonstrate to the Director that no changes to 

the original post-injection site care and site closure plan are necessary (146.93(a)(3)). EPA is not 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24495

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24496

366
requiring formal periodic review and updates to the PISC and site closure plan throughout the injection 

phase. EPA does not expect that changes to this plan would be implemented until injection operations 

cease. EPA envisions that owners or operators would take into account similar considerations that guide 

updates to other project plans, e.g., monitoring and operational data and results of AoR reevaluations. 

EPA adds that, if any monitoring or other site data indicate a need for amending the post-injection site 

care plan, the owner or operator is expected to amend the plan accordingly under §146.93(a)(3). 

EPA adds that, in the final rule, it has revised the text at §146.93(a)(4) as follows: "At any time during 

the life of the geologic sequestration project, the owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval within 30 days of such change." 

EPA is issuing guidance on development and updating of the GS project plans, including the postinjection site care and site closure plan. The guidance will be available on EPA's web site at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5220 2.8.2.1 Post-injection monitoring activities; 

5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b) 

Proposed CCS Group Recommendations: (b) The owner or operator shall monitor the 

site following the cessation of injection to show the position of the carbon 

dioxide plume and pressure front and demonstrate that USDWs are not being 

endangered. 

(1) The owner or operator shall continue to conduct monitoring as specified in 

the Director-approved post-injection site care and site closure plan, UNTIL 

CLOSURE IS AUTHORIZED PURSUANT TO 146.93(B)(3). 

Basis for CCS Group Comments: EPA should also reconsider its proposed 50-year 

default period for post-injection site care. EPA offers no rationale for this 

arbitrarily-selected period of 50 years. Establishing a fixed and unusually long 

time period may create a significant barrier for operators considering entry 

into CCS operations. Criteria for determining the period for post-injection site 

care should be performance-based and a function of the site specific 

characteristics of a project such as project size, geologic factors, and 

relative risk of the project. Such criteria are provided in our edits to 

§146.93(b)(3). 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most cases 

or arbitrary. EPA proposed a default post-injection site care timeframe of 50 years based on a review of 

research studies, industry reports, and existing environmental programs. This analysis was included in 

an EPA-prepared background document that is available in the federal docket, titled "Computational 

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and 

Potential Risk to Underground Sources of Drinking Water." EPA assessed various default timeframes 

based on additional review of research studies and evaluation of public comments. While numerous 

commenters suggested that EPA shorten the monitoring timeframe, none of the commenters provided 

sufficient data or other evidence to warrant a change in the proposed timeframe. While the 10- or 30-

year timeframe suggested by some of these commenters may be within the timeframe suggested in some 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24497

367
studies, EPA believes that the potential risks of endangering USDWs will likely not decline within these 

timeframes and available data, including data submitted by commenters, do not support a different 

default timeframe. However, EPA acknowledges there will be circumstances where it can be 

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of 

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility regarding 

the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the 

PISC timeframe during the post-injection period based on site-specific data, pursuant to requirements at 

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to 

demonstrate, during the permitting process based on substantial data, that an alternative PISC timeframe 

may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for 

post-injection site care will be necessary in most cases. The default 50 year post-injection site care 

timeframe represents a reasonable and protective monitoring period based on a review of research 

studies, industry reports, and existing environmental programs, and evaluation of public comments. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of the 

GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs from 

endangerment. 

Other EPA Comment Codes and Descriptions: 5220 2.8.2.1 Post-injection monitoring activities; 

5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(2) 

Proposed CCS Group Recommendations: (2) If the owner or operator can request and 

demonstrate to the satisfaction of the Director before 50 years, based on 

monitoring and other site-specific data, that the geologic sequestration project 

no longer poses an endangerment to USDWs, the Director may approve an amendment 

to THAT the post-injection site care and site closure plan SHOULD BE REVISED 

to reduce the frequency of monitoring, THE DIRECTOR SHALL APPROVE THE REDUCTION. 

or may authorize site closure before the end of the 50-year period. 

Basis for CCS Group Comments: See rationale stated above for eliminating 50-year 

period. 

Response: As described above, EPA disagrees that a post-injection site care timeframe of 50 years is 

excessive in most cases or arbitrary, and retains the default 50-year post-injection site care timeframe in 

the final rule. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24498

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

368
Other EPA Comment Codes and Descriptions: 5280 2.8.2.4 USDW non-endangerment 

demonstrations 

Comment: Rule Provision: 146.93(b)(3) 

Proposed CCS Group Recommendations: (3) Prior to authorization for site closure, 

the owner or operator must DEMONSTRATE TO THE DIRECTOR, BASED ON MONITORING, 

OTHER SITE-SPECIFIC DATA, AND MODELING THAT IS REASONABLY CONSISTENT WITH 

SITE 

PERFORMANCE, THAT NO ADDITIONAL MONITORING IS NEEDED TO ASSURE THAT THE 

GEOLOGIC 

SEQUESTRATION PROJECT DOES NOT AND IS NOT EXPECTED TO POSE AN 

ENDANGERMENT TO 

USDWS. THE DIRECTOR SHALL APPROVE CLOSURE IF THE OWNER OR OPERATOR 

DEMONSTRATES, 

BASED ON THE CURRENT UNDERSTANDING OF THE SITE, INCLUDING MONITORING 

DATA AND/OR 

MODELING, ALL OF THE FOLLOWING: (I) THE ESTIMATED MAGNITUDE AND EXTENT OF 

THE 

PROJECT FOOTPRINT (CO2 PLUME AND THE AREA OF ELEVATED PRESSURE) ; (II) THE 

ESTIMATED LOCATION OF THE DETECTABLE CO2 PLUME; (III) THAT THERE IS NO 

SIGNIFICANT LEAKAGE OF EITHER CO2 OR DISPLACED FORMATION FLUIDS THAT IS 

ENDANGERING USDWS; (IV) THAT THE INJECTED OR DISPLACED FLUIDS ARE NOT 

EXPECTED 

TO MIGRATE IN THE FUTURE IN A MANNER THAT ENCOUNTERS A POTENTIAL 

LEAKAGE PATHWAY 

INTO A USDW; (V) THAT THE INJECTION WELLS AT THE SITE COMPLETED INTO OR 

THROUGH 

THE INJECTION ZONE OR CONFINING ZONE ARE PLUGGED AND ABANDONED IN 

ACCORDANCE 

WITH THESE REQUIREMENTS; AND (VI) ANY REMAINING PROJECT MONITORING WELLS 

AT THE 

SITE ARE BEING MANAGED BY A PERSON AND IN A MANNER ACCEPTABLE TO THE 

DIRECTOR. 

Basis for CCS Group Comments: We believe there are three problems with the 

closure standard in proposed section 146.93(b). First, the presumption that 

monitoring should continue for 50 years is unnecessary and counterproductive. A 

straight performance standard is preferable to this or any other fixed time 

period because it provides a clearer standard and an incentive to maximize the 

understanding of site and project performance and as such is more protective of 

USDWs. Second, the proposal requires a showing that the CO2 plume has 

"stabilized", which is undefined. Cessation of plume movement is not necessarily 

essential to show that a project poses no threat of endangerment to USDWs-plumes 

that are still moving may, nonetheless, remain contained. Instead, it is more 

protective to show that the plume is not expected to encounter a leakage 

pathway. Third, the required showing that "no additional monitoring is needed" 

does not provide guidance regarding how an operator is to show that no 

additional monitoring is needed. The proposal below provides specific guidance 

on what the operator must show. 

Commenter Organization: Carbon Sequestration Council Comment ID: 24499

369
We recommend the standard in the proposed alternative language for section 

146.93(b) below because it sets forth detailed criteria, all of which must be 

satisfied, to demonstrate that the site does not pose an endangerment to USDWs. 

The specific criteria listed in our proposal will serve to provide the Director 

with the requisite information to make the appropriate determination. The 

advantage of this approach is that it establishes clear criteria that an 

operator must demonstrate before obtaining site closure based upon particular 

site characteristics and is, therefore, reasonably applicable to any storage 

site as opposed to a standard based upon a fixed-duration. Furthermore, it is 

more stringent than a purely discretionary approach because it establishes 

specific criteria that must be shown before site closure may be granted. We 

believe this language, which is an extension of work done by the World Resources 

Institute and the Ground Water Protection Council, avoids the noted shortcomings 

and provides stronger protection for USDWs. 

This is the same recommendation as presented by the multi-stakeholder group, in 

which the Carbon Sequestration Council participated. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring timeframe. 

Instead, EPA believes that such determinations are site-specific and should be described in a project 

specific post-injection site care and site closure plan. EPA also believes that periodic reviews and 

updates, where necessary, to the plan are important to ensuring that the site continues to be managed 

effectively and to determine whether shortening the monitoring timeframe is appropriate. 

The post-injection site care requirements in the final GS rule incorporate a combination of a fixed 

timeframe and a performance standard approach. The final GS rule offer owners or operators flexibility 

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or 

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to 

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or 

operator to demonstrate, during the permitting process based on substantial data, that an alternative PISC 

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at 

§146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will assist 

Directors in evaluating proposed well plugging plans and post-injection site care and site closure plans 

under §146.92 and §146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells, perform post-injection monitoring, demonstrate the 

appropriateness of an alternative post-injection site care time frame, demonstrate non-endangerment, 

and perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24500

370
Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment); 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(4) 

Proposed CCS Group Recommendations: (4) If such a demonstration cannot be made 

(i.e., if the carbon dioxide plume and pressure front have not stabilized) after 

the 50-year period, the owner or operator must submit to the Director a plan to 

continue post-injection site care. 

Basis for CCS Group Comments: No longer necessary with 50-year period deletion. 

Response: As described above, EPA believes that to ensure USDW protection from endangerment, a 

default timeframe for post-injection site care is necessary in most cases. A 50-year post-injection site 

care timeframe represents a reasonable and protective monitoring period for most GS sites based on a 

review of research studies, industry reports, and existing environmental programs, and evaluation of 

public comments. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care 

Comment: Rule Provision: 146.93(c) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment and the final rule retains the text as proposed. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: Rule Provision: 146.93(d) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Rule Provision: 146.93(e) 

Proposed CCS Group Recommendations: (e) Once the Director has

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24501

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24502

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24503

371
authorizeSd site closure, the owner or operator must submit a site closure 

report within 90 days that must thereafter be retained at a location 

designated by the Director. AFTER COMPLETION OF ALL CLOSURE OPERATIONS. The 

report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the location 

of the injection well(S) relative to permanently surveyed benchmarks. The owner 

or operator must also submit a copy of the plat to the Regional Administrator of 

the appropriate EPA Regional Office; 

Basis for CCS Group Comments: Once the site closure report is submitted to the 

Director, the operator cease to bear responsibility for any further record 

retention. At this point, EPA becomes the steward of information for the 

project. 

Rule Provision: 146.93(e)(2) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Rule Provision: 146.93(f) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Rule Provision: 146.93(g) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention such 

as site closure reports. EPA believes that the requirements that the owner or operator retain for ten years 

following site closure, records collected during the post-injection site care period at §146.93(f) and 

§146.93(h) are appropriate for the post-injection and site closure period to ensure that data are available 

to support non-endangerment demonstrations and to address any concerns that may arise following site 

closure. This data will also support EPA's review of project data as part of the adaptive rulemaking 

approach. 

The GS regulation at §146.93(g) requires the owner or operator to record a notation on the deed to the 

facility property or other similar document examined during a title search that the land has been used to 

sequester CO2 at the time of site closure. 

EPA acknowledges the commenter’s support of the other parts; the final rule retains these provisions. 

372
Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: Rule Provision: 146.94(a) 

Proposed CCS Group Recommendations: (a) As part of the permit application, the 

owner or operator must provide the Director with an emergency A RISK-BASED 

remedial response plan that describes actions to be taken to address movement of 

the injection or formation fluids that may cause an endangerment to a USDW 

during construction, operation, closure and post-closure periods. 

Basis for CCS Group Comments: Any response plan should be based on a risk 

assessment and risk management approach that accounts not only for potential 

causes of endangerment, but probabilities and potential timing of occurrence as 

determined on a site-specific basis. As EPA has recognized, "The SDWA does not 

provide authority to develop regulations for all areas related to GS." 73 Fed. 

Reg. at 43495. Accordingly, the nature and scope of any such plans will 

necessarily be limited to the extent of that authority. 

Response: EPA agrees that emergency and remedial response plans should be risk-based, however, 

EPA did not make the requested change. The Agency believes that the requirement to develop a sitespecific emergency and remedial response plan that is informed by required site characterization data 

collected under per §146.82, modeling for AoR evaluations and reevaluations, per §146.84, and 

monitoring data, per §146.90, will appropriately address commenter concerns regarding the need for a 

risk-based emergency and remedial response plan. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: Rule Provision: 146.94(b) 

Proposed CCS Group Recommendations: (b) If the owner or operator obtains 

evidence that the injected carbon dioxide stream, DISPLACED FORMATION FLUIDS OR 

and associated pressure front may cause an endangerment to ENDANGERS a 

USDW, the owner or operator must: 

(1) Immediately Cease injection IN A PRUDENT MANNER CONSIDERING 

CIRCUMSTANCES. 

(2) Take all steps reasonably necessary to identify and characterize THE 

ENDANGERMENT POSED; 

(3) Notify the Director or the designated representative within 24 hours OF 

BECOMING AWARE OF THE ENDANGERMENT; and 

Basis for CCS Group Comments: Technical clarifications. 

Under some circumstances, an immediate cessation of injection could have adverse 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24504

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24505

373
impacts on other aspects of the operation. 

Rule Provision: 146.94(c) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Rule Provision: 146.94(d) 

Proposed CCS Group Recommendations: (d) The owner or operator must notify the 

Director prior to conducting any well workover IN RESPONSE TO ANY CASE OF 

ENDANGERMENT. 

Basis for CCS Group Comments: In critical situations, time spent obtaining 

approval could adversely affect the ability to conduct operations or increase 

the level of endangerment. 

Response: After consideration of comments, EPA has finalized the rule language in §146.94(b) as 

proposed. In the introductory section of §146.94(b), EPA clarifies that the pressure front, as defined in 

§146.81, is a zone where the pressure differential is sufficient to cause the movement of injected fluids 

or formation fluids into a USDW. Therefore, displaced formation fluids are implicitly included in the 

requirements for §146.94. EPA also clarifies that owners or operators must take action when the CO2 

stream or pressure front may cause endangerment. In order to prevent the endangerment of USDWs, as 

required under §1421 of the SDWA, EPA expects the owner or operator to act preemptively and not 

wait until endangerment has occurred. This language is consistent with existing UIC requirements for 

other well classes and EPA’s authority under the SDWA. 

EPA clarifies that the Agency expects that owners or operators should take care not to damage the well 

when ceasing injection under §146.94(b)(1). At §146.94(b)(2), EPA is maintaining the requirement to 

“characterize the release.” In order to prevent the endangerment of USDWs, as required under §1421 of 

the SDWA, EPA expects the owner or operator to act preemptively and not wait until endangerment has 

occurred. This language is consistent with existing UIC requirements for other well classes and EPA’s 

authority under the SDWA. 

EPA clarifies that the 24-hour notification required under §146.94(b)(3) begins when the owner or 

operator obtains evidence of possible endangerment. EPA believes the rule language is clear on this 

requirement. 

Since proposal, EPA has modified the final regulatory language at §146.94(d) to clarify what constitutes 

a workover to address a well failure (which invokes remedial actions) and what constitutes a 

maintenance-type workover. For maintenance-type workovers (i.e., those that are scheduled in advance), 

the owner or operator must notify and gain approval from the Director prior to beginning the workover. 

In the final GS regulation, EPA has moved this requirement to the reporting requirements at §146.91(d) 

to clarify its intent. 

Regarding concerns that notification could delay responses, EPA clarifies that the GS rule (at §146.94

(b)) describes procedures owners or operators must take in emergency situations. Specifically, upon 

determining that there is a problem with the well that may endanger a USDW, the owner or operator 

must first cease injection, then take all steps reasonably necessary to identify and characterize any 

release, notify the Director, and implement the approved emergency and remedial response plan, which 

374
may include a well workover. EPA believes that ceasing injection (which the owner or operator would 

do immediately and before notifying the Director) is the immediate action necessary to prevent or 

mitigate endangerment of USDWs, as required under the SDWA. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a)(2) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment; the final rule retains the requirements for logs to be run 

prior to installation of surface casing required at §146.87(a)(2). 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: Enhanced recovery of oil or natural gas and geologic sequestration of CO2 

EPA’s Proposal would continue to regulate and permit injection of CO2 for 

EOR/EGR purposes as Class II injection "as long as any production is occurring." 

EPA has asked for comment on the merits of this approach "since owners or 

operators of some Class II EOR/EGR wells may wish to use wells for the purposes 

of production and GS prior to the field being completely depleted." 73 Fed. Reg. 

at 43502. We recommend that the rules be clarified to provide more certainty 

about the applicability of Class II requirements where GS of CO2 occurs in 

connection with EOR/EGR activities. Specifically, the UIC rules should provide a 

"bright line" definition as to the applicable class of wells where CO2 injection 

for EOR/EGR production and for GS occur in tandem. We recommend the following 

language to accomplish that objective: 

[In the paragraphs below, the text in all CAPS denotes added text.] 

§ 144.6, 144.80 and 146.5, and Classification of injection wells. 

Injection wells are classified as follows: 

* * * 

(b) Class II. Wells which inject fluids: 

(1) Which are brought to the surface in connection with conventional oil 

or natural gas production and may be commingled with waste waters from 

gas plants which are an integral part of production operations, unless 

those waters are classified as a hazardous waste at the time of 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24973

Commenter Name: Kyle Isakower Letter ID: 0191

Commenter Organization: American Petroleum Institute Comment ID: 23878

375
injection. 

(2) For enhanced recovery of oil or natural gas; 

(3) For storage of hydrocarbons which are liquid at standard temperature 

and pressure; 

(4) FOR ENHANCED RECOVERY OF OIL OR NATURAL GAS WHERE GEOLOGIC 

SEQUESTRATION IS OCCURRING DURING OR IN CONNECTION WITH ENHANCED 

RECOVERY OF OIL OR NATURAL GAS PROVIDED (I) THERE IS REASONABLE 

EXPECTATION OF MORE THAN INSIGNIFICANT FUTURE PRODUCTION VOLUMES OR 

RATES AS A RESULT OF CARBON DIOXIDE INJECTION AND (II) OPERATING 

PRESSURES ARE NO HIGHER THAN REASONABLY NECESSARY TO PRODUCE SUCH 

VOLUMES OR RATES; 

* * * 

(F) CLASS VI. WELLS INJECTING A CARBON DIOXIDE STREAM FOR GEOLOGIC 

SEQUESTRATION EXCEPT THOSE WELLS DESCRIBED IN SUBSECTION (B)(4) OF THIS 

SECTION OR OTHERWISE EXCLUDED FROM THIS CLASS.[FN1/] 

[FN1/: Please note that well classification for geologic sequestration in 

certain formations is a matter still under discussion within the multistakeholder group and may be addressed further in future recommendations from 

the group. In the mean time individual participants in these discussions will be 

expressing views on this and other issues with an openness to revising their 

views if a consensus can be reached.] 

The undersigned have agreed that proposed language describing wells in 

classification (b)(4) establishes a "bright line" definition for wells that 

inject CO2 for EOR/EGR and GS and, consistent with EPA’s intent, should remain 

in Class II and be subject to the current requirements of Class II. We have also 

agreed that the wells used for GS in oil and gas reservoirs that do not meet the 

criteria of (b)(4) should be subject to additional requirements. We have 

tentatively defined such wells as wells used "for geologic sequestration in oil 

and gas formations and where the criteria of paragraph (b)(4) are not met." But 

we have not yet attempted to define what specific requirements should apply to 

these wells. We are committed to working toward agreement on those requirements 

(probably within a Class II context) and submitting the results of that effort 

to EPA by February 28, 2009 for your consideration. 

Response: EPA did not make the suggested change. The Agency disagrees that wells injecting CO2 for 

the primary purpose of long term storage should be regulated under Class II requirements. The Agency 

believes that the nature and risks of CO2 injection for the primary purpose of long term storage poses 

different risks than injection for the primary purpose of EOR, and therefore has developed new Class VI 

regulations to address these unique risks. For example, the volume of CO2 anticipated to be injected for 

long term storage is significantly greater than for EOR operations. Reservoir pressure conditions will 

also be different, with Class VI injection operations involving large volumes of CO2 and likely having 

higher pressures within their storage formations than Class II EOR projects. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

376
for Comment EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

Other EPA Comment Codes and Descriptions: 4110 2.4.1.1 Injection pressure limitations 

Comment: Injection Pressure Limitations 

We are concerned about three aspects of proposed section 146.88(a), governing 

injection pressure limitations. First, it "restricts" fractures in the injection 

zone "except during stimulation" rather than focusing on maintaining the 

integrity of the confining zone, which is what really matters for protecting 

USDWs. Second, it fails to refer specifically to the full range of potential 

geomechanical failure modes potentially posed by operations at a particular 

site. Third, the type of geomechanical risk that is addressed (initiation or 

propagation of fractures), is dealt with in a potentially arbitrary fashion (the 

90% of fracture pressure limit), which may not be appropriate in all cases. 

Our recommended language addresses these concerns by focusing on maintaining the 

integrity of the confining zone and including tensile failure and shear failure 

as transmissivity concerns. It calls for additional geomechanical studies of 

tensile failure and shear failure only "where appropriate" because there will be 

locations where experience or existing information will provide sufficient 

evidence to avoid the need for additional studies. The need for conducting 

additional tests and for determining which tests would be acceptable is left to 

the Director’s discretion. 

The owner or operator must comply with a maximum injection pressure 

limit approved by the Director and specified in the permit. In approving 

a maximum injection pressure limit, the Director shall consider the 

results of well tests and, where appropriate, geomechanical or other 

studies that assess the risks of tensile failure and shear failure. The 

Director shall approve limits that, with a reasonable degree of 

certainty, will avoid initiation or propagation of fractures in the 

confining zone or cause otherwise non-transmissive faults transecting 

the confining zone to become transmissive. In no case may injection 

pressure cause movement of injection or formation fluids in a manner 

prohibited by 40 CFR Part 144.12(a). 

Response: EPA notes that because determination of the injection pressure limit is based on the fracture 

pressure of the injection zone, the limit is site-specific and not arbitrary and is appropriate to protect 

USDWs from endangerment. EPA emphasizes that injection pressure limits are important to protect 

against fracturing of the confining zone, and that the requirement at §146.88(a) that the pressure in the 

injection zone not exceed 90 percent of the fracture pressure provides a margin of safety in the well 

operation and protects USDWs from endangerment. If the Director determines, based on a review of the 

information collected as part of site characterization, that a lower injection pressure limitation is 

appropriate, the Director has the authority to set a lower limit in the operating permit than the limit 

established in the rule. 

EPA notes that during the site characterization process, owners or operators must submit data about the 

Commenter Name: Kyle Isakower Letter ID: 0191

Commenter Organization: American Petroleum Institute Comment ID: 23879

377
geology of the site, as specified at §146.82(a), including data on known or suspected faults and fractures 

and geomechanical information on fractures, stress, ductility, rock strength, and in situ fluid pressures 

within the confining zone. The Director will use these data to determine appropriate limits on injection. 

In response to the concern about reopening of faults at lower pressures than 90 percent of fracture 

pressure, EPA believes that the requirement for the owner or operator to submit data on known or 

suspected faults and fractures and information on the seismic history of the site will inform the 

determination of an appropriate pressure limitation in the permit. Any sites with the potential for 

reopening or reactivation of faults or unacceptable seismic risk that could otherwise interfere with 

containment will not be permitted as GS sites. 

EPA is developing guidance on site characterization for GS projects to assist owners or operators in 

meeting the requirements of §146.82 and to assist directors in evaluating permit applications. The 

guidance will describe recommended approaches for characterizing the regional geology and 

hydrogeology of a proposed site and performing the necessary geochemical, geomechanical, and 

geophysical analyses of the injection and confining zone. EPA is also developing guidance for primacy 

agencies that will include recommended approaches for evaluating owner or operator-submitted data in 

setting permit conditions. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: We recommend the standard in the proposed alternative language for section 

146.93(b) below because it sets forth detailed criteria, all of which must be 

satisfied, to demonstrate that the site does not pose an endangerment to USDWs. 

The specific criteria listed in our proposal will serve to provide the Director 

with the requisite information to make the appropriate determination. The 

advantage of this approach is that it establishes clear criteria that an 

operator must demonstrate before obtaining site closure based upon particular 

site characteristics and is, therefore, reasonably applicable to any storage 

site as opposed to a standard based upon a fixed-duration. Furthermore, it is 

more stringent than a purely discretionary approach because it establishes 

specific criteria that must be shown before site closure may be granted. We 

believe this language, which is an extension of work done by the World Resources 

Institute and the Ground Water Protection Council, avoids the noted shortcomings 

and provides stronger protection for USDWs. 

146.93 (b) The owner or operator shall monitor the site following the 

cessation of injection. 

(1) The owner or operator shall continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site 

closure plan until closure is authorized pursuant to 146.93(b)(3). 

(2) The owner or operator can request and demonstrate to the 

satisfaction of the Director that the post-injection site care and site 

closure plan should be revised to reduce the frequency of monitoring. 

Commenter Name: Kyle Isakower Letter ID: 0191

Commenter Organization: American Petroleum Institute Comment ID: 23883

378
Response: EPA disagrees with the suggested edits, but believes that the provisions of the final GS rule 

at §146.93(b) address the commenter’s suggestions. Specifically, the owner or operator must monitor the 

site until it can be demonstrated that the CO2 plume and pressure front no longer pose a risk of 

endangerment to USDWs and that monitoring must continue until the owner or operator demonstrates, 

based on monitoring and other site-specific data, that no additional monitoring is needed to ensure that 

the GS project does not pose a risk of endangerment to USDWs, as required at §146.93(b)(3). See the 

final rule and preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 5280 2.8.2.4 USDW non-endangerment 

demonstrations 

Comment: (3) Prior to authorization for site closure, the owner or operator must 

demonstrate to the Director, based on monitoring, other site-specific 

data, and modeling that is reasonably consistent with site performance, 

that no additional monitoring is needed to assure that the geologic 

sequestration project does not and is not expected to pose an 

endangerment to USDWs. The Director shall approve closure if the owner 

or operator demonstrates, based on the current understanding of the 

site, including monitoring data and/or modeling, all of the following: 

(i) the estimated magnitude and extent of the project footprint (CO2 

plume and the area of elevated pressure) ; (ii) the estimated location 

of the detectable CO2 plume; (iii) that there is no significant leakage 

of either CO2 or displaced formation fluids that is endangering USDWs; 

(iv) that the injected or displaced fluids are not expected to migrate 

in the future in a manner that encounters a potential leakage pathway 

into a USDW; (v) that the injection wells at the site completed into or 

through the injection zone or confining zone are plugged and abandoned 

in accordance with these requirements; and (vi) any remaining project 

monitoring wells at the site are being managed by a person and in a 

manner acceptable to the Director. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring timeframe. 

Instead, EPA believes that such determinations are site-specific and should be described in a project 

specific post-injection site care and site closure plan. EPA also believes that periodic reviews and 

updates, where necessary, to the plan are important to ensuring that the site continues to be managed 

effectively and to determine whether shortening the monitoring timeframe is appropriate. 

The post-injection site care requirements in the final GS rule offer owners or operators flexibility 

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or 

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to 

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or 

operator to demonstrate, during the permitting process based on substantial data, that an alternative PISC 

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at 

§146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

Commenter Name: Kyle Isakower Letter ID: 0191

Commenter Organization: American Petroleum Institute Comment ID: 23884

379
and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will assist 

Directors in evaluating proposed well plugging plans and post-injection site care and site closure plans 

under §146.92 and §146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells; perform post-injection monitoring; demonstrate the 

appropriateness of an alternative post-injection site care time frame; demonstrate non endangerment; and 

perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: Enhanced recovery of oil or natural gas and geologic sequestration of CO2 

EPA's Proposal would continue to regulate and permit injection of CO2 for 

EOR/EGR (enhanced gas recovery) purposes as Class II injection "as long as any 

production is occurring." EPA has asked for comment on the merits of this 

approach "since owners or operators of some Class II EOR/EGR wells may wish to 

use wells for the purposes of production and GS prior to the field being 

completely depleted." 73 Fed. Reg. at 43502. We support the Multi-Stakeholder 

consensus recommendation that the rules be clarified to provide more certainty 

about the applicability of Class II requirements where GS of C02 occurs in 

connection with EOR/EGR activities. Specifically, the UIC rules should provide a 

"bright line" definition as to the applicable class of wells where C02 

injections for EOR/EGR production and for GS occur in tandem. We strongly 

support the recommendation for the following language to accomplish that 

objective: 

§ 144.6, 144.80 and 146.5, and Classification of injection wells. 

Injection wells are classified as follows: 

*** 

(b) Class II. Wells which inject fluids: 

(1) Which are brought to the surface in connection with conventional oil 

or natural gas production and may be commingled with waste waters from 

gas plants which are an integral part of production operations, unless 

those waters are classified as a hazardous waste at the time of 

injection. 

(2) For enhanced recovery of oil or natural gas; 

(3) For storage of hydrocarbons which are liquid at standard temperature 

and pressure; 

(4) For enhanced recovery of oil or natural gas where geologic 

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23891

380
sequestration is occurring during or in connection with enhanced 

recovery of oil or natural gas provided (i) there is reasonable 

expectation of more than insignificant future production volumes or 

rates as a result of carbon dioxide injection and (ii) operating 

pressures are no higher than reasonably necessary to produce such 

volumes or rates; 

* * * 

(f) Class VI. Wells injecting a carbon dioxide stream for geologic 

sequestration except those wells described in subsection (b)(4) of this 

section or otherwise excluded from this Class. 

The Multi-Stakeholder group has agreed that wells in classification (b)(4) 

should remain in Class II and be subject to the current requirements of Class 

II. We have also agreed that the wells used for GS in oil and gas reservoirs 

that do not meet the criteria of (b)(4) should be subject to additional 

requirements. We have tentatively defined such wells as wells used "for geologic 

sequestration in oil and gas formations and where the criteria of paragraph (b) 

(4) are not met" But we have not yet reached consensus on defining what specific 

requirements should apply to these wells. We are committed to working toward 

agreement on those requirements (probably within a Class II context) and 

submitting the results of that effort to EPA by February 28, 2009 for your 

consideration. 

ConocoPhillips further recommends that Class VI be used for wells designed 

"exclusively for geologic sequestration of carbon dioxide." This clarifies and 

broadens Class II to include former producing oil and gas wells, EOR wells, EOR 

with simultaneous storage, and EOR fields transitioning to/from storage, such 

that all oil and gas fields storing CO2 are Class II, whether producing or not. 

This approach removes uncertainty for fields which may have become storage 

fields, but return to production as economic conditions change, or cease 

production for some time as part of enhancing recovery, and possibly other 

scenarios. This approach acknowledges the track record of CO2 injection for EOR 

and the significant knowledge base in oil and gas fields. Thus, Class VI 

requirements would acknowledge the greater uncertainties inherent in often 

deeper saline storage, newer field developments, and possibly less defined 

closure structures. This approach also may safely accelerate CCS projects 

utilizing well known oil and gas formations, public acceptance may be more 

likely and regulatory authorities/ oil and gas agencies are in place to begin 

CCS projects. We support API's recommendation to add a Class II (b)(S), "For 

geologic sequestration in oil and gas formations and where the criteria of 

paragraph (b)(4) are not met". 

Response: EPA did not make the suggested change. The Agency disagrees that wells injecting CO2 for 

the primary purpose of long term storage should be regulated under Class II requirements. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

381
EPA is developing guidance on transitioning permits from Class II to Class VI. The guidance will assist 

Directors in determining whether an injection project should be transitioned from Class II where the 

primary purpose is oil and gas production to Class VI where the primary purpose is long-term storage of 

large volumes of CO2. The guidance describes the recommended methods the Director may use to 

evaluate changes in risk to USDWs from projects, and how the Director may determine whether a 

project should be regulated within the Class II or Class VI UIC program. This guidance will be available 

on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. For more 

information, please see the discussion on transition of Class II wells in the preamble to the final GS rule. 

Other EPA Comment Codes and Descriptions: 4110 2.4.1.1 Injection pressure limitations 

Comment: Injection Pressure Limitations 

We are concerned about three aspects of proposed 146.88(a), governing injection 

pressure limitations. First, it "restricts" fractures in the injection zone 

"except during stimulation" rather than focusing on maintaining the integrity of 

the confining zone, which is the suggested focus for protecting USDWs. Second, 

it misses an opportunity to refer specifically to the full range of potential 

geomechanical failure modes potentially posed by operations at a particular 

site. Third, the type of geomechanical risk that is addressed (initiation or 

propagation of fractures), is dealt with in a potentially arbitrary fashion (the 

90% of fracture pressure limit), which may not be appropriate in all cases. 

The MSDG's recommended language addresses these concerns by focusing on 

maintaining the integrity of the confining zone and including tensile failure 

and shear failure as appropriate to evaluate for potential transmissivity 

concerns. It calls for additional geomechanical studies of tensile failure and 

shear failure only "where appropriate" because there will be locations where 

experience or existing information will provide sufficient evidence to avoid the 

need for additional studies. The need for conducting additional tests and for 

determining which tests would be acceptable is left to the Director's 

discretion. Recommended language: 

The owner or operator must comply with a maximum injection pressure 

limit approved by the Director and specified in the permit. In approving 

a maximum injection pressure limit, the Director shall consider the 

results of well tests and, where appropriate, geomechanical or other 

studies that assess the risks of tensile failure and shear failure. The 

Director shall approve limits that, with a reasonable degree of 

certainty, will avoid initiation or propagation of fractures in the 

confining zone or cause otherwise non-transmissive faults transecting 

the confiding zone to become transmissive. In no case may injection 

pressure cause movement of injection or formation fluids in a manner 

prohibited by 40 CFR Part 144.12(a). 

Response: EPA notes that because determination of the injection pressure limit is based on the fracture 

pressure of the injection zone, the limit is site-specific and not arbitrary. EPA emphasizes that injection 

pressure limits are important to protect against fracturing of the confining zone, and that the requirement 

at §146.88(a) that the pressure in the injection zone not exceed 90 percent of the fracture pressure 

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23892

382
provides a margin of safety in the well operation and protects USDWs from endangerment. If the 

Director determines, based on a review of the information collected as part of site characterization, that a 

lower injection pressure limitation is appropriate, the Director has the authority to set a lower limit in the 

operating permit than the limit established in the rule. 

EPA notes that during the site characterization process, owners or operators must submit data about the 

geology of the site, as specified at §146.82(a), including data on known or suspected faults and fractures 

and geomechanical information on fractures, stress, ductility, rock strength, and in situ fluid pressures 

within the confining zone. The Director will use these data to determine appropriate limits on injection. 

In response to the concern about reopening of faults at lower pressures than 90 percent of fracture 

pressure, EPA believes that the requirement for the owner or operator to submit data on known or 

suspected faults and fractures and information on the seismic history of the site will inform the 

determination of an appropriate pressure limitation in the permit. Any sites with the potential for 

reopening or reactivation of faults or unacceptable seismic risk that could otherwise interfere with 

containment will not be permitted as GS sites. 

EPA is developing guidance on site characterization for GS projects to assist owners or operators in 

meeting the requirements of §146.82 and to assist directors in evaluating permit applications. The 

guidance will describe recommended approaches for characterizing the regional geology and 

hydrogeology of a proposed site and performing the necessary geochemical, geomechanical, and 

geophysical analyses of the injection and confining zone. EPA is also developing guidance for primacy 

agencies that will include recommended approaches for evaluating owner or operator-submitted data in 

setting permit conditions. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: We recommend the standard in the proposed alternative language for section 

146.93(b) below because it sets forth detailed criteria, all of which must be 

satisfied, to demonstrate that the site does not pose an endangerment to USDWs. 

The specific criteria listed in our proposal will serve to provide the Director 

with the requisite information to make the appropriate determination. The 

advantage of this approach is that it establishes clear criteria that an 

operator must demonstrate before obtaining site closure based upon particular 

site characteristics and is, therefore, reasonably applicable to any storage 

site as opposed to a standard based upon a fixed duration. Furthermore, it is 

more stringent than a purely discretionary approach because it establishes 

specific criteria that must be presented before site closure may be granted. We 

believe this language, which is an extension of work done by the World Resources 

Institute and the Ground Water Protection Council, avoids the noted shortcomings 

and provides stronger protection for USDWs. 

146.93 (b) The owner or operator shall monitor the site following the 

cessation of injection. 

(1) The owner or operator shall continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site 

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23904

383
closure plan, until closure is authorized pursuant to 146.93(b)(3). 

(2) The owner or operator can request and demonstrate to the 

satisfaction of the Director that the post-injection site care and site 

closure plan should be revised to reduce the frequency of monitoring. 

Response: EPA disagrees with the suggested edits, but believes that the provisions of the final GS rule 

at §146.93(b) address the commenter’s suggestions. Specifically, the owner or operator must monitor the 

site until it can be demonstrated that the CO2 plume and pressure front no longer pose a risk of 

endangerment to USDWs and that monitoring must continue until the owner or operator demonstrates, 

based on monitoring and other site-specific data, that no additional monitoring is needed to ensure that 

the GS project does not pose a risk of endangerment to USDWs, as required at §146.93(b)(3). See the 

final rule and preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 5280 2.8.2.4 USDW non-endangerment 

demonstrations 

Comment: (3) Prior to authorization for site closure, the owner or operator must 

demonstrate to the Director, based on monitoring, other site-specific 

data, and modeling that is reasonably consistent with site performance, 

that no additional monitoring is needed to assure that the geologic 

sequestration project does not and is not expected to pose an 

endangerment to USDWs. The Director shall approve closure if the owner 

or operator demonstrates, based on the current understanding of the 

site, including monitoring data and/or modeling, all of the following: 

(i) the estimated magnitude and extent of the project footprint (CO2 

plume and the area of elevated pressure) ; (ii) the estimated location 

of the detectable CO2 plume; (iii) that there is no significant leakage 

of either CO2 or displaced formation fluids that is endangering USDWs; 

(iv) that the injected or displaced fluids are not expected to migrate 

in the future in a manner that encounters a potential leakage pathway 

into a USDW; (v) that the injection wells at the site completed into or 

through the injection zone or confining zone are plugged and abandoned 

in accordance with these requirements; and (vi) any remaining project 

monitoring wells at the site are being managed by a person and in a 

manner acceptable to the Director. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring timeframe. 

Instead, EPA believes that such determinations are site-specific and should be described in a project 

specific post-injection site care and site closure plan. EPA also believes that periodic reviews and 

updates, where necessary, to the plan are important to ensuring that the site continues to be managed 

effectively and to determine whether shortening the monitoring timeframe is appropriate. The postinjection site care requirements in the final GS rule offer owners or operators flexibility regarding the 

duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC 

timeframe during the post-injection period based on site-specific data, pursuant to requirements at 

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to 

demonstrate, during the permitting process based on substantial data, that an alternative PISC timeframe 

may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23905

384
timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will assist 

Directors in evaluating proposed well plugging plans and post-injection site care and site closure plans 

under §146.92 and §146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells; perform post-injection monitoring; demonstrate the 

appropriateness of an alternative post-injection site care time frame; demonstrate non endangerment; and 

perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions; 1610 1.3.1 

Risks to USDWs; 4400 2.4.4.3 Allowing injection above or between USDWs (seeking comment) 

Comment: Issue 3. The proposed regulation currently defines USDWs as zones that contain 

groundwater with a total dissolved solids (TDS) concentration of less than 

10,000 mg/L. This limit should be revised to consider geologic strata with water 

containing higher TDS concentrations, because these zones may be economic in the 

future. 

The technology for treating high TDS water for use in water supply is improving 

rapidly, and these high TDS aquifer zones may be needed in the future. In areas 

with limited water resources water providers are beginning to turn to 

groundwater sources containing in excess of 10,000 mg/L TDS (Sengebush 2008). 

It is already conceivable that in the near future sources with up to 

approximately 20,000 mg/L TDS will be considered viable as water treatment 

technology advances making such water sources economical. To protect 

groundwater resources which may be economical in the foreseeable future the rule 

should evaluate the potential that currently marginal groundwater sources will 

be usable. The repository zones should be limited to strata containing very high 

TDS concentrations that siting studies and public input indicate are not likely 

to be useable in the future, as use of a zone for CO2 sequestration will likely 

preclude recovery and use of the groundwater resource in the future. 

Sengebush, R. M. 2008, INTERA, Inc. Deep Brackish Water Considered for New 

Mexico Development. Southwest Hydrology, March/April 2008, p. 8. Available from 

http://www.swhydro.arizona.edu/archive/V7_N2/dept-ontheground.pdf. 

Response: The Agency acknowledges the commenter’s concerns about water resources and future water 

resource availability. However, modifying the definition of a USDW is outside the scope of the GS 

rulemaking. USDWs are defined as aquifers currently being used as sources of drinking water or those 

capable of supplying a public water system, with a total dissolved solids (TDS) content of 10,000 

milligrams per liter or less, as specified in §144.3. 

The primary goal of the UIC Program under the SDWA is to protect USDWs from endangerment in 

Commenter Name: Andy Horn Letter ID: 0196

Commenter Organization: Colorado Ground Water Association (CGWA) Comment ID: 23923

385
order to ensure a reliable supply of drinking water for the American public. The GS rule, as part of the 

UIC program regulations implementing the SDWA, continues the program’s mandate of ensuring the 

protection of USDWs. EPA expects that the tailored permitting, siting, construction, operation, 

monitoring, and post-injection site care requirements in the GS rule will prevent leakage from injection 

formations and protect USDWs. 

EPA recognizes that there is increasing demand for water resources and that technology improvements 

may make high TDS aquifers viable drinking water sources. EPA believes these potential resources 

should be considered when injection depth waivers are sought. Therefore, the final GS rule at §146.95

(b) requires the Director to consider these issues in determining whether an injection depth waiver is 

appropriate. Specifically, the Director must consider whether alternative injection sites are available; 

community needs, demands, and supply from drinking water resources; planned needs, potential and/or 

future use of USDWs and non-USDWs in the area; and a plan for securing alternative resources or 

treating USDW formation waters in the event of contamination related to the Class VI injection activity. 

For additional information on the waiver approach, please see the final rule and preamble, as well as 

EPA's responses to comments on the Notice of Data Availability and Request for Comment. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: We believe that use of the phrase "corrective action" to describe well plugging 

and repair risks confusion with the concept of corrective action under either 

RCRA or CERCLA. This potential confusion can lead to unwarranted negative 

associations with the phrase "corrective action," and we would suggest 

abandoning this phrase and instead use a phrase such as "well plugging and 

repair." We would then also support a phased approach to well plugging and 

repair ("corrective action") for CO2 GS wells as contemplated in the Proposal 

and it should be available to all Owners or Operators of CO2 GS wells rather 

than be available only at the discretion of the Director. 73 Fed. Reg. at 

43507-08. 

Response: EPA notes that the term "corrective action" at §146.84(d) has been used to describe the 

process of addressing improperly plugged wells in the AoR of injection wells since the inception of the 

UIC Program, e.g., at §146.7 and §146.64. While EPA is aware that the term has a different meaning 

under RCRA and CERCLA, this has not caused confusion in the past. The alternative term, "well 

plugging," suggested by the commenter is reserved for injection well plugging as indicated at §146.92. 

Other EPA Comment Codes and Descriptions: 5700 2.12 Comments on the proposed duration of 

Class VI permits (seeking comment) 

Comment: Rule Provision: 144.36(a) 

Anadarko Petroleum Corporation (APC) Comments: (a) Permits for Class I and V 

wells shall be effective for a fixed term not to exceed 10 years. UIC Permits 

for Class II AND III and VI wells shall be issued EFFECTIVE for a period 

up to the operating life of the facility. PERMITS FOR CLASS VI WELLS SHALL BE 

EFFECTIVE FOR THE PERIOD THROUGH SITE CLOSURE. 

Commenter Name: Paul Pike Letter ID: 0198

Commenter Organization: Ameren Corporation Comment ID: 23948

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24627

386
Rationale: Permits are necessary for Class VI wells through the end of the post 

closure monitoring phase, which is consistent with the term site closure in the 

amended requirement. 

Response: EPA clarifies that the final GS rule specifies that Class VI permits will be issued for the 

operating life of the facility and the post-injection site care period (144.36(a)). However, it also adds a 

requirement that the Director review each Class VI permit at least every five years to determine whether 

it should be modified, revoked and reissued, terminated, or a minor modification made as provided in 

§§144.39, 144.40, or 144.41. The Director’s review will be informed by the owners’ or operators’ 

iterative reevaluation of the project. Specifically, the final rule includes a requirement that the AoR be 

reevaluated at least every five years, and also requires owners or operators to review and update the AoR 

and corrective action plan, the testing and monitoring plan, and the emergency and remedial response 

plan throughout the life of the project (146.84(e), 146.90(j), and 146.94(d)). Owners or operators must 

review each plan and identify necessary amendments or demonstrate to the Director that no amendment 

is needed. In no case can reviews occur less often than once every five years. The iterative process and 

subsequent plan reevaluations ensure that time and resources are committed to the most critical aspects 

of the permit in preventing endangerment to USDWs. 

EPA believes that the iterative process of developing and executing the various plans required of GS 

well operators in the final rule (e.g., for AoR and corrective action, testing and monitoring, well 

plugging, and post-injection site care, and emergency and remedial response) is tailored to the unique 

aspects of—and is more appropriate for–GS than establishing a finite permit duration (e.g., five years as 

suggested by some commenters). This is preferable to a periodic permit reapplication. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: Rule Provision: 146.23(a) 

Anadarko Petroleum Corporation (APC) Comments: (3) WHEN, ON AN ANNUAL BASIS, THE 

FIELD-WIDE AVERAGE CO2 INJECTION TO WITHDRAWAL RATIO IS GREATER THAN 5.0 

IN AN 

INJECTION ZONE AND THE AVERAGE RESERVOIR PRESSURE IN THE INJECTION ZONE 

BECOMES 

GREATER THAN (A) THE AVERAGE ORIGINAL RESERVOIR PRESSURE IN THE INJECTION 

ZONE 

AT THE TIME OF DISCOVERY OF THE RESERVOIR, OR (B) THE AVERAGE DESIGN 

OPERATING 

PRESSURE DURING CO2 EOR OR EGR, WHICHEVER IS GREATER, THE DIRECTOR MAY 

REQUIRE 

THE OPERATOR OF A CO2 EOR OR EGR PROJECT PERMITTED UNDER CLASS II TO 

PROVIDE 

ADDITIONAL INFORMATION AND DATA TO THE DIRECTOR EXPLAINING THE 

NECESSITY TO 

INCREASE OR MAINTAIN SUCH PRESSURE. 

IF THE DIRECTOR DETERMINES, BASED ON SITE-SPECIFIC CHARACTERISTICS THAT THE 

INFORMATION PROVIDED FAILS TO SUPPORT THE NEED TO INCREASE OR MAINTAIN 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24629

387
THE 

AVERAGE RESERVOIR PRESSURE IN THE INJECTION ZONE ABOVE THE AVERAGE 

ORIGINAL 

RESERVOIR PRESSURE, OR THE AVERAGE DESIGN OPERATING PRESSURE DURING CO2 

EOR OR 

EGR, THE DIRECTOR MAY REQUIRE THE OPERATOR TO: 

(I) REDUCE OR MAINTAIN THE CO2 EOR OR EGR PROJECT’S FIELD-WIDE AVERAGE 

INJECTION 

TO WITHDRAWAL RATIO TO A VALUE SUCH THAT THE AVERAGE RESERVOIR 

PRESSURE OR 

AVERAGE DESIGN OPERATING PRESSURE DURING CO2 EOR OR EGR WITHIN THE 

INJECTION 

ZONE ESSENTIALLY REMAINS CONSTANT; OR 

(II) APPLY TO RECLASSIFY THE CO2 EOR OR EGR INJECTION WELLS AND INJECTION 

ZONE 

COVERED UNDER THE CLASS II PERMIT AS A GEOLOGIC SEQUESTRATION PROJECT 

REGULATED 

UNDER THE APPLICABLE WELL CLASS. 

IF THE OPERATOR FAILS TO COMPLY WITH ANY OF THE ABOVE REQUIREMENTS, THE 

DIRECTOR 

MAY REVOKE OR MODIFY THE APPLICABLE CLASS II INJECTION PERMIT. 

Rationale: A carbon dioxide stream or carbon dioxide may be injected into a 

reservoir for EOR or EGR. When CO2 comes in contact with oil it dissolves into 

the oil, the oil swells, becomes less viscous and the surface tension between 

the oil and the formation is reduced to such a point that the oil becomes 

mobile. The injection of CO2 also raises the pressure in the formation to a 

desired or designed operating pressure. If achievable, the desired operating 

pressure will be above the miscibility pressure of the oil and CO2. Achieving 

sustained pressures at or above the miscibility pressure will generally allow 

the most efficient and effective recovery of the residual oil remaining in the 

formation. Miscibility pressures are dependent on the oil properties, carbon 

dioxide stream properties and the reservoir temperature. Thus, miscibility 

pressure may be less than the average original discovery pressure of the 

reservoir, or may be equal to or greater than the average original discovery 

pressure of the reservoir. The properties of some oils (generally heavier 

crudes) are such that the miscibility pressure of the oil and CO2 is far in 

excess of the average original discovery pressure of the reservoir and can even 

be greater than the fracture pressure of the reservoir and/or the confining 

zone. 

Once the reservoir pressure reaches the designed or desired average reservoir 

pressure for the CO2 EOR project, the injections of CO2 (or CO2 and water in 

water alternating gas CO2 EOR projects) are managed such that the volumes of CO2 

(or CO2 and water) being injected into the reservoir are generally equal to, or 

slightly greater than, the volumes of fluids being withdrawn from the reservoir 

such that the average designed or desired operating reservoir pressure remains 

relatively constant. The desired or designed operating reservoir pressure may be 

388
altered from time to time, but the process of raising the average reservoir 

pressure, and then holding the average reservoir pressure relatively constant, 

is the same. 

Therefore, except during periods of reservoir re-pressurization (i.e. the 

beginning of a CO2 EOR project, or for a period of time when the designed or 

desired average reservoir operating pressure is being raised), the ratio of the 

injected volumes (CO2 + water) to the withdrawal volumes (CO2, oil, associated 

natural gas and water) will most likely be less than 1.5. All volumes should be 

determined at average reservoir conditions, or, at a minimum, at the same 

conditions (i.e. same average pressures and temperatures). 

In contrast, a GS project whether occurring after a CO2 EOR project or as a 

standalone GS project is a project in which the primary, but not necessarily 

only, purpose is to inject and store a CO2 stream. Therefore, the ratio of 

injected volumes (CO2) to the withdrawal volumes (CO2 + other formation fluids) 

should be greatly in excess of 1.5 and more than likely an order of magnitude 

greater. 

In order to allow for reasonable fluctuations and variations within CO2-EOR 

projects an injection-withdrawal ratio of 5.0 (3 to 4 times multiple of typical 

injection-withdrawal ratios) is recommended to distinguish between CO2- EOR and 

Geologic Storage projects. The injection-withdrawal ratio should be measured 

over the applicable reporting period required under the applicable permit and 

will be evaluated on a field-wide basis compared to a well-by-well basis (which 

will allow for phased development). 

Response: As described above in the response to comment 24625 regarding the suggested edit at 144.6, 

EPA did not make the suggested change. The Agency disagrees that wells injecting CO2 for the primary 

purpose of long-term storage should be regulated under Class II requirements because Class II 

requirements do not address the unique risks posed by GS to ensure protection of USDWs from 

endangerment. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment, EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: Rule Provision: 146.81(b) 

Anadarko Petroleum Corporation (APC) Comments: (b) This subpart applies to wells 

used to inject carbon dioxide EXCLUSIVELY for the purpose of geologic 

sequestration, i.e., the long-term containment of a gaseous, liquid or 

supercritical carbon dioxide stream in subsurface geologic formations. IT IS 

RECOGNIZED THAT SOME ACTIVITIES CONDUCTED UNDER CLASS II, INCLUDING CO2 

BASED 

EOR OR EGR MAY SEQUESTER A PORTION OF THE CARBON DIOXIDE STREAM USED FOR 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24631

389
EOR OR 

EGR. THIS SUBPART DOES NOT APPLY TO INJECTION OF A CARBON DIOXIDE STREAM 

FOR 

PURPOSES OF EOR OR EGR EVEN THOUGH GEOLOGIC SEQUESTRATION OF CARBON 

DIOXIDE MAY 

OCCUR DURING OR IN CONNECTION WITH EOR OR EGR OPERATIONS AND/OR 

ACTIVITIES. 

Rationale: See 144.6 

Deleted "gaseous, liquid or supercritical" because it was added to the 

definition of CO2 stream. 

Response: As described above in the response to comment 24625 regarding the suggested edit at 144.6, 

EPA did not make the suggested change. The Agency disagrees that wells injecting CO2 for the primary 

purpose of long-term storage should be regulated under Class II requirements because Class II 

requirements do not address the unique risks posed by GS while ensuring protection of USDWs from 

endangerment. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment, EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: Rule Provision: 146.81(c) 

Anadarko Petroleum Corporation (APC) Comments: (c) ) This subpart applies to 

owners and operators of permit or rule-authorized Class I industrial, Class 

II, or Class V experimental carbon dioxide injection projects who seek to 

apply for a Class VI geologic sequestration permit for their well or wells. If 

the Director determines that USDWs will not be endangered, such wells are 

exempt, at the Director’s discretion, from the casing and cementing requirements 

at §§ 146.86(b) and 146.87(a)(1) through (3). 

Rationale: The reference to Class II wells in section 146.81(c) is no longer 

needed due to addition of 146.25. 

However, if EPA were not to adopt section 146.25, APC would suggest the 

following revisions: 

(c) This subpart applies to owners and operators of permit or rule-authorized 

Class I industrial, Class II WHO HAVE CEASED AND WILL NO LONGER CONTINUE EOR OR 

EGR OPERATIONS OR ACTIVITIES, or Class V experimental carbon dioxide injection 

projects who seek to apply for a Class VI geologic sequestration permit for 

their well or wells. If the Director determines that USDWs will not be 

endangered, such wells are exempt, at the Director’s discretion, from the 

casing and cementing requirements at §§ 146.86(b) and 146.87(a)(1) through 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24632

390
(3). CLASS VI REQUIREMENTS. CLASS II WELLS PERMITTED FOR CO2 INJECTION AND 

THAT HAVE DEMONSTRATED MIT ARE EXEMPT FROM THE REQUIREMENTS AT §§146.86 

AND 

146.87. 

The language allows for the transition of Class II wells to Class VI operations. 

These wells should be allowed to inject CO2 for storage based on their history 

of sound performance under the Class II program as demonstrated by MIT results. 

The language also allows the Director to exercise discretion to exempt other 

Class VI requirements. 

Response: As described above in the response to comment 24625 regarding the suggested edit at 144.6, 

EPA did not make the suggested change. The Agency disagrees that wells injecting CO2 for the primary 

purpose of long-term storage should be regulated under Class II requirements because Class II 

requirements do not address the unique risks posed by GS while ensuring protection of USDWs from 

endangerment. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment, EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach to transitioning from Class II to Class VI. 

EPA is developing guidance on transitioning permits from Class II to Class VI. The guidance will assist 

Directors in determining whether an injection project should be transitioned from Class II where the 

primary purpose is oil and gas production to Class VI where the primary purpose is long-term storage of 

large volumes of CO2. The guidance describes recommended methods the Director may use to evaluate 

changes in risk to USDWs from projects, and how the Director may determine whether a project should 

be regulated within the Class II or Class VI UIC program. This guidance will be available on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. For more information, 

please see the discussion on transition of Class II wells in the preamble to the final GS rule. 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: Rule Provision: 146.82(b) 

Anadarko Petroleum Corporation (APC) Comments: (b) A surface map showing the 

PROPOSED LOCATIONS FOR the injection well(s) for which a permit is sought and 

the applicable area of review. Within the area of review, the map must show the 

number, or name and location of all KNOWN injection wells, producing wells, 

abandoned wells, plugged wells or dry holes, deep STRATAGRAPHIC boreholes, State 

or EPA approved subsurface cleanup sites, surface bodies of water, springs, 

mines (surface and subsurface), quarries, water wells and other pertinent 

surface features including structures intended for human occupancy and roads. 

The map should also show faults, if known or suspected. Only information of 

public record is required to be included on this map; 

Rationale: Faults are not shown on maps unless there is a surface expression of 

the fault. Also, faults are detailed in (d) below and this language appears 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24641

391
redundant. 

Known needs to be added to remove any implication that an applicant has to 

conduct stuides to determine wells that are not currently documented in some 

fashion. 

Response: Regarding the comment that EPA delete mention of faults on surface maps, EPA believes 

that if faults have surface expressions, they should be presented on maps submitted; this information 

would complement the required cross section data. EPA is developing guidance on site characterization 

for GS projects to assist owners or operators and Directors in evaluating permit requirements and 

applications under §146.82. The guidance provides recommendations regarding characterizing the 

regional geology and hydrogeology of a proposed GS site as well as performing the necessary 

geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The 

guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA disagrees that the information that is submitted to support a Class VI permit application should be 

limited to known/available data. The Agency believes that the site characterization requirements at 

§146.82, including geomechanical information and geologic and topographic maps and cross sections, 

are essential to proper siting of a GS well and are the foundation for a detailed understanding of the local 

and regional geology, and that the owner or operator should collect this information, regardless of 

whether it is known in advance of the siting process. Collecting and evaluating this data supports 

important evaluations regarding the suitability of the site to receive and contain injected CO2. Please see 

the final rule and the discussion of geologic site characterization in the preamble for additional 

information. 

EPA acknowledges that some smaller fractures may not be detectable during the site characterization 

process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or 

suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells and sites 

can mitigate the potential impacts of unidentified fractures. These include limitations on injection 

pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and 

assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible 

CO2 movement through high-permeability regions (i.e., faults and/or fractures) not detected in the initial 

site characterization. 

EPA also believes that a determination about whether or what information may be necessary (for a 

specific GS project) is outside of the public record will be site-specific and based on knowledge of the 

site, data availability, and data quality. For instance, in meeting the requirement to tabulate information 

on wells in the AoR, the Director has the discretion to require the owner or operator to supplement a 

data records search if there is reason to believe that the incompleteness of available information could 

compromise USDW protection from endangerment. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(c) 

Anadarko Petroleum Corporation (APC) Comments: (c) A MAP DELINEATING the area of 

review based on UPON modeling, using ALL AVAILABLE data INCLUDING DATA 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24642

392
obtained during logging and testing of the well and the formation as required 

by paragraphs (l), (r), and (s) of this section ANY WELLS IN THE AREA OF 

REVIEW 

Rationale: This appears to be related to a condition where a well is already 

drilled. This does not align with requesting information to receive a permit. 

Response: EPA recognizes that this information may not be available until after a well has been drilled. 

EPA revised §146.82 so that the final regulation specifies separate requirements for information to be 

submitted with the permit application and before well construction is approved (at §146.82(a)) and 

information to be submitted before operation of the well is authorized (at §146.82(c)). 

Final information on injection zone pressures would be required. EPA recognizes that this information 

may not be available until after a well has been drilled. EPA revised §146.82 so that the final regulation 

specifies separate requirements for information to be submitted with the permit application and before 

well construction is approved (at §146.82(a)) and information to be submitted before operation of the 

well is authorized (at §146.82(c)). Final information on injection zone pressures would be required 

following drilling of the well, at §146.82(c)(4). 

In the final rule, the requirement for the final AoR based on modeling, including data obtained during 

logging and testing, can be found at §146.82(c)(1). Please see the final rule and the discussion of 

geologic site characterization in the preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: Rule Provision: 146.82(d) 

Anadarko Petroleum Corporation (APC) Comments: (d) KNOWN information on the 

geologic structure and hydrogeologic RESERVOIR properties of the proposed 

storage site and overlying formations, including: 

(1) ISOPACH maps and OF THE PROPOSED INJECTION AND CONFINING ZONE(S), A 

STRUCTURAL CONTOUR MAP HUNG ON THE TOP OF THE PROPOSED INJECTION ZONE, 

AND AT 

LEAST TWO GEOLOGIC cross sections of the area of review SHOWING THE GEOLOGIC 

FORMATIONS FROM THE SURFACE TO TOTAL DEPTH. 

(2) Location, orientation, and properties of known or suspected SUBSURFACE 

faults and fractures that may transect the confining zone(s) in the area of 

review and a determination that they would not interfere with containment; 

Rationale: If the information is not known, it cannot be reported. 

"Reservoir" and changes to (1) and (2) are technical corrections. 

Fractures generally can’t be identified until a well is drilled and evaluated. 

Even then, only fractures in the immediate vicinity of the wellbore can be 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24643

393
identified. 

Response: EPA believes that all of the site characterization requirements at 146.82, including 

information on faults and fractures, are essential to proper siting of a GS well and are the foundation for 

a detailed understanding of the local and regional geology, and that the owner or operator should collect 

this information, regardless of whether it is known in advance of the siting process. Collecting and 

evaluating this data supports important evaluations regarding the suitability of the site to receive and 

contain injected CO2. 

EPA recognizes that this information may not be available until after a well has been drilled. EPA 

revised §146.82 so that the final regulation specifies separate requirements for information to be 

submitted with the permit application and before well construction is approved (at §146.82(a)) and 

information to be submitted before operation of the well is authorized (at §146.82(c)). Final information 

on injection zone pressures would be required following drilling of the well, at §146.82(c)(4). 

EPA acknowledges that some smaller fractures may not be detectable during the site characterization 

process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or 

suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells and sites 

can mitigate the potential impacts of unidentified fractures. These include limitations on injection 

pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and 

assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible 

CO2 movement through high-permeability regions (i.e., faults and/or fractures) not detected in the initial 

site characterization. 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: Rule Provision:146.82(d)(3) 

Anadarko Petroleum Corporation (APC) Comments: (3) Information on seismic 

history THAT HAVE AFFECTED THE PROPOSED AREA OF REVIEW INCLUDING 

KNOWLEDGE OF 

PREVIOUS SEISMIC EVENTS AND HISTORY OF THESE EVENTS, including the presence and 

depth of seismic sources and a determination that the seismicity would not 

interfere with containment; 

Rationale: Information on seismic history should have some degree of relevance 

to the project. 

Response: EPA believes that consideration of local and regional seismicity is important and this type of 

review is relevant to every project. The site characterization provisions in the GS rule, including a 

review of the local and regional geology, and detailed review of any known or potential seismically 

active terrain in the vicinity of a proposed GS site are necessary to minimize the potential for induced 

seismic events or the reactivation of faults, which are a known potential risk associated with injection 

and are addressed in all aspects of the UIC regulations. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24644

Commenter Name: Craig R. Walters Letter ID: 0200

394
Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: Rule Provision: 146.82(d)(4) & (5) 

Anadarko Petroleum Corporation (APC) Comments: (4) Data on the depth, areal 

extent, thickness, mineralogy, porosity, permeability and capillary 

RESERVOIR pressure of the injection and confining zone(s) WITHIN THE AREA OF 

REVIEW; including geologic/facies changes based on field data which may 

include geologic cores, outcrop data, seismic surveys, well logs, and names and 

lithologic descriptions; 

(5) KNOWN geomechanical information on fractures, stress, ductility, rock 

strength, and in situ fluid pressures within the confining zone(s) WITHIN THE 

AREA OF REVIEW; and 

Rationale: Deleted capillary pressure because it is too hard to measure outside 

of the lab. Using sidewall cores, it may be difficult to determine capillary 

pressure. Additionally, full cores are not available until after the well being 

permitted is drilled. 

Response: EPA acknowledges the comment but did not make the suggested edits. The Agency believes 

that the site characterization requirements at §146.82, including geomechanical information and 

geologic and topographic maps and cross sections, are essential to proper siting of a GS well and are the 

foundation for a detailed understanding of the local and regional geology, and that the owner or operator 

should collect this information, regardless of whether it is known in advance of the siting process. 

Collecting and evaluating this data supports important evaluations regarding the suitability of the site to 

receive and contain injected CO2. 

EPA acknowledges that laboratory methods are standard for determining capillary pressures regardless 

of formation permeability and that in situ measurements would require drilling of a well. However, EPA 

also anticipates that test wells will be drilled to support geologic site characterization of the proposed GS 

sites and can be used to collect subsurface samples (for laboratory determination of capillary pressure) 

and take other necessary measurements. 

EPA recognizes that this information may not be available until after a well has been drilled. EPA 

revised §146.82 so that the final regulation specifies separate requirements for information to be 

submitted with the permit application and before well construction is approved (at §146.82(a)) and 

information to be submitted before operation of the well is authorized (at §146.82(c)). Final information 

on injection zone pressures would be required following drilling of the well, at §146.82(c)(4). 

EPA believes that information on capillary entry pressure is necessary and appropriate. Capillary entry 

pressure measurements on core samples can quantify the amount of buoyant force the confining zone 

can maintain before failure (World Resources Institute, 2008). 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24645

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24646

395
Comment: Rule Provision: 146.82(e) 

Anadarko Petroleum Corporation (APC) Comments: (e) A tabulation of all wells 

ARTIFICIAL PENETRATIONS within the area of review which penetrate the injection 

or confining zone(s). Such data must include a description of each well’s type, 

construction, date drilled, location, depth, record of plugging and/ or 

completion, and any additional information the Director may require; 

Rationale: Artificial penetrations is a more inclusive term. 

Response: EPA agrees that all artificial penetrations must be identified and evaluated during site 

characterization. However the final rule retains the proposed text to be consistent with similar 

requirements for other well classes and to support the corrective action requirements. EPA is developing 

guidance on AoR and corrective action at GS Class VI sites to assist owners or operators and Directors 

in evaluating requirements and proposed AoR and corrective action plans under §146.84. The guidance 

can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(f) 

Anadarko Petroleum Corporation (APC) Comments: (f) Maps and stratigraphic 

cross sections indicating the general vertical and lateral limits of all USDWs, 

water wells and springs within the area of review, their positions relative to 

the injection zone(s) and the direction of water movement, where known; 

POTENTIOMETRIC (WATER LEVEL) SURFACE MAP(S) OF EXISTING AQUIFERS BEING 

UTILIZED 

AS PRIVATE OR PUBLIC WATER SUPPLIES AND THE DIRECTION OF GROUNDWATER 

FLOW IN 

THESE AQUIFERS WITHIN THE AREA OF REVIEW. AT LEAST TWO GEOLOGIC CROSS 

SECTIONS 

SHOWING THE THICKNESS AND GENERAL VERTICAL AND LATERAL LIMITS OF ALL 

USDWS 

WITHIN THE AREA OF REVIEW. 

No rationale provided 

Response: The Agency acknowledges the suggested edits but has retained the language as proposed. 

EPA believes that a thorough understanding of the hydrogeologic conditions of all USDWs in the AoR 

is necessary to protect USDWs from endangerment, and disagrees with the suggested edits because the 

GS rule, as written, affords flexibility to owners or operators and Directors to tailor the site 

characterization process to the unique geologic features of the site. The final requirements will allow for 

submittal of information similar to or the same as that which was suggested by the commenter. EPA 

encourages owners or operators and Directors to consult during site characterization to discuss 

information needs and ensure that all appropriate data necessary to assess the suitability of the site are 

collected. The Director may request additional hydrogeologic data or other data on USDWs as well, as 

provided in §146.82(a)(21). 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24647

396
Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(g) 

Anadarko Petroleum Corporation (APC) Comments: (g) Baseline geochemical data 

on subsurface formations, including all USDWs in the area of review 

COMPILATION OF AVAILABLE GEOCHEMICAL DATA ON THE PROPOSED INJECTION 

ZONE AND 

NEAREST POROUS AND PERMEABLE FORMATION ABOVE THE CONFINING ZONE. 

Rationale: Limits the data submitted to available information and to the 

injection zone and the zone immediately above the confining zone which is the 

zones most likely to be monitored for potential CO2 leakage. 

Response: The Agency acknowledges the suggested edits but has retained the language as proposed. 

EPA believes that a thorough understanding of the hydrogeologic conditions of all USDWs in the AoR 

is necessary, and disagrees with the suggested edits because the GS rule, as written, affords flexibility to 

owners or operators and Directors to tailor the site characterization process to the unique features of the 

site. EPA encourages owners or operators and Directors to consult during site characterization to discuss 

information needs and ensure that all appropriate data necessary to assess the suitability of the site are 

collected. The Director has the authority to request additional hydrogeologic data or other data on 

USDWs as well. 

The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on 

subsurface geologic formations, including all USDWs in the AoR, is appropriate and protective of 

USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate 

and transport model development (e.g., by providing appropriate input parameters), and provide 

information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. 

The baseline geochemical information will allow the owner or operator and permitting authority to 

evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid 

movement. 

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all 

USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining 

system and to serve as a baseline for future monitoring. The Director has the discretion to require 

geochemical analysis of additional subsurface zones if, in the Director's opinion, they are necessary for 

the protection of USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(h) 

Anadarko Petroleum Corporation (APC) Comments: (h) Proposed operating data: 

(1) Average and maximum daily INJECTION rate and volume of the carbon dioxide 

stream; 

(2) Average and maximum SURFACE injection pressure; 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24648

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24649

397
Rationale: Technical clarifications. 

Response: EPA disagrees that the suggested technical clarifications are necessary. EPA adds that it is 

developing guidance for owners or operators on the geologic site characterization process. The guidance 

will provide recommendations for owners and operators to consider when completing a permit 

application. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(n) 

Anadarko Petroleum Corporation (APC) Comments: (n) A WELLBORE schematic or 

other appropriate drawings of the surface and of the subsurface construction 

details of the well AND SURFACE WELLHEAD CONSTRUCTION. 

Rationale: Technical clarification. 

Response: EPA disagrees that the suggested technical clarifications are necessary. EPA adds that it is 

developing guidance for owners or operators on the geologic site characterization process. The guidance 

will provide recommendations for owners and operators to consider when completing a permit 

application. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(q) 

Anadarko Petroleum Corporation (APC) Comments: q) The ANY status of 

corrective action on wells in the area of review; 

Rationale: Clarifies that wells not needing corrective action will not have a 

corrective action status. 

Response: EPA disagrees that the suggested technical clarifications are necessary. EPA adds that it is 

developing guidance for owners or operators on the geologic site characterization and AoR and 

corrective action process. The guidance documents will provide recommendations for owners and 

operators to consider when completing a permit application. The guidance can be found on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3110 2.1.1 Proposed siting requirements (i.e., 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24650

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24651

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24652

398
injection/confining zones, trapping mechanism) 

Comment: Rule Provision: 146.83(a)(2) 

Anadarko Petroleum Corporation (APC) Comments: (2) A confining zone(s) that is 

LATERALLY CONTINUOUS AND free of KNOWN TRANSECTING, transmissive faults or 

fractures and of sufficient areal extent and integrity to contain the injected 

carbon dioxide stream and displaced formation fluids and allow injection at 

proposed maximum pressures and volumes without initiating or propagating 

fractures in the confining zone(s); and OVER AN AREA SUFFICIENT TO PREVENT THE 

MOVEMENT OF INJECTED OR DISPLACED FLUIDS INTO A USDW; 

Rationale: The proposed clarification keeps the emphasis on the non-endangerment 

of USDWs and limits the requirements to that which is known or can be readily 

determined. 

Response: The Agency believes that the requirement at §146.83(a)(2) that the confining zone be free of 

transmissive faults or fractures is appropriate for Class VI wells and is necessary to ensure containment 

of the injectate and that requiring the confining zone to be free of transmissive faults maximizes 

protection of USDWs from endangerment. EPA believes that the text regarding propagation of faults 

and fractures is important to avoid the potential for fluid movement and to ensure that injection is at 

appropriate pressures. Class I hazardous waste injection well operators must also meet a similar 

requirement that the site is free of transmissive faults or fractures; they have successfully made such 

demonstrations in the past. While core samples obtained through drilling and hydraulic testing are direct 

methods to obtain such information, geophysical techniques such as seismic or electromagnetic surveys 

can also be used in many geologic settings to demonstrate the absence of or identify and characterize the 

presence of faults or fractures. EPA adds that the Director must evaluate all geologic data on the site to 

ensure protection of USDWs from endangerment before approving a site for a GS project. 

Other EPA Comment Codes and Descriptions: 3120 2.1.2 Need to identify additional confining and 

containment zones (seeking comment) 

Comment: Rule Provision: 146.83(b) 

Anadarko Petroleum Corporation (APC) Comments: (b) At the Director’s 

discretion, owners or operators of Class VI wells must identify and characterize 

additional zones that will impede vertical fluid movement, are free of faults 

and fractures that may interfere with containment, allow for pressure 

dissipation, and provide additional opportunities for monitoring, mitigation and 

remediation. 

Rationale: This paragraph creates a presumption that additional confining zones 

WILL be required. It is also redundant given the previous sections. 

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, 

secondary confining zones are required when the Director determines that these zones are needed to 

maximize the protection of USDWs from endangerment. EPA retains the requirement to identify 

additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA 

believes that, in some situations, the presence of additional confining and containment zones above the 

primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24653

399
impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for 

monitoring, mitigation, and remediation. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rule Provision: 146.84(a) 

Anadarko Petroleum Corporation (APC) Comments: (a) The area of review is the 

region surrounding the geologic sequestration project that may be impacted by 

the injection activity. The area of review is based on computational modeling 

that accounts for the physical and chemical properties of all phases of the 

injected carbon dioxide stream. SUBSURFACE THREE-DIMENSIONAL EXTENT OF THE 

CARBON DIOXIDE PLUME, ASSOCIATED PRESSURE FRONT, AS WELL AS THE 

OVERLYING 

FORMATIONS AND SURFACE AREA ABOVE THAT DELINEATED REGION. 

Rationale: Edits make this provision consistent with the definition of "Area of 

Review", which was revised. 

Response: EPA disagrees that the AoR definition needs to specifically include the overlying formations 

and surface area above the delineated region. The intent of the AoR, a long-standing concept within the 

UIC Program, is to delineate the surface area and all subsurface formations below it that may potentially 

be impacted by injection activity. Acceptable delineation models will provide predictions of CO2 fate 

and transport, as well as changes in formation pressure, in three dimensions as a function of time that 

can be used to delineate the subsurface storage site and the AoR. Although EPA disagrees with the 

commenter's suggested change, the Agency has carefully considered all comments on the AoR definition 

at 146.84(a) and modified it to read as follows: The region surrounding the geologic sequestration 

project where USDWs may be endangered by the injection activity. The area of review is delineated 

using computational modeling that accounts for the physical and chemical properties of all phases of the 

injected CO2 stream and is based on available site characterization, monitoring, and operational data. 

EPA believes that this definition is sufficiently broad and describes both the intent of the computational 

modeling and the relationship of the AoR to areas that are subject to the risks associated with injection. 

Other EPA Comment Codes and Descriptions: 3700 2.2.5 Comments on the requirement for an AoR 

and corrective action plan 

Comment: Rule Provision: 146.84(b) 

Anadarko Petroleum Corporation (APC) Comments: (b) The owner or operator of a 

Class VI well must prepare, maintain, and comply with a plan to delineate the 

area of review for a proposed geologic sequestration project, periodically 

reevaluate the delineation, and perform corrective action that meets the 

requirements of this section and is IN A MANNER AND AT A FREQUENCY 

acceptable to the Director. As a part of the permit application, for approval 

by the Director the owner or operator must submit an area of review and 

corrective action plan that includes the following information: 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24654

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24655

400
Rationale: Clarification. 

Response: EPA disagrees with the suggested changes and believes the proposed text is clear as written. 

EPA believes that review and approval of the AoR and corrective action plan, including the reevaluation 

frequency of at least every five years, by the Director (and in the context of all information submitted by 

the owner or operator with the permit application) is important to ensuring USDW protection. 

Other EPA Comment Codes and Descriptions: 3500 2.2.3 Area of Review Reevaluation (seeking 

comment); 3700 2.2.5 Comments on the requirement for an AoR and corrective action plan 

Comment: Rule Provision: 146.84(b)(2) 

Anadarko Petroleum Corporation (APC) Comments: (i) The minimum fixed 

frequency, not to exceed 10 years, the owner or operator proposes to reevaluate 

the area of review; 

(ii) The monitoring and operational conditions that would warrant a reevaluation 

of the area of review prior to the next scheduled reevaluation as determined by 

the minimum fixed frequency established in paragraph (b)(2)(i) of this 

section. 

(iii)(i) How monitoring and operational data (e.g., injection rate and 

pressure) will be used to inform an area of review reevaluation; and 

No rationale provided 

Response: EPA believes that periodic AoR reevaluation at a set frequency of at least every five years is 

necessary to ensure protection of USDWs from endangerment and address the uncertainties inherent in 

predictive modeling. Periodic AoR reevaluations at §146.84(e) ensure that a deliberate effort is made to 

verify, based on monitoring and operational data, that the CO2 plume is moving within the subsurface as 

predicted. EPA believes that less frequent reevaluations may not be sufficient to appropriately model 

plume and pressure front movement, establish conditions for corrective action, and ensure protection of 

USDWs from endangerment. 

EPA clarifies that if site monitoring data agrees with the existing AoR delineation, a model recalibration 

may not be necessary, and the AoR reevaluation may consist of a demonstration that the current AoR 

delineation is adequate based on site monitoring data. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action; 3700 2.2.5 Comments 

on the requirement for an AoR and corrective action plan 

Comment: Rule Provision: 146.84(b)(2)(iv) 

Anadarko Petroleum Corporation (APC) Comments: (iv II) How corrective action 

will be conducted to meet the requirements of paragraph (d) of this section, 

including what corrective action will be performed prior to injection and what, 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24656

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24657

401
if any, portions of the area of review will have corrective action addressed on 

a phased basis and how the phasing will be determined; how corrective action 

will be adjusted if there are changes in the area of review; and how site access 

will be guaranteed ARRANGED for future corrective action. 

Rationale: Future access cannot be guaranteed for an area in advance that may 

not even be within the boundaries of the AOR/ project. 

Response: The purpose of the corrective action requirement at §146.84(d) is to ensure that all wells in 

the AoR that have the potential to cause the movement of CO2 or other fluids into or between USDWs 

receive appropriate corrective action. In general, to meet this requirement, the owner or operator will 

most likely need to obtain the right of access to wells that may require corrective action, and 

demonstrate they have done this in their proposed AoR and corrective action plan. The final rule retains 

the requirement as proposed. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rule Provision: 146.84(c)(1) 

Anadarko Petroleum Corporation (APC) Comments: (1) Predict, using computational 

modeling, the projected lateral and vertical migration of the carbon dioxide 

plume and formation fluids in the subsurface from the commencement of injection 

activities until the plume movement ceases, pressure differentials sufficient to 

cause the movement of injected fluids or formation fluids into a USDW are no 

longer present, or after FOR a fixed time period as determined by the 

Director. The model MODELING must: 

Rationale: Clarification 

Response: Based on an evaluation of all comments received, EPA has clarified this language in the final 

rule at 146.84(c)(1). It now reads, “Predict, using existing site characterization, monitoring and 

operational data, and computational modeling, the projected lateral and vertical migration of the carbon 

dioxide plume and formation fluids in the subsurface from the commencement of injection activities 

until the plume movement ceases, until pressure differentials sufficient to cause the movement of 

injected fluids or formation fluids into a USDW are no longer present, or until the end of a fixed time 

period as determined by the Director.” 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rule Provision: 146.84(c)(1)(i) & (ii) 

Anadarko Petroleum Corporation (APC) Comments: (i) Be based on detailed geologic 

data collected to characterize the injection zone, confining zone and any 

additional zones; and anticipated operating data, including injection 

pressures, rates and total volumes over the proposed life of the geological 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24658

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24659

402
sequestration project THE DURATION OF INJECTION; 

(ii) Take into account any RELEVANT geologic heterogeneities, AND data 

quality, and their possible impact on model predictions; and 

Rationale: Clarification. 

Response: EPA agrees that detailed geologic data is invaluable to modeling an accurate AoR. EPA 

clarifies that owners or operators may use existing data as well as data collected during site 

characterization to predict the AoR. The final rule retains the language in §146.84(c)(1)(i) as proposed, 

and modifies §146.84(c)(1)(ii) slightly to require owners or operators to take into account “other 

discontinuities” in addition to geologic heterogeneities when predicting the AoR. 

EPA disagrees that only the injection and confining zones should be included in AoR modeling of GS 

sites. EPA believes that the modeling should also take into account the possibility of displaced fluids or 

brines caused by a lateral and/or vertical pressure plume, and therefore it may be necessary to include 

additional zones along with the confining/injection zones to ensure the integrity of the confining zone 

and ultimately protect a USDW from endangerment. 

Other EPA Comment Codes and Descriptions: 3420 2.2.2.1 Scope of the inventory process (e.g., 

reliance on publicly available information, depth of wells) 

Comment: Rule Provision: 146.84(c)(2) 

Anadarko Petroleum Corporation (APC) Comments: (2) Using methods approved by the 

Director, identify all KNOWN ARTIFICIAL penetrations INTO THE CONFINING ZONE, 

including active and abandoned wells and underground mines, in the area of 

review that may penetrate the confining zone. Provide a description of each 

well’s type, construction, date drilled, location, depth, record of plugging 

and/or completion, and any additional information the Director may require; and 

Rationale: Changed for consistency with earlier language. 

Response: EPA is retaining the requirement as proposed. EPA agrees with commenters that, for most 

GS sites, relying on database and other public records searches (i.e., of "known" artificial penetrations) 

will be sufficient to meet the requirements at §146.84(c)(2). However, the Agency recognizes that there 

may be situations where additional surveys or research to locate wells may be appropriate. For example, 

there may be cases where the Director may determine that ground or airborne surveys for wells are 

appropriate, e.g., if there is reason to believe, based on knowledge of the site or of available data, that 

the incompleteness of information on known wells could compromise USDW protection from 

endangerment. In order to preserve the Director's discretion to require an operator to supplement a 

records search, EPA did not make the suggested change. EPA adds that all corrective action must be 

performed pursuant to the approved AoR and corrective action plan, which affords the Director the 

discretion to require any additional information needed (including information that is not publically 

available) to ensure that all necessary corrective action is performed. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24660

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24661

403
Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: Rule Provision: 146.84(c)(3) 

Anadarko Petroleum Corporation (APC) Comments: (3) Determine which abandoned 

wells IDENTIFIED IN 146.84 (C) (2) in the area of review have been plugged 

(as required by §146.92) in a manner that prevents the movement of carbon 

dioxide or associated FORMATION fluids that may endanger USDWs. 

Rationale: Remove as redundant. 

Response: EPA clarifies that the term "associated fluids" as proposed in §146.84(c)(3) refers to 

formation fluids, other injectates, etc. that may be present in the subsurface and affect movement of the 

CO2 plume and/or pressure front. EPA believes this terminology would incorporate any fluids in the 

subsurface that could potentially move through artificial penetrations and affect USDWs. EPA has 

revised the language at §146.84(c)(3) to read, "... carbon dioxide or other fluids that may endanger 

USDWs..." EPA disagrees that deleting the term area of review is necessary and has retained the term in 

the final rule language. 

Other EPA Comment Codes and Descriptions: 3460 2.2.2.3 Acceptable corrective action techniques 

for GS sites (e.g., cements) 

Comment: Rule Provision: 146.84(d) 

Anadarko Petroleum Corporation (APC) Comments: (d) Owners or operators of Class 

VI wells must perform corrective action USING MATERIALS SUITABLE FOR USE WITH 

THE CARBON DIOXIDE STREAM AND FORMATION FLUIDS, on all wells in the area of 

review IDENTIFIED IN 146.84(C)(2) that are determined to need corrective 

action". using methods necessary to prevent the movement of fluid into or 

between USDWs including use of corrosion resistant materials, where 

appropriate. 

Rationale: Experience with CO2 based EOR strongly supports the use of many 

conventional materials that might not meet the technical definition of 

"corrosion resistant". 

Response: EPA revised the text at §146.84(d) to require the use of materials that are "compatible with 

the carbon dioxide stream." EPA believes this language change addresses commenters' concerns and is 

also consistent with other language regarding materials requirements in the GS rule. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: Rule Provision: 146.84(e) 

Anadarko Petroleum Corporation (APC) Comments: (e) If monitoring data indicate 

an endangerment to USDWs, the owner or operator must notify the Director and 

cease operations as required by § 146.94. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24662

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24663

404
Rationale: This is not needed if §146.94 already specifies the notification and 

cessation of injection. APC suggests the removal of this language as 

unnecessarily duplicative. 

Response: Based on consideration of all public comments and other information, EPA deleted this 

provision from §146.84. The final rule now contains a provision in §146.91(c) that requires the owner or 

operator to report within 24 hours any evidence that the carbon dioxide stream or associated pressure 

front may cause an endangerment to a USDW. EPA believes this change consolidates reporting 

requirements in one place and provides additional clarity. 

Other EPA Comment Codes and Descriptions: 3530 2.2.3.1 AoR reevaluation frequency (seeking 

comment) 

Comment: Rule Provision: 146.84(f) 

Anadarko Petroleum Corporation (APC) Comments: (f) At the minimum fixed 

frequency, not to exceed 10 years, as specified in the APPROVED area of review 

and corrective action plan, or when monitoring and operational conditions 

warrant, owners or operators must: 

Rationale: Clarification. 

Response: EPA did not make the suggested change, but agrees that AoR reevaluations must take place 

as specified in approved AoR and corrective action plan. EPA clarifies that owners or operators must 

develop, implement, and update a Director-approved AoR and corrective action plan as required under 

§146.84(b). EPA is developing guidance for owners or operators on how to prepare the required GS 

project plans. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3700 2.2.5 Comments on the requirement for an AoR 

and corrective action plan 

Comment: Rule Provision: 146.84(f)(4) 

Anadarko Petroleum Corporation (APC) Comments: (4) Submit an amended area of 

review and corrective action plan or demonstrate to the Director through 

monitoring data and modeling results that no amendment CHANGE to the area of 

review and corrective action plan is needed. 

Rationale: Clarification. 

Response: EPA disagrees with the suggested change and believes the proposed text is clear as written. 

For additional information on EPA's approach to AoR and corrective action, please see the final rule and 

preamble. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24664

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24665

Commenter Name: Craig R. Walters Letter ID: 0200

405
Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

responsibility requirements (40 CFR 146.85) 

Comment: Rule Provision: 146.85(a)(1) 

Anadarko Petroleum Corporation (APC) Comments: (1) The Director receives WELL 

PLUGGING REPORT IDENTIFIED IN 146.92(D) and approves OR COMPLETION OF the 

completed post-injection site care and site closure plan as appropriate; 

and 

Rationale: Maintenance of the well plugging financial obligation until site 

closure is not necessary. The Director should have the authority to release the 

obligation once the well is plugged. 

Response: EPA will allow owners or operators to use separate financial responsibility instruments for 

different GS activities as long as they are able to demonstrate that their instruments will protect USDWs 

from endangerment. This means that owners or operators must demonstrate adequate financial 

responsibility for all required activities, including well plugging, with their permit application, per 

§146.82(a)(14). In addition, on an annual basis, the owner or operator must adjust the cost estimate for 

inflation, increase or decrease the value of the financial instrument to match the cost estimate, and 

provide any updated information related to their financial responsibility instrument(s), or at any other 

time deemed appropriate by the Director. These annual reviews provide a mechanism for revising cost 

estimates up or down to account for changes in the project, including the execution of environmental 

obligations as phases of a GS project are completed. 

Regarding the suggested edit at §146.85(a)(1), EPA clarifies that the owner or operator may be released 

from a financial instrument when the phase of the project for which the instrument was required is 

complete and all financial obligations for that instrument have been met, as specified in §146.85(b)(2). 

For example, when the injection well is plugged to the Director's satisfaction, the owner or operator's 

financial instrument will be released if it was not used. 

EPA is developing guidance on financial responsibility for Class VI wells. The guidance will include a 

discussion on how best to estimate costs to assist GS well owners or operators, third party insurers or 

providers of financial instruments, and permitting authorities in developing estimates of the costs 

associated with various GS activities. The guidance is available on EPA's website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

responsibility requirements (40 CFR 146.85) 

Comment: Rule Provision: 146.85(b) 

Anadarko Petroleum Corporation (APC) Comments: (b) The owner or operator must 

provide to the Director, at a frequency determined by the Director, BUT NO MORE 

THAN ANNUALLY, written updates of adjustments to the cost estimate to account 

for any amendments CHANGE to the area of review and corrective action plan 

(§146.84), the injection well plugging plan (§146.92), and the post-injection 

site care and site closure plan (§146.93). 

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24666

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24667

406
Rationale: Updates more frequent than annual is not justified. 

Response: Cost estimates must be reevaluated after amendments to the area of review and corrective 

action plan, prior to well plugging or site closure, after amendments to the emergency and remedial 

response plan, or at any other time deemed appropriate by the Director. The rule will also require annual 

adjustments to the cost estimates for inflation, as specified in §146.85(c)(2). These annual reviews 

provide a mechanism for revising cost estimates up or down to account for changes in the project, 

including the execution of environmental obligations as phases of a GS project are completed. 

EPA did not make the proposed edits at §146.85(b), but did extensively revise and clarify the financial 

responsibility requirements. See the final GS rule and preamble for additional information on EPA's 

final approach. 

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

responsibility requirements (40 CFR 146.85) 

Comment: Rule Provision: 146.85(c) 

Anadarko Petroleum Corporation (APC) Comments: (c) The owner or operator must 

notify the Director of adverse financial conditions such as bankruptcy, that 

may affect the ability to carry out injection well plugging and post-injection 

site care and site closure. 

Rationale: Clarification. 

Response: EPA did not make the proposed edits at §146.85(c), but did extensively revise and clarify the 

financial responsibility requirements. EPA believes that the Director must be notified of bankruptcy 

specifically, among other adverse financial conditions, because it affects the use of financial 

instruments. See the final GS rule and preamble for additional information on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 5432 2.9.1.1 Need to adjust financial responsibility 

mechanisms (seeking comment) 

Comment: Rule Provision: 146.85(d) 

Anadarko Petroleum Corporation (APC) Comments: (d) The operator must provide an 

adjustment of the cost estimate to the Director if the Director has reason to 

believe that original THE MOST RECENT demonstration is no longer adequate to 

cover the cost of injection well plugging (as required by §146.92) and postinjection site care and site closure (as required by §146.93) 

Rationale: Clarification. 

Response: EPA agrees that it is important to periodically update cost estimates that support financial 

responsibility determinations. EPA clarifies that the GS rule, at §146.85(e), requires the owner or 

operator to provide annual updates to the cost estimate to account for any amendments to the AoR and 

corrective action plan, the injection well plugging plan, and the PISC and site closure plan. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24668

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24669

407
Other EPA Comment Codes and Descriptions: 3800 2.3 Proposed Injection Well Construction 

Requirements (40 CFR 146.86) 

Comment: Rule Provision: 146.86(a)(1) 

Anadarko Petroleum Corporation (APC) Comments: (1) Prevent the movement of fluid 

into or between USDWs or into any unauthorized zones; CONTAINING ANY 

CONTAMINANT INTO UNDERGROUND SOURCES OF DRINKING WATER, IF THE 

PRESENCE OF THAT 

CONTAMINANT MAY CAUSE A VIOLATION OF ANY PRIMARY DRINKING WATER 

REGULATION UNDER 

40 CFR PART 142 OR MAY OTHERWISE ADVERSELY AFFECT THE HEALTH OF PERSONS.; 

Rationale: The proposed changes reflect the nonendangerment standard that is the 

basis of the UIC program. 

Response: EPA disagrees that the language provided in § 146.86(a)(1) does not meet the nonendangerment standard provided under the SDWA. In fact, EPA believes that protection of USDWs 

from endangerment and prevention of fluid movement between formations is paramount and believes 

that the language as proposed meets the non-endangerment standard. Appropriately designed and 

constructed wells are necessary to prevent endangerment to USDWs and maintain integrity of the well 

throughout the lifetime of a GS project. This is the foundation of the requirements for construction and 

pre-operational testing of Class VI wells at §§146.86 and 146.87. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment, EPA has made many revisions to the GS rule. Please see the final rule and preamble for 

additional information. 

Other EPA Comment Codes and Descriptions: 3860 2.3.3 Well component degradation 

Comment: Rule Provision: 146.86(b)(1) 

Anadarko Petroleum Corporation (APC) Comments: (1) Casing and cement or other 

materials used in the construction of each Class VI well must have sufficient 

structural strength and be designed for the operating life of the geologic 

sequestration project WELL. All well materials must be compatible SUITABLE 

FOR USE with the fluids with which the materials may be expected to come into 

contact and meet or exceed TEST standards OR PRACTICES developed for such 

materials by the American Petroleum Institute, ASTM International, or comparable 

standards acceptable to the Director. The casing and cementing program must be 

designed to prevent the movement of fluids into or between USDWs. In order to 

allow the Director to determine and specify casing and cementing requirements, 

the owner or operator must provide the following information: 

Rationale: The life of a geologic sequestration project could be different than 

the life of the well. Class VI well design should be based on the life of the 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24670

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24671

408
well. 

Response: EPA disagrees that the casing, cement, or other materials should only be designed for the 

period of the injection process, rather than the life of the sequestration project. GS projects are 

anticipated to have long life spans in comparison to other types of deep injection wells. Not only must 

Class VI wells be able to function safely and properly over the lifespan of the GS project, but they must 

be constructed such that USDWs remain protected after well plugging. The requirements at §146.86 will 

ensure that the well can maintain integrity throughout the proposed life span of the project, including 

after the injection well is plugged and through the post-injection site care period and beyond. While the 

risk profile of a GS site will decrease following cessation of injection, EPA believes that Class VI wells 

must be designed to protect USDWs from endangerment for the life of the project. Furthermore, 

rigorous casing and cementing help ensure that the Class VI well will not serve as a conduit for 

movement of fluids associated with future injection operations. 

Other EPA Comment Codes and Descriptions: 3864 2.3.3.2 Use of corrosion-resistant cements 

(seeking comment) 

Comment: Rule Provision: 146.86(b)(1)(v) 

Anadarko Petroleum Corporation (APC) Comments: (v) Corrosiveness COMPOSITION 

of the carbon dioxide stream and formation fluids; 

Rationale: There is no method for measurement of "corrosiveness" of a CO2 

stream. The relevant information is the composition of the CO2 stream. 

Response: The suggested revision to refer to CO2 "composition" would be less precise. EPA clarifies 

that, although corrosiveness does not have a unit of measure, corrosiveness can be technically measured 

and described. Procedures that can identify corrosion (or the absence of corrosion) in a Class VI well 

provide valuable operational information that the Director needs to determine appropriate standards for 

the tubing and packer. 

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3860 2.3.3 Well component degradation 

Comment: Rule Provision: 146.86(b)(1)(vi) 

Anadarko Petroleum Corporation (APC) Comments: (vi) Down-hole temperatures AND 

PRESSURES; 

Rationale: Technical clarification 

Response: EPA clarifies that information on down-hole pressures is required at §146.86(b)(1)(ii). 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24672

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24673

409
Other EPA Comment Codes and Descriptions: 3860 2.3.3 Well component degradation 

Comment: Rule Provision: 146.86(b)(1)(viii) 

Anadarko Petroleum Corporation (APC) Comments: (viii) Type or grade of cement 

AND ADDITIVES; and 

Rationale: Technical clarification. 

Response: EPA agrees with the suggestion that §146.86(b)(1)(viii) be revised to also address cement 

additives. In the final GS rule, the subparagraph reads as follows: "Type or grade of cement and cement 

additives." 

Other EPA Comment Codes and Descriptions: 3822 2.3.1.1 Depth of surface casing (seeking 

comment) 

Comment: Rule Provision: 146.86(b)(2) 

Anadarko Petroleum Corporation (APC) Comments: (2) Surface casing must extend 

through the base of the lowermost USDW ABOVE THE INJECTION ZONE and be cemented 

to the surface. 

Rationale: In some parts of the US the USDW is very deep and this standard may 

preclude geologic sequestration in these areas. 

Response: EPA disagrees with the suggested edit. As described above, EPA disagrees that the surface 

casing requirements in the GS rule preclude injection below deep USDWs. EPA also recognizes 

concerns regarding construction of Class VI wells where the lowermost USDW is very deep. To further 

address comments on deep injection wells, the final GS rule at §146.95 includes requirements for 

owners or operators that seek a waiver of the injection depth requirements. Owners or operators of wells 

operating under injection depth waivers must comply with additional construction requirements to 

ensure that wells used to inject above or between USDWs are protective. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: Rule Provision: 146.86(b)(3) 

Anadarko Petroleum Corporation (APC) Comments: (3) At least one long string 

casing, using a sufficient number of centralizers TO CREATE A CEMENT BOND 

THROUGH THE INJECTION AND CONFINING ZONE(S), must extend to the injection zone 

and must be cemented ISOLATED by circulating cement to the surface in one 

or more stages. PLACING CEMENT AND/OR OTHER ISOLATION TECHNOLOGIES AS 

NECESSARY TO PROVIDE ADEQUATE ISOLATION OF THE INJECTION ZONE AND 

PROVIDE FOR 

PROTECTION OF USDWS. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24674

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24675

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24676

410
Rationale: Cementing to surface is not necessary to protect USDWS, and may have 

negative consequences, as follows. Cement to surface would eliminate the ability 

to monitor pressures in this annulus and would limit flexibility of remedial 

options. As revised, the proposal would allow for application and development of 

alternative technologies. See API RP90 for description of risk-based approach 

for managing situations involving annular casing pressure. Industry experience 

with CO2 EOR under the class II program demonstrates the effectiveness of 

existing cementing procedures. 

Response: EPA disagrees with the suggested edits. EPA believes that the requirements for long-string 

casing are appropriate and offer appropriate flexibility: §146.86(b)(3) requires that the long-string casing 

extend to the injection zone and be cemented by circulating cement to the surface in one or more stages. 

It does not, however, specify how cementing would be accomplished, and gives flexibility to the owner 

or operator to propose alternate methods to provide a sufficient amount of cement to meet the standard 

that USDWs are protected from endangerment, subject to the approval of the Director. 

EPA stresses that protection of USDWs is the primary mission and mandate of the UIC program and the 

purpose of all requirements for injection wells. Any injection activity must be demonstrated to not 

endanger USDWs, regardless of their depth, and if such non-endangerment cannot be shown, then the 

activity will not be allowed under UIC requirements or the SDWA. 

EPA does not believe that the cementing requirements at §146.86 would prevent monitoring, operation, 

and remediation of Class VI wells. Cementing of deep wells has been performed successfully in the past 

by owners or operators of Class I hazardous and Class I municipal waste disposal wells. Some of these 

wells, which must meet the same cementing and casing requirements as Class VI wells, are up to 12,000 

feet deep and have been successfully cemented in a manner that maintains integrity and allows for all 

required well testing, operation, and remediation (EPA, 2001). See the discussion of Class VI well 

construction requirements in the preamble to the final GS rule for additional information. Additionally, 

EPA is developing guidance on the construction of Class VI wells. This guidance will be available on 

EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: Rule Provision: 146.86(b)(4) 

Anadarko Petroleum Corporation (APC) Comments: (4) Circulation of cement may 

be accomplished by staging. The Director may approve an alternative method of 

cementing in cases where the cement cannot be recirculated to the surface, 

provided the owner or operator can demonstrate by using logs that the cement 

does not allow fluid movement behind the well bore. 

Rationale: Same as above 

Response: EPA disagrees that the requirement should be deleted. Section 146.86(b)(4) of the final rule 

allows alternate methods of staging the cement, at the Director's discretion, provided the owner or 

operator can demonstrate using logs that the cement does not allow fluid movement behind the wellbore.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24677

411
See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: Rule Provision: 146.86(b)(5) 

Anadarko Petroleum Corporation (APC) Comments: (5) Cement and cement additives 

must be compatible SUITABLE FOR USE with the carbon dioxide stream and 

formation fluids and of sufficient quality and quantity to maintain integrity 

over the design OPERATING life of the geologic sequestration project 

WELL. The integrity and location of the cement shall be verified using 

technology capable of evaluating cement quality radially and identifying the 

location of channels to ensure that USDWs are not endangered. 

Rationale: Experience with CO2 EOR under the class II program demonstrates the 

effectiveness of existing cementing materials and procedures. Standard API 

cements have been used in numerous CO2 EOR operations with no adverse 

consequences. Refer to the citations within EPA’s proposed rule 73 FR 43532- 

43533: Carey et al., (2007), Crow et al., (2008), and Meyer, J.P (2007). 

Response: EPA disagrees with the suggested edits. EPA disagrees that the casing, cement or other 

materials should only be designed for the period of the injection process, rather than the life of the 

sequestration project. GS projects are anticipated to have long life spans in comparison to other types of 

deep injection wells. Not only must Class VI wells be able to function safely and properly over the 

lifespan of the GS project, but they must be constructed such that USDWs remain protected after well 

plugging. The requirements at §146.86 will ensure that the well can maintain integrity throughout the 

proposed life span of the project, including after the injection well is plugged and through the postinjection site care period and beyond. While the risk profile of a GS site will decrease following 

cessation of injection, EPA believes that Class VI wells must be designed to protect USDWs from 

endangerment for the life of the project. Furthermore, rigorous casing and cementing help ensure that 

the Class VI well will not serve as a conduit for movement of fluids associated with future injection 

operations. 

EPA recognizes that the oil and gas industry has decades of experience injecting CO2 and has 

demonstrated the effectiveness of existing cementing materials and procedures. The final GS rule, at 

§146.86(b)(1), specifies that all casing and cementing or other materials used in the construction of 

Class VI wells must meet or exceed standards developed for such materials by the American Petroleum 

Institute, ASTM International, or comparable standards acceptable to the Director. This requirement 

invokes the expertise of these bodies to ensure that the requirements for construction of Class VI wells 

reflect the state of the art in well construction technology. See the discussion of Class VI well 

construction requirements in the preamble to the final GS rule for additional information. Additionally, 

EPA is developing guidance on the construction of Class VI wells. This guidance will be available on 

EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA also believes that GS is sufficiently different from Class II ER operations to warrant the tailored 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24678

412
construction requirements for Class VI wells at §146.86. For example, the volume of CO2 anticipated to 

be injected in Class VI wells is significantly greater than for Class II wells. Reservoir pressure 

conditions will be different, with Class VI injection operations involving large volumes of CO2 and 

likely having higher pressures within their storage formations than Class II ER projects. Therefore, Class 

VI GS reservoir pressures will increase during the injection phase of the GS project. 

Other EPA Comment Codes and Descriptions: 3826 2.3.1.3 Packer requirements (seeking comment) 

Comment: Rule Provision: 146.86(c)(2)(ii) 

Anadarko Petroleum Corporation (APC) Comments: (ii) Composition of the carbon 

dioxide stream. (chemical content, corrosiveness, temperature, and density); 

Rationale: There is no method for measurement of "corrosiveness" of a CO2 

stream. The relevant information is the composition of the CO2 stream. The 

composition of the CO2 stream is more relevant to the design of a tubing and 

packer system. 

Response: As written, the text at §146.86(c)(3)(ii) accounts for all characteristics of the CO2 that could 

affect the performance of the tubing and packer, including the chemical content, corrosiveness, 

temperature, and density. The suggested revision to refer to CO2 "composition" would be less precise. 

EPA clarifies that, although corrosiveness does not have a unit of measure, corrosiveness can be 

technically measured and described. Procedures that can identify corrosion (or the absence of corrosion) 

in a Class VI well provide valuable operational information that the Director needs to determine 

appropriate standards for the tubing and packer. 

The final GS rule at §146.86(c)(1) also requires that tubing materials used in Class VI wells must meet 

or exceed standards developed by the American Petroleum Institute, ASTM International, or comparable 

standards acceptable to the Director. EPA believes that this requirement invokes the expertise of these 

bodies without the added burden of a certification program. 

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3826 2.3.1.3 Packer requirements (seeking comment) 

Comment: Rule Provision: 146.86(c)(2)(iii) - (v) 

Anadarko Petroleum Corporation (APC) Comments: (iii) MAXIMUM PROPOSED Injection 

temperature and pressure; 

(iv) MAXIMUM PROPOSED Annular pressure; 

(v) MAXIMUM PROPOSED Injection rate (intermittent or continuous) and volume of 

the carbon dioxide stream; 

Rationale: Technical corrections. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24679

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24680

413
Response: EPA has revised §146.86(c)(3)(iii) and (iv) to reference the maximum proposed injection 

pressure and maximum proposed annular pressure, respectively. EPA has revised §146.86(c)(3)(v) to 

read "proposed injection rate (intermittent or continuous), and volume and/or mass of the carbon dioxide 

stream." EPA believes that reference to the continuous injection rate would be duplicative of the 

maximum rate. EPA believes that considering the maximum injection and annular pressure would be 

more protective. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a) 

Anadarko Petroleum Corporation (APC) Comments: (a) During the drilling and 

construction of a Class VI injection well, the owner or operator must run 

appropriate logs, surveys and tests to determine or verify the depth, thickness, 

porosity, permeability, and lithology of, and the salinity of any formation 

fluids in, all relevant geologic formations to assure conformance with the 

injection well construction requirements under §146.86, and to establish 

accurate baseline data against which future measurements may be compared. The 

owner or operator must submit to the Director a descriptive report prepared by a 

knowledgeable log analyst that includes an interpretation of the results of such 

logs and tests. At a minimum, such logs and tests must include: THE DIRECTOR 

MAY REQUIRE SUCH LOGS AND TESTS AS MAY BE NEEDED AFTER TAKING INTO 

ACCOUNT THE 

AVAILABILITY OF SIMILAR DATA IN THE AREA OF THE DRILLING SITE, THE 

CONSTRUCTION 

PLAN, AND THE NEED FOR ADDITIONAL INFORMATION THAT MAY ARISE FROM TIME 

TO TIME 

AS THE CONSTRUCTION OF THE WELL PROGRESSES AND THESE MAY INCLUDE THE 

FOLLOWING: 

Rationale: In well defined areas, these evaluations are frequently unnecessary. 

The director should have discretion to select the appropriate requirements 

necessary to ensure sufficient baseline data and information are available. For 

example, in an area where a number of wells are being drilled, the logging of 

surface hole yields little useful additional information. In particular, this 

change would allow the Director to reduce the requirements when multiple wells 

are installed for a project. 

Response: EPA disagrees that the requirements for logs, surveys, and tests are unnecessary. All logs, 

surveys, and tests listed at §146.87(a) are necessary to verify information about the injection and 

confining zones and ensure that the well is being drilled and cased as approved, and has mechanical 

integrity. This information is needed to demonstrate that the well can be operated and tested in a manner 

that protects USDWs from endangerment. While the tests do provide information on some of the same 

items, each test provides unique pieces of information that build on each other and allow for 

interpretations not possible with a single test. 

EPA notes that the Director has the discretion at §146.87(a)(5) to approve alternative methods that 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24681

414
provide equivalent or better information, and the Director may accept information on cores of the 

injection and confining zones from nearby wells if the owner or operator can demonstrate that such 

cores are representative of conditions at the well in question and core retrieval is not possible, as 

specified at §146.87(b). EPA believes that logs and tests must be performed on each well drilled 

regardless of existing information about the area to account for the complexity of CO2 injection well 

construction and the buoyancy of CO2. Existing lithologic and geologic information may lack the details 

needed for site-specific well design and the geology needed to support protection of USDWs from 

endangerment. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a)(2)(i) 

Anadarko Petroleum Corporation (APC) Comments: (i) Resistivity, spontaneous 

potential, and caliper logs before the casing is installed; and 

Rationale: After a few wells are drilled in an area, these evaluations are 

frequently unnecessary and yield little new information. This is an example of 

where Director discretion may be appropriate. 

Response: As described above, EPA disagrees that the requirements for logs, surveys, and tests are 

excessive or duplicative. All logs, surveys, and tests listed at §146.87(a) are necessary to verify 

information about the injection and confining zones and ensure that the well is being drilled and cased as 

approved, and has mechanical integrity. EPA notes that the Director has the discretion at §146.87(a)(5) 

to approve alternative methods that provide equivalent or better information. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a)(2)(ii) 

Anadarko Petroleum Corporation (APC) Comments: (ii) A Cement bond and 

variable density log, and a temperature log evaluation log(s) after the casing 

is set and cemented. 

Rationale: Unusual to run these logs in a surface hole due to uniformity of 

shallow geology. This is an example of where Director discretion may be 

appropriate. 

The proposed change provides more flexibility to select the appropriate log to 

demonstrate adequate cement bond. 

Response: EPA clarifies at §146.87(a)(2)(ii) that owners or operators must perform a cement bond (i.e., 

cement evaluation) log after the casing is set and cemented. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24682

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24683

415
Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a)(3)(i) 

Anadarko Petroleum Corporation (APC) Comments: Resistivity, spontaneous 

potential, porosity, caliper, gamma ray, fracture finder logs and any other 

logs the Director requires BASED ON SITE SPECIFIC CONDITIONS AND RISK-BASED 

FACTORS for the given geology before the casing is installed; and 

Rationale: It is acceptable to specify basic logging requirements, however, 

special logs should not be specified. Any other information from the area should 

be drawn on. 

Response: EPA believes that a minimum suite of logs and tests is necessary at all Class VI wells. All 

logs, surveys, and tests listed at §146.87(a) are necessary to verify information about the injection and 

confining zones and ensure that the well is being drilled and cased as approved and has mechanical 

integrity. 

EPA notes that owners or operators will describe in their permit applications how they will construct and 

test the well, and will also submit site-specific information about the subsurface geology. The Director 

will evaluate the proposed logging activities along with site-specific geologic information to identify 

geologic data of interest. 

EPA adds that, should alternative methods be shown to provide equivalent or better information or if 

site-specific conditions and risk factors dictate that other logs are necessary, the Director has the 

discretion at §146.87(a)(5) to require further logs and tests if necessary and to approve alternative 

methods that provide equivalent or better information. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a)(3)(ii) 

Anadarko Petroleum Corporation (APC) Comments: (ii) A Cement bond and 

variable density log, and a temperature log EVALUATION LOG(S) after the casing 

is set and cemented. 

Rationale: The proposed change provides more flexibility to select the 

appropriate log to demonstrate adequate cement bond. 

Response: EPA clarifies at 146.87(a)(3)(ii) that owners or operators must perform a cement bond (i.e., 

cement evaluation) log after the casing is set and cemented. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24684

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24685

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24686

416
CFR 146.87) 

Comment: Rule Provision: 146.87(a)(4) 

Anadarko Petroleum Corporation (APC) Comments: (4) A series of tests TEST(S) 

designed to demonstrate the internal and external mechanical integrity of 

injection wells, which may include: 

(i) A pressure test with liquid or gas; 

(ii) A tracer survey DIAGNOSTIC TOOLS such as oxygen-activation logging; 

(iii) A temperature or noise log; AND 

(iv) A casing inspection log. if required by the Director; and 

Rationale: Technical and grammatical corrections 

In (iv), "if required by the Director" is unnecessary. 

Response: EPA disagrees that allowing the use of unspecified "diagnostic tools" would provide the 

same amount of information as the requirement to perform a tracer survey. The track record for tracer 

surveys in evaluating mechanical integrity has been proven over time. The Agency clarifies that a tracer 

survey is one of the mechanical integrity tests that may be required by the Director or used by the owner 

or operator. 

EPA agrees with the commenter about the wording of the casing inspection log requirement at §146.87

(a)(4) and made the suggested change to improve clarity. In the final regulation, §146.87(a)(iv) does not 

include the phrase, “if required by the Director.” 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(b) 

Anadarko Petroleum Corporation (APC) Comments: (b) The owner or operator must 

submit to the Director A REPORT DESCRIBING whole cores or sidewall cores 

REPRESENTATIVE of the injection zone and confining system and formation fluid 

samples from the injection zone(s). The Director may accept DATA from cores AND 

FLUID SAMPLES from nearby wells if the owner or operator can demonstrate that 

such DATA are representative of conditions in the wellbore. 

Rationale: The information required should be sufficient to properly describe 

the injection and confining zones. 

Response: EPA clarifies that it is not the Agency's intent that physical cores be submitted to the 

Director. In the final GS rule, EPA has revised the first sentence of §146.87(b) to read as follows: "The 

owner or operator must take whole cores or sidewall cores of the injection zone and confining system 

and formation fluid samples from the injection zone(s), and must submit to the Director a detailed report 

prepared by a log analyst that includes: well log analyses (including well logs), core analyses, and 

formation fluid sample information...." 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24687

Commenter Name: Craig R. Walters Letter ID: 0200

417
Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(c) 

Anadarko Petroleum Corporation (APC) Comments: (c) PRIOR TO INJECTION WELL 

OPERATION, the owner or operator must record the fluid FORMATION 

temperature, FORMATION FLUID pH and conductivity, and reservoir pressure and 

the static fluid level of the injection zone(s). 

Rationale: Technical corrections. Reservoir pressure and static fluid level are 

redundant parameters. 

Response: EPA disagrees that "reservoir pressure" and "static fluid level" are redundant parameters. 

Although the static fluid level is equal to the bottom hole pressure, this may not always be identical to 

the reservoir pressure. Additionally, measuring the static fluid level provides additional assurance that 

the reading is accurate (or, provides the needed information in cases where a good reading is not 

obtained). In addition, a static fluid level measurement provides information regarding the proximity to 

USDWs that need protection afforded to them. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(d) 

Anadarko Petroleum Corporation (APC) Comments: (d) At a minimum, the owner or 

operator must determine or calculate the following information concerning the 

injection and confining zone(s): 

(1) Fracture pressure; 

(2) Other physical and chemical characteristics of the injection and confining 

zones; and 

(3) Physical and chemical characteristics of the formation fluids in the 

injection zone. 

Rationale: With the exception of calculating fracture pressure, the requirements 

of this section appear redundant to other requirements of prior sections. The 

fracture pressure requirement has been added to section 146.87(e) below. 

(2) and (3) are too vague. 

Response: EPA believes that the requirement to provide information on the injection and confining 

zones in §146.87(d) is warranted, and that the rule provides flexibility to account for the variety of 

geologic conditions that may be encountered at GS sites. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24688

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24689

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24690

418
Comment: Rule Provision: 146.87(e) 

Anadarko Petroleum Corporation (APC) Comments: (e) (D) Upon completion 

but Prior to INJECTION WELL operation, the owner or operator must ESTIMATE 

FRACTURE PRESSURES OF THE INJECTION AND CONFINING ZONES AND conduct the 

following tests to verify hydrogeologic AND GEOMECHANICAL characteristics of 

the injection zone, E.G., INJECTIVITY TESTS, ESTIMATES BASED ON OPEN-HOLE 

LOGGING TOOLS (E.G. MECHANICAL PROPERTIES LOGS), AND OTHER APPROPRIATE 

METHODS. 

(1) A pump test; or 

(2) Injectivity tests. 

Rationale: Allows the use of information such as leak off tests conducted during 

the drilling operation. 

The results of a pump test (pumping fluid from the well) have no relevance for 

an injection well. 

Deletion of the injectivity test would allow the use of non-destructive methods 

to calculate fracture pressure. 

Response: EPA clarifies that the owner or operator has the option of using the pump tests or injectivity 

tests specified at §146.87(e) depending on which would provide the most valuable information based on 

site-specific conditions. Further, EPA disagrees that pump tests are irrelevant to determining injection 

zone properties. Depending on the characteristics or depth of knowledge of the confining and injection 

zone formations, pump tests may be necessary to prove that no hydraulic connection exists between the 

injection zone and a USDW. 

EPA disagrees that the wording at §146.87(d) would lead the owner or operator to employ destructive 

testing methods for determination of fracture pressure. The wording "determined or calculated" allows 

for calculations to be performed based on non-destructive methods. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(f) 

Anadarko Petroleum Corporation (APC) Comments: (f) The owner or operator must 

provide the Director with the opportunity to witness all logging and testing by 

this subpart. The owner or operator must submit a schedule of such activities to 

the Director 30 days prior to conducting the first test UPON SPUDDING THE 

WELL and submit any changes to the schedule 30 days 48 HOURS prior to the 

next scheduled test. 

Rationale: The changes reflect the realities of flexible rig schedules and 

operations. In addition, they are fully consistent with current Class II 

requirements and practices, which deal with these issues on a daily basis. 

Response: EPA disagrees that the 30-day notification requirement is unreasonable. Acknowledging the 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24691

419
developing nature of CO2 GS, EPA believes that involvement by the permitting authority in each project 

will provide much needed field data for assurance of USDW protection from endangerment and will 

help update and refine the permitting process. Adequate timing of notification will ensure the Director's 

ability to be involved. 

Other EPA Comment Codes and Descriptions: 4110 2.4.1.1 Injection pressure limitations 

Comment: Rule Provision: 146.88(a) 

Anadarko Petroleum Corporation (APC) Comments: (a) Except during stimulation, 

the owner or operator must ensure that injection pressure does not exceed 90 

percent of the fracture pressure of the injection zone so as to assure that the 

injection does not initiate new fractures or propagate existing fractures in the 

injection zone. In no case may injection pressure initiate fractures in the 

confining zone(s) or cause the movement of injection or formation fluids that 

endangers a USDW. 

(A) THE OWNER OR OPERATOR MUST COMPLY WITH A MAXIMUM INJECTION PRESSURE 

LIMIT 

APPROVED BY THE DIRECTOR AND SPECIFIED IN THE PERMIT. IN APPROVING A 

MAXIMUM 

INJECTION PRESSURE LIMIT, THE DIRECTOR SHALL CONSIDER THE RESULTS OF WELL 

TESTS. 

THE DIRECTOR SHALL APPROVE LIMITS THAT, WITH A REASONABLE DEGREE OF 

CERTAINTY, 

WILL AVOID INITIATION OR PROPAGATION OF FRACTURES IN THE CONFINING ZONE OR 

CAUSE 

OTHERWISE NONTRANSMISSIVE FAULTS TRANSECTING THE CONFINING ZONE TO 

BECOME 

TRANSMISSIVE. IN NO CASE MAY INJECTION PRESSURE CAUSE MOVEMENT OF 

INJECTION OR 

FORMATION FLUIDS IN A MANNER PROHIBITED BY 40 CFR PART 144.12(A) 

Rationale: Maintaining the integrity of the confining zone is the critical 

parameter. 

Response: EPA notes that because determination of the injection pressure limit is based on the fracture 

pressure of the injection zone, the limit is site-specific and not arbitrary. EPA emphasizes that injection 

pressure limits are important to protect against fracturing of the confining zone, and that the requirement 

at §146.88(a) that the pressure in the injection zone not exceed 90 percent of the fracture pressure 

provides a margin of safety in the well operation and protects USDWs from endangerment. If the 

Director determines, based on a review of the information collected as part of site characterization, that a 

lower injection pressure limitation is appropriate, the Director has the authority to set a lower limit in the 

operating permit than the limit established in the rule. 

EPA notes that during the site characterization process, owners or operators must submit data about the 

geology of the site, as specified at §146.82(a), including data on known or suspected faults and fractures 

and geomechanical information on fractures, stress, ductility, rock strength, and in situ fluid pressures 

within the confining zone. The Director will use these data to determine appropriate limits on injection. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24692

420
In response to the concern about reopening of faults at lower pressures than 90 percent of fracture 

pressure, EPA believes that the requirement for the owner or operator to submit data on known or 

suspected faults and fractures and information on the seismic history of the site will inform the 

determination of an appropriate pressure limitation in the permit. Any sites with the potential for 

reopening or reactivation of faults or unacceptable seismic risk that could otherwise interfere with 

containment will not be permitted as GS sites. 

EPA is developing guidance on site characterization for GS projects to assist owners or operators in 

meeting the requirements of §146.82 and to assist directors in evaluating permit applications. The 

guidance will describe recommended approaches for characterizing the regional geology and 

hydrogeology of a proposed site and performing the necessary geochemical, geomechanical, and 

geophysical analyses of the injection and confining zone. EPA is also developing guidance for primacy 

agencies that will include recommended approaches for evaluating owner or operator-submitted data in 

setting permit conditions. The guidance will be available on EPA's web site at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4100 2.4.1 Injection parameters 

Comment: Rule Provision: 146.88(b) 

Anadarko Petroleum Corporation (APC) Comments: (b) Injection OF THE CO2 STREAM 

between the outermost casing protecting USDWs and the well bore is prohibited. 

Rationale: Routine injection into zones other than the target interval(s) should 

be prohibited, however, wording of this requirement is not clear as to which 

interval is being addressed. An absolute prohibition on injection into this 

annulus may also limit diagnostic options that could be useful. 

Response: EPA retains the provision as proposed, and clarifies that injection between the casing and the 

well bore is prohibited. This is consistent with requirements for other injection well classes. 

Other EPA Comment Codes and Descriptions: 4100 2.4.1 Injection parameters 

Comment: Rule Provision: 146.88(c) 

Anadarko Petroleum Corporation (APC) Comments: (c) The owner or operator must 

fill the annulus between the tubing and the long string casing with a noncorrosive fluid approved by the Director. The owner or operator must maintain 

on the annulus a pressure that exceeds the operating injection pressure, 

unless the Director determines that such requirement might harm the integrity of 

the well. A POSITIVE PRESSURE ON THE ANNULUS. 

Rationale: Industry experience with the Class II UIC program does not support 

this requirement. 

Positive annular pressure that exceeds the operating injection pressure is not 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24693

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24694

421
necessary because a leak from tubing to annulus does not have the same 

implications as in a Class I hazardous situation. 

Response: EPA believes that maintaining an annulus pressure that is higher than the injection pressure, 

as required at §146.88(c), will ensure that if there are leaks in the tubing, the annulus fluid will move 

into the tubing, rather than the injectate moving out of the tubing and potentially along the outside of the 

well. EPA believes this requirement is appropriate for Class VI wells given the potential high volumes 

and supercritical nature of the CO2 injectate, potential geomechanical stresses in the wellbore, and the 

potential for movement of the CO2 in the event of a mechanical integrity loss. 

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells 

(seeking comment) 

Comment: Rule Provision: 146.88(e) 

Anadarko Petroleum Corporation (APC) Comments: (e) The owner or operator must 

install and use continuous recording devices to monitor: the injection pressure; 

the rate, volume, and temperature of the carbon dioxide stream and. THE 

OWNER OR OPERATOR MUST REGULARLY MONITOR the pressure on the annulus between the 

tubing and the long string casing and annulus fluid volume and. THE OWNER OR 

OPERATOR must install and use alarms and automatic down-hole shut-off 

systems, designed to alert the operator and shutin the well when operating 

parameters such as injection rate, injection pressure, or other parameters 

approved by the Director diverge beyond ranges and/or gradients specified in the 

permit; 

Rationale: Over-pressure protection is best achieved by ensuring compatibility 

of the casing/tubing material design strength with the surface injection 

(compression) system. Down-hole shut-in devices are not appropriate for this 

application. These devises are installed in the tubing string and are typically 

near the surface of the well. They’re intended to seal the tubing in the event 

of catastrophic failure of the wellhead. These devises would provide little if 

any protection to USDWs. Is not practicable to install these devises deep within 

the well (e.g. shortly above the packer). Additionally these devises create a 

restriction on running other tools like logging tools in the well and therefore 

could limit an operators ability to do required monitoring and diagnostic work. 

Lastly, these devises require periodic testing and maintenance which could 

require either pulling the devise by wireline or by pulling the entire tubing 

string depending on the type of devise installed. Either of these activities 

would be disruptive and costly to the overall project operations. 

A more appropriate approach would be installation of landing nipples at 

appropriate points in the tubing string which would allow use of wireline 

retrievable plugs when needed. 

Response: As described above, EPA will not require automatic down-hole shut-off devices for onshore 

Class VI wells since it is not necessary in all cases to ensure protection of USDWs from endangerment. 

Instead, the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells 

install automatic surface shut-off devices. The rule affords Director's discretion to mandate automatic 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24695

422
down-hole shut-off devices in onshore situations that may warrant their use. The rule requires, at 

§146.88(e)(3), that owners or operators of offshore wells within State territorial waters install automatic 

down-hole shut-off systems. Please see the final rule and preamble for additional information on EPA's 

final approach. 

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells 

(seeking comment) 

Comment: Rule Provision: 146.88(f) 

Anadarko Petroleum Corporation (APC) Comments: (f) If aN down-hole automatic 

shutdown is triggered or a loss of mechanical integrity is discovered, the owner 

or operator must immediately investigate and identify as expeditiously as 

possible the cause of the shutoff. If, upon such investigation, the well 

appears to be lacking mechanical integrity, or if monitoring required under 

paragraph (e) of this section otherwise indicates that the well may be lacking 

mechanical integrity, the owner or operator must: 

Rationale: Technical clarification given changes above. 

Response: As described above, EPA will not require automatic down-hole shut-off devices for onshore 

Class VI wells since it is not necessary in all cases to ensure protection of USDWs from endangerment. 

Instead, the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells 

install automatic surface shut-off devices. The rule affords Director's discretion to mandate automatic 

down-hole shut-off devices in onshore situations that may warrant their use. The rule requires, at 

§146.88(e)(3), that owners or operators of offshore wells within State territorial waters install automatic 

down-hole shut-off systems. Please see the final rule and preamble for additional information on EPA's 

final approach. 

Other EPA Comment Codes and Descriptions: 4000 2.4 Proposed Injection Well Operating 

Requirements (40 CFR 146.88) 

Comment: Rule Provision: 146.88(f)(3) 

Anadarko Petroleum Corporation (APC) Comments: (3) Notify the Director within 24 

hours OF DISCOVERY; 

No rationale provided 

Response: The final rule text at §146.88(f) now reads, "If a shutdown (i.e., down-hole or at the surface) 

is triggered or a loss of mechanical integrity is discovered." Therefore the notice required at §146.88(f)

(3) must be provided within 24 hours of an automatic shut-off device being triggered or a loss of 

mechanical integrity being discovered. EPA believes this provision is necessary to ensure timely 

response to potential USDW endangerment. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24696

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24697

Commenter Name: Craig R. Walters Letter ID: 0200

423
Other EPA Comment Codes and Descriptions: 4520 2.5.1 Continuous internal mechanical integrity 

monitoring (seeking comment); 4720 2.7.2 Operational recordkeeping and reporting 

Comment: Rule Provision: 146.89(b) 

Anadarko Petroleum Corporation (APC) Comments: (b) To evaluate the absence of 

significant leaks under paragraph (a)(1) of this section, owners or operators 

must, following an initial annulus pressure test, continuously monitor AND 

RECORD AT LEAST DAILY, ANNULUS PRESSURE AND VOLUMES OF PACKER FLUID 

INJECTED OR 

REMOVED FROM injection pressure, rate, injected volumes, and pressure on the 

annulus between THE tubing and long stem STRING casing and annulus fluid 

volume as specified in §146.88 (e); 

Rationale: Technical clarification. 

Response: EPA agrees with the commenter regarding the importance of demonstrating internal 

mechanical integrity (MI), but disagrees with the suggested changes. Class VI injection wells will be 

equipped with dedicated computer-based continuous pressure monitoring devices in concert with the 

shut-off systems required for GS wells, which typically take readings several times per second (i.e., 

more frequently than daily) and record them electronically in a computer system. 40 CFR §146.91(a)(2) 

requires that monthly averages of the continuous annulus monitoring be reported on a semiannual basis.

40 CFR §146.91(a)(2) requires that monthly averages of the continuous annulus monitoring be reported 

on a semiannual basis. EPA agrees with the commenter that recording annulus fluid volume may not be 

appropriate. EPA believes that annulus fluid volume (146.88(e)) is a necessary component of monitoring 

well mechanical integrity, but believes that knowing the annulus fluid volume added is sufficient to meet 

the intent of the requirement. The final GS rule requires that owners or operators use continuous 

recording devices to monitor injection pressure, rate, and volume, as well as the pressure on the annulus 

between the tubing and the long string casing. It also modifies the requirement in the proposed rule to 

continuously monitor annulus fluid volume; it now requires recording of annulus fluid volume added. 

See §§146.88(e), 146.89(b), and 146.90 (b). The final rule implements the suggested change from “longstem” to “long-string” casing. 

Other EPA Comment Codes and Descriptions: 4540 2.5.2 Proposed external MIT requirements; 4543 

2.5.2.1 MIT procedures and methods for GS (seeking comment) 

Comment: Rule Provision: 146.89(c) 

Anadarko Petroleum Corporation (APC) Comments: (c) At least once per year, the 

owner or operator must confirm the absence of significant fluid movement under 

paragraph (a)(2) of this section USING A METHOD ACCEPTABLE TO THE DIRECTOR (E.G. 

INCLUDING DIAGNOSTIC SURVEYS SUCH AS OXYGENACTIVATION LOGGING OR 

TEMPERATURE OR 

NOISE LOGS). 

(1) A tracer survey such as oxygen-activation logging; (2) A temperature or 

noise log; or (3) A casing inspection log, if required by the Director. 

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24698

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24699

424
Rationale: Revised text supports a performance-based approach and allows the 

development and use of new technologies as they become available. Cement 

circulation to the surface is not necessary because having the open annulus 

above the top of cement allows regular monitoring of annular pressure which 

could indicate leakage. 

Number 3 was deleted because it requires the tubing to be pulled at significant 

cost and risk of uncontrolled releases. 

Response: EPA believes that the MITs described in 146.89(c) of the rule (an approved tracer log or 

temperature or noise logs) are effective methods to demonstrate external MI, provide an important early 

warning of potential problems in the injection well system, and represent standard techniques that have 

been used successfully by the drilling industry and for the UIC Program for decades. The Agency notes 

that the regulations do provide the Director flexibility at §146.89(e) to approve the use of alternative 

MIT methods. 

EPA agrees that the casing inspection log is not an appropriate test to detect fluid movement behind the 

casing, but clarifies that it is appropriate for determining the presence or absence of corrosion of the 

long-string casing, and is required if the Director determines that it is necessary based on site-specific 

information. EPA has revised the final GS rule to require that the frequency of the casing inspection log 

must be specified in the approved testing and monitoring plan. See §146.89(d). 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Rule Provision: 146.90 

Anadarko Petroleum Corporation (APC) Comments: The owner or operator of a 

Class VI well must prepare, maintain, and comply with a testing and monitoring 

plan to verify that the geologic sequestration project is operating as permitted 

and is not endangering USDWs. The testing and monitoring plan must be submitted 

with the permit application, for Director approval, and must include a 

description of how the owner or operator will meet the requirements of this 

section. Testing and monitoring associated with geologic sequestration projects 

must, at a minimum, include: 

(A) BASED ON A SITE-SPECIFIC ASSESSMENT OF THE POTENTIAL FOR FLUID 

MOVEMENT FROM 

THE INJECTION WELL OR INJECTION ZONE, AND ON THE POTENTIAL VALUE OF 

MONITORING 

WELLS TO DETECT SUCH MOVEMENT, THE OWNER OR OPERATOR OF A CLASS VI WELL 

MUST 

PREPARE, MAINTAIN, AND COMPLY WITH A TESTING AND MONITORING PLAN TO 

VERIFY THAT 

THE GEOLOGIC SEQUESTRATION PROJECT IS OPERATING AS PERMITTED AND IS NOT 

ENDANGERING USDWS. THE TESTING AND MONITORING PLAN MUST BE SUBMITTED 

WITH THE 

PERMIT APPLICATION, FOR DIRECTOR APPROVAL AND INCLUDE A DESCRIPTION OF 

HOW THE 

OWNER OR OPERATOR WILL MEET THE REQUIREMENTS OF THIS SECTION; 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24700

425
No rationale provided 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

EPA anticipates that the testing and monitoring plan will address site-specific geologic factors, 

modeling, and risk-assessment. EPA is developing guidance on how best to develop the various required 

project plans, including the testing and monitoring plan. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: Rule Provision: 146.90(b) 

Anadarko Petroleum Corporation (APC) Comments: (b) The testing and monitoring 

plan must, at a minimum, include: 

(a1) Analysis of the carbon dioxide stream with sufficient frequency to 

yield data representative of its chemical and physical characteristics; 

(b2) Installation and use, except during well workovers as defined in § 

146.86(d), of continuous recording MONITORING DEVICES (INCLUDING DIGITAL 

DEVICES CAPTURING PERIODIC DATA) to monitor injection pressure, rate and volume; 

AND TO RECORD AT LEAST DAILY the pressure on the annulus between the tubing and 

the long string casing; and the annulus fluid volume; 

(3) A DEMONSTRATION OF EXTERNAL MECHANICAL INTEGRITY PURSUANT TO §146.89

(C) 

UNTIL THE WELL IS PLUGGED; 

(4) MONITORING OF THE PRESSURE BUILDUP IN THE INJECTION ZONE ANNUALLY, 

INCLUDING 

AT A MINIMUM, A SHUTDOWN OF THE WELL FOR A TIME SUFFICIENT TO CONDUCT A 

VALID 

OBSERVATION OF THE PRESSURE FALLOFF CURVE AT LEAST ONCE EVERY FIVE YEARS; 

AND 

(5) A QUALITY ASSURANCE PLAN FOR ALL TESTING AND MONITORING 

REQUIREMENTS. 

(b) Installation and use, except during well workovers as defined in §146.88(d), 

of continuous monitoring devices (including digital devices capturing periodic 

data) to monitor injection pressure, rate and volume; and RECORD AT LEAST DAILY 

the pressure on the annulus between the tubing and the long string casing; 

Rationale: §146.86(d) does not exist; perhaps §146.88(d) is what was apparently 

intended. 

There is concern regarding what constitutes continuous monitoring. Industry 

agrees that regular monitoring of the parameters identified by EPA is 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24701

426
appropriate. Our experience with CO2 EOR strongly shows that daily monitoring of 

most of these parameters is adequate (exceptions to this would be on a sitespecific basis). Recording should generally be done on a daily basis and 

reporting on a semi-annually basis. As a guiding principle, the frequency of 

monitoring should be determined by the level of risk posed by the injection 

operation. 

Response: EPA believes that continuous pressure monitoring of GS wells, as required at §146.88(e), is 

important and appropriate because the potentially corrosive nature of CO2 streams in the presence of 

water makes it critical to immediately identify corrosion-related well mechanical integrity loss. Class VI 

injection wells must be equipped with dedicated computer-based continuous pressure monitoring 

devices (in concert with the Director-approved shut-off systems required for GS wells), which typically 

take readings several times per second and record them electronically in a computer system.. 

EPA believes that a frequency of at least once every five years, as specified at §146.90(f), is an 

appropriate interval for pressure fall-off testing (particularly given the suite of tests operators will 

perform on the well and the site). EPA clarifies that the Director may require more frequent pressure 

fall-off tests at a specific project, if necessary based on site-specific circumstances. Pressure fall-off tests 

may be conducted in conjunction with other well performance tests (i.e., mechanical integrity testing) to 

ensure safe and effective operations. All monitoring data collected, including information from pressure 

fall-off tests, will be incorporated in AoR reevaluations, at least every five years. EPA disagrees that the 

rule should provide specifics of the testing at the degree suggested, however. 

EPA clarifies that periodic MITs are not be required following plugging of the well. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment, EPA has made many revisions to the GS rule. See the final rule and preamble for further 

discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4630 2.6.3 Corrosion monitoring 

Comment: Rule Provision: 146.86(c) 

Anadarko Petroleum Corporation (APC) Comments: (C) WHERE APPROPRIATE, THE 

TESTING AND MONITORING PLAN SHALL ALSO INCLUDE: 

(1) CONTINUOUS MONITORING FOR PRESSURE CHANGES IN AN APPROPRIATELY 

POROUS AND 

PERMEABLE FORMATION OVERLYING THE CONFINING ZONE. WHEN A WELL IS 

INSTALLED TO 

ENABLE SUCH MONITORING, THE OWNER OR OPERATOR SHALL, ON A SPECIFIED 

FREQUENCY OR 

AT SPECIFIED TIMES, SAMPLE THE FORMATION AND ANALYZE FOR CONSTITUENTS 

SPECIFIED 

IN THE PLAN; 

(2) THE USE OF INDIRECT, GEOPHYSICAL TECHNIQUES TO DETERMINE THE POSITION 

OF THE 

CO2 STREAM FRONT, THE WATER QUALITY IN A DESIGNATED FORMATION, OR TO 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24702

427
PROVIDE 

OTHER SITE SPECIFIC DATA; 

(3) PERIODIC MONITORING OF WATER QUALITY IN AN APPROPRIATELY POROUS AND 

PERMEABLE FORMATION OVERLYING THE INJECTION ZONE; 

(4) PERIODIC MONITORING OF WATER QUALITY IN ONE OR MORE USDWS; 

(5) CORROSION MONITORING OF THE WELL MATERIALS FOR LOSS OF MASS, 

THICKNESS, 

CRACKING, PITTING AND OTHER SIGNS OF CORROSION PERFORMED AND RECORDED 

AT LEAST 

QUARTERLY WHICH MAY BE MODIFIED TO BE LESS FREQUENT AS APPROVED BY THE 

DIRECTOR 

BASED ON CONSTRUCTION MATERIALS, OPERATING CONDITIONS, AND MONITORING 

HISTORY TO 

ENSURE THAT THE WELL COMPONENTS MEET THE MINIMUM STANDARDS FOR 

MATERIAL STRENGTH 

AND PERFORMANCE SET FORTH IN §146.86(B) BY: 

(I) ANALYZING COUPONS OF THE WELL CONSTRUCTION MATERIALS PLACED IN 

CONTACT WITH 

THE CARBON DIOXIDE STREAM; OR 

(II) ROUTING THE CARBON DIOXIDE STREAM THROUGH A LOOP CONSTRUCTED WITH 

THE 

MATERIAL USED IN THE WELL AND INSPECTING THE MATERIALS IN THE LOOP; OR 

(III) USING AN ALTERNATIVE METHOD, MATERIALS, OR TIME PERIOD APPROVED BY 

THE 

DIRECTOR; 

(6) ANY ADDITIONAL TESTING AND MONITORING APPROPRIATE TO SUPPORT 

MODELING THE 

EXTENT OF THE CARBON DIOXIDE PLUME AND THE POSITION OF THE PRESSURE 

FRONT; AND 

(7) ANY ADDITIONAL TESTING AND MONITORING NECESSARY TO DETERMINE 

WHETHER FLUID 

MOVEMENT IS OCCURRING INTO OR BETWEEN USDWS THAT WOULD ENDANGER A 

USDW. 

Rationale: Drilling monitoring wells should be carefully considered since each 

well introduces a potential pathway for movement. In addition the cost of adding 

multiple wells could create a barrier to CCS development, while providing 

limited information on actual movement of the CO2 stream. 

APC questions the need for corrosion monitoring of most injected CO2 streams 

since they will typically be nearly pure and dry thus having no corrosive 

properties. Industry experience with production, transportation, and injection 

of dry CO2 strongly illustrates the non-corrosive nature of this type of CO2 

stream. 

Response: EPA believes that quarterly corrosion monitoring of GS wells is necessary. CO2 in the 

428
presence of water (including water with NOx, SOx, and H2S impurities) can be corrosive to well 

materials and cements. Thus, although a CO2 stream may be dry, the potential for corrosion of well 

materials down-hole, where the injectate can potentially mix with water in the target formation, must be 

considered. 

Several laboratory studies and a limited number of field studies have investigated and characterized the 

effects of carbonic acid on well materials. Laboratory studies (e.g., Kutchko et al., 2007; Kutchko et al., 

2008) consistently identify alterations (typically carbonation) of cement as the result of interactions 

between cement and CO2-saturated brine. 

Currently, there are only a few analyses of cement from wells that have been in prolonged contact with 

CO2 in actual field (down-hole) conditions. Evaluation of cement from a well at the Scurry Area 

Canyon Reef Operators Committee (SACROC) site showed alteration, but did not show degradation that 

compromised the structural integrity of the cement (Carey et al., 2007). In another study, cement 

samples were collected and analyzed from a CO2 production well in a natural CO2 reservoir in 

Colorado exposed to a CO2-water down-hole environment for 30 years (Crow et al., 2008). The study 

found evidence of reaction between the CO2-rich water and the cement. 

Oil industry research also addresses the effects of corrosion of steel tubing and pipes. Lopez et al. (2003) 

noted that 60 percent of oilfield failures are related to the effects of carbonic acid from produced brines 

on carbon and low alloy steels. 

Laboratory investigation of cement alteration/degradation is an ongoing research area. Few field-based 

studies have been completed to date. The laboratory and field studies currently available suggest that 

corrosion problems can be managed; however, there is not a large enough body of research to rule out 

potential corrosion problems of steel components of injection wells. The IPCC (2005) report on carbon 

dioxide capture and storage reviewed oil and gas industry experience with gas injection wells, close 

industry analogues to CO2 injection wells. The report stated that while the design of CO2 injection wells 

will be very similar to gas injection wells, most down-hole components of the CO2 injection wells will 

“need to be upgraded for higher pressure ratings and corrosion resistance.” Given the pressure and 

corrosion considerations, anticipated long lifespan of a GS well and the difficulties that would be 

associated with a corrosion-related well failure, EPA believes that corrosion monitoring in the downhole environment is justified. For these reasons, the final rule requires quarterly corrosion monitoring at 

§146.90(c). 

EPA maintains that plume tracking and pressure monitoring are key components of monitoring at GS 

sites. A rigorous plume tracking and pressure monitoring scheme, such as one that meets the 

requirements at §146.90(g), is imperative for ensuring that the CO2 plume is contained within the 

injection zone. Pressure monitoring in the injection zone is necessary to track the development and 

movement of the pressure front and CO2 plume. When combined with information on temperature, 

pressure data provide an indication of the phase (e.g., gas, supercritical) and distribution of the injected 

CO2. Monitoring can also identify needed remedial actions, provide inputs for AoR reevaluation 

modeling, evaluate predictions of plume movement, and target additional geochemical and surface 

monitoring needs. 

EPA also believes that the ground water geochemical monitoring outlined in §146.90(d) will maximize 

protection of USDWs from endangerment at GS sites. Direct geochemical sampling is an important part 

of a monitoring program. See the final rule and preamble for further discussion on EPA's final approach. 

Commenter Name: Craig R. Walters Letter ID: 0200

429
Other EPA Comment Codes and Descriptions: 4630 2.6.3 Corrosion monitoring 

Comment: Rule Provision: 146.90(c) 

Anadarko Petroleum Corporation (APC) Comments: (c) Corrosion monitoring of the 

well materials for loss of mass, thickness, cracking, pitting and other signs of 

corrosion must be performed on a quarterly basis to ensure that the well 

components meet the minimum standards for material strength and performance set 

forth in § 146.86(b) by: 

(1) Placing coupons of the well construction materials in contact with the 

carbon dioxide stream; or 

(2) Routing the carbon dioxide stream through a loop constructed with the 

material used in the well; or 

(3) Using an alternative method approved by the Director; 

Rationale: See 146.90(5)(i-iii) 

Response: EPA believes that corrosion monitoring is necessary for all Class VI wells to prevent 

endangerment of USDWs. CO2 in the presence of water (including water with NOx, SOx, and H2S 

impurities) can be corrosive to well materials and cements. Thus, although a CO2 stream may be dry, 

the potential for corrosion of well materials down-hole, where the injectate can potentially mix with 

water in the target formation, must be considered. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment, EPA has made many revisions to the GS rule. See the final rule and preamble for further 

discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4660 2.6.6 Geochemical monitoring 

Comment: Rule Provision: 146.90(d) 

Anadarko Petroleum Corporation (APC) Comments: (d) Periodic monitoring of the 

ground water quality and geochemical changes above the confining zone(s) that 

may be a result of carbon dioxide movement through the confining zone or 

additional identified zones: 

(1) The location and number of monitoring wells must be based on specific 

information about the geologic sequestration project, including injection rate 

and volume, geology, the presence of artificial penetrations and other factors; 

(2) The monitoring frequency and spatial distribution of monitoring wells must 

be based on baseline geochemical data that has been collected under § 146.82(a) 

(6) and any modeling results in the area of review evaluation required by § 

146.84(b); 

Rationale: See 146.90(c)(1 thru 4 and 7) 

Response: EPA did not make the suggested changes, but agrees that monitoring plans and methods need 

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24703

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24704

430
to be site-specific and based on baseline data and data collected throughout operations. EPA believes 

that the monitoring requirements for GS sites at §146.90 provide an appropriate level of flexibility in 

structuring a testing and monitoring plan that protects USDWs from endangerment. 

The final regulation provides for flexibility in: 1) methodologies used to collect these data, 2) the spatial 

resolution at which the data should be collected, and 3) how often the data should be collected. The 

number and placement of monitoring wells will be based on site-specific information such as the 

calculated AoR, injection rate and volume, site geology, baseline data, and the presence of artificial 

penetrations within the AoR. In some instances, there may be a limited number of options for complying 

with EPA's minimum requirements. For example, monitoring for geochemical changes will require use 

of monitoring wells and collection of groundwater samples for chemical analysis. Many options 

currently exist for complying with other requirements, such as tracking the position of the plume and 

pressure front within the injection zone. 

Flexibility is also provided regarding how to monitor for the specific data required by the final rule. The 

testing and monitoring plan is developed by the owner or operator in consultation with the Director and 

is designed to ensure that a detailed, Director-approved document describing how monitoring will be 

conducted during the lifetime of the project exists. EPA is developing guidance on testing and 

monitoring to assist owners or operators and Directors in evaluating requirements under §146.90, 

including proposed monitoring plans. The guidance describes available technologies and recommended 

approaches for implementing a testing and monitoring plan, including pre-operational geophysical 

logging and testing of injection wells, MITs, injection well testing during operation, groundwater quality 

monitoring, tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which 

may be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: Rule Provision: 146.90(e) 

Anadarko Petroleum Corporation (APC) Comments: (e) A demonstration of external 

mechanical integrity pursuant to § 146.89(c) at least once per year throughout 

the duration of the geologic sequestration project; 

Rationale: See 146.90(b)(3) 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS rule. See the final rule and 

preamble for further discussion on EPA's final approach. EPA adds that the purpose of including all 

testing and monitoring requirements in §146.90 is to clarify and to specify the content of the required 

testing and monitoring plan. 

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: Rule Provision: 146.90(f) 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24705

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24706

431
Anadarko Petroleum Corporation (APC) Comments: (f) A pressure fall-off test at 

least once every five years unless more frequent testing is required by the 

Director based on site specific information; 

Rationale: See 146.90(b)(4) 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS rule. See the final rule and 

preamble for further discussion on EPA's final approach. EPA adds that the purpose of including all 

testing and monitoring requirements in §146.90 is to clarify and to specify the content of the required 

testing and monitoring plan. 

Other EPA Comment Codes and Descriptions: 4650 2.6.5 CO2 plume and pressure front tracking 

(seeking comment) 

Comment: Rule Provision: 146.90(g) 

Anadarko Petroleum Corporation (APC) Comments: (g) Testing and monitoring to 

track the extent of the carbon dioxide plume and the position of the pressure 

front by either monitoring for pressure changes in the first formation overlying 

the confining zone or using indirect, geophysical techniques (e.g., seismic, 

electrical, gravity, or electromagnetic surveys and/or down-hole carbon dioxide 

detection tools); 

Rationale: See 146.90(c)(1 thru 4 and 7) 

Monitoring outside of the injection zone provides little information of value 

for tracking and monitoring the injected plume. Examples of how to test and 

monitor could be included in the Preamble but need not be included in the rule 

itself. 

Response: EPA believes that direct pressure measurements are appropriate and the final rule (at §146.90

(g)) requires owners or operators to perform monitoring to track the extent of the CO2 plume and 

pressure front. The owner or operator must use direct methods to monitor for pressure changes in the 

injection zone. Indirect methods (e.g., seismic, electrical, gravity, or electromagnetic surveys and/or 

down-hole CO2 detection tools) are also required unless the Director determines, based on site-specific 

geology, that such methods are not appropriate. 

EPA believes that pressure monitoring in the injection zone is necessary to track the development and 

movement of the pressure front and CO2 plume. Monitoring can also identify needed remedial actions, 

provide inputs for AoR reevaluation modeling, evaluate predictions of plume movement, and target 

additional geochemical and surface monitoring needs. Knowledge of the location of the CO2 plume and 

the associated pressure front will assure the public that GS projects are proceeding according to plan, 

provide sufficient information to the owner or operator and Director, or allow for appropriate actions to 

address any indication that USDWs may be endangered. 

EPA acknowledges that, at certain sites, there may be a need for more or different monitoring schemes 

(which may include monitoring in the confining zone), and adds that it is important to balance the need 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24707

432
for adequate monitoring that ensures USDW protection from endangerment against too many artificial 

penetrations which could serve as conduits for fluid migration. Site-specific testing and monitoring plans 

should describe the proposed monitoring regime, which must be approved by the Director. 

Flexibility is also provided regarding how to monitor for the specific data required by the final rule. The 

testing and monitoring plan is developed by the owner or operator in consultation with the Director and 

is designed to ensure that a detailed, Director-approved document describing how monitoring will be 

conducted during the lifetime of the project exists. 

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in 

evaluating requirements under §146.90, which will include discussion of identifying the extent of the 

CO2 plume and pressure front. The guidance describes available technologies and recommended 

approaches for implementing a testing and monitoring plan, including pre-operational geophysical 

logging and testing of injection wells, MITs, injection well testing during operation, groundwater quality 

monitoring, tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which 

may be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. In addition, in January 

2009, DOE published a best practices manual entitled "Monitoring, Verification, and Accounting of 

CO2 Stored in Deep Geologic Formations" (DOE/NETL-311/081508); this manual is included in the 

docket for the final GS rule. 

Other EPA Comment Codes and Descriptions: 4670 2.6.7 Surface air monitoring and/or soil gas 

monitoring (seeking comment) 

Comment: Rule Provision: 146.90(h) 

Anadarko Petroleum Corporation (APC) Comments: (h) At the Director’s 

discretion, surface air monitoring and/or soil gas monitoring to detect movement 

of carbon dioxide that could endanger a USDW. 

(1) The testing and monitoring plan must be based on potential vulnerabilities 

within the area of review; 

(2) The monitoring frequency and spatial distribution of surface air monitoring 

and/or soil gas monitoring must reflect baseline data and the monitoring plan 

must include how the proposed monitoring will yield useful information on the 

area of review delineation and/or compliance with standards under 40 CFR 

144.12; 

Rationale: In most situations soil and air monitoring does not provide an 

effective method of protecting USDWs. 

Response: As described above, EPA acknowledges that air and soil gas monitoring to ensure USDW 

protection is not necessary at all GS sites and agrees that the decision to use surface monitoring and the 

selection of monitoring methods for the purpose of USDW protection will be site-specific. 

In the final rule, at §146.90(h), the decision to require such monitoring as an additional measure to 

ensure USDW protection rests with the Director as a means of identifying leaks that may pose a risk to 

USDWs and informing emergency notification of a Class VI owner or operator and UIC Director in the 

event of a USDW endangerment, pursuant to requirements at §146.91(c).

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24708

433
The Agency agrees with the commenter that, if air and soil gas monitoring is performed, baseline soil 

CO2 levels need to be determined before monitoring. This would be considered and described in the 

site-specific testing and monitoring plan. 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Rule Provision: 146.90(i) 

Anadarko Petroleum Corporation (APC) Comments: (i) Any additional monitoring, 

as required by the Director, necessary to support, upgrade, and improve 

computational modeling of the area of review evaluation required under § 

146.84(b) and to determine compliance with standards under 40 CFR 144.12; and 

Rationale: See 146.90(c)(6) 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Rule Provision: 146.90(j) 

Anadarko Petroleum Corporation (APC) Comments: (j) A quality assurance and 

surveillance plan for all testing and monitoring requirements. 

Rationale: See 146.90(b)(5) 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4720 2.7.2 Operational recordkeeping and reporting 

Comment: Rule Provision: 146.91(a) 

Anadarko Petroleum Corporation (APC) Comments: (a) Semi-annual OR LESS FREQUENT 

AT THE DISCRETION OF THE DIRECTOR reports containing: 

(1) Any SIGNIFICANT changes to the physical, chemical and other relevant 

characteristics of the carbon dioxide stream from the proposed operating data; 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24709

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24710

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24711

434
Rationale: Over the life of the project, the Director may decide that less 

reporting is acceptable 

(1) Technical clarification. Significance can be determined by a statistical 

analysis of the data. Rules should recognize that there will be minor variations 

in many data sets over time. 

Response: EPA retained this provision as proposed. The final rule at §146.91(a)(3) requires reporting of 

all exceedances of operating parameters. EPA disagrees with the suggestion to report only "significant" 

exceedances. Making a determination as to whether an exceedance is "significant" is not the purpose of 

the requirement. EPA believes that the ability of an operator to consistently meet operating requirements 

and avoid exceedances provides evidence of a well-managed GS project that is in compliance with the 

Class VI permit. If multiple exceedances occur, the Director should be aware of such occurrences, and 

that information will aid in his/her determination of whether these indicate problems at the site, and 

what is the appropriate course of action (e.g., a well workover, modification of operating parameters, or 

imposition of a penalty) to remediate such problem(s). 

Other EPA Comment Codes and Descriptions: 4720 2.7.2 Operational recordkeeping and reporting 

Comment: Rule Provision: 146.91(3) & (4) 

Anadarko Petroleum Corporation (APC) Comments: (3) A description of any 

SIGNIFICANT event that exceeds operating parameters for annulus pressure or 

injection pressure as specified in the permit; 

(4) A description of any SIGNIFICANT event which triggers a shutdown device 

required pursuant to §146.88(e) and the response taken; 

Rationale: EPA should consider some significance threshold on reporting these 

events to avoid reporting events that would be of limited interest or 

consequence. 

Response: EPA retained this provision as proposed. The final rule at §146.91(a)(3) requires reporting of 

all exceedances of operating parameters. EPA disagrees with the suggestion to report only "significant" 

exceedances. Making a determination as to whether an exceedance is "significant" is not the purpose of 

the requirement. EPA believes that the ability of an operator to consistently meet operating requirements 

and avoid exceedances provides evidence of a well-managed GS project that is in compliance with the 

Class VI permit. If multiple exceedances occur, the Director should be aware of such occurrences, and 

that information will aid in his/her determination of whether these indicate problems at the site, and 

what is the appropriate course of action (e.g., a well workover, modification of operating parameters, or 

imposition of a penalty) to remediate such problem(s). 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: Rule Provision: 146.92(a) 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24712

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24713

435
Anadarko Petroleum Corporation (APC) Comments: (a) Prior to the well plugging, 

the owner or operator must flush each Class VI injection well with a buffer 

fluid, determine bottomhole reservoir pressure, and perform a final EXTERNAL 

mechanical integrity test OF ANY RELEVANT WELLBORE MATERIALS REMAINING. 

Rationale: Many of the components that would be tested by an internal MIT are 

removed or tested during the plugging process. 

Response: EPA agrees that only an external MIT is required, and has modified the GS rule at §146.92

(a) to require owners or operators to perform a final external mechanical integrity test prior to the well 

plugging. 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: Rule Provision: 146.92(b)(2) 

Anadarko Petroleum Corporation (APC) Comments: (2) Appropriate testing methods 

to ensure FINAL EXTERNAL mechanical integrity as specified in §146.89(C); ... 

(5) The type and grade and quantity of material to be used in plugging. The 

material must be SUITABLE FOR USE with the carbon dioxide stream; and 

Rationale: Many of the components that would be tested by an internal MIT are 

removed or tested during the plugging process. 

Response: Regarding the suggested edit at 146.92(b)(2), EPA agrees that only an external MIT is 

required, and has modified the GS rule at §146.92(a) to require owners or operators to perform a final 

external mechanical integrity test prior to the well plugging. 

Regarding the edit at 146.92(b)(5), EPA believes, considering the potentially corrosive nature of CO2 

when it is in contact with water, that the requirement that the material must be compatible with the CO2 

stream is appropriate. The final rule retains this requirement. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 

146.92) 

Comment: Rule Provision: 146.92(d) 

Anadarko Petroleum Corporation (APC) Comments: (d) Plugging report. Within 60 

days after plugging the owner or operator must submit a plugging report to the 

Director. If the semi-annual report is due less than 15 days after completion 

of plugging, then the report must be submitted within 60 days after plugging. 

The report must be certified as accurate by the owner or operator and by the 

person who performed the plugging operation (if other than the owner or 

operator.) 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24714

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24715

436
Rationale: The proposed changes are suggested to simplify and clarify a 

provision that APC believes is needlessly complicated. 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads, "Within 

60 days after plugging the owner or operator must submit a plugging report to the Director." 

Other EPA Comment Codes and Descriptions: 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Rule Provision: 146.93(a)(1) 

Anadarko Petroleum Corporation (APC) Comments: (1) The owner or operator must 

submit the postinjection site care and site closure plan as a part of the permit 

application to be approved by the Director. SHALL CONTINUE TO CONDUCT 

MONITORING AS SPECIFIED IN THE DIRECTOR-APPROVED POST-INJECTION SITE CARE 

AND 

SITE CLOSURE PLAN, PURSUANT TO THE PERFORMANCE BASED CRITERIA DESCRIBED 

IN 

146.93(3). 

Rationale: Revisions here reflect changes to §146.93(b)(3) 

Response: EPA disagrees with the suggested changes, and disagrees that the post-injection monitoring 

period should be strictly performance-based. The Agency agrees that there will be limited circumstances 

where it can be demonstrated in less than 50 years that the plume and pressure front no longer pose a 

risk of endangerment to USDWs. 

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC 

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the 

post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording 

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the permitting 

process based on substantial data, that an alternative PISC timeframe may be appropriate if it ensures 

non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for 

post-injection site care will be necessary in most cases. The default 50 year post-injection site care 

timeframe represents a reasonable and protective monitoring period based on a review of research 

studies, industry reports, and existing environmental programs, and evaluation of public comments. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

The GS rule requires owners or operators to submit a post-injection site care and site closure plan as part 

of the permit application, as specified in §146.82(a), in order to outline how these activities will be 

performed and how non-endangerment of USDWs will be demonstrated throughout the post-injection 

site care period. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24716

437
Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: Rule Provision: 146.93(a)(2) 

Anadarko Petroleum Corporation (APC) Comments: (2) The post-injection site 

care and site closure plan must include the following information: 

(i) The pressure differential between preinjection and predicted post-injection 

pressures in the injection zone; 

(ii) The predicted position of the carbon dioxide plume and associated pressure 

front at site closure as demonstrated in the area of review evaluation required 

under § 146.84(b); 

(iii) A description of post-injection monitoring location, methods, and proposed 

frequency; and 

(iv) A proposed schedule for submitting post-injection site care monitoring 

results to the Director. 

Rationale: Revisions here reflect changes to §146.93(b)(3) 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Comment: Rule Provision: 146.93(a)(4) 

Anadarko Petroleum Corporation (APC) Comments: (4) AT ANY TIME DURING THE POSTINJECTION SITE CARE PHASE, The owner or operator may modify and resubmit the 

post-injection site care and site closure plan for the Director’s approval 

within 30 days of such change. 

Rationale: Technical Clarification. 

Response: EPA agrees that a post-injection site care monitoring plan is an important tool for GS and 

anticipates that, in some cases, the appropriate post-injection monitoring strategy may end up being 

different than initially projected and there may be a need to amend the post-injection site care and site 

closure plan. EPA is requiring that upon the cessation of injection, the owner or operator submit an 

amended post-injection site care and site closure plan or demonstrate to the Director that no changes to 

the original post-injection site care and site closure plan are necessary (146.93(a)(3)). EPA is not 

requiring formal periodic review and updates to the PISC and site closure plan throughout the injection 

phase. EPA does not expect that changes to this plan would be implemented until injection operations 

cease. EPA envisions that owners or operators would take into account similar considerations that guide 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24717

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24718

438
updates to other project plans, e.g., monitoring and operational data and results of AoR reevaluations. 

EPA adds that, if any monitoring or other site data indicate a need for amending the post-injection site 

care plan, the owner or operator is expected to amend the plan accordingly. EPA is issuing guidance 

with recommended approaches for development and updating of the GS project plans, including the 

post-injection site care and site closure plan. The guidance will be available on EPA's web site at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA adds that, in the final rule, it has revised the text at §146.93(a)(4) as follows: "At any time during 

the life of the geologic sequestration project, the owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval within 30 days of such change." 

Other EPA Comment Codes and Descriptions: 5220 2.8.2.1 Post-injection monitoring activities; 

5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(1) 

Anadarko Petroleum Corporation (APC) Comments: (1) The owner or operator shall 

continue to conduct monitoring as specified in the Director-approved postinjection site care and site closure plan, for at least 50 years following the 

cessation of injection. At the Director’s discretion, the monitoring will 

continue until the geologic sequestration project no longer poses an 

endangerment to USDWs. PURSUANT TO THE PERFORMANCE BASED CRITERIA DESCRIBED 

IN 

§146.93(B)(3). 

Rationale: EPA should also reconsider its proposed 50- year default period for 

post-injection site care. EPA offers no rationale for this arbitrarily selected 

period of 50 years. Establishing a fixed and unusually long time period may 

create a significant barrier for operators considering entry into CCS 

operations. Criteria for determining the period for postinjection site care 

should be performance based and a function of the site specific characteristics 

of a project such as project size, geologic factors, and relative risk of the 

project. APC offers such criteria in our edits to §146.93(b)(3). 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most cases 

or arbitrary. EPA proposed a default post-injection site care timeframe of 50 years based on a review of 

research studies, industry reports, and existing environmental programs. This analysis was included in 

an EPA-prepared background document that is available in the federal docket, titled "Computational 

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and 

Potential Risk to Underground Sources of Drinking Water." EPA assessed various default timeframes 

based on additional review of research studies and evaluation of public comments. While numerous 

commenters suggested that EPA shorten the monitoring timeframe, none of the commenters provided 

sufficient data or other evidence to warrant a change in the proposed timeframe. While the 10- or 30-

year timeframe suggested by some of these commenters may be within the timeframe suggested in some 

studies, EPA believes that the potential risks of endangering USDWs will likely not decline within these 

timeframes and available data, including data submitted by commenters, do not support a different 

default timeframe. However, EPA recognizes that alternative timeframes may be appropriate under 

limited, specific circumstances. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24719

439
For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC 

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the 

post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording 

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the permitting 

process based on substantial data, that an alternative PISC timeframe may be appropriate if it ensures 

non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for 

post-injection site care will be necessary in all but a limited number of cases. This default 50 year postinjection site care timeframe represents a reasonable and protective monitoring period based on a review 

of research studies, industry reports, and existing environmental programs, and evaluation of public 

comments. 

EPA adds that the purpose of the GS rule is not to incentivize the use of GS. Rather, the purpose of the 

GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs from 

endangerment. 

Other EPA Comment Codes and Descriptions: 5220 2.8.2.1 Post-injection monitoring activities; 

5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(2) 

Anadarko Petroleum Corporation (APC) Comments: (2) If the owner or operator can 

request and demonstrate to the satisfaction of the Director before 50 years, 

based on monitoring and other site-specific data, that the geologic 

sequestration project no longer poses an endangerment to USDWs, the Director may 

approve an amendment to THAT the post-injection site care and site closure 

plan SHOULD BE REVISED to reduce the frequency of monitoring. or may authorize 

site closure before the end of the 50-year period. 

Rationale: (See above) 

Response: As described above, EPA disagrees that a post-injection site care timeframe of 50 years is 

excessive in most cases or arbitrary, and retains the default 50-year post-injection site care timeframe in 

the final rule. 

Other EPA Comment Codes and Descriptions: 5280 2.8.2.4 USDW non-endangerment 

demonstrations 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24720

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24721

440
Comment: Rule Provision: 146.93(b)(3) 

Anadarko Petroleum Corporation (APC) Comments: (3) Prior to authorization for 

site closure, the owner or operator must submit to the Director a 

demonstration, DEMONSTRATE TO THE DIRECTOR, based on monitoring, and other 

site-specific data, AND MODELING THAT IS REASONABLY CONSISTENT WITH SITE 

PERFORMANCE that the carbon dioxide plume and pressure front have stabilized 

and that no additional monitoring is needed to assure that the geologic 

sequestration project does not pose an endangerment to USDWs. 

THE OWNER OR OPERATOR MUST DEMONSTRATE, BASED ON THE CURRENT 

UNDERSTANDING OF 

THE SITE, INCLUDING MONITORING DATA AND/OR MODELING, ALL OF THE 

FOLLOWING: (I) 

THE ESTIMATED MAGNITUDE AND EXTENT OF THE PROJECT FOOTPRINT (CO2 PLUME 

AND THE 

AREA OF ELEVATED PRESSURE); (II) THE ESTIMATED LOCATION OF THE DETECTABLE 

CO2 

PLUME ; (III) THAT THERE IS NO SIGNIFICANT LEAKAGE OF EITHER CO2 OR DISPLACED 

FORMATION FLUIDS THAT IS ENDANGERING USDWS; (IV) THAT THE INJECTED OR 

DISPLACED 

FLUIDS ARE NOT EXPECTED TO MIGRATE IN THE FUTURE IN A MANNER THAT 

ENCOUNTERS A 

POTENTIAL LEAKAGE PATHWAY INTO A USDW; (V) THAT THE INJECTION WELLS AT 

THE SITE 

COMPLETED INTO OR THROUGH THE INJECTION ZONE OR CONFINING ZONE ARE 

PLUGGED AND 

ABANDONED IN ACCORDANCE WITH THESE REQUIREMENTS; AND (VI) ANY 

REMAINING PROJECT 

MONITORING WELLS AT THE SITE ARE BEING MANAGED BY A PERSON AND IN A 

MANNER 

ACCEPTABLE TO THE DIRECTOR. 

Rationale: APC edits establish the performance based criteria for selecting the 

monitoring period. 

EPA should recognize that under any given set of site specific conditions some 

of these criteria may not be fully satisfied. EPA should retain the ability to 

waive individual monitoring criteria described here to reflect that situation. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring timeframe. 

Instead, EPA believes that such determinations are site-specific and should be described in a projectspecific post-injection site care and site closure plan. EPA also believes that periodic reviews and 

updates, where necessary, to the plan are important to ensuring that the site continues to be managed 

effectively and to determine whether shortening the monitoring timeframe is appropriate. The postinjection site care requirements in the final GS rule incorporate a combination of a fixed timeframe and 

a performance standard approach. The final GS rule offer owners or operators flexibility regarding the 

duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC 

timeframe during the post-injection period based on site-specific data, pursuant to requirements at 

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to 

demonstrate, during the permitting process based on substantial data, that an alternative PISC timeframe 

441
may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will assist 

Directors in evaluating proposed well plugging plans and post-injection site care and site closure plans 

under §146.92 and §146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells, perform post-injection monitoring, demonstrate the 

appropriateness of an alternative post-injection site care time frame, demonstrate non-endangerment, 

and perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment); 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(4) 

Anadarko Petroleum Corporation (APC) Comments: (4) If such a demonstration 

cannot be made (i.e., if the carbon dioxide plume and pressure front have not 

stabilized) after the 50-year period, the owner or operator must submit to the 

Director a plan to continue post-injection site care. 

Rationale: No longer necessary given changes above. 

Response: As described above, EPA disagrees that a post-injection site care timeframe of 50 years is 

excessive in most cases or arbitrary, and retains the default 50-year post-injection site care timeframe in 

the final rule. . 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Rule Provision: 146.93(e) 

Anadarko Petroleum Corporation (APC) Comments: (e) Once the Director has 

authorized site closure, the owner or operator must submit a site closure report 

within 90 days that must thereafter be retained at a location designated by 

the Director. AFTER COMPLETION OF ALL CLOSURE OPERATIONS. The report must 

include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24722

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24723

442
zoning authority designated by the Director. The plat must indicate the location 

of the injection well(S) relative to permanently surveyed benchmarks. The owner 

or operator must also submit a copy of the plat to the Regional Administrator of 

the appropriate EPA Regional Office; 

Rationale: Once the site closure report is submitted to the Director, the 

operator cease to bear responsibility for any further record retention. At this 

point, EPA becomes the steward of information for the project. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention such 

as site closure reports. EPA believes that the requirements that the owner or operator retain for ten years 

following site closure, records collected during the post-injection site care period at §146.93(f) and 

§146.93(h) are appropriate for the post-injection and site closure period to ensure that data are available 

to support non-endangerment demonstrations and to address any concerns that may arise following site 

closure. This data will also support EPA's review of project data as part of the adaptive rulemaking 

approach. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: Rule Provision: 146.94(b) 

Anadarko Petroleum Corporation (APC) Comments: (b) If the owner or operator 

obtains evidence that the injected carbon dioxide stream, DISPLACED FORMATION 

FLUIDS OR and associated pressure front may cause an endangerment to 

ENDANGERS a USDW, the owner or operator must: 

(1) Immediately cease injection IN A PRUDENT MANNER CONSIDERING 

CIRCUMSTANCES. 

(2) Take all steps reasonably necessary to identify and characterize THE 

ENDANGERMENT POSED; 

(3) Notify the Director or the designated representative within 24 hours OF 

BECOMING AWARE OF THE ENDANGERMENT; and 

Rationale: Technical clarifications. 

There is a slight change that immediately ceasing injection could have adverse 

impacts on other aspects of the operation. 

Response: After consideration of comments, EPA has finalized the rule language in §146.94(b) as 

proposed. In the introductory section of §146.94(b), EPA clarifies that the pressure front, as defined in 

§146.81, is a zone where the pressure differential is sufficient to cause the movement of injected fluids 

or formation fluids into a USDW. Therefore, displaced formation fluids are implicitly included in the 

requirements for §146.94. EPA also clarifies that owners or operators must take action when the CO2 

stream or pressure front may cause endangerment. In order to prevent the endangerment of USDWs, as 

required under §1421 of the SDWA, EPA expects the owner or operator to act preemptively and not 

wait until endangerment has occurred. This language is consistent with existing UIC requirements for 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24724

443
other well classes and EPA’s authority under the SDWA.

EPA clarifies that the Agency expects that owners or operators should take care not to damage the well 

when ceasing injection under §146.94(b)(1). At §146.94(b)(2), EPA is maintaining the requirement to 

“characterize the release.” In order to prevent the endangerment of USDWs, as required under §1421 of 

the SDWA, EPA expects the owner or operator to act preemptively and not wait until endangerment has 

occurred. This language is consistent with existing UIC requirements for other well classes and EPA’s 

authority under the SDWA. 

In response to commenters’ suggestions regarding §146.94(b)(3), EPA clarifies that the 24 hours begins 

when the owner or operator obtains evidence of possible endangerment. EPA believes the rule language 

is clear on this requirement. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: Rule Provision: 146.94(d) 

Anadarko Petroleum Corporation (APC) Comments: (d) The owner or operator must 

notify the Director prior to conducting any well workover IN RESPONSE TO ANY 

CASE OF ENDANGERMENT. 

Rationale: In critical situations, time spent obtaining approval could adversely 

affect the ability to conduct operations or increase the level of endangerment. 

Response: Since proposal, EPA has modified the final regulatory language at §146.94(d) to clarify what 

constitutes a workover to address a well failure (which invokes remedial actions) and what constitutes a 

maintenance-type workover. For maintenance-type workovers (i.e., those that are scheduled in advance), 

the owner or operator must notify and gain approval from the Director prior to beginning the workover. 

In the final GS regulation, EPA has moved this requirement to the reporting requirements at §146.91(d) 

to clarify its intent. 

Regarding concerns that notification could delay responses, EPA clarifies that the GS rule (at §146.94

(b)) describes procedures owners or operators must take in emergency situations. Specifically, upon 

determining that there is a problem with the well that may endanger a USDW, the owner or operator 

must first cease injection, then take all steps reasonably necessary to identify and characterize any 

release, notify the Director, and implement the approved emergency and remedial response plan, which 

may include a well workover. EPA believes that ceasing injection (which the owner or operator would 

do immediately and before notifying the Director) is the immediate action necessary to prevent or 

mitigate endangerment of USDWs, as required under the SDWA. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82) 

Comment: 1. EPA Proposed: §146.82 (f) Maps and stratigraphic cross sections 

indicating the general vertical and lateral limits of all USDWs, water 

wells and springs within the area of review, their positions relative to 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24725

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24289

444
the injection zone(s) and the direction of water movement, where known; 

So long as the Applicant proposes to inject CO2 below the lowermost USDW, as 

proposed under the rule, there is no justification to require maps and 

stratigraphic cross sections for the entire extent of those USDWs above the 

lowermost USDW, although mapping and stratigraphic cross sections in the 

immediate vicinity of the proposed injection locations (e.g. where the injection 

wells will be drilled) should still be required. Data regarding all USDWs in the 

AoR will likely be costly and/or difficult to collect and, except as noted 

above, the usefulness of those data seems questionable. 

Accordingly, Denbury suggests that subparagraph (f) should be modified as 

follows: 

(f) Maps and stratigraphic cross sections indicating the general 

vertical and lateral limits of all THE LOWERMOST USDWs, 

ALL USDWS IN THE IMMEDIATE VICINITY OF THE PROPOSED INJECTION WELL(S), 

water wells and springs within the area of review, their positions 

relative to the injection zone(s) and the direction of water movement, 

where known; 

Response: EPA disagrees with the commenter that there is no justification to require maps and 

stratigraphic cross sections for the entire extent of those USDWs above the lowermost USDW. EPA 

believes that a thorough understanding of the hydrogeologic conditions of all USDWs in the AoR is 

necessary. EPA clarifies that §146.82(a)(5) requires, as part of the site characterization and permit 

application process, that operators submit maps and cross sections indicating the general vertical and 

lateral limits of all USDWs within the area of review. This information will result in information on and 

a characterization of the number, location, and depth of USDWs. The Director has the authority to 

request additional hydrogeologic data or other data on USDWs as well. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82) 

Comment: 2. EPA Proposed : §146.82(l) The results of the formation testing 

program as required in paragraph (j) of this section; (r) All available 

logging and testing program data on the well required by§ 146.87; (s) A 

demonstration of mechanical integrity pursuant to § 146.89; 

The requirements of subparts (l), (r) and (s) of § 146.82 cannot be met until 

after the well is drilled. For example, subparagraph (l) references (j), 

formation testing. Clearly formation testing is a drilling or post completion 

operation. Similarly, logging and mechanical integrity testing also are drilling 

or post well completion operations. Because this information will be collected 

post application approval, it should not be required prior to the granting of 

the Class VI permit. 

Denbury suggests that EPA modify § 146.82 to eliminate subparts (l), (r) and (s) 

because those data do not belong in and in fact may not be available as part of 

a permit application. 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24290

445
Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be 

available at the time the owner or operator develops their initial permit application. In response to 

comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this 

subpart so that the final regulation specifies separate requirements for information to be submitted with 

the permit application and before well construction is approved (at §146.82(a)) and information to be 

submitted before operation of the well is authorized (at §146.82(c)). 

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of 

information to be submitted. In addition, section §146.82 in the final rule is similar to the permit 

application requirements for other injection well classes, which could help avoid confusion about how to 

meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to 

be submitted before operation of the well is authorized are very similar to those for Class I wells, with 

modifications and additions that address the unique challenges and types of data collected for GS wells.

Other EPA Comment Codes and Descriptions: 3330 2.2.1.3 Applicability /adequacy of 

computational models (seeking comment) 

Comment: B. §146.84 Area of review and corrective action. 

EPA’s proposed rule allows each applicant to define the Area of Review ("AoR") 

associated with the sequestration project. Denbury has no objection to this 

flexible approach as it allows the size and shape of the AoR to reflect the 

unique geology of each CO2 sequestration project. However, under §146.84 (a), to 

define the AoR, an applicant must use a model capable of considering the 

physical and chemical properties of all phases of the injected carbon dioxide 

stream. Denbury is uncertain that there is a model that can satisfy this 

requirement. Accordingly, Denbury suggests that the proposed rule be amended as 

follows: 

§146.84 Area of review and corrective action. 

(a) The area of review is the region surrounding the geologic 

sequestration project that may be impacted by the injection activity. 

The area of review is based on computational modeling that, TO THE 

EXTENT PRACTICABLE AND TO THE EXTENT DETERMINED TO BE NECESSARY BY THE 

DIRECTOR, accounts for the MATERIAL physical and chemical properties of 

all CRITICAL phases of the injected carbon dioxide stream. 

Response: EPA disagrees that available multiphase models cannot consider the physical and chemical 

properties of all phases of the injected CO2 stream. Research, as discussed in the preamble to the 

proposed GS regulation and the associated background document "Computational Modeling of 

Underground Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk to 

Underground Sources of Drinking Water" (cited in the proposed rule preamble as USEPA, 2008d), 

substantiates the modeling requirements in the GS regulation and indicates that technology has advanced 

to the point that a CO2 injection project can be adequately modeled to support both prediction and 

tracking the movement of the CO2 plume and pressure front. EPA believes the Director should have 

discretion to evaluate each plan based on current, state of the art modeling science because there are 

large numbers and types of available models and because advances in the field of geologic modeling 

continue. 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24291

446
Based on review of all public comments on the AoR definition at 146.84(a), the Agency has modified it 

to read as follows: The region surrounding the geologic sequestration project where USDWs may be 

endangered by the injection activity. The area of review is delineated using computational modeling that 

accounts for the physical and chemical properties of all phases of the injected CO2 stream and is based 

on available site characterization, monitoring, and operational data. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: Denbury suggests the following revision: 

§146.86 (b) Casing and Cementing of Class VI Wells. (3) At least one 

long string casing, using a sufficient number of centralizers, must 

extend to the injection zone and must be cemented by circulating cement 

to the surface INJECTION ZONE AND CONFINING ZONE AND AN 

AUTHORIZED DISTANCE ABOVE THE CONFINING ZONE, SUBMITTED BY THE PERMITTEE 

AND APPROVED BY THE DIRECTOR in one or more stages. 

* 

* 

* 

(5) TO PROTECT USDWS, Ccement and cement additives must be 

compatible with the carbon dioxide stream and formation fluids and of 

sufficient quality and quantity to maintain integrity over the 

design OPERATING life of the WELL geologic sequestration 

project MUST BE USED ACROSS THE INJECTION ZONE AND CONFINING ZONE. 

The integrity and location of the cement shall be verified using 

technology capable of evaluating cement quality radially and identifying 

the location of channels to ensure that USDWs are not endangered. 

Response: EPA disagrees that the casing, cement, or other materials should only be designed for the 

period of the injection process, rather than the life of the sequestration project. GS projects are 

anticipated to have long life-spans in comparison to other types of deep injection wells. Not only must 

Class VI wells be able to function safely and properly over the lifespan of the GS project, but they must 

be constructed such that USDWs remain protected after well plugging. The requirements at §146.86 will 

ensure that the well can maintain integrity throughout the proposed life span of the project, including 

after the injection well is plugged and through the post-injection site care period and beyond. While the 

risk profile of a GS site will decrease following cessation of injection, EPA believes that Class VI wells 

must be designed to protect USDWs from endangerment for the life of the project. Furthermore, 

rigorous casing and cementing help ensure that the Class VI well will not serve as a conduit for 

movement of fluids associated with future injection operations. 

Additionally, EPA is developing guidance on the construction of Class VI wells. This guidance will be 

available on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24295

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24297

447
CFR 146.87) 

Comment: 1. EPA Proposed § 146.87 (a)(2) Before and upon installation of the 

surface casing:... 

(ii) A cement bond and variable density log, and a temperature log after 

the casing is set and cemented. 

The requirements in §146.87(a)(2)(ii) to secure and submit specified logs 

before, upon and after surface casing installation is excessive. The proposed 

rule fails to provide a sufficient justification for requiring a cement bond and 

variable density log before and upon installation of the long string casing, and 

requiring a temperature log after the casing is set and cemented. Temperature 

logs are seldom used in the drilling industry to determine cement 

characteristics as they do not provide useful data regarding the bonding of 

cement. The rules should be modified to allow the permittee to select between 

the specified logs and any other logging tool approved by the Director as 

follows: 

§146.87(a)(2)(ii) A cement bond and variable density log OR OTHER 

APPROVED TOOL, and OR a temperature log after the casing is set 

and cemented. [see § 146.12(d)(2)(i)(B) Criteria and Standards 

applicable to Class I nonhazardous wells: Construction Requirements.] 

* 

* 

* 

(5) Any alternative methods that provide equivalent or better 

information and that are required of and/or approved of by the Director. 

THE DIRECTOR MAY WAIVE ANY LOG OR TEST SPECIFIED IN THIS SUBPARAGRAPH. 

Response: Cement bond, variable density, and temperature logs are required by §146.87(a)(2) upon 

installation of the surface casing. EPA disagrees that the surface casing logging requirements are 

excessive. Evaluation of all logs, surveys, and tests listed in the rule will provide detailed information on 

the parts of the well that will penetrate the lowermost USDW and provide information on the quality of 

the cement seal with surrounding formations in order to ensure protection of USDWs from 

endangerment. 

As described above, EPA disagrees that any tests should be waived. While the tests do provide 

information on some of the same items, the tests provide unique pieces of information which enhance 

each other and allow for interpretations not possible with a single test. For example, a variable density 

log can detect microannuli, fractures, and formation effects. Temperature logs can detect fluid or gas 

flow through channels that cannot be detected by either of the other tests. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: 2. EPA Proposed §146.87 (a)( (3) Before and upon installation of the 

long string casing: (i) Resistivity, spontaneous potential, porosity, 

caliper, gamma ray, fracture finder logs, and any other logs the 

Director requires for the given geology before the casing is installed; 

and 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24298

448
Once again, the proposed rule requires testing that would be of little benefit 

in protecting USDWs, but would impose significant costs on operators. For 

example, Denbury sees no basis to run a fracture finder log in every well. 

Fracture finder logs will only see minor fractures within the individual 

formations. The log does not provide information on whether these minor 

fractures can act as conduits between the injection zone and confining zone. To 

avoid unnecessary data collection and submittal, the rules should allow the 

applicant to propose and justify a logging suite based on the reservoir and 

geology associated with the particular CO2 project. The Director of course 

should be allowed to approve, or recommend revisions to the proposed suite. This 

would avoid mandating unneeded testing. Denbury suggests the following revised 

rule, incorporating this proposed change: 

§146.87 (a)( (3) Before and upon installation of the long string casing: 

(i) Resistivity, spontaneous potential, porosity, caliper, gamma ray, 

fracture finder logs, and any other OR ANY SUITE OF LOGS 

SUBMITTED BY THE PERMITTEE AND APPROVED BY logs the Director 

BEFORE THE CASING IS INSTALLED requires for CONSIDERING the 

given geology before the casing is installed; and 

Response: EPA believes that a minimum suite of logs and tests is necessary at all Class VI wells. All 

logs, surveys, and tests listed at §146.87(a) are necessary to verify information about the injection and 

confining zones and ensure that the well is being drilled and cased as approved and has mechanical 

integrity. 

EPA notes that owners or operators will describe in their permit applications how they will construct and 

test the well, and will also submit site-specific information about the subsurface geology. The Director 

will evaluate the proposed logging activities along with site-specific geologic information to identify 

geologic data of interest. 

EPA adds that, should alternative methods be shown to provide equivalent or better information or if 

site-specific conditions and risk factors dictate that other logs are necessary, the Director has the 

discretion at §146.87(a)(5) to require further logs and tests if necessary and to approve alternative 

methods that provide equivalent or better information. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: The proposed rule also requires unnecessary and duplicative logging with respect 

to the long-string casing. 

3. EPA Proposed §146.87(a)( (3) Before and upon installation of the long 

string casing: (ii) A cement bond and variable density log, and a 

temperature log after the casing is set and cemented. 

Denbury suggests that the logging options it recommends with respect to surface casing 

also apply for the long-string casing. Thus, the proposed rule should be revised as 

follows: 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24299

449
§146.87(a)(3)(ii) A cement bond and variable density log OR OTHER 

APPROVED TOOL, and OR a temperature log after the casing is set 

and cemented. [see § 146.12(d)(2)(ii)(C) Criteria and Standards 

applicable to Class I nonhazardous wells: Construction Requirements.] 

Response: EPA disagrees that the requirements for logging of the long-string casing at §146.87(a)(3)(ii) 

are unnecessary. While the tests do provide information on some of the same items, the tests provide 

unique pieces of information which enhance each other and allow for interpretations not possible with a 

single test. For example, a variable density log can detect microannuli, fractures, and formation effects. 

Temperature logs can detect fluid or gas flow through channels that cannot be detected by either of the 

other tests. 

Determining the quality of the cementing of the long-string casing is essential to the protection of 

USDWs from endangerment. EPA adds that, should alternative methods be shown to provide equivalent 

or better information, the Director may allow such alternatives under §146.87(a)(5). 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: 4. EPA Proposed §146.87(b) The owner or operator must take and submit to 

the Director whole cores or sidewall cores of the injection zone and 

confining system and formation fluid samples from the injection zone(s). 

The Director may accept cores from nearby wells if the owner or operator 

can demonstrate that core retrieval is not possible and that such cores 

are representative of conditions at the well. The Director may require 

the owner or operator to core other formations in the borehole. 

Denbury opposes the requirement to collect cores from more than one (1) well 

within a CO2 project. As a practical matter, the majority of the important 

physical and geophysical properties of the injection reservoir, including the 

particular attributes of the confining formations can and are required to be 

evaluated from logs and other scientific, reliable measures. A "whole core," as 

specified in §146.87(b) is only a very small sample of the attributes of a 

reservoir and a sidewall core, an even smaller sample. The former is very 

expensive to collect, and the latter often not available. Neither is essential 

given the vast amount of data otherwise required, and multiple samples, as 

proposed by the rule, are not reasonable. The unreasonableness of the whole 

core, sidewall core and extra core sampling is evident upon consideration of the 

sheer volume of physical evidence that this provision alone may produce. For 

example, in Texas there are over 5000 existing Class II CO2 injection wells. If 

a small fraction of these wells are converted to Class VI CO2 injection wells 

following the completion of production activities, there will be a large 

universe of cuttings. Where will the regulatory agency store this magnitude of 

cuttings? This may become a particular problem given the total number of CO2 

sequestration projects that may be proposed. 

Denbury suggests the following: 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24300

450
§146.87(b) AT THE SPECIFIC REQUEST OF THE DIRECTOR AND ONLY WHERE CORE 

RETRIEVAL IS POSSIBLE, TThe owner or operator must take and 

submit to the Director A whole cores or sidewall cores of the injection 

zone and confining system and formation fluid samples from the injection 

zone(s). The Director may accept cores from nearby wells if the owner 

or operator can demonstrate that core retrieval is not possible and that 

such cores are representative of conditions at the well. The Director 

may require the owner or operator to core other formations in the 

borehole. 

Response: EPA clarifies that §146.87(b) allows information on cores from nearby wells to be submitted 

if the owner or operator can demonstrate that core retrieval is not possible and that cores from nearby 

wells are representative of conditions at the Class VI well. EPA clarifies that, at a minimum, reports on 

cores of injection zones, confining zones, and samples of formation fluids must be submitted. Section 

146.87(b) gives the Director authority to require the owner or operator to core other formations in the 

borehole if necessary to provide sufficient geologic information to verify that the site is suitable for GS.

EPA clarifies that it is not the Agency's intent that physical cores be submitted to the Director. In the 

final GS rule, EPA has revised the first sentence of §146.87(b) to read as follows: "The owner or 

operator must take whole cores or sidewall cores of the injection zone and confining system and 

formation fluid samples from the injection zone(s), and must submit to the Director a detailed report 

prepared by a log analyst that includes: well log analyses (including well logs), core analyses, and 

formation fluid sample information...." 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: 6. EPA Proposed §146.87(f) The owner or operator must provide the 

Director with the opportunity to witness all logging and testing by this 

subpart. The owner or operator must submit a schedule of such activities 

to the Director 30 days prior to conducting the first test and submit 

any changes to the schedule 30 days prior to the next scheduled test. 

The agency requires the submission of a proposed logging and testing schedule at 

least 30 days in advance of those proposed activities. Although a logging and 

testing schedule certainly can be designed 30 or more days in advance, the 

actual date that logging is performed is usually available only 24 to 48 hours 

in advance of actual logging operations. A mandatory 30 day notice is simply not 

practical for logging and testing. Denbury asks that notice requirements in this 

subpart be adjusted to take into account the practical limitations experienced 

routinely in field operations. Suggested revised language is set forth below. 

§146.87(f) The owner or operator must provide the Director with the 

opportunity to witness all logging and testing by this subpart. The 

owner or operator must submit a PROPOSED schedule of such activities to 

the Director AT LEAST 30 days prior to conducting the first test and 

submit NOTICE AT LEAST 24 HOURS IN ADVANCE OF THE CONDUCT OF ANY ACTUAL 

LOGGING AND TESTING. any changes to the schedule 30 days prior to the 

next scheduled test. 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24302

451
Response: EPA disagrees that the 30-day notification requirement is unreasonable. Acknowledging the 

developing nature of CO2 GS, EPA believes that involvement by the permitting authority in each project 

will provide much needed field data for assurance of USDW protection from endangerment and will 

help update and refine the permitting process. Adequate timing of notification will ensure the Director's 

ability to be involved. 

Other EPA Comment Codes and Descriptions: 4100 2.4.1 Injection parameters 

Comment: E. § 146.88 Injection well operating requirements. 

1. EPA Proposed §146.88(c) The owner or operator must fill the annulus 

between the tubing and the long string casing with a non-corrosive fluid 

approved by the Director. The owner or operator must maintain on the 

annulus a pressure that exceeds the operating injection pressure, unless 

the Director determines that such requirement might harm the integrity 

of the well. 

EPA’s suggested Mechanical Integrity ("MI") rule to maintain pressure on the 

annulus exceeding the operating injection pressure will, in most cases, result 

in an exceedance of the burst pressure of the casing. If the operator is 

required to maintain pressure on the annulus at a rate that is greater than the 

injection pressure (as indicated in EPA proposed §146.88(c)), monitoring the 

annulus pressure may not be an accurate indicator of mechanical integrity. The 

EPA appears to recognize this likelihood and thus allows the Director to waive 

the requirement. However, the rule should not require a questionable practice 

and then permit its waiver. Rather, the practice should only be required if the 

Director makes a determination that the conduct of the test will NOT cause a 

problem. The suggested revision is encapsulated below: 

(c) The owner or operator must fill the annulus between the tubing and 

the long string casing with a non-corrosive fluid approved by the 

Director. IF THE DIRECTOR DETERMINES THAT SUCH REQUIREMENT WILL NOT HARM 

THE INTEGRITY OF THE WELL, Tthe owner or operator must maintain A 

POSITIVE PRESSURE on the annulus a pressure that exceeds the 

operating injection pressure. ., unless the Director determines that 

such requirement might harm the integrity of the well. 

Response: EPA disagrees that maintaining annulus pressures that exceed the injection pressure would 

cause bursting of the casing. A properly designed well that takes into account the geologic and 

geomechanical properties of the site based on information collected under §146.82 and meets the 

construction requirements at §146.86 would be able to maintain integrity if the annulus pressure were 

reasonably higher than injection pressure. 

The purpose of continuous pressure monitoring (to demonstrate internal MI) is to demonstrate that no 

pressure changes are occurring, because a drop in pressure on the annulus provides an early indication 

that attention is needed to prevent a loss of MI or unacceptable fluid movement. EPA believes that any 

change in the pressure on the annulus between tubing and long stem casing, regardless of what the 

annulus pressure is relative to injection pressure, can indicate a leak. 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24303

452
The GS rule, at §146.88(c), allows the Director to make exceptions if the Director determines that such a 

requirement might harm the integrity of the well. The final regulation at §146.88(c) requires that the 

owner or operator must maintain on the annulus a pressure that exceeds the operating injection pressure, 

unless the Director determines that such requirement might harm the integrity of the well or endanger a 

USDW. 

Other EPA Comment Codes and Descriptions: 4520 2.5.1 Continuous internal mechanical integrity 

monitoring (seeking comment) 

Comment: Furthermore, the requirement to continuously monitor the annulus fluid volume is 

impractical, because it does not provide any meaningful data regarding potential 

problems with the operation of the well. Requiring the continuous monitoring of 

the amount of annulus fluid added during operations is more practical and will 

reveal potential leakage paths. Denbury recommends the following: 

§146.88(e) The owner or operator must install and use continuous 

recording devices to monitor: The injection pressure; the rate, volume, 

and temperature of the carbon dioxide stream; and the pressure on the 

annulus between the tubing and the long string casing and THE VOLUME OF 

annulus fluid added to the annulus volume; and the owner 

or operator must install and use alarms and automatic down-hole 

shut-off systems, designed to alert the operator and shut-in off 

the well when operating parameters such as annulus pressure, injection 

rate or other parameters approved by the Director diverge beyond 

permitted ranges and/or gradients specified in the permit. IF THE 

Response: EPA believes that monitoring of annulus fluid volume is an important method for verifying 

that the well system is intact and is necessary for monitoring annulus pressure. While this requirement 

has, until now, been limited to Class I hazardous waste injection wells, the high volumes and 

supercritical nature of the injectate, the potential geomechanical stresses in the wellbore, and the 

potential for movement of the buoyant CO2 in the event of a MI loss make it an important safety 

consideration for GS projects. Continuous pressure monitoring allows immediate identification of 

corrosion-related well integrity loss. EPA agrees with the commenter that recording annulus fluid 

volume may not be appropriate. EPA believes that knowing annulus fluid volume as required at §146.88

(e) is a necessary component of monitoring well mechanical integrity, but also believes that knowing the 

annulus fluid volume added is sufficient to meet the intent of the requirement. The final GS rule requires 

that owners or operators use continuous recording devices to monitor injection pressure, rate, and 

volume, as well as the pressure on the annulus between the tubing and the long string casing. It also 

modifies the requirement in the proposed rule to continuously monitor annulus fluid volume; it now 

requires recording of annulus fluid volume added. See §§146.88(e); 146.89(b); and 146.90 (b). 

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells 

(seeking comment) 

Comment: OPERATION INVOLVES OFF-SHORE INJECTION, THE OWNER OR OPERATOR 

MUST 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24305

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24306

453
INSTALL AND USE ALARMS AND AUTOMATIC DOWN-HOLE SHUT-OFF SYSTEMS, 

DESIGNED TO ALERT THE OPERATOR AND SHUT-IN THE WELL IF THE WELLHEAD IS 

DAMAGED OR WHEN OPERATING PARAMETERS SUCH AS ANNULUS PRESSURE, 

INJECTION 

RATE OR OTHER PARAMETERS APPROVED BY THE DIRECTOR DIVERGE BEYOND 

PERMITTED RANGES AND/OR GRADIENTS SPECIFIED IN THE PERMIT; 

(f) If aN down-hole automatic shutdown is triggered or a loss of 

mechanical integrity is discovered, the owner of operator must 

immediately investigate and identify as expeditiously as possible the 

cause of the shutoff. 

Response: After evaluating the risks and benefits of down-hole shut-off systems and considering 

additional research, EPA will not require automatic down-hole shut-off devices for onshore Class VI 

wells since it is not necessary in all cases to ensure protection of USDWs from endangerment. Instead, 

the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells install 

automatic surface shut-off devices. The rule affords Director's discretion to mandate automatic downhole shut-off devices in onshore situations that may warrant their use. 

The GS rule, at §146.88(e)(3), requires the installation of down-hole shut-off devices for Class VI wells 

located in the offshore submerged lands within the jurisdiction of a State UIC program. The Agency 

believes that the unique construction and operational conditions for offshore Class VI wells, including 

isolation from shorelines and the need to construct wells through the water column and the subsurface, 

may delay response time in the event of well difficulties. These conditions merit requiring automatic 

down-hole shut-off devices for offshore wells in the submerged lands of a State. 

EPA believes that requiring the installation of automatic surface shut-off devices for onshore wells (and 

affording Director's discretion to require down-hole devices where necessary) and automatic down-hole 

shut-off devices for offshore wells in submerged lands within the jurisdiction of a State ensures that 

proper precautions are taken to prevent subsurface fluid movement and ensure protection of USDWs, 

human health, and the environment. 

Other EPA Comment Codes and Descriptions: 4543 2.5.2.1 MIT procedures and methods for GS 

(seeking comment) 

Comment: F. § 146.89 Mechanical integrity. 

1. EPA Proposed §146.89(c) At least once per year, the owner or operator 

must use one of the following methods to determine the absence of 

significant fluid movement under paragraph (a)(2) of this section: 

(3) A casing inspection log, if required by the Director. 

Among the test protocols prescribed by the proposed rule to confirm lack of 

significant fluid movement is a casing inspection log. Although this log is 

optional, it may be required by the Director. Conducting a casing inspection log 

will require the tubing to be pulled from a well, and that in turn substantially 

increases the possibility of a well control event (that is a loss of control 

over well operation). Accordingly, the technique should only be mandated when 

other testing methodologies are unavailable. Denbury suggests the following

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24307

454
edit: 

§146.89(c) At least once per year, the owner or operator must use one of 

the following methods to determine the absence of significant fluid 

movement under paragraph (a)(2) of this section: 

(3) A casing inspection log, if A TRACER SURVEY OR A TEMPERATURE OR 

NOISE LOG CANNOT BE OBTAINED AND A CASING INSPECTION LOG IS THUS 

required by the Director. 

Response: EPA agrees that the casing inspection log is not an appropriate test to detect fluid movement 

behind the casing, but clarifies that it is appropriate for determining the presence or absence of corrosion 

of the long-string casing, and is required if the Director determines that it is necessary based on sitespecific information. EPA has revised the final GS rule to require that the frequency of the casing 

inspection log be specified in the approved testing and monitoring plan at §146.89(d). 

Other EPA Comment Codes and Descriptions: 4620 2.6.2 Injectate monitoring 

Comment: G. § 146.90 Testing and monitoring requirements. 

1. EPA Proposed §146.90(b) Installation and use, except during well 

workovers as defined in § 146.86(d), of continuous recording devices to 

monitor injection pressure, rate and volume; the pressure on the annulus 

between the tubing and the long string casing; and the annulus fluid 

volume; 

Consistent with our comment regarding proposed § 146.88(e) in Section 5 above, 

Denbury is unaware of a methodology to monitor the actual volume of annular 

fluid in the annulus on a continuous basis, and thus seeks agency clarification 

on this portion of the proposed rule. 

Response: EPA believes that knowing annulus fluid volume, as required at §146.88(e), is a necessary 

component of monitoring well mechanical integrity, but believes that monitoring the annulus fluid 

volume added is sufficient to meet the intent of continuous monitoring of the pressure on the annulus. 

The final GS rule at §146.90 (b) requires that owners or operators use continuous recording devices to 

monitor injection pressure, rate, and volume; the pressure on the annulus between the tubing and the 

long string casing; and the annulus fluid volume added. 

Other EPA Comment Codes and Descriptions: 4630 2.6.3 Corrosion monitoring 

Comment: 2. EPA Proposed §146.90(c) Corrosion monitoring of the well materials 

for loss of mass, thickness, cracking, pitting and other signs of 

corrosion must be performed on a quarterly basis to ensure that the well 

components meet the minimum standards for material strength and 

performance set forth in § 146.86(b) by: 

(1) Placing coupons of the well construction materials in contact with 

the carbon dioxide stream; or 

(2) Routing the carbon dioxide stream through a loop constructed with 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24308

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24309

455
the material used in the well; or 

(3) Using an alternative method approved by the Director; 

Denbury believes the requirements in EPA proposed §146.90(c) related to 

corrosion monitoring are inapplicable. In the vast majority of cases, the CO2 

will be transported to the injection site through pipelines, will be dehydrated 

prior to transportation and therefore when injected it will be noncorrosive.[FN44] In those instances, the test methods described in § 146.90(c) 

(1) and (c)(2) (except of course alternatives approved by the Director) will not 

provide meaningful information regarding the mechanical integrity of down-hole 

casing, tubing and other equipment because the CO2 will simply not be corrosive 

at the surface. Consequently, to have any relevance such requirements should be 

reserved for situations where water saturated CO2 is being injected. 

§146.90(c) Corrosion monitoring of the well materials for loss of mass, 

thickness, cracking, pitting and other signs of corrosion must be 

performed on a quarterly basis to ensure that the well components 

THAT CONTACT WATER SATURATED CARBON DIOXIDE STREAMS meet the minimum 

standards for material strength and performance set forth in § 146.86(b) 

by: 

(1) Placing coupons of the well construction materials in contact 

with the carbon dioxide stream; or 

(2) Routing the carbon dioxide stream 

through a loop constructed with the material used in the well; or 

(3) Using an alternative method approved by the Director. THE REQUIREMENTS 

OF THIS SUBPART ARE WAIVED WHEN THE CARBON DIOXIDE STREAM IS DEHYDRATED 

TO MEET PIPELINE SPECIFICATIONS. 

[44] For evidence on CO2 corrosiveness in the absence of free water see Don 

Duttlinger, "Enhanced Recovery Intertwines Naturally With CO2 Sequestration," 

Tech Connections Column, American Oil and Gas Reporter (January 2004), available 

at http://www.pttc.org/aogr_columns_archived/aogrcojan04.htm (From the 

processing/injection standpoint, CO2 is noncorrosive as long as it is dry. 

Proving that point, Kinder Morgan has hydro-tested the 32-year-old CRC Pipeline 

built in 1971 to transport CO2. Only one minor failure occurred. After testing, 

the line was rated for 2,025 psi maximum operating pressure, which established a 

200 psi increase over most recent ratings); see also J. Layne, "Results of the 

Hydrotest of the 30-year old Canyon Reef Carriers CO2 Pipeline," 2003 CO2 

Flooding Conference, University of Texas of the Permian Basin's Center for 

Energy and Economic Diversification, Midland,Texas (December 11-12, 2003). 

Response: EPA disagrees that corrosion monitoring is unnecessary or excessive. CO2 in the presence of 

water (including water with NOx, SOx, and H2S impurities) can be corrosive to well materials and 

cements. Thus, although a CO2 stream may be dry, the potential for corrosion of well materials downhole, where the injectate can potentially mix with water in the target formation, must be considered. 

EPA believes that the testing methods specified in the rule are appropriate and have been used 

successfully by Class I hazardous waste injection well owners or operators. 

Several laboratory studies and a limited number of field studies have investigated and characterized the 

effects of carbonic acid on well materials. Laboratory studies (e.g., Kutchko et al., 2007; Kutchko et al., 

456
2008) consistently identify alterations (typically carbonation) of cement as the result of interactions 

between cement and CO2-saturated brine. 

Currently, there are only a few analyses of cement from wells that have been in prolonged contact with 

CO2 in actual field (down-hole) conditions. Evaluation of cement from a well at the Scurry Area 

Canyon Reef Operators Committee (SACROC) site showed alteration, but did not show degradation that 

compromised the structural integrity of the cement (Carey et al., 2007). In another study, cement 

samples were collected and analyzed from a CO2 production well in a natural CO2 reservoir in 

Colorado exposed to a CO2-water down-hole environment for 30 years (Crow et al., 2008). The study 

found evidence of reaction between the CO2-rich water and the cement. 

Oil industry research also addresses the effects of corrosion of steel tubing and pipes. Lopez et al. (2003) 

noted that 60 percent of oilfield failures are related to the effects of carbonic acid from produced brines 

on carbon and low alloy steels. 

Laboratory investigation of cement alteration/degradation is an ongoing research area. Few field-based 

studies have been completed to date. The laboratory and field studies currently available suggest that 

corrosion problems can be managed; however, there is not a large enough body of research to rule out 

potential corrosion problems of steel components of injection wells. The IPCC (2005) report on carbon 

dioxide capture and storage reviewed oil and gas industry experience with gas injection wells, close 

industry analogues to CO2 injection wells. The report stated that while the design of CO2 injection wells 

will be very similar to gas injection wells, most down-hole components of the CO2 injection wells will 

“need to be upgraded for higher pressure ratings and corrosion resistance.” Given the pressure and 

corrosion considerations, anticipated long lifespan of a GS well and the difficulties that would be 

associated with a corrosion-related well failure, EPA believes that corrosion monitoring in the downhole environment is justified. For these reasons, the final rule requires quarterly corrosion monitoring (at 

§146.90(c)). See the final rule and preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: H. § 146.92 Injection well plugging. 

1. EPA Proposed §146.92 (b) Well Plugging Plan. (5) The type and grade 

and quantity of material to be used in plugging. The material must be 

compatible with the carbon dioxide stream; 

The proposed regulation requires the wellbore to be flushed prior to plugging 

and thus it is unnecessary to use cement "compatible with the carbon dioxide 

stream." In the absence of water, CO2 is non-corrosive and compatible with 

conventional cements (see discussion under Comment #G). Accordingly, the rule 

should be revised as follows: 

§146.92 (b) Well Plugging Plan. (5) The type and grade and quantity of 

material to be used in plugging. The material must be compatible with 

the carbon dioxide stream; 

Response: EPA believes, considering the potentially corrosive nature of CO2 when it is in contact with 

water, that the requirement that the material must be compatible with the CO2 stream is appropriate. The 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24312

457
final rule retains this requirement because CO2 and water will be present in the subsurface. 

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment); 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: I. § 146.93 Post-injection site care and site closure. 

The proposed rule establishes a 50 year default period for post-injection site 

care. There is, however, no factual or scientific basis for such an extensive 

period. Under EPA’s Resource Conservation and Recovery Act rules, which regulate 

the disposal of hazardous wastes, post closure care is limited to 30 

years.[FN45] Defaulting to an excessively long period will increase costs and 

introduce greater regulatory uncertainty, which will discourage capital 

formation around CO2 sequestration. A more prudent regulatory approach is to set 

a minimum period for site care, ten years, with allowance for the Director to 

extend the period if facts and circumstances warrant a longer post-injection 

site care period. 

Additionally, the proposed rule’s 50 year default post injection site care 

period, is an illusory deadline, as it is not self-executing. Under the rules, 

post injection site care must continue indefinitely until the Director 

authorizes closure. The closure approval process could take years, even decades, 

as the Director has no regulatory incentive to act on any post injection site 

care report. Meanwhile, a permittee may be required to continue unnecessary and 

expensive monitoring and reporting indefinitely. 

Denbury suggests that the post-injection site care rules be reconfigured to 

require a more limited mandatory post-injection site care timeframe, and to 

allow for closure at the end of that period unless the Director affirmatively 

acts to extend the post-injection site care period. These changes are contained 

in the suggested text below: 

§ 146.93 Post-injection site care and site closure. 

(a) The owner or operator of a Class VI well must prepare, maintain, and 

comply with a plan for post-injection site care and site closure that 

meets the requirements of paragraph (a)(2) of this section and is 

acceptable to the Director. 

(1) The owner or operator must submit the post-injection site 

care and site closure plan as a part of the permit application to be 

approved by the Director. 

(2) The post-injection site care and site closure plan must 

include the following information: 

(i) The pressure differential between pre-injection and 

predicted post-injection pressures in the injection zone; 

(ii) The predicted position of the carbon dioxide plume 

and associated pressure front at site closure as demonstrated in 

the area of review evaluation required under § 146.84(b); 

(iii) A description of post-injection monitoring 

location, methods, and proposed frequency; and 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24313

458
(iv) A proposed schedule for submitting post-injection 

site care monitoring results to the Director. 

(3) Upon cessation of injection, owners or operators of Class VI 

wells must either submit an amended post-injection site care and site 

closure plan or demonstrate to the Director through monitoring data and 

modeling results that no amendment to the plan is needed. 

(4) The owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval 

within 30 days of such change. 

(b) The owner or operator shall monitor the site following the cessation 

of injection to show the position of the carbon dioxide plume and 

pressure front and demonstrate that USDWs are not being endangered. 

(1) The owner or operator shall continue to conduct monitoring 

as specified in the Director-approved post-injection site care and site 

closure plan for at least 50 10 years following the cessation of 

injection. At the UPON A DETERMINATION BY THE Director ’s 

THAT THE GEOLOGIC SEQUESTRATION PROJECT MAY POSE AN ENDANGERMENT TO 

USDWS discretion , THE DIRECTOR, AT HIS DISCRETION, MAY REQUIRE 

the monitoring will TO continue FOR A TIME PERIOD SPECIFIED BY 

THE DIRECTOR until the geologic sequestration project no longer poses 

an endangerment to USDWs. 

(2) If the owner or operator can demonstrate to the satisfaction 

of the Director before 50 10 years, based on monitoring and other 

site-specific data, that the geologic sequestration project no longer 

poses an endangerment to USDWs, the Director may approve an amendment to 

the post injection site care and site closure plan to reduce the 

frequency of monitoring or may authorize site closure before the end of 

the 50 10 year period. 

(3) Prior to authorization for THE EXPIRATION OF THE 10 

YEAR POST-INJECTION SITE CARE PERIOD, site closure, the owner or 

operator must submit to the Director a demonstration, based on 

monitoring and other site specific data, that the carbon dioxide plume 

and pressure front have stabilized and that no additional monitoring is 

needed to assure that the geologic sequestration project does not pose 

an endangerment to USDWs. 

(4) IF WITHIN 180 DAYS AFTER THE SUBMITTAL OF THE DATA REQUIRED 

UNDER SUBPARAGRAPH (3) ABOVE THE DIRECTOR DETERMINES THAT THE 

GEOLOGICAL 

SEQUESTRATION PROJECT MAY CONTINUE TO POSE AN ENDANGERMENT TO USDWS, 

HE 

SHALL SO NOTIFY THE OWNER OR OPERATOR OF HIS DETERMINATION AND THE BASIS 

THEREFORE, AND If such a demonstration cannot be made (i.e., if the 

carbon dioxide plume and pressure front have not stabilized) after the 

50-year period, the owner or operator must submit to the Director a 

plan to continue post-injection site care. 

(5) IF WITHIN 180 DAYS AFTER THE SUBMITTAL OF THE DATA REQUIRED 

UNDER SUBPARAGRAPH (3) ABOVE THE DIRECTOR FAILS TO DETERMINE AND TO 

NOTIFY THE OWNER OR OPERATOR THAT THE GEOLOGICAL SEQUESTRATION PROJECT 

MAY CONTINUE TO POSE AN ENDANGERMENT TO USDWS, SITE CLOSURE SHALL BE 

DEEMED AUTHORIZED BY RULE 

(c) Notice of intent for site closure. 

459
The owner or operator must notify the Director at least 120 days before 

site closure. At this time, if any changes have been made to the 

original post-injection site care and site closure plan, the owner or 

operator must also provide the revised plan. At the discretion of the 

Director, a shorter notice period may be allowed. 

(d) After the Director has authorized site closure OR SITE CLOSURE IS 

AUTHORIZED BY RULE, the owner or operator must plug all monitoring wells 

in a manner which will not allow movement of injection or formation 

fluids that endangers a USDW. 

(e) Once the Director has authorized site closure, OR SITE CLOSURE IS 

AUTHORIZED BY RULE, the owner or operator must submit a site closure 

report within 90 days that must thereafter be retained at a location 

designated by the Director. The report must include: 

(1) Documentation of appropriate injection and monitoring well 

plugging as specified in § 146.92 and paragraph (c) of this section. The 

owner or operator must provide a copy of a survey plat which has been 

submitted to the local zoning authority designated by the Director. The 

plat must indicate the location of the injection well relative to 

permanently surveyed benchmarks. The owner or operator must also submit 

a copy of the plat to the Regional Administrator of the appropriate EPA 

Regional Office; 

(2) Documentation of appropriate notification and information to 

such State, local and tribal authorities as have authority over drilling 

activities to enable such State and local authorities to impose 

appropriate conditions on subsequent drilling activities that may 

penetrate the injection and confining zone(s); and 

(3) Records reflecting the nature, composition and volume of the 

carbon dioxide stream. 

(f) Each owner or operator of a Class VI injection well must record a 

notation on the deed to the facility property or any other document that 

is normally examined during title search that will in perpetuity provide 

any potential purchaser of the property the following information: 

(1) The fact that land has been used to sequester carbon dioxide; 

(2) The name of the State agency, local authority, and/or tribe 

with which the survey plat was filed, as well as the address of the 

Regional Environmental Protection Agency Office to which it was 

submitted; and 

(3) The volume of fluid injected, the injection zone or zones 

into which it was injected, and the period over which injection 

occurred. 

(g) The owner or operator must retain for three years following site 

closure, records collected during the post-injection site care period. 

The owner or operator must deliver the records to the Director at the 

conclusion of the retention period, and the records must thereafter be 

retained at a location designated by the Director for that purpose. 

[45] 40 C.F.R. § 264.117(a)(1) 

Response: The post-injection site care requirements in the final GS rule, §146.93(b), incorporate a 

combination of a 50-year default post-injection site care timeframe, in conjunction with a performance 

standard, for Class VI wells. The GS rule offers owners or operators flexibility regarding the duration of 

460
the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe 

during the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or 

(2) affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during 

the permitting process based on substantial data, that an alternative PISC timeframe may be appropriate 

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for 

post-injection site care will be necessary in all but a limited number of cases. This default 50 year postinjection site care timeframe represents a reasonable and protective monitoring period based on a review 

of research studies, industry reports, and existing environmental programs, and evaluation of public 

comments. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. EPA expects that the Director will consider 

the types of information the commenter describes in determining whether the plume and pressure front 

no longer pose a risk of endangerment to USDWs and post-injection site care monitoring may be 

discontinued. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will assist 

Directors in evaluating proposed well plugging plans and post-injection site care and site closure plans 

under §146.92 and §146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells, perform post-injection monitoring, demonstrate the 

appropriateness of an alternative post-injection site care time frame, demonstrate non-endangerment, 

and perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: Page 43498. The Weyburn Field is in Saskatchewan, Canada, not Alberta. 

Response: EPA acknowledges the comment and agrees. 

Comment: Page 43500. Regarding the statement, "4-D seismic is a valuable tool for plume 

tracking" at Weyburn. "Is" is a strong word. Based on personal conversations 

with those who have worked on Weyburn, it is suggested that "may be" is more 

accurate. 

Response: EPA acknowledges the comment; this paragraph is not included in the preamble to the final 

rule. 

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the 

University of North Dakota

Comment ID: 

21586

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the 

University of North Dakota

Comment ID: 

21591

461
Other EPA Comment Codes and Descriptions: 2060 1.5.3 Comments on grandfathering of existing 

wells (seeking comment); 3820 2.3.1 Well construction procedures 

Comment: 1. § 146.81 Applicability 

The proposed rule provides that owners or operators of authorized Class I 

industrial, Class II, or Class V experimental CO2 injection projects who seek to 

"convert" these wells to Class VI wells and apply for a Class VI permit may be 

exempted, at the Director’s discretion, from the proposed casing and cementing 

requirements applicable to Class VI wells. 

EPA Proposed § 146.81(c) This subpart applies to owners and operators of 

permit or rule- authorized Class I industrial, Class II, or Class V 

experimental carbon dioxide injection projects who seek to apply for a 

Class VI geologic sequestration permit for their well or wells. If the 

Director determines that USDWs will not be endangered, such wells are 

exempt, at the Director’s discretion, from the casing and cementing 

requirements at §§ 146.86(b) and 146.87(a)(1) through (3). 

It is helpful that EPA recognizes that entities may wish to convert other 

classes of wells (such as Class II wells used for CO2 enhanced oil recovery 

projects) into Class VI wells and that flexibility is necessary for this 

conversion process. This flexibility should be maintained in the final rules but 

should be enhanced. In addition, the rules should be expanded to provide further 

detail on the conversion process. It is critical that owners and operators have 

clear and concise rules to rely on when seeking to grandfather their existing 

wells. This provision should be revised to limit the Director’s discretion and 

address all variances resulting in modifications to existing wells. For 

instance, while the rules waive the Class VI casing and cementing requirements 

for existing wells being converted to Class VI wells, the rules do not address 

other construction or construction-related Class VI well requirements that 

create variances between Class VI and Class I, II and V wells. Those 

requirements include: 

1. Down hole automatic shut-off valve with wellhead hydraulics; 

2. Annulus liquid level detector; 

3. Wellhead corrosion monitoring equipment; and 

4. Mechanical integrity testing. 

Each of these requirements applicable to Class VI wells would require 

retrofitting or modifications to existing wells and could make conversion of 

wells impracticable or excessively expensive. Rather than requiring existing 

wells to meet prescriptive rules that may not be necessary or applicable, the 

decision to grandfather an existing well should be based solely on the well’s 

passing a mechanical integrity test without physical well modification and 

meeting all other Class VI permit requirements that may be met without well 

modification. This change could be accomplished by revising proposed § 146.81(c) 

as follows: 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23967

462
(c) This subpart applies to owners and operators of permit or rule-authorized 

Class I industrial, Class II, or Class V experimental carbon dioxide injection 

projects who seek to apply for a Class VI geologic sequestration permit for 

their well or wells. If the Director determines that USDWs will not be 

endangered THROUGH THE RESULTS OF MECHANICAL INTEGRITY TESTING PURSUANT 

TO § 

146.89 THAT THE WELL IS EFFECTIVE IN PREVENTING ENDANGERMENT OF USDWS, such 

wells are exempt, at the Director’s discretion, from the casing and 

cementing requirements at §§ 146.86(b) and 146.87(a)(1) through (3) ANY 

REQUIREMENT IMPOSING PHYSICAL WELL MODIFICATIONS, SUBJECT TO MEETING ALL 

OTHER 

CLASS VI WELL REQUIREMENTS. 

Response: EPA expects that any decision to convert a well for long term storage of CO2 be made in the 

context of all available information about the site and history of injection. The final GS rule provides for 

the construction of these wells to be grandfathered per §146.81(c), provided the owner or operator can 

demonstrate to the Director that the wells were engineered and constructed to meet the requirements at 

§146.86(a) and ensure protection of USDWs, in lieu of requirements at §146.86(b) and §146.87(a). 

EPA clarifies that other Class VI requirements (i.e., beyond the construction requirements) will not be 

grandfathered. Following conversion of the project to Class VI, many of the unique factors of GS sites 

(e.g., increased reservoir pressures associated with large volumes of stored CO2 and the corrosivity of 

CO2 in the presence of water) warrant the specific operational, MIT, monitoring, reporting, plugging, 

post-injection site care, and site closure requirements in the final GS rule. Therefore, following repermitting, these projects must be subject to the requirements in the final GS rule, including 

requirements related to down-hole shut-off devices, annulus fluid monitoring, corrosion monitoring, and 

MITs. EPA adds that only requiring a MIT test for wells converting from Class I, II, or V would not be 

sufficient to ensure that the well was adequate to properly contain the buoyant and corrosive nature of 

the CO2 stream. EPA believes that down-hole shut-off systems and corrosion monitoring are also 

necessary to ensure the well maintains its integrity. See the discussion of EPA's final regulatory 

approach in the preamble to the GS rule for additional detail on these requirements. 

If, because of its construction, a current Class II well cannot be converted for GS in such a way that 

USDWs are protected from endangerment (i.e., by meeting the monitoring, MIT, and other requirements 

for Class VI wells), conversion will not be allowed. While conversion of suitable Class II wells for GS is 

desirable in many situations, EPA stresses that protection of USDWs from endangerment is the primary 

mission and mandate of the UIC program. 

To clarify the point at which the primary purpose of CO2 injection transitions from ER (i.e., a Class II 

well) to long-term storage (i.e., Class VI), the final GS rule at §144.19 contains specific, risk-based 

factors to be considered by the Director in making this determination. Furthermore, EPA is developing 

guidance on transitioning from Class II to Class VI. The guidance will assist Directors and 

owner/operators in evaluating where a project may fit within a Class II to Class VI transition. The 

guidance describes the methods available for the Director to determine the risk posed to USDWs from a 

GS/ER project, and how the Director may determine if a project should be regulated by a Class II or 

Class VI UIC program. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Commenter Name: Darrick Eugene Letter ID: 0223

463
Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: 2. § 146.82 Required Class VI permit information 

This section of the proposed rule sets forth the information which the owner or 

operator must submit to the Director in order to obtain a Class VI well permit. 

All of the information specified must be part of the permit application. But 

some data are not necessary in light of other provisions of the current 

proposal, and some are not attainable prior to well drilling (applicants will 

not drill the well until it has been approved, otherwise they risk drilling an 

unusable well). Still other data can only be obtained after injection activities 

have been initiated. Post drilling and post injection data should not be 

required as part of the application process but instead should be considered 

confirmatory data that may be submitted after they are obtained. In general, the 

proposed rule should be modified to require submission of only those data which 

are needed for consideration of the initial permit application, and only those 

data that may be reasonably obtained prior to commencement of installation and 

operation of the injection well. 

EPA Proposed: §146.82 (f) Maps and stratigraphic cross sections 

indicating the general vertical and lateral limits of all USDWs, water 

wells and springs within the area of review, their positions relative to 

the injection zone(s) and the direction of water movement, where known; 

So long as the Applicant proposes to inject CO2 below the lowermost USDW, as 

required by the proposed rule, there is no justification to require maps and 

stratigraphic cross sections for the entire extent of those USDWs above the 

lowermost USDW, although mapping and stratigraphic cross sections in the 

immediate vicinity of the proposed injection locations (e.g. where the injection 

wells will be drilled) should still be required. Data regarding all USDWs in the 

AoR will likely be costly and/or difficult to collect and, except as noted 

above, the usefulness of those data seems questionable. 

Accordingly, TxCCSA suggests that subparagraph (f) should be modified as 

follows: 

(f) Maps and stratigraphic cross sections indicating the general 

vertical and lateral limits of all THE LOWERMOST USDWs, ALL USDWS IN 

THE IMMEDIATE VICINITY OF THE PROPOSED INJECTION WELL(S), water wells 

and springs within the area of review, their positions relative to the 

injection zone(s) and the direction of water movement, where known; 

EPA Proposed : §146.82(l) The results of the formation testing program 

as required in paragraph (j) of this section; 

(r) All available logging and testing program data on the well required 

by § 146.87; 

(s) A demonstration of mechanical integrity pursuant to § 146.89; 

The requirements of subparts (l), (r) and (s) of § 146.82 cannot be met until 

after the well is drilled. For example, subparagraph (l) references (j), 

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23969

464
formation testing. Clearly formation testing is a drilling or post completion 

operation. Similarly, logging and mechanical integrity testing also are drilling 

or post well completion operations. Because this information will be collected 

post application approval, it should not be required prior to the granting of 

the Class VI permit. 

TxCCSA suggests that EPA modify § 146.82 to eliminate subparts (l), (r) and (s) 

because those data do not belong in and in fact may not be available as part of 

a permit application. 

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be 

available at the time the owner or operator develops their initial permit application. In response to 

comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this 

subpart so that the final regulation specifies separate requirements for information to be submitted with 

the permit application and before well construction is approved (at §146.82(a)) and information to be 

submitted before operation of the well is authorized (at §146.82(c)). 

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of 

information to be submitted. In addition, section §146.82 in the final rule is similar to the permit 

application requirements for other injection well classes, which could help avoid confusion about how to 

meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to 

be submitted before operation of the well is authorized are very similar to those for Class I wells, with 

modifications and additions that address the unique challenges and types of data collected for GS wells.

Additionally, EPA disagrees with the commenter that there is no justification to require maps and 

stratigraphic cross sections for the entire extent of those USDWs above the lowermost USDW. EPA 

believes a thorough understanding of the hydrogeologic conditions of all USDWs in the AoR is 

necessary. EPA clarifies that §146.82(a)(5) requires, as part of the site characterization and permit 

application process, that operators submit maps and cross sections indicating the general vertical and 

lateral limits of all USDWs within the area of review. This information will result in information on and 

a characterization of the number, location and depth of USDWs. The Director has the authority to 

request additional hydrogeologic data or other data on USDWs as well. 

Other EPA Comment Codes and Descriptions: 3330 2.2.1.3 Applicability /adequacy of 

computational models (seeking comment) 

Comment: 3. §146.84 Area of review and corrective action. 

EPA’s proposed rule allows each applicant to define the Area of Review ("AoR") 

associated with the sequestration project. TxCCSA has no objection to this 

flexible approach as it allows the size and shape of the AoR to reflect the 

unique geology of each CO2 sequestration project. However, under §146.84 (a), to 

define the AoR, an applicant must use a model capable of considering the 

physical and chemical properties of all phases of the injected carbon dioxide 

stream. TxCCSA is uncertain that there is a model that can satisfy this 

requirement. Accordingly, TxCCSA suggests that the proposed rule be amended as 

follows: 

§146.84 Area of review and corrective action. (a) The area of review is 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23970

465
the region surrounding the geologic sequestration project that may be 

impacted by the injection activity. The area of review is based on 

computational modeling that, TO THE EXTENT PRACTICABLE AND TO THE EXTENT 

DETERMINED TO BE NECESSARY BY THE DIRECTOR, accounts for the MATERIAL 

physical and chemical properties of all CRITICAL phases of the 

injected carbon dioxide stream. 

Response: EPA disagrees that available multiphase models cannot consider the physical and chemical 

properties of all phases of the injected CO2 stream. Research, as discussed in the preamble to the 

proposed GS regulation and the associated background document "Computational Modeling of 

Underground Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk to 

Underground Sources of Drinking Water" (cited in the proposed rule preamble as USEPA, 2008d), 

substantiates the modeling requirements in the GS regulation and indicates that technology has advanced 

to the point that a CO2 injection project can be adequately modeled to support both prediction and 

tracking the movement of the CO2 plume and pressure front. EPA believes the Director should have 

discretion to evaluate each plan based on current, state of the art modeling science because there are 

large numbers and types of available models and because advances in the field of geologic modeling 

continue. 

Based on review of all public comments on the AoR definition at 146.84(a), the Agency has modified it 

to read as follows: The region surrounding the geologic sequestration project where USDWs may be 

endangered by the injection activity. The area of review is delineated using computational modeling that 

accounts for the physical and chemical properties of all phases of the injected CO2 stream and is based 

on available site characterization, monitoring, and operational data. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: TxCCSA suggests the following revision: 

§146.86 (b) Casing and Cementing of Class VI Wells. (3) At least one 

long string casing, using a sufficient number of centralizers, must 

extend to the injection zone and must be cemented by circulating cement 

across the surface INJECTION ZONE AND CONFINING ZONE AND AN 

AUTHORIZED DISTANCE ABOVE THE CONFINING ZONE, SUBMITTED BY THE PERMITTEE 

AND APPROVED BY THE DIRECTOR in one or more stages. 

* 

* 

* 

(5) TO PROTECT USDWS, CCement and cement additives must be 

compatible with the carbon dioxide stream and formation fluids and of 

sufficient quality and quantity to maintain integrity over the 

design OPERATING life of the WELL geologic sequestration project 

MUST BE USED THROUGH THE INJECTION ZONE AND CONFINING ZONE. The 

integrity and location of the cement shall be verified using technology 

capable of evaluating cement quality radially and identifying the 

location of channels to ensure that USDWs are not endangered. 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23973

466
Response: EPA disagrees that the casing, cement or other materials should only be designed for the 

period of the injection process, rather than the life of the sequestration project. GS projects are 

anticipated to have long life spans in comparison to other types of deep injection wells. Not only must 

Class VI wells be able to function safely and properly over the lifespan of the GS project, but they must 

be constructed such that USDWs remain protected after well plugging. The requirements at §146.86 will 

ensure that the well can maintain integrity throughout the proposed life span of the project, including 

after the injection well is plugged and through post-injection site care period and beyond. While the risk 

profile of a GS site will decrease following cessation of injection, EPA believes that Class VI wells must 

be designed to protect USDWs from endangerment for the life of the project. Furthermore, rigorous 

casing and cementing help ensure that the Class VI well will not serve as a conduit for movement of 

fluids associated with future injection operations. EPA believes that the requirements for long-string 

casing are appropriate and offer appropriate flexibility: §146.86(b)(3) requires that the long-string casing 

extend to the injection zone and be cemented by circulating cement to the surface in one or more stages. 

It does not, however, specify how cementing would be accomplished, and gives flexibility to the owner 

or operator to propose alternate methods to provide a sufficient amount of cement to meet the standard 

that USDWs are protected from endangerment, subject to the approval of the Director. 

Additionally, EPA is developing guidance on the construction of Class VI wells. This guidance will be 

available on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: cement. The rules should be modified to allow the permittee to select between 

the specified logs and any other logging tool approved by the Director as 

follows: 

§146.87(a)(2)(ii) A cement bond and variable density log OR OTHER 

APPROVED TOOL, and OR a temperature log after the casing is set and 

cemented. [see § 146.12(d)(2)(i)(B) CRITERIA AND STANDARDS APPLICABLE TO 

CLASS I NONHAZARDOUS WELLS: CONSTRUCTION REQUIREMENTS.] 

* 

* 

* 

(5) Any alternative methods that provide equivalent or better 

information and that are required of and/or approved of by the Director. 

THE DIRECTOR MAY WAIVE ANY LOG OR TEST SPECIFIED IN THIS SUBPARAGRAPH. 

Response: Cement bond, variable density, and temperature logs are required by §146.87(a)(2) upon 

installation of the surface casing. EPA disagrees that the surface casing logging requirements are 

excessive. Evaluation of all logs, surveys, and tests listed in the rule will provide detailed information on 

the parts of the well that will penetrate the lowermost USDW and provide information on the quality of 

the cement seal with surrounding formations in order to ensure protection of USDWs from 

endangerment. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23975

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23977

467
CFR 146.87) 

Comment: The proposed rule also requires unnecessary and duplicative logging with respect 

to the long-string casing. 

EPA Proposed §146.87(a)( (3) Before and upon installation of the long 

string casing: (ii) A cement bond and variable density log, and a 

temperature log after the casing is set and cemented. 

TxCCSA suggests that the logging options it recommends with respect to surface 

casing also apply for the long-string casing. Thus, the proposed rule should be 

revised as follows: 

§146.87(a)(3)(ii) A cement bond and variable density log OR OTHER 

APPROVED TOOL, and OR a temperature log after the casing is set and cemented. 

[see § 146.12(d)(2)(ii)(C) CRITERIA AND STANDARDS APPLICABLE TO CLASS I 

NONHAZARDOUS WELLS: CONSTRUCTION REQUIREMENTS.] 

Response: EPA disagrees that the requirements for logging of the long-string casing at §146.87(a)(3)(ii) 

are unnecessary. While the tests do provide information on some of the same items, the tests provide 

unique pieces of information which enhance each other and allow for interpretations not possible with a 

single test. For example, a variable density log can detect microannuli, fractures, and formation effects. 

Temperature logs can detect fluid or gas flow through channels that cannot be detected by either of the 

other tests. 

Determining the quality of the cementing of the long-string casing is essential to the protection of 

USDWs from endangerment. EPA adds that should alternative methods be shown to provide equivalent 

or better information, the Director may allow such alternatives under §146.87(a)(5). 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: TxCCSA suggests the following: 

§146.87(b) AT THE SPECIFIC REQUEST OF THE DIRECTOR AND ONLY WHERE CORE 

RETRIEVAL IS POSSIBLE, TThe owner or operator must take and submit 

to the Director A whole cores or sidewall cores of the injection zone 

and confining system and formation fluid samples from the injection 

zone(s). The Director may accept cores from nearby wells if the owner 

or operator can demonstrate that core retrieval is not possible and that 

such cores are representative of conditions at the well. The Director 

may require the owner or operator to core other formations in the 

borehole. 

Response: As described above, EPA clarifies that §146.87(b) allows information on cores from nearby 

wells to be submitted if the owner or operator can demonstrate that core retrieval is not possible and that 

cores from nearby wells are representative of conditions at the Class VI well. EPA clarifies that, at a 

minimum, reports on cores of injection zones, confining zones, and samples of formation fluids must be 

submitted. Section 146.87(b) gives the Director authority to require the owner or operator to core other 

formations in the borehole if necessary to provide sufficient geologic information to verify that the site 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23980

468
is suitable for GS. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: EPA Proposed §146.87(f) The owner or operator must provide the Director 

with the opportunity to witness all logging and testing by this subpart. 

The owner or operator must submit a schedule of such activities to the 

Director 30 days prior to conducting the first test and submit any 

changes to the schedule 30 days prior to the next scheduled test. 

The agency requires the submission of a proposed logging and testing schedule at 

least 30 days in advance of those proposed activities. Although a logging and 

testing schedule certainly can be designed 30 or more days in advance, the 

actual date that logging is performed is usually available only 24 to 48 hours 

in advance of actual logging operations. A mandatory 30 day notice is simply not 

practical for logging and testing. 

TxCCSA asks that notice requirements in this subpart be adjusted to take into 

account the practical limitations experienced routinely in field operations. 

Suggested revised language is set forth below. 

§146.87(f) The owner or operator must provide the Director with the 

opportunity to witness all logging and testing by this subpart. The 

owner or operator must submit a PROPOSED schedule of such activities to 

the Director AT LEAST 30 days prior to conducting the first test and 

submit NOTICE AT LEAST 24 HOURS IN ADVANCE OF THE CONDUCT OF ANY ACTUAL 

LOGGING AND TESTING. any changes to the schedule 30 days prior to the 

next scheduled test. 

Response: EPA disagrees that the 30-day notification requirement is unreasonable. The 30-day 

notification mirrors the current requirement for logging and testing of new Class I wells, as described in 

§146.66. Acknowledging the developing nature of CO2 GS, EPA believes that involvement by the 

permitting authority in each project will provide much needed field data for assurance of USDW 

protection from endangerment and will help update and refine the permitting process. Adequate timing 

of notification will ensure the Director's ability to be involved. 

Other EPA Comment Codes and Descriptions: 4100 2.4.1 Injection parameters 

Comment: problem. The suggested revision is encapsulated below: 

(c) The owner or operator must fill the annulus between the tubing and 

the long string casing with a non-corrosive fluid approved by the 

Director. IF THE DIRECTOR DETERMINES THAT SUCH REQUIREMENT WILL NOT HARM 

THE INTEGRITY OF THE WELL, Tthe owner or operator must maintain A 

POSITIVE PRESSURE on the annulus a pressure that exceeds the 

operating injection pressure. ., unless the Director determines that 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23982

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23984

469
such requirement might harm the integrity of the well.

Response: As described above, EPA disagrees that maintaining annulus pressures that exceed the 

injection pressure would cause bursting of the casing. Therefore, EPA disagrees with the suggested 

revision. 

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells 

(seeking comment) 

Comment: EPA Proposed §146.88(e) The owner or operator must install and use 

continuous recording devices to monitor: The injection pressure; the 

rate, volume, and temperature of the carbon dioxide stream; and the 

pressure on the annulus between the tubing and the long string casing 

and annulus fluid volume; and must install and use alarms and automatic 

down-hole shut-off systems, designed to alert the operator and shut-in 

the well when operating parameters such as annulus pressure, injection 

rate or other parameters approved by the Director diverge beyond 

permitted ranges and/or gradients specified in the permit; 

The installation and use of automatic down-hole shut-off systems creates a 

potential avenue for leakage and is unnecessary on land-based onshore systems. 

Down-hole shut-off systems, more commonly used in off-shore operations, serve to 

shut in the well and prevent reservoir fluids from exiting the wellbore. They 

are used in off-shore operations because of the risk of damage to the wellhead 

from atmospheric or anthropogenic phenomenon, such as a hurricane causing 

extensive platform damage or a ship colliding with a platform. But in an onshore 

injection system, a down-hole shut-off system will not determine or deter 

leakage of fluids in the wellbore and therefore is not effective in protecting 

USDWs. Also, the likelihood of damage to an onshore wellhead is extremely 

remote. The greater risk in a Class VI onshore operation is that the mechanics 

of the down-hole shut-off system will be compromised or malfunction. Such a 

malfunction would require removal of the tubing and shut-off system equipment, 

thereby creating a potential unwanted migration path. The use of automatic downhole shut-off systems should be limited to off-shore operations. 

Furthermore, the requirement to continuously monitor the annulus fluid volume is 

impractical, because it does not provide any meaningful data regarding potential 

problems with the operation of the well. Requiring the continuous monitoring of 

the amount of annulus fluid added during operations is more practical and will 

reveal potential leakage paths. TxCCSA recommends the following: 

§146.88(e) The owner or operator must install and use continuous 

recording devices to monitor: The injection pressure; the rate, volume, 

and temperature of the carbon dioxide stream; and the pressure on the 

annulus between the tubing and the long string casing and THE VOLUME 

OF annulus fluid added to the annulus VOLUME; and the owner or 

operator must install and use alarms and automatic DOWN-HOLE shut-off 

systems, designed to alert the operator and shut-in off the well when 

operating parameters such as annulus pressure, injection rate or other 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23986

470
parameters approved by the Director diverge beyond permitted ranges 

and/or gradients specified in the permit. IF THE OPERATION INVOLVES 

OFF-SHORE INJECTION, THE OWNER OR OPERATOR MUST INSTALL AND USE ALARMS 

AND AUTOMATIC DOWN-HOLE SHUT-OFF SYSTEMS, DESIGNED TO ALERT THE 

OPERATOR 

AND SHUT-IN THE WELL IF THE WELLHEAD IS DAMAGED OR WHEN OPERATING 

PARAMETERS SUCH AS ANNULUS PRESSURE, INJECTION RATE OR OTHER PARAMETERS 

APPROVED BY THE DIRECTOR DIVERGE BEYOND PERMITTED RANGES AND/OR 

GRADIENTS SPECIFIED IN THE PERMIT; 

(f) If aN down-hole automatic shutdown is triggered or a loss of 

mechanical integrity is discovered, the owner of operator must 

immediately investigate and identify as expeditiously as possible the 

cause of the shutoff. 

Response: After evaluating the risks and benefits of down-hole shut-off systems and considering 

additional research, EPA will not require automatic down-hole shut-off devices for onshore Class VI 

wells since it is not necessary in all cases to ensure protection of USDWs from endangerment. Instead, 

the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells install 

automatic surface shut-off devices. The rule affords Director's discretion to mandate automatic downhole shut-off devices in onshore situations that may warrant their use. 

The GS rule, at §146.88(e)(3), requires the installation of down-hole shut-off devices for Class VI wells 

located in the offshore submerged lands within the jurisdiction of a State UIC program. The Agency 

believes that the unique construction and operational conditions for offshore Class VI wells, including 

isolation from shorelines and the need to construct wells through the water column and the subsurface, 

may delay response time in the event of well difficulties. These conditions merit requiring automatic 

down-hole shut-off devices for offshore wells in the submerged lands of a State. 

EPA believes that requiring the installation of automatic surface shut-off devices for onshore wells (and 

affording Director's discretion to require down-hole devices where necessary) and automatic down-hole 

shut-off devices for offshore wells in submerged lands within the jurisdiction of a State ensures that 

proper precautions are taken to prevent subsurface fluid movement and ensure protection of USDWs. 

Regarding annulus fluid volume, EPA believes that knowing annulus fluid volume, as required at 

§146.88(e), is a necessary component of monitoring well mechanical integrity, but believes that 

monitoring the annulus fluid volume added is sufficient to meet the intent of continuous monitoring of 

the pressure on the annulus. The final GS rule at §146.90 (b) requires that owners or operators use 

continuous recording devices to monitor injection pressure, rate and volume; the pressure on the annulus 

between the tubing and the long string casing; and the annulus fluid volume added. 

Other EPA Comment Codes and Descriptions: 4500 2.5 Proposed Mechanical Integrity Testing 

(MIT) Requirements (40 CFR 146.89) 

Comment: 7. § 146.89 Mechanical integrity. 

EPA Proposed §146.89(c) At least once per year, the owner or operator 

must use one of the following methods to determine the absence of 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23987

471
significant fluid movement under paragraph (a)(2) of this section: 

(3) A casing inspection log, if required by the Director. 

Among the test protocols prescribed by the proposed rule to confirm lack of 

significant fluid movement is a casing inspection log. Although this log is 

optional, it may be required by the Director. Conducting a casing inspection log 

will require the tubing to be pulled from a well, and that in turn substantially 

increases the possibility of a well control event (that is a loss of control 

over well operation). Accordingly, the technique should only be mandated when 

other testing methodologies are unavailable. TxCCSA suggests the following edit: 

§146.89(c) At least once per year, the owner or operator must use one of 

the following methods to determine the absence of significant fluid 

movement under paragraph (a)(2) of this section: 

(3) A casing inspection log, if A TRACER SURVEY OR A TEMPERATURE OR 

NOISE LOG CANNOT BE OBTAINED AND A CASING INSPECTION LOG IS THUS 

required by the Director. 

Response: EPA agrees that the casing inspection log is not an appropriate test to detect fluid movement 

behind the casing, but clarifies that it is a technique that can be used to determine the presence or 

absence of corrosion of the long-string casing, and is required if the Director determines that it is 

necessary based on site-specific information. EPA has revised the final GS rule to require that the 

frequency of the casing inspection log be specified in the approved testing and monitoring plan at 

§146.89(d). 

Other EPA Comment Codes and Descriptions: 4630 2.6.3 Corrosion monitoring 

Comment: EPA Proposed §146.90(c) Corrosion monitoring of the well materials for 

loss of mass, thickness, cracking, pitting and other signs of corrosion 

must be performed on a quarterly basis to ensure that the well 

components meet the minimum standards for material strength and 

performance set forth in § 146.86(b) by: 

(1) Placing coupons of the well construction materials in contact with 

the carbon dioxide stream; or 

(2) Routing the carbon dioxide stream through a loop constructed with 

the material used in the well; or 

(3) Using an alternative method approved by the Director; 

TxCCSA believes the requirements in EPA proposed §146.90(c) related to corrosion 

monitoring are inapplicable. In the vast majority of cases, the CO2 will be 

transported to the injection site through pipelines, will be dehydrated prior to 

transportation and therefore when injected it will be non-corrosive.[FN2] In those 

instances, the test methods described in § 146.90(c)(1) and (c)(2) (except of 

course alternatives approved by the Director) will not provide meaningful 

information regarding the mechanical integrity of down-hole casing, tubing and 

other equipment because the CO2 will simply not be corrosive at the surface. 

Consequently, to have any relevance such requirements should be reserved for 

situations where water saturated CO2 is being injected. 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23989

472
[FN2: For evidence on CO2 corrosivity in the absence of free water see Don 

Duttlinger, Enhanced Recovery Intertwines Naturally With CO2 Sequestration, Tech 

Connections Column, January 2004, American Oil and Gas Reporter, available at 

http://www.pttc.org/aogr_columns_archived/aogrcojan04.htm (From the 

processing/injection standpoint, CO2 is noncorrosive as long as it is dry. 

Proving that point, Kinder Morgan has hydro-tested the 32-year-old CRC Pipeline 

built in 1971 to transport CO2. Only one minor failure occurred. After testing, 

the line was rated for 2,025 psi maximum operating pressure, which established a 

200 psi increase over most recent ratings); see J. Layne, Results of the 

Hydrotest of the 30-year old Canyon Reef Carriers CO2 Pipeline, 2003 CO2 

Flooding Conference, December 11-12, 2003, Midland,Texas (University of Texas of 

the Permian Basin’s Center for Energy and Economic Diversification).] 

§146.90(c) Corrosion monitoring of the well materials for loss of mass, 

thickness, cracking, pitting and other signs of corrosion must be 

performed on a quarterly basis to ensure that the well components 

THAT CONTACT WATER SATURATED CARBON DIOXIDE STREAMS meet the minimum 

standards for material strength and performance set forth in § 146.86(b) 

by: 

(1) Placing coupons of the well construction materials in contact with 

the carbon dioxide stream; or 

(2) Routing the carbon dioxide stream through a loop constructed with 

the material used in the well; or 

(3) Using an alternative method approved by the Director. 

THE REQUIREMENTS 

OF THIS SUBPART ARE WAIVED WHEN THE CARBON DIOXIDE STREAM IS DEHYDRATED 

TO MEET PIPELINE SPECIFICATIONS. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS rule. See the final rule and preamble 

for further discussion on EPA's final approach. 

EPA disagrees with commenters' assertions that corrosion monitoring is unnecessary or excessive. CO2 

in the presence of water (including water with NOx, SOx, and H2S impurities) can be corrosive to well 

materials and cements. Thus, although a CO2 stream may be dry, the potential for corrosion of well 

materials down-hole, where the injectate can potentially mix with water in the target formation, must be 

considered. 

Several laboratory studies and a limited number of field studies have investigated and characterized the 

effects of carbonic acid on well materials. Laboratory studies (e.g., Kutchko et al., 2007; Kutchko et al., 

2008) consistently identify alterations (typically carbonation) of cement as the result of interactions 

between cement and CO2-saturated brine. EPA believes that the testing methods specified in the rule are 

appropriate and have been used successfully by Class I hazardous waste injection well owners or 

operators. 

Currently, there are only a few analyses of cement from wells that have been in prolonged contact with 

CO2 in actual field (down-hole) conditions. Evaluation of cement from a well at the Scurry Area 

Canyon Reef Operators Committee (SACROC) site showed alteration, but did not show degradation that 

compromised the structural integrity of the cement (Carey et al., 2007). In another study, cement 

samples were collected and analyzed from a CO2 production well in a natural CO2 reservoir in 

473
Colorado exposed to a CO2-water down-hole environment for 30 years (Crow et al., 2008). The study 

found evidence of reaction between the CO2-rich water and the cement. 

Oil industry research also addresses the effects of corrosion of steel tubing and pipes. Lopez et al. (2003) 

noted that 60 percent of oilfield failures are related to the effects of carbonic acid from produced brines 

on carbon and low alloy steels. 

Laboratory investigation of cement alteration/degradation is an ongoing research area. Few field-based 

studies have been completed to date. The laboratory and field studies currently available suggest that 

corrosion problems can be managed; however, there is not a large enough body of research to rule out 

potential corrosion problems of steel components of injection wells. The IPCC (2005) report on carbon 

dioxide capture and storage reviewed oil and gas industry experience with gas injection wells, close 

industry analogues to CO2 injection wells. The report stated that while the design of CO2 injection wells 

will be very similar to gas injection wells, most down-hole components of the CO2 injection wells will 

“need to be upgraded for higher pressure ratings and corrosion resistance.” Given the pressure and 

corrosion considerations, anticipated long lifespan of a GS well and the difficulties that would be 

associated with a corrosion-related well failure, EPA believes that corrosion monitoring in the downhole environment is justified. For these reasons, the final rule requires quarterly corrosion monitoring (at 

§146.90(c)). 

The Agency plans to, every six years, collect and review data on GS projects to determine whether the 

appropriate amount and types of information and appropriate documentation are being collected, and to 

determine if modifications to the requirements are appropriate or necessary. 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: 9. § 146.92 Injection well plugging. 

EPA Proposed §146.92 (b) Well Plugging Plan. (5) The type and grade and 

quantity of material to be used in plugging. The material must be 

compatible with the carbon dioxide stream; 

The proposed regulation requires the wellbore to be flushed prior to plugging 

and thus it is unnecessary to use cement "compatible with the carbon dioxide 

stream". In the absence of water, CO2 is non-corrosive and compatible with 

conventional cements (see discussion under Comment #7). Accordingly, the rule 

should be revised as follows: 

§146.92 (b) Well Plugging Plan. (5) The type and grade and quantity of 

material to be used in plugging. The material must be compatible with 

the carbon dioxide stream; 

Response: EPA believes, considering the potentially corrosive nature of CO2 when it is in contact with 

water, that the requirement that the material must be compatible with the CO2 stream is appropriate. The 

final rule retains this requirement because CO2 and water will be present in the subsurface. 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23992

Commenter Name: Darrick Eugene Letter ID: 0223

474
Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93); 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Director affirmatively acts to extend the post-injection site care period. These 

changes are contained in the suggested text below: 

§ 146.93 Post-injection site care and site closure. 

(a) The owner or operator of a Class VI well must prepare, maintain, and 

comply with a plan for post-injection site care and site closure that 

meets the requirements of paragraph (a)(2) of this section and is 

acceptable to the Director. 

(1) The owner or operator must submit the post-injection site 

care and site closure plan as a part of the permit application to be 

approved by the Director. 

(2) The post-injection site care and site closure plan must 

include the following information: 

(i) The pressure differential between pre-injection and 

predicted post-injection pressures in the injection zone; 

(ii) The predicted position of the carbon dioxide plume 

and associated pressure front at site closure as demonstrated in 

the area of review evaluation required under § 146.84(b); 

(iii) A description of post-injection monitoring 

location, methods, and proposed frequency; and 

(iv) A proposed schedule for submitting post-injection 

site care monitoring results to the Director. 

(3) Upon cessation of injection, owners or operators of Class VI 

wells must either submit an amended post-injection site care and site 

closure plan or demonstrate to the Director through monitoring data and 

modeling results that no amendment to the plan is needed. 

(4) The owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval 

within 30 days of such change. 

(b) The owner or operator shall monitor the site following the cessation 

of injection to show the position of the carbon dioxide plume and 

pressure front and demonstrate that USDWs are not being endangered. 

* 

* 

* 

(3) Prior to authorization for THE EXPIRATION OF THE PERIOD 

SPECIFIED IN SUBPART (B)(1), site closure, the owner or operator 

must submit to the Director a demonstration, based on monitoring and 

other site specific data, that the carbon dioxide plume and pressure 

front have stabilized and that no additional monitoring is needed to 

assure that the geologic sequestration project does not pose an 

endangerment to USDWs. 

(4) IF WITHIN 180 DAYS AFTER THE SUBMITTAL OF THE DATA REQUIRED 

UNDER SUBPARAGRAPH (3), THE DIRECTOR DETERMINES THAT THE GEOLOGICAL 

SEQUESTRATION PROJECT MAY CONTINUE TO POSE AN ENDANGERMENT TO USDWS, 

HE 

SHALL SO NOTIFY THE OWNER OR OPERATOR OF HIS DETERMINATION AND THE BASIS 

THEREFORE, AND If such a demonstration cannot be made (i.e., if the 

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23994

475
carbon dioxide plume and pressure front have not stabilized) after the 

50-year period, the owner or operator must submit to the Director a 

plan to continue post-injection site care. 

(5) IF WITHIN 180 DAYS AFTER THE SUBMITTAL OF THE DATA REQUIRED 

UNDER SUBPARAGRAPH (3) ABOVE THE DIRECTOR FAILS TO DETERMINE AND TO 

NOTIFY THE OWNER OR OPERATOR THAT THE GEOLOGICAL SEQUESTRATION PROJECT 

MAY CONTINUE TO POSE AN ENDANGERMENT TO USDWS, SITE CLOSURE SHALL BE 

DEEMED AUTHORIZED BY RULE 

(c) Notice of intent for site closure. The owner or operator must notify 

the Director at least 120 days before site closure. At this time, if any 

changes have been made to the original post- injection site care and 

site closure plan, the owner or operator must also provide the revised 

plan. At the discretion of the Director, a shorter notice period may be 

allowed. 

(d) After the Director has authorized site closure OR SITE CLOSURE IS 

AUTHORIZED BY RULE, the owner or operator must plug all monitoring wells 

in a manner which will not allow movement of injection or formation 

fluids that endangers a USDW. 

(e) Once the Director has authorized site closure, OR SITE CLOSURE IS 

AUTHORIZED BY RULE, the owner or operator must submit a site closure 

report within 90 days that must thereafter be retained at a location 

designated by the Director. The report must include: 

(1) Documentation of appropriate injection and monitoring well 

plugging as specified in § 146.92 and paragraph (c) of this section. The 

owner or operator must provide a copy of a survey plat which has been 

submitted to the local zoning authority designated by the Director. The 

plat must indicate the location of the injection well relative to 

permanently surveyed benchmarks. The owner or operator must also submit 

a copy of the plat to the Regional Administrator of the appropriate EPA 

Regional Office; 

(2) Documentation of appropriate notification and information to 

such State, local and tribal authorities as have authority over drilling 

activities to enable such State and local authorities to impose 

appropriate conditions on subsequent drilling activities that may 

penetrate the injection and confining zone(s); and (3) Records 

reflecting the nature, composition and volume of the carbon dioxide 

stream. 

(f) Each owner or operator of a Class VI injection well must record a 

notation on the deed to the facility property or any other document that 

is normally examined during title search that will in perpetuity provide 

any potential purchaser of the property the following information: 

(1) The fact that land has been used to sequester carbon 

dioxide; 

(2) The name of the State agency, local authority, and/or tribe 

with which the survey plat was filed, as well as the address of the 

Regional Environmental Protection Agency Office to which it was 

submitted; and 

(3) The volume of fluid injected, the injection zone or zones 

into which it was injected, and the period over which injection 

occurred. 

(g) The owner or operator must retain for three years following site 

476
closure, records collected during the post-injection site care period. 

The owner or operator must deliver the records to the Director at the 

conclusion of the retention period, and the records must thereafter be 

retained at a location designated by the Director for that purpose. 

Response: The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a 

combination of a fixed timeframe and a performance standard approach. EPA believes that a default 

PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this timeframe, combined 

with a site-specific Director’s discretion to create an alternative PISC time frame, ensures that USDWs 

are protected. The GS rule offers owners or operators flexibility regarding the duration of the PISC 

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the 

PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the 

Director discretion to allow a Class VI well owner or operator to demonstrate, based on substantial data 

during the permitting process, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c). 

EPA expects that the Director would consider the types of information the commenter describes in 

determining whether the plume and pressure front no longer pose a risk of endangerment to USDWs and 

post-injection site care monitoring may be discontinued. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will assist 

Directors in evaluating proposed well plugging plans and post-injection site care and site closure plans 

under §146.92 and §146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells; perform post-injection monitoring; demonstrate the 

appropriateness of an alternative post-injection site care time frame; demonstrate non endangerment; and 

perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3864 2.3.3.2 Use of corrosion-resistant cements 

(seeking comment) 

Comment: HEI strongly supports, with one modification discussed below, EPA’s actual 

language of the Proposed Rule in section 146.86(b)(5), which establishes a 

reliable performance standard that will achieve protection of USDWs. Section 

146.86(b)(5) states, "Cement and cement additives must be compatible with the 

carbon dioxide stream and formation fluids and of sufficient quality and 

quantity to maintain integrity over the design life the geologic sequestration 

project." HEI recommends that EPA’s discussion in the Preamble should be 

consistent with the actual language of the Proposed Rule to ensure clarity and 

remove any ambiguity regarding the performance-based approach set forth in the 

Proposed Rule. 

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21681

477
Response: The final rule does not specifically require the use of acid-resistant cements, but it requires at 

§146.86(b)(5) that cement and cement additives be compatible with the CO2 stream and formation 

fluids and of sufficient quality and quantity to maintain integrity over the design life the GS project. 

Both field and laboratory studies have found acid alteration where traditional well cements have been 

used for CO2 injection. Although the laboratory and field studies suggest that corrosion problems may 

not be severe, such problems cannot be conclusively ruled out, and the amount of available data on this 

problem is still relatively small. Laboratory investigation of cement degradation is an ongoing research 

area, and field-based studies are very few. There also does not appear to be a clear consensus at this time 

on the corrosion risks for the steel components of injection wells. Given the anticipated long lifespan of 

a Class VI well and the difficulties that would be associated with a corrosion-related well failure, EPA 

believes that the construction requirements at §146.86 are justified. 

EPA clarifies that the requirement at §146.86(b)(5) is that cement and cement additives must be 

compatible with the CO2 stream and formation fluids and of sufficient quality and quantity to maintain 

integrity over the design life of the GS project. 

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4520 2.5.1 Continuous internal mechanical integrity 

monitoring (seeking comment) 

Comment: The frequency of the monitoring should be defined not as "continuous" but as 

"regular" or "periodic" based upon site characteristics because regular 

monitoring (e.g., every minute or hour) will often be adequate. For example, 

fluid volume in the annulus is static and requires evaluation of a pressure 

pulse to determine the depth of top of fluid. Therefore, this should be 

monitored on a monthly or quarterly basis to support the pressure data. 

Response: EPA believes that continuous pressure monitoring of GS wells, instead of periodic testing, 

which is required for most other types of deep injection wells is appropriate because the potentially 

corrosive nature of CO2 injectate streams in the presence of water enables the immediate identification 

of corrosion-related internal mechanical integrity problems that could lead to significant well problems 

and failure. Continuous monitoring was found to be very important in an EPA study of UIC Class I 

internal MIT failure rates and causes (USEPA 1993). The study reviewed MIT results over a 5 year 

period and found 135 MIT failures in 428 wells (a single well can have more than one MIT failure). In 

all cases, the MIT failures were found through continuous annulus monitoring which served the 

important role of an early warning to prevent any well failure. Class VI injection wells must be equipped 

with dedicated computer-based continuous pressure monitoring devices in concert with the shut-off 

systems required for GS wells, which typically take readings several times per second and record them 

electronically in a computer system. 40 CFR §146.91(a)(2) requires that monthly averages of the 

continuous annulus monitoring be reported on a semiannual basis. 

EPA believes that monitoring of annulus fluid volume is an important method for verifying that the well 

system is intact, and knowing the annulus fluid volume is necessary for monitoring annulus pressure. 

While this requirement has until now been limited to Class I hazardous waste injection wells, the high 

volumes and supercritical nature of the injectate, the potential geomechanical stresses in the wellbore, 

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21693

478
and the potential for movement of the buoyant CO2 in the event of a MI loss make it an important safety 

consideration for GS projects. Continuous pressure monitoring allows immediate identification of 

corrosion-related well integrity loss. EPA agrees with the commenter that recording annulus fluid 

volume may not be appropriate. However, EPA believes that knowing annulus fluid volume required at 

§146.88(e) is a necessary component of monitoring well mechanical integrity, but believes that knowing 

the annulus fluid volume added is sufficient to meet the intent of the requirement. The final GS rule 

requires that owners or operators use continuous recording devices to monitor injection pressure, rate 

and volume; as well as the pressure on the annulus between the tubing and the long string casing. It also 

modifies the requirement in the proposed rule to continuously monitor annulus fluid volume; it now 

requires recording of annulus fluid volume added §§146.88(e); 146.89(b); and 146.90 (b). 

Fluid level can be detected using acoustic techniques (Schubert, 1998). The Texas Class I well 

regulations for industrial wells currently require continuous monitoring of annulus pressure and volume, 

and the majority of injection wells in Ohio conduct continuous monitoring (GWPC, 2006). At least one 

commenter indicated that the technology required for continuous monitoring is currently available and 

should not present an undue cost burden. Continuous annulus monitoring is also conducted at the 

commercial-scaled carbon capture and geologic sequestration operation at the In Salah, Algeria natural 

gas plant where more than 3 million tons of CO2 have been sequestered since 2004. The technology for 

continuous monitoring is available, is currently in fairly wide use, and the costs are not burdensome, 

especially given the operational and safety considerations addressed. 

Other EPA Comment Codes and Descriptions: 3864 2.3.3.2 Use of corrosion-resistant cements 

(seeking comment) 

Comment: BP strongly supports, with one modification discussed below, EPA’s actual 

language of the Proposed Rule in section 146.86(b)(5), which establishes a 

reliable performance standard that will achieve protection of USDWs. Section 

146.86(b)(5) states, "Cement and cement additives must be compatible with the 

carbon dioxide stream and formation fluids and of sufficient quality and 

quantity to maintain integrity over the design life the geologic sequestration 

project." BP recommends that EPA’s discussion in the Preamble should be 

consistent with the actual language of the Proposed Rule to ensure clarity and 

remove any ambiguity regarding the performance-based approach set forth in the 

Proposed Rule. 

Response: The final rule does not specifically require the use of acid-resistant cements, but it requires at 

§146.86(b)(5) that cement and cement additives be compatible with the CO2 stream and formation 

fluids and of sufficient quality and quantity to maintain integrity over the design life the GS project. 

Both field and laboratory studies have found acid alteration where traditional well cements have been 

used for CO2 injection. Although the laboratory and field studies suggest that corrosion problems may 

not be severe, such problems cannot be conclusively ruled out, and the amount of available data on this 

problem is still relatively small. Laboratory investigation of cement degradation is an ongoing research 

area, and field-based studies are very few. There also does not appear to be a clear consensus at this time 

on the corrosion risks for the steel components of injection wells. Given the anticipated long lifespan of 

a Class VI well and the difficulties that would be associated with a corrosion-related well failure, EPA 

believes that the construction requirements at §146.86 are justified. 

EPA clarifies that the requirement at §146.86(b)(5) is that cement and cement additives must be 

compatible with the CO2 stream and formation fluids and of sufficient quality and quantity to maintain 

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21731

479
integrity over the design life of the GS project.

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: 1. Schlumberger asks that the EPA expand the applicability of Class VI wells to 

cover wells injecting CO2 that is dissolved in water or brine. The current 

draft language for Section 146.81(b) states: 

This subpart applies to wells used to inject carbon dioxide specifically 

for the purpose of geologic sequestration, i.e., the long-term 

containment of a gaseous, liquid or supercritical carbon dioxide stream 

in subsurface geologic formations. 

We suggest that the EPA replace the current language with the following 

language: 

This subpart applies to wells used to inject carbon dioxide specifically 

for the purpose of geologic sequestration, i.e., the long-term 

containment of a gaseous, liquid or supercritical carbon dioxide stream 

or carbon dioxide dissolved in water or brine into subsurface geologic 

formations. 

While we recognize today the injection of dissolved CO2 raises economic 

challenges we feel that there may be cases where the injection of dissolved CO2 

will make sense both in terms of economics and in terms of leakage risk. 

Unlike separate phase CO2, CO2 dissolved in water is not less dense than the 

formation fluid and will not be subject to buoyancy driven leakage. 

Response: EPA disagrees with the suggested change. §146.81(b) reads as follows: “This subpart applies 

to any wells used to inject carbon dioxide specifically for the purpose of geologic sequestration, i.e., the 

long-term containment of a gaseous, liquid, or supercritical carbon dioxide stream in subsurface 

geologic formations.” Nothing in the rule precludes the injection of dissolved CO2, as long as the CO2 

does not meet the definition of a hazardous waste under 40 CFR part 261. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection timeframe 

(seeking comment); 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: 3. Schlumberger does not support the default post injection site care period of 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 23996

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 23998

480
50 years. We feel that because the characterization and operation of the site 

will be based on the specific attributes of the site that the length of post 

injection site care should also be site specific information. In particular the 

criteria for ending the PISC period should be based on site performance and 

risk. We support the idea that the director approves final site closure. We 

suggest the following language for Section 146.93(b)(1): 

(1) The owner or operator shall continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site 

closure plan, pursuant to the performance based criteria described in 

146.93(b)(3). 

We suggest the following language for section 146.93(b)(2) 

(2) If the owner or operator can demonstrate to the satisfaction of the 

Director that the geologic sequestration project no longer poses an 

endangerment to USDWs, the Director may approve an amendment to the 

post- injection site care and site closure plan to reduce the 

frequency of monitoring or may authorize site closure. 

And we suggest the following language for section 146.93(b)(3) 

(3) Prior to authorization for site closure, the owner or operator must 

demonstrate to the Director, based on monitoring and other sitespecific data that no additional monitoring is needed to assure that 

the geologic sequestration project does not pose an endangerment to 

USDWs, considering the following:. 

(i) the estimated magnitude and extent of the AOR based on measurements 

and modeling; (ii) that CO2 movement and pressure changes match model 

predictions, (iii) the estimated location of the detectable CO2 plume 

based on measurement and modeling (measuring magnitude of saturation 

within the plume or mapping the edge of it); (iv) that there is no 

evidence of significant leakage of either CO2 or formation fluids that 

endanger USDWs; (v) that the CO2 plume and displaced formation fluid are 

not expected to migrate in the future in a manner that encounters a 

potential leakage pathway; and, (vi) that wells at the site are not 

leaking and have maintained integrity. 

Response: The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a 

combination of a fixed timeframe and a performance standard approach. EPA believes that a default 

PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this timeframe, combined 

with a site-specific Director’s discretion to create an alternative PISC time frame, ensures that USDWs 

are protected. The GS rule offers owners or operators flexibility regarding the duration of the PISC 

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the 

PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the 

Director discretion to allow a Class VI well owner or operator to demonstrate, based on substantial data 

during the permitting process, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c). 

EPA expects that the Director would consider the types of information the commenter describes in 

481
determining whether the plume and pressure front no longer pose a risk of endangerment to USDWs and 

post-injection site care monitoring may be discontinued. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will assist 

Directors in evaluating proposed well plugging plans and post-injection site care and site closure plans 

under §146.92 and §146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells; perform post-injection monitoring; demonstrate the 

appropriateness of an alternative post-injection site care time frame; demonstrate non endangerment; and 

perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4650 2.6.5 CO2 plume and pressure front tracking 

(seeking comment) 

Comment: 4. Schlumberger supports the concept of testing and monitoring to track the CO2 

plume and the associated pressure front. We feel that without this monitoring 

the validation and updating of the models used to predict the size and shape of 

the AOR cannot be properly conducted and that the use of models to predict the 

size and shape of the AOR will be ineffective. However we feel that the 

language in section 146.90(g) is too restrictive. The current language states: 

(g) Testing and monitoring to track the extent of the carbon dioxide 

plume and the position of the pressure front by either monitoring for 

pressure changes in the first formation overlying the confining zone or 

using indirect, geophysical techniques (e.g., seismic, electrical, 

gravity, or electromagnetic surveys and/or down-hole carbon dioxide 

detection tools); 

We feel that the restrictions placed in this language could adversely impact the 

efficiency of monitoring and modeling depending on site conditions. 

Schlumberger proposes the following alternate language: 

(g) Testing and monitoring to track the extent of the carbon dioxide 

plume and the position of the pressure front by either monitoring for 

pressure changes, using geophysical techniques (e.g., seismic, 

electrical, gravity, or electromagnetic surveys and/or down-hole carbon 

dioxide detection tools), other techniques that are approved by the 

director or a combination of techniques if multiple techniques are 

deemed necessary by the director; 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 23999

482
Response: EPA has revised this requirement in the final rule. The final GS regulation, at §146.90(g)(1), 

requires all GS project owners or operators to monitor directly for pressure changes in the injection 

zone. EPA believes that pressure monitoring in the injection zone is necessary to track the development 

and movement of the pressure front and CO2 plume. In addition, §146.90(g)(2) requires owners or 

operators to track the position of the CO2 plume using indirect methods (e.g., seismic, electrical, 

gravity, or electromagnetic surveys and/or down-hole CO2 detection tools), unless the Director 

determines based on site-specific geology, that such methods are not appropriate. EPA is affording 

Director's discretion regarding the use of geophysical techniques at some sites because the Agency 

recognizes that geophysical methods are not appropriate in all geologic settings. EPA clarifies that this 

determination will be made by the Director based on the site-specific geologic information submitted by 

the owner or operator with their permit application. 

EPA believes that this approach provides flexibility to develop a site-specific monitoring plan, ensures 

that direct monitoring is available to track the movement of the CO2 and validate models, and 

recognizes that indirect techniques are not appropriate in all situations. The owner or operator's 

approved testing and monitoring plan will include the site-specific details, technologies, testing and 

monitoring frequencies, and other pertinent information. 

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in 

evaluating requirements under §146.90, including proposed monitoring plans. The guidance describes 

available technologies and recommended approaches for implementing a testing and monitoring plan, 

including pre-operational geophysical logging and testing of injection wells, MITs, injection well testing 

during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, and soil 

gas and surface air monitoring which may be required by the UIC Director for specific GS projects. The 

guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4324 2.4.4.1.2 Comments opposed to requiring 

injection below the lowermost USDW 

Comment: §144.6 Classification of wells. 

Proposed Rule:(f) Class VI. Wells used for geologic sequestration of carbon 

dioxide beneath the lowermost formation containing a USDW. 

Schlumberger Suggested Revision: (f) Class VI. Wells used for geologic 

sequestration of carbon dioxide. 

Schlumberger Rationale: We feel that sequestration can be conducted safely above 

USDWs as evidenced by the class 2 EOR experience. Also, the restriction to below 

the lowest USDW rules out many potential CCS sites. 

Response: EPA acknowledges that there are limited circumstances where injection above the lowermost 

USDW can be performed in a manner that protects USDWs from endangerment, as long as appropriate 

protections are in place. The final GS rule at §146.95 establishes a process by which owners or operators 

can seek a waiver of the Class VI injection depth requirements for injection into non-USDW formations 

above and/or between USDWs. It establishes: 1) requirements specifying information that owners or 

operators must submit, and Directors must consider, in consultation with PWSS Directors; 2) procedures 

for public notice of a waiver application and for Director-Regional Administrator communication; 3) the 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24006

483
waiver issuance process; and, 4) additional requirements that apply to owners or operators of Class VI 

wells granted a waiver of the injection depth requirements to ensure USDW protection above and below 

the injection zone. 

EPA adds that it has revised the definition of a Class VI well to read as follows: “Wells that are not 

experimental in nature that are used for geologic sequestration of carbon dioxide beneath the lowermost 

formation containing a USDW; or, wells used for geologic sequestration of carbon dioxide that have 

been granted a waiver of the injection depth requirements pursuant to requirements at §146.95 of this 

chapter; or, wells used for geologic sequestration of carbon dioxide that have received an expansion to 

the areal extent of an existing Class II enhanced oil recovery or enhanced gas recovery aquifer 

exemption pursuant to §§146.4 of this chapter and 144.7(d).” 

For additional information on the waiver approach, please see the final rule and preamble, as well as 

EPA's responses to comments on the Notice of Data Availability and Request for Comment. 

Other EPA Comment Codes and Descriptions: 2066 1.5.3.3 Grandfathering construction of Class V 

wells (seeking comment) 

Comment: §144.15 Prohibition of non-experimental Class V wells for geologic 

sequestration. 

Proposed Rule: The construction, operation or maintenance of any nonexperimental Class V geologic sequestration well is prohibited. 

Schlumberger Suggested Revision: - 

Schlumberger Rationale: We agree, there should be only one class of geologic 

sequestration well but CO2 class V wells should be grandfathered. 

Response: EPA agrees that many Class V experimental technology wells are designed and constructed 

to withstand exposure to CO2. The final GS rule provides for the construction of these wells to be 

grandfathered per §146.81(c), provided the owner or operator can demonstrate to the Director that the 

wells were engineered and constructed to meet the requirements at §146.86(a) and ensure protection of 

USDWs, in lieu of requirements at §146.86(b) and §146.87(a). EPA clarifies that only the construction 

requirements are grandfathered and that all other Class VI requirements (reporting, monitoring, 

mechnical integrity testing, etc.) must be met following a determination under §146.81(c). 

Other EPA Comment Codes and Descriptions: 4324 2.4.4.1.2 Comments opposed to requiring 

injection below the lowermost USDW 

Comment: §146.5 Classification of injection wells. 

Proposed Rule:(f) Class VI. Wells used for geologic sequestration of carbon 

dioxide beneath the lowermost formation containing an underground source of 

drinking water (USDW). 

Schlumberger Suggested Revision: (f) Class VI. Wells used for geologic 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24007

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24008

484
sequestration of carbon dioxide. 

Schlumberger Rationale: We feel that sequestration can be conducted safely above 

USDWs as evidenced by the class 2 EOR experience. Also, the restriction to below 

the lowest USDW rules out many potential CCS sites. 

Response: Please see the response to the commenter’s suggested revision to §144.6(f). 

Other EPA Comment Codes and Descriptions: 2060 1.5.3 Comments on grandfathering of existing 

wells (seeking comment); 3800 2.3 Proposed Injection Well Construction Requirements (40 CFR 

146.86) 

Comment: §146.81 Applicability. 

Proposed Rule: (c) This subpart applies to owners and operators of permit or 

rule-authorized Class I industrial, Class II, or Class V experimental carbon 

dioxide injection projects who seek to apply for a Class VI geologic 

sequestration permit for their well or wells. If the Director determines that 

USDWs will not be endangered, such wells are exempt, at the Director’s 

discretion, from the casing and cementing requirements at §§146.86(b) and 

146.87(a)(1) through (3). 

Schlumberger Suggested Revision: (c) This subpart applies to owners and 

operators of permit or rule-authorized Class I industrial, Class II, or Class V 

experimental carbon dioxide injection projects who seek to apply for a Class VI 

geologic sequestration permit for their well or wells. If the Director 

determines that USDWs will not be endangered, such wells are exempt, at the 

Director’s discretion, from the casing and cementing requirements at §§146.86(b) 

and 146.87(a)(1) through (3) if the wells were constructed prior to January 1, 

2010. 

Schlumberger Rationale: We feel that there needs to be a cutoff date for the 

grandfathering of wells so eventually all Class 6 wells are constructed to the 

same standard 

Response: EPA agrees that many Class I, Class II, and Class V experimental technology wells are 

designed and constructed to withstand exposure to CO2. The final GS rule provides for the construction 

of these wells to be grandfathered per §146.81(c), provided the owner or operator can demonstrate to the 

Director that the wells were engineered and constructed to meet the requirements at §146.86(a) and 

ensure protection of USDWs, in lieu of requirements at §146.86(b) and §146.87(a). EPA clarifies that 

only the construction requirements are grandfathered and that all other Class VI requirements (reporting, 

monitoring, mechanical integrity testing, etc.) must be met following a determination under §146.81(c). 

EPA does not plan to institute a "cut-off date" for this requirement since conversion is a site-specific 

decision. EPA believes that the requirement should be based on the specific aspects of the well's 

construction, not on the date on which it was constructed. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24009

Commenter Name: Andrew Duguid Letter ID: 0226

485
Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: Proposed Rule: Carbon dioxide stream means carbon dioxide that has been captured 

from an emission source (e.g., a power plant), plus incidental associated 

substances derived from the source materials and the capture process, and any 

substances added to the stream to enable or improve the injection process. This 

subpart does not apply to any carbon dioxide stream that meets the definition of 

a hazardous waste under 40 CFR part 261. 

Schlumberger Suggested Revision:: Carbon dioxide stream carbon dioxide that has 

been captured from an industrial process that is injected in any physical state 

or dissolved in water or brine. It includes incidental associated substances 

derived from the source materials and the capture process, and any substances 

added to the stream to enable or improve the injection process. This subpart 

does not apply to any carbon dioxide stream that meets the definition of a 

hazardous waste under 40 CFR part 261. 

Schlumberger Rationale: We want to ensure that dissolved CO2 is specifically 

allowed as it may allow a solution to the upward buoyancy drive associated with 

separate phase CO2. 

Response: EPA disagrees with the suggested edit. The final definition of carbon dioxide stream at 

§146.81(d) remains unchanged and reads as: “carbon dioxide that has been captured from an emission 

source (e.g., a power plant), plus incidental associated substances derived from the source materials and 

the capture process, and any substances added to the stream to enable or improve the injection process. 

This subpart does not apply to any carbon dioxide stream that meets the definition of a hazardous waste 

under 40 CFR part 261.” As described above, nothing in the rule precludes the injection of dissolved 

CO2, as long as the CO2 does not meet the definition of a hazardous waste under 40 CFR part 261. 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment EPA has made many revisions to the GS rule. Please see the final rule and 

preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: Proposed Rule:Geologic sequestration means the long-term containment of a 

gaseous, liquid or supercritical carbon dioxide stream in subsurface geologic 

formations. This term does not apply to its capture or transport. 

Schlumberger Suggested Revision: Geologic sequestration means the long-term 

containment of a carbon dioxide stream in subsurface geologic formations. This 

term does not apply to its capture or transport. 

Schlumberger Rationale: CO2 stream was already defined and should e used here. 

Response: EPA disagrees with the suggested change. The final definition of geologic sequestration at 

§146.81(d) reads as follows: “[T]he long-term containment of a gaseous, liquid, or supercritical carbon 

dioxide stream in subsurface geologic formations. This term does not apply to carbon dioxide capture or 

transport.” 

Commenter Organization: Schlumberger Carbon Services Comment ID: 24010

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24011

486
Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: Proposed Rule: Geologic sequestration project means an injection well or wells 

used to emplace a carbon dioxide stream beneath the lowermost formation 

containing a USDW. It includes the subsurface three-dimensional extent of the 

carbon dioxide plume, associated pressure front, and displaced brine, as well as 

the surface area above that delineated region. 

Schlumberger Suggested Revision: Geologic sequestration project means an 

injection well or wells used to emplace a carbon dioxide stream into an 

injection zone. It includes the subsurface three-dimensional extent of the 

carbon dioxide plume, associated pressure front, and displaced brine, as well as 

the surface area above that delineated region. 

Schlumberger Rationale: - 

Response: The Agency has modified the definition of geologic sequestration project at §146.81(d) to 

read as follows: “Geologic sequestration project means an injection well or wells used to emplace a 

carbon dioxide stream beneath the lowermost formation containing a USDW; or, wells used for geologic 

sequestration of carbon dioxide that have been granted a waiver of the injection depth requirements 

pursuant to requirements at §146.95; or, wells used for geologic sequestration of carbon dioxide that 

have received an aquifer exemption expansion. It includes the subsurface three-dimensional extent of the 

carbon dioxide plume, associated pressure front, and displaced brine, as well as the surface area above 

that delineated region.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: Proposed Rule: Injection zone means a geologic formation, group of formations, 

or part of a formation that is of sufficient areal extent, thickness, porosity, 

and permeability to receive carbon dioxide through a well or wells associated 

with a geologic sequestration project. 

Schlumberger Suggested Revision: Injection zone means a geologic formation, 

group of formations, or part of a formation that is of sufficient areal extent, 

thickness, porosity, and permeability to receive carbon dioxide through a well 

or wells associated with a geologic sequestration project. 

Schlumberger Rationale: - 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24012

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24013

487
Response: EPA disagrees with the suggested edit. The definition of injection zone at §146.81(d) 

remains unchanged and reads as follows: “[A] geologic formation, group of formations, or part of a 

formation that is of sufficient areal extent, thickness, porosity, and permeability to receive carbon 

dioxide through a well or wells associated with a geologic sequestration project.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: Proposed Rule: Pressure front means the zone of elevated pressure that is 

created by the injection of carbon dioxide into the subsurface. For the purposes 

of this subpart, the pressure front of a carbon dioxide plume refers to a zone 

where there is a pressure differential sufficient to cause the movement of 

injected fluids or formation fluids into a USDW. 

Schlumberger Suggested Revision: Pressure front means the zone of elevated 

pressure that is created by the injection of the carbon dioxide stream into the 

subsurface, where there is a pressure differential sufficient to cause movement 

of the carbon dioxide stream or formation fluids into a USDW. 

Response: EPA disagrees with the suggested edit. The final definition of pressure front at §146.81(d) is 

unchanged and reads as follows: “[T]he zone of elevated pressure that is created by the injection of 

carbon dioxide into the subsurface. For the purposes of this subpart, the pressure front of a carbon 

dioxide plume refers to a zone where there is a pressure differential sufficient to cause the movement of 

injected fluids or formation fluids into a USDW.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: Proposed Rule: Site closure the point/time, as determined by the Director 

following the requirements under §146.93, at which the owner or operator of a GS 

site is released from post-injection site care responsibilities. 

Schlumberger Suggested Revision: Site closure means the point/time, as 

determined by the Director following the requirements under §146.93, at which 

the owner or operator of a GS project is released from post-injection site care 

responsibilities. 

Schlumberger Rationale: Suggest using "GS project" to be consistent with other 

definitions 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24014

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24015

488
Response: EPA disagrees with the suggested edit. The final definition of site closure at §146.81(d) is 

unchanged and reads as follows: “The point/time, as determined by the Director following the 

requirements under §146.93, at which the owner or operator of a GS site is released from post-injection 

site care responsibilities.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: Proposed Rule: Transmissive fault or fracture means a fault or fracture that has 

sufficient permeability and vertical extent to allow fluids to move between 

formations. 

Schlumberger Suggested Revision: Transmissive fault or fracture means a fault or 

fracture that has sufficient permeability and vertical extent to allow fluids to 

move beyond the confining zone. 

Schlumberger Rationale: The term between formations is insufficient as it could 

also include multiple zones within a injection zone or between two zones above 

the confining unit. 

Response: EPA disagrees with the suggested edit. The final definition of transmissive fault or fracture at 

§146.81(d) is unchanged and reads as follows: “[A] fault or fracture that has sufficient permeability and 

vertical extent to allow fluids to move between formations.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82) 

Comment: §146.82 Required Class VI permit information. 

Proposed Rule: (b) A map showing the injection well(s) for which a permit is 

sought and the applicable area of review. Within the area of review, the map 

must show the number, or name and location of all injection wells, producing 

wells, abandoned wells, plugged wells or dry holes, deep stratigraphic 

boreholes, State or EPA approved subsurface cleanup sites, surface bodies of 

water, springs, mines (surface and subsurface), quarries, water wells and other 

pertinent surface features including structures intended for human occupancy and 

roads. The map should also show faults, if known or suspected. Only information 

of public record is required to be included on this map; 

Schlumberger Suggested Revision: (b) A map or electronic file (e.g. GIS file) 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24016

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24017

489
showing the injection well(s) for which a permit is sought and the applicable 

area of review. Within the area of review, the map must show the number, or name 

and location of all injection wells, producing wells, abandoned wells, plugged 

wells or dry holes, deep stratigraphic boreholes, State or EPA approved 

subsurface cleanup sites, surface bodies of water, springs, mines (surface and 

subsurface), quarries, water wells and other pertinent surface features 

including structures intended for human occupancy and roads. The map should also 

show faults, if known or suspected with surface expressions. Only information of 

public record is required to be included on this map; 

Schlumberger Rationale: This may mean more clarification. It seems strange to 

have deep faults on a surface map. Is the map to be of the surface or of the 

confining unit? Also, any map will be very busy so it may be useful to be able 

to submit an electronic file like a GIS file. 

Proposed Rule: (c) The area of review based on modeling, using data obtained 

during logging and testing of the well and the formation as required by 

paragraphs (l), (r), and (s) of this section; 

Schlumberger Suggested Revision: - 

Schlumberger Rationale: We support this but it may need to be better clarified 

that the well must e drilled prior to the permit application 

Proposed Rule: (3) Information on seismic history including the presence and 

depth of seismic sources and a determination that the seismicity would not 

interfere with containment; 

Schlumberger Suggested Revision: (3) Information on seismic history of the area 

including the presence and depth of seismic sources and a determination that the 

seismicity would not interfere with containment; 

Schlumberger Rationale: It seems like this requirement is at a larger scale than 

the AOR (maybe a regional scale) than the other requirements. This should be 

specified. 

Proposed Rule: (4) Data on the depth, areal extent, thickness, mineralogy, 

porosity, permeability and capillary pressure of the injection and confining 

zone(s); including geology/facies changes based on field data which may include 

geologic cores, outcrop data, seismic surveys, well logs, and names and 

lithologic descriptions; 

Schlumberger Suggested Revision: (4) Data on the depth, areal extent, thickness, 

mineralogy, porosity, permeability and capillary entry pressure of the injection 

and confining zone(s); including geology/facies changes based on field data 

which may include geologic cores, outcrop data, seismic surveys, well logs, and 

names and lithologic descriptions; 

Schlumberger Rationale: Should this include capillary pressure or capillary 

entry pressure? 

490
Proposed Rule: (e) A tabulation of all wells within the area of review which 

penetrate the injection or confining zone(s). Such data must include a 

description of each well's type, construction, date drilled, location, depth, 

record of plugging and/or completion, and any additional information the 

Director may require; 

Schlumberger Suggested Revision: - 

Schlumberger Rationale: How will this be handled if all of this data is not 

available for each well? 

Proposed Rule: (f) Maps and stratigraphic cross sections indicating the general 

vertical and lateral limits of all USDWs, water wells and springs within the 

area of review, their positions relative to the injection zone(s) and the 

direction of water movement, where known; 

Schlumberger Suggested Revision: In 

Schlumberger Rationale: - 

Proposed Rule: (g) Baseline geochemical data on subsurface formations, including 

all USDWs in the area of review; 

Schlumberger Suggested Revision: (g) Baseline geochemical data on subsurface 

formations, including all USDWs and geochemically monitored in the area of 

review; 

Schlumberger Rationale: All formations that are or may need to be geochemically 

monitored should be included 

Response: EPA agrees that deep faults would not be expressed on a surface map, but information on 

such faults should be provided in cross sections, which are also required as part of the materials that 

support a permit application. 

EPA agrees that submittal of support information electronically is beneficial. The final GS rule requires 

owners or operators to submit permit applications, including supporting information, to EPA in an 

electronic format (§146.91(e)). 

Regarding seismic information, EPA acknowledges that, due to the nature of seismic events and records, 

available information would likely address an area that is larger than the delineated AoR. EPA clarifies 

that the intent of this requirements is to ensure that the Director has sufficient information on which to 

base a determination of the suitability of a potential project site for GS. 

EPA clarifies that information on capillary entry pressure must be submitted. EPA believes that capillary 

entry pressure measurements on core samples are necessary to quantify the amount of buoyant force the 

confining zone can maintain before failure (World Resources Institute, 2008). 

Regarding the requirement to submit tabulations of all wells within the AoR, EPA acknowledges that 

public records may not contain data on every artificial penetration in the AoR (or all of the data on each 

well that is required for the tabulation), particularly in areas with many older wells. However, EPA notes 

that the inventory and review process for GS wells required at §146.84(c)(2) is similar to what is 

491
required of Class I and Class II injection well operators, that the AoR and corrective action process for 

these well types has been successful for many years. EPA adds that the Director has the discretion to 

require the owner or operator to supplement a data records search, including requiring ground or 

airborne surveys for wells, if there is reason to believe, based on knowledge of the site or of available 

data bases, that the incompleteness of available information could compromise USDW protection from 

endangerment. 

Regarding baseline geochemical data, EPA is not specifying for which formations this information 

should be submitted to allow flexibility, but examples may include the following formations: a) the 

injection zone, b) the confining zones, c) containment zones above the confining zones in which any 

potentially migrating CO2 could be trapped, d) all USDWs, and e) any other geologic zone or formation 

that is important to the proposed monitoring program. The Director has the authority to request 

additional geochemical data as well. 

EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available 

at the time the owner or operator develops their initial permit application. In response to comments and 

based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that 

the final regulation specifies separate requirements for information to be submitted with the permit 

application and before well construction is approved (at §146.82(a)) and information to be submitted 

before operation of the well is authorized (at §146.82(c)). 

EPA is developing guidance on site characterization for GS projects to assist owners or operators and 

Directors in evaluating permit requirements and applications under §146.82. The guidance provides 

recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site 

as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the 

injection and confining zone. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: §146.83 Minimum criteria for siting. 

Proposed Rule: (2) A confining zone(s) that is free of transmissive faults or 

fractures and of sufficient areal extent and integrity to contain the injected 

carbon dioxide stream and displaced formation fluids and allow injection at 

proposed maximum pressures and volumes without initiating or propagating 

fractures in the confining zone(s); and 

Schlumberger Suggested Revision: - 

Schlumberger Rationale: We support this language as it is written. 

Response: EPA acknowledges the comment and the final rule retains the text at §146.83 as proposed. 

Other EPA Comment Codes and Descriptions: 3120 2.1.2 Need to identify additional confining and 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24018

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24019

492
containment zones (seeking comment) 

Comment: Proposed Rule: (b) At the Director’s discretion, owners or operators of Class VI 

wells must identify and characterize additional zones that will impede vertical 

fluid movement, are free of faults and fractures that may interfere with 

containment, allow for pressure dissipation, and provide additional 

opportunities for monitoring, mitigation and remediation. 

Schlumberger Suggested Revision: (b) Owners or operators of Class VI wells must 

identify and characterize some additional zones, if they exist, that will impede 

vertical fluid movement, allow for pressure dissipation, and provide additional 

opportunities for monitoring, mitigation and remediation. Vertical faults and 

fractures that transect these zones must be identified. 

Schlumberger Rationale: We believe that a site with a single confining can 

provide storage integrity, however, we feel that if there are additional 

confining layers at the site they should be characterized to get a better 

estimate of leakage risk to USDWs and possibly identify additional monitoring 

zones. 

Response: EPA retains the requirement to identify additional containment/confining zones, if required 

by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be 

needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on 

his or her understanding of a particular site. EPA believes that, in some situations, the presence of 

additional confining and containment zones above the primary (i.e., lowermost) confining zone can 

improve USDW protection. These layers could further impede vertical fluid movement and allow for 

pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The 

Agency's decision is supported by commenters representing states, water associations, and an electric 

utility who assert that these requirements promote a flexible, risk-based, site-specific approach to 

characterizing and permitting a site for GS projects, and are intended to improve understanding of the 

project as a whole and promote better modeling of the site. 

Other EPA Comment Codes and Descriptions: 3200 2.2 Proposed Area of Review and Corrective 

Action Requirements (40 CFR 146.84) 

Comment: §146.84 Area of review and corrective action. 

Proposed Rule: (a) The area of review is the region surrounding the geologic 

sequestration project that may be impacted by the injection activity. The area 

of review is based on computational modeling that accounts for the physical and 

chemical properties of all phases of the injected carbon dioxide stream. 

Schlumberger Suggested Revision: (a) The area of review is based on 

computational modeling that accounts for physical and the chemical properties of 

all phases of the injected carbon dioxide stream, the associated pressure 

front, and displaced brine. 

Schlumberger Rationale: - 

Response: Based on review of all public comments on the AoR definition at 146.84(a), the Agency has 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24020

493
modified it to read as follows: The region surrounding the geologic sequestration project where USDWs 

may be endangered by the injection activity. The area of review is delineated using computational 

modeling that accounts for the physical and chemical properties of all phases of the injected CO2 stream 

and is based on available site characterization, monitoring, and operational data. The definition in the 

proposed rule accounted for the varying physical and chemical properties of the CO2 including freephase and water-dissolved CO2, as the commenter suggests. The definition in the final rule will continue 

to do so. 

EPA is developing guidance on AoR and corrective action at GS Class VI sites to assist owners or 

operators and Directors in evaluating requirements and proposed AoR and corrective action plans under 

146.84. The guidance describes EPA's recommended approaches for the data to be considered in an 

initial AoR delineation, how to apply computational modeling to delineate the AoR, performing 

corrective action at GS sites, and, when appropriate, completing AoR reevaluations. The guidance will 

be available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action; 3530 2.2.3.1 AoR 

reevaluation frequency (seeking comment) 

Comment: Proposed Rule: (b) The owner or operator of a Class VI well must prepare, 

maintain, and comply with a plan to delineate the area of review for a proposed 

geologic sequestration project, periodically reevaluate the delineation, and 

perform corrective action that meets the requirements of this section and is 

acceptable to the Director. As a part of the permit application for approval by 

the Director, the owner or operator must submit an area of review and corrective 

action plan that includes the following information: 

Schlumberger Suggested Revision: (b) The owner or operator of a Class VI well 

must prepare, maintain, and comply with a plan to delineate the area of review 

for a proposed geologic sequestration project, reevaluate the delineation, and 

perform corrective action that meets the requirements of this section in a 

manner and at a frequency acceptable to the Director. As a part of the permit 

application, the owner or operator must submit an area of review and corrective 

action plan that includes the following information: 

Schlumberger Rationale: - 

Response: EPA disagrees with the proposed changes and retains the provisions as proposed. For 

additional information on EPA's approach to AoR and corrective action, please see the final rule and 

preamble. 

Other EPA Comment Codes and Descriptions: 3530 2.2.3.1 AoR reevaluation frequency (seeking 

comment) 

Comment: Proposed Rule: (i) The minimum fixed frequency, not to exceed 10 years, the 

owner or operator proposes to reevaluate the area of review; 

Schlumberger Suggested Revision: Revision: (i) The owner or operator will 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24021

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24022

494
reevaluate the AOR after two years, 5 years and then no less frequently than 

every 5 years for period of injection. This schedule may be relaxed at the 

discretion of the director in the post injection period if appropriate data 

exist to support the change. 

Schlumberger Rationale: We feel that a frequency of every 10 years is too long 

to identify early discrepancies between the site performance and the site model. 

Seeing early difference will allow for earlier model updating and provide 

additional reduction in leakage risk and a better understanding of the site. 

Response: EPA agrees with commenters that reevaluations of the AoR every ten years may not be 

sufficient to appropriately model plume and pressure front movement, establish conditions for corrective 

action, and ensure protection of USDWs from endangerment. For these reasons, the Agency changed the 

minimum frequency for the AoR reevaluation at §146.84(e) from 10 years to at least every 5 years in the 

final GS rule. EPA believes that this revised frequency addresses commenters' concerns about the 

inherent uncertainties in modeling CO2 movement, the emerging nature of GS technology, risk-based 

targeting of monitoring activities, and the unique nature of CO2 GS. In addition, the Director has 

discretion to require more frequent AoR reevaluation if he or she has reason to believe, based on sitespecific information, that a five-year reevaluation schedule is not sufficiently protective of USDWs. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: Proposed Rule: (iv) How corrective action will be conducted to meet the 

requirements of paragraph (d) of this section, including what corrective action 

will be performed prior to injection and what, if any, portions of the area of 

review will have corrective action addressed on a phased basis and how the 

phasing will be determined; how corrective action will be adjusted if there are 

changes in the area of review; and how site access will be guaranteed for future 

corrective action. 

Schlumberger Suggested Revision: (iv) How corrective action will be conducted to 

meet the requirements of paragraph (d) of this section, including what 

corrective action will be performed prior to injection and what, if any, 

portions of the area of review will have corrective action addressed on a phased 

basis and how the phasing will be determined; how corrective action will be 

adjusted if there are changes in the area of review; and how site access will be 

arranged for future corrective action. 

Schlumberger Rationale: Future access cannot be fully guaranteed for an area in 

advance that may not even be within the boundaries of the initial AOR/ project. 

Response: EPA is retaining this requirement as proposed. The purpose of the corrective action 

requirement at §146.84(d) is to ensure that all wells in the AoR that have the potential to cause the 

movement of CO2 or other fluids into or between USDWs receive appropriate corrective action. In 

general, to meet this requirement, the owner or operator will most likely need to obtain the right of 

access to wells that may require corrective action, and demonstrate they have done this in their proposed 

AoR and corrective action plan. In the AoR and corrective action plan, the owner or operator must 

describe how site access will be guaranteed for future corrective action. §146.84(b)(2)(iv). 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24023

495
Other EPA Comment Codes and Descriptions: 3110 2.1.1 Proposed siting requirements (i.e., 

injection/confining zones, trapping mechanism) 

Comment: Proposed Rule: (i) Be based on detailed geologic data collected to characterize 

the injection zone, confining zone and any additional zones; and anticipated 

operating data, including injection pressures, rates and total volumes over the 

proposed life of the geological sequestration project; 

Schlumberger Suggested Revision: (i) Be based on detailed geologic data 

collected to characterize the injection zone, confining zone(s), monitoring 

zones and any additional zones; and anticipated operating data, including 

injection pressures, rates and total volumes over the proposed life of the 

geological sequestration project; 

Schlumberger Rationale: We feel that if there are secondary confining units that 

they should be included in the site model along with any transmissive zones 

between the primary and secondary confining units. 

Response: EPA agrees that all geologic data about the site, including confining zone(s) and transmissive 

zones, should be addressed in the model but disagrees that the suggested revision is necessary. EPA 

clarifies that the AoR delineation model must be based on detailed geologic data collected to 

characterize the injection zone, confining zone and any additional zones (§146.84(c)(1)(i)). 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action; 5100 2.8.1 Injection 

well plugging activities (seeking comment) (40 CFR 146.92) 

Comment: Proposed Rule: (3) Determine which abandoned wells in the area of review have 

been plugged (as required by §146.92) in a manner that prevents the movement of 

carbon dioxide or associated fluids that may endanger USDWs. 

Schlumberger Suggested Revision: (3) Determine which abandoned wells identified 

in 146.84 (c) (2) have been plugged (as required by §146.92) in a manner that 

prevents the movement of carbon dioxide or formation fluids that may endanger 

USDWs. 

Schlumberger Rationale: - 

Response: EPA acknowledges the comment. Based on its evaluation of all public comments and input 

on the proposed rule and NODA and Request for Comment, EPA has made many revisions to the GS 

Rule. See the final rule and preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: Proposed Rule: (d) Owners or operators of Class VI wells must perform corrective 

action on all wells in the area of review that are determined to need corrective 

action using methods necessary to prevent the movement of fluid into or between 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24025

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24027

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24028

496
USDWs including use of corrosion resistant materials, where appropriate. 

Schlumberger Suggested Revision: Owners or operators of Class VI wells must 

perform corrective action using corrosion resistant materials, when appropriate, 

on all wells identified in 146.84(c)(2) that are determined to need corrective 

action". 

Schlumberger Rationale: - 

Response: EPA revised the text at §146.84(d) to require the use of materials that are "compatible with 

the carbon dioxide stream" Instead of corrosion resistant materials. EPA believes this language change 

addresses commenters' concerns and is also consistent with other language regarding materials 

requirements in the GS rule. EPA did not make the other suggested changes. See the final rule and 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 3530 2.2.3.1 AoR reevaluation frequency (seeking 

comment) 

Comment: Proposed Rule: (f) At the minimum fixed frequency, not to exceed 10 years, as 

specified in the area of review and corrective action plan, or when monitoring 

and operational conditions warrant, owners or operators must: 

Schlumberger Suggested Revision: (f) At the same frequency as the reevaluation 

of the AOR as specified in 146.84(c ) (2) (i), or when monitoring and 

operational conditions warrant, owners or operators must: 

Schlumberger Rationale: - 

Response: EPA disagrees with the proposed changes and retains the provisions as proposed. EPA 

believes that the commenter’s suggested edit has substantively the same meaning as the proposed text. 

For additional information on EPA's approach to AoR and corrective action, please see the final rule and 

preamble. 

Other EPA Comment Codes and Descriptions: 3700 2.2.5 Comments on the requirement for an AoR 

and corrective action plan 

Comment: Proposed Rule: (4) Submit an amended area of review and corrective action plan 

or demonstrate to the Director through monitoring data and modeling results that 

no amendment to the area of review and corrective action plan is needed. 

Schlumberger Suggested Revision: (4) Submit an amended area of review and 

corrective action plan or demonstrate to the Director through monitoring data 

and modeling results that no change to the area of review and corrective action 

plan is needed. 

Schlumberger Rationale: - 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24029

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24030

497
Response: EPA disagrees with the suggested change and believes the proposed text is clear as written. 

For additional information on EPA's approach to AoR and corrective action, please see the final rule and 

preamble. 

Other EPA Comment Codes and Descriptions: 5400 2.9 Proposed Financial Responsibility and 

Long-Term Care Requirements 

Comment: §146.85 Financial responsibility. 

Proposed Rule: (b) The owner or operator must provide to the Director, at a 

frequency determined by the Director, written updates of adjustments to the cost 

estimate to account for any amendments to the area of review and corrective 

action plan (§146.84), the injection well plugging plan (§146.92), and the postinjection site care and site closure plan (§146.93). 

Schlumberger Suggested Revision: (b) The owner or operator must provide to the 

Director, at the same frequency as the AOR reevaluation, written updates of 

adjustments to the cost estimate to account for any amendments to the area of 

review and corrective action plan (§146.84), the injection well plugging plan 

(§146.92), and the post-injection site care and site closure plan (§146.93). 

Schlumberger Rationale: We feel that potential changes in the size of the AOR 

require that all site plans be reevaluated at the same frequency as the AOR. 

Response: EPA agrees that it is important to periodically update cost estimates that support financial 

responsibility determinations. The final GS rule, at §146.85(c), requires the owner or operator to provide 

annual updates to the cost estimate to account for any amendments to the AoR and corrective action 

plan, the injection well plugging plan, the PISC and site closure plan, and the emergency and remedial 

response plan. Owners or operators must also adjust the estimates for inflation annually under §146.85

(c)(2). EPA adds that the Director can also require the owner or operator to provide an adjustment of the 

cost estimate if the Director determines that the original demonstration is no longer adequate, as 

specified at §146.85(e). See the final rule and preamble for further discussion of EPA's final approach to 

financial responsibility. 

Other EPA Comment Codes and Descriptions: 3800 2.3 Proposed Injection Well Construction 

Requirements (40 CFR 146.86) 

Comment: §146.86 Injection well construction requirements. 

Proposed Rule: (1) Prevent the movement of fluids into or between USDWs or into 

any unauthorized zones; 

Schlumberger Suggested Revision:(1) Prevent the movement of fluids into or 

between USDWs or into any unauthorized zones that causes endangerment; 

Schlumberger Rationale: - 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24031

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24032

498
Response: EPA disagrees with the suggested edit. EPA believes that protection of USDWs from 

endangerment and prevention of fluid movement between formations is paramount, and believes that the 

language as proposed meets the standards in SDWA §1421. Appropriately designed and constructed 

wells are necessary to prevent endangerment to USDWs and maintain integrity of the well throughout 

the lifetime of a GS project. This is the foundation of the requirements for construction and preoperational testing of Class VI wells at §§146.86 and 146.87. 

Other EPA Comment Codes and Descriptions: 3820 2.3.1 Well construction procedures 

Comment: Proposed Rule: (ii) Injection pressure, external pressure, internal pressure and 

axial loading; 

Schlumberger Suggested Revision: (ii) Injection pressure, external pressure, 

internal pressure and axial loading; 

Schlumberger Rationale: What is meant by external and internal pressure? 

Response: The internal and external pressure mentioned in §146.86(b)(1)(ii) refers to pressure on the 

well casing. Internal pressures could be caused by cement or annular fluids; external pressures could be 

caused by cementing against the borehole or pressure head from formations. See the discussion of Class 

VI well construction requirements in the preamble to the final GS rule for additional information. 

Additionally, EPA is developing guidance on the construction of Class VI wells. This guidance will be 

available on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3800 2.3 Proposed Injection Well Construction 

Requirements (40 CFR 146.86) 

Comment: Proposed Rule: (vi) Down-hole temperatures; 

Schlumberger Suggested Revision: (vi) Down-hole temperatures and pressures; 

Schlumberger Rationale: - 

Response: EPA believes the requirement at 146.86(b)(1)(ii), which requires consideration of Injection 

pressure, external pressure, internal pressure, and axial loading addresses this concern, and therefore the 

proposed change is unnecessary. 

Other EPA Comment Codes and Descriptions: 3822 2.3.1.1 Depth of surface casing (seeking 

comment); 3824 2.3.1.2 Cementing of long-string casing (seeking comment) 

Comment: Proposed Rule: (2) Surface casing must extend through the base of the lowermost 

USDW and be cemented to the surface. 

Schlumberger Suggested Revision: (2) Surface casing must extend through the base 

of the lowermost USDW above the injection zone and be cemented to the surface. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24034

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24035

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24036

499
Schlumberger Rationale: In some parts of the US the USDW is very deep and this 

standard may preclude geologic sequestration in these areas. 

Response: EPA disagrees with the suggested edit or that the surface casing requirements in the GS rule 

preclude injection below deep USDWs. The final GS rule at §146.86(b)(2) requires that surface casing 

extend through the base of the lowermost USDW and be cemented to the surface through the use of a 

single or multiple strings of casing and cement. It does not, however, specify how cementing must be 

accomplished, and gives flexibility to the owner or operator to propose alternate methods- to provide a 

sufficient amount of cement to meet the standard that USDWs are protected from endangerment. EPA 

notes that there are many potential ways to meet the requirement, such as the use of staged cementing. 

EPA recognizes concerns regarding construction of Class VI wells where the lowermost USDW is very 

deep. To further address comments on deep injection wells, the final GS rule at §146.95 includes 

requirements for owners or operators that seek a waiver of the injection depth requirements. Owners or 

operators of wells operating under injection depth waivers must comply with additional construction 

requirements to ensure that wells used to inject above or between USDWs are protective. See the 

discussion of the waiver approach in the preamble to the final GS rule for additional information. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: Proposed Rule: (3) At least one long string casing, using a sufficient number of 

centralizers, must extend to the injection zone and must be cemented by 

circulating cement to the surface in one or more stages. 

Schlumberger Suggested Revision: - 

Schlumberger Rationale: We support this language work by Carey et al and crow et 

al shows that CO2 can move above the top of the CO2 reservoir, so cementing to 

surface will provide the best chance to have maximum zonal isolation 

Response: EPA agrees that the requirement for long-string casing of Class VI wells at §146.86(b) will 

offer the best protection against fluid movement behind the casing, between formations, and above the 

injection zone and will ensure competency of Class VI wells and protect USDWs from endangerment. 

The buoyant nature of CO2 dictates deep well construction procedures that address movement of fluid 

behind the casing and provide necessary barriers to CO2 leakage outside of the injection zone. In 

developing the construction requirements for Class VI wells, EPA reviewed the work cited by Carey et 

al. (2007) and Crow et al. (2008). EPA agrees that they offer important justification for the 

establishment of tailored requirements. 

Other EPA Comment Codes and Descriptions: 3864 2.3.3.2 Use of corrosion-resistant cements 

(seeking comment) 

Comment: Proposed Rule: (5) Cement and cement additives must be compatible with the 

carbon dioxide stream and formation fluids and of sufficient quality and 

quantity to maintain integrity over the design life the geologic sequestration 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24037

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24038

500
project. The integrity and location of the cement shall be verified using 

technology capable of evaluating cement quality radially and identifying the 

location of channels to ensure that USDWs are not 

Schlumberger Suggested Revision: (5) Cement and cement additives must be 

suitable for use with the carbon dioxide stream and formation fluids and of 

sufficient quality and quantity to maintain integrity over the project life. The 

integrity and location of the cement shall be verified using technology capable 

of evaluating cement quality radially and identifying the location of channels 

to ensure that USDWs are not endangered. 

Schlumberger Rationale: Well cements need to site and condition specific. There 

may be instances or places in the well that will require special cements. It is 

also that the cement in the well last as long as the project and post injection 

period. 

Response: EPA recognizes that each GS project will be unique and, for this reason, the rule provides 

flexibility regarding the selection and use of cements for Class VI wells that are appropriate to the sitespecific conditions of the project. With the permit application, the owner or operator must submit well 

construction procedures, as specified at §146.82 (a)(12), that demonstrate that the well as constructed 

will prevent unacceptable fluid movement; allow the use of appropriate testing devices and workover 

tools; and allow continuous monitoring of the annulus space between the injection tubing and longstring casing, as specified at §146.86(a). The Director will evaluate the procedures in the context of 

geological and proposed operating data about the site. EPA adds that the rule does not specify cements 

to be used; rather, it provides owners or operators with the flexibility to choose, as long as the cements 

are compatible with the CO2 stream and formation fluids and of sufficient quality and quantity to 

maintain integrity over the design life of the GS project, as specified at §146.86(b)(5). 

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: §146.87 Logging, sampling, and testing prior to injection well operation. 

Proposed Rule: (a) During the drilling and construction of a Class VI injection 

well, the owner or operator must run appropriate logs, surveys and tests to 

determine or verify the depth, thickness, porosity, permeability, and lithology 

of, and the salinity of any formation fluids in, all relevant geologic 

formations to assure conformance with the injection well construction 

requirements under §146.86, and to establish accurate baseline data against 

which future measurements may be compared. The owner or operator must submit to 

the Director a descriptive report prepared by a knowledgeable log analyst that 

includes an interpretation of the results of such logs and tests. At a minimum, 

such logs and tests must include: 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24039

501
Schlumberger Suggested Revision: (a) During the drilling and construction of a 

Class VI injection well, the owner or operator must run appropriate logs, 

surveys and tests to determine or verify the depth, thickness, porosity, 

permeability, and lithology of, and the salinity of any formation fluids in, all 

relevant geologic formations to assure conformance with the injection well 

construction requirements under §146.86, and to establish accurate baseline data 

against which future measurements may be compared. The owner or operator must 

submit to the Director a descriptive report prepared by a knowledgeable log 

analyst that includes an interpretation of the results of such logs and tests. 

The Director may require such logs and tests as may be needed after taking into 

account the availability of similar data in the area of the drilling site to 

ensure that the data is equivalent to the data as would be collected based on 

such logs and tests as:: 

Schlumberger Rationale: In well defined areas, these evaluations are frequently 

unnecessary. The director should have discretion to select the appropriate 

requirements necessary to ensure that sufficient baseline data and information 

are available. For example, in an area where a number of wells are being 

drilled, the logging of surface hole yields little useful additional 

information. 

Response: EPA disagrees that the requirements for logs, surveys, and tests are unnecessary. All logs, 

surveys, and tests listed at §146.87(a) are necessary to verify information about the injection and 

confining zones and ensure that the well is being drilled and cased as approved, and has mechanical 

integrity. This information is needed to demonstrate that the well can be operated and tested in a manner 

that protects USDWs from endangerment. While the tests do provide information on some of the same 

items, each test provides unique pieces of information that build on each other and allow for 

interpretations not possible with a single test. 

EPA notes that the Director has the discretion at §146.87(a)(5) to approve alternative methods that 

provide equivalent or better information. EPA believes that logs and tests must be performed on each 

well drilled regardless of existing information about the area to account for the complexity of CO2 

injection well construction and the buoyancy of CO2. Existing lithologic and geologic information may 

lack the details needed for site-specific well design and the geology needed to support protection of 

USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Proposed Rule: (ii) A cement bond and variable density log, and a temperature 

log after the casing is set and cemented. 

Schlumberger Suggested Revision: (ii) Cement evaluation logs after the casing is 

set and cemented to evaluate cement quality radially with sufficient resolution 

to identify channels or changes to the cement quality. 

Schlumberger Rationale: Radial is key to finding pathways but the resolution 

must be sufficient to see the pathways. See the pathway identified in Crow et al 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24040

502
Response: EPA agrees with the suggested change. In the final GS rule, §146.87(a)(2)(ii) reads as 

follows: "A cement bond and variable density log to evaluate cement quality radially, and a temperature 

log after the casing is set and cemented." 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Proposed Rule: (4) A series of tests designed to demonstrate the internal and 

external mechanical integrity of injection wells, which may include: 

Schlumberger Suggested Revision: (4) Test(s) designed to demonstrate the 

internal and external mechanical integrity of injection wells, which may 

include: 

Schlumberger Rationale: - 

Response: EPA disagrees that the suggested edit is necessary, and the final rule retains the text as 

proposed. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Proposed Rule: (ii) A tracer survey such as oxygen-activation logging; 

Schlumberger Suggested Revision: (ii) Diagnostic tools such as oxygenactivation logging; 

Schlumberger Rationale: Technical correction 

Response: EPA disagrees that the allowing the use of unspecified "diagnostic tools" would provide the 

same amount of information as the requirement to perform a tracer survey. The track record for tracer 

surveys in evaluating mechanical integrity has been proven over time. The Agency clarifies that a tracer 

survey is one of the mechanical integrity tests that may be required by the Director or used by the owner 

or operator. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Proposed Rule: (b) The owner or operator must take and submit to the Director 

whole cores or sidewall cores of the injection zone and confining system and 

formation fluid samples from the injection zone(s). The Director may accept 

cores from nearby wells if the owner or operator can demonstrate that core 

retrieval is not possible and that such cores are representative of conditions 

at the well. The Director may require the owner or operator to core other 

formations in the borehole. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24041

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24042

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24044

503
Schlumberger Suggested Revision: (b) The owner or operator must submit to the 

Director a report describing whole cores or sidewall cores representative of the 

injection zone and confining system and formation fluid samples from the 

injection zone(s). The Director may accept data from cores and fluid samples 

from nearby wells if the owner or operator can demonstrate that such data are 

representative of conditions at the well. 

Schlumberger Rationale: The information required should be sufficient to 

properly describe the injection and confining zones. 

Response: EPA clarifies that it is not the Agency's intent that physical cores be submitted to the 

Director. In the final GS rule, EPA has revised the first sentence of §146.87(b) to read as follows: "The 

owner or operator must take whole cores or sidewall cores of the injection zone and confining system 

and formation fluid samples from the injection zone(s), and must submit to the Director a detailed report 

prepared by a log analyst that includes: well log analyses (including well logs), core analyses, and 

formation fluid sample information...." 

EPA clarifies that §146.87(b) allows information on cores from nearby wells to be submitted only if the 

operator can demonstrate that core retrieval is not possible and that cores from nearby wells are 

representative of conditions at the Class VI well. If the Director approves the use of alternate cores and 

determines that additional logs, such as video logs, are necessary to evaluate the site, he/she has 

authority under §146.87(a)(5) to require additional information. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Proposed Rule: (c) The owner or operator must record the fluid temperature, pH, 

conductivity, reservoir pressure and the static fluid level of the injection 

zone(s). 

Schlumberger Suggested Revision: (c) Prior to injection well operation, the 

owner or operator must record the formation temperature, formation fluid pH and 

conductivity, and reservoir pressure of the injection zone(s). 

Schlumberger Rationale: - 

Response: EPA clarifies that all logging, sampling and testing for characteristics of the injection zone 

required in §146.87 are, as defined in the title to that section, to be performed prior to injection well 

operation. EPA adds that §146.82(c)(7) requires that the Director evaluate the results of all logging and 

testing prior to authorizing injection. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Proposed Rule:(f) The owner or operator must provide the Director with the 

opportunity to witness all logging and testing by this subpart. The owner or 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24045

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24047

504
operator must submit a schedule of such activities to the Director 30 days prior 

to conducting the first test and submit any changes to the schedule 30 days 

prior to the next scheduled test. 

Schlumberger Suggested Revision: (f) The owner or operator must provide the 

Director with the opportunity to witness all logging and testing by this 

subpart. The owner or operator must submit a schedule of such activities to the 

Director upon spudding the well and submit any changes to the schedule 48 hours 

prior to the scheduled test. 

Schlumberger Rationale: The changes reflect the realities of flexible rig 

schedules and consistency with Class II practices. 

Response: EPA disagrees that the 30-day notification requirement is unreasonable. The 30-day 

notification mirrors the current requirement for logging and testing of new Class I wells, as described in 

§146.66. Acknowledging the developing nature of CO2 GS, EPA believes that involvement by the 

permitting authority in each project will provide much needed field data for assurance of USDW 

protection from endangerment and will help update and refine the permitting process. Adequate timing 

of notification will ensure the Director's ability to be involved. 

Other EPA Comment Codes and Descriptions: 4110 2.4.1.1 Injection pressure limitations 

Comment: §146.88 Injection well operating requirements. 

Proposed Rule: (a) Except during stimulation, the owner or operator must ensure 

that injection pressure does not exceed 90 percent of the fracture pressure of 

the injection zone so as to assure that the injection does not initiate new 

fractures or propagate existing fractures in the injection zone. In no case may 

injection pressure initiate fractures in the confining zone(s) or cause the 

movement of injection or formation fluids that endangers a USDW. 

Schlumberger Suggested Revision: (a) Except during stimulation, the owner or 

operator must ensure that injection pressure does not exceed 90 percent of the 

hydraulic fracture pressure of the confining zone so as to assure that the 

injection does not initiate new fractures or propagate existing fractures in the 

confining zone. In no case may injection pressure initiate fractures in the 

confining zone(s) or cause the movement of injection or formation fluids that 

endangers a USDW. 

Schlumberger Rationale: Maintaining the integrity of the confining zone is the 

critical parameter. 

Response: EPA agrees that maintaining the integrity of the confining zone is critical in order to protect 

USDWs from endangerment. However, EPA also believes that the injection pressure should not exceed 

90 percent of the fracture pressure of the injection zone. The final rule retains this provision at §146.88

(a). EPA believes that the 90 percent requirement, which was suggested by IOGCC and permit writers 

whom EPA consulted when writing the regulation, is a satisfactory margin of safety for well operation. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24048

505
Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Proposed Rule: (e) Upon completion, but prior to operation, the owner or 

operator must conduct the following tests to verify hydrogeologic 

characteristics of the injection zone: 

Schlumberger Suggested Revision: (d) At any time prior to injection well 

operation, the owner or operator must determine fracture pressures of the 

injection and confining zones and conduct tests to verify hydrogeologic and 

geomechanical characteristics of the injection zone, e.g.: 

Schlumberger Rationale: - 

Response: EPA disagrees that the suggested edit is necessary, and the final rule retains the text as 

proposed. 

Other EPA Comment Codes and Descriptions: 4000 2.4 Proposed Injection Well Operating 

Requirements (40 CFR 146.88) 

Comment: Proposed Rule: (b) Injection between the outermost casing protecting USDWs and 

the well bore is prohibited. 

Schlumberger Suggested Revision: (b) Injection of the CO2 stream between the 

outermost casing protecting USDWs and the well bore is prohibited. 

Schlumberger Rationale: - 

Response: EPA retains the provision as proposed, and clarifies that injection between the casing and the 

well bore is prohibited. This is consistent with requirements for other injection well classes in the UIC 

program. 

Other EPA Comment Codes and Descriptions: 4000 2.4 Proposed Injection Well Operating 

Requirements (40 CFR 146.88) 

Comment: Proposed Rule: (c) The owner or operator must fill the annulus between the 

tubing and the long string casing with a non-corrosive fluid approved by the 

Director. The owner or operator must maintain on the annulus a pressure that 

exceeds the operating injection pressure, unless the Director determines that 

such requirement might harm the integrity of the well. 

Schlumberger Suggested Revision: (c) The owner or operator must fill the annulus 

between the tubing and the long string casing with a non-corrosive fluid 

approved by the Director. 

Schlumberger Rationale: Industry experience with the Class II UIC program does 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24049

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24050

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24051

506
not support this requirement. 

Response: EPA believes that maintaining an annulus pressure that is higher than the injection pressure, 

as required at §146.88(c), will ensure that if there are leaks in the tubing, the annulus fluid will move 

into the tubing, rather than the injectate moving out of the tubing and potentially along the outside of the 

well. EPA believes this requirement is appropriate and necessary for Class VI wells given the potential 

high volumes and supercritical nature of the CO2 injectate, potential geomechanical stresses in the 

wellbore, and the potential for movement of the CO2 in the event of a mechanical integrity loss. 

Other EPA Comment Codes and Descriptions: 4000 2.4 Proposed Injection Well Operating 

Requirements (40 CFR 146.88) 

Comment: Proposed Rule: (3) Notify the Director within 24 hours 

Schlumberger Suggested Revision: (3) Notify the Director within 24 hours of 

discovery; 

Schlumberger Rationale: - 

Response: The final rule text at §146.88(f) now reads, "If a shutdown (i.e., down-hole or at the surface) 

is triggered or a loss of mechanical integrity is discovered." Therefore the notice required at §146.88(f)

(3) must be provided within 24 hours of an automatic shut-off device being triggered or a loss of 

mechanical integrity being discovered. EPA believes this provision is necessary to ensure timely 

response to potential USDW endangerment. 

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: §146.90 Testing and monitoring requirements. 

Proposed Rule: (b) Installation and use, except during well workovers as defined 

in §146.86(d), of continuous recording devices to monitor injection pressure, 

rate and volume; the pressure on the annulus between the tubing and the long 

string casing; and the annulus fluid volume; 

Schlumberger Suggested Revision: - 

Schlumberger Rationale: 146.86(d) does not exist; perhaps 146.88(d) is what was 

intended. 

Response: EPA acknowledges the comment; the final rule contains the suggested revision. 

Other EPA Comment Codes and Descriptions: 4630 2.6.3 Corrosion monitoring 

Comment: Proposed Rule: (c) Corrosion monitoring of the well materials for loss of mass, 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24052

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24053

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24054

507
thickness, cracking, pitting and other signs of corrosion must be performed on a 

quarterly basis to ensure that the well components meet the minimum standards 

for material strength and performance set forth in §146.86(b) by: 

Schlumberger Suggested Revision: (c) Corrosion monitoring of the well materials 

for loss of mass, thickness, cracking, pitting and other signs of corrosion must 

be performed quarterly and may be modified to be less frequent as approved by 

the Director based on construction materials, operating conditions, and 

monitoring history to ensure that the well components meet the minimum standards 

for material strength and performance set forth in §146.86(b) by: 

Schlumberger Rationale: Allows application of performance based approach. 

Response: EPA believes that corrosion monitoring is appropriate given the potentially corrosive nature 

of the CO2 stream. CO2 in the presence of water becomes acidic, potentially accelerating corrosion of 

well materials. The CO2 stream for a GS project may also contain small volumes of impurities that 

could contribute to corrosion. For these reasons, the final rule requires quarterly corrosion monitoring at 

§146.90(c), as proposed. 

Other EPA Comment Codes and Descriptions: 4630 2.6.3 Corrosion monitoring 

Comment: Proposed Rule: (1) Placing coupons of the well construction materials in contact 

with the carbon dioxide stream; or 

Schlumberger Suggested Revision: (1) Analyzing coupons of the well construction 

materials placed in contact with the carbon dioxide stream; or 

Schlumberger Rationale: - 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS rule. See the final rule and preamble 

for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4630 2.6.3 Corrosion monitoring 

Comment: Proposed Rule: (2) Routing the carbon dioxide stream through a loop constructed 

with the material used in the well; or 

Schlumberger Suggested Revision: (2) Routing the carbon dioxide stream through a 

loop constructed with the material used in the well and inspecting the materials 

in the loop; or 

Schlumberger Rationale: - 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS rule. See the final rule and preamble 

for further discussion on EPA's final approach. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24055

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24056

508
Other EPA Comment Codes and Descriptions: 4630 2.6.3 Corrosion monitoring 

Comment: Proposed Rule: (3) Using an alternative method approved by the Director; 

Schlumberger Suggested Revision: (3) Using an alternative method, materials, or 

time period approved by the Director; 

Schlumberger Rationale: - 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS rule. See the final rule and preamble 

for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4660 2.6.6 Geochemical monitoring 

Comment: Proposed Rule: (d) Periodic monitoring of the ground water quality and 

geochemical changes above the confining zone(s) that may be a result of carbon 

dioxide movement through the confining zone or additional identified zones: 

Schlumberger Suggested Revision: (d) Periodic monitoring of the ground water 

quality for geochemical changes above the confining zone(s) that may be a result 

of carbon dioxide movement through the confining zone or additional identified 

zones: 

Schlumberger Rationale: - 

Response: EPA did not make the suggested change. Based on its evaluation of all public comments and 

input on the proposed rule and NODA and Request for Comment EPA has made many revisions to the 

GS rule. See the final rule and preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4650 2.6.5 CO2 plume and pressure front tracking 

(seeking comment) 

Comment: Proposed Rule: (1) The location and number of monitoring wells must be based on 

specific information about the geologic sequestration project, including 

injection rate and volume, geology, the presence of artificial penetrations and 

other factors; 

Schlumberger Suggested Revision: (1) The location and number of monitoring wells 

must be based on specific information about the geologic sequestration project, 

including injection rate and volume, geology, the presence of artificial 

penetrations and other relevant factors as warranted by a risk-assessment; 

Schlumberger Rationale: The monitoring should be designed to reduce risk 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24057

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24058

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24059

509
Response: EPA agrees that monitoring plans and methods need to be site-specific and believes that the 

monitoring requirements for GS sites at §146.90 provide an appropriate level of flexibility in structuring 

a testing and monitoring plan that protects USDWs from endangerment. EPA retains the requirement 

regarding placement of monitoring wells, but adds that any additional relevant site-specific information 

must be considered in the development of the testing and monitoring plan to ensure USDW protection 

from endangerment. 

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in 

evaluating requirements under §146.90, including proposed monitoring plans. The guidance describes 

available technologies and recommended approaches for implementing a testing and monitoring plan, 

including pre-operational geophysical logging and testing of injection wells, MITs, injection well testing 

during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, and soil 

gas and surface air monitoring which may be required by the UIC Director for specific GS projects. The 

guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4660 2.6.6 Geochemical monitoring 

Comment: Proposed Rule: (2) The monitoring frequency and spatial distribution of 

monitoring wells must be based on baseline geochemical data that has been 

collected under §146.82(a) (6) and any modeling results in the area of review 

evaluation required by §146.84(b); 

Schlumberger Suggested Revision: (2) The monitoring frequency and spatial 

distribution of monitoring wells must be based on geological and geophysical 

data that has been collected under §146.82(d) and any modeling results in the 

area of review evaluation required by §146.84(b); 

Schlumberger Rationale:Geochemical data does not seem have a high degree of 

relevance in selecting monitoring well sites. 

Response: EPA believes that baseline characterization of the site, including the geochemical data and 

initial modeling, will be highly valuable in selection of monitoring well locations and in refining plans 

for monitoring frequency. The GS rule stipulates that the monitoring frequency and spatial distribution 

of monitoring wells must be based on baseline geochemical data that were collected during the initial 

site characterization and the area of review evaluation at §146.90(d)(2). The details of the geochemical 

monitoring will be based on site-specific information and described in the Director-approved testing and 

monitoring plan. 

Other EPA Comment Codes and Descriptions: 4546 2.5.2.2 MIT frequency (seeking comment) 

Comment: Proposed Rule: (e) A demonstration of external mechanical integrity pursuant to 

§146.89(c) at least once per year throughout the duration of the geologic 

sequestration project; 

Schlumberger Suggested Revision: (e) A demonstration of external mechanical 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24060

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24061

510
integrity pursuant to §146.89(c) at least once per year throughout the life of 

the well; 

Schlumberger Rationale: - 

Response: EPA is retaining the language as proposed. EPA clarifies that the monitoring and testing plan 

requirements in §146.90 cover the period prior to well plugging. External MITs are not required once a 

well is plugged, as this test would no longer be possible in a plugged well. If a well is plugged prior to 

site closure, no further MITs are required for that well. 

Other EPA Comment Codes and Descriptions: 4640 2.6.4 Pressure fall-off testing (seeking comment) 

Comment: Proposed Rule: (f) A pressure fall-off test at least once every five years 

unless more frequent testing is required by the Director based on site specific 

information; 

Schlumberger Suggested Revision: (f) A pressure fall-off test or other 

equivalent test that identifies reservoir conditions with respect to flow 

dynamics at least once every five years unless more frequent testing is required 

by the Director based on site specific information; 

Schlumberger Rationale: Allows more flexibility while still providing the needed 

information 

Response: EPA believes that pressure fall-off testing is necessary for GS wells. Pressure fall-off tests 

are designed to verify that modeled projections of reservoir pressure decline agree with measured 

pressure decline profiles. These tests can be useful in AoR calculations and reevaluations and may also 

indicate mischaracterization of site geology and the presence of leakage pathways. EPA therefore 

believes that pressure fall-off testing is conducted at least once every five years and the final GS 

regulation includes this requirement at §146.90(f). Pressure fall-off tests may be conducted in 

conjunction with other well performance tests (i.e., mechanical integrity testing) to ensure safe and 

effective operations. 

Other EPA Comment Codes and Descriptions: 4650 2.6.5 CO2 plume and pressure front tracking 

(seeking comment) 

Comment: Proposed Rule: (g) Testing and monitoring to track the extent of the carbon 

dioxide plume and the position of the pressure front by either monitoring for 

pressure changes in the first formation overlying the confining zone or using 

indirect, geophysical techniques (e.g., seismic, electrical, gravity, or 

electromagnetic surveys and/or down-hole carbon dioxide detection tools); 

Schlumberger Suggested Revision: (g) Testing and monitoring to track the extent 

of the carbon dioxide plume and the position of the pressure front. 

Schlumberger Rationale:Monitoring outside of the injection zone provides little 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24062

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24063

511
information of value for tracking and monitoring the injected plume. Examples of 

how to test and monitor could be included in the Preamble. 

Response: As described above, EPA has revised this requirement in the final rule. The final GS 

regulation, at §146.90(g)(1), requires all GS project owners or operators to monitor directly for pressure 

changes in the injection zone. EPA believes that pressure monitoring in the injection zone is necessary 

to track the development and movement of the pressure front and CO2 plume. In addition, §146.90(g)(2) 

requires owners or operators to track the position of the CO2 plume using indirect methods (e.g., 

seismic, electrical, gravity, or electromagnetic surveys and/or down-hole CO2 detection tools), unless 

the Director determines based on site-specific geology, that such methods are not appropriate. 

Other EPA Comment Codes and Descriptions: 4670 2.6.7 Surface air monitoring and/or soil gas 

monitoring (seeking comment) 

Comment: Proposed Rule: (h) At the Director’s discretion, surface air monitoring and/or 

soil gas monitoring to detect movement of carbon dioxide that could endanger a 

USDW. 

Schlumberger Suggested Revision: (h) At the Director’s discretion based on sitespecific conditions and risk- based factors, surface air monitoring and/or soil 

gas monitoring to detect movement of carbon dioxide that could endanger a USDW. 

Schlumberger Rationale: In most situations soil and air monitoring does not 

provide an effective method of protecting USDWs. 

Response: EPA acknowledges that air and soil gas monitoring to ensure USDW protection is not 

necessary at all GS sites and agrees that the decision to use surface monitoring and the selection of 

monitoring methods for the purpose of USDW protection will be site-specific. 

In the final rule, at §146.90(h), the decision to require such monitoring as an additional measure to 

ensure USDW protection rests with the Director as a means of identifying leaks that may pose a risk to 

USDWs and informing emergency notification of a Class VI owner or operator and UIC Director in the 

event of a USDW endangerment, pursuant to requirements at §146.91(c). 

The Agency believes that surface air and soil gas monitoring, when coupled with subsurface monitoring, 

may be appropriate at some GS projects to ensure USDW protection. EPA also acknowledges that 

surface air and soil gas measurements are subject to variability and may not be suitable in all settings as 

a method to ensure USDW protection. However, EPA does not believe that this should entirely preclude 

their use. The decision to use surface monitoring and the selection of monitoring methods will be sitespecific (e.g., may be influenced by geology, injection depth, and operational conditions) and must be 

based on potential risks to USDWs within the AoR. 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Proposed Rule: (1) The testing and monitoring plan must be based on potential 

vulnerabilities within the area of review; 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24064

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24065

512
Schlumberger Suggested Revision: (1) The testing and monitoring plan must be 

based on site-specific geologic factors, modeling, and risk-assessment within 

the area of review; 

Schlumberger Rationale: - 

Response: EPA anticipates that the testing and monitoring plan will address site-specific geologic 

factors, modeling, and risk-assessment. EPA is developing guidance on how best to develop the various 

required project plans, including the testing and monitoring plan. The guidance can be found on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment EPA has made many revisions to the GS rule. See the final rule and preamble for further 

discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: §146.91 Reporting requirements. 

Proposed Rule: (1) Any changes to the physical, chemical and other relevant 

characteristics of the carbon dioxide stream from the proposed operating data; 

Schlumberger Suggested Revision: (1) Any significant changes to the physical, 

chemical and other relevant characteristics of the carbon dioxide stream from 

the proposed operating data; 

Schlumberger Rationale: Minor changes could just be due to uncertainty in 

measurements or models 

Response: EPA retained this provision as proposed. The final rule at §146.91(a)(3) requires reporting of 

all exceedances of operating parameters. EPA disagrees with the suggestion to report only "significant" 

exceedances. Making a determination as to whether an exceedance is "significant" is not the purpose of 

the requirement. EPA believes that the ability of an operator to consistently meet operating requirements 

and avoid exceedances provides evidence of a well-managed GS project that is in compliance with the 

Class VI permit. If multiple exceedances occur, the Director should be aware of such occurrences and 

determine whether these indicate non-compliance at the site, and require the appropriate course of action 

(e.g., a well workover, modification of operating parameters, or imposition of a penalty). Please see the 

final rule and the discussion of testing and monitoring in the preamble for additional information. 

EPA clarifies that the rule, at §146.91(c), also requires operators to notify the Director, within 24 hours, 

of any event that may cause endangerment to a USDW. If such events occur outside of business hours 

(e.g., over night), operators must report to the Director within 24 hours, and permitting agencies have 

staff and procedures to respond to these types of calls 24 hours a day, 7 days a week. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24066

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24067

513
Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: §146.92 Injection well plugging. 

Proposed Rule: (a) Prior to the well plugging, the owner or operator must flush 

each Class VI injection well with a buffer fluid, determine bottomhole reservoir 

pressure, and perform a final mechanical integrity test. 

Schlumberger Suggested Revision: (a) Prior to the well plugging, the owner or 

operator must flush each Class VI injection well with a buffer fluid, determine 

bottomhole reservoir pressure, and perform a final external mechanical integrity 

test. 

Schlumberger Rationale: Many of the components that would be tested by an 

internal MIT are removed or tested during the plugging process. 

Response: EPA agrees that only an external MIT is required, and has modified the GS rule at §146.92

(a) to require owners or operators to perform a final external mechanical integrity test prior to the well 

plugging. 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: Proposed Rule: (2) Appropriate testing methods to ensure mechanical integrity as 

specified in §146.89; 

Schlumberger Suggested Revision: (2) Appropriate testing methods to ensure final 

external mechanical integrity as specified in §146.89(c); 

Schlumberger Rationale: Many of the components that would be tested by an 

internal MIT are removed or tested during the plugging process. 

Response: EPA agrees that only an external MIT is required, and has modified the GS rule at §146.92

(a) to require owners or operators to perform a final external mechanical integrity test prior to the well 

plugging. 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: Proposed Rule: (5) The type and grade and quantity of material to be used in 

plugging. The material must be compatible with the carbon dioxide stream; and 

Schlumberger Suggested Revision: (5) The type and grade and quantity of material 

to be used in plugging. The material must be suitable for use with the carbon 

dioxide stream; and 

Schlumberger Rationale: - 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24068

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24069

514
Response: EPA believes, considering the potentially corrosive nature of CO2 when it is in contact with 

water, that the requirement that the material must be compatible with the CO2 stream is appropriate. The 

final rule retains this requirement. 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: Proposed Rule: (d) Plugging report. Within 60 days after plugging or at the time 

of the next semi-annual report (whichever occurs earlier) the owner or operator 

must submit a plugging report to the Director. If the semi-annual report is due 

less than 15 days after completion of plugging, then the report must be 

submitted within 60 days after plugging. The report must be certified as 

accurate by the owner or operator and by the person who performed the plugging 

operation (if other than the owner or operator.) 

Schlumberger Suggested Revision: (d) Plugging report. Within 60 days after 

plugging the owner or operator must submit a plugging report to the Director. 

The report must be certified as accurate by the owner or operator and by the 

person who performed the plugging operation (if other than the owner or 

operator.) 

Schlumberger Rationale: Simplification 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads, "Within 

60 days after plugging the owner or operator must submit a plugging report to the Director." 

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment); 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: §146.93 Post-injection site care and site closure. 

Proposed Rule: (1) The owner or operator shall continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site closure 

plan for at least 50 years following the cessation of injection. At the 

Director’s discretion, the monitoring will continue until the geologic 

sequestration project no longer poses an endangerment to USDWs. 

Schlumberger Suggested Revision: (1) The owner or operator shall continue to 

conduct monitoring as specified in the Director-approved post-injection site 

care and site closure plan, pursuant to the performance based criteria described 

in 146.93(3). 

Schlumberger Rationale: The 50 year default period is not based on any 

scientific or technical information and could be considered arbitrary and 

capricious. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24070

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24071

515
Proposed Rule: (2) If the owner or operator can demonstrate to the satisfaction 

of the Director before 50 years, based on monitoring and other site-specific 

data, that the geologic sequestration project no longer poses an endangerment to 

USDWs, the Director may approve an amendment to the post-injection site care and 

site closure plan to reduce the frequency of monitoring or may authorize site 

closure before the end of the 50-year period. 

Schlumberger Suggested Revision: (2) If the owner or operator can demonstrate to 

the satisfaction of the Director that the geologic sequestration project no 

longer poses an endangerment to USDWs, the Director may approve an amendment to 

the post- injection site care and site closure plan to reduce the frequency of 

monitoring or may authorize site closure. 

Schlumberger Rationale: - 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most cases 

or is arbitrary and capricious. EPA proposed a default post-injection site care timeframe of 50 years 

based on a review of research studies, industry reports, and existing environmental programs. This 

analysis was included in an EPA-prepared background document that is available in the federal docket, 

titled "Computational Modeling of Underground Injection of Carbon Dioxide for Determination of 

Area-of-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various 

default timeframes based on additional review of research studies and evaluation of public comments. 

While numerous commenters suggested that EPA shorten the monitoring timeframe, none of the 

commenters provided sufficient data or other evidence to warrant a change in the proposed timeframe. 

While the 10- or 30-year timeframe suggested by some of these commenters may be within the 

timeframe suggested in some studies, EPA believes that the potential risks of endangering USDWs will 

likely not decline within these timeframes and available data, including data submitted by commenters, 

do not support a different default timeframe. However, EPA recognizes that alternative timeframes may 

be appropriate under limited, specific circumstances. 

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC 

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the 

post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording 

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the permitting 

process based on substantial data, that an alternative PISC timeframe may be appropriate if it ensures 

non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for 

post-injection site care will be necessary in all but a limited number of cases. This default 50 year postinjection site care timeframe represents a reasonable and protective monitoring period based on a review 

of research studies, industry reports, and existing environmental programs, and evaluation of public 

comments. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

516
EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will assist 

Directors in evaluating proposed well plugging plans and post-injection site care and site closure plans 

under §146.92 and §146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells; perform post-injection monitoring; demonstrate the 

appropriateness of an alternative post-injection site care time frame; demonstrate non endangerment; and 

perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Proposed Rule: (3) Prior to authorization for site closure, the owner or 

operator must submit to the Director a demonstration, based on monitoring and 

other site-specific data, that the carbon dioxide plume and pressure front have 

stabilized and that no additional monitoring is needed to assure that the 

geologic sequestration project does not pose an endangerment to USDWs. 

Schlumberger Suggested Revision: (3) Prior to authorization for site closure, 

the owner or operator must demonstrate to the Director, based on monitoring and 

other site-specific data that no additional monitoring is needed to assure that 

the geologic sequestration project does not pose an endangerment to USDWs, 

considering the following:. (i) the estimated magnitude and extent of the AOR 

based on measurements and modeling; (ii) that CO2 movement and pressure changes 

match model predictions, (iii) the estimated location of the detectable CO2 

plume based on measurement and modeling (measuring magnitude of saturation 

within (iv) that there is no evidence of significant leakage of either CO2 or 

formation fluids that endanger USDWs; (v) that the CO2 plume and displaced 

formation fluid are not expected to migrate in the future in a manner that 

encounters a potential leakage pathway; and, (vi) that wells at the site are not 

leaking and have maintained integrity. 

Schlumberger Rationale: Establishes the performance based criteria for selecting 

the monitoring period. the plume or mapping the edge of it); 

Response: The post-injection site care requirements in the final GS rule, §146.93(b), incorporate a 

combination of a fixed timeframe and a performance standard approach. Specifically , the GS rule offers 

owners or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing the 

Director discretion to shorten or lengthen the PISC timeframe during the post-injection period based on 

site-specific data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to 

allow a Class VI well owner or operator to demonstrate, during the permitting process based on 

substantial data, that an alternative PISC timeframe may be appropriate if it ensures non-endangerment 

of USDWs pursuant to requirements at §146.93(c). 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for 

post-injection site care will be necessary in most cases. The default 50 year post-injection site care 

timeframe represents a reasonable and protective monitoring period based on a review of research 

studies, industry reports, and existing environmental programs, and evaluation of public comments. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24072

517
exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist Directors 

in evaluating proposed well plugging plans and post-injection site care and site closure plans under 

146.92 and 146.93. The guidance describes recommended approaches for how an owner or operator 

could plug injection and monitoring wells; demonstrate the appropriateness of an alternative postinjection site care time frame; perform post-injection monitoring; demonstrate non endangerment; and 

perform site closure activities. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Proposed Rule: (e) Once the Director has authorized site closure, the owner or 

operator must submit a site closure report within 90 days that must thereafter 

be retained at a location designated by the Director. The report must include: 

Schlumberger Suggested Revision: (e) Once the Director has authorized site 

closure, the owner or operator must submit a site closure report within 90 days 

after completion of all closure operations. The report must include: 

Schlumberger Rationale: What is the retention period? Many other programs have a 

three year limit for retention of records. EPA is the steward of information at 

this point of the project, not the owner or operator. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention such 

as site closure reports. EPA believes that the requirements that the owner or operator retain for ten years 

following site closure, records collected during the post-injection site care period at §146.93(f) and 

§146.93(h) are appropriate for the post-injection and site closure period to ensure that data are available 

to support non-endangerment demonstrations and to address any concerns that may arise following site 

closure. This data will also support EPA's review of project data as part of the adaptive rulemaking 

approach. 

Other EPA Comment Codes and Descriptions: 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Proposed Rule: (1) Documentation of appropriate injection and monitoring well 

plugging as specified in §146.92 and paragraph (c) of this section. The owner or 

operator must provide a copy of a survey plat which has been submitted to the 

local zoning authority designated by the Director. The plat must indicate the 

location of the injection well relative to permanently surveyed benchmarks. The 

owner or operator must also submit a copy of the plat to the Regional 

Administrator of the appropriate EPA Regional Office; 

Schlumberger Suggested Revision: (1) Documentation of appropriate injection and 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24073

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24074

518
monitoring well plugging as specified in §146.92 and paragraph (c) of this 

section. The owner or operator must provide a copy of a survey plat which has 

been submitted to the local zoning authority designated by the Director. The 

plat must indicate the location of the injection well(s) relative to permanently 

surveyed benchmarks. The owner or operator must also submit a copy of the plat 

to the Regional Administrator of the appropriate EPA Regional Office; 

Schlumberger Rationale: - 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on the 

deed to the facility property or other similar document examined during a title search that the land has 

been used to sequester CO2 on the deed to the facility property at the time of site closure. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: §146.94 Emergency and remedial response. 

Proposed Rule: (b) If the owner or operator obtains evidence that the injected 

carbon dioxide stream and associated pressure front may cause an endangerment to 

a USDW, the owner or operator must: 

Schlumberger Suggested Revision: (b) If the owner or operator obtains evidence 

that the injected carbon dioxide stream or associated pressure front endangers a 

USDW, the owner or operator must: 

Schlumberger Rationale: - 

Proposed Rule: (2) Take all steps reasonably necessary to identify and 

characterize any release; 

Schlumberger Suggested Revision: (2) Take all steps reasonably necessary to 

identify and characterize the endangerment posed; 

Schlumberger Rationale: - 

Proposed Rule: (3) Notify the Director within 24 hours; and 

Schlumberger Suggested Revision: (3) Notify the Director within 24 hours of 

becoming aware of the endangerment; and 

Schlumberger Rationale:- 

Proposed Rule: (d) The owner or operator must notify the Director and obtain his 

approval prior to conducting any well workover. 

Schlumberger Suggested Revision: (d) The owner or operator must notify the 

Director prior to conducting any well workover in response to any case of 

endangerment. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24075

519
Schlumberger Rationale:In critical situations, time spent obtaining approval 

could adversely affect the ability to conduct operations or increase the level 

of endangerment. 

Response: After consideration of comments, EPA has finalized the rule language in §146.94(b) as 

proposed. In the introductory section of §146.94(b), EPA clarifies that the pressure front, as defined in 

§146.81, is a zone where the pressure differential is sufficient to cause the movement of injected fluids 

or formation fluids into a USDW. Therefore, displaced formation fluids are implicitly included in the 

requirements for §146.94. EPA also clarifies that owners or operators must take action when the CO2 

stream or pressure front may cause endangerment. In order to prevent the endangerment of USDWs, as 

required under §1421 of the SDWA, EPA expects the owner or operator to act preemptively and not 

wait until endangerment has occurred. This language is consistent with existing UIC requirements for 

other well classes and EPA’s authority under the SDWA. 

EPA clarifies that the Agency expects that owners or operators should take care not to damage the well 

when ceasing injection under §146.94(b)(1). At §146.94(b)(2), EPA is maintaining the requirement to 

“characterize the release.” In order to prevent the endangerment of USDWs, as required under §1421 of 

the SDWA, EPA expects the owner or operator to act preemptively and not wait until endangerment has 

occurred. This language is consistent with existing UIC requirements for other well classes and EPA’s 

authority under the SDWA. 

Concerning commenters’ suggestions for §146.94(b)(3), EPA clarifies that the 24 hours begins when the 

owner or operator obtains evidence of possible endangerment. EPA believes the rule language is clear 

on this requirement. 

Since proposal, EPA has modified the final regulatory language at §146.94(d) to clarify what constitutes 

a workover to address a well failure (which invokes remedial actions) and what constitutes a 

maintenance-type workover. For maintenance-type workovers (i.e., those that are scheduled in advance), 

the owner or operator must notify and gain approval from the Director prior to beginning the workover. 

In the final GS regulation, EPA has moved this requirement to the reporting requirements at §146.91(d) 

to clarify its intent. 

Regarding concerns that notification could delay responses, EPA clarifies that the GS rule, at §146.94

(b), describes procedures owners or operators must take in emergency situations. Specifically, upon 

determining that there is a problem with the well that may endanger a USDW, the owner or operator 

must first cease injection, then take all steps reasonably necessary to identify and characterize any 

release, notify the Director, and implement the approved emergency and remedial response plan, which 

may include a well workover. EPA believes that ceasing injection (which the owner or operator would 

do immediately and before notifying the Director) is the immediate action necessary to prevent or 

mitigate endangerment of USDWs, as required under the SDWA. 

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection timeframe 

(seeking comment) 

Comment: Proposed Rule: (4) If such a demonstration cannot be made (i.e., if the carbon 

dioxide plume and pressure front have not stabilized) after the 50 year period, 

the owner or operator must submit to the Director a plan to continue postinjection site care. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24970

520
Schlumberger Suggested Revision: Delete 

Schlumberger Rationale: No longer necessary 

Response: As described above, EPA believes that a default post-injection site care timeframe of 50 

years, with allowance of Director's discretion to shorten or lengthen this timeframe or approve an 

alternative PISC timeframe, is appropriate to ensure that USDWs are protected, while accounting for the 

variety of site-specific circumstances that may come in to play at GS sites. EPA expects that the Director 

would consider the types of information the commenter describes in determining whether the plume and 

pressure front no longer pose a risk of endangerment to USDWs and post-injection site care monitoring 

may be discontinued. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: Proposed Rule: (viii) Type or grade of cement; and 

Schlumberger Suggested Revision: (viii) Type or grade of cement; and additives 

Schlumberger Rationale: - 

Response: EPA agrees with the suggestion that §146.86(b)(1)(viii) be revised to also address cement 

additives. In the final GS rule, the subparagraph reads as follows: "Type or grade of cement and cement 

additives." 

Comment: -Prevention of "endangerment" of drinking water is a legislative requirement. 

Moreover, as noted in Section II.B. of the Preamble, Congress has defined 

endangerment to activities which "may result" in a system not meeting drinking 

water regulatory requirements, or otherwise affecting health. However, EPA 

appears to have defined the word "may" to include an additional level of 

possibility in stating, for example, that the post-injection site care period 

ends when there is "no potential threat of endangerment." Because 

"endangerment" is such a central theme throughout this regulation, we recommend 

that the rule clearly state that EPA interprets endangerment to mean "a 

reasonable likelihood" of damage based upon an objective assessment of genuine 

risk and not derived through any mathematically hypothesized possibility of 

damage. 

Response: The primary goal of the UIC program under the SDWA is to protect USDWs from 

endangerment. The UIC program provides that no injection shall be authorized if it results in “the 

movement of fluid containing any contaminant into [USDW]s, if the presence of that contaminant may 

cause a violation of any primary drinking water regulation under 40 CFR part 142 or may adversely 

affect the health of persons,” per §144.12. 

The Class VI GS rule, as part of the UIC program regulations, continues the program’s goal of ensuring

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24971

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21785

521
the protection of USDWs from endangerment. The permitting, siting, construction, operation, 

monitoring, and post-injection site care requirements in the Class VI GS rule are built on a long-standing 

protective regulatory framework, tailored to the unique aspects of CO2 GS. Defining endangerment is 

outside the scope of the Class VI GS rulemaking. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: - Minimum criteria for siting: We request that EPA revise proposed section 

146.83(a) to say that "Owners or operators of Class VI wells must demonstrate to 

the satisfaction of the Director that the wells will be sited in areas with a 

suitable geologic system, and in a manner that will not adversely impact the 

safe operation of nearby natural gas underground storage facilities, in 

compliance with applicable safety regulations and guidelines of the Department 

of Transportation." (Requested amended language in italics.) Further, the 

required geologic assessment should include analysis of potential leak paths 

through faulting, fracturing, or other migration paths from injected CO2 in 

formations in close proximity above or below a natural gas storage formation. 

Response: EPA believes that the extensive requirements for geologic site characterization (at §146.82), 

AoR evaluation (§146.84), and testing of the well during drilling (§146.87) are appropriate to ensure that 

permitting authorities have the necessary information to evaluate whether a specific site will allow safe 

injection of CO2. EPA adds that submittal and review of monitoring data (as required at §146.90) and 

the AoR reevaluation process (§146.84(e)) will provide an opportunity for an ongoing review of the site 

and a dialogue between the Director and the owner or operator to ensure that the project is being 

operated in a manner that protects USDWs from endangerment. EPA believes that any natural gas 

storage operations would be found in site characterization as would any faults or fractures. 

Other EPA Comment Codes and Descriptions: 3420 2.2.2.1 Scope of the inventory process (e.g., 

reliance on publicly available information, depth of wells) 

Comment: [In the paragraph below the text in 

all CAPS denotes added text.] 

§146.82(e): "A tabulation COMPILATION of all wells within the area of review 

which penetrate the injection or confining zone(s). TO SUPPLEMENT AND/OR VERIFY 

INFORMATION OF PUBLIC RECORD, OPERATORS SHALL USE REASONABLE METHODS 

TO IDENTIFY 

THE PRESENCE WELLS WITHIN THE AREA OF REVIEW THAT PENETRATE THE INJECTION 

OR 

CONFINING ZONE(S). Such data must include a description [...]" 

Response: EPA is retaining the requirement, which is now found in §146.82(a)(4), as proposed. EPA 

notes that the Director has the discretion in §146.84(c)(2) to require the owner or operator to supplement 

a data records search—including the use of ground, airborne, or geophysical (e.g., magnetic) surveys—if

there is reason to believe that the incompleteness of available information could compromise USDW 

protection from endangerment. EPA adds that all corrective action must be performed pursuant to the 

approved AoR and corrective action plan, which affords the Director the discretion to require any

Commenter Name: Pamela A. Lacey Letter ID: 0228

Commenter Organization: American Gas Association Comment ID: 21803

Commenter Name: Kristin Henry Letter ID: 0242

Commenter Organization: Sierra Environmental Law Program, Sierra Club Comment ID: 23331

522
additional information needed (including information that is not publically available) to ensure that all 

necessary corrective action is performed. EPA is developing guidance on AoR and corrective action at 

GS Class VI sites to assist owners or operators and Directors in evaluating requirements and proposed 

AoR and corrective action plans under 146.84. The guidance describes EPA's recommended approaches 

for the data to be considered in an initial AoR delineation, how to apply computational modeling to 

delineate the AoR, performing corrective action at GS sites, and, when appropriate, completing AoR 

reevaluations. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3420 2.2.2.1 Scope of the inventory process (e.g., 

reliance on publicly available information, depth of wells) 

Comment: [In the paragraph below the text in 

all CAPS denotes added text.] 

"Using methods approved by the Director, identify all penetrations, including 

active and abandoned wells and underground mines, in the area of review that may 

penetrate the confining zone OR OTHERWISE ACT AS CONDUITS FOR FLUID MOVEMENT 

INSIDE OR OUTSIDE THE CONFINING ZONE". 

Response: For the reasons described in the response above, EPA is retaining the requirement as 

proposed. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: The rule should incorporate a "non-interference principle" to keep one 

sequestration project from interfering with the effectiveness of another 

As EPA notes in the preamble (page 43506), "it is ... possible that multiple 

owners or operators will be injecting CO2 into formations that are hydraulically 

connected and thus the elevated pressure zones may intersect or interfere with 

each other." Our Environmental NGO Group agrees that this is a genuine 

possibility at this stage in GS implementation. Until comprehensive approaches 

to basin-scale management are developed, we urge the adoption of the following 

addition to §146.94: 

"(e) If an owner or operator obtains evidence that a pressure front associated 

with one geologic sequestration project intersects or threatens to intersect a 

pressure front associated with any other project, the owner or operator 

obtaining such evidence must notify the Director and the other owner or 

operator. If the Director determines that the pressure front associated with one 

project interferes or threatens to interfere with the ability of a project that 

began operations at an earlier date to sequester the earlier project’s total 

anticipated volume of the carbon dioxide stream as determined under §146.83(a), 

the Director may require the owner or operator of the project that began 

operations at a later date to modify operations as necessary to avoid such 

interference." 

Commenter Name: Kristin Henry Letter ID: 0242

Commenter Organization: Sierra Environmental Law Program, Sierra Club Comment ID: 23333

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22285

523
Response: EPA agrees with the commenter that there are a variety of factors that may affect the need 

for emergency and remedial response at GS sites. EPA believes that the GS Rule adequately protects 

USDWs from being endangered by multiple wells. EPA has decided not to adopt the commenter’s edit. 

However, the Agency believes that a site-specific emergency and remedial response plan that is 

informed by required site characterization data (per §146.82), modeling for AoR evaluations and 

reevaluations (per §146.84), and monitoring data (per §146.90) will appropriately address commenter 

concerns regarding the potential impacts of multiple GS projects. EPA has added a requirement at 

§146.94(d) that owners or operators must review their emergency and remedial response plan within one 

year of an AoR reevaluation required under §146.84 or following significant changes to the facility. 

Subsequently, the owners or operators must submit an amended plan or demonstrate to the Director that 

no amendment to the plan is needed based on the AoR reevaluation or any significant changes made to 

the facility. 

EPA also encourages owners or operators and permitting authorities to communicate planned GS 

activities during initial permitting activities to maximize coordination and minimize pressure 

interference. If a permit applicant (or the permitting authority) is aware of pending GS projects near a 

proposed well, the AoR delineation performed pursuant to §146.84 should account for the impacts of 

multiple owners and operators injecting within a single basin. EPA expects that, where multiple 

operators are involved, the Director will not approve modeling that does not account for changes that 

may result from all injection operations. 

EPA expects that changes within the AoR, such as the addition of new wells or projects that could 

potentially interfere with a GS project, will be identified as part of the AoR reevaluations required at 

§146.84(e) and would need to be addressed in a revised emergency and remedial response plan. EPA is 

developing guidance on the development and implementation of project plans for GS sites, including 

emergency and remedial response plans. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: The definition of "carbon dioxide stream" should not be restricted to CO2 

captured from industrial sources 

The definition of "carbon dioxide stream" in §146.81(b) includes only carbon 

dioxide "that has been captured from an emission source (e.g., a power plant)." 

Over time, the vast majority of sequestered CO2 is likely to be captured from 

such sources, but rules are also needed to govern the sequestration of naturally 

occurring CO2 produced from geologic formations. We suggest that the definition 

be revised to read as follows: 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf, starting on p. 

10, to see the original formatting.] 

"Carbon dioxide stream means that has been captured from an emission source 

(e.g., a power plant), carbon dioxide plus incidental associated substances 

derived from the source materials OF THE CO2 AND/OR the capture process, and 

any substances added to the stream to enable or improve the injection process. 

This subpart does not apply to any carbon dioxide stream that meets the 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22293

524
definition of a hazardous waste under 40 CFR part 261." 

Response: EPA disagrees with the suggested edit. The final definition of carbon dioxide stream at 

§146.81(d) remains unchanged and reads as follows: “[C]arbon dioxide that has been captured from an 

emission source (e.g., a power plant), plus incidental associated substances derived from the source 

materials and the capture process, and any substances added to the stream to enable or improve the 

injection process. This subpart does not apply to any carbon dioxide stream that meets the definition of a 

hazardous waste under 40 CFR part 261.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 3440 2.2.2.2 Evaluation of wells in the AoR (e.g., 

types of data to be reviewed) 

Comment: In proposed §144.55(a) the rule would require Class I, II (other than existing), 

III or VI permit applicants to identify the location "of all known wells within 

the injection well’s area of review which penetrate the injection zone" or, in 

the case of Class II wells operating over the fracture pressure of the injection 

formation, "all known wells within the area of review penetrating formations 

affected by the increase in pressure". 

Since injection in deep saline formations will result in an area of elevated 

pressure (above the original reservoir pressure) that will be larger than the 

CO2 plume and could affect overlying or underlying formations, we believe that 

the latter requirement for Class II wells operating above the fracture pressure 

should also apply to Class VI wells. This would help prevent the unwanted 

migration of reservoir fluids from outside the injection zone through existing 

wells in the confining zone, as a result of the pressure increase. We therefore 

suggest that §144.55(a) be revised to read as follows: 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Coverage. Applicants for Class I, II, (other than existing), or III, or VI 

injection well permits shall identify the location of all known wells within the 

injection well's area of review which penetrate the injection zone. In the case 

of Class II wells operating over the fracture pressure of the injection 

formation, applicants shall identify the location of all known wells within the 

area of review penetrating formations affected by the increase in pressure. 

Applicants for Class VI SHALL IDENTIFY THE LOCATION OF ALL KNOWN WELLS WITHIN 

THE AREA OF REVIEW PENETRATING THE INJECTION ZONE AND ALL KNOWN WELLS 

WHICH 

PENETRATE FORMATIONS AFFECTED BY THE INCREASE IN PRESSURE AND shall perform 

corrective action as specified in Sec. 146.84." 

Response: The final rule leaves §144.55 unchanged; i.e., Class VI wells are not addressed in this 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22295

525
provision. Based on its evaluation of all public comments and input on the proposed rule and NODA and 

Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and preamble 

for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: Emergency and remedial response, including response to potential problems 

relating to geologic features, is a necessary complement to corrective action 

and should remain in the rule. While wells are the most likely conduits for fluid 

movement into USDWs, the definition of corrective action and the relevant 

provisions in §146.84 do not take into account the potential for geologic 

features, such as faults, spill points or fractures, to act as conduits for CO2 

or other fluid migration, and hence breach of confinement. Actions to mitigate 

or remediate a potential breach of confinement, or a situation which might 

eventually lead to a breach of confinement, should not be limited to corrective 

action on wells. We therefore strongly support EPA’s inclusion of the Emergency 

and remedial response section. We propose two minor changes - change §146.94(b) 

(4) to read: 

[In the paragraphs below the text in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf 

to see the 

original formatting.] 

"Implement the emergency and remedial response plan approved by the 

Director, AND KEEP HIM APPRIZED OF THE IMPLEMENTATION." 

and §146.94(d) to read: 

"The owner or operator must notify the Director and obtain his approval prior to 

conducting any well workover OR OTHER REMEDIATION MEASURES NOT LISTED IN THE 

EMERGENCY AND REMEDIAL RESPONSE PLAN." 

Response: The final rule keeps the language in §146.94(b)(4) as proposed. EPA agrees that the Director 

should be kept apprised of progress on the implementation of the emergency and remedial response plan 

and expects that the plan itself will include provisions on communications with the Director. EPA agrees 

that an emergency and remedial response plan is an important part of assuring protection of USDWs 

from endangerment at GS sites. The requirements for an emergency and remedial response plan at 

§146.94(a) are designed to ensure that owners or operators, as part of their permit applications, 

comprehensively plan what actions would be necessary in the unlikely event of an emergency. The plan 

will ensure that operators know what entities and individuals must be notified and what actions must be 

taken to expeditiously mitigate any emergency situations. EPA is developing guidance on the 

development and implementation of emergency and remedial response plans for GS sites. 

Since proposal, EPA has modified the final regulatory language at §146.94(d) to clarify what constitutes 

a workover to address a well failure (which invokes remedial actions) and what constitutes a 

maintenance-type workover. For maintenance-type workovers (i.e., those that are scheduled in advance), 

the owner or operator must notify and gain approval from the Director prior to beginning the workover. 

In the final GS regulation, EPA has moved this requirement to the reporting requirements at §146.91(d) 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22299

526
to clarify its intent. 

Regarding concerns that notification could delay responses, EPA clarifies that the GS rule, at §146.94

(b), describes procedures owners or operators must take in emergency situations. Specifically, upon 

determining that there is a problem with the well that may endanger a USDW, the owner or operator 

must first cease injection, then take all steps reasonably necessary to identify and characterize any 

release, notify the Director, and implement the approved emergency and remedial response plan, which 

may include a well workover. EPA believes that ceasing injection (which the owner or operator would 

do immediately and before notifying the Director) is the immediate action necessary to prevent or 

mitigate endangerment of USDWs as required under the SDWA. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: The definition of "confining zone" should not be limited to formations overlying 

the injection zone, and should focus on limiting movement through the confining 

zone rather than out the injection zone 

The proposed definition of confining zone in §146.81(d) requires that the 

formation act as "a barrier" to fluid movement, which may be unnecessarily 

strict. The definition also fails to recognize that it is movement through and 

beyond the confining zone that needs to be limited. We suggest instead that the 

definition of "confining zone" read as follows: 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Confining zone means a geologic formation, group of formations, or part of a 

formation stratigraphically overlying the injection zone that acts as a 

barrier to limit fluid movement beyond THIS FORMATION, GROUP OF FORMATIONS, OR 

PART OF A FORMATION." 

Response: EPA disagrees with the suggested edit. However, the Agency has modified the final 

definition of confining zone at §146.81(d) to read as follows: “[A] geologic formation, group of 

formations, or part of a formation stratigraphically overlying the injection zone that acts as barrier to 

fluid movement. For Class VI wells operating under an injection depth waiver, confining zone means a 

geologic formation, group of formations, or part of a formation stratigraphically overlying and 

underlying the injection zone.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: The second sentence of the definition of ‘geologic sequestration project" should 

be amended to refer more generally to formation fluids and be transferred to the 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22300

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22301

527
definition of "area of review" 

We suggest the following amendment to §146.81(d) in order to be more inclusive 

on the types of fluid that could be displaced: 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"[...] It includes the subsurface three-dimensional extent of the carbon dioxide 

plume, associated pressure front, and displaced brine FORMATION FLUIDS, as 

well as the surface area above that delineated region. 

We also suggest that this second sentence of the definition of geologic 

sequestration project be transferred to the definition of area of review as 

recommended above. The language provided above reflects the change from "brine" 

to "formation fluids." 

Moreover, we suggest that the present restriction of Class VI to formations 

below the lowermost USDW is more appropriately addressed elsewhere. Accordingly, 

we recommend that geologic sequestration project be defined as follows: 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Geologic sequestration project means an injection well or wells used to emplace 

a carbon dioxide stream beneath the lowermost formation containing a USDW INTO 

AN INJECTION ZONE FOR GEOLOGIC SEQUESTRATION. It includes the subsurface threedimensional extent of the carbon dioxide plume, associated pressure front, and 

displaced brine, as well as the surface area above that delineated region." 

The term "pressure front" should be replaced with the more accurate term "area 

of elevated pressure" throughout the rule 

The term "pressure front" in 146.81(d) is likely to be scientifically inaccurate 

as it implies a front, or discontinuity in pressure, whereas in reality there 

will be a continuous pressure gradient in the formation in most cases. We 

suggest globally replacing "pressure front" with "area of elevated pressure" 

throughout the rule. 

Response: EPA disagrees with the suggested edit. However, the Agency has modified the definition of 

geologic sequestration project at §146.81(d) to read as follows: “Geologic sequestration project means 

an injection well or wells used to emplace a carbon dioxide stream beneath the lowermost formation 

containing a USDW; or, wells used for geologic sequestration of carbon dioxide that have been granted 

a waiver of the injection depth requirements pursuant to requirements at §146.95; or, wells used for 

geologic sequestration of carbon dioxide that have received an aquifer exemption expansion. It includes 

the subsurface three-dimensional extent of the carbon dioxide plume, associated pressure front, and 

displaced brine, as well as the surface area above that delineated region.” 

The final definition of pressure front at §146.81(d) also is unchanged and reads as follows: “[T]he zone 

528
of elevated pressure that is created by the injection of carbon dioxide into the subsurface. For the 

purposes of this subpart, the pressure front of a carbon dioxide plume refers to a zone where there is a 

pressure differential sufficient to cause the movement of injected fluids or formation fluids into a 

USDW.” 

Based on its evaluation of all public comments and input on the proposed rule and the NODA and 

Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the final rule 

and preamble for additional information. 

Other EPA Comment Codes and Descriptions: 1616 1.3.1.3 Fluid movement 

Comment: The term "transmissive fault or fracture" should be clarified 

The proposed rule in §146.83(a)(2) requires a confining zone(s) that is free of 

transmissive faults or fractures, while §146.81 defines this term as "A fault or 

fracture that has sufficient permeability and vertical extent to allow fluids to 

move between formations". We suggest the following modification to the 

definition in §146.81(d) in order to avoid unduly restricting movement that is 

merely between formations (compare our comments above on the definition of 

"confining zone"): 

[In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Transmissive fault or fracture means a fault or fracture that has sufficient 

permeability and vertical extent to allow fluids to move between formations 

BEYOND A CONFINING ZONE." 

Response: EPA has retained the definition in the final rule. While there may be cases, as the commenter 

suggests, where a transmissive fault may exist but not pose a concern for confinement, i.e., in the 

context of all other information, EPA believes the definition is accurate. Based on its evaluation of all 

public comments and input on the proposed rule and NODA and Request for Comment EPA has made 

many revisions to the GS Rule. See the final rule and the geologic site characterization discussion in the 

preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 3120 2.1.2 Need to identify additional confining and 

containment zones (seeking comment) 

Comment: Secondary confining zone 

§146.83 allows the Director to require additional confining zones, at his 

discretion. We do not believe that this will always be necessary - a good 

primary zone should be sufficient. Where additional hazards justify it, a 

secondary zone might be desirable. In all cases, we caution against relying on 

secondary confinement in place of establishing with a greater degree of 

certainty the suitability of the primary zone. Potential problems are best 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22304

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22305

529
identified and anticipated early, and the focus should be on site 

characterization to show with confidence whether the confining zones are 

adequate. We suggest striking part (b) in §146.83 as it seems redundant. 

However, the Director must have the discretion to require a secondary confining 

zone if needed. We therefore recommend clarifying part (a)(2) to read 

explicitly: 

[In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"A confining zone, or zones, that is ARE free of transmissive faults or 

fractures and of sufficient areal extent and integrity to contain the injected 

carbon dioxide stream and displaced formation fluids and allow injection at 

proposed maximum pressures and volumes without initiating or propagating 

fractures in the confining zone(s)" 

Response: EPA disagrees with the suggested edit, but agrees that providing the Director discretion will 

allow consideration of a range of sites for GS, based on site-specific conditions and ensure USDW 

protection. EPA believes that requiring appropriate site characterization by the owner or operator (under 

§146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific 

geologic data will afford the greatest protection of USDWs from endangerment. The Agency believes 

that in some geologic settings, the presence and identification of additional confining and containment 

zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These 

formations could further impede vertical fluid movement, allow for pressure dissipation, and provide 

additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection 

of USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: An additional concern is that both §146.81 and §146.84(a) state that the AOR is 

"based on computational modeling". This could imply that the Area of Review 

could be based solely on computational modeling. Instead, the AOR should be 

based on computational modeling, monitoring and operational data (and kept 

updated until closure is approved). All references to computational modeling in 

relation to the Area of Review in this section, as well as in the definition of 

Area of Review in §146.81 should be amended as appropriate to read "based on 

computational modeling, as well as monitoring and other operational data." We 

urge that the definition be revised as follows: 

[In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Area of review means the AREA that may be impacted by the injection activity. 

The area of review is based on computational modeling, as well as MONITORING AND 

OTHER OPERATIONAL DATA, that account for the physical and chemical properties of 

all phases of the injected carbon dioxide stream. IT INCLUDES THE SUBSURFACE 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22307

530
THREE-DIMENSIONAL EXTENT, THROUGHOUT THE OPERATING LIFE OF THE FACILITY, 

OF THE 

CARBON DIOXIDE STREAM PLUME, ASSOCIATED PRESSURE FRONT, AND DISPLACED 

FORMATION 

FLUIDS, AS WELL AS THE OVERLYING FORMATIONS AND SURFACE AREA ABOVE THAT 

DELINEATED REGION." 

Response: Based on review of all public comments on the AoR definition at 146.84(a), the Agency has 

modified it to read as follows: "The region surrounding the geologic sequestration project where 

USDWs may be endangered by the injection activity. The area of review is delineated using 

computational modeling that accounts for the physical and chemical properties of all phases of the 

injected CO2 stream and is based on available site characterization, monitoring, and operational data." 

The definition in the proposed rule accounted for the varying physical and chemical properties of the 

CO2 including free-phase and water-dissolved CO2, as the commenter suggests. The definition in the 

final rule will continue to do so. 

EPA is developing guidance on AoR and corrective action at GS Class VI sites to assist owners or 

operators and Directors in evaluating requirements and proposed AoR and corrective action plans under 

146.84. The guidance describes EPA's recommended approaches for the data to be considered in an 

initial AoR delineation, how to apply computational modeling to delineate the AoR, performing 

corrective action at GS sites, and, when appropriate, completing AoR reevaluations. The guidance will 

be available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA clarifies that the initial AoR delineation required under 146.84(c) is performed prior to injection, 

and therefore no monitoring or operational data would yet exist. The AoR delineation models will 

incorporate all available site data and anticipated operating procedures (e.g., injection rates and 

volumes). 

The AoR reevaluation process required at 146.84(e) requires owners or operators to incorporate 

monitoring or operational data and make any needed adjustments to corrective action or monitoring at 

the site. EPA believes that the iterative process of AoR reevaluation is appropriate to verify that the CO2 

plume and pressure front are moving through the subsurface as predicted, verify the accuracy of the 

delineation model (or identify needed changes), and refine testing and monitoring activities to ensure 

that USDWs are protected from endangerment and that there would be adequate warning of potential 

problems at the site before any endangerment could occur. 

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: In particular, monitoring above the caprock, sometimes informally referred to as 

"above-zone monitoring, and covered in (d), is a tested monitoring method [FN23], and 

one that can be key to verifying the integrity and lateral extent of the caprock 

(or confining zone). We support its inclusion, but also recognize that it might 

not be necessary to employ this method every time. We would only consider its 

omission acceptable only if another method capable of testing and verifying the 

integrity of the confining zone is being used. Subpart (d) would also cover 

groundwater monitoring near the surface, at a long distance from the caprock. It 

is our understanding that researchers from the Lawrence Livermore National 

Laboratory are already confident in the merits of this approach and its accuracy 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22319

531
in detecting small amounts of CO2. We therefore recommend the following minor 

changes to §146.90(d): 

[In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Periodic monitoring of the ground water quality and GEOPHYSICAL, geochemical OR 

OTHER changes above the confining zone(s) that may be a result of carbon dioxide 

OR OTHER INDUCED fluid movement through the confining zone or additional 

identified zones; provided however that the DIRECTOR MAY INSTEAD REQUIRE THE 

INCLUSION OF OTHER METHODS THAT TEST AND/OR VERIFY THE INTEGRITY OF THE 

CONFINING ZONE(S) WITH SIMILAR ACCURACY AND TO THE SAME OR LARGER AREAL 

EXTENT.(1) [...]" 

[FN23: Used successfully at the Frio pilot project, and already being 

considered for other projects.] 

Response: EPA clarifies that direct monitoring of ground water quality above the confining zone is 

important, and the GS rule requires this at §146.90(d). EPA believes that the ground water geochemical 

monitoring outlined in §146.90(d) will maximize protection of USDWs from endangerment at GS sites. 

Additional monitoring above the confining zone, as well as monitoring in additional formations, e.g., the 

injection zone, may also be necessary, and if the Director believes such monitoring is warranted he/she 

has the authority under §146.90(i) to require that it be included in the testing and monitoring plan. 

EPA adds that the baseline geochemical data required with the permit application at §146.82(a)(6) will 

provide information on predicting potential interactions between rocks and CO2 as the commenter 

suggests, and also expects that this information will inform the development and approval of a sitespecific testing and monitoring plan. EPA expects that the data will also help determine whether any 

changes are occurring above the confining zone and whether they might be associated with the CO2 

plume or pressure front. 

EPA further clarifies that the final rule at §146.90(g) requires indirect monitoring not above the 

confining zone but in the injection zone, unless the Director determines, based on site-specific geology, 

that indirect methods are not appropriate. Indirect methods can include geophysical methods. 

Other EPA Comment Codes and Descriptions: 4650 2.6.5 CO2 plume and pressure front tracking 

(seeking comment) 

Comment: To capture the points made above and resolve current inaccuracies or limitations 

in the proposed language, we recommend the following additional changes in 

§146.90(g): 

[In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf, to see the 

original formatting.] 

"(1) Testing and monitoring to track ESTABLISH the extent of the carbon 

dioxide plume and the position of the pressure front WITHIN DEFINED 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22325

532
THRESHOLDS, WITH THE ASSISTANCE OF MODELING TOOLS WHERE APPROPRIATE AND 

THROUGH 

DIRECT MEASUREMENTS OR INDIRECT, GEOPHYSICAL OR OTHER TECHNIQUES by either 

monitoring for pressure changes in the first formation overlying the confining 

zone or using indirect, geophysical techniques (e.g., seismic, electrical, 

gravity, or electromagnetic surveys and/or down-hole carbon dioxide detection 

tools); 

(2) TESTING AND MONITORING TO ESTABLISH THE EXTENT OF THE AREA OF ELEVATED 

PRESSURE THROUGH DIRECT MEASUREMENTS AND THE ASSISTANCE OF MODELING 

TOOLS." 

and in §146.90(h): 

[In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf, to see the 

original formatting.] 

"At the Director’s discretion, surface air monitoring METHODS and/or soil 

gas monitoring to detect movement of carbon dioxide that could SIGNAL 

endangerMENT OF a USDW. 

(1) The testing and monitoring plan must be based on potential vulnerabilities 

within the area of review; 

(2) The monitoring frequency and spatial distribution of surface air 

monitoring and/or soil gas monitoring must reflect baseline data and the 

monitoring plan must include how the proposed monitoring will yield useful 

information on the area of review delineation and/or compliance with standards 

under 40 CFR 144.12" 

Response: As described above, EPA believes that direct pressure measurements are appropriate and that 

direct pressure monitoring will be feasible at all GS sites and retains this provision in the final GS rule, 

at §146.90(g). 

EPA acknowledges that air and soil gas monitoring to ensure USDW protection is not necessary at all 

GS sites and agrees that the decision to use surface monitoring and the selection of monitoring methods 

for the purpose of USDW protection will be site-specific. 

The Agency believes that surface air and soil gas monitoring, when coupled with subsurface monitoring, 

may be appropriate at some GS projects to ensure USDW protection. EPA also acknowledges that 

surface air and soil gas measurements are subject to variability and may not be suitable in all settings as 

a method to ensure USDW protection. However, EPA does not believe that this should entirely preclude 

their use. The decision to use surface monitoring and the selection of monitoring methods will be sitespecific (e.g., may be influenced by geology, injection depth, and operational conditions) and must be 

based on potential risks to USDWs within the AoR. 

In the final rule, at §146.90(h), the decision to require such monitoring as an additional measure to 

ensure USDW protection rests with the Director as a means of identifying leaks that may pose a risk to 

USDWs and informing emergency notification of a Class VI owner or operator and UIC Director in the 

event of a USDW endangerment, pursuant to requirements at §146.91(c). 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

533
for Comment EPA has made many revisions to the GS rule. See the final rule and preamble for further 

discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 1620 1.3.2 Induced seismicity 

Comment: [In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf, to see the 

original formatting.] 

"Information on seismic history including the presence and depth of seismic 

sources and aN ASSESSMENT OF that WHETHER SUCH seismicity would not 

interfere with containment;" 

In addition, language should be added to the minimum criteria for siting in 

§146.83, clarifying that if induced or natural seismicity poses unacceptable 

risks, a permit will not be granted. In order properly to assess the risk of 

significant induced seismicity in light of permitted operating conditions, the 

rule may need to require applicants to submit information beyond what is 

currently required in proposed §146.82. The effects of any seismic events during 

project operation should also be taken into account when updating, or 

considering whether to update, the Area of Review and Corrective Action Plan, 

the Testing and Monitoring Plans, and the Emergency and Remedial Response Plans, 

as well as any other plans as necessary. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS Rule. See the final rule and 

preamble discussion of geologic site characterization for further discussion on EPA's final approach. 

EPA clarifies that under §146.82(a)(21), the Director has the authority to require additional information 

to be submitted with the permit application. EPA agrees that seismic events should be taken into account 

when updating the plans or other permit conditions and clarifies that existing language at §144.39(a)(2) 

allows the Director to modify the permit when he or she receives new information that was not available 

at the time of permit issuance. 

Other EPA Comment Codes and Descriptions: 3420 2.2.2.1 Scope of the inventory process (e.g., 

reliance on publicly available information, depth of wells) 

Comment: [In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

§146.82(e): "A tabulation COMPILATION of all wells within the area of review 

which penetrate the injection or confining zone(s). TO SUPPLEMENT AND/OR VERIFY 

INFORMATION OF PUBLIC RECORD, OPERATORS SHALL USE REASONABLE METHODS 

TO IDENTIFY 

THE PRESENCE WELLS WITHIN THE AREA OF REVIEW THAT PENETRATE THE INJECTION 

OR 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22327

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 25256

534
CONFINING ZONE(S). Such data must include a description [...]" 

[FN22: NETL , for example, has developed an electromagnetic 

system that can be used for areal or ground-based identification of wells 

(casings).] 

Additionally, we believe that problematic wells may not be limited to the 

confining zone, as would be the case if confinement were to be breached, or if 

pressure effects caused by the injection caused fluid movement outside the 

defined confining zone. We recommend the following modification in §146.84(c) 

(2): 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Using methods approved by the Director, identify all penetrations, including 

active and abandoned wells and underground mines, in the area of review that may 

penetrate the confining zone OR OTHERWISE ACT AS CONDUITS FOR FLUID MOVEMENT 

INSIDE OR OUTSIDE THE CONFINING ZONE". 

Response: EPA is retaining the requirement at §146.82(b), which is now found in §146.82(a)(4), as 

proposed. EPA adds that all corrective action must be performed pursuant to the approved AoR and 

corrective action plan, which affords the Director the discretion to require any additional information 

needed (including information that is not publically available) to ensure that all necessary corrective 

action is performed. EPA notes that the Director has the discretion at §146.84(c)(2) to require the owner 

or operator to supplement a data records search—including the use of ground, airborne, or geophysical 

(e.g., magnetic) surveys—if there is reason to believe that the incompleteness of available information 

could compromise USDW protection from endangerment. For these reasons, EPA is retaining the 

requirement at §146.84(c)(2) as proposed. 

Regarding the concern about identifying wells other than those that penetrate the confining zone, EPA 

adds that the Director the discretion to require any additional information needed to ensure that all 

necessary corrective action is performed, including information on wells that are above the confining 

zone, if site-specific information indicates such a need to ensure USDW protection. 

Other EPA Comment Codes and Descriptions: 2046 1.5.2.3 Continuing to classify CO2 injection for 

EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment) 

Comment: The GWPC also recommends EPA consider retaining all geologic sequestration in 

oil and gas reservoirs under the jurisdiction of Class II UIC programs and 

create a subclass within this program for geologic storage of carbon dioxide. 

This subclass (Class II GS) would be used for those wells that depart from the 

traditional uses of Class II wells for enhanced recovery, and result in the 

application of Class VI standards. This change would eliminate any confusion 

over whether a Class II CO2 injection well used for enhanced recovery might also 

need a Class VI permit and would avoid the need to change jurisdiction for a 

well from one state agency to another over time. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24835

535
Response: EPA disagrees that the risks posed by long term storage of CO2 for GS can be addressed 

under existing UIC requirements, such as those for Class II wells. EPA believes and the administrative 

record supports that there are significant differences between how EOR and GS projects are operated, as 

well as the different risks posed by these different injection activities. The new tailored approach of the 

GS rule was designed to address the general risks deep injection may pose to USDWs and was tailored 

specifically to address the risks posed by long term storage of CO2 (i.e., very large volumes, very long 

time-periods, and reservoir pressure conditions). 

In response to the comment on the burden of changing regulatory agencies in the middle of an operation, 

EPA clarifies that primacy is granted to a state, not to a specific agency within that state, and states may 

choose which agency implements the Class VI program. States may, for example, choose an 

environmental quality protection agency (non-Class II) or the state's traditional oil and gas regulatory 

agency to implement the Class VI program as long as the program meets the minimum federal 

requirements for Class VI wells as required under section 1422 of SDWA. Some states manage all 

injection well classes under Section 1422 and through a single agency, while in other states, Class II 

programs are run by oil and gas agencies. 

Regardless of the specific Agency the state selects to assume regulatory authority for Class VI 

operations, the state must obtain primacy for the 1422 Class VI program. Furthermore, the state may 

determine that a memorandum of understanding (MOU) between several state agencies regarding 

specific projects can facilitate this process without needing to change regulatory agencies after Class II 

projects have transitioned to a Class VI permit. 

Other EPA Comment Codes and Descriptions: 2048 1.5.2.4 Oppose Class VI/ Support Class V 

experimental technology well 

Comment: EPA Proposal: 4. Adding § 144.15 to read as follows. 

§ 144.15 Prohibition of non-experimental Class V wells for geologic 

sequestration. 

The construction, operation or maintenance of any non-experimental Class V 

geologic sequestration well is prohibited. 

GWPC Recommendations: This provision should be deleted if EPA does limit Class 

VI wells to injection below the lowermost USDW in the final rule to allow 

Directors to selectively authorize GS in areas with USDWs below the injection 

zone. 

In addition, it is recommended that all GS into basalts, coal seams, salt domes, 

and shales be conducted under Class V as experimental wells initially and then 

as commercial scale Class V wells/projects if the experimental projects 

demonstrate that these sites can be suitable for geological sequestration while 

preventing endangerment of USDWs. 

Rationale: Keeping these wells under Class V would allow EPA and the states to 

gain enough experience to develop suitable permitting requirements for such 

wells and to tailor those requirements until the agencies are ready to adapt the 

Class VI regulations. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24836

536
Response: The text at 144.15 is retained in the final regulation; the construction, operation or 

maintenance of any non-experimental Class V GS well is prohibited under the final rule. The final rule 

contains tailored requirements for Class VI wells to ensure that GS projects are permitted sited, 

constructed, operated, and closed in a manner that does not endanger USDWs. 

EPA also clarifies that the final GS rule does not categorically preclude injection of CO2 into any 

formation types. Existing experimental GS projects may be permitted as described in UIC Program 

Guidance #83: Using the Class V Experimental Technology Well Classification for Pilot Carbon 

Geologic Sequestration Projects, which provided information for permitting authorities to consider when 

permitting experimental GS projects (i.e., those projects that are designed to test new, unproven 

technologies, per the definition of a Class V experimental technology well). EPA adds that, following 

finalization of the GS rule, all GS projects that are not for experimental purposes must be re-permitted as 

Class VI wells and be subject to the final GS requirements. EPA expects that, after promulgation of the 

final rule, a limited number of experimental injection projects to test GS technology will continue, e.g., 

to inform the technology associated with GS into basalts, coal seams, and salt domes. 

The Agency also clarifies that it does not consider it appropriate to permit CO2 injection wells that are 

testing the injectivity or appropriateness of an individual formation (e.g., as a prelude to a commercialscale operation) as Class V experimental technology wells. Such wells must be permitted as Class VI 

wells. 

EPA is preparing an addendum to UICPG #83 that describes the use of the Class V experimental 

technology well classification to clarify permitting for Class V wells. This addendum will address 

shifting of Class V experimental projects to full-scale GS projects and the future use of the Class V 

experimental technology well subclass for research and testing of new GS technologies. This guidance 

will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: Rule Provision: 144.18 

EPA Proposal: 5. Adding § 144.18 to read as follows. 

§ 144.18 Requirements for class VI wells. 

Owners or operators of Class VI wells must obtain a permit. Class VI wells are 

not authorized by rule to inject. 

GWPC Recommendations: Support the proposed language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24837

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24838

537
Other EPA Comment Codes and Descriptions: 3500 2.2.3 Area of Review Reevaluation (seeking 

comment); 5700 2.12 Comments on the proposed duration of Class VI permits (seeking comment) 

Comment: Rule Provision: 144.36 

EPA Proposal: 6. Section 144.36 is amended by revising the first two sentences 

in paragraph (a) to read as follows: 

§ 144.36 Duration of permits. 

(a) Permits for Class I and V wells shall be effective for a fixed term not to 

exceed 10 years. UIC Permits for Class II, III and VI wells shall be issued for 

a period up to the operating life of the facility. * * * 

* * * * * 

GWPC Recommendations: Support the proposed language. 

Rationale: The proposed provision is considered acceptable as long as the 

iterative reevaluation process established for AoRs also applies to other 

aspects of the project including modeling, characterization, operational 

decisions, monitoring, financial assurance, etc. It is recognized that 

Directors may also depend on 144.39 regarding modification and revocation of 

Class VI permits. 

Response: EPA acknowledges the commenter’s support and notes that the final rule retains this 

requirement. The final rule maintains the lifetime permit provision and clarifies that the permit extends 

through the post-injection site care period (144.36(a)). It also adds a requirement that the Director 

review each Class VI permit at least once every 5 years to determine whether it should be modified, 

revoked and reissued, terminated or a minor modification made as provided in §§144.39, 144.40, or 

144.41. The Director’s review will be informed by the owners’ or operators’ iterative reevaluation of the 

project. Specifically, the final rule includes a requirement that the AoR be reevaluated at least every five 

years, and also requires owners or operators to review and update the AoR and corrective action plan, 

the testing and monitoring plan, and the emergency and remedial response plan throughout the life of the 

project (146.84(e), 146.90(j), and 146.94(d)). Owners or operators must review each plan and identify 

necessary amendments or demonstrate to the Director that no amendment is needed. In no case can 

reviews occur less often than once every five years. The iterative process and subsequent plan 

reevaluations ensure that time and resources are committed to the most critical aspects of the permit in 

preventing endangerment to USDWs. EPA believes that the iterative process of developing and 

executing the various plans required of GS well operators in the final rule (e.g., for AoR and corrective 

action, testing and monitoring, injection well plugging, post-injection site care, and emergency and 

remedial response) is tailored to the unique aspects of—and is more appropriate for–GS than 

establishing a finite permit duration. 

EPA emphasizes that the final rule requires owners or operators to revise their cost estimates for 

financial assurance within 60 days of amendments to the AoR and corrective action plan, the injection 

well plugging plan, the post-injection site care and site closure plan, or the emergency and remedial 

response plan (40 CFR 146.85(c)(2). 

EPA emphasizes that, the Director has the authority to revise the permit if project operations change or 

if the Director believes based on monitoring or operational data that the project may endanger USDWs. 

EPA has also added text to 144.39(a)(5) that permit modifications would be required if the Director 

determines that a modification is necessary based on an AoR reevaluation, amendments to any of the 

538
project plans, or a review of the testing and monitoring results. The Director may also choose to require 

minor permit modifications under 40 CFR 144.41, depending on the extent of the plan amendment. All 

permit modifications, except minor modifications under 40 CFR 144.41, require an opportunity for 

public comment on the portion of the permit that is being reopened pursuant to requirements under 40 

CFR Part 124. 

Other EPA Comment Codes and Descriptions: 5900 2.14 Other administrative requirements under 40 

CFR 144 

Comment: EPA Proposal: 7. Section 144.39 is amended by revising the second sentence in 

paragraph (a) introductory text and by revising the second sentence in paragraph 

(a)(3) introductory text to read as follows: 

§ 144.39 Modification or revocation and reissuance of permits. 

* * * * * 

GWPC Recommendations: Support the proposed language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 5900 2.14 Other administrative requirements under 40 

CFR 144 

Comment: Rule Provision: 144.39 

EPA Proposal: (a) * * * For Class I hazardous waste injection wells, Class 

II, Class III or Class VI wells the following may be causes for revocation and 

reissuance as well as modification; and for all other wells the following may be 

cause for revocation or reissuance as well as modification when the permittee 

requests or agrees. * * * 

* * * * * 

(3) * * * Permits other than for Class I hazardous waste injection wells, 

Class II, Class III or Class VI wells may be modified during their terms for 

this cause only as follows: * * * * * * * * 

GWPC Recommendations: Support the proposed language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24839

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24840

539
comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 5900 2.14 Other administrative requirements under 40 

CFR 144 

Comment: EPA Proposal: (2) When the Director determines that a Class I, II, III or VI 

well lacks mechanical integrity pursuant to § 146.8 or § 146.89 for Class VI of 

this chapter, he/she shall give written notice of his/ her determination to the 

owner or operator. * * * 

* * * * * 

GWPC Recommendations: Support the proposed language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 5900 2.14 Other administrative requirements under 40 

CFR 144 

Comment: Rule Provision: 144.52 

EPA Proposal: 9. Section 144.52 is amended by revising paragraph (a)(8) to 

read as follows: 

§ 144.52 Establishing permit conditions. 

(a) * * * 

(8) Mechanical integrity. A permit for any Class I, II, III or VI well or 

injection project which lacks mechanical integrity shall include, and for any 

Class V well may include, a condition prohibiting injection operations until the 

permittee shows to the satisfaction of the Director under § 146.08 or § 146.89 

for Class VI that the well has mechanical integrity. 

* * * * * 

GWPC Recommendations: Support the proposed language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24842

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24843

540
see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 5900 2.14 Other administrative requirements under 40 

CFR 144 

Comment: Rule Provision: 144.55 

EPA Proposal: § 144.55 Corrective action. 

(a) Coverage. Applicants for Class I, II, (other than existing), III or VI 

injection well permits shall identify the location of all known wells within the 

injection well’s area of review which penetrate the injection zone, or in the 

case of Class II wells operating over the fracture pressure of the injection 

formation, all known wells within the area of review penetrating formations 

affected by the increase in pressure. Applicants for Class VI shall perform 

corrective action as specified in § 146.84.* * * 

* * * * * 

GWPC Recommendations: Support the proposed language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 4324 2.4.4.1.2 Comments opposed to requiring 

injection below the lowermost USDW 

Comment: Rule Provision: 144.80 

EPA Proposal: 11. Section 144.80 is amended by revising the first sentence in 

paragraph (e) and by adding paragraph (f)to read as follows: 

§ 144.80 What is a Class V injection well? * * * * * 

(e) Class V. Injection wells not included in Class I, II, III, IV or VI. * * 

* 

(f) Class VI. Wells used for geologic sequestration of carbon dioxide. 

GWPC Recommendations: (4) For enhanced recovery of oil or natural gas where 

geologic sequestration is occurring during or in connection with enhanced 

recovery of oil or natural gas provided (i) there is reasonable expectation of 

more than insignificant future production volumes or rates as a result of carbon 

dioxide injection and (ii) operating pressures are no higher than reasonably

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24844

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24845

541
necessary to produce such volumes or rates; 

(f) Class VI. Wells injecting a carbon dioxide stream for geologic 

sequestration except those wells described in subsection (b)(4) of this section 

or otherwise excluded from this Class. 

Rationale: There should not be a blanket prohibition concerning injection above 

USDW’s or at specific levels. The determination of injection zones should be 

based upon appropriate containment. This is especially true in light of recent 

calls for changes in the definition of a USDW to include formations greater than 

10K PPM TDS and the fact that several states including Wyoming and California 

might be prevented from instituting geologic sequestration as a practical matter 

if injection were limited to above USDW’s due to the great depth of some USDW’s. 

This would create a situation where otherwise good injection zones are 

artificially excluded, thus decreasing the overall availability of geologic 

sequestration in the U.S. 

The GWPC also recommends EPA consider retaining all geologic sequestration in 

oil and gas reservoirs under the jurisdiction of Class II UIC programs and 

create a subclass within this program for geologic storage of carbon dioxide. 

This subclass (Class II GS) would be used for those wells that depart from the 

traditional uses of Class II wells for enhanced recovery, and result in the 

application of Class VI standards. This change would eliminate any confusion 

over whether a Class II CO2 injection well used for enhanced recovery might also 

need a Class VI permit and would avoid the need to change jurisdiction for a 

well from one state agency to another over time. 

Response: EPA acknowledges that there are limited circumstances where injection above the lowermost 

USDW can be performed in a manner that protects USDWs from endangerment, as long as appropriate 

protections are in place. The final GS rule at §146.95 establishes a process by which owners or operators 

can seek a waiver of the Class VI injection depth requirements for injection into non-USDW formations 

above and/or between USDWs. It establishes: 1) requirements specifying information that owners or 

operators must submit, and Directors must consider, in consultation with PWSS Directors; 2) procedures 

for public notice of a waiver application and for Director-Regional Administrator communication; 3) the 

waiver issuance process; and, 4) additional requirements that apply to owners or operators of Class VI 

wells granted a waiver of the injection depth requirements to ensure USDW protection above and below 

the injection zone. 

EPA adds that it has revised the definition of a Class VI well to read as follows: “Wells that are not 

experimental in nature that are used for geologic sequestration of carbon dioxide beneath the lowermost 

formation containing a USDW; or, wells used for geologic sequestration of carbon dioxide that have 

been granted a waiver of the injection depth requirements pursuant to requirements at §146.95 of this 

chapter; or, wells used for geologic sequestration of carbon dioxide that have received an expansion to 

the areal extent of an existing Class II enhanced oil recovery or enhanced gas recovery aquifer 

exemption pursuant to §§146.4 of this chapter and 144.7(d).” 

For additional information on the waiver approach, please see the final rule and preamble, as well as 

EPA's responses to comments on the Notice of Data Availability and Request for Comment. 

In response to the comment that GS wells should be regulated as Class II wells, EPA believes that 

injection for the primary purpose of long term storage is sufficiently different from Class II ER 

542
operations and warrants tailored requirements. For example, the volume of CO2 anticipated to be 

injected in Class VI wells is significantly greater than for Class II wells. Reservoir pressure conditions 

will also be different, with Class VI injection operations involving large volumes of CO2 and likely 

having higher pressures within their storage formations than Class II ER projects. The Director has the 

authority to determine at what point a Class VI permit is required for those projects that are transitioning 

from the primary purpose of EOR to long term storage of CO2. The final regulation provides a set of 

technical factors for the Director to evaluate in making this determination, at §144.19. EPA believes that 

this approach provides sufficient protection of USDWs when there is an increased risk to USDWs as 

compared to traditional Class II operations while allowing for site-specific flexibility. EPA is developing 

guidance on transitioning permits from Class II to Class VI. The guidance will assist Directors in 

determining whether an injection project should be transitioned from Class II where the primary purpose 

is oil and gas production to Class VI where the primary purpose is long-term storage of large volumes of 

CO2. This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA also recognizes that there is increasing demand for water resources and that technology 

improvements may make high TDS aquifers viable drinking water sources. However, EPA is not 

changing the USDW definition; changing the definition of a USDW is outside the scope of the GS 

rulemaking. The GS rule focuses on ensuring protection of USDWs, as required under the SDWA, by 

establishing regulations to ensure the safe injection of CO2 for long-term storage. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 144.51 

EPA Proposal: 8. Section 144.51 is amended by revising the first sentence in 

paragraph (q)(1) and the first sentence in paragraph (q)(2) to read as follows: 

§ 144.51 Conditions applicable to all permits. 

* * * * * 

(q) * * * 

(1) The owner or operator of a Class I, II, III or VI well permitted under this 

part shall establish mechanical integrity prior to commencing injection or on a 

schedule determined by the Director. Thereafter the owner or operator of Class 

I, II, and III wells must maintain mechanical integrity as defined in § 146.8 

and the owner or operator of Class VI wells must maintain mechanical integrity 

as defined in § 146.89 of this chapter. * * * 

GWPC Recommendations: (q) * * * 

(1) The owner or operator of a Class I, II, III or VI well permitted under this 

part shall establish mechanical integrity prior to commencing injection or on a 

schedule determined by the Director. Thereafter the owner or operator of Class 

I, II, and III wells must maintain mechanical integrity as defined in §146.8 and 

the owner or operator of Class VI wells must maintain mechanical integrity as 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24847

543
defined in §146.89 of this chapter. 

Rationale: EPA may want to reconsider the use of the term "or" as this implies 

that an initial MIT can be optional based on Directors discretion which 

contradicts 146.89 with respect to Class VI wells. Alternatively, the two 

provisions can be read together to require an initial MIT and to give the 

Director limited discretion to allow the scheduling of the initial MIT after 

some injection has occurred, such as may be required during initial testing of 

the well and injection zone. 

Response: EPA disagrees that the suggested edit is needed, and clarifies that all owners or operators 

must demonstrate internal and external mechanical integrity prior to commencing injection as required 

at §146.87(a)(4). 

Other EPA Comment Codes and Descriptions: 5900 2.14 Other administrative requirements under 40 

CFR 144 

Comment: Rule Provision: Part 146 

EPA Proposal: 12. The authority citation for part 146 continues to read as 

follows: 

Authority: Safe Drinking Water Act 42, U.S.C. 300f et seq.; Resource 

Conservation and Recovery Act, 42 U.S.C. 6901 et seq. 

GWPC Recommendations: Support the proposed language. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment letter for further details. For additional information on EPA's final regulatory approach, please 

see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 4324 2.4.4.1.2 Comments opposed to requiring 

injection below the lowermost USDW 

Comment: Rule Provision: 146.5 

EPA Proposal: 13. Section 146.5 is amended as follows: 

a. Revising the first sentence in paragraph (e) introductory text; and 

b. Adding paragraph (f). 

(f) Class VI. Wells used for geologic sequestration of carbon dioxide beneath 

the lowermost formation containing an underground source of drinking water 

(USDW). 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24848

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24849

544
GWPC Recommendations: (4) For enhanced recovery of oil or natural gas where 

geologic sequestration is occurring during or in connection with enhanced 

recovery of oil or natural gas provided (i) there is reasonable expectation of 

more than insignificant future production volumes or rates as a result of carbon 

dioxide injection and (ii) operating pressures are no higher than reasonably 

necessary to produce such volumes or rates; 

(f) Class VI. Wells injecting a carbon dioxide stream for geologic 

sequestration except those wells described in subsection (b)(4) of this section 

or otherwise excluded from this Class. 

Rationale: There should not be a blanket prohibition concerning injection above 

USDW’s or at specific levels. The determination of injection zones should be 

based upon appropriate containment. This is especially true in light of recent 

calls for changes in the definition of a USDW to include formations greater than 

10K PPM TDS and the fact that several states including Wyoming and California 

might be prevented from instituting geologic sequestration as a practical matter 

if injection were limited to above USDW’s due to the great depth of some USDW’s. 

This would create a situation where otherwise good injection zones are 

artificially excluded, thus decreasing the overall availability of geologic 

sequestration in the U.S. 

The GWPC also recommends EPA consider retaining all geologic sequestration in 

oil and gas reservoirs under the jurisdiction of Class II UIC programs and 

create a subclass within this program for geologic storage of carbon dioxide. 

This subclass (Class II GS) would be used for those wells that depart from the 

traditional uses of Class II wells for enhanced recovery, and result in the 

application of Class VI standards. This change would eliminate any confusion 

over whether a Class II CO2 injection well used for enhanced recovery might also 

need a Class VI permit and would avoid the need to change jurisdiction for a 

well from one state agency to another over time. 

Response: Please see the response to the commenter’s suggested revision to §144.80. 

Comment: Rule Provision: Part 146 Subpart H 

EPA Proposal: 14. Subpart H is added to read as follows: 

Subpart H - Criteria and Standards Applicable to Class VI Wells 

Sec. 

146.82 Required Class VI permit information. 

146.83 Minimum criteria for siting. 

146.84 Area of review and corrective action. 

146.85 Financial responsibility. 

146.86 Injection well construction requirements. 

146.87 Logging, sampling, and testing prior to injection well operation. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24851

545
GWPC Recommendations: Support the proposed language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: EPA Proposal: (b) This subpart applies to wells used to inject carbon dioxide 

specifically for the purpose of geologic sequestration, i.e., the long-term 

containment of a gaseous, liquid or supercritical carbon dioxide stream in 

subsurface geologic formations. 

GWPC Recommendations: (b) This subpart applies to wells used to inject carbon 

dioxide streams into saline formations for the purpose of geologic 

sequestration, i.e., the long-term containment of a carbon dioxide stream in 

subsurface geologic formations. 

Rationale: Use of the term "specifically" was removed as it implied Class VI 

wells could not be used for multiple purposes and still be Class VI 

Remove "gaseous, liquid or supercritical" as these terms are implied by the use 

of the term carbon dioxide. 

See the rationale discussion under 146.85 regarding inclusion or exclusion of 

the term "saline" 

Response: EPA disagrees with the suggested change. EPA believes that this paragraph, along with the 

definition of a CO2 stream at §146.81(d), appropriately convey the allowable injection activities that 

may be permitted as Class VI. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 2060 1.5.3 Comments on grandfathering of existing 

wells (seeking comment) 

Comment: EPA Proposal: (c) This subpart applies to owners and operators of permit or 

rule-authorized Class I industrial, Class II, or Class V experimental carbon 

dioxide injection projects who seek to apply for a Class VI geologic 

sequestration permit for their well or wells. If the Director determines that 

USDWs will not be endangered, such wells are exempt, at the Director’s 

discretion, from the casing and cementing requirements at §§ 146.86(b) and 

146.87(a)(1) through (3). 

GWPC Recommendations: (c) This subpart applies to owners and operators of permit 

or rule-authorized Class I industrial, Class II, or Class V experimental carbon 

dioxide injection projects who seek to apply for a Class VI geologic 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24852

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24853

546
sequestration permit for their well or wells or to convert to Class II GS 

operation. If the Director determines that USDWs will not be endangered, such 

wells are exempt, at the Director’s discretion, from such Class VI requirements 

contained in this subpart as the Director specifies. 

Rationale: The proposed EPA waiver applies only to the casing and cementing 

requirements. Directors should have the flexibility to waive other requirements 

as appropriate for conversions to Class VI. 

Response: EPA disagrees with commenters who suggest that other requirements (outside of well 

construction) should also be grandfathered. Following re-permitting of the project as GS, many of the 

unique factors of GS sites (e.g., increased reservoir pressures associated with large volumes of stored 

CO2 and the corrosivity of CO2 in the presence of water) will result in an increased risk profile, 

warranting the specific requirements in the final GS rule. Therefore, following re-permitting as Class VI 

wells, these projects must be subject to the operational, MIT, monitoring, reporting, plugging, and postinjection site care and site closure requirements in the final GS rule. See the discussion of EPA's final 

regulatory approach in the preamble to the GS rule for additional detail on these requirements. 

Comment: Rule Provision: 146.82 

EPA Proposal: Required Class VI permit information 

This section sets forth the information which the owner or operator must submit 

to the Director in order to be permitted as a Class VI well. The application 

for a permit for construction and operation of a Class VI well must include the 

following: 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Rule Provision: 146.82(a) 

EPA Proposal: (a) Information required in 40 CFR 144.31(e)(1) through (6); 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24868

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24869

547
Comment: EPA Proposal: (b) A map showing the injection well(s) for which a permit is 

sought and the applicable area of review. Within the area of review, the map 

must show the number, or name and location of all injection wells, producing 

wells, abandoned wells, plugged wells or dry holes, deep stratigraphic 

boreholes, State or EPA approved subsurface cleanup sites, surface bodies of 

water, springs, mines (surface and subsurface), quarries, water wells and other 

pertinent surface features including structures intended for human occupancy and 

roads. [Highlighted text: The map should also show faults, if known or 

suspected.] Only information of public record is required to be included on this 

map; 

GWPC Recommendations: (b) A surface map showing the proposed locations for the 

injection well(s) for which a permit is sought and the applicable area of 

review. Within the area of review, the map must show the number, or name and 

location of all known injection wells, producing wells, abandoned wells, plugged 

wells or dry holes, deep stratigraphic boreholes, State or EPA approved 

subsurface cleanup sites, surface bodies of water, springs, mines (surface and 

subsurface), quarries, water wells and other pertinent surface features 

including structures intended for human occupancy and roads. Only information of 

public record is required to be included on this map; 

Rationale: Insert "known" before "injection" 

Suggests removing highlighted text as faults are not shown on maps unless there 

is a surface expression of the fault. Also, faults are detailed in (d) below 

and this language appears redundant. 

Response: Regarding the comment that EPA delete mention of faults on surface maps, EPA believes 

that if faults have surface expressions, they should be presented on maps submitted; this information 

would complement the required cross section data. EPA is developing guidance on site characterization 

for GS projects to assist owners or operators and Directors in evaluating permit requirements and 

applications under §146.82. The guidance provides recommendations regarding characterizing the 

regional geology and hydrogeology of a proposed GS site as well as performing the necessary 

geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The 

guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. Please see the final rule and the 

discussion of geologic site characterization in the preamble for additional information. 

EPA acknowledges but did not make the suggested edits. EPA believes that all of the site 

characterization requirements at §146.82, including geomechanical information and geologic and 

topographic maps and cross sections, are essential to proper siting of a GS well and are the foundation 

for a detailed understanding of the local and regional geology, and that the owner or operator should 

collect this information, regardless of whether it is known in advance of the siting process. Collecting 

and evaluating this data supports important evaluations regarding the suitability of the site to receive and 

contain injected CO2. 

EPA acknowledges that some smaller fractures may not be detectable during the site characterization 

process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or 

suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells and sites 

can mitigate the potential impacts of unidentified fractures. These include limitations on injection 

pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and 

548
assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible 

CO2 movement through high-permeability regions (i.e., faults and/or fractures) not detected in the initial 

site characterization. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: EPA Proposal: (c) The area of review based on modeling, using data obtained 

during logging and testing of the well and the formation as required by 

paragraphs (l), (r), and (s) of this section; 

GWPC Recommendations: (c) A map delineating the area of review based upon 

modeling, using all available data including data available from any logging and 

testing of wells within the area of review. 

Rationale: Is this supposed to be a map, a tabular display, a cross section or 

series of cross sections etc... This appears to be related to a condition where 

a well is already drilled. This does not align with requesting information to 

receive a permit. 

Response: EPA recognizes that information necessary for an area of review may not be available until 

after a well has been drilled and formation testing can occur. EPA revised §146.82 so that the final 

regulation specifies separate requirements for information to be submitted with the permit application 

and before well construction is approved (at §146.82(a)) and information to be submitted before 

operation of the well is authorized (at §146.82(c)) including The final area of review based on modeling, 

using data obtained during logging and testing of the well and the formation §146.82(c)(1). 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Response 

to Comments EPA has made many revisions to the GS Rule. See the final rule and the site 

characterization discussion in the preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: EPA Proposal: (d) Information on the geologic structure and hydrogeologic 

properties of the proposed storage site and overlying formations, including: 

(1) Maps and cross sections of the area of review; 

(2) Location, orientation, and properties of known or suspected faults and 

fractures that may transect the confining zone(s) in the area of review and a 

determination that they would not interfere with containment; 

GWPC Recommendations: (d) Sufficient information on the geologic structure and 

reservoir properties of the proposed storage site and overlying formations, 

including: 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24870

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24871

549
(1) Isopach maps of the proposed injection and confining zone(s), a structural 

contour map aligned with the top of the proposed injection zone, and at least 

two geologic cross sections of the area of review reasonably perpendicular to 

each other showing the geologic formations from the surface to total depth. 

(2) Location, orientation, and properties of known or suspected subsurface 

faults that may transect the confining zone(s) in the area of review and a 

determination that they would not interfere with containment; 

Rationale: Fractures can be incredibly small and it is virtually impossible to 

find all subsurface fractures. The GWPC also recommends addition of the term 

"Sufficient" before the information sought in (d) as this is more precise. 

Response: EPA acknowledges that some smaller fractures may not be detectable during the site 

characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit 

data on known or suspected faults and fractures (i.e., not all fractures). Other requirements for GS 

injection wells and sites can mitigate the potential impacts of unidentified fractures. These include 

limitations on injection pressures to avoid propagation of existing fractures in the confining zone 

(§146.88(a)), collection and assessments of CO2 monitoring data at the site, and AoR reevaluations 

(§146.84(e)) to assess possible CO2 movement through high-permeability regions (i.e., faults and/or 

fractures) not detected in the initial site characterization. 

EPA disagrees with the other suggested edits because the GS rule, as written, affords flexibility to 

owners or operators and Directors to tailor the site characterization process to the unique features of the 

site. Please see the final rule and the discussion of geologic site characterization in the preamble for 

additional information. 

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit 

more (or different) geologic data than proposed; 4710 2.7.1 Proposed submissions required for permit 

applications (seeking comment) 

Comment: EPA Proposal: (3) Information on seismic history including the presence and 

depth of seismic sources and a determination that the seismicity would not 

interfere with containment; 

(4) Data on the depth, areal extent, thickness, mineralogy, porosity, 

permeability and capillary pressure of the injection and confining zone(s); 

including geology/facies changes based on field data which may include geologic 

cores, outcrop data, seismic surveys, well logs, and names and lithologic 

descriptions; 

(5) Geomechanical information on fractures, stress, ductility, rock strength, 

and in situ fluid pressures within the confining zone; and 

GWPC Recommendations: (3) Information on seismic history that have affected the 

proposed area of review including knowledge of previous seismic events and 

history of these events, including the presence and depth of seismic sources and 

a determination that the seismicity would not compromise containment; 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24872

550
(4) Data sufficient to demonstrate the effectiveness of the injection and 

confining zone(s), including data on the depth, areal extent, thickness, 

mineralogy, porosity, vertical permeability reservoir pressure and of the 

injection and confining zone(s) within the area of review; including geologic 

changes based on field data which may include geologic cores, outcrop data, 

seismic surveys, well logs, capillary pressure tests and names and lithologic 

descriptions; 

(5) Geomechanical information on the confining zone(s) within the area of 

review; and 

Rationale: Capillary pressure is too hard to measure outside the lab; how 

comparable are lab results to what goes into the ground. Sidewall core may not 

be sufficient to do this, and it is difficult to core the whole of the confining 

and injection zones. Rewording keeps the usefulness of capillary pressure in the 

provision without making it a mandatory use. 

Response: EPA acknowledges that laboratory methods are standard for determining capillary pressures 

regardless of formation permeability and that in situ measurements would require drilling of a well. 

However, EPA also anticipates that test wells will be drilled to support geologic site characterization of 

the proposed GS sites and can be used to collect subsurface samples (for laboratory determination of 

capillary pressure) and take other necessary measurements. EPA believes that information on capillary 

entry pressure is necessary and appropriate. Capillary entry pressure measurements on core samples can 

quantify the amount of buoyant force the confining zone can maintain before failure (World Resources 

Institute, 2008). 

EPA recognizes that this information may not be available until after a well has been drilled. EPA 

revised §146.82 so that the final regulation specifies separate requirements for information to be 

submitted with the permit application and before well construction is approved (at §146.82(a)) and 

information to be submitted before operation of the well is authorized (at §146.82(c)). Final information 

on injection zone pressures would be required following drilling of the well, at §146.82(c)(4). 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: EPA Proposal: (6) Geologic and topographic maps and cross sections illustrating 

regional geology, hydrogeology, and the geologic structure of the local area. 

GWPC Recommendations: Support the EPA language. 

Response: EPA acknowledges the comment and the final rule retains the text as proposed. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(e) 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24873

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24874

551
EPA Proposal: (e) A tabulation of all wells within the area of review which 

penetrate the injection or confining zone(s). Such data must include a 

description of each well’s type, construction, date drilled, location, depth, 

record of plugging and/ or completion, and any additional information the 

Director may require; 

GWPC Recommendations: (e) A compilation of all artificial penetrations within 

the area of review which penetrate the injection or confining zone(s). Such data 

must include a description of each well’s type, construction, date drilled, 

location, depth, record of plugging and/ or completion, and any additional 

information the Director may require; 

Rationale: The GWPC felt that the term compilation was more appropriate than 

tabulation because tabulation as tabulation implies a spreadsheet while 

compilation can take numerous forms. 

Response: EPA used the term tabulation in the final rule because it is the same term used in the same 

requirement for other well classes; and, the regulated community and permitting officials are familiar 

with existing terminology. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Response 

to Comments EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: EPA Proposal: (f) Maps and stratigraphic cross sections indicating the general 

vertical and lateral limits of all USDWs, water wells and springs within the 

area of review, their positions relative to the injection zone(s) and the 

direction of water movement, where known; 

GWPC Recommendations: (f) Maps and stratigraphic cross sections indicating the 

general vertical and lateral limits of all USDWs, the location of water wells 

and perennial springs within the area of review, their positions relative to the 

injection zone(s) and the direction of water movement, where known; 

Rationale: Clarification: Use of the term perennial before springs will prevent 

a requirement to list very minor, intermittent springs which are not 

hydrologically significant. 

Response: EPA acknowledges the comment; however, the final rule does not reflect the suggested edit. 

The Agency uses the term “springs” in the site characterization requirements for other classes of wells 

(see §146.70 (a)(2)) and the term is familiar to the regulated community and permitting officials. EPA 

adds that characterization will be site-specific, and owners or operators are encouraged to discuss the 

site with the Director as data are collected to identify thresholds for certain types of data. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Response 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24875

552
to Comments EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: EPA Proposal: (g) Baseline geochemical data on subsurface formations, including 

all USDWs in the area of review; 

GWPC Recommendations: (g) Compilation of available baseline geochemical data on 

the proposed injection zone and nearest adjacent porous and permeable formation 

to the confining zone, existing utilized water supply aquifers and any other 

USDWs designated by the Director. 

Rationale: It will be unduly burdensome to address "all USDWs" in some contexts. 

This revision allows for more appropriate focusing on those USDWs designated by 

the Director. 

Response: EPA believes that identifying and mapping all surrounding USDWs near an injection well, as 

specified at §146.82(a)(5), is necessary to ensure protection of all USDWs from endangerment. The 

purpose of the UIC requirements (including those for Class VI wells) is to ensure the protection of 

USDWs from endangerment, which are defined based on total dissolved solids (TDS) content, not their 

location or depth (40 CFR §144.3). 

EPA adds that knowing the number, location and depth of USDWs near an injection well will generate 

baseline regional information, support development of an effective testing and monitoring plan, and 

enhance owner or operator and Director understanding of the site. This requirement is common to all 

injection well classes. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Response 

to Comments EPA has made many revisions to the GS Rule. See the final rule and preamble for further 

discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: EPA Proposal: (h) Proposed operating data: 

(1) Average and maximum daily rate and volume of the carbon dioxide stream; 

(2) Average and maximum injection pressure; 

(3) The source of the carbon dioxide stream; and 

(4) An analysis of the chemical and physical characteristics of the carbon 

dioxide stream; 

GWPC Recommendations: (h) Proposed operating data: 

(1) Average and maximum daily injection rate and volume of the carbon dioxide 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24876

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24877

553
stream; 

(2) Average and maximum surface injection pressure; 

(3) The source of the carbon dioxide stream; and 

(4) An analysis of the chemical and physical characteristics of the carbon 

dioxide stream; 

Rationale: Clarification: Addition of the term surface in (h)(d) will make it 

clear as to where the injection pressure is to measured. 

Rule Provision: 146.82(i) 

EPA Proposal: (i) The compatibility of the carbon dioxide stream with fluids in 

the injection zone and minerals in both the injection and the confining zone(s), 

based on the results of the formation testing program, and with the materials 

used to construct the well; 

(j) Proposed formation testing program to obtain an analysis of the chemical and 

physical characteristics of the injection zone and confining zone; 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

EPA Proposal: (k) Proposed stimulation program and a determination that 

stimulation will not interfere with containment; 

(l) The results of the formation testing program as required in paragraph (j) of 

this section; 

(m) Proposed procedure to outline steps necessary to conduct injection operation; 

(n) Schematic or other appropriate drawings of the surface and subsurface 

construction details of the well; 

(o) Injection well construction procedures that meet the requirements of § 

146.86; 

GWPC Recommendations: (k) Proposed stimulation program and a determination that 

stimulation will not compromise containment; 

(l) The results of the formation testing program as required in paragraph (j) of 

this section; 

(m) Proposed procedure to outline steps necessary to conduct injection 

operation; 

(n) A wellbore schematic of the subsurface construction details and surface 

wellhead construction. 

(o) Injection well construction procedures that meet the requirements of § 

146.86; 

554
Rationale: "Interfere" is too ambiguous and should be replaced by "compromise" 

which limits concerns to situations where containment may be lost. 

EPA Proposal: (p) Proposed area of review and corrective action plan that meets 

the requirements under § 146.84; 

(q) The status of corrective action on wells in the area of review; 

(r) All available logging and testing program data on the well required by § 

146.87; 

(s) A demonstration of mechanical integrity pursuant to § 146.89; 

(t) A demonstration, satisfactory to the Director, that the applicant has met 

the financial responsibility requirements under § 146.85; 

GWPC Recommendations: (p) Proposed corrective action plan for artificial 

penetrations within the area of review, if necessary 

(q) All available logging and testing program data on the well required by § 

146.87; 

(r) The proposed demonstration method for mechanical integrity pursuant to 

(s) A demonstration, satisfactory to the Director, that the applicant has met 

the financial responsibility requirements under § 146.85; 

Rationale: (q) Should be deleted because it is not part of an application 

process but, rather a post permitting activity. This would result in a renumbering of the subsections after the new (q). 

Rule Provision: 146.82(u) 

EPA Proposal: (u) Proposed testing and monitoring plan required by § 146.90; 

(v) Proposed injection well plugging plan required by § 146.92(b); 

(w) Proposed post-injection site care and site closure plan required by § 

146.93(a); 

(x) Proposed emergency and remedial response plan required by § 146.94; and 

(y) Any other information requested by the Director. 

GWPC Recommendations: (t) Proposed testing and monitoring plan required by § 

146.90; 

(u) Proposed injection and monitoring well(s) plugging plan required by § 

146.92(b); 

555
(v) Proposed post-injection site care and site closure plan required by § 

146.93(a); 

(w) Proposed emergency and remedial response plan required by § 146.94; and 

(x) Any other information requested by the Director. 

Rationale: Need to address the plugging of monitoring well(s), if any, included 

in the project. 

Response: EPA acknowledges the commenter’s support for portions of the subject requirements. EPA 

disagrees that the technical clarifications suggested are necessary. EPA adds that it is developing 

guidance for owners or operators on the geologic site characterization and AoR and corrective action 

processes. These guidances will provide recommendations and clarify the intent of all required elements 

of a permit application. The guidances can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: Rule Provision: 146.83 

EPA Proposal: Minimum criteria for siting 

(a) Owners or operators of Class VI wells must demonstrate to the satisfaction 

of the Director that the wells will be sited in areas with a suitable geologic 

system. The geologic system must be comprised of: 

(1) An injection zone of sufficient areal extent, thickness, porosity, and 

permeability to receive the total anticipated volume of the carbon dioxide 

stream; 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment and the final rule retains the text at §146.83(a) as proposed. 

Other EPA Comment Codes and Descriptions: 3110 2.1.1 Proposed siting requirements (i.e., 

injection/confining zones, trapping mechanism) 

Comment: EPA Proposal: (2) A confining zone(s) that is free of transmissive faults or 

fractures and of sufficient areal extent and integrity to contain the injected 

carbon dioxide stream and displaced formation fluids and allow injection at 

proposed maximum pressures and volumes without initiating or propagating 

fractures in the confining zone(s); and 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24878

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24879

556
GWPC Recommendations: (2) A confining zone(s) that is laterally continuous and 

free of known transecting, transmissive faults or fractures over an area 

sufficient to prevent the movement of fluids into a USDW; 

Rationale: Suggest using the Class I regulation for this paragraph (2) in 

146.62(c) with the addition of reactivation of existing faults or fractures and 

before the terms faults or fractures the word known should be added. 

Response: The Agency believes that the requirement at §146.83(a)(2) that the confining zone to be free 

of transmissive faults or fractures is appropriate for Class VI wells and is necessary to ensure 

containment of the injectate and that requiring the confining zone to be free of transmissive faults 

maximizes protection of USDWs from endangerment. EPA believes that the text regarding propagation 

of faults and fractures is important to avoid the potential for fluid movement and to ensure that injection 

is at appropriate pressures. Class I hazardous waste injection well operators must also meet a similar 

requirement that the site is free of transmissive faults or fractures; they have successfully made such 

demonstrations in the past. While core samples obtained through drilling and hydraulic testing are direct 

methods to obtain such information, geophysical techniques such as seismic or electromagnetic surveys 

can also be used in many geologic settings to demonstrate the absence of or identify and characterize the 

presence of faults or fractures. EPA adds that the Director will evaluate all geologic data on the site to 

ensure protection of USDWs from endangerment before approving a site for a GS project. 

Other EPA Comment Codes and Descriptions: 3120 2.1.2 Need to identify additional confining and 

containment zones (seeking comment) 

Comment: EPA Proposal: (b) At the Director’s discretion, owners or operators of Class VI 

wells must identify and characterize additional zones that will impede vertical 

fluid movement, are free of faults and fractures that may interfere with 

containment, allow for pressure dissipation, and provide additional 

opportunities for monitoring, mitigation and remediation. 

GWPC Recommendations: Delete paragraph 

Rationale: This paragraph creates a presumption that additional zones WILL be 

required. It is also redundant from previous sections. 

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, 

secondary confining zones are required when the Director determines that these zones are needed to 

maximize the protection of USDWs from endangerment. EPA retains the requirement to identify 

additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA 

believes that, in some situations, the presence of additional confining and containment zones above the 

primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further 

impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for 

monitoring, mitigation, and remediation. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24880

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24881

557
Comment: Rule Provision: 146.84 

EPA Proposal: 146.84. Area of review and corrective action 

(a) The area of review is the region surrounding the geologic sequestration 

project that may be impacted by the injection activity. The area of review is 

based on computational modeling that accounts for the physical and chemical 

properties of all phases of the injected carbon dioxide stream. 

GWPC Recommendations: (a) The area of review is based on computational modeling 

that accounts for the physical and chemical properties of all phases of the 

injected carbon dioxide stream. 

Rationale: This is the same as the definition of "Area of review" that was 

revised by the GWPC .to delete the first sentence. 

Comments on many provisions are predicated on proposed changes in definitions 

Response: The Agency has carefully considered all comments on the AoR definition at 146.84(a) and 

modified it to read as follows: The region surrounding the geologic sequestration project where USDWs 

may be endangered by the injection activity. The area of review is delineated using computational 

modeling that accounts for the physical and chemical properties of all phases of the injected CO2 stream 

and is based on available site characterization, monitoring, and operational data. 

Other EPA Comment Codes and Descriptions: 3700 2.2.5 Comments on the requirement for an AoR 

and corrective action plan 

Comment: EPA Proposal: (b) The owner or operator of a Class VI well must prepare, 

maintain, and comply with a plan to delineate the area of review for a proposed 

geologic sequestration project, periodically reevaluate the delineation, and 

perform corrective action that meets the requirements of this section and is 

acceptable to the Director. As a part of the permit application for approval by 

the Director, the owner or operator must submit an area of review and corrective 

action plan that includes the following information: 

(1) The method for delineating the area of review that meets the requirements of 

paragraph (c) of this section, including the model to be used, assumptions that 

will be made, and the site characterization data on which the model will be 

based; 

GWPC Recommendations: (b) The owner or operator of a Class VI well must prepare, 

maintain, and comply with a plan to delineate the area of review for a proposed 

geologic sequestration project, reevaluate the delineation, and perform 

corrective action that meets the requirements of this section in a manner and at 

a frequency acceptable to the Director. As a part of the permit application, the 

owner or operator must submit an area of review and corrective action plan that 

includes the following information: 

Rationale: Suggest deletion of "periodically." See Workgroup recommendation 7.6 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24882

558
from 

Recommendations for the Regulatory Management of Geologic Sequestration of CO2 

Under the UIC Program 

Replace with "in a manner and at a frequency" 

Delete "for approval by the Director,". Director’s approval is implicit in a 

permit application. 

Response: EPA disagrees with the suggested change, and is retaining the approach of setting a 

minimum fixed frequency for reevaluating the AoR but has, based on commenters' input, changed the 

frequency from 10 years to at least every 5 years, as specified in §146.84(e). EPA agrees with 

commenters that site-specific information is an important factor in determining an appropriate AoR 

reevaluation frequency, and adds that the owner or operator's AoR and corrective action plan must 

describe the minimum fixed frequency for reevaluating the AoR and the site-specific conditions on 

which this frequency is based. EPA adds that the Director will evaluate the proposed plan in connection 

with a review of a vast amount of geologic and proposed operating data in determining whether to 

approve the plan. EPA is developing guidance describing approaches to preparing all of the required GS 

project plans, which will address considerations for determining an appropriate AoR reevaluation 

schedule. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3500 2.2.3 Area of Review Reevaluation (seeking 

comment); 3700 2.2.5 Comments on the requirement for an AoR and corrective action plan 

Comment: Rule Provision: 146.84(b)(2) 

EPA Proposal: (2) A description of: 

(i) The minimum fixed frequency, not to exceed 10 years, the owner or operator 

proposes to reevaluate the area of review; 

(ii) The monitoring and operational conditions that would warrant a reevaluation 

of the area of review prior to the next scheduled reevaluation as determined by 

the minimum fixed frequency established in paragraph (b)(2)(i) of this section. 

(iii) How monitoring and operational data (e.g., injection rate and pressure) 

will be used to inform an area of review reevaluation; and 

GWPC Recommendations: Delete (i) and (ii) 

Rationale: Suggest deletion of (i) as this is handled by "manner and at a 

frequency acceptable to the Director in (b) 

Suggest deletion of (ii) for same reason as comment on (i) 

Response: EPA believes that periodic AoR reevaluation at a set frequency of at least every 5 years is 

necessary to ensure protection of USDWs from endangerment and address the uncertainties inherent in 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24883

559
predictive modeling. Periodic AoR reevaluations at §146.84(e) ensure that a deliberate effort is made to 

verify, based on monitoring and operational data, that the CO2 plume is moving within the subsurface as 

predicted. EPA believes that less frequent reevaluations may not be sufficient to appropriately model 

plume and pressure front movement, establish conditions for corrective action, and ensure protection of 

USDWs from endangerment. 

EPA clarifies that if site monitoring data agrees with the existing AoR delineation, a model recalibration 

may not be necessary, and the AoR reevaluation may consist of a demonstration that the current AoR 

delineation is adequate based on site monitoring data. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: EPA Proposal: (iv) How corrective action will be conducted to meet the 

requirements of paragraph (d) of this section, including what corrective action 

will be performed prior to injection and what, if any, portions of the area of 

review will have corrective action addressed on a phased basis and how the 

phasing will be determined; how corrective action will be adjusted if there are 

changes in the area of review; and how site access will be guaranteed for future 

corrective action. 

GWPC Recommendations: (iv) How corrective action will be conducted to meet the 

requirements of paragraph (d) of this section, including what corrective action 

will be performed prior to injection and what, if any, portions of the area of 

review will have corrective action addressed on a phased basis and how the 

phasing will be determined; how corrective action will be adjusted if there are 

changes in the area of review; and how site access will be assured for future 

corrective action. 

Rationale: Replace "guaranteed" with "assured" Future access cannot be 

absolutely guaranteed for an area in advance that may not even be within the 

boundaries of the AOR/ project. However, assurance of access is a standard that 

is less onerous than guaranteed, it is firmer than another standard such as 

"arranged" 

Response: EPA is retaining this requirement as proposed. The purpose of the corrective action 

requirement at §146.84(d) is to ensure that all wells in the AoR that have the potential to cause the 

movement of CO2 or other fluids into or between USDWs receive appropriate corrective action. In 

general, to meet this requirement, the owner or operator will most likely need to obtain the right of 

access to wells that may require corrective action, and demonstrate they have done this in their proposed 

AoR and corrective action plan. In the AoR and corrective action plan, the owner or operator must 

describe how site access will be guaranteed for future corrective action, as specified in §146.84(b)(2)

(iv). 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rule Provision: 146.84(c) 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24884

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24885

560
(c) Owners or operators of Class VI wells must perform the following actions to 

delineate the area of review, identify all wells that require corrective action, 

and perform corrective action on those wells: 

(1) Predict, using computational modeling, the projected lateral and vertical 

migration of the carbon dioxide plume and formation fluids in the subsurface 

from the commencement of injection activities until the plume movement ceases, 

pressure differentials sufficient to cause the movement of injected fluids or 

formation fluids into a USDW are no longer present, or after a fixed time period 

as determined by the Director. The model must: 

GWPC Recommendations: (c) Owners or operators of Class VI wells must perform the 

following actions to delineate the area of review, identify all wells that 

require corrective action, and perform corrective action on those wells: 

(1) Predict, using computational modeling, the projected lateral and vertical 

migration of the carbon dioxide plume and formation fluids in the subsurface 

from the commencement of injection activities until the plume movement ceases, 

pressure differentials sufficient to cause the movement of injected fluids or 

formation fluids into a USDW are no longer present, or for a fixed time period 

as determined by the Director. The model must: 

Rationale: Should say "for" not "after." 

Response: Based on its evaluation of all public comments and input on the proposed rule, EPA has 

clarified this language in the final rule. It now reads, “Predict, using existing site characterization, 

monitoring and operational data, and computational modeling, the projected lateral and vertical 

migration of the carbon dioxide plume and formation fluids in the subsurface from the commencement 

of injection activities until the plume movement ceases, until pressure differentials sufficient to cause 

the movement of injected fluids or formation fluids into a USDW are no longer present, or until the end 

of a fixed time period as determined by the Director.” 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rule Provision: 146.84(c)(i) 

EPA Proposal: (i) Be based on detailed geologic data collected to characterize 

the injection zone, confining zone and any additional zones; and anticipated 

operating data, including injection pressures, rates and total volumes over the 

proposed life of the geological sequestration project; 

(ii) Take into account any geologic heterogeneities, data quality, and their 

possible impact on model predictions; and 

(iii) Consider potential migration through faults, fractures, and artificial 

penetrations. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24886

561
GWPC Recommendations: (i) Be based on detailed geologic data collected to 

characterize the injection zone, confining zone; and anticipated operating data, 

including injection pressures, rates and total volumes over the duration of 

injection; 

(ii) Take into account relevant geologic heterogeneities, and data quality, and 

their possible impact on model predictions; and 

(iii) Consider potential migration through faults, fractures, and artificial 

penetrations. 

Rationale: Suggest deletion of "any additional zones". You do not need to 

include any additional zones if you use the current CFR definition of confining 

zone since it includes multiple zones. 

Should be geologic not geological for consistency with other provisions because 

geologic sequestration project is defined. 

Suggest "duration of injection" instead of "life of the geological sequestration 

project" 

Suggest "relevant" instead of any in (ii) 

Insert "and" between "heterogeneities" and "data" 

Response: EPA agrees that detailed geologic data is invaluable to modeling an accurate AoR. The 

Agency believes that the AoR delineation requirements in 146.84 (c)(1)(i), which specify using "detailed 

geologic data collected to characterize the injection zone, confining zone and any additional zones; and 

anticipated operating data...," and (c)(iii) to "consider potential migration through faults, fractures and 

artificial penetrations," provide the necessary information needed for appropriate site modeling, 

subsequent site evaluation, and protection of USDWs from endangerment. EPA adds that the extensive 

requirements for data that is to be included in the permit application at 146.82 incorporate these same 

types of information. The Director will review the AoR models in the context of the extensive site data 

submitted with the permit application. EPA recognizes that in some instances, the Director may require 

additional types of data to be included in the AoR delineation (146.84(c)(1)). Based on its evaluation of 

all public comments and input on the proposed rule and NODA and Request for Comment EPA has 

made many revisions to the GS Rule. See the final rule and preamble for further discussion on EPA's 

final approach. 

EPA disagrees that only the injection and confining zones should be included in AoR modeling of GS 

sites. EPA believes that the modeling should also take into account the possibility of displaced fluids or 

brines caused by a lateral and/or vertical pressure plume, and therefore it may be necessary to include 

additional zones along with the confining/injection zones to ensure the integrity of the confining zone 

and ultimately protect a USDW from endangerment. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: EPA Proposal: (2) Using methods approved by the Director, identify all 

penetrations, including active and abandoned wells and underground mines, in the 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24887

562
area of review that may penetrate the confining zone. Provide a description of 

each well’s type, construction, date drilled, location, depth, record of 

plugging and/or completion, and any additional information the Director may 

require; and 

GWPC Recommendations: (2) Using methods approved by the Director, identify all 

known artificial penetrations into the confining zone, including active and 

abandoned wells and underground mines, in the area of review that may penetrate 

the confining zone. Provide a description of each well’s type, construction, 

date drilled, location, depth, record of plugging and/or completion, and any 

additional information the Director may require; and 

Rationale: Insert "known artificial penetrations into the confining zone" 

EPA Proposal: (3) Determine which abandoned wells in the area of review have 

been plugged (as required by § 146.92) in a manner that prevents the movement of 

carbon dioxide or associated fluids that may endanger USDWs 

GWPC Recommendations: (3) Determine which abandoned wells identified in 146.84 

(c) (2) have been plugged (as required by §146.92) in a manner that prevents the 

movement of carbon dioxide or displaced formation fluids that may endanger 

USDWs. 

Rationale: Add identified in 146.84 (c) (2) 

Remove "area of review" as redundant. 

Suggest change "associated fluids" to "displaced formation fluids." Associated 

fluids is not defined so if EPA means displaced formation fluids the regulation 

should just use this term. Otherwise, you need to define associated fluids. 

Response: EPA is retaining the requirement in 146.84(c)(2) as proposed. EPA agrees with commenters 

that, for most GS sites, relying on database and other public records searches (i.e., of "known" artificial 

penetrations) will be sufficient to meet the requirements at §146.84(c)(2). However, the Agency 

recognizes that there may be situations where additional surveys or research to locate wells may be 

appropriate. For example, there may be cases where the Director may determine that ground or airborne 

surveys for wells are appropriate, e.g., if there is reason to believe, based on knowledge of the site or of 

available data, that the incompleteness of information on known wells could compromise USDW 

protection from endangerment. In order to preserve the Director's discretion to require an operator to 

supplement a records search, EPA did not make the suggested change. 

EPA clarifies that the term "associated fluids" as proposed in §146.84(c)(3) refers to formation fluids, 

other injectates, etc that may be present in the subsurface and affect movement of the CO2 plume and/or 

pressure front. EPA believes this terminology would incorporate any fluids in the subsurface that could 

potentially move through artificial penetrations and affect USDWs. EPA has revised the language at 

§146.84(c)(3) to read, "... carbon dioxide or other fluids that may endanger USDWs..." 

Other EPA Comment Codes and Descriptions: 3460 2.2.2.3 Acceptable corrective action techniques 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24888

563
for GS sites (e.g., cements) 

Comment: Rule Provision: 146.84(d) 

EPA Proposal: (d) Owners or operators of Class VI wells must perform corrective 

action on all wells in the area of review that are determined to need corrective 

action using methods necessary to prevent the movement of fluid into or between 

USDWs including use of corrosion resistant materials, where appropriate. 

GWPC Recommendations: (d) Owners or operators of Class VI wells must perform 

corrective action using materials suitable for use with carbon dioxide streams, 

on all wells identified in 146.84(c)(2) that are determined to need corrective 

action". 

Rationale: Re-write as follows "Owners or operators of Class VI wells must 

perform corrective action using corrosion resistant materials, when appropriate, 

on all wells identified in 146.84(c)(2) that are determined to need corrective 

action". 

Response: EPA revised the text at §146.84(d) to require the use of materials that are "compatible with 

the carbon dioxide stream." EPA believes this language change addresses commenters' concerns and is 

also consistent with other language regarding materials requirements in the GS rule. 

Other EPA Comment Codes and Descriptions: 3400 2.2.2 Corrective Action 

Comment: EPA Proposal: (e) If monitoring data indicate an endangerment to USDWs, the 

owner or operator must notify the Director and cease operations as required by § 

146.94. 

GWPC Recommendations: Delete 

Rationale: Why is this needed if 146.94 already specifies the notification and 

cessation of injection? 

Response: Based on consideration of all public comments and other information, EPA deleted this 

provision from §146.84. The final rule now contains a provision in §146.91(c) that requires the owner or 

operator to report within 24 hours any evidence that the carbon dioxide stream or associated pressure 

front may cause an endangerment to a USDW. EPA believes this change consolidates reporting 

requirements in one place and provides additional clarity. 

Other EPA Comment Codes and Descriptions: 3530 2.2.3.1 AoR reevaluation frequency (seeking 

comment) 

Comment: EPA Proposal: (f) At the minimum fixed frequency, not to exceed 10 years, as 

specified in the area of review and corrective action plan, or when monitoring 

and operational conditions warrant, owners or operators must: 

(1) Reevaluate the area of review in the same manner specified in paragraph (c) 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24889

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24890

564
(1) of this section; 

(2) Identify all wells in the reevaluated area of review that require corrective 

action in the same manner specified in paragraph (c)(2) of this section; 

GWPC Recommendations: (f) As specified in the approved area of review and 

corrective action plan, or when monitoring and operational conditions warrant, 

owners or operators must 

(1) Reevaluate the area of review in the same manner specified in paragraph (c) 

(1) of this section; 

(2) Identify all wells in the reevaluated area of review that require corrective 

action in the same manner specified in paragraph (c)(2) of this section; 

Rationale: Delete "At the minimum fixed frequency, not to exceed 10 years". 

Insert "approved" before "area of review" in (f). 

Response: EPA disagrees with the suggested edit, and believes that periodic AoR reevaluation at a set 

frequency is necessary to ensure protection of USDWs from endangerment and address the uncertainties 

inherent in predictive modeling. Periodic AoR reevaluations at §146.84(e) ensure that a deliberate effort 

is made to verify, based on monitoring and operational data, that the CO2 plume is moving within the 

subsurface as predicted. EPA believes that less frequent reevaluations may not be sufficient to 

appropriately model plume and pressure front movement, establish conditions for corrective action, and 

ensure protection of USDWs from endangerment. 

EPA clarifies that if site monitoring data agrees with the existing AoR delineation, a model recalibration 

may not be necessary, and the AoR reevaluation may consist of a demonstration that the current AoR 

delineation is adequate based on site monitoring data. 

Other EPA Comment Codes and Descriptions: 3700 2.2.5 Comments on the requirement for an AoR 

and corrective action plan 

Comment: EPA Proposal:(3) Perform corrective action on wells requiring corrective action 

in the reevaluated area of review in the same manner specified in paragraph (c) 

(3) of this section; and 

(4) Submit an amended area of review and corrective action plan or demonstrate 

to the Director through monitoring data and modeling results that no amendment 

to the area of review and corrective action plan is needed. 

GWPC Recommendations: (3) Perform corrective action on wells requiring 

corrective action in the reevaluated area of review in the same manner specified 

in paragraph (c)(3) of this section; and 

(4) Submit an amended area of review and corrective action plan or demonstrate 

to the Director through monitoring data and modeling results that no change to 

the area of review and corrective action plan is needed. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24891

565
Rationale: Suggest "change" instead of "amendment" in (4) because the term 

amendment is typically construed to mean an official permit modification 

process. 

Response: EPA disagrees with the suggested change regarding the term “amendment.” EPA believes 

that, in some cases an amendment to the AoR and corrective action plan may warrant a permit 

modification. EPA added text to §144.39(a)(5) that permit modifications, requiring public notice and 

comment, are required if the Director determines that a modification is necessary based on an AoR 

reevaluation, amendments to any of the project plans, or a review of the testing and monitoring results. 

EPA made this change because the Agency recognizes that the AoR reevaluation process and any 

subsequent modifications to the plans may generate significant levels of public interest. 

EPA clarifies that if site monitoring data agrees with the existing AoR delineation, a model recalibration 

may not be necessary, and the AoR reevaluation may consist of a demonstration that the current AoR 

delineation is adequate based on site monitoring data. 

Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2 

movement 

Comment: Rule Provision: 146.84(g) 

(g) The emergency and remedial response plan (as required by § 146.94) and a 

demonstration of financial responsibility (as described by § 146.85) must 

account for the entire area of review, regardless of whether or not corrective 

action in the area of review is phased. 

GWPC Recommendations: (g) The emergency and remedial response plan (as required 

by § 146.94) and a demonstration of financial responsibility (as described by § 

146.85) must account for the entire area of review [as modified], regardless of 

whether or not corrective action in the area of review is phased. 

Rationale: Need to add phrase to account for the periodic reevaluations and 

possible revisions that will be occurring. Addition of the term [as modified] 

addresses this concern. 

Response: EPA agrees with the commenter and has modified the final rule at §146.84(f) to require the 

owner or operator to periodically review the emergency and remedial response plan to take into account 

the most recent AoR. Owners or operators must also periodically update the demonstration of financial 

responsibility to account for any such changes. 

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

responsibility requirements (40 CFR 146.85) 

Comment: Rule Provision: 146.85 

EPA Proposal: 146.85 Financial responsibility

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24892

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24893

566
(a) The owner or operator must demonstrate and maintain financial responsibility 

and resources for corrective action (that meets the requirements of § 146.84), 

injection well plugging (that meets the requirements of § 146.92), postinjection site care and site closure (that meets the requirements of § 146.93), 

and emergency and remedial response (that meets the requirements of§ 146.94) in 

a manner prescribed by the Director until: 

(1) The Director receives and approves the completed post-injection site care 

and site closure plan; and 

(2) The Director determines that the site has reached the end of the postinjection site care period. 

GWPC Recommendations: No specific language recommended. See rationale 

Rationale: Maintenance of plugging liability until site closure release by the 

Director is probably not needed once the well has been plugged. Should the 

owner/ operator be allowed to make a demonstration to the Director for the 

partial release of other financial responsibility elements? 

Response: EPA will allow owners or operators to use separate or multiple financial responsibility 

instruments for different GS activities. However, owners or operators must demonstrate adequate 

financial responsibility for all required activities, including well plugging, with their permit application, 

per §146.82(a)(14). In addition, on an annual basis, the owner or operator must adjust the cost estimate 

for inflation, increase or decrease the value of the financial instrument to match the cost estimate, and 

provide any updated information related to their financial responsibility instrument(s), or at any other 

time deemed appropriate by the Director. These annual reviews provide a mechanism for revising cost 

estimates up or down to account for changes in the project, including the execution of environmental 

obligations as phases of a GS project are completed. See the final rule and preamble for further 

discussion of EPA's final approach to financial responsibility. 

Regarding the suggested edit at §146.85(a)(1), EPA clarifies that the owner or operator may be released 

from a financial instrument when the phase of the project for which the instrument was required is 

complete and financial obligations for the required activity have been met, as specified in §146.85(b)(2). 

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

responsibility requirements (40 CFR 146.85) 

Comment: EPA Proposal: (b) The owner or operator must provide to the Director, at a 

frequency determined by the Director, written updates of adjustments to the cost 

estimate to account for any amendments to the area of review and corrective 

action plan (§ 146.84), the injection well plugging plan (§ 146.92), and the 

post-injection site care and site closure plan (§ 146.93). 

GWPC Recommendations: (b) The owner or operator must provide to the Director, at 

a frequency determined by the Director, but no more frequently than annually, 

written updates or adjustments to the cost estimate to account for any changes 

to: the area of review and corrective action plan (§146.84), the injection well 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24894

567
plugging plan (§146.92), and the post-injection site care and site closure plan 

(§146.93). 

Rationale: Does this contemplate both upward and downward adjustments? 

Suggest "change" instead of amendments. 

Clarification on what is meant by "updates or adjustments" would be beneficial 

e.g. what is included, at what frequency etc... 

Response: Owners or operators will be required to adjust costs when they are no longer adequate, as 

specified in the GS rule, at §146.85. These baseline estimates can then be updated annually and kept 

current through input from ongoing dialogue between the owner or operator and the Director. The cost 

estimation methodology guidance will also contain instructions on how to adjust cost estimates for 

inflation to help account for the long-term nature of GS and will address the need to adjust cost 

estimates for inflation. 

EPA is developing guidance on financial responsibility for GS wells. The guidance will include a 

discussion on how to estimate costs to assist GS well owners or operators, third party insurers or 

providers of financial instruments, and permitting authorities in developing estimates of the costs 

associated with various GS activities. The guidance is available on EPA's website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA did not make the proposed edits, but did extensively revise and clarify the financial responsibility 

requirements. See the final GS rule and preamble for additional information on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

responsibility requirements (40 CFR 146.85) 

Comment: Rule Provision: 146.85(c) 

EPA Proposal: (c) The owner or operator must notify the Director of adverse 

financial conditions such as bankruptcy that may affect the ability to carry out 

injection well plugging and post-injection site care and site closure. 

GWPC Recommendations: (c) The owner or operator must notify the Director of 

adverse financial conditions that may affect the ability to carry out injection 

well plugging and post-injection site care and site closure. 

Rationale: Delete "such as bankruptcy" from (c). Such examples of potential 

circumstances are unnecessary. 

Response: EPA did not make the proposed edits, but did extensively revise and clarify the financial 

responsibility requirements. EPA believes that the Director must be notified of bankruptcy specifically, 

among other adverse financial conditions, because it affects the use of financial instrument. See the final 

GS rule and preamble for additional information on EPA's final approach. Please see the final rule and 

the discussion of financial responsibility in the preamble for additional information. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24895

568
Other EPA Comment Codes and Descriptions: 5432 2.9.1.1 Need to adjust financial responsibility 

mechanisms (seeking comment) 

Comment: EPA Proposal: (d) The operator must provide an adjustment of the cost estimate 

to the Director if the Director has reason to believe that the original 

demonstration is no longer adequate to cover the cost of injection well plugging 

(as required by § 146.92) and post-injection site care and site closure (as 

required by § 146.93). 

GWPC Recommendations: (d) The operator must provide an adjustment of the cost 

estimate to the Director if the Director has reason to believe that the most 

recent demonstration is no longer adequate to cover the cost of injection well 

plugging (as required by § 146.92) and post-injection site care and site closure 

(as required by § 146.93). 

Rationale: The reference should be to the last demonstration not the original 

demonstration 

This is a one time extraordinary event. Regular updates are covered by 

146.85(b). 

Recognize that these will be updated periodically. 

Response: EPA agrees that it is important to periodically update cost estimates that support financial 

responsibility determinations. EPA clarifies that the GS rule, at §146.85(e) requires the owner or 

operator to provide annual updates to the cost estimate to account for any amendments to the AoR and 

corrective action plan, the injection well plugging plan, and the PISC and site closure plan. 

Other EPA Comment Codes and Descriptions: 3800 2.3 Proposed Injection Well Construction 

Requirements (40 CFR 146.86) 

Comment: Rule Provision: 146.86 

EPA Proposal: 6. Injection well construction requirements 

(a) General. The owner or operator must ensure that all Class VI wells are 

constructed and completed to: 

(1) Prevent the movement of fluids into or between USDWs or into any 

unauthorized zones; 

(2) Permit the use of appropriate testing devices and workover tools; and 

(3) Permit continuous monitoring of the annulus space between the injection 

tubing and long string casing. 

GWPC Recommendations: (a) General. The owner or operator must ensure that all 

Class VI wells are constructed and completed to: 

(1) Prevent the movement of fluid containing any contaminant into USDWs per 40 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24896

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24897

569
CFR Part 144.12(a). 

(2) Permit the use of appropriate testing devices and workover tools; and 

(3) Permit continuous monitoring of the annulus space between the injection 

tubing and long string casing. 

Rationale: Mirror language concerning endangerment standard in (1). 

The GWPC suggests re-wording (a)(1) to simplify and make it consistent with the 

CFR definitions of fluid movement. 

Response: EPA believes that protection of USDWs from endangerment and prevention of fluid 

movement between formations is paramount and believes that the language as proposed meets the nonendangerment standard provided in SDWA and §144.12. Appropriately designed and constructed wells 

are necessary to prevent endangerment to USDWs and maintain integrity of the well throughout the 

lifetime of a GS project. This is the foundation of the requirements for construction and pre-operational 

testing of Class VI wells at §§146.86 and 146.87. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment EPA has made many revisions to the GS rule. Please see the final rule and preamble for 

additional information. 

Other EPA Comment Codes and Descriptions: 3860 2.3.3 Well component degradation 

Comment: EPA Proposal: (b) Casing and Cementing of Class VI Wells. 

(1) Casing and cement or other materials used in the construction of each Class 

VI well must have sufficient structural strength and be designed for the life of 

the geologic sequestration project. All well materials must be compatible with 

fluids with which the materials may be expected to come into contact and meet or 

exceed standards developed for such materials by the American Petroleum 

Institute, ASTM International, or comparable standards acceptable to the 

Director. The casing and cementing program must be designed to prevent the 

movement of fluids into or between USDWs. In order to allow the Director to 

determine and specify casing and cementing requirements, the owner or operator 

must provide the following information: 

GWPC Recommendations: (1) Casing and cement or other materials used in the 

construction of each Class VI well must have sufficient structural strength and 

be designed for the life of the operating life of the well. All well materials 

must be compatible with fluids with which the materials may be expected to come 

into contact and meet or exceed test standards or practices developed for such 

materials by the American Petroleum Institute, ASTM International, or comparable 

standards acceptable to the Director. The casing and cementing program must be 

designed to prevent the movement of fluids into or between USDWs. In order to 

allow the Director to determine and specify casing and cementing requirements, 

the owner or operator must provide the following information: 

Rationale: Suggest substituting "operating life of the well" for "the life of 

the geologic sequestration project" in (1) The GWPC determined that geologic 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24898

570
sequestration project was a nebulous term that could not be calculated and thus 

would have no meaning in designing a casing or cementing program. 

IMirror the non endangerment standard. 

Response: EPA disagrees that the casing, cement or other materials should only be designed for the 

period of the injection process, rather than the life of the sequestration project. GS projects are 

anticipated to have long life spans in comparison to other types of deep injection wells. Not only must 

Class VI wells be able to function safely and properly over the lifespan of the GS project, but they must 

be constructed such that USDWs remain protected after well plugging. The requirements at §146.86 will 

ensure that the well can maintain integrity throughout the proposed life span of the project, including 

after the injection well is plugged and through post-injection site care period and beyond. While the risk 

profile of a GS site will decrease following cessation of injection, EPA believes that Class VI wells must 

be designed to protect USDWs from endangerment for the life of the project. Furthermore, rigorous 

casing and cementing help ensure that the Class VI well will not serve as a conduit for movement of 

fluids associated with future injection operations. 

Other EPA Comment Codes and Descriptions: 3860 2.3.3 Well component degradation 

Comment: Rule Provision: 146.86(b)(1) 

EPA Proposal: (i) Depth to the injection zone; 

(ii) Injection pressure, external pressure, internal pressure and axial loading; 

(iii) Hole size; 

(iv) Size and grade of all casing strings (wall thickness, external diameter, 

nominal weight, length, joint specification and construction material); 

(v) Corrosiveness of the carbon dioxide stream, and formation fluids; 

(vi) Down-hole temperatures; 

(vii) Lithology of injection and confining zones; 

GWPC Recommendations: (i) Depth to the injection zone; 

(iii) Hole size; 

(iv) Size and grade of all casing strings (wall thickness, external diameter, 

nominal weight, length, joint specification and construction material); 

(v) Predicted corrosiveness of the combined carbon dioxide stream and formation 

fluids; 

(vi) Down-hole temperatures and pressures; 

(vii) Lithology of injection and confining zones; 

Rationale: What is meant by external and internal pressure? Recommend deleting 

(ii). 

Insert "and pressures" in (vi) 

Cannot measure the corrosiveness of the CO2 stream because it is not corrosive. 

Only liquids will yield pH measurements. 

Response: EPA disagrees with the suggested edits. The internal and external pressure mentioned in 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24899

571
§146.86(b)(1)(ii) refers to pressure on the well casing. Internal pressures could be caused by cement or 

annular fluids; external pressures could be caused by cementing against the borehole or pressure head 

from formations. 

At §146.86(c)(3)(ii), EPA clarifies that, although corrosiveness does not have a unit of measure, 

corrosiveness can be technically measured and described. Procedures that can identify corrosion (or the 

absence of corrosion) in a Class VI well provide valuable operational information that the Director 

needs to determine appropriate standards for the tubing and packer. EPA believes that this subpart 

accounts for all characteristics of the CO2 that could affect the performance of the tubing and packer, 

including the chemical content, corrosiveness, temperature, and density. 

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: EPA Proposal: (viii) Type or grade of cement; and 

(ix) Quantity, chemical composition, and temperature of the carbon dioxide 

stream. 

GWPC Recommendations: (viii) Type or grade of cement and additives; and 

(ix) Quantity, chemical composition, and temperature of the carbon dioxide 

stream. 

Rationale: Insert "and additives" in (viii) 

Response: EPA agrees with the suggestion that §146.86(b)(1)(viii) be revised to also address cement 

additives. In the final GS rule, the subparagraph reads as follows: "Type or grade of cement and cement 

additives." 

Other EPA Comment Codes and Descriptions: 3822 2.3.1.1 Depth of surface casing (seeking 

comment) 

Comment: EPA Proposal: (2) Surface casing must extend through the base of the lowermost 

USDW and be cemented to the surface. 

GWPC Recommendations: (2) Surface casing must extend through the base of the 

lowermost USDW above the injection zone and be cemented to the surface. 

Rationale: Insert "above the injection zone" in (2) after "USDW." In some parts 

of the US the USDW is very deep and this standard may preclude geologic 

sequestration in these areas. EPA should consider allowing the Director to 

exercise discretion to approve alternative means of achieving continuous cement 

around the well in such areas. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24901

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24902

572
Response: EPA disagrees with the suggested edit or that the surface casing requirements in the GS rule 

preclude injection below deep USDWs. The final GS rule at §146.86(b)(2) requires that surface casing 

extend through the base of the lowermost USDW and be cemented to the surface through the use of a 

single or multiple strings of casing and cement. It does not, however, specify how cementing must be 

accomplished, and gives flexibility to the owner or operator to propose alternate methods- to provide a 

sufficient amount of cement to meet the standard that USDWs are protected from endangerment. EPA 

notes that there are many potential ways to meet the requirement, such as the use of staged cementing. 

EPA adds that protection of USDWs is the primary mission and mandate of the UIC program and the 

purpose of all requirements for injection wells. Any injection activity must be demonstrated to not 

endanger USDWs, regardless of their depth, and if such a demonstration cannot be made, then the 

activity will not be allowed under UIC requirements or the SDWA. 

EPA recognizes concerns regarding construction of Class VI wells where the lowermost USDW is very 

deep. To further address comments on deep injection wells, the final GS rule at §146.95 includes 

requirements for owners or operators that seek a waiver of the injection depth requirements. Owners or 

operators of wells operating under injection depth waivers must comply with additional construction 

requirements to ensure that wells used to inject above or between USDWs are protective. See the 

discussion of the waiver approach in the preamble to the final GS rule for additional information. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: EPA Proposal: (3) At least one long string casing, using a sufficient number of 

centralizers, must extend to the injection zone and must be cemented by 

circulating cement to the surface in one or more stages. 

GWPC Recommendations: (3) At least one long string casing, using a sufficient 

number of centralizers, which at a minimum, would create a cement bond through 

the confining zone, and which must extend to the injection zone and must be 

isolated by placing cement and/or other isolation technologies as necessary to 

provide adequate isolation of the injection zone and provide for protection of 

USDWs. 

Rationale: Cementing to surface is not necessary to protect USDWS, and may have 

negative consequences, as follows. Cement to surface would eliminate the 

ability to monitor pressures in this annulus and would limit flexibility of 

remedial options. As revised, the proposal would allow for application and 

development of alternative technologies. See API RP90 for description of riskbased approach for managing situations involving annular casing pressure. 

Industry experience with CO2 EOR under the class II program demonstrates the 

effectiveness of existing cementing procedures. 

Response: EPA does not believe that the cementing requirements at §146.86 would prevent monitoring, 

operation and remediation of Class VI wells. Cementing of deep wells has been performed successfully 

in the past by owners or operators of Class I hazardous and Class I municipal waste disposal wells. 

Some of these wells, which must meet the same cementing and casing requirements as Class VI wells, 

are up to 12,000 feet deep and have been successfully cemented in a manner that maintains integrity and 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24903

573
allows for all required well testing, operation, and remediation (EPA, 2001). See the discussion of Class 

VI well construction requirements in the preamble to the final GS rule for additional information. 

Additionally, EPA is developing guidance on the construction of Class VI wells. This guidance will be 

available on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: Rule Provision: 146.86(b) 

EPA Proposal: (4) Circulation of cement may be accomplished by staging. The 

Director may approve an alternative method of cementing in cases where the 

cement cannot be recirculated to the surface, provided the owner or operator can 

demonstrate by using logs that the cement does not allow fluid movement behind 

the well bore. 

GWPC Recommendations: Delete 

Rationale: Same as above 

Response: EPA disagrees that the requirement should be deleted. Section 146.86(b)(4) of the final rule 

allows alternate methods of staging the cement, at the Director's discretion, provided the owner or 

operator can demonstrate using logs that the cement does not allow fluid movement behind the wellbore.

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3864 2.3.3.2 Use of corrosion-resistant cements 

(seeking comment) 

Comment: EPA Proposal: (5) Cement and cement additives must be compatible with the carbon 

dioxide stream and formation fluids and of sufficient quality and quantity to 

maintain integrity over the design life of the geologic sequestration project. 

The integrity and location of the cement shall be verified using technology 

capable of evaluating cement quality radially and identifying the location of 

channels to ensure that USDWs are not endangered. 

GWPC Recommendations: (5) Cement and cement additives must be suitable for use 

with the carbon dioxide stream and formation fluids and of sufficient quality 

and quantity to maintain integrity over the operating life the well. The 

integrity and location of the cement shall be verified using technology capable 

of evaluating cement quality radially and identifying the location of channels 

to ensure that USDWs are not endangered. 

Rationale: Experience with CO2 EOR under the class II program demonstrates the 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24904

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24905

574
effectiveness of existing cementing materials and procedures. Standard API 

cements have been used in numerous CO2 EOR operations without adverse 

consequences. Reference API CO2 EOR report and Carey et al. Bill Carey (SACROC) 

and Walter Crow (CCP2 - placement and annular gap more important than type). 

Once the well is plugged, the plug will isolate the other portions of the well 

from the injected fluids. 

Response: EPA clarifies that the requirement at §146.86(b)(5) is that cement and cement additives must 

be compatible with the CO2 stream and formation fluids and of sufficient quality and quantity to 

maintain integrity over the design life of the GS project. The rule does not specify materials to be used; 

rather, it provides owners or operators with the flexibility to choose, as long as the materials used in 

Class VI wells are compatible with fluids with which they may come into contact and meet or exceed 

standards developed for such materials by API or ASTM International, or comparable standards 

approved by the Director. 

EPA recognizes that the oil and gas industry has decades of experience injecting CO2 for the purpose of 

enhanced recovery, and that this practice has led to the development of many measures that would be 

appropriate for the design of Class VI wells. 

EPA disagrees that the casing, cement or other materials should only be designed for the period of the 

injection process, rather than the life of the sequestration project. GS projects are anticipated to have 

long life spans in comparison to other types of deep injection wells. Not only must Class VI wells be 

able to function safely and properly over the lifespan of the GS project, but they must be constructed 

such that USDWs remain protected after well plugging. The requirements at §146.86 will ensure that the 

well can maintain integrity throughout the proposed life span of the project, including after the injection 

well is plugged and through post-injection site care period and beyond. While the risk profile of a GS 

site will decrease following cessation of injection, EPA believes that Class VI wells must be designed to 

protect USDWs from endangerment for the life of the project. Furthermore, rigorous casing and 

cementing help ensure that the Class VI well will not serve as a conduit for movement of fluids 

associated with future injection operations. 

Additionally, EPA is developing guidance on the construction of Class VI wells. This guidance will be 

available on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3826 2.3.1.3 Packer requirements (seeking comment) 

Comment: Rule Provision: 146.86(c) 

EPA Proposal: (c) Tubing and packer. 

(1) All owner and operators of Class VI wells must inject fluids through tubing 

with a packer set at a depth opposite a cemented interval at the location 

approved by the Director. 

(2) In order for the Director to determine and specify requirements for tubing 

and packer, the owner or operator must submit the following information: 

(i) Depth of setting; 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24906

575
(ii) Characteristics of the carbon dioxide stream (chemical content, 

corrosiveness, temperature, and density); 

GWPC Recommendations: (c) Tubing and packer. 

(1) All owner and operators of Class VI wells must inject fluids through tubing 

with a packer set at a depth opposite a cemented interval at the location 

approved by the Director. 

(2) In order for the Director to determine and specify requirements for tubing 

and packer, the owner or operator must submit the following information: 

(i) Depth of setting; 

(ii) Composition of the carbon dioxide stream; 

Rationale: What does corrosiveness mean? How is it measured? 

Cannot measure the corrosiveness of a carbon dioxide stream. 

Composition of the cO2 stream is needed to design a tubing and packer system. 

The other listed characteristics are not needed. 

Response: As written, the text at §146.86(c)(3)(ii) accounts for all characteristics of the CO2 that could 

affect the performance of the tubing and packer, including the chemical content, corrosiveness, 

temperature, and density. The suggested revision to refer to CO2 "composition" would be less precise. 

EPA clarifies that, although corrosiveness does not have a unit of measure, corrosiveness can be 

technically measured and described. Procedures that can identify corrosion (or the absence of corrosion) 

in a Class VI well provide valuable operational information that the Director needs to determine 

appropriate standards for the tubing and packer. 

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3826 2.3.1.3 Packer requirements (seeking comment) 

Comment: Rule Provision: 146.86(c)(2) 

EPA Proposal: (iii) Injection pressure; 

(iv) Annular pressure; 

(v) Injection rate (intermittent or continuous) and volume of the carbon dioxide 

stream; 

(vi) Size of casing; and 

(vii) Tubing tensile, burst, and collapse strengths. 

GWPC Recommendations: (iii) Maximum proposed Injection temperature and pressure; 

(iv) Maximum proposed Annular pressure; 

(v) Maximum proposed Injection rate (intermittent or continuous) and volume of 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24907

576
the carbon dioxide stream; 

Rationale: It is more helpful to know the recommended information. 

The GWPC also recommends addition of the term "proposed in (iii), (iv) and (v) 

as this section relates to an application and not to actual established permit 

conditions 

Response: EPA has revised §146.86(c)(3)(iii) and (iv) to reference the maximum proposed injection 

pressure and maximum proposed annular pressure, respectively. EPA has revised §146.86(c)(3)(v) to 

read "proposed injection rate (intermittent or continuous), and volume and/or mass of the carbon dioxide 

stream." EPA believes that reference to the continuous injection rate would be duplicative of the 

maximum rate. EPA believes that considering the maximum injection and annular pressure would be 

more protective. 

Other EPA Comment Codes and Descriptions: 4110 2.4.1.1 Injection pressure limitations 

Comment: Rule Provision: 146.88 

EPA Proposal: 8. Injection well operating requirements 

(a) Except during stimulation, the owner or operator must ensure that injection 

pressure does not exceed 90 percent of the fracture pressure of the injection 

zone so as to assure that the injection does not initiate new fractures or 

propagate existing fractures in the injection zone. In no case may injection 

pressure initiate fractures in the confining zone(s) or cause the movement of 

injection or formation fluids that endangers a USDW. 

GWPC Recommendations: (a) The owner or operator must comply with a maximum 

injection pressure limit approved by the Director and specified in the permit. 

In approving a maximum injection pressure limit, the Director shall consider the 

results of well tests and, where appropriate, geomechanical or other studies 

that assess the risks of tensile failure and shear failure. The Director shall 

approve limits that, with a reasonable degree of certainty, will avoid 

initiation or propagation of fractures in the confining zone or cause otherwise 

non-transmissive faults transecting the confining zone to become transmissive. 

In no case may injection pressure cause movement of injection or formation 

fluids in a manner prohibited by 40 CFR Part 144.12(a). 

Rationale: Maintaining the integrity of the confining zone is the critical 

parameter. We believe establishing a maximum pressure based on an arbitrary 

percentage of injection zone fracture pressure does not address the issue of 

confining zone integrity in an appropriate way. 

Response: EPA notes that because determination of the injection pressure limit is based on the fracture 

pressure of the injection zone, the limit is site-specific and not arbitrary. EPA emphasizes that injection 

pressure limits are important to protect against fracturing of the confining zone, and that the requirement 

at §146.88(a) that the pressure in the injection zone not exceed 90 percent of the fracture pressure 

provides a margin of safety in the well operation and protects USDWs from endangerment. If the 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24909

577
Director determines, based on a review of the information collected as part of site characterization, that a 

lower injection pressure limitation is appropriate, the Director has the authority to set a lower limit in the 

operating permit than the limit established in the rule. 

EPA notes that during the site characterization process, owners or operators must submit data about the 

geology of the site, as specified at §146.82(a), including data on known or suspected faults and fractures 

and geomechanical information on fractures, stress, ductility, rock strength, and in situ fluid pressures 

within the confining zone. The Director will use these data to determine appropriate limits on injection. 

EPA is developing guidance on site characterization for GS projects to assist owners or operators in 

meeting the requirements of §146.82 and to assist directors in evaluating permit applications. The 

guidance will describe recommended approaches for characterizing the regional geology and 

hydrogeology of a proposed site and performing the necessary geochemical, geomechanical, and 

geophysical analyses of the injection and confining zone. EPA is also developing guidance for primacy 

agencies that will include recommended approaches for evaluating owner or operator-submitted data in 

setting permit conditions. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4100 2.4.1 Injection parameters 

Comment: EPA Proposal: (b) Injection between the outer-most casing protecting USDWs and 

the well bore is prohibited. 

GWPC Recommendations: (b) Injection of the CO2 stream between the outermost 

casing protecting USDWs and the well bore is prohibited. 

Rationale: Routine injection into zones other than the target interval(s) should 

be prohibited, however, wording of this requirement is not clear as to which 

interval is being addressed. An absolute prohibition on injection may also 

limit diagnostic options that could be useful. 

Sometimes inject other things to remediate well. 

Response: EPA retains the provision as proposed, and clarifies that injection between the casing and the 

well bore is prohibited. This is consistent with requirements for other injection well classes. 

Other EPA Comment Codes and Descriptions: 4100 2.4.1 Injection parameters 

Comment: EPA Proposal: (c) The owner or operator must fill the annulus between the tubing 

and the long string casing with a non-corrosive fluid approved by the Director. 

The owner or operator must maintain on the annulus a pressure that exceeds the 

operating injection pressure, unless the Director determines that such 

requirement might harm the integrity of the well. 

GWPC Recommendations: (c) The owner or operator must fill the annulus between 

the tubing and the long string casing with a corrosion inhibiting fluid approved 

by the Director. The owner or operator must maintain a positive pressure on the 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24910

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24911

578
annulus. 

Rationale: Agency and Industry experience with the Class II UIC program does not 

support this requirement. The standard proposed by EPA is consistent with 

neither the risk level related to CO2 nor the specifications needed to monitor 

the annular space for leakage. 

Rule Provision: 146.88(d) 

EPA Proposal: (d) Other than during periods of well workover (maintenance) 

approved by the Director in which the sealed tubing-casing annulus is of 

necessity disassembled for maintenance or corrective procedures, the owner or 

operator must maintain mechanical integrity of the injection well at all times. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA believes that maintaining an annulus pressure that is higher than the injection pressure, 

as required at §146.88(c), is appropriate and will ensure that if there are leaks in the tubing, the annulus 

fluid will move into the tubing, rather than the injectate moving out of the tubing and potentially along 

the outside of the well. EPA believes this requirement is appropriate for Class VI wells given the 

potential high volumes and supercritical nature of the CO2 injectate, potential geomechanical stresses in 

the wellbore, and the potential for movement of the CO2 in the event of a mechanical integrity loss. 

EPA disagrees that maintaining an annulus pressure higher than the injection pressure impacts 

continuous pressure monitoring for internal MI. The purpose of continuous pressure monitoring (to 

demonstrate internal MI) is to demonstrate that no pressure changes are occurring, because a drop in 

pressure on the annulus provides an early indication that attention is needed to prevent a loss of MI or 

unacceptable fluid movement. EPA believes that any change in the pressure on the annulus between 

tubing and long stem casing, regardless of what the annulus pressure is relative to injection pressure, can 

indicate a leak. 

EPA agrees with the commenter that maintaining mechanical integrity is an essential component of 

protecting USDWs. The final rule retains a requirement to maintain mechanical integrity at §146.88(d). 

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells 

(seeking comment) 

Comment: Rule Provision: 146.88 

EPA Proposal: (e) The owner or operator must install and use continuous 

recording devices to monitor: The injection pressure; the rate, volume, and 

temperature of the carbon dioxide stream; and the pressure on the annulus 

between the tubing and the long string casing and annulus fluid volume; and must 

install and use alarms and automatic down-hole shut-off systems, designed to 

alert the operator and shut-in the well when operating parameters such as 

annulus pressure, injection rate or other parameters approved by the Director 

diverge beyond permitted ranges and/or gradients specified in the permit; 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24912

579
GWPC Recommendations: (e) The owner or operator must install and use continuous 

recording devices to monitor: the injection pressure; the rate, volume, and 

temperature of the carbon dioxide stream. The owner or operator must regularly 

monitor the pressure on the annulus between the tubing and the long string 

casing. The owner or operator must install, test and use alarms and automatic 

shut-off systems, designed to alert the operator and shut-in the well when 

operating parameters such as injection rate, injection pressure, or other 

parameters approved by the Director diverge beyond ranges and/or gradients 

specified in the permit; 

Rationale: Over-pressure protection is best achieved by ensuring compatibility 

of the casing/tubing material design strength with the surface injection 

(compression) system. Down-hole shut-in devices may be appropriate, however, 

for site-specific situations of unique potential impact (such as offshore or 

near airports), but they should not be mandated for all injection sites. 

Response: EPA acknowledges that proper design of the well, including appropriate materials and 

emplacement of casing and tubing, is essential to proper operation of the well so that USDWs are 

protected. Such design, however, does not eliminate the possibility of failure, e.g., due to overpressurization as suggested by the commenter. EPA believes that a multiple-barrier approach, which 

includes appropriate well design as required at §146.86, suitable injection pressure limits as required at 

§146.88(a), and automatic shut-off systems, as required at §146.88(e), is necessary to ensure protection 

of USDWs from endangerment from the risks associated with CO2 GS. 

After evaluating the risks and benefits of down-hole shut-off systems and considering additional 

research, EPA will not require automatic down-hole shut-off devices for onshore Class VI wells since it 

is not necessary in all cases to ensure protection of USDWs from endangerment. Instead, the final rule, 

at §146.88(e)(2), requires that owners or operators of onshore Class VI wells install automatic surface 

shut-off devices. The rule affords Director's discretion to mandate automatic down-hole shut-off devices 

in onshore situations that may warrant their use. However, the Agency believes that offshore Class VI 

wells present unique construction and operational conditions, including isolation from shorelines and the 

need to construct wells through the water column and the subsurface, which may delay response time in 

the event of well difficulties. The rule requires, at §146.88(e)(3), that owners or operators of offshore 

wells within State territorial waters install automatic down-hole shut-off systems. EPA believes that 

these requirements at §146.88(e) ensure that proper precautions are taken to prevent subsurface fluid 

movement and ensure protection of USDWs. 

While EPA acknowledges that the likelihood of damage to onshore facilities is lower than that for offshore facilities, down-hole shut-off valves are still commonly used in onshore facilities such as acid gas 

injection wells and high pressure, high-temperature wells. While valve failure is a concern, EPA 

believes that technology has advanced sufficiently to make valve failure a rare occurrence and to 

appropriately handle such failure if it occurs. For example, wireline retrievable devices can allow repair 

or replacement of damaged devices without necessitating pulling the tubing. 

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells 

(seeking comment) 

Comment: Rule Provision: 146.88 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24913

580
EPA Proposal: (f) If a down-hole automatic shutdown is triggered or a loss of 

mechanical integrity is discovered, the owner or operator must immediately 

investigate and identify as expeditiously as possible the cause of the shutoff. 

If, upon such investigation, the well appears to be lacking mechanical 

integrity, or if monitoring required under paragraph (e) of this section 

otherwise indicates that the well may be lacking mechanical integrity, the owner 

or operator must: 

GWPC Recommendations: (f) If an automatic shutdown is triggered or a loss of 

mechanical integrity is discovered, the owner or operator must immediately 

investigate and identify as expeditiously as possible the cause. If, upon such 

investigation, the well appears to be lacking mechanical integrity, or if 

monitoring required under paragraph (e) of this section otherwise indicates that 

the well may be lacking mechanical integrity, the owner or operator must: 

Rationale: Eliminates requirement for down-hole shutoff device. Although the 

use of downhole shutoff valves may be needed in some applications, their 

required use would be less than ideal for many reasons such as the fact that 

since they are a downhole installation, integrity and maintenance of the valves 

is difficult. Further the installation of surface valves would allow for more 

control and provide for visual inspection. Since the key is to shut down the 

injection flow if a parameter is exceeded, the use of surface valves would be 

just as effective as downhole valves. 

Response: As described above, EPA will not require automatic down-hole shut-off devices for onshore 

Class VI wells since it is not necessary in all cases to ensure protection of USDWs from endangerment. 

Instead, the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells 

install automatic surface shut-off devices. The rule affords Director's discretion to mandate automatic 

down-hole shut-off devices in onshore situations that may warrant their use. The rule requires, at 

§146.88(e)(3), that owners or operators of offshore wells within State territorial waters install automatic 

down-hole shut-off systems. Please see the final rule and preamble for additional information on EPA's 

final approach. 

Other EPA Comment Codes and Descriptions: 4000 2.4 Proposed Injection Well Operating 

Requirements (40 CFR 146.88) 

Comment: Rule Provision: 146.88(f) 

EPA Proposal: (1) Immediately cease injection; 

(2) Take all steps reasonably necessary to determine whether there may have been 

a release of the injected carbon dioxide stream into any unauthorized zone; 

(3) Notify the Director within 24 hours; 

(4) Restore and demonstrate mechanical integrity to the satisfaction of the 

Director prior to resuming injection; and 

(5) Notify the Director when injection can be expected to resume. 

GWPC Recommendations: Support the proposed EPA language for (1), (2), and (5) 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24914

581
(3) Notify the Director within 24 hours of discovery; 

(4) Restore and demonstrate mechanical integrity to the satisfaction of the 

director as soon as practicable and prior to resuming injection. 

Rationale: Needs to be reasonable and allow for time following discovery. 

It was felt that some timeframe for restoration of mechanical integrity should 

be added to (4) 

Response: The final rule text at §146.88(f) now reads, "If a shutdown (i.e., down-hole or at the surface) 

is triggered or a loss of mechanical integrity is discovered." Therefore the notice required at §146.88(f)

(3) must be provided within 24 hours of an automatic shut-off device being triggered or a loss of 

mechanical integrity being discovered. EPA believes this provision is necessary to ensure timely 

response to potential USDW endangerment. 

Other EPA Comment Codes and Descriptions: 4500 2.5 Proposed Mechanical Integrity Testing 

(MIT) Requirements (40 CFR 146.89) 

Comment: Rule Provision: 146.89 

EPA Proposal: 9. Mechanical integrity 

(a) A Class VI well has mechanical integrity if: 

(1) There is no significant leak in the casing, tubing or packer; and 

(2) There is no significant fluid movement into a USDW through channels adjacent 

to the injection well bore. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment and the final rule retains the text at 146.89(a) as proposed. 

For additional information, please see the discussion of MITs in the final rule preamble. 

Other EPA Comment Codes and Descriptions: 4520 2.5.1 Continuous internal mechanical integrity 

monitoring (seeking comment); 4720 2.7.2 Operational recordkeeping and reporting 

Comment: EPA Proposal: (b) To evaluate the absence of significant leaks under paragraph 

(a)(1) of this section, owners or operators must, following an initial annulus 

pressure test, continuously monitor injection pressure, rate, injected volumes, 

and pressure on the annulus between tubing and long stem casing and annulus 

fluid volume as specified in § 146.88(e); 

GWPC Recommendations: (b) To evaluate the absence of significant leaks under 

paragraph (a)(1) of this section, owners or operators must, following an initial 

annulus pressure test, continuously monitor and record at least daily injection 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24915

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24916

582
pressure, rate, injected volumes, and pressure on the annulus between tubing 

and long stem casing and annulus fluid volume as specified in §146.88 (e); 

Rationale: We believe that injection parameters must not only be monitored but 

should be recorded at least daily. We further believe the use of monitoring with 

digital equipment which records readings on an appropriate frequency should be 

considered continuous for purposes of this section. 

Response: EPA believes that continuous pressure monitoring to demonstrate internal mechanical 

integrity of Class VI wells required at §146.89(b) is important, given the potential corrosive impact of 

CO2 and impurities on well materials, the potential geomechanical impacts to well integrity due to CO2 

phase changes, and the temperature and pressure effects associated with injecting supercritical CO2. 

EPA also believes that the technology for continuous monitoring is practicable, available, and is 

currently in fairly wide use. Class VI injection wells will be equipped with dedicated computer-based 

continuous pressure monitoring devices (in concert with the shut-off systems required for GS wells), 

which typically take readings several times per second (i.e., more frequently than daily) and record them 

electronically in a computer system. 40 CFR §146.91(a)(2) requires that monthly averages of the 

continuous annulus monitoring be reported on a semiannual basis. For additional information, please see 

the discussion of MITs in the final rule preamble. 

Other EPA Comment Codes and Descriptions: 4540 2.5.2 Proposed external MIT requirements; 4543 

2.5.2.1 MIT procedures and methods for GS (seeking comment) 

Comment: Rule Provision: 146.89(c) 

EPA Proposal: (c) At least once per year, the owner or operator must use one of 

the following methods to determine the absence of significant fluid movement 

under paragraph (a)(2) of this section: 

(1) A tracer survey such as oxygen-activation logging; 

(2) A temperature or noise log; or 

(3) A casing inspection log, if required by the Director. 

GWPC Recommendations: (c) At least once per year, the owner or operator must 

confirm the absence of significant fluid movement under paragraph (a)(2) of this 

section using a method acceptable to the Director (e.g. including diagnostic 

surveys such as oxygen-activation logging or temperature or noise logs). 

Delete (1) 

Delete (2) 

Delete (3) 

Rationale: Revised text supports a performance-based approach and allows the 

development and use of new technologies as they become available. 

Response: EPA believes that the MITs described in §146.89(c) of the rule (e.g., an approved tracer log 

or temperature or noise logs) are effective methods to demonstrate external MI, provide an important 

early warning of potential problems in the injection well system, and represent standard techniques that 

have been used successfully by the drilling industry and for the UIC Program for decades. The Agency

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24917

583
notes that the regulations do provide the Director flexibility at §146.89(e) to approve the use of 

alternative MIT methods. 

EPA agrees that the casing inspection log is not an appropriate test to detect fluid movement behind the 

casing, but clarifies that it is appropriate to be used to determine the presence or absence of corrosion of 

the long-string casing, and is required if the Director determines that it is necessary based on sitespecific information. EPA has revised the final GS rule to require that the frequency of the casing 

inspection log must be specified in the approved testing and monitoring plan. See §146.89(d). 

Other EPA Comment Codes and Descriptions: 4543 2.5.2.1 MIT procedures and methods for GS 

(seeking comment) 

Comment: EPA Proposal: (d) The Director may require any other test to evaluate mechanical 

integrity under paragraph (a)(1) or (a)(2) of this section. Also, the Director 

may allow the use of a test to demonstrate mechanical integrity other than those 

listed above with the written approval of the Administrator. To obtain 

approval, the Director must submit a written request to the Administrator, which 

must set forth the proposed test and all technical data supporting its use. The 

Administrator must approve the request if it will reliably demonstrate the 

mechanical integrity of wells for which its use is proposed. Any alternate 

method approved by the Administrator will be published in the Federal Register 

and may be used in all States in accordance with applicable State law unless its 

use is restricted at the time of approval by the Administrator. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment and the final rule retains the text as proposed. 

Other EPA Comment Codes and Descriptions: 4543 2.5.2.1 MIT procedures and methods for GS 

(seeking comment) 

Comment: Rule Provision: 146.89(e) 

EPA Proposal: (e) In conducting and evaluating the tests enumerated in this 

section or others to be allowed by the Director, the owner or operator and the 

Director must apply methods and standards generally accepted in the industry. 

When the owner or operator reports the results of mechanical integrity tests to 

the Director, he/she shall include a description of the test(s) and the 

method(s) used. In making his/her evaluation, the Director must review 

monitoring and other test data submitted since the previous evaluation. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24918

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24919

584
Response: EPA acknowledges the comment and the final rule retains the text as proposed. 

Other EPA Comment Codes and Descriptions: 4543 2.5.2.1 MIT procedures and methods for GS 

(seeking comment) 

Comment: EPA Proposal: (f) The Director may require additional or alternative tests if 

the results presented by the owner or operator under paragraph (d) of this 

section are not satisfactory to the Director to demonstrate that there is no 

significant leak in the casing, tubing or packer or significant movement of 

fluid into or between USDWs resulting from the injection activity as stated in 

paragraphs (a)(1) and (2) of this section. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment and the final rule retains the text as proposed. 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Rule Provision: 146.90 

EPA Proposal: 10. Testing and monitoring requirements 

The owner or operator of a Class VI well must prepare, maintain, and comply with 

a testing and monitoring plan to verify that the geologic sequestration project 

is operating as permitted and is not endangering USDWs. The testing and 

monitoring plan must be submitted with the permit application, for Director 

approval, and must include a description of how the owner or operator will meet 

the requirements of this section. Testing and monitoring associated with 

geologic sequestration projects must, at a minimum, include: 

GWPC Recommendations: Support the proposed EPA language. 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS rule. See the final rule and preamble 

for further discussion on EPA's final approach. 

EPA agrees with commenters that developing and following testing and monitoring plans is an 

important part of assuring that a GS project is operating properly and is crucial for the early detection of 

potential endangerment to USDWs. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24920

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24922

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24923

585
Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: Rule Provision: 146.90 

EPA Proposal: (a) Analysis of the carbon dioxide stream with sufficient 

frequency to yield data representative of its chemical and physical 

characteristics; 

(b) Installation and use, except during well workovers as defined in § 

146.86(d), of continuous recording devices to monitor injection pressure, rate 

and volume; the pressure on the annulus between the tubing and the long string 

casing; and the annulus fluid volume; 

GWPC Recommendations: Support the proposed EPA language in (a) 

(b) Installation and use, except during well workovers as defined in §146.88(d), 

of continuous monitoring devices (including digital devices capturing periodic 

data) to monitor injection pressure, rate and volume; and record at least daily 

the pressure on the annulus between the tubing and the long string casing; 

Rationale: 146.86(d) does not exist; perhaps 146.88(d) is what was apparently 

intended. 

Response: EPA acknowledges the comment; the final rule retains the language in §146.90(a) as 

proposed. EPA adds that the final GS rule references §146.88(e), as the commenter suggests. 

Regarding §146.90(b), based on its evaluation of all public comments and input on the proposed rule 

and NODA and Request for Comment EPA has made many revisions to the GS rule. See the final rule 

and preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4630 2.6.3 Corrosion monitoring 

Comment: Rule Provision: 146.90 

EPA Proposal: (c) Corrosion monitoring of the well materials for loss of mass, 

thickness, cracking, pitting and other signs of corrosion must be performed on a 

quarterly basis to ensure that the well components meet the minimum standards 

for material strength and performance set forth in § 146.86(b) by: 

GWPC Recommendations: c) Corrosion monitoring of the well materials for loss of 

mass, thickness, cracking, pitting and other signs of corrosion must be 

performed and recorded at least quarterly and may be modified to be less 

frequent as approved by the Director based on construction materials, operating 

conditions, and monitoring history to ensure that the well components meet the 

minimum standards for material strength and performance set forth in §146.86(b) 

by: 

Rationale: Allows application of performance based approach. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24924

586
Rationale: Allows less frequent monitoring, for example, where corrosion 

resistant materials are used. 

Response: EPA believes that quarterly corrosion monitoring is appropriate given the potentially 

corrosive nature of the CO2 stream. CO2 in the presence of water becomes acidic, potentially 

accelerating corrosion of well materials. The CO2 stream for a GS project may also contain small 

volumes of impurities that could contribute to corrosion. For these reasons, the final rule requires 

quarterly corrosion monitoring, at §146.90(c). 

Based on its evaluation of all public comments and input on the proposed rule and NODA and Request 

for Comment EPA has made many revisions to the GS rule. See the final rule and preamble for further 

discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4630 2.6.3 Corrosion monitoring 

Comment: Rule Provision: 146.90(c) 

EPA Proposal: (1) Placing coupons of the well construction materials in contact 

with the carbon dioxide stream; or 

(2) Routing the carbon dioxide stream through a loop constructed with the 

material used in the well; or 

(3) Using an alternative method approved by the Director; 

GWPC Recommendations: (1) Analyzing coupons of the well construction materials 

placed in contact with the carbon dioxide stream; or 

(2) Routing the carbon dioxide stream through a loop constructed with the 

material used in the well and inspecting the materials in the loop; or 

(3) Using an alternative method, materials, or time period approved by the 

Director; 

Rationale: Clarification edits 

Response: As described above, EPA believes that quarterly corrosion monitoring is appropriate given 

the potentially corrosive nature of the CO2 stream. Based on its evaluation of all public comments and 

input on the proposed rule and NODA and Request for Comment EPA has made many revisions to the 

GS rule. See the final rule and preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 4660 2.6.6 Geochemical monitoring 

Comment: Rule Provision: 146.90(d) 

EPA Proposal: (d) Periodic monitoring of the ground water quality and 

geochemical changes above the confining zone(s) that may be a result of carbon 

dioxide movement through the confining zone or additional identified zones: 

(1) The location and number of monitoring wells must be based on specific 

information about the geologic sequestration project, including injection rate 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24925

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24926

587
and volume, geology, the presence of artificial penetrations and other factors; 

(2) The monitoring frequency and spatial distribution of monitoring wells must 

be based on baseline geochemical data that has been collected under § 146.82(a) 

(6) and any modeling results in the area of review evaluation required by § 

146.84(b); 

GWPC Recommendations: (d) Periodic monitoring of reservoir formation fluid 

quality in a permeable and porous formation as near as practicable to the 

confining zone(s) for geochemical changes that may be a result of carbon dioxide 

or displaced formation fluid movement: 

(1) The location and number of monitoring wells must be based on specific 

information about the geologic sequestration project, including injection rate 

and volume, geology, the presence of artificial penetrations and other relevant 

factors as warranted by a risk-assessment; 

(2) The monitoring frequency and spatial distribution of monitoring wells must 

be based on geological, geochemical and geophysical data that has been collected 

under §146.82(d) and any modeling results in the area of review evaluation 

required by §146.84(b); 

Rationale: Drilling monitoring wells should be carefully considered since each 

well introduces a potential pathway for movement. 

[Geochemical data do not have a high degree of relevance in selecting monitoring 

well sites.] 

Response: EPA believes that monitoring using wells in the injection zone, e.g., for pressure monitoring 

as required at §146.90(g)(1), can be safely performed if the wells are constructed to prevent flow 

between the injection zone and USDWs or other layers above the confining zone. Such construction 

technologies exist and have been used in the oil and gas industry for years. EPA believes that properly 

constructed monitoring wells will be a safe way to obtain the data that is essential to ensure that the 

injected CO2 remains confined in the injection zone and that pressure changes are not causing 

movement of formation or other fluids. To mitigate the risk of fluid movement, EPA requires owners 

and operators to submit a testing and monitoring plan that describes how the owner or operator plans to 

site and construct monitoring wells. EPA has developed a brief technical paper on construction of 

monitoring wells that perforate the confining zone; this paper can be found in the rulemaking docket. 

EPA is also developing guidance on well construction that will include recommendations for monitoring 

well construction. The guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Baseline characterization of the site, including the geochemical data and initial modeling, will be highly 

valuable in selection of monitoring well locations and in refining plans for monitoring frequency. The 

GS rule stipulates that the monitoring frequency and spatial distribution of monitoring wells must be 

based on baseline geochemical data that were collected during the initial site characterization and the 

area of review evaluation (§146.90(d)(2)). The details of the geochemical monitoring must be based on 

site-specific information and described in the Director-approved testing and monitoring plan. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24927

588
Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: Rule Provision: 146.90 

EPA Proposal: (e) A demonstration of external mechanical integrity pursuant to § 

146.89(c) at least once per year throughout the duration of the geologic 

sequestration project; 

(f) A pressure fall-off test at least once every five years unless more frequent 

testing is required by the Director based on site specific information; 

GWPC Recommendations: (e) A demonstration of external mechanical integrity 

pursuant to §146.89(c) at least once per year until the well is plugged; 

(f) A pressure fall-off test or other equivalent test that identifies reservoir 

conditions with respect to flow dynamics at least once every five years unless 

more frequent testing is required by the Director based on site specific 

information; 

Rationale: Redundant to section 146.89 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS rule. See the final rule and preamble 

for further discussion on EPA's final approach. 

EPA believes that pressure fall-off testing is necessary for GS wells. Pressure fall-off tests are designed 

to verify that modeled projections of reservoir pressure decline agree with measured pressure decline 

profiles. These tests can be useful in AoR calculations and reevaluations and may also indicate 

mischaracterization of site geology and the presence of leakage pathways. EPA therefore believes that 

pressure fall-off testing is necessary every five years at a minimum, and the final GS regulation includes 

this requirement at §146.90(f). Pressure fall-off tests may be conducted in conjunction with other well 

performance tests (i.e., mechanical integrity testing) to ensure safe and effective operations. 

Other EPA Comment Codes and Descriptions: 4650 2.6.5 CO2 plume and pressure front tracking 

(seeking comment) 

Comment: EPA Proposal: (g) Testing and monitoring to track the extent of the carbon 

dioxide plume and the position of the pressure front by either monitoring for 

pressure changes in the first formation overlying the confining zone or using 

indirect, geophysical techniques (e.g., seismic, electrical, gravity, or 

electromagnetic surveys and/or down-hole carbon dioxide detection tools); 

GWPC Recommendations: (g) Testing and monitoring to track the extent of the 

carbon dioxide plume and the position of the pressure front. 

Rationale: Monitoring outside of the injection zone provides little information 

of value for tracking and monitoring the injected plume. Examples of how to 

test and monitor could be included in the Preamble but need not be included in 

the rule itself. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24928

589
Response: EPA has revised this requirement in the final rule. The final GS regulation, at §146.90(g)(1), 

requires all GS project owners or operators to monitor for pressure changes in the injection zone. EPA 

believes that pressure monitoring in the injection zone is necessary to track the development and 

movement of the pressure front and CO2 plume. 

Pressure monitoring within the injection zone is necessary because any such monitoring above the 

confining zone would not detect movement of the pressure front unless a breach of the confining zone 

occurs. EPA believes that monitoring using wells in the injection zone (i.e., that penetrate the confining 

zone) can be safely performed if the wells are constructed to prevent flow between the injection zone 

and USDWs or other layers above the confining zone. Such construction technologies exist and have 

been used in the oil and gas industry for years. EPA believes that the benefits of monitoring in the 

injection formation outweigh the manageable risk of those monitoring wells serving as conduits for fluid 

movement. EPA adds that owners or operators may consider performing additional pressure monitoring 

in wells that are above the confining zone (e.g., in the same wells used to perform ground water quality 

monitoring required at §146.90(d)) to provide additional verification that no pressure changes are 

occurring above the confining zone due to CO2 leakage. Monitoring also identifies needed remedial 

actions, provides inputs for AoR reevaluation modeling, and targets additional geochemical and surface 

monitoring needs. Knowledge of the location of the CO2 plume and the associated pressure front will 

assure the public that GS projects are proceeding according to plan, provide sufficient information to the 

owner or operator and Director, or allow for appropriate actions to address any indication that USDWs 

may be endangered. 

EPA acknowledges that, at certain sites, there may be a need for more or different monitoring schemes 

(which may include monitoring in the confining zone), and adds that it is important to balance the need 

for adequate monitoring that ensures USDW protection from endangerment against too many artificial 

penetrations which could serve as conduits for fluid migration. Site-specific testing and monitoring plans 

should describe the proposed monitoring regime, which must be approved by the Director. 

Flexibility is also provided regarding how to monitor for the specific data required by the final rule. The 

testing and monitoring plan is developed by the owner or operator in consultation with the Director and 

is designed to ensure that a detailed, Director-approved document describing how monitoring will be 

conducted during the lifetime of the project exists. EPA is developing guidance on testing and 

monitoring to assist owners or operators and Directors in evaluating requirements under §146.90, 

including proposed monitoring plans. The guidance describes available technologies and recommended 

approaches for implementing a testing and monitoring plan, including pre-operational geophysical 

logging and testing of injection wells, MITs, injection well testing during operation, groundwater quality 

monitoring, tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which 

may be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 4670 2.6.7 Surface air monitoring and/or soil gas 

monitoring (seeking comment) 

Comment: Rule Provision: 146.90 

EPA Proposal: (h) At the Director’s discretion, surface air monitoring and/or 

soil gas monitoring to detect movement of carbon dioxide that could endanger a 

USDW. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24929

590
GWPC Recommendations: (h) At the Director’s discretion based on site-specific 

conditions and risk-based factors, surface air monitoring and/or soil gas 

monitoring to detect movement of carbon dioxide that could endanger a USDW. 

Rationale: In most situations soil and air monitoring does not provide an 

effective method of protecting USDWs. 

Response: As described above, EPA acknowledges that air and soil gas monitoring are subject to sitespecific limitations and may not be suitable in all settings as a method to ensure USDW protection. 

However, EPA does not believe that this should entirely preclude their use. The final rule at §146.90(h) 

retains the allowance for surface air and soil gas monitoring at the discretion of the Director as a means 

of identifying leaks that may pose a risk to USDWs and informing emergency notification of a Class VI 

owner or operator and UIC Director in the event of a USDW endangerment, pursuant to requirements at 

§146.91(c). 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Rule Provision: 146.90(h) 

EPA Proposal: (1) The testing and monitoring plan must be based on potential 

vulnerabilities within the area of review; 

(2) The monitoring frequency and spatial distribution of surface air monitoring 

and/or soil gas monitoring must reflect baseline data and the monitoring plan 

must include how the proposed monitoring will yield useful information on the 

area of review delineation and/or compliance with standards under 40 CFR 144.12; 

GWPC Recommendations: (1) The testing and monitoring plan must be based on sitespecific geologic factors, modeling, and risk-assessment within the area of 

review; 

(2) Agree with EPA language 

Rationale: The GWPC feels that the term "potential vulnerabilities" is too 

nebulous. We suggest replacing this term with the term "site-specific geologic 

factors, modeling, and risk-assessment." 

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA 

and Request for Comment EPA has made many revisions to the GS rule. See the final rule and preamble 

for further discussion on EPA's final approach. 

EPA anticipates that the testing and monitoring plan will address site-specific geologic factors, 

modeling, and risk-assessment. EPA is developing guidance on how best to develop the various required 

project plans, including the testing and monitoring plan. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24930

Commenter Name: Michel Paque Letter ID: 0259

591
Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Rule Provision: 146.90(i) 

EPA Proposal: (i) Any additional monitoring, as required by the Director, 

necessary to support, upgrade, and improve computational modeling of the area of 

review evaluation required under § 146.84(b) and to determine compliance with 

standards under 40 CFR 144.12; and 

(j) A quality assurance and surveillance plan for all testing and monitoring 

requirements. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. The final rule retains these provisions as proposed. 

Other EPA Comment Codes and Descriptions: 4760 2.7.6 Proposed reporting frequency (seeking 

comment) 

Comment: Rule Provision: 146.91 

11. Reporting requirements. 

The owner or operator must, at a minimum, provide the following reports to the 

Director, for each permitted Class VI well: 

(a) Semi-annual reports containing: 

(1) Any changes to the physical, chemical and other relevant characteristics of 

the carbon dioxide stream from the proposed operating data; 

(2) Monthly average, maximum and minimum values for injection pressure, flow 

rate and volume, and annular pressure; 

GWPC Recommendations: (a) Semi-annual or at a frequency determined by the 

Director reports containing: 

(1) Any significant changes to the physical, chemical and other relevant 

characteristics of the carbon dioxide stream from the proposed operating data; 

Rationale: Should be semi-annual unless otherwise determined 

Response: EPA is retaining the semi-annual reporting requirements as proposed at §146.91(a). These 

requirements ensure the Director has the information needed to take preventive action in a timely 

manner to protect USDWs from endangerment. For additional information, please see the final rule and 

the preamble for a discussion of EPA's final approach to recordkeeping and reporting. 

Commenter Organization: Ground Water Protection Council Comment ID: 24931

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24932

592
Other EPA Comment Codes and Descriptions: 4720 2.7.2 Operational recordkeeping and reporting 

Comment: Rule Provision: 146.91(a) 

EPA Proposal: (3) A description of any event that exceeds operating parameters 

for annulus pressure or injection pressure as specified in the permit; 

(4) A description of any event which triggers a shutdown device required 

pursuant to § 146.88(e) and the response taken; 

(5) The monthly volume of the carbon dioxide stream injected over the reporting 

period and project cumulatively; 

(6) Monthly annulus fluid volume added; and 

(7) The results of monitoring prescribed under § 146.90. 

GWPC Recommendations: (3) A description of any event that significantly exceeds 

operating parameters for annulus pressure or injection pressure as specified in 

the permit; 

(4) A description of any event which triggers a shutdown device required 

pursuant to §146.88(e) and the response taken; 

Rationale: EPA should consider some significance threshold on reporting these 

events, to avoid reporting events would be of limited interest or consequence. 

Response: EPA retained this provision as proposed. The final rule at §146.91(a)(3) requires reporting of 

all exceedances of operating parameters. EPA disagrees with the suggestion to report only "significant" 

exceedances. Making a determination as to whether an exceedance is "significant" is not the purpose of 

the requirement. EPA believes that the ability of an operator to consistently meet operating requirements 

and avoid exceedances provides evidence of a well-managed GS project that is in compliance with the 

Class VI permit. If multiple exceedances occur, the Director should be aware of such occurrences, and 

that information will aid in his/her determination of whether these indicate problems at the site, and 

what is the appropriate course of action (e.g., a well workover, modification of operating parameters, or 

imposition of a penalty) to remediate such problem(s). 

Other EPA Comment Codes and Descriptions: 4720 2.7.2 Operational recordkeeping and reporting; 

4740 2.7.4 Electronic reporting (seeking comment) 

Comment: EPA Proposal: (b) Report, within 30 days the results of: 

(1) Periodic tests of mechanical integrity; 

(2) Any other test of the injection well conducted by the permittee if required 

by the Director; and 

(3) Any well workover. 

(c) Owners or operators must submit reports in an electronic format acceptable 

to the Director. At the discretion of the Director, other formats may be 

accepted. 

GWPC Recommendations: Support the proposed EPA language. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24933

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24934

593
Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. Please see the final rule and the discussion of reporting 

preamble for additional information on EPA's final rulemaking approach. 

EPA believes that electronic formatting is the most appropriate format for submitting Class VI project 

information to the Director, and that many GS well owners or operators will have the capability to report 

electronically. 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: Rule Provision: 146.92 

EPA Proposal: 12. Injection well plugging. 

(a) Prior to the well plugging, the owner or operator must flush each Class VI 

injection well with a buffer fluid, determine bottomhole reservoir pressure, and 

perform a final mechanical integrity test. 

GWPC Recommendations: (a) Prior to the well plugging, the owner or operator must 

flush each Class VI injection well with a buffer fluid, determine bottomhole 

reservoir pressure, and perform a final external mechanical integrity test. 

Rationale: Many of the components that would be tested by an internal MIT are 

removed or tested during the plugging process. Consequently, the GWPC suggests 

including the term internal to the language for clarification. 

Response: EPA agrees that only an external MIT is required, and has modified the GS rule at §146.92

(a) to require owners or operators to perform a final external mechanical integrity test prior to the well 

plugging. 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: Rule Provision: 146.92(b) 

EPA Proposal: (b) Well Plugging Plan. The owner or operator of a Class VI well 

must prepare, maintain, and comply with a plan that is acceptable to the 

Director. The requirement to maintain and implement an approved plan is 

directly enforceable regardless of whether the requirement is a condition of the 

permit. The well plugging plan must be submitted as part of the permit 

application and must include the following information: 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24935

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24936

594
Response: EPA acknowledges the commenter’s support; the final rule retains this provision. 

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities (seeking 

comment) (40 CFR 146.92) 

Comment: EPA Proposal: (1) Appropriate test or measure to determine bottomhole reservoir 

pressure; 

(2) Appropriate testing methods to ensure mechanical integrity as specified in § 

146.89; 

(3) The type and number of plugs to be used; 

(4) The placement of each plug including the elevation of the top and bottom of 

each plug; 

(5) The type and grade and quantity of material to be used in plugging. The 

material must be compatible with the carbon dioxide stream; and 

(6) The method of placement of the plugs. 

GWPC Recommendations: Support the proposed EPA language for (1), (3), (4) and 

(6) 

(2) Appropriate testing methods to ensure final external mechanical integrity as 

specified in §146.89(c); 

(5) The type and grade and quantity of material to be used in plugging. The 

material must be suitable for use with the carbon dioxide stream; and 

Rationale: Many of the components that would be tested by an internal MIT are 

removed or tested during the plugging process. Consequently, the GWPC suggests 

adding the term external to the language for clarification. 

Response: Regarding the suggested edit at 146.92(b)(2), EPA agrees that only an external MIT is 

required, and has modified the GS rule at §146.92(a) to require owners or operators to perform a final 

external mechanical integrity test prior to the well plugging. 

Regarding the edit at 146.92(b)(5), EPA believes, considering the potentially corrosive nature of CO2 

when it is in contact with water, that the requirement that the material must be compatible with the CO2 

stream is appropriate. The final rule retains this requirement. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 

146.92) 

Comment: EPA Proposal: (c) Notice of intent to plug. The owner or operator must notify 

the Director at least 60 days before plugging of a well. At this time, if any 

changes have been made to the original well plugging plan, the owner or operator 

must also provide the revised well plugging plan. At the discretion of the 

Director, a shorter notice period may be allowed. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24937

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24938

595
GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 

146.92) 

Comment: Rule Provision: 146.92(d) 

EPA Proposal: (d) Plugging report. Within 60 days after plugging or at the time 

of the next semi-annual report (whichever occurs earlier) the owner or operator 

must submit a plugging report to the Director. If the semi-annual report is due 

less than 15 days after completion of plugging, then the report must be 

submitted within 60 days after plugging. The report must be certified as 

accurate by the owner or operator and by the person who performed the plugging 

operation (if other than the owner or operator.) 

GWPC Recommendations: (d) Plugging report. Within 60 days after plugging the 

owner or operator must submit a plugging report to the Director. The report 

must be certified as accurate by the owner or operator and by the person who 

performed the plugging operation (if other than the owner or operator.) 

Rationale: Simplification 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads, "Within 

60 days after plugging the owner or operator must submit a plugging report to the Director." 

Other EPA Comment Codes and Descriptions: 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Rule Provision: 146.93 

EPA Proposal: 13. Post-injection site care and site closure 

(a) The owner or operator of a Class VI well must prepare, maintain, and comply 

with a plan for post-injection site care and site closure that meets the 

requirements of paragraph (a)(2) of this section and is acceptable to the 

Director. 

(1) The owner or operator must submit the post-injection site care and site 

closure plan as a part of the permit application to be approved by the Director. 

GWPC Recommendations: Support the proposed EPA language 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24939

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24940

596
Rationale: Agree with EPA’s rationale 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: EPA Proposal: (2) The post-injection site care and site closure plan must 

include the following information: 

(i) The pressure differential between pre-injection and predicted post-injection 

pressures in the injection zone; 

(ii) The predicted position of the carbon dioxide plume and associated pressure 

front at site closure as demonstrated in the area of review evaluation required 

under § 146.84(b); 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision. 

Other EPA Comment Codes and Descriptions: 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Rule Provision: 146.93(a)(2) 

(iii) A description of post-injection monitoring location, methods, and proposed 

frequency; and 

(iv) A proposed schedule for submitting post-injection site care monitoring 

results to the Director. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: EPA Proposal: (3) Upon cessation of injection, owners or operators of Class VI 

wells must either submit an amended post-injection site care and site closure 

plan or demonstrate to the Director through monitoring data and modeling results 

that no amendment to the plan is needed. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24941

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24942

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24943

597
GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision. 

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking comment) 

(40 CFR 146.93) 

Comment: EPA Proposal: (4) The owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval within 30 

days of such change. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision. 

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment); 5280 2.8.2.4 USDW non-endangerment demonstrations 

Comment: Rule Provision: 146.93(b) 

EPA Proposal: (b) The owner or operator shall monitor the site following the 

cessation of injection to show the position of the carbon dioxide plume and 

pressure front and demonstrate that USDWs are not being endangered. 

(1) The owner or operator shall continue to conduct monitoring as specified in 

the Director-approved post-injection site care and site closure plan for at 

least 50 years following the cessation of injection. At the Director’s 

discretion, the monitoring will continue until the geologic sequestration 

project no longer poses an endangerment to USDWs. 

GWPC Recommendations: (b) The owner or operator shall monitor the site following 

the cessation of injection. 

(1) The owner or operator shall continue to conduct monitoring as specified in 

the Director-approved post-injection site care and site closure plan until 

closure is authorized pursuant to 146.93(b)(3). 

Rationale: Eliminate the 50 year requirement. 

There is no justification for extending completed projects for the presumptive 

50 years, and it will be difficult to accept much shorter demonstration periods 

with the 50 year presumption in the regulations. Default 50-year period defeats 

incentives for best site identification and best MMV 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24944

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24945

598
Need for site-specific considerations and use of data 

Need achievable and definable standard 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50 

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this 

reason, the final GS regulation includes a provision that the Director may, at his or her discretion, 

shorten the post-injection site care timeframe if the owner or operator can demonstrate that the GS 

project does not pose an endangerment to USDWs, as specified in §146.93(b)(2). Such a demonstration 

will be site-specific, and based on pressure monitoring and USDW impacts. Alternatively, the final rule 

at §146.93(c), also allows the Director to approve an alternative post-injection site care timeframe where 

an owner or operator can demonstrate during the permitting process that an alternative post-injection site 

care timeframe, other than the 50 year default, is appropriate and ensures non-endangerment of USDWs. 

The demonstration must be based on site-specific information, including the results of site-specific 

computational modeling; the predicted timeframe for pressure decline; the predicted rate of carbon 

dioxide plume migration; site-specific chemical processes that will result in carbon dioxide trapping; the 

predicted rate of carbon dioxide trapping; characterization of the confining zone(s); laboratory analyses 

or studies to verify the information on trapping; the presence of potential conduits for fluid movement 

and the quality of abandoned well plugs within the AoR; the distance between the injection zone and the 

USDWs above and/or below the injection zone; and any additional site-specific factors determined by 

the Director. The demonstration must meet the criteria at §146.93(c)(2) for ensuring the quality and 

accuracy of the data and models on which the demonstration is based. This demonstration would be 

submitted as part of the permit application, per §146.82(a)(18), in addition to the PISC and site closure 

plan required at §146.82(a)(17). 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for 

post-injection site care will be necessary in all but a limited number of cases. This default 50 year postinjection site care timeframe represents a reasonable and protective monitoring period based on a review 

of research studies, industry reports, and existing environmental programs, and evaluation of public 

comments. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment); 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b) 

EPA Proposal: (2) If the owner or operator can demonstrate to the satisfaction 

of the Director before 50 years, based on monitoring and other site-specific 

data, that the geologic sequestration project no longer poses an endangerment to 

USDWs, the Director may approve an amendment to the post-injection site care and 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24946

599
site closure plan to reduce the frequency of monitoring or may authorize site 

closure before the end of the 50-year period. 

GWPC Recommendations: (2) The owner or operator can request and demonstrate to 

the satisfaction of the Director that the post-injection site care and site 

closure plan should be revised to reduce the frequency of monitoring. 

Rationale: See above regarding elimination of 50-year presumptive time period. 

Response: As described above, EPA disagrees that a post-injection site care timeframe of 50 years is 

excessive for most Class VI wells. However, EPA agrees that there will be circumstances where it can 

be demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of 

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility regarding 

the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the 

PISC timeframe during the post-injection period based on site-specific data, pursuant to requirements at 

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to 

demonstrate, during the permitting process based on substantial data, that an alternative PISC timeframe 

may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

Other EPA Comment Codes and Descriptions: 5280 2.8.2.4 USDW non-endangerment 

demonstrations 

Comment: EPA Proposal: (3) Prior to authorization for site closure, the owner or operator 

must submit to the Director a demonstration, based on monitoring and other sitespecific data, that the carbon dioxide plume and pressure front have stabilized 

and that no additional monitoring is needed to assure that the geologic 

sequestration project does not pose an endangerment to USDWs. 

GWPC Recommendations: (3) Prior to authorization for site closure, the owner or 

operator must demonstrate to the Director, based on monitoring, other sitespecific data, and modeling that is reasonably consistent with site performance, 

that no additional monitoring is needed to assure that the geologic 

sequestration project does not and is not expected to pose an endangerment to 

USDWs. The Director shall approve closure if the owner or operator demonstrates, 

based on the current understanding of the site, including monitoring data and/or 

modeling, all of the following: (i) the estimated magnitude and extent of the 

project footprint (CO2 plume and the area of elevated pressure) ; (ii) the 

estimated location of the detectable CO2 plume; (iii) that there is no 

significant leakage of either CO2 or displaced formation fluids that is 

endangering USDWs; (iv) that the injected or displaced fluids are not expected 

to migrate in the future in a manner that encounters a potential leakage pathway 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24947

600
into a USDW; (v) that the injection wells at the site completed into or through 

the injection zone or confining zone are plugged and abandoned in accordance 

with these requirements; and (vi) any remaining project monitoring wells at the 

site are being managed by a person and in a manner acceptable to the Director. 

Rationale: The GWPC revised this section to establish the performance based 

criteria for selecting the monitoring period. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring timeframe. 

Instead, EPA believes that such determinations are site-specific and should be described in a project 

specific post-injection site care and site closure plan. EPA also believes that periodic reviews and 

updates, where necessary, to the plan are important to ensuring that the site continues to be managed 

effectively and to determine whether shortening the monitoring timeframe is appropriate. 

As described above, EPA agrees that there will be circumstances where it can be demonstrated in less 

than 50 years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For 

this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC 

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the 

post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording 

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the permitting 

process based on substantial data, that an alternative PISC timeframe may be appropriate if it ensures 

non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment); 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: EPA Proposal: (4) If such a demonstration cannot be made (i.e., if the carbon 

dioxide plume and pressure front have not stabilized) after the 50-year period, 

the owner or operator must submit to the Director a plan to continue postinjection site care. 

GWPC Recommendations: Delete 

Rationale: No longer necessary if 50 year time period is removed. 

Response: As described above, EPA believes that, to ensure USDW protection from endangerment, a 

default timeframe for post-injection site care is necessary in most cases. A 50 year post-injection site 

care timeframe represents a reasonable and protective monitoring period for most GS sites based on a 

review of research studies, industry reports, and existing environmental programs, and evaluation of 

public comments. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24948

601
EPA believes that a 50-year default post-injection site care timeframe, as required at §146.93(b)(1), is 

not overly burdensome, does not exaggerate the risks associated with GS, is consistent with other 

environmental programs, and sufficiently protects USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Rule Provision: 146.93(c) 

EPA Proposal: (c) Notice of intent for site closure. The owner or operator must 

notify the Director at least 120 days before site closure. At this time, if any 

changes have been made to the original post-injection site care and site closure 

plan, the owner or operator must also provide the revised plan. At the 

discretion of the Director, a shorter notice period may be allowed. 

GWPC Recommendations: No recommendation 

Rationale: Need for site-specific considerations and use of data 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Rule Provision: 146.93(d) 

EPA Proposal: (d) After the Director has authorized site closure, the owner or 

operator must plug all monitoring wells in a manner which will not allow 

movement of injection or formation fluids that endangers a USDW. 

GWPC Recommendations: No recommendation 

Rationale: Need for site-specific considerations and use of data 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: EPA Proposal: (e) Once the Director has authorized site closure, the owner or 

operator must submit a site closure report within 90 days that must thereafter 

be retained at a location designated by the Director. The report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in § 146.92 and paragraph (c) of this section. The owner or operator 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24949

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24950

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24951

602
must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the 

location of the injection well relative to permanently surveyed benchmarks. The 

owner or operator must also submit a copy of the plat to the Regional 

Administrator of the appropriate EPA Regional Office; 

GWPC Recommendations: (e) Once the Director has authorized site closure, the 

owner or operator must submit a site closure report within 90 days after 

completion of all closure operations. The report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the location 

of the injection well(s) relative to permanently surveyed benchmarks. The owner 

or operator must also submit a copy of the plat to the Regional Administrator of 

the appropriate EPA Regional Office; 

Rationale: What is the retention period? Many other programs have a three year 

limit for retention of records. EPA is the steward of information at this point 

of the project, not the owner or operator. 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on the 

deed to the facility property or other similar document examined during a title search that the land has 

been used to sequester CO2 on the deed to the facility property at the time of site closure. 

Regarding record retention, EPA has clarified the recordkeeping requirements in the final GS rule, 

which includes requirements that well plugging reports, as required at §146.92(d), post-injection site 

care data, as required at §146.93(f), and site closure reports, as required at §146.93(h), must be kept by 

the owner or operator for ten years after site closure. EPA believes that longer record retention times for 

GS wells are appropriate and necessary for the post-injection and site closure period to ensure that data 

are available to support non-endangerment demonstrations and to address any concerns that may arise 

following site closure. This data will also support EPA's review of project data as part of the adaptive 

rulemaking approach. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: EPA Proposal: (2) Documentation of appropriate notification and information to 

such State, local and tribal authorities as have authority over drilling 

activities to enable such State and local authorities to impose appropriate 

conditions on subsequent drilling activities that may penetrate the injection 

and confining zone(s); and 

(3) Records reflecting the nature, composition and volume of the carbon dioxide 

stream. 

GWPC Recommendations: No recommendation 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24952

603
Rationale: Need for site-specific considerations and use of data 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on the 

deed to the facility property or other similar document examined during a title search that the land has 

been used to sequester CO2 on the deed to the facility property at the time of site closure. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Rule Provision: 146.93 

EPA Proposal: (f) Each owner or operator of a Class VI injection well must 

record a notation on the deed to the facility property or any other document 

that is normally examined during title search that will in perpetuity provide 

any potential purchaser of the property the following information: 

(1) The fact that land has been used to sequester carbon dioxide; 

(2) The name of the State agency, local authority, and/or tribe with which the 

survey plat was filed, as well as the address of the Regional Environmental 

Protection Agency Office to which it was submitted; and 

GWPC Recommendations: No recommendation 

Rationale: Need for site-specific considerations and use of data 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on the 

deed to the facility property or other similar document examined during a title search that the land has 

been used to sequester CO2 on the deed to the facility property at the time of site closure. 

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and 

post-injection site care; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: EPA Proposal: (3) The volume of fluid injected, the injection zone or zones into 

which it was injected, and the period over which injection occurred. 

(g) The owner or operator must retain for three years following site closure, 

records collected during the post-injection site care period. The owner or 

operator must deliver the records to the Director at the conclusion of the 

retention period, and the records must thereafter be retained at a location 

designated by the Director for that purpose. 

GWPC Recommendations: No recommendation 

Rationale: Need for site-specific considerations and use of data 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on the 

deed to the facility property or other similar document examined during a title search that the land has 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24953

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24954

604
been used to sequester CO2 on the deed to the facility property at the time of site closure. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: Rule Provision: 146.94(b) 

(b) If the owner or operator obtains evidence that the injected carbon dioxide 

stream and associated pressure front may cause an endangerment to a USDW, the 

owner or operator must: 

(1) Immediately cease injection; 

(2) Take all steps reasonably necessary to identify and characterize any 

release; 

(3) Notify the Director within 24 hours; and 

(4) Implement the emergency and remedial response plan approved by the Director. 

GWPC Recommendations: (b) If the owner or operator obtains evidence that the 

injected carbon dioxide stream, displaced formation fluids or associated 

pressure front endangers a USDW, the owner or operator must: 

(1) Immediately cease injection; 

(2) Take all steps reasonably necessary to identify and characterize the 

endangerment posed; 

(3) Notify the Director or the designated representative within 24 hours of 

becoming aware of the endangerment; and 

(4) Implement the emergency and remedial response plan approved by the Director. 

Rationale: The GWPC felt the notification period needed clarification since it 

did not specify when the clock began to run for the 24 hour notice period. 

Further, it was felt that notification of someone representing the Director 

would also constitute appropriate notice. 

Response: After consideration of comments, EPA has finalized the rule language in §146.94(b) as 

proposed. In the introductory section of §146.94(b), EPA clarifies that the pressure front, as defined in 

§146.81, is a zone where the pressure differential is sufficient to cause the movement of injected fluids 

or formation fluids into a USDW. Therefore, displaced formation fluids are implicitly included in the 

requirements for §146.94. EPA also clarifies that owners or operators must take action when the CO2 

stream or pressure front may cause endangerment. In order to prevent the endangerment of USDWs, as 

required under §1421 of the SDWA, EPA expects the owner or operator to act preemptively and not 

wait until endangerment has occurred. This language is consistent with existing UIC requirements for 

other well classes and EPA’s authority under the SDWA. 

Regarding changes to the language in §146.94(b)(1), EPA clarifies that the Agency expects that owners 

or operators take care not to damage the well when ceasing injection under §146.94(b)(1). At §146.94(b)

(2), EPA is maintaining the requirement to “characterize the release.” In order to prevent the 

endangerment of USDWs, as required under §1421 of the SDWA, EPA expects the owner or operator to 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24956

605
act preemptively and not wait until endangerment has occurred. This language is consistent with existing 

UIC requirements for other well classes and EPA’s authority under the SDWA. 

Concerning commenters’ suggestions for §146.94(b)(3), EPA clarifies that the 24 hours begins when the 

owner or operator obtains evidence of possible endangerment. Note that the definition of the Director in 

40 CFR 144.3 includes the Director’s authorized representative. EPA believes the rule language is clear 

on this requirement. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: EPA Proposal: (c) The Director may allow the operator to resume injection prior 

to remediation if the owner or operator demonstrates that the injection 

operation will not endanger USDWs. 

(d) The owner or operator must notify the Director and obtain his approval prior 

to conducting any well workover. 

GWPC Recommendations: Support the proposed EPA language for (c) 

(d) The owner or operator must notify the Director prior to conducting any well 

workover in response to any case of endangerment. 

Rationale: In critical situations, time spent obtaining approval could adversely 

affect the ability to conduct operations or increase the level of endangerment. 

Response: Since proposal, EPA has modified the final regulatory language at §146.94(d) to clarify what 

constitutes a workover to address a well failure (which invokes remedial actions) and what constitutes a 

maintenance-type workover. For maintenance-type workovers (i.e., those that are scheduled in advance), 

the owner or operator must notify and gain approval from the Director prior to beginning the workover. 

In the final GS regulation, EPA has moved this requirement to the reporting requirements at §146.91(d) 

to clarify its intent. 

Regarding concerns that notification could delay responses, EPA clarifies that the GS rule, at §146.94

(b), describes procedures owners or operators must take in emergency situations. Specifically, upon 

determining that there is a problem with the well that may endanger a USDW, the owner or operator 

must first cease injection, then take all steps reasonably necessary to identify and characterize any 

release, notify the Director, and implement the approved emergency and remedial response plan, which 

may include a well workover. EPA believes that ceasing injection (which the owner or operator would 

do immediately and before notifying the Director) is the action necessary to prevent or mitigate 

endangerment of USDWs as required under the SDWA. 

Comment: Rule Provision: 146.81 Applicability. 

EPA Proposal: (a) This subpart establishes criteria and standards for 

underground injection control programs to regulate Class VI carbon dioxide 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24957

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24965

606
geologic sequestration injection wells. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87 

EPA Proposal: 7. Logging, sampling, and testing prior to injection well 

operation 

(a) During the drilling and construction of a Class VI injection well, the owner 

or operator must run appropriate logs, surveys and tests to determine or verify 

the depth, thickness, porosity, permeability, and lithology of, and the salinity 

of any formation fluids in, all relevant geologic formations to assure 

conformance with the injection well construction requirements under § 146.86, 

and to establish accurate baseline data against which future measurements may be 

compared. The owner or operator must submit to the Director a descriptive 

report prepared by a knowledgeable log analyst that includes an interpretation 

of the results of such logs and tests. At a minimum, such logs and tests must 

include: 

GWPC Recommendations: (a) During the drilling and construction of a Class VI 

injection well, the owner or operator must run appropriate logs, surveys and 

tests to determine or verify the depth, thickness, porosity, permeability, and 

lithology of, and the salinity of any formation fluids in, all relevant geologic 

formations to assure conformance with the injection well construction 

requirements under §146.86, and to establish accurate baseline data against 

which future measurements may be compared. The owner or operator must submit to 

the Director a descriptive report prepared by a knowledgeable log analyst that 

includes an interpretation of the results of such logs and tests. The Director 

may require such logs and tests as may be needed after taking into account the 

availability of similar data in the area of the drilling site, the construction 

plan, and the need for additional information that may arise from time to time 

as the construction of the well progresses and these may include the following: 

Rationale: In well defined areas, these evaluations are frequently unnecessary. 

The director should have discretion to select the appropriate requirements 

necessary to ensure sufficient baseline data and information are available. For 

example, in an area where a number of wells are being drilled, the logging of 

surface hole yields little useful additional information. 

In particular, this change would allow the Director to reduce the requirements 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29176

607
when multiple wells are installed for a project. 

Response: EPA believes that the logging and testing requirements in the GS rule are appropriate and 

necessary. The requirements at §146.87 stem from existing knowledge and practices in place for other 

injection well classes and within the oil and gas industry, and are tailored to the special characteristics of 

CO2 injection for GS. 

EPA is developing guidance on monitoring and testing that will describe recommended tests and 

procedures to assist owners/operators and Directors in evaluating the requirements for pre-operational 

logging and testing under §146.87. This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA clarifies that §146.87(b) provides some flexibility. EPA notes that §146.87(b) allows information 

on cores from nearby wells to be submitted if the owner or operator can demonstrate that core retrieval 

is not possible and that cores from nearby wells are representative of conditions at the GS well. EPA 

clarifies that, at a minimum, reports on cores of injection zones and confining zones, and samples of 

formation fluids must be submitted. Section 146.87(b) gives the Director authority to require the owner 

or operator to core other formations in the borehole if necessary to provide sufficient geologic 

information to verify that the site is suitable for GS. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: EPA Proposal: (1) Deviation checks during drilling on all holes constructed by 

drilling a pilot hole which are enlarged by reaming or another method. Such 

checks must be at sufficiently frequent intervals to determine the location of 

the borehole and to assure that vertical avenues for fluid movement in the form 

of diverging holes are not created during drilling; and 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment; the final rule retains the requirements for deviation checks 

required at §146.87(a)(1). EPA adds that the Director would have discretion to approve a plan without 

deviation checks that addresses circumstances where these tests may not be practical or useful, such as 

those mentioned by the commenter. EPA encourages owners or operators to discuss these situations with 

the Director when planning the deviation testing. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(a) 

EPA Proposal: (2) Before and upon installation of the surface casing: 

GWPC Recommendations: Support the proposed EPA language. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29177

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29178

608
Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment; the final rule retains the requirements for logging and 

testing prior to and upon installation of surface casing. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: EPA Proposal: (i) Resistivity, spontaneous potential, and caliper logs before 

the casing is installed; and 

GWPC Recommendations: (i) Resistivity, spontaneous potential, and caliper logs 

before the casing is installed; and 

Rationale: After a few wells are drilled in an area, these evaluations are 

frequently unnecessary and yield little new information.This is an example of 

why it is appropriate to make this a discretionary rather than mandatory 

requirement. The proposed revision to 146.87(a) would give the Director the 

necessary discretion. 

Response: EPA disagrees that the requirements for logs, surveys, and tests are excessive or duplicative. 

All logs, surveys, and tests listed at §146.87(a) are necessary to verify information about the injection 

and confining zones and ensure that the well is being drilled and cased as approved, and has mechanical 

integrity. EPA notes that the Director has the discretion at §146.87(a)(5) to approve alternative methods 

that provide equivalent or better information. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: EPA Proposal: (ii) A cement bond and variable density log, and a temperature log 

after the casing is set and cemented. 

GWPC Recommendations: (ii) A cement bond and variable density log, and a 

temperature log after the casing is set and cemented. 

Rationale: Unusual to run these logs in a surface hole due to uniformity of 

shallow geology. This is an example of why it is appropriate to make this a 

discretionary rather than mandatory requirement. The proposed revision to 

146.87(a) would give the Director the necessary discretion. 

Response: As described above, EPA disagrees that the requirements for logs, surveys, and tests are 

excessive or duplicative. All logs, surveys, and tests listed at §146.87(a) are necessary to verify 

information about the injection and confining zones and ensure that the well is being drilled and cased as 

approved, and has mechanical integrity. EPA notes that the Director has the discretion at §146.87(a)(5) 

to approve alternative methods that provide equivalent or better information. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29179

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29180

609
EPA clarifies that in the final GS rule, §146.87(a)(2)(ii) reads as follows: "A cement bond and variable 

density log to evaluate cement quality radially, and a temperature log after the casing is set and 

cemented." 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: EPA Proposal: (3) Before and upon installation of the long string casing: 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment; the final rule retains the requirements for logging and 

testing prior to and upon installation of the long string casing. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: EPA Proposal: (i) Resistivity, spontaneous potential, porosity, caliper, gamma 

ray, fracture finder logs, and any other logs the Director requires for the 

given geology before the casing is installed; and 

GWPC Recommendations: Support the proposed EPA language. 

Response: EPA acknowledges the comment; the final rule retains the requirements for the logs and tests 

required at §146.87(a)(3). 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: EPA Proposal: (ii) A cement bond and variable density log, and a temperature log 

after the casing is set and cemented. 

GWPC Recommendations: (ii) Cement evaluation logs after the casing is set and 

cemented to evaluate cement quality with sufficient radial resolution to 

identify channels or missing cement. 

Rationale: Acceptable to specify basic logging requirements, however, special 

logs should not be specified. Any other information from the area should be 

drawn on. Provides more flexibility to select the appropriate log to demonstrate 

adequate cement bond. 

Response: EPA agrees with the suggested change. In the final GS rule, §146.87(a)(2)(ii) reads as 

follows: "A cement bond and variable density log to evaluate cement quality radially, and a temperature 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29181

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29182

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29183

610
log after the casing is set and cemented."

EPA believes that a minimum suite of logs and tests is necessary at all GS wells. All logs, surveys, and 

tests listed at §146.87(a) are necessary to verify information about the injection and confining zones and 

ensure that the well is being drilled and cased as approved and has mechanical integrity. EPA adds that, 

should alternative methods be shown to provide equivalent or better information or if site-specific 

conditions and risk factors dictate that other logs are necessary, the Director has the discretion at 

§146.87(a)(5) to require further logs and tests if necessary and to approve alternative methods that 

provide equivalent or better information. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: EPA Proposal: 146.87(a)(4) 

(4) A series of tests designed to demonstrate the internal and external 

mechanical integrity of injection wells, which may include: 

(i) A pressure test with liquid or gas; 

(ii) A tracer survey such as oxygen-activation logging; 

(iii) A temperature or noise log; 

(iv) A casing inspection log, if required by the Director; and 

(5) Any alternative methods that provide equivalent or better information and 

that are required of and/or approved of by the Director. 

GWPC Recommendations: (4) Test(s) designed to demonstrate the internal and 

external mechanical integrity of injection wells, which may include: 

(i) A pressure test with liquid or gas; 

(ii) Diagnostic tools such as oxygen-activation logging; 

(iii) A temperature or noise log; and 

(iv) A casing inspection log. 

(5) Accept the EPA language and numbering. 

Rationale: Technical and grammatical corrections 

In (iv), "if required by the Director" is unnecessary. 

We interpret that (5) applies to 146.87(a) 

Response: EPA agrees with the commenter about the wording of the casing inspection log requirement 

at §146.87(a)(4) and made the suggested change to improve clarity. In the final regulation, §146.87(a)(4)

(iv) does not include the phrase, “if required by the Director.” 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29184

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29185

611
Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule provision: 146.87(b) 

EPA Proposal: (b) The owner or operator must take and submit to the Director 

whole cores or sidewall cores of the injection zone and confining system and 

formation fluid samples from the injection zone(s). The Director may accept 

cores from nearby wells if the owner or operator can demonstrate that core 

retrieval is not possible and that such cores are representative of conditions 

at the well. The Director may require the owner or operator to core other 

formations in the borehole. 

GWPC Recommendations: (b) The owner or operator must submit to the Director a 

report describing whole cores or sidewall cores representative of the injection 

zone and confining system and formation fluid samples from the injection 

zone(s). The Director may accept data from cores and fluid samples from nearby 

wells if the owner or operator can demonstrate that such data are representative 

of conditions in the wellbore. 

Rationale: The information required should be sufficient to properly describe 

the injection and confining zones. 

Response: EPA clarifies that it is not the Agency's intent that physical cores be submitted to the 

Director. In the final GS rule, EPA has revised the first sentence of §146.87(b) to read as follows: "The 

owner or operator must take whole cores or sidewall cores of the injection zone and confining system 

and formation fluid samples from the injection zone(s), and must submit to the Director a detailed report 

prepared by a log analyst that includes: well log analyses (including well logs), core analyses, and 

formation fluid sample information...." 

EPA believes that logs and tests must be performed on each well drilled regardless of existing 

information about the area to account for the complexity of CO2 injection well construction and the 

buoyancy of CO2. Existing lithologic and geologic information may lack the details needed for sitespecific well design and the geology needed to support protection of USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: EPA Proposal: (c) The owner or operator must record the fluid temperature, pH, 

conductivity, reservoir pressure and the static fluid level of the injection 

zone(s). 

GWPC Recommendations: (c) Prior to injection well operation, the owner or 

operator must record the formation temperature, formation fluid pH and 

conductivity, and reservoir pressure of the injection zone(s). 

Rationale: Technical corrections. Reservoir pressure and static fluid level are 

redundant parameters. 

Response: EPA disagrees that "reservoir pressure" and "static fluid level" are redundant parameters. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29186

612
Although the static fluid level is equal to the bottom hole pressure, this may not always be identical to 

the reservoir pressure. Additionally, measuring the static fluid level provides additional assurance that 

the reading is accurate (or, provides the needed information in cases where a good reading is not 

obtained). In addition, a static fluid level measurement provides information regarding the proximity to 

USDWs that need protection afforded to them. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: EPA Proposal: (d) At a minimum, the owner or operator must determine or 

calculate the following information concerning the injection and confining 

zone(s): 

(1) Fracture pressure; 

(2) Other physical and chemical characteristics of the injection and confining 

zones; and 

(3) Physical and chemical characteristics of the formation fluids in the 

injection zone. 

GWPC Recommendations: Delete all 

Rationale: With the exception of calculating fracture pressure, the requirements 

of this section appear redundant to other requirements of prior sections. 

Recommend moving injection pressure to old (e), now renumbered as (d). 

(2) and (3) are also too vague. 

Response: EPA believes that the requirement to provide information on the injection and confining 

zones in §146.87(d) is warranted, and that the rule provides flexibility to account for the variety of 

geologic conditions that may be encountered at GS sites. 

EPA is developing guidance on monitoring and testing that will describe recommended tests and 

procedures to assist owners/operators and Directors in evaluating the requirements for pre-operational 

logging and testing under §146.87. This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: EPA Proposal: (e) Upon completion, but prior to operation, the owner or operator 

must conduct the following tests to verify hydrogeologic characteristics of the 

injection zone: 

(1) A pump test; or 

(2) Injectivity tests. 

GWPC Recommendations: (d) At any time prior to injection well operation, the 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29187

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29188

613
owner or operator must determine fracture pressures of the injection and 

confining zones and conduct tests to verify hydrogeologic and geomechanical 

characteristics of the injection zone, e.g., injectivity tests. 

Rationale: Allows the use of information such as leak off tests conducted during 

the drilling operation. 

Delete (1) 

It was felt that Geomechanical properties were at least as important as 

hydrogeologic characteristics. 

The results of a pump test (pumping fluid from the well) has no relevance for an 

injection well. 

If current (d) is deleted as recommended, this would become (d) 

Response: EPA clarifies that the owner or operator has the option of using pump tests or injectivity tests 

depending on which would provide the most valuable information based on site-specific conditions. 

Further, EPA disagrees that pump tests are irrelevant to determining injection zone properties. 

Depending on the characteristics or depth of knowledge of the confining and injection zone formations, 

pump tests may be necessary to prove that no hydraulic connection exists between the injection zone and 

a USDW. 

EPA is developing guidance on monitoring and testing that will describe recommended tests and 

procedures to assist owners/operators and Directors in evaluating the requirements for pre-operational 

logging and testing under §146.87. This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3866 2.3.3.3 Logging and testing requirements (40 

CFR 146.87) 

Comment: Rule Provision: 146.87(f) 

EPA Proposal: (f) The owner or operator must provide the Director with the 

opportunity to witness all logging and testing by this subpart. The owner or 

operator must submit a schedule of such activities to the Director 30 days prior 

to conducting the first test and submit any changes to the schedule 30 days 

prior to the next scheduled test. 

GWPC Recommendations: (e) The owner or operator must provide the Director with 

the opportunity to witness all logging and testing by this subpart. The owner or 

operator must submit a schedule of such activities to the Director upon spudding 

the well and submit any changes to the schedule 48 hours prior to the scheduled 

test. 

Rationale: The changes reflect the realities of flexible rig schedules and are 

fully consistent with current Class II requirements and practices. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 29189

614
If current (d) is deleted as recommended, this would become (e) 

Response: EPA disagrees that the 30-day notification requirement is unreasonable. The 30-day 

notification mirrors the current requirement for logging and testing of new Class I wells, as described in 

§146.66. Acknowledging the developing nature of CO2 GS, EPA believes that involvement by the 

permitting authority in each project will provide much needed field data for assurance of USDW 

protection from endangerment and will help update and refine the permitting process. Adequate timing 

of notification will ensure the Director's ability to be involved. 

Other EPA Comment Codes and Descriptions: 4110 2.4.1.1 Injection pressure limitations 

Comment: C. Pressure management 

[FR p. 43538, §146.88(a)] EPA has proposed to adopt an injection pressure limit 

equal to 90 percent of the fracture pressure in the injection zone. This is a 

high number, and there will be cases where it is prudent to lower limits. Since 

injection is likely to take place in diverse geologic settings, we believe that 

those limits should be calculated individually, taking into account a number of 

geologic factors each time, which we attempt to incorporate in the proposed 

language below. Nonetheless, we believe that EPA should maintain a maximum upper 

limit (equal to or less than 90 percent of the fracture pressure in the 

injection zone), so as to avoid cases where studies might appear to support 

higher limits that would not be advisable. We also consider the "Except during 

stimulation" qualifier as confusing and creating a loophole and we urge that it 

be removed. Finally, the pressure limits themselves should refer to the 

confining zone and not the injection zone. We offer the following language as a 

starting point: 

"The owner or operator must ensure that injection pressure does not exceed [90] 

percent of the fracture pressure of the confining zone. The owner or operator 

must comply with a maximum injection pressure limit approved by the Director and 

specified in the permit. In approving a maximum injection pressure limit, the 

Director must consider the results of well tests and, where appropriate 

geomechanical or other studies, that assess the risks of tensile failure and 

shear failure. Limits shall be calculated so as to assure that pressure will 

avoid initiation or propagation of fractures in the confining zone or cause 

otherwise non-transmissive faults transecting the confining zone to become 

transmissible. In no case may injection pressure cause movement of injection or 

formation fluids that endangers a USDW." 

The maximum upper limit should not be used as a default in place of tests and 

studies that should be used to establish appropriate limits for specific sites - 

we urge EPA to ensure that this is built into the rule language. The 

consideration of both tensile and shear failure is necessary in carrying out a 

rigorous evaluation, in our view, as is the requirement not to cause otherwise 

non-transmissive faults transecting the confining zone to become transmissible. 

We also urge EPA to compile a list of quality criteria against which the results 

of the mentioned tests and studies will be evaluated - these need to be 

transparent and capable of screening adequate tests from inadequate ones. 

Commenter Name: David Hawkins Letter ID: 0272

Commenter Organization: Natural Resources Defense Council Comment ID: 24078

615
Pressure limits should also ensure that no significant risks from seismicity are 

posed, and EPA should incorporate appropriate language in the setting of 

pressure limits. 

We further believe that the established phrasing "so as to assure that", used in 

Class II, is preferable to other formulations such as "with a reasonable degree 

of certainty". We also believe that the proposed rule’s language on movement of 

fluids "that endangers a USDW" is more protective and preferable to the wording 

"into a USDW", and preferable to references to §144.12(a). As mentioned above, 

the rule should be drafted to assure no releases to the atmosphere as well. 

Response: EPA disagrees with the suggestion that injection pressure be set at less than 90 percent of 

fracture pressure. EPA believes that a lower pressure limitation may not allow for sufficient volumes of 

CO2 to be transmitted away from the well and into the injection formation. EPA acknowledges that 

there may be circumstances where a lower pressure limitation may be appropriate; in such cases, the 

Director has the authority, at §146.88, to set a lower pressure limit in the operating permit. EPA believes 

that the 90 percent requirement allows the consideration of site-specific circumstances and provides a 

satisfactory margin of safety during well operation. 

EPA clarifies that injection pressure limit for each GS project will be based on site-specific conditions, 

and be informed by data on the injection and confining zones. During injection, the pressure in the 

injection zone must not exceed 90 percent of the fracture pressure of the injection zone, as specified at 

§146.88(a). The fracture pressure (and, therefore, the injection pressure) are based on site-specific 

geologic and geomechanical data collected during the site characterization process required at §146.82. 

Tests are available and have been used by injection well operators, e.g., Class I operators, to measure 

fracture pressure. Examples include the step-rate test, in-situ stress tests, and a combination of a long 

spaced sonic log with laboratory measurement of the mechanical properties of cores. To meet the GS 

requirements, the permitting authority must set the injection pressure limit at 90 percent of this value. 

The Director will review geologic, hydrogeologic, and geomechanical information submitted by the 

owner or operator in setting permit conditions. If, based on this information, a lower pressure limitation 

is appropriate, the Director has the authority to set a lower limit in the operating permit. EPA clarifies 

that fracturing of the confining zone during injection and/or stimulation is also prohibited at §146.88(a).

The final rule provides for the use of stimulation. EPA believes that stimulation is important for 

enhancing formation injectivity, provided it is performed in a manner that maintains the integrity of the 

confining zone. All stimulation must be approved by the Director. Owners or operators must submit a 

proposed stimulation program as part of the permit application under §146.82(a)(9); the plan must 

demonstrate that any stimulation activities will not compromise the integrity of the confining zone. The 

Director will evaluate the owner or operator's proposed stimulation plan in the context of all information 

about the site, and the owner or operator must perform stimulation only as approved. 

EPA is developing guidance on site characterization for GS projects to assist owners or operators in 

meeting the requirements of §146.82 and to assist directors in evaluating permit applications. The 

guidance will describe recommended approaches for characterizing the regional geology and 

hydrogeology of a proposed site and performing the necessary geochemical, geomechanical, and 

geophysical analyses of the injection and confining zone. EPA is also developing guidance for primacy 

agencies that will include recommended approaches for evaluating owner or operator-submitted data in 

setting permit conditions. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

616
Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment) 

Comment: D. Closure 

[FR p. 43540, §146.93(b)] EPA has proposed an arrangement whereby the operator 

continues to monitor the site for a minimum of 50 years after the cessation of 

injection, unless the operator can demonstrate to the satisfaction of the 

Director that the project no longer poses an endangerment to USDWs and that the 

CO2 plume and pressure front have stabilized. 

While 50 years is not a number that will apply in all cases and projects, we do 

believe that it is appropriate as a default at today’s level of our 

understanding and operational experience with GS. The option that operators have 

under the current proposal to obtain approval for a lower number, based on 

actual project performance, should be sufficient to deal with situations where 

50 years can be demonstrated to be unnecessarily long. Along the same lines, 

there might be situations where 50 years would not suffice, and where the 

Director should require a longer period, as per the current proposal. In 

assessing non-endangerment to USDWs and plume/pressure front stabilization, we 

believe that the EPA should be far more specific in its requirements. We offer 

the following language as a suggested revision to §146.93(b): 

"(b) The owner or operator shall monitor the site following the cessation of 

injection. 

(1) The owner or operator shall continue to conduct monitoring as specified in 

the Director-approved post-injection site care and site closure plan for at 

least 50 years following the cessation of injection or until closure is 

authorized. 

(2)If the owner or operator can demonstrate to the satisfaction of the Director 

before 50 years, based on/pursuant to the criteria in (b), that the geologic 

sequestration project does not and is not expected to pose an endangerment to 

USDWs or result in releases to the atmosphere, the Director may approve an 

amendment to the post-injection site care and site closure plan to reduce the 

frequency of monitoring or may authorize site closure before the end of the 50- 

year period. 

(3) Prior to authorization for site closure, the owner or operator must 

demonstrate to the Director, based on monitoring, other site-specific data, and 

modeling that is consistent with site performance, that no additional monitoring 

is needed to assure that the geologic sequestration project does not and is not 

expected to pose an endangerment to USDWs or any release to the atmosphere. The 

owner or operator must demonstrate, based on the current understanding of the 

site, including monitoring data and modeling, all of the following: (i) the 

magnitude and extent of the project footprint (CO2 plume and the area of 

elevated pressure); (ii) the location of the detectable CO2 plume; (iii) that 

there is no significant leakage of either CO2 or displaced formation fluids that 

is endangering USDWs or creating a potential release to the atmosphere; (iv) 

Commenter Name: David Hawkins Letter ID: 0272

Commenter Organization: Natural Resources Defense Council Comment ID: 24079

617
that the injected or displaced fluids are not expected to migrate in the future 

in a manner that encounters a potential leakage pathway into a USDW or to the 

atmosphere; (v) that the injection wells at the site completed into or through 

the injection zone or confining zone are plugged and abandoned in accordance 

with these requirements; and (vi) any remaining project monitoring wells at the 

site are being managed by a person and in a manner acceptable to the Director. 

(4) If such a demonstration cannot be made after the 50-year period, the owner 

or operator must submit to the Director a plan to continue post-injection site 

care." 

Response: EPA agrees that a 50 year post-injection site care timeframe represents a reasonable and 

protective post-injection site monitoring period for most projects and available data, including data 

submitted by commenters, do not support a different default timeframe. EPA bases this on a review of 

research studies, industry reports, and existing environmental programs, and evaluation of public 

comments. 

However, EPA recognizes that there may be sites where the 50 year post injection site care timeframe 

may be either not appropriate or more burdensome than necessary based on site-specific conditions. For 

this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC 

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the 

post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording 

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the permitting 

process based on substantial data, that an alternative PISC timeframe may be appropriate if it ensures 

non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for 

post-injection site care will be necessary in most cases. The default 50 year post-injection site care 

timeframe represents a reasonable and protective monitoring period based on a review of research 

studies, industry reports, and existing environmental programs, and evaluation of public comments. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

In response to comments to be more specific, EPA believes §146.93 is sufficiently specific for the 

purposes of protecting USDWs. Furthermore, the commenter’s proposed language regarding released 

CO2 emissions into the air are outside the scope of this rulemaking and EPA’s authority under the 

SDWA. 

Other EPA Comment Codes and Descriptions: 2048 1.5.2.4 Oppose Class VI/ Support Class V 

experimental technology well; 2200 1.6.4 Other formation types 

Comment: To implement this approach, sections 144.6(f), 144.80(f), 146.5(f) and the 

definition of sequestration in 146.81 should be revised. The proposed 144.15 

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25308

618
provision that the construction, operation or maintenance of any nonexperimental Class V GS well is prohibited should be retained, but only with the 

understanding that this prohibition is not intended to limit the size or scale 

of any experimental GS operation. 

"Class VI. Wells used for geologic sequestration but not including those wells 

used for geologic sequestration that are regulated under another Class. Wells 

used for geologic sequestration in basalts, coal seams, salt caverns or shales 

are regulated under Class V as experimental wells until such time as the 

Administrator establishes separate requirements by rule for the specific type of 

formation or determines, following public notice and opportunity for comment, 

that wells used for geologic sequestration of carbon dioxide streams into the 

specific type of formation should be regulated under another class." 

Response: The text at 144.15 is retained in the final regulation; the construction, operation or 

maintenance of any non-experimental Class V GS well is prohibited under the final rule. The final rule 

contains tailored requirements for Class VI wells to ensure that GS projects are permitted, sited, 

constructed, operated, and closed in a manner that protects USDWs from endangerment. 

As described above, EPA clarifies that the final GS rule does not categorically preclude injection of 

CO2 into any formation types. EPA clarifies that experimental research projects will continue to be 

regulated as Class V experimental technology wells as long as they remain of an experimental nature. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: 2. Non-interference principle 

EPA notes in the preamble (page 43506), "it is...possible that multiple owners 

or operators will be injecting CO2 into formations that are hydraulically 

connected and thus the elevated pressure zones may intersect or interfere with 

each other." We have agreed that this possibility should be addressed through a 

revision to the regulations. Until more comprehensive approaches to basin-scale 

management are developed and based on the proposed definition of "pressure 

front", we recommend the adoption of the following addition to §146.94: 

"(e) If an owner or operator obtains evidence that a pressure front associated 

with one geologic sequestration project intersects or will more likely than not 

intersect the pressure front or area of review associated with another project, 

the owner or operator obtaining such evidence must notify the Director. The 

Director shall notify the owner or operator of the other geologic sequestration 

project. If the Director determines that the pressure front associated with one 

project interferes or will more likely than not interfere with the ability of 

another project to comply with the terms of its permit(s), the Director may 

require the owners or operators of the interfering or potentially interfering 

projects to modify operations as necessary to mitigate or avoid such 

interference. Such modifications may also include modifications mutually agreed 

upon by the respective owners and operators and approved by the Director." 

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25309

619
Response: EPA agrees with the commenter that there are a variety of factors that may affect the need 

for emergency and remedial response at GS sites. The Agency believes that a site-specific emergency 

and remedial response plan that is informed by required site characterization data (per §146.82), 

modeling for AoR evaluations and reevaluations (per §146.84), and monitoring data (per §146.90) will 

appropriately address commenter concerns regarding the potential impacts of multiple GS projects. EPA 

has added a requirement at §146.94(d) that owners or operators must review their emergency and 

remedial response plan within one year of an AoR reevaluation required under 146.84 or following 

significant changes to the facility. Subsequently, the owners or operators must submit an amended plan 

or demonstrate to the Director that no amendment to the plan is needed based on the AoR reevaluation 

or any significant changes made to the facility. 

EPA also encourages owners or operators and permitting authorities to communicate planned GS 

activities during initial permitting activities to maximize coordination and minimize pressure 

interference. If a permit applicant (or the permitting authority) is aware of pending GS projects near a 

proposed well, the AoR delineation performed pursuant to 146.84 should account for the impacts of 

multiple owners and operators injecting within a single basin. EPA expects that, where multiple 

operators are involved, the Director will not approve modeling that does not account for changes that 

may result from all injection operations. 

EPA expects that changes within the AoR, such as the addition of new wells or projects that could 

potentially interfere with a GS project, would be identified as part of the AoR reevaluations required at 

§146.84(e) and would need to be addressed in a revised emergency and remedial response plan. EPA is 

developing guidance on the development and implementation of project plans for GS sites, including 

emergency and remedial response plans. 

Other EPA Comment Codes and Descriptions: 3420 2.2.2.1 Scope of the inventory process (e.g., 

reliance on publicly available information, depth of wells) 

Comment: 6. Area of review and corrective action requirements 

In proposed §144.55(a) the rule would require Class I, II (other than existing), 

III or VI permit applicants to identify the location "of all known wells within 

the injection well’s area of review which penetrate the injection zone" or, in 

the case of Class II wells operating over the fracture pressure of the injection 

formation, "all known wells within the area of review penetrating formations 

affected by the increase in pressure." 

Since injection in deep saline formations will result in an area of elevated 

pressure (above the original reservoir pressure) that will be larger than the 

CO2 plume and could conceivably affect overlying or underlying formations, we 

have agreed that the requirement for Class II wells operating above the fracture 

pressure should also apply to Class VI wells. This would help prevent the 

unwanted migration of reservoir fluids from the injection zone as a result of 

the pressure increase. We therefore recommend that §144.55(a) be revised to read 

as follows, with revisions shown in blue: 

"(a) Coverage. Applicants for Class I, II, (other than existing), or III, 

injection well permits shall identify the location of all known wells within the 

injection well's area of review which penetrate the injection zone. In the case 

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25314

620
of Class II wells that operate over the fracture pressure of the injection 

formation, applicants shall also identify the location of all known wells within 

the area of review penetrating formations affected by the increase in pressure. 

For such wells which are improperly sealed, completed, or abandoned, the 

applicant shall also submit a plan consisting of such steps or modifications as 

are necessary to prevent movement of fluid into underground sources of drinking 

water (‘‘corrective action’’). Where the plan is adequate, the Director shall 

incorporate it into the permit as a condition. Where the Director’s review of an 

application indicates that the permittee’s plan is inadequate (based on the 

factors in §146.07), the Director shall require the applicant to revise the 

plan, prescribe a plan for corrective action as a condition of the permit under 

paragraph (b) of this section, or deny the application. The Director may 

disregard the provisions of §146.06 (Area of Review) and §146.07 (Corrective 

Action) when reviewing an application to permit an existing Class II well. 

Applicants for permits for Class VI wells [or for wells in other classes that 

are used for geologic sequestration and do not meet the criteria for §144.6(b) 

(4)][FN3] shall identify the location of all known wells within the area of review 

penetrating the injection zone and all known wells within the area of review 

which penetrate formations affected by the pressure front and shall perform 

corrective action as specified in §146.84." 

3/ The undersigned, except NRDC which does not support the Group’s proposed 

bright line definition and language for §144.6(b)(4) (see MSG letter of Dec. 23, 

2008), believe that this clause in brackets should be included. 

Response: The final rule leaves §144.55 unchanged from the existing UIC requirements; i.e., Class VI 

wells are not addressed in this provision. Based on its evaluation of all public comments and input on 

the proposed rule and NODA and Request for Comment, EPA has made many revisions to the GS Rule. 

See the final rule and preamble for further discussion on EPA's final approach. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: 7. Well construction 

EPA’s proposed §146.86(b)(3) would require the long string casing to be cemented 

by circulating cement to surface in one or more stages. Yet that may be hard to 

accomplish in some cases, such as very deep wells. There are also potential 

disadvantages of this approach with regard to the weight of the cement column 

and its relation to well integrity. Sealing this annulus also eliminates an 

approach for monitoring the integrity of the cement in that critical interval 

through the primary confining interval and above. We recommend that EPA not 

make this a mandatory requirement. The requirement should also recognize that 

there may be other technologies that could be as effective as cement and 

centralizers, which may not be feasible in some applications; furthermore, 

current research and development efforts are likely to yield additional 

technologies the use of which should not be foreclosed. Accordingly, we 

recommend the following language for §146.86(b)(3): 

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25315

621
"(3) At least one long string casing, using a sufficient number of centralizers, 

which at a minimum: must be sealed from within the injection zone upward through 

the overlying confining zone, and must provide adequate isolation of the 

injection zone and other intervals as necessary for protection of USDWs using 

cement and/or other isolation techniques. The Director may approve the use of 

packers or alternative isolation techniques, provided these are demonstrated to 

be equivalent to cement or more effective to provide adequate isolation and to 

protect USDWs." 

Response: EPA does not believe that the cementing requirements at §146.86 would prevent monitoring, 

operation and remediation of Class VI wells. Cementing of deep wells has been performed successfully 

in the past by owners or operators of Class I hazardous and Class I municipal waste disposal wells. 

Some of these wells, which must meet the same cementing and casing requirements as Class VI wells, 

are up to 12,000 feet deep and have been successfully cemented in a manner that maintains integrity and 

allows for all required well testing, operation, and remediation (EPA, 2001). See the discussion of Class 

VI well construction requirements in the preamble to the final GS rule for additional information. 

Additionally, EPA is developing guidance on the construction of Class VI wells. This guidance will be 

available on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Section 146.86(b)(3) requires that the long-string casing extend to the injection zone and be cemented by 

circulating cement to the surface in one or more stages. It does not, however, specify how cementing 

should be accomplished, and gives flexibility to the owner or operator to propose alternate methods to 

provide a sufficient amount of cement to meet the standard that USDWs are protected from 

endangerment, subject to the approval of the Director. EPA notes that there are many potential ways to 

meet the requirement in deep wells, such as the use of staged cementing. 

EPA also received comments from stakeholders representing states, a water association, and industry 

supporting this provision, saying that it provides, at a reasonable cost, corrosion protection of the casing; 

prevents undesirable migration of fluids behind the casing; provides support to the casing; and provides 

multiple barriers against endangerment of USDWs. 

EPA stresses that protection of USDWs is the primary mission and mandate of the UIC program and the 

purpose of all requirements for injection wells. Any injection activity must be demonstrated to not 

endanger USDWs, regardless of their depth, and if such non-endangerment cannot be shown, then the 

activity will not be allowed under UIC requirements or the SDWA. 

EPA recognizes concerns regarding construction of Class VI wells where the lowermost USDW is very 

deep. To further address comments on deep injection wells, the final GS rule at §146.95 includes 

requirements for owners or operators that seek a waiver of the injection depth requirements. Owners or 

operators of wells operating under injection depth waivers must comply with additional construction 

requirements to ensure that wells used to inject above or between USDWs are protective. See the 

discussion of the waiver approach in the preamble to the final GS rule for additional information. 

Other EPA Comment Codes and Descriptions: 3530 2.2.3.1 AoR reevaluation frequency (seeking 

comment) 

Comment: 8. Reevaluation of the Area of Review and Revision and Maintenance of Plans 

Although the proposed §146.84(f) would require "reevaluation" of the aor at a 

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25316

622
"minimum" fixed frequency of ten years or "when operational and monitoring 

conditions warrant," the specific language of §146.84 runs the risk that 

revisions will not be made on a timely basis. We recommend imposing a continual 

obligation on operators to assess whether the aor itself, the aor and corrective 

action plan and all other plans required by the regulations should be revised, 

requiring an annual certification stating that the owner or operator has 

reviewed the circumstances (including operating and monitoring data) during the 

preceding year to determine whether these circumstances warranted a revision of 

the aor and any plans, and requiring that revisions be done when required by the 

director as well as when the operator determines that conditions warrant. To 

accomplish this, it is useful to break down the concept of "reevaluation" into 

two ideas - "assessment" of the need to revise the aor and all plans and the 

actual process of "revision." we believe that these suggestions will result in 

increased accuracy and reliability in the site performance data while avoiding 

work that is not warranted by the site data and site performance. Moreover, a 

continuous obligation to assess whether revisions are needed, when coupled with 

an annual certification requirement (see proposed §146.91(d) below) will create 

a clear accountability trail for both operator and director in case of disputes. 

Given this annual certification process, we believe it is unnecessary to require 

a reevaluation on a fixed basis every 10 years in every case. 

An annual certification requirement can also be used to enhance the ability of 

both Director and operators to keep track of which plans require updating and 

whether or not plans that ought to be updated have in fact been revised. Such a 

shared understanding is essential if there is to be the "ongoing dialogue" 

between regulators and operators that EPA anticipates. We considered the 

inclusion of an annual report as described in the preamble at 73 Fed. Reg. 

43518, but concluded that the benefits of that particular report would be 

outweighed by the burden. The annual certification we are recommending would be 

uch simpler. We recommend: 

That §146.84(f) be revised to read as follows: 

"(f) (1) Notwithstanding the requirement in paragraph (2)(i) of this subsection 

to perform a reevaluation of the area of review at the frequency set forth in 

the area of review and corrective action plan, the owner or operator must also 

conduct the following whenever warranted by material change in the monitoring 

and operational data or in the evaluation of the monitoring and operational 

data by the owner or operator: 

"(i) reevaluate the area of review by performing all of the actions specified 

in paragraphs (c)(1) through (3) of this section to delineate the area of 

review and identify all wells that require corrective action; 

"(ii) perform corrective action on wells requiring corrective action in the 

reevaluated area of review in the same manner specified in paragraph (d) of 

this section; and 

"(iii) submit an amended area of review and corrective action plan or 

demonstrate to the Director through monitoring data and modeling results that 

no change to the area of review and corrective action plan is needed. 

623
"(2) Except as provided in paragraph (3) of this subsection, the owner or 

operator shall also conduct a reevaluation by performing all of the actions 

specified in subparagraphs (1)(i) through (iii) of this subsection: 

"(i) Within the time periods specified in the area of review and corrective 

action plan for conducting such a reevaluation of the area of review; or 

"(ii) If an area of review evaluation or reevaluation has not been performed 

pursuant to §146.84(c) and (d) for the geologic sequestration project during 

the preceding ten (10) years, then within six months after the passage of that 

10-year period. 

"(3) The Director shall waive the requirement for a reevaluation pursuant to 

either §146.84(f)(2)(i) or (ii) if the owner or operator demonstrates to the 

Director through monitoring and operational data and modeling results, such as 

those reviewed annually pursuant to section 146.95, that such a reevaluation is 

not warranted by material change." 

Response: EPA disagrees with the proposed changes and believes that periodic AoR reevaluation at a 

set frequency of at least every 5 years is necessary to ensure protection of USDWs from endangerment 

and address the uncertainties inherent in predictive modeling. Periodic AoR reevaluations at §146.84(e) 

ensure that a deliberate effort is made to verify, based on monitoring and operational data, that the CO2 

plume is moving within the subsurface as predicted. EPA believes that less frequent reevaluations may 

not be sufficient to appropriately model plume and pressure front movement, establish conditions for 

corrective action, and ensure protection of USDWs from endangerment. 

EPA agrees that site-specific information will influence the need for AoR reevaluations, and clarifies 

that if site monitoring data agrees with the existing AoR delineation, a model recalibration may not be 

necessary, and the AoR reevaluation may consist of a demonstration that the current AoR delineation is 

adequate based on site monitoring data. 

Other EPA Comment Codes and Descriptions: 3500 2.2.3 Area of Review Reevaluation (seeking 

comment); 4700 2.7 Proposed Recordkeeping and Reporting Requirements (40 CFR 146.91) 

Comment: In addition, we recommend the following new §146.95: 

"146.95 Plan Maintenance and Update 

"(a) Owners or operators must submit an annual statement, signed by an 

appropriate company official, confirming that the company has: 

"(i) reviewed the monitoring and operational data that are relevant to a 

decision on whether to reevaluate the area of review and the monitoring and 

operational data that are relevant to a decision on whether to update a plan 

identified in §146.82(p) or (u) through (x) or the quality assurance plan for 

all testing and monitoring requirements; and 

"(ii) determined whether any updates were warranted by material change in the 

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25317

624
monitoring and operational data or in the evaluation of the monitoring and 

operational data by the owner or operator. 

"(b) Owners or operators must submit either the updated plan or a summary of 

the modifications for each plan for which an update was determined to be 

warranted pursuant to subsection (a) of this section. The Director may require 

submission of copies of any updated plans and/or additional information 

regarding whether or not updates of any particular plans are warranted. 

"(c) The Director may require the revision of any required plan whenever the 

Director determines that such a revision is necessary to comply with the 

requirements of this subchapter." 

Response: EPA agrees with the commenter that review of the GS project plans is appropriate. The final 

rule includes provisions that owners or operators review and update the AoR and corrective action plan, 

the testing and monitoring plan, and the emergency and remedial response plan throughout the life of the 

project (these provisions are added at §146.84(c), §146.90(j), and §146.94(d)). Owners or operators 

must review each plan and identify necessary amendments to the plan or demonstrate to the Director that 

no amendment is needed. These reviews must be performed within one year of an AoR reevaluation, 

following any significant changes to the facility (e.g., the addition of monitoring or injection wells), or 

when required by the Director. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

response (40 CFR 146.94) 

Comment: With respect to the emergency and remedial response section, we propose two 

changes - change §146.94(b)(4) to read: 

"Implement the emergency and remedial response plan approved by the Director, 

and keep the Director apprized of the implementation." 

Response: The final rule retains the language in §146.94(b)(4) as proposed. EPA agrees that the 

Director should be kept apprised of progress on the implementation of the emergency and remedial 

response plan but expects that the plan itself will include provisions on communications with the 

Director. The requirements for an emergency and remedial response plan at §146.94(a) are designed to 

ensure that owners or operators, as part of their permit application, comprehensively plan what actions 

would be necessary in the unlikely event of an emergency. The plan will ensure that operators know 

what entities and individuals must be notified and what actions must be taken to expeditiously mitigate 

any emergency situations. The rule sets forth triggers for notification to the Director that initiates 

consultation on appropriate responses. EPA expects that the owner or operator and Director would 

discuss the necessary response action and maintain a dialogue and communication throughout the 

conclusion of any needed actions. EPA is developing guidance on the development and implementation 

of emergency and remedial response plans for GS sites. 

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial 

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25318

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25319

625
response (40 CFR 146.94) 

Comment: and §146.94(d) to read: 

"The owner or operator must notify the Director and obtain his approval prior to 

conducting any well workover or other remediation measures not listed in the 

emergency and remedial response plan." 

It should be noted that the language chosen here for §146.94(d) relates 

specifically to remediation measures and not to emergency responses, which 

should not be delayed to seek approval when immediate response action is 

necessary. Every effort should be taken to ensure that emergency responses are 

comprehensively addressed in the plan, including appropriate notification 

provisions and timeframes, but emergency responses should not be delayed when 

awaiting approvals could impair the effectiveness of the response. 

Response: Since proposal, EPA has modified the final regulatory language at §146.94(d) to clarify what 

constitutes a workover to address a well failure (which invokes remedial actions) and what constitutes a 

maintenance-type workover. For maintenance-type workovers (i.e., those that are scheduled in advance), 

the owner or operator must notify and gain approval from the Director prior to beginning the workover. 

In the final GS regulation, EPA has moved this requirement to the reporting requirements at §146.91(d) 

to clarify its intent. 

Regarding concerns that notification could delay responses, EPA clarifies that the GS rule (at §146.94

(b)) describes procedures owners or operators must take in emergency situations. Specifically, upon 

determining that there is a problem with the well that may endanger a USDW, the owner or operator 

must first cease injection, then take all steps reasonably necessary to identify and characterize any 

release, notify the Director, and implement the approved emergency and remedial response plan, which 

may include a well workover. EPA believes that ceasing injection (which the owner or operator would 

do immediately and before notifying the Director) is the action necessary to prevent or mitigate 

endangerment of USDWs, as required under the SDWA. 

Comment Code: 1250 1.1.1.4 Flexibility is needed (performance-based standards) 

Individual Comments 

Comment: Second, the regulations should be sufficiently flexible to take into 

consideration site-specific characteristics and performance-based measures, and 

should be sufficiently adaptable to incorporate lessons learned from ongoing 

pilot and demonstration projects. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

Commenter Name: Karl R. Moor Letter ID: 0109

Commenter Organization: Southern Company, on behalf of Edison Electric 

Institute (EEI)

Comment ID: 

21993

626
post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Regarding the comment that flexibility would allow the incorporation of information gained from pilot, 

demonstration, and early commercial projects, EPA adds that it is using an adaptive approach to 

regulating GS under the UIC Program. Even after finalization of the GS regulation, EPA plans, every six 

years, to collect and review project data on GS research projects to determine whether the appropriate 

amount and types of information and appropriate documentation are being collected, and to determine if 

modifications to the requirements are appropriate or necessary. 

Comment: Our second message for EPA today addresses the importance of regulatory 

flexibility. 

Regulatory flexibility is essential for carbon capture and storage projects. EEI 

cautions against overly prescriptive, one-size fits all regulations because they 

add costs without ensuring greater protection to underground sources of drinking 

water. 

Because no two geologic formations are the same, no two CCS projects will be the 

same. The geologic framework in the selected injection formation - including, 

but not limited to, geometry, depth, composition, confining strata, and the 

number and location of existing wells in the Area of Review - will all affect 

how and whether a project moves forward. EPA already recognizes that each 

storage project will be unique: Under the proposed regulations, a potential 

owner or operator of a project will be required to present detailed information 

in its permit application that is specific to the geologic formation chosen for 

storage and the surrounding area, both above and below the surface. Based on 

the site-specific information presented, the UIC program director will decide 

whether to issue a permit. 

Consistent with EPA’s approach to permitting, the portions of the proposed 

regulations that address inherently site-specific issues should allow for sitespecific determinations. Tying regulatory requirements to site-specific 

characteristics not only will ensure that properly sited projects are able to 

secure the approvals and financing needed to move forward, but also will prevent 

the imposition of unnecessary and expensive requirements that could render some 

proposed projects uneconomic and hinder the commercial deployment of this 

critical technology. 

Response: EPA agrees that permitting decisions for GS wells should be based on site-specific factors. 

The GS rule requires owners or operators to submit, and Directors to consider, extensive site-specific 

data, specified at §146.82, to demonstrate that a site is suitable for GS. Additionally, many of the permit 

requirements for GS wells are established through individualized site-specific plans for AoR and 

corrective action, testing and monitoring, and injection well plugging and post-injection site care and 

site closure. EPA adds that the final GS rule includes a balance of specific criteria to be met by the 

Commenter Name: Karl R. Moor Letter ID: 0109

Commenter Organization: Southern Company, on behalf of Edison Electric 

Institute (EEI)

Comment ID: 

22002

627
owner or operator and areas of Directorial discretion and considerations for how that discretion would 

be exercised. The Agency believes this balance allows for GS projects to be designed and permitted to 

address the unique, site-specific aspects of each project, while providing consistency in permitting 

across the U.S. 

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

Comment: EEI and its members also encourage EPA to consider performance-based 

requirements over prescriptive rules. Again, these are better regulatory 

options for CCS projects because they ensure that a project is subject to only 

those requirements that have been shown to be necessary. Moreover, in many 

cases they will better protect underground sources of drinking water than 

default prescriptions. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Other EPA Comment Codes and Descriptions: 2400 1.8 Comments on EPA's adaptive rulemaking 

process; 5600 2.11 Comments related to UIC Program primacy for Class VI wells 

Comment: Flexible, site-specific regulations ask a great deal of the regulator, in this 

case the UIC program director. Despite these challenges, EEI urges EPA to 

consider these types of regulations because they present a win-win situation: a 

higher level of environmental protection while fostering a regulatory regime 

that encourages investment in CCS projects. We also acknowledge that these 

benefits cannot be realized unless the UIC program director is given good 

guidance on how best to exercise his or her discretion. EPA should provide that 

guidance in either the final regulations or supplemental guidance, in order to 

ensure that the director’s decisions have a sound regulatory basis. 

Response: EPA agrees that flexibility is important to accommodate the varied conditions that may be 

encountered at GS sites. EPA notes that the final rule does allow owners or operators flexibility. Many 

of the permit requirements will be established through site-specific plans developed by the owner or 

operator and approved by the Director, and EPA anticipates that owners or operators will consult with 

the Director as they develop, implement, and update these plans. In addition, the final rule affords the 

Director flexibility to approve alternatives to the requirements in some cases. For example, the Director 

Commenter Name: Karl R. Moor Letter ID: 0109

Commenter Organization: Southern Company, on behalf of Edison Electric 

Institute (EEI)

Comment ID: 

22005

Commenter Name: Karl R. Moor Letter ID: 0109

Commenter Organization: Southern Company, on behalf of Edison Electric 

Institute (EEI)

Comment ID: 

22009

628
may in certain situations modify the length of the post-injection site care period or approve an 

alternative post-injection site care timeframe as part of the permitting process under §146.93, allow the 

use of alternate methods for mechanical integrity testing, and waive the requirement that wells be 

designed to inject below the lowermost USDW. Additionally, the regulations provide flexibility for 

selecting appropriate sites and target formations at §146.82, well construction specifics at §146.86, and 

testing and monitoring regimes at §146.90, provided the owner or operator can demonstrate that the 

injection and storage will not endanger USDWs and that minimum requirements for the site are met. 

EPA agrees with commenters on the importance of allowing Directors discretion given the variety of 

geologic settings in which GS will be applied. EPA recognizes that State, Tribal, and DI UIC Program 

Directors are in the best position to evaluate the unique issues related to well depth, geology, and 

hydrogeology that are posed by a Class VI well. Some degree of flexibility is needed for Class VI wells 

because each decision made will be site-specific and conditions will differ from state to state. The GS 

rule balances the need for these site-specific decisions with the need for minimum Federal requirements 

to ensure national consistency while ensuring the protection of USDWs. To ensure the final rule is 

applied consistently, EPA is developing guidance materials and plans to conduct on-line and in-person 

training for States, Tribes, and Territories that describe the process of applying for and receiving 

primary enforcement responsibility (primacy) for GS Class VI wells under Section 1422 of SDWA, as 

well as the technical and administrative issues related to developing GS regulations that are the 

equivalent of minimum Federal criteria and requirements. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

As part of its adaptive approach, if EPA finds that there is not sufficient consistency in the permits so 

that USDWs are not being sufficiently protected from endangerment, it will consider changes to the 

permit requirements in the future. 

Comment: 2. Given the direct impact this program will have on the electric utility 

industry, we appreciate EPA's goal of establishing certainty and transparency to 

the requirements for Class VI carbon dioxide injection. It is also crucial, 

however, for the regulations to reflect the challenges inherent in crafting 

controls for commercial CO2 injection and storage activities when such largescale commercial operations are only at the nascent stage. The fundamental 

challenge confronting EPA in this rulemaking is to establish a cost-effective 

and environmentally sound regulatory program to cover a range of operations for 

which the technology will not be commercially deployed for a number of years. To 

meet this challenge and establish a workable regulatory framework over the 

coming decades for the long-term storage of carbon dioxide, EPA must craft the 

regulations with flexibility so that they may be fine-tuned as industry and 

regulators alike gain experience with large-scale carbon dioxide sequestration. 

3. Because information and technology related to carbon sequestration are sure 

to develop as more experience is gained, USWAG urges EPA to avoid blanket 

prohibitions or arbitrary absolutes in the Final Rule. We agree that the 

standard underlying the technical requirements for carbon dioxide sequestration 

wells is the protection of underground sources of drinking water. However, 

because it is difficult to know at this point what future technologies will be 

developed for injection and long-term storage of carbon dioxide in a manner that 

is protective of USDWs - and because there is sure to be demand for significant 

Commenter Name: Paul Pike Letter ID: 0111

Commenter Organization: Ameren Corporation on behalf of USWAG Comment ID: 22401

629
capacity for CO2 storage - EPA should not prematurely preclude injection in 

specific types of sites or through certain methods. The Final Rule should leave 

the door open for a range of injection sites and methods - some of which are 

unrecognized, or even unknowable, at this point in time - provided that the 

ultimate objective of protecting USDWs is achieved. 

Response: The Agency agrees that flexibility is important, and believes that the Class VI requirements 

balance site-specific flexibility with USDW protection. Rather than setting performance or technologybased standards for GS projects, EPA is adopting a flexible approach, where operators of GS projects 

would develop and implement site-specific plans for delineating the AoR, testing and monitoring the 

site, performing corrective action, and post-injection site care. EPA believes that the plans—which 

would be reviewed and approved by the Director and periodically updated throughout the life of the 

project—promote an ongoing dialogue between the operator and the Director that will encourage use of 

the most appropriate technologies for a particular project. 

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Other EPA Comment Codes and Descriptions: 3500 2.2.3 Area of Review Reevaluation (seeking 

comment); 5000 2.8 Proposed Well Plugging and Post-Injection Site Care Requirements 

Comment: 6. Because of the widely varied characteristics and limitations of different 

carbon dioxide sequestration projects, it is essential to incorporate 

performance-based standards into the Final Rule, leading to a site-specific 

approach to requirements for Area of Review reevaluation and post-injection site 

care and closure periods. 

Response: The post-injection site care requirements in the final GS rule, as specified in §146.93(b), 

incorporate a combination of a fixed timeframe and a performance standard approach. The GS rule 

offers owners or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing the 

Director discretion to shorten or lengthen the PISC timeframe during the PISC period based on sitespecific data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a 

Class VI well owner or operator to demonstrate, based on substantial data during the permitting process, 

that an alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs 

pursuant to requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

Commenter Name: Paul Pike Letter ID: 0111

Commenter Organization: Ameren Corporation on behalf of USWAG Comment ID: 22405

630
and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection site 

care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will assist 

Directors in evaluating proposed well plugging plans and post-injection site care and site closure plans 

under §146.92 and §146.93. The guidance describes recommended approaches for how an owner or 

operator could plug injection and monitoring wells; perform post-injection monitoring; demonstrate the 

appropriateness of an alternative post-injection site care time frame; demonstrate non endangerment; and 

perform site closure activities. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

In response to comments about AoR evaluation, EPA disagrees that the GS regulation should include 

performance-based standards for AoR calculation. However, EPA believes that consideration of sitespecific conditions is appropriate for the AoR calculation and reevaluation process. EPA believes that 

the flexibility incorporated into the AoR and corrective action plans and the provision for AoR 

reevaluation as required at §146.84(e) provide for an ongoing review of the site and a dialogue between 

the Director and the owner or operator to ensure that the most appropriate modeling and corrective 

action technologies are used to protect USDWs from endangerment. 

Comment: Wells are indeed a fundamental component of a geologic storage system. Having 

appropriate design, construction & operating requirements for these wells is 

necessary to ensure delivery of the secure storage of CO2. 

Site-specific performance-based guidelines, like the well-related examples I’ve 

noted, will serve the purpose of requiring application of the appropriate 

technological solutions to protect USDWs. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Comment: The Proposal does not include sufficient flexibility. Congress mandated, through 

Section 1421(b)(3)(A) of the SDWA, that UIC regulations developed by EPA permit 

or provide consideration of varying geologic, hydrological, or historical 

conditions in different States and in different areas within a State. Thus, 

Congress cautioned EPA against a ‘one-size-fits-all’ regulatory scheme, and 

mandated consideration of local conditions and practices. However, the Proposal 

does not allow State directors to use their expertise and knowledge to account 

for these varying conditions. 

Commenter Name: Brian Williams Letter ID: 0116

Commenter Organization: BP Alternative Energy Comment ID: 22056

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24741

631
EPA states in the preamble that its reason for selecting Alternative #3 is 

because it ‘provides flexibility while creating a framework of minimum 

requirements to ensure consistency across the nation.’ However, by selecting 

Alternative #3, EPA selected as a starting point the requirements for Class I 

industrial non-hazardous wells. Because of this, the flexibility is restrained 

at the very outset. 

Using as the reason the unknowns and the unique characteristics of CO2 

geosequestration (buoyancy, corrosivity, high injection volumes, etc.), the 

Proposal seems to include the entire slate of possible technologies available to 

complete, operate, monitor and close a UIC well and the injection/confining 

formations. In a few areas, the Proposal provides the Director with discretion 

to set certain application, permit, and monitoring criteria that are appropriate 

to local geologic settings. However, because EPA began with an unnecessarily 

stringent Class I framework, and added numerous other nondiscretionary 

requirements, the flexibility is insufficient. The result is that the Proposal 

is unnecessarily prescriptive and costly. 

Response: EPA agrees that flexibility is important to accommodate the varied conditions that may be 

encountered at GS sites while ensuring the protection of USDWs. 

The technical requirements in Alternative 3 (and the final GS rule) build upon the long-standing UIC 

regulatory framework for deep wells and are appropriately tailored to address the unique nature of fullscale CO2 GS, including the volumes of CO2 to be injected, the buoyant and mobile nature of the 

injectate, and its corrosivity in the presence of water. 

The regulation provides flexibility for selection of appropriate sites and target formations (under 

§146.82), well construction specifics (under §146.86), and testing and monitoring regimes (under 

§146.90), provided the owner or operator can demonstrate that the injection and storage will not 

endanger USDWs and that minimum requirements for the site are met. 

Comment: 3. EPA should provide more flexibility in the siting requirements: a. 

acknowledge that some sites offer very good protection when compared to others 

and ease regulatory burden on those sites; b. promote transfer of EOR to 

storage; c. delete the requirement that the confining zone be free of all 

transmissive faults or fractures; d. delete references to multiple confining 

zones; and e. revise the Proposal to allow for site-specific characteristics and 

performance- based determinations. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24745

632
Please see the remainder of EPA’s responses to this comment for further details related to transitioning 

of ER projects for GS and confining zone requirements. 

Other EPA Comment Codes and Descriptions: 3824 2.3.1.2 Cementing of long-string casing (seeking 

comment) 

Comment: 4. EPA should provide more flexibiilty in construction, for example, delete the 

requirement that the long string casing be cemented to the surface. 

Response: EPA believes that the requirements for long-string casing are appropriate and offer 

appropriate flexibility: §146.86(b)(3) requires that the long-string casing extend to the injection zone and 

be cemented by circulating cement to the surface in one or more stages. It does not, however, specify 

how cementing would be accomplished, and gives flexibility to the owner or operator to propose 

alternate methods to provide a sufficient amount of cement to meet the standard that USDWs are 

protected from endangerment, subject to the approval of the Director. 

EPA notes that there are many potential ways to meet the requirement, such as the use of staged 

cementing. See the discussion of Class VI well construction requirements in the preamble to the final 

GS rule for additional information. Additionally, EPA is developing guidance on the construction of 

Class VI wells. This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA adds that other aspects of the rule allow flexibility based on site-specific considerations: with their 

permit applications, owners or operators must submit proposed well construction procedures, as 

specified at §146.82(a)(12), that address the specific drilling and injection environment and the chemical 

and physical nature of the CO2 injected stream. The Director must evaluate the appropriateness of the 

proposed construction based on site-specific information about the injection project, including injection 

pressures, injection and confining zone lithology, and information about the carbon dioxide stream, as 

provided in the final GS rule at §146.86(b)(1). 

Other EPA Comment Codes and Descriptions: 3530 2.2.3.1 AoR reevaluation frequency (seeking 

comment) 

Comment: 5. EPA should provide more flexibiilty in operation. For example, allow an EOR 

operator to demonstrate that CO2 is sequestered, and instead of a 10-year 

default period for reevaluation of the area of review, allow the timing for such 

reevaluation to be determined based on site-specific characteristics and sitespecific monitoring of the CO2 plume and pressure front. 

Response: EPA disagrees that the GS regulation should include performance-based standards for AoR 

calculation. However, EPA believes that consideration of site-specific conditions is appropriate for the 

AoR calculation and reevaluation process. EPA believes that the flexibility incorporated into the AoR 

and corrective action plans and the provision for AoR reevaluation as required at §146.84(e) provide for 

an ongoing review of the site and a dialogue between the Director and the owner or operator to ensure 

that the most appropriate modeling and corrective action technologies are used to protect USDWs from 

endangerment. 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24746

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24748

633
However, EPA believes that setting a minimum reevaluation frequency is appropriate. In the final rule, 

the Agency changed the minimum frequency for the AoR reevaluation at §146.84(e) from 10 years to at 

least every 5 years in the final GS rule. EPA believes that this revised frequency addresses commenters' 

concerns about the inherent uncertainties in modeling CO2 movement, the emerging nature of GS 

technology, risk-based targeting of monitoring activities, and the unique nature of CO2 GS. 

Comment: General Comments 

Effort should be made, to the extent practicable, to keep provisions for 

Underground Injection Control (UIC) of CO2 consistent with already known and 

understood UIC principles and regulations. Care should be taken to avoid 

overestimating the risks associated with GS, in order to ensure that the final rules 

are not excessively burdensome or complex. Of course, the rules must 

simultaneously ensure adequate protection of human health and the environment. 

However, excessive, complex regulatory requirements have the potential to limit 

development of a technology that will be critical to our efforts to address climate 

change effectively, adding significantly to costs for a program that will already 

result in significant additional costs to the energy sector, industry and consumers. 

Response: EPA disagrees that the requirements in the GS rule overstate the risk associated with GS. 

The UIC Program, under the authority of the SDWA, provides a strong framework for regulating 

injection of CO2 for GS; the GS regulation tailors the UIC requirements to address the unique issues 

associated with large-scale GS including large injection volumes, the relative buoyancy of CO2, its 

corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its 

mobility within subsurface geologic formations. 

EPA recognizes the importance of providing clear, flexible, scalable, and appropriate regulations. EPA 

believes that the GS regulation will provide certainty to industry and the public by providing consistency 

in requirements across the U.S. and transparency about what requirements apply to owners or operators.

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

Other EPA Comment Codes and Descriptions: 1600 1.3 Risk Associated with CO2 GS 

Comment: 1.) The SWP would like to recommend a risk-based approach to the siting 

requirements, Area of Review (AoR), monitoring requirements, site-closure 

requirements, and the grandfather clause. The EPA notes in several places within 

the proposed rule that each GS site is unique with respect to physical and 

chemical properties. As such, the SWP recommends that the EPA adopt a 

risk/performance-based approach for each site. Reasoning for this recommendation 

as it relates to specific aspects of the proposed rule are outlined by relevant 

sections: 

Response: EPA has taken a regulatory approach that promotes USDW protection, incorporates 

Commenter Name: Carl Carlsson Letter ID: 0131

Commenter Organization: SUEZ Energy Generation NA, LLC Comment ID: 21525

Commenter Name: Dawn A. Thorne Letter ID: 0134

Commenter Organization: University of Utah Energy and Geoscience Institute on 

behalf of the Southwest Regional Partnership

Comment ID: 

21653

634
flexibility or permitting authority discretion when appropriate, seeks to limit burden on owners or 

operators and permitting agencies, and provides a foundation for national consistency in permitting of 

GS projects. Under the final rule, many of the permit requirements must be established through sitespecific plans (e.g., AoR and corrective action plan, testing and monitoring plan, etc.) developed by the 

owner or operator and approved by the Director. Consequently EPA expects that owners or operators 

will consult with the Director as they develop, implement, and update these plans. Additionally, the 

Director has the discretion to approve alternatives to the requirements in some cases. For example, the 

Director may in certain situations modify the length of the post-injection site care period or approve an 

alternative post-injection site care timeframe as part of the permitting process under §146.93, allow the 

use of alternate methods for mechanical integrity testing (if approved by EPA) under §146.89, and 

waive the requirement that wells be designed to inject below the lowermost USDW under §146.95. 

Comment: In conclusion, the SWP recommends a site-specific, performance/risk-based 

approach to the fmal regulatory framework. This method will allow for 

consideration of the uniqueness of each CCS site, and accommodate advancements 

in technology over time. The SWP would also urge collaboration with other 

regulatory agencies and private insurers to establish a sound regulatory 

framework with long-term funding and oversight at the state level. Thank you for 

the opportunity to comment. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Comment: Tailored Regulatory Requirements 

WDNR supports EPA's selection of a flexible regulatory approach which recognizes 

that full-scale projects involving long-term storage of CO2 are unique due to 

the volume of CO2 that is to be injected, the buoyancy and viscosity of the 

proposed injectate, the corrosive nature of CO2 when mixed with water, and the 

many geologic formations that can potentially be used for CO2 storage. By 

building on the existing regulatory framework for other deep injection wells and 

providing flexibility and/or discretion to the permitting authority to address 

site specific variability, the requirements being proposed by the Agency 

appropriately balance the need to provide protection to the nation's underground 

sources of drinking water with the need to provide a degree of regulatory 

certainty and consistency to owners and operators of GS facilities, 

Response: EPA acknowledges the comment, and agrees that permitting decisions for GS wells should 

Commenter Name: Dawn A. Thorne Letter ID: 0134

Commenter Organization: University of Utah Energy and Geoscience Institute on 

behalf of the Southwest Regional Partnership

Comment ID: 

21665

Commenter Name: Jill D. Jonas Letter ID: 0135

Commenter Organization: Wisconsin Dept. of Natural Resources (WDNR) Comment ID: 21669

635
be based on site-specific factors. The GS rule requires owners or operators to submit, and Directors to 

consider, extensive site-specific data, specified at §146.82, to demonstrate that a site is suitable for GS. 

Additionally, many of the permit requirements for GS wells are established through individualized sitespecific plans for AoR and corrective action, testing and monitoring, and injection well plugging and 

post-injection site care and site closure. EPA adds that the final GS rule includes a balance of specific 

criteria to be met by the owner or operator and areas of Directorial discretion and considerations for how 

that discretion would be exercised. The Agency believes this balance allows for GS projects to be 

designed and permitted to address the unique, site-specific aspects of each project, while providing 

consistency in permitting across the U.S. 

Comment: 2. EPA should adopt a performance-based regulatory scheme rather than the 

"Tailored-General Provision" approach it has proposed. Any regulatory approach 

to geologic sequestration must be based on the recognition that no two sites are 

alike. Because this is so, it is crucial that the regulatory scheme that is 

ultimately implemented be one that is flexible and performance-based, rather 

than one that imposes across-the-board requirements that may be appropriate for 

one kind of site but inappropriate for another. The need for flexibility is only 

increased by the fact that there is still a good deal to learn about large-scale 

geologic sequestration. Premature imposition of prescriptive requirements could 

damper the development and future interest in these projects by companies that 

might otherwise be interested in entering this new field. EPA should use 

performance-based standards and should maintain flexibility in the creation and 

implementation of regulatory requirements, in light of the variations in 

geologic formations that will be encountered from project to project. Imposition 

of "one-size-fits-all" requirements would be inappropriate and would 

unnecessarily hinder full development of geologic sequestration technology. 

TPA believes that the best approach would be for states with primacy to develop 

specific, performance-based standards based on the particular geologic 

characteristics and experience with deep well injection activities present in 

the respective states. Texas, in particular, has a breadth and depth of 

experience in this area and our Texas regulatory body, the Texas Railroad 

Commission, has the technical expertise and knowledge to develop criteria suited 

to our state. Geologic sequestration can be an important tool in the nation's 

effort to reduce greenhouse gas emissions, but only if its implementation is not 

hindered by unnecessarily burdensome or inflexible regulations. TPA recognizes 

that performance-based standards impose an increased burden on regulators, but 

if geologic sequestration is to be widely utilized as a means to reduce carbon 

dioxide emissions, then there really is no alternative. 

The importance of protecting drinking water is obvious, and no one in the oil 

and gas industry is seeking to cut regulatory corners. TPA is simply urging EPA 

to recognize both the need for flexibility in the regulatory regime and the 

importance of fostering public confidence in the safety of geologic 

sequestration technology. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

Commenter Name: Patrick Nugent Letter ID: 0143

Commenter Organization: Texas Pipeline Association (TPA) Comment ID: 23124

636
is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

In response to the comment that States with primacy be able to develop “performance-based standards,” 

the Agency clarifies that States, Tribes, and Territories can develop requirements for Class VI and 

submit primacy applications (under Section 1422 of the SDWA) for review and approval by EPA as 

long as the requirements are as stringent as or more stringent than the Federal minimum requirements. 

Other EPA Comment Codes and Descriptions: 2400 1.8 Comments on EPA's adaptive rulemaking 

process 

Comment: General Comment 

1. TVA acknowledges the challenge of developing a rule to provide regulatory 

certainty for the GS of CO2 in order to foster industry adoption of carbon capture 

and storage (CCS) in the face of considerable technological and experiential 

uncertainty about safely injecting and sequestering the huge volumes of 

supercritical CO that would be required to meet the goals of future climate 

change legislation. In the face of such uncertainty, this rule is justifiably 

stringent for protecting USDWs, ecological resources, and the public. Because 

scale-up from experimental to fully operational wells will provide the 

experience necessary to have a rulemaking with the most appropriate protections, 

TVA requests that a provision be added to require periodic review (possibly 

every two years initially until sufficient operational experience is gained) and 

to revise the rule’s flexibility appropriately where justified. TVA agrees with 

EPA that the regulatory standard for permitting CO2 GS wells should be the 

protection of USDWs, which must take precedence over the need to sequester CO2 

underground at any site. For this reason, TVA supports a stringent rule 

initially as long as a provision is made to revise the rule to incorporate 

operational experience as it is gained. 

Response: EPA agrees that an adaptive approach to the UIC GS rulemaking is appropriate. The Agency 

plans to use such an approach to ensure that USDWs are protected from endangerment while making it 

possible to meet the potentially fast pace of GS deployment. EPA believes that an adaptive approach 

will allow regulatory development to proceed in time to meet the current and future demand for Class VI 

permits while recognizing the need to: continue to gather data from pilot projects and other research as it 

becomes available; and to enhance understanding of the technical and administrative aspects of GS 

deployment, operation, and technology developments. EPA plans, every six years, to collect and review 

data on GS projects to determine whether the appropriate amount and types of information and 

appropriate documentation are being collected, and to determine if modifications to the requirements are 

appropriate or necessary. 

However, the Agency cannot definitively predict that future requirements will be less stringent than 

those in the final GS rule. The Agency believes that the Class VI requirements appropriately address the 

Commenter Name: Richard Driggans Letter ID: 0145

Commenter Organization: Tennessee Valley Authority Comment ID: 23147

637
unique challenges posed by large-scale GS–including large injection volumes, the relative buoyancy of 

CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and 

its mobility within subsurface formations. Any changes implemented under the adaptive rulemaking 

would be based on technical information and data generated and collected during early GS projects or 

other research. 

EPA believes that reevaluating the GS requirements every six years is appropriate to allow sufficient 

time for projects to be permitted, for State and Tribal programs to apply for and receive primacy, and for 

sufficient project data to be collected. For example, once the first GS projects are permitted, injection 

commences, and monitoring data are generated and analyzed, EPA can begin to review this data to 

verify the applicability and appropriateness of the requirements including the usefulness of AoR 

calculation models, and the utility and design of monitoring plans and corrective action plans. As 

construction and operation of GS projects continue (e.g., as AoR reevaluations are conducted or when 

the first projects cease injecting), EPA will have additional opportunities to evaluate the requirements in 

the course of subsequent reviews. 

EPA believes that shorter review intervals, e.g., 2 years, as the commenter suggests, would not provide 

sufficient time for projects to be permitted, State and Tribal programs to apply for and receive primacy, 

and sufficient data to be collected. EPA clarifies that, if early project data indicate before six years that 

revisions are appropriate, EPA will publish new requirements prior to then. 

Comment: 1. Regulatory ("Director’s") Discretion - TVA supports a flexible rule that 

vests in the Director the discretion to grant certain approvals. However, where 

the Director is provided such discretion (e.g., for imposing secondary 

containment, requesting additional testing, monitoring CO2 fluxes in surface air 

and soil gas, changing the 50-year default post injection care requirement, 

shortening the notification period for plugging an injection well or approving 

site closure plans), the proposed rule should include factors that the Director 

must consider in exercising discretion. 

Response: The final GS rule includes a balance of specific criteria to be met by the owner or operator 

and areas of Directorial discretion and considerations for how that discretion would be exercised. The 

Agency believes this balance allows for GS projects to be designed and permitted to address the unique, 

site-specific aspects of each project, while providing consistency in permitting across the U.S. 

EPA is developing guidances for States that describe the process of applying for and receiving primary 

enforcement authority (primacy) for GS Class VI wells under Section 1422 of SDWA, as well as the 

technical and administrative issues on developing GS regulations that are the equivalent of minimum 

federal criteria and requirements. The guidance will describe areas of Directorial discretion and 

considerations for how that discretion would be exercised. This guidance will be available on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: SUMMARY 

Commenter Name: Richard Driggans Letter ID: 0145

Commenter Organization: Tennessee Valley Authority Comment ID: 23148

Commenter Name: Kenneth Alexander Letter ID: 0146

Commenter Organization: Old Dominion Electric Cooperative (ODEC) Comment ID: 21709

638
ODEC applauds the efforts EPA has taken thus far to instill "certainty" and 

"transparency" into the future Class VI C02 regulatory regime, 73 Fed. Reg. at 

43496. The challenge EPA faces is to craft a Final Rule for commercial 

CO2injection appropriate for activities that will largely be conducted in the 

future. EPA has had to confront many technical uncertainties regarding the 

establishment and operation of GS wells. Because many of the technical aspects 

are unknown, it is also very difficult to develop a clear understanding 

ofproject risks and liabilities. As long as risks and liabilities are largely 

unknown and open-ended, private companies will not step forward to offer 

insurance and other risk management products, and it will not be possible to 

obtain the level of financing needed to undertake a costly GS operation. We hope 

the pilot carbon capture and sequestration (CCS) projects conducted by DOE and 

other entities will help resolve some of these uncertainties. EPA needs to 

establish clear, reasonable regulations that are environmentally protective and 

cover a range of operations for which the technology will not be commercially 

deployed for a number of years. To the extent practicable, EPA needs to 

establish a single, clear, reasonable and protective liability regime for an 

activity where the nature of the risks are different from many other industrial 

activities and the full extent of possible risks from full scale CCS operations 

are presently unknown. Comments Regarding UIC Regulations 

1.Because ofthe difficulty of regulating future activities, we urge EPA to 

continue to use a "performance based" approach in developing the requirements 

for Class VI UIC wells. This way, rules can be readily adjusted and fine-tuned 

as industry and regulators alike gain experience with large-scale CO2 

sequestration. 

2.Because information and technology related to carbon sequestration will evolve 

as industry and regulators gain experience with CCS, ODEC urges EPA to resist 

placing blanket prohibitions or detailed operational specifications in the Final 

Rule. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

639
projects and facilitating deployment are outside the scope of the GS rulemaking. 

Comment: The real challenge, however, will be for EPA to create a regulatory framework 

flexible enough to allow for technologies that may not be commercially available 

for many years. That is, EPA must craft its CCS regulations with enough 

flexibility so that they may be modified to include technologies not yet on the 

market. 

Response: EPA is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Other EPA Comment Codes and Descriptions: 1680 1.3.8 Don't overstate risk, don't stigmatize CO2 

Comment: a. Distorts Public Perception 

By making the proposed rule so strict, the public may unduly perceive CCS as a 

dangerous activity. Consider that the proposed rule requires a secondary 

containment field for CO2 storage. Such a requirement is unprecedented both 

domestically, in the UIC program (including for storage of hazardous wastes in 

Class I wells), as well as internationally. [FN10 Countries such as Norway, 

Canada, and Australia, which have carbon capture and storage projects currently 

underway, do not require secondary containment zones, and in fact, those 

countries regulate CCS using existing petroleum laws.] Singling out carbon 

capture and storage for this heightened and substantially more rigorous 

requirement would suggest to the public that EPA thinks geologic storage of 

carbon dioxide is more dangerous than the underground injection of other 

substances. Since EPA is the agency charged with protecting the environment, the 

public could be easily swayed by EPA’s apparent apprehension of carbon capture 

and storage as currently embodied in the proposed regulations. In order to 

create a regulatory scheme that fosters carbon capture and storage development 

and deployment, EPA should reconsider how it has characterized carbon dioxide 

injection -- both explicitly and implicitly -- in its final regulations. 

Response: EPA disagrees that the GS regulation overstates the risk of CO2 injection. EPA recognizes 

that injecting large volumes of CO2 for GS poses unique challenges that, if not properly managed, could 

endanger drinking water sources and have other adverse impacts. However, with proper site selection, 

the final, tailored, Class VI requirements address the large volumes of CO2 injected, its buoyancy, 

potential corrosivity in the presence of water, and potential impurities in the CO2 stream. In addition, 

EPA expects the tailored permitting, siting, construction, operation, monitoring, and post-injection site 

care requirements in the GS rule to prevent leakage from injection formations and protect USDWs. 

EPA also disagrees that the tailored requirements will create a negative public perception of GS. The 

Agency believes that a demonstration to the public that GS projects are meeting the GS rule's tailored 

Commenter Name: William Kovacs Letter ID: 0148

Commenter Organization: U.S. Chamber of Commerce Comment ID: 21770

Commenter Name: William Kovacs Letter ID: 0148

Commenter Organization: U.S. Chamber of Commerce Comment ID: 21773

640
requirements will likely improve confidence in the project and help address public questions and 

concerns. 

Regarding secondary containment, EPA retains the requirement to identify additional 

containment/confining zones, if required by the Director, as proposed, at §146.83(b). EPA 

acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this 

requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA 

believes that, in some situations, the presence of additional confining and containment zones above the 

primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further 

impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for 

monitoring, mitigation, and remediation. The Agency's decision is supported by commenters 

representing states, water associations, and an electric utility who assert that these requirements promote 

a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and 

are intended to improve understanding of the project as a whole and promote better modeling of the site. 

While other countries may not require such additional protection, EPA believes that providing the 

Director this additional discretion is an important element of assuring that GS activities will not 

endanger USDWs. 

Comment: Conclusion 

CCS is not a "silver bullet" but an innovative solution for reducing CO2 

emissions to the atmosphere. The Chamber applauds EPA for seeking out novel and 

important approaches for addressing climate change, reducing CO2 emissions, and 

continuing to protect our vital sources of safe drinking water. Nevertheless, 

the Chamber encourages EPA to address the potentially serious impediments to CCS 

development and deployment that have been raised in these comments. 

Response: EPA acknowledges the comment. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: The proposed Class VI rule addresses all of the important issues which must be 

addressed in order to protect USDWs when geologic sequestration of CO2 is 

undertaken. Actions required by the rule are generally conservative, which is 

good, but, in three areas, discussed below, requirements are overly, and 

unnecessarily, conservative. 

Response: EPA acknowledges the comment. The requirements for GS projects are tailored to address 

the unique issues associated with GS, including large injection volumes, the relative buoyancy of CO2, 

its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its 

mobility within subsurface geologic formations. 

Please see the remainder of EPA's responses to this comment for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble as well as the 

Commenter Name: William Kovacs Letter ID: 0148

Commenter Organization: U.S. Chamber of Commerce Comment ID: 21777

Commenter Name: Larry Myer Letter ID: 0149

Commenter Organization: Lawrence Berkeley National Laboratory (Berkeley Lab) 

U.S. Department of Energy (DOE)

Comment ID: 

21796

641
rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1420 1.2.1.1 Support the GS rulemaking 

Comment: Spectra believes the GS Rule should be designed to encourage carbon capture and 

sequestration as an integral part of any national climate change policy. Second, 

while Spectra appreciates many of the unknowns that currently exist with respect 

to commercial scale GS operations, sour CO2 [1] from natural gas operations has been 

safely injected for nearly two decades and such operations present significant 

opportunities for further reductions in atmospheric CO2 emission through longterm geologic sequestration. Lastly, Spectra and many others within the 

industry have ongoing operations in North America and elsewhere, and we are 

concerned that, should EPA impose excessive or unreasonable requirements as part 

of the GS Rule, this could have negative implications for GS activities in other 

jurisdictions such as Canada - where the majority of Spectra’s current geologic 

sequestration activities occur. 

1 The term sour CO2 (a/k/a "acid gas") is used to describe the by-product 

generated from natural gas processing and is primarily a mixture of CO2 and H2S 

but may also contain a small amount of impurities. 

Response: EPA clarifies that the intent of the GS rule is not to encourage GS or CCS in the US or 

elsewhere; rather, the purpose of the GS rule is to ensure that, where GS is deployed, it is conducted in a 

manner that protects USDWs from endangerment. The Agency's authority as it relates to GS is limited 

to protection of USDWs within the United States. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; and the Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research, and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

EPA is using an adaptive approach to regulating GS under the UIC Program. Even after finalization of 

the GS regulation, the Agency plans to collect and review data every six years on GS projects to 

determine whether the appropriate amount and types of information and appropriate documentation are 

being collected, and to determine if modifications to the requirements are appropriate or necessary. 

Comment: II. FOR CCS TO BE VIABLE, GS REQUIREMENTS MUST BE FLEXIBLE, TAILORED 

Commenter Name: Brianne Metzger Letter ID: 0151

Commenter Organization: Spectra Energy Corp Comment ID: 21816

Commenter Name: Brianne Metzger Letter ID: 0151

Commenter Organization: Spectra Energy Corp Comment ID: 21817

642
TO SITE 

SPECIFIC NEEDS, AND MUST RELY UPON STATE EXPERIENCE. 

Under the Proposed Rule, EPA has adopted an approach specifically tailored to 

the unique characteristics of CO2 deepwell injection. While we generally 

support the Agency’s decision not to be overly prescriptive in the development 

of the GS requirements, certain portions of the technical requirements appear 

to be excessive and unreasonable and will result in higher operational costs 

without meaningful benefits. In the promulgation of the Final Rule, we would 

encourage EPA to continue to build upon the concept of flexibility, reduce the 

amount of unnecessary and costly requirements, and, in certain cases, provide 

greater discretion to the States in deciding the technical specifications 

applicable to siting, well construction, and monitoring. 

Response: EPA agrees that permitting decisions for GS wells should be based on site-specific factors. 

The GS rule requires owners or operators to submit, and Directors to consider, extensive site-specific 

data, specified at §146.82, to demonstrate that a site is suitable for GS. Additionally, many of the permit 

requirements for GS wells are established through individualized site-specific plans for AoR and 

corrective action, testing and monitoring, and injection well plugging and post-injection site care and 

site closure. EPA adds that the final GS rule includes a balance of specific criteria to be met by the 

owner or operator and areas of Directorial discretion and considerations for how that discretion would 

be exercised. The Agency believes this balance allows for GS projects to be designed and permitted to 

address the unique, site-specific aspects of each project, while providing consistency in permitting 

across the U.S. 

EPA disagrees that the Class VI requirements are overly stringent; instead, the GS requirements are 

tailored to the unique nature of GS, including the large volumes of CO2 injected, its buoyancy and 

potential corrosivity in the presence of water, and impurities in the CO2 stream. EPA believes these 

tailored requirements are more appropriate than Class I or Class II requirements. Please see the 

remainder of EPA's responses to this comment for further details. For additional information on EPA's 

final regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 5000 2.8 Proposed Well Plugging and Post-Injection 

Site Care Requirements; 5400 2.9 Proposed Financial Responsibility and Long-Term Care Requirements 

Comment: IV. EPA MUST DEVELOP A FLEXIBLE FRAMEWORK TO ADDRESS POSTINJECTION SITE CARE, 

FINANCIAL ASSURANCE, AND LONG TERM LIABILITY THAT ELIMINATES OBSTACLES 

TO 

COMMERCIAL-SCALE DEPLOYMENT OF CCS. 

Numerous studies and commentators have recognized that the principle obstacle 

to commercial-scale deployment of CCS is regulatory uncertainty over the 

capture, transport, injection, and storage of CO2. As stated by a recent GAO 

report: 

The IPCC, two federal advisory committee reports, and many stakeholders we 

contacted agreed that key regulatory and legal issues will need to be addressed 

Commenter Name: Brianne Metzger Letter ID: 0151

Commenter Organization: Spectra Energy Corp Comment ID: 21877

643
if CCS is to be deployed at commercial scale. Among these issues are (1) 

confusion over the rules for injecting large volumes of CO2, (2) long-term 

liability issues concerning CO2 storage and potential leakage, (3) how property 

ownership patterns may affect CO2 storage, and (4) how the Clean Air Act will 

apply to facilities that capture CO2. - EPA’s 2007 UIC workshop, attended by 

more than 200 stakeholders, revealed liability associated with unintended 

migration of injected CO2 to be a critical concern. Similarly, 19 of the 20 

stakeholders we interviewed told us that liability related to CO2 storage was a 

large or very large barrier to deployment of CCS at a commercial scale, with 

some noting that liability concerns have already negatively impacted companies’ 

ability to initiate CCS projects. For example, two stakeholders reported that 

these concerns had already made it difficult to obtain insurance for CCS 

projects. They noted specifically that insurers have difficulty writing 

insurance policies because of uncertainties associated with and limited data 

available for CCS, while another added that investors will not support projects 

like CCS if they expose them to unlimited and undefined long-term liabilities, 

especially when future revenue streams are uncertain.[14] 

The promise of CCS as a strategy to address climate change and promote national 

energy security hinges on resolving this regulatory uncertainty in a way that 

does not place an unreasonable burden on site owners and operators that would 

effectively prevent the development of commercial-scale CCS projects in the 

United States. The EPA has the authority under SDWA and the UIC Program to 

create a flexible framework to address issues such as post-injection site care, 

financial assurance, and long-term liability in a manner that places enough 

responsibility on owners and operators to ensure that all applicable best 

practices are followed, but not so much that it becomes virtually impossible to 

secure the requisite financing and insurance needed for CCS projects to be 

commercially viable. 

The potentially unique challenge of resolving the regulatory uncertainty 

currently inhibiting the development of CCS projects, if done with inadequate 

attention to existing market dynamics and economic realities, likely will 

preclude any commercial-scale deployment of CCS and undermine its effectiveness 

as a strategy to reduce greenhouse gas emissions. Addressing the regulatory 

uncertainty surrounding post-injection site care, financial assurance, and 

long-term liability effectively boils down to four overarching questions 

confronting entities involved in the capture, transport, injection, and storage 

of CO2: (1) length of the post-injection site care time period; (2) aspects of 

post-injection site care for which entities will be responsible; (3) 

availability and suitability of different risk management instruments for 

meeting financial assurance requirements; and (4) permanent transfer of all 

liability to the State. Spectra’s comments on post-injection site care, 

financial assurance, and long-term liability focus broadly on these issues. 

14 GAO Report, Climate Change, Federal Actions Will Greatly Affect the 

Viability of Carbon Capture and Storage As a Key Mitigation Option, Report to 

the Chairman on the Select Committee on Energy Independence and Global Warming, 

House of Representatives, GAO-08-1080, September 2008, at 23, 25. See also 

Capturing King Coal: Deploying Carbon Capture and Storage Systems in the US at 

Scale, WORLD RESOURCES INSTITUTE (2008) at 24 ("In the event of an accident or 

644
damage years after the well is closed, who is financially and legally 

responsible? Current law and policy is unclear on this matter, and more 

generally on the matter of responsibility for long-term measuring and 

monitoring of the site. In particular, the degree to which private parties 

remain responsible, or the government assumes a measure of responsibility, is 

important."). 

Response: EPA acknowledges the commenter¿s request for certainty regarding post-injection site care 

(PISC) requirements for GS wells. However, EPA believes that a certain amount of flexibility is 

appropriate for setting the PISC timeframe, given the variety of circumstances that may occur at GS 

sites. The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a combination 

of a fixed timeframe and a performance standard approach. The GS rule offers owners or operators 

flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to 

shorten or lengthen the PISC timeframe during the post-injection period based on site-specific data, 

pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well 

owner or operator to demonstrate, during the permitting process based on substantial data, that an 

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to 

requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize site-specific 

data, and be based on pressure monitoring and USDW impacts. 

EPA recognizes that there are challenges associated with financial responsibility for GS projects. 

However, the Agency believes that in order to protect USDWs from endangerment under the SDWA 

operators must demonstrate under §146.85 that financial resources are available to plug the injection 

well and provide PISC when injection begins. 

Under the final GS rule owners or operators may choose from a variety of financial instruments to 

demonstrate that they meet the financial responsibility requirements under §146.85, provided the 

Director determines that the demonstration is adequate to pay for each activity for which financial 

responsibility is required. EPA is developing guidance (available on EPA¿s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm) to help owners or operators, 

permitting authorities, and third parties choose and evaluate appropriate financial methods. 

Under SDWA authority, owners or operators of injection wells must ensure protection of USDWs from 

endangerment and are subject to liability for enforcement under the Act. The final rule requires an 

owner or operator to conduct monitoring as specified in the Director-approved PISC and site closure 

plan following the cessation of injection until he or she can demonstrate that the GS project no longer 

poses an endangerment to USDWs. 

Once an owner or operator has met all requirements under Part 146 for Class VI wells and the Director 

has approved site closure pursuant to §146.93, the owner or operator will generally no longer be subject 

to enforcement for regulatory noncompliance. Furthermore, the financial instrument required under 

§146.85 will be released if it was not used. However, even if site closure is approved, an owner or 

operator may be held liable for regulatory noncompliance (e.g., violation of 40 CFR 144.12) in certain 

circumstances. For example, an owner or operator may be held liable for noncompliance even after site 

645
closure if the Director relied on erroneous information (e.g., erroneous modeling data) provided by the 

owner or operator when approving site closure. 

Additionally, an owner or operator may always be subject to any action, such as administrative orders or 

civil actions, the Administrator deems necessary under §1431 of the SDWA after site closure if there is 

unanticipated migration towards or into a USDW that causes or threatens imminent and substantial 

endangerment to public health. If the owner or operator fails to comply with the order, he or she may be 

subject to a civil penalty for each day such violation occurs or failure to comply continues. 

The Agency clarifies that Class VI well permits may be transferred to another owner or operator 

pursuant to §144.38 whereby all potential liabilities associated with meeting the requirements of that 

permit are transferred to that new owner or operator. 

Furthermore, after site closure an owner or operator may remain liable under tort and other remedies, or 

under other federal statutes including, but not limited to, the Clean Air Act, 42 U.S.C. §§ 7401-7671; 

CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. EPA does not have authority to 

transfer SDWA or other legal liability for Class VI wells to the State or federal government or a thirdparty fund. See the final rule preamble for further discussion of EPA's final approach. 

Other EPA Comment Codes and Descriptions: 1530 1.2.3.1 State regulatory efforts on GS (seeking 

comment) 

Comment: given the potential size, scope and impact of the sequestration operations. Our 

main concerns focus on states being given sufficient flexibility to regulate 

such a program efficiently and effectively. 

Response: EPA clarifies that SDWA, under section 1422(b)(3)(9)(A), requires that the regulations of 

the Administrator "permit or provide for varying geologic, hydrological, or historical conditions in 

different states and in different areas within a state." In the final GS rule, EPA has provided the Director 

discretion in applying the GS requirements, taking into account varying conditions, particularly with 

regard to the evaluation of site characteristics. 

For additional information, please see the discussion of EPA’s Final Regulatory Approach in the 

preamble to the final GS rule and the section entitled, “How Does This Action Affect UIC Program 

Implementation?" 

Comment: 1. South Dakota recommends that more flexibility be given to the type and 

location of formations where CO2 can be sequestered. At this point EPA is 

Response: EPA agrees that permitting decisions for GS wells should be based on site-specific factors. 

The GS rule requires owners or operators to submit, and Directors to consider, extensive site-specific 

data, specified at §146.82, to demonstrate that a site is suitable for GS. Additionally, many of the permit 

requirements for GS wells are established through individualized site-specific plans for AoR and 

corrective action, testing and monitoring, and injection well plugging and post-injection site care and 

Commenter Name: Steven Pirner Letter ID: 0153

Commenter Organization: South Dakota Department of Environment and Natural 

Resources

Comment ID: 

22134

Commenter Name: Steven Pirner Letter ID: 0153

Commenter Organization: South Dakota Department of Environment and Natural 

Resources

Comment ID: 

22135

646
site closure. EPA adds that the final GS rule includes a balance of specific criteria to be met by the 

owner or operator and areas of Directorial discretion and considerations for how that discretion would 

be exercised. The Agency believes this balance allows for GS projects to be designed and permitted to 

address the unique, site-specific aspects of each project, while providing consistency in permitting 

across the U.S. 

Other EPA Comment Codes and Descriptions: 1410 1.2.1 Comments in support of EPA/rulemaking 

Comment: EPA is commended for taking this action that begins the process of providing 

regulatory clarity to a complex and important topic. In its decision process, 

EPA needs to consider the importance of CCS to the success of the nation's 

overall climate change, energy independence and economic growth strategies. Any 

rule for geologic storage of CO2 needs to provide an unambiguous framework that 

promotes the development and deployment of CCS while protecting the environment. 

Also, given the current state of experience in geologic sequestration, any 

prescription needs to be flexible and adaptive. 

Response: While EPA agrees with commenters that a stable, predictable, nationally consistent, and 

workable regulatory framework is important, EPA stresses that the focus of the GS rule is to ensure that, 

where GS is deployed, it is conducted in a manner that protects USDWs from endangerment. 

EPA agrees that an adaptive and flexible approach is appropriate. To protect USDWs from 

endangerment and meet the potentially fast pace of GS deployment, EPA is using an adaptive approach 

to regulating CO2 injection for GS. The Agency plans to collect and review data every six years on GS 

projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. An adaptive approach will allow regulatory development to proceed in time to meet the 

current and future demands for Class VI permits while EPA continues to gather data from pilot projects 

and other research as it becomes available. 

Comment: this technology is still years down the road. At this point, we ask EPA to lay 

out a performance based regulatory framework that can be readily adapted to new 

information and technology gained from these yet to be started large scale 

demonstrations. Also, the requirements should not be so restrictive and costly 

to make carbon sequestration not a viable option for implementation. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

To address the comment that the rule should accommodate future technological developments related to 

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23754

Commenter Name: Skiles Boyd Letter ID: 0160

Commenter Organization: DTE Energy Comment ID: 21270

647
GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Comment: Comments Regarding UIC Regulations 

1. Because of the difficulty of regulating future activities, we urge EPA to 

continue to use a "performance based" approach in developing the requirements 

for Class VI UIC wells. This way, rules can be readily adjusted and fine-tuned 

as industry and regulators alike gain experience with large-scale CO2 

sequestration. 

2. Because information and technology related to carbon sequestration will 

evolve as industry and regulators gain experience with CCS, San Miguel urges EPA 

to resist placing blanket prohibitions or detailed operational specifications in 

the Final Rule. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Comment: First, EPA's regulations must reflect a balanced approach between the need to 

protect underground drinking water supplies and the need to avoid regulations 

that ultimately discourage CCS. While the proposed rule attempts to provide 

flexibility in the form of director discretion, in several areas the proposed 

rule establishes default provisions that would apply to all GS sites. EPA must 

be careful to recognize that each storage site will present unique 

characteristics. Rather than imposing default provisions on all sites, EPA 

should utilize performance-based standards in the regulatory program. 

Response: EPA agrees that permitting decisions for GS wells should be based on site-specific factors. 

Commenter Name: Joseph Eutizi Letter ID: 0161

Commenter Organization: San Miguel Electric Cooperative, Inc Comment ID: 21285

Commenter Name: Sandi Tabor Letter ID: 0162

Commenter Organization: Lignite Energy Council (LEC) Comment ID: 21294

648
The GS rule requires owners or operators to submit, and Directors to consider, extensive site-specific 

data, specified at §146.82, to demonstrate that a site is suitable for GS. Additionally, many of the permit 

requirements for GS wells are established through individualized site-specific plans for AoR and 

corrective action, testing and monitoring, and injection well plugging and post-injection site care and 

site closure. EPA adds that the final GS rule includes a balance of specific criteria to be met by the 

owner or operator and areas of Directorial discretion and considerations for how that discretion would 

be exercised. The Agency believes this balance allows for GS projects to be designed and permitted to 

address the unique, site-specific aspects of each project, while providing consistency in permitting 

across the U.S. 

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

Comment: Principles for new regulations 

§ Because of the difficulty of regulating future activities, we urge EPA to 

continue to use a "performance based" approach in developing the requirements 

for Class VI UIC wells. This way, rules can be readily adjusted and fine-tuned 

as industry and regulators alike gain experience with large-scale CO2 

sequestration. 

§ Because information and technology related to carbon sequestration will evolve 

as industry and regulators gain experience with CCS, NRECA urges EPA to resist 

placing blanket prohibitions or detailed operational specifications in the Final 

Rule. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Commenter Name: James Stine Letter ID: 0163

Commenter Organization: National Rural Electric Cooperative Association 

(NRECA)

Comment ID: 

21313

Commenter Name: James Stine Letter ID: 0163

Commenter Organization: National Rural Electric Cooperative Association 

(NRECA)

Comment ID: 

21320

649
Comment: COMMENTS 

1. NRECA acknowledges EPA's efforts to use a "performance-based" approach and to 

build flexibility into the Proposal, including the use of directorial discretion 

and the provision for forthcoming guidance to clarify other requirements. In 

general, we agree that these methods will help create a regulatory framework 

that can evolve as information and technological advancements are gained in the 

field of carbon capture and sequestration. It is important, however, that any 

directorial discretion be clearly defined and limited; this can be achieved 

while still maintaining a rule that is flexible and avoids unnecessary 

prohibitions. In addition, guidance on any aspect of the Final Rule (for 

example, clarification of requirements for financial assurance mechanisms) must 

be developed in accordance with OMB’s Good Guidance Practices Bulletin, which 

directs that notice and comment be provided on "economically significant" 

guidance documents. See 72 Fed. Reg. 3432, 3438 (Jan. 25, 2007). 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

EPA is developing guidances for States that describe the process of applying for and receiving primary 

enforcement authority (primacy) for GS Class VI wells under Section 1422 of SDWA, as well as the 

technical and administrative issues on developing GS regulations that are the equivalent of minimum 

federal criteria and requirements. The guidance will describe areas of Directorial discretion and 

considerations for how that discretion would be exercised. This guidance will be available on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. EPA has taken OMB’s 

Good Guidance Manual into consideration as it developed the guidance. OMB’s Good Guidance Manual 

establishes policies and procedures for the development, issuance, and use of significant guidance 

documents by Executive Branch departments and agencies. 

Comment: EPA, in this rulemaking, must establish a cost-effective and environmentally 

sound regulatory program to cover a range of operations in order that the 

technology will be commercially deployed. To meet this challenge and establish a 

workable regulatory framework over the coming decades for the long-term storage 

of CO2, it is imperative that EPA take care to craft the regulations with 

flexibility so that they may be fine-tuned as industry and regulators alike gain 

experience with the large-scale CO2 sequestration contemplated by this 

rulemaking. APPA applauds EPA’s efforts to build such flexibility mechanisms 

into the Proposed Rule, including the use of state directorial discretion and 

the provision for forthcoming guidance to clarify other requirements. APPA 

agrees that both of these methods will help create a regulatory framework that 

can evolve as information and technological advancements are gained in the field 

of carbon capture and sequestration. 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23394

650
Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

EPA clarifies that the intent of the Class VI regulations is not to promote or encourage the use of GS, 

but, instead to ensure protection of USDWs where GS technologies are deployed. EPA is using an 

adaptive approach to regulating GS under the UIC Program. Even after finalization of the GS regulation, 

EPA plans, every six years, to collect and review project data on GS research projects to determine 

whether the appropriate amount and types of information and appropriate documentation are being 

collected, and to determine if modifications to the requirements are appropriate or necessary. 

Comment: · Because the technology described in the Proposal will not be commercially and 

widely deployed (in states without oil and gas production) for perhaps as long 

as 30 years, the Final Rule must be flexible enough to accommodate developments 

in information and technology related to carbon sequestration. These 

developments could reflect knowledge that affirms the technology and minimizes 

any cautions or concerns expressed by APPA regarding USDW risk, liability, etc. 

· APPA is really not qualified to comments on site selection or well 

construction or injection procedures. APPA defers to decision making by the 

state directors (or EPA in the case of non-delegated states on these aspect). 

EPA’s Final Rule should keep as many options regarding site and method of 

injection available, subject to the standard that any CO2 GS be protective of 

underground sources of drinking water ("USDWs"). 

Response: As described above, EPA believes the rule provides flexibility to address site-specific 

conditions. EPA is using an adaptive approach to regulating GS under the UIC Program. 

Comment: API shares the same goal as EPA: to develop rules that facilitate the safe, 

secure longterm storage of CO2. API is concerned though that by being overly 

restrictive in designing the new well class, the proposed rule will hinder the 

deployment of CCS and could have the unanticipated consequence of hindering the 

innovations that could improve both well security and performance. CCS is likely 

to be of one of the core technologies that could help to ensure that we can 

continue to produce the clean energy society demands. API would be eager to 

Response: EPA agrees that permitting decisions for GS wells should be based on site-specific factors. 

The GS rule requires owners or operators to submit, and Directors to consider, extensive site-specific 

data, specified at §146.82, to demonstrate that a site is suitable for GS. Additionally, many of the permit 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23402

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24132

651
requirements for GS wells are established through individualized site-specific plans for AoR and 

corrective action, testing and monitoring, and injection well plugging and post-injection site care and 

site closure. EPA adds that the final GS rule includes a balance of specific criteria to be met by the 

owner or operator and areas of Directorial discretion and considerations for how that discretion would 

be exercised. The Agency believes this balance allows for GS projects to be designed and permitted to 

address the unique, site-specific aspects of each project, while providing consistency in permitting 

across the U.S. 

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

Comment: Comments Regarding UIC Regulations 

1. Due to the difficulty and uncertainty of regulating future activities, we 

urge EPA to continue to use a "performance based" approach in developing the 

requirements for Class VI UIC wells. This way, rules can be readily adjusted and 

fine-tuned as industry and regulators alike gain experience with large-scale CO2 

sequestration. It is also important to maintain the flexibility for a site-based 

approach when addressing the requirements for Area of Review evaluations, 

operational monitoring and post injection care and closure periods. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance- or technology-based standards for GS projects, 

EPA is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Comment: 2. Information and technology related to carbon sequestration will evolve as 

industry and regulators gain experience with CCS. GRE feels EPA should resist 

placing blanket prohibitions or detailed operational specifications in the Final 

Rule. 

Response: As described above, the Agency believes that the Class VI requirements balance site-specific 

flexibility with USDW protection. EPA adds that it is using an adaptive approach to regulating GS under 

Commenter Name: Erik Silvola Letter ID: 0171

Commenter Organization: Great River Energy Comment ID: 23440

Commenter Name: Erik Silvola Letter ID: 0171

Commenter Organization: Great River Energy Comment ID: 23441

652
the UIC Program. Even after finalization of the GS regulation, EPA plans, every six years, to collect and 

review project data on GS research projects to determine whether the appropriate amount and types of 

information and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. 

Comment: State Standards, Regulations, Funding, and Primacy Requirements 

State Flexibility Needed: 

The flexible regulatory approach that is built into the proposed rule appears to 

adequately provide for state implementation efforts to address site specific 

circumstances and assure that the rule is implemented toward the highest degree 

of protection for USDWs. However, the rule should also allow for state 

flexibility with regard to existing state standards and regulations, if they are 

more stringent (i.e., regarding well construction requirements) than the Federal 

rule. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

In response to the comment that States with primacy be able to develop “performance-based standards,” 

the Agency clarifies that States, Tribes, and Territories can develop requirements for Class VI and 

submit primacy applications (under Section 1422 of the SDWA) for review and approval by EPA as 

long as the requirements are as stringent as or more stringent than the Federal minimum requirements. 

Comment: • Because the technology described in the Proposal will not be commercially 

deployed for a number of years, the Final Rule must be flexible enough to 

accommodate developments in information and technology related to carbon 

sequestration. Similarly, because there is likely to be a significant amount of 

CO2 available for sequestration under the Program, the Final Rule should avoid 

arbitrary absolutes or blanket prohibitions regarding site selection or well 

construction or injection procedures. The Final Rule should keep available as 

many options as possible for site selection and method of injection, subject 

always to the standard that any CO2 GS be protective of USDWs. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement siteCommenter Name: James Taft Letter ID: 0172

Commenter Organization: Association of State Drinking Water Administrators 

(ASDWA)

Comment ID: 

23456

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23461

653
specific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Comment: • Because carbon sequestration technology is still developing and the 

characteristics and limitations of CO2 GS projects will vary greatly from one 

site to another, it is essential to incorporate performance-based standards into 

the Final Rule, leading to a site-tailored approach to requirements for Area of 

Review ("AoR") reevaluation and post-injection site care and closure periods. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Other EPA Comment Codes and Descriptions: 2400 1.8 Comments on EPA's adaptive rulemaking 

process 

Comment: 2. Necessity of a Flexible Regulatory Scheme 

USWAG applauds the efforts EPA has taken thus far to instill certainty and 

transparency in the future Class VI CO2 regulatory regime. 73 Fed. Reg. at 

43496. At the same time, it is imperative that the Final Rule reflect the 

challenges inherent in crafting regulations for commercial CO2 injection 

activities when large-scale commercial operations are only at the nascent stage. 

The challenge confronting EPA in this rulemaking is to establish a costeffective and environmentally protective regulatory program to cover a range of 

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23462

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23473

654
operations for which the technology will not be commercially deployed for a 

number of years. 

To meet this challenge, it is critical that the Final Rule emphasize 

performance-based rules that can be readily adjusted and fine-tuned as industry 

and regulators alike gain experience with large-scale CO2 sequestration. USWAG 

acknowledges EPA's efforts to build flexibility mechanisms into the Proposal, 

including provisions for directorial discretion and the suggestion that 

forthcoming guidance may be used to clarify other requirements. In general, we 

agree that these methods will help create a regulatory framework that can evolve 

as information and technological advancements are gained in the field of carbon 

capture and sequestration. It is important, however, that any directorial 

discretion be clearly defined and limited; this can be achieved while still 

maintaining a rule that is flexible and avoids unnecessary prohibitions. In 

addition, guidance on any aspect of the Final Rule (for example, clarification 

of requirements for financial assurance mechanisms) must be developed in 

accordance with OMB's Good Guidance Practices Bulletin, which directs that 

notice and comment be provided on "economically significant" guidance 

documents.[FN2] See 72 Fed. Reg. 3432, 3438 (Jan. 25,2007). 

Because information and technology related to carbon sequestration will develop 

as industry and regulators gain experience with CCS, USWAG urges EPA to avoid 

blanket prohibitions or arbitrary absolutes in the Final Rule. We agree that the 

appropriate standard underlying the technical requirements for CO2 GS wells is 

the protection of USDWs. However, because it is difficult to know at this point 

what methods or technology will be developed for injection and long-term storage 

of CO2 in a manner that is protective of USDWs - and because there is sure to be 

demand for significant capacity for CO2GS - EPA should not prematurely preclude 

the use of specific types of sites or methods for Class VI CO2 injection. The 

Final Rule should leave the door open for a range of injection sites and methods 

(some of which are unknown or not yet fully understood), provided that the Owner 

or Operator can show that the injection and storage will be protective of USDWs. 

[FN2] The Bulletin defines "economically significant guidance document" as "a 

significant guidance document that 'may reasonably be anticipated to lead to' an 

annual effect on the economy of $100 million or more or adversely affect in a 

material way the economy or a sector of the economy." See 72 Fed. Reg. at 3435. 

Response: EPA recognizes the importance of providing clear, flexible, scalable, and appropriate 

regulations. The final GS rule includes a balance of specific criteria to be met by the owner or operator 

and areas of Directorial discretion. The Agency believes this balance allows for GS projects to be 

designed and permitted to address the unique, site-specific aspects of each project, while providing 

consistency in permitting across the U.S. EPA is developing guidances for states that describe the 

process of applying for and receiving primary enforcement responsibility (primacy) for GS Class VI 

wells under Section 1422 of SDWA, as well as the technical and administrative issues on developing GS 

regulations that are the equivalent of minimum federal criteria and requirements. The guidance will 

provide recommended approaches for how permitting authorities may exercise Director's discretion. The 

guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA also agrees that an adaptive approach to rulemaking for GS is appropriate. The Agency plans to use 

655
such an approach to ensure that USDWs are protected from endangerment and meet the potentially fast 

pace of GS deployment. EPA believes that an adaptive approach will allow regulatory development to 

proceed in time to meet the current and future demand for Class VI permits while recognizing the need 

to: continue to gather data from pilot projects and other research as it becomes available; and to enhance 

understanding of the technical and administrative aspects of GS deployment, operation, and technology 

developments. EPA plans, every six years, to collect and review data on GS projects to determine 

whether the appropriate amount and types of information and appropriate documentation are being 

collected, and to determine if modifications to the requirements are appropriate or necessary. 

EPA disagrees that the GS rulemaking needs to be based solely on large-volume projects. While 

studying the impact of injecting large volumes of CO2 is important, data on other aspects of GS—

including the buoyancy and corrosivity of CO2 in the presence of water, the potential presence of 

impurities in captured CO2, and its mobility within subsurface formations—informed the rulemaking. 

Comment: Proposed requirements for well drilling, construction, and other characteristics 

With respect to many of the proposed requirements, USWAG believes it is 

imperative to craft the Final Rule as a flexible instrument that establishes 

performance-based standards, which can be achieved through a variety of methods 

as long as there is a sound technical basis underlying each method and assuring 

its protection of USDWs. See id. at 43508-09. Because this technology is years 

from commercial deployment and is still developing, the Final Rule should allow 

for the use of technologies and methods that are not yet developed or are only 

in the beginning stages, provided that they are shown to be protective of USDWs. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Other EPA Comment Codes and Descriptions: 3840 2.3.2 Horizontal well drilling techniques 

(seeking comment) 

Comment: This logic also applies to argue against a prohibition on any type of well 

drilling, whether horizontal, vertical, or angled. Id. at 43509. There will 

likely be a need to maximize capacity for CO2 GS, and it would be premature at 

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23491

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23492

656
this point to impose a blanket prohibition on any type of well drilling without 

knowing whether that drilling could be done in a manner that is protective of 

USDWs. 

Response: In the final rule, EPA allows the use of horizontal wells at GS projects. In the proposed rule, 

EPA sought comment on the appropriateness of horizontal drilling techniques for Class VI wells, and 

commenters representing energy companies, electric utilities, the oil and gas industry, CCS associations, 

states, and the public, unanimously supported the concept and provided many reasons why horizontal 

wells could be beneficial at GS sites. Based on an evaluation of these comments and additional research 

by EPA, the Agency has concluded that horizontal wells that are properly constructed, logged, and 

tested for mechanical integrity (i.e., to meet the requirements of the GS rule) can ensure the protection of

USDWs from endangerment. 

Comment: Flexibility 

EPA states throughout the proposal that flexibility in the application of the 

rule is essential to balancing the protection of USDW against the need to 

facilitate CCS development and commercialization. Accordingly, Dominion urges 

EPA to recognize that no two GS sites are identical and that requirements that 

may be appropriate for one site may be prohibitive for another site. While 

directorial discretion is a useful mechanism to ensure flexibility in the Final 

Rule, such discretion must be clearly defined and limited. 

Response: EPA agrees that permitting decisions for GS wells should be based on site-specific factors. 

The GS rule requires owners or operators to submit, and Directors to consider, extensive site-specific 

data, specified at §146.82, to demonstrate that a site is suitable for GS. Additionally, many of the permit 

requirements for GS wells are established through individualized site-specific plans for AoR and 

corrective action, testing and monitoring, and injection well plugging and post-injection site care and 

site closure. EPA adds that the final GS rule includes a balance of specific criteria to be met by the 

owner or operator and areas of Directorial discretion and considerations for how that discretion would 

be exercised. The Agency believes this balance allows for GS projects to be designed and permitted to 

address the unique, site-specific aspects of each project, while providing consistency in permitting 

across the U.S. 

EPA is developing guidances for States that describe the process of applying for and receiving primary 

enforcement authority (primacy) for GS Class VI wells under Section 1422 of SDWA, as well as the 

technical and administrative issues on developing GS regulations that are the equivalent of minimum 

federal criteria and requirements. The guidance will describe areas of Directorial discretion and 

considerations for how that discretion would be exercised. This guidance will be available on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: Adaptability 

The Agency should strive to anticipate future statutory and regulatory 

developments in the climate change arena so that any rulemaking has a reasonable 

Commenter Name: Pamela Faggert Letter ID: 0175

Commenter Organization: Dominion Comment ID: 23515

Commenter Name: Pamela Faggert Letter ID: 0175

Commenter Organization: Dominion Comment ID: 23516

657
chance of facilitating such developments. EPA can and should consider how its 

UIC rulemaking will fit with foreseeable features of potential future regimes 

and how rules can be drafted to complement such features to the extent possible. 

Additionally, because it is difficult to know at this point what methods or 

technology will be developed for injection and long-term storage of CO2, coupled 

with projected demands for capacity, EPA should not prematurely preclude the use 

of specific types of sites or methods for Class VI CO2 injection. 

Response: EPA is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Comment: "Tailored requirements," as opposed to more general or more specific 

requirements, are preferable as they provide adequate protection while 

simultaneously allowing for the flexibility to address local geology and sitespecific conditions and to embrace evolving technology. Tailored requirements 

should be brought to bear when considering the nine specific topical areas for 

addressing the proposed Class VI UIC requirements: 

1. Geologic Siting; 

2. Area of Review and Corrective Action; 

3. Injection Well Construction; 

4. Injection Well Operating; 

5. Mechanical Integrity Testing; 

6. Plume and Pressure Front Monitoring; 

7. Recordkeeping and Reporting; 

8. Well Plugging, Post-Injection Site Care, and Site Closure; and 

9. Financial Responsibility and Long-term Care. 

Response: EPA agrees that permitting decisions for GS wells should be based on site-specific factors. 

The GS rule requires owners or operators to submit, and Directors to consider, extensive site-specific 

data, specified at §146.82, to demonstrate that a site is suitable for GS. Additionally, many of the permit 

requirements for GS wells are established through individualized site-specific plans for AoR and 

corrective action, testing and monitoring, and injection well plugging and post-injection site care and 

site closure. EPA adds that the final GS rule includes a balance of specific criteria to be met by the 

owner or operator and areas of Directorial discretion and considerations for how that discretion would 

be exercised. The Agency believes this balance allows for GS projects to be designed and permitted to 

address the unique, site-specific aspects of each project, while providing consistency in permitting

Commenter Name: Kenneth Nemeth Letter ID: 0176

Commenter Organization: Southern States Energy Board Comment ID: 23541

658
across the U.S. Please see the final rule and preamble for additional information on EPA's final 

regulatory approach. 

Comment: 2. Avoidance of one-size-fits-all approaches. As currently proposed, EPA‘s 

regulations contain a number of default provisions that would apply universally 

to projects, at least as a matter of initial presumption. Rather than imposing 

default provisions, those portions of the rulemaking that address inherently 

site-specific issues should allow for site-specific, performance-based 

determinations as part of the permitting process. The geologic variability 

involved in different conceivable GS projects needs to be taken into account in 

issues ranging from site characterization to area of review (AOR) to containment 

requirements. 

Response: EPA believes that the Class VI requirements balance site-specific flexibility with USDW 

protection. Rather than setting performance or technology-based standards for GS projects, EPA is 

adopting a flexible approach, where operators of GS projects would develop and implement site-specific 

plans for delineating the AoR, testing and monitoring the site, performing corrective action, and postinjection site care. EPA believes that the plans—which would be reviewed and approved by the Director 

and periodically updated throughout the life of the project—promote an ongoing dialogue between the 

operator and the Director that will encourage use of the most appropriate technologies for a particular 

project. Please see the final rule and preamble for additional information on EPA's final regulatory 

approach. 

Comment: 3. Importance of limits on discretion. EEI recognizes that in order to allow 

for effective site-specific determinations and to maintain essential regulatory 

flexibility, some amount of discretion must be vested in the UIC program 

director. At the same time, such discretion should be bounded by the inclusion 

of relevant and appropriate considerations for making necessary determinations. 

In general, the rules should establish with sufficient clarity the factors to be 

taken into account and leave the precise determinations to the permit process. 

Response: EPA is developing guidances for States that describe the process of applying for and 

receiving primary enforcement authority (primacy) for GS Class VI wells under Section 1422 of 

SDWA, as well as the technical and administrative issues on developing GS regulations that are the 

equivalent of minimum federal criteria and requirements. The guidance will describe areas of Directorial 

discretion and considerations for how that discretion would be exercised. This guidance will be available 

on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: Siting requirements should reflect that conditions affecting risk differ by 

site. They need to be tailored to the actual risks presented by specific sites. 

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23570

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23571

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23853

659
EOR is a well developed technique and there is now a history through which its 

risks can be assessed. This differs from injection for long-term storage in deep 

saline formations or unmineable coal seams. with which there is little 

experience, particularly on the massive scale (e.g., a million or more tons per 

year per plant) envisioned for the future. For CCS to be a viable long-term 

strategy, policy must encourage development of data about these sites, new 

technology. and new practices. 

Response: EPA agrees with the commenter that every site (and the risk posed) is unique. EPA agrees 

that site characterization should be site-specific, particularly in light of the variety of geologic settings in 

which GS may be employed. EPA believes that, while there is a large amount of required information, 

the owner or operator is given flexibility in determining what methods are used to demonstrate the 

suitability of a potential site. EPA envisions an ongoing dialogue between the Director and the owner or 

operator during the permitting process (as well as throughout the operation of the site). 

Comment: specifics that remain to be dealt with. With respect to suggested modifications, 

I find that the draft regulations are overly prescriptive on several points and 

not sufficiently performance based. With respect to some specific requirements, 

the objectives are not well defined such that required performance would be 

difficult to determine. I would urge the U.S. EPA to take all comments received 

and reissue a set of revised proposed regulations for further comment before 

finalizing Class VI regulations. My comments address specific points in the 

draft regulations, as outlined below. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Comment: - The final rule must be flexible and structured such that it has the ability to 

respond appropriately to the development of future carbon sequestration 

technologies. In this regard, performance-based standards allowing for a site 

tailored approach are critical. 

Response: EPA is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23617

Commenter Name: Scott Davis Letter ID: 0187

Commenter Organization: Arizona Public Service Company Comment ID: 25221

660
Other EPA Comment Codes and Descriptions: 2400 1.8 Comments on EPA's adaptive rulemaking 

process 

Comment: Recognizing that a great deal of this technology is currently in development and 

will not be commercially deployed for several years, it is vital that the final 

rule, if necessary, include reasonable performance based regulations that can be 

swiftly adjusted and finetuned as experience is gained in large-scale CO2 GS. 

The promulgation of this rule is only but the first step in the establishment of 

a regulatory framework to support the implementation of GS as the technology is 

scaled up from the current experimental stage to fully operational wells, 

considerable experience will be gained that would help further identify areas 

where adjustments to the rules would be necessary. Therefore, we recommend a two 

phase regulatory approach. The first phase would be to address initial projects 

where operational experience and familiarity with carbon injection and storage 

can be gained. That knowledge, including lessons learned from the both the 

technical and regulatory perspective, could then be utilized to develop a second 

phase rule that would more likely be able to provide a better balance between 

risks with regulatory requirements. 

Response: EPA agrees that an adaptive approach to the UIC GS rulemaking is appropriate. The Agency 

plans to use such an approach to ensure that USDWs are protected from endangerment and meet the 

potentially fast pace of GS deployment. EPA believes that an adaptive approach will allow regulatory 

development to proceed in time to meet the current and future demand for Class VI permits while 

recognizing the need to: continue to gather data from pilot projects and other research as it becomes 

available; and to enhance understanding of the technical and administrative aspects of GS deployment, 

operation, and technology developments. 

EPA plans, every six years, to collect and review data on GS projects to determine whether the 

appropriate amount and types of information and appropriate documentation are being collected, and to 

determine if modifications to the requirements are appropriate or necessary. 

EPA disagrees that the GS rulemaking needs to be based solely on large-volume projects. While 

studying the impact of injecting large volumes of CO2 is important, data on other aspects of GS—

including the buoyancy and corrosivity of CO2 in the presence of water, the potential presence of 

impurities in captured CO2, and its mobility within subsurface formations—informed the rulemaking. 

Other EPA Comment Codes and Descriptions: 1260 1.1.1.5 More certainty/stringency is needed 

Comment: 4. For an activity covering such a diverse geographic, geologic, and commercial 

spectrum as GS, NiSource believes it is essential to incorporate considerable 

regulatory flexibility. However, some relatively high minimum standards of 

technical requirements should be established in key areas. While this may sound 

contradictory, NiSource's observation is that firmly addressing those few real 

risks will ultimately pay significant dividends by preventing a few "bad" 

projects from being developed that ultimately lead to an avoidable incident that 

taints the entire industry. These issues are addressed below. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

Commenter Name: Daniel Plath Letter ID: 0188

Commenter Organization: NiSource, Inc. Comment ID: 25226

Commenter Name: Daniel Plath Letter ID: 0188

Commenter Organization: NiSource, Inc. Comment ID: 25232

661
USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Comment: 1. Because of the difficulty of regulating future activities, Oglethorpe urges 

EPA to continue to use a "performance based" approach in developing the 

requirements for Class VI UIC wells. This way, rules can be readily adjusted and 

fine-tuned as industry and regulators alike gain experience with large-scale CO2 

sequestration. 

2. Because information and technology related to carbon sequestration will 

evolve as industry and regulators gain experience with CCS, Oglethorpe Power 

strongly encourages EPA to resist placing blanket prohibitions or detailed 

operational specifications in the Final Rule. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Comment: To achieve its goals for this rulemaking - to address the risks of CO2 injection 

and promote the development of GS - EPA must take a hard look at the need for, 

and practical utility of, each of the requirements it has proposed for CO2 

injection. As further detailed in these Comments, we believe that the proposed 

requirements can and should be streamlined significantly to increase the 

flexibility of the requirements for CO2 injection and reduce the unnecessary 

(and ultimately counterproductive) regulatory burdens the proposed rule would 

impose. We respectfully urge EPA to modify its proposed regulatory approach 

accordingly. 

Commenter Name: G. Graham Holden Letter ID: 0189

Commenter Organization: Oglethorpe Power Corporation Comment ID: 25246

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24318

662
Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Other EPA Comment Codes and Descriptions: 1410 1.2.1 Comments in support of EPA/rulemaking 

Comment: We support EPA’s conclusion that the UIC program provides an appropriate 

framework for regulation of carbon dioxide (CO2) injection for geologic 

sequestration (GS). The UIC program governs a very wide range of underground 

injection activities - including the operation of thousands of existing CO2 

injection wells - and enjoys an extensively documented record of success. The 

program has in many respects been a model for Federal-State cooperation, and has 

benefited from a long history of regulatory and technical discourse among 

agencies and regulators armed with considerable practical experience and 

exceptional technical expertise. While the UIC program is focused on the 

protection of "underground sources of drinking water" (USDWs), this seemingly 

narrow objective is narrow in name only. In fact, the measures the UIC program 

relies upon to protect USDWs - measures designed to ensure that injected 

material remains isolated in the deep subsurface - are by nature sufficient to 

ensure protection of human health and the environment. 

The UIC program currently provides regulations that can be (and are being) 

successfully applied to CO2 injection into oil and gas reservoirs. We also agree 

that it makes sense to develop regulations more specifically designed to address 

CO2 injection in the GS context especially for formations that are not oil and 

gas reservoirs. Such regulations can and should be designed to build on relevant 

UIC program experience, including experience with CO2 injection, and should be 

tailored to address the particular needs for this category of injection 

activity: both the need to protect USDWs and the need to facilitate use of GS as 

a technology for reducing CO2 emissions. Those regulations should follow a 

flexible, performance-based approach that allows regulators to tailor specific 

permit requirements as appropriate based on the broad range of injection sites 

and practices that may be encountered in the GS context and on the body of 

knowledge and experience that will be gained not only from pilot and 

demonstration projects, but from the initial deployment of commercial scale 

geologic sequestration projects. 

Moreover, the safeguards of the UIC program have been adequate to protect USDWs 

of all types, including sole source aquifers, from injection that occurs 

substantially below those aquifers even where that involves drilling through the 

aquifer to construct wells that will inject into deeper formations. These 

drilling activities have not resulted in any significant contamination of sole 

source aquifers and, indeed, have probably served to protect those aquifers by 

avoiding surface disposal operations that would have been more likely to pose 

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24319

663
threats of endangerment to drinking water resources.[FN1] 

[FN1: Each year, industrial facilities and municipal wastewater treatment 

plants generate billions of gallons of hazardous and non-hazardous waste. Class 

I injection wells provide a safe means to remove these wastes from the surface 

environment by isolating them deep below the land surface, away from drinking 

water resources. 

Class I injection wells inject far below the lowermost USDW. Injection zones 

typically range from 1,700 to more than 10,000 feet in depth. The injection zone 

is separated from USDWs by an impermeable "cap" rock called the confining layer, 

along with additional layers of permeable and impermeable rock and sediment that 

separate the injection layer from the USDW. 

http://www.epa.gov/safewater/uic/wells_class1.html] 

Response: EPA acknowledges the comment and believes that the creation of a new injection well class 

(VI) under the existing UIC Program is necessary to enable the use of GS as a climate change mitigation 

technology in a manner that protects USDWs from endangerment. EPA agrees that the UIC Program, 

under the authority of the SDWA, provides a strong framework for regulating injection of CO2 for GS 

and adds that the GS regulation tailors the UIC requirements to address the unique issues associated with 

large-scale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the 

presence of water, the potential presence of impurities in captured CO2, and its mobility within 

subsurface geologic formations. 

EPA agrees that the implementation of the GS rule in a manner that ensures protection of USDWs from 

endangerment is important to establishing a foundation for further advances in the field of CO2 GS. 

EPA acknowledges the need for regulatory certainty: the final GS requirements provide a level of 

certainty by setting forth unique requirements for GS. These requirements include: the tailored AoR 

delineation process at §146.84, the types of monitoring appropriate to GS projects at §146.90 and the 

post-injection site care process at §146.93. For additional information on these requirements, please also 

see the discussion of EPA’s Final Regulatory Approach in the preamble to the final GS rule. 

To protect USDWs from endangerment and meet the potentially fast pace of GS deployment, EPA is 

using an adaptive approach to regulating CO2 injection for GS. The Agency plans to collect and review 

data every six years on GS projects to determine whether the appropriate amount and types of 

information and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. An adaptive approach will allow regulatory development to 

proceed in time to meet the current and future demands for Class VI permits while EPA continues to 

gather data from pilot projects and other research as it becomes available. 

Other EPA Comment Codes and Descriptions: 1210 1.1.1 Comments about the proposed rule; 1420 

1.2.1.1 Support the GS rulemaking 

Comment: Protection of U.S. Drinking Water (USDW) sources is paramount and a central 

requirement of the Safe Drinking Water Act and ConocoPhillips wholeheartedly 

supports high standards for protection of current and potential future USDWs. We 

believe that maintaining focus on several key principles can ensure rulemaking 

that is protective and flexible to allow site specific considerations while 

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23887

664
maintaining cost-effective operations. We applaud EPA's work to that end. We 

support most concepts, elements and details in the proposed requirements, and 

provide our comments to reinforce and amplify a few issues which we believe flow 

from the following important key principles: 

o All UIC well classes have requirements fully designed to protect USDW's. 

o The oil and gas industry's experience with CO2 injection for enhanced oil 

recovery (EOR) provides a track record of USDW protection that can enhance EPA's 

rulemaking. 

Response: EPA believes that the creation of a new injection well class (VI) under the existing UIC 

Program is necessary to enable the use of GS as a climate change mitigation technology in a manner that 

protects USDWs from endangerment. EPA agrees that the UIC Program, under the authority of the 

SDWA, provides a strong framework for regulating injection of CO2 for GS and adds that the GS 

regulation tailors the UIC requirements to address the unique issues associated with large-scale GS 

including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, 

the potential presence of impurities in captured CO2, and its mobility within subsurface geologic 

formations. 

EPA recognizes that the oil and gas industry has decades of experience injecting CO2 for the purpose of 

ER, and that sites used for ER may be suitable for GS and may be among the first GS sites. Some of the 

research that informs the final GS rule was conducted at ER sites. EPA also recognizes that a by-product 

of ER activities is that a certain percentage of the CO2 is trapped in the receiving formation. 

Comment: o Performance standards should focus on containment while allowing for 

flexibility as more is learned about CCS. An approach which is overly 

prescriptive reduces learning, risks delaying the use of newer/better 

alternatives in the future, and can add unnecessary costs. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Comment: FLEXIBLE REGULATORY SCHEME 

Ameren generally supports the creation of Class VI, a new class of injection 

wells for CO2 injection and storage. We also appreciate the attempt that EPA 

has taken to bring "certainty" and "transparency" to the future CO2 underground 

injection regulatory regime. However, it is imperative that the Final Rule be 

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23889

Commenter Name: Paul Pike Letter ID: 0198

Commenter Organization: Ameren Corporation Comment ID: 23938

665
flexible enough to deal with the current investigative phase and when largescale commercial operations are in place. We recognize that GS has significant 

potential to be a major portion of any future CO2 emission reduction scheme, but 

that can only occur if the regulations adapt to the actual hazard posed by the 

technology which may not be fully understood until some time in the future. 

Clearly the Agency understands the need for flexibility by allowing a Director 

to provide guidance on regulatory compliance. We understand that this can allow 

the regulatory framework to evolve; however, there also needs to be some 

definition and limits to that discretion so that the public and regulated 

community can provide comments on that guidance. This means that technical and 

financial aspects are considered in the development of guidance. 

We also recognize that the underlying basis for these regulations is the 

protection of underground sources of drinking water ("USDWs"), but we urges EPA 

to avoid blanket prohibitions or arbitrary absolutes in the Final Rule. It is 

impossible to know what methods or technology will be developed for injection 

and long-term storage of CO2 and the Agency should not prematurely preclude the 

use of specific types of sites or methods for Class VI CO2 injection. The Final 

Rule should allow a range of injection sites and methods, provided that the 

Owner or Operator can show that the injection and storage will be protective of 

USDWs. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

EPA is developing guidances for States that describe the process of applying for and receiving primary 

enforcement authority (primacy) for GS Class VI wells under Section 1422 of SDWA, as well as the 

technical and administrative issues on developing GS regulations that are the equivalent of minimum 

federal criteria and requirements. The guidance will describe areas of Directorial discretion and 

considerations for how that discretion would be exercised. This guidance will be available on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

Comment: emissions. It is critical, therefore, that EPA promulgate flexible regulations 

that can develop as industry and regulators alike gain experience with largescale CO2 sequestration. These regulations should be built around performancebased standards that encourage tailoring of the Program's requirements to the 

geologic and technical needs of a given CO2 GS site. 

Commenter Name: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22154

666
Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Other EPA Comment Codes and Descriptions: 1610 1.3.1 Risks to USDWs 

Comment: Southern Company agrees that the appropriate standard underlying the technical 

requirements to be applied to Class VI wells should be the protection of 

underground sources of drinking water ("USDWs"). See id. at 43497. With this 

standard in mind, it is imperative that EPA fashion the Final Rule with 

sufficient flexibility to meet two primary goals: first, adequately addressing 

the varied geologic conditions of different CO2 GS sites; second, ensuring 

adaptability as industry and regulators gain experience with and information 

regarding CO2 GS. It is important that the Final Rule not exclude the existing 

experience and knowledge gained from current CO2 injection and GS demonstration 

projects. To encourage use of this information, Southern Company supports 

facilitated GS in oil and gas reservoirs with the protection of USDWs and the 

transition of Class II and Class V C02 injection operations to GS. The Final 

Rule should establish a regulatory framework built around the standard of 

protecting USDWs while allowing Directors to issue permits with site-specific 

requirements. An emphasis on site selection, site characterization, and careful 

permit-writing will further strengthen a regulatory scheme that will provide 

protection of USDWs while maximizing the beneficial environmental and economic 

impacts of carbon sequestration. 

Response: EPA notes that the final rule does allow owners or operators flexibility. EPA has taken a 

regulatory approach that promotes USDW protection, incorporates flexibility or the discretion of the 

permitting authority when appropriate, seeks to limit burden on owners or operators and permitting 

agencies, and provides a foundation for national consistency in permitting of GS projects. Many Class 

VI permit requirements must be established through site-specific plans developed by the owner or 

operator and approved by the Director. Consequently, EPA anticipates that owners or operators will 

consult with the Director as they develop, implement, and update these plans. In addition, the final rule 

affords the Director flexibility to approve alternatives to the requirements in some cases. For example, 

the Director may in certain situations modify the length of the post-injection site care period or approve 

an alternative post-injection site care timeframe as part of the permitting process under §146.93, allow 

the use of alternate methods for mechanical integrity testing (if approved by EPA), and waive the 

requirement that wells be designed to inject below the lowermost USDW.

Commenter Name: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22155

667
EPA recognizes that technologies will evolve and improve over time, and for these reasons, the Agency 

is using an adaptive approach to regulate GS injection. The Agency plans, every six years, to collect and 

review data on GS projects to determine whether the appropriate amount and types of information and 

appropriate documentation are being collected, and to determine if modifications to the requirements are 

appropriate or necessary. 

EPA is allowing the construction of Class II and V wells to be re-permitted as Class VI wells pursuant to 

§146.81(c), provided the owner or operator can demonstrate to the Director that the wells were 

engineered and constructed to meet the requirements at §146.86(a) and ensure protection of USDWs, in 

lieu of requirements at §146.86(b) and §146.87(a). EPA believes that allowing for grandfathering of 

select construction requirements, if approved by the Director, will ease the transition to Class VI from an 

existing ER project while protecting USDWs from endangerment. 

EPA clarifies that the GS rule does not promote GS in specific settings, nor does it limit injection 

activities to any specific type of formation, geographic region, or depth. The focus of the GS rule is to 

ensure that, where GS is deployed, it is conducted in a manner that is protective of USDWs. 

Comment: The Proposal includes many provisions for directorial discretion that will help 

ensure that the C02 GS program has the flexibility it needs to succeed. While 

EPA must take care to clearly define the circumstances in which directorial 

discretion may be exercised and to limit the scope of that discretion, in many 

cases this discretion will allow Directors to consider the unique 

characteristics of a given CO2 GS project and adopt a site-specific approach 

that will meet the Final Rule's performance-based standards. 

Response: EPA is developing guidances for States that describe the process of applying for and 

receiving primary enforcement authority (primacy) for GS Class VI wells under Section 1422 of 

SDWA, as well as the technical and administrative issues on developing GS regulations that are the 

equivalent of minimum federal criteria and requirements. The guidance will describe areas of Directorial 

discretion and considerations for how that discretion would be exercised. This guidance will be available 

on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: Operating and Monitoring Requirements 

It is important to reiterate that, because CO2 GS technology is still 

developing, additional information will be gained and technological advancements 

made that will allow Owners or Operators to make use of a broader range of tools 

and methods in Class VI well operation while being fully protective of USDWs. 

For example, our pilot projects as part of the Southeast Carbon Sequestration 

Regional Partnership will lead to greater technical expertise related to CO2 

injection. In addition, the geologic characteristics and limitations of Class VI 

wells will vary significantly from site to site. For these reasons, the Final 

Rule should be flexible enough to incorporate new information and technological 

advancements which, in turn, will help promote a more robust and environmentally 

Commenter Name: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22156

Commenter Name: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22170

668
protective CO2 injection program. To achieve this result, the Final Rule should 

establish performance-based standards and allow permit applicants and Directors 

to work together to fashion a plan that will best suit the needs of a particular 

Class VI site and any associated USDWs. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Other EPA Comment Codes and Descriptions: 1420 1.2.1.1 Support the GS rulemaking 

Comment: Southern Company applauds the EPA's initial efforts to create a clear and 

flexible regulatory scheme that will promote carbon capture and storage 

technology and projects while protecting underground sources of drinking water. 

We appreciate the opportunity to comment on this rulemaking and look forward to 

continuing to work with EPA on this important issue. 

Response: As described above, EPA agrees that the UIC Program, under the authority of the SDWA, 

provides a strong framework for regulating injection of CO2 for GS. 

Comment: As one of the largest coal-fired generators of electricity in the U.S., and as a 

likely user of GS to reduce CO2 emissions, this rulemaking will have a direct 

impact on Duke Energy and its customers. As an entity whose operations will be 

directly impacted by the rule, Duke Energy encourages EPA to provide as much 

flexibility as possible while maintaining appropriate environmental safeguards. 

For example, the characteristics of potential GS sites will be highly variable. 

EPA should provide flexibility by avoiding a one-size-fits-all approach. This 

can be done by incorporating performance-based standards into the final rule 

that would allow for site-specific project design, monitoring and closure. 

Additionally, the technology associated with large scale injection and storage 

of CO2 associated with electricity generation is still developing. EPA should 

provide flexibility by designing the UIC program for GS of CO2 so the program 

requirements can evolve along with the technology over time rather than lock-in 

regulatory requirements that will likely become obsolete. 

Commenter Name: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22177

Commenter Name: Michael Stroben Letter ID: 0209

Commenter Organization: Duke Energy Comment ID: 22677

669
RULE MUST PROVIDE FLEXIBILITY 

The technologies described in the proposal will not likely be commercially 

deployed on a widespread basis for some time; therefore EPA’s rule must remain 

flexible in order to accommodate technological developments related to the GS of 

CO2 as they occur. It is also essential that performance-based standards be 

incorporated into the Final Rule to reflect the fact that the characteristics of 

GS sites will vary widely. The use of performance-based standards rather than a 

one-size-fits-all approach will result in better performing and more costeffective projects because they will have been tailored to a specific site’s 

characteristics. 

Response: EPA believes that the Class VI requirements balance site-specific flexibility with USDW 

protection. Rather than setting performance or technology-based standards for GS projects, EPA is 

adopting a flexible approach, where operators of GS projects would develop and implement site-specific 

plans for delineating the AoR, testing and monitoring the site, performing corrective action, and postinjection site care. EPA believes that the plans—which would be reviewed and approved by the Director 

and periodically updated throughout the life of the project—promote an ongoing dialogue between the 

operator and the Director that will encourage use of the most appropriate technologies for a particular 

project. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Comment: captured using commercially available technologies. Due to its inherent carbon 

capture capability, gasification can serve a major role in Carbon Capture and 

Storage (CCS) projects. GTC’s interest in EPA’s proposed regulation derives from 

the importance of CCS to achieving future goals of CO2 emissions reduction while 

using secure and indigenous resources to meet our growing national need for 

chemicals, fertilizers, liquid fuels, hydrogen, and electricity. 

EPA is commended for taking this action that begins the process of providing 

regulatory clarity to a complex and important topic. In its decision process, 

EPA needs to consider the importance of CCS to the success of the nation’s 

overall climate change, energy independence and economic growth strategies. Any 

rule for geologic storage of CO2 needs to provide an unambiguous framework that 

promotes the development and deployment of CCS while protecting the environment. 

Also, given the current state of experience in geologic sequestration, any 

prescription needs to be flexible and adaptive. In addition to regulatory 

clarity, climate change policy will be needed to define a value for CO2 in order 

to drive deployment of CCS. After policy, cost will determine how quickly and 

widely CCS can be deployed. Currently, the value of CO2 is principally limited 

to its use in Enhanced Oil Recovery (EOR). The cost of CCS needs to be reduced 

by implementing requirements that are necessary and sufficient while not 

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22691

670
compromising the protection of drinking water. 

Response: EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, 

GS is conducted in a manner that protects USDWs from endangerment. The requirements apply to 

owners or operators of injection wells used to inject CO2 for permanent storage, and do not apply to 

generators of CO2. Encouraging investment in CCS projects, addressing climate change, and setting a 

price for carbon are outside the scope of the GS rulemaking. 

See the remainder of EPA's responses to this comment and the final rule and preamble for additional 

information on EPA's regulatory approach. 

Comment: injection. SEPCo believes, as further detailed in these comments that the 

proposed requirements should be streamlined significantly to increase the 

flexibility of the requirements for CO2 injection and reduce the unnecessary 

regulatory burdens the proposed rule would impose. SEPCo respectfully recommends 

EPA modify its proposed regulatory approach accordingly. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Comment: use of GS as a technology for reducing CO2 emissions. In developing such 

regulations, it is important that EPA maintain a flexible, performance-based 

approach that allows regulators to tailor specific permit requirements as 

appropriate based on the broad range of injection sites and practices that may 

be encountered in the GS context and on the body of knowledge and experience 

that will be gained not only from pilot and demonstration projects, but from the 

initial deployment of commercial scale GS projects. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Commenter Name: John King Letter ID: 0211

Commenter Organization: Shell Exploration and Production Company (SEPCo) Comment ID: 22746

Commenter Name: John King Letter ID: 0211

Commenter Organization: Shell Exploration and Production Company (SEPCo) Comment ID: 22757

Commenter Name: Paul L. Carpinone Letter ID: 0212

671
Comment: It is imperative that the Final Rule reflect the challenges inherent in crafting 

regulations for commercial CO2 injection activities when large-scale commercial 

operations are only at the nascent stage. The challenge confronting EPA in this 

rulemaking is to establish a cost-effective and environmentally protective 

regulatory program to cover a range of operations for which the technology will 

not be commercially deployed for a number of years. To meet this challenge, it 

is critical that the Final Rule emphasize performance-based rules that can be 

readily adjusted and fine-tuned as industry and regulators alike gain experience 

with large-scale CO2 sequestration. Tampa Electric acknowledges EPA's efforts to 

build flexibility mechanisms into the Proposal, including provisions for 

directorial discretion and the suggestion that forthcoming guidance may be used 

to clarify other requirements. In general, we agree that these methods will help 

create a regulatory framework that can evolve as information and technological 

advancements are gained in the field of carbon capture and sequestration. It is 

important, however, that any directorial discretion be clearly defined and 

limited; this can be achieved while still maintaining a rule that is flexible 

and avoids unnecessary prohibitions. In addition, guidance on any aspect of the 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

EPA is developing guidances for States that describe the process of applying for and receiving primary 

enforcement authority (primacy) for GS Class VI wells under Section 1422 of SDWA, as well as the 

technical and administrative issues on developing GS regulations that are the equivalent of minimum 

federal criteria and requirements. The guidance will describe areas of Directorial discretion and 

considerations for how that discretion would be exercised. This guidance will be available on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: Because information and technology related to carbon sequestration will develop 

as industry and regulators gain experience with CCS, Tampa Electric urges EPA to 

avoid blanket prohibitions or arbitrary absolutes in the Final Rule. We agree 

that the appropriate standard underlying the technical requirements for CO2 GS 

wells is the protection of underground sources of drinking water (USDWs). 

However, because it is difficult to know at this point what methods or 

Commenter Organization: Tampa Electric Company Comment ID: 22898

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 22900

672
technology will be developed for injection and long-term storage of CO2 in a 

manner that is protective of USDWs -- and because there is sure to be demand for 

significant capacity for CO2 GS -- EPA should not prematurely preclude the use of 

specific types of sites or methods for Class VI CO2 injection. The Final Rule 

should leave the door open for a range of injection sites and methods (some of 

which are unknown or not yet fully understood), provided that the Owner or 

Operator can show that the injection and storage will be protective of USDWs. 

Response: As described above, EPA believes that the Class VI requirements balance site-specific 

flexibility with USDW protection. EPA clarifies that the Class VI GS requirements are designed to 

ensure that, where deployed, GS is conducted in a manner that protects USDWs from endangerment. 

Encouraging investment in CCS projects and facilitating deployment are outside the scope of the GS 

rulemaking. 

Comment: - Because the technology described in the Proposal will not be commercially 

deployed for a number of years, the Final Rule must be flexible enough to 

accommodate developments in information and technology related to carbon 

sequestration. Similarly, because there is likely to be a significant amount of 

CO2 available for sequestration under the Program, the Final Rule should avoid 

arbitrary absolutes or blanket prohibitions regarding site selection or well 

construction or injection procedures. The Final Rule should keep available as 

many options as possible for site selection and method of injection, subject 

always to the standard that any CO2 GS be protective of USDWs. 

Response: As described above, EPA is using an adaptive approach to regulating GS under the UIC 

Program. Even after finalization of the GS regulation, EPA plans, every six years, to collect and review 

project data on GS research projects to determine whether the appropriate amount and types of 

information and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. 

Other EPA Comment Codes and Descriptions: 3500 2.2.3 Area of Review Reevaluation (seeking 

comment); 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Comment: - Because carbon sequestration technology is still developing and the 

characteristics and limitations of CO2 GS projects will vary greatly from one 

site to another it is essential to incorporate performance-based standards into 

the Final Rule, leading to a site-tailored approach to requirements for Area of 

Review ("AoR") reevaluation and post-injection site care and closure periods. 

Response: The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a 

combination of a fixed timeframe and a performance standard approach. EPA believes that a default 

PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this timeframe, combined 

with a site-specific Director’s discretion to create an alternative PISC time frame, ensures that USDWs 

are protected. The GS rule offers owners or operators flexibility regarding the duration of the PISC 

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the 

PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the 

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 22905

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 22906

673
Director discretion to allow a Class VI well owner or operator to demonstrate, based on substantial data 

during the permitting process, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c). EPA expects that the Director will 

consider the types of information the commenter describes in determining whether the plume and 

pressure front no longer pose a risk of endangerment to USDWs and post-injection site care monitoring 

may be discontinued. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

EPA disagrees that the GS regulation should include performance-based standards for AoR calculation. 

However, EPA believes that consideration of site-specific conditions is appropriate for the AoR 

calculation and reevaluation process. EPA believes that the flexibility incorporated into the AoR and 

corrective action plans and the provision for AoR reevaluation as required at §146.84(e) provide for an 

ongoing review of the site and a dialogue between the Director and the owner or operator to ensure that 

the most appropriate modeling and corrective action technologies are used to protect USDWs from 

endangerment. However, EPA believes that setting a minimum reevaluation frequency is appropriate. In 

the final rule, the Agency changed the minimum frequency for the AoR reevaluation at §146.84(e) from 

10 years to at least every 5 years in the final GS rule. EPA believes that this revised frequency addresses 

commenters' concerns about the inherent uncertainties in modeling CO2 movement, the emerging nature 

of GS technology, risk-based targeting of monitoring activities, and the unique nature of CO2 GS. 

Comment: - While directorial discretion is a useful mechanism to ensure flexibility in 

the Final Rule, such discretion must be clearly defined and limited. 

Response: EPA is developing guidances for States that describe the process of applying for and 

receiving primary enforcement authority (primacy) for GS Class VI wells under Section 1422 of 

SDWA, as well as the technical and administrative issues on developing GS regulations that are the 

equivalent of minimum federal criteria and requirements. The guidance will describe areas of Directorial 

discretion and considerations for how that discretion would be exercised. This guidance will be available 

on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information 

(40 CFR 146.82) 

Comment: Many statements in this section of the proposed rule specify exactly what types 

of data will be collected and how they will be presented in a permit 

application. Across the United States, there are widely varying geologies, 

available regional data sets, and how well various technologies perform. The 

permitting authority for a state or region should have the flexibility to 

determine what types of information an operator should present to adequately 

characterize a specific injection well site. 

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 22911

Commenter Name: Dennis R. James Letter ID: 0214

Commenter Organization: North American Coal Corporation (NAC) Comment ID: 22963

674
For example, the following statement is made: "Today’s proposal would require 

owners or operators to submit geochemical data on (a) the injection zone, (b) 

the confining zones, (c) containment zones above the confining zones in which 

any potentially migrating CO2 could be trapped, (d) all USDWs, and (e) any other 

geologic zone or formation that is important to the proposed monitoring 

program." This essentially requires an operator to collect geochemical data on 

the entire geologic column: From the surface down to the target formation. It 

is important to geochemically define the target formation and its overlying 

seal. It is also prudent to obtain data from adjacent formations that may be 

involved if leakage occurs. However, does this data all the way to the surface 

in any way add additional USDW protection? The permitting authority should have 

some discretion to limit the required data, based on the geology of the area. 

Response: The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical 

data on subsurface geologic formations, including all USDWs in the AoR is appropriate and protective 

of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate 

and transport model development (e.g., by providing appropriate input parameters), and provide 

information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. 

The baseline geochemical information will allow the owner or operator and permitting authority to 

evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid 

movement. 

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all 

USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining 

system and to serve as a baseline for future monitoring. The Director has the discretion to require 

geochemical analysis of additional subsurface zones if in the Director's opinion they are necessary for 

the protection of USDWs from endangerment. 

EPA agrees that site characterization should be site-specific, particularly in light of the variety of 

geologic settings in which GS may be employed. EPA believes that, while there is a large amount of 

required information, the owner or operator is given flexibility in determining what methods are used to 

demonstrate the suitability of a potential site. EPA envisions an ongoing dialogue between the Director 

and the owner or operator during the permitting process (as well as throughout the operation of the site).

EPA is developing guidance on site characterization for GS projects to assist owners or operators and 

Directors in evaluating permit requirements and applications under §146.82. The guidance provides 

recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site 

as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the 

injection and confining zone. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: A. Tri-State acknowledges EPA's efforts to use a "performance-based" approach 

and to build flexibility mechanisms into the rule. In general, Tri-State agrees 

that these methods will help create a regulatory framework that can evolve as 

information and technological advancements are gained in the field of carbon 

capture and sequestration. It is important, however, that any directorial 

discretion be clearly defined and limited; this can be achieved while still 

Commenter Name: Barbara Walz Letter ID: 0216

Commenter Organization: Tri-State Generation and Transmission Association, 

Inc.

Comment ID: 

22965

675
maintaining a rule that is flexible and avoids unnecessary prohibitions. In 

Response: EPA is developing guidances for States that describe the process of applying for and 

receiving primary enforcement authority (primacy) for GS Class VI wells under Section 1422 of 

SDWA, as well as the technical and administrative issues on developing GS regulations that are the 

equivalent of minimum federal criteria and requirements. The guidance will describe areas of Directorial 

discretion and considerations for how that discretion would be exercised. This guidance will be available 

on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: We also learned, however, that there are number of critical policy, legal, and 

technical issues that must be resolved before geologic storage can be 

implemented on a full-scale commercial basis. The proposed rule is a significant 

early step in helping to resolve these issues. The rule, however, must be 

designed to facilitate, not unduly hinder, progress towards commercial 

deployment of geologic storage. Large-scale underground injection and storage of 

CO2 remains an emerging technology and it is important that any rule adopted by 

EPA be flexible enough to adapt to advances in science and technology moving 

forward. We offer these comments in support of a flexible and appropriately 

tailored rule that will facilitate geologic storage technology and projects 

while protecting underground sources of drinking water. 

Response: EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, 

GS is conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Comment: Default Provisions 

Although underground injection of CO2 is well established for enhanced oil and 

gas recovery, it remains in it nascent stages with respect to large-scale 

geologic storage. Throughout the proposed rule, EPA suggests the need for 

blanket prohibitions, limitations and default provisions that are overly 

conservative and not supported by established facts. Such examples include: 

- 50-year default post closure period 

- Mandatory 10-year reevaluation of the Area of Review (AoR) 

- Categorical exclusion of specific formations (e.g,. coal seams) 

- Prohibitions on types of well drilling (e.g., horizontal, angled) 

- Mandate to always inject below the lowermost USDW 

Commenter Name: Olon Plunk Letter ID: 0217

Commenter Organization: Xcel Energy, Inc. Comment ID: 21550

Commenter Name: Olon Plunk Letter ID: 0217

Commenter Organization: Xcel Energy, Inc. Comment ID: 21553

676
- Prohibition on use of exempt aquifers 

- Prohibition on hydraulic fracturing 

- Mandatory use of tracers 

- Mandatory annual and electronic reporting 

At this early stage, EPA should avoid establishing arbitrary limits or 

prohibitions that might stifle research and development, or that are so 

excessively conservative as to close the door on geologic storage projects that 

are otherwise safe and economically sound. The final rule must recognize that 

the potential risks, as well as the approaches to mitigate or eliminate that 

risk, will vary greatly from project to project. The broad imposition of 

administrative and technical requirements designed to be protective of the 

highest risk projects unnecessarily burden low to moderate risk projects. Viable 

projects might not be proposed or move forward due to excessive economic burdens 

or regulatory uncertainty. EPA should avoid a "one size fits all" approach and 

instead develop a framework that provides the flexibility for projects to be 

successfully permitted, based on each project's unique characteristics and 

circumstances. 

Long-Term Liability 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

Comment: Just as in nature with deep-sourced, natural CO2, there are low-risk sites that 

will permanently entrap CO2, and there are places where it may migrate, perhaps 

even to the surface. CO2 is a naturally occurring substance, and movement within 

the subsurface is very common. Rather than trying to fashion rules that protect 

against surface escape in all subsurface conditions, regulatory oversight needs 

to recognize the nearly ubiquitous presence of the molecule while identifying 

low-risk sites for entrapment and provide flexibility in regulation to 

accommodate the attendant risk level. 

In order to achieve statistically significant reductions of greenhouse gas 

emissions, large-scale carbon capture and storage (CCS) will have to be 

implemented at numerous sites. One of the greatest potential barriers to 

widespread deployment of sequestration projects would be the specification of 

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the 

University of North Dakota

Comment ID: 

21573

677
overly complex well design and monitoring of sites. Experience shows that exotic 

well designs add little benefit, while, on the other hand, judicious site 

selection adds greatly to the security of emplacement. For example, subsurface 

sequestration formations overlain by bedded salts provide optimal conditions for 

long-term storage. The focus of regulation should be performance criteria, not 

design criteria. As long as CO2 sequestration sites can meet the standards 

required for permitting, injection of CO2 for sequestration is, to a large 

extent, similar to EOR operations. In turn, requirements for injection wells 

accessing judiciously selected zones for sequestration should be more closely 

aligned with those of Class II standards than the more stringent Class I 

hazardous waste well standards. As currently proposed, the Class VI requirements 

are more reflective of Class I hazardous waste well standards. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

Comment: Detailed Comments 

Page 43492. SUMMARY. Regarding the phrase "...help ensure consistency..." 

Consistency does not necessarily mean that regulations are appropriate or 

effective. Geology is notoriously heterogeneous and, therefore, by definition 

inconsistent. Striving for consistency across geologic systems is difficult at 

best. One need only to look at the history of injection regulation across 

different states to see a lack of consistency is appropriate and primarily due 

to heterogeneity and inconsistency with respect to regional geologic 

characteristics. Guidelines must be flexible. Flexibility to ensure the safe 

maximization of CO2 storage must not be compromised by a desire to ensure 

consistency of rules across all geologic settings. 

Response: EPA agrees that permitting decisions for GS wells should be based on site-specific factors. 

The GS rule requires owners or operators to submit, and Directors to consider, extensive site-specific 

data, specified at §146.82, to demonstrate that a site is suitable for GS. Additionally, many of the permit 

requirements for GS wells are established through individualized site-specific plans for AoR and 

corrective action, testing and monitoring, and injection well plugging and post-injection site care and 

site closure. EPA adds that the final GS rule includes a balance of specific criteria to be met by the 

owner or operator and areas of Directorial discretion and considerations for how that discretion would 

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the 

University of North Dakota

Comment ID: 

21577

678
be exercised. The Agency believes this balance allows for GS projects to be designed and permitted to 

address the unique, site-specific aspects of each project, while providing consistency in permitting 

across the U.S. 

As described above, encouraging investment in CCS projects and facilitating deployment are outside the 

scope of the GS rulemaking. 

Comment: Page 43496. B. What Is EPA’s Authority under the Safe Drinking Water Act (SDWA) 

to Regulate Injection of CO2?Regarding the following quote from the document, 

referring to a key aspect of the Safe Drinking Water Act: 

"Section 1421 (b)(3)(A) of the Act also provides that EPA’s UIC regulations 

shall permit or provide for consideration of varying, geologic, hydrological, or 

historical conditions in different States and in different areas within a 

State." 

It is important that this aspect of the SDWA is a guiding principle for the 

proposed regulations. Based on those words in the SDWA, flexibility is demanded 

by statute and must be built into any UIC regulations. Unfortunately, the 

regulations proposed for GS wells in this document are often anything but 

flexible, but rather are quite prescriptive and inflexible. 

Response: As described above, EPA believes that the Class VI requirements balance site-specific 

flexibility with USDW protection. The final GS rule affords flexibility to owners or operators. Many of 

the permit requirements will be established through site-specific plans developed by the owner or 

operator and approved by the Director. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: There is also text in this section that can be interpreted as requiring the 

owner/operator to submit core, outcrop, seismic survey, cross sections, well 

logs, and other unspecified data. Some later passages on this subject suggest 

that they are not all necessarily required, but rather are examples of types of 

data that could be used to demonstrate and quantify various key characteristics 

of a formation. With respect to the need for various types of geological data, 

the document is at times vague, inconsistent and, occasionally, even 

contradictory. It is critical that geologic heterogeneity and regional 

differences in data availability be acknowledged and state or regional directors 

be given the flexibility to make decisions based on data sets that reflect the 

geologic and regional differences. For instance, seismic survey data are limited 

in coverage, are expensive to acquire, can be inconclusive with respect to 

interpretation, and should not be universally required as a precondition for 

site consideration. The regulations must be performance-based and reinforce the 

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the 

University of North Dakota

Comment ID: 

21585

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the 

University of North Dakota

Comment ID: 

21611

679
need to technically and efficiently achieve specific goals, such as proving that 

an adequate and competent seal exists or that a target formation has sufficient 

injectivity. The regulations should not prescribe precisely how such proof is 

obtained, but should only dictate that sufficient proof be presented to the 

director. The regulations should give the director a significant degree of 

flexibility to determine whether the body of evidence presented by the 

owner/operator constitutes sufficient proof that USDWs will be protected. The 

regulations may include a list of useful data types, but EPA should clearly 

state that the list is one of available tools from which to choose the most 

applicable to a specific site, not a list of required applications and data that 

must be acquired and presented. 

Response: EPA disagrees that any of these protective requirements are unnecessary. EPA believes that 

requiring appropriate site characterization by the owner or operator (under §146.82) and providing an 

appropriate degree of flexibility to the Director to evaluate site-specific geologic data will afford the 

greatest protection of USDWs from endangerment. EPA believes that it is important for the Director to 

have as much site-specific information as possible in order to make an informed decision to permit 

injection for GS at a specific site. The GS regulation allows flexibility where appropriate. Certain 

requirements (e.g., the need to characterize additional confining layers) are at the Director's discretion 

(§146.83(b)), based on his or her understanding of a particular site. 

Additionally, EPA disagrees that consideration of local and regional seismicity is not important. The site 

characterization provisions in the GS rule, including a review of the local and regional geology, and 

detailed review of any known or potential seismically active terrain in the vicinity of a proposed GS site 

are necessary to minimize the potential for induced seismic events or the reactivation of faults, which 

are a known potential risk associated with injection and are addressed in all aspects of the UIC 

regulations. 

Other EPA Comment Codes and Descriptions: 3140 2.1.4 Comments that the proposed geologic data 

requirements are too stringent 

Comment: Following is a series of comments with regard to the quote on page 43505: 

"...require owners or operators to submit geochemical data on (a) the injection 

zone, (b) the confining zones, (c) containment zones above the confining zones 

in which any potentially migrating CO2 could be trapped, (d) all USDWs, and (e) 

any other geologic zone or formation that is important to the proposed 

monitoring program." 

The EPA should recognize that it is essentially saying that the entire rock 

column from the injection zone to the surface must be geochemically 

characterized. Such characterization goes far above and beyond that which is 

necessary to protect the USDWs. It is essentially forcing owners/operators to 

pay for potentially unnecessary research activities. For instance, in the 

Williston Basin, a vast majority of the hydrocarbon production is historically 

from Paleozoic formations. One result of this is that there is a wealth of 

readily available data on the nature of Paleozoic formations in the Williston 

Basin. Likewise, the Cenozoic formations are fairly well characterized because 

of the presence of coal and potable aquifers. However, the Mesozoic formations 

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the 

University of North Dakota

Comment ID: 

21612

680
that lie between those two groups are relatively poorly understood. This is 

because there is little economic incentive to characterize most of the Mesozoic 

rocks beyond the fact that they are dominated by low permeability shales and 

evaporites. There are 15 named rock units in the Mesozoic section of the 

Williston Basin. The regulations as proposed indicate that they must all be 

geochemically characterized. To geochemically characterize all of these Mesozoic 

units as part of a GS project in which the primary sinks and seals are in the 

deeper Paleozoic would be very expensive and of dubious value to anyone. Once 

again, there must be flexibility and discretionary powers given to directors 

with respect to what formations must be geochemically characterized. Indeed, 

this concept of flexibility must apply for all types of characterization that 

are considered necessary to prove that a GS well application can be approved. 

Response: The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical 

data on subsurface geologic formations, including all USDWs in the AoR is appropriate and protective 

of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate 

and transport model development (e.g., by providing appropriate input parameters), and provide 

information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. 

The baseline geochemical information will allow the owner or operator and permitting authority to 

evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid 

movement. 

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all 

USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining 

system and to serve as a baseline for future monitoring. The Director has the discretion to require 

geochemical analysis of additional subsurface zones if in the Director's opinion they are necessary for 

the protection of USDWs from endangerment. 

EPA agrees that site characterization should be site-specific, particularly in light of the variety of 

geologic settings in which GS may be employed. EPA believes that, while there is a large amount of 

required information, the owner or operator is given flexibility in determining what methods are used to 

demonstrate the suitability of a potential site. EPA envisions an ongoing dialogue between the Director 

and the owner or operator during the permitting process (as well as throughout the operation of the site).

Comment: In the context of geologic sequestration of CO2, it is imperative to maintain 

flexibility in the regulatory requirements due to the site-specific nature of 

this activity and because the technology is continually advancing. For 

geologic sequestration of CO2, "one-size-fits-all" is not an approach that is 

necessarily or reasonably protective of USDWs. Rather, each site has sitespecific characteristics that merit differing requirements. Indeed, what may 

appear to be a standard protective measure in the context of a particular site 

could actually have the opposite effect and increase potential risks at another 

site. (See A Technical Basis for Carbon Dioxide Storage, CO2 Capture Project, 

December 2008.) 

Consequently, HEI strongly encourages EPA to provide performance standards for 

the various phases of a geologic sequestration project (i.e., site 

characterization, operation and site closure), while providing the Director 

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21648

681
flexibility to add requirements as necessary to address site-specific 

characteristics. This type of approach, consistent with Regulatory Alternative 

2, offers the degree of flexibility that the permitting authority will require 

to tailor fit-for-purpose requirements that address site specific 

characteristics. Furthermore, it ensures that project costs will be commensurate 

with the geologic risk, and will further the continued evolution of the best 

technologies. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: With respect to monitoring requirements in general, EPA should adopt regulations 

that are performance and risk-based and will result in a site-specific 

monitoring program that is designed to understand the location, movement and 

stabilization of the CO2 plume in the subsurface as well as the early 

identification of any leakage for appropriate corrective action. HEI commends 

EPA for its efforts in this regard, but believes that further modification is 

necessary. HEI agrees with the proposal to allow a phased approach to conduct 

Response: EPA agrees with commenters and believes that flexibility is important in developing and 

implementing a monitoring plan that is appropriately tailored for a specific GS site. The purpose of the 

requirement at §146.90 to develop site-specific testing and monitoring plans is to ensure that the 

monitoring performed at a site is appropriate for site operational conditions and the geologic setting. 

EPA believes that this is the best approach for addressing potential risks at GS sites. These flexible 

provisions in the monitoring requirements for Class VI wells enable the owner or operator to tailor 

monitoring programs to the specific needs of each project in consultation with the Director. 

The final regulation provides for flexibility in: 1) methodologies used to collect these data, 2) the spatial 

resolution at which the data should be collected, and 3) how often the data should be collected. The 

number and placement of monitoring wells will be based on site-specific information such as the 

calculated AoR, injection rate and volume, site geology, baseline data, and the presence of artificial 

penetrations within the AoR. In some instances, there may be a limited number of options for complying 

with EPA's minimum requirements. For example, monitoring for geochemical changes will require use 

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21676

682
of monitoring wells and collection of groundwater samples for chemical analysis. Many options 

currently exist for complying with other requirements, such as tracking the position of the plume and 

pressure front within the injection zone. 

Flexibility is also provided regarding how to monitor for the specific data required by the final rule. The 

testing and monitoring plan is developed by the owner or operator in consultation with the Director and 

is designed to ensure that a detailed, Director-approved document describing how monitoring will be 

conducted during the lifetime of the project exists. EPA is developing guidance on testing and 

monitoring to assist owners or operators and Directors in evaluating requirements under §146.90, 

including proposed monitoring plans. The guidance describes available technologies and recommended 

approaches for implementing a testing and monitoring plan, including pre-operational geophysical 

logging and testing of injection wells, MITs, injection well testing during operation, groundwater quality 

monitoring, tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which 

may be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: In the context of geologic sequestration of CO2, it is imperative to maintain 

flexibility in the regulatory requirements due to the site-specific nature of 

this activity and because the technology is continually advancing. For geologic 

sequestration of CO2, "one-size-fits-all" is not an approach that is necessarily 

or reasonably protective of USDWs. Rather, each site has site-specific 

characteristics that merit differing requirements. Indeed, what may appear to be 

a standard protective measure in the context of a particular site could actually 

have the opposite effect and increase potential risks at another site. (See A 

Technical Basis for Carbon Dioxide Storage, CO2 Capture Project, December 2008.) 

Consequently, BP strongly encourages EPA to provide performance standards for 

the various phases of a geologic sequestration project (i.e., site 

characterization, operation and site closure), while providing the Director 

flexibility to add requirements as necessary to address site-specific 

characteristics. This type of approach, consistent with Regulatory Alternative 

2, offers the degree of flexibility that the permitting authority will require 

to tailor fit-for-purpose requirements that address site specific 

characteristics. Furthermore, it ensures that project costs will be 

commensurate with the geologic risk, and will further the continued evolution of 

the best technologies. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21713

683
finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front 

Monitoring Requirements (40 CFR 146.90) 

Comment: With respect to monitoring requirements in general, EPA should adopt regulations 

that are performance and risk-based and will result in a site-specific 

monitoring program that is designed to understand the location, movement and 

stabilization of the CO2 plume in the subsurface as well as the early 

identification of any leakage for appropriate corrective action. BP commends 

EPA for its efforts in this regard, but believes that further modification is 

necessary. BP agrees with the proposal to allow a phased approach to conduct 

Response: EPA agrees with commenters and believes that flexibility is important in developing and 

implementing a monitoring plan that is appropriately tailored for a specific GS site. The purpose of the 

requirement at §146.90 to develop site-specific testing and monitoring plans is to ensure that the 

monitoring performed at a site is appropriate for site operational conditions and the geologic setting. 

EPA believes that this is the best approach for addressing potential risks at GS sites. These flexible 

provisions in the monitoring requirements for Class VI wells enable the owner or operator to tailor 

monitoring programs to the specific needs of each project in consultation with the Director. 

The final regulation provides for flexibility in: 1) methodologies used to collect these data, 2) the spatial 

resolution at which the data should be collected, and 3) how often the data should be collected. The 

number and placement of monitoring wells will be based on site-specific information such as the 

calculated AoR, injection rate and volume, site geology, baseline data, and the presence of artificial 

penetrations within the AoR. In some instances, there may be a limited number of options for complying 

with EPA's minimum requirements. For example, monitoring for geochemical changes will require use 

of monitoring wells and collection of groundwater samples for chemical analysis. Many options 

currently exist for complying with other requirements, such as tracking the position of the plume and 

pressure front within the injection zone. 

Flexibility is also provided regarding how to monitor for the specific data required by the final rule. The 

testing and monitoring plan is developed by the owner or operator in consultation with the Director and 

is designed to ensure that a detailed, Director-approved document describing how monitoring will be 

conducted during the lifetime of the project exists. EPA is developing guidance on testing and 

monitoring to assist owners or operators and Directors in evaluating requirements under §146.90, 

including proposed monitoring plans. The guidance describes available technologies and recommended 

approaches for implementing a testing and monitoring plan, including pre-operational geophysical 

logging and testing of injection wells, MITs, injection well testing during operation, groundwater quality 

monitoring, tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which 

may be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21721

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21729

684
Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Furthermore, in various parts of the Proposed Rule, EPA has prescribed 

particular monitoring technologies. Mandating any specific technology(ies) would 

have the adverse effect of (1) promoting particular technologies to the 

exclusion of other developed - and to be developed - technology(ies), and (2) 

substantially increasing costs without necessarily contributing to the 

protection of USDWs. This would hinder the development and deployment of CCS at 

commercial scale. Moreover, it would discourage the development of other 

technologies. BP therefore strongly discourages EPA from promulgating 

regulations that mandate the use of any specific monitoring technology. 

Response: EPA agrees that prescribing specific technologies to be used in all cases for GS would not be 

appropriate given the variability in sites, and believes that the rule provides flexibility to owners or 

operators to develop site-specific testing and monitoring plans that employ appropriate technologies 

provided they meet the requirements at §146.90. EPA is developing guidance on testing and monitoring 

to assist owners or operators and Directors in evaluating requirements under §146.90, including 

proposed monitoring plans. The guidance describes available technologies and recommended 

approaches for implementing a testing and monitoring plan, including pre-operational geophysical 

logging and testing of injection wells, MITs, injection well testing during operation, groundwater quality 

monitoring, tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which 

may be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. In addition, in January 

2009, DOE published a best practices manual entitled "Monitoring, Verification, and Accounting of 

CO2 Stored in Deep Geologic Formations" (DOE/NETL-311/081508); this manual is included in the 

docket for the for the final GS rule. 

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan requirement 

(seeking comment) 

Comment: Plume and Pressure Front Monitoring 

EPA would require each Class VI well permit application to contain a monitoring 

plan to verify that a GS well is operating as intended and not endangering USDW. 

EPA should be aware that certain monitoring technology is currently under 

development and not available as a tool in the near term to meet the proposed 

EPA requirements. Further, the usefulness of available technology is a function 

of site-specific characterizations. The EPA should not impose a one-size-fitsall approach. CURC recommends that the EPA permit well owners and operators to 

propose the use of available technology to meet the proposed requirements and 

then to amend their tailored monitoring plans as technology evolves. 

Response: EPA agrees that prescribing specific technologies to be used in all cases for GS would not be 

appropriate given the variability in sites, and believes that the rule provides flexibility to owners or 

operators to develop site-specific testing and monitoring plans that employ appropriate technologies 

provided they meet the requirements at §146.90. EPA is developing guidance on testing and monitoring 

to assist owners or operators and Directors in evaluating requirements under §146.90, including 

proposed monitoring plans. The guidance describes available technologies and recommended 

approaches for implementing a testing and monitoring plan, including pre-operational geophysical 

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21789

685
logging and testing of injection wells, MITs, injection well testing during operation, groundwater quality 

monitoring, tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which 

may be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. In addition, in January 

2009, DOE published a best practices manual entitled "Monitoring, Verification, and Accounting of 

CO2 Stored in Deep Geologic Formations" (DOE/NETL-311/081508); this manual is included in the 

docket for the for the final GS rule. 

Comment: C. The Regulatory Design 

Section III.A. of the Preamble presents several approaches for how the UIC rules 

for CO2 injection might be structured. EPA selected an approach described as 

"Tailored Requirements," based on the perceived ability of that approach to be 

"tailored" to the volume, buoyancy, and corrosiveness of CO2 from specific CCS 

operations. It rejected a more flexible alternative, described as "General 

Requirements," because it was not "tailored." A performance-based program with 

requirements that prescribe the required outcomes of properly designing and 

operating a CCS project, rather than a program that prescribes how to achieve 

those outcomes, is preferable. A performance-based approach better accommodates 

changes in knowledge and technology over time, and would allow implementing 

state permitting authorities the flexibility to use their expertise to address 

varying geologic and geographic situations. In many instances, retaining the 

primacy of state regulatory authority may better address such an approach, and 

in all instances a performance-based approach would provide federal or state 

authorities and the CCS operators the flexibility to achieve required outcomes. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

In response to the comment that States with primacy be able to develop “performance-based standards,” 

the Agency clarifies that States, Tribes, and Territories can develop requirements for Class VI and 

submit primacy applications (under Section 1422 of the SDWA) for review and approval by EPA as 

long as the requirements are as stringent as or more stringent than the Federal minimum requirements. 

Comment: regulatory certainty for early CCS projects. EPA should acknowledge that overly 

prescriptive regulations can discourage technological development and commercial 

deployment. Such an outcome can adversely impact the environment by impairing 

the design or implementation of a CO2 mitigation program and can also lead to 

costly and unnecessary requirements. We also encourage EPA to reconsider the 

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21793

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21800

686
basic design of the UIC Class VI program and create a more flexible performancebased program given the fact that CO2 injections has been conducted safely in 

the U.S. for more than a decade, rather than the more prescriptive program 

proposed. Lastly, CURC recommends that EPA issue guidance for an interim Class 

Response: As described above, EPA believes that the Class VI requirements balance site-specific 

flexibility with USDW protection. EPA adds that it is using an adaptive approach to regulating GS under 

the UIC Program. Even after finalization of the GS regulation, EPA plans, every six years, to collect and 

review project data on GS research projects to determine whether the appropriate amount and types of 

information and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. 

Comment: Complexity and Consistency of Regulations - We recognize that EPA has attempted 

to provide a great deal of flexibility in most aspects of the regulations, while 

incorporating most of currently known concepts and technologies in permitting, 

operation, and monitoring of the sites. The flexibility has primarily been 

incorporated through making the requirements subject to "directors" decision. 

Our concern is that some directors may choose to require all of the numerous 

requirements mentioned in the permit, rather then selectively requiring an 

appropriate portfolio of safeguards. Such an approach could deter operators 

from considering the GS as an option for CO2 mitigation. Another concern is 

that the requirements will be applied with inconsistent level of flexibility in 

various regions and states, making some regions more or less favorable for GS. 

We encourage EPA’s continuing oversight and guidance in ensuring that the 

regulations are applied consistently and with a reasonable selection of 

requirements. 

Response: EPA is developing guidances for States that describe the process of applying for and 

receiving primary enforcement authority (primacy) for GS Class VI wells under Section 1422 of 

SDWA, as well as the technical and administrative issues on developing GS regulations that are the 

equivalent of minimum federal criteria and requirements. The guidance will describe areas of Directorial 

discretion and considerations for how that discretion would be exercised. This guidance will be available 

on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: 7. The Proposed Rule precludes a meaningful role for States. 

UIC regulations developed by EPA must permit or provide consideration of varying 

geologic, hydrological, or historical conditions in different States and in 

different areas within a State. The Proposed Rule does not allow State directors 

to use their expertise and knowledge to account for these varying conditions. 

Response: EPA agrees that permitting decisions for GS wells should be based on site-specific factors. 

The GS rule requires owners or operators to submit, and Directors to consider, extensive site-specific 

data, specified at §146.82, to demonstrate that a site is suitable for GS. Additionally, many of the permit 

Commenter Name: Neeraj Gupta Letter ID: 0229

Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21813

Commenter Name: A. James Mayer Letter ID: 0230

Commenter Organization: A. J. Mayer International on behalf of the American 

Energy Security Initiative

Comment ID: 

21884

687
requirements for GS wells are established through individualized site-specific plans for AoR and 

corrective action, testing and monitoring, and injection well plugging and post-injection site care and 

site closure. EPA adds that the final GS rule includes a balance of specific criteria to be met by the 

owner or operator and areas of Directorial discretion and considerations for how that discretion would 

be exercised. The Agency believes this balance allows for GS projects to be designed and permitted to 

address the unique, site-specific aspects of each project, while providing consistency in permitting 

across the U.S. 

In response to the comment that States with primacy be able to develop “performance-based standards,” 

the Agency clarifies that States, Tribes, and Territories can develop requirements for Class VI and 

submit primacy applications (under Section 1422 of the SDWA) for review and approval by EPA as 

long as the requirements are as stringent as or more stringent than the Federal minimum requirements. 

Other EPA Comment Codes and Descriptions: 2000 1.5 Need for a New Class of Injection Well 

Comment: 3. EPA should begin with a Class II injection well framework to assure that the 

rules are flexible enough to consider site-specific characteristics and 

knowledge gained from the extensive CO2 history and the ongoing demonstration 

and pilot projects. 

Response: EPA agrees that owners and operators of Class II wells have experience that will be helpful 

in implementing the Class VI requirements, but EPA disagrees that the risks posed by long-term storage 

of CO2 for GS can be addressed under existing UIC requirements, such as those for Class II wells. EPA 

believes that there are significant differences between how projects are operated, as well as the risks 

posed by these different injection activities. The new tailored approach of the GS rule was designed to 

address the general risks deep injection may pose to USDWs and was tailored specifically to address the 

risks posed by long-term storage of CO2 (i.e., very large volumes, very long time-periods, and reservoir 

pressure conditions). 

The final Class VI regulations require that any owner or operator injecting CO2 for the primary purpose 

of long term storage obtain a Class VI permit with some special consideration for the fact that they are 

transitioning from a well not originally designed to meet Class VI requirements. The Director has the 

authority to determine at what point a Class VI permit is required for those projects that are transitioning 

from the primary purpose of EOR to long term storage of CO2. The final regulation provides a set of 

technical factors for the Director to evaluate in making this determination, at §144.19. EPA believes that 

this approach provides sufficient protection of USDWs when there is an increased risk to USDWs as 

compared to traditional Class II operations while allowing for site-specific flexibility. For more 

information, please see the discussion on transition of Class II wells in the preamble to the final GS rule.

Furthermore, EPA agrees that flexibility is important for regulating GS activities. EPA has taken a 

regulatory approach which promotes USDW protection, incorporates flexibility or the discretion of the 

permitting authority when appropriate, seeks to limit burden on owners or operators and permitting 

agencies, and provides a foundation for national consistency in permitting of GS projects. For example, 

under the final rule, many of the permit requirements must be established through site-specific plans 

(e.g., AOR and corrective action plan, testing and monitoring plan, etc.) developed by the owner or 

operator and approved by the Director. Consequently EPA expects that owners or operators will consult 

with the Director as they develop, implement, and update these plans. Additionally, the Director has the 

discretion to approve alternatives to the requirements in some cases. For example, the Director may in 

Commenter Name: A. James Mayer Letter ID: 0230

Commenter Organization: A. J. Mayer International on behalf of the American 

Energy Security Initiative

Comment ID: 

21886

688
certain situations modify the length of the post-injection site care period or approve an alternative postinjection site care timeframe as part of the permitting process under §146.93, allow the use of alternate 

methods for mechanical integrity testing under §146.89, or grant waivers from the requirement to inject 

below the lowermost USDW under §146.95. 

Other EPA Comment Codes and Descriptions: 1410 1.2.1 Comments in support of EPA/rulemaking; 

1850 1.4.2 CO2 GS Field Research 

Comment: Montana-Dakota strongly supports research and development efforts underway to 

facilitate commercial-scale CO2 capture and sequestration (CCS) projects, and 

shows this support specifically through its active membership in the Plains CO2 

Regional (PCOR) Partnership. Led by the EERC and assisted by its members, PCOR 

and has developed and is currently carrying out two CO2 geologic sequestration 

projects designed to demonstrate the effectiveness of CO2 geologic 

sequestration. As these efforts increase, it is necessary to develop clear, 

flexible and appropriately tailored regulations to facilitate the development of 

and spur investment in carbon capture and sequestration technology. The proposed 

rule assists with creating additional certainty in approaching GS project 

development, however there are some concerns that need to be addressed. MontanaResponse: EPA acknowledges the value of the DOE pilot projects and resultant data and information 

generated by such projects. EPA has evaluated permits and reviewed operational data and information 

associated with the seven RCSPs funded by the U.S. Department of Energy and coordinated through the 

National Energy Technology Laboratory (NETL). In addition to the information cited in the preamble to 

the proposed rule, EPA published a Notice of Data Availability and Request for Comment on August 31, 

2009 (74 FR 44802) in which the Agency described the results of research at three DOE partnership 

sites: the Escatawpa, Mississippi project; the Aneth Field project in Paradox Basin, Southeast Utah; and 

the Pump Canyon Site, New Mexico. 

EPA agrees that flexibility to address new research is important. Even after finalizing the rule, the 

Agency plans to collect and review data every six years on GS projects, including research by the DOE 

Partnerships, to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

EPA agrees that the implementation of the GS rule in a manner that ensures protection of USDWs from 

endangerment is important to establishing a foundation for further advances in the field of CO2 GS. 

EPA acknowledges the need for regulatory certainty: the final GS requirements provide a level of 

certainty by setting forth unique requirements for GS. These requirements include: the tailored AoR 

delineation process at §146.84, the types of monitoring appropriate to GS projects (§146.90) and the 

post-injection site care process (§146.93). For additional information on these requirements, please also 

see the discussion of EPA’s Final Regulatory Approach in the preamble to the final GS rule. 

EPA agrees that an adaptive and flexible approach is appropriate. To protect USDWs from 

endangerment and meet the potentially fast pace of GS deployment, EPA is using an adaptive approach 

to regulating CO2 injection for GS. The Agency plans to collect and review data every six years on GS 

projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. An adaptive approach will allow regulatory development to proceed in time to meet the 

Commenter Name: Abbie Krebsbach Letter ID: 0235

Commenter Organization: Montana-Dakota Utilities Co. Comment ID: 23177

689
current and future demands for Class VI permits while EPA continues to gather data from pilot projects 

and other research as it becomes available. 

Comment: Utilize Performance-based Standards for Proposed Sites 

As proposed, EPA's regulations contain a number of default provisions that would 

apply universally to projects. Rather than imposing default provisions, those 

portions of the rulemaking that address inherently site-specific issues should 

allow for site-specific, performance-based determinations as part of the 

permitting process. Sites will differ greatly geologically and otherwise. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance- or technology-based standards for GS projects, 

EPA is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: Careful Characterization of Site Risks 

It is, of course, crucial that the final rule meet EPA's objective of protecting 

drinking water supplies. We are concerned, however, that some of the more 

stringent requirements being proposed for Class VI wells are not supported by 

findings of unique risks actually posed by CCS wells. EPA's regulations should 

be based upon an accurate characterization of the potential risks posed by the 

geologic sequestration of CO2 and be specifically tailored accordingly to 

address those identified risks. This will ensure that EPA meets its obligation 

to provide appropriate protection of underground sources of drinking water, 

while avoiding unnecessary regulations that may hamper CCS or EOR projects from 

going forward or call into question the general safety of CO2 storage. 

Regulations tailored to ensure proper site selection will in turn minimize the 

need for regulations crafted to respond to risks that, in such a context, would 

be extremely unlikely to occur. For example, simply limiting CO2 injection to 

Response: EPA believes that a detailed, site-specific, geologic site characterization (required under 

§146.82) is essential to evaluating the presence and adequacy of the various geologic features necessary 

to receive and confine injected CO2 for GS. The requirements for geologic site characterization are 

based on a long standing UIC regulatory framework developed to address specific risks to USDWs 

posed by injection. The Class VI GS requirements are tailored so that they are appropriate for the unique 

nature of injecting large volumes of CO2 into a variety of geological formations for long-term storage. 

Commenter Name: Abbie Krebsbach Letter ID: 0235

Commenter Organization: Montana-Dakota Utilities Co. Comment ID: 23179

Commenter Name: Abbie Krebsbach Letter ID: 0235

Commenter Organization: Montana-Dakota Utilities Co. Comment ID: 23181

690
Other EPA Comment Codes and Descriptions: 1930 1.4.4.2 Consultations with State, Tribal, and 

local Associations (e.g., GWPC, IOGCC) 

Comment: Limits on EPA Authority and Discretion 

EPA should consider the significant interests and experience of the states in 

developing regulations. Montana-Dakota recognizes that in order to allow for 

effective site-specific determinations and to maintain essential regulatory 

flexibility, some amount of discretion must be vested in the UIC program 

director. At the same time, such discretion should be bounded by the inclusion 

of relevant and appropriate considerations for making necessary determinations. 

In general, the rules should establish with sufficient clarity the factors to be 

taken into account and leave the precise determinations to the permit process. 

Response: The GS rule provides flexibility to determine the suitability of a proposed site based on 

extensive, site-specific data. EPA believes that requiring appropriate site characterization by the owner 

or operator and providing an appropriate degree of flexibility to the Director to evaluate site-specific 

geologic data will afford the greatest protection of USDWs. The issuance of a UIC Class VI permit is 

determined based on evaluation of site-specific permit information pursuant to the requirements at 

§§146.82 and 146.83. 

EPA is developing guidance materials that describe the process of applying for and receiving primary 

enforcement responsibility (primacy) for GS Class VI wells under Section 1422 of SDWA, as well as 

the technical and administrative issues on developing GS regulations that are the equivalent of minimum 

federal criteria and requirements. This guidance and training addresses areas where the Director is given 

discretion in implementing the requirements. Such requirements where the Director has discretion 

include: whether to require owners or operators to identify and characterize additional confining zones 

under §146.83, whether to require surface air monitoring and/or soil gas monitoring under §146.90, and 

whether to extend or shorten the post-injection site care period or approve an alternative post-injection 

site care timeframe as part of the permitting process under §146.93 

Other EPA Comment Codes and Descriptions: 2300 1.7 Comments on the Alternatives Considered 

Comment: Section III -Proposed Regulatory Alternatives 

Subsection A -Proposed Alternative 

Comment: Of the four alternatives considered by EPA, we appreciate the fact that 

the highly specific requirements approach of Alternative 4 was not chosen. 

However, even with the selected Alternative 3, we believe that EPA still must 

provide some of the flexibility that was to be considered under Alternative 2. 

We are somewhat troubled by EPA's statement that it "did not select this 

alternative (Alternative 2) because it is not tailored to meet the unique 

challenges of long-term C02 storage. While this option includes flexibility for 

permit authorities to add requirements, EPA cannot be certain that the necessary 

adjustments would be made." 

Commenter Name: Abbie Krebsbach Letter ID: 0235

Commenter Organization: Montana-Dakota Utilities Co. Comment ID: 23193

Commenter Name: Robert E. Carter Jr. Letter ID: 0236

Commenter Organization: Indiana Department of Natural Resources (IDNR) Comment ID: 23205

691
Response: Even though the Agency did not choose Alternative 2, EPA agrees that flexibility is 

important to accommodate the varied conditions that may be encountered at GS sites while ensuring the 

protection of USDWs. 

The technical requirements in Alternative 3 (and the final GS rule) build upon the long-standing UIC 

regulatory framework for deep wells and are appropriately tailored to address the unique nature of fullscale CO2 GS, including the volumes of CO2 to be injected, the buoyant and mobile nature of the 

injectate, and its corrosivity in the presence of water. 

The regulation provides flexibility for selection of appropriate sites and target formations (under 

§146.82), well construction specifics (under §146.86), and testing and monitoring regimes (under 

§146.90), provided the owner or operator can demonstrate that the injection and storage will not 

endanger USDWs and that minimum requirements for the site are met. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: – EPA should apply a tiered set of site characterization requirements based on 

demonstrable and known site characteristics. For example, potential sites that 

are deep saline formations located more than one kilometer below the surface are 

generally recognized as among the most favorable and secure site options for 

assuring public safety.[FN1] If such sites do not have a USDW aquifer located 

between it and the ground surface above, a more streamlined regulatory site 

characterization and risk review may be appropriate. On the other hand, an 

example of a potential site that may require a more rigorous site 

characterization and risk assessment are "sole source aquifers" which are 

aquifers that are a sole supply of water for a region and are critically 

important to protect. Some stakeholders may assert that there should be no CO2 

storage above or below a sole source, aquifer. However, such a restriction 

would essentially prohibit storage in many western areas. Rather, a better 

approach would allow EPA to permit UIC Class VI wells in areas where it can be 

shown that there are sufficient caps and protections to prevent the migration of 

CO2 in overlying aquifers, even in proximity of aquifers designated as sole 

source. An early detection-monitoring program could be established to provide 

sufficient opportunity to mitigate any unlikely release of CO2 from the geologic 

storage unit. Approaches like this illustrate how EPA can streamline UIC 

regulations for site characterization and permit UIC Class VI wells that first 

and foremost protect public safety, yet reflect a workable balance in adapting 

site characterization and risk assessments based on criteria adaptable to unique 

candidate sites. 

Response: EPA believes that requiring appropriate, site-specific, site characterization by the owner or 

operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate 

site-specific geologic data will afford the greatest protection of USDWs from endangerment. EPA 

believes that it is important for the Director to have as much site-specific information as possible in 

order to make an informed decision to permit injection for GS at a specific site. This approach allows 

the permit writer to establish requirements considering varying site conditions eliminating the need for 

tiered requirements. GS in areas that may pose risks to USDWs, as assessed and identified by the owner 

or operator and the Director during the site selection process, would not be permitted. EPA disagrees 

that a tiering system for GS sites or formations is appropriate. Instead, the GS rule focuses on evaluating 

the suitability of each site based on site-specific geological and operational data. 

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission Associates Comment ID: 22246

692
EPA adds that the final GS rule contains a provision (at §146.95) for owners or operators to apply for 

waivers from the requirement that injection be below the lowermost USDW. EPA believes this waiver 

provision will reduce potential limitations on the re-permitting of Class II wells as Class VI wells, 

provided they meet the requirements at §146.95 while still protecting USDWs from endangerment. 

Comment: – EPA's proposed regulation needs to focus on accurate site specific 

characterization of the potential risks posed by geologic sequestration of CO2 

and the UIC program needs to be specifically tailored accordingly to address 

those identified risks. This will help EPA avoid over generalizing in its 

regulatory requirements. Too many general default provisions that presume 

universal application can be problematic. The geologic variability involved in 

different conceivable GS projects needs to be specifically addressed, site-bysite, on issues ranging from site characterization to area of review (AoR) to 

containment requirements. The regulations should encourage site-specific, 

performance-based determinations at the permitting stage to handle these 

specific issues. This approach will work toward practical problem resolution 

without unduly alarming the public with generalizations about potential, but 

unrealistic risks and problems. 

Response: EPA agrees that permitting decisions for GS wells should be based on site-specific factors. 

The GS rule requires owners or operators to submit, and Directors to consider, extensive site-specific 

data, specified at §146.82, to demonstrate that a site is suitable for GS. Additionally, many of the permit 

requirements for GS wells are established through individualized site-specific plans for AoR and 

corrective action, testing and monitoring, and injection well plugging and post-injection site care and 

site closure. EPA adds that the final GS rule includes a balance of specific criteria to be met by the 

owner or operator and areas of Directorial discretion and considerations for how that discretion would 

be exercised. The Agency believes this balance allows for GS projects to be designed and permitted to 

address the unique, site-specific aspects of each project, while providing consistency in permitting 

across the U.S. 

Rather than setting performance or technology-based standards for GS projects, EPA is adopting a 

flexible approach, where operators of GS projects would develop and implement site-specific plans for 

delineating the AoR, testing and monitoring the site, performing corrective action, and post-injection site 

care. EPA believes that the plans—which would be reviewed and approved by the Director and 

periodically updated throughout the life of the project—promote an ongoing dialogue between the 

operator and the Director that will encourage use of the most appropriate technologies for a particular 

project. 

Other EPA Comment Codes and Descriptions: 2400 1.8 Comments on EPA's adaptive rulemaking 

process 

Comment: – Finally, EPA needs to build into this regulation a "learning and adjustment" 

process that gains feedback from implementation of the UIC for CO2 GS rule, and 

establish a periodic review process to make adjustments and corrections to the 

rule based on experienced gained in permitting, operation, and closure of UIC/GS 

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission Associates Comment ID: 22248

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission Associates Comment ID: 22250

693
wells. A CCS program of the size anticipated to meet national climate change 

CO2 abatement goals is going to create a very large endeavor that is bound to 

experience difficulties in its deployment and implementation. EPA needs a ready 

means to provide regulatory adjustments to reinforce the safety and success of 

this UIC / GS program as it proceeds in the future. 

Response: EPA agrees that an adaptive approach to the UIC GS rulemaking is appropriate. The Agency 

plans to use such an approach to ensure that USDWs are protected from endangerment and meet the 

potentially fast pace of GS deployment. EPA believes that an adaptive approach will allow regulatory 

development to proceed in time to meet the current and future demand for Class VI permits while 

recognizing the need to: continue to gather data from pilot projects and other research as it becomes 

available; and to enhance understanding of the technical and administrative aspects of GS deployment, 

operation, and technology developments. 

EPA plans, every six years, to collect and review data on GS projects to determine whether the 

appropriate amount and types of information and appropriate documentation are being collected, and to 

determine if modifications to the requirements are appropriate or necessary. 

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 

CFR 146.83) 

Comment: EPA should consider applying a tiered set of site characterization requirements 

based on demonstrable and known site characteristics. For example, potential 

sites that are deep saline formations located one or more kilometers below the 

ground surface are generally recognized as among the most favorable and secure 

site options for assuring public safety. If such sites do not have a 

Underground Source of Drinking Water (USDW) aquifer located between it and the 

ground surface above, a more streamlined regulatory site characterization and 

risk review may be appropriate. 

On the other hand, an example of a potential site that may require a more 

rigorous site characterization and risk assessment are "sole source aquifers" 

which are aquifers that are the sole supply of water for a region and are 

critically important to protect. Some stakeholders may assert that there should 

be no CO2 storage above or below a sole source aquifer. However, such a 

restriction could essentially prohibit storage in many Western areas. Rather, a 

better approach would allow EPA to permit UIC Class VI wells in areas where it 

can be shown that there are sufficient caps and protections to prevent the 

migration of CO2 in overlying aquifers, even in proximity to aquifers designated 

as sole source. An early detection monitoring program could be established to 

provide sufficient opportunity to mitigate any unlikely release of CO2 from 

geologic storage unit. 

Approaches like this illustrate how EPA can streamline UIC regulations for site 

characterizations and permit UIC Class VI wells that first and foremost protect 

public safety, yet reflect a workable balance in adapting site characterization 

and risk assessments based on criteria adaptable to unique candidate sites. 

Response: EPA believes that requiring appropriate, site-specific, site characterization by the owner or 

Commenter Name: James T. Sims Letter ID: 0249

Commenter Organization: Western Business Roundtable Comment ID: 22263

694
operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate 

site-specific geologic data will afford the greatest protection of USDWs from endangerment. EPA 

believes that it is important for the Director to have as much site-specific information as possible in 

order to make an informed decision to permit injection for GS at a specific site. This approach allows 

the permit writer to establish requirements considering varying site conditions eliminating the need for 

tiered requirements. GS in areas that may pose risks to USDWs, as assessed and identified by the owner 

or operator and the Director during the site selection process, would not be permitted. EPA disagrees 

that a tiering system for GS sites or formations is appropriate. Instead, the GS rule focuses on evaluating 

the suitability of a site based on site-specific geological and operational data. 

EPA adds that the final GS rule contains a provision (at 146.95) for owners or operators to apply for 

waivers from the requirement that injection be below the lowermost USDW. EPA believes this waiver 

provision will reduce potential limitations on the re-permitting of Class II wells as Class VI wells, 

provided they meet the requirements at 146.95 while still protecting USDWs from endangerment. 

Comment: 7. Avoid Over-Generalization in Regulations - We strongly urge EPA to avoid 

blanket prohibitions or arbitrary absolutes in the rule. As currently proposed, 

EPA’s regulations contain a number of default provisions that presume universal 

application. We believe that approach is problematic. It is too early to 

fully understand precisely which methods or technologies will ultimately prove 

optimal. 

Further, the geologic variability involved in different conceivable GS projects 

needs to be taken into account in issues ranging from site characterization to 

area of review (AOR) to containment requirements. The regulations should 

encourage site-specific, performance-based determinations at the permitting 

stage to handle these important issues. 

EPA should leave the door open for a range of injection sites and methods (some 

of which are not yet fully understood), provided that the Owner or Operator can 

show that the injection and storage will be protective of drinking water 

supplies. 

Response: EPA agrees that permitting decisions for GS wells should be based on site-specific factors. 

The GS rule requires owners or operators to submit, and Directors to consider, extensive site-specific 

data, specified at §146.82, to demonstrate that a site is suitable for GS. Additionally, many of the permit 

requirements for GS wells are established through individualized site-specific plans for AoR and 

corrective action, testing and monitoring, and injection well plugging and post-injection site care and 

site closure. EPA adds that the final GS rule includes a balance of specific criteria to be met by the 

owner or operator and areas of Directorial discretion and considerations for how that discretion would 

be exercised. The Agency believes this balance allows for GS projects to be designed and permitted to 

address the unique, site-specific aspects of each project, while providing consistency in permitting 

across the U.S. 

Rather than setting performance- or technology-based standards for GS projects, EPA is adopting a 

flexible approach, where operators of GS projects would develop and implement site-specific plans for 

delineating the AoR, testing and monitoring the site, performing corrective action, and post-injection site 

care. EPA believes that the plans—which would be reviewed and approved by the Director and 

Commenter Name: James T. Sims Letter ID: 0249

Commenter Organization: Western Business Roundtable Comment ID: 22266

695
periodically updated throughout the life of the project—promote an ongoing dialogue between the 

operator and the Director that will encourage use of the most appropriate technologies for a particular 

project. 

Comment: Carbon capture and geologic sequestration encompasses more than the injection of 

captured CO2. The development of the entire enabling legal and regulatory 

framework, in which legal and regulatory barriers have been identified and 

resolved, to implement CCGS on a commercial scale will require multi-media, 

multi-agency, and multi-statute consideration, including possible amendments of 

existing statutes. In addition to removing barriers to implementation, this 

legal and regulatory framework will need to be flexible and adaptable to 

facilitate the incorporation of new information and experiences gained from the 

numerous pilot CO2 sequestration projects currently in their infancy. Whereas 

CO2 pipeline technology and legal and regulatory framework have reached a status 

of relative maturity due primarily to the use of CO2 in enhanced oil recovery 

for the past 30+ years, CO2 capture technology as applied to coal-fired power 

plants is just beginning to develop. Statutes and regulations governing the 

injection and storage of CO2 should be adaptive to the constraints of the other 

elements of an entire CCGS project (and vice versa) as they are identified. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

Comment: We believe that EPA should make efforts to keep the final rules flexible and 

avoid blanket prohibitions or absolute mandates. In several instances, EPA 

establishes default provisions that apply to all GS sites. Rather than imposing 

such a "one-size-fits-all" approach, we believe that EPA should use performancebased standards and allow site-specific flexibility in meeting those standards. 

Furthermore, the rules should be consistent with already known principles under 

Commenter Name: Walter L. Baker Letter ID: 0253

Commenter Organization: Utah Division of Water Quality Comment ID: 22339

Commenter Name: Mike Nasi Letter ID: 0254

Commenter Organization: Clean Coal Technology Foundation of Texas Comment ID: 22358

696
the Underground Injection Control ("UIC") program, and care should be taken to 

avoid overestimating the risks associated with GS in order to ensure that the 

rules are not overly burdensome. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Other EPA Comment Codes and Descriptions: 4324 2.4.4.1.2 Comments opposed to requiring 

injection below the lowermost USDW 

Comment: 1. Geologic Siting Section 1421(b)(3)(A) of the Safe Drinking Water Act mandates 

that the UIC regulations developed by EPA "permit or provide for consideration 

of varying geologic, hydrological, or historical conditions in different States 

and in different areas within a State." Limiting CO2 injection to geologic 

formations that lie below the lowermost USDW is inconsistent with Congress' 

mandate, and thus, CCTF believes that a blanket constraint that limits injection 

only to reservoirs below the USDW is inappropriate. A performance based approach 

that would place containment requirements on the acceptable reservoirs would be 

more sensible. Accordingly, we believe that the rule should allow a range of 

injection sites and methods provided that the ultimate performance based 

objective of protecting USDWs is achieved. 

Response: EPA acknowledges that there are limited circumstances where injection above the lowermost 

USDW can be performed in a manner that protects USDWs from endangerment, as long as appropriate 

protections are in place. The final GS rule at §146.95 establishes a process by which owners or operators 

can seek a waiver of the Class VI injection depth requirements for injection into non-USDW formations 

above and/or between USDWs. Additionally, the final GS rule does not categorically preclude or 

prohibit injection into any type of formation. 

EPA believes that these requirements will ensure USDW protection while providing flexibility to UIC 

program Directors and owners or operators who undertake CO2 injection for GS. The Agency believes 

this approach: 1) responds to concerns about local and regional geologic storage capacity limitations 

imposed by the proposed injection depth requirements; 2) allows for a more site-specific assessment of 

injection depth for GS projects; 3) accommodates injection into different formation types; 4) allows for 

injection of CO2 for GS into non-USDWs above and/or between USDWs when appropriate and where it 

can be demonstrated that USDWs will be protected; and 5) responds to concerns about the use of aquifer 

exemptions for GS. Finally, EPA’s approach to addressing injection depth variability through a waiver 

process responds to concerns about future drinking water resource availability and the need to ensure 

that high quality water remains available in sufficient quantities to supply drinking water needs. 

For additional information on the waiver approach, please see the final rule and preamble, as well as 

EPA's responses to comments on the Notice of Data Availability and Request for Comment. 

Commenter Name: Mike Nasi Letter ID: 0254

Commenter Organization: Clean Coal Technology Foundation of Texas Comment ID: 22362

697
Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment) 

Comment: 3. Post-Closure Care 

The proposal includes a default monitoring period of 50 years after closure of 

an injection well, but fails to provide the necessary justification for setting 

the default monitoring period for this time period. CCTF does not believe that 

there is a sufficient connection between this time period and the relative risks 

associated with geologic sequestration of CO2. Consistent with our previous 

comments, we urge EPA to incorporate performance-based standards, so as to lead 

to site specific approaches. In this context, we believe that post-injection 

site care should be based on site and project specific characteristics rather 

than a prescribed and lengthy time period, especially a default time period that 

does not seem to be supported by relevant literature. 

Although provision is made in the proposed rule for a potential shortening of 

the post-closure monitoring period, the reality under the existing program is 

that permitting authorities almost without exception default to the maximum 

statutory monitoring period. Because there is no reason to believe that 

permitting authorities will take a different approach here, the practical impact 

of including the 50 year period in the rule will be that operators will be 

required to monitor for that time period with only rare exceptions. There is 

simply no technical justification for such an extended monitoring period, 

especially given the decades of experience showing the 30 year monitoring period 

to be fully protective of human health and the environment. 

Response: EPA disagrees with this comment. In determining the post-injection site care timeframe for 

the proposed regulation, EPA reviewed industry reports, existing environmental programs, and initial 

GS research studies. EPA provided a synthesis of pertinent results from GS modeling studies in the 

preamble to the proposed regulation. Further explanation of this analysis was included in an EPAprepared background document that is available in the federal docket, titled "Computational Modeling of

Underground Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk to 

Underground Sources of Drinking Water." Based on review of these studies, modeling results indicate 

that the CO2 plume stabilization may occur on the timeframe of 10-100 years after the cessation of 

injection. EPA believes that a 50-year default post-injection site care timeframe is a reasonable 

midpoint, and has retained this in the final regulation. 

EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most Class VI wells. 

While the 10- or 30-year timeframe suggested by some of these commenters may be within the 

timeframe suggested in some studies, EPA believes that the potential risks of endangering USDWs will 

likely not decline within these timeframes and available data, including data submitted by commenters, 

do not support a different default timeframe. However, EPA recognizes that alternative timeframes may 

be appropriate under limited, specific circumstances. 

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC 

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the 

post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording 

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the permitting 

process based on substantial data, that an alternative PISC timeframe may be appropriate if it ensures 

Commenter Name: Mike Nasi Letter ID: 0254

Commenter Organization: Clean Coal Technology Foundation of Texas Comment ID: 22366

698
non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for 

post-injection site care will be necessary in all but a limited number of cases. This default 50 year postinjection site care timeframe represents a reasonable and protective monitoring period based on a review 

of research studies, industry reports, and existing environmental programs, and evaluation of public 

comments. 

Comment: We encourage EPA to consider seriously all of these comments which, if taken 

into consideration, could help create a more flexible, performance based Class 

VI program recognizing the characteristics of CO2 injections. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Other EPA Comment Codes and Descriptions: 3820 2.3.1 Well construction procedures 

Comment: III A. 3 Proposed Injection Well Construction Requirements 

Q. EPA seeks comment on the proposed GS well requirements for depth of surface 

casing, the cementing of long-string casing, and construction with a packer set 

opposite a cemented interval. 

IOGCC Response: IOGCC agrees with the need for adequate protection of USDWs and the 

proposed measures. However, Director discretion is necessary to address sitespecific conditions. Well construction should be evaluated so as to insure 

necessary protections of the USDWs, and should not be overly prescriptive. 

Response: EPA agrees that, given the continuing evolution of material design and the numerous 

variables possible in a long-term GS project, listing specific requirements for casing and cement would 

not be appropriate. Rather, requiring that materials must have sufficient structural strength and be 

compatible with fluids with which they may come in contact, in §146.86(b)(1), allows the owner or 

Commenter Name: Dianna Tickner Letter ID: 0262

Commenter Organization: Peabody Energy Comment ID: 22995

Letter ID: 0263

Commenter Organization: Interstate Oil & Gas Compact Commission Comment ID: 22802

699
operator to determine the best casing and cementing design for each project based on information about 

the site and the planned injection and for the Director to approve that design. 

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment); 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: NACCSA urges the Agency to adopt a performance-based approach more in keeping 

with the actual risks posed by CCS projects. NACCSA believes that the site specific 

nature of CO2 storage projects will require each project to be judged on its own 

merit. If a project can show, at any time after the cessation of injection, that 

there is sufficiently small risk of endangerment to USDWs, monitoring should no 

longer be required. Given that under the proposed rule, the program director would 

retain discretion to lengthen or shorten the PISC period as necessary to protect 

USDWs, a performance based approach is in keeping with the spirit of the draft 

rule. Furthermore, performance based approach is more in keeping with the 

realty of potential risks associated with CO2 storage would minimize 

disincentivization of CCS projects while providing an equivalent degree 

of protection for USDWs. NACCSA believes that the performance-based approach, 

currently proposed by EPA as an element of the rule, would be beneficial to 

project operators and investors and for the protection of USDWs. The final rule 

should include specific and appropriate circumstances that the program director 

will consider in exercising discretion in this regard, so that project operators 

and investors have a clear idea of the bar they will be required to meet in order 

to close out the PISC period. 

Response: As described above, EPA agrees that there will be circumstances where it can be 

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of 

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility regarding 

the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the 

PISC timeframe during the post-injection period based on site-specific data, pursuant to requirements at 

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to 

demonstrate, during the permitting process based on substantial data, that an alternative PISC timeframe 

may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters’ concerns, while ensuring USDW protection. Both approaches will utilize site-specific data, 

and be based on pressure monitoring and USDW impacts. 

Commenter Name: Michael Moore Letter ID: 0265

Commenter Organization: North American Carbon Capture & Storage 

Association (NACCSA)

Comment ID: 

22868

700
Comment: (1) Appropriate Level of Regulation -Recognizing mandates under the Safe 

Drinking Water Act (SDWA) for protection of drinking water, there are serious 

concerns about the overall burdens and resource requirements of the proposed 

rules. This concern includes consideration of how such rules may inhibit 

implementation of carbon capture and storage technology. 

The "tailoring," as described by EPA, of the basic regulations for injection of 

nonhazardous industrial waste to the unique characteristics of CO2 injection has 

resulted in proposed requirements that in many aspects exceed the stringency of 

those for injection of hazardous waste. This excessive stringency is particularly 

present in the proposed requirements for iterative computational modeling of the 

CO2 plume and pressure front, and the model's proposed influence on a project's 

area of review, corrective action, monitoring, post-injection site care, 

closure, and financial assurance. Many of these concerns have been expressed in 

the CO2-GS Workgroup process by state and federal staff responsible for 

regulation of the nation's largest concentration of Class I hazardous waste 

injection wells. As an additional consideration, the lack of significant 

environmental or health risks evident from our state's experience in CO2 

injection for enhanced recovery of oil and gas under regulation by the Railroad 

Commission does not provide a supporting basis for the unprecedented stringency 

of Class VI requirements as proposed by EPA. 

Response: EPA disagrees that the Class VI requirements are overly stringent; instead, the GS 

requirements are tailored to the unique nature of GS, including the large volumes of CO2 injected, its 

buoyancy and potential corrosivity in the presence of water, and impurities in the CO2 stream. EPA 

believes these tailored requirements are more appropriate than Class I or Class II requirements. Please 

see the remainder of EPA's responses to this comment for further details. For additional information on 

EPA's final regulatory approach, please see the final rule and preamble as well as the rulemaking docket.

The Agency believes that the Class VI requirements balance site-specific flexibility with USDW 

protection. Rather than setting performance or technology-based standards for GS projects, EPA is 

adopting a flexible approach, where operators of GS projects would develop and implement site-specific 

plans for delineating the AoR, testing and monitoring the site, performing corrective action, and postinjection site care. EPA believes that the plans—which would be reviewed and approved by the Director 

and periodically updated throughout the life of the project—promote an ongoing dialogue between the 

operator and the Director that will encourage use of the most appropriate technologies for a particular 

project. 

Other EPA Comment Codes and Descriptions: 1480 1.2.2.2.2 CO2 is not a pollutant 

Comment: With regard to the appropriate level of regulation, EPA has described the rule 

development as an adaptive process occurring over a period of years with careful 

consideration of stakeholder and general public comment, and results of research 

including experimental CO2 injection projects worldwide. This process includes 

the possibility of future revision of the final adopted rules in response to 

accumulating knowledge from project operational experience, research, and 

increasing public confidence in capture and sequestration technology. Concern 

Commenter Name: Mark Vickery Letter ID: 0280

Commenter Organization: Texas Commission on Environmental Quality Comment ID: 24098

Commenter Name: Mark Vickery Letter ID: 0280

Commenter Organization: Texas Commission on Environmental Quality Comment ID: 24105

701
however remains that overly burdensome regulations may seriously impede the 

technology in a manner not easily correctable by later rule revisions, 

especially considering the experience from CO2 injection in Class II well 

enhanced recovery projects indicating no significant environmental or health 

risks. EPA should strive to protect drinking water sources as mandated by the 

SDWA while imposing reasonable and proven controls on carbon sequestration, not 

onerous burdens without risk-based justification or cost effectiveness. 

Reasonable and proven controls will encourage responsible parties to voluntarily 

implement carbon capture and storage technology. In short, carbon is not a 

hazardous material and responsible industries need incentives, rather than 

unreasonable stringency, to participate in the program. Otherwise, the United 

States may not realize the benefits of carbon geosequestration. 

Response: EPA believes the final GS rule addresses the commenter’s concern that it protects drinking 

water sources while imposing reasonable and proven controls. The GS rulemaking builds upon decades 

of knowledge about safe injection practices regulated by the UIC Program (including the oil and gas 

industry’s decades of experience injecting CO2 for the purpose of ER). The final GS rule contains new 

requirements for Class VI wells that are tailored to address the unique nature of full-scale CO2 GS, 

including the injection volumes anticipated for long-term storage, the buoyant nature of the injectate, its 

corrosivity in the presence of water, and its mobility within subsurface geologic formations. 

EPA remains committed to an adaptive approach. The Agency plans to, every six years, collect and 

review data on GS projects to determine whether the appropriate amount and types of information and 

appropriate documentation are being collected, and to determine if modifications to the requirements are 

appropriate or necessary. An adaptive approach will allow regulatory development to proceed in time to 

meet the current and future demands for Class VI permits while EPA continues to gather data from pilot 

projects and other research as it becomes available. 

EPA adds that the intent of the GS rule is not to promote GS. Rather, the purpose of the GS regulation is 

to assure that, where deployed, GS is conducted in a manner that protects USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 5610 2.11.1 Allowing partial primacy for Class VI 

wells (seeking comment) 

Comment: (3) Flexibility and Streamlining in Class VI Program Primacy Considerations - 

TCEQ concurs with EPA's assessment that current options for injection of CO2 

include Class I, ClassII, and ClassV wells. Accordingly, under state law, injection 

of CO2 in Texas will be regulated by either the TCEQ or the Railroad Commission 

(RRC). Noting the RRC's responsibility for Class II injection (including CO2 

injection for enhanced recovery of oil and gas), TCEQ is responsible for Class I 

and most of Class V (including experimental injection of CO2). Class VI as 

proposed by EPA, under state law, would appear to be in TCEQ's jurisdiction. 

Section 27.022, Texas Water Code provides: "The commission has jurisdiction over 

the injection of carbon dioxide produced by a clean coal project, to the extent 

authorized by federal law, into a zone that is below the base of usable quality 

water and that is not productive of oil, gas, or geothermal resources". However, 

such jurisdictional lines are subject to change by state legislation. 

Flexibility will therefore be needed in federal authorization of the Class VI 

well program at whichever agency is designated by the state legislature. 

Commenter Name: Mark Vickery Letter ID: 0280

Commenter Organization: Texas Commission on Environmental Quality Comment ID: 24111

702
Flexibility in this sense primarily means free from constraints that EPA has 

traditionally imposed by bundling various well classes into an "all or nothing" 

condition for program primacy. 

Response: EPA agrees with commenters that states should be allowed to obtain primacy for Class VI 

wells independently of other well classes, and will allow independent primacy for Class VI wells under 

§145.1(i) of the final GS rule. EPA believes that allowing independent Class VI primacy may encourage 

states to take responsibility for implementation of Class VI regulations and provide for a more 

comprehensive approach to managing CCS projects by promoting the integration of GS activities under 

SDWA into a broader framework for managing CCS. Furthermore, GS operations involve ancillary 

activities (e.g., pipeline operations, pore space ownership, land use rights, and surface access) for which 

states can call upon other authorities that exist at the state level (but outside UIC authority) to provide a 

more comprehensive CCS management approach. 

EPA also believes that allowing states to apply only for Class VI primacy will shorten the primacy 

approval process for states. EPA's willingness to accept independent primacy applications for Class VI 

wells represents a shift in its longstanding policy of discouraging "partial primacy." It is very important 

to note that this shift in policy allowing for Class VI primacy does not apply to any other well Class 

under Section 1422. EPA will continue to discourage applications for partial primacy for all other well 

types under Section 1422. 

EPA clarifies that states should be able to obtain primacy for Class VI wells independent of other well 

classes provided they develop regulations that are at least as stringent as the minimum Federal 

requirements (e.g., permitting, inspection, operation, monitoring, and recordkeeping requirements) 

provided in the final GS rule. EPA believes that existing programs can adapt their expertise to the new 

requirements for Class VI wells and will be able to develop a primacy application for Class VI wells 

under section 1422 of SDWA and ensure that their GS programs integrate into national climate change 

priorities and protect USDWs from endangerment. 

EPA also clarifies that primacy is granted to a state, not to any agency within that state, and states are 

free to choose which agency will implement the Class VI program—for instance, an environmental 

quality protection agency (non-Class II) or the state's traditional oil and gas regulatory agency (Class 

II)—as long as the program meets the minimum Federal requirements for Class VI wells as required 

under section 1422 of SDWA. Some states administer their program for all injection well classes 

through a single agency, whereas other States elect to divide the program between agencies. For 

example, in most States, the Class II program is run by an oil and gas agency and other well classes are 

run by a State environmental agency (e.g., the Oklahoma Corporation Commission oversees Class II 

wells in the State, and the Oklahoma Department of Environmental Quality oversees other well classes). 

Additionally, several States allow their oil and gas agencies to administer their UIC program for specific 

well classes or subclasses provided they meet all Federal requirements (e.g., the Texas Railroad 

Commission oversees Class III brine-mining wells and Class V geothermal wells in Texas). EPA 

believes that retaining this flexibility for States to identify the appropriate agency to oversee Class VI 

wells will address commenters’ concerns that States should be afforded the opportunity to determine 

which agency should oversee Class VI wells, and recognizes the existing expertise of both State oil and 

gas agencies and environmental agencies. 

Comment: Our second message to the EPA today addresses the regulatory flexibility. We 

believe that the agency should be cautious in overly prescriptive regulation, 

Commenter Name: Karl R. Moor Letter ID: 0501

Commenter Organization: Southern Company Comment ID: 21162

703
one size fits all approaches to siting. No two geological formations are the 

same, no two CCS projects will be the same. And the geological formations in 

which CO2 is injected will be defined by a number of characteristics. We believe 

the many instances and the regulation has chosen to tie with the regulated 

entities to a -- whether it be -- of responsible, duration of responsibility 

award, financial assurance responsibility. 

In all of these instances where EPA has said that there is one defining 

characteristic, it will tie the regulated entity's hands to an existing set, a 

new set of regulatory prescriptions with the EPA has not done good service to 

the industry or to the development of GS technology? 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Comment: Next, EPA should also reconsider its proposed well construction and operation 

requirements, which are much more prescriptive and rigorous than necessary, and 

do not reflect industry's 35 plus years of success in rejecting CO2 under the 

Class II UIC program. 

Response: EPA disagrees that the Class VI requirements are overly stringent; instead, the GS 

requirements are tailored to the unique nature of GS, including the large volumes of CO2 injected, its 

buoyancy and potential corrosivity in the presence of water, and impurities in the CO2 stream. EPA 

believes these tailored requirements are more appropriate than Class I or Class II requirements. Please 

see the remainder of EPA's responses to this comment for further details. For additional information on 

EPA's final regulatory approach, please see the final rule and preamble as well as the rulemaking docket.

The Agency believes that the Class VI requirements balance site-specific flexibility with USDW 

protection. Rather than setting performance or technology-based standards for GS projects, EPA is 

adopting a flexible approach, where operators of GS projects would develop and implement site-specific 

plans for delineating the AoR, testing and monitoring the site, performing corrective action, and postinjection site care. EPA believes that the plans—which would be reviewed and approved by the Director 

and periodically updated throughout the life of the project—promote an ongoing dialogue between the 

operator and the Director that will encourage use of the most appropriate technologies for a particular 

project. 

Comment: In conclusion, API shares the same goal as EPA, to develop rules that facilitate 

the safe, secure, long-term storage of CO2. API is concerned though that by 

being overly prescriptive in designing the new well class the proposed rule 

Commenter Name: Michele Schoepper Letter ID: 0503

Commenter Organization: American Petroleum Institute Comment ID: 21176

Commenter Name: Michele Schoepper Letter ID: 0503

Commenter Organization: American Petroleum Institute Comment ID: 21179

704
hinder the deployment of CCS and could have the unanticipated consequence of 

hindering innovations that could improve both well security and performance. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

Comment: So, in conclusion, wells are indeed a fundamental component of a geologic 

storage system, having appropriate design, construction, and operating 

expectations for these wells is necessary to ensure delivery of a secure storage 

CO2. 

Site-specific performance based guidelines, as per the well-related example that 

I note previously, do serve to, do serve the purpose of requiring application of 

appropriate technological solutions to protect USDWs. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Comment: I also want to agree with the American Petroleum Institute and Iain Wright, that 

the standard for site closure in the proposed rule needs to be improved. We 

agree that the standards should be site-specific and performance based. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

Commenter Name: Brian Williams Letter ID: 0507

Commenter Organization: BP Alternative Energy Comment ID: 21169

Commenter Name: Scott Anderson Letter ID: 0510

Commenter Organization: Environmental Defense Fund Comment ID: 21216

705
particular project. 

Comment: defined using reasonable risk based criteria. EPA should also reconsider its 

proposed well construction and operating requirements which are much more 

prescriptive and rigorous than necessary and do not reflect industries thirtyfive plus years of success in injecting CO2 under the Class II UIC program. 

Response: EPA disagrees that the Class VI requirements are overly stringent; instead, the GS 

requirements are tailored to the unique nature of GS, including the large volumes of CO2 injected, its 

buoyancy and potential corrosivity in the presence of water, and impurities in the CO2 stream. EPA 

believes these tailored requirements are more appropriate than Class I or Class II requirements. Please 

see the remainder of EPA's responses to this comment for further details. For additional information on 

EPA's final regulatory approach, please see the final rule and preamble as well as the rulemaking docket.

The Agency believes that the Class VI requirements balance site-specific flexibility with USDW 

protection. Rather than setting performance or technology-based standards for GS projects, EPA is 

adopting a flexible approach, where operators of GS projects would develop and implement site-specific 

plans for delineating the AoR, testing and monitoring the site, performing corrective action, and postinjection site care. EPA believes that the plans—which would be reviewed and approved by the Director 

and periodically updated throughout the life of the project—promote an ongoing dialogue between the 

operator and the Director that will encourage use of the most appropriate technologies for a particular 

project. 

Comment: In conclusion, API shares the same goal as EPA to develop rules that facilitate 

the safe, secure, long term storage of CO2. API is concerned that if by being 

overly prescriptive in designing a new well class, the proposed rule will hinder 

the development of CCS and could have the unanticipated consequence of hindering 

the innovations that could improve both well security and performance. CCS is 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

Commenter Name: Steve Crookshank Letter ID: 0523

Commenter Organization: American Petroleum Institute (API) Comment ID: 21359

Commenter Name: Steve Crookshank Letter ID: 0523

Commenter Organization: American Petroleum Institute (API) Comment ID: 21362

Commenter Name: George Peridas Letter ID: 0534

Commenter Organization: Natural Resources Defense Council (NRDC) Comment ID: 21455

706
Comment: trigger for major revisions to the rule. I do not think that is necessary. I 

mean, it really does depend on how the rule is phrased and to what extent it is 

flexible and performance based and I think if I weigh in that direction. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Comment: The fundamental challenge confronting EPA in this rulemaking is to establish a 

cost effective and environmentally sound regulatory program to cover a range of 

operations for which the technology will not be commercially deployed for a 

number of years. To meet this challenge and to establish a workable regulatory 

framework over the coming decades for the long term storage of carbon dioxide, 

EPA must craft regulations with flexibility so that it may be fine tuned as 

industry and regulations alike gain experience with large scale carbon dioxide 

sequestration. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

Comment: Because information related to carbon sequestration is sure to develop, Ameren 

urges EPA to avoid blanket probations or arbitrary absolutes in the final rule. 

We agree that the standard underlying protective rule requirements for carbon 

dioxide sequestration is the protection of underground sources of drinking 

water. However, because it is difficult to know at this point what future 

technologies will be developed for injection and long term storage of carbon 

dioxide in the manner that is protective of these drinking water sources. But 

because there is, there should be a significant demand for the capacity to store 

Commenter Name: Paul Pike Letter ID: 0535

Commenter Organization: Ameren Corporation on behalf of Utility Solid Waste 

Activities Group (USWAG)

Comment ID: 

21433

Commenter Name: Paul Pike Letter ID: 0535

Commenter Organization: Ameren Corporation on behalf of Utility Solid Waste 

Activities Group (USWAG)

Comment ID: 

21434

707
this CO2, EPA should not prematurely preclude injection in certain specific 

types of sites or through certain methods. The final rule should leave the door 

open for a range of injection options, sites and methods, some of which are 

unrecognized or even unknowable at this point in time provided that the ltimate 

objective of protecting the underground sources of drinking water is achieved. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

To address the comment that the rule should accommodate future technological developments related to 

GS, EPA adds that it is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, EPA plans, every six years, to collect and review project data on GS 

research projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Comment: Because of wildly varied characteristics and limitations of sites and projects, 

it is important to incorporate performance based standards into the final rule 

waiting for site specific approach to requirements for site review, reevaluation 

and post injection site care and closure. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Comment Code: 1260 1.1.1.5 More certainty/stringency is needed 

Individual Comments 

Other EPA Comment Codes and Descriptions: 1500 1.2.2.2.4 Some other agency should regulate 

Commenter Name: Paul Pike Letter ID: 0535

Commenter Organization: Ameren Corporation on behalf of Utility Solid Waste 

Activities Group (USWAG)

Comment ID: 

21439

Commenter Name: Emily Rochon Letter ID: 0129

Commenter Organization: Greenpeace International Comment ID: 23076

708
GS; 1510 1.2.2.3 Need for additional study 

Comment: that are consistent with what Greenpeace believes must be done, however a more 

comprehensive regulatory structure is what is truly needed before any carbon 

capture and sequestration project can be allowed to start. 

Response: As described above, EPA believes that establishing a regulatory framework for the future 

development and deployment of CCS technology provides a framework for injecting CO2 so that the 

activity does not result in endangerment of USDWs. 

Further, as described above, the Agency will continue to coordinate on GS and CCS related issues to 

minimize redundancy and maximize efficiencies for owners or operators. For additional information, 

please see the discussion entitled "How Does This Rulemaking Relate to Other Federal Authorities and 

GS and CCS Activities?" in the preamble to the final GS rule. 

Other EPA Comment Codes and Descriptions: 1970 1.4.4.6 Need for other consultations 

Comment: II. Regulatory Oversight 

Regional Advisory Boards: Establish a Carbon Capture and Sequestration Advisory 

Board for each of the EPA's ten regional offices (according to guidelines under 

40 CFR 25.7), in order to optimally administer a "Tailored Requirements 

Approach" that applies national standards which are adaptive to a variety of 

regional differences in geological formations, natural resources, weather 

patterns, industrial operations, and applicable state laws. 

Response: EPA clarifies that establishing a Carbon Capture and Sequestration Advisory Board is out of 

the scope of the GS rulemaking. EPA adds that the Agency plans to collect and review data every six 

years on GS projects to determine whether the appropriate amount and types of information and 

appropriate documentation are being collected, and to determine if modifications to the requirements are 

appropriate or necessary. As part of this adaptive rulemaking approach, EPA will consult with a variety 

of stakeholders, including the National Drinking Water Advisory Council, associations and 

organizations, ORD, and experts to ensure that implementation of the national Class VI program is 

based on the best available science. 

Other EPA Comment Codes and Descriptions: 1970 1.4.4.6 Need for other consultations 

Comment: Regulatory Oversight 

D. Regional Advisory Boards 

Recommendation D: Establish a Carbon Capture and Sequestration Advisory Board 

Commenter Name: Anonymous2 Letter ID: 

0133

Commenter Organization: Sierra Club National Global Warming and Energy 

Committee and Sierra Club California-Nevada Regional Conservation Committee on 

Energy and Climate Change

Comment ID: 

21581

Commenter Name: Anonymous2 Letter ID: 

0133

Commenter Organization: Sierra Club National Global Warming and Energy 

Committee and Sierra Club California-Nevada Regional Conservation Committee on 

Energy and Climate Change

Comment ID: 

21606

709
for each of the EPA's ten regional offices (according to guidelines under 40 CFR 

25.7), in order to optimally administer a "Tailored Requirements Approach" that 

applies national standards which are adaptive to a variety of regional 

differences in geological formations, natural resources, weather patterns, 

industrial operations, and applicable state laws. 

Response: EPA will continue to consult with a variety of stakeholders, including the National Drinking 

Water Advisory Council, associations and organizations, ORD, and experts; review permits; and 

continue to hold workshops to build expertise and ensure that implementation of the national program is 

based on the best available science. The Agency plans to collect and review data every six years on GS 

projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Other EPA Comment Codes and Descriptions: 5600 2.11 Comments related to UIC Program primacy 

for Class VI wells 

Comment: 2.EPA should set standards and criteria that will result in reasonably 

consistent implementation and results regardless of geographic location. 

3.EPA should establish a hierarchy of authority for decision making and 

oversight, to ensure interstate and inter- jurisdictional conflicts are avoided. 

In this, Global appreciates that some states have moved ahead to implement 

carbon management programs. However, it is our view that effective and early 

implementation will be best served by consistency across the board. We 

therefore encourage EPA to review the programs of all states and select the 

common threads that are most suitable to early and effective implementation. 

Response: EPA agrees that it is important to balance flexibility and national consistency. The GS rule 

sets forth minimum Federal requirements, tailored to the unique nature of CO2 GS, which must be met 

in order to ensure USDW protection from endangerment. EPA acknowledges the importance of 

flexibility for certain Class VI well requirements given the variety of geologic settings in which GS will 

be applied and therefore affords the Director discretion when making permitting decisions. Such 

requirements where the Director has discretion include whether to require owners or operators to 

identify and characterize additional confining zones, as specified in §146.83, whether to require surface 

air monitoring and/or soil gas monitoring, as specified in §146.90, and whether to extend or shorten the 

post-injection site care period or approve an alternative post-injection site care timeframe as part of the 

permitting process, as specified in §146.93. The GS rule balances the need for site-specific decisions 

with the need for minimum standards to ensure national consistency and USDW protection from 

endangerment while also ensuring that states have the data they need to make permitting decisions. EPA 

Headquarters also plans to review initial permits to ensure that the final rule, including all permitting 

decisions, are implemented consistently, and to ensure that USDW protection goals are consistently met 

across differing geologic situations. 

EPA understands that the CO2 plumes for large GS projects may cross State, Tribal, Territorial, or EPA 

Regional boundaries. The final GS rule, at §146.82(a)(2), requires the owner or operator to identify all 

State, Tribal, and Territorial boundaries within the AoR. Based on this information, the Director must 

provide written notification to all States, Tribes, and Territories to inform them of the permit application, 

as specified in §146.82(b), and ensure that they are involved in any necessary processes (e.g., 

Commenter Name: Dwight Lockwood, PE, QEP Letter ID: 0141

Commenter Organization: Global Energy, Inc. Comment ID: 23094

710
development of the emergency and remedial response plan, as specified in §146.94). The Agency 

encourages transparency in the permitting process and anticipates that State-State/State-Tribal 

communication on GS permitting will facilitate information sharing and encourage safe, protective 

projects. 

Because some GS projects will require coordination across State, Tribal, and Territorial jurisdictions, the 

Agency will work with the appropriate entities to facilitate communication among States, Tribes, and 

Territories during the implementation phase of the GS regulation. Such communication may involve 

other organizations such as the Sierra Club, NDWAC, associations, and other experts. However, the 

responsibility for addressing such subjects ultimately rests with the States, Tribes, and Territories with 

primacy. EPA is developing primacy implementation materials for states that describe recommended 

approaches to addressing trans-boundary issues during the permitting of Class VI wells under the GS 

regulation. The materials will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

In response to questions about which state or region would oversee the permit for projects where the 

AoR spans State, Tribal, or Territorial boundaries, EPA clarifies that issuance and oversight of a GS 

permit, including any associated AoR boundary-related coordination, is the responsibility of the primacy 

(State, Tribe, or Territory) or regional DI program in the state where the injection well is located. 

Comment: EPRI COMMENT#1: The proposed rule allows the EPA Director to make discretionary 

decisions regarding numerous program elements including, but not limited to, 

characterization, monitoring, testing, and site closure. EPRI urges EPA to 

provide clarity in the final rule regarding the technical or administrative 

criteria that trigger the need for discretionary decision making. 

Response: EPA is developing guidances for States that describe the process of applying for and 

receiving primary enforcement authority (primacy) for GS Class VI wells under Section 1422 of 

SDWA, as well as the technical and administrative issues on developing GS regulations that are the 

equivalent of minimum federal criteria and requirements. The guidance will describe areas of Directorial 

discretion and considerations for how that discretion would be exercised. This guidance will be available 

on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

The Agency believes that the Class VI requirements balance site-specific flexibility with USDW 

protection. Rather than setting performance or technology-based standards for GS projects, EPA is 

adopting a flexible approach, where operators of GS projects would develop and implement site-specific 

plans for delineating the AoR, testing and monitoring the site, performing corrective action, and postinjection site care. EPA believes that the plans—which would be reviewed and approved by the Director 

and periodically updated throughout the life of the project—promote an ongoing dialogue between the 

operator and the Director that will encourage use of the most appropriate technologies for a particular 

project. 

Comment: experience is for the power plant sector. Regardless of the actual future volume 

of injection (or perhaps the ultimately limited success of carbon separation and 

ultimate injection), a practical Class VI permitting system is essential. Given 

Commenter Name: Michael J. Miller Letter ID: 0168

Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22491

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23391

711
the direct impact this program will have on the electric utility industry, APPA 

genuinely appreciates EPA's goal of establishing a regulatory regime that will 

provide "certainty" and "transparency" to what requirements would apply to 

owners/operators who engage in Class VI CO2 injection. Id. at 43496 (July 25, 

2008). At the same time, it is crucial for the regulations to reflect the 

Response: EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, 

GS is conducted in a manner that protects USDWs from endangerment. Encouraging investment in CCS 

projects and facilitating deployment are outside the scope of the GS rulemaking. 

Other EPA Comment Codes and Descriptions: 1620 1.3.2 Induced seismicity 

Comment: Because information and technology related to carbon sequestration are sure to 

develop as more experience is gained, APPA urges EPA to do what it can avoid the 

use of arbitrary or blanket prohibitions or absolutes in the EPA final rule. 

However, APPA believes that there are some common sense prohibitions that may be 

justifiable. For example, EPA should have in the final rule an explanation, 

consistent with the Class I program, that seismic-induced subsurface conveyance 

risks such as major faults, or proximity to sole source aquifer [FN5] 

protections are essential. Sole source aquifers are not the same as deep saline 

aquifers. APPA believes there are some prohibitions that are key to protection 

of USDWs. At the same time we do not want to contribute to "NIMBY" or "not in my 

backyard" or "NUMBY" - or "not under my back yard". What APPA asks for in the 

context of seismicity issues are clear-cut and understandable parameters or USGS 

guidelines so that power plant owner/operators don't pursue a geologic formation 

thinking that it is eligible only to learn that the EPA has used a USGS 

designation on seismic risks that would render it disqualified later in the 

permitting process. APPA asks that when the EPA or state directors make 

seismicity conditions that these be subject to notice and comment and be 

published in the Federal Register and the state equivalent publication. It would 

be terrible to have a power plant owner/operator spend time and significant 

money pursuing a geologic formation only to learn after he had spent many 

hundreds of thousands of dollars that the site did not meet the EPA’s seismic 

risk or USGS seismic requirements. Seismicity risk avoidance is a new factor for 

thermal or fossil plants and not one with which we have experience. APPA 

includes in the Appendix a paper from an NETL-funded study on seismic activity 

induced by injection of CO2 into deep saline aquifers [FN6] and an article 

regarding the Greek government’s concerns with injection of CO2 in the 

Mediterranean. [FN7] [See EPA-HQ-OW-2008-0390-0169.pdf for these documents.] 

Including these references to seismic issues does not mean that APPA fears that 

CO2 will cause seismic activity. Instead APPA does not want to see APPA member 

utilities pursue geology which has underlying seismic risks that are unknown to 

the power sector (and perhaps to the state agencies) and misuse critical 

resources, time and money pursuing that location for permitting only to find out 

later that they must start again. Most locations in the U.S. have not had recent 

seismic data assessed at the "fine granular" level needed to target the right 

formations for carbon dioxide geosequestration. This will necessitate the 

support of United States Geologic Survey and other agencies. 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23396

712
[FN5] A sole source aquifer (SSA) is an underground water supply designated by 

the U.S. EPA as the "sole or principal" source of drinking water for an area 

under Section 1424(e) the Safe Drinking Water Act of 1974. "Sole or principal" 

has been interpreted to mean that the aquifer must supply at least 50 percent of 

the drinking water to persons living over the aquifer; there should be no 

alternate and feasible sources of drinking water that could replace the aquifer. 

[FN6] Issues Related to Seismic Activity Induced by the Injection of CO2 in Deep 

Saline Aquifers, Joel Sminchak and Neeraj Gupta, Battelle Memorial Institute 

[FN7] "Why doesn't Greece like carbon capture?" Leigh Phillips, EU Observer, 

9/23/08, http://euobserver.com/19/26794 

Response: The GS rule, at §146.82(a)(5) requires prospective owners or operators to submit information 

on all USDWs within the AoR. EPA expects that this information will include identification of any sole 

source aquifers. The GS rule also requires operators to submit extensive information about the site, 

including the geologic characteristics of the injection and confining zones, to demonstrate that the 

injected CO2 will remain within the target formation. The Director must consider this information when 

determining whether GS is acceptable at a given site. EPA expects that during this evaluation the 

Director will consider the potential impact of the GS project on any sole source aquifers. 

Regarding seismicity, EPA acknowledges that induced seismicity is a risk that may be associated with 

GS but maintains that the risk is low (IPCC, 2005). The GS rule contains several requirements to 

address seismic risk. First, as part of the site characterization process, owners or operators must submit 

information about the seismic history of and seismic sources near a proposed GS site, data on known or 

suspected faults in the AoR, geomechanical information on fractures, stress, ductility, rock strength, and 

in situ fluid pressures within the confining zone as specified in §146.82(a)(3). This information is 

evaluated by the Director, who determines the suitability of a potential project site for GS. Any sites 

with the potential for reopening or reactivation of faults or unacceptable seismic risk that could 

otherwise interfere with containment will not be permitted as GS sites. During injection, the pressure in 

the injection zone must not exceed 90 percent of the fracture pressure of the injection zone as specified 

in §146.88(a); this requirement is intended to prevent the opening of fractures or faults through over 

pressurization of the injection zone. 

EPA clarifies that the rule does not contain any specific requirements describing "seismically 

appropriate" areas, and does not believe this is appropriate for all sites. EPA believes such 

determinations should be made on a site-specific basis. If such information is available, and the Director 

determines it to be relevant to the site characterization, it is in their authority to require detailed 

evaluations. However, EPA disagrees that this should be a requirement for all GS projects. In many 

cases, UIC Directors will have extensive knowledge of which areas are suitable for GS, but clarifies that 

it is the responsibility of Class VI permit applicants to demonstrate the suitability of a particular site or 

formation. It is the responsibility of the Director to evaluate the information collected and submitted by 

the owner or operator to determine whether a permit for GS at the site is appropriate. 

EPA is developing guidance on site characterization for GS projects to assist owners or operators and 

Directors in evaluating permit requirements and applications under §146.82. The guidance provides 

recommendations to owners or operators regarding information to support characterizing the regional 

geology and hydrogeology of a proposed GS site as well as how to perform the necessary geochemical, 

geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this 

guidance will assist permit writers/UIC Directors in making an objective decision about requiring 

additional confining layers. The guidance can be found on EPA’s website at 

713
http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Other EPA Comment Codes and Descriptions: 1420 1.2.1.1 Support the GS rulemaking 

Comment: VII. Conclusion 

ELPC and ETIP support many portions of the EPA's proposed regulations and 

commend the EPA for implementing safeguards for GS that go beyond those required 

for other classes of injection wells. For example, we are pleased to see that 

EPA has provided flexibility in the choice of construction materials used by 

well owners while preserving rigorous construction standards. Our primary 

objection to the regulations, however, is that they constitute a piecemeal 

approach to regulation ofGS (and CCS), thus leaving several issues unaccounted 

for. The lack of certainty on issues of liability, financial assurance, and 

well-closure standards, could both stifle the use ofGS as a climate change 

mitigation tool and place the public at greater risk. 

Response: EPA acknowledges that GS falls within the broader context of CCS and the need for 

regulatory clarity to ensure that USDWs are protected from endangerment. In developing the final GS 

rule, the Office of Water coordinated with other Agency program offices and across federal agencies 

(e.g., with the Department of Energy; United States Geological Survey; Bureau of Ocean Energy 

Management, Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of 

Land Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

EPA recognizes that liability is an important issue to owners or operators; however the Agency does not 

have authority under the SDWA to transfer long term liability from owners or operators to the state or 

federal government. Therefore, liability remains with the owner or operator. EPA notes that the final 

rule clarifies the requirements for the use of financial responsibility instruments for GS. In addition, the 

final rule requires owners or operators to address well plugging in well plugging plans submitted with 

the Class VI permit application. EPA is developing guidance manuals for owners or operators that 

describe the financial responsibility and injection well plugging requirements in the GS rule. 

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performance-based 

standards) 

Comment: 4. For an activity covering such a diverse geographic, geologic, and commercial 

spectrum as GS, NiSource believes it is essential to incorporate considerable 

regulatory flexibility. However, some relatively high minimum standards of 

technical requirements should be established in key areas. While this may sound 

Commenter Name: Wendy Jacobs Letter ID: 0183

Commenter Organization: Harvard Law School Environmental Law and Policy 

Center

Comment ID: 

25169

Commenter Name: Daniel Plath Letter ID: 0188

Commenter Organization: NiSource, Inc. Comment ID: 25232

714
contradictory, NiSource's observation is that firmly addressing those few real 

risks will ultimately pay significant dividends by preventing a few "bad" 

projects from being developed that ultimately lead to an avoidable incident that 

taints the entire industry. These issues are addressed below. 

Response: The Agency believes that the Class VI requirements balance site-specific flexibility with 

USDW protection. Rather than setting performance or technology-based standards for GS projects, EPA 

is adopting a flexible approach, where operators of GS projects would develop and implement sitespecific plans for delineating the AoR, testing and monitoring the site, performing corrective action, and 

post-injection site care. EPA believes that the plans—which would be reviewed and approved by the 

Director and periodically updated throughout the life of the project—promote an ongoing dialogue 

between the operator and the Director that will encourage use of the most appropriate technologies for a 

particular project. 

Other EPA Comment Codes and Descriptions: 1210 1.1.1 Comments about the proposed rule 

Comment: Issue 2. Under the proposed rule, full-scale implementation can begin after 

finalization. 

The EPA is encouraged to consider limiting the scale of projects initially in 

order to identify issues that may crop up that are currently unanticipated. The 

early large scale projects should be extensively monitored in order to validate 

concepts that can be applied to other locations. This early work should include 

validation of appropriate modeling techniques capable of reliably predicting 

system responses. This early proof of concept work should also address issues of 

heterogeneity in reservoir and confining zones. 

Response: EPA clarifies that the intent of the GS rule is not to set or control the pace at which GS is 

deployed. Rather, the purpose of the GS regulation is to ensure that GS, where deployed, is conducted in 

a manner that protects USDWs from endangerment. The Class VI GS requirements are one way in 

which the Agency can achieve this goal. EPA does not intend to limit the scale of initial GS projects; 

each project will be evaluated based on site-specific information about the ability of the geologic 

formations to safely receive and confine injected CO2. However, the Agency agrees that a protective 

initial approach is appropriate and additional safeguards are necessary, given the uncertainty associated 

with the long-term effects of CO2 GS. EPA plans, every six years, to collect and review data on GS 

projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Comment: On behalf of our members, WORC urges EPA to establish as its highest priority 

the safety and effectiveness of the Carbon Dioxide Geologic Sequestration Wells 

program. We are very concerned that EPA is moving forward with a regulatory 

program for a technology that has yet to be demonstrated to be technologically 

and commercially viable on a large scale. It is possible that the first 

generation of geologic sequestration sites will experience a variety of 

problems, as demonstrated by the FutureGen project, in which unanticipated 

Commenter Name: Andy Horn Letter ID: 0196

Commenter Organization: Colorado Ground Water Association (CGWA) Comment ID: 23922

Commenter Name: Randy Joseph Letter ID: 0240

Commenter Organization: Western Organization of Resource Councils Comment ID: 23217

715
technological challenges and budget overruns caused the Department of Energy to 

abandon the project. 

Taking into account the potential challenges of this technology that is not yet 

proven at scale, especially the unique challenges that the western US faces, we 

propose instead of going forward with large-scale implementation of technology 

that is yet unproven and untested, that EPA focus intently on the research and 

design aspect at a limited number of pilot sites to ensure that carbon capture 

and storage of CO2 is appropriate. 

If EPA does go forward with its regulations, we urge you to use extreme caution 

and establish requirements that are as stringent as necessary, even though those 

requirements are likely to be more expensive than other parts of the UIC 

program. 

Our primary concerns are as follows: 1) protecting water supplies from 

contamination 2) ensuring that geologic sequestration projects are safely sited, 

3) protecting the interests of landowners. 

Response: EPA clarifies that the intent of the GS rule is not to set or control the pace at which GS is 

deployed. Rather, the purpose of the GS regulation is to ensure that GS, where deployed, is conducted in 

a manner that protects USDWs from endangerment. The Class VI GS requirements are one way in 

which the Agency can achieve this goal. EPA does not intend to limit the scale of initial GS projects; 

each project will be evaluated based on site-specific information about the ability of the geologic 

formations to safely receive and confine injected CO2. However, the Agency agrees that a protective 

initial approach is appropriate and additional safeguards are necessary, given the uncertainty associated 

with the long-term effects of CO2 GS. EPA plans, every six years, to collect and review data on GS 

projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Other EPA Comment Codes and Descriptions: 1614 1.3.1.2 Impurities in captured CO2; purity 

standards for CO2 

Comment: We do not want to contaminate our groundwater with those carcinogens. The fact 

is that CCWs, this is a significant issue in that each year our power plants 

produce enough of this stuff to fill a train of coal cars that stretches from 

Manhattan to Los Angeles not just once, not just twice, but three and a half 

times. It is a huge problem and the EPA has pointed out that these toxins are 

carcinogenic and EPA has also stated that there are no regulations for these 

toxins. Therefore I urge the EPA when you are considering these regulations on 

CO2 sequestration that you broaden them to include CCWs. Stricter rules will not 

set us back economically, but rather it is going to ensure that the next 

generation has a prosperity to grow like our generation has. 

Response: It is beyond the scope of the GS rule and the UIC Program’s authority to require or set 

standards for upstream management of coal combustion wastes (CCWs), also known as coal combustion 

residuals (CCRs). The UIC program’s authority under the SDWA is limited to ensuring that GS projects 

are sited, constructed, operated, and closed in a manner that protects USDWs. EPA is separately

Commenter Name: Barbara Massoner Letter ID: 0531

Commenter Organization: Legacy Economy Comment ID: 21444

716
considering standards for the management of CCRs under RCRA. See 75 Fed. Reg. 35128 (proposed 

rule). 

Comment Code: 1270 1.1.2 Comments on other rules/issues 

Individual Comments 

Comment: A plethora of regulations affect the delivery of power using coal. We suggest 

that the Agency consider other regulations addressing the environment, human 

health and safety, and electricity cost and reliability, when drafting and 

implementing these regulations. The Alliance urges the Agency to consider the 

support of integrated energy, climate, and environmental policy as time 

progresses. 

Response: EPA agrees that a strong regulatory framework will be important to ensuring that GS is 

deployed safely. The Class VI GS regulation will provide certainty, consistency, and transparency to 

owners or operators and the public about requirements that apply to GS injection across the U.S. The 

Class VI GS regulation builds upon the long-standing, protective framework of the UIC program, which 

has been regulating the injection of billions of gallons of liquids for decades. The Class VI GS 

regulation enhances this existing framework with requirements for Class VI wells that are tailored to the 

unique nature of large scale GS of CO2. These additional protective requirements include more 

extensive geologic testing, detailed computational modeling of the AoR and periodic re-evaluations, 

detailed requirements for monitoring and tracking the CO2 plume and pressure front, and extended postinjection monitoring and site care. 

In response to the suggestion that the Agency develop an integrated permitting process, EPA clarifies 

that the UIC program’s authority under SDWA is focused on ensuring consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Comment: Climate change, drought, and the depletion of traditional ground water supplies 

due to population growth and land development are causing drinking water utility 

managers to look at new sources of drinking water that have not traditionally 

been considered as sources of drinking water. Coupled with improvements in 

desalination and other treatment technologies, drinking water sources of high 

salinity are being used for water supply. AMWA recommends that EPA reexamine 

the current classification of a USDW (i.e., an aquifer with a total dissolved 

solids (TDS) concentration of less than 10,000 mg/L) when siting Class VI 

geosequestration wells. The potential need to use saline aquifers for potable 

supply, particularly in water-stressed areas, should take precedence over the 

sequestration of carbon dioxide there. 

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23794

Commenter Name: Diane VanDe Hei Letter ID: 0213

Commenter Organization: Association of Metropolitan Water Agencies 

(AMWA)

Comment ID: 

22922

717
Response: EPA clarifies that addressing climate change, drought, and the depletion of traditional 

ground water supplies are outside the scope of the Class VI GS rulemaking. Rather, the purpose of the 

Class VI GS rule is to ensure consistency in permitting underground injection of CO2 at GS operations 

across the United States and provide requirements to prevent endangerment of USDWs in anticipation of

the eventual use of GS to reduce CO2 emissions. 

The Agency acknowledges commenter concerns about water resources and future water resource 

availability. However, modifying the definition of a USDW is outside the scope of the Class VI GS 

rulemaking. USDWs are defined as aquifers currently being used as sources of drinking water or those 

capable of supplying a public water system and have a total dissolved solids (TDS) content of 10,000 

milligrams per liter or less (§144.3). 

The primary goal of the UIC program under the SDWA is to protect USDWs in order to ensure a 

reliable supply of drinking water for the American public. The Class VI GS rule, as part of the UIC 

program regulations, continues the program’s tradition of ensuring the protection of USDWs. The 

permitting, siting, construction, operation, monitoring, and post-injection site care requirements in the 

GS rule build on a long-standing protective regulatory framework, tailored to the unique characteristics 

of CO2 injected for the purpose of GS. 

Comment: - Relationships with other Environmental Laws: The Agency should carefully 

consider any discussion of other environmental laws that it may desire to 

include in the Preamble to the rules in order to ensure that such discussion is 

necessary and does not hamper the successful commercialization ofCCS. 

Response: EPA clarifies that the Class VI GS regulation is being promulgated under authority of the 

Safe Drinking Water Act, and other environmental laws are outside the scope of the Class VI GS 

rulemaking. The purpose of the Class VI GS rule is to ensure consistency in permitting underground 

injection of CO2 at GS operations across the United States and provide requirements to prevent 

endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

In a separate rulemaking under authority of the Clean Air Act (CAA), EPA is amending the Greenhouse 

Gas Reporting Program at 40 CFR Part 98 to add reporting requirements for CO2 injection and GS. The 

greenhouse gas mandatory reporting requirements build on the Class VI requirements outlined in this 

final rule with the additional goals of verifying the amount of CO2 sequestered and collecting data on 

any CO2 emissions to the surface from GS facilities. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

Commenter Name: Michael Moore Letter ID: 0265

Commenter Organization: North American Carbon Capture & Storage 

Association (NACCSA)

Comment ID: 

22858

718
for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

Other EPA Comment Codes and Descriptions: 4300 2.4.4 Injection Depth 

Comment: And then secondly, I would like to agree with American Waterworks Association 

about the point that changing technical abilities for cleaning up water as well 

as increasing water demand does make it important that we not consider ten 

thousand parts per million to be set in stone. 

Response: EPA recognizes that there is increasing demand for water resources and that technology 

improvements may make high TDS aquifers viable drinking water sources. EPA believes these potential 

resources should be considered when injection depth waivers are sought. Therefore, the final GS rule at 

§146.95(b) requires the Director to consider these issues in determining whether an injection depth 

waiver is appropriate. Specifically, the Director must consider whether alternative injection sites are 

available; community needs, demands, and supply from drinking water resources; planned needs, 

potential and/or future use of USDWs and non-USDWs in the area; and a plan for securing alternative 

resources or treating USDW formation waters in the event of contamination related to the Class VI 

injection activity. 

EPA is not changing the USDW definition; changing the definition of a USDW is outside the scope of 

the GS rulemaking. The GS rule focuses on ensuring protection of USDWs, as required under the 

SDWA, by establishing regulations to ensure the safe injection of CO2 for long-term storage. 

Other EPA Comment Codes and Descriptions: 1670 1.3.7 Other/miscellaneous risks 

Comment: The rule I believe, I believe the preamble does mention the possibility of 

interference among projects, but whether or not that is the case, we think it is 

important that the rule contain a provision to head off potential interference 

among projects. The idea that seems to make sense to us is to flatly say that a 

project cannot interfere with the effectiveness of a preexisting project and 

anytime there is an overlap in the pressure fronts or footprint or however else 

you might define it, we think there ought to be inquiry made as to whether that 

would constitute interference. A rule like that would force projects in a single 

basin or brine formation to space themselves at least somewhat properly. 

Response: EPA anticipates that the impacts of multiple operators injecting into hydraulically connected 

formations will be accounted for in the initial AoR calculation. EPA adds that the owner or operator 

must demonstrate, in the proposed AoR and corrective action plan, to the satisfaction of the Director that 

the modeled AoR will be based on detailed geologic data collected on the site and includes consideration 

of existing conditions such as the presence of multiple operators. EPA adds that if any new GS projects 

are permitted within the AoR of a GS project between AoR evaluations, the AoR reevaluation must 

address such projects. EPA also expects that the permitting of the newer GS project will have considered 

the presence of an existing GS project. 

Commenter Name: Scott Anderson Letter ID: 0520

Commenter Organization: Environmental Defense Fund Comment ID: 21419

Commenter Name: Scott Anderson Letter ID: 0520

Commenter Organization: Environmental Defense Fund Comment ID: 21429

719
Comment: How about an EPA rule that goes like this. No use of any form of energy that 

does not yield more net energy across its process life cycle than it actually 

contains in its primary energy capture mode. Short of that, I must call today 

Response: The UIC program’s authority under the SDWA focuses on ensuring that Class VI GS 

projects are permitted, sited, constructed, operated, monitored, and closed in a manner that protects 

USDWs from endangerment. Prohibiting the use of certain forms of energy is outside the scope of the 

Class VI GS rulemaking. 

Comment: Does it make any sense at all to be expending more energy than coal actually 

yields and more money than could ever be justified with comprehensive life cycle 

accounting to widely used coal as a fuel source in the first place or by 

extension to perform carbon capture and sequestration? Does it net out to 

administer this stuff with hearings like this knowing what we already know? To 

accept as taxpayers the well known liabilities to fish and wildlife habitats and 

human health? To do the appropriate and necessary greenhouse gas reduction 

accounting? To deal with interstate boundary and commerce issues? To mine and 

process the coal with all the environmental degradation and health costs that we 

know are associated with that; to transport it to its destinations and then 

spend the fuel and human resources and fuel again to send the trains back empty? 

To burn it, gasify it, liquify it, whatever and then spend more money and more 

energy trying to put CO2 back into the ground from whence it came in the first 

place, for heaven's sake? And then, and then importantly trying to guess, guess 

how effective that process might be since we are lacking longitudinal data and I 

am wondering do reliable methods even exist to monitor that the sequestered CO2 

is staying put? We are getting new information that it is not staying put at 

least in a few cases, but even this non-scientist here knows that gasses have a 

tendency to seek the surface. I can see that when I drink my 7-up that I like 

every afternoon. The bubbles like to go up and as many others here can attest to 

better than I, CO2 leakage at the surface can cause serious public health and 

safety issues so. And then of course, not to mention that we have been undoing 

the energy intents given costly sequestration exercise that we just gone through 

and oh by the way, reintroducing CO2 again above ground as a greenhouse gas. So 

I am asking you, does this make any sense at all to even be in the business of 

doing these activities? 

Response: EPA clarifies that prohibiting the use of certain forms of energy, including coal and 

greenhouse gas accounting are outside the scope of the Class VI GS rulemaking. 

EPA recognizes that GS poses unique challenges, such as buoyancy; for this reason, the requirements 

for GS wells are tailored to the unique nature of large scale GS of CO2. These additional protective 

requirements include more extensive geologic testing, detailed computational modeling of the AoR and 

periodic re-evaluations, detailed requirements for monitoring and tracking the CO2 plume and pressure 

front, and extended post-injection monitoring and site care. 

Commenter Name: Becky English Letter ID: 0524

Commenter Organization: Sierra Club Comment ID: 21487

Commenter Name: Becky English Letter ID: 0524

Commenter Organization: Sierra Club Comment ID: 21488

720
Comment Code: 1280 1.1.2.1 General comments on climate change/ global warming 

Individual Comments 

Comment: The scientific basis for sequestering Carbon Dioxide (CO2) as a means of slowing 

or eliminating climate change (Global Warming) is not scientifically 

established. In fact, EPA in the proposed rule does not claim anthropogenic CO2 

is the cause of global temperature increase. EPA simply infers sequestration is 

necessary, without support. Refer to the Comment Section below entitled 

"Sequestration is not necessary" for details on the lack of supporting data for 

this EPA inferred position. 

Response: EPA clarifies that the purpose of the Class VI GS rule is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Mitigating climate change is outside the scope of the Class VI GS rulemaking. 

Comment: CS WELLS ARE NOT NECESSARY 

Carbon dioxide sequestration will not stop global temperature increase! EPA in 

the preamble to the CS proposed rule (73 FR 43496-43502) discusses the reasons 

for the need for CO2 sequestration. Nowhere in those pages does EPA state that 

carbon dioxide emissions cause global warming or what the optimum earth 

temperature is, or how the Agency knows when the optimum temperature is reached, 

so future sequestration can be discontinued. Is EPA suggesting sequestration 

continue until it causes the next ice age? A review of the U. S. Department of 

Energy (2007) report demonstrates a similar lack of CO2 cause and effect. 

We can find no peer reviewed technical paper, referenced by EPA or anyone else 

(not based on computer simulation) showing CO2 causes global warming. EPA 

relies heavily on computer simulations by the Intergovernmental Panel on Climate 

Changes (IPCC) reports. Reference to IPCC reports subjects EPA to serious 

question regarding the technical validity of the information presented. The use 

of the Hockey Stick Figure (Figure 22, IPCC, 1996) brings into sharp focus the 

political nature of the IPCC reports. McIntyre and McKitrick (2003) demonstrated 

conclusively the Hockey Stick Figure was based on truncated data, obsolete data, 

calculation errors and quality control deficiencies. Also, Figures 5.20 and 

5.21 (IPCC, 2005) , sequestration well details, demonstrate IPCC is technically 

deficient because, IPCC blithely suggests pulling cemented casing from Class VI 

at the completion of injection, IPCC Figure 5.21. Experience demonstrates 

cemented casing cannot be pulled. IPCC (2005 at page 231) suggests milling the 

casing from the shoe upwards to remove corrodible metal from contact with the 

carbonic acid. Milling is possible. Modern mills can "hog out" 10 feet of 

Commenter Name: George Holliday, PhD, PE, BCEE Letter ID: 0114

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 22520

Commenter Name: George Holliday, PhD, PE, BCEE Letter ID: 0114

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 22527

721
casing per hour, but the metal chips settle-out in the well Blowout Preventer, 

preventing proper operation in the event of an emergence. The ludicrous 

suggestion of using a milling stone as a means of connecting to a fixed packer 

defies all understanding, IPCC Figure 5.20. Astute scientists and engineers are 

very wary of IPCC reports, because of the frequent and consistent errors 

contained in the reports. 

EPA, in the proposed sequestration rule, does not provide any indication of the 

benefit sequestration will provide other than reduce CO2 concentration in the 

atmosphere. Even that goal appears questionable. Our extensive review of the 

technical literature demonstrate no peer reviewed reports based on field 

observations are available showing a direct relationship of global warming 

caused by increase in the atmospheric CO2. However, Lucas, 2008, states the "We 

Can Solve It" (www.wecansolveit.org) campaign compares "your commitment to 

solving the climate crisis as [being equivalent to solving] the World War II, 

Normandy landing, the civil rights movement and putting a man on the moon" 

combined. Unfortunately, www.wecansolveit.org offers no supporting data, but it 

offers new high financial income opportunities, which appears to be the major 

driving force behind temperature change projects. 

Is the relationship between CO2 and global temperature increase is real? The 

quantity of anthropogenic CO2 emissions are infinitesimally small compared with 

naturally occurring CO2 releases as shown by DOE, Figure 1, below,. The U.S. 

Department of Energy ( 

www.fossil.energy.gov/programs/sequestration/overview.html) developed the graph, 

showing projected CO2 entering the atmosphere during 2008 from Anthropogenic 

sources is 6.0 GtC/yr: Forests and Soils release >100 GtC/yr: Geologic >300 

GtC/yr and Oceans 1,400 GtC/yr. It appears sequestering all of the 

anthropogenic CO2 in minuscule when compared with natural sources. Will 

sequestering such a small quantity effective reduce global warming? 

[Figure 1. 2008 Estimated United States CO2 Emissions for 2008. See pdf] 

IPCC, 1996. Second Assessment Report, Summary for Policymakers. 

Lucas, F., 2008. Cashing in on Climate Change. Human Events, 64:28;15, August 

14, 2008 

McIntyre, S. and R.M. McKitrick, 2003. "Correction of Mann et al. Proxy Data 

Base and Northern Hemisphere Average Surface Air Temperature Series" Energy and 

Environment, 14:751-771 

U.S. Department of Energy, 2007. Carbon Sequestration Technology Roadmap and 

Program Plan 2007. 

http://www.netl.doe.gov/technologies/carbon_seq/refshelf/project%20portfolio/20 

07/2007Roadmap.pdf 

Response: EPA clarifies that the purpose of the Class VI GS rule is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. As 

described above, mitigating climate change is outside the scope of the Class VI GS rulemaking. 

722
Comment: SEQUESTRATION IS NOT NECESSARY 

Based on a review of existing technical papers, CO2 emissions are not causing 

climate temperature change. There have been climate changes for at about 2 

million years. Life has struggled forward under climate temperature increases 

and decreases without being annihilated. 

During these temperature changes, Greenland has gone from a marginal framing 

area to a bleak cold frozen area, but people continue taking advantage of the 

warmer climate by moving away from the cold areas. The belief that these global 

temperature changes can be mitigated by sequestering carbon dioxide has no 

scientific support, since previous Global temperature increases occurred in the 

absence of anthropogenic CO2. 

Climate models, which are being used to suggest CO2 is causing global warming 

are inaccurate at best, because climate predictions are very complicated and 

beyond our current technical capabilities. Relying on computer modeling as the 

basis for needing the instant rule proposal is a cruel hoax. 

Response: As described above, mitigating and modeling climate change is outside the scope of the 

Class VI GS rulemaking. EPA clarifies that the purpose of the Class VI GS rule is to ensure consistency 

in permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. 

Comment: A: CO2 SEQUESTRATION IS NOT NECESSARY TO STOP GLOBAL WARMING 

1. DOE compared the 2008 estimated CO2 emissions from anthropogenic sources with 

naturally occurring emissions, Fig 1. Based on the graph data, it is difficult 

to believe sequestering the anthropogenic releases will change anything. 2. The 

only accurate means of measuring the changing Global Temperature is via 

satellite. Since 2001 the satellite measurements show a decrease of 0.1°C per 

year, while the CO2 continues to increase.. 

3. The IPPC computer simulation of climate change predicts an "Atmospheric 

Hotspot" layer about 10 Km above the earth’s surface as CO2 increases. Try as we 

have, the weather balloons have never recorded such a raise in temperature. This 

casts doubt on the validity of the IPPC Model and the need for CO2 

sequestration. 

Response: EPA notes that mitigating and modeling climate change is outside the scope of the Class VI 

GS rulemaking. EPA clarifies that the purpose of the Class VI GS rule is to ensure consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

Commenter Name: George Holliday, PhD, PE, BCEE Letter ID: 0114

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 24116

Commenter Name: George Holliday, PhD, PE, BCEE Letter ID: 0127

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 23052

723
CO2 emissions. 

Comment: Action is needed to reduce greenhouse gas emissions 

In 2007, the UN Intergovernmental Panel on Climate Change said warming of the 

climate system is unequivocal and directly linked to human activity, primarily 

the burning of fossil fuels. Global warming threatens America and the world with 

more frequent and more severe storms, new outbreaks of diseases and crop pests, 

and massive coastal flooding. Scientists have documented that Arctic sea ice is 

melting rapidly and the Western United States already may be in permanent 

drought. The climate crisis requires urgent action. To avoid the worst effects, 

global greenhouse gas emissions must peak by 2015 and then start falling by at 

least 50% by 2050, compared to 1990 levels. Developed countries must reduce 

their greenhouse gas emissions by at least 25 percent below 1990 levels by 2020, 

and at least 80 percent below 1990 levels by 2050.[FN1 1 IPCC, 2007: Climate 

Change 2007: Fourth Assessment Report of the Intergovernmental Panel on Climate 

Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. 

Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United 

Kingdom and New York, NY, USA, 996 pp.] 

Coal is the largest emitter of global warming pollution in our country. In fact, 

emissions from coal-fired power plants are responsible for 40 percent of the 

global warming pollution in today’s atmosphere.[FN2 2 U.S. Environmental 

Protection Agency, "Inventory of U.S. Greenhouse Gas Emissions and Sinks: 

1990-2005," April 2007. Based on calculation of CO2 emissions from tables 3-1 

and 3-3.] Yet world governments are planning to build hundreds of coal power 

plants in the next decade. If such plans go ahead it will be impossible for 

governments to reduce greenhouse gas emissions enough to seriously tackle 

climate change. 

Response: EPA clarifies that mitigating climate change and regulating the use of coal are outside the 

scope of the Class VI GS rulemaking. The purpose of the Class VI GS rule is to ensure consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions The requirements apply to owners or operators of wells that will be used to inject CO2 

into the subsurface for the purpose of long-term storage. 

Comment: Greenpeace would urge the United States not to divert resources from proven 

solutions to climate change such as wind and solar power and energy efficiency 

to invest in risky technology such as CCS. However, should such plans be 

Response: EPA clarifies that other climate change mitigation technologies such as wind and solar power 

and energy efficiency, are not within the UIC program’s authority and outside the scope of this 

rulemaking. EPA emphasizes that the UIC program’s authority under the SDWA is focused on ensuring 

that Class VI CO2 injection projects are permitted, sited, constructed, operated, monitored, and closed in 

Commenter Name: Emily Rochon Letter ID: 0129

Commenter Organization: Greenpeace International Comment ID: 23060

Commenter Name: Emily Rochon Letter ID: 0129

Commenter Organization: Greenpeace International Comment ID: 23074

724
a manner that protects USDWs from endangerment. 

Comment: CCS and a 'Clean Energy Future': Encourage public acceptance of CCS by 

emphasizing it as one part of a strategic national plan for effecting a 'Clean 

Energy Future'. 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. However, the use of and investment in these 

technologies is outside the scope of the Class VI GS rulemaking. The Class VI GS requirements are 

designed to ensure that, where GS is deployed, projects are permitted, sited, constructed, operated, and 

closed in a manner that protects USDWs from endangerment. 

Comment: I. CCS and a 'Clean Energy Future' 

Recommendation I: Encourage public acceptance of CCS by emphasizing it as one 

part of a strategic plan for effecting a Clean Energy Future'. 

A prominent theme in public opposition to CCS is the concern that geologic 

storage will prolong our dependence on fossil fuels and divert the necessary 

funds for developing sustainable energy resources in the US. In addition to 

providing protocols for public outreach, education, and dialogue about 

geosequestration siting, the EPA has an opportunity during these early stages of 

implementation of national CCS policies to frame social perceptions of geologic 

storage as part of a larger set of strategies for achieving a 'Clean Energy 

Future.' The Sierra Club strongly recommends that the EPA partner with the DOE 

and other federal agencies to garner public support for CCS by characterizing it 

as one of several policy measures designed to reduce the overabundance of CO2 in 

our atmosphere. While CO2 capture is outside the scope of these proposed 

regulations for CO2 injection and storage, it is important to recognize that 

many opponents of CCS in general are fearful that the development of CO2 capture 

technology will prolong our reliance on coal for electrical generation, thus 

delaying deployment of renewable energy resources such as wind, solar, and 

geothermal. By promoting the adoption of "companion carbon control strategies" 

such as energy efficiency, energy conservation, and renewable energy electrical 

generation, the EPA can help position CCS as one constituent of a broader 

integrated objective. 

Response: EPA clarifies that the Class VI GS regulation does not promote or encourage the use of GS; 

Commenter Name: Anonymous2 Letter ID: 

0133

Commenter Organization: Sierra Club National Global Warming and Energy 

Committee and Sierra Club California-Nevada Regional Conservation Committee on 

Energy and Climate Change

Comment ID: 

21598

Commenter Name: Anonymous2 Letter ID: 

0133

Commenter Organization: Sierra Club National Global Warming and Energy 

Committee and Sierra Club California-Nevada Regional Conservation Committee on 

Energy and Climate Change

Comment ID: 

21619

725
rather the purpose of the rule is to ensure consistency in permitting underground injection of CO2 at GS 

operations across the United States and provide requirements to prevent endangerment of USDWs in 

anticipation of the eventual use of GS to reduce CO2 emissions. EPA agrees that GS is one technology 

in a portfolio of options, including energy conservation, efficiency improvements, and the use of 

alternative fuels and renewable energy sources, that could be deployed to reduce CO2 emissions. 

However, the use of and investment in these technologies is outside the scope of the Class VI GS 

rulemaking. The Class VI GS requirements are designed to ensure that, where GS is deployed, projects 

are permitted, sited, constructed, operated, and closed in a manner that protects USDWs from 

endangerment. 

Other EPA Comment Codes and Descriptions: 1480 1.2.2.2.2 CO2 is not a pollutant 

Comment: J. CO2 as a Valuable Commodity 

Recommendation J: Re-frame public perceptions of CO2 as a hazardous waste 

material by funding CCS demonstration projects which biologically or chemically 

transform CO2 into valuable products. 

Localities that oppose the permitting of geologic sequestration projects usually 

hold the perception that CO2 is a toxic waste material being dumped and buried 

in their backyards. Typically, localities are distrustful of the motivations of 

business and government representatives who seek to allay fears of economic, 

health, and environmental risks attendant to pumping CO2 into injection wells. 

An important avenue for re-framing such perceptions is by emphasizing CCS 

methods which value carbon dioxide as a naturally occurring and commercially 

valuable resource. The DOE's carbon sequestration program at the National Energy 

Technology Laboratory includes funding for research and development of advanced 

chemical and biological approaches, including systems for decarbonization, 

photosynthesis, and conversion of CO2 into useful forms. However, since no 

demonstration projects have been announced over the same time period that 

multiple geosequestration projects have been implemented, the DOE's "Novel 

Carbon Sequestration Concepts" program appears to be under- publicized and 

under-funded. This lack of vigor in promoting carbon transformation methods 

gives the public the impression that CCS technologies are being readied solely 

for the purpose of perpetuating our dependency on fossil fuels for electricity 

generation and manufacturing processes. 

Numerous business ventures are seeking opportunities to prove the efficacy of 

their carbon mineralization processes with larger demonstration projects. 

Companies holding proprietary patents for useful CO2-sequestered materials such 

as calcium carbonate cement and construction materials, paper products, 

biodegradable plastics, and algae biofuels need government funding and support 

to scale-up their methods. By narrowly targeting geosequestration as the primary 

carbon storage solution, the federal government is missing an opportunity to 

secure broader public acceptance of CCS as a safe and viable method for reducing 

the overabundance of CO2 in our atmosphere, and is neglecting important avenues 

Commenter Name: Anonymous2 Letter ID: 

0133

Commenter Organization: Sierra Club National Global Warming and Energy 

Committee and Sierra Club California-Nevada Regional Conservation Committee on 

Energy and Climate Change

Comment ID: 

21620

726
for achieving that goal. 

Response: EPA acknowledges that GS falls within the broader context of CCS and the need for 

regulatory clarity to ensure that USDWs are protected from endangerment. In developing the final GS 

rule, the Office of Water coordinated with other Agency program offices and across federal agencies 

(e.g., with the Department of Energy; United States Geological Survey; Bureau of Ocean Energy 

Management, Regulation, and Enforcement, formerly the Minerals Management Service; and the 

Bureau of Land Management). The Agency continues to evaluate areas of potential applicability of other 

Federal environmental statutes including, but not limited to: the Clean Air Act; the Resource 

Conservation and Recovery Act; the Comprehensive Environmental Response, Compensation, and 

Liability Act; and the Marine Protection, Research and Sanctuaries Act to various aspects of GS and 

CCS. The Agency will continue to coordinate on GS and CCS related issues to minimize redundancy 

and maximize efficiencies for owners or operators. For additional information, please see the discussion 

entitled "How Does This Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" 

in the preamble to the final GS rule. 

EPA adds that the intent of the GS rule is not to promote GS. Rather, the purpose of the GS regulation is 

to assure that, where deployed, GS is conducted in a manner that protects USDWs from endangerment.

The Agency acknowledges that there is ongoing research in many fields that could address the broader 

environmental concern of climate change, but the focus of the Class VI requirements is to ensure that, 

where GS is deployed, it is conducted in a manner that protects USDWs from endangerment. 

Much of the research on terrestrial and geologic sequestration is being conducted by other federal 

agencies, particularly DOE's Office of Science and Technology 

(www.energy.gov/sciencetech/carbonsequestration.htm). Other federal agencies involved in research 

include the US Department of Agriculture, US Geological Survey, and others. EPA's Office of Research 

and Development is also researching issues related to global climate change, including geologic and 

terrestrial sequestration. 

Comment: The rationale for regulating greenhouse gases, including CO2, is simple. 

We don't know much for certain about this subject, but we do have a very good 

sense of the relative odds, and they are these : 

If we do nothing about Global Warming and we are wrong, the consequences will be 

horrendous and in many cases irreversible. 

In money terms, they will be much greater than the money we would waste, if we 

were to do something and it turns out to have been unnecessary. 

And by the way, why should we worry about a low probability of wasting money on 

the mitigation of Global Warming, when we happily wasted so much more on our 

"Iraq adventure" ? Why this sudden concern for "fiscal responsibility" when so 

much blood and treasure has been thrown away for reasons which turned out to be 

entirely phony ? 

[ We can be certain about that ! ] 

Commenter Name: Lewis L. Smith Letter ID: 0136

Comment ID: 21670

727
Response: The Class VI GS requirements are designed to ensure consistency in permitting underground 

injection of CO2 at GS operations across the United States and provide requirements to prevent 

endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. For 

additional information on EPA's final regulatory approach, please see the final rule and preamble as well 

as the rulemaking docket. 

Comment: U.S. population. Our associations are very concerned with the effects of climate 

change on water resources and while we recognize the need for strategies to be 

developed that address mitigation of greenhouse gases (GHG), we also believe 

strongly that any strategy deployed for this purpose should above all else 

protect our water resources. 

Many of the most critical impacts of global climate change will manifest 

themselves through the hydrologic system, and there is already strong evidence 

that climate change is having an impact on the world’s water resources. In 2000, 

approximately 79% of 54,000 community water systems in the United States were 

supplied by groundwater (almost 86 million people). In addition, many surface 

water utilities are currently looking at conjunctive use and/or groundwater 

development as adaptation measures (supply portfolio diversification/new 

storage) to combat climate change. There is the potential for each of these 

utilities to be impacted by geologic carbon sequestration, simply by the fact 

that these utilities utilize groundwater resources. 

Response: The Agency agrees that protecting drinking water is important. The primary goal of the UIC 

program under the SDWA is to protect USDWs. The UIC program provides that no injection shall be 

authorized if it results in the movement of fluid containing any contaminant into USDWs, if the 

presence of that contaminant may cause a violation of any primary drinking water regulation under 40 

CFR §141 or may adversely affect the health of persons (§144.12). 

The GS rule, as part of the UIC program regulations, continues the Program’s goal of ensuring the 

protection of USDWs from endangerment. The purpose of the Class VI GS rule is to ensure consistency 

in permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. The permitting, siting, construction, operation, monitoring, and post-injection site care 

requirements in the Class VI GS rule are built on a long-standing protective regulatory framework, 

tailored to the unique aspects of CO2 GS. 

Comment: AMWA appreciates the opportunity to comment on the proposed rule for permitting 

the geological sequestration of carbon dioxide (CO2). Many of the most critical 

impacts of global climate change will manifest themselves through the hydrologic 

system, and there is already strong evidence that climate change is having an 

impact on the world’s water resources. AMWA recognizes the importance of 

Commenter Name: Diane VanDe Hei Letter ID: 0206

Commenter Organization: Association of Metropolitan Water Agencies 

(AMWA)

Comment ID: 

22205

Commenter Name: Diane VanDe Hei Letter ID: 0213

Commenter Organization: Association of Metropolitan Water Agencies 

(AMWA)

Comment ID: 

22915

728
reducing carbon dioxide emissions to mitigate climate change impacts. Our member 

utilities across the country are engaged in efforts to reduce their carbon 

footprint and greenhouse gas emissions in a myriad of ways -- from increased 

efficiency to green power projects. However, protecting our nation’s water 

Response: The use of and investment in climate change mitigation technologies is outside the scope of 

the Class VI GS rulemaking. The Class VI GS requirements are designed to ensure that, where GS is 

deployed, projects are permitted, sited, constructed, operated, and closed in a manner that protects 

USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 6000 3. Cost of the Proposed Rule 

Comment: We are also concerned that certain unnecessary and costly requirements in the 

Proposed Rule would discourage, or even foreclose, the conversion of existing 

Class II EOR wells to Class VI geologic sequestration wells. This would undercut 

the effectiveness of the Proposed Rule’s provisions for such conversion. 

Unnecessary or unduly costly requirements would preclude CCS from playing the 

role that many policy analysts and governments worldwide believe that it must 

play in any successful strategy for reducing atmospheric concentrations of CO2. 

This is important because it means that the EPA may - and indeed, must - balance 

objectives that pull at times in competing directions. In other words, if the 

EPA’s primary objective is to reduce CO2 emissions and if CCS is an essential 

component of a CO2 reduction strategy, then the rules governing CO2 injection 

and storage must be crafted in such a way as to advance the primary objective of 

reducing GHG emissions. 

New rules for CO2 sequestration that are too risky or too costly for widespread 

use will work against this primary overall objective of reducing GHG emissions. 

Absent a broader legal foundation than the SDWA alone, however, the EPA could 

conceivably find itself required to impose conditions for sequestration that 

would foreclose (or unduly limit) the use of CCS as an emissions reduction tool. 

This, we fear, could defeat the very purpose of the rule in the first place. 

Accordingly, we suggest that EPA examine whether it may be appropriate to invoke 

other existing statutory authorities as part of the legal foundation for the new 

sequestration rules. 

Response: EPA disagrees that certain requirements for the conversion of existing Class II EOR wells to 

Class VI wells are unnecessary. The final GS regulation requires at §146.81(c) that owners or operators 

seeking to grandfather existing Class II wells for GS demonstrate that grandfathered wells were 

engineered and constructed to meet the requirements at §146.86(a) and ensure protection of USDWs, in 

lieu of requirements at §§146.86(b) and 146.87(a). These requirements do not impose additional 

stringency on conversion from Class II wells as compared to new construction. For additional 

information on EPA's final regulatory approach, including transitioning of EOR wells for GS, please see 

the final rule and preamble. 

In regard to cost, the Agency clarifies that sequestration costs are expected to be a small component of 

total CCS project costs. EPA estimates that the GS rule requirements amount to approximately two 

percent of the total CCS project costs, according to the cost analysis for the final GS rule, which is in the 

rulemaking docket. EPA adds that promoting or incentivizing GS is outside the scope of the GS 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24275

729
rulemaking. Rather, the purpose of the GS regulation is to ensure that GS is conducted in a manner that 

protects USDWs from endangerment. 

EPA is developing guidance on transitioning of EOR projects. This guidance will be available on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: We agree with EPA that CCS could play an important role in allowing deep 

greenhouse gas emission reductions from electric generation and industrial 

facilities. In order to achieve the cuts necessary to avoid the worst 

consequences of climate change, CCS must be integrated within a larger climate 

policy that includes legislation limiting greenhouse gas emissions, investment 

in efficiency improvements and renewable energy sources such as solar, wind, 

biomass and geothermal. [FN1] 

[FN1: 1 IPCC Special Report on Carbon Dioxide Capture and Storage, 2005 

(hereinafter "IPCC CCS") Section 1.1, 1.3.] 

CCS must be deployed on a very large-scale to enable deep cuts in worldwide 

greenhouse gases. To deploy this nascent technology in a short timeframe, it 

must be managed very proficiently from the start to minimize ecological, human 

health, and financial risks. Any CCS regulatory regime must establish clear 

incentives for responsible site selection, appropriate monitoring, safe and 

environmentally sound operation, and financially responsible closure. 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. However, the use of and investment in these 

technologies is outside the scope of the Class VI GS rulemaking. The Class VI GS requirements are 

designed to ensure that, where GS is deployed, projects are permitted, sited, constructed, operated, and 

closed in a manner that protects USDWs from endangerment. 

The GS regulation builds upon the long-standing protective framework of the UIC program, which has 

been regulating the injection of billions of gallons of liquids for decades. The Class VI GS regulation 

enhances this existing framework with requirements for Class VI wells that are tailored to the unique 

nature of large scale GS of CO2. These additional protective requirements include more extensive 

geologic testing, detailed computational modeling of the AoR and periodic re-evaluations, detailed 

requirements for monitoring and tracking the CO2 plume and pressure front, and extended post-injection 

monitoring and site care. 

Comment: The planet’s climate is changing fast. Greenhouse gas emissions from the use of 

fossil fuels, mainly carbon dioxide (CO2), are having a profound effect on our 

climate, presenting us with one of the most significant environmental and social 

challenges of the century. In its most recent Assessment Report last year, the 

Intergovernmental Panel on Climate Change, an independent scientific body, 

issued the loudest warning to date, calling the warming in the climate system 

Commenter Name: Kristin Henry Letter ID: 0242

Commenter Organization: Sierra Environmental Law Program, Sierra Club Comment ID: 23307

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22269

730
"unequivocal" and calling for serious emission reductions if we are to avoid 

truly dangerous greenhouse gas concentrations. Failure to pursue significant 

reductions in greenhouse gas emissions very soon will make it much harder in the 

future both to stabilize atmospheric pollution concentrations and to avoid the 

worst impacts of climate change. Climate change is expected to and, indeed, 

already is having a profound effect on sources of drinking water. The American 

West, for example, is already becoming noticeable hotter and drier, as a recent 

compilation of studies by the Rocky Mountain Climate Organization (RMCO) and 

NRDC summarizes.[FN1] 

[FN1: 1 "Hotter and Drier: The West’s Changes Climate". Rocky Mountain Climate 

Organization (RMCO) and the Natural Resources Defense Council. Available at: 

http://www.nrdc.org/globalWarming/west/west.pdf] 

A growing body of scientific research indicates that we face extreme dangers to 

human health, economic well-being, and the ecosystems on which we depend if 

global average temperatures are allowed to increase by more than 2 degrees 

Fahrenheit from today’s levels. We have good prospects of staying below this 

temperature increase if atmospheric concentrations of CO2 and other global 

warming gases are kept from exceeding 350 to 450 parts per million (ppm) 

CO2equivalent. Achieving this goal will require rapid reductions in existing 

emissions, including action to cut emissions by approximately 80% by midcentury. This goal is ambitious, but achievable. It can be done through an 

annual rate of emissions reductions that ramps up to about a 4% reduction per 

year. Fortunately, a wide variety of tools is available today to achieve those 

reductions. 

Response: GS is one technology in a portfolio of options, including energy conservation, efficiency 

improvements, and the use of alternative fuels and renewable energy sources, that could be deployed to 

reduce CO2 emissions. However, the use and promotion of these technologies is outside the scope of the 

Class VI GS rulemaking. The Class VI GS requirements are designed to ensure that, where GS is 

deployed, projects are permitted, sited, constructed, operated, and closed in a manner that protects 

USDWs from endangerment. 

Comment: In comments on the Agency’s recent advanced notice of proposed rulemaking on 

using the Clean Air Act to combat climate change, a coalition of environmental 

NGOs, including some members of our Environmental NGO Group, pointed out that 

for the U.S. to achieve its necessary climate goals, controlling CO2 emissions 

from new and existing sources of CO2 is required. That necessitates reductions 

from all sectors, including radical shifts to zero-emitting technologies and 

corrective action on existing sources. These reductions will require targeted 

measures and policies, which include air regulations that would set CO2 

emissions standards implicating the capture and sequestration of CO2. Setting an 

NSPS or a BACT standard based on CO2 capture technology necessarily creates a 

need for complementary requirements to assure that the captured CO2 is 

effectively isolated from the atmosphere. At this time, such an outcome requires 

injecting CO2 underground for permanent sequestration in either hydrocarbon 

reservoirs or deep saline formations. Such permanent sequestration clearly meets 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22274

731
the definition of underground injection, regulated by the UIC program of the 

Safe Drinking Water Act ("SDWA").[FN6] 

[FN6: 6 42 U.S.C. §300h, et seq. Geologic sequestration of CO2 clearly meets the 

definition of underground injection found at 42 U.S.C. §300h(d)(1), "the 

subsurface emplacement of fluids by well injection." Carbon dioxide, whether 

injected in a supercritical state, or as a gas, meets the definition of a fluid 

included in the existing regulations under the SDWA: those rules state that a 

"fluid" is "any material or substance which flows or moves whether in a 

semisolid, liquid, sludge, gas or other form or state." 40 CFR § 144.3.] 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. However, the use of and investment in these 

technologies is outside the scope of the Class VI GS rulemaking. The Class VI GS requirements are 

designed to ensure that, where GS is deployed, projects are permitted, sited, constructed, operated, and 

closed in a manner that protects USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 1320 1.1.3 General comments about GS 

Comment: Assessment of the Proposed Rule The proposed rule repeatedly references climate 

change mitigation by the injection of CO2 as the justification for the need for 

the new class of injection well: 

Summary: "EPA is proposing Federal requirements under the Safe Drinking Water 

Act (SDWA) for underground injection of carbon dioxide (CO2) for the purpose of 

geologic sequestration (GS). GS is one of a portfolio of options that could be 

deployed to reduce CO2 emissions to the atmosphere and help to mitigate climate 

change." 

And "If finalized, this proposal would help ensure consistency in permitting 

underground injection of CO2 at GS operations across the U.S. and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual 

use of GS to reduce CO2 emissions." 

In Part II "What is the EPA Proposing" the proposition reiterates: 

"In addition to protecting USDWs, today’s proposed rule provides a regulatory 

framework to promote consistent approaches to permitting GS projects across the 

U.S. and supports the development of a key climate change mitigation 

technology." 

Under Part II A. "Why Is EPA Proposing To Develop New Regulations To Address GS 

of CO2?" Part II. Section 2, states: The Intergovernmental Panel on Climate 

Change (IPCC) has concluded that much of the warming in recent decades is very 

likely the result of human activities (IPCC, 2007). The burning of fossil fuels 

(e.g., from coalfired electric plants and other sources in the electricity and 

industrial sectors) is a major contributor to humaninduced greenhouse gas 

emissions. 

Commenter Name: Mary Munn Letter ID: 0273

Commenter Organization: Fond du Lac Reservation Comment ID: 24082

732
Fossil fuels are expected to remain the mainstay of energy production well into 

the 21st century, and increased concentrations of CO2 are expected unless energy 

producers reduce the CO2 emissions to the atmosphere. The capture and storage of 

CO2 would enable the continued use of coal in a manner that greatly reduces the 

associated CO2 emissions while other safe and affordable alternative energy 

sources are developed in the coming decades. Given the United States’ abundant 

coal resources and reliance on coal for power generation, CCS could be a key 

mitigation technology for achieving domestic emissions reductions" 

And: 

"Congressional climate change legislative proposals (the McCain-Lieberman bill 

S. 280, the Bingaman-Specter bill S. 1766, and the Lieberman-Warner bill S. 

2191) indicate that CCS has the potential to play a significant role in climate 

change mitigation scenarios." 

And: 

"Today’s proposal provides a regulatory framework to protect USDWs as this key 

climate mitigation technology is developed and deployed." 

The allusion of mitigating climate change or reducing CO2 emissions by geologic 

sequestration cannot be fairly used as persuasive point for this rule without 

providing data demonstrating the mass balance of energy and carbon dioxide in 

the whole system. A great deal of analysis has been completed and posted on the 

docket of cost and incremental cost within the proposed rule for CCS and GS 

implementation but no analysis is made in terms of the actual amount carbon 

dioxide that will be sequestered in relation to the amount of carbon dioxide 

emitted throughout the process (Cost: EPA-HQ-OW-2008-0390-0073 and EPA-HQOW-2008-0390-0094). 

A mass balance of the participating fossil energy processes, generating the CO2, 

must be evaluated to determine if any real reduction in CO2 can be made. CO2 is 

emitted during the excavation and transport of the fossil fuel to a power plant. 

Additional power will be required, and will emit additional CO2, to provide the 

energy to extract the CO2 from the emission stream, to compress, transport, and 

to inject the CO2 into a geologic formation. 

Response: EPA clarifies that the Class VI GS requirements are designed to ensure consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. The requirements apply to owners or operators of injection wells used to inject CO2 for 

permanent storage. 

GS is one technology in a portfolio of options, including energy conservation, efficiency improvements, 

and the use of alternative fuels and renewable energy sources, that could be deployed to reduce CO2 

emissions. However, the use of and investment in these technologies is outside the scope of the Class VI 

GS rulemaking. The Class VI GS requirements are designed to ensure that, where GS is deployed, 

projects are permitted, sited, constructed, operated, and closed in a manner that protects USDWs from 

endangerment. 

733
Comment: Social Justice: The United Nations Environmental Progamme states: "Globally 

around $300 billion or 0.7 per cent of global GDP is being spent on energy 

subsidies annually. The lion's share is being used to artificially lower or 

reduce the real price of fuels like oil, coal and gas or electricity generated 

from such fossil fuels. Cancelling these subsidies might reduce greenhouse gas 

emissions by as much as six per cent a year while contributing 0.1 per cent to 

global GDP." 

Mr. Steiner added: "Whereas fossil fuel subsidies are an example of a blunt 

policy instrument, perpetuating old and inefficient economic models, the CDM is 

an example of a more intelligent, market-based mechanism that is fostering the 

transition to a modern Green Economy". (Accessed online Nov. 14, 2008 

http://www.unep.org/Documents.Multilingual/Default.asp?DocumentID=543&ArticleID= 

5902 ) 

Response: EPA clarifies that the Class VI GS requirements are designed to ensure consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. The requirements apply to owners or operators of injection wells used to inject CO2 for 

permanent storage. Fuel subsidies are outside the scope of the Class VI GS rulemaking. 

Comment: Although the effort made to address the serious issues of climate mitigation 

through CCS is greatly appreciated, the effort largely appears to mitigate CO2 

emissions via a complex system that will, in reality, increase fossil energy 

consumption. With projected consumption to increase more than 30% by 2030 and 

CCS adding at least 20% additional demand, one may wonder if this proposal 

equates to yet another subsidy for fossil fuel industry. 

The absence of analysis of the carbon neutrality of this project is a serious 

omission. An analysis of this kind should have been the first step in evaluating 

this proposal, yet it is not addressed in the rule or in any of the supporting 

documentation. An endeavor of this magnitude should be demonstrably carbon 

neutral and hopefully operate as a true carbon sink. 

Response: As described above, EPA clarifies that the purpose of the Class VI GS requirements are 

designed to ensure consistency in permitting underground injection of CO2 at GS operations across the 

United States and provide requirements to prevent endangerment of USDWs in anticipation of the 

eventual use of GS to reduce CO2 emissions. The requirements apply to owners or operators of injection 

wells used to inject CO2 for permanent storage. The topics of climate change mitigation, fossil energy 

consumption, carbon neutrality, CO2 emissions, and GHG regulations are outside the scope of the Class 

VI GS rulemaking. 

Commenter Name: Mary Munn Letter ID: 0273

Commenter Organization: Fond du Lac Reservation Comment ID: 24085

Commenter Name: Mary Munn Letter ID: 0273

Commenter Organization: Fond du Lac Reservation Comment ID: 24090

Commenter Name: Mary Munn Letter ID: 0273

734
Comment: This rule is written for the existing energy production system. The reliance on 

fossil energy must change to meet the challenge of climate change. Barriers to 

the success of alternate sources of energy must be removed so the issue can be 

faced head on. This rule will impede and obstruct progress for those competing 

industries. 

The resources required to pursue this undertaking will be in direct competition 

with efforts focused on sustainable energy sources and alternative, arguably 

more effective carbon sequestration, utilizing wetland restoration, improved 

agricultural methods, and sustainable forestry practices that have numerous and 

vital fringe benefits. 

Experts in carbon sequestration know that utilizing biologic methods of carbon 

capture is cost effective and will include economic benefits. For example, 

wetland protection and restoration will not only sequester carbon but will 

purify water, impede drainage (flooding), and replenish aquifers. Many avenues 

could be used to reverse engineer the activities that drained these wetlands. 

Many studies including the Kyoto Protocol Wetland Restoration and Management and 

the Wilderness Society Forest Carbon Report support these alternative carbon 

sequestration mechanisms. 

Reduction of carbon emissions to the atmosphere is the primary driver for this 

new class of well, proof that carbon capture and sequestration will provide a 

net removal of CO2 must be provided else any reference to the reduction of CO2 

emissions or climate mitigation must be removed from the document. 

Response: EPA agrees that GS is a key climate change mitigation technology that is part of a portfolio 

of options that could be deployed to reduce CO2 emissions. Other options include efficiency 

improvements and the use of alternative fuels and renewable energy sources. However, promoting or 

incentivizing these technologies is outside the UIC program’s authority under the SDWA, which focuses 

on ensuring that, where deployed, GS projects are permitted, sited, constructed, operated, monitored, 

and closed in a manner that protects USDWs from endangerment. 

Other federal agencies (e.g., DOE and the U.S. Geological Survey) have conducted research on 

available storage capacity and made determinations of the feasibility of capturing and storing CO2 at the 

scales needed to address climate change. These agencies, along with private entities, have identified 

large areas for potential sequestration in capacity studies. For example, in 2008, USGS initiated 

development of a methodology for estimating the capacity to store CO2 in geologic formations of the 

United States. In 2009, USGS published a proposed, risk-based methodology for GS capacity 

estimation. This report, Development of a Probabilistic Assessment Methodology for Evaluation of 

Carbon Dioxide Storage, is available at http://pubs.usgs.gov/of/2009/1035/ofr2009-1035.pdf. 

Comment: This isn't about me, and it isn't about you, it's about global climate change. 

That's why we're here, that's why anybody's contemplating geological 

sequestration. 

Just this week in the current issue of Science Magazine, Peter Cox and Chris 

Commenter Organization: Fond du Lac Reservation Comment ID: 24092

Commenter Name: Mark Singer Letter ID: 0504

Commenter Organization: Green America Project, LLC Comment ID: 21242

735
Jones report research that gives more bad news. New data shows that, this is 

the, the current issue, new data shows that climates sensitivity of the carbon 

cycle is now constrained at the high end of the range of values consistent with 

contemporary records. 

Previous studies gave a broad range of possible values from relatively minor to 

alarming. Cox and Jones now constrain it to the high end. If you read the 

article, it's written in a very dry, emotionless tone. But in a personal 

communication Peter Cox my question, which was, you know, is this good news or 

bad news, it is bad news for the world, but its bad news that we have to hear. 

Response: EPA clarifies that climate change mitigation is outside the scope of the GS rulemaking. 

Rather, the purpose of the Class VI GS rule is to ensure consistency in permitting underground injection 

of CO2 at GS operations across the United States and provide requirements to prevent endangerment of 

USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Comment: I recognize that the Supreme Court of the United States has given the EPA the 

regulatory authority to regulate CO2. Over the past eighteen months, I have come 

to the conclusion that managed production of CO2 is not the cause of global 

climate change. 

Dr. Roy Spencer of the University of Alabama has written a book called Climate 

Confusion. In this book he states that man's production of CO2 is equivalent to 

one molecule of CO2 for every 100,000 molecules of the atmosphere over a five 

year period. So when we hear these numbers of millions and millions of tons of 

CO2 being released in the atmosphere, we must put that in context of what part 

of that is generated by man. Dr. Spencer thinks that this is not a significant 

contribution to global warming. 

I have also read numerous articles, five different books, consulted with several 

PhD. Climatologists, in particular, Dr. William Gray from Colorado State 

University who is known for his annual forecast of hurricane activity. All of 

the literature that I have read further indicate that man's production of CO2 is 

not the cause of climate change. 

The issue of CO2 causing climate change is not a closed issue as some would have 

you believe. 

I would refer you to a project called the Petition Project written by the Oregon 

Institute of Science and Medicine where over 31,000 scientists have signed a 

petition to the President of the United States of America saying to take drastic 

action with respect to eliminating mass production of CO2 will not do anything 

to minimize climate change. 

So, I respect the EPA for its efforts and attempts to do something to comply 

with the mandate by the U.S. Supreme Court and to also respond to the apparent 

public concern of climate change by man. However, as we go forward the 

development of these regulations, both the regulation of drinking water quality 

Commenter Name: Dave Bufalo Letter ID: 0522

Comment ID: 21468

736
and atmospheric relationship to, I would urge the EPA to look closely at the 

cost benefit ratios of what this is going to cost. 

Response: EPA clarifies that climate change mitigation is outside the scope of the Class VI GS 

rulemaking. Rather, the purpose of the Class VI GS rule is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

EPA clarifies that the Class VI GS requirements apply to owners or operators of injection wells used to 

inject CO2 for permanent storage. The Class VI GS rulemaking is promulgated under Safe Drinking 

Water Act authority and does not relate to any endangerment and cause or contribute findings under the 

Clean Air Act. The Class VI GS requirements do not depend upon, and are unaffected by, Clean Air Act 

endangerment and cause or contribute findings. More information on EPA's Endangerment and Cause or 

Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act can be found at 

http://www.epa.gov/climatechange/endangerment.html. 

Other EPA Comment Codes and Descriptions: 5520 2.10.1 Appropriateness of existing public 

participation requirements (Part 25 and Part 124) for GS (seeking comment) 

Comment: Modeling data should have been provided well before the beginning of this thirty 

day period, this comment period. Again, we need more time. 

I also want to point out that a remediation plan should have been developed by 

now to deal with all possible contamination events in tandem with this 

particular process especially in view of EPA's, some of EPA's past failures to 

perform adequate risk monitoring and timely detection of remediation of 

contamination. Obviously, a remediation plan needs to be in place along with 

this particular proposal. Please provide us with that remediation plan and give 

the public time to comment on that as well. 

EPA's management of carbon capture and sequestration operations should be 

absolutely transparent to the public and so today, I want to call for real time 

online postings and RSS feeds of all incidents no matter how minor to interested 

members of the public. EPA should be providing such reporting for all incidents 

already and not just for carbon sequestration leaks, but for really I think all 

incidents across your entire realm of responsibility. Again, with the 

transparency, the public needs to know what is going on a lot easier than it 

currently is for us to find things out. 

I am not a geologist or a mining engineer, but I think I have some common sense 

and as a U.S. citizen, I just must insist that EPA adopt a more comprehensive 

method for evaluating IGCC and carbon sequestration, carbon capture and 

sequestration in view of the now well known fact that carbon based fuels are 

roasting our atmosphere and rapidly reducing the viability of our planet. 

Response: EPA clarifies that the final rule does not change the public notice requirements for injection 

well owners or operators already required under 40 CFR Part 124. However, because of the unique 

nature of GS projects, and the anticipated level of public interest in GS projects, EPA encourages early 

public involvement in GS projects. Providing the public with accurate, project specific information in 

Commenter Name: Becky English Letter ID: 0524

Commenter Organization: Sierra Club Comment ID: 21484

737
the early stages of each GS project can help clarify project details and avoid public misperceptions about 

the nature and safety of GS projects, and will allow a potential GS owner or operator and the permitting 

agency to address the public's concerns before the permitting process is complete. 

EPA clarifies that the final GS rule requires each owner or operator to develop an emergency and 

remedial response plan prior to receiving a permit to inject carbon dioxide. See §146.94. This plan must 

be submitted to the Director along with the permit application and will be available for review during 

the public comment period for the draft permit. Each owner or operator will be responsible for any 

remediation associated with his or her well. The rule also requires each owner or operator to maintain 

financial responsibility for emergency and remedial response. See §146.85(a). EPA is developing 

guidance on both financial responsibility and emergency and remedial response plans. 

EPA agrees with commenters that the use of new forms of information technology can improve public 

participation and understanding of GS projects and the associated injection technologies involved. EPA 

does not require the use of any new information technologies to inform the public, but encourages GS 

project operators and permitting authorities to use the Internet as well as both new and established tools 

to explain and post information on the latest developments. This information may include schedules for 

hearings, briefings, and other opportunities for involvement. EPA plans to conduct outreach on the GS 

rule, and provides GS related information on its website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. EPA currently uses social 

networking applications for important information (e.g., Facebook and Twitter), and will encourage GS 

operators and permitting authorities to use similar technologies to keep the public informed of GS 

projects. 

Comment: So I'd like to start with a note and say that this is not an attempt to 

legitimize or to further perpetuate the use of coal. We believe that there are 

much better, cheaper, and cleaner ways to meet our energy needs. Nonetheless, 

there is a very good reason why we do need to have CCS in the mitigation 

portfolio as well and this is because of the world's vast coal resources, the 

projected business as usual use of this resource and the pace at which we see 

climate change evolving. We believe that coal, mainly in China is and climatic 

changes are on a collision course and we really need to do something about it. 

Response: EPA clarifies that the purpose of the Class VI GS rule is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Regulating the use of coal or any energy form is outside the scope of the Class VI GS rulemaking. More 

information on EPA's Endangerment and Cause or Contribute Findings for Greenhouse Gases under 

Section 202(a) of the Clean Air Act can be found at 

http://www.epa.gov/climatechange/endangerment.html. 

Comment Code: 1290 1.1.2.2 Comments that EPA should regulate CO2 as a pollutant 

Individual Comments 

Commenter Name: George Peridas Letter ID: 0534

Commenter Organization: Natural Resources Defense Council (NRDC) Comment ID: 21450

738
Comment: Dear Administrator Johnson and EPA staff: I urge you to take immediate action 

and rule that carbon dioxide and other global warming pollutants clearly 

"endanger the public health and welfare" and thus should be regulated under the 

Clean Air Act. Carbon dioxide (CO2) pollution is the primary cause of the 

climate crisis. We're already seeing dramatic and dangerous climate effects 

today, and the climate crisis threatens the very livability of our planet for 

our children. We must reduce CO2 pollution now. Rather than continue to rely on 

polluting fossil fuels, we can "Repower America" by using energy sources that 

don't emit CO2, and make the switch to 100% clean electricity. 

Response: EPA clarifies that the Class VI GS requirements are designed to ensure consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. The requirements apply to owners or operators of injection wells used to inject CO2 for 

permanent storage. The Class VI GS rulemaking is promulgated under Safe Drinking Water Act 

authority and does not relate to any endangerment and cause or contribute findings under the Clean Air 

Act. The Class VI GS requirements do not depend upon, and are unaffected by, Clean Air Act 

endangerment and cause or contribute findings. 

The Agency clarifies that the use of “clean electricity” is outside the scope of the GS rulemaking. More 

information on EPA's Endangerment and Cause or Contribute Findings for Greenhouse Gases under 

Section 202(a) of the Clean Air Act can be found at 

http://www.epa.gov/climatechange/endangerment.html. 

Other EPA Comment Codes and Descriptions: 1310 1.1.2.4 Comments on other "out of scope" 

issues, e.g., pore space ownership 

Comment: The Supreme Court recognized in Massachusetts v. EPA [FN2] that EPA has 

authority and, indeed an obligation, under the Clean Air Act to regulate 

emissions of greenhouse gases, including CO2, that "cause or contribute to air 

pollution that may reasonably be anticipated to endanger public health or 

welfare." [FN3] Similarly, the D.C. Circuit’s remand of the power plant new 

source performance standards ("NSPS") places EPA in the position to regulate CO2 

emissions from new and also existing sources within that industrial sector. 

[FN4] The Environmental Appeals Board EAB also recently has rejected the 

agency’s arguments that it is not authorized to issue best available control 

technology (BACT) emissions limits for CO2 in the context of a new source air 

permit decision for a large new coal-fired power plant, under the Clean Air 

Act’s Prevention of Significant Deterioration (PSD) new source review authority. 

[FN5] 

[FN2: 127 S.Ct. 1438 (2007).] 

[FN3: Id. at 1460-61.] 

[FN4: Order, NY, et al. v. EPA, D.C. Cir. No. 06-1322 (Sept. 24, 2007). Once 

NSPS are set for an industry under section 111(b), 42 U.S.C. §7411(b), the Act 

requires EPA to set standards for states to regulate emissions from existing 

sources in that industry. 42 U.S.C. § 7411(d).] 

Commenter Name: Anonymous3 Letter ID: 0138

Comment ID: 23078

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22272

739
[FN5: In re: Deseret Power Electric Coop., PSD App. No 07-03, Slip Op. (Nov. 13, 

2008). The memorandum issued December 18, 2008 by Administrator Johnson entitled 

"EPA’ Interpretation of Regulations that determine Pollutants Covered by Federal 

Prevention of Significant Deterioration (PSD) Permit Program" (Johnson PSD memo) 

is procedurally deficient, and, in any event, states explicitly on its face that 

it is not intended to supersede the EAB’s decision in the Deseret case. Johnson 

memo at 2. Nor, indeed, can it lawfully do so.] 

Response: The purpose of the Class VI GS regulation is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

The requirements apply only to GS injection technologies including well construction, operation, 

monitoring and testing technologies. The Supreme Court decision under Massachusetts v. EPA and 

Clean Air Act (CAA) provisions related to New Source Performance Standards (NSPS) and Best 

Available Control Technology (BACT) determinations are outside the scope of this Class VI GS 

rulemaking. 

The Class VI GS rulemaking is promulgated under Safe Drinking Water Act authority and does not 

relate to any endangerment and cause or contribute findings under the Clean Air Act. The Class VI GS 

requirements do not depend upon, and are unaffected by, Clean Air Act endangerment and cause or 

contribute findings. More information on EPA's Endangerment and Cause or Contribute Findings for 

Greenhouse Gases under Section 202(a) of the Clean Air Act can be found at 

http://www.epa.gov/climatechange/endangerment.html. 

In a separate rulemaking under authority of the Clean Air Act, EPA is amending the Greenhouse Gas 

Reporting Program at 40 CFR Part 98 to add reporting requirements for CO2 injection and geologic 

sequestration. The greenhouse gas reporting requirements build on the requirements outlined in the 

Class VI GS rule with the additional goals of verifying the amount of CO2 sequestered and collecting 

data on any CO2 emissions to the surface from GS facilities. 

Other EPA Comment Codes and Descriptions: 1400 1.2 Comments on EPA's Authority to Regulate 

Injection of CO2 

Comment: The preamble to the proposed GS rule states "EPA is not proposing regulations for 

CO2 under the Clean Air Act (CAA) in this proposed rulemaking". As noted in our 

previous letter and comments, it is clear the Clean Air Act provides authority to regulate 

the geologic sequestration of CO2. Therefore CATF urges EPA to reconsider the 

position stated in the preamble and propose for comment, as part of the contemplated 

NODA, the inclusion of GS regulations under the Clean Air Act in the proposed 

rulemaking. 

Response: EPA clarifies that the scope of the GS regulation is limited to injection of CO2, and that all 

requirements in the GS rule are designed for the purpose of protecting USDWs from endangerment. 

Consequently, this comment is outside the scope of this rulemaking. The SDWA does not provide the 

UIC Program with the authority to develop regulations for all areas related to GS, such as releases to the 

atmosphere. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Commenter Name: Kurt Waltzer Letter ID: 0292

Commenter Organization: Clean Air Task Force Comment ID: 25277

740
Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

In a separate rulemaking under authority of the Clean Air Act, EPA is amending the Greenhouse Gas 

(GHG) Reporting Program at 40 CFR Part 98 to add reporting requirements for facilities that conduct 

GS (subpart RR) and all other facilities that inject CO2 underground (subpart UU). For additional 

information, see the section of the final GS rule preamble entitled, "How Does Mandatory Reporting of 

Greenhouse Gases (GHGs) Relate to This Rulemaking?” and the GHG Reporting Program rulemaking 

and docket. 

Comment Code: 1300 1.1.2.3 Comments on other aspects of CCS (capture, transport) 

Individual Comments 

Comment: Federal Pipeline Standards for Transporting CO2: Co-ordinate with the US 

Congress and federal agencies to adopt national standards for materials 

requirements and performance specifications in pipelines used to transmit CO2. 

Response: EPA clarifies that the purpose of the Class VI GS rule is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Transportation of CO2 via pipelines is outside the scope of the Class VI GS rulemaking. 

Comment: As numerous EPA and Department of Energy publications have reiterated, the 

regulation of the geologic storage of CO2 for the purpose of safeguarding 

underground sources of drinking water (USDWs) and public health, cannot be 

isolated from the construction of a broad national framework for the regulation 

Commenter Name: Anonymous2 Letter ID: 

0133

Commenter Organization: Sierra Club National Global Warming and Energy 

Committee and Sierra Club California-Nevada Regional Conservation Committee on 

Energy and Climate Change

Comment ID: 

21583

Commenter Name: Anonymous2 Letter ID: 

0133

Commenter Organization: Sierra Club National Global Warming and Energy 

Committee and Sierra Club California-Nevada Regional Conservation Committee on 

Energy and Climate Change

Comment ID: 

21600

741
of carbon capture and sequestration (CCS) in its myriad current and anticipated 

forms. While technical standards are of paramount importance in addressing 

safety issues attendant to CO2 injection and storage, there are two other key 

factors in successfully implementing an integrated CCS program: regulatory 

oversight and public acceptance. 

Response: EPA clarifies that the Class VI GS regulation is being promulgated under authority of the 

Safe Drinking Water Act (SDWA). The purpose of the Class VI GS rule is to ensure consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. 

EPA believes that the Class VI GS regulation, which builds upon the long-standing protective 

framework of the UIC program, will provide the regulatory certainty and oversight that operators have 

requested. EPA also believes that tailored requirements to ensure that GS projects are permitted, sited, 

constructed, operated, and closed in a manner that avoids releases of CO2 will protect USDWs from 

endangerment and thus may improve public confidence in GS. 

Comment: F. Federal Pipeline Standards for Transporting CO2 

Recommendation F: Co-ordinate with the US Congress and federal agencies to adopt 

national standards for materials requirements and performance specifications in 

pipelines used to transmit CO2. 

The EPA's Office of Water has stated that the transmission of captured CO2 to 

injection storage sites is somewhat outside the scope of the SDWA ("Proposed UIC 

Regulations for Geologic Sequestration of Carbon Dioxide" February 2008; See: 

http://www.epa.gov/safewater/uic/pdfs/page_uic_washingtondc_feburay2008_summ 

ary.pdf). However, the EPA is coordinating its issuance of UIC regulations with 

the US Department of Transportation, and has recognized the importance of 

maintaining safety standards and risk management practices throughout the 

various stages of carbon capture, transportation, and storage. Currently in the 

US, about 3,600 miles of CO2 pipelines are in operation, primarily located in 

Texas and New Mexico. They carry CO2 from underground reservoirs, natural gas 

processing facilities, ammonia manufacturing plants, and a North Dakota coal 

gasification project to oil fields for use in EOR/EGR (See: 

http://www.nicholas.duke.edu/nicholas/insider/thegreengrok/co2pipeline/). 

According to a recent press release, a Norwegian risk management company is 

partnering with European businesses and governments to establish EU pipeline 

standards for transmitting large amounts of captured CO2 to onshore and offshore 

storage sites. The guidelines will relate to issues of "safety, fast propagating 

ductile fractures, fatigue crack growth, pipeline operation conditions, flow 

assurance, corrosion and material compatibility," and will address all phases of 

construction and lifetime performance, "including the design, testing, 

Commenter Name: Anonymous2 Letter ID: 

0133

Commenter Organization: Sierra Club National Global Warming and Energy 

Committee and Sierra Club California-Nevada Regional Conservation Committee on 

Energy and Climate Change

Comment ID: 

21616

742
inspection, operation, maintenance and de-commissioning phases"(See: 

http://www.dnv.com/press_area/press_releases/2008/developingthefirstco2pipelines 

tandard.asp) . One important objective of the standards is to standardize the 

transport of CO2 so that it will become uniformly insurable by private insurance 

companies. 

Reportedly, American-based oil companies are participating in the European rulemaking process, and so presumably will have ongoing information about the 

standards adopted by the EU. This information can enhance the decision making 

process during the coming period that US regulations are being promulgated for 

all stages of carbon capture, transportation, and storage. Several 2008 

Congressional Research Reports indicate that the US Congress has begun to 

address the issues related to constructing and operating a network of CO2 

pipelines for CCS(See: http://assets.opencrs.com/rpts/RL33971_20080117.pdf and 

http://ncseonline.org/nle/crsreports/08Apr/RL34307.pdf). When such a network is 

constructed, it is probable that the Federal Energy Regulatory Commission (FERC) 

and the Surface Transportation Board (STB) will receive jurisdiction over 

interstate pipelines used for this purpose. Currently, the Pipeline and 

Hazardous Materials Safety Administration applies safety requirements to CO2 

pipelines that are mandated by CO2's classification as a Class 2.2 (nonflammable gas) hazardous material under DOT regulations (40 CFR 172.101). Since 

it is likely that a federally-administrated hierarchy will be established over 

the next decade, it is important that the EPA's terrestrial storage regulations 

remain compatible with progressive developments for the transportation of CO2 to 

the injection well sites. 

Response: EPA clarifies that regulation of CO2 pipelines is outside the scope of the GS rulemaking. 

Rather, the purpose of the Class VI GS rule is to ensure consistency in permitting underground injection 

of CO2 at GS operations across the United States and provide requirements to prevent endangerment of 

USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Comment: 3.) The SWP would like to comment on the compatibility of the proposed rule 

with other regulatory processes. 

The CCS process is extremely complex. The proposed rule is associated with 

storage of CO2 as it relates to protecting USDWs under the UIC program. Other 

aspects of the process including capture, compression, and transport of CO2 are 

not addressed within the proposed rule, and rightfully so since those processes 

are independent of the UIC program. In the overall scheme of permitting a 

commercial scale CCS site, has any consideration been given to the compatibility 

of the UIC proposed rule with other permitting processes (i.e., pipeline, air 

quality, etc) so as to streamline all regulatory requirements? The SWP would 

like to suggest collaboration with other permitting agencies, at the state and 

federal level, as regulatory framework development progresses so that the 

permitting of an entire CCS project is not unrealistically burdensome for the 

regulators and owners/operators. 

Commenter Name: Dawn A. Thorne Letter ID: 0134

Commenter Organization: University of Utah Energy and Geoscience Institute on 

behalf of the Southwest Regional Partnership

Comment ID: 

21663

743
Response: EPA agrees that a strong regulatory framework will be important to ensuring that GS is 

deployed safely. EPA believes that the Class VI GS regulation will provide certainty, consistency, and 

transparency to owners or operators and the public about requirements that apply to GS injection across 

the United States. The Class VI GS regulation builds upon the long-standing, protective framework of 

the UIC program, which has been regulating the injection of billions of gallons of liquids for decades. 

The Class VI GS regulation enhances this existing framework with requirements for GS wells that are 

tailored to the unique nature of large scale GS of CO2. These additional protective requirements include 

more extensive geologic testing, detailed computational modeling of the AoR and periodic reevaluations, detailed requirements for monitoring and tracking the CO2 plume and pressure front, and 

extended post-injection monitoring and site care. 

In response to the suggestion that the Agency develop an integrated permitting process that addresses 

the entire CCS process, EPA clarifies that the UIC program’s authority under SDWA is focused on 

ensuring protection of USDWs from endangerment. The capture and transport of CO2 are outside of the 

scope of the Class VI GS rulemaking. 

Comment: to date with this demonstration. However, there are other pieces to the puzzle 

that still need to fall into place to make this a viable option for our 

continued use of coal in a carbon constrained world. Affordable, efficient and 

commercially available carbon capture technology is still years away. In 

addition, because not all existing power plants were built over suitable 

geologic formations for injection we must contemplate construction of a pipeline 

infrastructure to transport supercritical CO2 fluid from a power plant to an 

appropriate injection site. Another huge issue which has yet to be broached by 

Response: EPA agrees that a strong regulatory framework will be important to ensuring that GS is 

deployed safely. EPA believes that the Class VI GS regulation will provide certainty, consistency, and 

transparency to owners or operators and the public about requirements that apply to GS injection across 

the United States. The Class VI GS regulation builds upon the long-standing, protective framework of 

the UIC program, which has been regulating the injection of billions of gallons of liquids for decades. 

The Class VI GS regulation enhances this existing framework with requirements for GS wells that are 

tailored to the unique nature of large scale GS of CO2. These additional protective requirements include 

more extensive geologic testing, detailed computational modeling of the AoR and periodic reevaluations, detailed requirements for monitoring and tracking the CO2 plume and pressure front, and 

extended post-injection monitoring and site care. 

In response to the suggestion that the Agency develop an integrated permitting process that addresses 

the entire CCS process, EPA clarifies that the UIC program’s authority under SDWA is focused on 

ensuring protection of USDWs from endangerment. The capture and transport of CO2 are outside of the 

scope of the Class VI GS rulemaking. 

Other EPA Comment Codes and Descriptions: 1530 1.2.3.1 State regulatory efforts on GS (seeking 

comment) 

Comment: 6. NRECA urges EPA to issue more definitive direction in the Final Rule 

Commenter Name: Skiles Boyd Letter ID: 0160

Commenter Organization: DTE Energy Comment ID: 21267

Commenter Name: James Stine Letter ID: 0163

Commenter Organization: National Rural Electric Cooperative Association 

(NRECA)

Comment ID: 

21327

744
regarding the regulation of CO2 injection activities that cross state 

boundaries. This issue is mentioned in the Preamble to the Proposal but receives 

little attention. See 73 Fed. Reg. at 43497. Rather, EPA simply observes that 

"some injection activities may raise cross-state boundary issues that are beyond 

the scope of this rulemaking." Id. More guidance should be given regarding how 

such cross-state activities should be regulated, including making clear in the 

Final Rule that Owners or Operators of Class VI CO2 GS projects will seek a 

Class VI permit for that operation from the state in which the wellhead is 

located; in other words, a given state is the permitting body for any Class VI 

CO2 GS project with a wellhead in that state. EPA should direct states to 

consult and coordinate with other affected states (i.e., other states to which 

the underground portion of the well may extend and/or those to which there could 

be a subsurface release or migration of injected material) in determining how to 

avoid duplicative or dueling regulatory systems. NRECA urges EPA to play a 

leadership role and proactively address these issues by suggesting procedural 

guidelines for inter-state regulation and cooperation. 

Response: EPA understands that the CO2 plumes for large GS projects may cross state, tribal, EPA 

Regional, or national boundaries. The final GS rule, at §146.82(a)(2), requires the owner or operator to 

identify all State, Tribal, and Territorial boundaries within the AoR. Based on this information, the 

Director must provide written notification to all States, Tribes, and Territories to inform them of the 

permit application §146.82(b) and ensure that they are involved in any necessary processes (e.g., 

development of the emergency and remedial response plan (146.94)). The Agency encourages 

transparency in the permitting process and anticipates that State-State/State-Tribal communication on 

GS permitting will facilitate information sharing and encourage safe, protective projects. 

Because some GS projects will require coordination across State and Tribal jurisdictions and plans, EPA 

will work with the appropriate entities to facilitate communication among States and Tribes interested in 

obtaining Primacy during the implementation phase of the GS regulation. Such communication may 

involve other organizations such as the Sierra Club, NDWAC, associations, and other experts. However, 

the responsibility for addressing such subjects ultimately rests with the States and Tribes with primacy. 

EPA is developing a series of guidance documents to support the GS rulemaking. These are available on 

EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment: Electric Reliability -- Pg. 47 

APPA believes that potential impacts to electric reliability should be considered in 

promulgating the UIC Class VI permitting program rules. 

NERC’s study can be found at: 

http://www.nerc.com/files/2008-Climate-Initiatives-Report.pdf 

Response: The UIC program’s authority under the SDWA focuses on ensuring that Class VI GS 

projects are permitted, sited, constructed, operated, monitored, and closed in a manner that protects 

USDWs from endangerment. Regulation of electricity providers is outside the scope of the Class VI GS 

rulemaking. 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23374

745
Comment: One of the largest hurdles: Parasitic Power 

The fundamental challenge confronting the utility industry is in carbon 

separation and in reducing the parasitic loss of energy at a power plant. 

Parasitic loss issues at power plants are best explained in Attachments 2 and 3 

by Doug Carter. [Please see EPA-HQ-OW-2008-0390-0169.pdf for Attachments 2 and 

3.] These two papers explain to both laymen and technical experts why parasitic 

energy could be one of several "deal killers" for new power plants with GS.[FN4] 

These parasitic are problems that are very fundamental and will determine 

whether power plants pursue this technology or opt for another type of 

generation such as nuclear power or perhaps natural gas (which has roughly half 

of the carbon dioxide as coal). See Figure 2 which highlights the processes 

which contribute to the parasitic power demands of CCS. Even if carbon 

separation technology is commercially demonstrated at > 30 MW in the next few 

years, parasitic power or energy losses are a huge disincentive to use this new 

generation technology. 

[Please refer to the p. 19 of the pdf file for Figure 2 of Parasitic Power 

Losses in CCS Power Plant] 

The storage issues can be equally daunting but the fundamental question of 

separation and parasitic power are so overwhelming that it is not entirely clear 

how many municipal governments will want to pursue this technology until those 

economic issues (especially the parasitic power) are sorted out. The other 

remaining issue in the three legged footstool is the question of infrastructure 

and logistics. Without a massive investment in infrastructure for additional 

pipelines and booster compressors, APPA wonders how many of these plants will be 

built in the first 10-30 years. The oil and gas industry had 35 years to build 

up the essential infrastructure for CO2 injection in the context of oil and gas 

recovery. This infrastructure includes pipelines, booster compressors and 

feedstock delivery. See Figure 3 for a map showing current CO2 pipelines in the 

U.S. [Please refer to p. 21 of the pdf file for Figure 3 of U.S. CCS Pipeline 

Map] The industry also has systems in place to remove/treat produced waters. 

These systems are not in place in states with no oil or gas production. Those 

oil and gas recovery fields were and are highly profitable and had a revenue 

stream to offset the investments in delivery methods such as construction of 

pipeline or adaptation of existing natural gas pipelines, booster compressors, 

or for the use of tankers for some small quantities of CO2 for use at production 

fields. The economics for power plants are not yet ripe for such investments 

because power plants would not have the additional revenue stream coming in for 

infrastructure investments coming off the oil and gas production revenue stream 

Nor are the right of way or surface right issues sorted out by state law before 

CO2 can be either transported across jurisdictional lines or stored as a 

commodity without surface property rights being sorted out. These commercial and 

practical impediments to geologic sequestration (GS) are enormous and should not 

be minimized simply because we wish to find a technology that will work to 

enable us to use coal or natural gas in the future. These commercial, technology 

and feasibility impediments are not EPA’s problems to fix-but they are mentioned 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23393

746
here because we are trying to inject "reality" into the zealous discussions in 

the trade press, on television, and at coal plant hearings about the viability 

of geologic sequestration at new coal plants in 2008. These same issues apply to 

the existing coal plant fleet. These same commercial issues apply in the context 

of natural gas generation sources where no carbon separation technology exists 

today without dramatic parasitic power impacts which would typically be too 

onerous for existing plants. 

[Figure 3. Please refer to p. 21 of the pdf file for Figure 3 of U.S. CCS Pipeline Map] 

[FN4] L.D. Carter, White Paper, "Carbon Capture and Storage From Coal-based 

Power Plants: A White Paper on Technology for the American Public Power 

Association (APPA)," May 2007 and L.D. Carter, White Paper, "Retrofitting Carbon 

Capture Systems on Existing Coal-fired Power Plants," November 2007 

Response: EPA emphasizes that the UIC program’s authority under the SDWA is focused on ensuring 

that Class VI CO2 injection projects are permitted, sited, constructed, operated, monitored, and closed in 

a manner that protects USDWs from endangerment. The capture and transport of CO2 are not within the 

UIC program’s authority. 

Comment: Electricity Reliability 

While the EPA UIC Class VI program permitting proposed rule did not call for 

comments on electricity reliability, we offer our comments to NERC on 

Reliability Impacts of Climate Change Initiatives, dated July 16, 2008, which we 

believe should be considered. These are included in the Appendix. [See EPA-HQOW-2008-0390-0169.pdf for these comments.] NERC’s "Reliability Impact of Climate 

Change Initiatives" (Nov. 2008) link is: 

http://www.nerc.com/files/2008-Climate-Initiatives-Report.pdf to the final 

report (23pp). 

Response: As described above, the capture and transport of CO2 are not within the UIC program’s 

authority. The UIC program’s authority under the SDWA focuses on ensuring that Class VI GS projects 

are permitted, sited, constructed, operated, monitored, and closed in a manner that protects USDWs 

from endangerment. 

Comment: DISCUSSION 

1. Legal and Regulatory Challenges to Commercial-Scale CO2 GS 

It is important to recognize that the development of a viable, large-scale 

commercial CCS program requires resolution of technical, policy, and legal 

issues that are beyond the scope of this rulemaking. The General Accounting 

Office ("GAO") recently issued a report entitled "Climate Change - Federal 

Actions Will Greatly Affect the Viability of Carbon Capture and Storage As a Key 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23433

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23469

747
Mitigation Option" which emphasizes that significant technological barriers 

involving CO2 capture technologies must be resolved before a successful CO2 CCS 

program of the scale envisioned by policymakers can be achieved. GAO-08-1080 at 

3-5 (September 2008) ("GAO Report"). The GAO Report also references a number of 

regulatory and legal uncertainties involving CO2 storage, leakage, and ownership 

issues, the resolution of which is critical to a successful CCS program. Id. 

Federal agencies must also work together to "examine how CO2 pipeline 

infrastructure might be regulated to accommodate commercial-scale CCS," as well 

as how "CO2 emissions reductions from CCS will be treated in a future emissions 

trading scheme." Id. at 4. 

Response: EPA emphasizes that the UIC program’s authority under the SDWA is focused on ensuring 

that Class VI CO2 injection projects are permitted, sited, constructed, operated, monitored, and closed in 

a manner that protects USDWs from endangerment. The capture and transport of CO2 are not within the 

UIC program’s authority. 

Other EPA Comment Codes and Descriptions: 1540 1.2.3.2 Climate change legislation 

Comment: Single, Clear Regulatory Structure 

There should be a single, clear regulatory structure applicable to CCS rather 

than multiple, ill-suited regulatory and liability statutes and regulations that 

likely will discourage CCS To that end, the CCS Alliance believes that a 

beneficial approach would be to enact at the federal level a new regulatory 

structure specific to CCS. 

Response: EPA acknowledges that GS falls within the broader context of CCS and the need for 

regulatory clarity to ensure that USDWs are protected from endangerment. In developing the final GS 

rule, the Office of Water coordinated with other Agency program offices and across federal agencies 

(e.g., with the Department of Energy; United States Geological Survey; Bureau of Ocean Energy 

Management, Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of 

Land Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

EPA is also aware that states are currently in various stages of developing statutory frameworks, 

regulations, technical guidance, and strategies for addressing CCS and GS. States can use multiple 

authorities beyond those afforded under the SDWA and UIC regulations, including laws and policies 

addressing surface access and land rights, unitization of fields, pore space ownership, mineral rights, 

worker safety and emergency preparedness, and maximization of state oil and gas resource exploitation. 

EPA plans to work closely with states and tribes as they develop Class VI primacy programs in this 

broader context. EPA adds that states may adopt more stringent standards for Class VI wells than the 

Federal requirements. 

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23800

748
In a separate rulemaking under authority of the Clean Air Act, EPA is amending the Greenhouse Gas 

(GHG) Reporting Program at 40 CFR Part 98 to add reporting requirements for facilities that conduct 

GS (subpart RR) and all other facilities that inject CO2 underground (subpart UU). For additional 

information, see the section of the final GS rule preamble entitled, "How Does Mandatory Reporting of 

Greenhouse Gases (GHGs) Relate to This Rulemaking?” and the GHG Reporting Program rulemaking 

and docket. 

Other EPA Comment Codes and Descriptions: 1310 1.1.2.4 Comments on other "out of scope" 

issues, e.g., pore space ownership; 1400 1.2 Comments on EPA's Authority to Regulate Injection of 

CO2 

Comment: XII. RELATED ISSUES, NOT RAISED IN THE PROPOSED RULE, THAT REQUIRE 

RESOLUTION 

The SDWA does not provide EPA authority to develop regulations for many 

important areas related to the geological sequestration of CO2. Thus the draft 

rule cannot address all of the potential impediments to CCS development. Even if 

EPA were to promulgate a final UIC rule that encourages development of these 

critical technologies, there are other key factors that would need to be 

properly addressed before major investment in these technologies can be 

expected. 

The following sets forth key issues that will not be resolved through this 

rulemaking but are linked inextricably to the successful development and 

implementation of CCS technology. 

A. EMINENT DOMAIN AUTHORITY TO FACILITATE PIPELINE CONSTRUCTION 

Energy facilities for the public convenience and necessity, such as electric 

transmission facilities and natural gas pipelines, are able to make use of state 

or federal eminent domain authority to ensure that private landowners cannot 

block a project necessary for the public good. Eminent domain authority should 

be available for CO2 pipelines for CCS when it is necessary to cross private 

property. A substantial CO2 pipeline network may be required for the transport 

of CO2 from sites where it is produced to an injection site. CO2 pipelines for 

CCS clearly should be considered to be used for the public convenience and 

necessity. 

B. DETERMINATION OF SUB-SURFACE PROPERTY RIGHTS 

The government must address the ability to gain sufficient property rights to 

deep saline formations to conduct geologic sequestration. State property 

ownership regimes vary, but surface owners typically are considered to own 

property below the surface to the center of the earth. Safe sequestration of CO2 

will not have any effect on the surface, but GS injections will result in 

underground plumes that may stretch across many square miles under the property 

of multiple surface property owners. Property ownership issues have been 

resolved successfully in the context of EOR, but it should not be assumed that 

the same will be true for GS. Eminent domain authority should be available to 

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23877

749
obtain rights to subsurface storage space for geologic sequestration because of 

its public benefit. 

C. RESOLUTION OF SURFACE LIABILITY ISSUES 

Though this Proposed Rule is limited in its scope to underground injection of 

CO2 and the potential risks and resulting liabilities, issues regarding risks 

and liability at the surface must be addressed for CCS technology to fully 

develop. These include liability for major and sudden releases, seismic activity 

and ground heave, as well as liability under any GHG emission control regime 

when sequestered CO2, for the storage of which credits or offsets have been 

granted, is subsequently released into the upper atmosphere. 

Response: EPA acknowledges that the issue of GS falls within the broader context of CCS. EPA 

received a number of comments indicating that the Agency should further explore environmental and 

regulatory issues beyond the scope of the GS rule as proposed. This comment is outside the scope of this 

rulemaking. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

EPA recognizes that liability is an important issue to owners or operators but the Agency does not have 

authority under the SDWA to transfer long term liability from owners or operators to the state or federal 

government. Therefore, liability remains with the owner or operator. 

Comment: B. The Proposed Regulation Does Not Cover All Parties Involved in CCS Even 

Though Their Actions Create a Risk of Endangerment to USDWs. 

The proposed regulation applies only to "owners or operators of injection wells 

that will be used to inject CO2 into the subsurface for the purposes of GS." 73 

Fed. Reg. at 43,492; see id. at 43,534 (proposed 40 C.F.R. §144.18). Other 

parties involved in a CCS project, including the CO2 generator, transporter and

surface and sub-surface property owner(s), are not covered. As EPA notes, 

though, "[t]he SDWA provides EPA with the authority to develop regulations to 

protect USDWs." Id. at 43,495; see also 42 U.S.C. §300h(a)-(b), (d). That 

authority extends over all actors involved in the CCS process (not just the

Commenter Name: Wendy Jacobs Letter ID: 0183

Commenter Organization: Harvard Law School Environmental Law and Policy 

Center

Comment ID: 

25155

750
injection well owner or operator), at least to the extent their actions may

contribute to the risk of harm to USDWs.[FN11] 

For instance, EPA has recognized that "co-contaminants in the CO2 stream could 

endanger a USDW if the injectate migrates into a USDW." 73 Fed. Reg. at 43,497. 

The "types of impurities and their concentrations in the CO2 stream are likely 

to vary by facility, coal composition, plant operating conditions, and pollution 

removal technologies." Id. at 43,503. Yet the proposed regulation’s current 

standard for stream purity is loosely defined. The proposed regulation allows 

injection of a stream with "incidental associated substances derived from the 

source materials and the capture process, and any substances added to the stream 

to enable or improve the injection process." Id. at 43,535 (proposed 40 CFR § 

146.81(d) (definition of "carbon dioxide stream")). By regulating CO2 

generators and CO2 stream treatment (purification) facilities directly, EPA 

could reduce the likelihood that a contaminated CO2 stream would be injected 

into a GS well and thereby reduce the likelihood that such contaminants would 

endanger a USDW.[FN12] EPA should therefore consider setting specific requirements 

for the maximum concentrations of "incidental substances" in injected CO2 

streams to reduce the uncertainty about the proper level of treatment required. 

By imposing financial assurance requirements on those parties, EPA could also 

reduce the likelihood that costs and damages arising from such contamination 

would go unpaid, for example, if such costs exceeded the security posted by the 

owner or operator. Regulatory oversight would make these firms "more likely to 

undertake operating decisions that consider environmental (and remediation) 

costs." WRI ISSUE BRIEF at 6. 

[FN11] ELPC agrees, however, that EPA does not have authority under the SDWA to 

address all of the conduct of all of the parties involved in CCS or all of the 

risks posed by CCS, and therefore urges EPA to advocate on behalf of a broader 

mandate from Congress. See discussion at Part III(C)(1)(b). supra. 

[FN12] Note that even such a consideration would fall short of protecting many 

private sources of well-water which could be harmed by CO2 migration. EPA should 

provide for mandatory consultation with owners of private wells before 

permitting any sequestration project in an area with private well use. 

As a matter of equity, parties other than owners and operators should also be 

regulated to "ensure that risks are borne by those who share in the benefit of 

[GS] technologies." Id. at 9. For example, geological sequestration may "allow 

some [generators of CO2] to extend the life of their existing capital investment 

in plant machinery or plant processes." 73 Fed. Reg. at 43,531. Moreover, since 

"it is caps on greenhouse gas emissions that will explicitly establish a price 

for CO2 and will encourage utilities and others to invest in CCS in order to 

meet those caps," it is the generators of the CO2 -along with their 

customers-who may receive credits for sequestration. KLASS AND WILSON at 13. 

All parties who benefit from GS of CO2 should help bear the risks attendant to 

that sequestration. 

Response: EPA clarifies that the Class VI GS rule applies to owners or operators of wells that will be 

used to inject CO2 into the subsurface for the purpose of long-term storage. EPA clarifies that regulating 

CO2 generators and transporters is outside the scope of the Class VI GS rulemaking. The Class VI GS 

751
rule is designed to ensure consistency in permitting underground injection of CO2 at GS operations 

across the United States and provide requirements to prevent endangerment of USDWs in anticipation of

the eventual use of GS to reduce CO2 emissions. 

The GS rule does not set generic purity standards for CO2 injectate streams (e.g., a percent CO2). 

Instead, the GS rule addresses the quality and quantity of impurities by requiring owners or operators to 

submit information on the source of the CO2 and its physical and chemical properties. Specifically, the 

GS rule requires the owner or operator to submit data about the site, including an analysis of the 

chemical and physical characteristics of the CO2 stream, as required at §146.82(a)(7)(iv), and 

information on the compatibility of the CO2 stream with fluids in the injection zone and minerals in 

both the injection and the confining zones and the materials used to construct the well, per §146.82(c)

(3). This information can help the Director determine the potential for geochemical reactions between 

the injectate (CO2) and the host geologic formations, which could result in the plugging of pore spaces 

or the dissolution of formation minerals. 

Comment: - In order to more clearly illustrate the actual risks of CO2 transport and 

storage, EPA should work to dispel concerns that geologic sequestration could be 

encumbered with those requirements except possibly through the commingling of a 

captured CO2 stream with an actual waste stream. 

Response: The Class VI GS rule applies to owners or operators of wells that will be used to inject CO2 

into the subsurface for the purpose of long-term storage. EPA clarifies that regulating CO2 

transportation is outside the scope of the Class VI GS rulemaking. The Class VI GS rule is designed to 

ensure consistency in permitting underground injection of CO2 at GS operations across the United 

States and provide requirements to prevent endangerment of USDWs in anticipation of the eventual use 

of GS to reduce CO2 emissions. 

EPA received many comments regarding the applicability of the RCRA regulations and statute to CO2 

streams that are geologically sequestered under the final Class VI UIC well requirements. As a result, 

EPA has decided to initiate a separate proposed rulemaking specifically to examine the issue of RCRA 

applicability to CO2 streams being geologically sequestered, including the possible option of a 

conditional exemption from the RCRA requirements for CO2 GS in Class VI wells. EPA will consider 

these comments as part of its development of that proposal. The Agency will consider issues particular 

to RCRA in the context of that separate rulemaking, and recommends that the commenter read that 

proposed rule when it is published. The Agency notes that commenters who wish to submit comments 

on the RCRA proposal will need to do so during the comment period for that rule. Finally, EPA also 

notes that the final GS rule, which adds new regulations for Class VI wells under the Safe Drinking 

Water Act (SDWA), is not making any changes to the RCRA regulations. 

The GS rule does not set generic purity standards for CO2 injectate streams (e.g., a percent CO2). 

Instead, the GS rule addresses the quality and quantity of impurities by requiring owners or operators to 

submit information on the source of the CO2 and its physical and chemical properties. Specifically, the 

GS rule requires the owner or operator to submit data about the site, including an analysis of the 

chemical and physical characteristics of the CO2 stream, as required at §146.82(a)(7)(iv), and 

information on the compatibility of the CO2 stream with fluids in the injection zone and minerals in 

both the injection and the confining zones and the materials used to construct the well, per §146.82(c)

(3). This information can help the Director determine the potential for geochemical reactions between 

the injectate (CO2) and the host geologic formations, which could result in the plugging of pore spaces 

Commenter Name: John King Letter ID: 0211

Commenter Organization: Shell Exploration and Production Company (SEPCo) Comment ID: 22755

752
or the dissolution of formation minerals. 

Other EPA Comment Codes and Descriptions: 1510 1.2.2.3 Need for additional study 

Comment: o Potential ancillary effects of CCS -- such as pressure waves, which could move 

hundreds of miles and affect sequestration sites -- must be evaluated. 

Response: EPA agrees that continued research in all GS associated fields will be integral to 

development of GS technology. EPA notes that a study conducted by Lawrence Berkeley National 

Laboratory evaluated basin-scale hydrology and pressure changes that could occur as a result of GS; this 

study is described in EPA’s Notice of Data Availability and Request for Comment (74 FR 44802, see 

references to Birkholzer et al. 2008b). 

Comment: Very little data is available to evaluate the energy balance of various carbon 

capture processes. The evaluations available limit the efficiency of carbon 

capture (CC) to a percent recovered from the feed stack to the emission stack. 

Capturing the carbon is very energy intensive and may increase energy demand by 

up to 50%. (www.lowtechmagazine.com accessed October 27 2008). 

According to Greenpeace International: False Hope: Why carbon capture and 

storage won't save the climate, "capturing and storing carbon uses lots of 

energy; anywhere from 10-40% of a power station’s capacity. An energy penalty of 

just 20% would require the construction of an extra power station for every four 

built. These reductions in efficiency will require more coal to be mined, 

transported, and burned, for a power station to produce the same amount of 

energy as it did without CCS." 

The attached summary of a study by Wuppertal Institute, the German Aerospace 

Center (DLR), Zentrum für Sonnenenergie- und Wasserstoff-Forschung BadenWürttemberg (ZSW) and the Potsdam Institute for Climate Impact Research (PIK) 

for the German government (the full report available at: www.wupperinst.org, 

accessed on line Dec. 23 2008) offers an in depth study of CCS that evaluates 

the various power plant designs, transport, and storage costs; accesses life 

cycle, ecological criteria, carbon neutrality etc. Estimates in the study show a 

20 to 40% increase in energy consumption and the process will only lower 

emissions of CO2, ignoring the increases of other greenhouse gases (GHG). [SEE 

EPA-OW-2008-0390-0273.PDF FOR THIS DOCUMENT.] 

Consuming an additional 20 to 50% more coal to energize the capture of CO2 is a 

questionable tactic that must supported by transparent data analysis. 

Response: EPA clarifies that CO2 capture and the energy demands of CCS operations are outside the 

scope of the Class VI GS rulemaking. The UIC program’s authority under the SDWA focuses on 

ensuring that GS projects are permitted, sited, constructed, operated, monitored, and closed in a manner 

that protects USDWs from endangerment. 

Commenter Name: Diane VanDe Hei Letter ID: 0213

Commenter Organization: Association of Metropolitan Water Agencies 

(AMWA)

Comment ID: 

22938

Commenter Name: Mary Munn Letter ID: 0273

Commenter Organization: Fond du Lac Reservation Comment ID: 24083

753
Other federal agencies (e.g., DOE and the U.S. Geological Survey) have conducted research on 

available storage capacity and determinations of the feasibility of capturing and storing CO2 at the 

scales needed to address climate change. These agencies, along with private entities, have identified 

large areas for potential sequestration in capacity studies. For example, in 2008, USGS initiated 

development of a methodology for estimating the capacity to store CO2 in geologic formations of the 

United States. In 2009, USGS published a proposed, risk-based methodology for GS capacity 

estimation. This report, Development of a Probabilistic Assessment Methodology for Evaluation of 

Carbon Dioxide Storage, is available at http://pubs.usgs.gov/of/2009/1035/ofr2009-1035.pdf. 

Comment: Recommendations: 

· A thorough mass balance of the CO2 generated in the participating fossil 

energy processes, generating CO2 must be demonstrated to prove the feasibility 

of the proposal; including mining and transport of the fossil fuel to power 

plants, extraction and compression of the CO2 emissions, transport, and 

injection the CO2 into a geologic formation. 

Response: EPA clarifies that other federal agencies (e.g., DOE and the U.S. Geological Survey) have 

conducted research on available storage capacity and determinations of the feasibility of capturing and 

storing CO2 at the scales needed to address climate change. These agencies, along with private entities, 

have identified large areas for potential sequestration in capacity studies. For example, in 2008, USGS 

initiated development of a methodology for estimating the capacity to store CO2 in geologic formations 

of the United States. In 2009, USGS published a proposed, risk-based methodology for GS capacity 

estimation. This report, Development of a Probabilistic Assessment Methodology for Evaluation of 

Carbon Dioxide Storage, is available at http://pubs.usgs.gov/of/2009/1035/ofr2009-1035.pdf. 

The UIC program’s authority under the SDWA focuses on ensuring that GS projects are permitted, 

sited, constructed, operated, monitored, and closed in a manner that is protective of USDWs. Coal 

mining and CO2 capture and transport are outside the scope of the Class VI GS rulemaking. 

Comment: The commitment of resources; human, material, and capital, required to construct 

the network of pipelines and wells for a project that is most likely 

energetically untenable, cannot be supported without a proper evaluation of 

carbon throughput of the entire process. 

Response: As described above, CO2 transport is outside the scope of the Class VI GS rulemaking, 

which is focused on ensuring that Class VI CO2 injection projects are permitted, sited, constructed, 

operated, monitored, and closed in a manner that is protective of USDWs. 

Comment: I would like to start my comments in talking about the general approach the EPA 

has taken to regulate sequestration. While it is great that we are talking about 

Commenter Name: Mary Munn Letter ID: 0273

Commenter Organization: Fond du Lac Reservation Comment ID: 24086

Commenter Name: Mary Munn Letter ID: 0273

Commenter Organization: Fond du Lac Reservation Comment ID: 24091

Commenter Name: Jonah Fruchter Letter ID: 0526

Commenter Organization: Sierra Club Comment ID: 21491

754
keeping water clean in Colorado, I do not understand why EPA is not taking a 

comprehensive approach to environmental regulation. We should be talking about 

how to regulate the capture, transfer, leakage problems, public health issues 

and water safety all in one package. I do not think it is helpful to draft 

environmental regulation in a piecemeal fashion. 

The environment does not function as separate pieces. It is interconnected. What 

affects the water, affects the land and what affects the land affects our air 

and so on and so forth. 

Furthermore it is cumbersome and inefficient to form regulatory policy in 

separate parts. I would not suggest you use piecemeal regulation for anything, I 

mean, including the environment. Environmental regulation should always reflect 

a comprehensive approach rather than the singular and isolated approach we are 

taking with only regulating water safety. 

Response: EPA clarifies that the Class VI GS regulation is being promulgated under authority of the 

Safe Drinking Water Act. The purpose of the Class VI GS rule is to ensure that where GS technologies 

are deployed, GS is performed in a manner that protects USDWs from endangerment. CO2 capture and 

transport are outside the scope of the Class VI GS rulemaking. 

EPA is using an adaptive approach to regulating Class VI wells. EPA plans, every six years, to collect 

and review data on Class VI projects to determine whether the appropriate amount and types of 

information and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. The adaptive approach may include solicitation of input and 

expertise from experts and stakeholders, similar to the consultations held to develop the current rule. 

Comment Code: 1310 1.1.2.4 Comments on other "out of scope" issues, e.g., pore space ownership 

Individual Comments 

Other EPA Comment Codes and Descriptions: 1210 1.1.1 Comments about the proposed rule 

Comment: We believe the following issues warrant additional review by the 

Environmental Protection Agency: 

1. The potential negative impact to large CO2 deep saline formation geologic 

sequestration projects resulting from the reference in these regulations to 

storage rather than disposal, implying the CO2 may have value or is even 

actually a commodity. Large projects could have a CO2 plume covering many square 

miles. The reference to storage may result in the operator having to rent or pay 

for the use of pore space for storage, which may involve dealing with numerous 

parties, considerable legal work and considerable costs. 

2. The potential adverse impact to Class I industrial waste disposal well 

Commenter Name: Michael H. Cochran Letter ID: 0108

Commenter Organization: Bureau of Water, Division of Environment, Kansas 

Department of Health & Environment (KDHE)

Comment ID: 

21942

755
program that could result from the concept of storage described in above item 

#1. 

Response: EPA acknowledges that issues such as pore space ownership and surface and subsurface 

property rights are important issues that need to be addressed; however, these are generally addressed 

though state regulations and are outside of the UIC program’s authority under the Safe Drinking Water 

Act (SDWA). EPA adds that the requirements apply to owners or operators of injection wells used to 

inject CO2 for permanent storage, and do not apply to owners or operators of Class I wells. 

EPA believes that developing a consistent regulatory framework will ensure that there is adequate 

opportunity for public involvement on the permitting process and that all USDWs are protected from 

endangerment. 

Other EPA Comment Codes and Descriptions: 1350 1.1.3.3 Comments on the need for GS 

technology; 3460 2.2.2.3 Acceptable corrective action techniques for GS sites (e.g., cements) 

Comment: For the past four years, our company has been field testing our 

proprietary systems and methods for utilizing a low melting point fusible metal 

alloy to mold in situ plugs in wells to repair gas leakage problems. Our focus 

has been on repair of vent gas flows that occur because of channels that exist 

within the cement surrounding production casing in wells. Our field tests have 

been carried out with permission of the Alberta Energy Resources Control Board 

("ERCB") and under their scrutiny. We presently have a proposal under 

consideration by the ERCB and the Canadian Association of Petroleum Producers 

(CAPP) to add our methods to the approved well abandonment protocols presently 

under review in Alberta. 

We believe our methods are directly applicable to the problem of long term 

leakage of sequestered GHG from wells that penetrate a reservoir used for the 

sequestration. Obviously, it makes neither economic nor environmental sense to 

capture, concentrate, compress, deliver, and inject CO2 into depleted reservoirs 

or saltwater formations if there is not a reliable sealing method used on 

existing wells in that reservoir to prevent the CO2 leaking back into the 

atmosphere. We believe that our plugging methods can assure long term success in 

preventing this leakage. 

We use an alloy of bismuth and tin for our sealing medium. This alloy is nontoxic and will not corrode or cause corrosion in the relevant well environment 

from either chemical or galvanic processes. We believe we can seal a well 

against gas flow even if the well casing has been entirely corroded away. The 

important properties of the alloy that cause it to be effective are: 

1) it expands about 1% by volume when solidifying from the liquid phase; 2) it 

is impermeable to gas flow; 3) it seals effectively in dirty oily casing; 4) it 

has a high specific gravity to facilitate displacement of other fluids present 

during the deployment process; and 5) it has a very low viscosity and surface 

tension such that it will enter small fissures, and absorb into and wet 

permeable rocks such as sandstone. 

Commenter Name: Homer Spencer Letter ID: 0120

Commenter Organization: Canitron Systems Inc. Comment ID: 22071

756
Only small amounts of the alloy are required to form a seal with the 

differential pressure strength required to seal GHG sequestration wells. We set 

the plugs using an electric heater deployed on a wire line. The procedure is 

both fast and inexpensive. We have data to back the above contentions, including 

corrosion tests carried out in a CO2/saltwater environment with a pH of 3 that 

indicate plug life in steel casing in excess of 10,000 years. 

Response: EPA thanks the commenters for the information on available well materials. EPA believes 

that the regulation affords owners or operators flexibility to use various materials and techniques to 

perform corrective action, provided they meet with the Director's approval. 

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

responsibility requirements (40 CFR 146.85) 

Comment: Proposed Financial Responsibility and Long-Term Care Requirements 

-There is no language in the proposed regulation that covers compensation to 

homeowners for the degradation or loss of a water supply. 

-EPA should consider how Class VI wells and associated GS projects could impact 

the ownership of mineral rights in formations that are penetrated en route to 

the CO2 storage reservoir. Some suggestions include a mechanism to require 

disclosure of mineral rights that may be impacted by a sequestration project and 

how such ownership issues will be resolved. 

-If phased corrective action (plugging of existing penetrations) is to be 

approved, then the operator must post a 100 percent performance bond with the 

permitting agency before the permit is issued. The performance bond is to be in 

the amount necessary for the permitting agency to immediately complete the 

corrective action should the owner/operator fail to timely do so. 

Response: EPA clarifies that the goal of the financial responsibility requirements is to ensure that 

financial resources are available to prevent endangerment of USDWs from improper plugging, 

remediation, and management of wells in the event that the owner or operator experiences financial 

difficulties. EPA would also like to highlight the emergency and remedial response plan required under 

the rule. This includes the cost to perform any necessary responses or remediation to address potential 

USDW endangerment. See the preamble to the final rule for more details on the emergency and 

remedial response requirements. 

EPA clarifies that pore space ownership and surface and subsurface property and mineral rights are 

outside the scope of the UIC GS rulemaking. EPA recognizes that many of these issues are the purview 

of the states and any of these issues as they relate to GS will need to be addressed though state 

regulations. The purpose of the Class VI GS rule is to ensure that where GS technologies are deployed, 

GS is performed in a manner that protects USDWs from endangerment. 

EPA agrees with the comment on phased corrective action. The GS rule, at §146.85(c), requires the 

owner or operator to have a detailed written estimate, in current dollars, of the cost of: performing 

corrective action on wells in the AoR, plugging the injection well(s), PISC and site closure, and 

emergency and remedial response. A cost estimate must be prepared separately for each of these 

Commenter Name: John Hanger Letter ID: 0130

Commenter Organization: Pennsylvania Dept. of Env. Protection Comment ID: 21514

757
activities and be based on the costs to the owner or operator of hiring a third party (who is neither a 

parent nor a subsidiary of the owner or operator) to perform the activities. EPA clarifies that owners or 

operators will need to demonstrate and maintain financial responsibility for all corrective action at the 

time of Class VI well permitting, before the onset of injection operations. See the final rule and 

preamble for further discussion of EPA's final approach to financial responsibility. 

Comment: Does this include any Carbon diooxide released from carbonated beverasges such 

as soda and beer? 

Response: EPA clarifies that the final Class VI GS rule final rule applies to owners or operators of wells 

that will be used to inject CO2 into the subsurface for the purpose of long-term storage. The purpose of 

the Class VI GS rule is to ensure consistency in permitting underground injection of CO2 at GS 

operations across the United States and provide requirements to prevent endangerment of USDWs in 

anticipation of the eventual use of GS to reduce CO2 emissions. 

Comment: E. Other Areas of Concern 

The proposed UIC regulations raise many other questions, creating additional 

uncertainty. These concerns include but are not limited to the following: 

- Economic liability related to selling carbon credits, and how it relates to this 

regulation. 

- Impact on underground coal mines, conflicts regarding mineral ownership, and 

possible mineral takings. 

- Development of geological horizons below the carbon sequestration horizon but in 

the same area. EPA should retain the flexibility currently available in the other UIC 

programs. EPA's Class VI program should not interfere with mineral extraction (oil 

and gas specifically) through the imposition of restrictions in CO2 storage fields. 

- Potential liability of landowner with CO2 storage area beneath the property. 

Response: The purpose of the Class VI GS rule is to ensure consistency in permitting underground 

injection of CO2 at GS operations across the US and prevent endangerment of USDWs in anticipation of

the eventual use of GS to reduce CO2 emissions. EPA clarifies that carbon crediting, mining, pore space 

ownership, and surface and subsurface property and mineral rights are outside the scope of the GS 

rulemaking. EPA clarifies that many of these issues are under the purview of states, and any of these 

issues as they relate to GS will need to be addressed though state regulations. 

However, the Agency acknowledges that these issues are important and is addressing them using other 

regulatory authorities. For example, in a separate rulemaking under authority of the Clean Air Act, EPA 

is amending the GHG Reporting Program at 40 CFR Part 98 to add reporting requirements for CO2 

injection and GS. The greenhouse gas reporting requirements build on the requirements outlined in the 

GS rule with the additional goals of verifying the amount of CO2 sequestered and collecting data on any 

CO2 emissions to the surface from GS facilities. 

With regard to whether CO2 is considered a commodity, EPA clarifies that the GS rule does not address 

Commenter Name: W.J. Curran Letter ID: 0137

Comment ID: 23077

Commenter Name: Robert Bessette Letter ID: 0139

Commenter Organization: Council of Industrial Boiler Owners (CIBO) Comment ID: 23088

758
the status of CO2 as a pollutant or commodity and that EPA regulates both pollutants and commodities 

under the UIC provisions. In addition, whether or not a fluid could be sold on the market as a 

commodity is outside the scope of EPA’s authority under the SDWA to protect USDWs. The Class VI 

GS rulemaking is promulgated under Safe Drinking Water Act authority and does not relate to any 

endangerment and cause or contribute findings under the Clean Air Act. The Class VI GS requirements 

do not depend upon, and are unaffected by, Clean Air Act endangerment and cause or contribute 

findings. 

The Agency clarifies that the final GS rule does not require owners or operators to use GS technologies, 

nor does it impact business as usual for Class II owners or operators that are injecting CO2 to enhance 

production of oil or gas. Owners or operators that choose to transition from EOR to GS may do so, 

provided they meet the requirements for Class VI wells. 

Regarding long-term liability, once an owner or operator has met all regulatory requirements under Part 

146 for Class VI wells and the Director has approved site closure pursuant to requirements at §146.93, 

the owner or operator will generally no longer be subject to enforcement for regulatory noncompliance. 

Furthermore, their financial instrument as required under §146.85 will be released if it was not used. 

However, even if a site closure is approved under §146.93, an owner or operator may be held liable for 

regulatory noncompliance (including violation of 40 CFR 144.12) in certain circumstances. For 

example, an owner or operator may be held liable for regulatory noncompliance even after site closure 

was approved if the Director relied on erroneous information (e.g., erroneous modeling data) provided 

by the owner or operator when approving site closure. 

Separate from EPA’s authority to enforce regulatory compliance, an owner or operator may be subject to 

a §1431 response order even after proper site closure is approved under §146.93. Under §1431 the 

Administrator may require an owner or operator to take necessary response measures if he or she 

receives information that a contaminant is present or is likely to enter a public water system or an 

USDW, which may present an imminent and substantial endangerment to the health of persons, and the 

appropriate State and local authorities have not acted to protect the health of such persons. The action 

may include issuing administrative orders or commencing a civil action for appropriate relief against the 

owner or operator of a Class VI well. If the owner or operator fails to comply with the order, they may 

be subject to a civil penalty for each day in which such violation occurs or failure to comply continues. 

Comment: UIC program and to develop a new Class VI for CO2GS well is appropriate. ODEC 

also appreciates EPA's recognition that while the new regulations at hand must 

be within the scope of the SDWA, there are a number ofvery important issues 

(such as long term liability) that are outside the scope of the act but are 

highly pertinent to developing a viable GS program and we are glad that EPA is 

willing to discuss these issues as part of this regulatory proposal. 

Response: EPA clarifies that the purpose of the Class VI GS rule is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

EPA recognizes the importance of providing clear, flexible, scalable, and appropriate regulations. EPA 

believes that the Class VI GS regulation will provide certainty to industry and the public by providing 

consistency in requirements across the U.S. and transparency about what requirements apply to owners 

or operators. 

Commenter Name: Kenneth Alexander Letter ID: 0146

Commenter Organization: Old Dominion Electric Cooperative (ODEC) Comment ID: 21707

759
EPA notes that long-term liability is outside of the scope of the GS rulemaking and is not addressed in 

the GS rule. SDWA does not contain any express provisions addressing liability. An owner or operator 

will be held liable for any permit violations under SDWA §1423. 

Under the final GS rule, once an owner or operator has met all regulatory requirements under Part 146 

for Class VI wells and the Director has approved site closure pursuant to requirements at §146.93, the 

owner or operator will generally no longer be subject to enforcement for regulatory noncompliance. 

Furthermore, their financial instrument as required under §146.85 will be released if it was not used. 

However, even if a site closure is approved under §146.93, an owner or operator may be held liable for 

regulatory noncompliance (including violation of 40 CFR 144.12) in certain circumstances. For 

example, an owner or operator may be held liable for regulatory noncompliance even after site closure 

was approved if the Director relied on erroneous information (e.g., erroneous modeling data) provided 

by the owner or operator when approving site closure. 

Separate from EPA’s authority to enforce regulatory compliance, an owner or operator may be subject to 

a §1431 response order even after proper site closure is approved under §146.93. Under §1431 the 

Administrator may require an owner or operator to take necessary response measures if he or she 

receives information that a contaminant is present or is likely to enter a public water system or an 

USDW, which may present an imminent and substantial endangerment to the health of persons, and the 

appropriate State and local authorities have not acted to protect the health of such persons. The action 

may include issuing administrative orders or commencing a civil action for appropriate relief against the 

owner or operator of a Class VI well. If the owner or operator fails to comply with the order, they may 

be subject to a civil penalty for each day in which such violation occurs or failure to comply continues. 

Furthermore, after site closure an owner or operator may remain liable under tort and other remedies, or 

under other federal statutes including, but not limited to, Clean Air Act, 42 U.S.C. §§ 7401-7671; 

CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. EPA does not have authority to 

transfer SDWA or other legal liability for Class VI wells to the State or federal government or a thirdparty fund. See the final rule preamble for further discussion of EPA's final approach to financial 

responsibility for Class VI wells. 

Comment: 3. CCS May impact Private Property Rights 

Recognizing that subsurface land can be privately owned in the United States, 

the chamber notes that CO2 injection into geologic formations may require 

permission from all owners of intersected subsurface property. While this 

consideration may be somewhat addressed during the initial siting process, it 

may still lead to tensions between large-scale CCS projects and individual 

property rights. The issue becomes even more important as investors and industry 

participants will seek to minimize liability from property trespass claims 

related to sub-surface trespass, geological surveying, and deposit monitoring. 

Likewise, property rights considerations may impact the availability of 

liability insurance for CCS project participants. If insurance companies cannot 

accurately calculate the risk of CCS projects, or future potential environmental 

liability for property trespass, they may decline to offer coverage. 

Response: EPA clarifies that pore space ownership and surface or subsurface property and mineral 

Commenter Name: William Kovacs Letter ID: 0148

Commenter Organization: U.S. Chamber of Commerce Comment ID: 21771

760
rights are outside of the scope of the Class VI GS rulemaking, which focuses on ensuring consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. EPA clarifies that these issues are under the purview of states and any of these issues, as 

they relate to GS, will need to be addressed though state regulations. Please see the final rule and 

preamble for additional information on financial responsibility for Class VI GS projects. 

Comment: appropriate injection site. Another huge issue which has yet to be broached by 

EPA is that of property and mineral rights ownership and encroachment. This was 

cause to slow progress on obtaining an injection permit in Michigan. The EPA 

Appeals Board ruled that issue was outside the scope of the UIC program but we 

anticipate this issue will resurface as more sites seek injection permits. 

Someone has to proactively address this difficult issue. With all these issues 

Response: EPA clarifies that pore space ownership and surface and subsurface property and mineral 

rights are outside of the scope of the Class VI GS rulemaking, which focuses on ensuring consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. EPA clarifies that these issues are under the purview of states and any of these issues, as 

they relate to GS, will need to be addressed though state regulations. Please see the final rule and 

preamble for additional information on financial responsibility for Class VI projects. 

Comment: PROPERTY AND MINERAL RIGHTS 

The Property Rights encroachment issue delayed the issuance of an injection 

permit for the MRCSP small scale injection project near Gaylord, Michigan. The 

permit was ultimately issued but the topic of property rights was never 

satisfactorily resolved. Fortunately the small quantity injected in this case 

did not present a property rights issue and the case did not go to litigation. 

Future larger CCS projects may not go forward in the absence of resolution of 

property rights-related issues. As EEI aptly points out: "Numerous property 

rights may be implicated by a given CCS project, including ownership interests 

in the surface property to be used for injection equipment, the subsurface 

property housing the injection well, the .pore space. in which CO2 will be 

stored, and water rights and mineral interests that may exist in the area. 

Currently, an entity interested in pursuing a CCS project is left to sort out 

who owns these various interests, an exercise that is a combination of 

applicable state law--to the extent any applicable state law exists--and sitespecific due diligence. This exercise is likely fraught with considerable 

uncertainty and expense and must be successfully completed in order for a 

project to begin." DTE Energy, along with EE, supports further exploration and 

discussion of these issues, and EPA’s efforts to solicit public views will serve 

to raise stakeholder and policy-maker awareness regarding the importance of 

their resolution to the successful commercial deployment of CCS. 

Commenter Name: Skiles Boyd Letter ID: 0160

Commenter Organization: DTE Energy Comment ID: 21268

Commenter Name: Skiles Boyd Letter ID: 0160

Commenter Organization: DTE Energy Comment ID: 21277

761
Response: As described above, EPA clarifies that pore space ownership and surface and subsurface 

property and mineral rights are outside of the scope of the Class VI GS rulemaking. EPA clarifies that 

these issues are under the purview of states and any of these issues, as they relate to GS, will need to be 

addressed though state regulations. 

Comment: is appropriate. San Miguel also appreciates EPA's recognition that while the new 

regulations at hand must be within the scope of the SDWA, there are a number of 

very important issues (such as long term liability) that are outside the scope 

of the act but are highly pertinent to developing a viable GS program and we are 

glad that EPA is willing to discuss these issues as part of this regulatory 

proposal. 

Response: EPA clarifies that the purpose of the Class VI GS rule is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

EPA recognizes the importance of providing clear, flexible, scalable, and appropriate regulations. EPA 

believes that the Class VI GS regulation will provide certainty to industry and the public by providing 

consistency in requirements across the U.S. and transparency about what requirements apply to owners 

or operators. 

EPA notes that long-term liability is outside of the scope of the GS rulemaking and is not addressed in 

the GS rule. SDWA does not contain any express provisions addressing liability. An owner or operator 

will be held liable for any permit violations under SDWA §1423. 

Under the final GS rule, once an owner or operator has met all regulatory requirements under Part 146 

for Class VI wells and the Director has approved site closure pursuant to requirements at §146.93, the 

owner or operator will generally no longer be subject to enforcement for regulatory noncompliance. 

Furthermore, their financial instrument as required under §146.85 will be released if it was not used. 

However, even if a site closure is approved under §146.93, an owner or operator may be held liable for 

regulatory noncompliance (including violation of 40 CFR 144.12) in certain circumstances. For 

example, an owner or operator may be held liable for regulatory noncompliance even after site closure 

was approved if the Director relied on erroneous information (e.g., erroneous modeling data) provided 

by the owner or operator when approving site closure. 

Separate from EPA’s authority to enforce regulatory compliance, an owner or operator may be subject to 

a §1431 response order even after proper site closure is approved under §146.93. Under §1431 the 

Administrator may require an owner or operator to take necessary response measures if he or she 

receives information that a contaminant is present or is likely to enter a public water system or an 

USDW, which may present an imminent and substantial endangerment to the health of persons, and the 

appropriate State and local authorities have not acted to protect the health of such persons. The action 

may include issuing administrative orders or commencing a civil action for appropriate relief against the 

owner or operator of a Class VI well. If the owner or operator fails to comply with the order, they may 

be subject to a civil penalty for each day in which such violation occurs or failure to comply continues. 

Furthermore, after site closure an owner or operator may remain liable under tort and other remedies, or 

under other federal statutes including, but not limited to, Clean Air Act, 42 U.S.C. §§ 7401-7671; 

CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. EPA does not have authority to 

transfer SDWA or other legal liability for Class VI wells to the State or federal government or a thirdCommenter Name: Joseph Eutizi Letter ID: 0161

Commenter Organization: San Miguel Electric Cooperative, Inc Comment ID: 21281

762
party fund. See the final rule preamble for further discussion of EPA's final approach to financial 

responsibility for Class VI wells. 

Comment: NRECA also appreciates EPA's recognition that while the new regulations at hand 

must be within the scope of the SDWA, there are a number of very important 

issues (such as long term liability) that are outside the scope of the act but 

are highly pertinent to developing a viable GS program and we are glad that EPA 

is willing to discuss these issues as part of this regulatory proposal. 

Response: EPA clarifies that the purpose of the Class VI GS rule is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

EPA recognizes the importance of providing clear, flexible, scalable, and appropriate regulations. EPA 

believes that the Class VI GS regulation will provide certainty to industry and the public by providing 

consistency in requirements across the U.S. and transparency about what requirements apply to owners 

or operators. 

EPA notes that long-term liability is outside of the scope of the GS rulemaking and is not addressed in 

the GS rule. SDWA does not contain any express provisions addressing liability. An owner or operator 

will be held liable for any permit violations under SDWA §1423. 

Under the final GS rule, once an owner or operator has met all regulatory requirements under Part 146 

for Class VI wells and the Director has approved site closure pursuant to requirements at §146.93, the 

owner or operator will generally no longer be subject to enforcement for regulatory noncompliance. 

Furthermore, their financial instrument as required under §146.85 will be released if it was not used. 

However, even if a site closure is approved under §146.93, an owner or operator may be held liable for 

regulatory noncompliance (including violation of 40 CFR 144.12) in certain circumstances. For 

example, an owner or operator may be held liable for regulatory noncompliance even after site closure 

was approved if the Director relied on erroneous information (e.g., erroneous modeling data) provided 

by the owner or operator when approving site closure. 

Separate from EPA’s authority to enforce regulatory compliance, an owner or operator may be subject to 

a §1431 response order even after proper site closure is approved under §146.93. Under §1431 the 

Administrator may require an owner or operator to take necessary response measures if he or she 

receives information that a contaminant is present or is likely to enter a public water system or an 

USDW, which may present an imminent and substantial endangerment to the health of persons, and the 

appropriate State and local authorities have not acted to protect the health of such persons. The action 

may include issuing administrative orders or commencing a civil action for appropriate relief against the 

owner or operator of a Class VI well. If the owner or operator fails to comply with the order, they may 

be subject to a civil penalty for each day in which such violation occurs or failure to comply continues. 

Furthermore, after site closure an owner or operator may remain liable under tort and other remedies, or 

under other federal statutes including, but not limited to, Clean Air Act, 42 U.S.C. §§ 7401-7671; 

CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. EPA does not have authority to 

transfer SDWA or other legal liability for Class VI wells to the State or federal government or a thirdparty fund. See the final rule preamble for further discussion of EPA's final approach to financial 

responsibility for Class VI wells. 

Commenter Name: James Stine Letter ID: 0163

Commenter Organization: National Rural Electric Cooperative Association 

(NRECA)

Comment ID: 

21310

763
Comment: allowed by the director if he so chooses. However, APPA believes that the 

operation of the power plant should not be stopped if the geologic storage or 

sequestration is deemed ill advised by the state director (or court). Only the 

CO2 injection in that location should cease. Instead the owner/operator of that 

power plant should be allowed to continue operations for the purpose of 

generating electricity (and other functions) without CO2 injection until either 

a different technique is developed or until infrastructure can be built to move 

the CO2 to a different injection location. In some cases, the power plant 

owner/operator will simply have to make commercial or contractual arrangements 

to pay a party to take the CO2 for injection or geoengineering mitigation 

measures (not yet identified). 

Response: The UIC program’s authority under the SDWA focuses on ensuring that Class VI GS 

projects are permitted, sited, constructed, operated, monitored, and closed in a manner that protects 

USDWs from endangerment. EPA clarifies that the Class VI GS regulation applies to owners or 

operators of wells that will be used to inject CO2 into the subsurface for the purpose of long-term 

storage and does not require any facilities to capture and/or sequester CO2 and that permitting of power 

plants is outside the scope of the Class VI GS rulemaking. 

Comment: In addition, the GAO report discusses the complex and still unresolved property 

rights issues involving CO2 injection on both federal and nonfederal lands. Id. 

at 42-23. Finally, GAO cites a National Academy of Sciences ("NAS") report 

Response: EPA clarifies that pore space ownership and surface and subsurface property and mineral 

rights are outside of the scope of the Class VI GS rulemaking. Rather, the purpose of the Class VI GS 

rule is to ensure that where GS technologies are deployed, GS is performed in a manner that protects 

USDWs from endangerment. EPA clarifies that these issues are under the purview of states and any of 

these issues, as they relate to GS, will need to be addressed though state regulations. 

Comment: USWAG also urges EPA to issue more definitive direction in the Final Rule 

regarding the regulation of CO2 injection activities that cross state 

boundaries. This issue is mentioned in the Preamble to the Proposal but receives 

little attention. See 73 Fed. Reg. at 43497. Rather, EPA simply observes that 

"some injection activities may raise cross-state boundary issues that are beyond 

the scope of this rulemaking." Id. EPA should provide more direction regarding 

how such cross-state activities would be regulated, and specifically should make 

clear in the Final Rule that Owners or Operators of Class VI CO2 GS projects 

will seek a Class VI permit for that operation from the state in which the 

wellhead is located. In other words, a given state is the permitting body for 

any Class VI CO2 GS project with a wellhead in that state. EPA should direct 

states to consult and coordinate with other affected states (i.e., other states 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23400

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23470

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23476

764
to which the underground portion of the well may extend and/or those to which 

there could be a subsurface release or migration of injected material) in 

determining how to avoid duplicative or dueling regulatory systems. USWAG urges 

EPA to play a leadership role and proactively address these issues by suggesting 

procedural guidelines for interstate regulation and cooperation. 

Response: EPA acknowledges that CO2 plumes may cross state or even international boundaries and 

encourages cooperation and coordination among permitting authorities. The final Class VI GS rule, at 

§146.82(a)(2), requires the owner or operator to identify all State, Tribal, and territorial boundaries 

within the AoR. Based on this information, the Director must provide written notification to all States, 

Tribes, and Territories to inform them of the permit application and ensure that they are involved in any 

necessary processes; this new requirement was added to the final rule at §146.82(b). The Agency 

encourages transparency in the permitting process and anticipates that State-State/State-Tribal 

communication on Class VI GS permitting will facilitate information sharing and encourage safe, 

protective projects. 

EPA clarifies that the Class VI permit would be issued by the permitting authority in the state where the 

wellhead is located. 

Comment: c. Impact of GS well siting on Underground Natural Gas Storage 

As a general matter, EPA should ensure that Class VI permits not inappropriately 

interfere with other pre-existing subsurface interests and operations. 

Dominion's interest in the rulemaking is from the perspective of both an 

owner/operator/contractor of CCS and a potentially affected party as an operator 

of an extensive network of underground natural gas storage. The sole 

responsibility of the UIC Program is to provide protections for existing and 

future USDW. Little protections are afforded for other underground resources, 

however. The rulemaking unambiguously leaves these concerns to the individual 

states, irrespective of primacy status. The rulemaking's silence with regard to 

protections for underground natural gas storage formations is cause for concern 

to the natural gas industry. 

Gas storage operators have particular expertise regarding their natural gas 

storage fields, and can help prevent problems if EPA helps to ensure their 

participation in the process of the site evaluation and construction of GS wells 

in natural gas storage fields. The Agency should authorize the Director to 

ensure the coordination between natural gas storage operators and GS well 

owners/operators in circumstances where the GS construction will occur in 

natural gas storage fields. Such coordination can involve, for example, 

obtaining input from the natural gas storage operators on the unique 

circumstances associated with the natural gas storage field where the GS well 

will be constructed. To assist in this process, natural gas storage field 

operators should have ready access to GS well records, well logs and cementing 

records for any GS construction activity that occurs in a natural gas storage 

field. 

EPA should authorize Directors to ensure coordination between natural 

Commenter Name: Pamela Faggert Letter ID: 0175

Commenter Organization: Dominion Comment ID: 23521

765
gas storage operators and GS well owners/operators in circumstances 

where the GS construction will occur in natural gas storage fields. 

Response: EPA clarifies that pore space ownership and surface and subsurface property and mineral 

rights are outside of the scope of the Class VI GS rulemaking. EPA clarifies that these issues are under 

the purview of states and any of these issues, as they relate to GS, will need to be addressed though state 

regulations. The Class VI GS rule is designed to ensure protection of USDWs from endangerment 

through proper permitting, siting, well construction, operation, monitoring, and closure of Class VI GS 

projects. 

As part of the permit application process, prospective operators of Class VI GS wells must submit data 

on other activities subject to environmental permitting (e.g., oil or gas fields), mines, and a tabulation of 

all wells in the area of review. This information, including data on any other injection or production 

activities in the area would be taken into consideration by the Director in evaluating the appropriateness 

and safety of the proposed site. 

Comment: 8. Other Issues Outside the Scope of the Rulemaking 

An area of concern to the gas storage industry is the expansion of the UIC 

program. To date, the injection of hydrocarbons for purposes of storage has been 

excluded from federal regulation under the UIC program. If EPA sees fit to 

establish a new category of well for the purpose of injecting CO2 for storage, 

it should be made clear that this program will not affect storage of natural 

gas. This concern is more pronounced as the industry expands its use of CO2 as a 

base gas for underground storage of natural gas. 

The establishment of a new class of well for geologic sequestration of 

CO2 should not include expanding the UIC program generally to 

incorporate underground natural gas storage. 

Response: EPA clarifies that the Class VI GS requirements apply only to wells that are injecting CO2 

into the subsurface for the purpose of GS, and not to natural gas storage operations. EPA clarifies that 

developing specific requirements for natural gas storage operations is out of the scope of the UIC 

program's authority. However, EPA notes that the final rule requires Class VI permit applicants to 

submit maps and tabulations of wells, including injection wells (which could be used for ER or natural 

gas storage), in the AoR for review by the UIC program Director. In addition, the rule requires the 

Director to notify the state oil and gas agency and state mineral exploration and recovery agency as part 

of the public notification required for a draft permit (§ 124.10(c)(1)(xi)). EPA expects that these 

agencies will inform the Director of any existing natural gas storage facilities around the proposed Class 

VI GS site and that the Director will take this information and the data on wells in the AoR into 

consideration when deciding whether to grant a permit for the Class VI well. 

Other EPA Comment Codes and Descriptions: 2100 1.6 Target Geologic Formations for GS; 3100 

2.1 Proposed Geologic Siting Requirements (40 CFR 146.83); 3120 2.1.2 Need to identify additional 

confining and containment zones (seeking comment) 

Commenter Name: Pamela Faggert Letter ID: 0175

Commenter Organization: Dominion Comment ID: 23533

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23551

766
Comment: 

EEI agrees that proper site selection is critical to a successful GS project and 

notes that it serves to minimize, if not eliminate, any potential threats to 

drinking water sources that CO2 injection and storage may pose. However, 

several of the proposed requirements are unnecessary from the perspective of 

protecting drinking water sources and would only serve to hamper GS projects 

from going forward, including limitations on receiving formations, potential 

alteration to the current definition of an underground source of drinking water 

(USDW), and the proposed grant of discretion to the UIC program director to 

require permit applicants to identify secondary containment/confining zones. 

Response: EPA retains the requirement to identify additional containment/confining zones, if required 

by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be 

needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on 

his or her understanding of a particular site. EPA believes that, in some situations, the presence of 

additional confining and containment zones above the primary (i.e., lowermost) confining zone can 

improve USDW protection. These layers could further impede vertical fluid movement and allow for 

pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The 

Agency's decision is supported by commenters representing states, water associations, and an electric 

utility who assert that these requirements promote a flexible, risk-based, site-specific approach to 

characterizing and permitting a site for GS projects, and are intended to improve understanding of the 

project as a whole and promote better modeling of the site. 

EPA believes that the Class VI requirements, including the level of site characterization required under 

§§146.82 and 146.83, appropriately address the unique challenges posed by large-scale GS including 

large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the 

potential presence of impurities in captured CO2, and its mobility within subsurface geologic 

formations. 

EPA disagrees with the commenter that the GS rule requirements are unnecessary to protect USDWs. 

The GS final rule builds upon longstanding programmatic requirements for underground injection that 

have been in place since the 1980s and that are used to manage over 800,000 injection wells nationwide. 

These programmatic requirements are designed to prevent fluid movement into USDWs by addressing 

the potential pathways through which injected fluids can migrate into USDWs. EPA coordinated with 

Federal and non- Federal entities on GS and CCS to determine how best to tailor existing injection 

requirements to CO2 for GS. 

Additionally, EPA clarifies that the GS rule does not categorically preclude injection of CO2 into any 

non-USDW formation types. The purpose of the GS rule is to ensure protection of USDWs from 

endangerment, and the rule requires that owners or operators demonstrate that wells are sited in suitable 

systems with geologic formations to receive and confine injected CO2, required at §146.83 of the GS 

rule. The Class VI siting, well construction and operation, monitoring and testing, and post-injection site 

care and site closure requirements are designed to ensure that injected CO2 remains within the target 

formation. If an owner or operator can demonstrate to the Director's satisfaction that GS in coal seams, 

basalts, salt domes, or shales can be accomplished in a manner that protects USDWs and meets all of the 

requirements of the GS rule, the project may be permitted as a Class VI well. 

Comment: Further, although EEI appreciates that issues related to property rights and 

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23575

767
pore space ownership that may be associated with injection and storage are 

outside the scope of the Agency‘s rulemaking, comments are provided on these 

issues as well, at the Agency‘s request. 

Response: EPA clarifies that pore space ownership and surface and subsurface property and mineral 

rights are outside of the scope of the Class VI GS rulemaking, which focuses on ensuring consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. EPA clarifies that these issues are under the purview of states and any of these issues, as 

they relate to GS, will need to be addressed though state regulations. 

Comment: K. Issues Related to Potentially Implicated Property Rights 

Finally, although EEI recognizes the limits on EPA‘s jurisdiction regarding CCS 

projects, our members appreciate the Agency raising for public comment issues 

related to property rights that may be associated with CO2 injection and 

storage. While the importance of EPA‘s rulemaking as an important step in 

providing clarity, flexibility and certainty for project operators and investors 

cannot be overstated, CCS projects may not go forward in the absence of 

resolution of property rights-related issues. 

Numerous property rights may be implicated by a given CCS project, including 

ownership interests in the surface property to be used for injection equipment, 

the subsurface property housing the injection well, the "pore space" in which 

CO2 will be stored, and water rights and mineral interests that may exist in the 

area. Currently, an entity interested in pursuing a CCS project is left to sort 

out who owns these various interests, an exercise that is a combination of 

applicable state law--to the extent any applicable state law exists--and sitespecific due diligence.[FN15] This exercise is likely fraught with considerable 

uncertainty and expense and must be successfully completed in order for a 

project to begin. Commercial deployment of CCS technology may be advanced 

considerably through legal mechanisms at the state and federal levels that 

assist potential permittees in working through property rights-related issues. 

Available mechanisms may range from laws that clarify presumptions related to 

ownership of various implicated interests [FN16] to provisions allowing for use of 

eminent domain authority to obtain such interests. EEI supports further 

exploration and discussion of these issues, and EPA‘s efforts to solicit public 

views will serve to raise stakeholder and policy-maker awareness regarding the 

importance of their resolution to the successful commercial deployment of CCS. 

[FN15] The proposed regulations would also require the permittee to record a 

notice on the deed (or other relevant document) to the "facility property" 

containing certain information. While EEI is not opposed to the concept of a 

deed notice, more clarity is needed in the regulations regarding how "facility 

property" is to be defined in order to better understand the scope of the 

proposed requirement. EEI recommends limiting "facility property" to the area 

immediately surrounding the injection well. 

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23608

768
[FN16] See Wyoming‘s House Bill 89, 

http://legisweb.state.wy.us/2008/Enroll/HB0089.pdf, which became law in July 

2008. 

Response: As described above, EPA clarifies that pore space ownership and surface and subsurface 

property and mineral rights are outside of the scope of the Class VI GS rulemaking, which focuses on 

ensuring consistency in permitting underground injection of CO2 at GS operations across the United 

States and provide requirements to prevent endangerment of USDWs in anticipation of the eventual use 

of GS to reduce CO2 emissions. 

EPA recognizes the importance of providing clear, flexible, scalable, and appropriate regulations. EPA 

believes that the Class VI GS regulation will provide certainty to industry and the public by providing 

consistency in requirements across the U.S. and transparency about what requirements apply to owners 

or operators. 

Other EPA Comment Codes and Descriptions: 1300 1.1.2.3 Comments on other aspects of CCS 

(capture, transport); 1400 1.2 Comments on EPA's Authority to Regulate Injection of CO2 

Comment: XII. RELATED ISSUES, NOT RAISED IN THE PROPOSED RULE, THAT REQUIRE 

RESOLUTION 

The SDWA does not provide EPA authority to develop regulations for many 

important areas related to the geological sequestration of CO2. Thus the draft 

rule cannot address all of the potential impediments to CCS development. Even if 

EPA were to promulgate a final UIC rule that encourages development of these 

critical technologies, there are other key factors that would need to be 

properly addressed before major investment in these technologies can be 

expected. 

The following sets forth key issues that will not be resolved through this 

rulemaking but are linked inextricably to the successful development and 

implementation of CCS technology. 

A. EMINENT DOMAIN AUTHORITY TO FACILITATE PIPELINE CONSTRUCTION 

Energy facilities for the public convenience and necessity, such as electric 

transmission facilities and natural gas pipelines, are able to make use of state 

or federal eminent domain authority to ensure that private landowners cannot 

block a project necessary for the public good. Eminent domain authority should 

be available for CO2 pipelines for CCS when it is necessary to cross private 

property. A substantial CO2 pipeline network may be required for the transport 

of CO2 from sites where it is produced to an injection site. CO2 pipelines for 

CCS clearly should be considered to be used for the public convenience and 

necessity. 

B. DETERMINATION OF SUB-SURFACE PROPERTY RIGHTS 

The government must address the ability to gain sufficient property rights to 

deep saline formations to conduct geologic sequestration. State property

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23877

769
ownership regimes vary, but surface owners typically are considered to own 

property below the surface to the center of the earth. Safe sequestration of CO2 

will not have any effect on the surface, but GS injections will result in 

underground plumes that may stretch across many square miles under the property 

of multiple surface property owners. Property ownership issues have been 

resolved successfully in the context of EOR, but it should not be assumed that 

the same will be true for GS. Eminent domain authority should be available to 

obtain rights to subsurface storage space for geologic sequestration because of 

its public benefit. 

C. RESOLUTION OF SURFACE LIABILITY ISSUES 

Though this Proposed Rule is limited in its scope to underground injection of 

CO2 and the potential risks and resulting liabilities, issues regarding risks 

and liability at the surface must be addressed for CCS technology to fully 

develop. These include liability for major and sudden releases, seismic activity 

and ground heave, as well as liability under any GHG emission control regime 

when sequestered CO2, for the storage of which credits or offsets have been 

granted, is subsequently released into the upper atmosphere. 

Response: EPA acknowledges that the issue of GS falls within the broader context of CCS. EPA 

received a number of comments indicating that the Agency should further explore environmental and 

regulatory issues beyond the scope of the GS rule as proposed. This comment is outside the scope of this 

rulemaking. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

EPA recognizes that liability is an important issue to owners or operators but the Agency does not have 

authority under the SDWA to transfer long term liability from owners or operators to the state or federal 

government. Therefore, liability remains with the owner or operator. 

Other EPA Comment Codes and Descriptions: 1610 1.3.1 Risks to USDWs 

Comment: Assignment of Liability: Most importantly, the regulation does not seem to 

address the liability that would be realized by owners/operators of the geologic 

sequestration projects if water quality of USDWs is degraded by the operation of 

their project (even if the impacts are limited to MCLs). AWWA recommends that 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23664

770
this issue be addressed in the final regulation, as drinking water utilities may 

have little financial recourse if the water quality one of their aquifers is 

degraded due to the operation of a geologic sequestration process. Provisions 

need to be included in the final rule that would allow the drinking water 

utility to recoup any costs that are realized due to increased treatment 

requirements for contaminated ground water or to replace lost capacity. In some 

cases, utilities may need to install different types of treatment to remove 

compounds that might not have been present in the water prior to the geologic 

sequestration project. In other instances, treatment may consist of the addition 

of more chemicals to facilitate precipitation of the inorganic compounds or the 

utility may have to backwash membranes more often, resulting in higher energy 

and other operation and maintenance costs. In any of these cases, the 

owner/operator of the geologic sequestration project should be required to 

reimburse the drinking water utility for these incurred costs, and they should 

also be required to continue such payments for as long as the ground water 

source remains degraded. 

Water utilities should not be penalized for having to develop local sites 

contaminated by sequestration activities for water supply. In fact they should 

be encouraged to do so, under the appropriate conditions, as there is no more 

critical public health issue than the need to provide potable water. In order to 

meet increasing demands imposed on them by a growing service population, water 

utilities will need to develop marginal water supplies. However, increased 

treatment costs due to contamination resulting from sequestration activities 

should not be borne by the local utility or their customers when national 

environmental objectives have been met without significant benefit to the local 

economy. 

Should a water utility "lose" an existing or future source of supply due to 

contamination or inaccessibility resulting from a sequestration project, there 

will be the issue of financial compensation (for treatment or development of an 

alternative source). As water resources become scarce, financial compensation 

for a lost source of supply may not suffice, as local alternatives may not be 

available. Hence, it will be critical that contingency planning to identify 

alternatives to the current groundwater supply be a part of the planning 

activities for the sequestration project, along with a commitment to provide an 

alternative source of water, should the need arise. 

Response: EPA agrees that owners or operators of Class VI wells must ensure that resources are 

available to prevent endangerment of USDWs from improper plugging, remediation, and management 

of wells. For this reason, the GS rule requires that owners or operators demonstrate and maintain 

financial responsibility for corrective action on wells in the AoR, injection well plugging, post-injection 

site care and site closure, and emergency and remedial response at GS sites as specified in §146.85. In 

the event of contamination or other adverse event to the USDW during the life of the project, the 

financial instrument(s), such as insurance, bonds, etc., rather than public monies, would cover necessary 

response actions. EPA clarifies that it is the owner or operator of the well who will be required to 

demonstrate financial responsibility, not the generator of the CO2, consistent with EPA’s authority 

under SDWA. Furthermore, EPA notes that tort and other remedies will continue to be available after 

site closure. Other Federal environmental statutes, e.g. Clean Air Act, 42 U.S.C. §§7401-7671; 

CERCLA, 42 U.S.C. §9601-9675; and RCRA, 42 U.S.C. §6901-6992, potentially apply as well to the 

risks created by the long-term storage of CO2. EPA has also examined potential methods for conducting 

771
treatment of water affected by a CO2 leak; this study is presented in the final rulemaking docket.

EPA clarifies that long-term liability beyond the life of the project (after site closure) is beyond the 

scope of the GS rulemaking. Please see the final rule and the discussion of financial responsibility and 

long-term liability in the preamble for additional information. 

EPA adds that Class VI well owners and operators must site, construct, operate, monitor, and close their 

wells in a manner that protects USDWs, and Class VI permits will set forth rigorous technical 

requirements to ensure careful planning, operation, and closure of GS projects. Failure to meet these 

requirements would be considered a violation of the permit and would be subject to applicable civil, 

criminal, or administrative penalties under SDWA §1423. 

Comment: AWWA also recommends that the company generating the carbon dioxide must 

maintain sole ownership of the carbon dioxide they generate. This would ensure 

that liability remains with the original generator in perpetuity; even if the 

carbon dioxide is commingled with some generated from another facility or if its 

disposal is managed by another company. 

Response: EPA clarifies that the final Class VI GS rule applies to owners or operators of wells that will 

be used to inject CO2 into the subsurface for the purpose of long-term storage, and not the generator of 

the CO2. Any issues related to "ownership" of generated CO2 are outside the scope of the Class VI GS 

rulemaking. Rather, the purpose of the Class VI GS rule is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Comment: Project Security: AWWA recommends that EPA work with the Department of 

Transportation and the Department of Homeland Security to ensure the safety and 

security of geologic sequestration projects. We have concerns about the 

unintentional or intentional release of stored carbon dioxide and the related 

control and monitoring systems required, as well as security measures. A 

requirement for strict monitoring systems during project construction and 

operation is necessary to ensure that the project is not intentionally 

sabotaged, as this could result in a massive leak of carbon dioxide out of the 

confinement zone and into the environment. EPA should mandate strict monitoring 

systems be included as part of any geologic sequestration project, not only to 

ensure the safety of USDWs, but also the safety of those living in the footprint 

of the project. 

Response: EPA clarifies that pipelines and CO2 transport are outside the scope of the Class VI GS 

rulemaking. The Class VI GS regulation is being promulgated under authority of the Safe Drinking 

Water Act. The purpose of the Class VI GS rule is to ensure consistency in permitting underground 

injection of CO2 at GS operations across the United States and provide requirements to prevent 

endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Regarding the comment on ensuring the safety and security of GS projects related to unintentional or 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23665

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23674

772
intentional release of stored CO2, EPA clarifies that the purpose of the Class VI GS rule is to ensure that 

where GS technologies are deployed, GS is performed in a manner that protects USDWs from 

endangerment. EPA agrees that testing and monitoring are important aspects of ensuring USDW 

protection, and the Class VI GS rule requires that owners or operators develop and implement a testing 

and monitoring plan. See the final rule and preamble discussion of testing and monitoring requirements 

for additional information. 

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial 

responsibility requirements (40 CFR 146.85) 

Comment: Category: Financial 

EPA Request for Comment: Because of the possibility that the owner or operator 

may face financial distress prior to the trust being fully funded, EPA is 

considering a guidance approach that would recommend adopting a pay in period of 

three years for GS projects, consistent with other similar programs in the 

Agency. EPA Notice 43521. 

EPA is assessing whether to provide guidance on the use of insurance providers 

and, if so, whether to update eligibility requirements for insurers for GS wells 

consistent with other current Federal agency practices. EPA Notice 43521. 

EPA is requesting comments on whether financial responsibility mechanisms to be 

recommended in EPA guidance should be adjusted in the manner described, whether 

additional instruments should be included, and whether other adjustments to the 

financial responsibility mechanisms should be considered, all subject to EPA’s 

authority under the SDWA. EPA Notice 43522. 

AWWA Response: AWWA has several major concerns regarding owner/operator 

financial assurance and liability. Our primary concern is that the liability 

mechanism that would be triggered when the confining zone fails and carbon 

dioxide escapes has not been identified. Would this incident trigger CERCLA 

requirements if groundwater is degraded? AWWA recommends that the liability 

requirements and financial mechanisms that were used to address MTBE 

contamination be applied to any USDW degradation from carbon sequestration 

activities. The definition of a "corrective action" does not provide any 

protection for aquifers that are contaminated by the carbon sequestration 

process. The definition as provided in the proposed rule states that corrective 

action is "...the use of Director approved methods to assure that wells within 

the area of review do not serve as conduits for the movement of fluids into 

underground sources of drinking water (USDW)." Note that this definition does 

not address "fixing" the impact to USDW. What is unclear to AWWA is if the 

geologic sequestration process does endanger groundwater aquifers, whether the 

owners/operators have any financial liability in restoring water quality (e.g., 

paying for extra treatment costs incurred by water utilities or other 

groundwater users), as the corrective action seems to focus on fixing injection 

wells and/or the confining layer. 

The question remains regarding what an owner/operator’s total liability would be 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23707

773
outside of the USDW contamination. The potential exists for contamination of 

other ground water aquifers, such as those that are not classified as USDWs but 

are used as a drinking water sources, and it is extremely important that the 

liability requirements are extended to these aquifers. The cost to remediate any 

degradation can be extremely high. Depending on the scope and location of the 

degradation, examples of potential costs that might be incurred by a drinking 

water utility include the installation of advanced water treatment technologies 

and/or development of alternative water sources. The responsibility for these 

costs must be assumed by the owner/operator in the event of a failure of the 

geologic sequestration process. 

AWWA believes that the time limit for financial responsibility in the proposed 

regulation may be too long for most insurance agencies, which may trigger the 

need for the development of a trust fund or for owner/operators to use a selfinsurance mechanism. If the trust fund is the desired method, EPA should require 

that companies constantly add to the fund, even if it appears that the fund is 

fully funded. In addition to the initial pay in period of three years, 

owner/operators should be required to pay in any additional amount identified 

during the five-year reviews for the area of review and corrective action plan, 

injection well plugging plan, the post-injection site care and site closure 

plan, and the emergency and remedial response plan. This additional pay in is 

required so that we don't have a repeat of the funding stoppage with the 

Superfund program. 

Response: The goal of financial responsibility is to ensure that financial resources are available to 

prevent endangerment of USDWs from improper plugging, remediation, and management of wells in 

the event that the owner or operator experiences financial difficulties. As such, owners or operators must 

demonstrate financial responsibility for, among other things, any needed emergency and remedial 

response actions that are necessary to mitigate endangerment or potential endangerment of USDWs. See 

the final rule and preamble for further discussion of EPA's final approach to financial responsibility. 

EPA clarifies that, while the commenter accurately defines corrective action for wells in the AoR, this 

term does not refer to actions needed to address endangerment in the UIC program regulations. EPA 

clarifies that the intent of the emergency and remedial response requirements at §146.94 is that if the 

owner or operator obtains any evidence that USDWs may be endangered, he or she must cease injection, 

take all steps reasonably necessary to identify and characterize any release, notify the Director, and 

implement the approved emergency and remedial response plan, per §146.94(b). 

EPA disagrees that GS is analogous to the MTBE situation. EPA believes that large scale GS can be 

done safely. The GS regulation builds upon the long-standing, protective regulatory framework of the 

UIC program, which has been regulating the injection of fluids for decades. The GS regulation enhances 

this existing framework with tailored requirements for Class VI GS wells to address the unique nature of 

large scale GS of CO2. These protective requirements include extensive geologic testing, detailed 

computational modeling of the AoR and periodic re-evaluations, detailed requirements for monitoring 

and tracking the CO2 plume and pressure front, and extended post-injection monitoring and site care. 

Comment: II. Ensuring the Long-Term Containment of CO2 at Sequestration Sites 

Commenter Name: Wendy Jacobs Letter ID: 0183

Commenter Organization: Harvard Law School Environmental Law and Policy 

Center

Comment ID: 

25142

774
A. EPA Should Require Owners or Operators to Demonstrate that CO2 Will Be 

Contained for the Long-Term 

The purpose of GS is to store anthropogenic CO2 for the "long term." See 73 

Fed. Reg. at 43,535 (proposed 40 C.F.R. § 146.81) (defining "geologic 

sequestration" as the "long-term containment of a gaseous, liquid or 

supercritical carbon dioxide stream in subsurface geologic formations"). If-but 

only if-the sequestered CO2 is contained (i.e., not allowed to escape into the 

atmosphere) for a sufficiently long period of time will CCS fulfill its 

potential to be "a key mitigation technology for achieving domestic emissions 

reductions" and "help to mitigate climate change." 73 Fed. Reg. at 43,492, 

43,496. As drafted, however, the proposed regulation fails to tackle the 

question of how long is "long term." 

EPA should provide a sense of the time scales involved and require 

owners/operators to make a reasonable demonstration that the injected CO2 will 

not migrate in such a way that will frustrate the broader climate change related 

goals of GS, lead to human endangerment, or threaten USDWs. 

Despite the fact that long-term containment is critical to the success of a 

climate change mitigation program and to satisfy the public protection mandate 

of the SDWA, EPA’s proposed GS regulation fails to require permit applicants to 

demonstrate that long-term containment will be achieved and maintained. In this 

respect, the proposed rule is less stringent than the requirements for Class I 

hazardous waste injection wells, which require the permit applicant to show to a 

reasonable degree of certainty that no hazardous materials will migrate from the 

injection zone for 10,000 years.[FN3] 40 C.F.R. § 148.20(a)(1)(i). The differences 

between hazardous waste and CO2 suggest that a 10,000 year demonstration may be too 

stringent for GS within Class VI wells, but the existence of a 10,000 year 

demonstration standard for Class I wells confirms that EPA can reasonably impose 

and administer a reasonable demonstration standard for Class VI wells. 

[FN3] In the alternative, the owner or operator may demonstrate that, "[b]efore the 

injected fluids migrate out of the injection zone or to a point of discharge or 

interface with USDW, the fluid will no longer be hazardous because of 

attenuation, transformation, or immobilization of hazardous constituents within 

the injection zone by hydrolysis, chemical interactions or other means . . . ." 

40 C.F.R. §148.20(a)(1)(ii). 

In its regulations for GS of CO2, Washington State requires GS permit applicants 

to demonstrate to a high degree of confidence that "substantially ninety-nine 

percent of the greenhouse gases will remain contained for at least one thousand

years." Wash. Admin. Code §§ 173-218-115(4)(a)(i)(A), 173-407-110 (2008). 

Though Washington’s one thousand year requirement seems consistent with the 

timescales imagined in EPA’s preamble, see 73 Fed. Reg. at 43,496 (total GS 

capacity is expressed as the ability to sequester CO2 emissions for "hundreds, 

if not thousands" of years), no comparable requirement is imposed on a permit 

applicant under EPA’s proposed regulation for Class VI wells (or on the owner or 

operator during the construction, injection, post-site injection care, site 

closure, and post-closure phases of a GS project). See id. at 43,536-37,

775
43,537-41 (proposed 40 C.F.R. §§ 146.82-.84, 146.86-.94).[FN4]

Given the central importance of "long-term" containment to any GS project, EPA 

should add a long-term containment demonstration requirement to the proposed 

regulation. At a minimum, a permit applicant should be required to demonstrate 

long-term containment as a precondition to being issued an injection permit, 

similar to the requirement in the Class I UIC program and Washington State’s GS 

regulation.[FN5] ELPC and ETIP recommend adopting a 1,000 year containment 

standard. 

[FN4] Texas imposes a demonstration requirement similar to Washington State as a 

condition for tax exemptions to encourage GS. Tex. Tax Code Ann. § 202.0545(d) 

(1)(2007) ("The operator’s planned sequestration program will ensure that at 

least 99 percent of the carbon dioxide sequestered . . . will remain sequestered 

for at least 1,000 years."). 

[FN5] EPA also should consider requiring the owner or operator to demonstrate 

long-term containment again as a precondition to granting site closure, and/or 

periodically during various phases of the GS project. 

Response: EPA clarifies that setting a "confinement standard" is outside the scope of the Class VI GS 

rulemaking. However, the Class VI GS rule requires that CO2 injected for GS remain confined in the 

injection zone. Leakage outside of the injection zone/to the surface would be a permit violation. The 

purpose of the Class VI GS rule is to ensure consistency in permitting underground injection of CO2 at 

GS operations across the United States and provide requirements to prevent endangerment of USDWs in 

anticipation of the eventual use of GS to reduce CO2 emissions. 

Comment: While NiSource will readily agree that there are many differences between 

storage of natural gas and geologic sequestration of CO2, NiSource submits that 

there are a number of technical and commercial similarities in addition to 

lessons that can be applied from decades of injection and control of high 

pressure natural gas. These similarities include technical issues, securing 

mineral rights, landowner relations, coexisting with third party development of 

the surface and subsurface, and a wide range of regulatory and commercial 

aspects. The following points summarize four primary lessons learned through 

Response: EPA recognizes that the oil and gas industry has decades of experience injecting CO2 and 

has demonstrated the effectiveness of many of the technologies that will be employed at GS sites. The 

Class VI GS rule builds on this expertise with requirements tailored to the unique issues associated with 

GS through proper permitting, siting, well construction, operation, monitoring, and closure of GS 

projects. However, EPA clarifies that pore space issues are outside the scope of the Class VI GS 

rulemaking. EPA clarifies that these issues are under the purview of states and any of these issues, as 

they relate to GS, will need to be addressed though state regulations. 

Comment: aspects. The following points summarize four primary lessons learned through 

Commenter Name: Daniel Plath Letter ID: 0188

Commenter Organization: NiSource, Inc. Comment ID: 25228

Commenter Name: Daniel Plath Letter ID: 0188

Commenter Organization: NiSource, Inc. Comment ID: 25231

776
operation of natural gas storage that would be applicable to GS: 

3. NiSource subsidiaries' experience is that it is impossible to obtain 100% 

agreement from thousands of landowners on the development of their subsurface 

for virtually any activity even with numerous public meeting, private 

discussions, newsletters, etc. For GS to be utilized beyond the pilot project 

scale, this issue must be addressed. While this topic is not directly within the 

scope of EPA and this Proposed Rule, EPA's requirements can have an impact on 

the degree and extent to which a potential operator will have to interfere with 

a landowner. That will directly impact a landowner's willingness to accept GS on 

their property. Excessive MMV regulations can cause the landowner to have an 

incorrect perception as to the safety of GS under their property. 

Response: As described above, pore space issues are outside the scope of the Class VI GS rulemaking. 

EPA clarifies that these issues are under the purview of states and any of these issues, as they relate to 

GS, will need to be addressed though state regulations. 

EPA acknowledges that CO2 plumes may cross state or even international boundaries and encourages 

cooperation and coordination among permitting authorities. The final Class VI GS rule, at §146.82(a)

(2), requires the owner or operator to identify all State, Tribal, and Territorial boundaries within the 

AoR. Based on this information, the Director must provide written notification to all States, Tribes, and 

Territories to inform them of the permit application and ensure that they are involved in any necessary 

processes; this new requirement was added to the final rule at §146.82(b). The Agency encourages 

transparency in the permitting process and anticipates that State-State/State-Tribal communication on 

Class VI permitting will facilitate information sharing and encourage safe, protective projects. 

Comment: Associated with the State primacy issue is how to address cross-state 

boundaries. We feel that some injection activities will cross State boundaries 

and that the State in which the wellhead is located should consult and 

coordinate with the other impacted State(s). Duel or duplicative regulatory 

systems will only unnecessarily burden potential injection projects limiting the 

value of this overall program. A final aspect for the states will be the 

Response: EPA acknowledges that CO2 plumes may cross state or even international boundaries and 

encourages cooperation and coordination among permitting authorities. The final Class VI GS rule, at 

§146.82(a)(2), requires the owner or operator to identify all State, Tribal, and Territorial boundaries 

within the AoR. Based on this information, the Director must provide written notification to all States, 

Tribes, and Territories to inform them of the permit application and ensure that they are involved in any 

necessary processes; this new requirement was added to the final rule at §146.82(b). The Agency 

encourages transparency in the permitting process and anticipates that State-State/State-Tribal 

communication on GS permitting will facilitate information sharing and encourage safe, protective 

projects. 

EPA clarifies that the Class VI permit would be issued by the permitting authority in the state where the 

wellhead is located. 

Commenter Name: Paul Pike Letter ID: 0198

Commenter Organization: Ameren Corporation Comment ID: 23940

Commenter Name: John Corra Letter ID: 0205

777
Comment: 3. Permit Fees: The US EPA should consider a permit fee formula for Class VI 

wells that is sufficient to support state, tribal, and permitting programs, 

provides consistency of fee amounts between such programs, and provides 

certainty of fee expenses to those interested in or applying for a Class VI 

permit. 

Response: EPA clarifies that it does not have authority to set permit fees for Class VI well owners or 

operators under SDWA. 

EPA recognizes that states may face technical and administrative challenges including resource 

concerns, and will work closely with the states to assist them in resolving funding issues or acquiring the 

resources, personnel, and training needed to address the unique technical challenges associated with GS. 

EPA will also incorporate Class VI GS wells into the UIC program's grant allocation process. The 

States/Tribes/Territories must also demonstrate that they have adequate resources to implement the 

program through matching resources against those allocated by the UIC program's grant allocation 

formula. Currently, primacy programs are required to meet a minimum of 25 percent matching 

requirement. 

Other EPA Comment Codes and Descriptions: 1610 1.3.1 Risks to USDWs; 3100 2.1 Proposed 

Geologic Siting Requirements (40 CFR 146.83) 

Comment: - The USDW classification must be reconsidered when siting Class VI wells. The 

best sources of drinking water are already being used by utilities. Coupled with 

challenges resulting from climactic changes, population growth and land 

development, many utilities are turning to more challenging groundwater sources 

such as those that are very deep or have high salinity concentrations, also 

because the pumping costs for these deep wells are no longer prohibitive given 

the lack of sufficient water elsewhere. Some of these new sources could fall 

outside of the current definition of a USDW, in that the aquifer has a TDS 

concentration higher than 10,000 ppm. EPA’s proposed rule promises protection of 

USDWs from endangerment yet there are no anti-degradation provisions in the 

proposed regulation to protect other groundwater supplies, such as those 

aquifers that are not classified as a USDW but have been, or may be, identified 

as a future drinking water source. The TDS criterion was written at a time when 

many advanced water treatment technologies were generally cost prohibitive. In 

light of the changes in the hydrological and technological landscape, we 

recommend that EPA reexamine the classification of USDWs based on TDS when 

considering the siting of Class VI geosequestration wells. The potential need to 

use saline aquifers for potable supply, particularly in water-stressed areas, 

should take precedence over the sequestration of carbon dioxide there. 

Response: The Agency acknowledges commenter concerns about water resources and future water 

resource availability. However, modifying the definition of a USDW is outside the scope of the GS 

rulemaking. USDWs are defined as aquifers currently being used as sources of drinking water or those 

capable of supplying a public water system and they have a total dissolved solids (TDS) content of 

10,000 milligrams per liter or less (§144.3). 

Commenter Organization: Wyoming Department of Environmental Quality 

(DEQ)

Comment ID: 

22191

Commenter Name: Diane VanDe Hei Letter ID: 0206

Commenter Organization: Association of Metropolitan Water Agencies 

(AMWA)

Comment ID: 

22209

778
The primary goal of the UIC Program under the SDWA is to protect USDWs in order to ensure a 

reliable supply of drinking water for the American public. The GS rule, as part of the UIC program 

regulations, continues the program’s tradition of ensuring the protection of USDWs. The permitting, 

siting, construction, operation, monitoring, and post-injection site care requirements in the GS rule built 

on a long-standing protective regulatory framework, tailored to the unique characteristics of CO2 GS. 

Comment: INJECTION ACTIVITIES THAT CROSS STATE BOUNDARIES 

In view of the likelihood that CO2 injection activities on GS projects will 

cross state boundaries, Duke Energy joins other stakeholders in urging EPA to 

reconsider its position of not addressing cross-state boundary issues in this 

rule-making. Instead, EPA should provide directives to states and corresponding 

certainty to owners and operators of GS projects when the AoR crosses state 

lines. At a minimum, the Final Rule should provide that the state in which the 

well head is located should be the primary state for purposes of permitting the 

Class VI well for GS of CO2. EPA should also direct the primary state to 

consult, coordinate and cooperate with each state within the AoR. The Final Rule 

should establish guidelines for the consultation, coordination and cooperation 

between the primary state and ach state within the AoR. 

Response: EPA acknowledges that CO2 plumes may cross state or even international boundaries and 

encourages cooperation and coordination among permitting authorities. The final Class VI GS rule, at 

§146.82(a)(2), requires the owner or operator to identify all State, Tribal, and Territorial boundaries 

within the AoR. Based on this information, the Director must provide written notification to all States, 

Tribes, and Territories to inform them of the permit application and ensure that they are involved in any 

necessary processes; this new requirement was added to the final rule at §146.82(b). The Agency 

encourages transparency in the permitting process and anticipates that State-State/State-Tribal 

communication on Class VI permitting will facilitate information sharing and encourage safe, protective 

projects. 

EPA clarifies that the Class VI permit must be issued by the permitting authority in the state where the 

wellhead is located pursuant to UIC regulations. 

Comment: Tampa Electric acknowledges the EPA's note that the proposed SDWA underground 

injection regulations do not provide the EPA with authority to develop 

regulations for all areas related to carbon sequestration, including 

"determining property rights (i.e., to permit its use for [carbon sequestration] 

and for possible storage credits) [and] transfer of liability from one entity to 

another", but feels that parts of this regulation can be constructed so as to 

provide important guidance in further statue and regulatory development as 

related to these issues. Of main importance in this particular regulation 

development, if the Federal government believes this type of regulation is 

necessary, then it is Tampa Electric's recommendation to EPA to include a 

declaration that the activity of CCS is of high public importance. If and when 

Commenter Name: Michael Stroben Letter ID: 0209

Commenter Organization: Duke Energy Comment ID: 22686

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 22901

779
storage of carbon dioxide is deemed a public necessity by the EPA, for the 

occasion that a CO2 injection well may be located adjacent to property owned by 

another party, the Final Rule may include verbiage analogous to underground 

natural gas storage eminent domain powers or oil and gas unitization processes 

for acquisition of pore space of a geological formation. Also, the EPA may 

consider providing guidance similar to that of the "negative rule of capture" 

for secondary oil recovery operations (water flooding), which provides that less 

valuable substances injected into a geological formation may migrate and replace 

more valuable substances without resulting liability. 

Response: EPA clarifies that eminent domain, pore space ownership, and surface and subsurface 

property and mineral rights are outside of the scope of the Class VI GS rulemaking. EPA clarifies that 

these issues are under the purview of states and any of these issues, as they relate to GS, will need to be 

addressed though state regulations. EPA also notes that carbon crediting and green house gas accounting 

are outside the scope of the Class VI GS rulemaking. The Class VI GS rule is designed to ensure 

consistency in permitting underground injection of CO2 at GS operations across the United States and 

provide requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to 

reduce CO2 emissions. 

However, the Agency acknowledges that these issues are important and is addressing them using other 

regulatory authorities. For example, in a separate rulemaking under authority of the Clean Air Act, EPA 

is amending the Greenhouse Gas Reporting Program at 40 CFR Part 98 to add reporting requirements 

for CO2 injection and GS. The greenhouse gas reporting requirements build on the requirements 

outlined in the Class VI GS rule with the additional goals of verifying the amount of CO2 sequestered 

and collecting data on any CO2 emissions to the surface from GS facilities. 

Comment: We would also call to EPA’s attention other recent research from the GHGT-9 

Conference that is relevant to this rulemaking with regard to the carbon content 

of oil that could be produced via CO2 injection of captured CO2 emissions. 

Ferguson, et al. reviewed the net carbon content of oil produced via CO2-based 

EOR, taking into account the storage of residual CO2 that remains stored as a 

normal incident of EOR production operations. The researchers calculated that 

oil produced through injection of captured CO2 emissions would be roughly 70 

percent "carbon free" under current technology. See Ferguson, Nichols, Leeuwen, 

and Kuuskraa, "Storing CO2 with Enhanced Oil Recovery" ("Ferguson, et al. 2008") 

[FN34] The authors estimate that next generation CO2 storage technology may 

allow for the produced oil to be "100+" percent carbon free and evaluate the 

potential size of the market for CO2 for these EOR purposes on the order of 

7,500 million metric tonnes between now and 2030. This capability of the U.S. 

oil industry to reduce the net carbon content of new oil supplies is an aspect 

of the sequestration debate that is not addressed in the Proposed Rule, but 

illustrates how targeted technological innovation can reduce carbon emissions 

while maintaining - indeed, growing - energy supply. 

[34] Paper presented at GHGT-9 Conference and available from the GHGT-9 

Conference website cited above. 

Response: EPA clarifies that the final Class VI GS rule does not require owners or operators to use GS 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24281

780
technologies, nor does it impact business as usual for Class II owners or operators that are injecting CO2 

to enhance production of oil or gas. Those owners or operators that choose to transition from enhanced 

recovery to GS may do so, provided they meet the requirements for Class VI wells. 

EPA clarifies that the purpose of the Class VI GS rule is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

EPA agrees that GS is one technology in a portfolio of options, including energy conservation, 

efficiency improvements, and the use of alternative fuels and renewable energy sources, that could be 

deployed to reduce CO2 emissions. 

Comment: 5. Clarify jurisdiction across state lines. The proposed rule does not address 

injection issues across state lines. For example, if the pressure boundary and 

the CO2 plume traverse across state lines, will the permittee be required to 

obtain a UIC permit from the neighboring state? If so, what kind of permit? In 

addition to requiring monitoring and financial assurance, would the neighboring 

state also set limits on the injection rates? Etc. Oklahoma DEQ recommends that 

EPA clarify jurisdiction across state lines. 

Response: EPA acknowledges that CO2 plumes may cross state or even international boundaries and 

encourages cooperation and coordination among permitting authorities. The final Class VI GS rule, at 

§146.82(a)(2), requires the owner or operator to identify all State, Tribal, and Territorial boundaries 

within the AoR. Based on this information, the Director must provide written notification to all States, 

Tribes, and Territories to inform them of the permit application and ensure that they are involved in any 

necessary processes; this new requirement was added to the final rule at §146.82(b). The Agency 

encourages transparency in the permitting process and anticipates that State-State/State-Tribal 

communication on Class VI permitting will facilitate information sharing and encourage safe, protective 

projects. 

EPA clarifies that the Class VI permit would be issued by the permitting authority in the state where the 

wellhead is located. 

Comment: Technical Comments p. 43497, IIC: USEPA needs to develop an effective way to 

handle cross-state boundary issues. Cross-state boundary issues could be a 

problem when dealing with pressure fronts in a setting like the Mt. Simon 

Sandstone, which is present beneath several Midwestern states. In addition, 

many stationary CO2 sources are located along state boundaries (i.e., power 

plants along major rivers). 

Response: EPA acknowledges that CO2 plumes may cross state or even international boundaries and 

encourages cooperation and coordination among permitting authorities. The final Class VI GS rule, at 

§146.82(a)(2), requires the owner or operator to identify all State, Tribal, and Territorial boundaries 

within the AoR. Based on this information, the Director must provide written notification to all States, 

Tribes, and Territories to inform them of the permit application and ensure that they are involved in any

Commenter Name: Saba Tahmassebi Letter ID: 0218

Commenter Organization: Oklahoma Department of Environmental Quality 

(DEQ)

Comment ID: 

21566

Commenter Name: Edward Mehnert Letter ID: 0221

Commenter Organization: Illinois State Geological Survey Comment ID: 21636

781
necessary processes; this new requirement was added to the final rule at §146.82(b). The Agency 

encourages transparency in the permitting process and anticipates that State-State/State-Tribal 

communication on GS permitting will facilitate information sharing and encourage safe, protective 

projects. 

Comment: 4. An applicant for CO2 credits must provide a clear demonstration of longterm 

CO2 containment. If the CO2 cannot be contained in a geological formation 

indefinitely, then the operator should not receive a credit. 

Response: EPA clarifies that setting a "containment standard" is outside the scope of the Class VI GS 

rulemaking. However, the Class VI GS rule requires that CO2 injected for GS remain confined in the 

injection zone. Leakage outside of the injection zone/to the surface would be a permit violation. The 

purpose of the Class VI GS rule is to ensure consistency in permitting underground injection of CO2 at 

GS operations across the United States and provide requirements to prevent endangerment of USDWs in 

anticipation of the eventual use of GS to reduce CO2 emissions. 

EPA clarifies that carbon crediting and greenhouse gas accounting are outside the scope of the Class VI 

GS rulemaking. The Class VI GS rule is designed to ensure the protection of USDWs from 

endangerment. However, the Agency acknowledges that these issues are important and is addressing 

them using other regulatory authorities. For example, in a separate rulemaking under authority of the 

Clean Air Act, EPA is amending the Greenhouse Gas Reporting Program at 40 CFR Part 98 to add 

reporting requirements for CO2 injection and geologic sequestration. The greenhouse gas reporting 

requirements build on the requirements outlined in the Class VI GS rule with the additional goals of 

verifying the amount of CO2 sequestered and collecting data on any CO2 emissions to the surface from 

Class VI GS facilities. 

Comment: Point #7: Multi-state jurisdictional issues. Finally, the scale of geologic 

storage projects could raise multi-state jurisdictional issues if the CO2 plume 

and AoR extend beyond and across state boundaries. The proposed rule should 

speak to potential multi-state jurisdictional issues in a manner that avoids 

conflicting state requirements. For instance, one option would allow the well 

head or injection site location to control jurisdiction. This would provide a 

framework for addressing multi-state jurisdiction and give owners/operators some 

certainty regarding tbe approach to this issue. 

Response: EPA acknowledges that CO2 plumes may cross jurisdictional boundaries and encourages 

cooperation and coordination among permitting authorities. The final Class VI GS rule, at §146.82(a)

(2), requires the owner or operator to identify all State, Tribal, and Territorial boundaries within the 

AoR. Based on this information, the Director must provide written notification to all States, Tribes, and 

Territories to inform them of the permit application and ensure that they are involved in any necessary 

processes; this new requirement was added to the final rule at §146.82(b). The Agency encourages 

transparency in the permitting process and anticipates that State-State/State-Tribal communication on 

GS permitting will facilitate information sharing and encourage safe, protective projects. 

Commenter Name: Jonathon Palm Letter ID: 0222

Commenter Organization: Nevada Division of Environmental Protection, Bureau of

Water Pollution Control

Comment ID: 

21643

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23965

782
EPA clarifies that the Class VI permit would be issued by the permitting authority in the state where the 

wellhead is located. 

Comment: (1) Property Rights Issues Are Matter of State Law 

EPA accurately states that the SDWA does not afford EPA the authority to 

regulate many issues involved in CO2 sequestration, including property rights 

which are regulated under state law. (73 Fed. Reg. at 43495.) In many instances, 

the owner of the surface property rights may be different than the owner of the 

subsurface mineral rights. There may be a legal question as to who owns the 

subsurface storage rights as between, for example, the surface property rights 

owner and the mineral rights owner. This is a matter of state law as correctly 

discussed by EPA. BP requests that EPA expand on its assertion in the Preamble 

that it does not have authority to regulate in this area and that nothing in the 

Proposed Rule should be interpreted or inferred as a grant of subsurface storage 

rights. 

Response: EPA clarifies that pore space ownership and surface and subsurface property and mineral 

rights are outside of the scope of the Class VI GS rulemaking. These issues are under the purview of 

states and any of these issues, as they relate to GS, will need to be addressed though state regulations. 

The UIC program’s authority under SDWA is focused on ensuring that where GS technologies are 

deployed, GS is performed in a manner that protects USDWs from endangerment. 

Comment: (3) Proposed Rule Should Not Affect Injection of Oil & Gas Waste 

Oil and gas waste (such as produced water and amine waste gases [CO2 and H2S]) 

are often injected back into the reservoir after separation during oil and gas 

production activities. This type of injection is and has been historically 

permissible under Class II regulations. (See 40 CFR § 144.6(b)(1).) EPA was 

silent on whether the Proposed Rule would in any manner affect the applicability 

of the Class II well regulations for injection of oil and gas waste. EPA should 

indicate in its Preamble to the Final Rule that the Final Rule does not alter in 

any manner the applicability of Class II regulations to injection of oil and gas 

waste. 

Response: The Agency clarifies that the final Class VI GS rule does not require owners or operators to 

use GS technologies, nor does it impact business as usual for Class II owners or operators that are 

injecting CO2 to enhance production of oil or gas. Those owners or operators that choose to transition 

from enhanced recovery to GS may do so, provided they meet the requirements for Class VI wells. 

Comment: A. Regulatory Uncertainty 

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21760

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21762

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21780

783
GS projects need regulatory certainty in order to move forward as a meaningful 

approach to reduce CO2 emissions. While it is an important first step, the EPA 

proposed rule addresses only one piece of the needed regulatory framework: that 

is the protection of USDW. CURC understands that the authority delegated to EPA 

in the SDWA does not permit the EPA to develop a comprehensive regulatory 

framework that covers all of the components needed to provide regulatory 

certainty, which are needed to facilitate the widespread use of GS. This 

regulatory certainty is essential; a number of additional issues must be 

addressed by the federal or state governments in order for carbon capture and 

the enabling GS to move forward. Chief among these issues are: 

1. the surface property rights associated with GS wells; 

2. subsurface and pore space rights associated with GS wells; 

3. flexibility in the ruling that allows transfer of geologic storage (GS) sites 

and CO2 ownership, monitoring and mitigation responsibility from one entity to 

another; and 

4. long-term liability. 

Response: EPA clarifies that pore space ownership and surface and subsurface property and mineral 

rights are outside of the scope of the Class VI GS rulemaking. The purpose of the Class VI GS rule is to 

ensure consistency in permitting underground injection of CO2 at GS operations across the United 

States and provide requirements to prevent endangerment of USDWs in anticipation of the eventual use 

of GS to reduce CO2 emissions. EPA recognizes the importance of providing clear, flexible, scalable, 

and appropriate regulations. EPA believes that the GS regulation will provide certainty to industry and 

the public by providing consistency in requirements across the U.S. and transparency about what 

requirements apply to owners or operators. 

Regarding transfer of GS sites, the Agency acknowledges that owners or operators of wells regulated 

under existing well classifications may seek to re-permit their wells for GS. However, the Class VI GS 

rule does not allow for automatic transfer of a Class VI permit to a new owner or operator; see §144.38

(b). Given the unique nature of GS and the importance of interaction between GS project owners or 

operators and permitting authorities, the Agency believes that the Director should have an opportunity to 

review the permit and determine whether any changes are necessary at the time of the permit transfer, 

pursuant to requirements at §146.38(a). If information about the GS project and existing permit 

conditions are determined to be adequate, the permit review and transfer may entail a minimal amount 

of new information and administrative effort. 

Regarding long-term liability, once an owner or operator has met all requirements under Part 146 for 

Class VI wells and the Director has approved site closure pursuant to requirements at §146.93, the 

owner or operator will generally no longer be subject to enforcement for regulatory noncompliance. 

Furthermore, their financial instrument as required under §146.85 will be released if it was not used. 

However, even if a site closure is approved under §146.93, an owner or operator may be held liable for 

regulatory noncompliance (including violation of 40 CFR 144.12) in certain circumstances. For 

example, an owner or operator may be held liable for regulatory noncompliance even after site closure 

was approved if the Director relied on erroneous information (e.g., erroneous modeling data) provided 

by the owner or operator when approving site closure. 

Separate from EPA’s authority to enforce regulatory compliance, an owner or operator may be subject to 

a §1431 response order even after proper site closure is approved under §146.93. Under §1431 the 

Administrator may require an owner or operator to take necessary response measures if he or she 

784
receives information that a contaminant is present or is likely to enter a public water system or an 

USDW, which may present an imminent and substantial endangerment to the health of persons, and the 

appropriate State and local authorities have not acted to protect the health of such persons. The action 

may include issuing administrative orders or commencing a civil action for appropriate relief against the 

owner or operator of a Class VI well. If the owner or operator fails to comply with the order, they may 

be subject to a civil penalty for each day in which such violation occurs or failure to comply continues. 

Furthermore, after site closure an owner or operator may remain liable under tort and other remedies, or 

under other federal statutes including, but not limited to, Clean Air Act, 42 U.S.C. §§ 7401-7671; 

CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. EPA does not have authority to 

transfer SDWA or other legal liability for Class VI wells to the State or federal government or a thirdparty fund. See the final rule preamble for further discussion of EPA's final approach to financial 

responsibility for Class VI wells. 

Comment: Page 138, Primacy/Jurisdiction- Given the size and location of potential GS 

projects, many storage areas are likely to cross state lines. For example 

almost all of the major sources of CO2 emissions in the MRCSP region are at or 

near state boundaries, along Ohio River. For example, a geologic storage 

facility located near Wheeling West Virginia could have a CO2 plume and 

injection well locations in Ohio, West Virginia, and Pennsylvania. It is 

unclear how these projects would be implemented regarding who has primacy in 

permitting the site under a single permit, rather than three separate permits. 

Additional guidance permitting sites with multiple jurisdictions is highly 

desirable to prevent confusion or legal challenges. 

Response: EPA acknowledges that CO2 plumes may cross jurisdictional boundaries and encourages 

cooperation and coordination among permitting authorities. The final Class VI GS rule, at §146.82(a)

(2), requires the owner or operator to identify all State, Tribal, and Territorial boundaries within the 

AoR. Based on this information, the Director must provide written notification to all States, Tribes, and 

Territories to inform them of the permit application and ensure that they are involved in any necessary 

processes; this new requirement was added to the final rule at §146.82(b). The Agency encourages 

transparency in the permitting process and anticipates that State-State/State-Tribal communication on 

Class VI permitting will facilitate information sharing and encourage safe, protective projects. 

Other EPA Comment Codes and Descriptions: 1400 1.2 Comments on EPA's Authority to Regulate 

Injection of CO2 

Comment: 7. EPA’s laudable efforts notwithstanding, we believe the Safe Drinking Water 

Act (SDWA) does not provide adequate authority to comprehensively regulate GS. 

Because the statutory authority for the UIC Program derives from the SDWA, the 

proposed rule is unable to address key issues that must be resolved for 

commercial-scale GS,[FN1] such as: 

• ownership of pore space (discussed in Chapter 5 of attached report); 

• potential human health or ecological impacts if carbon dioxide leaks to the 

Commenter Name: Neeraj Gupta Letter ID: 0229

Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21867

Commenter Name: M. Granger Morgan Letter ID: 0233

Commenter Organization: Carnegie Mellon University on behalf of the CCS Reg 

Project

Comment ID: 

21899

785
surface or near-surface (discussed in Chapters 1, 4, and 6 of attached report); 

• long-term liability (discussed in Chapters 7 and 8 of attached report); and, 

• greenhouse gas regulatory accounting, which will be the enabling link to 

incentive structures that make GS economically viable (discussed in Chapters 8 

and 9 of attached report). 

[FN1: These limitations are acknowledged by the agency in the preamble to the 

rule. (73 FR 43,495)] 

8. Failure to resolve the above issues could make the commercial development of 

CCS impossible. 

Response: EPA acknowledges that GS falls within the broader context of CCS and the need for 

regulatory clarity to ensure that USDWs are protected from endangerment. In developing the final GS 

rule, the Office of Water coordinated with other Agency program offices and across federal agencies 

(e.g., with the Department of Energy; United States Geological Survey; Bureau of Ocean Energy 

Management, Regulation, and Enforcement, formerly the Minerals Management Service; and the 

Bureau of Land Management). The Agency continues to evaluate areas of potential applicability of other 

Federal environmental statutes including, but not limited to: the Clean Air Act; the Resource 

Conservation and Recovery Act; the Comprehensive Environmental Response, Compensation, and 

Liability Act; and the Marine Protection, Research and Sanctuaries Act to various aspects of GS and 

CCS. The Agency will continue to coordinate on GS and CCS related issues to minimize redundancy 

and maximize efficiencies for owners or operators. For additional information, please see the discussion 

entitled "How Does This Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" 

in the preamble to the final GS rule. 

EPA is also aware that states are currently in various stages of developing statutory frameworks, 

regulations, technical guidance, and strategies for addressing CCS and GS. States can use multiple 

authorities beyond those afforded under the SDWA and UIC regulations, including laws and policies 

addressing surface access and land rights, unitization of fields, pore space ownership, mineral rights, 

worker safety and emergency preparedness, and maximization of state oil and gas resource exploitation. 

EPA plans to work closely with states and tribes as they develop Class VI primacy programs in this 

broader context. EPA adds that states may adopt more stringent standards for Class VI wells than the 

Federal requirements. 

The final rulemaking falls within EPA’s authority under the SDWA. EPA clarifies that the SDWA 

provides EPA with the authority to develop federal minimum requirements for underground injection, 

such as GS, that are directly related to protecting USDWs from endangerment. Thus EPA does not have 

authority under the SDWA to address other general issues related to CCS, such as capture and 

transportation. EPA clarifies that the GS rule does not address the status of CO2 as a pollutant or 

commodity. The UIC requirements regulate the injection of fluids. EPA adds that regulating carbon capand trade is outside of the UIC program's authority under SDWA. 

EPA recognizes that liability is an important issue to owners or operators but the Agency does not have 

authority under the SDWA to transfer long-term liability from owners or operators to the state or federal 

government. Therefore, liability remains with the owner or operator. 

Commenter Name: M. Granger Morgan Letter ID: 0233

Commenter Organization: Carnegie Mellon University on behalf of the CCS Reg 

Project

Comment ID: 

21901

786
Other EPA Comment Codes and Descriptions: 1400 1.2 Comments on EPA's Authority to Regulate 

Injection of CO2 

Comment: Overarching recommendations 

10. The inability of the proposed rule to manage the issues listed above should 

be remedied by either: 

a. passage of new federal legislation to supplement the UIC program and amend 

the SDWA; or 

b. passage of new freestanding federal legislation to regulate GS 

comprehensively. 

These options are detailed in Chapter 6 of the attached report [SEE PDF TO VIEW THE REPORT]. 

Response: This comment is outside the scope of this rulemaking. As described above, EPA recognizes 

that a more comprehensive framework may be needed and that some stakeholders remain uncertain 

about the potential applicability of other federal environmental statutes, such as the Clean Air Act, to 

various aspects of GS. The Agency is currently evaluating the need for a more comprehensive regulatory 

framework for this emerging technology. 

Other EPA Comment Codes and Descriptions: 1400 1.2 Comments on EPA's Authority to Regulate 

Injection of CO2 

Comment: Issues that would requirement amendment of the SWDA or passage of new 

legislation 

13. Need to balance multiple environmental interests: Protection of drinking 

water is an essential environmental goal, but must be balanced with avoidance of 

the dangerous impacts of climate change. As mandated by the SDWA, the UIC 

Program rules have been developed with the objective of preventing any migration 

of injected fluid or other contaminants into USDWs. In practice, however, 

regulatory treatment of injectate migration has been less clear-cut. For example 

the experience in Florida, discussed in Chapter 6 of the attached report [SEE PDF TO VIEW THE 

REPORT], 

suggests that it would be highly desirable to have arrangements in place ahead 

of time to allow balancing of potentially conflicting national environmental 

interests. We recommend that the SDWA be amended to allow balancing multiple 

environmental interests. 

Response: This comment is outside the scope of the rulemaking. As described above, EPA recognizes 

that a more comprehensive framework may be needed and that some stakeholders remain uncertain 

about the potential applicability of other federal environmental statutes, such as the Clean Air Act, to 

various aspects of GS. The Agency is currently evaluating the need for a more comprehensive regulatory 

framework for this emerging technology. 

Commenter Name: M. Granger Morgan Letter ID: 0233

Commenter Organization: Carnegie Mellon University on behalf of the CCS Reg 

Project

Comment ID: 

21904

Commenter Name: M. Granger Morgan Letter ID: 0233

Commenter Organization: Carnegie Mellon University on behalf of the CCS Reg 

Project

Comment ID: 

21905

787
Comment: 14. Ownership of Pore Space: Considerable ambiguity exists today in the U.S. as 

to the current ownership of the deep pore space that would hold injected CO2, 

and how the right to use deep pore space would be obtained for GS purposes. It 

appears that most injectors of waste fluids into other well classes regulated by 

the UIC have not secured rights or permission to use the pore space from any 

surface or sub-surface property owners. At least a few of those injection 

projects likely involve volumes of fluid as large or larger than the volumes of 

CO2 that will be involved in commercial-scale CCS projects. In order for CCS to 

remain an economic possibility, new legislation must allow the federal or state 

governments to intervene to manage or limit private property rights for the use 

of pore space for GS. Otherwise, states or private property owners could demand 

high rental rates that could block development of CCS. 

Response: EPA clarifies that pore space ownership and surface and subsurface property and mineral 

rights are outside of the scope of the Class VI GS rulemaking, which focuses on ensuring consistency in 

permitting underground injection of CO2 at GS operations across the United States and provides 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. EPA clarifies that these issues are under the purview of states and any of these issues, as 

they relate to GS, will need to be addressed though state regulations. 

Comment: Beyond establishing regulations to govern the actual process for managing the 

injection of CO2 into underground formations, there are other important matters 

that must also be addressed before carbon capture and geologic storage (CCGS) 

operations can be developed. These matters are clearly beyond the scope of the 

regulations proposed by EPA. Included are: 

1. The creation of a legal framework for a storage facility operator to obtain 

control of the reservoir and associated pore space to be used for C02 storage. 

The right to use reservoirs and associated pore space is a private property 

right that must be acquired from the owner of the property. Included with this 

framework must be a method for amalgamating or consolidating the rights in order 

to provide for the orderly development of a long-term storage project. Given 

that these actions pertain to the acquisition or control of private property 

rights, they are functions to be established by state law. 

Response: EPA clarifies that pore space ownership and surface and subsurface property and mineral 

rights are outside of the scope of the Class VI GS rulemaking, which focuses on ensuring consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. EPA clarifies that these issues are under the purview of states and any of these issues, as 

they relate to GS, will need to be addressed though state regulations. 

Comment: 3) Landowners: Land ownership may change through the course of a CCS facility’s 

life. At some sites, the surface owner of a plot of land will not own the pore 

space underneath. Wyoming is the only state we are aware of that has clarified 

Commenter Name: Robert E. Carter Jr. Letter ID: 0236

Commenter Organization: Indiana Department of Natural Resources (IDNR) Comment ID: 23201

Commenter Name: Randy Joseph Letter ID: 0240

Commenter Organization: Western Organization of Resource Councils Comment ID: 23221

788
ownership rules, and clearly states that the surface owner owns the pore space 

for carbon storage, but Wyoming law allows ownership of the surface and pore 

space to be severed. Thus, it is likely that multiple property rights will be 

involved in any geologic sequestration site, particularly where geologic 

sequestration is proposed at sites where oil, gas and coal are already being 

developed. 

One of the aspects of having split estates is that the surface owner, who 

suffers most if a site is not appropriately closed and reclaimed, may not be the 

party who is doing the actual closure and reclamation work. In our experience, 

surface owners often have little ability to ensure that appropriate siting, 

operating, monitoring, closure and reclamation controls are in place. These 

landowners must rely on the regulatory agency to protect their interests. 

Response: EPA clarifies that pore space ownership and surface and subsurface property and mineral 

rights are outside of the scope of the Class VI GS rulemaking, which focuses on ensuring consistency in 

permitting underground injection of CO2 at GS operations across the United States and provides 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. EPA clarifies that these issues are under the purview of states and any of these issues, as 

they relate to GS, will need to be addressed though state regulations. 

Other EPA Comment Codes and Descriptions: 1200 1.1 General comments about the rulemaking 

Comment: WEST Associates Comments on the Proposed Rule 

The following are WEST's comments on the Preamble and proposed rule, which we 

believe will clarify and strengthen the proposal: 

– Under the proposed UIC regulation, siting UIC wells for GS in the west will 

likely involve a challenging set of national agencies, states, and tribal sets 

of regional and sub-regional regulation that will require streamlining in order 

to site UIC wells and pipelines to transfer super critical CO2 to GS sites 

located at some distances away from coal fired power plants. Such projects will 

cross over many jurisdictions and involve a patchwork of regulatory 

requirements. This will require coordination among federal and tribal 

jurisdictions since it is highly likely that most western projects will impact 

federal lands, including tribal lands. EPA should immediately start working 

towards building support and consensus among the federal land managers and BIA 

for the UIC regulatory program. 

Response: EPA understands that the CO2 plumes for large GS projects may cross State, Tribal, 

Territorial, EPA Regional, or national boundaries. The final GS rule, at §146.82(a)(2), requires the 

owner or operator to identify all State, Tribal, and Territorial boundaries within the AoR. Based on this 

information, the Director must provide written notification to all States, Tribes, and Territories to inform 

them of the permit application §146.82(b) and ensure that they are involved in any necessary processes 

(e.g., development of the emergency and remedial response plan (§146.94)). The Agency encourages 

transparency in the permitting process and anticipates that State-State/State-Tribal communication on 

GS permitting will facilitate information sharing and encourage safe, protective projects. 

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission Associates Comment ID: 22240

789
EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

Comment: ROUNDTABLE CONCERNS 

As policymakers and project developers work through the many nuances involved 

with large-scale CCS, we believe that it is important to keep focused on this 

central tenet: strong and early investment in CCS technologies and 

infrastructure is a necessary foundation for any viable climate change regulatory 

regime. 

Response: EPA clarifies that the purpose of the Class VI GS rule is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

EPA agrees that GS is one technology in a portfolio of options, including energy conservation, 

efficiency improvements, and the use of alternative fuels and renewable energy sources, that could be 

deployed to reduce CO2 emissions. However, the intent of the Class VI GS regulations is not to promote 

or incentivize the use of GS, but, instead to ensure protection of USDWs where GS technologies are 

deployed. 

EPA recognizes the importance of providing clear, flexible, scalable, and appropriate regulations. EPA 

believes that the Class VI GS regulation will provide certainty to industry and the public by providing 

consistency in requirements across the U.S. and transparency about what requirements apply to owners 

or operators. 

Other EPA Comment Codes and Descriptions: 1420 1.2.1.1 Support the GS rulemaking 

Comment: It is also essential that the U.S. Environmental Protection Agency (EPA) take 

supplemental action, based on other (non-SDWA) authority, to provide additional 

assurance that injected CO2 will not be released into the atmosphere in a way 

that adversely impacts the climate or otherwise endangers public health and 

welfare. Generally, the steps needed to protect USDWs are also needed in order 

to prevent emissions to the atmosphere. Supplemental steps citing additional 

authority should also guarantee that CO2 injected into geologic formations stays 

out of the atmosphere. This should be done according to a permanence 

Commenter Name: James T. Sims Letter ID: 0249

Commenter Organization: Western Business Roundtable Comment ID: 22257

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22271

790
(performance) standard, which will certify CO2 as ‘geologically sequestered’ for 

that purpose, in addition to protecting USDWs. These are needed, as none of the 

existing or proposed injection classes are adequate for the task of certifying 

CO2 as permanently sequestered for the purposes of preventing atmospheric 

releases. In order to be fully protective of the environment, Congress will also 

need to pass comprehensive cap and trade legislation to control the emission of 

greenhouse gases from all anthropogenic sources. But the need for such 

legislation is not a basis for deferring the adoption of EPA rules to protect 

USDWs or to assure that injected CO2 does not result in harmful releases to the 

atmosphere. 

Response: EPA acknowledges that the issue of GS falls within the broader context of CCS, but clarifies 

that the scope of the GS regulation is limited to injection of CO2, and that all requirements in the GS 

rule are designed for the purpose of protecting USDWs from endangerment. The SDWA does not 

provide the UIC Program with the authority to develop regulations for all areas related to GS, such as 

releases to the atmosphere. "Cap and trade" legislation is outside of the scope of this rulemaking. The 

UIC requirements are designed to ensure that, where GS is employed, it is done in a manner that protects 

USDWs from endangerment. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

In a separate rulemaking under authority of the Clean Air Act, EPA is amending the Greenhouse Gas 

(GHG) Reporting Program at 40 CFR Part 98 to add reporting requirements for facilities that conduct 

GS (subpart RR) and all other facilities that inject CO2 underground (subpart UU). For additional 

information, see the section of the final GS rule preamble entitled, "How Does Mandatory Reporting of 

Greenhouse Gases (GHGs) Relate to This Rulemaking?” and the GHG Reporting Program rulemaking 

and docket. 

Other EPA Comment Codes and Descriptions: 1290 1.1.2.2 Comments that EPA should regulate 

CO2 as a pollutant 

Comment: The Supreme Court recognized in Massachusetts v. EPA [FN2] that EPA has 

authority and, indeed an obligation, under the Clean Air Act to regulate 

emissions of greenhouse gases, including CO2, that "cause or contribute to air 

pollution that may reasonably be anticipated to endanger public health or 

welfare." [FN3] Similarly, the D.C. Circuit’s remand of the power plant new 

source performance standards ("NSPS") places EPA in the position to regulate CO2 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22272

791
emissions from new and also existing sources within that industrial sector. 

[FN4] The Environmental Appeals Board EAB also recently has rejected the 

agency’s arguments that it is not authorized to issue best available control 

technology (BACT) emissions limits for CO2 in the context of a new source air 

permit decision for a large new coal-fired power plant, under the Clean Air 

Act’s Prevention of Significant Deterioration (PSD) new source review authority. 

[FN5] 

[FN2: 127 S.Ct. 1438 (2007).] 

[FN3: Id. at 1460-61.] 

[FN4: Order, NY, et al. v. EPA, D.C. Cir. No. 06-1322 (Sept. 24, 2007). Once 

NSPS are set for an industry under section 111(b), 42 U.S.C. §7411(b), the Act 

requires EPA to set standards for states to regulate emissions from existing 

sources in that industry. 42 U.S.C. § 7411(d).] 

[FN5: In re: Deseret Power Electric Coop., PSD App. No 07-03, Slip Op. (Nov. 13, 

2008). The memorandum issued December 18, 2008 by Administrator Johnson entitled 

"EPA’ Interpretation of Regulations that determine Pollutants Covered by Federal 

Prevention of Significant Deterioration (PSD) Permit Program" (Johnson PSD memo) 

is procedurally deficient, and, in any event, states explicitly on its face that 

it is not intended to supersede the EAB’s decision in the Deseret case. Johnson 

memo at 2. Nor, indeed, can it lawfully do so.] 

Response: The purpose of the Class VI GS regulation is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

The requirements apply only to GS injection technologies including well construction, operation, 

monitoring and testing technologies. The Supreme Court decision under Massachusetts v. EPA and 

Clean Air Act (CAA) provisions related to New Source Performance Standards (NSPS) and Best 

Available Control Technology (BACT) determinations are outside the scope of this Class VI GS 

rulemaking. 

The Class VI GS rulemaking is promulgated under Safe Drinking Water Act authority and does not 

relate to any endangerment and cause or contribute findings under the Clean Air Act. The Class VI GS 

requirements do not depend upon, and are unaffected by, Clean Air Act endangerment and cause or 

contribute findings. More information on EPA's Endangerment and Cause or Contribute Findings for 

Greenhouse Gases under Section 202(a) of the Clean Air Act can be found at 

http://www.epa.gov/climatechange/endangerment.html. 

In a separate rulemaking under authority of the Clean Air Act, EPA is amending the Greenhouse Gas 

Reporting Program at 40 CFR Part 98 to add reporting requirements for CO2 injection and geologic 

sequestration. The greenhouse gas reporting requirements build on the requirements outlined in the 

Class VI GS rule with the additional goals of verifying the amount of CO2 sequestered and collecting 

data on any CO2 emissions to the surface from GS facilities. 

Comment: As EPA correctly notes in the preamble of this rule, several key areas remain to 

be addressed that are beyond the EPA's authority under the SDWA before 

commercial scale carbon capture and storage will occur. Examples of these areas 

indude management of long lerm responsibihty for storage sites, monetization of 

Commenter Name: Ken Miller Letter ID: 0257

Commenter Organization: ExxonMobil Production Company Comment ID: 22370

792
CO2 in a way that does not adversely affect economic development and prospenty, 

public education and awareness, and development of balanced property rights and 

access principles. 

Response: EPA clarifies that the purpose of the Class VI GS rule is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

Establishing a price for carbon and property rights issues are outside of the scope of the GS rule. 

EPA recognizes the importance of providing clear, flexible, scalable, and appropriate regulations. EPA 

believes that the GS regulation will provide certainty to industry and the public by providing consistency 

in requirements across the U.S. and transparency about what requirements apply to owners or operators.

EPA notes that long-term liability is outside of the scope of the GS rulemaking and is not addressed in 

the GS rule. SDWA does not contain any express provisions addressing liability. An owner or operator 

will be held liable for any permit violations under SDWA §1423. 

Under the final GS rule, once an owner or operator has met all regulatory requirements under Part 146 

for Class VI wells and the Director has approved site closure pursuant to requirements at §146.93, the 

owner or operator will generally no longer be subject to enforcement for regulatory noncompliance. 

Furthermore, their financial instrument as required under §146.85 will be released if it was not used. 

However, even if a site closure is approved under §146.93, an owner or operator may be held liable for 

regulatory noncompliance (including violation of 40 CFR 144.12) in certain circumstances. For 

example, an owner or operator may be held liable for regulatory noncompliance even after site closure 

was approved if the Director relied on erroneous information (e.g., erroneous modeling data) provided 

by the owner or operator when approving site closure. 

Separate from EPA’s authority to enforce regulatory compliance, an owner or operator may be subject to 

a §1431 response order even after proper site closure is approved under §146.93. Under §1431 the 

Administrator may require an owner or operator to take necessary response measures if he or she 

receives information that a contaminant is present or is likely to enter a public water system or an 

USDW, which may present an imminent and substantial endangerment to the health of persons, and the 

appropriate State and local authorities have not acted to protect the health of such persons. The action 

may include issuing administrative orders or commencing a civil action for appropriate relief against the 

owner or operator of a Class VI well. If the owner or operator fails to comply with the order, they may 

be subject to a civil penalty for each day in which such violation occurs or failure to comply continues. 

Furthermore, after site closure an owner or operator may remain liable under tort and other remedies, or 

under other federal statutes including, but not limited to, Clean Air Act, 42 U.S.C. §§ 7401-7671; 

CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. EPA does not have authority to 

transfer SDWA or other legal liability for Class VI wells to the State or federal government or a thirdparty fund. See the final rule preamble for further discussion of EPA's final approach to financial 

responsibility for Class VI wells. 

Comment: Finally, although NACCSA recognizes the limits on the Agency's jurisdiction with 

regard to CCS projects, its members appreciate the Agency raising for public 

comment issues related to property rights that may be associated with CO2 injection and storage, such as 

Commenter Name: Michael Moore Letter ID: 0265

Commenter Organization: North American Carbon Capture & Storage 

Association (NACCSA)

Comment ID: 

22874

793
ownership of pore 

space in which CO2 will be stored, as well as issues of long-term responsibility 

for stored CO2 and storage site integrity. While the importance of EPA's rulemaking 

as an important step in providing clarity and certainty for project operators and 

investors cannot be overstated, CCS projects may not go forward in the absence 

of resolution of these issues. EPA's efforts in this regard will serve to raise 

stakeholder and policy maker awareness regarding the importance of resolving these 

critical issues so necessary to the successful commercial deployment of CCS. 

Response: EPA acknowledges the comment. EPA agrees that pore space ownership issues are outside 

the scope of the Class VI GS rulemaking; these are under the purview of states and any of these issues, 

as they relate to GS, will need to be addressed though state regulations. The purpose of the Class VI GS 

rule is to ensure consistency in permitting underground injection of CO2 at GS operations across the 

United States and provide requirements to prevent endangerment of USDWs in anticipation of the 

eventual use of GS to reduce CO2 emissions. 

EPA recognizes the importance of providing clear, flexible, scalable, and appropriate regulations. EPA 

believes that the Class VI GS regulation will provide certainty to industry and the public by providing 

consistency in requirements across the U.S. and transparency about what requirements apply to owners 

or operators. 

EPA notes that long-term liability is outside of the scope of the GS rulemaking and is not addressed in 

the GS rule. SDWA does not contain any express provisions addressing liability. An owner or operator 

will be held liable for any permit violations under SDWA §1423. 

Under the final GS rule, once an owner or operator has met all regulatory requirements under Part 146 

for Class VI wells and the Director has approved site closure pursuant to requirements at §146.93, the 

owner or operator will generally no longer be subject to enforcement for regulatory noncompliance. 

Furthermore, their financial instrument as required under §146.85 will be released if it was not used. 

However, even if a site closure is approved under §146.93, an owner or operator may be held liable for 

regulatory noncompliance (including violation of 40 CFR 144.12) in certain circumstances. For 

example, an owner or operator may be held liable for regulatory noncompliance even after site closure 

was approved if the Director relied on erroneous information (e.g., erroneous modeling data) provided 

by the owner or operator when approving site closure. 

Separate from EPA’s authority to enforce regulatory compliance, an owner or operator may be subject to 

a §1431 response order even after proper site closure is approved under §146.93. Under §1431 the 

Administrator may require an owner or operator to take necessary response measures if he or she 

receives information that a contaminant is present or is likely to enter a public water system or an 

USDW, which may present an imminent and substantial endangerment to the health of persons, and the 

appropriate State and local authorities have not acted to protect the health of such persons. The action 

may include issuing administrative orders or commencing a civil action for appropriate relief against the 

owner or operator of a Class VI well. If the owner or operator fails to comply with the order, they may 

be subject to a civil penalty for each day in which such violation occurs or failure to comply continues. 

Furthermore, after site closure an owner or operator may remain liable under tort and other remedies, or 

under other federal statutes including, but not limited to, Clean Air Act, 42 U.S.C. §§ 7401-7671; 

CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. EPA does not have authority to 

transfer SDWA or other legal liability for Class VI wells to the State or federal government or a thirdparty fund. See the final rule preamble for further discussion of EPA's final approach to financial 

responsibility for Class VI wells. 

794
Other EPA Comment Codes and Descriptions: 5400 2.9 Proposed Financial Responsibility and 

Long-Term Care Requirements 

Comment: drinking water, particularly sole-source aquifers. Other concerns include 

unproven technology to be used for injection wells, undefined water rights 

between states sharing a single underground source of water, and unresolved 

long-term liability and financial responsibility for sequestration sites. We 

Response: EPA clarifies that subsurface property rights, including water rights, are outside the scope of 

the GS rulemaking. 

Under SDWA authority, owners or operators of injection wells must ensure protection of USDWs from 

endangerment and are subject to liability for enforcement under the Act. The final rule requires that an 

owner or operator must conduct monitoring as specified in the Director-approved PISC and site closure 

plan following the cessation of injection until the owner or operator can demonstrate to the Director that 

the geologic sequestration project no longer poses an endangerment to USDWs. For additional 

information about the PISC and site closure requirements, see the preamble to the final GS rule. 

Once an owner or operator has met all regulatory requirements under Part 146 for Class VI wells and the 

Director has approved site closure pursuant to requirements at §146.93, the owner or operator will 

generally no longer be subject to enforcement for regulatory noncompliance. Furthermore, their 

financial instrument as required under §146.85 will be released if it was not used. However, even if a 

site closure is approved under §146.93, an owner or operator may be held liable for regulatory 

noncompliance (including violation of 40 CFR 144.12) in certain circumstances. For example, an owner 

or operator may be held liable for regulatory noncompliance even after site closure was approved if the 

Director relied on erroneous information (e.g., erroneous modeling data) provided by the owner or 

operator when approving site closure. 

Additionally, an owner or operator may always be subject to any action the Administrator deems 

necessary to protect the health of persons under §1431 of the SDWA after site closure if there is 

unanticipated migration towards or into a USDW that causes or threatens imminent and substantial 

endangerment to public health. The action may include issuing administrative orders or commencing a 

civil action for appropriate relief. If the owner or operator fails to comply with the order, they may be 

subject to a civil penalty for each day in which such violation occurs or failure to comply continues. 

The Agency clarifies that Class VI well permits may be transferred to another owner or operator 

pursuant to §144.38 whereby generally all other regulatory responsibilities are transferred to that new 

owner and operator, which includes all potential liabilities associated with meeting the requirements of 

that permit. Please see further clarification on the issue of long term liability in the preamble of the final 

rule. 

Furthermore, after site closure an owner or operator may remain liable under tort and other remedies, or 

under other federal statutes including, but not limited to, Clean Air Act, 42 U.S.C. §§ 7401-7671; 

CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. EPA does not have authority to 

transfer SDWA or other legal liability for Class VI wells to the State or federal government or a thirdparty fund. See the final rule preamble for further discussion of EPA's final approach. 

Commenter Name: Mic Stewart Letter ID: 0279

Commenter Organization: Metropolitan Water District of Southern California Comment ID: 24094

795
Other EPA Comment Codes and Descriptions: 1400 1.2 Comments on EPA's Authority to Regulate 

Injection of CO2 

Comment: Third, we raise the issue of authority. The rulemaking to date has only cited 

authority under the Safe Drinking Water Act (SDWA). As we stated in our comments 

of Dec24, 2008, an appropriate regulatory regime for GS must also be grounded on 

authority to prevent re-emissions of injected carbon dioxide to the atmosphere. 

The proposed rule defines GS solely for the purposes of protecting Underground 

Sources of Drinking Water (USDWs). Climate legislation is presently being 

drafted in Congress however, and will very likely rely on EPA’s injection 

classes to certify GS. Specifically, the legislation will very likely exempt 

carbon dioxide emissions from large facilities that are geologically sequestered 

according to regulations promulgated by EPA and/or other agencies. We stress the 

importance of EPA being ready and prepared to meet such requirements. Accounting 

protocols for carbon allowances is an issue that can be dealt with outside the 

scope of the current rulemaking, and is likely to have a far narrower remit than 

the current rule’s specific requirements for site screening, monitoring, and 

various plans. EPA, therefore, must define and regulate GS from the outset in a 

way that assures not only that USDWs are not endangered, but that GS for the 

purposes of climate protection is also taking place. 

Response: EPA clarifies that the scope of the GS regulation is limited to injection of CO2, and that all 

requirements in the GS rule are designed for the purpose of protecting USDWs from endangerment. 

Consequently, this comment is outside the scope of the rulemaking. The SDWA does not provide the 

UIC Program with the authority to develop regulations for all areas related to GS, such as releases to the 

atmosphere. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

To protect USDWs from endangerment and meet the potentially fast pace of GS deployment, EPA is 

using an adaptive approach to regulating CO2 injection for GS. The Agency plans to collect and review 

data every six years on GS projects to determine whether the appropriate amount and types of 

information and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. An adaptive approach will allow regulatory development to 

proceed in time to meet the current and future demands for Class VI permits while EPA continues to 

gather data from pilot projects and other research as it becomes available. 

Commenter Name: George Peridas Letter ID: 0291

Commenter Organization: Natural Resources Defense Council Comment ID: 25287

796
Comment: In my opinion, the best way to resolve is to attack it from a broad standpoint 

of changing the way you burn it, changing the way you do that type of process. I 

don't know how far they've gotten in the past five years, technology has changed 

so drastically in likely the way we attack different problems, with chemicals, 

with types of things that they can inject into the carbon to get different 

results, where you could actually isolate the carbon dioxide molecule, that kind 

of thing. But people have been working on that. 

Anyway, I'd like to see a little more money and focus put towards that rather 

than putting this crap in the ground. It's just, to me it's a bad idea, and it's 

not really a problem, and it gets us by for a while, sure. But in the long run 

our kids are going to pay for it. Thank you. 

Response: EPA clarifies that the UIC program’s authority under SDWA is focused on ensuring 

protection of USDWs from endangerment. The capture of CO2 is outside of the scope of the Class VI 

GS rulemaking. 

EPA does not believe that a properly managed GS site is dangerous. The Class VI GS regulation builds 

upon the long-standing protective framework of the UIC program, which has been regulating the 

injection of billions of gallons of liquids for decades. The Class VI GS regulation enhances this existing 

framework with requirements for Class VI wells that are tailored to the unique nature of large scale GS 

of CO2. These additional protective requirements include more extensive geologic testing, detailed 

computational modeling of the AoR and periodic re-evaluations, detailed requirements for monitoring 

and tracking the CO2 plume and pressure front, and extended post-injection monitoring and site care. 

Comment: MR. KALLIO: My name is Brad Kallio. I have a little research company in Grand 

Rapids, Michigan. We try our best to solve different types of problems with 

energy and what have you. 

And the easiest way to say it would be, wind generation is something that's 

going be used for years and years and years. -- uses the old, big windmill. They 

don't move real fast, they don't chop a lot up, we don't have birds hitting them 

and getting cut in half, which they do have in -- they're moving very slow. 

But what we do with wind, especially in these areas here, is that when you got a 

whole amount of wind, has anybody ever wound a cuckoo clock, pull the little 

chains up and the weight goes up, and it keeps the little pendulum going? Same 

principle, only instead of lifting a little metal weight you're lifting, like 

what he wants to do, his whole house. 

But any mass is a lot of weight if you lift it up. And as soon as it gets to a 

certain height it clicks over to another gear system. And then the wind keeps 

blowing, picks up another one, and another one, and another one. You can do a 

whole sequence of these along the shoreline or anything like that. 

Now, you're not storing your energy in batteries, you're storing your energy in 

Commenter Name: Brad Kallio Letter ID: 0502

Comment ID: 21232

Commenter Name: Brad Kallio Letter ID: 0502

Comment ID: 21233

797
gravity. And when you don't have wind you can also use solar to generate motors 

to do the same thing. It's just like a windmill kind of thinking, you pull it up 

and you store it. It goes into a fly wheel at the other end, with a generator on 

the other end of it now you've get a turbine generator just like you have in a 

coal mining plant with no emissions. You can build these anywhere. 

And this is only one way of doing it. There's dozens of other ways, any 

difference in potential from one to the other you can harness and turn it into, 

drive into a system like that, and now you're not polluting at all. 

So I believe in keeping it simple, the Romans did this kind of stuff that moves 

water from one point to another, it's old technology but we can apply it to what 

we have today. I mean, that's more efficient than ever having to burn coal or 

oil or any of this stuff. That's what I had to say. 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. However, the use of and investment in these 

technologies is outside the scope of the Class VI GS rulemaking. The Class VI GS requirements are 

designed to ensure that, where GS is deployed, projects are permitted, sited, constructed, operated, and 

closed in a manner that protects USDWs from endangerment. 

Comment: Now, there are some, a couple other things. While the EPA is very careful about 

saying that this does not cover Clean Air Act there are other things that they 

should admit that it does not cover. The EPA's permitting process cannot affect 

landowners' property rights. And the proposed rule should point this out 

explicitly. 

For example, there's an ADM sequestration test in the middle of Decatur, 

Illinois, it's in a sandstone formation. But if that were in limestone it would 

undermine the City of Decatur I think they'd be pretty upset that it was 

asserted that the EPA permit prevented them from recovering against ADM. 

Response: EPA clarifies that pore space ownership and surface and subsurface property and mineral 

rights are outside of the scope of the Class VI GS rulemaking; these are under the purview of states and 

any of these issues, as they relate to GS, will need to be addressed though state regulations. The Class VI 

GS requirements are designed to ensure that, where GS is deployed, projects are permitted, sited, 

constructed, operated, and closed in a manner that protects USDWs from endangerment. 

In a separate rulemaking under authority of the Clean Air Act, EPA is amending the Greenhouse Gas 

Reporting Program at 40 CFR Part 98 to add reporting requirements for CO2 injection and geologic 

sequestration. The greenhouse gas reporting requirements build on the requirements outlined in the 

Class VI GS rule with the additional goals of verifying the amount of CO2 sequestered and collecting 

data on any CO2 emissions to the surface from GS facilities. 

Commenter Name: Mark Singer Letter ID: 0504

Commenter Organization: Green America Project, LLC Comment ID: 21250

Commenter Name: Leslie Glustrome Letter ID: 0527

Comment ID: 21410

798
Comment: Lastly, another thing I would like to remind EPA and all of the participants is 

that Tom Friedman and his recent focus point book has pointed out that Americans 

are learning that we can no longer be "as dumb as we want to be" and that 

nothing will happen. We have seen what has happened on Wall Street. We have seen 

what happened in Iraq that was unjustified. Right now, we are flying on the 

assumption that we have two hundred years to rely on coal energy in this 

country. Anybody who says that has not read the U.S.G.S (United States 

Geological rvey) reports on coal availability. That should be, in my mind, part 

of the preamble to this so that we, as a country, can come to face the fact that 

we actually only have a very small percentage of that "200 years." A most recent 

study tells us about 6%. Six percent of 200 is about 12 years depends upon how 

we look at the Powder River field up in Wyoming. So the reality is very 

different than what we have been told in the media. As Americans we like to 

think this is not unusual actually. We have been told lots of things that were 

not exactly true, so it is time to sit up, pay attention and demand answers, not 

demonstrate what we want them to be. 

Next I would like to point out that life does not follow models. You can do 

anything on a computer. You can make assumptions about anything and when you 

look at the models that have been used, Mike Celia models or whoever you want to 

use, they make assumptions that basically determine the outcome. In the real 

world, it does not work that way. As a simple, but I think a very important 

example, I am trained as a biochemist, I worked at the University of Colorado 

for eight years, I have worked at lots of other places, but that is one of the 

things I have done. During that eight years working with people who were highly 

trained scientists, as I try to remember it, we had at least six incidents where 

someone left the water running and the drain plugged one way or another. That 

meant that a highly expensive lab flooded and the water comes leaking through to 

the lab underneath destroying and many times very expensive, extremely expensive 

scientific equipment. In eight years, my memory is six of those occurrences. Now 

we happen to have been in sort of penthouse lab which meant we were on the top 

floor, so you might think we might have been immune from such a thing, but in a 

separate set of incidences, all of the HVAC equipment is up on that ceiling and 

I remember at least three times when the guys who were in, maybe women, but the 

guys who were fixing the HVAC equipment did something so our lab flooded and we 

lost very expensive, both results and scientific equipment so stuff happens. 

Life does not happen the way models tell you it is going to happen. We have 

better ways to do this. We aren't just talking about boiling water when we are 

burning coal. We can boil water too by using concentrating, solar power. We can 

ship the electrons instead of shipping the coal over in nineteen century 

railroad system. We do not have as much coal as we have been told anyway, so all 

Response: EPA acknowledges this comment. The purpose of the Class VI GS rule is to ensure 

consistency in permitting underground injection of CO2 at GS operations across the United States and 

provide requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to 

reduce CO2 emissions. EPA clarifies that setting the scale of GS deployment and addressing the 

availability of coal are outside the scope of the Class VI GS rulemaking. 

Commenter Name: Dag Nummedal Letter ID: 0533

Commenter Organization: Colorado Energy Resource Institute Comment ID: 21479

799
Other EPA Comment Codes and Descriptions: 1660 1.3.6 Ecosystem impacts (soil, air, surface 

water) 

Comment: The last part then gets at the biosphere. A lot of people think I believe that 

the subsurface beneath our feet consists mostly of rocks only. It does not. 

Turns out that we have a very extensive community of microorganisms that go deep 

down. In the deepest gold mines in South Africa, people are recovering microbes. 

And these microbes play a fundamental roles in the geochemical and radiological 

reactions. In fact in all different rocks, whether they be hard rocks where we 

get gold and silver and copper and whatnot, there are organisms related and are 

present in both deep hard rock mines, those organisms that are found on 

limestones. We can look at that as potentially large carbon sequestration. 

Reservoirs contain a lot of bacteria, microbes in coal. Coal seams potentially 

are great places to store CO2 partly because some of the microbes will actually 

use the hydrogen as in the electron donor and then reduce the CO2 into methane. 

And we add hydrogen to the C and the O's and it produces methane and oxygen and 

water. And then if you can get that reaction to work in commercial and 

industrial settings in the subsurface, then you can actually use CO2 in the 

subsurface, in the coal seams, the same way that we are increasingly using CO2 

in algal farms. Algal biofuels which most people are strongly in favor of. 

Environmentally algal biofuels are probably very good and what you do of course, 

algae have to eat something, they eat CO2. Now if you can get the microbes in 

this subsurface, in the coal seams, to do the same thing basically converting 

that CO2 into methane and regenerate the methane, you can have a sustained 

production of methane which can be trapped and captured and used as it leaves a 

much cleaner fuel than coal and oils for a long time while you are storing CO2 

in the process. I think it is a very encouraging future technology. 

And that will then also be a significant part of the research that we are 

attracted, that we are here proposing. 

Response: EPA acknowledges that there are potential risks associated with GS. The purpose of the 

Class VI requirements is to minimize and mitigate potential/identified risks through proper site 

characterization, well construction, operation, monitoring, post-injection site care, and site closure and 

to ensure protection of USDWs. The Agency clarifies that, under SDWA authority, the requirements do 

not explicitly protect against CO2 leakage to the surface. However, the GS rule requires that CO2 

injected for GS remain confined in the injection zone. Leakage outside of the injection zone/to the 

surface would be a permit violation. 

In response to the comment suggesting "harnessing biological activity"—such as underground 

microbes—to consume CO2, the Agency clarifies that the GS rule does not preclude or endorse the use 

of specific technologies (e.g., microbes) for GS provided they are used in conjunction with appropriately 

sited, constructed, operated, and monitored injection wells to ensure protection of USDWs. 

Comment Code: 1320 1.1.3 General comments about GS 

Individual Comments 

800
Comment: Hi, MaryRose. My name is Rebecca, and I teach school for the Mendocino 

County Water Agency. I'm pretty confused about carbon sequestration, and 

wondered if you could enlighten me. I have a difficult time picturing carbon, 

and wonder how it is sequestered. Is it in a gas or liquid form? If it's a gas 

and injected into the ground, wouldn't it be able to seep between rocks and get 

into our water supply? Is it stored in tanks? Someone told me it's injected into 

coal, then buried? Could we inject it into old coal mines and seal it up? Even 

our most knowledgeable around here are stumped on this one. Thank you. 

Response: GS is the process of injecting CO2 captured from an emission source (e.g., a power plant or 

industrial facility) into deep subsurface rock formations for long-term storage. It is part of a process 

known as “carbon capture and storage” (CCS). When injected into an appropriate receiving formation, 

CO2 is sequestered by a combination of trapping mechanisms, including physical and geochemical 

processes. Please see the preamble and materials in the docket for additional information. 

Comment: The Group Against Smog and Pollution (GASP) has three primary concerns 

regarding the geologic sequestration of CO2: 

1. The potential for adverse chemical reaction of CO2 and its contaminants with 

the water/mineral environment of the host rock. 

2. The need for Class VI wells given the advantages of CO2 enhanced recovery 

methods in existing Class II wells. 

3. What agency will administer and oversee the program? At least five agencies 

could be involved: EPA, DOE, DOT, USGS, and BLM. 

Response: EPA acknowledges that there are potential risks associated with GS, including the potential 

that CO2 injection for GS may result in leaching of subsurface materials that could mobilize 

contaminants or compromise pore space, and therefore injectivity. The purpose of the Class VI 

requirements is to minimize and mitigate potential or identified risks through proper site 

characterization, well construction, operation, monitoring, post-injection site care, and site closure. To 

ensure USDW protection and mitigate risks, the GS regulation requires the owner or operator of a Class 

VI well to submit data about the site (during the site characterization process), including information on 

the porosity, permeability, mineralogy, and geochemistry of the injection and confining zones, along 

with information on the compatibility of the CO2 stream with fluids in the injection zone and minerals 

in both the injection and confining zones (§146.82). This data can help identify potential geochemical 

reactions that may occur between the injected CO2 and the host geologic formation. Identification of 

potential reactions prior to injection would address concerns that formation of carbonic acid could 

dissolve potential limestone creating karst features. 

Regarding EOR wells, EPA recognizes that the oil and gas industry has decades of experience injecting 

CO2 for the purpose of ER, and that sites used for ER may be suitable for GS and may be among the 

first GS sites. However, the Agency believes that the nature of CO2 injection for the primary purpose of 

long term storage poses different risks than injection for the primary purpose of ER, and therefore has 

developed new Class VI regulations to address these unique risks. For example, the volume of CO2 

Letter ID: 0102

Commenter Organization: Mendocino County Water Agency, State of CaliforniaComment ID: 21938

Commenter Name: Herbert Skolnick, Ph.D. Letter ID: 0110

Commenter Organization: Group Against Smog and Pollution, Inc. (GASP) Comment ID: 22035

801
anticipated to be injected for long term storage is significantly greater than for ER operations. Reservoir 

pressure conditions will also be different, with Class VI injection operations involving large volumes of 

CO2 and likely having higher pressures within their storage formations than Class II ER projects. 

EPA clarifies that the Agency's UIC program or states with primary enforcement responsibility will 

oversee GS projects. 

For additional information on EPA’s final regulatory approach (including well construction 

requirements, monitoring, and post-injection site care and closure), please see the final rule and 

preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1940 1.4.4.3 Consultations with Industry; experience 

with other wells 

Comment: EPA has correctly recognized that wells are a fundamental component of a 

geologic storage system that successfully ensures the containment of stored CO2. 

As such, we agree that having appropriate well design, construction & operating 

requirements are critical to the delivery of secure storage of CO2. 

Oil and gas operators have decades of experience, via past and existing 

operations, in constructing and operating EOR/EGR wells in a safe and secure 

way. For existing EOR projects and wells, Class II requirements have proven to 

be sufficient at ensuring the necessary protection of USDWs, and, therefore, 

analysis of the experiences and performances of these Class II CO2 EOR wells 

should inform the requirements for new Class VI wells. 

Response: EPA recognizes that the oil and gas industry has decades of experience injecting CO2 for the 

purpose of ER, and that sites used for ER may be suitable for GS and may be among the first GS sites. 

Some of the research that informs the final GS rule was conducted at ER sites. EPA also recognizes that 

a by-product of ER activities is that a certain percentage of the CO2 is trapped in the receiving 

formation. 

In addition, EPA is using an adaptive approach to regulating GS under the UIC Program. Even after 

finalization of the GS regulation, the Agency plans to collect and review data every six years on GS 

projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Comment: Thank you for the opportunity to speak today. My name is Iain Wright. I work for 

BP and I manage the industrial-scale CO2 geo-sequestration project at In Salah 

in Algeria. BP appreciates EPA's efforts to create a regulatory framework for 

industrial-scale CO2 geo-sequestration in the US. 

At In Salah, BP and its partners (Sonatrach and StatoilHydro) have, for the last 

Commenter Name: Brian Williams Letter ID: 0116

Commenter Organization: BP Alternative Energy Comment ID: 22049

Commenter Name: Iain Wright Letter ID: 0118

Commenter Organization: BP Alternative Energy Comment ID: 22064

802
four years, been sequestering around 1 million tonnes/year CO2 in a deep saline 

formation, which is down-dip of a producing gas field. CO2 storage at In Salah 

is permitted under Algerian hydrocarbon regulations and we have learned a number 

of lessons that could be beneficial for the development of geo-sequestration 

regulations in the US. 

My comments will address three issues: 

1. Well Design, 

2. Monitoring and 

3. The Timeframe for Site Closure 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach (including 

well construction requirements, monitoring, and post-injection site care and closure), please see the final 

rule and preamble as well as the rulemaking docket. 

Comment: - Page 43498. Second paragraph on that page. "However, some CO2 releases from 

injection activities have been documented." Crystal Geyser is not an "injection 

activity" as that term is used in the context of this Class VI rule. The text 

in that paragraph makes it clear that the CO2 which erupts from Crystal Geyser 

is from "improper well plugging." It is technically inaccurate, misleading and 

prejudicial to start off this paragraph by saying "some CO2 releases from 

injection activities have been documented." 

Response: EPA agrees that the Crystal Geyser site is not associated with injection. However, this 

incident demonstrates that abandoned or improperly plugged boreholes can serve as conduits for 

migration of fluids to USDWs. It is for this reason that the final rule includes requirements related to 

performing corrective action on all deficient wells within the AoR at §146.84, and proper injection well 

construction that meets the goals of §146.86. 

Comment: - Page 43495, third column, under "II What is EPA Proposing?" I believe the 

IPCC Special Report on Carbon Dioxide Capture and Storage (IPCC SR on CCS) 

and/or more recent peer reviewed papers can shed light on the timeframes under 

which primary and secondary trapping mechanism begin to operate. Adding some 

quantification to this point would likely help stakeholders better understand 

and be more familiar with CO2 storage. Consider adding something like "Some of 

these trapping mechanisms begin as soon as the CO2 is injected into the host 

formation while others take hundred to thousands of years to run their course." 

I believe one could cite the IPCC SR on CCS to substantiate that point. 

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific 

Northwest National Laboratory

Comment ID: 

22656

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific 

Northwest National Laboratory

Comment ID: 

22672

803
Response: EPA agrees that the IPCC study mentioned is informative. The IPCC report is cited 

extensively in the preambles to the proposed and final rules, and is also available in the rulemaking 

docket. 

Comment: 5. APPA believes that new power plants designed for geologic sequestration 

should be planned for sequestration to be conducted for the "life of the plant"- 

which can be as long as 60 years. However, APPA believes that if some type of 

lateral or vertical migration of the CO2 or other substances (such as brine, 

metals, drilling muds, cement from well failure) is detected and believed to be 

potentially harmful to the underground sources of drinking water (USDW), that 

the power plant or power plants supplying the CO2 to the injection site(s) 

should be given an "infeasibility exemption[FN3]" for sequestration of its CO2. 

This exemption should enable the power plant to continue to operate without 

carbon dioxide injection in that location. Without this "infeasibility" or "back 

out" clause for geosequestration, it is highly unlikely that communities would 

build power generating facilities with carbon capture and injection systems that 

could cost at least $2 billion dollars (2008 dollars) or be able to obtain 

financing if the plant was not expected to operate for the full 50-60 years. The 

financial risks for closure of a power generating plant or multiple plants in a 

region would simply be too enormous. APPA does not believe that anyone should 

presume that the CO2 from power plants to be injected into in situ or distant 

geology should be presumed to exceed 50% of the total CO2 in the first few 

decade of the commercial deployment. APPA has no notion that the future fossil 

power plants with CCS will be carbon neutral given the larger volume of coal to 

be consumed in the gasification process in order to make up for parasitic power 

losses. 

[FN3] For the first generation plants, the "infeasibility exemption" should 

extend beyond infeasibility of the carbon capture operations of the power plant. 

Response: EPA clarifies that regulating power plants is outside the scope of the UIC GS rulemaking, 

and that GS rule does not require any facilities to capture and/or sequester CO2. 

EPA also clarifies that the intent of the Class VI regulations is not to promote or encourage the use of 

GS, but, instead to ensure protection of USDWs where GS technologies are deployed. 

Comment: The EPA’s proposed rule asks for comment on many issues which are new to the 

power sector. EPA does its best to tease out what we know from the use of CO2 

injection/recycling from the oil and gas sector and try to apply some of these 

concepts to the future power sector parties who might need to build coal-fired 

electric generating plants but would be required to reduce emissions of carbon 

dioxide through the combination of carbon capture technology at the plant and GS 

at an injection site. 

Carbon sequestration can employ any of several physical, chemical, or biological 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23377

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23384

804
processes to isolate CO2 from the atmosphere, on a long-term basis. Carbon 

sequestration can be terrestrial and geological. As part of the Earth’s carbon 

cycle, terrestrial sequestration uses vegetation and the soil as carbon sinks. 

There are both technical and non-technical challenges to sequester large 

quantities of CO2 in subsurface repositories. The technical challenges are 

exacerbated by a lack of experience with processes on an appropriate scale, or 

in geologic formations that have no history of oil and gas production. The nontechnical challenges - in the form of legal and regulatory issues - are as 

significant as the technical uncertainties. But APPA supports research in order 

to assist us to make these changes. 

The amount of CO2 that could be required to be sequestered is enormous. The 

generation of power by coal-fired power plants in the U.S. produces 1.5 billion 

tons of CO2 that, when compressed to supercritical conditions, comprises a 

volume that exceeds that equal to U.S. oil consumption. The task of transporting 

and managing this volume of material is complicated by the need to operate the 

transport in a pipeline at 2,000 psig to maintain CO2 in a fluid state in these 

specialty pipelines. 

APPA does not question the viability of the technology of carbon dioxide 

injection for enhanced oil and gas recovery in production fields. Any 

questioning about the technology in the context of these APPA comments pertains 

to new large scale power plant parties which would likely be built outside the 

geologic formations suitable for oil and gas recovery. While the proposed rule 

asked for comments on the impacts on other industries, these APPA comments focus 

on power plants. We don't offer comments on carbon separation and 

injection/storage for ethanol plants, chemical companies, cement factories, or 

coal bed methane plants that might have similar opportunities to inject CO2. 

APPA has no comments on more shallow methane recovery from coal operations. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. As described above, the GS rule does not 

require any facilities to capture and/or sequester CO2. 

Comment: Our comments pertain to large scale power plant applications and those much 

larger CO2 injections and storage in geologic formations. There may be 

opportunities in the early years for the placement of coal plants for 

geosequestration in the shadow of the oil and gas industry where there would be 

opportunities for EOR/EGR. APPA encourages this and believes that this may be 

beneficial to many parties-including the power sector. If all new coal power 

plants could be built over geologic formations that have oil and gas recovery 

operations or where the CO2 could be stored in depleted wells, the economics 

would be far more favorable for the power sector. However, even if that were the 

case, the drinking water protection issues do suggest some initial caution in 

site selection. 

Response: EPA acknowledges the comment. As described above, the GS rule does not require any

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23386

805
facilities to capture and/or sequester CO2. Please see the remainder of EPA’s responses to this comment 

for further details. 

Other EPA Comment Codes and Descriptions: 5600 2.11 Comments related to UIC Program primacy 

for Class VI wells 

Comment: Because state regulators in approximately five or six states have worked 

extensively with Owners or Operators of UIC Class V experimental CO2 wells they 

have familiarity with environmental, geologic, and financial concerns specific 

to a given region, their adoption and tailored implementation of the CO2 GS 

rules will be crucial to the success of the Program. 

Response: EPA acknowledges the expertise of existing State, Tribal, and Territorial programs that 

implement the UIC requirements under Section 1422 of the SDWA (Class I, III, IV, and V wells 

(particularly Class V experimental technology wells)) and state oil and gas agencies that have been 

regulating Class II UIC wells for decades under section 1425 of SDWA. These agencies already 

understand the technical and administrative issues involved in construction, operation, injection and 

permitting as well as, in the case of Class II operators issues related to CO2 injection, subsurface 

operations, and pipeline transport. EPA believes that existing programs can adapt this expertise to the 

new requirements for Class VI wells and will be able to develop a primacy application for Class VI 

wells under section 1422 of SDWA. 

Many of the tools, resources, expertise, and infrastructure currently exist within States to effectively and 

efficiently manage GS projects. Additionally, States can use multiple authorities beyond those afforded 

under the SDWA and UIC regulations including surface access and land rights, unitization of fields, 

pore space ownership, mineral rights, site safety and emergency preparedness, and maximization of 

State oil and gas resource exploitation. 

Comment: Regulation of GS under the UIC program will have a direct impact on Ameren, 

particularly our fossil-fired facilities involved in the production of 

electricity and we have a substantial interest in EPA's development of a 

realistic and cost-effective UIC program for Class VI CO2 GS wells 

Response: EPA acknowledges the comment. EPA clarifies that the GS rule does not require any 

facilities to capture and/or sequester CO2. Please see the remainder of EPA’s responses to this comment 

for further details. For additional information on EPA’s final regulatory approach, please see the final 

rule and preamble as well as the rulemaking docket. 

Comment: The development of a viable CO2 capture and sequestration regulatory program has 

been cited by many as a prerequisite to the implementation of energy reform 

initiatives involving carbon reduction measures on both the federal and state 

level. Because the electric utility industry has been identified as the primary 

industrial sector targeted for regulation under future carbon capture and 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23403

Commenter Name: Paul Pike Letter ID: 0198

Commenter Organization: Ameren Corporation Comment ID: 23936

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 22895

806
sequestration (CCS) regulations, the electric utility industry has a direct and 

substantial interest in EPA's development of a realistic and cost-effective UIC 

program for Class VI CO2 GS wells. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: I. General Statement: 

The North American Coal Corporation believes that a diverse fuel supply is 

imperative to the economic health of our country. Affordable and reliable 

electricity, which is created in an environmentally friendly manner, forms the 

cornerstone for our country’s economy and creates a healthy society. Lignite 

coal is a vital part of this diverse fuel supply. 

Coal and the low-cost electricity it provides are vital to the reliability of 

the U.S. electric supply system, and to the economic vitality of the U.S. 

economy. Coal production and related electrical generation account for some 

hundreds of billions of dollars of U.S. gross domestic output, over a hundred 

billion dollars of annual household income, and millions of jobs. 

Lime rock in Florida is used as aggregates in the construction of buildings and 

roads and as a feedstock for cement production. As such, lime rock is a 

critical component for the growth of the region: It is literally the foundation 

for any building project. 

Coal-fired power plants and cement kilns all produce carbon dioxide (CO2). If 

legislation or regulations are promulgated that restrict the emission of carbon 

dioxide, then many of these facilities will need to capture and sequester CO2. 

Thus, NAC’s customers will be impacted by the proposed regulations. 

Furthermore, as a natural resource producer, NAC will be directly impacted by 

any rule that affects the subsurface of the Earth. Lignite-fired power plants 

and cement kilns are all "mine mouth" facilities. That is to say, the mine is 

literally next door to the facility. If the facility (and/or others in the 

area) sequester CO2 in subsurface formations, then lands and resources 

controlled by NAC could be adversely affected. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: developmental aspects of CCS activities in both the U.S. and Canada. As we noted in 

Commenter Name: Dennis R. James Letter ID: 0214

Commenter Organization: North American Coal Corporation (NAC) Comment ID: 22956

Commenter Name: Michael Moore Letter ID: 0265

Commenter Organization: North American Carbon Capture & Storage 

Association (NACCSA)

Comment ID: 

22848

807
our oral and written testimony presented at EPA's September 30, 2008 public 

hearing on the proposed rules, policymakers and companies are, and should be, like 

the members of NACCSA,interested in CCS technology because it holds significant 

promise as a tool to manage CO2 emissions as well as to maximize energy recovery. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1280 1.1.2.1 General comments on climate change/ 

global warming 

Comment: Assessment of the Proposed Rule The proposed rule repeatedly references climate 

change mitigation by the injection of CO2 as the justification for the need for 

the new class of injection well: 

Summary: "EPA is proposing Federal requirements under the Safe Drinking Water 

Act (SDWA) for underground injection of carbon dioxide (CO2) for the purpose of 

geologic sequestration (GS). GS is one of a portfolio of options that could be 

deployed to reduce CO2 emissions to the atmosphere and help to mitigate climate 

change." 

And "If finalized, this proposal would help ensure consistency in permitting 

underground injection of CO2 at GS operations across the U.S. and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual 

use of GS to reduce CO2 emissions." 

In Part II "What is the EPA Proposing" the proposition reiterates: 

"In addition to protecting USDWs, today’s proposed rule provides a regulatory 

framework to promote consistent approaches to permitting GS projects across the 

U.S. and supports the development of a key climate change mitigation 

technology." 

Under Part II A. "Why Is EPA Proposing To Develop New Regulations To Address GS 

of CO2?" Part II. Section 2, states: The Intergovernmental Panel on Climate 

Change (IPCC) has concluded that much of the warming in recent decades is very 

likely the result of human activities (IPCC, 2007). The burning of fossil fuels 

(e.g., from coalfired electric plants and other sources in the electricity and 

industrial sectors) is a major contributor to humaninduced greenhouse gas 

emissions. 

Fossil fuels are expected to remain the mainstay of energy production well into 

the 21st century, and increased concentrations of CO2 are expected unless energy 

producers reduce the CO2 emissions to the atmosphere. The capture and storage of 

CO2 would enable the continued use of coal in a manner that greatly reduces the 

associated CO2 emissions while other safe and affordable alternative energy 

sources are developed in the coming decades. Given the United States’ abundant 

coal resources and reliance on coal for power generation, CCS could be a key 

Commenter Name: Mary Munn Letter ID: 0273

Commenter Organization: Fond du Lac Reservation Comment ID: 24082

808
mitigation technology for achieving domestic emissions reductions" 

And: 

"Congressional climate change legislative proposals (the McCain-Lieberman bill 

S. 280, the Bingaman-Specter bill S. 1766, and the Lieberman-Warner bill S. 

2191) indicate that CCS has the potential to play a significant role in climate 

change mitigation scenarios." 

And: 

"Today’s proposal provides a regulatory framework to protect USDWs as this key 

climate mitigation technology is developed and deployed." 

The allusion of mitigating climate change or reducing CO2 emissions by geologic 

sequestration cannot be fairly used as persuasive point for this rule without 

providing data demonstrating the mass balance of energy and carbon dioxide in 

the whole system. A great deal of analysis has been completed and posted on the 

docket of cost and incremental cost within the proposed rule for CCS and GS 

implementation but no analysis is made in terms of the actual amount carbon 

dioxide that will be sequestered in relation to the amount of carbon dioxide 

emitted throughout the process (Cost: EPA-HQ-OW-2008-0390-0073 and EPA-HQOW-2008-0390-0094). 

A mass balance of the participating fossil energy processes, generating the CO2, 

must be evaluated to determine if any real reduction in CO2 can be made. CO2 is 

emitted during the excavation and transport of the fossil fuel to a power plant. 

Additional power will be required, and will emit additional CO2, to provide the 

energy to extract the CO2 from the emission stream, to compress, transport, and 

to inject the CO2 into a geologic formation. 

Response: EPA clarifies that the Class VI GS requirements are designed to ensure consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce 

CO2 emissions. The requirements apply to owners or operators of injection wells used to inject CO2 for 

permanent storage. 

GS is one technology in a portfolio of options, including energy conservation, efficiency improvements, 

and the use of alternative fuels and renewable energy sources, that could be deployed to reduce CO2 

emissions. However, the use of and investment in these technologies is outside the scope of the Class VI 

GS rulemaking. The Class VI GS requirements are designed to ensure that, where GS is deployed, 

projects are permitted, sited, constructed, operated, and closed in a manner that protects USDWs from 

endangerment. 

Comment: We are writing in relation to EPA’s ongoing efforts to regulate the geologic 

sequestration of carbon dioxide (GS). We believe that a truly sustainable energy 

system will utilize opportunities to increase energy efficiency and renewable 

energy first and foremost. However, the vast majority of our energy in the U.S. 

Commenter Name: Scott Anderson Letter ID: 0295

Commenter Organization: Environmental Defense Fund Comment ID: 26136

809
and worldwide is still produced from fossil fuels, and this is likely to 

continue for some time. Faced with a rapidly changing climate, we believe that 

carbon capture and geologic sequestration (CCGS) can and should play an 

important role in reducing greenhouse gas emissions in the near term. 

Response: EPA acknowledges the comment. EPA clarifies that the purpose of the UIC GS regulation is 

to ensure that GS is conducted in a manner that protects USDWs from endangerment. EPA agrees that 

GS is one technology in a portfolio of options, including energy conservation, efficiency improvements, 

and the use of alternative fuels and renewable energy sources, that could be deployed to reduce CO2 

emissions. However, the use of and investment in these technologies is outside the scope of the UIC GS 

rulemaking. The Class VI GS requirements are designed to ensure that, where GS is deployed, projects 

are permitted, sited, constructed, operated, and closed in a manner that protects USDWs from 

endangerment. 

Please see the remainder of EPA’s responses to this comment for further details. For additional 

information on EPA’s final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: It is clear that industry and people believe that CO2 sequestration is possible 

even though there are no long-term studies available -- for the storage over 

long periods of time. 

Response: The UIC Program’s authority under the SDWA focuses on ensuring that GS projects are 

permitted, sited, constructed, operated, monitored, and closed in a manner that is protective of USDWs. 

Ensuring storage capacity is outside the scope of the UIC GS rulemaking. 

EPA clarifies that other federal agencies (e.g., DOE and the U.S. Geological Survey) have conducted 

research on available storage capacity and determinations of the feasibility of capturing and storing CO2 

at the scales needed to address climate change. These agencies, along with private entities, have 

identified large areas for potential sequestration in capacity studies. For example, in 2008, USGS 

initiated development of a methodology for estimating the capacity to store CO2 in geologic formations 

of the US. In 2010, USGS finalized and published a risk-based methodology for GS capacity estimation. 

"A Probabilistic Assessment Methodology for the Evaluation of Geologic Carbon Dioxide Storage" is 

available at http://pubs.usgs.gov/of/2010/1127/. 

Comment Code: 1330 1.1.3.1 Support use of GS in general 

Individual Comments 

Other EPA Comment Codes and Descriptions: 1680 1.3.8 Don't overstate risk, don't stigmatize CO2 

Commenter Name: Lee Sprague Letter ID: 0505

Commenter Organization: Sierra Club Comment ID: 21234

Commenter Name: Karl R. Moor Letter ID: 0109

Commenter Organization: Southern Company, on behalf of Edison Electric 

Institute (EEI)

Comment ID: 

21992

810
Comment: Key Messages 

We have two key messages for EPA today: 

First, the regulations can and should promote the development and deployment of 

carbon capture and storage while protecting underground sources of drinking 

water without unduly stigmatizing carbon dioxide injection and storage. Carbon 

dioxide has been injected for years for enhanced oil recovery and enhanced gas 

recovery without incident. 

Response: EPA does not believe that the GS regulation stigmatizes CO2 injection. However, EPA 

believes that injecting large volumes of CO2 for GS poses unique challenges that, if not properly 

managed, could endanger drinking water sources and have other adverse impacts. The final, tailored, 

Class VI requirements address the large volumes of CO2 injected, its buoyancy, potential corrosivity in 

the presence of water, and potential impurities in the CO2 stream. In addition, EPA expects the tailored 

permitting, siting, construction, operation, monitoring, and post-injection site care requirements in the 

GS rule to prevent leakage from injection formations and protect USDWs. 

EPA believes that building upon the existing UIC requirements (e.g., Class I and Class II well 

requirements) to develop the Class VI GS regulation provides a foundation for protecting USDWs based 

on success, field experience, and lessons learned about CO2 injection in other applications. Class I well 

owners or operators have experience with site characterization, well construction, and monitoring 

procedures and technologies that are applicable to Class VI wells. Class II ER well operators have 

experience with managing the unique properties of CO2. To successfully flood a hydrocarbon field with 

CO2 during an ER operation, the behavior of injected CO2 must be well understood. 

Comment: Energy (DOE). We share the EPA’s belief that CO2 sequestration has the potential 

to improve air quality. We further believe that the best way to promote 

economical geosequestration of CO2 initially is to link captured CO2 with oil 

reserves, producing increased petroleum recovery efficiencies. 

Texas is a leader in enhanced oil recovery using CO2. Texas possesses an 

extensive oil and gas pipeline infrastructure capable of transporting CO2 to 

various sequestration sites. The first CO2 flood occurred in 1972 in West Texas. 

In 2005, over 160,000 barrels of oil per day were produced with CO2 EOR in 

Texas. The RRC has permitted over 11,200 CO2 injection wells, with over 5,400 of 

those being currently active. The 50 active CO2 enhanced oil recovery projects 

in West Texas represent about 50 percent of total CO2 flooding activity 

worldwide. CO2-driven EOR has grown steadily since 1985 and now accounts for 

over 15 percent of the average yearly oil production in Texas. The oil industry 

has experienced a supply shortage of CO2 over the past few years. Finding new 

sources of CO2 will alleviate that shortfall and result in an increase in oil 

production. The current shortage is about 0.5 billion cubic feet per day, with 

industry consuming the available 1.5 billion cubic feet per day. Increased 

availability of anthropogenic CO2 could accelerate this production. In April of 

2004, the University of Texas Bureau of Economic Geology identified at least 31 

billion barrels of oil in Texas that are recoverable using CO2-driven EOR. 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24730

811
The RRC has primacy over Class II wells and Class III brine mining wells in 

Texas. Texas has been regulating injection wells since the 1930s. With nearly a 

Response: EPA clarifies that injection of CO2 for the purposes of enhanced oil and gas recovery will 

continue to be permitted under the Class II program, as long as any oil or gas production is occurring. 

The UIC GS requirements will apply to wells used for the purpose of long-term GS. 

Please see the remainder of EPA’s responses to this comment for further details. 

For additional information on EPA’s approach to wells that are transitioning from ER to GS, see the 

discussion of Class II wells under “How Does This Rule Affect Existing Injection Wells Under the UIC 

Program?” in the preamble to the final GS rule. 

Comment: As the owner of power generation facilities, SEGNA respectfully submits the 

following comments for consideration by EPA. SEGNA supports efforts to curb 

greenhouse gas emissions, including research and investment in carbon capture 

and sequestration (CCS) technology. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1000 1. General and Administrative Comments 

Comment: ODEC supports the comments of the Carbon Capture and Sequestration Alliance 

(CCS, or the Alliance) on the proposed UIC regulations. The CCS Alliance is a 

coalition of entities, spanning a number of economic sectors, that share a 

common interest in removing impediments to investment in and development of CCS, 

as well as mitigating the potential risks associated with the deployment ofthis 

technology.[l] Its purpose is to promote development of policy by the states and 

the federal government to appropriately address risks and potential liabilities, 

thereby enabling the further development and increased deployment of CCS. The 

CCS Alliance believes these technologies can be developed while protecting 

underground water resources, significantly reducing global and U.S. greenhouse 

gas ("GHG") emissions, and enhancing u.s. energy security. The Alliance's 

purpose is to consider ways ofpromoting the development and use ofCCS 

technologies and to support effOlis by the private sector, states, the federal 

government, non- governmental organizations and others, to help ensure that 

these technologies can be developed and widely, efficiently and cost-effectively 

deployed. 

Response: EPA clarifies that the purpose of the UIC GS regulation is to ensure that GS is conducted in 

a manner that protects USDWs from endangerment. EPA agrees that GS is one technology in a portfolio 

of options, including energy conservation, efficiency improvements, and the use of alternative fuels and 

renewable energy sources, that could be deployed to reduce CO2 emissions. 

Commenter Name: Carl Carlsson Letter ID: 0131

Commenter Organization: SUEZ Energy Generation NA, LLC Comment ID: 21524

Commenter Name: Kenneth Alexander Letter ID: 0146

Commenter Organization: Old Dominion Electric Cooperative (ODEC) Comment ID: 21726

812
Please see the remainder of EPA’s responses to this comment, and CCS Alliance’s comment for further 

details. For additional information on EPA’s final regulatory approach, please see the final rule and 

preamble as well as the rulemaking docket. 

Comment: Simply stated, CCS involves separating and capturing CO2, transporting the CO2 

by truck or pipeline to an underground storage location, and injecting and 

storing it in underground geologic formations. While CCS is just one of many 

climate change mitigation options,[FN2 Other options include energy efficiency 

improvements, a switch to less carbon-intensive fuels, nuclear power, and 

renewable energy sources.] it will be a vital component of any U.S. strategy for 

addressing climate change given our reliance on coal for almost half of our 

electricity production. Likewise, CCS could have a substantial role in reducing 

CO2 emissions from developing countries, such as India and China, where CO2 

emissions are projected to increase exponentially in connection with their 

growing energy needs. 

Response: EPA clarifies that the purpose of the UIC GS regulation is to ensure that GS is conducted in 

a manner that protects USDWs from endangerment. EPA agrees that GS is one technology in a portfolio 

of options, including energy conservation, efficiency improvements, and the use of alternative fuels and 

renewable energy sources, that could be deployed to reduce CO2 emissions. Please see the remainder of 

EPA’s responses to this comment for further details. For additional information on EPA’s final 

regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1410 1.2.1 Comments in support of EPA/rulemaking 

Comment: As part of the U.S. strategy for addressing climate change and implementing CCS, 

EPA has proposed a first-time rule under the SDWA for sequestering CO2 in 

geologic formations. The proposed rule is based on EPA’s existing regulatory 

framework for its UIC Program and proposes a new category of injection well 

(Class VI) along with several technical criteria for its implementation. 

The Chamber strongly supports the development and deployment of carbon capture 

and sequestration technology, and we applaud EPA for its extensive public 

outreach, stakeholder dialog, and public workshops on this issue. Nevertheless, 

in order to ensure that this proposed rule accomplishes its objectives to 

promote a CCS regulatory framework and support "the development of a key climate 

change mitigation technology," the Chamber offers the following comments on 

potential legal, economic, regulatory, and technical barriers to CCS deployment 

that EPA should consider before finalizing this rule. 

Response: EPA agrees that input of and participation by a wide spectrum of stakeholders is a vital 

component of a successful rulemaking. The Agency appreciates the degree of cooperation, participation, 

and active dialogue between the EPA and stakeholders and will continue to work with stakeholders and 

experts as it implements the GS rule. 

EPA believes that the creation of a new injection well class (VI) under the existing UIC Program is 

Commenter Name: William Kovacs Letter ID: 0148

Commenter Organization: U.S. Chamber of Commerce Comment ID: 21748

Commenter Name: William Kovacs Letter ID: 0148

Commenter Organization: U.S. Chamber of Commerce Comment ID: 21749

813
necessary to enable deployment of GS as a climate change mitigation technology in a manner that 

protects USDWs from endangerment. EPA agrees that the UIC Program, under the authority of the 

SDWA, provides a strong framework for regulating injection of CO2 for GS and adds that the GS 

regulation tailors the UIC requirements to address the unique issues associated with large-scale GS 

including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, 

the potential presence of impurities in captured CO2, and its mobility within subsurface geologic 

formations. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

Other EPA Comment Codes and Descriptions: 1000 1. General and Administrative Comments 

Comment: To whom it may concern: 

I appreciate the opportunity to provide comments on the proposed rules for 

federal management of geologic sequestration of CO2 in Docket ID No. EPA-HQOW-2008-0390. This is a unique opportunity to broaden our national public policy 

foundation by melding new federal energy policy with responsible natural 

resource policy and, in so-doing, expand economic opportunities and potentially 

reduce the amount of CO2 that is introduced into the atmosphere. As currently 

written, provisions of the proposed rules related to the suitability of specific 

reinjection locations cause serious concern. 

Wyoming has been proactive in its stewardship of all state resources and we 

recognize the need for environmental regulation. Over the years we have 

demonstrated our regulatory capability by meeting and often exceeding EPA 

standards in managing activities that impact public health, public safety and 

all public resources. We are eager to collaborate with the federal government 

yet again, to craft rules that work not only for the interests of the nation but 

that also work directly for the people of Wyoming. Within the framework of this 

collaborative undertaking, the importance of including local expertise and 

knowledge into the regulation of CO2 sequestration is necessary to ensure public 

safety while also providing new growth opportunities for a vibrant new 

industry. 

Response: EPA recognizes the importance of states having primacy for GS wells given the variety of 

geologic settings in which GS will be applied. EPA recognizes that State, Tribal, Territorial, and DI UIC 

Commenter Name: Dave Freudenthal Letter ID: 0150

Commenter Organization: State of Wyoming Comment ID: 22216

814
program Directors are in the best position to evaluate the unique issues related to well depth, geology, 

and hydrogeology that are posed by a Class VI well. Some degree of flexibility is needed for Class VI 

wells because each decision made will be site-specific and conditions will differ from state to state. The 

GS rule balances the need for these site-specific decisions with the need for minimum Federal 

requirements to ensure national consistency while ensuring the protection of USDWs. 

EPA also believes that providing states the flexibility to obtain primacy for Class VI wells 

independently of other well classes can help foster effective management of CCS. EPA believes that 

allowing independent Class VI primacy may encourage states to take responsibility for implementation 

of Class VI regulations and provide for a more comprehensive approach to managing CCS projects by 

promoting the integration of GS activities under SDWA into a broader framework for managing CCS. 

Furthermore, GS operations involve ancillary activities (e.g., pipeline operations, pore space ownership, 

land use rights, and surface access) for which states can call upon other authorities that exist at the state 

level (but outside UIC authority) to provide a more comprehensive CCS management approach. The 

Agency will allow independent primacy for Class VI wells under §145.1(i) of the final GS rule. 

For additional information on EPA's final regulatory approach, please see the final rule and preamble as 

well as the rulemaking docket. EPA is using an adaptive approach to regulating GS. 

Other EPA Comment Codes and Descriptions: 1350 1.1.3.3 Comments on the need for GS 

technology 

Comment: Given public concern over climate change, pending legislative proposals to 

sharply curtail carbon dioxide (CO2) emissions, and estimates that energy 

companies based in Houston and elsewhere could use anthropogenic CO2 to produce 

billions of barrels of oil that would otherwise not be produced, the 

Partnership believes it is important that carbon capture and storage (CCS) 

technologies become commercially available as soon as possible. In the near 

term, strategies employing CO2 sequestration for Enhanced Oil Recovery (EOR) will 

help commercialize the carbon capture technology and will help demonstrate the 

technology necessary for long-term storage of CO2 as a predicate to larger-scale 

CCS projects. The Partnership strongly supports regulatory efforts to strengthen 

incentives for EOR and other technologies focused on meeting the challenge of 

global warming while providing energy and enhancing our region's economic life. 

Response: EPA clarifies that the intent of the Class VI regulation is not to promote or encourage the use 

of GS, but, instead to ensure protection of USDWs where GS technologies are deployed. In addition, 

EPA clarifies that injection of CO2 for the purposes of enhanced oil and gas recovery will continue to be 

permitted under the Class II program, as long as any oil or gas production is occurring. The UIC GS 

requirements will apply to wells used for the purpose of long-term GS. 

Other EPA Comment Codes and Descriptions: 1420 1.2.1.1 Support the GS rulemaking 

Comment: Carbon capture technologies have been developed and there is reason to expect 

that CO2 can be successfully stored on a long-term basis in properly selected 

and managed geologic formations. Full commercialization will require additional 

economic incentives and early demonstration projects at large scale. In 

Commenter Name: Jeff Moseley Letter ID: 0155

Commenter Organization: Greater Houston Partnership (GHP) Comment ID: 21252

Commenter Name: Jeff Moseley Letter ID: 0155

Commenter Organization: Greater Houston Partnership (GHP) Comment ID: 21253

815
addition, it is important for business planning purposes that the Environmental 

Protection Agency (EPA) soon adopt reasonable rules governing CO2 storage in 

geologic formations. 

Response: EPA believes that the creation of a new injection well class (VI) under the existing UIC 

Program is necessary to enable the use of GS as a climate change mitigation technology in a manner that 

protects USDWs from endangerment. EPA agrees that the UIC Program, under the authority of the 

SDWA, provides a strong framework for regulating injection of CO2 for GS and adds that the GS 

regulation tailors the UIC requirements to address the unique issues associated with large-scale GS 

including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, 

the potential presence of impurities in captured CO2, and its mobility within subsurface geologic 

formations. 

Other EPA Comment Codes and Descriptions: 1420 1.2.1.1 Support the GS rulemaking 

Comment: The EPA is presently considering how CO2 sequestration should be regulated under 

the federal Underground Injection Control (UIC) program. The Partnership is 

pleased that this work is a priority for the agency. We encourage EPA to develop 

rules that: 

1. Assure that sites are properly selected managed and monitored in order to 

protect underground sources of drinking water (USDW), especially sole source 

aquifers. 

Response: EPA clarifies that the purpose of the GS rule is to protect USDWs from endangerment 

through permitting, siting, construction, operation, injection, and post-injection site care and site closure 

requirements that are tailored to address the unique nature of GS. 

EPA clarifies that SDWA, under section 1422(b)(3)(9)(A), requires that the regulations of the 

Administrator "permit or provide for varying geologic, hydrological, or historical conditions in different 

states and in different areas within a state." EPA has provided the Director discretion in applying the GS 

requirements, taking into account varying conditions, particularly with regard to the evaluation of site 

characteristics. 

For additional information on site characterization and testing and monitoring requirements, please also 

see the discussion of EPA’s Final Regulatory Approach in the preamble to the final GS rule. 

Comment: The development of GS is an important strategy within a portfolio of options for 

the Midwestern region to reduce greenhouse gas emissions. In 2007, we endorsed 

the Energy Security and Climate Stewardship Platform (Platform) that includes a 

broad range of measurable goals, policies and initiatives to transition the 

Midwest to a lower carbon energy economy. Priorities include the development of 

energy efficiency, bio-based products and transportation, renewable electricity 

and advanced coal with carbon capture and sequestration (CCS). 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy

Commenter Name: Jeff Moseley Letter ID: 0155

Commenter Organization: Greater Houston Partnership (GHP) Comment ID: 21254

Commenter Name: M. Michael Rounds Letter ID: 0159

Commenter Organization: Midwestern Governors Association (MGA) Comment ID: 22223

816
conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: The Midwestern region depends heavily on coal-fired generation and has 

significant coal and oil resources. These resources are also located in close 

proximity to formations that are likely suitable for geologic sequestration, 

specifically saline aquifers and depleted oil and gas fields. Thus, the Platform 

supports the development of a CO2 management infrastructure and demonstration 

and commercialization of large-scale geologic sequestration projects that take 

advantage of our region’s EOR potential. The Midwest has significant experience 

in both EOR and in the transport of CO2 through pipelines. These EOR projects 

would be part of a broader CO2 management strategy to capture CO2 from various 

sources and effectively leverage projects to build-out an infrastructure that 

could support long-term CO2 sequestration across the region. 

Response: EPA acknowledges the comment. EPA clarifies that injection of CO2 for the purposes of 

enhanced oil and gas recovery will continue to be permitted under the Class II program, as long as any 

oil or gas production is occurring. The UIC GS requirements will apply to wells used for the purpose of 

long-term GS. 

Please see the remainder of EPA’s responses to this comment for further details. For additional 

information on EPA’s final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: DTE Energy is a member of the Edison Electric Institute (EEI) and the Utility 

Solid Waste Activities Group (USWAG) and endorses the comments filed by each in 

this docket. The development of cost effective Carbon Capture and Sequestration 

(CCS) technology, in concert with regulations that allow flexible yet protective 

implementation are extremely important to our subsidiary -Detroit Edison, which 

has a fuel mix nearly 80% dependent on coal. Coal is domestically abundant and 

affordable. For those reasons, along with the need to comply with future 

regulations requiring the reduction of CO2 emissions, we would like to continue 

to utilize coal in our fuel mix in the future and see CCS as an important 

element to accomplish that goal. We applaud EPA’s effort and initiative to take 

the first critical steps to establishing a regulatory framework for geologic 

sequestration. We appreciate the opportunity to provide input into the 

regulatory development process and hope that EPA will consider our comments that 

we feel will impact our company and also the commercial deployment and public 

perception about carbon capture and storage. 

EEI and USWAG have done an excellent job of articulating the important general 

and specific technical comments which we anticipate EPA will seriously consider. 

DTE Energy submits the following high level overview and interpretation of the 

Commenter Name: M. Michael Rounds Letter ID: 0159

Commenter Organization: Midwestern Governors Association (MGA) Comment ID: 22224

Commenter Name: Skiles Boyd Letter ID: 0160

Commenter Organization: DTE Energy Comment ID: 21265

817
issues that we believe are of utmost importance to the rulemaking. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment, EEI’s comment, and USWAG’s comment for further details. For additional information on 

EPA’s final regulatory approach, please see the final rule and preamble as well as the rulemaking 

docket. 

Comment: The LEC's, along with our major members', participation in PCOR signals the 

importance of CCS technology and the need for the development of clear, flexible 

and appropriately tailored regulations that will facilitate the development of 

and spur investment in CCS technology. To achieve this goal several general 

principles should be considered by EPA as it refines the proposed regulations. 

Response: EPA recognizes the importance of providing clear, flexible, scalable, and appropriate 

regulations. EPA believes that the GS regulation will provide certainty to industry and the public by 

providing consistency in requirements across the U.S. and transparency about what requirements apply 

to owners or operators. EPA clarifies that the intent of the Class VI regulation is not to promote or 

encourage the use of GS, but, instead to ensure protection of USDWs where GS technologies are 

deployed. 

Please see the remainder of EPA’s responses to this comment for further details. For additional 

information on EPA’s final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: 3. APPA wants geologic sequestration of CO2 to work. Geologic Sequestration 

might enable the power utility sector to use coal at future and existing power 

plants while reducing CO2 emissions. However, the technology is not yet fully 

commercially demonstrated and suitable geology may not be available in all 

states. This caution does not discourage us from wanting it to work or for 

supporting additional demonstration projects at DOE/NETL and in the private 

sector. Geosequestration opportunities in oil and gas states are probably the 

most optimal location for early adopters of CCS technology(s). APPA encourages 

the use of oil and gas fields for injection of CO2 from power plants. 

Response: EPA clarifies that the intent of the Class VI regulation is not to promote or encourage the use 

of GS, but to ensure protection of USDWs where GS technologies are deployed. Please see the 

remainder of EPA’s responses to this comment for further details. For additional information on EPA’s 

final regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1610 1.3.1 Risks to USDWs 

Comment: Geologic sequestration into all geologic formations must be considered by 

electric utilities in their long-term plans for future fossil-fuel electricity

Commenter Name: Sandi Tabor Letter ID: 0162

Commenter Organization: Lignite Energy Council (LEC) Comment ID: 21293

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23375

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23382

818
generation while also weighing the need to protect public drinking water 

supplies. Protection of drinking water supplies, for some communities, may mean 

that inadequate surface water supplies may require that the city (or private 

utility) may require usage of groundwater in future years which may not appear 

to be "drinkable" under today’s presumed costs and technological (pump and treat 

or desalination) limitations. Our colleagues in the municipal drinking water 

operations remind us that Americans are currently drinking water which, in many 

locations, was undrinkable only 5-10 years ago. While most American cities in 

the east provide drinking water made up largely of surface water, more than 90% 

of all drinking water systems (private and public) use some amount of 

groundwater to make up for shortages. Acknowledging this does not mean that 

geosequestration should not be allowed. It simply requires common sense decision 

making at the local and regional level by power plants and the state directors 

as to the best placement of geosequestration plants or off-site injection 

formations. 

Response: The Agency acknowledges commenter concerns about water resources and future water 

resource availability. The primary goal of the UIC Program under the SDWA is to protect USDWs from 

endangerment in order to ensure a reliable supply of drinking water for the American public. The GS 

rule, as part of the UIC program regulations, continues the program’s mandate and mission of ensuring 

the protection of USDWs. EPA expects the tailored permitting, siting, construction, operation, 

monitoring, and post-injection site care requirements in the GS rule to prevent leakage from injection 

formations and protect USDWs. 

Other EPA Comment Codes and Descriptions: 1610 1.3.1 Risks to USDWs; 1800 1.4 Scientific 

Background/Informing the Proposal 

Comment: Our comments here should not deny the viability of CCS in some subsurface 

locations nor be read as APPA’s view that geologic sequestration works in all 

geologic locations or for all power plants. There is a great deal that we do not 

yet know about the wide variety of geologic formations to know that there are no 

risks to USDWs or that we could identify specifically what those risks might be. 

APPA hopes that on-going private and public research in the United States, 

Canada, Australia, and Europe will affirm that there are no risks to drinking 

water supplies or that the risks are so truly negligible that there is no reason 

to hesitate to use this technology. But we cannot presume that there are no 

risks simply based upon the commercial and technical success in CO2 recycling in 

Class II injection locations that are managed as production fields. It has been 

presumed that because the CO2 injections began in the Permian Basin of West 

Texas in the late 1970s that the CO2 from those tertiary recovery fields (for 

oil or gas) is actually still in the formation. In most cases the CO2 was 

recycled and used in different production operations. Even if the CO2 was 

injected 25-35 years ago, the CO2 may not still reside or remain in storage 

there. Because we have not seen large storage fields where the CO2 was stored 

for 10-30 years on a sustained basis, there is not as much known about the 

geologic formations, the adequacy of holding capacity and subsurface impacts as 

we would like to know. Also, in many cases, those oil or gas production fields 

are regulated differently than a newly established long-term GS formation would 

be regulated if it were owned/operated by a power company. 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23387

819
Response: EPA agrees with the commenter that the risks involved in GS projects are different than the 

risks associated with Class II activities. EPA believes that GS is sufficiently distinct from Class II ER 

operations to warrant the tailored requirements in the GS regulation. For example, the volume of CO2 

anticipated to be injected in Class VI wells is significantly greater than for Class II wells. Reservoir 

pressure conditions will be different, with Class VI injection operations involving large volumes of CO2 

and likely having higher pressures within their storage formations than Class II ER projects. Therefore, 

Class VI GS reservoir pressures will increase more in comparison to Class II ER during the injection 

phase of the GS project. 

EPA continues to research and collect data on CO2 storage and containment. EPA is tracking operations 

at the DOE GS pilot projects and will review data on all aspects of those operations, from well 

construction and injection to long-term plume fate and transport and monitoring of containment, as the 

data become available. In addition to the information cited in the preamble to the proposed rule, EPA 

published a Notice of Data Availability and Request for Comment on August 31, 2009 (74 FR 44802), 

in which the Agency described the results of research at three DOE partnership sites: the Escatawpa, 

Mississippi project; the Aneth Field project in Paradox Basin, Southeast Utah; and the Pump Canyon 

Site, New Mexico. Please also see the research described in the above response. 

As part of its adaptive rulemaking approach, the Agency plans, every six years, to collect and review 

data on GS projects to determine whether the appropriate amount and types of information and 

appropriate documentation are being collected, and to determine if modifications to the requirements are 

appropriate or necessary. 

Other EPA Comment Codes and Descriptions: 1540 1.2.3.2 Climate change legislation 

Comment: Some personnel at the U.S. EPA and members of Congress often assume falsely that 

CCS or GS is commercially deployable now in all states based upon the success in 

the half dozen or perhaps as many as a dozen oil/gas production states. The 

development of a national viable and workable CO2 capture and sequestration 

permitting program is one of the key prerequisites to the implementation of 

contemplated energy reform initiatives-ranging from state laws that force 

reductions in CO2 to pending new Federal legislation to require a national cap 

(on CO2 emissions.) APPA’s comments are offered here on the UIC permitting 

system are valid regardless to whatever "carbon signal" there might be to reduce 

CO2 from power plants. Even if there is no new national law setting a carbon 

emissions limit, intensity limit, carbon tax, or new generation requirement, 

states also have the ability to set state by state limits on 16 carbon dioxide 

emissions from power plants under separate state CO2 laws. APPA does not like 

patchwork quilt state by state regulatory approaches to reduce CO2 through 

different laws and regulations. It is entirely too soon to know what Congress 

might do. At this time, we have no clue what Congress might do in the future to 

constrain CO2 that would motivate any party to reduce CO2 from coal or natural 

gas plants. APPA’s comments are neutral as to the new legislative mechanism that 

would "constrain carbon". These technical, logistical, or cost issues are valid 

regardless of why utilities would want to inject CO2 under any carbon dioxide 

mitigation standard, reduction policy, or law. 

Response: EPA acknowledges that GS falls within the broader context of CCS and the need for 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23389

820
regulatory clarity to ensure that USDWs are protected from endangerment. In developing the final GS 

rule, the Office of Water coordinated with other Agency program offices and across federal agencies 

(e.g., with the Department of Energy; United States Geological Survey; Bureau of Ocean Energy 

Management, Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of 

Land Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

EPA is also aware that states are currently in various stages of developing statutory frameworks, 

regulations, technical guidance, and strategies for addressing CCS and GS. States can use multiple 

authorities beyond those afforded under the SDWA and UIC regulations, including laws and policies 

addressing surface access and land rights, unitization of fields, pore space ownership, mineral rights, 

worker safety and emergency preparedness, and maximization of state oil and gas resource exploitation. 

EPA plans to work closely with states and tribes as they develop Class VI primacy programs in this 

broader context. EPA adds that states may adopt more stringent standards for Class VI wells than the 

Federal requirements. 

In a separate rulemaking under authority of the Clean Air Act, EPA is amending the Greenhouse Gas 

(GHG) Reporting Program at 40 CFR Part 98 to add reporting requirements for facilities that conduct 

GS (subpart RR) and all other facilities that inject CO2 underground (subpart UU). For additional 

information, see the section of the final GS rule preamble entitled, "How Does Mandatory Reporting of 

Greenhouse Gases (GHGs) Relate to This Rulemaking?” and the GHG Reporting Program rulemaking 

and docket. 

Other EPA Comment Codes and Descriptions: 1420 1.2.1.1 Support the GS rulemaking; 2020 1.5.1 

Support Class VI designation 

Comment: Overall Comments 

ASDWA and its members appreciate EPA’s efforts to develop this rule under very 

limited time constraints and agree with EPA’s plan to create a new class of 

wells for carbon dioxide geologic sequestration sites. States believe that all 

appropriate steps need to be taken to ensure the effectiveness of Carbon Capture 

and Sequestration as a tool to mitigate greenhouse gas emissions, as well as 

avoid potential unintended consequences that could have a negative impact on 

Underground Sources of Drinking Water (USDW). Additional research and data are 

needed to ensure that this rule is fully protective of all potential drinking 

water sources. 

Response: EPA acknowledges the comment and agrees that tailored requirements for Class VI wells are 

necessary to address the unique nature of injecting large volumes of CO2 and to ensure that USDWs are 

protected from endangerment. The Class VI requirements are appropriate because of the unique nature 

and risks of CO2 injection for long-term storage (e.g., large injection volumes, long project duration, 

Commenter Name: James Taft Letter ID: 0172

Commenter Organization: Association of State Drinking Water Administrators 

(ASDWA)

Comment ID: 

23449

821
and reservoir pressure conditions). The GS rule contains tailored requirements for the permitting, 

geologic site characterization, AoR and corrective action, well construction, operation, mechanical 

integrity testing, monitoring, well plugging, post-injection site care, and site closure of GS wells that 

directly address issues unique to the nature of large-scale CO2 injection for GS. 

EPA agrees that continued research in all GS associated fields will be integral to development of GS 

technology. EPA is aware of research by other federal agencies, industry, international parties, and 

academia related to GS, including projects that address many of the topics suggested by commenters. 

EPA published a Notice of Data Availability (NODA) and Request for Comment on August 31, 2009 

(74 FR 44802), in which the Agency described the results of research at three DOE partnership sites (in 

Escatawpa, Mississippi; the Aneth Field in Paradox Basin, southeast Utah; and the Pump Canyon Site, 

New Mexico). In the NODA and Request for Comment, EPA also described two studies by the 

Lawrence Berkeley National Laboratory on the potential effects of CO2 injection on ground water and 

surrounding formations to determine the potential for impacts on USDWs and human health in the event 

that a GS project is not properly sited, operated, or managed. 

To protect USDWs from endangerment and meet the potentially fast pace of GS deployment, EPA is 

using an adaptive approach to regulating CO2 injection for GS. The Agency plans to, every six years, 

collect and review data on GS projects to determine whether the appropriate amount and types of 

information and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. An adaptive approach will allow regulatory development to 

proceed in time to meet the current and future demands for Class VI permits, while EPA continues to 

gather data from pilot projects and other research as it becomes available. 

Comment: Guiding Principals 

Addressing climate change will require a full portfolio of options for reducing 

greenhouse gas emissions. Dominion believes that carbon capture and storage 

(CCS) is an essential component of any future climate change mitigation policy 

and, accordingly, commends EPA for initiating the rulemaking process. 

Dominion supports the development of clear, flexible, scalable and appropriate 

regulations that will facilitate investment and development of CCS technology 

while assuring appropriate protections against adverse impacts to underground 

sources of drinking water (USDW). Dominion feels that the proposed regulations 

achieve these goals in many respects. 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. EPA recognizes the importance of providing clear, 

flexible, scalable, and appropriate regulations, and believes that the GS regulation will provide certainty 

to industry and the public by providing consistency in requirements across the U.S. and transparency 

about what requirements apply to owners or operators. 

Please see the remainder of EPA’s responses to this comment for further details. For additional 

information on EPA’s final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Commenter Name: Pamela Faggert Letter ID: 0175

Commenter Organization: Dominion Comment ID: 23513

822
Other EPA Comment Codes and Descriptions: 1420 1.2.1.1 Support the GS rulemaking 

Comment: Executive Summary 

Addressing climate change concerns requires a full commitment to development and 

commercial deployment of carbon capture and storage (CCS) technologies. EEI 

thus supports the development of clear, flexible and appropriately tailored 

regulatory regimes that will facilitate development of and investment in CCS 

technology and projects while protecting against potential environmental risks. 

We applaud the Agency for taking this crucial first step toward establishing 

such a regime for geological sequestration (GS). Recognizing the significance of 

EPA‘s initiative in proposing regulations for the injection and storage of 

carbon dioxide (CO2) under the Safe Drinking Water Act‘s (SDWA) Underground 

Injection Control (UIC) program, EEI appreciates the opportunity to provide 

input into the process and to share our suggestions for changes to the proposed 

rule. Incorporation of our comments into the final rule will serve to promote 

the dual goals of promoting the commercialization of CCS technology and 

preventing potentially undesirable impacts to drinking water resources. 

Response: EPA believes that the creation of a new injection well class (VI) under the existing UIC 

Program is necessary to enable the use of GS as a climate change mitigation technology in a manner that 

protects USDWs from endangerment. EPA agrees that the UIC Program, under the authority of the 

SDWA, provides a strong framework for regulating injection of CO2 for GS and adds that the GS 

regulation tailors the UIC requirements to address the unique issues associated with large-scale GS 

including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, 

the potential presence of impurities in captured CO2, and its mobility within subsurface geologic 

formations. 

Other EPA Comment Codes and Descriptions: 1420 1.2.1.1 Support the GS rulemaking 

Comment: I. General Principles Applicable To EPA's GS Regulatory Effort 

As we noted in our prior comments, addressing climate change concerns requires a 

full commitment to development and commercial deployment of carbon capture and 

storage (CCS) technologies. To put the need for this commitment in context, 

consider that electricity generation is responsible for 34 percent of greenhouse 

gas (GHG) emissions and 40 percent of CO2 in the U.S. The Energy Information 

Administration projects net electric demand will increase 30 percent by 2030, 

even after taking into account energy-efficiency improvements. New and 

replacement power plant capacity to meet this increased demand is projected to 

total 150,000 megaWatts. Coal is one of the primary sources of baseload 

generation in the U.S. and will continue to be an important fuel for generating 

electricity through 2030 because it is comparatively affordable and abundant in 

this country. Given this backdrop, the potential environmental benefits of CCS 

- in terms of reduced or avoided CO2 emissions - are substantial. Consequently, 

EEI and our members see CCS as a critical element in the full portfolio of 

options needed not only to reduce CO2 emissions, but also to ensure continued 

affordable and reliable electric service to customers throughout the nation. 

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23549

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23561

823
EEI thus supports the development of clear, flexible and appropriately tailored 

regulatory regimes that will facilitate development of and investment in CCS 

technology and projects while protecting against potential environmental risks. 

We applaud the Agency for taking this crucial first step toward establishing 

such a regime for GS. Recognizing the significance of EPA's initiative in 

proposing regulations for the injection and storage of CO2 under SDWA's UIC 

program, EEI appreciates the opportunity to provide input into the process and 

to share our suggestions for changes to the proposed rules. Incorporation of 

our comments into the final rules will serve to promote the dual goals of 

promoting the commercialization of CCS technology and preventing potentially 

undesirable impacts to drinking water resources. 

Response: EPA believes that the creation of a new injection well class (VI) under the existing UIC 

Program is necessary to enable the use of GS as a climate change mitigation technology in a manner that 

protects USDWs from endangerment. EPA agrees that the UIC Program, under the authority of the 

SDWA, provides a strong framework for regulating injection of CO2 for GS and adds that the GS 

regulation tailors the UIC requirements to address the unique issues associated with large-scale GS 

including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, 

the potential presence of impurities in captured CO2, and its mobility within subsurface geologic 

formations. 

EPA agrees that the implementation of the GS rule in a manner that ensures protection of USDWs from 

endangerment is important to establishing a foundation for further advances in the field of CO2 GS. 

EPA acknowledges the need for regulatory certainty: the final GS requirements provide a level of 

certainty by setting forth unique requirements for GS. These requirements include: the tailored AoR 

delineation process (per §146.84), the types of monitoring appropriate to GS projects (per §146.90), and 

the post-injection site care process (per §146.93). 

While EPA agrees with commenters that a stable, predictable, nationally consistent, and workable 

regulatory framework is important, EPA stresses that the focus of the GS rule is to ensure that, where 

GS is deployed, it is conducted in a manner that protects USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 1200 1.1 General comments about the rulemaking 

Comment: EEI's views are guided by several general principles applicable to any federal 

legislative or regulatory effort on CCS, which are described below and discussed 

more fully in the context of specific comments: 

1. Promotion of CCS. As EPA acknowledges in the preamble, CCS is a key climate 

change mitigation technology, and the proposed rules are intended to support its 

development.[FN2] Likewise, any EPA regulatory regime related to CCS developed 

under the authority of SDWA (or any other statute) should be designed to 

facilitate, and not unduly hinder, the successful commercial-scale deployment of 

CCS. The potential environmental benefits of such deployment in terms of 

reduced or avoided GHG emissions should be weighed against potential 

requirements that might delay or compromise the ability to achieve commercialscale CCS. Issues the Agency should consider in connection with this principle 

include: 

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23562

824
[FN2] 73 Fed. Reg. 43495, col.1. 

Response: EPA clarifies that the intent of the GS rule is not to promote or encourage the use of GS; 

rather, its purpose is to ensure consistency in permitting underground injection of CO2 at GS operations 

across the United States and provide requirements to prevent endangerment of USDWs in anticipation of

the eventual use of GS to reduce CO2 emissions. Please see the remainder of EPA's responses to this 

comment for further details. For additional information on EPA's final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1400 1.2 Comments on EPA's Authority to Regulate 

Injection of CO2 

Comment: If atmospheric emissions of CO2 are to be controlled, CCS is the only tool now 

on the horizon that may be capable of addressing in a major way and within a 

mid-term timeframe, the very large quantities of CO2 emissions from fossil-fuel 

using facilities in the United States. However, CCS still requires the 

definition of a stable and rational legal and regulatory regime before it can be 

widely deployed. EPA has clear regulatory authority over the injection of wastes 

and other substances into below-surface wells through the UIC program. The UIC 

program was created by Congress under the Safe Drinking Water Act ("SDWA") over 

30 years ago, without consideration of potential interaction with policies to 

address climate change, for the protection of underground sources of drinking 

water ("USDW). The Agency now proposes to use this framework to regulate belowground CO2 injection activities, an application not contemplated at the time 

SDWA was drafted. Rules for geologic sequestration ("GS") of CO2 are timely and 

would be needed even if CCS is not deployed as quickly as many predict. While 

many projects are under development, many observers are operating under the 

assumption that it will be a decade or more before there can be wide deployment 

of CCS.[FN3] The future of CCS is and will be at a critical juncture for some years. 

The CCS Alliance seeks, through its comments, to help ensure that these 

regulatory activities promote well designed and implemented CCS projects with 

sound risk management practices, and do not preclude the responsible, cost 

effective commercial-scale sequestration of CO2. 

[FN3] See, e.g., "EPRI Summer Seminar and Energy Technology Assessment Center 

(ETAC) Studies," presentation of Hank Courtright, Senior Vice President, 

Electric Power Research Institute. October 22. 2008. 

Response: EPA believes that the creation of a new injection well class (VI) under the existing UIC 

Program is necessary to enable the use of GS as a climate change mitigation technology in a manner that 

protects USDWs from endangerment. EPA believes that the UIC Program, under the authority of the 

SDWA, provides a strong framework for regulating injection of CO2 for GS and adds that the GS 

regulation tailors the UIC requirements to address the unique issues associated with large-scale GS 

including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, 

the potential presence of impurities in captured CO2, and its mobility within subsurface geologic 

formations. 

EPA agrees that the implementation of the GS rule in a manner that ensures protection of USDWs from 

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23796

825
endangerment is important to establishing a foundation for further advances in the field of CO2 GS. 

EPA acknowledges the need for regulatory certainty: the final GS requirements provide a level of 

certainty by setting forth unique requirements for GS. These requirements include: the tailored AoR 

delineation process at §146.84, the types of monitoring appropriate to GS projects §146.90, and the postinjection site care process §146.93. 

Comment: Geologic sequestration holds promise as a key component in the promotion of 

cleaner coal technologies. As a coal producing state, we are especially interested 

in technologies that will secure the industry’s future in the face of the challenges 

associated with reducing greenhouse gas emissions, thereby mitigating the 

impacts from global warming. 

Our commitment to greenhouse gas reductions is reflected in Colorado’s Climate 

Action Plan which calls for reducing greenhouse gas emissions by 20% from 2005 

levels by 2020. We cannot fully realize this goal without cleaner coal 

technologies. But emerging solutions, such as geologic sequestration, must be 

technologically and environmentally sound and supported by a viable and efficient 

regulatory framework. 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. 

Please see the remainder of EPA’s responses to this comment for further details. For additional 

information on EPA’s final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: As EPA has correctly recognized, it is critical that any UIC program regulation 

addressing GS be designed to achieve two goals. First - obviously - such a rule 

should ensure that CO2 injection is conducted in a manner that is protective of 

human health and the environment. Second, such a rule should effectively 

facilitate the development of GS as a means for greenhouse gas (GHG) mitigation. 

EPA’s rulemaking effort will prove successful only to the extent that both of 

these goals are achieved. 

Fortunately, there is abundant evidence that CO2 injection can be accomplished 

in a manner that is protective of human health and the environment. Indeed there 

has been a long history of successful injection well operation in the United 

States, and multiple studies have confirmed that the UIC program has been 

remarkably effective in ensuring protection of human health and the environment. 

While GS projects are likely to be large in scale, it is important to recognize 

that the injection of CO2 is nothing new. To the contrary, CO2 has been injected 

for purposes of enhanced oil and gas recovery (EOR/EGR) for more than thirtyfive years, and the UIC program already regulates more than thirteen thousand 

Commenter Name: Ginny Brannon Letter ID: 0182

Commenter Organization: Colorado Department of Public Health and 

Environment

Comment ID: 

23752

Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24316

826
CO2 injection wells that have successfully injected more than 600 million tons 

of CO2. Accordingly, there is a vast body of experience demonstrating that CO2 

injection can be conducted without adverse impacts on human health and the 

environment. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this letter 

for further details. For additional information on EPA’s final regulatory approach, please see the final 

rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1420 1.2.1.1 Support the GS rulemaking 

Comment: of energy sources including renewable energy. Southern Company has already begun 

a CO2 injection project at a deep saline-filled geologic formation in 

Mississippi as part of the Southeast Carbon Sequestration Regional Partnership. 

We believe that carbon capture and storage ("CCS") is critical to the likely 

federal goal of reducing greenhouse gas emissions and to the implementation of a 

number of federal and state energy reform initiatives; we are proud of our 

efforts to help bring this important technology towards commercial viability and 

generally support EPA's efforts in this rulemaking. 

Carbon capture and storage has the potential to lead to substantial 

environmental benefits in terms of avoided CO2 emissions. Therefore, a workable 

CCS program, including a regulatory framework for long-term carbon dioxide 

sequestration as anticipated by this rulemaking, is an essential element in the 

full portfolio of options needed to ensure continued affordable and reliable 

electric service to customers throughout the United States while reducing CO2 

Response: EPA believes that the creation of a new injection well class (VI) under the existing UIC 

Program is necessary to enable the use of GS as a climate change mitigation technology in a manner that 

protects USDWs from endangerment. EPA agrees that the UIC Program, under the authority of the 

SDWA, provides a strong framework for regulating injection of CO2 for GS and adds that the GS 

regulation tailors the UIC requirements to address the unique issues associated with large-scale GS 

including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, 

the potential presence of impurities in captured CO2, and its mobility within subsurface geologic 

formations. 

Comment: warming. With Eastman’s long-term commitment to gasification technology the 

company has a vested interest in the geologic storage of CO2 that is important 

for the continued viability of gasification facilities. Eastman Chemical Company 

supports the following comments on the proposed rule generated by the 

Gasification Technologies Council. 

Gasfication is an important technology for the conversion of coal, biomass, 

petroleum coke, municipal solid waste (MSW) and other carbonaceous feedstocks to 

power, chemicals, fertilizers and cleaner fuels. With gasification, CO2 can be 

captured using commercially available technologies. Due to its inherent carbon 

Commenter Name: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22153

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22690

827
capture capability, gasification can serve a major role in Carbon Capture and 

Storage (CCS) projects. GTC’s interest in EPA’s proposed regulation derives from 

the importance of CCS to achieving future goals of CO2 emissions reduction while 

using secure and indigenous resources to meet our growing national need for 

chemicals, fertilizers, liquid fuels, hydrogen, and electricity. 

Response: EPA clarifies that GHG emissions reductions and the use of integrated gasification combined 

cycle technologies are outside the scope of the UIC GS rulemaking. The purpose of the GS rule is to 

ensure that, where GS is deployed, the projects are permitted sited, constructed, operated, and closed in 

a manner that protects USDWs from endangerment. The requirements apply to owners or operators of 

injection wells used to inject CO2 for long-term storage. 

Please see the remainder of EPA’s responses to this comment for further details. For additional 

information on EPA’s final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: As we studied the feasibility of developing an IGCC project with CCS, we learned 

a great deal about geologic storage of CO2. We learned that geologic storage is 

currently one of the most important means by which power companies can reduce 

CO2 emissions while still producing reliable and affordable energy from coal. 

International studies as well as studies here in this country attest to the 

importance of geologic storage of CO2 in any strategy to reduce increasing 

carbon concentrations in the atmosphere. The development of a rational 

regulatory framework to address geologic storage of CO2 is essential in order to 

balance the nation's need for energy security, through increased use of domestic 

energy resources, with concerns over global climate change. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1410 1.2.1 Comments in support of EPA/rulemaking 

Comment: As an initial matter, we applaud EPA’s significant efforts to include and 

encourage broad stakeholder participation both before and after publication of 

the Proposed Rule. Furthermore, it is evident from the Proposed Rule that EPA 

considered and incorporated many of the stakeholders’ comments from the public 

workshops. Accordingly, EPA adopted a framework that is intended to encourage 

the deployment of carbon capture and sequestration or storage ("CCS") in a 

manner that is protective of underground sources of drinking water ("USDWs"). 

There is growing consensus among scientists, environmental groups and members of 

government that CCS will play a critical role in addressing greenhouse gas 

emissions. 

Response: EPA agrees that input of and participation by a wide spectrum of stakeholders is a vital 

component of successful rulemaking. The Agency appreciates the degree of cooperation, participation, 

Commenter Name: Olon Plunk Letter ID: 0217

Commenter Organization: Xcel Energy, Inc. Comment ID: 21549

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21646

828
and active dialogue between the EPA and stakeholders and will continue to work with stakeholders and 

experts as it implements the GS rule. 

Comment: The comments herein are founded on knowledge and experience gained through 

decades of industry operations, and are intended to provide constructive input 

on the Proposed Rule. HEI’s comments are based upon two important and mutuallyachievable goals: (1) protecting USDWs; and (2) adopting regulations that are 

reasonable, cost-effective and facilitate geologic sequestration of CO2. HEI 

concurs with EPA’s conclusion that CCS presents a "key climate change mitigation 

technology." (73 Fed. Reg. at 43495.) 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: workshops. Accordingly, EPA adopted a framework that is intended to encourage 

the deployment of carbon capture and sequestration or storage ("CCS") in a 

manner that is protective of underground sources of drinking water ("USDWs"). 

There is growing consensus among scientists, environmental groups and members of 

government that CCS will play a critical role in addressing greenhouse gas 

emissions. 

The comments herein are founded on knowledge and experience gained through 

decades of industry operations, and are intended to provide constructive input 

on the Proposed Rule. BP’s comments are based upon two important and mutuallyachievable goals: (1) protecting USDWs; and (2) adopting regulations that are 

reasonable, cost-effective and facilitate geologic sequestration of CO2. BP 

concurs with EPA’s conclusion that CCS presents a "key climate change mitigation 

technology." (73 Fed. Reg. at 43495.) 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: capacity--enough to power nearly 20 million homes. NRG believes that emissions 

of GHGs from power generation and other sectors must be reduced, both 

domestically and internationally, to successfully address climate change, and 

that commercially attractive, safe and environmentally secure carbon capture and 

sequestration will be critical for that success. Headquartered in Princeton, NJ, 

NRG is a member of the U.S. Climate Action Partnership (USCAP), a group of 

business and environmental organizations calling for mandatory legislation to 

reduce greenhouse gas emissions. 

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21647

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21712

Commenter Name: Steven B. Corneli Letter ID: 0234

Commenter Organization: NRG Energy, Inc. Comment ID: 23158

829
Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: electricity generation facilities. Currently, Montana-Dakota generates a 

majority of its electricity through fossil-fired power plants. Therefore, the 

proposed rule, in providing additional certainty in capturing and sequestering 

CO2, is expected to support Montana-Dakota's continued utilization of the 

region's abundant fossil fuel resources in order to continue generating 

affordable electricity for its customers. Montana-Dakota believes it is 

important to proceed with development of CO2 GS projects while preventing 

potentially undesirable impacts to drinking water resources. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this letter 

for further details. For additional information on EPA’s final regulatory approach, please see the final 

rule and preamble as well as the rulemaking docket. 

Comment: Among WEST Associates' membership, coal-fired generation constitutes a 

significant proportion of electrical generation resources for the western 

states, and the nation as a whole relies on more than 50% of its generation from 

coal-fired power plants. Demographic growth in the western states has been, and 

likely will continue to be, greater than the rest of the U.S.; as a result, coal 

generation and the potential need to abate it’s growing CO2 emissions will 

require effective options such as GS. Clearly, as the nation embarks on programs 

to reduce greenhouse gas (GHG) emissions to achieve it's climate change goals, 

the option of carbon sequestration through under-ground injection wells must be 

a significant part of the CO2 emissions abatement program for fossil fuel 

generation. In its preamble to this rulemaking, EPA notes that the UIC Program 

and GS are "one of a portfolio of options" for successful abatement of CO2 

emissions to the atmosphere. 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: WEST generally supports a well-designed and cost-effective national program for 

CO2 abatement, and believes that some of the features of the Lieberman-Warner 

Bill (S.2191) present a fair start for negotiating a workable program in 

Congress. Indeed, EPA estimated in its review of S.2191 that Carbon Capture and 

Commenter Name: Abbie Krebsbach Letter ID: 0235

Commenter Organization: Montana-Dakota Utilities Co. Comment ID: 23176

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission Associates Comment ID: 22238

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission Associates Comment ID: 22239

830
Sequestration (CCS) technology could account for about 30% of CO2 emissions 

reductions sought by year 2050 under that bill. Notably, the 11 western states 

where WEST members reside and produce electricity, the regional geology, 

geography and its demographics in the vast spaces of the West may provide unique 

sequestration opportunities in general proximity to abundant coal supplies and 

coal powered generating plants. National legislation and regulatory 

developments such as this one on UIC of CO2 for GS, should remove legal and 

institutional barriers that prevent the development and use of carbon capture 

and storage/sequestration technologies. That is, the design of a UIC/GS 

regulatory program should promote efficient and simple regulation without 

redundancies with other regulations, yet maximize protection of underground 

sources of drinking water ("USDW"), and the public health and safety above 

ground. 

Response: EPA acknowledges that the issue of GS falls within the broader context of CCS and 

acknowledges that regulatory clarity is essential for enabling GS to move forward in a manner that 

protects human health and the environment. The Agency is working to identify areas related to GS that 

could be addressed under other statutes to ensure that GS is conducted in a manner that is protective of 

human health and the environment. Additionally, the Agency is and will continue to coordinate 

internally and with other Federal agencies involved in GS and CCS, including the Bureau of Ocean 

Energy Management, Regulation and Enforcement, Bureau of Land Management, and the United States 

Geological Survey, to promote consistency in existing and future GS initiatives. 

Please see the remainder of EPA’s responses to this comment for further details. For additional 

information on EPA’s final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: The Roundtable strongly supports the aggressive research and development efforts 

underway to facilitate commercial-scale CO2 capture and sequestration ("CCS") 

projects. We also believe that expansion of enhanced oil recovery ("EOR") 

present a meaningful opportunity to utilize CO2 in a way that is beneficial to 

the global environment and both our nation’s economy and its energy security. 

Response: EPA clarifies that injection of CO2 for the purposes of enhanced oil and gas recovery will 

continue to be permitted under the Class II program, as long as any oil or gas production is occurring. 

The UIC GS requirements will apply to wells used for the purpose of long-term GS. The intent of the 

Class VI regulations is not to promote or encourage the use of GS, but, instead to ensure protection of 

USDWs where GS technologies are deployed. 

For additional information on EPA’s approach to wells that are transitioning from ER to GS, see the 

discussion of Class II wells under “How Does This Rule Affect Existing Injection Wells Under the UIC 

Program?” in the preamble to the final GS rule. 

Other EPA Comment Codes and Descriptions: 1350 1.1.3.3 Comments on the need for GS 

technology 

Commenter Name: James T. Sims Letter ID: 0249

Commenter Organization: Western Business Roundtable Comment ID: 22254

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22270

831
Comment: While it is not a "silver bullet", one important tool is the geologic 

sequestration (GS) of CO2 at properly selected and properly regulated sites. Our 

Environmental NGO Group does not necessarily have a common view concerning the 

magnitude of the long-term role of GS in combating climate change, but we are 

united in recognizing that a transition away from fossil fuels will take time 

and that GS is likely to be an important part of the near- to medium-term 

solution. Fortunately, capturing CO2 and permanently sequestering it in certain 

types of well-selected and well-managed geologic formations is a technology that 

is ready to begin deployment today. While GS projects can be permitted today 

under the Safe Drinking Water Act’s (SDWA) UIC program (in fact a number of 

projects have already been permitted under existing well classes), the rules 

that currently apply to such projects were not designed with geologic 

sequestration in mind. Thus, the importance of this rulemaking is not that it is 

needed in order for GS projects to receive permits; rather, the rulemaking is 

important because it can assure that GS projects are regulated under rules that 

are specifically designed to require GS projects to be done safely and 

effectively without endangering underground sources of drinking water (USDWs) 

or, as discussed below, resulting in a risk of release to the atmosphere. For 

that reason, it is essential that EPA promulgate final rules for GS in a timely 

manner that are sufficient to protect USDWs. 

Response: EPA agrees that GS is one technology in a portfolio of options, including solar, wind, 

biomass, and geothermal, that could be deployed to reduce CO2 emissions; however these technologies 

are outside the scope of the UIC GS rulemaking. The Class VI GS requirements are designed to ensure 

that, where GS is deployed to address climate change, projects are permitted sited, constructed, 

operated, and closed in a manner that avoids releases of CO2 into USDWs. 

Please see the remainder of EPA’s responses to this comment for further details. For additional 

information on EPA’s final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: The NAM supports development and deployment of advanced, energy efficient and 

zero-and-low-Greenhouse Gas (GHG) emission and sequestration technology as part 

of a long-term strategy to reduce GHG emissions in the U.S. economy. Many 

members of the NAM have a direct interest in removing impediments to the 

development of CCS technology in order to increase its commercial viability. 

Pursuant to issues raised specifically by the proposal, the NAM believes that 

CCS can be developed in a manner that does not undermine the safety of 

underground sources of drinking water. 

Response: EPA agrees that large-scale GS can be done safely. The GS regulation builds upon the longstanding protective framework of the UIC program, which has been regulating the injection of billions 

of gallons of liquids for decades. The GS regulation enhances this existing framework with requirements 

for GS wells that are tailored to the unique nature of large-scale GS of CO2. These additional protective 

requirements include more extensive geologic testing, detailed computational modeling of the AoR and 

periodic re-evaluations, detailed requirements for monitoring and tracking the CO2 plume and pressure 

front, and extended post-injection monitoring and site care. 

Commenter Name: Keith McCoy Letter ID: 0258

Commenter Organization: National Association of Manufacturers Comment ID: 22373

832
For additional information on EPA’s final regulatory approach, please see the final rule and preamble as 

well as the rulemaking docket. 

Comment: Geological sequestration of CO2 is, in sum, one of the important tools available 

for stabilizing CO2 levels in the atmosphere, and Basin Electric/DGC's Weyburn 

project is currently the largest carbon sequestration project in the world 

demonstrating the feasibility of such capture and storage. Whatever steps are 

taken either legislatively or through rulemaking to regulate CO2 and other 

greenhouse gases (GHGs) must allow CCS technology and other carbon and GHG 

control technologies to be developed, and must allow a reasonable time frame to 

do so. 

II. Importance of Developing Reasonable Regulations 

The energy needs of the United States are dependent upon carbon producing fuels. 

The development of reasonable regulations, including reasonable regulations for 

carbon dioxide capture and sequestration (CCS), thus is crucial for CCS is to 

fulfill its potential as one of the important ways to mitigate greenhouse gas 

impacts. "While other climate mitigation options exist-such as energy efficiency 

improvements, a switch to less carbon-intensive fuels, nuclear power, and 

renewable energy sources-CCS is considered by many to be a crucial component of 

any U.S. approach or strategy for addressing the climate change problem, 

particularly given the United States' current reliance on coal for almost half 

of its electricity production." [FN8] 

The use of carbon dioxide for enhanced oil recovery (EOR) is also generally 

recognized as an important intermediate step in developing EOR, because the 

knowledge and technology is already there to begin to use it. "The injection of 

CO2 in deep geological formations involves many of the same technologies that 

have been developed in the oil and gas exploration and production industry. 

Well-drilling technology, injection technology, computer simulation of storage 

reservoir dynamics and monitoring methods from existing applications are being 

developed further for design and operation of geological storage." [FN9] 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. However, the use of and investment in these 

technologies is outside the scope of the UIC GS rulemaking. 

EPA clarifies that the intent of the Class VI regulation is not to promote or encourage the use of GS, but, 

instead to ensure protection of USDWs where GS technologies are deployed. Please see the remainder 

of EPA’s responses to this comment for further details. For additional information on EPA’s final 

regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Commenter Name: Claire Olson Letter ID: 0260

Commenter Organization: Basin Electric Power Cooperative Comment ID: 22385

Commenter Name: Michael Moore Letter ID: 0265

Commenter Organization: North American Carbon Capture & Storage 

Association (NACCSA)

Comment ID: 

22850

833
Comment: II. General Principles Applicable To EPA's GS Regulatory Effort 

As legislative and regulatory efforts to address climate change accelerate, it is 

critically important that policymakers follow EPA's lead by continuing to 

recognize the central role that CCS can play as a mitigation tool. As noted in the 

Preamble to EPA's proposed rule, CCS holds the promise of storing large volumes of 

carbon dioxide in geologic formations such as deep saline formations, depleting 

and depleted oil & natural gas reservoirs, unmineable coal seams and similar 

geologic structures. Because CCS has the potential to be applied in a wide range of 

fossil fuel production processes, NACCSA believes that CCS should be recognized 

as an emissions mitigation measure under any climate regime. Additionally, NACCSA 

members view carbon dioxide as a central component in the enhanced recovery of oil 

and natural gas and recognize that it is capable of being responsibly stored as 

part of this process. 

Recognizing the significance of the initiative displayed by EPA in proposing 

regulations for injection and storage of CO2 carbon dioxide under the Safe 

Drinking Water Act's UIC program, NACCSA appreciates the opportunity to provide 

input on which aspects of the proposed rules are favorable, and for which aspects 

of the proposed rules EPA should consider possible changes, in light of the 

rulemaking's dual goals of improving the chances of achieving commercial 

viability for CCS while also preventing potentially undesirable impacts to 

drinking water resources. NACCSA's general areas of focus in this discussion 

include siting and secondary containment; monitoring/use of tracers; closure 

and post-injection site care; financial assurance; grandfathering; state primacy; 

and potential issues arising under other environmental laws. Comments on specific 

aspects of the Agency's proposed rules within these general focus areas are set 

forth below. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach (including 

information on siting and containment, monitoring and use of tracers, site closure and post-injection site 

care, financial assurance, primacy, transitioning existing wells into Class VI wells, and potential issues 

arising under other environmental laws), please see the final rule and preamble as well as the rulemaking 

docket. 

Comment: First, I'd like to provide some context for our comments. Oil and natural gas 

and coal provide approximately 85 percent of the world's energy. The power 

plants, vehicles, homes, businesses and factories that use these fuels produce 

more than 25 billion tons of carbon dioxide emissions annually. While no single 

technology is sufficient to mitigate these emissions, capturing CO2 and storing 

it deep underground in formations could play an important role. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Commenter Name: Michele Schoepper Letter ID: 0503

Commenter Organization: American Petroleum Institute Comment ID: 21170

834
Comment: CCS is one of the essential technologies that could help to ensure that we can 

continue to produce the clean energy society demands. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: My perspective is this, I believe geologic sequestration is essential and 

urgently needed, especially because coal is a major contributor to global 

climate change both in the United States and all around the world. And if coal 

is to be used it must be used on the basis of sequestration of 100 percent of 

the CO2. 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. However, the use of and investment in these 

technologies is outside the scope of the UIC GS rulemaking. The Class VI GS requirements are 

designed to ensure that, where GS is deployed, projects are permitted, sited, constructed, operated, and 

closed in a manner that protects USDWs from endangerment. For additional information on EPA’s final 

regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: I'd like to start out by agreeing with a couple of comments made previously. 

First, agree with the Sierra Club, that CCS is not a silver bullet, we believe 

it's a critical technology in the fight against climate change, but it's not a 

silver bullet by any means. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: Geologic sequestration holds promise as a key component in the promotion of 

premier coal technologies. As a coal producing state in Colorado, we are 

especially interested in technologies that will secure the industry's future in 

the face of the challenges associated with reducing greenhouse gas emissions and 

thereby mitigating the impacts from global warming. 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. However, the use of and investment in these 

Commenter Name: Michele Schoepper Letter ID: 0503

Commenter Organization: American Petroleum Institute Comment ID: 21180

Commenter Name: Mark Singer Letter ID: 0504

Commenter Organization: Green America Project, LLC Comment ID: 21241

Commenter Name: Scott Anderson Letter ID: 0510

Commenter Organization: Environmental Defense Fund Comment ID: 21215

Commenter Name: Ginny Brannon Letter ID: 0521

Commenter Organization: Colorado Department of Public Health and 

Environments

Comment ID: 

21445

835
technologies is outside the scope of the UIC GS rulemaking. The Class VI GS requirements are 

designed to ensure that, where GS is deployed, projects are permitted, sited, constructed, operated, and 

closed in a manner that protects USDWs from endangerment. For additional information on EPA’s final 

regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: First I would like to provide some context for our comments. Oil, natural gas 

and coal provide approximately 85% of the world's energy. The power plants, 

vehicles, homes, businesses and factories that use these fuels produce more than 

twenty five billion tons of CO2 emissions annually. While no single technology 

is sufficient to mitigate human CO2 emissions, capturing CO2 and storing it in 

deep underground formations could play an important role. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: the innovations that could improve both well security and performance. CCS is 

one of the essential technologies that could help to ensure that we can continue 

to produce clean energy society demands. 

Response: EPA acknowledges the comment. Please see the remainder of EPA’s responses to this 

comment for further details. For additional information on EPA’s final regulatory approach, please see 

the final rule and preamble as well as the rulemaking docket. 

Comment: I applaud the EPA for proposing these regulations. CCS holds significant promise 

to manage carbon emissions and should be part of any climate change regime. CCS 

is also essential to enhanced oil and gas recovery which we believe can be 

combined with permanent storage. 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. However, the use of and investment in these 

technologies is outside the scope of the UIC GS rulemaking. The Class VI GS requirements are 

designed to ensure that, where GS is deployed, projects are permitted, sited, constructed, operated, and 

closed in a manner that protects USDWs from endangerment. 

EPA clarifies that injection of CO2 for the purposes of enhanced oil and gas recovery will continue to be 

permitted under the Class II program, as long as any oil or gas production is occurring. The UIC GS 

requirements will apply to wells used for the purpose of long-term GS. For additional information on 

EPA’s approach to wells that are transitioning from ER to GS, see the discussion of Class II wells under 

“How Does This Rule Affect Existing Injection Wells Under the UIC Program?” in the preamble to the 

Commenter Name: Steve Crookshank Letter ID: 0523

Commenter Organization: American Petroleum Institute (API) Comment ID: 21353

Commenter Name: Steve Crookshank Letter ID: 0523

Commenter Organization: American Petroleum Institute (API) Comment ID: 21363

Commenter Name: Mike Moore Letter ID: 0532

Commenter Organization: North American Carbon Capture and Storage 

Association (NACCSA)

Comment ID: 

21365

836
final GS rule. 

Comment: We believe that the problem of economics and problem with policy can put CCS in 

context and give it the role that it needs. Nonetheless, we do not believe that 

we can do away with this if we are going to meet emission reduction targets in 

time, so this is what we think is an absolutely necessary part of the mitigation 

portfolio. We would like to see things happen otherwise; I think technically it 

is feasible. The way that some of the developing economies are growing these 

days and the way the political situation in the U.S. is heading, means that we 

wanted to use CCS as well. 

Having spent a good few years studying this and we took great care in being 

diligent, as an environmental group the idea of injecting large volumes of CO2 

underground that is not the most appealing at first. Nonetheless, the more we 

studied this, the more convinced we become that if regulated and performed well, 

it can be very safe and effective. And I stress the words, can be. 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. EPA clarifies that the purpose of the UIC GS 

regulation is to ensure that GS is conducted in a manner that protects USDWs from endangerment. 

EPA believes that large scale GS can be done safely. The GS regulation builds upon the long-standing 

protective framework of the UIC program, which has been regulating the injection of billions of gallons 

of liquids for decades. The GS regulation enhances this existing framework with requirements for GS 

wells that are tailored to the unique nature of large scale GS of CO2. These additional protective 

requirements include more extensive geologic testing, detailed computational modeling of the AoR and 

periodic re-evaluations, detailed requirements for monitoring and tracking the CO2 plume and pressure 

front, and extended post-injection monitoring and site care. 

Comment: I do not agree with the assertion that CCS is unproven, untried or untested. I 

think there was a good body of experience in related context that gives us 

reason to believe that CCS is safe and effective. EOR as one of those examples, 

I do not claim that EOR is tantamount to CCS. There are key differences. 

Nonetheless, there are fields that inject very large volumes of CO2 annually and 

in the U.S. and elsewhere. Some of these injections are well above the amount of 

CO2 that would be injected annually by a large qualified power plant. 

We do not have the monitoring provisions in place that we would have with a 

standard sequestration project. Nonetheless, there are studies that are almost 

completed that show, and these are going to be published I think within the next 

few weeks or few months by the University of Texas, that show that there is 

indeed no real contamination issue at some of the major UI projects and fields. 

Even though the objective is not to keep the CO2 down for hundreds of millions 

of years or thousands of years, nonetheless we have injected very large volumes 

Commenter Name: George Peridas Letter ID: 0534

Commenter Organization: Natural Resources Defense Council (NRDC) Comment ID: 21451

Commenter Name: George Peridas Letter ID: 0534

Commenter Organization: Natural Resources Defense Council (NRDC) Comment ID: 21452

837
of CO2 and the regulatory experience in Class II has shown that we have not come 

across any major contamination issues. 

The other I think major and striking example of CCS which is often overlooked is 

nature itself. CO2, methane and even H2S, hydrogen sulfide are occurring 

naturally in the subsurface. The fields that the industry has actually mined 

contained fairly pure CO2. These large volume fields, they have been there and 

they are testament that CO2 can be stored by nature in the subsurface for a 

very, very long time and very effectively. 

Oil fields and gas fields and also the deep saline formations also show nature's 

ability to retain those fluids, so I would urge a close study and consideration 

of what nature has done already. Just putting a label on a new technique and 

calling it sequestration does not necessarily mean that it has not been done 

before. 

Response: EPA clarifies that the purpose of the UIC GS regulation is to ensure that GS is conducted in 

a manner that protects USDWs from endangerment. EPA agrees that large scale GS can be done safely. 

The GS regulation builds upon the long-standing protective framework of the UIC program, which has 

been regulating the injection of billions of gallons of liquids for decades. The GS regulation enhances 

this existing framework with requirements for GS wells that are tailored to the unique nature of large 

scale GS of CO2. These additional protective requirements include more extensive geologic testing, 

detailed computational modeling of the AoR and periodic re-evaluations, detailed requirements for 

monitoring and tracking the CO2 plume and pressure front, and extended post-injection monitoring and 

site care. 

Please see the remainder of EPA’s responses to this comment for further details. For additional 

information on EPA’s final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: First we have learned that carbon sequestration is currently one of the most 

important means by which power companies can reduce carbon dioxide emissions 

while still producing reliable and affordable energy from coal. 

International studies as well as studies here in this country attest to the 

importance of geologic sequestration of carbon dioxide in any strategy to 

reducing increasing carbon concentrations in the atmosphere. 

Second, working with respected geo-technical and reservoir consultants to DOE 

sequestration partnerships and a world renowned national lab, we learned that 

geologic storage of CO2 is not only feasible, but actually happening 

successfully in a number of places around the world. We also discovered there 

are viable and even favorable sites to sequester large quantities of CO2 right 

here in Colorado. 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. However, the use of and investment in these 

Commenter Name: Olon Plunk Letter ID: 0536

Commenter Organization: Xcel Energy Comment ID: 21375

838
technologies is outside the scope of the UIC GS rulemaking. 

EPA agrees that large scale GS can be done safely. The GS regulation builds upon the long-standing 

protective framework of the UIC program, which has been regulating the injection of billions of gallons 

of liquids for decades. The GS regulation enhances this existing framework with requirements for GS 

wells that are tailored to the unique nature of large scale GS of CO2. These additional protective 

requirements include more extensive geologic testing, detailed computational modeling of the AoR and 

periodic re-evaluations, detailed requirements for monitoring and tracking the CO2 plume and pressure 

front, and extended post-injection monitoring and site care. For additional information on EPA’s final 

regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment Code: 1340 1.1.3.2 Oppose use of GS in general 

Individual Comments 

Other EPA Comment Codes and Descriptions: 1600 1.3 Risk Associated with CO2 GS 

Comment: i elieve these wells are extremely dangerous. it would be far better to 

see that less carbon dioxide is formed. i see little to no effort in that regard 

and ask for more effort on that. these wells are an accident waiting to happen. 

look at how the army orps of engineers built the leveees in new orleans - that 

is an indication of the quality of construction that can happen in the usa. 

Response: EPA recognizes that injecting large volumes of CO2 for GS poses unique challenges that, if 

not properly managed, could endanger drinking water sources and have other adverse impacts. However, 

the final, tailored, Class VI requirements address the large volumes of CO2 injected, its buoyancy, 

potential corrosivity in the presence of water, and potential impurities in the CO2 stream. In addition, 

EPA expects the tailored permitting, siting, construction, operation, monitoring, and post-injection site 

care requirements in the GS rule to prevent leakage from injection formations and protect USDWs. EPA 

acknowledges the comment on reduction of carbon emissions. This comment is outside the scope of the 

UIC Program’s authority under the GS rulemaking. 

Other EPA Comment Codes and Descriptions: 1430 1.2.1.2 Support EPA's authority to regulate CO2 

injection 

Comment: 43492-43541. We agree EPA has the authority under the Safe Drinking Water Act 

(SDWA) to propose regulations governing the protect Underground Sources of 

Drinking Water, but we believe Carbon Dioxide Sequestration Wells are: 1) 

dangerous and 2) unnecessary and should not promulgated. Also, we believe the 

Response: EPA disagrees that properly managed GS projects are dangerous. EPA believes that the GS 

requirements, which are based on the long-standing UIC regulatory framework and tailored to meet the 

unique nature of CO2 injection for GS, appropriately address endangerment risks to USDWs. The GS 

rule contains minimum technical criteria for the permitting, geologic site characterization, AoR and 

Commenter Name: B. Sachau Letter ID: 0105

Comment ID: 21939

Commenter Name: George Holliday, PhD, PE, BCEE Letter ID: 0114

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 22515

839
corrective action, well construction, operation, mechanical integrity testing, monitoring, financial 

responsibility, injection well plugging, post-injection site care, and site closure of GS wells, which will 

ensure that USDWs are protected from endangerment. 

EPA believes that the creation of a new injection well class (VI) under the existing UIC Program is 

necessary to enable the deployment of GS as a climate change mitigation technology in a manner that 

protects USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 3800 2.3 Proposed Injection Well Construction 

Requirements (40 CFR 146.86); 5000 2.8 Proposed Well Plugging and Post-Injection Site Care 

Requirements 

Comment: passing a written examination. Further, the Agency proposes to sequester 

buoyant CO2 until the end-of-time by only requiring 50 years of monitoring (40 

CFR 146.93(b)(1)). In addition, EPA proposes using well completion materials 

not currently developed and proven corrosion-resistant under carbonic acid 

corrosive conditions. 

The proposed regulations are a formula for future disaster: 1) Dangerous to 

sequester CO2, a supercritical fluid stored at high pressure (2200± psi): 2) 

Response: EPA does not believe that a properly managed GS site is dangerous. The Class VI GS 

regulation builds upon the long-standing protective framework of the UIC program, which has been 

regulating the injection of billions of gallons of liquids for decades. The Class VI GS regulation 

enhances this existing framework with requirements for Class VI wells that are tailored to the unique 

nature of large scale GS of CO2. 

EPA believes that a 50 year post-injection site care timeframe represents a reasonable and protective 

post-injection site monitoring period for most GS projects and available data, including data submitted 

by commenters, do not support a different default timeframe. EPA bases this on a review of research 

studies, industry reports, and existing environmental programs, and evaluation of public comments. EPA 

adds that the GS regulation includes a provision that the Director may, at their lengthen the postinjection site care timeframe if the owner or operator cannot demonstrate that movement of the plume 

and pressure front have ceased and the injectate does not pose a risk to USDWs (146.93(b)(2)). 

EPA disagrees that corrosion-resistant materials and cement do not exist. Industry experience of many 

decades in corrosive down-hole situations such as acid gas injection and production of natural gas with 

carbon dioxide and hydrogen sulfide impurities shows that materials are available that can resist 

corrosive environments. Meyer (2007) lists several types of cements that have been used under such 

corrosive conditions. EPA acknowledges that studies have likely not been performed to prove a 50-year 

life span for corrosion-resistant materials. However, there are two studies of wells that were exposed to 

CO2 for approximately 30 years by Carey et al. (2007) and Crow et al. (2008). Although these studies 

are limited in the number of well material samples and the number of wells examined, the casing and 

cement sampled indicate fairly good condition (i.e., fairly significant corrosion resistance) of well 

materials installed three decades ago. The best available corrosion-resistant materials suited for each GS 

project will be determined by the Director. 

EPA adds that, to address potential risks associated with high pressures associated with CO2 injection 

for GS, the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells 

Commenter Name: George Holliday, PhD, PE, BCEE Letter ID: 0114

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 22519

840
install automatic surface shut-off devices. Owners or operators must also monitor pressure in the 

injection zone, as required at §146.90(g). 

EPA acknowledges that there are limited data on this subject, and believes that providing multiple 

barriers of protection is the most appropriate approach to protecting USDWs from endangerment. See 

the discussion of Class VI well construction requirements in the preamble to the final GS rule for 

additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. 

This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

The Agency plans to, every six years, collect and review project data on early GS projects to determine 

whether the appropriate amount and types of information and appropriate documentation are being 

collected, and to determine if modifications to the requirements are appropriate or necessary. 

Comment: Carbon Capture and Storage (CCS) as a False Solution 

As carbon capture and storage is increasingly discussed as a possible mitigation 

option by some governments, it is necessary to highlight some critical 

limitations and concerns surrounding this technology. Serious problems are 

inherent with any CCS program. CCS is a very cost intensive procedure, it 

increases the costs of power generation by 40 to 80% compared with conventional 

power plants (depending on the location of the plant and the storage site, and 

the transport and capture technology used). In addition to the extra costs of 

operation, the US Department of Energy calculates that installing carbon capture 

systems will almost double plant costs.[FN3 3 National Energy Technology 

Laboratory (NETL), 2007, Cost and Performance Baseline for Fossil Energy Plants, 

NETL, August 2007, < http://www.netl.doe.gov/energy-analyses/pubs/Bituminous 

Baseline_Final Report.pdf>] This will lead to electricity price hikes of 

anywhere between 21 and 91%.[FN4 4 Rubin, E et al., 2005. Technical Summary in 

IPCC Special Report on Carbon Dioxide Capture and Storage, B. Metz et al., 

Editors. 2005, Cambridge University Press: Cambridge, U.K.] Additionally, using 

CCS technology greatly reduces the efficiency of power plants, up to 30% more 

fossil fuel must be burned to achieve the same power output.[FN5 5 Abanades, J C 

et al., 2005. Summary for Policymakers in IPCC Special Report on Carbon Dioxide 

Capture and Storage, B. Metz et al., Editors. 2005, Cambridge University Press: 

Cambridge, U.K.] Finally, CCS produces considerable additional long-term costs. 

Monitoring and verification over decades is necessary to guarantee the retention 

of the stored carbon dioxide. To have any potential climate benefit, buried CO2 

must remain underground forever. However, safe, permanent storage cannot be 

assured; the world has no experience with the deliberate long-term storage of 

anything, let alone CO2. The longest running storage project, Sleipner in 

Norway, is only 12 years old. While some geological reservoirs could have the 

specific combination of physical features and chemical processes that trap 

injected CO2 and essentially hold it for all time, there is insufficient data or 

practical experience to know whether there are enough. 

Response: EPA does not believe that GS is dangerous. The GS regulation builds upon the long-standing 

protective framework of the UIC program, which has been regulating the injection of billions of gallons 

Commenter Name: Emily Rochon Letter ID: 0129

Commenter Organization: Greenpeace International Comment ID: 23061

841
of liquids for decades. The GS regulation enhances this existing framework with requirements for GS 

wells that are tailored to the unique nature of large scale GS of CO2. These additional protective 

requirements include more extensive geologic testing, detailed computational modeling of the AoR and 

periodic re-evaluations, detailed requirements for monitoring and tracking the CO2 plume and pressure 

front, and extended post-injection monitoring and site care. 

EPA acknowledges that, because all GS in the U.S. is associated with pilot projects, there are unknowns 

regarding how GS projects will unfold and the practicalities of permitting, operating, monitoring, and 

closing a GS project. As a result, EPA is using an adaptive approach to regulating GS. EPA plans, every 

six years, to collect and review data on GS projects to determine whether the appropriate amount and 

types of information and appropriate documentation are being collected, and to determine if 

modifications to the requirements are appropriate or necessary. 

EPA clarifies that CCS operations and regulation of energy costs are not within the UIC Program’s 

authority. For additional information on EPA’s final regulatory approach, please see the final rule and 

preamble as well as the rulemaking docket. 

Comment: The Emperor has no clothes! This all seems like a sham, that will only create a 

lot of work for some people, cost taxpayers a lot of money over time, and 

continue a myth. 

Response: EPA does not believe that GS is dangerous. The GS regulation builds upon the long-standing 

protective framework of the UIC program, which has been regulating the injection of billions of gallons 

of liquids for decades. The GS regulation enhances this existing framework with requirements for GS 

wells that are tailored to the unique nature of large scale GS of CO2. These additional protective 

requirements include more extensive geologic testing, detailed computational modeling of the AoR and 

periodic re-evaluations, detailed requirements for monitoring and tracking the CO2 plume and pressure 

front, and extended post-injection monitoring and site care. For additional information on EPA’s final 

regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment: railroad system. We do not have as much coal as we have been told anyway, so all 

of these are very important as we think about this question of what to do and 

whether we should really be somehow thinking that the only way to address 

climate change is to burn coal and somehow try to smash a gas back into the 

planet and hope it does not come back out. It is completely absurd assumption in 

part because we do not have that much coal anyway. 

So, putting all that into context as we think about these rules, the 

sequestration space in our country and around the planet, but for now our 

country is going to be a very valuable commodity, so a fundamental concept 

behind these rules should be that sequestration space should only be used, 

because we can be pretty sure it is going to fail. We do not know it is probably 

not going to fail, it may or may not fail in our lifetimes because we have got a 

bunch of old folks in this room, but it -- we can be pretty sure that it will 

fail. As this country moves beyond the fossil fuel era and into the post fossil 

Commenter Name: Anonymous4 Letter ID: 0147

Comment ID: 21734

Commenter Name: Leslie Glustrome Letter ID: 0527

Comment ID: 21411

842
fuel era, how excited are we going to be -- or are future generations going to 

be about taking care of our carbon dioxide disposals sites? You know, they are 

going to have other things they are going to be tending to, all the other 

problems we have left them. 

Response: EPA does not believe that GS is dangerous. The GS regulation builds upon the long-standing 

protective framework of the UIC program, which has been regulating the injection of billions of gallons 

of liquids for decades. The GS regulation enhances this existing framework with requirements for GS 

wells that are tailored to the unique nature of large scale GS of CO2. These additional protective 

requirements include more extensive geologic testing, detailed computational modeling of the AoR and 

periodic re-evaluations, detailed requirements for monitoring and tracking the CO2 plume and pressure 

front, and extended post-injection monitoring and site care. 

Comment: So the fact, the concept that somehow they are going to be managing these sites 

for hundreds and thousands of years and paying great attention to them is just 

absurd. And we need to start with that assumption. They are not going to be well 

monitored and they are going to fail. Carbon dioxide is a gas, it is a corrosive 

gas and we can assume that it is going to fail in due time and we have got 

millions of wells around this country. So carbon dioxide space should only be 

used to sequester carbon dioxide that has been used for processes for which 

there is no reasonable alternative. That may be something like making cement or 

making steel. Our children and grandchildren may want to make that and they may 

need to use coal to do that. 

Response: As described above, EPA does not believe that GS is dangerous. The GS rule contains 

tailored requirements to address the unique nature of GS, including extensive geologic testing, detailed 

computational modeling of the AoR and periodic re-evaluations, detailed requirements for monitoring 

and tracking the CO2 plume and pressure front, and extended post-injection monitoring and site care. 

Comment: 80219 and I am here to comment today on EPA's underground injection control on 

CO2 and to talk about a number of reasons why this is a really, really bad idea 

and not someplace we should put billions of dollars. 

Response: EPA does not believe that GS is dangerous. The GS regulation builds upon the long-standing 

protective framework of the UIC program, which has been regulating the injection of billions of gallons 

of liquids for decades. The GS regulation enhances this existing framework with requirements for GS 

wells that are tailored to the unique nature of large scale GS of CO2. These additional protective 

requirements include more extensive geologic testing, detailed computational modeling of the AoR and 

periodic re-evaluations, detailed requirements for monitoring and tracking the CO2 plume and pressure 

front, and extended post-injection monitoring and site care. For additional information on EPA’s final 

regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Commenter Name: Leslie Glustrome Letter ID: 0527

Comment ID: 21412

Commenter Name: Nancy LaPlaca Letter ID: 0529

Comment ID: 21493

Commenter Name: Nancy LaPlaca Letter ID: 0529

Comment ID: 21496

843
Comment: And so the lesson for all of us I think is that it is up to us citizens. I have 

been working on coal issues for two years completely unpaid and myself and my 

friend filed a complaint against a gasified coal plant that was going to be 

built here in Colorado, Excel Energy was proposing to build an IGCC plant over 

4,000 feet elevation, get a $130 million from the feds to build a gasified coal 

plant here in Colorado and we let them know that this was not going to happen 

without a fight. They actually withdrew their proposal last October and are not 

building one here. However, states like Kentucky, Ohio, Illinois where there is 

a lot more political pressure, they are still getting stuck with these plants. 

Response: EPA clarifies that the regulation of coal gasification power plants is outside the scope of the 

UIC GS rulemaking. Rather, the purpose of the UIC GS regulation is to ensure that GS is conducted in a 

manner that protects USDWs from endangerment. EPA acknowledges the comment. Please see the 

remainder of EPA’s responses to this comment for further details. For additional information on EPA’s 

final regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 6000 3. Cost of the Proposed Rule 

Comment: Future Gen which some have dubbed Never Gen which is this prototype clean coal 

plant that was going to be built in South Illinois, but is now up in the air, 

that was going to cost a whopping $6,500 a kilowatt. To put that in, to compare 

that to other -- costs of other electric generation, wind is about even with 

escalated costs today about $2,000 a kilowatt to build a plant. Concentrating 

solar is about $3,000 or $4,000 a kilowatt, maybe $5,000 a kilowatt, but that 

includes storage, [indecipherable] salt storage. Nuclear power plants anywhere 

between $5,000 and $10,000 a kilowatt and incidentally in the energy bill right 

now, there is somewhere between 90 and 190 billion dollars in giveaways for 

nuclear industry and the energy policy act of 2008. 

Response: EPA clarifies that the GS rule addresses sequestration only, not capture or transportation. 

Any impacts on the cost of electricity are likely to be influenced by all aspects of CCS, including 

capture, transport, and sequestration. 

Comment: And so what have I learned from all of this? That wind is cheap. Energy 

efficiency is really, really cheap. Concentrating solar is here, it is now, it 

is working. It costs a fraction of what this gasified coal costs and what are we 

doing? We [indecipherable] our planet so all the young people that I see in this 

audience here, I see young people and I am afraid of what the world is going to 

look like when your hair looks like mine. I am fearful of that and I am 

fortunate to have a husband and a family that will let me quit my job and work 

for free full time on this issue so that we can stop this stupidity because all 

it takes is facts and information. And you know, we can whine and the coal 

industry is spending $100 million to convince us that coal is clean. Nothing can 

change this basic ratio. One pound of coal burned, three pounds of CO2; a very, 

very stable molecule that takes a lot of energy to compress, chill and then you 

pump it somewhere. This is absolute madness. 

Commenter Name: Nancy LaPlaca Letter ID: 0529

Comment ID: 21497

Commenter Name: Nancy LaPlaca Letter ID: 0529

Comment ID: 21498

844
And so I will submit my materials online. You know it is interesting, here in 

Colorado, Excel Energy was fighting a gasified coal plant in Minnesota. I think 

most of the testimony that we used was from Excel, so they were fighting against 

by a coal plant in Minnesota because they did not own it, and they wanted to 

build one here. Why? Because they want to put billions of dollars into 

[indecipherable] base and force rate payers, normal people to pay the bills. It 

is sort of like this bail out, but right now where you know, the big guys run 

away with the real cash so that when they make a profit, they get to keep it. 

When it does not work, they just stick it to the tax payers and so basically 

this is an incredible [indecipherable] and I hope we have the good sense for all 

the young people and all the people on this planet, the six billion people on 

the planet who are not part of the problem. They can only deal with what we here 

in the United States, 5% of the population creating 25 to 40% of the problems in 

the world deal them. 

Response: EPA clarifies that the regulation of coal gasification power plants is outside the scope of the 

UIC GS rulemaking. Rather, the purpose of the UIC GS regulation is to ensure that GS is conducted in a 

manner that protects USDWs from endangerment. EPA acknowledges the comment. Please see the 

remainder of EPA’s responses to this comment for further details. For additional information on EPA’s 

final regulatory approach, please see the final rule and preamble as well as the rulemaking docket. 

Comment Code: 1350 1.1.3.3 Comments on the need for GS technology 

Individual Comments 

Other EPA Comment Codes and Descriptions: 1310 1.1.2.4 Comments on other "out of scope" 

issues, e.g., pore space ownership; 3460 2.2.2.3 Acceptable corrective action techniques for GS sites 

(e.g., cements) 

Comment: For the past four years, our company has been field testing our 

proprietary systems and methods for utilizing a low melting point fusible metal 

alloy to mold in situ plugs in wells to repair gas leakage problems. Our focus 

has been on repair of vent gas flows that occur because of channels that exist 

within the cement surrounding production casing in wells. Our field tests have 

been carried out with permission of the Alberta Energy Resources Control Board 

("ERCB") and under their scrutiny. We presently have a proposal under 

consideration by the ERCB and the Canadian Association of Petroleum Producers 

(CAPP) to add our methods to the approved well abandonment protocols presently 

under review in Alberta. 

We believe our methods are directly applicable to the problem of long term 

leakage of sequestered GHG from wells that penetrate a reservoir used for the 

sequestration. Obviously, it makes neither economic nor environmental sense to 

capture, concentrate, compress, deliver, and inject CO2 into depleted reservoirs 

or saltwater formations if there is not a reliable sealing method used on 

Commenter Name: Homer Spencer Letter ID: 0120

Commenter Organization: Canitron Systems Inc. Comment ID: 22071

845
existing wells in that reservoir to prevent the CO2 leaking back into the 

atmosphere. We believe that our plugging methods can assure long term success in 

preventing this leakage. 

We use an alloy of bismuth and tin for our sealing medium. This alloy is nontoxic and will not corrode or cause corrosion in the relevant well environment 

from either chemical or galvanic processes. We believe we can seal a well 

against gas flow even if the well casing has been entirely corroded away. The 

important properties of the alloy that cause it to be effective are: 

1) it expands about 1% by volume when solidifying from the liquid phase; 2) it 

is impermeable to gas flow; 3) it seals effectively in dirty oily casing; 4) it 

has a high specific gravity to facilitate displacement of other fluids present 

during the deployment process; and 5) it has a very low viscosity and surface 

tension such that it will enter small fissures, and absorb into and wet 

permeable rocks such as sandstone. 

Only small amounts of the alloy are required to form a seal with the 

differential pressure strength required to seal GHG sequestration wells. We set 

the plugs using an electric heater deployed on a wire line. The procedure is 

both fast and inexpensive. We have data to back the above contentions, including 

corrosion tests carried out in a CO2/saltwater environment with a pH of 3 that 

indicate plug life in steel casing in excess of 10,000 years. 

Response: EPA thanks the commenters for the information on available well materials. EPA believes 

that the regulation affords owners or operators flexibility to use various materials and techniques to 

perform corrective action, provided they meet with the Director's approval. 

Other EPA Comment Codes and Descriptions: 1420 1.2.1.1 Support the GS rulemaking 

Comment: federal UIC regulations for the Geologic Sequestration of Carbon Dioxide. It is 

good to see that EPA has proposed a well defined, environmentally protective 

program through these rules for the geologic sequestration of carbon dioxide. 

I'm sure that EPA will receive many comments targeted at weakening or removing 

key parts of the proposed regulatory program; contrary to the arguments of some 

industry voices, geologic sequestration of carbon dioxide is new, untested 

technology that, if poorly implemented, could have large and long lasting 

environmental impacts including potentially degrading the quality of our ground 

water resources (USDW). Please help to encourage the use of this important 

technology by keeping a strong, environmentally protective regulatory program. 

One early disaster could destroy geologic sequestration of carbon dioxide as a 

strategy we can use to respond to rising atmospheric CO2 levels. Caution is 

warranted in the first set of regulations. Once experience with geologic 

sequestration has been gained, the regulations may be streamlined where 

appropriate. 

Response: EPA agrees that the implementation of the GS rule in a manner that ensures protection of 

USDWs from endangerment is important to establishing a foundation for further advances in the field of 

CO2 GS. EPA acknowledges the need for regulatory certainty: the final GS requirements provide a level 

Commenter Name: John Stormon Letter ID: 0123

Commenter Organization: Washington State Dept. of Ecology Comment ID: 22996

846
of certainty by setting forth unique requirements for GS. These requirements include: the tailored AoR 

delineation process at §146.84, the types of monitoring appropriate to GS projects at §146.90 and the 

post-injection site care process at §146.93. For additional information on these requirements, please also 

see the discussion of EPA’s Final Regulatory Approach in the preamble to the final GS rule. 

To protect USDWs from endangerment and meet the potentially fast pace of GS deployment, EPA is 

using an adaptive approach to regulating CO2 injection for GS. The Agency plans to collect and review 

data every six years on GS projects to determine whether the appropriate amount and types of 

information and appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. An adaptive approach will allow regulatory development to 

proceed in time to meet the current and future demands for Class VI permits, while EPA continues to 

gather data from pilot projects and other research as it becomes available. 

While EPA agrees with commenters that a stable, predictable, nationally consistent, and workable 

regulatory framework is important, EPA stresses that the focus of the GS rule is to ensure that, where 

GS is deployed, it is conducted in a manner that protects USDWs from endangerment. 

Other EPA Comment Codes and Descriptions: 1330 1.1.3.1 Support use of GS in general 

Comment: Given public concern over climate change, pending legislative proposals to 

sharply curtail carbon dioxide (CO2) emissions, and estimates that energy 

companies based in Houston and elsewhere could use anthropogenic CO2 to produce 

billions of barrels of oil that would otherwise not be produced, the 

Partnership believes it is important that carbon capture and storage (CCS) 

technologies become commercially available as soon as possible. In the near 

term, strategies employing CO2 sequestration for Enhanced Oil Recovery (EOR) will 

help commercialize the carbon capture technology and will help demonstrate the 

technology necessary for long-term storage of CO2 as a predicate to larger-scale 

CCS projects. The Partnership strongly supports regulatory efforts to strengthen 

incentives for EOR and other technologies focused on meeting the challenge of 

global warming while providing energy and enhancing our region's economic life. 

Response: EPA clarifies that the intent of the Class VI regulation is not to promote or encourage the use 

of GS, but, instead to ensure protection of USDWs where GS technologies are deployed. In addition, 

EPA clarifies that injection of CO2 for the purposes of enhanced oil and gas recovery will continue to be 

permitted under the Class II program, as long as any oil or gas production is occurring. The UIC GS 

requirements will apply to wells used for the purpose of long-term GS. 

Comment: 4. Support the development ofinnovative technologies for geologic carbon 

sequestration; 

Response: EPA clarifies that the UIC Program’s authority under SDWA is focused on ensuring 

protection of USDWs from endangerment. Promoting the use of GS or associated technologies is 

outside the scope of the UIC GS rulemaking. For additional information on EPA’s final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Commenter Name: Jeff Moseley Letter ID: 0155

Commenter Organization: Greater Houston Partnership (GHP) Comment ID: 21252

Commenter Name: Jeff Moseley Letter ID: 0155

Commenter Organization: Greater Houston Partnership (GHP) Comment ID: 21257

847
Comment: CCS Must be Deployed Quickly on a Very Large Scale 

Scientists agree that in order to avoid the worst consequences of climate 

change, the United States must cut greenhouse gas emissions at least 80 percent 

below 2000 levels by 2050. [FN7] The scale of CCS projects necessary in the 

electricity sector to achieve this objective is enormous. To store the two 

billion tons of CO2 emissions from annual fossil fuel electrical generation in 

the U.S. will require at least two hundred CCS projects, each 10 times larger 

than the largest sequestration projects currently in operation. [FN8] 

Worldwide, an estimated 6,000 of these projects would be needed. [FN9] 

Currently, only four large- scale commercial carbon sequestration projects exist 

worldwide. [FN10] 

[FN7: Luers, A.L. et al. 2007, How to Avoid Dangerous Climate Change: A target 

for U.S. emissions reductions. Union of Concerned Scientists, online at 

http://www.ucsusa.org/assets/documents/global_warming/emissions-targetreport.pdf] 

[FN8: Benson, S, 2004. Carbon Dioxide Capture and Storage in Underground 

Geologic Formations, Lawrence Berkeley National Laboratory, p. 15, available at 

http://www.pewclimate.org/docUploads/10-50_Benson.pdf (last visited Nov. 25, 

2008).] 

[FN9: International Energy Agency, Near-term Opportunities for Carbon Dioxide 

Capture and Storage, Global Assessments Workshop in Support of the G8 Plan of 

Action, June 2007 at p. 7] 

[FN10: The offshore Sleipner natural gas project in Norway, Snohvit in the North 

Sea, the InSalah natural gas project in Algeria, and the Weyburn Enhanced Oil 

Recovery project in Canada. IPCC CCS Technical Summary at 19; Wilson, E., 

Morgan, M. et al., Regulating the Geological Sequestration of CO2, Environmental 

Science & Technology, Apr. 15, 2008, at p. 4.] 

There is no time to waste to achieve this Herculean task. To have any meaningful 

role in curbing greenhouse gas emissions, CCS projects must proceed quickly 

while cognizant that there is no room for missteps. A team of international 

experts recently explained that "a single major accident, resulting from 

inadequate regulatory oversight, anywhere in the world, could seriously endanger 

the future viability of GS [geologic sequestration]." [FN11] 

[FN11: Wilson, E., Morgan, M. et al., Regulating the Geological Sequestration 

of CO2, Environmental Science & Technology, Apr. 15, 2008, at p. 5.] 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. However, EPA clarifies that the Class VI regulation 

does not promote or encourage the use of GS, but, instead ensure protection of USDWs from 

endangerment where GS technologies are deployed. 

EPA believes that the GS regulation will provide regulatory certainty and oversight that operators have 

requested, and allow for the deployment of this key climate change mitigation technology that could be 

deployed to reduce CO2 emissions. EPA adds that the GS regulation builds upon the long-standing 

Commenter Name: Kristin Henry Letter ID: 0242

Commenter Organization: Sierra Environmental Law Program, Sierra Club Comment ID: 23310

848
protective framework of the UIC Program, which has been regulating the injection of billions of gallons 

of fluids for decades. For additional information on EPA’s final regulatory approach, please see the final 

rule and preamble as well as the rulemaking docket. 

Other EPA Comment Codes and Descriptions: 1330 1.1.3.1 Support use of GS in general 

Comment: While it is not a "silver bullet", one important tool is the geologic 

sequestration (GS) of CO2 at properly selected and properly regulated sites. Our 

Environmental NGO Group does not necessarily have a common view concerning the 

magnitude of the long-term role of GS in combating climate change, but we are 

united in recognizing that a transition away from fossil fuels will take time 

and that GS is likely to be an important part of the near- to medium-term 

solution. Fortunately, capturing CO2 and permanently sequestering it in certain 

types of well-selected and well-managed geologic formations is a technology that 

is ready to begin deployment today. While GS projects can be permitted today 

under the Safe Drinking Water Act’s (SDWA) UIC program (in fact a number of 

projects have already been permitted under existing well classes), the rules 

that currently apply to such projects were not designed with geologic 

sequestration in mind. Thus, the importance of this rulemaking is not that it is 

needed in order for GS projects to receive permits; rather, the rulemaking is 

important because it can assure that GS projects are regulated under rules that 

are specifically designed to require GS projects to be done safely and 

effectively without endangering underground sources of drinking water (USDWs) 

or, as discussed below, resulting in a risk of release to the atmosphere. For 

that reason, it is essential that EPA promulgate final rules for GS in a timely 

manner that are sufficient to protect USDWs. 

Response: EPA agrees that GS is one technology in a portfolio of options, including solar, wind, 

biomass, and geothermal, that could be deployed to reduce CO2 emissions; however these technologies 

are outside the scope of the UIC GS rulemaking. The Class VI GS requirements are designed to ensure 

that, where GS is deployed to address climate change, projects are permitted sited, constructed, 

operated, and closed in a manner that avoids releases of CO2 into USDWs. 

Please see the remainder of EPA’s responses to this comment for further details. For additional 

information on EPA’s final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: One of the ways that we're doing that is by challenging coal fire power plants 

from being built in this day and age. We see this carbon sequestration, excuse 

me, I have a cold. We see this carbon sequestration as not a silver bullet to 

the carbon problem in our atmosphere. 

Response: EPA clarifies that the regulation of coal power plants is outside the scope of the UIC GS 

rulemaking. Rather, the purpose of the UIC GS regulation is to ensure that GS is conducted in a manner 

that protects USDWs from endangerment. For additional information on EPA’s final regulatory 

approach, please see the final rule and preamble as well as the rulemaking docket. 

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22270

Commenter Name: Becki Clayborn Letter ID: 0509

Commenter Organization: Sierra Club Comment ID: 21200

849
Comment: We have a joke within the Sierra Club that nature's version of carbon 

sequestration is called coal. We need to keep it in the ground, then you don't 

have to figure out how to put it back in the ground. 

I see one major flaw with this permitting process. And again, I'd like to thank, 

I want to make a point again of thanking everybody who works on this permitting 

process, because I believe that they're doing their jobs very well. 

However, this is only geological sequestration that's being addressed, it's not 

the entire life cycle of carbon capture and sequestration. It doesn't talk about 

the capture and transport of CO2, and it doesn't talk about leakage, and it 

doesn't regulate anything on air issues. 

The entire purpose of this rule as stated on the handout that's available back 

there, why is the proposed G.S. Rule needed? The capture and injection of CO2 

produced by human activities for long-term storage is one of a portfolio of 

options that can reduce CO2 emissions to the atmosphere, and helps mitigate 

climate change. 

The entire purpose of this rule is to keep CO2 out of the atmosphere, yet we're 

only allowed to talk about it in terms of how it affects drinking water. This 

does not make sense. This permit needs to be more comprehensive, it needs to 

take into consideration not just how it's going to affect drinking water, but 

how, how we're going to handle it if it does go back into the atmosphere. 

When we're challenging a coal fired power plant we talk to the utilities, and we 

talk to many utilities about how to mitigate and reduce their CO2 emissions. 

Many, many, many of them have come to us and said, we're planning on it, we're 

going to sequester, we're going to put it in the ground. 

But it doesn't mean anything unless it's in a permit, if it's not written down, 

if it's not in a legally binding document it doesn't mean anything. This permit 

process doesn't mean anything in terms of global warming emissions reductions if 

we can't write it down and put it in the permit. 

The fact that this has been a piecemeal process is typical in many of the 

processes we've seen in EPA, whether it's a coal mine, a coal fired power plant, 

there seems to be this spiraling effect of, let's talk about water over here, 

let's talk about air over here, let's talk about land use over here. 

When many of these projects, especially a project of this magnitude, when we're 

talking about relying on this technology to reduce the global warming emissions 

in our, in our atmosphere we have a huge goal ahead of us. 80 percent reduction 

by 2050 is what the scientists are telling us we need to do. If we're going to 

reach that we need to make sure that we're going to do this well, and it needs 

to be comprehensive, does not need to be a piecemeal permitting process. 

Commenter Name: Becki Clayborn Letter ID: 0509

Commenter Organization: Sierra Club Comment ID: 21202

850
Response: EPA clarifies that the regulation of coal plants or the use of coal is outside the scope of the 

UIC GS rulemaking. Rather, the purpose of the UIC GS regulation is to ensure that GS is conducted in a 

manner that protects USDWs from endangerment. 

EPA clarifies that climate change and CO2 emissions reductions are outside the scope of this 

rulemaking. The purpose of the Class VI GS rule is to ensure that where GS technologies are deployed, 

GS is performed in a manner that protects USDWs from endangerment. The requirements apply to 

owners or operators of injection wells used to inject CO2 for long-term storage. 

For additional information on EPA’s final regulatory approach, please see the final rule and preamble as 

well as the rulemaking docket. 

Comment Code: 1360 1.1.3.4 Effectiveness of trapping mechanisms 

Individual Comments 

Other EPA Comment Codes and Descriptions: 5280 2.8.2.4 USDW non-endangerment 

demonstrations 

Comment: - Page 43519. Consider explicitly referencing the work laid out by Benson to 

support the statement that physical and geochemical trapping mechanisms will 

help to improve the integrity of storage as time moves forward. This is a 

critically important "but widely misunderstood" point about how GS will work 

in practice. It would be good to include at least one citation to technical 

work to back up this point. 

o OTC 19244. Multi-Phase Flow and Trapping of CO2 in Saline Aquifers. Sally M. 

Benson, SPE, Stanford University. Copyright 2008, Offshore Technology Conference 

This paper was prepared for presentation at the 2008 Offshore Technology 

Conference held in Houston, Texas, U.S.A., 5-8 May 2008. 

Response: EPA added the Benson study to the final rule preamble (and has made it available in the 

rulemaking docket). 

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking 

comment) 

Comment: B. The Proposed 50-year Term for Post-Injection Site Care Is Unreasonably Long 

Denbury strongly objects to the use of a 50-year timeframe for continuous 

monitoring during post-injection site care. Our objection stems from the 

relative risks associated with the various phases of geologic storage 

operations, the recognized progression of various geologic trapping mechanisms 

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific 

Northwest National Laboratory

Comment ID: 

22665

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24282

851
(which means that risks of unexpected migration diminish over time), the 

creation of artificial impediments to financial assurance and the sagacity of 

other regulatory proposals. 

First, we believe that published and reputable literature suggests that a 50- 

year timeframe for post-injection site care is too long and wholly unrelated to 

the risks associated with geologic storage. For well-sited, characterized, 

operated and managed sites, the risks accumulate during the operational phase, 

but decline as sites move from post-injection site care to closure to eventual 

long-term care. Prevailing scientific opinion expects the risk profile to 

diminish with time.[FN35] As Lindene and Trabucchi suggest, "the risk of some 

events occurring that result in an unexpected release of carbon dioxide more 

than 10 years after termination of injection will become increasingly remote due 

to geochemistry conditions."[FN36] The geochemistry conditions they reference 

include the four main mechanisms which trap CO2 in well-chosen geological 

formations - 1) structural trapping -- which is addressed in the proposed rule 

and is not necessary to discuss further here; 2) residual CO2 trapping -- where 

CO2 is trapped by capillary forces in the interstices of the rock formation, a 

process which develops about 10 years after injection; 3) dissolution or 

solubility trapping -- where the CO2 dissolves into the brine found in the 

geological formation and sinks because the CO2 saturated brine is more dense 

than non-CO2 saturated brine, a process taking place between 10 and 100 years 

after injection; and finally, 4) mineralization or mineral trapping -- which 

occurs when dissolved CO2 chemically reacts with the formation rock to produce 

minerals, a process requiring hundreds of years.[FN37] 

Given that the greatest risk of a release occurs during the operational stage of 

a storage project, and that residual and dissolution trapping start well in 

advance of 50 years, it is difficult to understand why a 50-year timeframe for 

post-injection site care was chosen. A 50-year post-injection site care 

timeframe simply does not correlate to the relative risks associated with 

geological storage and the function of geologic trapping mechanisms that limit 

the risk of unexpected releases of CO2 after the termination of injection 

activity. 

Furthermore, other respected models use a much shorter period. For instance, the 

IOGCC Model Rules and Legislation stipulate a 10 year post-injection site care 

period.[FN38] Under the IOGCC Model, the operator of the storage site is the 

responsible party and is required to maintain an operational bond for the 

equivalent of a post-injection site care period and until closure. This 10 year 

post-injection site care period is more plainly related to the relative risks of 

geologic storage and the geochemical reactions discussed above. Also, in the 

preamble, EPA acknowledges that a 30-year post-closure care period is recognized 

as the industry standard for the injection of hazardous waste.[FN39] 

[35] See Intergovernmental Panel on Climate Change, Special Report on Carbon 

Dioxide Capture and Storage, 208 (Bert, Metz, et al. eds., 2005); see also Sally 

Benson, "Carbon Dioxide Capture and Storage: Research Pathways, Progress and 

Potential," Global Climate & Energy Project Annual Symposium, October 2007, 

available at 

http://pangea.stanford.edu/research/bensonlab/presentations/Carbon%20Dioxide%20C 

852
apture%20and%20St 

orage%20-%20Research%20Pathways%20Progress%20and%20Potential.pdf (hereafter 

"Benson 2007"). 

[36] Chiara Trabucchi and Lindene Patton, "Storing Carbon: Options for Liability 

Risk Management, Financial Responsibility," Daily Environment Report, Bureau of 

National Affairs, pg. 8 (Sept. 3, 2008). 

[37] See IPCC Special Report on CCS, supra n.2, at 208; see also Benson 2007, 

supra n.35. 

[38] See generally IOGCC, "Storage of Carbon Dioxide in Geologic Structures: A 

Legal and Regulatory Guide for States and Provinces" (September 2007) 

(publishing Model Statute and Rules for CO2 storage). The proposed 10 year 

default period for maintaining operator responsibility is at Model General Rules 

and Regulations, Section 2.0 (f) (defining "CSP Closure Period" as 10 years 

unless otherwise designated by the State Regulatory Agency). See also at Section 

4.0 (b) (10) (requiring performance bond to be maintained for 10 years after 

closure of the facility in accordance with Section 9.0). The discussion of the 

Model Statute and Regulation also mentions other potential periods of "10 or 29 

years, etc." IOGCC, supra, at 30. 

[39] See 73 Fed. Reg. at 43,510. 

Response: EPA agrees that some owners or operators will be able to demonstrate, in less than 50 years, 

that the pressure front and plume no longer pose a risk of endangerment to USDWs. However, based on 

studies, EPA believes that the 50-year default time frame is warranted in most cases based on additional 

review of research studies and reports and evaluation of public comments. 

EPA believes that the best way to address all possibilities, while ensuring USDW protection from 

endangerment, is to set a 50 year default post-injection site care timeframe, with flexibility to: (1) allow 

the Director discretion to shorten or lengthen the PISC timeframe during the PISC period based on sitespecific data, pursuant to requirements at §146.93(b); or (2) afford the Director discretion to allow a 

Class VI well owner or operator to demonstrate, based on substantial data during the permitting process, 

that an alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs 

pursuant to requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust the 

timeframe for a limited number of GS projects during the permitting process where substantial data 

exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on data 

collected during the PISC period, is appropriate to address the range of sites where GS is anticipated to 

occur, to accommodate site-specific circumstances and various geologic conditions, and addresses 

commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize site-specific 

data, and be based on pressure monitoring and USDW impacts. 

EPA clarifies that, in determining the post-injection site care-timeframe for the proposed regulation, 

EPA reviewed industry reports, existing environmental programs, and initial GS research studies. EPA 

provided a synthesis of pertinent results from GS modeling studies in the preamble to the proposed 

regulation. Further explanation of this analysis was included in an EPA-prepared background document 

that is available in the federal docket, titled ""Computational Modeling of Underground Injection of 

Carbon Dioxide for Determination of Area-of-Review and Potential Risk to Underground Sources of 

853
Drinking Water."" Based on review of these studies, modeling results indicate that the CO2 plume 

stabilization may occur on the timeframe of 10-100 years after the cessation of injection. EPA believes 

that a 50-year default post-injection site care timeframe is a reasonable midpoint for most GS projects 

and available data, including data submitted by commenters, do not support a different default 

timeframe, and has retained this in the final regulation. 

To the comment about the cost of post-injection site care, EPA does not agree that post-injection site 

care timeframes longer than 30 years will be prohibitively expensive. In fact, EPA believes that postinjection site care monitoring will represent a relatively minor component of total project cost, and will 

provide an essential level of protection from endangerment for USDWs. A discussion of the costs 

attributed to monitoring technologies (used during injection and the post-injection site care timeframes) 

is available in the Technology and Cost Document for the GS rule, which is in the federal docket for this 

rulemaking. EPA believes that it is logical to make use of existing monitoring infrastructure at a GS site 

in order to ensure USDWs are not endangered. 

EPA also recognizes the concerns associated with assuring financial responsibility for the long timeframes over which post-injection site care will be conducted. However, the Agency believes that, in 

order to protect USDWs from endangerment under the SDWA, operators must demonstrate under 

§146.85 that financial resources are available to plug the injection well and provide post-injection site 

care at the point in time that the first CO2 is injected. EPA is developing guidance on financial 

responsibility to assist owners or operators in evaluating the requirements of §146.85 and to assist 

Directors in evaluating financial responsibility demonstrations. The guidance describes the types of 

financial mechanisms that operators may choose to use when evaluating the financial responsibility 

requirements for GS wells and it will also include a section on how to estimate costs to support accurate 

financial responsibility demonstrations. The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Comment Code: 1370 1.1.3.5 US storage capacity 

Individual Comments 

Comment: For CCS to have a significant impact in reducing atmospheric concentrations of 

CO2 to reduce climate change, a significant amount would have to be stored. The 

IEA estimates that for CCS to deliver any meaningful climate mitigation effects 

by 2050, 6000 projects each injecting a million tons of CO2 per year into the 

ground would be required.[FN10 10 International Energy Agency (IEA) Greenhouse 

Gas R&D Programme, 2007. CO2 capture ready plants, 2007/4, May 2007.] At the 

moment, it is not clear that it will be technically feasible to capture and bury 

this much carbon, i.e. whether there are enough storage sites, or that they will 

be located close enough to power plants. National level estimates are largely 

based on modeled average values and therefore remain a source of considerable 

uncertainty.[FN11 11 Gough, C & Shackley, S, 2006. Towards a Multi-Criteria 

Methodology for Assessment of Geological Carbon Storage Options, Climactic 

Change 74, 2006, pp. 141-174.] The vast majority of these estimates quantify 

technical capacity assuming that the whole of a reservoir is accessible to store 

Commenter Name: Emily Rochon Letter ID: 0129

Commenter Organization: Greenpeace International Comment ID: 23066

854
CO2 in its pore volume. This can easily lead to unrealistically high numbers as 

the fraction of pore volume that can be used for CO2 storage is site-specific 

and depends on factors such as injection rate, relative permeability, density 

and mobility of fluids and rock heterogeneity. [FN12 12 Ibid ] Transport of CO2 

over distances greater than 60 miles is likely to be prohibitively 

expensive.[FN13 13 CSIRO submission to the Australian Parliamentary House of 

Representatives Inquiry in Geosequestration Technology, August 2006.] It is 

important to note however that the more CO2 that is stored, the greater the 

amount that would be released to the atmosphere if any leakage rate is accepted. 

Response: The UIC program’s authority under the SDWA focuses on ensuring that underground 

injection control activities, such as GS projects, are permitted, sited, constructed, operated, monitored, 

and closed in a manner that is protective of USDWs. Ensuring storage capacity is outside the scope of 

the Class VI GS rulemaking. 

EPA clarifies that other federal agencies (e.g., DOE and the U.S. Geological Survey) have conducted 

research on available storage capacity and made determinations of the feasibility of capturing and 

storing CO2 at the scales needed to address climate change. These agencies, along with private entities, 

have identified large areas for potential sequestration in capacity studies. For example, in 2008, USGS 

initiated development of a methodology for estimating the capacity to store CO2 in geologic formations 

of the United States. In 2009, USGS published a proposed, risk-based methodology for GS capacity 

estimation. This report, Development of a Probabilistic Assessment Methodology for Evaluation of 

Carbon Dioxide Storage, is available at http://pubs.usgs.gov/of/2009/1035/ofr2009-1035.pdf and is 

available in the rulemaking docket. 

Comment: EPA contemplates that the electric power sector "will most likely be the largest 

potential market for carbon capture and sequestration (CCS) technologies, with 

the potential to reduce CO2 by approximately 80-90% at an individual plant." 

EPA’s figure seems extremely optimistic and perhaps unrealistic given what we 

know about both current demonstration projects of carbon separation and geologic 

sequestration. We do not recommend that anyone assume that 80-90% of CO2 from 

the power sector can actually be separated and STORED or sequestered in all 

geologic formations given our current knowledge. While separation of CO2 from 

the other air emissions might be achievable at 80-90%, presuming this number for 

geosequestration that EPA offers seems overly rosy. See 73 Fed. Reg. 44354, 

44492. The oil and gas sector does not universally store 80-90% of the CO2 that 

is recycled in its current EOR/EGR operations. In our review of descriptions of 

current EGR/EOR, as much as 95% of the CO2 can be recycled many times and 

sometimes the remaining CO2 is ultimately vented to the atmosphere. 

Enhanced Oil Recovery Schematic Showing CO2 recycling (source: American 

Geological Institute) 

[Please refer to p. 17 of the pdf file for Figure 1.] 

Separation and storage capacities may be very different at each geologic 

formation or subsurface location. APPA is not offering this as a criticism of 

oil/gas operations but simply explaining that there are many myths about actual 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23390

855
retention of CO2 in oil/gas recovery operations and how translatable that 

experience is for the power plant sector. Regardless of the actual future volume 

Response: EPA acknowledges this comment. The purpose of the Class VI GS rule is to ensure 

consistency in permitting underground injection of CO2 at GS operations across the United States and 

provide requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to 

reduce CO2 emissions. 

In a separate rulemaking under authority of the Clean Air Act, EPA is amending the Greenhouse Gas 

Reporting Program at 40 CFR Part 98 to add reporting requirements for CO2 injection and geologic 

sequestration. The greenhouse gas reporting requirements build on the requirements outlined in the 

Class VI GS rule with the additional goals of verifying the amount of CO2 sequestered and collecting 

data on any CO2 emissions to the surface from Class VI GS facilities. 

Comment: Every other process when we have a carbon free alternative, that should be the 

first choice and that should be a criteria before carbon, a CCS project is 

approved because that CCS space, if we are able to find some spaces that are 

actually able to stand up to really thorough scientific analysis then that is 

going to be a very valuable site and it should only be used for processes that 

do not have a good alternative. 

Response: EPA acknowledges this comment. The purpose of the Class VI GS rule is to ensure 

consistency in permitting underground injection of CO2 at GS operations across the United States and 

provide requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to 

reduce CO2 emissions. EPA clarifies that approval of GS projects will be based on a demonstration that 

the CO2 injection will not endanger USDWs. The Class VI GS rule requires the owner or operator to 

provide extensive information to demonstrate to the Director, as specified at §§146.82 and 146.83, that 

the CO2 will be contained within the injection formation. EPA clarifies that siting and approval of 

facilities for capturing and transporting CO2 are outside the scope of the Class VI GS rule. 

Comment Code: 1380 1.1.3.6 Deployment of GS 

Individual Comments 

Other EPA Comment Codes and Descriptions: 1540 1.2.3.2 Climate change legislation 

Comment: However, we also believe that there are other barriers which may still impede 

the deployment of CCS, which cannot be addressed through existing legislative 

grants of power. Specifically, there are concerns governing short and long term 

liability, ownership issues, state and tribal sovereignty issues, and possible 

sequestration on the Outer Continental Shelf. Therefore, the Program for 

Interagency Cooperation is proposing legislation to address more of these 

Commenter Name: Leslie Glustrome Letter ID: 0527

Comment ID: 21413

Commenter Name: Victor B. Flatt Letter ID: 0103

Commenter Organization: The Center of Environment, Energy & Natural Resources 

Law (EENR Center), University of Houston Law Center

Comment ID: 

22490

856
barriers. It should be noted that while the Program for Interagency 

Environmental Cooperation supports the creation of new legislation to deal with 

CCS, much of the technical requirements which would be determined by the EPA 

under such proposed legislation are thoroughly addressed in this Proposed 

Rulemaking, meaning that the work and research done here would be equally useful 

in implementing the Program’s Proposed Legislation. 

Although the Call for Comments does not request legislative proposals, we 

provide the entire proposed legislation and accompanying white paper to provide 

context for evaluating whether this Proposed Final Rulemaking should also spur 

additional legislative action. While we support the Proposed Rule and the EPA 

moving forward with this Rule, the EPA also has the authority to suggest and 

comment on proposed legislation that furthers the agency’s environmental 

protection mandates. (42 U.S.C. Sec. 7609). We believe that in addition to 

implementing the Proposed Rule, that the EPA should also examine and suggest 

federal legislative changes that would further reduce legal and regulatory 

barriers to the deployment of CCS. 

Response: EPA clarifies that the SDWA does not provide EPA with specific authority to develop UIC 

regulations for GS that are not directly related to protecting USDWs from endangerment; thus EPA does 

not have authority under the SDWA to address issues related to CO2 pipelines, sub-surface property 

rights, and capture and transport of CO2. EPA clarifies that the GS rule does not address the status of 

CO2 as a pollutant or commodity. The UIC requirements regulate the injection of fluids. EPA 

recognizes that liability is an important issue to owners or operators but the Agency does not have 

authority under the SDWA to transfer long term liability from owners or operators to the state or federal 

government. Therefore, liability remains with the owner or operator. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

Comment: In addition to regulatory clarity, climate change policy will be needed to 

define a value for CO2 in order to drive deployment of CCS. After policy, cost 

will determine how quickly and widely CCS can be deployed. Currently, the value 

of CO2 is principally limited to its use in Enhanced Oil Recovery (EOR). The 

cost of CCS needs to be reduced by implementing requirements that are necessary 

and sufficient while not compromising the protection of drinking water. These are 

our principal concerns with the draft regulation: 

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23755

857
1 . EPA needs to categorically exclude CO2 specifically intended for geologic 

storage from the definition of RCRA hazardous waste. 

2. EPA must emphatically conclude that CO2 containing trace contaminants does 

not open any regulatory pathways to subjecting a geological storage site to 

Superfund liability. 

3. CLASS VI (Underground Injection Control (UIC) permits need to identify the 

potential for hazardous substances that might be generated in geologic 

formations after facility decommissioning and well closure so that should 

releases occur, they would be federally-permitted. 

4. Secondary confinement/containment should not be required. 

5. CO2 injection should not be restricted only to formations below the lowermost 

underground source of drinking water. 

6. EPA needs to clarify how to demonstrate financial responsibility; the 

proposed regulation leaves too much discretion to the Director. 

7. EPA should not adopt a pay-in period of three years. 

8. The period of post-injection site management should be performance-based and 

not be arbitrarily set at 50 years. . 

9. EPA should increase its state stakeholder effort towards uniformity of 

technical requirements; disparate requirements and processes will increase the 

time, cost, and complexity of projects. 

10. EPA should not stigmatize geological storage of CO2 such as can be inferred 

by having requirements for Class VI wells that are more restrictive than for 

Class II wells. 

11 . Requirements for conversion of any well to a Class VI well should be site 

and risk dependent. 

12. EPA's implied 2017 date for completion of the final UIC regulations is too 

late to provide regulatory clarity faced by CCS project developers today. 

Response: The purpose of the Class VI GS regulation is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

The UIC program’s authority under SDWA is focused on ensuring that GS projects are sited, 

constructed, operated, monitored, and closed in a manner that is protective of USDWs. EPA adds that 

setting a value for CO2 (i.e., a price per ton) is outside of the scope of the Class VI GS rulemaking. 

EPA acknowledges that GS falls within the broader context of CCS and the need for regulatory clarity to 

ensure that USDWs are protected from endangerment. In developing the final GS rule, the Office of 

Water coordinated with other Agency program offices and across federal agencies (e.g., with the 

Department of Energy; United States Geological Survey; Bureau of Ocean Energy Management, 

858
Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land 

Management). The Agency continues to evaluate areas of potential applicability of other Federal 

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and 

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the 

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will 

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies 

for owners or operators. For additional information, please see the discussion entitled "How Does This 

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the 

final GS rule. 

Please see the remainder of EPA's responses to this comment for further details. For additional 

information on EPA's final regulatory approach, please see the final rule and preamble as well as the 

rulemaking docket. 

Comment: Someone has to proactively address this difficult issue. With all these issues 

yet to be resolved, a reasonable conclusion is that commercial deployment of 

this technology is still years down the road. At this point, we ask EPA to lay 

Response: EPA clarifies that the Class VI regulations promulgated under Safe Drinking Water Act 

authority do not promote or encourage the use of GS, but, ensure consistency in permitting underground 

injection of CO2 at GS operations across the United States and provide requirements to prevent 

endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. EPA 

believes that the Class VI GS regulations, which build upon the long-standing, protective, regulatory 

framework of the UIC program, will provide the regulatory certainty and clarity that owners or operators 

have requested. 

EPA acknowledges that there are unknowns associated with early GS project deployment and the long 

term storage of CO2 for GS. For these reasons, the Agency is using an adaptive approach to regulating 

GS injection. The Agency will, every six years, collect and review data on GS projects to determine 

whether the appropriate amount and types of information and appropriate documentation are being 

collected, and to determine if modifications to the requirements are appropriate or necessary. 

Comment: 2008). At the same time, it is crucial for the regulations to reflect the 

challenges inherent in crafting controls for commercial CO2 injection and 

storage activities when such large-scale commercial operations are only at the 

nascent stage. Given what we know now, APPA remains rather skeptical that the 

large scale operations as envisioned by the popular or trade press (and perhaps 

EPA’s proposed rule’s preamble) are very possible in the next few decades. DOE’s 

original estimate that this new commercialized CCS industry is possible in about 

40 years is probably more realistic. Of course, APPA hopes that there are 

technology breakthroughs and that CCS or GS can be viable on larger scales which 

also remain protective of USDWs within the next 15 years. But we believe these 

larger commercial size power plants with > 10 tons of carbon sequestered 

annually would likely come online after 2025. We hold this hope on CCS in the 

same context as in hoping that there will be breakthroughs in large capacity

Commenter Name: Skiles Boyd Letter ID: 0160

Commenter Organization: DTE Energy Comment ID: 21269

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23392

859
battery storage or in storage for wind capacity or for new nanotechnology for 

solar panels. All are needed to achieve improvements in a power plants’ carbon 

footprint and in reducing criteria pollutants. While we may hope for technology 

and infrastructure breakthroughs, we plan on geologic sequestration based upon 

cold reality. The last thing that APPA wants is to promise what we might not yet 

be able to deliver. 

Response: EPA clarifies that the Class VI GS regulations promulgated under Safe Drinking Water Act 

authority do not promote or encourage the use of GS, but, ensure consistency in permitting underground 

injection of CO2 at GS operations across the United States and provide requirements to prevent 

endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. EPA 

believes that the Class VI GS regulations, which build upon the long-standing, protective, regulatory 

framework of the UIC program, will provide the regulatory certainty and clarity that owners or operators 

have requested. 

EPA acknowledges that there are unknowns associated with early GS project deployment and the long 

term storage of CO2 for GS. For these reasons, the Agency is using an adaptive approach to regulating 

GS injection. The Agency will, every six years, collect and review data on GS projects to determine 

whether the appropriate amount and types of information and appropriate documentation are being 

collected, and to determine if modifications to the requirements are appropriate or necessary. 

Comment: Promote CCS Development 

A CCS policy regime should be designed to encourage CCS, in addition to serving 

other public goals -- such as promotion of energy security, economic stability. 

and protection of USDWs, human health and the environment. 

Sound Risk Management 

Federal and state policy should encourage owners, operators, technology 

companies, engineering firms, utility regulators, and others involved in the CCS 

chain to take appropriate action to ensure safe and reliable operation of GS 

sites and systems, minimize risks, and allow CCS to earn broad public 

acceptance. 

Response: EPA clarifies that the Class VI GS regulations promulgated under Safe Drinking Water Act 

authority do not promote or encourage the use of GS but, ensure consistency in permitting underground 

injection of CO2 at GS operations across the United States and provide requirements to prevent 

endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. EPA 

believes that the Class VI GS regulations, which build upon the long-standing, protective, regulatory 

framework of the UIC program, will provide the regulatory certainty and clarity that owners or operators 

have requested. 

EPA acknowledges that there are unknowns associated with early GS project deployment and the long 

term storage of CO2 for GS. For these reasons, the Agency is using an adaptive approach to regulating 

GS injection. The Agency will, every six years, collect and review data on GS projects to determine 

whether the appropriate amount and types of information and appropriate documentation are being 

collected, and to determine if modifications to the requirements are appropriate or necessary.

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23798

860
EPA agrees that input of and participation by a wide spectrum of stakeholders is a vital component of 

successful rulemaking. The Agency appreciates the degree of cooperation, participation, and active 

dialogue between the EPA and stakeholders and will continue to work with stakeholders and experts as 

it implements the Class VI GS rule. 

Comment: A. RECOGNITION OF THE IMPORTANCE OF SPURRING THE DEVELOPMENT OF 

CCS TECHNOLOGY 

The Proposed Rule recognizes the value of promoting CCS technology. With further 

modification and a broader scope, these regulations could encourage 

substantially the safe deployment of CCS technologies, support the construction 

of new fossil fuel-fired generation, promote capital formation, and broaden the 

availability of risk management mechanisms for CCS projects. The costs and 

benefits associated with protecting USDWs must be the focus of the Proposed 

Rule, but account has to be taken of the reality that such protection is 

inextricably linked to the mitigation of climate change risk. 

Response: EPA clarifies that the Class VI GS regulations promulgated under Safe Drinking Water Act 

authority do not promote or encourage the use of GS, but, ensure consistency in permitting underground 

injection of CO2 at GS operations across the United States and provide requirements to prevent 

endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. EPA 

believes that the Class VI GS regulations, which build upon the long-standing, protective, regulatory 

framework of the UIC program, will provide the regulatory certainty and clarity that owners or operators 

have requested. 

EPA acknowledges that there are unknowns associated with early GS project deployment and the longterm storage of CO2 for GS. For these reasons, the Agency is using an adaptive approach to regulating 

GS injection. The Agency will, every six years, collect and review data on GS projects to determine 

whether the appropriate amount and types of information and appropriate documentation are being 

collected, and to determine if modifications to the requirements are appropriate or necessary. 

Comment: sequestration activities will remain questionable. In the meantime, EPA may 

modify the rule and consider proceeding with its implementation for depleted oil 

and gas reservoirs. Since these reservoirs have been extensively studied in the 

past, it is likely that enough data exists to ensure safe operations at some of 

the reservoirs under certain conditions. 

Response: EPA clarifies that the Class VI GS rule applies to all injection of CO2 into the subsurface for 

the purpose of long-term storage regardless of the type of injection formation. The Class VI GS siting 

requirements allow GS projects to be permitted if the owner or operator can demonstrate, to the Director 

that a proposed site has geologic formations suitable to receive and confine the injected fluids in order to 

ensure protection of USDWs from endangerment. EPA acknowledges that depleted oil and gas 

reservoirs associated with ER operations may be used for CO2 storage and that these sites may be some 

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23807

Commenter Name: Saba Tahmassebi Letter ID: 0218

Commenter Organization: Oklahoma Department of Environmental Quality 

(DEQ)

Comment ID: 

21562

861
of the first sites where commercial-scale GS is deployed. However, these wells can only be permitted if 

owners or operators can demonstrate that injection into other formations meet the Class VI GS 

requirements. 

Comment: Although the rule is geared specifically toward well operators there are several 

components that may affect potential upstream industrial clients, and are of 

great interest to TFI members. In fact, EPA must carefully consider the 

applicability of this rule and ensure that it covers large industrial 

manufacturers such as nitrogen fertilizer producers. 

Response: The purpose of the Class VI GS regulation is to ensure consistency in permitting 

underground injection of CO2 at GS operations across the United States and provide requirements to 

prevent endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

The UIC program’s authority under SDWA is focused on ensuring that GS projects are sited, 

constructed, operated, monitored, and closed in a manner that is protective of USDWs. EPA clarifies 

that the Class VI GS regulation applies to all injection of CO2 for the purpose of GS, regardless of the 

source of the CO2. Requiring or setting standards for upstream generators of CO2 is outside the scope of

the Class VI GS rulemaking. 

In a separate rulemaking under authority of the Clean Air Act, EPA is amending the Greenhouse Gas 

Reporting Program at 40 CFR Part 98 to add reporting requirements for CO2 injection and geologic 

sequestration. The greenhouse gas reporting requirements build on the requirements outlined in the 

Class VI GS rule with the additional goals of verifying the amount of CO2 sequestered and collecting 

data on any CO2 emissions to the surface from GS facilities. 

Comment: Global warming has to be attacked on several different layers, clean energy 

should be first, energy efficiency should be first, using less, having renewable 

energies, wind and solar, and reducing the need for fossil fuels to be burned. 

We believe that is actually the way to keep carbon out of the atmosphere and not 

just figuring out how to put it in the ground and hoping it'll stay there. 

Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. However, the use of and investment in these 

technologies is outside the scope of the Class VI GS rulemaking. The Class VI GS requirements are 

designed to ensure that, where GS is deployed, projects are permitted, sited, constructed, operated, and 

closed in a manner that protects USDWs from endangerment. 

Comment: While we acknowledge that geologic carbon sequestration has been identified as a 

means to combat climate change, we urge caution as we proceed with this 

technology. Thank you. 

Commenter Name: Bill Hertz Letter ID: 0500

Commenter Organization: Fertilizer Institute Comment ID: 21206

Commenter Name: Becki Clayborn Letter ID: 0509

Commenter Organization: Sierra Club Comment ID: 21201

Commenter Name: Cynthia Lane Letter ID: 0528

Commenter Organization: American Water Works Association (AWWA) Comment ID: 21392

862
Response: EPA agrees that GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy sources, 

that could be deployed to reduce CO2 emissions. However, the use of and investment in these 

technologies is outside the scope of the Class VI GS rulemaking. The Class VI GS requirements are 

designed to ensure that, where GS is deployed, projects are permitted, sited, constructed, operated, and 

closed in a manner that protects USDWs from endangerment. 

Comment: And secondly, I do have to doubt the capability of these DOE funded projects to 

provide the ultimate or deciding vote if you like on how to regulate and how to 

craft the regulatory language. I think there is, there will be some lessons that 

will be learned from those. There will be new data available. There will be some 

research that will take place, but ultimately I think that this program is too 

little, too late and I also do not think that it is a prerequisite for drafting 

good rules. There might be some need for revision, but the best way to get that 

experience and to that knowledge is to move ahead with a handful or two of large 

scale injections and that will be the best possible learning experience. 

Response: The final rule is based on the most recent GS-related data, information, and scientific 

research available. In addition to laboratory studies and modeling research that provide relevant 

information on GS, the Agency is also collecting and analyzing GS project data and permit information 

from a variety of sources. Most notably, EPA has evaluated permits and reviewed operational data and 

information associated with the seven regional carbon sequestration partnerships funded by the U.S. 

Department of Energy and coordinated through the National Energy Technology Laboratory. EPA 

believes that this data forms a solid basis for finalizing the Class VI GS requirements, and there is no 

reason to wait until all phases of the DOE demonstration tests are complete. Nevertheless, EPA 

anticipates that future experimental and full-scale projects will continue to inform the technology, and is 

therefore using an adaptive rulemaking approach. EPA plans, every six years, to collect and review data 

on GS projects to determine whether the appropriate amount and types of information and appropriate 

documentation are being collected, and to determine if modifications to the requirements are appropriate 

or necessary. 

Other EPA Comment Codes and Descriptions: 2400 1.8 Comments on EPA's adaptive rulemaking 

process 

Comment: Climate change will not wait and I think it will have a profound effect on 

drinking water results itself and I really do believe that USDWG will suffer if 

we do nothing about climate change. And I think sequestration as I said can be 

effective. 

I would like to end with a note on scale and timing. I do not believe that we 

are ready to proceed with wide scale deployment of sequestration all around the 

country. It is something we saw a hundred permit application as soon as rules 

promulgated and I do think this is premature. We are not ready to move in that 

direction. Nonetheless I think by the nature of the beast and the current 

economics of CCS, we will not see that happen. What we are talking about here is 

an initial wave and an initial set of projects that would be permitted and then 

Commenter Name: George Peridas Letter ID: 0534

Commenter Organization: Natural Resources Defense Council (NRDC) Comment ID: 21456

Commenter Name: George Peridas Letter ID: 0534

Commenter Organization: Natural Resources Defense Council (NRDC) Comment ID: 21465

863
studied intensely. And I think those will inform how we think about 

sequestration, whether we indeed need or do not need any revisions to the 

regulations and also how we manage projects. I think ultimately if CCS is to 

deliver on its promise to reduce greenhouse gasses, then yes we will need to 

deploy this at a wide scale. But this is not something that will happen over 

five years. Some we will scale up to overnight. There will be ample time, study 

and reassessments. 

Response: EPA believes that there is a potential that GS may be deployed at a fast pace (e.g., if climate 

change legislation provides an incentive for sequestering CO2 or if other climate policies or regulations 

limit CO2 emissions), and that it is necessary to prepare for such an event. EPA's adaptive approach to 

regulating CO2 injection for GS will allow regulatory development to proceed in time to meet the 

current and future demand for Class VI permits while recognizing the need to continue to gather data 

from pilot projects and other research as it becomes available and enhance understanding of the 

technical and administrative aspects of GS deployment, operation, and technology developments. 

864