2.1 Responses to Public Comments on Geologic Siting Requirements

This file contains responses to public comments on geologic siting for Class VI wells

(comment codes 3100 to 3150).  This section includes comments on the need for

injection and confining zones and required permit information.

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

2.1 Proposed Geologic Siting Requirements (40 CFR 146.83) 3100

2.1.1 Proposed siting requirements (i.e., injection/confining zones, trapping mechanism) 3110

2.1.2 Need to identify additional confining and containment zones   3120

2.1.3 Comments that operators should submit more (or different) geologic data than

proposed

3130

2.1.4 Comments that the proposed geologic data requirements are too stringent 3140

2.1.5 Comments on required permit information (40 CFR 146.82) 3150

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: 3100 2.1 Proposed Geologic Siting Requirements (40 CFR 146.83) 

Individual Comments

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24764

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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.

Please see the final rule and the discussion of geologic site characterization in the preamble for

additional information.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24767

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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.} 

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.

Commenter Name: Dwight Lockwood, PE, QEP Letter ID: 0141

Commenter Organization: Global Energy, Inc. Comment ID: 23090

Comment: 1. The siting criteria, including defining of the appropriate Area of Review, 

seismic evaluation, extensive modeling and characterization are sufficiently 

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rigorous that it is reasonable to anticipate minimal risks of leakage will exist 

long term. This minimal risk therefore argues in favor of a simple and 

pragmatic program. 

Response: EPA acknowledges the comment and 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.

Commenter Name: Brianne Metzger Letter ID: 0151

Commenter Organization: Spectra Energy Corp Comment ID: 21844

Other EPA Comment Codes and Descriptions: 2100 1.6 Target Geologic Formations for GS 

Comment: I. Large-Scale GS Operations Must Not Impact The Storage Of Hydrocarbon Natural 

Gases. 

One concern with GS is the potential implications for and impact on large-scale 

natural gas storage operations. Under SDWA, hydrocarbon natural gas storage is 

exempt from current UIC regulations governing injection activities. Spectra is 

concerned about the potential implications and impacts on underground gas 

storage from the Proposed Rule. Natural gas storage is regulated by State and 

interstate entities, such as Interstate Oil and Gas Compact Commission (IOGCC), 

that oversee the siting, permitting, design, construction, and operations of 

wells. Within the U.S., natural gas storage is generally located in two major 

geologic formations, porous rock reservoirs and salt caverns. Generally, the 

types of storage fields that will potentially be impacted by the Proposed Rule 

are porous rock reservoirs. Because many of the areas and geologic formations 

considered for GS will be in the same basins and may occur within or in close 

proximity to the same geologic strata, there is the potential for gas storage 

fields to be adversely impacted by GS. In order to avoid any unintended 

impacts to natural gas storage operations, there are several issues that need 

to be considered. 

First, gas storage wells are regulated by State oil and gas regulatory 

agencies. Individual States have a critical role in protecting and regulating 

the competing economic interests involved in utilizing the subsurface, not only 

for natural gas storage but also oil and gas production or other subsurface 

activities. Many State oil and gas regulations specify well siting or 

construction requirements for any wells that are drilled within a gas storage 

area or penetrate the storage horizon. Spectra suggests that appropriate 

regulatory agencies in individual States be active participants with the EPA in 

the GS permitting process, to ensure appropriate State knowledge of local 

geology is considered in a technical evaluation of the suitability of potential 

GS zones, and for the balanced protection of gas storage and other economic 

interests. We believe the EPA should affirm the authority of the States to 

require the GS operator to comply with all well construction and monitoring 

requirements to protect the integrity of gas storage reservoirs. 

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Second, as part of the site selection and GS permit application process, all 

natural gas storage projects within the AoR should be identified on the AoR map 

and assessments performed to determine the potential impact from CO2 or fluid 

migration to the gas reservoir. Such an assessment should also include 

analysis of potential leak paths through faulting, fracturing, or other 

migration paths from injected CO2 in formations in close proximity to gas 

storage reservoirs. 

Third, we would recommend that where GS and gas storage reservoirs are in close 

proximity that additional monitoring be required. We are also concerned about 

the potential impact of hydraulic fracturing of GS wells on natural gas 

storage. We believe that an analysis should be conducted based on the 

proximity (laterally and vertically) of the GS zone to existing gas storage 

reservoirs and the potential for communication with a gas storage reservoir. 

For this reason, we believe it is important that all records relating to well 

logs, cementing records, and casing strings and cementing operations of any GS 

wells drilled within the reservoir or protective perimeter boundaries of a gas 

storage field must be available and accessible to the public. Conversely, and 

for the same reasons, we believe information regarding the proximity of gas 

storage reservoirs to GS wells is equally important and should be readily 

available to the public to ensure the integrity of the CO2 injection operation. 

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. 

Under §146.82(a)(2) owners or operators must identify all injection and production wells, which will

most likely include evidence of and information about the location of natural gas storage sites. The

Director must evaluate this information when determining whether to issue a permit. While the GS

rule does not explicitly require the owner or operator to identify natural gas storage sites within the

AoR, the Director may require additional site-characterization or data collection at his or her

discretion. For example, the Director may require additional monitoring under §146.90(i) to ensure

that GS does not interfere with existing natural gas storage projects. The site characterization

requirements at §146.82 will also help determine the existence and locations of any faults and

fractures.

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 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. Additionally, EPA

expects that this guidance will support permitting authorities as they evaluate initial permits for Class

VI injection wells with technical assistance as needed. The guidance can be found on EPA’s website

at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

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EPA expects permitting authorities to retain an administrative record for the project, which at the

discretion of the permitting authority might be available online and at the authority's office. EPA

encourages (but does not require) operators and permitting agencies to begin involving the public by

providing information as early in the GS project development process as possible. 

In response to the comment that state gas agencies should be involved in permitting decisions, EPA

clarifies that the decision to issue a permit rests with the agency implementing the Class VI Program,

as identified in the state's approved primacy application. If a state or tribe chooses not to seek

primacy for Class VI program implementation, EPA will directly implement the program for the

state or tribe. However, the final rule includes a requirement that state and local oil and gas

regulatory agencies and state agencies regulating mineral exploration and recovery must be notified

when a draft Class VI permit is available for public comment, at §124.10(c)(1)(xi).

Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality

(MDEQ)

Comment ID:

22126

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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).

Commenter Name: Sandi Tabor Letter ID: 0162

Commenter Organization: Lignite Energy Council (LEC) Comment ID: 21296

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

Long-Term Care Requirements 

Comment: Third, EPA must develop financial assurance and risk management regulations that 

clarify the long-term obligations and risk associated with a GS project. One way 

to meet the EPA's dual goal of protecting the environment while facilitating the 

development of CCS is to focus regulations on proper site characterization. 

Proper site selection and characterization will help minimize potential future 

risks and lessen the need for default provisions that apply to all sites. 

Response: EPA agrees that proper site characterization is important to minimizing risks associated

with GS, but also believes that assuring financial responsibility for corrective action on Class VI

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. The goal of

the financial responsibility requirements at §146.85 are 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. See

the final rule and preamble for further discussion of EPA's final approach to financial responsibility.

EPA expects that the cost of financial responsibility will depend heavily on the estimated cost of

covered activities as well as certain site-specific factors and their project phases. Under the final

rule, the cost estimate must be performed for each phase of the GS project separately and must be

based on the costs to the owner or operator of hiring a third party to perform the required activities.

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Additionally, during the active life of the GS project, the owner or operator must adjust the cost

estimate for inflation within 60 days prior to the anniversary date of the establishment of the

financial instrument(s) to demonstrate financial responsibility. In order to assist owners or operators

and financial institutions in achieving accurate cost estimates, EPA plans to include a guidance that

includes discussion of how best to estimate costs, including how to adjust cost estimates for

inflation, in its guidance on meeting financial responsibility requirements for GS wells.

Commenter Name: James Devine Letter ID: 0166

Commenter Organization: United States Geological Survey (USGS) Comment ID: 21350

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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.

Commenter Name: Michael Mudd Letter ID: 0167

Commenter Organization: FutureGen Alliance (FGIA) Comment ID: 22467

Comment: A-1. Proposed Geologic Siting Requirements III-A-1. This section mentions 

several types of geologic/geochemical/geomechanical information needed to 

assess a site’s viability. EPA should specify the information required to 

support this analysis. 

Response: 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 characterize 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 is

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also developing a number of technical guidances and implementation materials to assist owners or

operators and Directors in the permitting process. These guidances will provide recommendations 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 draft

guidance material can be found on EPA’s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24150

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

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

same as the existing definition at §148.2, to address transmissive faults and fractures that extend

beyond the confining zone.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24152

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 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)).

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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.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24154

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 

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.

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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. 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.

Commenter Name: James Taft Letter ID: 0172

Commenter Organization: Association of State Drinking Water Administrators

(ASDWA)

Comment ID:

23450

Other EPA Comment Codes and Descriptions: 1510 1.2.2.3 Need for additional study 

Comment: Specific Comments 

Geologic Siting Requirements and Area of Review (AOR) 

Additional Research and Data Needed: 

More research and data are needed, than are typically available now, to make 

scientific determinations as well as implement proven methods to ensure the 

integrity of the proposed geologic sites, without displacement of existing USDW. 

Such research and data will be particularly important with regard to 

characterizing the thickness of the confining zone and permeability. 

Response: EPA agrees that continued research will be integral to development of GS technology,

but disagrees that the Agency is unable to ensure the integrity of the proposed geologic sites.

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

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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 collect and

review data every six years on GS projects to determine whether the appropriate amount and types of

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

requirements are 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: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23479

Comment: 5. Siting of CO2 GS Wells 

As a general matter, USWAG believes that EPA must consider the potential impact 

of CO2 GS projects on other pre-existing subsurface activities (e.g., natural 

gas storage operations). In particular, the Final Rule should ensure that final 

Class VI permits not inappropriately interfere with these other pre-existing 

subsurface interests and operations. 

With respect to the types of formations into which CO2 may be injected for GS 

under the UIC Program, it is counterproductive at this stage in the development 

of the CO2 GS regulatory regime to categorically preclude any potentially 

feasible injection formations as possible long-term storage sites. EPA 

recognizes that the commercial deployment of CO2 GS activities will result in 

the new production of large volumes of CO2 for which Owners or Operators will 

have to locate new and environmentally protective injection zones. In fact, the 

GAO Report anticipates a need to permit thousands, if not tens of thousands, of 

additional UIC wells to accommodate the increased volumes of CO2 expected to be 

captured in a large-scale CCS program. GAO Report at 40. Therefore, it makes 

sound policy sense for EPA to encourage the identification and utilization of as 

many injection zones as possible, with the prerequisite that injection at any 

site be protective of USDWs. 

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.

The final rule does not preclude injection into any formations or types of injection sites provided that

the wells meet the final GS rule requirements. The purpose of the GS regulation is to ensure that

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injection of CO2 for GS is conducted in a manner that is protective of USDWs. This includes

appropriate site characterization and identification of geologic formations that are amenable to

injection of potentially large volumes of CO2 for long-term storage. The regulation provides

flexibility to owners or operators to select appropriate sites and target formations (under §146.82),

well construction specifics (under §146.86), and injection procedures 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.

Commenter Name: Pamela Faggert Letter ID: 0175

Commenter Organization: Dominion Comment ID: 23518

Comment: 2. Siting 

Dominion agrees that proper site selection is critical to a successful GS 

project. Appropriate siting can minimize or eliminate risk of potential threats 

to USDW that GS may pose. However, several of the contemplated requirements and 

restrictions in the Dominion Comments on Proposed Regulation of CO2 Injection 

Wells proposal are unnecessary for the protection of USDW and could discourage 

the development of CCS. 

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 longterm storage. 

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 (§146.83(b)).

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23551

Other EPA Comment Codes and Descriptions: 1310 1.1.2.4 Comments on other "out of scope"

issues, e.g., pore space ownership; 2100 1.6 Target Geologic Formations for GS; 3120 2.1.2 Need to

identify additional confining and containment zones (seeking comment) 

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. 

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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.

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23567

Comment: It is also important to keep in mind the enormous extent to which proper site 

characterization will minimize any potential risks posed by CO2 storage. Proper 

site characterization is the most effective risk management tool for CCS. 

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. 

Response: The Agency agrees with the commenter about the importance of proper site selection and

believes that the site characterization requirements in the GS rule are essential to ensuring that a GS

11
project will not endanger USDWs. The GS injection requirements, under SDWA authority, ensure

protection of USDWs from endangerment through assessment of the suitability of an injection zone

(146.83), appropriate site characterization (§146.82), and area of review evaluation (§146.84) among

other requirements. The GS requirements are designed to ensure protection of USDWs from

endangerment by requiring that injection wells are not only sited properly, but permitted,

constructed, operated, monitored, and plugged in a manner that does not endanger USDWs.

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23577

Comment: B. Siting and Secondary Containment 

Our first area of concern relates to proposed provisions for the siting of GS 

projects, including requirements related to project site geology and permissible 

receiving formations. 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. 

Response: EPA disagrees that any of these protective requirements are unnecessary, and clarifies

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. 

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 (§146.83(b)), based on his or her understanding of a particular site.

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23853

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards) 

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. 

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 

12
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).

Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23624

Other EPA Comment Codes and Descriptions: 3110 2.1.1 Proposed siting requirements (i.e.,

injection/confining zones, trapping mechanism) 

Comment: 146.83 

(a)(2) 

Modify this section to indicate that the confining zone is "reasonably expected" 

to be free of faults and fractures that are transmissive. Again, the behavior of 

a given fault or fracture in an area cannot be conclusively proven with respect 

to its impact on fluid flow except by analogy to oil field or gas storage field 

performance. There is no mechanism to carry out a subsurface test of a fault 

except possibly in the case of multiple wells opportunely place on opposite 

sides of a defined fault to access a transmissive unit which can be pressure 

pulse tested and can be isolated by packers or other equipment. Such tests 

(obviously) are unlikely to work in a confining zone due to its low 

permeability. 

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. 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. At sites

where deep faults (even with little or no surface expression) are present, processing and interpreting

data from multiple geophysical sensing methods has been shown to detect faults better than analysis

of data from individual methods (Goussev et al, 2004). Drilling through faults or fractures with

appropriate well design, materials, and operation, would not result in an increase in their

permeability or a decrease in CO2 containment properties of the related CO2 storage reservoir. In

some cases, the use of complementary drilling and geophysical methods might provide the most

dependable characterization of potential transmissive faults and 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. 

EPA acknowledges that some smaller fractures may not be detectable during the site characterization

13
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. 

Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23625

Comment: (b) 

The words "allow for pressure dissipation" are unclear in meaning with respect 

to additional zones. If there are no formations in the stratigraphic column at a 

sequestration site which have been depleted below original reservoir pressure 

due to hydrocarbon production, all zones are likely to be at hydrostatic 

pressure (or overpressured, as in parts of the Gulf Coast Basin). Only in a few 

instances are formations encountered that have never been drilled and are at 

less than the basinal hydrostatic pressure gradient. This is the only case where 

leakage into such a unit may "allow for pressure dissipation". Is that what is 

meant here? I suggest this phrase be carefully reviewed and considered for 

deletion. 

Response: EPA clarifies that the primary purpose of the requirement for identification of additional

confining zones where needed is to improve USDW protection in cases where a primary confining

zone may not be sufficient to meet the UIC programmatic requirement to protect USDWs from

endangerment. The Agency acknowledges that the additional confining formations may also, in sitespecific circumstances, further impede vertical fluid movement, provide additional sites for

monitoring, mitigation, and remediation, and allow for pressure dissipation.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23728

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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.

14
Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24377

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

Comment: Part 146.83(a)(2) AWWA recommends revising this part to read: 

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.

Commenter Name: Adam P. Haynes Letter ID: 0184

Commenter Organization: Texas Independent Producers and Royalty Owners

Association (TIPRO)

Comment ID:

22787

Other EPA Comment Codes and Descriptions: 2143 1.6.2.1 Comments in favor of injection into

depleted reservoirs 

Comment: An additional point of concern in the rules is the limited view of applicable 

storage sites. While brine aquifers may indeed be good candidates for geologic 

storage, the same is true of oil and gas reservoirs, both productive and nonproductive. The EPA should develop a site rating system that allows for the 

geologic storage of CO2 in stable subsurface formations. This type of rating 

system will ensure that sites which are best suited to handle large CO2 storage 

projects are utilized and any CCS regulatory system will have early successes. 

Of course, the most likely sites to score well in any ranking system would be 

formations containing or having contained hydrocarbon reserves and properly 

permitted Class II wells existing in these formations should be acceptable 

conduits for CCS. 

Response: EPA disagrees that a rating system is appropriate. Instead, the GS rule focuses on

evaluating the suitability of a site based on site-specific geological and operational data. 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 agrees that depleted oil and gas fields are promising formations for GS, provided the Class VI

siting, well construction and operation, monitoring and testing, and post-injection site care and site

closure requirements are met. EPA adds that injection of carbon dioxide for the purposes of

15
enhanced oil recovery is classified as Class II injection, not Class VI, and will require a Class II

permit. Wells for which the primary purpose is long term sequestration are considered Class VI

wells.

EPA adds that the GS rule does not include criteria for rating particular sites for GS. 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 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.

Commenter Name: Daniel Plath Letter ID: 0188

Commenter Organization: NiSource, Inc. Comment ID: 25238

Comment: 5. Data and MMV Requirements (146.82 and 146.90) 

The Proposed Rule has potentially very extensive data and monitoring, measuring 

and verification (MMV) requirements, particularly once this is an established 

and proven technology. The required data to prudently develop a GS site and to 

monitor the gas plume is extremely site specific and industry knowledge base 

dependent. A pilot project will inherently require more frequent and diverse 

data collection and modeling than the nth project in the same formation. The 

Final Rule needs to recognize the clear differences in data requirements for 

first of its kind projects, where the primary driver is risk mitigation due to 

the multitude of unknowns, versus the application of a well developed technology 

for which cost effectiveness is the primary consideration because the experience 

and knowledge exists to effectively identify and manage the risks. NiSource does 

not see any recognition of this significant difference in the Proposed Rule and 

respectfully submit that EPA incorporate language accordingly. 

Response: EPA acknowledges that early pilot projects may focus on gathering data to inform GS

technology. However, EPA believes that a detailed geological site characterization of every GS site

(as 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 adds that, if data on a formation or site collected

in connection with an earlier project can support a geologic characterization, the Director has

discretion to accept this data, provided it is sufficient to demonstrate site suitability.

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.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24329

16
Comment: III. Comments Regarding Proposed Class VI Requirements 

A. Geologic Siting Requirements 

In view of the need to promote appropriate use of GS to reduce CO2 emissions, 

the regulations should be designed to allow GS in any geologic setting in which 

the Director concludes that GS can be conducted without endangering USDWs. It 

follows that the regulations should give the Director discretion to apply the 

"non-endangerment" performance standard on a site-specific basis as particular 

geologic site conditions warrant, without the need to apply prescriptive 

criteria that - while perhaps necessary to endure protection of USDWs in some 

cases - would arbitrarily disqualify some sites that would in fact be 

appropriate for GS. This does not mean that regulation need be lax; it simply 

means that regulation must be flexible, and that rigid criteria should not 

substitute for performance-based standards and site-specific consideration of 

the merits. 

The preamble to the proposed rule outlines normal site selection criteria for 

injection well projects, including the need to identify an injection zone with 

sufficient permeability, porosity, thickness and lateral extent and a lowpermeability confining zone with sufficient thickness and lateral extent to 

protect overlying USDWs. 73 Fed. Reg. at 43505. These are familiar and 

appropriate geologic siting requirements for injection well operations, and the 

regulatory text proposed for codification at 40 C.F.R. 146.83(a) - with 

relatively minor technical changes - would embody them appropriately. 

Unfortunately, the preamble goes on to suggest the need for overly-elaborate 

analysis of extraneous issues, and the rule text proposed for codification at 40 

C.F.R. 146.83(b) would allow the Director apparently unlimited discretion to 

impose siting conditions that go beyond those necessary to ensure protection of 

USDWs. EPA should clarify that site evaluation should go no farther than 

necessary to prevent endangerment, and should eliminate any apparent discretion 

to impose siting requirements that are not necessary to protect USDWs. 

Response: The final rule does not preclude injection into any formations or types of injection sites

provided that the wells meet the final GS rule requirements. The purpose of the GS regulation is to

ensure that injection of CO2 for GS is conducted in a manner that is protective of USDWs. This

includes appropriate site characterization and identification of geologic formations that are amenable

to injection of potentially large volumes of CO2 for long-term storage. The regulation provides

flexibility to owners or operators to select appropriate sites and target formations (under §146.82),

well construction specifics (under §146.86), and injection procedures 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.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24402

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

Comment: Rule Provision: 146.81(d) [Definition - Confining zone] 

Proposed CCS Group Recommendations: Confining zone means a geological formation, 

17
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.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24410

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

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 

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.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24414

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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. 

18
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.

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.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24419

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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

19
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. 

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. 

20
Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24421

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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.

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23888

Comment: o Appropriate site selection supported by rigorous characterization provides the 

strongest foundation for protection of USDWs. It is important that a diversity 

of geologic containment systems be used for sequestration, and that site 

selection requirements do not unnecessarily exclude potential storage sites. 

Response: EPA agrees that site characterization is an important aspect of ensuring USDW

protection, and clarifies that the final rule does not preclude injection into any formations or types of

injection sites provided that the wells meet the final GS rule requirements. The purpose of the GS

regulation is to ensure that injection of CO2 for GS is conducted in a manner that is protective of

USDWs. This includes appropriate site characterization and identification of geologic formations

that are amenable to injection of potentially large volumes of CO2 for long-term storage. The

regulation provides flexibility to owners or operators to select appropriate sites and target formations

(under §146.82), well construction specifics (under §146.86), and injection procedures 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.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24640

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

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.

21
Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24642

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 

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.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24646

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

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

22
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.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24647

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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: 24648

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 

23
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. 

Commenter Name: Brad Castleberry Letter ID: 0203

Commenter Organization: Water Environment Association of Texas (WEAT)Comment ID: 22179

Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front

Monitoring Requirements (40 CFR 146.90) 

Comment: groundwater quality as well as public drinking water sources. Careful 

consideration should he given to ensure an adequate assessment is made of each 

proposed injection well site. This consideration should come in the form of 

detailed site studies. sophisticated computer modeling, and other tools used to 

predict hydrogeology. Careful consideration should also he given to ensure that 

adequate ongoing monitoring and reporting is provided for any site ultimately 

permitted pursuant to the proposed rules. Given the unique circumstances 

surrounding this type of pollutant, and the lack of a significant body of longterm evidence to support the proposed activity, we would encourage EPA to 

include significant monitoring and reporting provisions to ensure the long-term 

viability of any permitted site with respect to surrounding groundwater quality. 

Response: EPA agrees with the commenter regarding the importance of site characterization, and

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

24
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 monitoring plans and methods need to be site-specific and 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 GS rule, at §146.90, requires injectate monitoring, mechanical integrity testing, corrosion

monitoring, tracking the CO2 plume and area of elevated pressure, monitoring geochemical changes

above the confining zone, and, at the discretion of the Director, surface air and soil gas monitoring

for CO2 fluctuations, and any additional tests necessary 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.

Commenter Name: Thomas Curtis Letter ID: 0204

Commenter Organization: American Water Works Association (AWWA) Comment ID: 22182

Comment: - Geosequestration activities should be prohibited in the immediate vicinity of 

sole source aquifers. 

Response: The GS requirements are designed to ensure protection of USDWs from endangerment by

requiring that injection wells are permitted, sited, constructed, operated, monitored, and plugged in a

manner that does not endanger USDWs. 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 clarifies that §146.82(a)(5) requires prospective owners or operators to submit information on

all USDWs (which would include sole source aquifers) within the AoR. The Director would consider

this information and the potential impact of the GS project on any sole source aquifers in

determining whether GS is acceptable. 

Commenter Name: Diane VanDe Hei Letter ID: 0206

Commenter Organization: Association of Metropolitan Water Agencies

(AMWA)

Comment ID:

22208

Comment: - Protection of drinking water sources and potential future underground sources 

of drinking water (USDW) is paramount. As a result AMWA and AWWA recommend that: 

o The final CO2 geologic sequestration regulation should at a minimum, prohibit 

25
the construction of CO2 sequestration wells in any sole source aquifers and 

restrict any project in the vicinity of any sole source aquifer. 

Response: The GS requirements are designed to ensure protection of USDWs from endangerment by

requiring that injection wells are permitted, sited, constructed, operated, monitored, and plugged in a

manner that does not endanger USDWs. 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 clarifies that §146.82(a)(5) requires prospective owners or operators to submit information on

all USDWs (which would include sole source aquifers) within the AoR. The Director would consider

this information and the potential impact of the GS project on any sole source aquifers in

determining whether GS is acceptable.

Commenter Name: Diane VanDe Hei Letter ID: 0206

Commenter Organization: Association of Metropolitan Water Agencies

(AMWA)

Comment ID:

22209

Other EPA Comment Codes and Descriptions: 1310 1.1.2.4 Comments on other "out of scope"

issues, e.g., pore space ownership; 1610 1.3.1 Risks to USDWs 

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). 

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

26
built on a long-standing protective regulatory framework, tailored to the unique characteristics of

CO2 GS.

Commenter Name: John King Letter ID: 0211

Commenter Organization: Shell Exploration and Production Company

(SEPCo)

Comment ID:

22751

Comment: - Site Characterization/Evaluation: EPA should seek to develop clear performance 

standards as detailed in the American Petroleum Institute’s submission regarding 

site characterization. The need for adequate site characterization and 

evaluation cannot be understated, however it is critical that EPA works to 

clarify the site evaluation needs and ensure that they are no more elaborate 

than necessary to ensure protection of USDWs. 

Response: EPA agrees with the commenter on the importance of proper site characterization, and

clarifies that the purpose of the GS regulation is to ensure that injection of CO2 for GS is conducted

in a manner that is protective of USDWs based on an evaluation of site-specific information. This

includes appropriate site characterization and identification of geologic formations that are amenable

to injection of potentially large volumes of CO2 for long-term storage. The regulation provides

flexibility to owners or operators to select appropriate sites and target formations (under §146.82),

well construction specifics (under 146.86), and injection procedures 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 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 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.

Commenter Name: Diane VanDe Hei Letter ID: 0213

Commenter Organization: Association of Metropolitan Water Agencies

(AMWA)

Comment ID:

22919

Comment: AMWA supports strong criteria for site selection, design and operation of carbon 

sequestration sites. EPA’s rule and any financial incentives put forth by other 

Response: EPA agrees with the commenter. The GS requirements are designed to ensure protection

of USDWs from endangerment by requiring that injection wells are permitted, sited, constructed,

operated, monitored, and plugged in a manner that does not endanger USDWs as informed by

extensive, site-specific site characterization data.

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the

University of North Dakota

Comment ID:

21611

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards) 

27
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 

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. 

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the

University of North Dakota

Comment ID:

21633

Comment: Page 43536. § 146.83 Minimum criteria for siting. Requiring the injection zone 

to have the ability to receive the "total anticipated volume of the carbon 

dioxide stream" seems unreasonable. Linking CO2 source potential with CO2 

injection potential is not recommended, and flexibility is required. For 

28
example, if the stream is coming from a power generating facility, it can be 

difficult to estimate the longevity of the plant given changes in technology 

that may allow for increased energy output. Multiple storage sites may be 

required for one source, or conversely, multiple sources may utilize a single 

storage site. 

Response: The Agency disagrees with the commenter that there should not be an absolute

requirement that the injection zone be capable of receiving the total anticipated volume of CO2. The

GS rule is designed to ensure that the total volume of CO2 anticipated to be injected can be safely

stored within the target injection zone. This evaluation is based on site-specific characteristics

including the local geology (e.g., data on formation thickness, porosity, and permeability and the

presence of confining zones). The GS injection requirements, under SDWA authority, ensure

protection of USDWs from endangerment through assessment of the suitability of an injection zone

(§146.83), appropriate site characterization (§146.82), and area of review evaluation (§146.84)

among other requirements. 

The Agency believes that this comment may be based on an assumption that Class VI injection wells

will be co-located with CO2 producing facilities. While this may, in some cases, be an accurate

assumption, the specifications, design, and purpose of the CO2 source/facility are not addressed by

the Class VI GS requirements. 

The productivity of the CO2 source (e.g., power plant, industrial facility, etc.) is not the driver of site

suitability. Rather, the acceptability of a candidate site is determined, in part, by the amount of CO2

it can receive without allowing pressures in the injection formation to build up to levels that may

fracture the confining zone or cause unacceptable fluid movement. If a CO2 source produces more

than a formation can hold, then once the capacity of the receiving formation is reached, any

additional CO2 produced would have to be injected elsewhere. 

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21671

Comment: (B) WELLS, MONITORING & OPERATIONS 

In general, regulations for geologic sequestration should provide for effective 

storage management by requiring the following activities: 

- Site characterization that validates the geological model of the storage site 

and confirms potential leakage pathways have been identified and evaluated; 

- Risk assessment that builds upon the predicted behavior and movement of the 

co2 in the reservoir over time and confirms that the potential for leakage has 

been evaluated through site characterization; and 

Response: EPA agrees with the commenter. The requirements for geologic site characterization are

based on a long standing UIC regulatory framework tailored to address specific risks to USDWs

posed by injection. 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.

29
Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21716

Comment: (B) WELLS, MONITORING & OPERATIONS 

In general, regulations for geologic sequestration should provide for effective 

storage management by requiring the following activities: 

- Site characterization that validates the geological model of the storage site 

and confirms potential leakage pathways have been identified and evaluated; 

- Risk assessment that builds upon the predicted behavior and movement of the 

CO2 in the reservoir over time and confirms that the potential for leakage has 

been evaluated through site characterization; and 

Response: EPA agrees with the commenter. The requirements for geologic site characterization are

based on a long standing UIC regulatory framework tailored to address specific risks to USDWs

posed by injection. 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.

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24018

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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.

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21783

Comment: -The potential requirement for "buffer zones" in addition to a confining zone 

(§146.83(b)). 

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

30
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.

Commenter Name: Pamela A. Lacey Letter ID: 0228

Commenter Organization: American Gas Association Comment ID: 21803

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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.

Commenter Name: A. James Mayer Letter ID: 0230

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

Energy Security Initiative

Comment ID:

21887

Other EPA Comment Codes and Descriptions: 2100 1.6 Target Geologic Formations for GS 

Comment: 4. EPA should provide flexibility in the siting requirements including promoting 

utilization of EOR, Enhanced Gas Recovery (EGR) and Enhanced Coalbed Methane 

Recovery (ECBM) formations for storage. 

Response: 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

31
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 site-suitability for GS is dependent on a number of factors and that many

formation types may be suitable for GS. EPA agrees that GS into unmineable coal seams has the

potential to allow sequestration while ensuring USDW protection from endangerment, as described

by commenters citing the process of enhanced methane recovery. The final GS rule does not

preclude injection into unmineable coal seams provided owners or operators can demonstrate that GS

can be performed in a manner that protects USDWs from endangerment. The Agency clarifies that

owners or operators of Class VI wells used for injecting CO2 into unmineable coal seams are subject

to the same site characterization, well construction, operation, monitoring, post-injection site care

and site closure requirements that are required of projects injecting into other formation types.

Commenter Name: Abbie Krebsbach Letter ID: 0235

Commenter Organization: Montana-Dakota Utilities Co. Comment ID: 23181

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards) 

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: Philip Papadeas Letter ID: 0238

Commenter Organization: Sandia Technologies, LLC Comment ID: 23348

Comment: Geologic Characterization 

32
EPA should allow an applicant to drill a site stratigraphic test well, 

convertible later to a Class VI injection well. All information should be 

provided, and utilized for modeling the reservoir, with conservative model 

inputs and predictions for determining future operations. 

Response: EPA 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, e.g. for laboratory

determination of capillary pressure, and take other necessary measurements. 

EPA believes that the 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.

Commenter Name: Philip Papadeas Letter ID: 0238

Commenter Organization: Sandia Technologies, LLC Comment ID: 23350

Comment: §146.82 (d) (2) 

Re: Faults transmissive or sealing? 

Whether faults are transmissive or sealing in the injection interval, or zone is 

immaterial, if the reservoir and injection interval can pass modeling scenarios 

using conservative assumptions successfully preventing fluid migration to the 

USDW, then these operational considerations should be used as the key threshold 

and benchmark for EPA’s geological evaluation. Class I operators are required to 

model both scenarios if data is not known or exists and this similar approach 

should be followed. 

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 clarifies that geological data collected

during site characterization, including information on faults, will be used as inputs for AoR

modeling. Modeling results, in concert with other site characterization information, will be used to

determine if a site is appropriate for GS and will ensure protection of USDWs from endangerment.

Commenter Name: Philip Papadeas Letter ID: 0238

Commenter Organization: Sandia Technologies, LLC Comment ID: 23351

Other EPA Comment Codes and Descriptions: 3860 2.3.3 Well component degradation 

Comment: §146.82 (h) (i, j) 

Re: Compatibility testing should be performed from cores and either native or 

synthesized formation fluid and injectate to determine and demonstrate potential 

reactivity of the injectate with formations, tubular materials, and other waste 

or injectate mixtures. This is presently performed for all Class I hazardous 

wastes, and should be employed as a one-time initial testing program for new 

well operations and injection constituents, composition and properties. 

Response: EPA has revised subpart §146.82 so that the final regulation specifies separate

requirements for information to be submitted with the permit application and before well

33
construction is approved (at §146.82(a)) and information to be submitted before operation of the

well is authorized (at §146.82(c)).

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission

Associates

Comment ID:

22245

Comment: – WEST urges EPA to take appropriate care in characterizing the risks of CO2 

geologic storage under the UIC program. As we commented above, a successful 

national CO2 emissions abatement program will necessarily need to rely heavily 

upon development of and public support for CCS. By overly burdening the detail 

of site characterization and UIC of CO2 risks related to given sites under 

consideration, EPA could inadvertently and inappropriately stigmatize CCS, 

particularly if it heads off into an unwarranted categorization of CO2 as a 

pollutant or a hazardous waste. Such excessive focus on risk or inappropriate 

characterization would imply liability risk that would chill further development 

of critically needed CCS under a climate change program. WEST Associates 

believes EPA can develop site characterization regulations that minimize 

potential burdensome regulations based on known potential site characteristics 

as discussed in these comments immediately below. 

Response: 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. 

EPA recognizes 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, EPA believes that

owners or operators of GS wells must characterize their CO2 stream as part of their permit

application, as required at §146.82(a)(7). 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. 

Since the GS rule, at §146.81(d), excludes CO2 streams that meet the definition of a hazardous waste

under 40 CFR part 261, if the injectate is determined to meet the definition of a hazardous waste

under RCRA, injection may only occur in a Class I hazardous waste injection well.

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission

Associates

Comment ID:

22246

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards) 

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 

34
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 sitespecific 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.

Commenter Name: James T. Sims Letter ID: 0249

Commenter Organization: Western Business Roundtable Comment ID: 22263

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards) 

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" 

35
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 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.

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22326

Other EPA Comment Codes and Descriptions: 1620 1.3.2 Induced seismicity 

Comment: Seismicity 

Naturally occurring seismicity has been cited as an area of concern for geologic 

sequestration of CO2. We do believe that seismicity merits diligent treatment 

both in the regulations and in project operation, but we see no need for a 

blanket ban of sequestration in seismically active areas. Although some sites - 

especially ones near major active faults - would not be advisable for injection, 

there are plenty of other sites in seismically active areas that would make 

excellent candidates for safe and effective sequestration. Moreover, tools to 

measure, predict and design against the effects of seismic activity are 

available. 

36
Nature has proven its ability to retain fluids trapped in the subsurface in 

seismically active areas in many instances over hundreds of millions of years, 

even in highly tectonically active regions of the country such as California. 

The potential for slippage for faults to create leakage pathways to USDWs or the 

surface can be managed and effectively minimized through careful siting and 

operational design using well-established tools and methods. The regulations 

should ensure that suitable sites are selected, while high risk areas, such as 

those near major, non-sealing faults or those that demonstrate frequent 

activity, are rejected. The most likely potential CO2 leakage paths would be 

injection wells, and not faults. However, these can be designed to prevent 

leakage and to be resilient to earthquakes. 

We regard a ban on sequestration in seismically active areas unwarranted. We do 

however believe that additional diligence is required in site characterization 

and selection in such areas. The requirement in §146.82(c)(3) should be modified 

as follows: 

Response: EPA agrees that GS should not be banned in any type of environment or geologic setting

and believes that decisions about seismic risk should be made on a site-specific basis. The Class VI

requirements to properly characterize, permit, operate, and monitor a GS project are designed to

ensure that, where GS is employed, it is done in a manner that protects USDWs from endangerment.

These requirements include site characterization during which owners or operators must submit

information about the seismic history of and seismic sources near a proposed GS site, as well as 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 in conjunction with information about well

construction, operation, monitoring, post-injection site care, and other site-specific information. The

Director determines suitability of a potential project site for GS. Sites with the potential for

reopening or reactivation of faults or unacceptable seismic risk that could otherwise interfere with

containment would not be suitable for GS sites –as owners or operators seeking to inject CO2 for GS

at such sites would not be able to demonstrate USDW protection from endangerment. 

EPA acknowledges that wells in the AoR are potential leakage pathways, and the GS rule contains

rigorous provisions for both injection well construction at §146.86 and corrective action on active or

abandoned wells located in the AoR at §146.84.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24857

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

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 

37
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.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24859

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

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: 24867

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

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.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24870

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 

38
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.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24873

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24874

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(e) 

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 

39
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.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24875

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 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.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24876

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

40
language; 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.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24878

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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

41
proposed.

Commenter Name: Lori Mathieu Letter ID: 0283

Commenter Organization: Connecticut Department of Health Comment ID: 25297

Comment: 2: The proposed rules should be limited in the scope of its geographic coverage 

to areas that provide the greatest potential for sequestration of Carbon Dioxide, 

in terms of both the amount of sequestered and storage suitability. 

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 longterm storage. However, regardless of the history of the site, the owner or operator must provide to

the Director extensive information demonstrating the adequacy of the site to contain the CO2

(§146.82) and ensure protection of USDWs from endangerment.

Commenter Name: Anonymous7 Letter ID: 0288

Comment ID: 25136

Comment: COMMENT ON CARBON SEQUESTRATION 

Geology, like hydrology is a science of averaged parameter values. When

determining lithologic properties (e.g.. transmissivity, thickness, threedimensional position, etc.) of a geologic stratum, scientists estimate these

properties based on collection of data at a small number points selected from an

infinite number of possible points. The more deeply buried the stratum, the

greater the cost of data collection and, so, the number of data points tends to

diminish with depth. There is no way to know how representative the collected

data are of a geologic stratum.

As an example, imagine driving down a road at 60 mph and hitting a hole in the

highway. In 20 million years from now, that highway likely will be buried under

hundreds of feet of sediment. If a dozen test holes are drilled from the land

surface, though the highway roadbed, the chance that that hole would be

intersected is minuscule, yet that hole in the roadbed may be the most important

feature of the highway.

Not all data are collected from drilling cores, there also are temperature data,

geophysical data, etc. An uncertainty analysis is performed to provide a sense

of how reliable the modeling results are, but the bottom line" is that the "weak

links" in the protectiveness of a confining unit are still likely to be unknown.

While this lack of knowledge is not a lethal blow to modeling for, say, watersupply, these weak links can lead to serious consequences where the purpose is

modeling the injection of supercritical CO2 fluids.

When we think of very deep strata that are, say, thousands of feet below land

surface, we take some "comfort" in their depth. We take this comfort, because

42
it's difficult to imagine that, absent a deep mappable fault, a fluid rupturing a

very deep confining layer is likely to reach the land surface. However, where

injection strata and confining units are shallower, our level of comfort

decreases, and rightly so. It is because of the lack of sufficient data to

accurately define the nature of the subsurface, that EPA needs to take a

protective approach to options for: 1) injecting into formations in or above the

lowermost USDW, 2) injecting below the lowermost USDW when that USDW is

"relatively" shallow, and 3) injecting into a formation overlain by a brittle

confining layer, unless that confining layer is very deep.

Response: EPA agrees that permitting decisions regarding GS sites must account for a large amount

of site-specific information. For this reason, the GS regulation requires the owner or operator to

submit data about the site, including information on the porosity, permeability, mineralogy, and

geochemistry of the targeted injection and confining zones. Operators must also present information

on the compatibility of the CO2 stream with fluids in the injection zone and minerals in both the

injection and the confining zone(s), as determined through the formation testing program and on the

compatibility of the CO2 with the materials used to construct the well, as required at §146.82(c)(3).

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25312

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

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.

Commenter Name: Scott Anderson Letter ID: 0510

Commenter Organization: Environmental Defense Fund Comment ID: 21219

Comment: I want to especially note some strengths of the rule that relate to brine 

displacement. Protecting USDWs from displaced formation fluids, is just as 

important as protecting USDWs from injected CO2. And EPA clearly realizes this, 

and we're pleased. 

43
I want to read these sections into the record or not, make a, maybe if I can do 

it quickly enough. We are pleased with Section 146.83, requires a confining 

zone that confines both CO2 and displaced formation fluids. 

Response: EPA acknowledges the comment. EPA's goal is developing standards for GS wells in

order to ensure the protection of USDWs from endangerment. The final rule requires that any GS

project must have at least one confining zone (i.e., impermeable layer) between the injection zone

and the lowermost USDW (§146.83(a)).

Commenter Name: Scott Anderson Letter ID: 0510

Commenter Organization: Environmental Defense Fund Comment ID: 21227

Comment: We believe that, that there should be a provision that prohibits interference 

among projects. Eventually, if sequestration becomes a big enough industry we 

would foresee a need for basic scale of regional management. 

Between now and then we think it's important to nip problems in the bud, and we 

suggest that a new project not be allowed to interfere with an existing project 

in terms of the pressure fronts overlapping or other types of interference 

unless a finding is made that such a overlap doesn't degrade the effectiveness 

of either project. So then a rule like that would force people to space 

projects in a way that is proper. 

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.

Commenter Name: Olon Plunk Letter ID: 0536

Commenter Organization: Xcel Energy Comment ID: 21377

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for

permit applications (seeking comment) 

Comment: In the meantime, I would like to offer some general observations. Having been 

through this effort to locate and prove up the acceptability of a CO2 

sequestration site for a large commercial scale project, Excel believes the 

topics EPA would require permit applicant to address in its proposed rules are 

appropriate and important. For example, we believe the best technical expertise 

should be brought to bear in the first studying and then submitting 

documentation concerning site and formation geology, hydro-geology, faults, 

fractures, injectivity, existing wells and so on. 

Response: EPA acknowledges the comment and agrees on the importance of the required permit

information set in §146.82. EPA believes that the extensive requirements for geologic site

44
characterization at §146.82 are appropriate to ensure that permitting authorities have the necessary

information to evaluate whether a specific site will allow safe injection of CO2.

Commenter Name: Olon Plunk Letter ID: 0536

Commenter Organization: Xcel Energy Comment ID: 21378

Other EPA Comment Codes and Descriptions: 3800 2.3 Proposed Injection Well Construction

Requirements (40 CFR 146.86); 4000 2.4 Proposed Injection Well Operating Requirements (40 CFR

146.88); 5000 2.8 Proposed Well Plugging and Post-Injection Site Care Requirements 

Comment: We believe there must be suitable CO2 injection plans backed by seismic surveys, 

multi dimensional modeling simulations and formation testing. 

We recognize the overriding importance of well design and construction that 

assures well integrity. We believe there must be a sound operations management 

program including appropriate monitoring and corrective actions that are 

prepared and implemented by experts in the field. 

We recognize both the local and national interest in providing effective post 

injection site care and closure and demonstrating adequate financial 

responsibility for these activities. While agreeing with supporting all of these 

important program elements, I would like to add a few words of caution. 

Response: EPA acknowledges the comment. The GS requirements are designed to ensure protection

of USDWs from endangerment by requiring that injection wells are permitted, sited, constructed,

operated, monitored, and plugged in a manner that does not endanger USDWs. 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. 

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 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

evaluating this information. The guidance can be found on EPA’s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

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 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

evaluating this information. The guidance can be found on EPA’s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Comment Code: 3110 2.1.1 Proposed siting requirements (i.e., injection/confining zones, trapping

mechanism) 

45
Individual Comments

Commenter Name: Michael H. Cochran Letter ID:

0108

Commenter Organization: Bureau of Water, Division of Environment, Kansas

Department of Health & Environment (KDHE)

Comment

ID: 21964

Comment: 146.83 (a): Need to include without initiating or propagating fractures in the 

injection in addition to the confining zone. 

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 stimulation program) to improve wellbore and formation injectivity.

EPA clarifies that all stimulation for GS must be reported to the Director for approval 30 days in

advance of such activities, pursuant to requirements at §146.91(d)(2).

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24768

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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.

Commenter Name: John Hanger Letter ID: 0130

Commenter Organization: Pennsylvania Dept. of Env. Protection Comment ID: 21502

Comment: Proposed Geologic Siting Requirements 

-The proposed regulations should better express the need for characterizing the 

number, location, and depth of "underground sources of drinking water." 

Specifically, Pennsylvania recommends the addition of a subsection under 

"Geologic Siting Requirements" that calls for a hydrogeologic characterization 

of USDWs in the area of review. Although a number of technical requirements for 

such a characterization are presented in the Technical Support Document, 

46
"Geologic CO2 Sequestration Technology and Cost Analysis," such visibility is 

not present in the proposed rule itself. The depth and capacity of the regional 

groundwater system should be established in this characterization, along with 

other required details described in the Technical Support Documents. 

Groundwater flow directions and approximate water budgets to estimate deep 

components of flow will help to assess any injection well impacts to USDWs. 

Fracturing and faulting in context with the regional groundwater system should 

be a part of the hydrogeologic characterization. This would include an 

uncertainty analysis of current knowledge for the area. 

Also, consideration should be given for a recommendation of scales for maps and 

cross sections. Scales should be sufficient to provide enough detail for the 

"detailed geologic assessment." 

-The definition and criteria to ‘show or demonstrate secondary containment of 

the reservoir’ does not make sense for PA geology. EPA should allow for 

demonstration approaches that are flexible to regional geology. 

Response: 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 evaluating this information. The guidance can be found on EPA’s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Richard Driggans Letter ID: 0145

Commenter Organization: Tennessee Valley Authority Comment ID: 23150

Comment: discretion to require cap rock redundancy. As a further precaution, potential 

GS sites near sole-source aquifers, as well as those sites in high risk seismic 

locations, should initially be eliminated from consideration until sufficient 

experience with operational scale GS is gained. 

As a related matter, at least for the near future, siting a fossil-fueled plant 

that utilizes GS near a sole-source aquifer should only be considered where the 

infrastructure is in place for transporting supercritical CO2 to a distant 

injection well location. Because a large portion of the Nation’s fleet of 

fossil-fueled generating facilities were sited and built without consideration 

of CCS, there are considerable space, water supply, geologic, seismic, and 

financial constraints for retrofitting many existing facilities with this 

technology. Although the proposed rule does not require facilities to capture 

and/or sequester CO2, promulgation of this rule should acknowledge that GS of 

CO2 will not be suitable at a large number of existing facilities and may be 

most applicable for new-generation facilities that are properly sited a priori 

for CCS. 

Response: The GS requirements are designed to ensure protection of USDWs from endangerment by

requiring that injection wells are permitted, sited, constructed, operated, monitored, and plugged in a

manner that does not endanger USDWs. GS in areas that may pose risks to USDWs, as assessed and

47
identified by the owner or operator and the Director during the site selection process, would not be

permitted.

In response to the comment that GS should not be allowed in areas with high-risk for a seismic

event, EPA clarifies that the GS rule does not allow GS to be performed in seismically active areas

and requires that operators must submit information about the seismic history of and seismic sources

near a proposed GS site (146.82(a)(3)(v)). This information, along with other required submissions,

will be evaluated by the Director, who will determine the suitability of a potential project site for GS.

EPA clarifies that 146.82(a)(5) requires prospective owners or operators to submit information on all

USDWs (which would include sole source aquifers) within the AoR. The Director would consider

this information and the potential impact of the GS project on any sole source aquifers in

determining whether GS is acceptable. 

Commenter Name: Kenneth Alexander Letter ID: 0146

Commenter Organization: Old Dominion Electric Cooperative (ODEC) Comment ID: 21710

Other EPA Comment Codes and Descriptions: 2100 1.6 Target Geologic Formations for GS 

Comment: 3.EPA should not automatically exclude placement of wells in pmiicular geologic 

tructures. The Final Rule should leave the door open for a range of injection 

sites and methods provided the owner or operator can show that the injection and 

storage will be protective of Underground Sources of Drinking Water (USDWs). 

Response: The final rule does not preclude injection into any formations or types of injection sites

provided that the wells meet the final GS rule requirements. The purpose of the GS regulation is to

ensure that injection of CO2 for GS is conducted in a manner that is protective of USDWs. This

includes appropriate site characterization and identification of geologic formations that are amenable

to injection of potentially large volumes of CO2 for long-term storage. The regulation provides

flexibility to owners or operators to select appropriate sites and target formations (under §146.82),

well construction specifics (under §146.86), and injection procedures 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 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.

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22630

Comment: Demonstrating Sufficient CO2 Storage Capacity 

Page 43536. The draft Class VI rule states that the applicant is required to 

identify "An injection zone of sufficient areal extent, thickness, porosity, and 

48
permeability to receive the total anticipated volume of the carbon dioxide 

stream." This is a good requirement but it is incomplete. There needs to be 

some time element here. That is the proposed rule needs to address "total 

anticipated volume" over what period of time. There is no need to establish an 

arbitrary quantitative figure here (e.g., "over 40 years"). Rather the 

calculation could be predicated on the expected lifetime of the facility, the 

duration of the injection permit, etc. It would be prudent to modify this 

sentence to explicitly communicate that the USEPA was not considering "the total 

anticipated volume of the carbon dioxide stream" for any given year of 

operations. 

Response: The Agency agrees with the commenter, in the final regulation, the owner or operator

must demonstrate that the receiving formation (injection zone) is "sufficient... to receive the total

anticipated volume of the CO2 stream" (§146.83 (a)(2)). In addition, the Director will also consider

the owner or operator's proposed AoR and corrective action plan, in which the owner or operator

must delineate, through modeling, the predicted extent of the CO2 plume over the duration of the

project.

Commenter Name: Michael J. Miller Letter ID: 0168

Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22495

Comment: EPRI COMMENT #4B: The minimum siting criterion specified in §146.83(a)(2) that 

states the confining zone must be "free of transmissive faults or fractures" is 

too vague and open to interpretation by permit writers, potentially leading to 

inconsistent application throughout the United States. Faults and fractures are 

ubiquitous and quite common in deep sedimentary basins where the natural 

accumulation of thick sediments causes differential compaction and settling, 

resulting in fracturing and faulting. However, some faults and fractures are 

sealed or have very low transmissivity, allowing them to be present in the 

caprock without jeopardizing containment. Therefore, if taken literally, the 

language in the proposed rule could limit permitting to those sites that are 

totally "free" of faults and fractures, potentially eliminating numerous 

sedimentary basins with excellent CO2 storage potential. EPRI recommends that 

the EPA remove the language "free of transmissive faults or fractures" from this 

section of the rule and, instead, base its decision on a site-by-site 

demonstration of capacity and containment using data and model results provided 

by the applicant. 

Response: EPA disagrees that the language is vague. 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. 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 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.

49
Commenter Name: Michael J. Miller Letter ID: 0168

Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22497

Comment: EPRI COMMENT #4D: If EPA retains the language in the rule requiring that 

confining zones be free of transmissive faults and fractures, EPRI wants to 

point out that reliable techniques for characterizing deep faults/fractures are 

rudimentary. Drilling through the fault or fracture plane and hydraulically 

testing it to determine its local transmissivity is the most direct and reliable 

characterization method. EPRI is concerned about any requirement to characterize 

the hydraulic properties of faults cutting across confining zones because this 

can only be achieved by drilling through and hydraulically testing the fault, 

creating potential fast-flow pathways in the caprock, potentially jeopardizing 

containment. 

Response: 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. At sites where deep faults (even with little or no surface expression)

are present, processing and interpreting data from multiple geophysical sensing methods has been

shown to detect faults better than analysis of data from individual methods (Goussev et al, 2004).

Drilling through faults or fractures with appropriate well design, materials, and operation, would not

result in an increase in their permeability or a decrease in CO2 containment properties of the related

CO2 storage reservoir. In some cases, the use of complementary drilling and geophysical methods

might provide the most dependable characterization of potential transmissive faults and 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.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24156

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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

50
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.

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23851

Comment: 2. Geologic Siting Requirements 

EPA's Proposed Rule includes significant technical information requirements for 

the geological siting of Class VI wells, including: maps and cross-sections of 

nearby USDWs; demonstrations of the porosity and permeability of the injection 

zone and subsurface formations; information on faults and fractures, including 

results of geomechanical studies; seismic history studies; determinations of 

maximum sustainable injection pressures; and geochemical data. 

The geological siting requirements for Class VI wells should be reasonably 

balanced to ensure that EPA's goals are met. but not be so burdensome so as to 

deter the development of CCS projects. To this end, EPA should ensure that the 

information it seeks is essential to its evaluation efforts, and not 

unnecessarily overbroad. Proper geological siting requirements will help EPA, 

state actors, and owners and operators identify the risks involved so that 

proper additional evaluations may be made to protect human health and the 

snvironment and to evaluate financial and strategic risks associated with CCS 

projects. 

Moreover, the siting requirements authorize the Director to use his discretion 

to require owners and operators to identify and provide additional information 

with respect to additional zones near the GS. Such discretion should not be 

unlimited. We recommend that EPA establish clearer guidelines with respect to 

how such discretion may be exercised to prevent unnecessary requirements. 

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 disagrees the requirements are too burdensome, and 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. 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 evaluating this information and

exercising discretion. The guidance can be found on EPA’s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Robert J. Finley Letter ID: 0180

51
Commenter Organization: Illinois State Geological Survey Comment ID: 23624

Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements

(40 CFR 146.83) 

Comment: 146.83 

(a)(2) 

Modify this section to indicate that the confining zone is "reasonably expected" 

to be free of faults and fractures that are transmissive. Again, the behavior of 

a given fault or fracture in an area cannot be conclusively proven with respect 

to its impact on fluid flow except by analogy to oil field or gas storage field 

performance. There is no mechanism to carry out a subsurface test of a fault 

except possibly in the case of multiple wells opportunely place on opposite 

sides of a defined fault to access a transmissive unit which can be pressure 

pulse tested and can be isolated by packers or other equipment. Such tests 

(obviously) are unlikely to work in a confining zone due to its low 

permeability. 

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. 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. At sites

where deep faults (even with little or no surface expression) are present, processing and interpreting

data from multiple geophysical sensing methods has been shown to detect faults better than analysis

of data from individual methods (Goussev et al, 2004). Drilling through faults or fractures with

appropriate well design, materials, and operation, would not result in an increase in their

permeability or a decrease in CO2 containment properties of the related CO2 storage reservoir. In

some cases, the use of complementary drilling and geophysical methods might provide the most

dependable characterization of potential transmissive faults and 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. 

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. 

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24330

Other EPA Comment Codes and Descriptions: 3140 2.1.4 Comments that the proposed geologic

52
data requirements are too stringent 

Comment: 1. Site Evaluation 

The preamble appears to suggest the need for an elaborate evaluation of site 

conditions to address concerns related to seismicity and potential geochemical 

interactions. In fact, however, seismicity and geochemical impacts are issues 

that are easily addressed in the GS context, and requirements for unnecessarily 

elaborate analysis would serve only to burden and impede the development of GS 

projects. 

Concerns with respect to seismicity are frequently raised in the injection well 

context, but there is ample experience demonstrating that such risks are modest 

and easily addressed through appropriate injection pressure limitations. 

Similarly, geologic compatibility - while it can present issues in some contexts 

- is unlikely to present any serious problems in the GS context. These 

conclusions are confirmed by decades of experience with literally thousands 

Class II CO2 injection wells injecting hundreds of millions of tons of CO2. 

The apparent extent of concern about geochemical compatibility is particularly 

hard to understand. Although it is true that injection of CO2 can be expected to 

lead to the formation of carbonic acid, the resulting carbonic acid is only 

weakly corrosive and - as experience with the injection of extremely corrosive 

hazardous wastes demonstrates - cannot reasonably be expected to cause any 

breach of containment that would endanger a USDW. The proposed rule expresses 

specific concern about geochemical reactions that could alter the composition of 

the injected CO2 stream - particularly through the mobilization of contaminants 

that occur naturally in the injection zone - but such concerns are essentially 

immaterial because the specific composition of the CO2 stream matters little as 

long as the CO2 stream remains confined. 

Response: The Agency believes that the site characterization requirements at §146.82 are essential

to proper siting of a GS well and are the foundation for a detailed understanding of the local and

regional geology. Collecting and evaluating geochemical data in and around the CO2 injection zone,

as required in §146.82(a)(6), serves several purposes. This baseline geochemical data can help

predict geochemical reactions between the injectate, reservoir geology, and formation fluids. Such

reactions can lead to dissolution and precipitation of minerals which affect formation porosity,

which in turn can affect required injection pressure (Sminchak and Gupta, 2002) and transport of

fluid within the formation. While the confining layer is the primary barrier to CO2 movement into a

USDW, multiple barriers are important and changes in injection pressure and fluid movement may

compromise those barriers. An increase in injection pressure due to reduced porosity, in particular,

can lead to fracturing of the confining layer and potentially allow fluid movement outside of the

injection zone. Losses in injectivity because of geochemical reactions may also require additional

injection wells and further penetrations in the confining layer that can become pathways for fluid

migration. 

EPA disagrees with the comment that the composition of the CO2 stream is not important.

Information about the composition of the CO2 stream informs decisions about the appropriate design

and construction of the well, the potential for adverse mineral reactions in the subsurface geologic

formations, and appropriate testing and monitoring parameters. 

53
EPA disagrees that injectivity is not an important consideration. While increasing storage capacity is

not the intent of the UIC requirements, EPA believes that maximizing the amount of CO2 that can

be injected through a single well may reduce the need for additional injection wells, which reduce

the potential for unacceptable fluid movement and improve USDW protection from endangerment. 

Finally, 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. 

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24422

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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.

Commenter Name: Andy Horn Letter ID: 0196

Commenter Organization: Colorado Ground Water Association (CGWA) Comment ID: 23925

Comment: Issue 5. The regulations should specifically address the potential for migration 

of injected CO2 in different types of groundwater reservoirs. 

54
The proposed rule lacks specificity with respect to the manner in which a 

proposed operation will demonstrate that there is a suitable geologic trap for 

the injected CO2 and that the integrity of that trap will be perpetual. 

Demonstrating a pre-existing geologic structure capable of trapping CO2 and 

demonstrating that the complex geochemical reactions in and adjacent to the GS 

reservoir will not compromise the reservoir’s integrity are critical. However, 

the rule simply presumes such a demonstration can be made and provides no 

methods or criteria to be met in developing the demonstration. 

Supercritical CO2 is essentially a light non-aqueous phase liquid (LNAPL) 

capable of dissolving into water and also into which water can dissolve. A 

porous medium, such as the strata comprising a GS reservoir, is about eight 

times as permeable to supercritical CO2 as to water due to the low viscosity of 

the supercritical CO2. The supercritical CO2 will rise through a water-bearing 

reservoir as a buoyant fluid, independent of injection pressure gradients. When 

the supercritical CO2 reaches an impermeable stratum, that buoyancy will cause 

it to continue to move updip along that stratum until it encounters a 

stratigraphic or structural trap or permeability change sufficient to preclude 

further migration, i.e., a trap. The CO2 will continue to migrate into that 

trap, displacing the native water. If the injected volume is greater than the 

trap’s available volume the excess CO2 will "spill" from the trap and continue 

to migrate laterally and vertically along the upper confining stratum until it 

either finds another trapping configuration or reaches temperature and pressure 

where it reverts from supercritical to gaseous CO2. 

Finding trapping structures in the subsurface is a non-trivial exercise. Every 

dry oil or gas exploration hole was drilled because a geologic investigation 

appeared to establish presence of a trap for buoyant hydrocarbons. While some 

dry holes may result from a missing source of petroleum, overwhelmingly the 

cause is that the postulated trap did not exist, either because the trapping 

structure was absent or due to natural leaks through the confining units through 

which the oil or gas escaped. These technical problems associated with finding 

petroleum LNAPL traps are directly analogous to finding traps capable of holding 

CO2 in perpetuity. There are, however, major issues for CO2 sequestration not 

borne by hydrocarbon exploration. 

One issue is geologic trap integrity. Drilling can verify the postulated 

trapping geometry for either activity. If the confirmed configuration does not 

contain petroleum, the configuration is likely to be leaky. There is no 

corresponding way to establish the integrity of the seals in the case of 

exploration for CO2 traps. 

Another issue relating to GS reservoir siting evaluation is economics inherent 

in the process. There is significant financial incentive to find the petroleumbearing trap, and that incentive can bear the burden of multiple failures. For 

the operator of a large point-source of CO2, sequestration of CO2 is a cost to 

be minimized as it does not result in a profit opportunity. Without detailed, 

explicit rules establishing how to prove a trap before attempting GS, the 

existence of functional traps will be simply presumed until lack of their 

55
existence or integrity is proven by failure. 

The problem of finding and proving a sequestration trap for CO2 can be minimized 

by requiring sequestration in depleted petroleum traps, however there may not be 

enough depleted oilfields to contain a significant amount of CO2 and the 

presence of unsuitably constructed or abandoned wells can compromise integrity 

of a GS reservoir. 

Response: EPA developed the GS regulations to address the potential for migration of injected CO2

into different types of groundwater reservoirs to prevent endangerment of USDWs. The rule requires

the owner or operator to provide extensive information to demonstrate to the Director (§146.82) that

the CO2 will be contained within the injection formation. Because of the site-specific nature of GS

and the variety of geologic settings in which GS may be employed, the regulation does not provide a

specific list of information to be provided. 

Owners or operators seeking a permit for GS wells must provide the appropriate information,

regardless of whether there is a cost incentive for proper site characterization. If the information

submitted is not adequate to support a determination that sufficient traps exist to contain the CO2

and ensure USDW protection, the Director may request additional information (under

§146.82(a)(21)), or ultimately decline to issue 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. The guidance can be found on EPA’s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24652

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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

56
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.

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23957

Comment: Point #2: The absence of a systemfor qualifying geologic storage sites. Fundamentally, 

the TxCCSA believes that hydrocarbon related geologic storage is one of the 

important avenues by which the next generation of energy production will move 

forward. CO2 occurs naturally in the subsurface and is no stranger to geologists 

who attempt to understand fluid migration and subsurface accumulations. The fact 

that CO2 can be trapped in subsurface formations for geologic times is known and 

accepted; and more of these locations will undoubtedly be found. This brings us 

to another concern with the Proposed Rule involving the absence of a system to 

qualify sites for CO2 injection (i.e. a site permitting framework). We feel this 

it is necessary to rate sites for injection security. There is an evolving [FN3] 

framework which could form the basis for qualifying or rating sites. We 

believe that such a framework is necessary for the insurance industry that will 

oversee injection in non-hydrocarbon related geologic storage applications. 

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. 

Response: EPA disagrees that a single process or framework for evaluating all 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. EPA believes that requiring appropriate, sitespecific, 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.

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24025

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

Comment: Proposed Rule: (i) Be based on detailed geologic data collected to characterize 

57
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)).

Commenter Name: A. James Mayer Letter ID: 0230

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

Energy Security Initiative

Comment ID:

21890

Comment: 7. EPA should provide for a system for qualifying sequestration sites, including 

qualifying geographically and geologically diverse sites for CO2 injection in 

non-trapping (oil/gas) applications. 

Response: EPA disagrees that a system for qualifying GS sites is appropriate. Instead, the GS rule

focuses on evaluating the suitability of each site based on site-specific geological and operational

data. 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.

Commenter Name: Randy Joseph Letter ID: 0240

Commenter Organization: Western Organization of Resource Councils Comment ID: 23220

Comment: 2) Siting: Geologic sequestration will require a lot of wells, roads, support 

facilities and other development. We expect that there will be many proposals 

for geologic sequestration in areas that are already subject to heavy energy 

development. It may seem appropriate to concentrate development in areas, but we 

submit that the opposite may be true. Areas already impacted by oil, gas and 

coal development will have underground fractures and fissures that could make 

safe implementation of geologic sequestration a challenge. 

58
Response: EPA clarifies that it is not the intent of the GS rule to identify or set requirements for

which areas may be or should be used for GS. Rather, the purpose of the rule is to ensure that where

deployed, GS is conducted in a manner that protects USDWs from endangerment.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23279

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions 

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 longterm 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.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23283

Comment: 146.83(a)1 An injection zone capable of receiving the total anticipated volume 

of carbon dioxide should not be an absolute requirement. The volume to be 

injected may be difficult to ascertain since the life of a power plant or other 

source may change with advances in technology or under certain economic 

conditions. A candidate injection zone should not be excluded if it can only 

serve as a sequestration zone for a portion of a project. 

Response: The Agency disagrees with the commenter for asserting that there should not be an

absolute requirement that the injection zone be capable of receiving the total anticipated volume of

CO2. The GS rule is designed to ensure that the total volume of CO2 anticipated to be injected can

be safely stored within the target injection zone. This evaluation is based on site-specific

characteristics including the local geology (e.g., data on formation thickness, porosity, and

permeability and the presence of confining zones). The GS injection requirements, under SDWA

authority, ensure protection of USDWs from endangerment through assessment of the suitability of

an injection zone (§146.83), appropriate site characterization (§146.82), and area of review

evaluation (§146.84) among other requirements. 

The Agency believes that this comment may be based on an assumption that Class VI injection wells

will be co-located with CO2 producing facilities. While this may, in some cases, be an accurate

assumption, the specifications, design, and purpose of the CO2 source/facility are not addressed by

59
the Class VI GS requirements. 

The productivity of the CO2 source (e.g., power plant, industrial facility, etc.) is not the driver of site

suitability. Rather, the acceptability of a candidate site is determined, in part, by the amount of CO2

it can receive without allowing pressures in the injection formation to build up to levels that may

fracture the confining zone or cause unacceptable fluid movement. If a CO2 source produces more

than a formation can hold, then once the capacity of the receiving formation is reached, any

additional CO2 produced would have to be injected elsewhere. 

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24879

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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 

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.

Commenter Name: Mark Singer Letter ID: 0504

Commenter Organization: Green America Project, LLC Comment ID: 21249

Comment: Geologic sequestration operations must have capstone formations separating the 

injection site not just from the surface but also from soluble rock such as 

limestone. 

Now, there's a couple places in the, in the Federal Register where they, where 

60
they discussed this. But none of them discussed the effect of CO2 on the rock, 

they just talk about, for example, plugging pore spaces. 

Response: 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. The

owner or operator and the permit writer must take into account the possibility of permeable and/or

soluble geology in the subsurface. The requirement focuses on isolation from the USDW in order to

meet the UIC programmatic requirement to protect USDWs from endangerment. 

EPA believes that plugging of pore spaces is one aspect of the interactions between CO2 and the

rock that need to be addressed. Additionally, the GS regulation requires the owner or operator to

submit data about the site, including information on the porosity, permeability, mineralogy, and

geochemistry of the targeted injection and confining zones. Operators must also present information

on the compatibility of the CO2 stream with fluids in the injection zone and minerals in both the

injection and the confining zone(s), as determined through the formation testing program and on the

compatibility of the CO2 with the materials used to construct the well (§146.82(c)(3)). The data 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: Cynthia Lane Letter ID: 0528

Commenter Organization: American Water Works Association (AWWA) Comment ID: 21387

Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit

more (or different) geologic data than proposed 

Comment: provide for a consistent application of the monitoring requirements. Another 

area of concern is often the lack of good records of abandoned wells that tap 

the very same strata used for carbon dioxide sequestration. There is a 

presumption that even states with oil and gas or mining operation have 

excellent, up to date reports and have maps indicating abandoned wells and 

mines. This is not always the case. Many states with extractive industries do 

have maps and surveys, but they are not sufficiently precise for geologic 

sequestration. Studies have shown that injected carbon dioxide will be able to 

find the abandoned wells. These wells allow for the transmission of the carbon 

dioxide out of the confined aquifer into potential USDW's and then eventually to 

the surface. 

Response: EPA acknowledges that areas previously used for drilling for oil, gas, or minerals pose

potential challenges for GS. However, regardless of the history of the site, the owner or operator

must provide to the Director extensive information demonstrating the adequacy of the site to contain

the CO2 (§146.82). This information includes the location of all existing or abandoned wells within

the modeled AoR (§§146.82(a)(2) and 146.84(c)(2)) and the location, orientation, and properties of

all known or existing faults (§146.82(a)(3)(ii)). The Director may require ground or airborne surveys

to identify active or abandoned wells if there is reason to believe, based on knowledge of the site or

of available data bases, that the available information is not adequate for assessing a proposed GS

site (§146.84(c)(2)). The Director may also require additional surveys and tests to identify and

characterize fractures. After reviewing the permit information submitted, the Director may deny the

application if there is reason to believe that USDWs may be endangered.

61
Comment Code: 3120 2.1.2 Need to identify additional confining and containment zones (seeking

comment) 

Individual Comments

Commenter Name: Michael H. Cochran Letter ID:

0108

Commenter Organization: Bureau of Water, Division of Environment, Kansas

Department of Health & Environment (KDHE)

Comment

ID: 21969

Comment: 146.83 (b): This should not be an option, but should be required of the 

owner/operator. This is important in evaluating and demonstrating containment. 

Response: EPA agrees with commenters 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. 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.

Commenter Name: Karl R. Moor Letter ID: 0109

Commenter Organization: Southern Company, on behalf of Edison Electric

Institute (EEI)

Comment ID:

21995

Comment: For example, requiring a secondary containment field would create the wrong 

impression about the safety of carbon capture and storage, and should not be 

part of the final rule. Such a requirement is unprecedented in the UIC program, 

even for storage of hazardous wastes in Class I wells. Secondary containment 

fields are also unprecedented internationally: Countries where carbon capture 

and storage projects are currently underway - including Norway, Canada, 

Australia and Algeria - do not require additional 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 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

62
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.

To the comment that the geologic siting requirements could create a negative public perception, 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.

Commenter Name: Doug Louis Letter ID: 0121

Commenter Organization: Kansas Corporation Commission Comment ID: 22077

Comment: KCC staff finds the concept of additional containment zones above the confining 

zones to be confusing and unnecessary. If the injection zone and confining zone 

are competent, well understood and monitored, there is no need to have a costly 

and unneeded system of redundant containment zones above the two. Futhermore, 

the term "containment zone" is not found in the definitions section nor fully 

explained. 

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 clarifies that the GS rule defines confining zone as "a geologic formation, group of formations,

or part of a formation stratigraphically overlying the injection zone that acts as barrier to fluid

movement." (§146.81(d)).

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.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24735

63
Comment: - The implied recommendation that a geologic sequestration project have more 

than one confining zone is much more stringent than the requirements for Class I 

hazardous waste injection wells. 

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.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24769

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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 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.

Commenter Name: John Stormon Letter ID: 0123

Commenter Organization: Washington State Dept. of Ecology Comment ID: 23001

Comment: Containment or a caprock are critical to prevent the migration of CO2 upward 

into shallower USDWs. Allowing the director to require additional confining 

zones will allow regulators to include additional protective standards where 

needed and could allow use of an otherwise marginal formation for geologic 

64
sequestration. 

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. 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.

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: 21654

Comment: - Section 146.83(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." 

Response/Discussion: These zones would imply that "secondary containment" is 

necessary for GS. Such zones are not required for Class I hazardous waste wells, 

thereby giving the impression that GS is more risky than the underground storage 

of hazardous waste. While a "stacked system" of reservoirs and seals certainly 

provides additional safeguards to underground sources of drinking water (USDWs), 

in general, these containment zones will not be necessary in every case, 

especially when it can be demonstrated that seal integrity will be maintained 

over the life of a GS project. As stated in the proposed rule, "...their absence 

does not necessarily indicate inappropriateness of a GS site". 

The SWP agrees with the testimony of Edison Electric Institute at the Public 

Hearing on September 30, 2008 (Chicago, IL), that such an additional requirement 

would create the perception of fear among the public. Through international and 

national GS pilot studies of various scales, it has been demonstrated that it is 

very unlikely that GS would harm human health and the environment when sited 

properly. The SWP would recommend that the EPA remove this section from the 

final rule, since detailed siting evaluation is explicitly covered in Sections 

146.83(a)(1,2). 

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.

65
Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22579

Comment: Preamble Questions: EPA’s proposal would provide the Director the discretion to 

require the owner or operator to identify and characterize additional confining 

and containment zones above the primary (i.e., lowermost) confining zone that 

could further impede vertical fluid movement and allow for pressure dissipation. 

EPA says that these layers could provide additional sites for monitoring, 

mitigation, and remediation. EPA’s proposal would not require that these 

additional zones be identified for all GS sites because their absence does not 

necessarily indicate inappropriateness of a GS site. However, if such zones are 

present, information about their characteristics can provide inputs for 

predictive models, identify appropriate monitoring locations, and improve public 

confidence in and acceptance of a proposed GS site. EPA specifically seeks 

comment on the merits of requiring the identification of these additional zones. 

EPA Notice 64. 

NGWA Response: While NGWA believes that a site with a single confining can 

provide storage integrity, NGWA recommends 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 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.

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22592

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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. 

66
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 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.

Commenter Name: Patrick Nugent Letter ID: 0143

Commenter Organization: Texas Pipeline Association (TPA) Comment ID: 23140

Comment: 7. Characterization of a secondary containment zone should not be left to 

the discretion of the Director. The proposed regulations provide that at the 

Director's discretion, he or she shall require owners or operators of Class VI 

wells to identify and characterize secondary containment or confinement zones. 

Rather than stating this provision as a requirement to be imposed upon an 

applicant at the discretion of the Director, TPA suggests that EPA establish 

this provision as an additional demonstration to be made by an applicant, in the 

event that a secondary confinement zone is present at the site. The existence of 

a secondary confining zone would make the site more attractive for permitting 

and should be treated as an incentive to make the permitting process progress 

more smoothly and swiftly. A secondary containment zone is certainly not needed 

to ensure safe geologic sequestration. A single containment zone is all that is 

needed. Accordingly, if a secondary containment zone does exist at the site, 

then the applicant should be provided the opportunity to demonstrate that it 

does exist and to receive preferential treatment in the permitting process as a 

result. 

Response: EPA retains the requirement to identify additional containment/confining zones, if

required by the Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by

commenters representing states, water associations, and an electric utility who assert that these

requirements (at §146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing

and permitting a site for GS projects. 

EPA disagrees that such sites warrant "preferential treatment." Rather, the Agency expects that the

extensive site characterization data collected at each site will be evaluated in the context of that site

(and USDW protection) to support a determination regarding where a permit should be issued. The

67
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. 

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.

Commenter Name: Richard Driggans Letter ID: 0145

Commenter Organization: Tennessee Valley Authority Comment ID: 23149

Comment: 2. Siting - The proposed rule provides the Director the discretion to require 

the owner or operator to identify and characterize additional (secondary) 

confining and containment zones above the primary (i.e., lowermost) confining 

zone to further impede vertical fluid movement and allow for pressure 

dissipation. There are situations that must require secondary containment, 

e.g., CO2 GS well fields located in the vicinity of a designated sole-source 

aquifer or other aquifer widely used for water supply. Assurance of CO2 

containment must be near-absolute in such cases, and regulators must have 

discretion to require cap rock redundancy. As a further precaution, potential 

Response: EPA retains the requirement to identify additional containment/confining zones, if

required by the Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by

commenters representing states, water associations, and an electric utility who assert that these

requirements (at §146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing

and permitting a site for GS projects. 

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. 

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.

68
Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality

(MDEQ)

Comment ID:

22110

Comment: 10. EPA seeks comment on the concept of identifying and characterizing additional 

confining and containment zones above the primary confining zone. MDEQ agrees 

with this approach and EPA's reasoning that such information would add to 

predictive models, identify monitoring locations and improve public confidence 

and acceptance of a proposed geologic sequestration site. Additionally, in the 

environmental assessment process required under NEPA and some state environmental 

policy acts, such information would allow for more thorough consideration 

of project alternatives. 

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. 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.

Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality

(MDEQ)

Comment ID:

22127

Comment: 146.83 (b): MDEQ suggests that this content be a requirement, not at the 

discretion of the Director. All possible demonstration of containment needs to be 

a requirement. 

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 with the commenter that the requirement

should be mandatory. 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.

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22642

Comment: Allowing the Director the Discretion to Ask for Additional Fact Finding on 

Supplemental Confining Layers Page 43505-43506. EPA specifically asks for 

comments on allowing the Director to require that additional confining zones be 

identified for certain projects. Assuming that the Director uses this authority 

to require more fact finding for cause (i.e., it is not a capricious request), 

then it seems as if USEPA has struck an appropriate balance here and should 

retain this flexibility in the final rule. Given the capital cost of something 

like an IGCC+CCS, it does not seem unreasonable to ask that cores be taken from 

a second or third overlying caprock if there is some reason to want to ensure 

that there are additional containment systems beyond the caprock immediately 

above the target injection zone. While the USEPA might receive comments saying 

that this is potentially a significant unknown cost that could delay CCS 

deployment, the cost of this additional fact finding is likely denominated in 

the millions of dollars or less while the rest of the complete end-to-end CCS 

69
facility could be worth tens of billions of dollars. Again assuming that this 

flexibility is only used when needed and for cause, it seems to be an 

appropriate and cost effective tool for ensuring the overall goals of the Class 

VI program are fulfilled. 

Response: EPA acknowledges the commenter's support and agrees 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. 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.

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23759

Comment: Concern #4: Requirement for secondary confinement/containment. (Ref. page 43505, 

1Proposed Geologic Siting Requirements) 

The proposal would provide the Director the discretion to require the owner or 

operator to identify and characterize additional confining and containment zones 

above the primary (i.e., lowermost) confining zone that could further impede 

vertical fluid movement and allow for pressure and dissipation. Secondary 

containment (multiple confining structures) should not be required to prevent 

leakage of CO2. If required, this will prevent geologic storage in certain but 

important geographic regions. It also raises doubt concerning procedures and 

protocols to characterize and validate safe geologic storage formations and 

containment where there is not secondary containment. Under the proposed rule, 

there are measures that provide adequate assurance of formation integrity and 

require operators to demonstrate that their project will not endanger 

underground sources of drinking water (USDWs). If a secondary containment is 

present, it will be detected during site characterization and risk assessment. 

Such a special case could be analyzed to evaluate the potential risks to USDWs 

and to develop additional evaluation criteria to be applied to permit geological 

storage without going through the aquifer exemption process. 

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.

Commenter Name: James Stine Letter ID: 0163

Commenter Organization: National Rural Electric Cooperative Association Comment ID:

70
(NRECA) 21325

Comment: 4. On a related subject, EPA requests comment on whether the Final Rule should 

require, or allow the Director to require at his discretion, the identification 

and characterization of additional confining and containment zones above the 

primary (i.e., lowermost) confining zone that could further impede vertical 

fluid movement and allow for pressure dissipation -- in effect, a "secondary 

containment" requirement. Id. at 43505-06. As a general matter, NRECA opposes 

the inclusion of this secondary containment requirement, and believes that it 

will only be in the most unusual situations where the circumstances warrant the 

Director exercising his discretion and requiring this additional protection in a 

Class VI permit. While it is of course true that additional containment zones 

above the confining zone could impede vertical fluid movement, there is no basis 

for requiring these additional zones if it has already been demonstrated that 

the original confining is protective of USDWs. 

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.

Commenter Name: Michael Mudd Letter ID: 0167

Commenter Organization: FutureGen Alliance (FGIA) Comment ID: 22457

Comment: Multiple Confining Layers Could be Required at the Direction of the 

Director 

p. 53536, c. 3 The Proposed Rules for Class VI wells identified by EPA include a 

requirement for a confining zone with suitable properties to contain the 

injected CO2 (§ 146.83(a). In addition, under subsection (b) of the proposed 

regulation, owners or operators may be required to identify and characterize 

multiple confining layers, at the discretion of the Director (§ 146.83(b)). 

Comment: 

- Subsection (b) of § 146.83 of the proposed regulations, which grants the 

Director discretion to require the presence of multiple confining layers, does 

not promote sound policy and should be removed from the proposed regulation. 

- If EPA chooses to retain the option described in subsection (b), then the 

discretion of the Director should be limited, and there should be specification 

of the types of conditions under which multiple confining layers might be 

required. 

71
This optional requirement may eliminate suitable GS sites without reducing risk. 

It also adds a potential risk to a proposed project because the likelihood and 

cost of this additional requirement will not be known during the project 

initiation phase. 

The rationale for inclusion of an optional requirement for multiple confining 

layers is not provided. There does not appear to be any clear need for that 

additional requirement, which goes beyond what is currently required for Class I 

UIC wells that inject hazardous wastes. The proposed regulation could lead to 

significant problems in the future, but more importantly, this requirement is 

not needed. If subsection (b) of § 146.83 were removed, and if the Director or 

his staff find that the confining system identified by an operator does not 

appear to be reliable, they can reject the application and/or require that the 

operator provide information on additional confining layers. The description 

of the requirements for a confining system given in part (2) of subsection (a) 

would cover this situation, and would allow protection of USDW’s and the public 

without creating the potential for confusion that would arise with the option 

outlined in subsection (b). 

Previous experience and research have demonstrated that a single wellcharacterized confining system can provide more than adequate protection by 

preventing the upward migration of CO2. For example, time-lapse seismic imaging 

at the Sleipner Project demonstrates "the caprock is an effective seal that 

prevents CO2 migration out of the storage formation" (IPCC 2005). Examination 

of recent surveys of the safety of underground CO2 sequestration found no 

suggestion that multiple confining systems are needed or should be required 

(e.g., IPCC 2005; Benson and Surles 2006). In addition, the technical support 

document provided by EPA for the proposed rule changes (Vulnerability Evaluation 

Framework for Geologic Sequestration of Carbon Dioxide, EPA430-R-08-009) does 

not provide any support for requirement of multiple confining layers. 

The proposed regulations do not specify or in any way limit the conditions under 

which multiple confining layers might be required. Thus, there is no guidance 

for imposition of the rule, and no limitations on the discretion of the 

Director. Including this additional discretionary requirement as an option in 

the regulations is troublesome because there then is a good possibility that it 

could become the default requirement. If that were the case, the requirement of 

multiple confining layers would lead to potential disqualification of excellent 

storage sites, and additional costs for characterization. 

An additional problem with the optional requirement of multiple confining layers 

is one of perception. We know of no precedent within current UIC regulations, 

other applicable U.S. environmental law, or internationally, for the 

requirement of multiple confining layers to contain injected fluids. Given the 

lack of precedent, the inclusion of the requirement for multiple confining 

layers for CO2 in the proposed regulations for Class VI wells could lead to the 

incorrect perception by the public that injection and storage of CO2 is more 

dangerous to the public than subsurface injection of hazardous wastes. This 

perception of high risk, which does not appear to be justified by previous 

72
studies of the risks of subsurface CO2 sequestration (e.g., IPCC 2005; Benson 

and Surles 2006) could lead to decreased use of carbon sequestration as an 

option to limit global climate change, and therefore to decreased potential for 

full use of U.S. energy resources. 

References: 

Benson SM and T Surles. 2006. Carbon Dioxide Capture and Storage: An Overview 

with Emphasis on Capture and Storage in Deep Geological Formations, The 

Proceedings Special Issue, Institute of Electrical and Electronics Engineers 

(IEEE), Vol. 94, No 10, October 2006, DOI 10.1109/PROC.2006.883716. 

IPCC. 2005. IPCC Special Report: Carbon Dioxide Capture and Storage. Summary for 

Policy Makers and Technical Summary, B. Metz, O. Davidson, H. de Coninck, M. 

Loos, and L. Meyer (eds.). Cambridge University Press, New York. 

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 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.

Commenter Name: Michael J. Miller Letter ID: 0168

Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22494

Comment: Preamble, page 43505-43506 and §146.83(b): "Today’s proposal would provide the 

Director the discretion to require the owner or operator to identify and 

characterize additional confining and containment zones above the primary (i.e., 

lowermost) confining zone that could further impede vertical fluid movement and 

allow for pressure dissipation ... EPA specifically seeks comment on the merits 

of identifying these additional zones." 

EPRI COMMENT #4A: From a technical perspective, the key criterion for requiring 

additional characterization should be that the applicant cannot demonstrate 

73
compliance with the minimum criteria for siting a GS project specified in 

§146.83(a)(1) and (a)(2) -- specifically if the applicant must rely on [a] 

multiple injection zones to receive the anticipated total volume (§146.83(a)(1)) 

without fracturing the formation or displacing fluids or [b] multiple confining 

units to impede vertical movement (§146.83(a)(2)). Section §146.83(b) requires 

characterization of additional zones that will impede fluid movement, which 

seems redundant to §146.83 (a)(2). EPA should remove Section §146.83(b) and 

characterization of additional zones should be limited to those needed by the 

applicant to demonstrate capacity and containment (i.e., §146.83(a)(1) and (a) 

(2)). 

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.

Commenter Name: Michael J. Miller Letter ID: 0168

Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22496

Comment: EPRI COMMENT #4C: Section §146.83(b) of the rule states that the Director may 

require an applicant to characterize additional zones that will impede vertical 

fluid movement that are "free of faults and fractures." Because fracture-free 

confining units are rare and many confining units that contain fractures can 

provide effective confinement (see EPRI Comment #4B), and because §146.83(a)(2) 

provides for additional characterization of multiple confining zones if needed, 

EPRI recommends that this section be eliminated. 

Response: The Agency believes that the requirement at §146.83(a)(2) that the confining zone(s) 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 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.

Commenter Name: Theresa Pugh Letter ID: 0169

74
Commenter Organization: American Public Power Association Comment ID: 23398

Comment: APPA is not expert on drilling practices and many of the site characterization 

techniques discussed in the proposed rule. As discussed below, the Final Rule 

should leave the door open for a range of injection sites (except for sole 

source aquifers which we believe should be excluded from consideration) and 

methods (some of which are unrecognized, or even unknowable, at this point in 

time), provided that the Owner or Operator can show that the injection and 

storage will be protective of USDWs. APPA does join its "sister" organization, 

AWWA, representing the water utilities, in calling for proposed GS projects to 

at least identify all the confining zones in applications. APPA does not believe 

that multiple confining zones should be arbitrarily required. We defer to state 

directors to make these judgments based upon their knowledge of local geology. 

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 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.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24157

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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

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

75
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.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24222

Comment: Rule Provisions: 73 FR 43506 

EPA Preamble Question: 10. EPA’s proposal would provide the Director the 

discretion to require the owner or operator to identify and characterize 

additional confining and containment zones above the primary (i.e., lowermost) 

confining zone that could further impede vertical fluid movement and allow for 

pressure dissipation. EPA says that these layers could provide additional sites 

for monitoring, mitigation, and remediation. EPA’s proposal would not require 

that these additional zones be identified for all GS sites because their absence 

does not necessarily indicate inappropriateness of a GS site. However, if such 

zones are present, information about their characteristics can provide inputs 

for predictive models, identify appropriate monitoring locations, and improve 

public confidence in and acceptance of a proposed GS site. EPA specifically 

seeks comment on the merits of requiring the identification of these additional 

zones. EPA Notice 43506. 

API Response: API holds that secondary containment is not mandatory. There are 

many areas where a single confining zone can be shown to be highly protective of 

USDWs. Adequacy of containment must be done on a site-specific basis. This 

requirement would reduce the number of CCS storage site opportunities while 

increasing costs and not enhancing protection. 

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. EPA disagrees that the requirement

would reduce the number of sites available for GS. The intent of this requirement is to ensure that a

proposed site provides adequate protection of USDWs from endangerment; if this protection cannot

be demonstrated, the Director would not issue a permit for GS at the site.

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23482

Comment: On a related subject, EPA requests comment on whether the Final Rule should 

require, or allow the Director to require at his discretion, the identification 

and characterization of additional confining and containment zones above the 

primary (i.e., lowermost) confining zone that could further impede vertical 

76
fluid movement and allow for pressure dissipation - in effect, a "secondary 

containment" requirement. Id. at 43505-06. As a general matter, USWAG opposes 

the inclusion of a secondary containment requirement, even at the Director's 

discretion, and believes that it will only be in the most unusual situations 

where circumstances warrant the requirement of this additional layer of 

protection. 

In developing this regulatory program, EPA must ensure that CO2 GS is protective 

of USDWs while simultaneously taking care not to unduly burden the permitting 

process or discourage the development of environmentally protective Class VI 

wells. While it is of course true that additional containment zones above the 

confining zone could impede vertical fluid movement, there is no basis for 

requiring these additional zones if it has already been demonstrated that the 

original confining zone is protective of USDWs. A redundant requirement that is 

frequently unnecessary will eliminate otherwise valid injection zones from the 

universe of potential Class VI injection sites. 

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.

Commenter Name: Pamela Faggert Letter ID: 0175

Commenter Organization: Dominion Comment ID: 23520

Comment: b. Requirements for Secondary Containment 

The Agency is considering granting discretion to the Director to require 

"additional zones that will impede vertical fluid movement..." Such broad 

discretionary authority is unnecessary for the same reasons that limitations of 

injection to formation below the lowermost USDW are unnecessary. This 

discretionary authority is likely to have a negative affect on GS into 

unmineable coal seams and for storage through existing EOR wells. In the event 

the Agency elects to retain this authority, we urge EPA to modify the proposal 

to include clear guidelines in order to provide some amount of certainty for CCS 

operators and investors. Additionally, clear guidelines for exercising 

requirements for secondary containment would safeguard against what is 

discretionary authority on paper from becoming default requirements in practice. 

Secondary confinement should not be a requirement. Such a requirement 

would eliminate good and sound storage sites and reduce ultimate 

capacity of the country to store CO2. 

77
Response: EPA retains the requirement to identify additional containment/confining zones, if

required by the Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by

commenters representing states, water associations, and an electric utility who assert that these

requirements (at §146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing

and permitting a site for GS projects. 

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. 

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.

Commenter Name: Kenneth Nemeth Letter ID: 0176

Commenter Organization: Southern States Energy Board Comment ID: 23540

Comment: being sited in what would otherwise be very safe geology. SSEB also does not 

support the requirement of secondary seals for the same reason as stated above. 

The only requirement would be viable provisions for safe and secure containment 

to protect USDWs. 

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. EPA disagrees that the requirement

would reduce the number of sites available for GS. The intent of this requirement is to ensure that a

proposed site provides adequate protection of USDWs from endangerment; if this protection cannot

be demonstrated, the Director would not issue a permit for GS at the site.

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23551

Other EPA Comment Codes and Descriptions: 1310 1.1.2.4 Comments on other "out of scope"

issues, e.g., pore space ownership; 2100 1.6 Target Geologic Formations for GS; 3100 2.1 Proposed

Geologic Siting Requirements (40 CFR 146.83) 

Comment: 

EEI agrees that proper site selection is critical to a successful GS project and 

78
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.

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23583

79
Comment: A third area of concern related to siting involves the Agency’s proposed grant 

of discretion to the UIC program director to require permit applicants to 

identify "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"-i.e., secondary containment/confining zones. A proposal to require 

secondary containment, even in discretionary form, is unnecessary and 

unwarranted for many of the same reasons that a blanket limitation on receiving 

formations is unnecessary and unwarranted. Specific concerns include the 

following: 

- Better alternatives exist to protect USDW: The presumed purpose of secondary 

containment is better addressed through proper site selection and well-designed 

plans to detect and contain leakage from the primary containment system. EEI 

also notes, as we did in our May 15, 2008, pre-rulemaking comments, a discussion 

led by panelist Susan Hovorka of the University of Texas at EPA‘s December 2007 

public workshop, as characterized in the Agency‘s meeting summary (p. 8): 

CO2 is very responsive to pressure as a mitigation technique in the 

event of movement to an undesired location. Injecting fluids in an 

adjacent well at a regulated pressure can guide CO2 back to the 

containment area. Another mitigation option is changing injection 

patterns once a problem is detected. Site-specific contingencies could 

be built into plans to provide guidance in the event of an unexpected 

event. 

Given the proposed rules‘ emergency and remedial response requirements, a 

secondary containment requirement is especially unwarranted. 

- Unprecedented under the UIC program: Secondary containment/confining systems 

are currently not required for any other types of injection wells under the UIC 

program. The physical and chemical properties of CO2 are not sufficiently 

unique--nor do they pose a sufficiently unique potential threat to USDW--to 

warrant such unprecedented treatment under the UIC program. 

- Unprecedented in U.S. environmental law generally: We are unaware of any 

comparable requirement to ascertain secondary containment features in geologic 

formations in any other environmental regulatory regime. Those regimes that 

impose secondary containment requirements--for example, secondary containment 

requirements for oil spill prevention control and countermeasure plans under the 

Oil Pollution Act, and for land disposal and underground storage tanks under the 

Resource Conservation and Recovery Act (RCRA)--relate to man-made containment 

structures, as opposed to geologic containment structures. 

- Unprecedented internationally: To our knowledge, none of the CO2 storage 

projects currently operating outside the U.S. has been required to have or 

demonstrate existence of a secondary containment zone/confining system. 

Further, Norway, Canada, Australia and Algeria, countries where CCS projects are 

currently underway, do not require secondary containment. 

80
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. 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. 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.

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23584

Comment: - Concerns for inaccurate public perception: As noted above, no secondary 

containment requirement, whether blanket or discretionary, currently exists even 

for the injection of hazardous wastes under the Class I permitting scheme. 

Imposition of a substantially more rigorous requirement on injection and storage 

of CO2 strongly implies that such a project would be more dangerous than 

underground injection of a host of other materials, including hazardous wastes. 

The final rules should be crafted to avoid creating this public stigma for one 

of the most promising GHG-management strategies, and for a technology that can 

be employed safely and effectively in the absence of secondary containment 

requirements of any sort. 

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

81
projects, and are intended to improve understanding of the project as a whole and promote better

modeling of the site. 

EPA adds 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.

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23585

Comment: While EEI is opposed to any secondary containment requirement, including one 

that would be subject to exercise of the UIC program director‘s discretion, 

EPA‘s proposal to establish secondary containment as a discretionary requirement 

presumably would allow for consideration of the nature of the particular primary 

confining system at issue and reduce unnecessary elimination of potential 

storage sites as compared to a default requirement to demonstrate secondary 

containment. At the same time, discretion, even where warranted, must be 

bounded by sufficiently clear guidelines for application in determining whether 

imposition of a discretionary requirement is warranted in a given case. 

However, the proposed rules contain no discussion of any factors for the UIC 

program director to consider in making this determination. Should the Agency 

choose to impose a discretionary requirement, the current proposal should be 

modified to include such clear guidelines in order to provide some amount of 

certainty for operators and investors as well as to avoid the metamorphosis of 

what is a discretionary requirement on paper into a default requirement in 

practice. 

Response: EPA retains the requirement to identify additional containment/confining zones, if

required by the Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by

commenters representing states, water associations, and an electric utility who assert that these

requirements (at §146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing

and permitting a site for GS projects. 

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. 

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.

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23818

82
Comment: E. SECONDARY CONTAINMENT SHOULD NOT BE REQUIRED 

Secondary containment (i.e., a second formation of "caprock" above the initial 

formation) should not be required because it could limit the eligibility of 

potential storage sites, raise costs due to extra transportation, and add to the 

considerable regulatory burden of regulating site characterization. The 

standards of the Safe Drinking Water Act require that any injection that does 

occur will not result in endangerment of USDWs. This should be sufficient, 

without imposing in addition an arbitrary additional standard. 

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. EPA disagrees that the requirement

would reduce the number of sites available for GS. The intent of this requirement is to ensure that a

proposed site provides adequate protection of USDWs from endangerment; if this protection cannot

be demonstrated, the Director would not issue a permit for GS at the site.

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. 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23680

Comment: EPA Request for Comment: EPA specifically seeks comment on the merits of 

requiring the identification of additional confining and containment zones above 

the primary (i.e., lowermost) confining zone that could further impede vertical 

fluid movement and allow for pressure dissipation. EPA Notice 43506. 

AWWA Response: AWWA recommends that EPA require owner/operators to identify 

these additional confining and containment zones as part of the site 

characterization process. This identification is important to understand the 

project as a whole, and failing to identify these additional zones results in a 

very large knowledge gap in the identification of potential mitigation options 

in the event that a leak occurs from the primary confining layer. Having this 

information available to regulators and stakeholders would allow for a better 

understanding of the project as a whole, and would provide for a more informed 

and comprehensive review process. If certain stakeholders, such as drinking 

water utilities, were provided with this information, utilities would have a 

better understanding of a geologic sequestration project with the knowledge that 

multiple confining layers separated the carbon dioxide injection zone from their 

USDWs. 

83
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.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23729

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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.

Commenter Name: Bradley J. Field Letter ID: 0186

Commenter Organization: New York State Dept. of Environmental Conservation

Div. of Mineral Resources

Comment ID:

25179

Comment: I. EPA specifically seeks comment on the merits of identifying these additional 

zones. 

NYSDEC-DMN Response: It is NYSDEC-DMN’s opinion that identification and 

characterization of secondary confinement should not be a requirement unless the 

unit identified as the primary confining zone is questionable. This 

84
determination should be made on a project and site-specific basis. 

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. 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.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24331

Comment: 2. Redundant Confining/Containment Zone Requirement 

EPA requests comment on whether the Final Rule should require, or allow the 

Director discretion to require, additional confining and containment zones above 

the primary confining zone. 73 Fed. Reg. at 43505-06. We oppose any such 

requirement. 

If there are substantial doubts as to the adequacy of a single confining 

formation, it would of course be necessary to specify one or more additional 

formations as part of the a confining system that would be adequate to protect 

USDWs; this is one of the reasons the term "confining zone" is defined in the 

way it is (i.e., to include a "geologic formation [or] group of formations" 

acting as a barrier to fluid movement). Considerations as to the adequacy of the 

confining zone are a central focus of the permitting process, with permit 

applicants being required to demonstrate that USDWs will not be endangered by 

the proposed injection activity. By definition, a requirement for additional 

confining zones would therefore be a requirement for redundant geologic 

containment: it would never be necessary for the protection of USDWs. By 

allowing the Director discretion to impose such a requirement, the proposed rule 

would expressly authorize the imposition of requirements that are not necessary 

for the protection of USDWs. Worse, the proposed rule provides no apparent limit 

on the Director’s discretion in this regard. Indeed, the preamble suggests that 

the Director could require detailed evaluation of additional geologic formations 

just because they are there, perhaps in the hope that additional study and 

documentation - though not necessary to show that USDWs will be protected - 

might "improve public confidence in and acceptance of" GS. 73 Fed. Reg. at 

43506. 

Again, the ultimate standard for geologic citing should be protection of USDWs. 

By authorizing extraneous siting (or site assessment) requirements that are not 

necessary for protection of USDWs, the proposed rule would invite a "belt and 

suspenders" approach that would unnecessarily burden permit applicants and 

signal unwarranted concern about the risks and uncertainties associated with CO2 

injection. Under the UIC program, protection of USDWs is and should be enough. 

The Director should have no discretion - let alone unlimited discretion - to 

"tack on" additional siting requirements. 

It should be noted that a requirement for redundant confining and containment 

zones would be unprecedented. No such requirement exists in the UIC program, 

85
even in the context of hazardous waste injection. Nor does such a requirement 

apply in any of the countries where GS projects are currently underway 

(including Norway, Canada, Australia and Algeria). EPA should not single out GS 

for heightened and substantially more rigorous requirements than would apply in 

other contexts. To do so would signal a disproportionate concern about the 

injection of CO2 that simply is not warranted on the merits. 

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. 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.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24423

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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 

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

86
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.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24514

Comment: Rule Provisions or Federal Register Cite: 73 FR 43506 

EPA Preamble Question: 10. EPA’s proposal would provide the Director the 

discretion to require the owner or operator to identify and characterize 

additional confining and containment zones above the primary (i.e., lowermost) 

confining zone that could further impede vertical fluid movement and allow for 

pressure dissipation. EPA says that these layers could provide additional sites 

for monitoring, mitigation, and remediation. EPA’s proposal would not require 

that these additional zones be identified for all GS sites because their absence 

does not necessarily indicate inappropriateness of a GS site. However, if such 

zones are present, information about their characteristics can provide inputs 

for predictive models, identify appropriate monitoring locations, and improve 

public confidence in and acceptance of a proposed GS site. EPA specifically 

seeks comment on the merits of requiring the identification of these additional 

zones. EPA Notice 43506. 

CSC Response: Secondary containment should not be mandatory. There are many 

areas where a single confining zone can be shown to be highly protective of 

USDWs. Adequacy of containment must be demonstrated on a site-specific basis. By 

definition, an additional confining or containment zone beyond is not necessary 

to prevent endangerment of USDWs, and would serve only to prevent the use of 

otherwise-appropriate GS reservoirs. 

Response: EPA retains the requirement to identify additional containment/confining zones, if

required by the Director, as proposed (§146.83(b)). EPA clarifies that secondary confining zones are

not required for all GS sites. 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.

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23893

Other EPA Comment Codes and Descriptions: 4324 2.4.4.1.2 Comments opposed to requiring

injection below the lowermost USDW 

Comment: Lowermost USDW: 

EPA's proposal restricts injection to formations beneath the lowermost USDW and 

87
gives the Director the discretion to require identification of additional 

confining zones. ConocoPhillips recommends focus on performance standards rather 

than depth or confining zone redundancy - injection should be allowed into any 

injection zone which has geologic and mechanical isolation sufficient to prevent 

fluid movement which could endanger any USDW. In some site situations injection 

zones can be safely above USDW's with adherence to well construction standards 

and other requirements. There may be high potential geologic sites above USDWs 

which need not be excluded for storage. Identification of redundant confining 

zones may be confusing and unduly reduce the number of sites deemed appropriate 

for CCS. This is particularly true since the definition of confining zone 

includes "formation or set of formations." 

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. EPA also believes that a site-specific

demonstration regarding the need for additional confining zones affords the flexibility the

commenter seeks. 

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.

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. 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 implications, benefits, and challenges

associated with GS and ensuring water availability and USDW protection. 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: Paul Pike Letter ID: 0198

Commenter Organization: Ameren Corporation Comment ID: 23944

Comment: A related subject is the requirement to identify and characterize additional 

confining and containment zones above the primary (i.e., lowermost) confining 

zone that could further impede vertical fluid movement and allow for pressure 

dissipation - in effect, a "secondary containment" requirement. 73 Fed. Reg. at 

43505-06. We believe that only in the most unusual situations would 

circumstances warrant the requirement of an additional protective layer and 

oppose the inclusion of a "secondary containment" requirement. 

88
Response: 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 largescale 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 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. 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.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24577

Comment: Rule Provisions: 73 FR 43506 

EPA Rule Issue: 10. EPA’s proposal would provide the Director the discretion to 

require the owner or operator to identify and characterize additional confining 

and containment zones above the primary (i.e., lowermost) confining zone that 

could further impede vertical fluid movement and allow for pressure dissipation. 

EPA says that these layers could provide additional sites for monitoring, 

mitigation, and remediation. EPA’s proposal would not require that these 

additional zones be identified for all GS sites because their absence does not 

necessarily indicate inappropriateness of a GS site. However, if such zones are 

present, information about their characteristics can provide inputs for 

predictive models, identify appropriate monitoring locations, and improve public 

confidence in and acceptance of a proposed GS site. EPA specifically seeks 

comment on the merits of requiring the identification of these additional zones. 

EPA Notice 43506. 

Anadarko Petroleum Corporation (APC) Response: By utilizing the definition of 

confining zone (a geologic formation, group of formations, or part of a 

formation stratigraphically overlying the injection zone that acts as a barrier 

to fluid movement) the EPA has provided necessary guidance to prevent movement 

of fluids from the injection zone which may potentially endanger a USDW. The 

director discretion does not provide for any additional protection level of 

USDWs but does create issues and uncertainty by allowing the director to require 

dditional zones without scientific basis. 

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

89
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.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24653

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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 impede vertical fluid movement and allow for pressure dissipation, and also provide

additional sites for monitoring, mitigation, and remediation.

Commenter Name: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22166

Comment: EPA also seeks comment on whether the Final Rule should require, or allow the 

Director to require at his discretion, the identification and characterization 

of additional confining and containment zones above the primary confining zone 

that could further impede vertical fluid movement and allow for pressure 

dissipation. Id. at 43505-06. As a general matter, Southern Company opposes the 

inclusion of any sort of "secondary containment" requirement - even at the 

Director's discretion - as it would unnecessarily burden Owners or Operators of 

Class VI wells while providing little or no benefit in terms of USDW protection. 

An emphasis on proper site selection and characterization combined with 

performance-based standards will ensure that Class VI permits are only issued 

for CO2 GS projects where the primary containment zone will protect against 

endangerment of USDWs in the first instance. Identification of redundant 

confining and containment zones would only serve to confuse the permit 

application and approval process and unduly restrict siting of CO2 GS projects. 

Response: 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 large90
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 retains the requirement to identify additional containment/confining zones, if required by the

Director, as proposed (§146.83(b)). 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. 

Commenter Name: John Corra Letter ID: 0205

Commenter Organization: Wyoming Department of Environmental Quality

(DEQ)

Comment ID:

22201

Comment: 6. Various issues where we agree with US EPA that the Director should have the 

discretion to determine, or require: 

b.Identifying and characterizing additional confining and containment zones 

above the primary (i.e., lowermost) confining zone that could further impede 

vertical fluid movement and allow for pressure dissipation. 

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. 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.

Commenter Name: Christopher Murray Letter ID: 0207

Commenter Organization: Pacific Northwest National Laboratory Comment ID: 22431

Comment: Multiple Confining Layers Could be Required at the Discretion of the Director.....Page 3 

Subsection (b) of § 146.83 of the proposed regulations, which grants the 

Director discretion to require the presence of multiple confining layers, does 

not promote sound policy and should be removed from the proposed regulation. 

Response: 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 largescale 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 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

91
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. 

Commenter Name: Christopher Murray Letter ID: 0207

Commenter Organization: Pacific Northwest National Laboratory Comment ID: 22439

Comment: PROPOSED REGULATION 

p. 43536, c. 3 The proposed rules for Class VI wells identified by EPA include 

a requirement for a confining zone with suitable properties to contain the 

injected CO2 (§ 146.83(a)). In addition, under subsection (b) of the proposed 

regulation, owners or operators may be required to identify and characterize 

multiple confining layers, at the discretion of the Director (§ 146.83(b)). 

DISCUSSION 

The rationale for inclusion of an optional requirement for multiple confining 

layers is not provided. There does not appear to be any clear need for that 

additional requirement, which go beyond what is currently required for Class I 

UIC wells that inject hazardous wastes. The proposed regulation could lead to 

significant problems in the future, but more importantly, this requirement is 

not needed. If subsection (b) of § 146.83 were removed, and if the Director or 

his staff find that the confining system identified by an operator does not 

appear to be reliable, they can reject the application and/or require that the 

operator provide information on additional confining layers. The description 

of the requirements for a confining system given in part (2) of subsection (a) 

would cover this situation, and would allow protection of USDW's and the public 

without creating the potential for confusion that would arise with the option 

outlined in subsection (b). 

Previous experience and research have demonstrated that a single wellcharacterized confining system can provide more than adequate protection by 

preventing the upward migration of CO2. For example, time-lapse seismic imaging 

at the Sleipner Project demonstrates "the caprock is an effective seal that 

prevents CO2 migration out of the storage formation" (IPCC 2005). Examination of 

recent surveys of the safety of underground CO2 sequestration found no 

suggestion that multiple confining systems are needed or should be required 

(e.g., IPCC 2005; Benson and Surles 2006). In addition, the technical support 

document provided by EPA for the proposed rule changes (Vulnerability Evaluation 

Framework for Geologic Sequestration of Carbon Dioxide, EPA 430-R-08-009) does 

not provide any support for requirement of multiple confining layers. 

The proposed regulations do not specify or in any way limit the conditions under 

which multiple confining layers might be required. Thus, there is no guidance 

for imposition of the rule, and no limitations on the discretion of the 

Director. We believe including this additional discretionary requirement as an 

option in the regulations is troublesome because there then is a good 

possibility that it could become the default requirement. If that were the case, 

the requirement of multiple confining layers would lead to potential 

92
disqualification of excellent storage sites, and additional costs for 

characterization. 

An additional problem with the optional requirement of multiple confining layers 

is one of perception. We know of no precedent within current UIC regulations, 

other applicable U.S. environmental law, or internationally, for the requirement 

of multiple confining layers to contain injected fluids. Given the lack of 

precedent, the inclusion of the requirement for multiple confining layers for 

CO2 in the proposed regulations for Class VI wells could lead to the incorrect 

perception by the public that injection and storage of CO2 is more dangerous to 

the public than subsurface injection of hazardous wastes. This perception of high 

risk, which does not appear to be justified by previous studies of the risks of 

subsurface CO2 sequestration (e.g., IPCC 2005; Benson and Surles 2006) could 

lead to decreased use of carbon sequestration as an option to limit global 

climate change, and therefore to decreased potential for full use of U.S. energy 

resources. 

PNNL RECOMMENDATION 

For the reasons outlined above, we believe that subsection (b) of § 146.83 of the 

proposed regulations, which grants the Director discretion to require the 

presence of multiple confining layers, does not promote sound policy and should 

be removed from the proposed regulation. If EPA chooses to retain the option 

described in subsection (b), then we feel that the discretion of the Director 

should be limited, and there should be specification of the types of conditions 

under which multiple confining layers might be required. 

REFERENCES 

Benson SM and T Surles. 2006. Carbon Dioxide Capture and Storage: An Overview 

with Emphasis on Capture and Storage in Deep Geological Formations, The 

Proceedings Special Issue, Institute of Electrical and Electronics Engineers 

(IEEE), Vol. 94, No 10, October 2006, DOI 10.1109/PROC.2006.883716. 

IPCC. 2005. IPCC Special Report: Carbon Dioxide Capture and Storage. Summary for 

Policy Makers and Technical Summary, B. Metz, O. Davidson, H. de Coninck, M. 

Loos, and L. Meyer (eds.). Cambridge University Press, NewYork. 

Response: 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 largescale 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 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. 

93
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. 

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.

To the comment that the geologic siting requirements could create a negative public perception, 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.

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22695

Comment: 4. Secondary confinement/containment should not be required. 

Response: EPA retains the requirement to identify additional containment/confining zones, if

required by the Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by

commenters representing states, water associations, and an electric utility who assert that these

requirements (at §146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing

and permitting a site for GS projects. 

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. 

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22710

Comment: Concern #4: Requirement for secondary confinement/containment. (Ref: page 43505, 

1- Proposed Geologic Siting Requirements) 

The proposal would provide the Director the discretion to require the owner or 

operator to identify and characterize additional confining and containment zones 

above the primary (i.e., lowermost) confining zone that could further impede 

vertical fluid movement and allow for pressure and dissipation. Secondary 

containment (multiple confining structures) should not be required to prevent 

leakage of CO2. If required, this will prevent geologic storage in certain but 

important geographic regions. It also raises doubt concerning procedures and 

94
protocols to characterize and validate safe geologic storage formations and 

containment where there is not secondary containment. Under the proposed rule, 

there are measures that provide adequate assurance of formation integrity and 

require operators to demonstrate that their project will not endanger 

underground sources of drinking water (USDWs). If a secondary containment is 

present, it will be detected during site characterization and risk assessment. 

Such a special case could be analyzed to evaluate the potential risks to USDWs 

and to develop additional evaluation criteria to be applied to permit geological 

storage without going through the aquifer exemption process. 

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. EPA disagrees that the requirement

would reduce the number of sites available for GS. The intent of this requirement is to ensure that a

proposed site provides adequate protection of USDWs from endangerment; if this protection cannot

be demonstrated, the Director would not issue a permit for GS at the site.

Commenter Name: John King Letter ID: 0211

Commenter Organization: Shell Exploration and Production Company

(SEPCo)

Comment ID:

22765

Comment: 2. Redundant Confining/Containment Zone Requirement 

EPA requests comment on whether the Final Rule should require, or allow the 

Administrator discretion to require, additional confining and containment zones 

above the primary confining zone. 73 Fed. Reg. at 43505-06. SEPCo strongly 

opposes any such requirement. 

Rather than being necessary for the protection of USDWs, a requirement for 

additional confining and containment zones above the injection zone would apply 

in addition to the requirement for an adequate demonstration that USDWs will be 

protected. By definition, such a requirement is unnecessary. Having demonstrated 

the adequacy of their belts, there is no need to require permit applicants to 

furnish suspenders as well. 

It should also be noted that a requirement for additional confining and 

containment zones above the injection zone would be unprecedented. No such 

requirement exists in the UIC program, even in the context of hazardous waste 

injection. Nor does such a requirement apply in any of the countries where GS 

projects are currently underway (including Norway, Canada, Australia and 

Algeria). EPA should not single out GS for heightened and substantially more 

rigorous requirements than would be warranted on the merits of the actual risk. 

Recommendation: 

95
Require potential operators to demonstrate that USDWs will not be endangered by 

the proposed injection activity in the primary containment zone through the 

Class VI permitting process, without adding a requirement of any secondary 

confining or containment zones. 

Response: 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 largescale 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 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.

Commenter Name: Barbara Walz Letter ID: 0216

Commenter Organization: Tri-State Generation and Transmission Association,

Inc.

Comment ID:

22969

Other EPA Comment Codes and Descriptions: 2100 1.6 Target Geologic Formations for GS 

Comment: D. It is counterproductive at this stage in the development of a CO2 geologic 

sequestration regulatory regime to categorically preclude any potentially 

feasible injection formations as possible long-term storage sites. EPA 

recognizes that the commercial deployment of CO2 geologic sequestration 

activities will result in the production of large volumes of CO2 for which 

owners or operators will have to locate new and environmentally protective 

injection zones. Therefore, it makes sound policy sense for EPA to encourage the 

identification and utilization of as many protective zones as possible, with the 

prerequisite that any injection site be protective of underground sources of 

drinking water (USDW). Tri-State supports alternative approaches that would allow 

Response: 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.

Commenter Name: Barbara Walz Letter ID: 0216

Commenter Organization: Tri-State Generation and Transmission Association,

Inc.

Comment ID:

22972

Comment: EPA requests comment on whether the Final Rule should require, or allow the 

96
Director to require at his/her discretion, the identification and 

characterization of additional confining and containment zones above the primary 

(i.e., lowermost) confining zone that could further impede vertical fluid 

movement and allow for pressure dissipation in effect, a "secondary containment" 

requirement. Tri-State opposes the inclusion of this secondary containment 

requirement, and believes that it will only be in the most unusual situations 

where the circumstances warrant the Director exercising discretion to require 

this additional protection in a Class VI permit. While additional containment 

zones above the confining zone could impede vertical fluid movement, there is no 

basis for requiring these additional zones if it was already demonstrated that 

the original confining zone is protective of USDWs. 

Response: 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 largescale 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 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. 

Commenter Name: Olon Plunk Letter ID: 0217

Commenter Organization: Xcel Energy, Inc. Comment ID: 21557

Comment: Secondary Containment 

Requiring secondary containment as a matter of standard practice is unnecessary 

and will likely significantly decrease the number of geologic storage sites 

available. Such a requirement exceeds the standard for Class I hazardous waste 

injection wells, creating the logical, yet erroneous inference that CO2 

injection in a Class VI well poses a greater risk than Class I injection of a 

hazardous waste. Given the proposed rule's basic premise that the design of a 

Class VI well and the designated receiving formation must be protective of USDWs 

in order to be permitted in the first instance, the need for secondary 

containment is redundant and unnecessary. Secondary containment should remain 

only as an option to be proposed by the project applicant in instances where 

legitimate concerns over the primary containment capabilities of the receiving 

formation preclude permitting in the normal manner. 

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

97
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. The Agency

acknowledges that the additional confining formations may also, in site-specific circumstances,

further impede vertical fluid movement, provide additional sites for monitoring, mitigation, and

remediation, and allow for pressure dissipation.

EPA disagrees that the requirement would reduce the number of sites available for GS or that the

requirement implies that CO2 poses a greater threat than Class I hazardous wells. The intent of this

requirement is to ensure that a proposed site provides adequate protection of USDWs from

endangerment; if this protection cannot be demonstrated, the Director would not issue a permit for

GS at the site.

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24019

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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.

98
Commenter Name: Neeraj Gupta Letter ID: 0229

Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21828

Comment: Page 61, Injection Zone and Confining Layer - Conditions under which "director" 

may require a secondary containment/buffer zone should be more clearly defined 

to provide regulatory certainty. In addition, in definition of what constitutes 

a secondary containment or buffer zone is highly subjective and a matter of 

individual opinions. Therefore, more clarity on how these zones should be 

selected is requested. 

Response: EPA retains the requirement to identify additional containment/confining zones, if

required by the Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by

commenters representing states, water associations, and an electric utility who assert that these

requirements (at §146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing

and permitting a site for GS projects. 

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. 

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.

Commenter Name: Abbie Krebsbach Letter ID: 0235

Commenter Organization: Montana-Dakota Utilities Co. Comment ID: 23183

Comment: Secondary Containment Requirement Concerns 

A proposal to require secondary containment, even in discretionary form, is 

unnecessary and unwarranted for many of the same reasons that a blanket 

limitation on receiving formations is unnecessary and unwarranted. The presumed 

purpose of secondary containment is better addressed through proper site 

selection and well-designed plans to detect and contain leakage from the primary 

containment system. Montana-Dakota believes that the physical and chemical 

propel1ies of CO2 are not sufficiently unique, nor do they pose a sufficiently 

unique potential threat to USDW, to warrant such unprecedented treatment under 

the UIC program. 

Imposition of a substantially more rigorous requirement on injection and storage 

of CO2 strongly implies that such a project would be more dangerous than 

underground injection of a host of other materials, including hazardous wastes. 

The final rules should be crafted to avoid creating this public stigma for one 

of the most promising GHG-management strategies, and for a technology that can 

99
be employed safely and effectively in the absence of secondary containment 

requirements of any sort. 

However, should the EPA choose to impose a discretionary requirement for program 

directors to determine secondary containment requirements, the current proposal 

should be modified to include such clear guidelines in order to provide some 

amount of certainty for operators and investors, as well as to avoid the 

metamorphosis of what is a discretionary requirement on paper into a default 

requirement in practice. 

Response: 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 largescale 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 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 retains the requirement to identify additional containment/confining zones, if required by the

Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by commenters

representing states, water associations, and an electric utility who assert that these requirements (at

§146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing and permitting a

site for GS projects. 

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. 

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.

Commenter Name: Philip Papadeas Letter ID: 0238

Commenter Organization: Sandia Technologies, LLC Comment ID: 23352

Comment: §146.83 (a)(2) 

Re: Confining Zone free of transmissive faults 

This remains very difficult to prove or demonstrate in the subsurface unless 

detailed seismic and geologic data exists in the area to define such. One 

suggested approach may involve including a secondary buffer confining zone, as a 

redundancy to the first confining zone. The key may also be if there is 

100
connection from the Injection Zone to the Confining Zone, then additional 

modeling or reduction in injection rate/pressure and more of a margin of safety 

built in unless more detailed geological modeling demonstrates the lack of 

transmissive faulting. 

Response: EPA acknowledges that some smaller fractures may not be detectable during the site

characterization process. 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.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23230

Comment: 10. EPA’s proposal would provide the Director the discretion to require the 

owner or operator to identify and characterize additional confining and 

containment zones above the primary (i.e., lowermost) confining zone that could 

further impede vertical fluid movement and allow for pressure dissipation. EPA 

says that these layers could provide additional sites for monitoring, 

mitigation, and remediation. EPA’s proposal would not require that these 

additional zones be identified for all GS sites because their absence does not 

necessarily indicate inappropriateness of a GS site. However, if such zones are 

present, information about their characteristics can provide inputs for 

predictive models, identify appropriate monitoring locations, and improve public 

confidence in and acceptance of a proposed GS site. EPA specifically seeks 

comment on the merits of requiring the identification of these additional zones. 

EPA Notice 43506. 

Redundant confining zones should not be required. If the primary confining zone 

is adequate, by definition it is sufficient. If one sequestration site 

identifies one confining zone and another identifies multiples, it may lead to 

public confusion and lack of confidence in a site that only has one confining 

zone even though it is just as protective. 

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.

101
Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23284

Comment: 146.83(b) Delete reference to identification of additional confining zones. 

This implies this will be required. Redundant confining zones are not required 

in other UIC well classes. 

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.

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22305

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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 

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

102
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.

Commenter Name: Walter L. Baker Letter ID: 0253

Commenter Organization: Utah Division of Water Quality Comment ID: 22346

Comment: ALLOWING FOR DIRECTOR DISCRETION IN REQUIRING ADDITIONAL

CONTAINMENT ZONES 

We support EPA's intention to provide Director's discretion in requiring 

additional confining and containment zones that could further impede vertical 

fluid movement and allow for pressure dissipation. This acknowledges the 

importance and merit of implementing a risk-based, site-specific approach in 

characterizing a site for CCGS projects. This allows for flexibility in setting 

permit requirements for the protection of USDWs and other natural resources 

thereby increasing the number of sites that could potentially be used for CCGS. 

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. 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. EPA 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.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24814

Comment: EPA Rule Issue: 10. EPA’s proposal would provide the Director the discretion to 

require the owner or operator to identify and characterize additional confining 

and containment zones above the primary (i.e., lowermost) confining zone that 

could further impede vertical fluid movement and allow for pressure dissipation. 

EPA says that these layers could provide additional sites for monitoring, 

mitigation, and remediation. EPA’s proposal would not require that these 

additional zones be identified for all GS sites because their absence does not 

necessarily indicate inappropriateness of a GS site. However, if such zones are 

present, information about their characteristics can provide inputs for 

predictive models, identify appropriate monitoring locations, and improve public 

confidence in and acceptance of a proposed GS site. EPA specifically seeks 

comment on the merits of requiring the identification of these additional zones. 

EPA Notice 43506. 

GWPC CO2 Committee Response: Any showing of secondary containment is unnecessary 

once the requirement for containment has been satisfied by providing for an 

adequate confining zone. References to additional confining and containment 

103
zones is more likely to lead to confusion than support. 

Rationale: Any emphasis on the availability of additional confining zones is 

likely to cause confusion over the adequacy of projects that satisfy the actual 

requirements but do not also provide what is by definition redundant and 

unnecessary layers of protection. Moreover, discussions of additional confining 

zones could undercut the ability to use beneficially any additional formations 

in the area of interest covered by a proposed project. 

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.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24880

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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.

Commenter Name: Claire Olson Letter ID: 0260

Commenter Organization: Basin Electric Power Cooperative Comment ID: 22396

104
Comment: "1. Proposed Geologic Siting Requirements" 

EPA requests comments on whether the final rule should require the 

identification and characterization of additional confining and containment 

zones with the primary (lowermost) confining zone that could further impede 

vertical fluid movement and allow for pressure dissipation and act as a 

"secondary containment" requirement. 

Basin Electric opposes the inclusion of this secondary containment or 

characterization requirement as a default provision. In the rare situation where 

specific site circumstances would warrant, the State Director could exercise 

discretion and require this additional protection in a Class VI Permit. 

This requirement for additional containment zones is not needed if it has 

already been demonstrated and characterized that the original confinement zone 

is protective of USDW. The requirement to identify and characterize additional 

zones that will impede vertical fluid movement is too broad. 

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.

Letter ID: 0263

Commenter Organization: Interstate Oil & Gas Compact Commission Comment ID: 22795

Comment: III A. 1 Proposed Geologic Siting Requirements 

K. EPA specifically seeks comment on the merits of identifying these additional zones. 

IOGCC Response: Secondary confinement should not be a requirement. Such a 

requirement would eliminate good and sound storage sites and reduce ultimate 

capacity of the country to store anthropogenic CO2. The determination as to 

whether secondary confinement should be required should be made on a project by 

project basis and be site specific. It is possible to hypothesize a circumstance 

where secondary confinement is not necessary with the addition of stronger 

monitoring requirements. 

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)).

105
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. EPA disagrees that the requirement

would reduce the number of sites available for GS. The intent of this requirement is to ensure that a

proposed site provides adequate protection of USDWs from endangerment; if this protection cannot

be demonstrated, the Director would not issue a permit for GS at the site.

Commenter Name: Michael Moore Letter ID: 0265

Commenter Organization: North American Carbon Capture & Storage

Association (NACCSA)

Comment ID:

22863

Comment: 2. Secondary Containment 

Another area of concern related to siting involves the Agency's proposed grant 

of discretion to the UIC program director to require permit applicants to identify 

secondary containment/confining zones. While NACCSA agrees with the Agency's 

current approach not to include a blanket secondary containment requirement 

(although, if secondary confining units exist with regard to a given project, 

they should be included in site modeling, along with identification of any 

transmissible zones between the primary and secondary confining units), and, 

while a discretionary requirement for secondary containment is preferable to a 

blanket, universal requirement, any discretionary requirement that is imposed 

should be bounded by clear parameters for its use. The proposed rule, however, 

contains no such parameters. NACCSA urges the Agency to consider what parameters 

may be put in place to ensure protection ofUSDWs while providing some level 

of clarity for project operators and investors regarding under what circumstances 

such a requirement should be expected, as well as some degree of assurance 

that the "on paper" discretionary requirement will not lead to an "in practice" 

blanket requirement due to the lack of appropriately enumerated. 

Several points should be considered in determining whether any sort 

of requirement for secondary containment, including a discretionary requirement, 

should be imposed, as well as what parameters maybe appropriately included in the 

final rule should the Agency choose to implement a discretionary requirement. They 

include the following: 

- Do better alternatives exist to protect USDWs? In any given case, the 

additional protection to USDWs that the Agency appears to believe secondary 

containment could provide likely may be better addressed through proper site 

selection and well-designed plans and procedures to detect and contain leakage 

from the primary containment system, rather than through imposing de facto 

limitations on the types of sites that maybe used. If such requirements have 

already been satisfied, there is likely no need for secondary containment. 

- What public misconceptions maybe created? Secondary containment is 

unprecedented under the UIC program, even for the injection of hazardous wastes 

under the Class I permitting scheme. Imposition of such a requirement on 

injection and storage of CO2suggests that such a project would be more dangerous 

than underground injection of a host of other materials, including hazardous 

106
wastes, or even than injection of CO2 for purposes of EOR. The Agency should 

carefully consider the risk of creating unwarranted negative public perception 

posed by proposed requirements. In any given case, CCS technology can be safely 

employed absent any secondary containment requirements. 

Response: 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 largescale 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 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. 

To the comment that the geologic siting requirements could create a negative public perception, 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.

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. 

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.

Commenter Name: Karl R. Moor Letter ID: 0501

Commenter Organization: Southern Company Comment ID: 21159

Comment: For example, requiring a secondary containment field for this is, would create 

the wrong impression about the safety of carbon capture and storage, and it 

should not be a part of the final rule. Such a requirement is unprecedented in 

the UIC program. 

Even for the storage of Class I sources secondary containment fields are also 

unprecedented internationally. Countries where carbon capture and storage 

projects are currently underway, besides the United States, including Norway, 

Canada, Australia, and Algeria did not require secondary containment zones. And 

in those, in most of these instances the countries are in fact using the 

existing petroleum walls without the benefit of an additional regulatory 

program. 

107
Singling out, as the regulations do, carbon capture and storage would just 

heighten the substantial level of scrutiny. It sends a message that carbon 

dioxide is more dangerous than the underground injection of other substances. 

And since EPA is the agency in charge with protecting the environment, the 

public could easily be swayed by EPA's apparent apprehension of carbon capture 

that's currently, that is currently embodied in the regulations. 

In order to create a regulatory scheme that fosters carbon capture and storage 

the development and employment, the EPA should also consider how it has 

characterized carbon capture injection, both explicitly and implicitly in the 

regulation. 

Moreover, EPA should consider the effect of these regulations on securing 

critical financial support for CCS projects. Misperceptions about the risks can 

skew opportunities for financing. No one needs to be reminded today that the 

recent turmoil in the financial markets makes very challenging the financing of 

new technologies. 

In a credit constrained world the heightened risk and overplaying risk and the 

conflicts that this regulation can impede the development of a critically 

important technology for reducing CO2 emissions. 

Response: 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 largescale 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 retains the requirement to identify additional

containment/confining zones, if required by the Director, as proposed (e.g., §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.

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. 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. To the comment

that the geologic siting requirements could create a negative public perception, 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.

Commenter Name: Kevin Frederick Letter ID: 0525

Commenter Organization: Wyoming Department of Environmental Quality Comment ID: 21399

Comment: Discretion for identifying and characterizing additional confining and 

containment zones of the primary confining zone that could further impede 

vertical fluid movement and allow for pressure dissipation. 

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

108
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.

Commenter Name: Doug Louis Letter ID: 0530

Commenter Organization: Kansas Corporation Commission Comment ID: 21340

Comment: KCC staff finds the cost of additional containment zones above the confining 

zones to be confusing and unnecessary. If the injection zone and the confining 

zone are competent, well understood and monitored, there is no need to have a 

costly and unneeded system of redundant containment zones above the two. 

Furthermore, the term containment zone has was not in the definitions section or 

fully explained. 

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 clarifies that the GS rule defines confining zone as "a geologic formation, group of formations,

or part of a formation stratigraphically overlying the injection zone that acts as barrier to fluid

movement." (§146.81(d)).

Comment Code: 3130 2.1.3 Comments that operators should submit more (or different) geologic

data than proposed 

Individual Comments

Commenter Name: Michael H. Cochran Letter ID:

0108

Commenter Organization: Bureau of Water, Division of Environment, Kansas

Department of Health & Environment (KDHE)

Comment

ID: 21963

Comment: 146.82 (g): Needs to list the formations for which baseline geochemical data 

should be obtained. In addition to the USDWs, this at minimum should include the 

injection formation and the confining zone immediately above the injection zone. 

Response: The GS regulation, at §146.82(a)(6), requires the owner or operator to submit baseline

geochemical data on subsurface geologic formations. EPA is not specifying for which formations

109
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 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.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24762

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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.

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22545

Other EPA Comment Codes and Descriptions: 2064 1.5.3.2 Grandfathering construction of Class

II wells (seeking comment); 2066 1.5.3.3 Grandfathering construction of Class V wells (seeking

comment); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: The NGWA Carbon Sequestration Task Force recommends that the experimental phase 

extend beyond the regional partnerships to each site proposed for productionscale injection of carbon dioxide. It is recommended that at least one well at 

each site be constructed under the Class V experimental category, and that 

110
testing of the adequacy of the geologic environment for geologic sequestration 

of carbon dioxide be conducted prior to permitting any well in the Class VI 

category at the site. 

The transition of carbon dioxide injection wells from Class II (Enhanced Oil 

Recovery wells) to Class VI (carbon sequestration wells) will presumably be 

requested when production of the petroleum has ceased. Liquid carbon dioxide 

from a distant source, such as a power plant, can be stored in the depleted 

petroleum reservoir even after production has ceased, necessitating a change in 

classification of the injection well. The new use of the wells involves much 

longer storage time, and raises concerns about mechanical integrity and long 

term effects, including geochemical changes, on underground source of drinking 

water (USDWs). The reclassification should depend on a positive outcome from a 

Class V experimental program conducted in the depleted reservoir, as described 

below. 

The "grandfathering" of Class V carbon sequestration wells would mean allowing 

experimental wells to be permitted for operation after the testing period is 

over. The NGWA Carbon Sequestration Task Force recommends that each carbon 

sequestration system or wellfield have an experimental phase, and not rely on 

results from distant experimental locations. Thus, nearly every operational 

well would start as a Class V experimental well, or would go through a Class VI 

testing phase, before being permitted for long-term operation. The transition 

to Class VI operational status would require demonstrating that the minimum 

requirements are met at that location. Most wells would go through the 

following permitting phases: 

- Class V experimental well construction permit: This permit would allow 

geologic and geophysical testing, aquifer testing, laboratory work, etc, but 

would not include injection of CO2 (only potable water injection testing would 

be allowed). 

- Class VI experimental well operational testing permit: At this stage, 

the full monitoring facilities would need to be constructed. This permit would 

allow test injection of liquid CO2 at rates high enough to demonstrate that the 

location meets the minimum requirements for operation, for a period of up to two 

years. 

- Class VI operation permit: After demonstrating that the location and 

the well meet all the minimum requirements for injection of CO2, the operation 

permit can be issued. 

The goals of the experimental well Class V construction permit would be to make 

the following demonstrations: 

- A receiving zone of sufficient depth, area extent, thickness, porosity, and 

permeability is present; 

- Lithologic description, geological name, thickness and depth of each confining 

unit above the storage aquifer, and of each USDW. 

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- A trapping mechanism that is free of pathways for migration of injected fluids 

into a USDW. These pathways may include major non-sealing faults, porous beds 

within the confining unit, changes of facies trending toward more porous units 

and man-made structures such as wells or mine shafts. A trapping mechanism is 

defined as a geologic environment that prevents vertical and horizontal movement 

of fluids into a USDW; The volume of the trap shall exceed the proposed total 

volume of injected carbon dioxide for the life of the proposed facility 

- Identification of all confining units between the primary injection/storage 

zone and the lowermost USDW, and their adequacy to contain the injected fluid. 

Unless the only feasible injection zone has only one confining unit separating 

it from the lowermost USDW, this demonstration includes adequacy of confinement 

for both the primary confining unit and a secondary containment system that 

extends to the base of the lowermost USDW and is completely redundant of the 

primary confining system and could confine the injected CO2 should the primary 

system fail. In locations where the secondary containment system is not 

possible, the applicant shall propose an alternative system of early warning of 

failure of the primary confining unit in order to avoid impacting any USDW 

should that confinement fail. This demonstration applies in the horizontal 

sense as well, demonstrating one or more mechanisms containing the fluid from 

horizontal movement into a USDW in the storage aquifer at a distant location. 

- The construction of an operational monitoring system meeting all the 

requirements described in this document’s MMV section, and demonstration of the 

adequacy of this system to meet those requirements. 

- Demonstration of mechanical integrity 

Having made the foregoing demonstrations, a Class VI operational testing permit 

can be issued for a period of up to two years. The goals of the experimental 

well Class VI operational testing permit would be to make the following 

demonstrations: 

- A hydraulic demonstration of the adequacy (depth, area extent, thickness, 

porosity, and permeability) of the storage zone, using monitoring data and 4-D 

seismic monitoring of the extent of the CO2 plume. 

- Demonstration of the adequacy of the trap for 5/10 years of injection at the 

proposed rate. The volume of the trap shall exceed the proposed total volume of 

injected carbon dioxide for the 5/10 years of the first operation permit. 

- Demonstration of the adequacy of confinement under operational conditions 

using monitoring data and a method of detecting the extent of the CO2 plume in 

the storage aquifer, such as 4-D seismic monitoring or direct sampling. 

- Re- evaluation of the Area of Review and extent of the zone of endangering 

influence. 

- Re-evaluation of mechanical integrity, using the buoyancy of the injected CO2 

to better measure external mechanical integrity. The re-evaluation shall 

include the testing required during the initial MIT, as well as evaluation of 

the cement for carbonation, or chemical weathering by CO2 

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Under this permitting scenario, the vast majority of Class V experimental wells 

would be constructed after the Class VI standards had been published. The 

"grandfathering" of Class V wells that do not meet the Class VI construction 

standards would only be needed for DOE test sites established before rulemaking 

was complete. If these wells include the ongoing mechanical integrity 

monitoring of annular fluid pressure and composition, and they pass periodic 

mechanical integrity testing, they should be able to follow the same permitting 

procedures to become operational Class VI wells. 

Response: EPA believes 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 notes that changes to these

plans require a permit modification under §144.39, the public must be notified according to the

public comment procedures under 40 CFR 124.

Please see the final rule and the discussion of geologic site characterization in the preamble for

additional information.

EPA disagrees that every GS well should initially be permitted as a Class V well. The Agency

believes that the tailored Class VI requirements including extensive requirements for geologic site

characterization at §146.82, AoR evaluation at §146.84, and testing of the well during drilling at

§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. Given this approach to permitting Class VI projects, EPA believes that the

requirements for grandfathering of construction at §146.81(c) are necessary and appropriate.

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22546

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for

permit applications (seeking comment) 

Comment: Geologic Characterization 

The UIC program is required under the Safe Drinking Water Act to protect USDWs 

from contamination from fluids injected into the subsurface. Part of this 

requirement is the demonstration that the injected fluids will not migrate, 

through buoyancy, ground-water flow or injection pressure, into USDWs. This 

demonstration is based on the characteristics of the geological environment 

where injection is to take place. The current UIC regulations require 

investigation of waste disposal sites through an application-phase data summary 

(Area of Review study) and geologic testing while drilling the pilot hole of the 

injection well. In general, the critical attributes of the injection and 

confining units are measured during pilot hole drilling, and the integrity and 

extent of those units are addressed in the literature review and Area of Review 

study at the application phase. Because of the large volumes of carbon dioxide 

that are expected to be injected, and the vast extent of the storage zones, it 

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is expected that more detailed information will be needed over a larger area for 

carbon sequestration than has been historically needed for injection of other 

wastes. 

The NGWA recommends that the adequacy and safety of injection of liquid carbon 

dioxide at each site be evaluated by multi-phase, variable density ground-water 

modeling, supported by extensive field investigations (see section General 

Comments on the Use of Modeling for Ground-Water Protection Related to CO2 

Sequestration, below) These models should be included at the experimental 

well permit application phase as conceptual models, and progressively refined as 

data are collected during well construction and testing, and monitoring of 

operations. 

The test injection well/operational testing permit application for a carbon 

sequestration injection well must address the geological characteristics of the 

site. The data presented at this stage should be adequate to make and calibrate 

an appropriate ground-water model. The necessary elements of the geologic 

system for carbon sequestration include: 

- A receiving zone of sufficient depth that the injected carbon dioxide 

can be maintained in a supercritical state 

- Of sufficient areal extent that it includes the entire zone of endangering 

influence 

- Of sufficient thickness and porosity to contain the volume of carbon dioxide 

injected over the life of the proposed system 

- Of sufficient permeability to accept the peak daily flow of injected carbon 

dioxide from the facility 

- A trapping mechanism (consisting of either impermeable barriers or 

geochemical/mixing barriers) that is free of vertical or horizontal pathways for 

migration of injected fluids into a USDW. The volume of the trap shall exceed 

the proposed total volume of injected carbon dioxide for the life of the 

proposed facility 

- A primary confining system of sufficient areal extent, thickness and 

competency to contain the injected fluid at proposed rates and volumes without 

initiating or propagating fractures in the confining zone 

- Unless the only feasible injection zone has only one confining unit separating 

it from the lowermost USDW, a secondary containment system that is completely 

redundant of the primary confining system and could confine the injected CO2 

should the primary system fail. 

- The identification of a monitoring zone between the primary and secondary 

confining units. In locations where the secondary containment system is not 

possible, the applicant shall propose a monitoring formation to provide early 

warning of failure of the primary confining unit in order to avoid impacting any 

USDW should that confinement fail. 

- Provide depth and completion information of all USDWs that may be affected by 

the injection if fluid movement does occur. 

- Provide geochemical information on subsurface aquifers, including all USDWs: 

Baseline geochemical data on water-rock- CO2 geochemistry and mineral reactions, 

maps and cross sections. 

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These elements should be identified in existing well records, in geologic 

literature, and by using the results of the exploratory program. The critical 

storage and confining units should be shown to exist over the entire area of 

review, or zone of endangering influence 

The operation permit application should also include a preliminary multi-phase 

numerical transport model for CO2 and formation fluid, including all of the 

elements listed above. This model should include at least one calibration 

scenario and will be used to provide a preliminary evaluation of the adequacy 

and safety of injection of carbon dioxide at the site, as well as a preliminary 

calculation of the potential storage volume of the geologic structure. 

Each permit application for a carbon sequestration injection well must include 

an Area of Review study, which addresses the entire zone of endangering 

influence of the carbon sequestration operation, including the area impacted 

after cessation of injection due to buoyancy transport. The zone of endangering 

influence shall be determined by the ground-water model described above and 

illustrated with maps and cross sections. 

Provide information on the geologic structure of the proposed site, including: 

- Maps and cross sections of local geologic structure. Each cross section 

should include the location and depth of relevant data sources, including 

geophysical logs, that were used in developing the cross section 

- Geological name and lithologic description of each injection zone, primary 

and/or secondary confining unit, and USDW 

- Data on the receiving formation and the confining systems : 

1. Size of the storage reservoir, and extent of the confining units in 

comparison to the area of endangering influence 

2. Presence or absence of a secondary confining unit 

3. Porosity, and permeability of the storage zone and confining units, 

including any geology/facies changes, based on field data which may 

include geologic cores, outcrop data, 3-dimensional seismic surveys, and 

well logs 

4. Capacity of the storage zone in comparison to the proposed total 

volume of carbon dioxide to be stored, 

5. Evaluation of the long-term effectiveness of the storage structure, 

including expected pathways of migration of injected carbon dioxide, and 

the horizontal barriers to fluid movement 

- Geomechanical information on fractures, stress, rock strength, and in situ 

fluid pressures within the primary and secondary containment units and confining 

systems 

- Identification of potential pathways for migration of injected fluids and 

determination that they would not conduct a volume of fluid that would cause a 

violation of the prohibition of fluid movement as it applies to the class of 

well that is to be constructed 

- Identification of potential risks within the zone of endangering influence, 

including degradation of water quality in USDWs, gas buildup in USDWs, reduction 

of porosity through geochemical changes in USDWs, and population that could be 

affected by gas releases. 

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- List of penetrations into the injection zone and secondary containment system. 

- Information on seismic history and the presence/depth of seismic sources 

Response: EPA agrees that extensive geological data collection and computational modeling, similar

to what the commenter suggests, are important components of characterizing a potential GS site. For

this reason, the GS regulation requires owners or operators to collect and submit extensive

geological data (specified at §146.82) on the proposed GS site, including the injection and confining

zones. Operators must also delineate the AoR using computational modeling that accounts for the

multiphase flow of CO2 and native fluids (§146.84(c)), based on the geological data collected and

proposed injection operations. 

EPA disagrees with the comment that all sites should be evaluated by multi-phase, variable density

groundwater modeling; instead, EPA believes that owners or operators should have the flexibility to

select models that are most appropriate to site conditions and available data types and amounts. EPA

is also requiring that the AoR be reevaluated at a frequency of every 5 years using monitoring and

operating data to verify that the CO2 plume and pressure front are behaving as predicted in AoR

calculation models (§146.84(e)).

Commenter Name: Brianne Metzger Letter ID: 0151

Commenter Organization: Spectra Energy Corp Comment ID: 21824

Comment: EPA is proposing that an applicant include "baseline geochemical data on 

subsurface formations, including all USDWs in the area of review." 40 C.F.R. § 

146.82(g). It is not clear how much baseline data EPA is expecting the permit 

applicant to generate and collect from additional drilling or testing of the 

injection zone and all other zones. Given the likely depth of many of the GS 

wells through multiple strata, this could involve tens (and possibly hundreds) 

of different formations above the injection zone. Therefore, we would 

recommend that EPA limit the baseline geochemical data "where feasible, to the 

next porous formation above the injection zone." EPA should also clarify that 

the permit applicant may rely upon secondary sources (such as other drilling or 

geologic records) that relate to and support the data requirement. EPA should 

also clarify whether the Agency expects applicants to test private wells, where 

permission is granted, within the AoR for purposes of establishing baseline 

data. As a general matter, Spectra believes that EPA should not require 

testing of private wells because sampling results could be affected by flawed 

well construction or poor integrity, wholly unrelated to the injection project. 

Response: The GS regulation, at 146.82(a)(6), requires the owner or operator to submit baseline

geochemical data on subsurface geologic formations. EPA is not specifying for which formations

this information should be submitted in the rule 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 does not expect that testing of

private wells will be required in most cases, but clarifies that the Director has authority to require

such sampling if it is believed to be necessary to ensure USDW protection. 

While each monitoring plan will be site-specific based on data collected during the initial site

characterization and baseline geochemical monitoring, it is likely that geochemical sampling might

116
include basic water quality parameters such as pH, specific conductivity, temperature, CO2,

alkalinity, major ions, and select heavy metals. Additional parameters may be monitored based on

the potential for leaching of minerals or the geochemistry of native fluids.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24151

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 

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.

117
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.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24153

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 

to the project. This responsibility is best left with EPA. 

118
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.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24413

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 

119
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 

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).

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24415

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

Comment: Rule Provision: 146.82(d) 

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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

(§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.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24416

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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; 

121
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.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24417

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 

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).

122
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). 

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24418

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 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).

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24641

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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, 

123
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 

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. 

124
Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24643

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 

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. 

125
Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24644

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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: 24645

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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

126
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). 

Commenter Name: Diane VanDe Hei Letter ID: 0213

Commenter Organization: Association of Metropolitan Water Agencies

(AMWA)

Comment ID:

22936

Comment: o Data can and should be gathered immediately and more core analysis should be 

required in the permitting process -- specifically for key formations and for 

water/rock/gas interaction. 

Response: The Agency agrees and believes that the site characterization requirements at §146.82 are

essential to proper siting of a GS well and are the foundation for a detailed understanding of the

local and regional geology. Collecting and evaluating geochemical data in and around the CO2

injection zone, as required in §146.82(a)(6), serves several purposes. This baseline geochemical data

can help predict geochemical reactions between the injectate, reservoir geology, and formation

fluids. Such reactions can lead to dissolution and precipitation of minerals which affect formation

porosity, which in turn can affect required injection pressure (Sminchak and Gupta, 2002) and

transport of fluid within the formation. While the confining layer is the primary barrier to CO2

movement into a USDW, multiple barriers are important and changes in injection pressure and fluid

movement may compromise those barriers. An increase in injection pressure due to reduced porosity,

in particular, can lead to fracturing of the confining layer and potentially allow fluid movement

outside of the injection zone. Losses in injectivity because of geochemical reactions may also require

additional injection wells and further penetrations in the confining layer that can become pathways

for fluid migration.

Commenter Name: Philip Papadeas Letter ID: 0238

Commenter Organization: Sandia Technologies, LLC Comment ID: 23349

Comment: §146.82 

127
Re: Collection of detailed geologic data. 

The collection of this data is the operator’s burden, and should be built on 

accumulation of all known geologic material in the area. Sandia believes this 

information is valuable for modeling, site characterization and geologic profile 

of the injection- confinement system. If none is present, then the operator 

must demonstrate via stratigraphic test or an information well all pertinent 

formation cores, not only of proposed permeable injection intervals, but 

overlying buffer intervals, confining zone cores, and formations that will act 

as hydraulic seals. 

One proposed approach is for the Agency to make the first Permitted injection 

well conditional, collecting the required data and providing this to the EPA 

under an adjusted permit to demonstrate that the data matches conservative 

assumptions used in reservoir and geologic modeling. The follow-up wells should 

collect in-fill well data on geomechanics and confirm data obtained from the 

first well. Reduced data collection should be employed for all subsequent wells 

on the site, since adequate will exit from these early wells for the storage 

operator and EPA to make a detailed assessment of the capability of the site. 

This idea is similar to many approaches on ‘greenfield’ sites followed via Class 

I well Permitting by EPA. A secondary approach is for the operator to include 

this data acquisition into their project costs for stratigraphic test data, 

cores, logs, pressures, reservoir testing to demonstrate the suitability of the 

injection and confining horizons. The burden 

Response: EPA agrees and 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 acknowledges that early pilot projects may focus on gathering data to inform GS technology.

However, EPA believes that a detailed geological site characterization of every GS site (as 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 adds that, if data on a formation or site collected in

connection with an earlier project can support a geologic characterization, the Director has discretion

to accept this data, provided it is sufficient to demonstrate site suitability.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23280

Comment: Capillary pressure is difficult to measure outside a lab and would not be 

available if no wells have been drilled in a project. Do not see necessity for 

128
this information. 

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).

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24869

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment) 

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. 

129
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 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.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24871

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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: 

(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. 

130
(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.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24872

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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; 

(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 

131
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).

Commenter Name: Cynthia Lane Letter ID: 0528

Commenter Organization: American Water Works Association (AWWA) Comment ID: 21387

Other EPA Comment Codes and Descriptions: 3110 2.1.1 Proposed siting requirements (i.e.,

injection/confining zones, trapping mechanism) 

Comment: provide for a consistent application of the monitoring requirements. Another 

area of concern is often the lack of good records of abandoned wells that tap 

the very same strata used for carbon dioxide sequestration. There is a 

presumption that even states with oil and gas or mining operation have 

excellent, up to date reports and have maps indicating abandoned wells and 

mines. This is not always the case. Many states with extractive industries do 

have maps and surveys, but they are not sufficiently precise for geologic 

sequestration. Studies have shown that injected carbon dioxide will be able to 

find the abandoned wells. These wells allow for the transmission of the carbon 

dioxide out of the confined aquifer into potential USDW's and then eventually to 

the surface. 

Response: EPA acknowledges that areas previously used for drilling for oil, gas, or minerals pose

potential challenges for GS. However, regardless of the history of the site, the owner or operator

must provide to the Director extensive information demonstrating the adequacy of the site to contain

the CO2 (§146.82). This information includes the location of all existing or abandoned wells within

132
the modeled AoR (§§146.82(a)(2) and 146.84(c)(2)) and the location, orientation, and properties of

all known or existing faults (§146.82(a)(3)(ii)). The Director may require ground or airborne surveys

to identify active or abandoned wells if there is reason to believe, based on knowledge of the site or

of available data bases, that the available information is not adequate for assessing a proposed GS

site (§146.84(c)(2)). The Director may also require additional surveys and tests to identify and

characterize fractures. After reviewing the permit information submitted, the Director may deny the

application if there is reason to believe that USDWs may be endangered.

Comment Code: 3140 2.1.4 Comments that the proposed geologic data requirements are too

stringent 

Individual Comments

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23460

Other EPA Comment Codes and Descriptions: 1210 1.1.1 Comments about the proposed rule 

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 (§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.

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23465

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Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2

movement 

Comment: • The Final Rule must not make the application process overly burdensome or 

unrealistic by requiring detailed information that may not be available at the 

time of the initial application; instead, the Final Rule should allow for 

submission of updated information regarding a CO2 GS well and its AoR as that 

information becomes available. 

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, §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.

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23501

Comment: For example, some requirements for information related to geologic structure and 

hydrogeologic properties of the proposed storage site and overlying formations 

may be unavailable until drilling commences, including "data on the depth, areal 

extent, thickness, mineralogy, porosity, permeability and capillary pressure ... 

geologic cores, outcrop data, seismic surveys, ... and lithologic descriptions" 

of the injection and confining zones (proposed § 146.82(d)(4)) and 

"geomechanical information on fractures, stress, ductility, rock strength, and 

in situ fluid pressures within the confining zone" (proposed § 146.82(d)(5)). 73 

Fed. Reg. at 43536. While some of this information may be available during the 

permit application process, other details will be unavailable prior to drilling. 

To require detailed information that may either be unreliable, because it is 

based on unrealistic or unfounded predictions, or may simply be unavailable 

could delay the permitting process and have an overall chilling effect on CO2 GS 

projects. EPA should craft these requirements with flexibility and require in 

the initial permit application only that information which is necessary to 

determine whether issuance of a Class VI permit is appropriate. Submission of 

additional information as it becomes available - whether through well drilling, 

construction, operation, reevaluation, or corrective action - will allow for 

more reliable data that will in turn ensure greater protection of USDWs. 

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

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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.

Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23621

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit

information (40 CFR 146.82) 

Comment: (d) (4) (5) 

This section calls for data that is almost certainly incompletely available and 

cannot be acquired except from a permitted well. Geomechanical information on 

the confining zone almost certainly will not exist until storage projects have 

been completed in a basin. There is no economic motive to develop such data. 

Acquiring a representative and accurate in situ fluid pressure in a confining 

zone may be impossible given that a confining zone should not be permeable and 

therefore its testing with wireline or drillstem tools is highly questionable. 

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.

EPA adds that the presence or absence of an economic motive for generating the data is outside the

scope of the rulemaking. The owner or operator must submit all of the data required at §146.82 in

order to support a determination about the suitability of the site, regardless of an economic incentive

for gathering that data. 

135
Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23622

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit

information (40 CFR 146.82) 

Comment: (g) 

Reference is made to geochemical data on subsurface formations with no 

indication of which formation or how many. This could be interpreted to mean all 

formations within the sedimentary column both above and below an injection zone 

at a given site. Much of such data may be both irrelevant and unavailable and it 

will be extremely costly to core and sample every formation in the area of a 

proposed site. 

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. 

EPA clarifies that 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 clarifies that operators would not necessarily need to core and sample each formation in the

area of a proposed GS site. If relevant, comprehensive information about the site exists (e.g., from

earlier geologic studies of the area), the Director may, at his/her discretion, allow its use in the site

characterization for the GS project. In addition, §146.87(b) allows 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,

cores of injection zones and confining zones, and samples of formation fluids must be submitted.

§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 adds that §146.87(b) allows the owner or operator to submit whole cores or sidewall

cores of the injection zone and confining system.

Additionally, EPA acknowledges comments regarding the costs associated with thoroughly

evaluating a potential GS site. The Agency believes the requirements for a thorough geologic site

characterization for a GS project are necessary to protect USDWs from endangerment. 

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24330

Other EPA Comment Codes and Descriptions: 3110 2.1.1 Proposed siting requirements (i.e.,

injection/confining zones, trapping mechanism) 

Comment: 1. Site Evaluation 

136
The preamble appears to suggest the need for an elaborate evaluation of site 

conditions to address concerns related to seismicity and potential geochemical 

interactions. In fact, however, seismicity and geochemical impacts are issues 

that are easily addressed in the GS context, and requirements for unnecessarily 

elaborate analysis would serve only to burden and impede the development of GS 

projects. 

Concerns with respect to seismicity are frequently raised in the injection well 

context, but there is ample experience demonstrating that such risks are modest 

and easily addressed through appropriate injection pressure limitations. 

Similarly, geologic compatibility - while it can present issues in some contexts 

- is unlikely to present any serious problems in the GS context. These 

conclusions are confirmed by decades of experience with literally thousands 

Class II CO2 injection wells injecting hundreds of millions of tons of CO2. 

The apparent extent of concern about geochemical compatibility is particularly 

hard to understand. Although it is true that injection of CO2 can be expected to 

lead to the formation of carbonic acid, the resulting carbonic acid is only 

weakly corrosive and - as experience with the injection of extremely corrosive 

hazardous wastes demonstrates - cannot reasonably be expected to cause any 

breach of containment that would endanger a USDW. The proposed rule expresses 

specific concern about geochemical reactions that could alter the composition of 

the injected CO2 stream - particularly through the mobilization of contaminants 

that occur naturally in the injection zone - but such concerns are essentially 

immaterial because the specific composition of the CO2 stream matters little as 

long as the CO2 stream remains confined. 

Response: The Agency believes that the site characterization requirements at §146.82 are essential

to proper siting of a GS well and are the foundation for a detailed understanding of the local and

regional geology. Collecting and evaluating geochemical data in and around the CO2 injection zone,

as required in §146.82(a)(6), serves several purposes. This baseline geochemical data can help

predict geochemical reactions between the injectate, reservoir geology, and formation fluids. Such

reactions can lead to dissolution and precipitation of minerals which affect formation porosity,

which in turn can affect required injection pressure (Sminchak and Gupta, 2002) and transport of

fluid within the formation. While the confining layer is the primary barrier to CO2 movement into a

USDW, multiple barriers are important and changes in injection pressure and fluid movement may

compromise those barriers. An increase in injection pressure due to reduced porosity, in particular,

can lead to fracturing of the confining layer and potentially allow fluid movement outside of the

injection zone. Losses in injectivity because of geochemical reactions may also require additional

injection wells and further penetrations in the confining layer that can become pathways for fluid

migration. 

EPA disagrees with the comment that the composition of the CO2 stream is not important.

Information about the composition of the CO2 stream informs decisions about the appropriate design

and construction of the well, the potential for adverse mineral reactions in the subsurface geologic

formations, and appropriate testing and monitoring parameters. 

EPA disagrees that injectivity is not an important consideration. While increasing storage capacity is

not the intent of the UIC requirements, EPA believes that maximizing the amount of CO2 that can

137
be injected through a single well may reduce the need for additional injection wells, which reduce

the potential for unacceptable fluid movement and improve USDW protection from endangerment. 

Finally, 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. 

Commenter Name: John King Letter ID: 0211

Commenter Organization: Shell Exploration and Production Company

(SEPCo)

Comment ID:

22764

Comment: A. Geologic Siting Requirements 

The preamble to the proposed rule outlines normal site selection criteria for 

injection well projects, including the need to identify an injection zone with 

sufficient permeability, porosity, thickness and lateral extent and a lowpermeability confining zone with sufficient thickness and lateral extent to 

protect overlying USDWs. 73 Fed. Reg. at 43505. These are familiar and 

appropriate requirements, and they appear to be appropriately embodied in the 

regulatory text proposed for codification at 40 C.F.R. 146.83(a). Unfortunately, 

the preamble goes on to suggest the need for extraneous detail in the evaluation 

of site conditions. In addition, the rule text proposed for codification at 40 

C.F.R. 146.83(b) would allow the Administrator apparently unlimited discretion 

to impose additional siting requirements that go beyond those necessary to 

ensure protection of USDWs. 

Recommendation: 

EPA should omit the latter requirement of extraneous details, and instead seek 

to develop clear performance standards as detailed in the American Petroleum 

Institute’s submission regarding site characterization. The need for adequate 

site characterization cannot be understated, however it’s is critical that EPA 

works to clarify the site evaluation needs and ensure that they are no more 

elaborate than necessary to ensure protection of USDWs. 

1. Site Evaluation 

The preamble appears to suggest that there may be a need for an elaborate 

evaluation of site conditions to address concerns related to seismicity and 

potential geochemical interactions. In fact, however, seismicity and geochemical 

compatibility are issues that are easily addressed in the GS context, and 

requirements for unnecessarily elaborate analysis would serve only to burden and 

impede the development of GS projects. 

Concerns with respect to seismicity are frequently raised in the injection well 

context, but there is ample experience demonstrating that such risks are modest 

and easily addressed through appropriate injection pressure limitations. 

138
Similarly, geologic compatibility -- while it can present issues in some 

contexts -- is unlikely to present any serious problems in the GS context. These 

conclusions are confirmed by decades of experience with thousands of Class II 

CO2 injection wells injecting hundreds of millions of tons of CO2. 

While it is true that injection of CO2 can be expected to lead to the formation 

of carbonic acid, the resulting carbonic acid is only weakly corrosive and -- as 

experience with the injection of extremely corrosive hazardous wastes 

demonstrates -- cannot reasonably be expected to cause any breach of containment 

that would endanger a USDW. The proposed rule expresses specific concern about 

geochemical reactions that could alter the composition of the injected CO2 

stream -- particularly through the mobilization of contaminants that occur 

naturally in the injection zone -- but such concerns are immaterial because the 

specific composition of the CO2 stream matters little as long as the CO2 remains 

confined. Another theoretical concern relates to the potential for geochemical 

changes to contribute to the plugging of pore spaces in the injection zone. 

However, experience with Class II CO2 injection confirms pore plugging should 

not pose any practical problems in the CO2 injection context because of the 

relative weakness of carbonic acid and the time and transport distance required 

for carbonic acid to form and for any subsequent geochemical changes to occur. 

Even if pore plugging were to manifest it, it would occur deep in the injection 

zone where its effect would be minimal. In any event, the impact of pore 

plugging would only be to decrease permeability in the injection zone, thereby 

reducing the efficiency (but not the safety) of the injection operation. 

In short, geochemical changes related to CO2 injection cannot be expected to be 

material to the protection of USDWs. Accordingly, there is no credible basis for 

the suggestion (73 Fed. Reg. at 43505) that "[s]tudies of rock samples and 

review of geochemical data from monitoring wells are needed to evaluate the 

impact" of potential geochemical changes related to CO2 injection. 

Recommendation: 

Remove requirements for detailed analysis of potential chemical or mineralogical 

reactions that are unnecessary to ensure protection of USDWs. 

Response: The Agency believes that the site characterization requirements at §146.82 are essential

to proper siting of a GS well and are the foundation for a detailed understanding of the local and

regional geology. Collecting and evaluating geochemical data in and around the CO2 injection zone,

as required in §146.82(a)(6), serves several purposes. This baseline geochemical data can help

predict geochemical reactions between the injectate, reservoir geology, and formation fluids. Such

reactions can lead to dissolution and precipitation of minerals which affect formation porosity,

which in turn can affect required injection pressure (Sminchak and Gupta, 2002) and transport of

fluid within the formation. While the confining layer is the primary barrier to CO2 movement into a

USDW, multiple barriers are important and changes in injection pressure and fluid movement may

compromise those barriers. An increase in injection pressure due to reduced porosity, in particular,

can lead to fracturing of the confining layer and potentially allow fluid movement outside of the

injection zone. Losses in injectivity because of geochemical reactions may also require additional

injection wells and further penetrations in the confining layer that can become pathways for fluid

migration. 

139
EPA disagrees with the comment that the composition of the CO2 stream is not important.

Information about the composition of the CO2 stream informs decisions about the appropriate design

and construction of the well, the potential for adverse mineral reactions in the subsurface geologic

formations, and appropriate testing and monitoring parameters. 

EPA disagrees that injectivity is not an important consideration. While increasing storage capacity is

not the intent of the UIC requirements, EPA believes that maximizing the amount of CO2 that can

be injected through a single well may reduce the need for additional injection wells which reduce the

potential for unacceptable fluid movement and improve USDW protection from endangerment. 

Finally, EPA disagrees that any of the requirements for detailed analysis of potential chemical or

mineralogical reactions are unnecessary to ensure protection of USDWs from endangerment. EPA

believes that information on the mineralogy of the injection and confining zones (required at

§146.82(3)(iii)), can help predict geochemical reactions between the injectate, reservoir geology, and

formation fluids. Such reactions can lead to dissolution and precipitation of minerals which can

affect formation porosity and injectivity, and in turn can affect required injection pressure (Sminchak

and Gupta, 2002) and transport of fluid within the formation. 

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. 

Commenter Name: Dennis R. James Letter ID: 0214

Commenter Organization: North American Coal Corporation (NAC) Comment ID: 22962

Comment: 1. Proposed Geologic Siting Requirements 

The proposed rule would require maps, cross sections, and geochemical data on 

all USDWs near an injection well. This requirement could be extremely 

burdensome to the operator, requiring significant work without any additional 

benefit. In many areas, near surface USDWs are very complex systems without 

much existing data. Obtaining the required data on these shallow USDWs would 

take significant time, money, and resources, and the interpreted data would have 

no impact on the injection well’s construction or operation. Defining the 

lowermost USDW sets a boundary condition for an injection well, everything above 

which would be protected. 

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 (§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

140
common to all injection well classes.

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the

University of North Dakota

Comment ID:

21610

Comment: Page 43505. 1. Proposed Geologic Siting Requirements 

With regard to the need for data on all USDWs at a site: 

Wording here suggests that maps and cross sections must be generated of all 

USDWs near the proposed injection well. Submitting maps and cross sections of 

all of the USDWs, not just the lowermost USDW, seems unnecessarily burdensome to 

the owner/operator. Such maps will require significant additional work, and it 

is not clear how doing so will result in improved protection of USDWs since 

protective casing is already required from the surface all the way to the bottom 

of the lowermost USDW. Identifying and mapping the lowermost USDW should be 

sufficient to protect all overlying USDW zones. 

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 (§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.

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the

University of North Dakota

Comment ID:

21612

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards) 

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 

141
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 

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).

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the

University of North Dakota

Comment ID:

21631

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit

information (40 CFR 146.82) 

Comment: Page 43536. § 146.82 Required Class VI permit information. There are numerous 

requirements for information on formations overlying the proposed storage site. 

Requirements should be flexible and site-specific. The required information 

should be limited to relevant primary and/or secondary seals and be used to 

document the vulnerability or lack thereof of any USDWs in the area. 

142
Response: 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).

Commenter Name: Neeraj Gupta Letter ID: 0229

Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21829

Comment: Page 63, Geochemical Data- The proposed requirements ask for geochemical data on 

injection zone, confining zone, any underground source of drinking water, and 

any other important zone. This may be a burdensome amount of information for GS 

sites. While some indication of geochemical parameters may be obtained from 

wireline methods, it can be a challenge to collect representative brine samples, 

especially from low permeability caprocks and deep saline formations. It is 

very unlikely we would even be able to collect samples from many low 

permeability confining layers. In addition, no guidance on the list of analytes 

(i.e. cations, anions, metals, physical parameters) is provided. We would 

suggest that data from regional studies and other deep wells also be allowed as 

an alternative for defining the geochemical setting. 

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 clarifies that if recent information about the site exists (e.g., from other

geologic studies of the area), the Director may, at his/her discretion, allow its use in the site

characterization for the GS project.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23281

Comment: 146.82(g) Baseline geochemical data on subsurface formations is too broad. 

143
Should be limited to the injection zone, confining zones, and possibly the next 

porous and permeable zone above the upper confining zone. 

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).

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission

Associates

Comment ID:

22242

Comment: – EPA needs to build a practical realism into the site characterization UIC 

regulatory requirements under the SWDA. The current rule proposal is so 

"demanding" it may preclude many otherwise eligible geological storage sites. 

The site characterization and related requirements for permitting a UIC well 

present a very large list of extremely detailed potential impact issues that by 

themselves may be frightening to members of the public. This evaluative process 

needs to be pared down to those most critical few factors that assure the 

greatest degree of safety for each unique UIC for CO2 GS site. WEST members do 

not want to see development of a regulatory program that gets so bogged down 

that it goes no further than the nuclear waste storage siting fiasco in the US 

(e.g., the Nevada nuclear storage site is still not approved by the state and is 

caught up in unrealistic public fear and political concerns). If this happens to 

UIC for CO2 GS siting, it could stop the coal fired power plant industry if CCS 

becomes one of a very few limited options for CO2 emissions abatement required 

under a GHG legislative or regulatory program. 

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

144
unique nature of injecting large volumes of CO2 into a variety of geological formations for longterm storage. 

EPA adds that the GS rule does not address the use of coal-fired power plants; instead 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 (§146.83(b)),

based on his or her understanding of a particular site. 

To the comment comparing the GS siting requirements to nuclear waste storage siting requirements,

EPA clarifies that the two activities are very different, and while it is out of the scope of the GS

rulemaking to comment on the stringency of nuclear waste siting requirements, EPA stresses that the

site characterization requirements for GS wells 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: Dianna Tickner Letter ID: 0262

Commenter Organization: Peabody Energy Comment ID: 22993

Comment: Class II EOR wells to permanent CO2 storage wells. As proposed, the site geology 

requirements seem to be unduly burdensome without any real additional safety 

benefit to underground sources of drinking water. Site geology should be 

considered on a case by case basis to prevent the categorical elimination of 

sites which may be technically acceptable. 

Response: EPA disagrees that the requirements at §146.82 are unnecessary and unduly burdensome

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. 

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).

Commenter Name: Mark Vickery Letter ID: 0280

Commenter Organization: Texas Commission on Environmental Quality Comment ID: 24099

Comment: (a) The proposed requirement that an application for Class VI well permit 

include baseline geochemical data on subsurface formations including all 

underground sources of drinking water (USDWs) in the area of review is 

unnecessarily burdensome, considering that this could entail sampling of 

numerous individual sands throughout thousands of feet of geologic section. 

145
USDWs in Texas may extend to depths of 4,000 feet or more, and in some regions 

of the U. S., even deeper. Baseline determinations for local aquifers in a CO2- 

GS project should focus on those immediately overlying CO2 confining zones, 

lowest USDWs, and any other USDWs of significance. 

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).

Regarding concerns about deep USDWs, 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.

Comment Code: 3150 2.1.5 Comments on required permit information (40 CFR 146.82) 

Individual Comments

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24765

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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.} 

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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.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24766

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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.

Commenter Name: John Hanger Letter ID: 0130

Commenter Organization: Pennsylvania Dept. of Env. Protection Comment ID: 21501

Comment: Proposed Class VI Permit Requirements 

-The permit applicant (owner/operator) for a proposed UIC Class VI well must 

demonstrate in the permit application that he owns the right to inject the CO2 

into the property and that his ownership extends to the entire area to which the 

CO2 may migrate. 

-Section 146.82 sets forth the information which the owner or operator must 

submit 

"(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... 

Only information of public record is required (emphasis added) to be included on 

this map;...." 

While it may be prudent to show only public information, it is also easy to 

avoid the aggravation of a diligent search by requiring that only public 

information is shown. This should not relieve the permittee from sharing any 

confidential information about the area, the subsurface conditions, the 

potential adjoining landuse, etc. Regulations should require full and complete 

disclosure of all information known, even if a confidential submittal is 

required. 

-It is possible that the owner/operator would be required to obtain information 

147
from neighboring non-owners in order to meet the requirements identified in the 

permit requirement and or area of review sections. EPA should identify the means 

by which Class VI owners/operators can obtain this information. This point is 

especially relevant to the inclusion of ‘buffer zones’ (see comments on the Area 

of Review) and the need to obtain site-specific information about these buffers. 

Response: EPA clarifies that land and pore space ownership issues are outside the scope of the GS

regulation and disagrees that it is necessary that the owner or operator of a GS site own the entire

area to which the CO2 may migrate. EPA does believe, however, that it is important that the owner

or operator have surface access to wells that require corrective action and for all necessary testing

and monitoring during the life of the project. For this reason, the GS rule requires owners or

operators to demonstrate that they will have access for these activities in the AoR and corrective

action plan at §146.84(b) and testing and monitoring plan (§146.90).

EPA acknowledges that information beyond publically available data may be needed to accurately

assess the suitability of a site for GS. 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 sitespecific and based on knowledge of the site, data availability, and data quality. The Director has the

discretion to require the owner or operator to supplement publically available data if there is reason

to believe that the incompleteness of available information could compromise USDW protection

from endangerment. 

In response to the comment suggesting that some of the required information may be available from

neighboring land owners, EPA replies that if relevant information about the site exists (e.g., from

earlier geologic studies of the area) and is available and the owner of that information is willing to

share it, the Director may, at his/her discretion, allow its use in the site characterization for the GS

project. 

Commenter Name: Brianne Metzger Letter ID: 0151

Commenter Organization: Spectra Energy Corp Comment ID: 21823

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for

permit applications (seeking comment) 

Comment: E. EPA Should Not Make The Permitting Process Overly Burdensome By Requiring 

Unnecessary Or Unavailable Data. 

Under the proposal, EPA is requiring the collection and submission of a 

significant amount of information and data. Although we understand and support 

the need for certain baseline data to support the determination that a 

particular project location is suitable, in certain cases, some of the data 

that EPA is requiring is irrelevant, excessive, or may even be unavailable. 

Therefore, we would recommend that the Agency include a provision in the Final 

GS Rule that would provide a waiver process and criteria, whereby the Director 

could waive certain data requirements, where such requirements are unnecessary. 

Response: EPA disagrees that any of these protective requirements are unnecessary, and believes

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 (§146.83(b)), based on his or her understanding of a particular site. 

148
EPA believes that a detailed 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 geologic formations for long-term storage.

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. 

Commenter Name: Brianne Metzger Letter ID: 0151

Commenter Organization: Spectra Energy Corp Comment ID: 21825

Comment: EPA has also included a requirement that the permit applicant include a 

"proposed formation testing program to obtain an analysis of the chemical and 

physical characteristics" of the injection and confining zone. 40 C.F.R. § 

146.82(j). A permit applicant is already required to submit the underlying 

data as part of the permit application process, and it appears that this 

requirement is unnecessary and duplicative. Therefore, we request further 

clarification regarding the intent and scope of this formation testing program. 

Spectra generally supports the requirement for the "proposed stimulation 

program" to ensure that stimulation activities will not interfere with 

containment. 40 C.F.R. § 146.82(k). We believe it is important that EPA 

monitor stimulation activities of third parties to ensure that such activities 

not interfere with or damage the containment integrity of other GS operations 

or natural gas storage reservoirs. 

Response: The formation testing plan must be approved before the owner or operator can generate

necessary data on the compatibility of the CO2 stream with fluids in the injection zone and minerals

in both the injection and the confining zone. In response to comments and based on an evaluation of

the proposed requirements, EPA revised subpart §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)). 

Additionally, EPA agrees that it is important that the Agency, as manager of the national UIC

Program, understand how various aspects of GS projects, including stimulation activities, are

proceeding, and that operators performing well stimulation activities are not endangering USDWs.

EPA plans to, every six years, collect and review project data on early GS projects, including site

characterization, operational, monitoring, and modeling 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.

149
Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality

(MDEQ)

Comment ID:

22123

Comment: 146.82 (b): MDEQ suggests that the information requirements not be limited to 

public records only. The area ofreview should be surveyed completely and all 

information shown on a map. 

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. EPA acknowledges

that maps are probably the most appropriate method for presenting the required information. 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.

Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality

(MDEQ)

Comment ID:

22124

Comment: 146.82 (e): MDEQ suggests that the tabulation of wells within the area of review 

not be limited to only those that penetrate the injection or confining zone(s). 

Identifying all perforations will allow for complete public involvement and 

identification of areas of risk should the plume move upward. 

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. 

EPA believes that limiting this inventory effort to those wells that penetrate the confining zone is

appropriate, because the confining zone, by definition, acts as a barrier to the fluid movement that

could endanger a USDW.

Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality

(MDEQ)

Comment ID:

22125

Comment: 146.82 (g) : MDEQ suggests that this rule be more specific to include 

geochemical data collection for the injection formation and the confining zone 

directly above the injection zone. 

Response: The Agency believes that the requirement at §146.82(a)(6) to submit baseline

150
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.

Commenter Name: Steven Pirner Letter ID: 0153

Commenter Organization: South Dakota Department of Environment and

Natural Resources

Comment ID:

22141

Comment: 144.18 Requirements of Class VI wells - owners must get a permit versus ruleauthorization - much more detailed application, and has/allows for public input. 

We are in agreement with this. 

Response: EPA acknowledges the comment and the final rule retains the requirement as proposed.

Commenter Name: Steven Pirner Letter ID: 0153

Commenter Organization: South Dakota Department of Environment and

Natural Resources

Comment ID:

22144

Comment: 146.82 Required Class VI permit information - (e) ".... and any additional 

information the Director may require:" - this is good part, as we as a state 

have had numerous occasions when operators do not submit all of the information 

needed to determine the viability of an application for a well because it is not 

specifically listed in the state regulations 

Response: The Agency believes that providing the Director discretion to request additional

information 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.

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23769

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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, 

deep stratigraphic boreholes, State or EPA approved subsurface cleanup sites, 

151
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.

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23770

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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.

Commenter Name: Michael J. Miller Letter ID: 0168

Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22493

Other EPA Comment Codes and Descriptions: 4660 2.6.6 Geochemical monitoring 

Comment: Preamble, page 43505, §146.82(g), and § 146.90(d): "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 

152
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." 

EPRI COMMENT #3A: EPA does not provide the technical justification for 

collecting geochemical data from all zones, geologic formations and USDWs. We 

believe the collection of data should be limited to zones needed to demonstrate 

system performance defined by the minimum siting criteria specified in 

§146.83(a)(1) and (a)(2). EPRI believes that system performance with the end 

goal of protecting USDW can be achieved by collecting geochemical data from a 

maximum of four zones for the reasons provided below: 

1) Injection zone -- during site characterization, check for conditions that 

could lead to CO2-induced rock dissolution, potentially resulting in formation 

and injection well collapse (well integrity); 

2) Primary confining zone -- during site characterization, check for conditions 

that could lead to caprock dissolution and degradation, potentially resulting in 

loss of CO2 containment with subsequent CO2 movement through the primary barrier 

(caprock integrity); 

3) Monitoring zone -- a zone proposed by the applicant and approved by the EPA 

where performance monitoring is required to take place in accordance with 

§146.90(d). The monitoring zone would lie between the primary confining zone and 

the USDW. It would be the only zone sampled on a routine schedule during CO2 

injection operations and closure to detect the leakage of CO2 through the 

primary confining zone (performance monitoring) as noted ; and 

4) USDW zone -- during site characterization, collect optional samples at or 

near the closest USDW boundary to the injection zone to establish baseline water 

quality. 

EPRI COMMENT #3B: Before promulgating the rule, a comprehensive study of deep 

well fluid sampling techniques needs to be performed to ensure that the 

techniques cited by EPA consistently produce samples that are representative of 

deep reservoir conditions. Otherwise, interpretation of geochemical data derived 

from methods producing inconsistent or non-representative sample data could 

result in erroneous conclusions, including unnecessary or inappropriate 

corrective action. Collecting representative deep well samples from confining 

zones is especially challenging (see EPRI comment #14). 

Response: The GS regulation, at §146.82(a)(6), requires the owner or operator to submit baseline

geochemical data on subsurface geologic formations. 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 believes that the necessary sampling techniques are available, and is developing guidance on

153
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.

On the topic of sampling, EPA recognizes that the collection of representative ground water samples

from depth poses challenges and that special methods, such as U-tubes, will be needed to preserve

the integrity of such samples. 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.

Regarding the comment about the technical justifications and difficulty of sampling within the

confining zone, EPA clarifies that §146.90(d) requires owners and operators to monitor ground water

quality and geochemical changes above the confining zone(s), rather than within the confining zone.

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23407

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for

permit applications (seeking comment) 

Comment: · The Final Rule must not make the application process overly burdensome or 

unrealistic by requiring detailed information that may not be available at the 

time of the initial application; instead, the Final Rule should allow for 

submission of updated information regarding a CO2 GS well and its AoR as that 

information becomes available through phased corrective action. 

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.

The final rule requires for the submission of updated information on the well and its AoR. The final

154
GS rule, at §§146.84(c) and §146.90(j) requires owners or operators to review and update the AoR

and corrective action plan and the testing and monitoring plan, at least once every 5 years,

throughout the life of the project. Owners or operators must review each plan and identify necessary

modifications 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. While

the rule does not specify that changes in phased corrective action warrant an update, the Director

may determine that these types of modifications need to be incorporated into a plan update. EPA is

developing guidance on developing and updating the GS project plans, which includes recommended

considerations for developing and updating the plans. This guidance will be available on EPA’s

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24120

Other EPA Comment Codes and Descriptions: 1210 1.1.1 Comments about the proposed rule 

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.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24155

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 

155
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 application. The guidances can be found on EPA’s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23845

Comment: B. PERMIT APPLICATION REQUIREMENTS 

EPA proposes to require owners and operators to submit relevant site information 

to the permitting authority for consideration of permit applications, including: 

maps of the injection wells, the AoR as determined through computational 

modeling, all artificial penetrations within the AoR, maps of the general 

vertical and lateral limits of USDWs, maps of the geologic cross sections of the 

local area, the proposed operating data and injection procedures, proposed 

formation testing program, and stimulation program, well schematics and 

construction procedures, and contingency plans for shut-ins or well failures. 

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Some of the data that EPA proposes to require is irrelevant, excessive, or in 

some cases unavailable. Therefore, the CCS Alliance recommends that EPA ensure 

that any required data is necessary to the ultimate goals of the Proposed Rule. 

For example, artificial penetrations several formations above the injection zone 

may have little relevance to the GS operation. Similarly, the CCS Alliance 

recommends including a provision in the final rule providing the Director 

discretion to waive certain data requirements, where such requirements are 

unnecessary, or require that the data be updated as it is collected or becomes 

available. 

EPA is proposing that an applicant include "baseline geochemical data on 

subsurface formations, including all USDWs in the area of review."" The 

Proposed Rule is not clear as to how much baseline data EPA is expecting the 

permit applicant to generate and collect from additional drilling or testing of 

the injection zone and all other zones. Given the likely depth of many of the GS 

wells through many strata, this could involve a large number of different 

formations above the injection zone. EPA should limit the baseline geochemical 

data to information regarding the next porous formation above the injection 

zone. Similarly, EPA should clarify that the permit applicant may rely upon 

secondary sources (such as other drilling or geologic records) that relate to 

and support the data requirement. EPA also should clarify whether its expects 

applicants to test private wells, where permission is granted, within the AoR 

for purposes of establishing baseline data. 

[FN44] 40 C.F.R. $ 146.82(g). 

EPA also has included a requirement that the permit applicant include a 

"proposed formation testing program to obtain an analysis of the chemical and 

physical characteristics" of the injection and confining zone." A permit 

applicant is already required to submit the underlying data as part of the 

permit application process, and it appears that this requirement is unnecessary 

and duplicative. Therefore, the Alliance requests further clarification 

regarding the intent and scope of this formation testing program. 

[FN45] 40 C.F.R. $ 146.82(j). 

EPA should monitor stimulation activities of third parties to ensure that such 

activities not interfere with or damage the containment integrity of other GS 

operations or natural gas storage reservoirs. The CCS Alliance, therefore, 

generally supports the requirement for the "proposed stimulation program" to 

ensure that stimulation activities will not interfere with containment. [FN46] 

[FN46] 40 C.F.R. 9 146.82(k). 

EPA has proposed requiring the applicant to submit "the status of corrective 

action on wells in the area of review."[FN47] The CCS Alliance does not believe 

it is necessary to require the inclusion of all wells within the AoR regardless 

of whether or not they penetrate the injection zone. There could be many shallow 

wells within the AoR located hundreds or thousands of feet above the CO2 

injection zone. Therefore, EPA should limit this requirement to the injection 

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zone, injection pool, and only those wells that either intersect or penetrate 

the proposed reservoir, the cap rock, and possibly the porous strata directly 

above the injection zone. 

[FN47] 40 C.F.R. $ 146.82(q). 

On a related matter, EPA has stated that only information of public record 

pertaining to all types of wells (injection. producing, abandoned) be included 

on the AoR. Data availability and use raises a question regarding the possible 

existence of other data which might be private, proprietary, and/or not publicly 

available. Such non-publicly available data may or may not be relevant to the 

application process. The CCS Alliance requests EPA to clarify to what extent an 

applicant would be expected to develop or use information not contained in the 

public record. 

EPA also proposes that permit applications for GS sites include several plans 

not currently required under existing UIC regulations, including (1) a 

monitoring and testing plan; (2) an AoR and corrective action plan; (3) a well 

plugging plan: and (4) a post-injection site care and site closure plan. The CCS 

Alliance questions whether it is necessary for each plan to be submitted 

contemporaneously with the permit application. The up-front gathering and 

submission of such detailed information would be costly and time-consuming. We 

recommend requiring the submission of such plans only upon approval of an 

initial permit application, with further approvals contingent upon the 

successful completion, submission, and approval of the required plans. The 

initial permit application could provide general information regarding the 

specific plans to be submitted later. Such a process will provide sufficient 

information for EPA to make an initial permitting decision. 

As part of the permitting process, EPA should require that owners and operators 

establish a plan to ensure that resource development may occur in other geologic 

strata within or near the AoR. CCS will be a critical technology, but also 

critical to the nation are energy resources and mineral reserves. Companies may 

have made considerable investment in purchasing, identifying and characterizing 

these resources. This value should be protected as GS sites are selected and 

developed. EPA's proposed rule at present does not address this issue. 

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 longterm storage. 

EPA recognizes that some of 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)).

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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 (§146.83(b)), based on his or her understanding of a particular site. 

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 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. 

In response to the comment that EPA should require that owners or operators establish a plan to

ensure that resource development may occur in other geologic strata within or near the AoR, the

Agency clarifies ensuring protection of resource rights including mineral, water, and energy resource

development rights is outside the scope of this rulemaking. 

In conducting GS site characterization, the Agency anticipates that the owner or operator would

consider the proximity of and implications that a GS project may have on other activities in the

AoR. However, the purpose of the requirements is to ensure that Class VI GS well is constructed,

operated, monitored, and closed in a manner that is protective of USDWs.

Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23619

Comment: 146.82 

Much of this section assumes that data are available from an injection well, 

such as the data referred to in (c) from logging and testing of "the well." The 

reality is that such a well will not be drilled until the permit is received, so 

specific data, especially for a saline reservoir that has not been a hydrocarbon 

producer or gas storage unit elsewhere in its depositional basin, likely will 

not exist. 

159
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.

EPA clarifies that operators would not necessarily need to core and sample each formation in the

area of a proposed GS site. If relevant, comprehensive information about the site exists (e.g., from

earlier geologic studies of the area), the Director may, at his/her discretion, allow its use in the site

characterization for the GS project. In addition, §146.87(b) allows 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,

cores of injection zones and confining zones, and samples of formation fluids must be submitted.

§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 adds that §146.87(b) allows the owner or operator to submit whole cores or sidewall

cores of the injection zone and confining system.

Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23620

Comment: (d) (2) 

The entire discussion of faults is problematic here and elsewhere. Faults may be 

sealing, as in the case of many hydrocarbon traps, or they may be transmissive, 

especially in tensional stress regimes. In compressive regimes, and if similar 

faults form hydrocarbon trap boundaries, faults are more likely to be sealing, 

but cannot be conclusively stated as such from inferential data. 

Response: EPA 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. 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. At sites

where deep faults (even with little or no surface expression) are present, processing and interpreting

data from multiple geophysical sensing methods has been shown to detect faults better than analysis

160
of data from individual methods (Goussev et al, 2004). 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.

Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23621

Other EPA Comment Codes and Descriptions: 3140 2.1.4 Comments that the proposed geologic

data requirements are too stringent 

Comment: (d) (4) (5) 

This section calls for data that is almost certainly incompletely available and 

cannot be acquired except from a permitted well. Geomechanical information on 

the confining zone almost certainly will not exist until storage projects have 

been completed in a basin. There is no economic motive to develop such data. 

Acquiring a representative and accurate in situ fluid pressure in a confining 

zone may be impossible given that a confining zone should not be permeable and 

therefore its testing with wireline or drillstem tools is highly questionable. 

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.

EPA adds that the presence or absence of an economic motive for generating the data is outside the

scope of the rulemaking. The owner or operator must submit all of the data required at §146.82 in

order to support a determination about the suitability of the site, regardless of an economic incentive

for gathering that data. 

Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23622

Other EPA Comment Codes and Descriptions: 3140 2.1.4 Comments that the proposed geologic

data requirements are too stringent 

Comment: (g) 

Reference is made to geochemical data on subsurface formations with no 

indication of which formation or how many. This could be interpreted to mean all 

formations within the sedimentary column both above and below an injection zone 

161
at a given site. Much of such data may be both irrelevant and unavailable and it 

will be extremely costly to core and sample every formation in the area of a 

proposed site. 

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. 

EPA clarifies that 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 clarifies that operators would not necessarily need to core and sample each formation in the

area of a proposed GS site. If relevant, comprehensive information about the site exists (e.g., from

earlier geologic studies of the area), the Director may, at his/her discretion, allow its use in the site

characterization for the GS project. In addition, §146.87(b) allows 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,

cores of injection zones and confining zones, and samples of formation fluids must be submitted.

§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 adds that §146.87(b) allows the owner or operator to submit whole cores or sidewall

cores of the injection zone and confining system.

Additionally, EPA acknowledges comments regarding the costs associated with thoroughly

evaluating a potential GS site. The Agency believes the requirements for a thorough geologic site

characterization for a GS project are necessary to protect USDWs from endangerment. 

Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23623

Comment: (i)(j) 

These two sections appear to conflict in that (j) asks for the proposed 

formation testing program, which certainly can be defined in advance of drilling 

the injection well, but preceding section (i) asks for the results of 

compatibility testing based on the results of the proposed program. Also, what 

does compatibility mean? Modeling to date suggests that there may be both 

dissolution and precipitation of mineral phases as brine containing dissolved 

CO2 reacts with reservoir and confining layer rock. What is the standard for 

compatibility? If the apertures of microfractures are first enlarged but then 

carbonate or other minerals are expected to be reprecipitated, is that 

compatible? Much more appropriate would be to ask for the expected pathway of 

162
geochemical and geochemical reactions with the standard being that the expected 

pathways present no substantive risk of compromise to the sealing systems. 

Response: EPA agrees that the formation testing plan must be approved before the owner or

operator can generate necessary data on the compatibility of the CO2 stream with fluids in the

injection zone and minerals in both the injection and the confining zone. In response to comments

and based on an evaluation of the proposed requirements, EPA revised subpart §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)).

Regarding compatibility, EPA clarifies that owners or operators must also present information on the

compatibility of the CO2 stream with fluids in the injection zone and minerals in both the injection

and the confining zone(s), as determined through the formation testing program and on the

compatibility of the CO2 with the materials used to construct the well (§146.82(c)(3)). Based on

this, the Director will 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: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23654

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for

permit applications (seeking comment) 

Comment: In its comments, AWWA makes several recommendations for the following specific 

items to be included in the final regulation: 

- A permit process for geologic sequestration (separate from the coal plant), 

with required monthly reporting similar to the NPDES permit/reporting process; 

Response: EPA believes that permitting under the UIC Program is an essential element for ensuring

that GS projects are operated in a manner that protects USDWs from endangerment. The UIC

Program establishes minimum federal requirements for owners or operators of GS wells; and, States

may choose to develop requirements that are as stringent as or more stringent than the minimum

federal requirements. This affords states the flexibility to implement the program while ensuring that

USDWs are protected from endangerment. If a State does not develop UIC Program requirements

for Class VI wells, EPA implements the program in those states. The Agency clarifies that all owners

or operators of Class VI wells must comply with the requirements under Subpart H of 146 in order to

inject CO2 for GS through a Class VI well. A UIC injection well permit application is separate from

other permitting activities (i.e., coal plant permitting). 

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 is developing a number of technical guidances and implementation materials to assist owners or

163
operators and Directors in the permitting process. These guidances will provide recommendations

regarding performing 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. These guidances can be found on EPA’s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

EPA clarifies that owners or operators of Class VI GS wells must comply with UIC semi-annual

reporting requirements at 146.91(a). EPA believes that semi-annual reporting is appropriate to ensure

that permitting authorities can maintain proper oversight of GS projects, particularly in 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.

EPA clarifies that it does not have the authority under the SDWA (and associated UIC requirements)

to alter permitting requirements issued under other environmental statutes for coal plants or any CO2

sources. The UIC program's authority is limited to the injection operation and ensuring that USDWs

are protected from endangerment. 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23656

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for

permit applications (seeking comment) 

Comment: In its comments, AWWA makes several recommendations for the following specific 

items to be included in the final regulation: 

- Requirement for formal technical, managerial, and financial plans for GS 

owners/operators; and 

Response: EPA agrees that requiring project plans for GS wells is appropriate. The final GS rule

requires owners and operators to develop, gain approval for, and implement a series of projectspecific plans, including: an area of review (AoR) and corrective action plan, a testing and

monitoring plan, an injection well plugging plan, a post-injection site care and site closure plan, and

an emergency and remedial response plan. All of these plans must be submitted at the time of permit

application (§146.82(a)), along with a demonstration that appropriate financial resources are

available, pursuant to requirements at §146.85, to fund all required activities. EPA believes that the

requirement for the plans associated with GS projects will promote an ongoing dialogue between the

owner or operator and the Director to ensure that USDWs are protected from endangerment. EPA is

developing guidances to assist owners or operators in describing how to prepare the project plans

and how to meet the financial responsibility requirements for GS wells. The guidances can be found

on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23724

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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 

164
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.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23725

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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 

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.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23726

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

Comment: Part 146.82 (c) AWWA recommends revising this part to read: 

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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...”

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23727

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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 

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 

166
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. 

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: 

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(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. 

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 sitespecific 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

168
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.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24374

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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 

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.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24420

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 

169
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.

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23890

Comment: o Area/field Permitting- Many CCS sites will be multi-well sites, with the 

170
possibility, as in EOR applications, for hundreds of wells. It is recommended 

that an area/field permitting approval be implemented to simplify the process 

and allow for well-by-well flexibility in requirements where that makes sense. 

Response: EPA disagrees that area permits are appropriate for GS wells. The Agency believes that

individual injection well permits are essential to ensure that every GS well is constructed, operated,

monitored, plugged, and closed in a manner that is protective of USDWs. 

EPA believes that the efficiencies and administrative benefits offered by area permits can be

achieved through well executed plans required for GS wells. EPA envisions that planned additional

GS wells should be discussed as part of the ongoing dialog between the owner or operator and the

Director. For example, EPA expects the AoR plan to consider anticipated future wells so that the

Director is able to consider all anticipated injection and resultant pressure changes in evaluating the

plan and setting permit conditions. Similarly testing and monitoring plans should account for future

injection wells to ensure that ground water monitoring or CO2 plume and pressure front tracking are

planned appropriately. 

Through this iterative planning process, the owner or operator and Director can identify ways to

streamline future submittals, including permit applications for future wells in the same field. For

example, the parties could identify common, static components of the project that could be

incorporated into future permit applications and facilitate submittal of data by the owner or operator

and review and approval by the Director.

EPA also believes that requiring separate permit applications for each well will ensure that the public

has an opportunity to provide input on each well in the field as it is constructed or brought online. In

addition, where wells are re-permitted as GS wells (e.g., in ER projects, which may typically operate

under Class II area permits), EPA believes that the unique nature of GS necessitates individual

review of each well to ensure the re-permitted wells were engineered and constructed to achieve the

goals of §§146.86(b) and 147.87(a) and ensure protection of USDWs from endangerment. 

EPA disagrees that many GS sites would have the hundreds of wells that are typical of some Class II

ER projects. EPA believes that newer technologies, such as horizontal well injection will likely

reduce the number of wells in GS projects.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24649

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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; 

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

171
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.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24650

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24651

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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.

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22720

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, 

deep stratigraphic boreholes, State or EPA approved subsurface cleanup sites, 

surface bodies of water, springs, mines (surface and subsurface), quarries, 

172
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). 

§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: EPA believes that a determination about whether information necessary (for a specific

GS project) 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 if there is reason to believe that the incompleteness of available

information could compromise USDW protection from endangerment.

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 22909

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for

permit applications (seeking comment) 

Comment: - The Final Rule must not make the application process overly burdensome or 

unrealistic by requiring detailed information that may not be available at the 

time of the initial application; instead, the Final Rule should allow for 

submission of updated information regarding a CO2 GS well and its AoR as that 

information becomes available. 

Response: EPA disagrees that any of the protective requirements are unnecessary, and believes that

the Class VI GS requirements for obtaining a permit are tailored so that they are appropriate for the

unique nature of injecting large volumes of CO2 into a variety of geological formations for longterm storage.

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

173
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.

Commenter Name: Diane VanDe Hei Letter ID: 0213

Commenter Organization: Association of Metropolitan Water Agencies

(AMWA)

Comment ID:

22926

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for

permit applications (seeking comment) 

Comment: Drinking water utilities must be consulted during the review of any CO2 

sequestration permit application. AMWA recommends that as part of the process, 

all drinking water utilities that draw from an aquifer in the area of review 

(AoR) of a potential CO2 sequestration project should be informed and consulted. 

Response: As part of the UIC permit review process in 40 CFR 124, the UIC program Director must

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.

In addition, the existing public participation requirements for UIC permits at 40 CFR

124.10(c)(1)(x)(A) require notification "to any unit of local government having jurisdiction over the

area where the facility is proposed to be located." EPA believes these requirements address the

commenter's concerns.

Commenter Name: Dennis R. James Letter ID: 0214

Commenter Organization: North American Coal Corporation (NAC) Comment ID: 22963

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards) 

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. 

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 

174
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.

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24288

Comment: IV. SUGGESTED CHANGES TO LANGUAGE OF PROPOSED RULE 

[In the sections below, the text in CAPS denotes added text.] 

A. § 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. 

175
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. 

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.

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24289

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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 

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: 

176
(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. 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24290

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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. 

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

177
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.

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the

University of North Dakota

Comment ID:

21631

Other EPA Comment Codes and Descriptions: 3140 2.1.4 Comments that the proposed geologic

data requirements are too stringent 

Comment: Page 43536. § 146.82 Required Class VI permit information. There are numerous 

requirements for information on formations overlying the proposed storage site. 

Requirements should be flexible and site-specific. The required information 

should be limited to relevant primary and/or secondary seals and be used to 

document the vulnerability or lack thereof of any USDWs in the area. 

Response: 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).

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the

University of North Dakota

Comment ID:

21632

Comment: Page 43536. § 146.82 Required Class VI permit information. The requirement of 

baseline geochemical data on subsurface formations should be flexible and sitespecific. The required information should be limited to relevant primary and/or 

secondary seals and be used to document the vulnerability or lack thereof of any 

USDWs in the area. 

Page 43536. § 146.82 Required Class VI permit information. Well-plugging 

requirements can change throughout the life of a well. Therefore, requiring a 

well-plugging plan with the permit application is excessive and unnecessary. 

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

178
require geochemical analysis of additional subsurface zones if in the Director's opinion they are

necessary for the protection of USDWs from endangerment. 

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23969

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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; 

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(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. 

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. 

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24017

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

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 

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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) 

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; 

181
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? 

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.

182
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 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.

Commenter Name: Neeraj Gupta Letter ID: 0229

Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21811

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for

permit applications (seeking comment) 

Comment: Permit Organization - The proposed regulation presents a large amount of 

material spread throughout the document. In general, it has been easier to 

complete the permit process with the basic UIC form with the simplified list of 

attachments (this procedure was used for Region 4 and Region 5). Thus, the 

MRCSP would encourage EPA to prepare suggested formats and a systematically 

organized list of information and documents required for the permit. 

183
Response: 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 is also developing a number of

technical guidances and implementation materials to assist owners or operators and Directors in the

permitting process. EPA expects that these guidances will assist permit writers in performing 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 guidance can be found

on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Neeraj Gupta Letter ID: 0229

Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21863

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for

permit applications (seeking comment) 

Comment: Page 112, Reporting - The policy suggests monitoring and testing plan, 

AOR/corrective action plan, and Post-Injection plan. We’d recommend these 

documents be included as supporting attachments the permit application. This 

level of reporting may result in delays to the permitting process. 

Response: EPA believes that the requirement that owners and operators develop an area of review

(AoR) and corrective action plan, a testing and monitoring plan, an injection well plugging plan, a

post-injection site care and site closure plan, and an emergency and remedial response plan are

necessary to protecting USDWs from endangerment and does not believe they will result in delays to

the permitting process. EPA anticipates that these plans will be attachments to the permit application

and also acknowledges that not all information necessary to develop full plans will be available at

the time of the initial permit application. For this reason, EPA envisions an iterative process where

the owner or operator and the Director will discuss the site data being collected and how it will

inform all aspects of the project, including the plans under §146.82. EPA is developing guidances to

assist the owner or operator in preparing the project plans and meeting the financial responsibility

requirements for GS wells. The guidances can be found on EPA’s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Neeraj Gupta Letter ID: 0229

Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21868

Comment: Page 193, AOR Map- It will be difficult to provide the numerous site features on 

a single map as required in the regulation. Multiple maps should be allowed. 

Otherwise, 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, and faults. 

Response: EPA acknowledges the comments and agrees that multiple maps may be necessary to

present all of the data needed to support a determination of the suitability of a site for GS. Nothing

in the GS rule prohibits this.

184
Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23257

Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for

permit applications (seeking comment) 

Comment: wells. The timing of plan submittal should be linked to the activity being 

addressed. Site closure plans, post-closure plans, well plugging plans, etc., 

should not be required many years in advance since conditions, understanding of 

the sequestration zones, and technology change over time. 

Response: EPA disagrees with the commenter's assertion that that the timing of plan submittals

should be linked to the specific activity being addressed, and believes that submittal and review of

each of the owner or operator's plans required at §146.82 at the time of the permit application is

necessary for the Director to make a permit approval determination. While injection well plugging,

post-injection site care and site closure will likely not occur for years after injection commences, the

Director needs to have assurance that the owner or operator has planned for these events.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23282

Comment: 146.82(u) Site closure plans, post-closure plans, well plugging plans, etc., 

should not be required many years in advance since conditions, understanding of 

the sequestration zones, and technology change over time. 

Response: EPA disagrees with the commenter's assertion that that the timing of plan submittals

should be linked to the specific activity being addressed, and believes that submittal and review of

each of the owner or operator's plans required at §146.82 at the time of the permit application is

necessary. While injection well plugging, post-injection site care and site closure will likely not

occur for years after injection commences, the Director needs to have assurance that the owner or

operator has planned for these events.

Commenter Name: Kristin Henry Letter ID: 0242

Commenter Organization: Sierra Environmental Law Program, Sierra Club Comment ID: 23312

Comment: CCS Permitting Requires Specialized Technical Expertise 

Permitting a Class VI well involves many complicated technical issues across a 

range of disciplines. Site selection alone involves characterization of geology, 

hydrogeology, geochemistry and geomechamics. [FN13] Well construction, interpreting 

monitoring data, and proper site closure are a few other highly technical areas. 

EPA’s proposed rule recognizes these complexities by requiring submission of 

numerous types of data with a permit application and continuous monitoring and 

reporting. But the rule does not provide for technical analysis of this 

information. It entrusts evaluation of this data to the state administrator or 

to the EPA in non-delegated states. 

[FN13: IPCC CCS 5.4.1.1, Table 5.3.] 

Response: EPA clarifies that permit information is subject to technical review. Permitting authority

staff will evaluate the extensive data that owners or operators submit under §146.82 to determine the

185
suitability of a potential project site for GS. EPA adds that the staff in state primacy agencies and

EPA regional offices (who will review permit applications in states that do not have primacy) have

years of experience with the current UIC injection well classes, have permitted deep injection wells

in the past, and have relevant specialties in geology, engineering, and related disciplines. 

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. Additionally, EPA expects that this guidance will assist

permitting authorities in evaluating initial permits for Class VI injection wells with technical

assistance as needed. The guidance can be found on EPA’s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Kristin Henry Letter ID: 0242

Commenter Organization: Sierra Environmental Law Program, Sierra Club Comment ID: 23314

Other EPA Comment Codes and Descriptions: 5600 2.11 Comments related to UIC Program

primacy for Class VI wells; 5700 2.12 Comments on the proposed duration of Class VI permits

(seeking comment) 

Comment: • EPA - advised by experts and regional stakeholders - and not individual 

states, should make permitting decisions on CCS projects, at least for the first 

few years. 

• Permits should be issued in stages, to be adaptive to advances in knowledge, 

science and regulation, not for the operating life of the well. 

Response: EPA agrees that an adaptive approach to address the availability of new information and

technology is appropriate. EPA plans to, every six years, collect and review project data on early GS

projects, including site characterization, operational, monitoring, and modeling 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.

EPA disagrees that it should be the only entity to issue permits during the first few years after

promulgation. 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) 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. 

Additionally, States can use multiple authorities beyond those afforded under the SDWA 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. 

EPA expects that both Headquarters and the Regions will work closely with the states during the

early permitting process to ensure that flexibility is applied in a manner that ensures a consistent

level of USDW protection from endangerment. EPA designed flexibility into the regulations to

ensure that site-specific factors can be accounted for and expects that permit writers will use

186
discretion where site-specific factors are important. As part of its adaptive approach, EPA also plans

to review initial permits (after they are granted) to ensure that USDW protection goals have been

consistently met across differing geologic situations. If necessary, EPA will reevaluate the flexibility

granted to states in the rule. 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. 

Regarding the commenter's request that permits be issued in stages, EPA clarifies that the final rule

maintains the lifetime permit provision and 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 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.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24877

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 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 

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 

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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; 

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; 

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(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); 

(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. 

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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.

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