2.7 – 2.8 – Responses to Public Comments on Recordkeeping, Reporting, Injection 

Well Plugging, Post Injection Site Care, and Site Closure

This file contains responses to public comments on recordkeeping, reporting, injection 

well plugging, post injection site care, and site closure (comment codes 4700 to 5300). 

This section includes comments on submissions required for permit applications, 

operational recordkeeping, and electronic reporting. It also includes comments on 

requirements for closing and maintaining the site after injection has ceased.

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

2.7 Proposed Recordkeeping and Reporting Requirements (40 CFR 146.91) 4700

2.7.1 Proposed submissions required for permit applications 4710

2.7.2 Operational recordkeeping and reporting 4720

2.7.3 Reporting associated with closure and post-injection site care 4730

2.7.4 Electronic reporting 4740

2.7.5 Comments on the merit of annual reports 4750

2.7.6 Proposed reporting frequency 4760

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

2.8.1 Injection well plugging activities (40 CFR 146.92) 5100

2.8.2 Post injection site care (40 CFR 146.93) 5200

2.8.2.1 Post-injection monitoring activities 5220

2.8.2.2 Post injection timeframe 5240

2.8.2.3 Adjusting the post-injection timeframe 5260

2.8.2.4 USDW non-endangerment demonstrations 5280

2.8.3 Site closure activities (40 CFR 146.93) 5300

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: 4700 2.7 Proposed Recordkeeping and Reporting Requirements (40 CFR 146.91) 

Individual Comments

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

Commenter Organization: Global Energy, Inc. Comment ID: 23121

Other EPA Comment Codes and Descriptions: 4546 2.5.2.2 MIT frequency (seeking comment) 

Comment: 6.We support mechanical integrity testing and monitoring, in some respects (on a 

continuous basis). Sensors and data logging is readily available. Semi-annual 

reporting, along with other reporting requirements, is also quite reasonable. 

Response: EPA agrees with the commenter regarding the importance of demonstrating internal

mechanical integrity (MI). EPA agrees with the commenter that continuous pressure monitoring of

GS wells, instead of periodic testing, which is required for most other types of deep injection wells is

appropriate because the potentially corrosive nature of CO2 injectate streams in the presence of

water enables the immediate identification of corrosion-related internal mechanical integrity

problems that could lead to significant well problems and failure. 

Continuous monitoring was found to be very important in an EPA study of UIC Class I internal MIT

failure rates and causes (USEPA 1993). The study reviewed MIT results over a 5 year period and

found 135 MIT failures in 428 wells (a single well can have more than one MIT failure). In all cases,

the MIT failures were found through continuous annulus monitoring which served the important role

of an early warning to prevent any well failure. Class VI injection wells will be equipped with

dedicated computer-based continuous pressure monitoring devices in concert with the shut-off

systems required for GS wells, which typically take readings several times per second and record

them electronically in a computer system. §146.91(a)(2) requires that monthly averages of the

continuous annulus monitoring be reported on a semiannual basis.

EPA is retaining the semi-annual reporting requirement in the final rule at §146.91(a) in order to

ensure that permitting authorities can maintain proper oversight of GS projects, particularly in 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.

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22654

Other EPA Comment Codes and Descriptions: 5500 2.1 Comments on Involving the Public in

Permitting Decisions 

Comment: Page 43528. The proposed Class VI rule states "The information gathered as a 

result of this proposed rule" allows the Agency to verify throughout the life 

of the injection project that UIC protective requirements are in place and that 

USDWs are protected. At the end of the day, this is indeed the figure of 

merit. Does this rule allow for sufficient exchange of information between the 

owners/operators of GS projects and regulators and stakeholders (?). This 

reviewer is not convinced that this metric is satisfied by the proposed rule. 

Response: EPA agrees that interaction between the owner or operator and the Director is an
important part of ensuring that GS projects are operated in a manner that protects USDWs from

endangerment. EPA believes that the site-specific GS project plans which will be reviewed and

approved by the Director and periodically updated throughout the life of the project—promote an

ongoing dialogue between the operator and the Director that will encourage use of the most

appropriate technologies for a particular project.

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.

Involving the public in the permitting process is an important aspect of both UIC Program

requirements and EPA's overall mission. The public will also have the opportunity to submit written

comments and, in many cases, attend hearings on proposed GS projects during formal public

comment periods. Although permit application information will not be made available as it is

submitted, permitting authorities must follow the public participation requirements for UIC permits

specified in 40 CFR Part 124 which require that owners or operators publish a public notice that

includes information about where interested parties can obtain copies of the draft permit and

application in addition to requesting a public hearing. 

Furthermore, the Agency recognizes that the initial phases of site evaluation and site selection may

begin in advance of permit application submission. The public may become aware of these activities

and begin to have questions or concerns about the pending project. For this reason, outreach and

education—which are outside of, but complementary to, the public notification process—can help

clarify project details and avoid public misperceptions about the nature and safety of GS projects.

This may also benefit the owner or operator by improving local acceptance of the site. EPA also

notes that should 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.

In addition, EPA is evaluating options for a centralized data system through which the public could

have access to public information on a GS project. EPA will also provide access to any required plan

to the public upon request. Providing the public with information throughout the GS project will help

clear up and avoid public misperceptions about the nature and safety of GS. 

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23844

Comment: A. GENERAL COMMENTS 

The application and reporting requirements for Class VI wells should be 

balanced, placing as little burden as possible on owners and operators, while 

also achieving EPA's goals. Sufficient reporting requirements ensure the 

collection of information necessary for the protection of human health and the 

environment, and provide companies and investors with information to better 

manage and mitigate risks. A robust but not overly burdensome reporting regime 

is necessary to the success of CCS. as well as to achieving EPA's goals of 

protecting USDWs. 

Response: EPA believes that all of the requirements for Class VI wells, including the reporting and

recordkeeping requirements, are necessary to ensure that GS is conducted in a manner that protects

USDWs from endangerment. The requirements for GS projects are tailored to address the unique

issues associated with GS including large injection volumes, the relative buoyancy of CO2, its

corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its
mobility within subsurface geologic formations. Because these requirements are necessary to protect

USDWs from endangerment, they are in effect not overly burdensome to the owner or operator.

The final GS rule affords flexibility to owners or operators. Many of the permit requirements will be

established through site-specific plans developed by the owner or operator and approved by the

Director. 

EPA is using an adaptive approach to regulating GS. The Agency plans to, every six years, collect

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

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

the requirements are appropriate or necessary.

Commenter Name: John R. Baza Letter ID: 0193

Commenter Organization: Utah Division of Oil, Gas, and Mining Comment ID: 23915

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

Monitoring Requirements (40 CFR 146.90) 

Comment: Monitoring 

EPA seeks comments on proposed pressure plume and pressure front monitoring 

including issues such as the amount and type of monitoring, the usefulness of 

geophysical, air and soil monitoring, post-injection site monitoring, and 

frequency of reporting requirements. The IOGCC comments of December 23, 2008 

have addressed all of these issues in great detail, and the Division concurs 

with their recommendations. 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

EPA agrees with commenters that developing and following testing and monitoring plans is an

important part of assuring that a GS project is operating properly and is crucial for the early

detection of potential endangerment to USDWs. EPA also agrees that periodic updates to the plan are

appropriate. EPA clarifies that the final GS regulation includes a requirement that the AoR be

reevaluated at least every five years, and it specifies at §146.90(j) that the operator revise the testing

and monitoring plan to incorporate the results of the most recent AoR reevaluation and recent

operational and monitoring data.

EPA acknowledges the comment and the final rule retains the text as proposed. Please see the final

rule and the discussion of testing and monitoring in the preamble for additional information.

Commenter Name: Neeraj Gupta Letter ID: 0229

Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21861

Comment: Page 111-118, Reporting- More streamlined permit application structure and 

clearly defined information requirements should be provided in regulatory 

guidance. We request streamlined reporting (Monitoring and testing plan, 

AOR/Corrective action review plan, post-injection plan, annual report, monthly 

operating reports). 
Response: EPA disagrees with the suggestion that the permit application structure be more

streamlined and information requirements be more clearly defined. EPA believes that information

required to be submitted with the permit application under §146.82 is necessary and appropriate to

provide permitting authorities sufficient basis for informed decisions about establishing permit

conditions and granting permits. The purpose of these requirements is to protect USDWs from

endangerment, and all operations must be permitted and operated in manner that is protective of

USDWs. 

Furthermore, EPA’s GS Rule provides for a streamlined approach to reporting under §146.91. EPA

is retaining the semi-annual reporting requirement in the final rule at §146.91(a) in order to ensure

that permitting authorities can maintain proper oversight of GS projects, particularly in 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.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23303

Comment: 146.91(a) Injection volumes and pressures should be reported monthly. 

Response: The final rule remains unchanged from the proposal and requires semi-annual reporting

of monthly average, maximum and minimum values for injection pressure, flow rate and volume,

annular pressure, and monthly annulus fluid volume added at §146.91(a). EPA believes that monthly

reporting of routine operational data and monitoring results would provide no additional protection of

USDWs from endangerment. EPA adds, at §146.91(c), that it has included in the final rule a

requirement that operators must report within 24 hours of any event that may endanger USDWs;

noncompliance with a permit condition or malfunction of injection system which triggers fluid

movement; any triggering of a shut-off system; any failure to maintain mechanical integrity; or if

anything is detected through surface/air monitoring, if its required. EPA notes that states seeking

primacy for Class VI wells are free to require more frequent reporting. 

Please see the final rule and the discussion of testing and monitoring in the preamble for additional

information.

Commenter Name: Walter L. Baker Letter ID: 0253

Commenter Organization: Utah Division of Water Quality Comment ID: 22353

Other EPA Comment Codes and Descriptions: 4740 2.7.4 Electronic reporting (seeking comment)

Comment: ELECTRONIC REPORTING 

We agree with EPA that electronic reporting will reduce reporting burden and 

will facilitate tracking of CCGS projects. However, the "electronic format 

acceptable to the Director" should not constitute a financial or resource burden 

to the owner / operator or to the regulating agency required to report to EPA on 

UIC program activity. Until that time when the regulating agency has developed 

a data flow to the National UIC Database, we strongly urge EPA to develop an 

online service for submitting CCGS information such as is currently in place for 

submitting Program Activity Measures (PAMs) and UIC inventory. 
Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director, and based on comments received on the proposed rule,

the majority of Class VI well owners or operators will have the capability to report electronically,

and requires this at §146.91(e). 

Acknowledging that some States may have to develop electronic data systems to receive electronic

information from the owner or operator, and that many States which already have electronic data

systems will have to make changes to accommodate a new class of UIC well (Class VI), EPA

believes that it is prudent to provide assistance by developing a central framework for the electronic

system that will be used by States to gather and track owner or operator data. This will enable

owners or operators to submit data without having to wait for a State to develop a system. It will also

provide for standardized submissions across the country and enable States to focus State resources on

reviewing and approving permit applications rather than building or upgrading separate, independent

databases for GS information.

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: John McManus Letter ID: 0294

Commenter Organization: American Electric Power Comment ID: 25317

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

language; 3500 2.2.3 Area of Review Reevaluation (seeking comment) 

Comment: In addition, we recommend the following new §146.95: 

"146.95 Plan Maintenance and Update 

"(a) Owners or operators must submit an annual statement, signed by an 

appropriate company official, confirming that the company has: 

"(i) reviewed the monitoring and operational data that are relevant to a 

decision on whether to reevaluate the area of review and the monitoring and 

operational data that are relevant to a decision on whether to update a plan 

identified in §146.82(p) or (u) through (x) or the quality assurance plan for 

all testing and monitoring requirements; and 

"(ii) determined whether any updates were warranted by material change in the 

monitoring and operational data or in the evaluation of the monitoring and 

operational data by the owner or operator. 

"(b) Owners or operators must submit either the updated plan or a summary of 

the modifications for each plan for which an update was determined to be 

warranted pursuant to subsection (a) of this section. The Director may require 

submission of copies of any updated plans and/or additional information 

regarding whether or not updates of any particular plans are warranted. 

"(c) The Director may require the revision of any required plan whenever the 
Director determines that such a revision is necessary to comply with the 

requirements of this subchapter." 

Response: EPA agrees with the commenter that review of the GS project plans is appropriate. The

final rule includes provisions that owners or operators review and update the AoR and corrective

action plan, the testing and monitoring plan, and the emergency and remedial response plan

throughout the life of the project (these provisions are added at §146.84(c), §146.90(j), and

§146.94(d)). Owners or operators must review each plan and identify necessary amendments to the

plan or demonstrate to the Director that no amendment is needed. These reviews must be performed

within one year of an AoR reevaluation, following any significant changes to the facility (e.g., the

addition of monitoring or injection wells), or when required by the Director.

Comment Code: 4710 2.7.1 Proposed submissions required for permit applications (seeking

comment) 

Individual Comments

Commenter Name: George Holliday, PhD, PE, BCEE Letter ID: 0114

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 22518

Other EPA Comment Codes and Descriptions: 1670 1.3.7 Other/miscellaneous risks 

Comment: required to see the project to completion. Further, the well designs and 

operations would be approved by Agency technically untrained employees, who are 

not Professional Engineers and supervised by a Regional Director who is neither 

an engineer nor a Professional Engineer. 

The Agency proposes using untrained EPA employees who are not required to 

demonstrate their CO2 sequestration technical knowledge by completing and 

passing a written examination. Further, the Agency proposes to sequester 

Response: As described above, EPA disagrees that the people designing and regulating wells lack

technical training for effective oversight of Class VI wells. Most permitting authority staff have years

of experience with the current UIC injection well classes and have relevant specialties in geology,

engineering, and related disciplines. Injection well owners and operators represent industries with

decades of experience injecting a variety of fluids, including CO2. EPA believes that this experience

has led to the development of well materials and construction and operating procedures that are

applicable to Class VI wells.

Commenter Name: George Holliday, PhD, PE, BCEE Letter ID: 0114

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 22521

Other EPA Comment Codes and Descriptions: 1670 1.3.7 Other/miscellaneous risks 

Comment: The sequestration of CO2 represents a money-making scheme for a "political" 

pollutant, which will encourage unqualified organizations and speculators to 

seek Class VI injection permits. These unqualified organizations will find 

unqualified consultants to prepare documents supporting the permit applications. 

EPA, in the instant proposed rule, suggests several financial responsibility 

schemes to avoid unqualified organizations and speculators from creating a 

disaster, but EPA and states do not know how to assure financial responsibility 
as demonstrated by the lack specificity within the proposed rule. Rules 

proposed with this lack of specificity, typically result in EPA selecting final 

rule wording, which received no comments during the proposal stage. This gives 

EPA free rein to select regulation wording not reviewed by the commenting 

public, and not alluded to during the proposal. 

One of the most frightening aspects of the proposed rule is EPA imposes no 

technical qualification requirements on EPA review personnel. Thus, a well 

written, but inaccurate document, can easily be accepted by EPA, when 

technically unqualified reviewers are used. If qualified reviewers were used, 

the application would be rejected. 

Response: As described above, EPA disagrees with the assertion that the staff reviewing permit

applications does not have adequate technical knowledge to review and approve Class VI permits.

EPA will be facilitating training on the GS rule requirements for states and Regional staff in addition

to providing guidance on implementation of the Class VI UIC program.

EPA clarifies that the person who signs a permit application must certify that the application is

accurate and that data was collected in accordance with a system designed to ensure that qualified

personnel evaluate the data. EPA believes that assigning this responsibility to the signatories will

ensure that the work has been properly supervised. Failure to meet this requirement would subject

the owner or operator of the well to applicable civil, criminal, or administrative penalties under

SDWA §1423.

EPA adds that owners or operators of Class VI wells must ensure that resources are available to

prevent endangerment of USDWs from improper plugging, remediation, and management of wells.

For this reason, the GS rule requires that owners or operators demonstrate and maintain financial

responsibility for corrective action on wells in the AoR, injection well plugging, post-injection site

care and site closure, and emergency and remedial response at GS sites as specified in §146.85. EPA

has revised the requirements in the final rule to provide more specifics. In the event of contamination

or other adverse event that endangers a USDW during the life of the GS project, the financial

instrument(s), such as insurance, bonds, etc., rather than public monies, would cover necessary

response actions. 

EPA adds that Class VI well owners and operators must site, construct, operate, monitor, and close

their wells in a manner that protects USDWs, and Class VI permits will set forth rigorous technical

requirements to ensure careful planning, operation, and closure of GS projects. 

EPA adds that the requirements in the final GS rule, including all changes from the proposed rule,

are based on consideration of public comments received in response to the proposed rule and its

subsequent Notice of data Availability and Request for Comment issued on August 31, 2009 (74 FR

44802).

Commenter Name: George Holliday, PhD, PE, BCEE Letter ID: 0114

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 22529

Other EPA Comment Codes and Descriptions: 1670 1.3.7 Other/miscellaneous risks 

Comment: LACK OF QUALIFIED EPA PERSONNEL 

EPA requests comments on many aspects of CO2. For example at 73 FR 43514, col. 
2, EPA request help learning to track CO2 underground plumes. I have worked 

with the UIC rules as a commenter since 1979. At no time did EPA use an EPA 

Professional Engineer (P.E.) for developing the UIC rules. During the initial 

stages of writing the 1979 draft rules, EPA used an Ancient English graduate as 

the Agency lead technical supervisor. Ancient English is not considered a 

technical background. 

I have not found any of the current EPA UIC Regional employees to be 

professional engineers. When I requested the information in writing from EPA, I 

was told privacy laws prohibited providing such information. Reviewing and 

understanding CO2 sequestration projects is a technically exacting task. 

Assigning an EPA non-Professional Engineer to this review task exposes the U.S. 

public to severe risk. Placing the final approval in the hands of a Regional 

Administrator, who traditionally is not an engineer, means the EPA is 

disregarding public safety. At a minimum, the reviewing engineer and Regional 

Administrator must be Professional Engineers. EPA at 40 CFR Part 112 requires a 

Professional Engineer certify a Spill Prevention, Control and Countermeasure 

(SPCC) Plan, which typically is intrinsically a simple non-technical document, 

but EPA does not rely on EPA Professional Engineers to review high pressure, 

corrosive fluid injection projects, that are highly technical and intrinsically 

unsafe. 

EPA has likened Class VI projects to Class I hazardous waste injection wells and 

Class II CO2 enhanced recovery wells. It is true Class I disposal wells 

sequester hazardous waste, but these wastes are not buoyant and typically are 

combined with other waste to make them non-corrosive. FURTHER, THE AGENCY HAS 

BEEN REVIEWING CLASS II WELL PLANS SUBMITTED BY EXPERIENCED OIL AND GAS

COMPANY 

ENGINEERS. An anticipated shortage of trained oil and gas industry engineers 

(Bryant, 2007) and the political nature of CO2 sequestration projects ( 

www.wecansolveit.org) will attract spectators, who do not intend to see the 

project through to completion. Thus, the Agency may be forced to correct many 

problems caused by poor review and oversight on the part of the untrained EPA 

employees 

Bryant, S., 2007. Geologic CO2 Storage - Can the Oil and Gas Industry Help 

Save the Planet? J Pet. Tech (JPT), p 98-105, September 

Response: As described previously, most permitting authority staff have years of experience with

the current UIC injection well classes and have relevant specialties in geology, engineering, and

related disciplines. Additionally, EPA will coordinate with and assist states, e.g., through guidance

and on-line and in-person training, to help them address problematic technical and policy issues.

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; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

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

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: 24765
Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

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

Comment: (i) The compatibility of the CO2 stream with fluids in the injection zone and 

minerals in both the injection and the confining zone(s), based on the 

results of the formation testing program, and with the materials used to 

construct the well; 

{See comment above.} 

Response: The final rule will allow the Director to require more than one confining zone; therefore,

EPA did not make the suggested change.

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

additional information.

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

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: George Holliday, PhD, PE, BCEE Letter ID: 0127

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 23057

Comment: D. EPA RULE DOES NOT IMPOSE ANY TECHNICAL QULIFICATIONS ON THE

EPA PERMIT 

REVIEWER. 

1. CO2 is injected in a supercritical phase, e.g., 2200± psia. 

2. CO2 is buoyant and becomes a gas as the pressure decreases. 

3. CO2 sequestration looks like a money making scheme, so speculators will be 

attracted. 

4. EPA likens CO2 sequestration wells (Class VI wells) to Class II Enhanced 

oil/gas well, water injector wells and Class I hazardous waste disposal wells. 
4. Class II well injected liquids are not corrosive. Special care is exercised 

to make injected water O2 free to avoid corrosion. 

5. Class I injected fluids are blended to avoid corrosion. 

6. Class II Enhanced oil recovery CO2 injection wells reservoirs are produced 

until abandonment, which lower the pressure to about the original pressure, 

Unlike Class II wells, sequestration well will be abandoned at the maximum 

injection pressure. 

7. CO2 sequestration will attract many speculators, because of fast money during 

injection, but the speculators will fade away during the monitoring phase. 

8. Speculators will write a good proposal without the technical expertise to 

conduct the drilling, completion and injection safely. Unqualified/untrained EPA 

reviewers will have difficulty recognizing a sound proposal from an 

unsatisfactory proposal. So unsafe projects will be approved. 

9. Speculators will go out of business in 50 years, assuming they remain in 

business after the money making inject is completed. 

10. EPA makes no provision in the rules for qualified EPA personnel to correct 

problem left by the speculators. 

11. EPA says the Regional Administrators have the authority to make technical 

decisions. 

12. Regional Administrators typically are not technically trained 

13. I requested under a FOI letter, the number of Permit writer/reviewers who 

were graduate engineers. EPA refuse to respond by saying such information was 

protected by the privacy laws. 

14. At a minimum the proposed rule needs to require the EPA permit 

writer/reviewer be a Professional Engineer who stamps ever permit demonstrating 

the competency of the well project design and the Regional Administrator must be 

a graduate engineer.. 

15. EPA require a P.E. stamp SPCC Plans, a Plan of no real consequence, but, 

now, allows an EPA employee, who has not demonstrated competency to review and 

approve a massive vessel operating at 2200 psia. 

Response: EPA disagrees that the people designing and regulating wells lack technical training for

effective oversight of Class VI wells. Most permitting authority staff have years of experience with

the current UIC injection well classes and have relevant specialties in geology, engineering, and

related disciplines. Injection well owners and operators represent industries with decades of

experience injecting a variety of fluids, including CO2. Regarding UIC requirements for staff

qualifications, EPA clarifies that only the Class I hazardous waste injection well regulations at

§§144.14(c)(9) and 144.63 (i) require that a professional engineer certify closure of the well.
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); 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

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 

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. 

- 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 

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: 3130 2.1.3 Comments that operators should submit

more (or different) geologic data than proposed 

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 

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. 

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. 

- 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: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22590

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

language 

Comment: Proposed Rule: 146.82 

Comment: NGWA raises the question of whether a requirement should be included 

that all applications for Class VI construction permits include a certification 

that the facility was designed by an appropriately qualified professional 

engineer with an option for an appropriate qualified professional geologist to 

certify the well design (taking into consideration confinement, injectivity, 

etc). 

Proposed addition: (1) Class VI - Test/Injection Well Construction and Testing 

Permit 

Proposed addition: (a) The Director shall deny a construction permit if 

construction of the well itself may endanger the health of persons or the 

environment 

Proposed addition: (b) For construction permit approval, reasonable assurance is 
required that the project will function in compliance with this chapter. The 

Director shall require an exploratory well for those projects located in an area 

where available information is lacking concerning geologic or hydraulic 

confinement or existing information indicates that geologic or hydraulic 

confinement may be poor or lacking. 

Proposed addition: (c ) For a Class VI well, issuance of a construction permit 

does not obligate the Director to authorize any operation of the well, unless 

reasonable assurance has been provided that the well can operate in compliance 

with this chapter. 

Proposed addition: (d) Information required in 40 CFR 144.31 (e)(1) through (6) 

Proposed addition: (e) A map showing the injection well(s) for which a permit is 

sought and the applicable area of review. Within the area of review, the map 

must show the number, or name and location of all injection wells, producing 

wells, abandoned wells, plugged wells or dry holes, deep stratigraphic 

boreholes, State or EPA approved subsurface cleanup sites, surface bodies of 

water, springs, mines (surface and subsurface), quarries, water wells and other 

pertinent surface features including structures intended for human occupancy and 

roads. The map should also show faults, if known or suspected. Only information 

of public record is required to be included on this map; 

Proposed addition: (f) The area of review based on modeling, using data obtained 

during logging and testing of the well and the formation as required by 

paragraphs (l), (r ), and (s) of this section; 

Proposed addition: (g) Information on the geologic structure and hydrogeologic 

properties of the proposed storage site and overlying formations, including 

Proposed addition: (1) Maps and cross sections of the area of review; 

roposed addition: (2) Location, orientation, and properties of known or 

suspected faults and fractures that may transect the confining zone(s) in the 

area of review and a determination that they would not interfere with 

containment; 

Proposed addition: (3) Information on seismic history including the presence and 

depth of seismic sources and a determination that the seismicity would not 

interfere with containment; 

Proposed addition: (4) Data on the depth, areal extent, thickness, mineralogy, 

porosity, permeability and capillary pressure of the injection and confining 

zone(s); including geology/facies changes based on field data which may include 

geologic cores, outcrop data, seismic surveys, well logs, and names and 

lithologic descriptions; 

Proposed addition: (5) Geomechanical information on fractures, stress, 

ductility, rock strength, and in situ fluid pressures within the confining zone; 

and 
Proposed addition: (6) Geologic and topographic maps and cross sections 

illustrating regional geology, hydrogeology, and the geologic structure of the 

local area 

Proposed addition: (h) All wells within the AOR and whose total depth is greater 

than the depth to the bottom of the lowermost USDW should be compiled. However, 

preventive corrective action should be undertaken only for those wells that 

penetrate the injection and confining zone(s) 

Rationale: A substantive risk analysis can be performed only if all the (known) 

wells within the AOR and between the injection formation and the bottom of the 

USDW are described. 

Proposed addition: (i) Maps and stratigraphic cross sections indicating the 

general vertical and lateral limits of all USDWs, water wells and springs within 

the area of review, their positions relative to the injection zone(s) and the 

direction of water movement, where known; 

Proposed addition: (j) Baseline geochemical data on subsurface formations, 

including all USDWs in the area of review; 

Proposed addition: (k) Proposed operating data: 

Proposed addition: (1) Average and maximum daily rate and volume of the carbon 

dioxide stream; 

Proposed addition: (2) Average and maximum injection pressure; 

Proposed addition: (3) The source of the carbon dioxide stream; and 

Proposed addition: (4) An analysis of the chemical and physical characteristics 

of the carbon dioxide stream; 

Proposed addition: (l) The compatibility of the carbon dioxide stream with 

fluids in the injection zone and minerals in both the injection and the 

confining zone(s), based on the results of the formation testing program, and 

with the materials used to construct the well; 

Proposed addition: (m) Proposed formation testing program to obtain an analysis 

of the chemical and physical characteristics of the injection zone and confining 

zone; 

Proposed addition: (n) Proposed stimulation program and a determination that 

stimulation will not interfere with containment; 

Proposed addition: (o) Proposed formation testing program to obtain an analysis 

of the chemical, physical and radiological characteristics of and other 

information on the injection zone. 
Proposed addition: (p) Proposed procedure to outline steps necessary to conduct 

injection operation; 

Proposed addition: (q) Engineering drawings of the surface and subsurface 

construction details of the system, including design features for surge control 

and water hammer protection; 

Proposed addition: (r ) Injection well construction procedures that meet the 

requirements of Section 146.86; 

Proposed addition: (s) Proposed area of review and corrective action plan that 

meets the requirements under Section 146.84; 

Proposed addition: (t) The status of corrective action on wells in the area of 

review; 

Proposed addition: (u) A demonstration, satisfactory to the Director, that the 

applicant has met the financial responsibility requirements under Section 

146.85; 

Proposed addition: (v) Proposed testing and monitoring plan required by Section 

146.90 

Proposed addition: (w) Proposed injection well plugging plan required by Section 

146.92(b) 

Proposed addition: (x) Proposed post-injection site care and site closure plan 

required by Section 146.93(a) 

Proposed addition: (y) Proposed emergency and remedial response plan required by 

Section 146.94; and 

Proposed addition: (z) Any other information requested by the Director. 

Proposed addition: (2) Required Class VI operation permit information 

Proposed Rule: 146.82(a) & (b) 

Revision or Comment: Renumber 2(a) & (b) 

Proposed Rule: 146.82(d) - (h) 

Revision or Comment: Renumber 2(d) - 2(h) 

Proposed Rule: 146.82(h) 

Proposed addition: (5) Contingency plans to cope with all shut-ins or well 

failures, including emergency discharge provisions; 

No rationale provided 
Proposed Rule: 146.82(i) 

Revision or Comment: Renumber 2(i) 

Proposed Rule: 146.82(j) 

Proposed revision: 2(j) Results of the formation testing program to obtain an 

analysis of the chemical, physical and radiological characteristics of and other 

information on the injection zone. 

No rationale provided 

Proposed Rule: 146.82(k) - (m) 

Revision or Comment: Renumber 2(k) - 2(m) 

No rationale provided 

Proposed Rule: 146.82(n) 

Proposed revision: 2 (n) Engineering drawings of the surface and subsurface 

construction details of the system, including design features for surge control 

and water hammer protection, including the following: 

Proposed addition: (1) Record drawings, based upon inspections by the engineer 

of record or persons under his direct supervision, with all deviations noted; 

Proposed addition: (2) Copies of the mill certificates of all casings used in 

the construction of the well; 

Proposed addition: (3) Certification of completion submitted by the engineer of 

record; 

Proposed addition: (4) An operation manual including emergency procedures; 

Proposed addition: (5) Proposed monitoring program and data to be submitted; 

Proposed addition: (6) Proof that the existence of the well and any associated 

monitoring wells have been recorded with the permanent warranty deed or other 

instrument of conveyance as a two page proviso or addendum that contains 

certification of the locations of the wells (by metes and bounds) and a detailed 

sketch of the parcel that shows the location of the well. The location shall be 

measured by a certified land surveyor, and shall contain the surveyor's 

signature, registration number, official seal, and the following statement: "I 

hereby certify that this survey was made under my responsible direction and 

supervision, and is a correct representation of the land surveyed." 

No rationale provided 
Proposed Rule: 146.82(o) - (y) 

Revision or Comment: Renumber 2(o) - (y) 

Proposed Rule: 146.82 

Proposed addition: (3) Operational Testing 

Proposed addition: (a) For Class VI wells, the construction permit includes a 

period of temporary injection operation for the purposes of long term testing. 

Prior to commencement of operational testing: 

Proposed addition: 1. Construction of the injection well shall be complete and 

the permittee shall submit a notice of completion of construction to the 

Director. 

Proposed addition: 2. Each well shall first be tested for integrity of 

construction, and shall be followed by a short term injection test of such 

duration to allow for the prediction of the operating pressure. 

Proposed addition: 3. The permittee shall submit the following information to 

the Director, as described in the permit. 

Proposed addition: a. A copy of the borehole television survey(s) 

Proposed addition: b. Geophysical logs, 

Proposed addition: c. Mechanical integrity test data, 

Proposed addition: d. Data obtained during the short term injection testing 

conducted according to subparagraph 2. above. 

Proposed addition: e. Confining zone data, 

Proposed addition: f. Background water quality data for the injection and 

monitor zones; 

Proposed addition: g. Waste stream analysis, 

Proposed addition: h. As-built well construction specifications, and 

Proposed addition: i. Other data obtained during well construction which 

demonstrates that the well will operate in compliance with this chapter. 

Proposed addition: 4. Any corrective action required under Section 146.84, shall 

be completed. 

Proposed addition: 5. Prior to granting approval for operational testing of a 

Class VI well, the Director shall consider the following information: 

Proposed addition: a. All available logging and testing program data on the 

well; 

Proposed addition: b. A demonstration of mechanical integrity 

Proposed addition: c. The anticipated maximum pressure and flow rate at which 

the permittee will operate; 

Proposed addition: d. The results of the formation testing program; 

Proposed addition: e. The actual injection procedure; 

Proposed addition: f. The compatibility of injected waste with fluids in the 
injection zone and minerals in both the injection zone and the confining zone; 

Proposed addition: g. The status of corrective action on defective wells in the 

area of review; and 

Proposed addition: (b) Written authorization for operational testing shall be 

obtained from the Director. Authorization shall be for up to two years or the 

expiration date of the construction permit, whichever is less, and is only 

renewable once as described in Section 146.91. The authorization shall specify 

the conditions under which operational testing is approved. The authorization 

shall include: 

Proposed addition: 1. Injection pressure limitation, 

Proposed addition: 2. Injection flow rate limitation, 

Proposed addition: 3. Injection well monitoring requirements, 

Proposed addition: 4. Effluent monitoring requirements, 

Proposed addition: 5. Weekly ground water sampling of monitor wells, 

Proposed addition: 6. Monthly specific injectivity testing, 

Proposed addition: 7. Reporting requirements, and 

Proposed addition: 8. An expiration date for the operational testing period not 

to exceed two years. 

Proposed addition: (c ) Before authorizing operational testing, the Director 

shall conduct an inspection of the facility to determine if the conditions of 

the permit have been met. 

Proposed addition: (d) A sampling frequency and reporting of less than once per 

month shall not be allowed. 

Proposed addition: (e) For Class VI wells, the duration of the operational 

testing period shall not exceed two years or the expiration date of the 

construction permit, whichever is less. If the Director has not issued an 

intent to issue an operation permit for the einjectionwell9s) by the end of the 

operational testing period, the permittee shall cease injection. 

Proposed addition: (f) For a Class VI well, if an operation permit has not been 

obtained for the well within two years after the cessation of operational 

testing, the permittee shall submit an application to the Director to plug and 

abandon the well in accordance with Section 146.92. 

Proposed addition: (4) The Director shall conduct periodic inspections during 

construction 

No rationale provided 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment EPA has made many revisions to the GS Rule. Please see the

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

information.

EPA clarifies that the final rule does not require an owner or operator to obtain a separate Class VI
operational testing permit. However, EPA revised §146.82 so that the final regulation specifies

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

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

well is authorized (at §146.82(c)). Final information on injection zone pressures are required

following drilling of the well, at §146.82(c)(4). 

EPA disagrees that the rule needs to specify the qualifications of owner or operator staff creating the

permit submittals. EPA is developing a number of technical guidances and implementation materials

to assist owners or operators and Directors in the permitting process. These guidances will provide

suggestions on how to perform many of the activities necessary for applying for a permit, including

developing all required plans and conducting site characterizations under §146.82. Technical

guidances and implementation materials will be available on EPA's web site, at

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

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22591

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

language; 3560 2.2.3.2 Conditions that merit reevaluation of the AoR (seeking comment) 

Comment: Proposed Rule: 146.82(c) 

Revision or Comment: Proposed Revision: 2(c ) Re-evaluation of Area of Review. 

After completion of the operational testing period, the Area of Review shall be 

re-evaluated, using a calibrated, multi-phase fluid flow model. The data 

collection during operational testing must be adequate for calibration of the 

model. If a calibrated model cannot be prepared using data collected during 

operational testing, the owner or operator shall apply for a new period of 

operational testing of up to two years in order to collect the required data. 

No rationale provided 

Response: EPA agrees that AoR reevaluations should be based on the same type of modeling that is

used to perform the initial delineation, but disagrees that the suggested change is necessary. EPA

clarifies that all AoR modeling (including that which supports reevaluations) should be based on

accepted, verified, and validated scientific methods. Under requirements at §146.84(b), the owner or

operator must demonstrate in the proposed AoR and corrective action plan, to the satisfaction of the

Director that the modeled AoR (and all updates) will be based on detailed geologic data collected on

the site. EPA anticipates that any model that does this in a comprehensive and satisfactory manner

would be approved by the Director.

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22610

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

language 

Comment: Proposed Rule: 146.91 

Proposed addition: (1) Class VI Test/Injection Well Construction Permit 

Proposed addition: (a) The Director shall require periodic data reports and 
progress reports during construction that include: 

Proposed addition: 1. Driller's log 

Proposed addition: 2. Geophysical surveys 

Proposed addition: 3. Core analyses 

Proposed addition: 4. Lithologic logs 

Proposed addition: 5. Drill stem tests 

Proposed addition: 6. Pump tests 

Proposed addition: 7. Daily job (construction) reports 

Proposed addition: 8. Water quality analyses 

Proposed addition: (b) The frequency of reporting shall be specified in the 

individual permit 

Proposed addition: (c ) Interpretation of data is required in the data reports 

or progress reports at the completion of each significant phase of construction, 

such as completion of test well construction and testing, completion of 

injection well construction, and completion of injection well testing. 

Proposed addition: (d) The owner or operator shall submit final reports of all 

data collected from the test injection ell with interpretations to the Director 

with the application for a Class VI Test/Injection Well Construction and Testing 

Permit and a Class VI Injection Well Operation Permit shall include all 

information and data collected under Section 146.87, with appropriate 

interpretations 

Proposed addition: (2) Class VI Operational Testing Permit 

Proposed addition: (a) The owner or operator shall submit, as part of the permit 

application, the proposed methodology for collection and reporting of 

operational data, to ensure that the data is collected, correlated, and reported 

in a fashion that would enable the Director to evaluate well performance. 

Proposed addition: (b) All Class VI wells shall report monthly the following: 

Proposed addition: 1. Operating reports to the Director on: 

Proposed addition: a. The physical, chemical, and other relevant 

characteristics of injection fluids; 

Proposed addition: b. Daily reading of the pressure and flow for each well. For 

each Class VI sequestration well, a specific injectivity test shall be performed 

quarterly; 

Proposed addition: c. Monthly average, maximum and minimum values for injection 

pressure, flow rate and volume, and annular pressure; and 

Proposed addition: d. The results of monitoring prescribed under Section 146.90 

Proposed addition: 2. Reporting the results, within three months after the 
completion of: 

Proposed addition: a. Annular monitoring tests of mechanical integrity; 

Proposed addition: b. Any other test of the injection ell conducted by the 

permittee if required by the Director; and 

Proposed addition: c. Any well work over. 

Proposed addition: (c ) Specific injectivity testing shall be performed while 

the pumping rate to the well(s) has been set at a predetermined level and 

reported as the specific injectivity index (gpm/specific pressure (psig)). As 

part of this test, the well shall be shut-in for a period of time necessary to 

conduct a valid observation of pressure fall-off. The owner or operator shall 

propose which pumping rate will be used based on the expected flow, the design 

of the pump station including the volume of the wet well and pump type(s), and 

the type of pump controls used. The pumping rate(s) shall be included as a 

condition of the operation permit. 

Proposed addition: (d) Re-evaluation of Area of Review. After completion of the 

operatonal testing period, the Area of Review shall be re-evaluated, using a 

calibrated, multi-phase fluid flow model. The data collection during 

operational testing must be adequate for calibration of the model. If a 

calibrated model cannot be prepared using data collected during operational 

testing, the owner or operator shall apply for a new period of operational 

testing of up to two years in order to collect the required data. No more than 

two operational testing permits can be issued for any Class VI well. If the 

recalculated Area of Review includes any relevant wells or penetrations through 

the confining zone that were not reported in the permit application, a new 

tabulation of penetrations as required in Section 146.84(c)(2) and (3) shall be 

provided. Owners or operators must perform corrective action as required in 

Section 146.84(d). 

Proposed addition: (e) If physical or geochemical data such as water quality, 

pressure changes, or mechanical integrity test results indicate that fluid 

movement into or between underground sources of drinking water may be occurring, 

the permittee shall submit additional data to provide reasonable assurance that 

the injection operation is in compliance with the requirements of this chapter. 

This additional data shall be submitted with the periodic operations reports, 

the content and frequency of which are specified in the individual permit. 

Proposed addition: (f) A Class VI well permit shall be written to require that 

if CFR Section 146.14(a) is applicable, progress reports shall be submitted no 

later than thirty days following each interim date and the final date of 

compliance. 

Proposed addition: (3) Class VI Injection Well Operation Permit. 

Proposed addition: (a) The applicant shall submit, as part of the permit 

application, the proposed methodology for collection and reporting of 
operational data, to ensure that the data is collected, correlated, and reported 

in a fashion that would enable the Director to evaluate well performance. 

Proposed addition: (b) All Class VI wells shall report monthly the following: 

Proposed addition: 1. Operating reports to the Director on: 

Proposed addition: a. The physical, chemical, and other relevant characteristics 

of injection fluids; 

Proposed addition: b. Daily readings of the pressure and flow for each well. 

For each Class VI well, a specific injectivity test shall be performed 

quarterly; 

Proposed addition: c. Monthly average, maximum and minimum values for injection 

pressure, flow rate and volume, and annular pressure; and 

Proposed addition: d. The results of monitoring prescribed under Section 146.90 

Proposed addition: 2. Reporting the results, within three months after the 

completion of: 

Proposed addition: a. Periodic tests of mechanical integrity; 

Proposed addition: b. Any other test of the injection well conducted by the 

permittee if required by the Director; and 

Proposed addition: c. Any well work over. 

Proposed addition: (c ) Specific injectivity testing shall be performed while 

the pumping rate to the well(s) has been set at a predetermined level and 

reported as the specific injectivity index (gpm/specific pressure (psig)). As 

part of this test, the well shall be shut-in for a period of time necessary to 

conduct a valid observation of pressure fall-off. The owner or operator shall 

propose which pumping rate will be used based on the expected flow, the design 

of the pump stations including the volume of the wet well and pump type(s), and 

the type of pump controls used. The pumping rate(s) shall be included as a 

condition of the operation permit. 

(d) Re-evaluation of Area of Review. Every five years, the Area of Review shall 

be re-evaluated, using a calibrated, multi-phase fluid flow model. The data 

collection during operation must be adequate for calibration of the model. If a 

calibrated model cannot be prepared using data collected during operation, the 

owner or operator shall, within 90 days, apply for a new operation permit with a 

revised monitoring and testing plan designed to collect the required data. The 

re-issued Class VI operation permit shall be valid for a period of no more than 

two years. After two years of operation under a re-issued operating permit, the 

applicant shall again re- evaluate the Area of Review using a calibrated, multiphase fluid flow model and re-apply for a five-year operating permit. If the 

recalculated Area of Review includes any relevant wells or penetrations whose 
total depth is greater than the depth to the bottom of the lowermost USDW that 

were not reported in the permit application, a new tabulation of penetrations as 

required in Section 146.84(c)(2) and (3) shall be provided. Owners or operators 

must perform corrective action as required in Section 146.84(d) must perform 

corrective action as required in Section 146.84(d). 

No rationale provided 

Proposed Rule: Introductory text to 146.91 and 146.91(a)(1)-(4) 

Revision or comment: Proposed for deletion 

Rationale: Covered in proposed Section 146.91(3) and subsections 

Proposed Rule: 146.91(a)(5) 

Revision or comment: Renumber 3(e) 

Proposed Rule: 146.91(a)(6) 

Revision or comment: Renumber 3(f); delete "and" 

Proposed addition: (g) If physical or geochemical data such as water quality, 

pressure changes, or mechanical integrity test results indicate that fluid 

movement into or between underground sources of drinking water may be occurring, 

the permittee shall submit additional data to provide reasonable assurance that 

the injection operation is in compliance with the requirements of this chapter. 

This additional data shall be submitted with the periodic operations reports, 

the content and frequency of which are specified in the individual permit. 

Proposed addition: (h) A Class VI well permit shall be written to require that 

if CFR Section 146.41(a) is applicable, progress reports shall be submitted no 

later than thirty days following each interim date and the final date of 

compliance. 

No rationale provided 

Proposed Rule: 146.91(a)(7); 146.91(b)(1)-(3) 

Proposed for deletion 

Rationale: Covered in proposed Section 146.91(3) and subsections 

Proposed Rule: 146.91(c) 

Renumber (4) 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach. EPA is developing guidances on
injection well construction and on monitoring and testing that will assist owners or operators and

Directors in performing the pre-operational logging and testing required at §146.86. This guidance

will be available on EPA’s website at

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

As described above, EPA clarifies that the final rule does not require an owner or operator to obtain

a separate Class VI operational testing permit. However, EPA revised §146.82 so that the final

regulation specifies separate requirements for information to be submitted with the permit

application and before well construction is approved (at §146.82(a)) and information to be submitted

before operation of the well is authorized (at §146.82(c)). Final information on injection zone

pressures are required following drilling of the well, at §146.82(c)(4).

Commenter Name: Brianne Metzger Letter ID: 0151

Commenter Organization: Spectra Energy Corp Comment ID: 21823

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit

information (40 CFR 146.82) 

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. 

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: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality

(MDEQ)

Comment ID:

22118

Other EPA Comment Codes and Descriptions: 3700 2.2.5 Comments on the requirement for an

AoR and corrective action plan; 4610 2.6.1 Testing and monitoring plan requirement (seeking

comment) 

Comment: 17. EPA seeks comment on the merits of requiring plans for monitoring, area of 

review and post-injection site care as part of a permit application. MDEQ agrees 

that this is necessary and appropriate. A"cradle-to-grave" approach is wise in 

this instance and allows for updating the permit application materials as new 

technologies are forthcoming. 

Response: EPA acknowledges the commenter’s support of the GS project plans. 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 for owners or operators describing recommended approaches to

prepare the project plans. The guidances will be available on EPA's web site, at

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

On the topic of monitoring and plan revision: EPA agrees with commenters on the importance of

monitoring at GS sites and emphasizes that monitoring of injection activities will be an important

component of every GS project. EPA also believes that periodic updates to the plans are appropriate.

EPA clarifies that the final GS regulation includes a requirement that the AoR be reevaluated at least

every 5 years, and it specifies at §146.90(j) that the operator revise the testing and monitoring plan to

incorporate the results of the most recent AoR reevaluation and recent operational and monitoring

data.

EPA agrees that incorporating the plans into the permit rather than establishing specific requirements

for corrective action, monitoring, injection well plugging, and post-injection site care in the

regulation provide the appropriate flexibility to address the variety of site-specific conditions that

may be encountered at GS sites. This approach is retained in the final rule. Please see the final rule

and the discussion of the required GS project plans in the preamble for additional information.

EPA also believes that it is appropriate to require owners and operators to submit all plans, including

the injection well plugging and post-injection site care and site closure plans, at the time of permit

application. EPA believes that the Director needs a satisfactory level of assurance that the owner or

operator has planned for these events before injection commences and that the owner or operator has

ensured that appropriate financial resources are available to fund all required activities, as required at

§146.85. The final rule retains requirements for submitting these plans with the permit application at

§146.82(a). EPA believes that the requirement for this and other plans associated with GS projects

will promote an ongoing dialogue between the owner or operator and the Director to ensure USDWs

are protected from endangerment. In addition, these plans will support a demonstration that owners

and operators have adequate financial resources to meet well plugging and post-injection site care

and site closure requirements.

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22636

Other EPA Comment Codes and Descriptions: 3420 2.2.2.1 Scope of the inventory process (e.g.,
reliance on publicly available information, depth of wells) 

Comment: All Wells and "All Known Wells" are not the Same Page 43507 and 43517. The 

proposed Class VI rule needs to be much more precise in its use of language in a 

couple of key areas. The rule requires an applicant for a Class VI permit to 

"identify all artificial penetrations." What exactly does this mean? Is it all 

known artificial penetrations (the rule speaks to the operator "review(ing) 

available information")? What is the test for what is a known well or available 

information (does it require detailed field surveys or does one only need to do 

a quick search of a database of wells drilled in the area)? If on the other 

hand it means literally all human penetrations, then one must ask if this is 

technologically possible (e.g., are there technologies which would allow for the 

identification of a small diameter non-steel walled well that has no visible 

surface features)? Is there a danger in asking for something that can not 

actually be delivered? One can guess what was likely meant by "identify all 

artificial penetrations" in terms of drafting this rule but it is not at all 

clear how this would be opperationalized at actual prospective GS sites. 

More importantly on Page 43535 under "144.55 Corrective Action", the rule says 

that owners/operators need to identify the location of "all known wells" which 

seems to be a lesser standard. In the actual text of the rule (page 43526), the 

applicant is told "Only information of public record is required to be included 

on this map." Given how many times the rule and its preamble talk about old 

wells being a potential conduit for CO2 release from the storage formation, this 

seems like an overly lax threshold. It would seem appropriate to require the 

applicant survey the actual site itself for artificial penetrations that might 

not be in the public record (the survey could include a number of different 

methods / tools). Further on in this section, the applicant is asked to submit 

a "tabulation of all wells within the area of review which penetrate the 

injection or confining zones." Again, "all wells" and "all known wells" and how 

much work does one need to do to determine if they have tried to find "all the 

wells" must be better articulated in the final rule. This same kind of language 

shows up on page 43537 within the discussion of the Area of Review and 

Corrective Action. 

Lastly, given the large amounts of money involved in a commercial CO2 storage 

project, I would think that the electric production, oil and gas, or other large 

industrial company contemplating a large CCS-enabled facility would want (or be 

required) to go beyond simply collecting existing data as a way of decreasing 

risk and uncertainty. In this context, the proposed "requirement" for going 

beyond existing data could be imposed by entities other than state or federal 

environmental regulators and could be imposed by shareholders, a public utility 

commission, or a firm’s own board of directors. In terms of abandoned wells, it 

seems likely that commercial firms would see it to be in their own best interest 

to do some kind of physical search / assessment of whether there are any known 

or unknown wells within the area of review given the relatively minor cost 

associated with something like an aerial magnetic survey versus the costs 

associated with loss of CO2 and any fines, the cost associated with any required 

post-leakage activities, or simply the cost of litigation and or loss of good 

will associated with such sloppy management of a critical, capital intensive 

pollution abatement facility. 
Response: EPA believes that, for the most part, data base and other public records searches will be

sufficient to identify artificial penetrations in the AoR. This inventory and review process is similar

to what is required of Class I and Class II injection well operators, that that the AoR and corrective

action process for these well types has been successful. 

EPA is developing guidance on AoR and corrective action for GS sites. The guidance describes

EPA's recommended approaches for the data to be considered in an initial AoR delineation, how to

apply computational modeling to delineate the AoR, performing corrective action at GS sites, and,

when appropriate, completing AoR reevaluations. The guidance will be available on EPA's web site,

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

EPA agrees with commenters that, for most GS sites, relying on database and other public records

searches (i.e., of "known" artificial penetrations) will be sufficient to meet the requirements at

§146.84(c)(2). However, the Agency recognizes that there may be situations where additional

surveys or research to locate wells may be appropriate. For example, there may be cases where the

Director may determine that ground or airborne surveys for wells are appropriate, e.g., if there is

reason to believe, based on knowledge of the site or of available data, that the incompleteness of

information on known wells could compromise USDW protection from endangerment. In order to

preserve the Director's discretion to require an operator to supplement a records search, EPA did not

make the suggested change. EPA encourages owners or operators to expand their searches, as the

commenter suggests. EPA adds that all corrective action must be performed pursuant to the approved

AoR and corrective action plan, which affords the Director the discretion to require any additional

information needed (including information that is not publically available) to ensure that all

necessary corrective action is performed. 

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22637

Comment: In this same section (page 43526), the applicant is asked to submit information 

on "the presence and depth of seismic sources" but this falls under a heading 

that is limited to the "proposed storage site and overlying formations." So if 

a proposed GS site sat 10 cm, 10m or 10km north of any aspect of the New Madrid 

Fault, that would not be noted in the application. Limiting the scope of data 

collection to the boundaries of the project site might not be appropriate for 

data related to "the presence and depth of seismic sources" 

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: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23787

Comment: EPA is proposing that permit applications for GS sites include several plans not 

currently required under existing UIC regulations. These plans include a 
monitoring and testing plan, an AoR and corrective action plan, and a postinjection site care and site closure plan. EPA seeks comment on the merits of 

requiring plans for monitoring, AoR, and post-injection site care as part of a 

permit application. EPA Notice 112. 

We believe that requiring a monitoring plan is reasonable. However, the EPA 

should develop such requirements with recognition of a distinct end to 

operations and monitoring following closure, and consider specific 

representations and codicils that recognize an end of "in-perpetuity" 

responsibility for the operator or owner. 

Response: EPA clarifies that the owner or operator's approved testing and monitoring plan and postinjection site care and site closure plan will be incorporated as a condition of the Class VI permit.

Class VI well operators will be required to perform monitoring pursuant to the plans throughout the

life of the facility (i.e., the duration of the Class VI permit). EPA adds that §146.93(b) requires

operators to perform post-injection site monitoring until it can be demonstrated that the CO2 and

pressure front no longer pose a risk of endangerment to USDWs. EPA notes that the post-injection

monitoring may be different from monitoring that occurs during the operational phase. Once this

demonstration is made, site closure may be authorized and monitoring is no longer required. EPA

adds that owners or operators must maintain financial responsibility until site closure has been

authorized.

Please see the final rule and preamble, including the discussion of post-injection site care monitoring

and financial responsibility for additional information.

Commenter Name: Michael J. Miller Letter ID: 0168

Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22509

Comment: Preamble, page 43517: "EPA seeks comment on the merits of requiring plans for 

monitoring, AoR, and post-injection site care as part of a permit application." 

EPRI COMMENT #15: Submitting a monitoring and AoR plan with the application 

seems practical since these activities will occur in the reasonably near future 

after the permit is issued. However, requiring too much specificity in a postinjection site care plan as part of the permit application may cement in methods 

that will be obsolete by the time the GS project enters the post-injection 

phase, 20-50 years from the permit date. EPA could instead require that a 

preliminary post-injection site care plan be submitted at the time of 

application outlining the general approach and parameters needed to demonstrate 

closure, and that a final detailed plan be prepared for approval a certain 

period of time prior to implementation of this phase. 

Preamble, page 43518: "Today’s proposal would require owners or operators to 

submit a well plugging plan at the same time the permit application is submitted 

and to have this plan approved by the Director." 

EPRI COMMENT #16: Again, well plugging and abandonment are activities that take 

place far in the future, perhaps several decades off. Therefore, submitting 

this plan at the time of permit application could render it obsolete when 

implementation is needed. EPA could instead require a preliminary plan 
outlining the general approach at the time of application and require that a 

final detailed plugging and abandonment plan be submitted for approval a certain 

period of time prior to implementation of this activity, allowing for the 

incorporation and use of new/better technologies. 

Response: EPA believes that incorporating the plans into the permit rather than establishing specific

requirements for corrective action, monitoring, injection well plugging, and post-injection site care in

the regulation provide the appropriate flexibility to address the variety of site-specific conditions that

may be encountered at GS sites. 

EPA also believes that it is appropriate to require owners and operators to submit all plans, including

the injection well plugging and post-injection site care and site closure plans, at the time of permit

application. EPA believes that the Director needs a satisfactory level of assurance that the owner or

operator has planned for these events before injection commences and that the owner or operator has

ensured that appropriate financial resources are available to fund all required activities, as required at

§146.85. The final rule retains requirements for submitting these plans with the permit application at

§146.82(a). EPA believes that the requirement for this and other plans associated with GS projects

will promote an ongoing dialogue between the owner or operator and the Director to ensure USDWs

are protected from endangerment. In addition, these plans will support a demonstration that owners

and operators have adequate financial resources to meet well plugging and post-injection site care

and site closure requirements.

EPA recognizes that the injection well plugging and post-injection site care and site closure plans

may need to be modified when injection ceases, as well as prior to site closure, which is why

§146.92(c) and §146.93(a) require review of these plans to ascertain whether the plan needs to be

modified. EPA notes that §144.39 and §144.41 contain requirements regarding permit modifications

that may be triggered as a result of these plan modifications. 

Please see the final rule and the discussion of the Class VI project plans in the preamble for

additional information.

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23407

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit

information (40 CFR 146.82) 

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

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: 24151

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

language; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

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.

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: 24152

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

language; 3100 2.1 Proposed Geologic Siting Requirements (40 CFR 146.83) 

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)).

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: 24153

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

language; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

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. 

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

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.

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

Comment: Rule Provision: 146.82(h) 

API Comments: (h) Proposed operating data: (1) Average and maximum daily 

INJECTION rate and volume of the carbon dioxide stream; (2) Average and maximum 

SURFACE injection pressure; 

Rationale: Technical clarifications. 

Rule Provision: 146.82(k) 

API Comments: (k) Proposed stimulation program and a determination that 

stimulation will not interfere with containment;

Rationale: This responsibility is best left with EPA. 

Rule Provision: 146.82(n) 

API Comments: (n) A WELLBORE schematic or other appropriate drawings of the 

surface and of the subsurface construction details of the well AND SURFACE 

WELLHEAD CONSTRUCTION. 

Rationale: Technical clarification. 

Rule Provision: 146.82(q) 

API Comments: q) The ANY status of corrective action on wells in the area of 

review; 

Rationale: Clarifies that wells not needing corrective action will not have a 

corrective action status. 

Response: EPA acknowledges the commenter’s support for parts of the requirements under 146.82.

EPA disagrees with suggested technical clarifications regarding proposed operating data, needs for

the stimulation program, and the status of corrective action. EPA adds that it is developing guidance

for owners or operators on the geologic site characterization, AoR, and corrective action processes.

These guidances will provide recommendations and clarify the intent of all required elements of a

permit application. The guidances 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: 24251

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan

requirement (seeking comment) 

Comment: Rule Provisions: 146.90, 146.93(a), 146.94(a) 

EPA Preamble Question: 34. EPA is proposing that permit applications for GS 

sites include several plans not currently required under existing UIC 

regulations. These plans include a monitoring and testing plan, an AoR and 

corrective action plan, and a post-injection site care and site closure plan. 

EPA seeks comment on the merits of requiring plans for monitoring, AoR, and 

Post-injection site care as part of a permit application. EPA Notice 43517. 

API Response: The development of such plans is a good idea because it negates 

prescriptive regulation of the process. API is concerned that every modification 

of a plan may trigger a major permit modification. Although actual monitoring of 

injection formation is most effective, there is still the unintended consequence 

of penetrating the confining zone to gain that data. The number of monitoring 

wells should not be established in advance. It is unclear how monitoring well 

construction, operation, and closure will be regulated since these are not 

actual injection wells. 

Timing of development of plans should be linked to the actual activity being 

addressed (i.e. staged). It should not be necessary to prepare and submit a site 

closure plan or the post-closure monitoring plan at the start of the project, 

particularly considering that these activities will not occur for many years 

after the project starts. 

Response: EPA agrees with commenters that developing and following testing and monitoring plans

is an important part of assuring that a GS project is operating properly and is crucial for the early

detection of potential endangerment to USDWs. EPA expects that the number of monitoring wells

needed will be determined based on site-specific information. EPA also agrees that periodic updates

to the plan are appropriate. EPA clarifies that the final GS regulation includes a requirement that the

AoR be reevaluated at least every five years, and it specifies at §146.90(j) that the operator revise the

testing and monitoring plan to incorporate the results of the most recent AoR reevaluation and recent

operational and monitoring data.

EPA believes that monitoring using wells in the injection zone, e.g., for pressure monitoring as

required at §146.90(g)(1), can be safely performed if the wells are constructed to prevent flow

between the injection zone and USDWs or other layers above the confining zone. Such construction

technologies exist and have been used in the oil and gas industry for years. The testing and

monitoring plan must describe how the owner or operator plans to site and construct monitoring

wells. EPA is developing guidance on well construction that will include recommendations for

monitoring well construction. The guidance will be available on EPA’s website at

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

EPA clarifies that every revision to the testing and monitoring plan will not necessarily trigger a

major permit modification. The existing regulation at 40 CFR 144.39(a) identifies causes for

modification of permits that would invoke the public notification procedures at 40 CFR 124. In the

final rule, EPA added text to §144.39(a)(5) that permit modifications would be required if the
Director determines that a modification is necessary based on an AoR reevaluation, amendments to

any of the project plans, or a review of the testing and monitoring results. 

In addition, 40 CFR Part 144.41 identifies causes for minor modifications of permits (which do not

require following the procedures of Part 124). In the final rule, EPA added a subparagraph (h) to

§144.41 that would include minor amendments (e.g., to clarify, correct, or update) to the testing and

monitoring plan, plugging plan, post-injection site care and site closure plan, or emergency and

remedial response plan for a GS well (i.e., amendments that are not included under 144.39(a)(5) and

that do not require additional permit requirements). 

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in

evaluating requirements under §146.90. The guidance can be found on EPA’s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. In addition, in January 2009,

DOE published a best practices manual entitled "Monitoring, Verification, and Accounting of CO2

Stored in Deep Geologic Formations" (DOE/NETL-311/081508); this manual is included in the

docket for the final GS rule. EPA notes that closure of monitoring wells should be addressed in the

post-injection site care and site closure plan.

EPA also believes that it is appropriate to require owners and operators to submit all plans, including

the injection well plugging and post-injection site care and site closure plans, at the time of permit

application. EPA believes that the Director needs a satisfactory level of assurance that the owner or

operator has planned for these events before injection commences and that the owner or operator has

ensured that appropriate financial resources are available to fund all required activities, as required at

§146.85. The final rule retains requirements for submitting these plans with the permit application at

§146.82(a).

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23500

Comment: 11. Permit Application and Reporting Requirements 

The Proposal would impose a number of requirements on Class VI permit 

applications that are not currently required under the existing UIC regulations, 

most notably the mandatory inclusion of a monitoring and testing plan, an AoR 

and corrective action plan, and a post-injection site care and site closure 

plan. Id. at 43517. For many of these requirements, there do not appear to be 

concrete risks particular to CO2 GS that would warrant these additional 

measures. 

USWAG is particularly concerned that the level of detail that would be required 

for Class VI permit applications is overly burdensome and unnecessary. A great 

deal of this information may be unavailable - or could be speculative at best - 

because of a lack of information at the early stages in the application process; 

an ongoing requirement for submission of this information over time, as it 

becomes available through drilling and operation of the well, would be of 

greater practical use and would lead to collection of more accurate data. 

Response: EPA believes that the unique characteristics of CO2 injection (e.g., its relative buoyancy,

the large volume that may be injected, or the potential for chemical interaction with the subsurface)

warrant the additional information required to be submitted by GS operators under §146.82. All of
the tailored requirements of the GS rule are necessary to protect USDWs from endangerment;

therefore Directors must have all site-specific data listed under §146.82 to make well-informed

decisions when establishing permit conditions and granting permits.

In response to concerns that some data will not be available until the well has been drilled, EPA

acknowledges that not all of the information listed at §146.82 of the proposed regulation would be

available at the time the owner or operator develops the permit application. Based on comments and

evaluation of the proposed requirements, EPA revised this subpart so that the final regulation

specifies separate requirements for information to be submitted for approval with the permit

application before well construction, as required at §146.82(a), and information to be submitted after

the well is constructed yet before injection is authorized, as required at §146.82(c).

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23839

Other EPA Comment Codes and Descriptions: 5100 2.8.1 Injection well plugging activities

(seeking comment) (40 CFR 146.92) 

Comment: A. WELL PLUGGING PLAN 

EPA's Proposed Rule would require owners and operators to develop a well 

plugging plan to be approved by the Director as part of each permit application. 

Such a plan would include: (1) a determination of bottom-hole reservoir 

pressure; (2) the identification of type and numbers of plugs to be used; (3) 

the placement of each plug; (4) testing methods to ensure mechanical integrity 

testing ("MIT"); (5) the method of plug placement; and (6) the type, grade and 

quantity of material to be used in plugging. By not mandating specific types, 

materials, or testing methods, EPA is giving applicants broad flexibility to 

accommodate the varying types of GS projects contemplated by this rulemaking. 

The CCS Alliance agrees with this approach. Such flexibility also accounts for 

the fact that supercritical CO2 has different properties than current injectants 

under the UIC program and, therefore. may require different plugging methods and 

materials. For instance, cement plugs can degrade over time from the build up of 

carbonic acid, which forms when CO2 is injected in subsurface formations 

containing brine. However. well integrity should be considered the function of 

well materials collectively in maintaining a fluid barrier (as opposed to 

individual components susceptibility, particularly from laboratory tests). 

Response: EPA agrees with commenters that a flexible approach is appropriate for GS wells. The

GS rule does not prescribe the specific cements to be used to plug injection wells because industry

standards, such as those developed by API or ASTM International, reflect the current state of the

science and the expertise of industrial users on CO2-compatible materials, as specified in

§146.92(b). Providing flexibility to choose materials for plugging, provided they are compatible with

the injected fluid, is consistent with requirements for other injection well classes and will allow

operators to utilize improved well technologies as they become available in the future without a need

to amend the regulation.

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23840

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking
comment) (40 CFR 146.93) 

Comment: B. POST-INJECTION SITE CARE PLAN 

The Proposed Rule would require that owners or operators develop a postinjection site care and closure plan, submitted as part of the permit 

application and approved by the Director. The proposed regulation at 40 C.F.R. $ 

146.93 would require the plan to describe: (1) the pressure differential between 

pre-injection and anticipated post-injection pressures in the injection zone; 

(2) predicted position of the plume and associated pressure front at the time 

the site is closed; (3) post-injection monitoring location(s), methods, and 

proposed frequency of monitoring; and (4) a schedule for submitting postinjection site care and monitoring results to the Director. 

These requirements are reasonable given the long-term nature of GS projects. The 

CCS Alliance also supports the ability to amend the plan should the plan no 

longer reflect what is likely to occur upon closing the site. Likewise, the CCS 

Alliance agrees that, upon permanent cessation of injection, the owner or 

operator should be provided the opportunity to demonstrate that no amendment to 

the plan is necessary through monitoring and modeling results. 

Response: EPA agrees that a post-injection site care monitoring plan is an important tool for GS,

and retains this requirement in the final rule, at 146.93(a). Regarding updates to the plan, EPA is

requiring that upon the cessation of injection, the owner or operator submit an amended postinjection site care and site closure plan or demonstrate to the Director that no changes to the original

post-injection site care and site closure plan are necessary, as specified in §146.93(a)(3). EPA is not

requiring formal periodic review and updates to the PISC and site closure plan throughout the

injection phase. EPA does not expect that changes to this plan would be implemented until injection

operations cease.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23654

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit

information (40 CFR 146.82) 

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

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: 3150 2.1.5 Comments on required permit

information (40 CFR 146.82) 

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: 23708

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial

responsibility requirements (40 CFR 146.85) 

Comment: AWWA questions whether it would be acceptable for energy companies and 

owner/operators to bond projects as a way to demonstrate financial assurance. 

AWWA recommends that EPA develop formal technical, managerial, and financial 

requirements for carbon sequestration projects that owner/operators must meet 

and maintain. This should be tied to the permitting process as these 

requirements must be demonstrated prior to the operating permit being issued. 

Demonstrating ongoing technical, managerial, and financial capabilities would be 

an important component of the five-year permitting review process that AWWA is 

recommending. 

Response: EPA agrees that financial responsibility demonstrations should be part of the permitting

process for Class VI wells. As a result, the rule requires owners or operators to demonstrate adequate

financial responsibility for all required activities with their permit application, per §146.82(a)(14). 

EPA is developing guidance on financial responsibility for Class VI wells. The guidance will include

a discussion on how best to estimate costs to assist GS well owners or operators, third party insurers

or providers of financial instruments, and permitting authorities in developing estimates of the costs

associated with various GS activities. This guidance will be available on EPA's website at

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

Commenter Name: Bradley J. Field Letter ID: 0186

Commenter Organization: New York State Dept. of Environmental Conservation

Div. of Mineral Resources

Comment ID:

25207

Comment: II. EPA seeks comment on the merits of requiring plans for monitoring, AoR, and 

post-injection site care as part of a permit application. 

NYSDEC-DMN Response: NYSDEC-DMN believes monitoring and testing plans, an AoR 

and corrective action plan, and a post-injection site care and site closure plan 

are integral components of any GS application, and should be required by the 

EPA. 

Response: EPA agrees that incorporating the plans into the permit rather than establishing specific

requirements for corrective action, monitoring, injection well plugging, and post-injection site care in

the regulation provide the appropriate flexibility to address the variety of site-specific conditions that

may be encountered at GS sites. 

EPA also believes that it is appropriate to require owners and operators to submit all plans, including

the injection well plugging and post-injection site care and site closure plans, at the time of permit

application. EPA believes that the Director needs a satisfactory level of assurance that the owner or

operator has planned for these events before injection commences and that the owner or operator has

ensured that appropriate financial resources are available to fund all required activities, as required at

§146.85. The final rule retains requirements for submitting these plans with the permit application at
§146.82(a). EPA anticipates that the requirement for this and other plans associated with GS projects

will promote an ongoing dialogue between the owner or operator and the Director to ensure USDWs

are protected from endangerment and the owner or operator is complying the Class VI permit. In

addition, these plans will support a demonstration that owners and operators have adequate financial

resources to meet well plugging and post-injection site care and site closure requirements. Please see

the final rule and the discussion of the GS project plans in the preamble for additional information.

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; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

Comment: Rule Provision: 146.82(b) 

Proposed CCS Group Recommendations: (b) A SURFACE map showing the PROPOSED 

LOCATIONS FOR the injection well(s) for which a permit is sought and the 

applicable area of review. Within the area of review, the map must show the 

number, or name and location of all KNOWN injection wells, producing wells, 

abandoned wells, plugged wells or dry holes, deep stratigraphic boreholes, State 

or EPA approved subsurface cleanup sites, surface bodies of water, springs, 

mines (surface and subsurface), quarries, water wells and other pertinent 

surface features including structures intended for human occupancy and roads. 

The map should also show faults, if known or suspected. Only information of 

public record is required to be included on this map; 

Basis for CCS Group Comments: Faults are not shown on maps unless there is a 

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: 24414

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

language; 3100 2.1 Proposed Geologic Siting Requirements (40 CFR 146.83) 

Comment: Rule Provision: 146.82(c) 

Proposed CCS Group Recommendations: (c) A MAP DELINEATING the area of review 

based on UPON modeling, using ALL AVAILABLE data INCLUDING DATA obtained 

during logging and testing of the well and the formation as required by 

paragraphs (l), (r), and (s) of this section ANY WELLS IN THE AREA OF REVIEW 

Basis for CCS Group Comments: This appears to be related to a condition where a 

well is already drilled. This does not align with requesting information to 

receive a permit. 

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation

will be available at the time the owner or operator develops their initial permit application. In

response to comments and based on an evaluation of the proposed requirements at §146.82, the

Agency revised this 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: 24415

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule
language; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

Comment: Rule Provision: 146.82(d) 

Proposed CCS Group Recommendations: (d) KNOWN information on the geologic 

structure and hydrogeologic RESERVOIR properties of the proposed storage 

site and overlying formations, including: 

(1) ISOPACH maps and OF THE PROPOSED INJECTION AND CONFINING ZONE(S), A 

STRUCTURAL CONTOUR MAP HUNG ON THE TOP OF THE PROPOSED INJECTION

ZONE, AND AT 

LEAST TWO GEOLOGIC cross sections of the area of review SHOWING THE GEOLOGIC 

FORMATIONS FROM THE SURFACE TO TOTAL DEPTH. 

(2) Location, orientation, and properties of known or suspected SUBSURFACE 

faults and fractures that may transect the confining zone(s) in the area of 

review and a determination that they would not interfere with containment; 

Basis for CCS Group Comments: If the information is not known, it cannot be 

reported. 

"Reservoir" and changes to (1) and (2) are technical corrections. 

Fractures generally can't be identified until a well is drilled and evaluated. 

Even then, only fractures in the immediate vicinity of the well bore can be 

identified. 

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

characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit

data on known or suspected faults and fractures (i.e., not all fractures). Other requirements for GS

injection wells and sites can mitigate the potential impacts of unidentified fractures. These include

limitations on injection pressures to avoid propagation of existing fractures in the confining zone

(§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; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

Comment: Rule Provision: 146.82(d)(3) 
Proposed CCS Group Recommendations: (3) Information on seismic history THAT HAVE 

AFFECTED THE PROPOSED AREA OF REVIEW, INCLUDING KNOWLEDGE OF PREVIOUS

SEISMIC 

EVENTS, including the presence and depth of seismic sources and a determination 

that the seismicity would not interfere with containment; 

Basis for CCS Group Comments: Information on seismic history should have some 

degree of relevance to the project. 

Response: EPA believes that consideration of local and regional seismicity is important and this

type of review is relevant to every project. The site characterization provisions in the GS rule,

including a review of the local and regional geology, and detailed review of any known or potential

seismically active terrain in the vicinity of a proposed GS site, are necessary to minimize the

potential for induced seismic events or the reactivation of faults, which are a known potential risk

associated with underground injection and are addressed in all aspects of the UIC regulations.

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; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

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).

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; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

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

Comment: Rule Provision: 146.82(e) 
Proposed CCS Group Recommendations: (e) A tabulation RECORD of all wells

ARTIFICIAL PENETRATIONS within the area of review which penetrate THAT REACH 

the injection or confining zone(s). Such data AS AVAILABLE IN THE PUBLIC RECORD 

must include a description of each well’s PENETRATION’S type, construction, 

date drilled, location, depth, record of plugging and/ or completion, and any 

additional information the Director may require; 

Basis for CCS Group Comments: "Artificial penetrations" is a more inclusive 

term. 

Rule Provision: 146.82(f) 

Proposed CCS Group Recommendations: (f) Maps and stratigraphic cross sections 

indicating the general vertical and lateral limits of all USDWs, water wells and 

springs within the area of review, their positions relative to the injection 

zone(s) and the direction of water movement, where known; POTENTIOMETRIC 

(WATER LEVEL) SURFACE MAP(S) OF EXISTING AQUIFERS BEING UTILIZED AS

PRIVATE OR 

PUBLIC WATER SUPPLIES AND THE DIRECTION OF GROUNDWATER FLOW IN THESE

AQUIFERS 

WITHIN THE AREA OF REVIEW. AT LEAST TWO GEOLOGIC CROSS SECTIONS

SHOWING THE 

THICKNESS AND GENERAL VERTICAL AND LATERAL LIMITS OF ALL USDWS WITHIN

THE AREA 

OF REVIEW. 

Basis for CCS Group Comments: This revision more accurately identifies the 

information that is needed and should be considered for permitting. 

Rule Provision: 146.82(g) 

Proposed CCS Group Recommendations: (g) Baseline geochemical data on 

subsurface formations, including all USDWs in the area of review COMPILATION 

OF AVAILABLE GEOCHEMICAL DATA ON THE PROPOSED INJECTION ZONE AND

NEAREST POROUS 

AND PERMEABLE FORMATION ABOVE THE CONFINING ZONE. 

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. 

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

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 

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: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24543

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan

requirement (seeking comment) 

Comment: Rule Provisions or Federal Register Cite: 146.90, 146.93(a), 146.94(a) 

EPA Preamble Question: 34. EPA is proposing that permit applications for GS 

sites include several plans not currently required under existing UIC 

regulations. These plans include a monitoring and testing plan, an AoR and 

corrective action plan, and a post-injection site care and site closure plan. 

EPA seeks comment on the merits of requiring plans for monitoring, AoR, and 

post-injection site care as part of a permit application. EPA Notice 43517. 

CSC Response: The development of such plans is a good idea because it negates 

prescriptive regulation of the process. CSC is concerned that every modification 

of a plan may trigger a major permit modification, although it does not appear 
that current regulations would require that result. If major permit 

modifications were required, EPA would lose the adaptability desired for 

responding to experience gained from GS projects. 

It is unclear how the construction, operation, and closure of any monitor wells 

would be regulated, since these are not actual injection wells. 

Timing of development of plans should be linked to the actual activity being 

addressed (i.e. staged). It should not be necessary to prepare and submit a site 

closure plan or the post-closure monitoring plan at the start of the project, 

particularly considering that these activities will not occur for many years 

after the project starts. 

Response: EPA agrees with commenters that developing and following testing and monitoring plans

is an important part of assuring that a GS project is operating properly and is crucial for the early

detection of potential endangerment to USDWs. EPA expects that the number of monitoring wells

needed will be determined based on site-specific information. EPA also agrees that periodic updates

to the plan are appropriate. EPA clarifies that the final GS regulation includes a requirement that the

AoR be reevaluated at least every five years, and it specifies at §146.90(j) that the operator revise the

testing and monitoring plan to incorporate the results of the most recent AoR reevaluation and recent

operational and monitoring data.

EPA clarifies that every revision to the testing and monitoring plan will not necessarily trigger a

major permit modification. The existing regulation at 40 CFR 144.39(a) identifies causes for

modification of permits that would invoke the public notification procedures at 40 CFR 124. In the

final rule, EPA added text to §144.39(a)(5) that permit modifications would be required if the

Director determines that a modification is necessary based on an AoR reevaluation, amendments to

any of the project plans, or a review of the testing and monitoring results. 

In addition, 40 CFR Part 144.41 identifies causes for minor modifications of permits (which do not

require following the procedures of Part 124). In the final rule, EPA added a subparagraph (h) to

§144.41 that would include minor amendments (e.g., to clarify, correct, or update) to the testing and

monitoring plan, plugging plan, post-injection site care and site closure plan, or emergency and

remedial response plan for a GS well (i.e., amendments that are not included under 144.39(a)(5) and

that do not require additional permit requirements). 

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in

evaluating requirements under §146.90. The guidance can be found on EPA’s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. In addition, in January 2009,

DOE published a best practices manual entitled "Monitoring, Verification, and Accounting of CO2

Stored in Deep Geologic Formations" (DOE/NETL-311/081508); this manual is included in the

docket for the final GS rule. EPA notes that closure of monitoring wells should be addressed in the

post-injection site care and site closure plan.

EPA also believes that it is appropriate to require owners and operators to submit all plans, including

the injection well plugging and post-injection site care and site closure plans, at the time of permit

application. EPA believes that the Director needs a satisfactory level of assurance that the owner or

operator has planned for these events before injection commences and that the owner or operator has

ensured that appropriate financial resources are available to fund all required activities, as required at

§146.85. The final rule retains requirements for submitting these plans with the permit application at
§146.82(a).

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24604

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan

requirement (seeking comment) 

Comment: Rule Provisions: 146.90, 146.93(a), 146.94(a) 

EPA Rule Issue: 34. EPA is proposing that permit applications for GS sites 

include several plans not currently required under existing UIC regulations. 

These plans include a monitoring and testing plan, an AoR and corrective action 

plan, and a post-injection site care and site closure plan. EPA seeks comment on 

the merits of requiring plans for monitoring, AoR, and postinjection site care 

as part of a permit application. EPA Notice 43517. 

Anadarko Petroleum Corporation (APC) Response: The development of plans is a 

good idea because it negates prescriptive regulation of the process. APC is 

concerned that every modification of a plan may trigger a major permit 

modification. Although actual monitoring of injection formation is most 

effective, there is still the unintended consequence of penetrating the 

confining zone to gain that data. The number of monitoring wells should not be 

established in advance. It is unclear how monitoring well construction, 

operation, and closure will be regulated since these are not actual injection 

wells. 

Timing of development of plans should be linked to the actual activity being 

addressed. It should not be necessary to prepare and submit a site closure plan 

or the post-closure monitoring plan at the start of the project, particularly 

considering that these activities will not occur for many years after the 

project starts. 

Response: EPA agrees with commenters that developing and following testing and monitoring plans

is an important part of assuring that a GS project is operating properly and is crucial for the early

detection of potential endangerment to USDWs. EPA expects that the number of monitoring wells

needed will be determined based on site-specific information. EPA also agrees that periodic updates

to the plan are appropriate. EPA clarifies that the final GS regulation includes a requirement that the

AoR be reevaluated at least every five years, and it specifies at §146.90(j) that the operator revise the

testing and monitoring plan to incorporate the results of the most recent AoR reevaluation and recent

operational and monitoring data.

EPA believes that monitoring using wells in the injection zone, e.g., for pressure monitoring as

required at §146.90(g)(1), can be safely performed if the wells are constructed to prevent flow

between the injection zone and USDWs or other layers above the confining zone. Such construction

technologies exist and have been used in the oil and gas industry for years. The testing and

monitoring plan must describe how the owner or operator plans to site and construct monitoring

wells. EPA is developing guidance on well construction that will include recommendations for

monitoring well construction. The guidance will be available on EPA’s website at

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

EPA clarifies that every revision to the testing and monitoring plan will not necessarily trigger a
major permit modification. The existing regulation at 40 CFR 144.39(a) identifies causes for

modification of permits that would invoke the public notification procedures at 40 CFR 124. In the

final rule, EPA added text to §144.39(a)(5) that permit modifications would be required if the

Director determines that a modification is necessary based on an AoR reevaluation, amendments to

any of the project plans, or a review of the testing and monitoring results. 

In addition, 40 CFR Part 144.41 identifies causes for minor modifications of permits (which do not

require following the procedures of Part 124). In the final rule, EPA added a subparagraph (h) to

§144.41 that would include minor amendments (e.g., to clarify, correct, or update) to the testing and

monitoring plan, plugging plan, post-injection site care and site closure plan, or emergency and

remedial response plan for a GS well (i.e., amendments that are not included under 144.39(a)(5) and

that do not require additional permit requirements). 

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in

evaluating requirements under §146.90. The guidance can be found on EPA’s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. In addition, in January 2009,

DOE published a best practices manual entitled "Monitoring, Verification, and Accounting of CO2

Stored in Deep Geologic Formations" (DOE/NETL-311/081508); this manual is included in the

docket for the final GS rule. EPA notes that closure of monitoring wells should be addressed in the

post-injection site care and site closure plan.

EPA also believes that it is appropriate to require owners and operators to submit all plans, including

the injection well plugging and post-injection site care and site closure plans, at the time of permit

application. EPA believes that the Director needs a satisfactory level of assurance that the owner or

operator has planned for these events before injection commences and that the owner or operator has

ensured that appropriate financial resources are available to fund all required activities, as required at

§146.85. The final rule retains requirements for submitting these plans with the permit application at

§146.82(a).

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; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

Comment: Rule Provision: 146.82(b) 

Anadarko Petroleum Corporation (APC) Comments: (b) A surface map showing the 

PROPOSED LOCATIONS FOR the injection well(s) for which a permit is sought and 

the applicable area of review. Within the area of review, the map must show the 

number, or name and location of all KNOWN injection wells, producing wells, 

abandoned wells, plugged wells or dry holes, deep STRATAGRAPHIC boreholes, State 

or EPA approved subsurface cleanup sites, surface bodies of water, springs, 

mines (surface and subsurface), quarries, water wells and other pertinent 

surface features including structures intended for human occupancy and roads. 

The map should also show faults, if known or suspected. Only information of 

public record is required to be included on this map; 

Rationale: Faults are not shown on maps unless there is a surface expression of 

the fault. Also, faults are detailed in (d) below and this language appears 
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. 

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

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: 24643

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

language; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

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. 

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; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

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; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

Comment: Rule Provision: 146.82(d)(4) & (5) 

Anadarko Petroleum Corporation (APC) Comments: (4) Data on the depth, areal 

extent, thickness, mineralogy, porosity, permeability and capillary

RESERVOIR pressure of the injection and confining zone(s) WITHIN THE AREA OF 

REVIEW; including geologic/facies changes based on field data which may 

include geologic cores, outcrop data, seismic surveys, well logs, and names and 

lithologic descriptions; 

(5) KNOWN geomechanical information on fractures, stress, ductility, rock 

strength, and in situ fluid pressures within the confining zone(s) WITHIN THE 

AREA OF REVIEW; and 

Rationale: Deleted capillary pressure because it is too hard to measure outside 

of the lab. Using sidewall cores, it may be difficult to determine capillary 

pressure. Additionally, full cores are not available until after the well being 

permitted is drilled. 

Response: EPA acknowledges the comment but did not make the suggested edits. The Agency

believes that the site characterization requirements at §146.82, including geomechanical information

and geologic and topographic maps and cross sections, are essential to proper siting of a GS well

and are the foundation for a detailed understanding of the local and regional geology, and that the

owner or operator should collect this information, regardless of whether it is known in advance of

the siting process. Collecting and evaluating this data supports important evaluations regarding the

suitability of the site to receive and contain injected CO2. 

EPA acknowledges that laboratory methods are standard for determining capillary pressures

regardless of formation permeability and that in situ measurements would require drilling of a well.

However, EPA also anticipates that test wells will be drilled to support geologic site characterization

of the proposed GS sites and can be used to collect subsurface samples (for laboratory determination

of capillary pressure) and take other necessary measurements. 

EPA recognizes that this information may not be available until after a well has been drilled. EPA

revised §146.82 so that the final regulation specifies separate requirements for information to be

submitted with the permit application and before well construction is approved (at §146.82(a)) and

information to be submitted before operation of the well is authorized (at §146.82(c)). Final

information on injection zone pressures would be required following drilling of the well, at

§146.82(c)(4).

EPA believes that information on capillary entry pressure is necessary and appropriate. Capillary

entry pressure measurements on core samples can quantify the amount of buoyant force the
confining zone can maintain before failure (World Resources Institute, 2008). 

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

Comment: Rule Provision: 146.82(e) 

Anadarko Petroleum Corporation (APC) Comments: (e) A tabulation of all wells

ARTIFICIAL PENETRATIONS within the area of review which penetrate the injection 

or confining zone(s). Such data must include a description of each well’s type, 

construction, date drilled, location, depth, record of plugging and/ or 

completion, and any additional information the Director may require; 

Rationale: Artificial penetrations is a more inclusive term. 

Response: EPA agrees that all artificial penetrations must be identified and evaluated during site

characterization. However the final rule retains the proposed text to be consistent with similar

requirements for other well classes and to support the corrective action requirements. EPA is

developing guidance on AoR and corrective action at GS Class VI sites to assist owners or operators

and Directors in evaluating requirements and proposed AoR and corrective action plans under

§146.84. The guidance can be found on EPA’s website at

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

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

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

Comment: Rule Provision: 146.82(g) 

Anadarko Petroleum Corporation (APC) Comments: (g) Baseline geochemical data 

on subsurface formations, including all USDWs in the area of review

COMPILATION OF AVAILABLE GEOCHEMICAL DATA ON THE PROPOSED INJECTION

ZONE AND 

NEAREST POROUS AND PERMEABLE FORMATION ABOVE THE CONFINING ZONE. 

Rationale: Limits the data submitted to available information and to the 

injection zone and the zone immediately above the confining zone which is the 

zones most likely to be monitored for potential CO2 leakage. 

Response: The Agency acknowledges the suggested edits but has retained the language as proposed.

EPA believes that a thorough understanding of the hydrogeologic conditions of all USDWs in the

AoR is necessary, and disagrees with the suggested edits because the GS rule, as written, affords

flexibility to owners or operators and Directors to tailor the site characterization process to the

unique features of the site. EPA encourages owners or operators and Directors to consult during site

characterization to discuss information needs and ensure that all appropriate data necessary to assess

the suitability of the site are collected. The Director has the authority to request additional

hydrogeologic data or other data on USDWs as well.

The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on

subsurface geologic formations, including all USDWs in the AoR, is appropriate and protective of

USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate

and transport model development (e.g., by providing appropriate input parameters), and provide

information needed to respond to any unexpected and unpermitted leaks outside of the injection

zone. The baseline geochemical information will allow the owner or operator and permitting

authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may

indicate fluid movement. 

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all

USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the

confining system and to serve as a baseline for future monitoring. The Director has the discretion to

require geochemical analysis of additional subsurface zones if, in the Director's opinion, they are

necessary for the protection of USDWs from endangerment. 
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; 3150 2.1.5 Comments on required permit information (40 CFR 146.82) 

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

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

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

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: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22160

Other EPA Comment Codes and Descriptions: 4720 2.7.2 Operational recordkeeping and

reporting 

Comment: Permit Application 

Southern Company opposes EPA's proposed requirements for Class VI permit 

applications to the extent that those requirements are more burdensome than 

current permit application requirements for other classes of UIC wells. id. at 

43517. C02 GS does not pose unique risks warranting many of the Proposal's 

additional requirements for detailed information. 

EPA should craft the Final Rule to require in the initial permit application 

information that the Director will need to determine whether issuance of a Class 

VI permit is appropriate. EPA could require submission of supplemental 

information as it becomes available through drilling, construction, and 

reevaluation of the well. This will not only prevent against the chilling effect 

that overly burdensome permit application requirements would have on the CO2 GS 

program, but will simultaneously ensure the ultimate collection of more thorough 

and reliable data. 

Response: EPA believes that the unique characteristics of CO2 injection (e.g., its relative buoyancy,

the large volume that may be injected, or the potential for chemical interaction with the subsurface)

warrant the additional information required to be submitted by Class VI operators under §146.82.

EPA disagrees that Directors should have the authority to waive some of the application

requirements. In order to protect USDWs from endangerment, Directors must have all the data

necessary to make well-informed decisions on establishing permit conditions and granting permits.

In response to concerns that some data will not be available until the well has been drilled, EPA

acknowledges 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 Class VI permit application. Based on

comments and evaluation of the proposed requirements, EPA revised this subpart so that the final

regulation specifies separate requirements for information to be submitted for approval with the

permit application before well construction, as required at §146.82(a), and information to be

submitted after the well is constructed; however, all data must be provided before injection is

authorized, as required at §146.82(c).

Commenter Name: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22171

Other EPA Comment Codes and Descriptions: 4200 2.4.2 Down-hole shut-off valves in GS wells

(seeking comment) 
Comment: While some requirements are appropriate for all Class VI wells, as a general 

matter operating and monitoring requirements for individual Class VI projects 

should be set forth in a Director-approved plan as part of the permit 

application and approval process. For example, while Southern Company supports a 

default requirement for automatic shut-off mechanisms for Class VI wells, we 

oppose a uniform requirement for down-hole shut-off valves. ¡d. at 34511. These 

valves are designed to meet unique offshore risks and are, in many instances, 

ill-suited to UIC operations, including C02 GS. A requirement for down-hole 

shut-off valves would provide little benefit but would come at a significant 

cost and would preclude the use of some tools that are critical to operation, 

monitoring, and repair of CO2 GS wells. 

Response: After evaluating the risks and benefits of down-hole shut-off systems and considering

additional research, EPA will not require automatic down-hole shut-off devices for onshore Class VI

wells since it is not necessary in all cases to ensure protection of USDWs from endangerment.

Instead, the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells

install automatic surface shut-off devices. The rule affords Director's discretion to mandate

automatic down-hole shut-off devices in onshore situations that may warrant their use. 

The GS rule, at §146.88(e)(3), requires the installation of down-hole shut-off devices for Class VI

wells located in the offshore submerged lands within the jurisdiction of a State UIC program. The

Agency agrees that offshore Class VI wells present unique construction and operational conditions,

including isolation from shorelines and the need to construct wells through the water column and the

subsurface, which may delay response time in the event of well difficulties. These conditions merit

requiring automatic down-hole shut-off devices for offshore wells in the submerged lands of a State. 

While EPA acknowledges that the likelihood of damage to onshore facilities is lower than that for

off-shore facilities, down-hole shut-off valves are still commonly used in onshore facilities such as

acid gas injection wells and high pressure, high-temperature wells. While valve failure is a concern,

EPA believes that technology has advanced sufficiently to make valve failure a rare occurrence and

to appropriately handle such failure if it occurs. For example, wireline retrievable devices can allow

repair or replacement of damaged devices without necessitating pulling the tubing.

EPA believes that requiring the installation of automatic surface shut-off devices for onshore wells

(and affording Director's discretion to require down-hole devices where necessary) and automatic

down-hole shut-off devices for offshore wells in submerged lands within the jurisdiction of a State

ensures that proper precautions are taken to prevent subsurface fluid movement and ensure protection

of USDWs.

Commenter Name: John Corra Letter ID: 0205

Commenter Organization: Wyoming Department of Environmental Quality

(DEQ)

Comment ID:

22204

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan

requirement (seeking comment) 

Comment: 7. Permit application content: 

a. We agree with the US EPA that permit applications for GS sites should include 

several plans not currently required under existing UIC regulations. These plans 

include a monitoring and testing plan, an AoR and corrective action plan, and a 
post-injection site care and site closure plan. 

Response: EPA agrees with commenters that developing and following testing and monitoring plans

is an important part of assuring that a GS project is operating properly and is crucial for the early

detection of potential endangerment to USDWs. The final rule retains this requirement.

EPA agrees that incorporating the plans into the permit rather than establishing specific requirements

for corrective action, monitoring, injection well plugging, and post-injection site care in the

regulation provide the appropriate flexibility to address the variety of site-specific conditions that

may be encountered at GS sites. 

EPA believes that it is appropriate and necessary to require owners and operators to submit all plans,

including the injection well plugging and post-injection site care and site closure plans, at the time of

permit application for the Director to make a proper permit decision. EPA believes that the Director

needs a satisfactory level of assurance that the owner or operator has planned for these events before

injection commences and that the owner or operator has ensured that appropriate financial resources

are available to fund all required activities, as required at §146.85. The final rule retains requirements

for submitting these plans with the permit application at §146.82(a). EPA expects that the

requirement for this and other plans associated with GS projects will promote an ongoing dialogue

between the owner or operator and the Director to ensure USDWs are protected from endangerment.

In addition, these plans will support a demonstration under §146.85 that owners and operators have

adequate financial resources to meet well plugging and post-injection site care and site closure

requirements. Please see the final rule and the discussion of the GS project plans for additional

information.

Commenter Name: Diane VanDe Hei Letter ID: 0206

Commenter Organization: Association of Metropolitan Water Agencies

(AMWA)

Comment ID:

22213

Other EPA Comment Codes and Descriptions: 5700 2.12 Comments on the proposed duration of

Class VI permits (seeking comment) 

Comment: have a plan to update the regulation on a regular basis as well. Having a permit 

renewal schedule built into the rule will allow each state Director to ensure 

that updates to the regulation are included in permit renewals. AWWA and AMWA 

also suggest that the permit application process include a review of the site 

operations to see if any instances of unsafe operation or changes in regulation 

would require a change in the plant operation. 

Response: The final rule maintains the lifetime permit provision and clarifies that the permit extends

through the post-injection site care period (144.36(a)). However, it also adds a requirement that the

Director review each Class VI permit at least every 5 years to determine whether it should be

modified, revoked and reissued, terminated or a minor modification made as provided in §§144.39,

144.40, or 144.41. The Director’s review will be informed by the owners’ or operators’ iterative

reevaluation of the project. Specifically, the final rule includes a requirement that the AoR be

reevaluated at least every five years, and also requires owners or operators to review and update the

AoR and corrective action plan, the testing and monitoring plan, and the emergency and remedial

response plan throughout the life of the project (146.84(e), 146.90(j), and 146.94(d)). Owners or

operators must review each plan and identify necessary amendments or demonstrate to the Director

that no amendment is needed. In no case can reviews occur less often than once every five years. The

iterative process and subsequent plan reevaluations ensure that time and resources are committed to
the most critical aspects of the permit in preventing endangerment to USDWs. 

EPA believes that the iterative process of developing and executing the various plans required of GS

well operators in the final rule (e.g., for AoR and corrective action, testing and monitoring, well

plugging, and post-injection site care, and emergency and remedial response) is tailored to the

unique aspects of—and is more appropriate for–GS than establishing a finite permit duration (e.g.,

five years as suggested by some commenters). This is preferable to a periodic permit reapplication. 

EPA adds that, in addition to the requirement that the Director review the permit every 5 years, as

part of existing requirements at 40 CFR 144.39, the Director has the authority to revise the permit if

project operations change, if the Director believes based on monitoring or operational data that the

project may endanger USDWs, or if the regulations change. EPA has also added text to 144.39(a)(5)

saying that permit modifications may be required if the Director determines that a modification is

necessary based on an AoR reevaluation, amendments to any of the project plans, or a review of the

testing and monitoring results. The Director may also choose to require minor permit modifications

under 40 CFR 144.41, depending on the extent of the plan amendment. All permit modifications,

except minor modifications under 40 CFR 144.41, require an opportunity for public comment on the

portion of the permit that is being reopened.

Commenter Name: Michael Stroben Letter ID: 0209

Commenter Organization: Duke Energy Comment ID: 22679

Comment: The rule should not be made unnecessarily stringent by requiring detailed 

information for Class VI permit applications that may not be available during 

the early phases of the permit application process. A better approach would be 

to require the reporting of detailed information over time as it becomes 

available through operation of the well, site reevaluation, and corrective 

action. 

Response: EPA believes that the unique characteristics of CO2 injection (e.g., its relative buoyancy,

the large volume that may be injected, or the potential for chemical interaction with the subsurface)

warrant the additional information required to be submitted by GS operators under §146.82. These

requirements are not unnecessarily stringent or burdensome. In order to protect USDWs from

endangerment, Directors must have all the data they need to make well-informed decisions on

establishing permit conditions and granting permits.

In response to concerns that some data will not be available until the well has been drilled, EPA

acknowledges 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 the permit application. Based on comments and

evaluation of the proposed requirements, EPA revised this subpart so that the final regulation

specifies separate requirements for information to be submitted for approval with the permit

application before well construction, as required at §146.82(a), and information to be submitted after

the well is constructed; however all information must be submitted before injection is authorized, as

required at §146.82(c).

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22737

Comment: EPA is proposing that permit applications for GS sites include several plans not 

currently required under existing UIC regulations. These plans include a 
monitoring and testing plan, an AoR and corrective action plan, and a postinjection site care and site closure plan. EPA seeks comment on the merits of 

requiring plans for monitoring, AoR, and post-injection site care as part of a 

permit application. EPA Notice 112. 

We believe that requiring a monitoring plan is reasonable. However, the EPA 

should develop such requirements with recognition of a distinct end to 

operations and monitoring following closure, and consider specific 

representations and codicils that recognize an end of "in-perpetuity" 

responsibility for the operator or owner. 

Response: EPA clarifies that the owner or operator's approved testing and monitoring plan and postinjection site care and site closure plan will be incorporated as a condition of the UIC permit. GS

well operators will be required to perform monitoring pursuant to the plans throughout the life of the

facility (i.e., the duration of the Class VI permit). EPA adds that §146.93(b) requires operators to

perform post-injection site monitoring until it can be demonstrated that the CO2 and pressure front

no longer pose a risk of endangerment to USDWs. EPA notes that the post-injection monitoring may

be different from monitoring that occurs during the operational phase (i.e., as required at §146.90).

Once this demonstration is made, site closure may be authorized and monitoring is no longer

required. EPA adds that owners or operators must maintain financial responsibility until site closure

has been authorized.

Please see the final rule and preamble, including the discussion of post-injection site care monitoring

and financial responsibility for additional information.

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 22909

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit

information (40 CFR 146.82) 

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

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: 3150 2.1.5 Comments on required permit

information (40 CFR 146.82) 

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: Diane VanDe Hei Letter ID: 0213

Commenter Organization: Association of Metropolitan Water Agencies

(AMWA)

Comment ID:

22950

Comment: updates to the regulation are included in permit renewals. AMWA also suggests 

that the permit application process include a review of the site operations to 

see if any instances of unsafe operation or changes in regulation would require 

a change in the plant operation. 

Response: EPA agrees that review of site operations is important and expects that the reevaluations

of the site plans will provide such review. For example, the AoR reevaluations offer a good

opportunity to promote a dialogue between the owner or operator and the permitting authority. The

final GS rule, at §§146.84(c), 146.90(j), and 146.94(d), requires owners or operators to review and

update the AoR and corrective action plan, the testing and monitoring plan, and the emergency and

remedial response plan throughout the life of the project. Owners or operators must review each plan

and identify necessary amendments to the plan or demonstrate to the Director that no amendment is

needed. These reviews must be performed within one year of an AoR reevaluation, following any

significant changes to the facility (e.g., the addition of monitoring or injection wells), or when

required by the Director. In no case can reviews occur less often than once every five years. Please

see the final rule and the discussion of AoR reevaluations in the preamble for additional information.
Commenter Name: Barbara Walz Letter ID: 0216

Commenter Organization: Tri-State Generation and Transmission Association,

Inc.

Comment ID:

22977

Comment: F. 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 geologic sequestration well, 

and its Area of Review as that information becomes available. 

Response: The final rule permit application process is not overly burdensome or unrealistic. EPA

acknowledges 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. Please see the final rule and the discussion of AoR reevaluations in the preamble for

additional information.

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

Comment: 2. § 146.82 Required Class VI permit information 

This section of the proposed rule sets forth the information which the owner or 

operator must submit to the Director in order to obtain a Class VI well permit. 

All of the information specified must be part of the permit application. But 

some data are not necessary in light of other provisions of the current 

proposal, and some are not attainable prior to well drilling (applicants will 

not drill the well until it has been approved, otherwise they risk drilling an 

unusable well). Still other data can only be obtained after injection activities 

have been initiated. Post drilling and post injection data should not be 

required as part of the application process but instead should be considered 

confirmatory data that may be submitted after they are obtained. In general, the 

proposed rule should be modified to require submission of only those data which 

are needed for consideration of the initial permit application, and only those 

data that may be reasonably obtained prior to commencement of installation and 

operation of the injection well. 

EPA Proposed: §146.82 (f) Maps and stratigraphic cross sections 

indicating the general vertical and lateral limits of all USDWs, water 

wells and springs within the area of review, their positions relative to 

the injection zone(s) and the direction of water movement, where known; 

So long as the Applicant proposes to inject CO2 below the lowermost USDW, as 

required by the proposed rule, there is no justification to require maps and 

stratigraphic cross sections for the entire extent of those USDWs above the 
lowermost USDW, although mapping and stratigraphic cross sections in the 

immediate vicinity of the proposed injection locations (e.g. where the injection 

wells will be drilled) should still be required. Data regarding all USDWs in the 

AoR will likely be costly and/or difficult to collect and, except as noted 

above, the usefulness of those data seems questionable. 

Accordingly, TxCCSA suggests that subparagraph (f) should be modified as 

follows: 

(f) Maps and stratigraphic cross sections indicating the general 

vertical and lateral limits of all THE LOWERMOST USDWs, ALL USDWS IN 

THE IMMEDIATE VICINITY OF THE PROPOSED INJECTION WELL(S), water wells 

and springs within the area of review, their positions relative to the 

injection zone(s) and the direction of water movement, where known; 

EPA Proposed : §146.82(l) The results of the formation testing program 

as required in paragraph (j) of this section; 

(r) All available logging and testing program data on the well required 

by § 146.87; 

(s) A demonstration of mechanical integrity pursuant to § 146.89; 

The requirements of subparts (l), (r) and (s) of § 146.82 cannot be met until 

after the well is drilled. For example, subparagraph (l) references (j), 

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: 24066

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

language 

Comment: §146.91 Reporting requirements. 

Proposed Rule: (1) Any changes to the physical, chemical and other relevant 

characteristics of the carbon dioxide stream from the proposed operating data; 

Schlumberger Suggested Revision: (1) Any significant changes to the physical, 

chemical and other relevant characteristics of the carbon dioxide stream from 

the proposed operating data; 

Schlumberger Rationale: Minor changes could just be due to uncertainty in 

measurements or models 

Response: EPA retained this provision as proposed. The final rule at §146.91(a)(3) requires

reporting of all exceedances of operating parameters. EPA disagrees with the suggestion to report

only "significant" exceedances. Making a determination as to whether an exceedance is "significant"

is not the purpose of the requirement. EPA believes that the ability of an operator to consistently

meet operating requirements and avoid exceedances provides evidence of a well-managed GS

project that is in compliance with the Class VI permit. If multiple exceedances occur, the Director

should be aware of such occurrences and determine whether these indicate non-compliance at the

site, and require the appropriate course of action (e.g., a well workover, modification of operating

parameters, or imposition of a penalty). Please see the final rule and the discussion of testing and

monitoring in the preamble for additional information.

EPA clarifies that the rule, at §146.91(c), also requires operators to notify the Director, within 24

hours, of any event that may cause endangerment to a USDW. If such events occur outside of

business hours (e.g., over night), operators must report to the Director within 24 hours, and

permitting agencies have staff and procedures to respond to these types of calls 24 hours a day, 7

days a week.

Commenter Name: Neeraj Gupta Letter ID: 0229

Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21811

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit

information (40 CFR 146.82) 

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. 

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: 3150 2.1.5 Comments on required permit

information (40 CFR 146.82) 

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: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23256

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan

requirement (seeking comment) 

Comment: 34. EPA is proposing that permit applications for GS sites include several plans 

not currently required under existing UIC regulations. These plans include a 

monitoring and testing plan, an AoR and corrective action plan, and a postinjection site care and site closure plan. EPA seeks comment on the merits of 

requiring plans for monitoring, AoR, and post-injection site care as part of a 

permit application. EPA Notice 43517. 
Allowing for different plans would be much more effective than prescriptive 

regulations; however, a plan modification should not be considered a major 

permit modification. Caution needs to be taken when monitoring the injection 

formation due to the artificial penetration of the confining zone to gain data. 

The number of monitoring wells should be decided on a case-by case basis. It is 

unclear how monitoring wells will be regulated since they are not injection 

wells. The timing of plan submittal should be linked to the activity being 

Response: EPA agrees with commenters that developing and following testing and monitoring plans

is an important part of assuring that a GS project is operating properly and is crucial for the early

detection of potential endangerment to USDWs. 

EPA expects that the number of monitoring wells needed will be determined based on site-specific

information as the testing and monitoring plan is developed. EPA believes that monitoring using

wells in the injection zone (i.e., that penetrate the confining zone) can be safely performed if the

wells are constructed to prevent flow between the injection zone and USDWs or other layers above

the confining zone. Such construction technologies exist and have been used in the oil and gas

industry for years. EPA believes that the benefits of monitoring in the injection formation outweigh

the manageable risk of those monitoring wells serving as conduits for fluid movement. 

EPA also agrees that periodic updates to the plan are appropriate. EPA clarifies that the final GS

regulation includes a requirement that the AoR be reevaluated at least every 5 years, and it specifies

at §146.90(j) that the operator revise the testing and monitoring plan to incorporate the results of the

most recent AoR reevaluation and recent operational and monitoring data. EPA clarifies that every

revision to the testing and monitoring plan will not necessarily trigger a major permit modification.

The existing regulation at 40 CFR 144.39(a) identifies causes for modification of permits that would

invoke the public notification procedures at 40 CFR 124, including: alterations or additions to the

facility; availability of additional information; new regulations; and compliance schedule

modifications. In the final rule, EPA added text to §144.39(a)(5) that permit modifications would be

required if the Director determines that a modification is necessary based on an AoR reevaluation,

amendments to any of the project plans, or a review of the testing and monitoring results. 

In addition, 40 CFR Part 144.41 identifies causes for minor modifications of permits (which do not

require following the procedures of Part 124). These include correction of typographical errors; more

frequent monitoring or reporting; changes in an interim compliance date; changes in ownership or

control of a facility; changes in the quantities or types of fluids injected which are within the

capacity of the facility; changes in construction requirements; or amendments to a plugging and

abandonment plan. In the final rule, EPA added a subparagraph (h) to §144.41 that would include

minor amendments (e.g., to clarify, correct, or update) the testing and monitoring plan, plugging

plan, post-injection site care and site closure plan, or emergency and remedial response plan for a

GS well (i.e., amendments that are not included under 144.39(a)(5) and that do not require additional

permit requirements). 

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in

evaluating requirements under §146.90, including proposed monitoring plans. The guidance

describes available technologies and recommended approaches for implementing a testing and

monitoring plan, including pre-operational geophysical logging and testing of injection wells, MITs,

injection well testing during operation, groundwater quality monitoring, tracking the CO2 plume and

pressure front, and soil gas and surface air monitoring which may be required by the UIC Director

for specific GS projects. The guidance can be found on EPA’s website at
http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. In addition, in January 2009,

DOE published a best practices manual entitled "Monitoring, Verification, and Accounting of CO2

Stored in Deep Geologic Formations" (DOE/NETL-311/081508); this manual is included in the

docket for the final GS rule. EPA notes that closure of monitoring wells should be addressed in the

post-injection site care and site closure plan.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23257

Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit

information (40 CFR 146.82) 

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: 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; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

Comment: EPA Proposal: (b) A map showing the injection well(s) for which a permit is 

sought and the applicable area of review. Within the area of review, the map 

must show the number, or name and location of all injection wells, producing 

wells, abandoned wells, plugged wells or dry holes, deep stratigraphic 

boreholes, State or EPA approved subsurface cleanup sites, surface bodies of 

water, springs, mines (surface and subsurface), quarries, water wells and other 

pertinent surface features including structures intended for human occupancy and 

roads. [Highlighted text: The map should also show faults, if known or 

suspected.] Only information of public record is required to be included on this 

map; 

GWPC Recommendations: (b) A surface map showing the proposed locations for the 

injection well(s) for which a permit is sought and the applicable area of 

review. Within the area of review, the map must show the number, or name and 

location of all known injection wells, producing wells, abandoned wells, plugged 

wells or dry holes, deep stratigraphic boreholes, State or EPA approved 

subsurface cleanup sites, surface bodies of water, springs, mines (surface and 

subsurface), quarries, water wells and other pertinent surface features 

including structures intended for human occupancy and roads. Only information of 

public record is required to be included on this map; 
Rationale: Insert "known" before "injection" 

Suggests removing highlighted text as faults are not shown on maps unless there 

is a surface expression of the fault. Also, faults are detailed in (d) below 

and this language appears redundant. 

Response: Regarding the comment that EPA delete mention of faults on surface maps, EPA believes

that if faults have surface expressions, they should be presented on maps submitted; this information

would complement the required cross section data. EPA is developing guidance on site

characterization for GS projects to assist owners or operators and Directors in evaluating permit

requirements and applications under §146.82. The guidance provides recommendations regarding

characterizing the regional geology and hydrogeology of a proposed GS site as well as performing

the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining

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

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. Please see the final rule and the

discussion of geologic site characterization in the preamble for additional information.

EPA acknowledges but did not make the suggested edits. EPA believes that all of the site

characterization requirements at §146.82, including geomechanical information and geologic and

topographic maps and cross sections, are essential to proper siting of a GS well and are the

foundation for a detailed understanding of the local and regional geology, and that the owner or

operator should collect this information, regardless of whether it is known in advance of the siting

process. Collecting and evaluating this data supports important evaluations regarding the suitability

of the site to receive and contain injected CO2. 

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

process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known

or suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells

and sites can mitigate the potential impacts of unidentified fractures. These include limitations on

injection pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)),

collection and 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: 24870

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

language; 3100 2.1 Proposed Geologic Siting Requirements (40 CFR 146.83) 

Comment: EPA Proposal: (c) The area of review based on modeling, using data obtained 

during logging and testing of the well and the formation as required by 

paragraphs (l), (r), and (s) of this section; 

GWPC Recommendations: (c) A map delineating the area of review based upon 

modeling, using all available data including data available from any logging and 

testing of wells within the area of review. 

Rationale: Is this supposed to be a map, a tabular display, a cross section or 

series of cross sections etc... This appears to be related to a condition where 

a well is already drilled. This does not align with requesting information to 
receive a permit. 

Response: EPA recognizes that information necessary for an area of review may not be available

until after a well has been drilled and formation testing can occur. EPA revised §146.82 so that the

final regulation specifies separate requirements for information to be submitted with the permit

application and before well construction is approved (at §146.82(a)) and information to be submitted

before operation of the well is authorized (at §146.82(c)) including The final area of review based on

modeling, using data obtained during logging and testing of the well and the formation

§146.82(c)(1). 

Based on its evaluation of all public comments and input on the proposed rule and NODA and

Response to Comments EPA has made many revisions to the GS Rule. See the final rule and the site

characterization discussion in the preamble for further discussion on EPA's final approach.

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; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

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. 

(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; 3130 2.1.3 Comments that operators should submit more (or different) geologic data than

proposed 

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 

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

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

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 

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

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

language; 3100 2.1 Proposed Geologic Siting Requirements (40 CFR 146.83) 

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: 24877

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

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

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 
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; 
(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. 
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.

Commenter Name: Craig Hart Letter ID: 0261

Commenter Organization: Alston & Bird LLP Comment ID: 22985

Comment: Experience in Phase II with SDWA Permitting 

Based on interviews with the lead implementing organizations in each regional 

partnership, the time and cost associated with preparing SDWA permit 

applications, and the time required for agency review, have caused delays and 

can impose burdens on small-scale research projects due to limited financial 

and staff resources. EPA review of permit applications is generally expected to 

require between 6 to 9 months based on EPA estimates provided to certain of the 

partnerships in informal consultations. State agency review under Class II, 

where available, is expected to require less time, in some cases requiring only 

1 to 2 months. 

Response: EPA disagrees that it should streamline or provide a different approval process for smallvolume operators. To protect USDWs from endangerment the information required to be submitted

with the permit application under §146.82 is necessary and appropriate to provide permitting

authorities sufficient information on which to base informed decisions about establishing permit

conditions and granting permits. The purpose of these requirements is to protect USDWs from

endangerment, and like large-volume operations, small-volume operations must be permitted and

operated in manner that is protective of USDWs.

EPA is preparing guidances to support permit application reviews for Class VI permits, including

guidance for primacy authorities and an addendum to UICPG #83 that describes the use of the Class

V experimental technology well classification following promulgation of the GS Class VI rule. The

guidances will be available on EPA's web site, at

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

Commenter Name: Craig Hart Letter ID: 0261

Commenter Organization: Alston & Bird LLP Comment ID: 22987

Other EPA Comment Codes and Descriptions: 1530 1.2.3.1 State regulatory efforts on GS

(seeking comment) 

Comment: Examples of Streamline Permitting in CCS Regimes and U.S. Environmental Law 

The State of Washington's Underground Injection Control Program allows 

streamline permitting under Class V for small-scale pilot injections of under 

1,000 metric tons or larger volumes by application.[FN5] Australia has adopted a 

phased permitting process, which includes an assessment permit.[FN6] 

[FN5] Wash. Admin. Code, 173-218-115(4)(b). 
[FN6] Nigel Bankes and Jenette Poschwatta, Australian Legislation on Carbon Capture 

and Storage: A Canadian Perspective (June 2008), available at 

www.iseee.cajfilesjiseeejbankesJesearch_paper.pdf. 

Response: EPA clarifies that, with the promulgation of the GS rule, it no longer considers it

appropriate to permit CO2 injection wells that are testing the injectivity or appropriateness of an

individual formation (e.g., as a prelude to a commercial-scale operation) as Class V experimental

technology wells. Such wells should be permitted as Class VI wells. EPA clarifies that Class V

experimental technology wells may be used for experimental projects designed to test new

technologies.

EPA is preparing an addendum to UICPG #83 that describes the use of the Class V experimental

technology well classification to clarify permitting for Class V wells. This addendum will address

shifting of Class V experimental projects to full-scale GS projects and the future use of the Class V

experimental technology well subclass for research and testing of new GS technologies. 

Throughout the regulatory development process for the Class VI regulation, EPA monitored states'

regulatory and legislative development efforts and approaches. In EPA's August 31, 2009, Notice of

Data Availability (NODA) and Request for Comment, the Agency described its ongoing monitoring

of states' regulatory efforts and approaches and how the Agency is considering this information as it

develops guidance on the primacy application and approval process for Class VI wells. Information

about these state activities may be found in the docket for the GS rule.

EPA disagrees with the suggestion that it should streamline or provide a different approval process

for small-volume operators. To protect USDWs from endangerment, EPA believes that the

information required to be submitted with the permit application under §146.82 is necessary and

appropriate to provide permitting authorities sufficient information on which to base informed

decisions about establishing permit conditions and granting permits. The purpose of these

requirements is to protect USDWs from endangerment, and like large-volume operations, smallvolume operations must be permitted and operated in manner that is protective of USDWs.

EPA clarifies that small scale, experimental research injection wells, such as those operated by the

Regional Carbon Sequestration Partnerships, will continue to be regulated as Class V experimental

wells as long as they remain small scale and of an experimental nature. Permitting of these wells is

addressed in UIC Program Guidance #83: Using the Class V Experimental Technology Well

Classification for Pilot Carbon Geologic Sequestration Projects.

Existing pilot projects will continue to be regulated under their Class V experimental well permits

and must meet the reporting requirements set forth in their individual permit. EPA expects that, as

the permits for these Class V projects expire, they will either be re-permitted as Class VI wells

(subject to reporting requirements at §146.91) or, if they continue to be of an experimental nature,

they may continue to be permitted as Class V experimental technology wells (subject to the

reporting requirements in the permit). EPA is preparing an addendum to UICPG #83 that describes

the use of the Class V experimental technology well classification following promulgation of the GS

Class VI rule. The guidance will address shifting of Class V experimental projects to full-scale GS

projects and the future use of the Class V experimental technology well subclass for research and

testing of new GS technology. The guidance will be available on EPA's web site, at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.
Commenter Name: Craig Hart Letter ID: 0261

Commenter Organization: Alston & Bird LLP Comment ID: 22988

Other EPA Comment Codes and Descriptions: 4000 2.4 Proposed Injection Well Operating

Requirements (40 CFR 146.88) 

Comment: Other U.S. environmental laws, such as the Toxic Substances Control Act, also 

provide precedent for a streamline permitting approach in other contexts.[FN7] 

Options for a Streamline Review Procedure 

A common feature of streamline permitting schemes is a quantified limit, which 

in the case of CCS, would likely be a volume limit. The advantages of quantified 

volume limit include that it provides greater certainty for research 

organizations and allows EPA to allocate resources to higher volume CCS 

injections that pose more significant risks. 

While no specific volume limit is suggested here, EPA should consider several 

factors for setting such a limit. A volume limit should be differentiated base 

on type of formation, site pressure, and other site-specific conditions. Such a 

limit could change (likely increase) along with our knowledge of a particular 

formation and experience with CO2 injections for purposes of permanent 

sequestration generally. Finally, in addition to considerations relating to 

protection of drinking water sources, a volume limit should be based on the 

needs of advancing research and the risks to health and safety, including 

workers, the general population, flora and fauna. CCS assessment models have 

been developed by our national laboratories specifically to address these kinds 

of risks.[FN8] 

[FN7] TSCA governs the manufacture, processing, use, distribution in commerce, and 

disposal of chemical substances and mixtures. It provides for varying levels of 

expedited review and exemption from regulations in qualifying research, low 

volume commercial production, and low release low exposure commercial 

production. See Elizabeth Brown et al., A Practitioner's Guide to the Toxic 

Substance Control Act, Environmental Law Institute, 1999. 

[FN8] See Curtis M. Oldenburg and Steven L. Bryant, Certification Framework for 

Geologic CO2 Storage, Sixth Annual Conference on Carbon Capture and 

Sequestration, National Energy Technology Laboratory, Pittsburgh, PA, May 7-10, 

2007 available at www.netl.doe.govjpublicationsjproceedingsj07jcarbon 

seqjdatajpapersjtue_062.pdf; Curtis M. Oldenburg, Steven L. Bryant, JeanPhilippe Nicot, and Ying Zhang, Certification Framework for Geologic Carbon 

Sequestration Based on Effective Trapping, Seventh Annual Conference on Carbon 

Capture and Sequestration, National Energy Technology Laboratory, Pittsburgh, 

PA, May 5-8, 2008; Curtis M. Oldenburg, Steven L. Bryant, Jean-Philippe Nicot, 

Certification Framework for Geologic Carbon Sequestration Based on Effective 

Trapping (forthcoming 2008). 

Response: As described above, EPA disagrees with the suggestion that it should streamline the

approval process for small-volume operators. EPA believes that the information required to be

submitted with the permit application under §146.82 is necessary and appropriate to provide

permitting authorities sufficient information on which to base informed decisions about establishing
permit conditions and granting permits. The purpose of these requirements is to protect USDWs

from endangerment, and like large-volume operations, small-volume operations must be permitted

and operated in manner that is protective of USDWs.

EPA disagrees with the suggestion to set a volume limit. EPA believes that the potentially wider

range of injection scenarios, formation types, and other site-specific factors necessitate a sitespecific approach, and permit limits that are based on the unique geology of the site. The injection

pressure limit for each GS project will be based on site-specific conditions, and be informed by data

on the injection zone.

Commenter Name: Craig Hart Letter ID: 0261

Commenter Organization: Alston & Bird LLP Comment ID: 22989

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

Partnerships 

Comment: As EPA considers its proposed rule for Class VI wells under the SDWA UIC 

program, we will have additional information about the CCS permitting process 

from the DOE RCSP Phases II and III projects. As part of its review of the 

proposed rules for Class VI injection wells, EPA should take account of this 

experience and consider providing an improved permitting regime for small-scale 

research projects in order to facilitate CCS research and development efforts. 

Response: The final rule allows owners or operators to continue using the Class V experimental well

permit process for small-scale projects that are experimental in nature. EPA believes that the Class V

and Class VI permitting requirements are necessary to protect USDWs from endangerment, and are

based on site-specific and project-specific information, including CO2 volume. EPA believes that

the requirements for GS owners or operators are flexible enough to take into account plant operating

data, including the volume to be injected.

The Agency is also tracking operation and technical developments of more than three dozen smalland large-scale GS injection projects in the United States and abroad. EPA meets regularly with

DOE to discuss its research initiatives, project developments, and "best practices." 

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

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

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

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

requirements are appropriate or necessary.

As described above, EPA disagrees with the suggestion that it should streamline the approval process

for small-volume operators. EPA believes that the information required to be submitted with the

permit application under §146.82 is necessary and appropriate to provide permitting authorities

sufficient information on which to base informed decisions about establishing permit conditions and

granting permits. The purpose of these requirements is to protect USDWs from endangerment, and

like large-volume operations, small-volume operations must be permitted and operated in manner

that is protective of USDWs.

Letter ID: 0263

Commenter Organization: Interstate Oil & Gas Compact Commission Comment ID: 22821
Comment: III A. 7 Proposed Recordkeeping and Reporting Requirements 

KK. EPA seeks comment on the merits of requiring plans for monitoring, AoR, 

and post-injection site care as part of a permit application. 

IOGCC Response: Yes, there should be detailed monitoring, AoR, and post-injection 

site care plans as a part of the permit consistent with the recommendations of the 

IOGCC modelregulations. 

Response: EPA agrees that incorporating the plans into the permit rather than establishing specific

requirements for corrective action, monitoring, injection well plugging, and post-injection site care in

the regulation provide the appropriate flexibility to address the variety of site-specific conditions that

may be encountered at GS sites. 

EPA also believes that it is appropriate to require owners and operators to submit all plans, including

the injection well plugging and post-injection site care and site closure plans, at the time of permit

application. The owner or operator must demonstrate to the Director a satisfactory level of assurance

that the they have planned for these events before injection commences and that they have ensured

that appropriate financial resources are available to fund all required activities, as required at

§146.85. The final rule retains requirements for submitting these plans with the permit application at

§146.82(a). EPA expects that the requirement for this and other plans associated with GS projects

will promote an ongoing dialogue between the owner or operator and the Director to ensure USDWs

are protected from endangerment. Please see the final rule and the discussion of GS project plans in

the preamble for additional information.

Commenter Name: Scott Anderson Letter ID: 0520

Commenter Organization: Environmental Defense Fund Comment ID: 21431

Other EPA Comment Codes and Descriptions: 1620 1.3.2 Induced seismicity; 4110 2.4.1.1

Injection pressure limitations 

Comment: Injection pressure limits. This is very important and we think EPA's about 

halfway toward addressing this properly. The half that seems to be well done is 

that the proposed rule requires quite a bit of geomechanical information to be 

submitted. The kind of information that could be used, should be used to 

determine whether or not there is a risk of induced seismicity and to determine 

whether or not there is risks of reopening otherwise closed faults and fractures 

making them, making what starts out as a non-transmissive fault into a 

transmissive fault. So the proposed rule calls for the information that enables 

that kind of stuff to be calculated, but it fails to require that information to 

be used as part of the permitting process to inform the injection pressure 

limits. Instead the rule uses the traditional sort of injection pressure limit 

from oil and gas regulation that says accepted as a percentage of fracture 

pressure. The problem with that is that these other problems I mentioned, 

induced seismicity and reopening of faults can occur in lower pressures than say 

90% of fracture pressure, it is possible for one to comply with the 90% of 

fracture pressure requirement and yet still cause these other geomechanics 

related problems. 

Response: EPA clarifies that all information about the site, including seismic history and data on

rock mechanics, will be used to inform pressure limitations. 
In response to the concern about induced seismicity and reopening of faults at lower pressures than

90 percent of fracture pressure, EPA believes that the requirement for the owner or operator to

submit data on known or suspected faults and fractures and information on the seismic history of the

site, including the presence and depth of seismic sources and a determination that the seismicity

would not interfere with containment per §146.82(a)(3)(v), will inform the determination of an

appropriate pressure limitation in the permit. This investigation would also identify any sites with the

potential for reopening or reactivation of faults or unacceptable seismic risk that could otherwise

interfere with containment. 

The Director will also review geologic, hydrogeologic, and geomechanical information submitted by

the owner or operator in setting permit conditions. If, based on this information, a lower pressure

limitation is appropriate, the Director has the authority to set a lower limit in the operating permit.

EPA clarifies that fracturing of the confining zone during injection and/or stimulation is also

prohibited at §146.88(a).

Commenter Name: Kevin Frederick Letter ID: 0525

Commenter Organization: Wyoming Department of Environmental Quality Comment ID: 21396

Other EPA Comment Codes and Descriptions: 1420 1.2.1.1 Support the GS rulemaking 

Comment: A few specific comments on issues where we agree with EPA's proposed rule. We 

believe that permit applications for GS sites should include several plans, not 

currently required under existing UIC regulations. These plans include a 

monitoring, a testing plan and an area of review and corrective action plan and 

a post injection site care and site closure plan. 

Response: EPA believes that the GS requirements, which are based on the long-standing UIC

regulatory framework and tailored to meet the unique nature of CO2 injection for GS, appropriately

address endangerment risks to USDWs. The GS rule contains minimum technical criteria for the

permitting, geologic site characterization, AoR and corrective action, well construction, operation,

mechanical integrity testing, monitoring, financial responsibility, injection well plugging, postinjection site care, and site closure of GS wells, which will ensure that USDWs are protected from

endangerment. 

For additional information on testing and monitoring, corrective action, and post-injection site care

requirements, please also see the discussion of EPA’s Final Regulatory Approach in the preamble to

the final GS rule.

EPA agrees that incorporating the plans into the permit rather than establishing specific requirements

for corrective action, monitoring, injection well plugging, and post-injection site care in the

regulation provide the appropriate flexibility to address the variety of site-specific conditions that

may be encountered at GS sites. 

EPA also believes that it is appropriate to require owners and operators to submit all plans, including

the injection well plugging and post-injection site care and site closure plans, at the time of permit

application. EPA believes that the Director needs a satisfactory level of assurance that the owner or

operator has planned for these events before injection commences and that the owner or operator has

ensured that appropriate financial resources are available to fund all required activities, as required at

§146.85. The final rule retains requirements for submitting these plans with the permit application at

§146.82(a). EPA believes that the requirement for this and other plans associated with GS projects
will promote an ongoing dialogue between the owner or operator and the Director to ensure USDWs

are protected from endangerment. In addition, these plans will support a demonstration that owners

and operators have adequate financial resources to meet well plugging and post-injection site care

and site closure requirements. Please see the final rule and the discussion of the GS project plans in

the preamble for additional information.

Commenter Name: Paul Pike Letter ID: 0535

Commenter Organization: Ameren Corporation on behalf of Utility Solid Waste

Activities Group (USWAG)

Comment ID:

21441

Comment: A final rule must not make Class VI permit 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 Class VI well and its area of review 

as that information becomes available. 

Response: EPA believes that the unique characteristics of CO2 injection (e.g., its relative buoyancy,

the large volume that may be injected, or the potential for chemical interaction with the subsurface)

warrant the additional information required to be submitted by GS operators under §146.82. EPA

disagrees that Directors should be able to waive some of the application requirements. To protect

USDWs from endangerment, Directors must have all the data they need to make well-informed

decisions on establishing permit conditions and granting permits.

In response to concerns that some data will not be available until the well has been drilled, EPA

acknowledges 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 the permit application. Based on comments and

evaluation of the proposed requirements, EPA revised this subpart so that the final regulation

specifies separate requirements for information to be submitted for approval with the permit

application before well construction, as required at §146.82(a), and information to be submitted after

the well is constructed yet before injection is authorized, as required at §146.82(c). Please see the

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

additional information.

Commenter Name: Olon Plunk Letter ID: 0536

Commenter Organization: Xcel Energy Comment ID: 21377

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

(40 CFR 146.83) 

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

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.

Comment Code: 4720 2.7.2 Operational recordkeeping and reporting 

Individual Comments

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24793

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

language; 4520 2.5.1 Continuous internal mechanical integrity monitoring (seeking comment) 

Comment: (b) To evaluate the absence of significant leaks under paragraph (a)(1) of 

this section, owners or operators must, following an initial annulus pressure 

test, continuously monitor injection pressure, rate, injected volumes, and 

pressure on the annulus between tubing and long stem casing and annulus fluid 

volume as specified in §146.88(e);

{Redundant language.} 

Response: The final rule retains this text to provide clarity about requirements for demonstrating

internal mechanical integrity and to specify the necessary monitoring. EPA believes that continuous

pressure monitoring to demonstrate internal mechanical integrity of Class VI wells (146.89(b)),

instead of periodic testing (which is required for most other types of deep injection wells) is

important given the potential corrosive impact of CO2 and impurities on well materials, the potential

geomechanical impacts to well integrity due to CO2 phase changes, and the temperature and

pressure effects associated with injecting supercritical CO2.

For additional information, please see the discussion of MITs in the final rule preamble.

Commenter Name: John Hanger Letter ID: 0130

Commenter Organization: Pennsylvania Dept. of Env. Protection Comment ID: 21513

Comment: Proposed Recordkeeping and Reporting Requirements 

-The chemistry of the gas stream will be affected by the fuel source and the 

operating conditions of the capture and purification systems. These data, while 

not the responsibility of the operator, can have significant impacts on the gas 

constituents. Semi-annual reports will not be timely in identifying these 

impacts. The operator should require reports from the gas source, which can be 

forwarded to EPA as part of the semi-annual report, or as an additional 

submittal between the semi-annual reports. Once parameters of operations are 

known, the reports could be waived or modified. A specific example of a 

potential concern: Power Plant A receives a modification to its air permit from 

a non-primacy state. The modification allows the burning of petcoke, which 

commonly has a high vanadium content. Vanadium oxides can form on operating 

surfaces, affecting capture system efficiencies, or possible modifying down-hole 

behavior. This type of change could greatly affect the overall system. 

-Also, operating performance of the gas suppliers’ systems should be monitored. 
Changes in characteristics such as pressure drop, filter cloth efficiencies, 

increases or changes in dilution air, etc., can affect the quality of the CO2 

stream. 

Response: EPA is retaining the semi-annual reporting requirement in the final rule at §146.91(a) in

order to ensure that permitting authorities can maintain proper oversight and track compliance 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 cannot reply specifically as to whether any change to the CO2 stream or the fuel source would

warrant a change in the permit. However, it is possible that a permit may have to be modified for

these reasons. Section 144.39(a) identifies causes for modification of permits that would invoke the

public notification procedures at Part 124, including: alterations or additions to the facility;

availability of additional information; new regulations; and compliance schedule modifications. EPA

added text to §144.39(a)(5) that permit modifications would be required if the Director determines

that a modification is necessary based on an AoR reevaluation, amendments to any of the project

plans, or a review of the testing and monitoring results.

If the source of the injectate changes, the Director must evaluate whether this change warrants a

modification of the permit or is a minor modification based on site-specific information about the

injection project, including geologic information about the injection and confining zones, formation

fluids, and the well's construction. If the injectate from the new source were within the capacity of

the facility, this would be considered a minor modification per §144.41(h); otherwise the Director

must initiate a public process regarding the change in the permit. 

Please see the final rule and the discussion of testing and monitoring for GS projects in the preamble

for additional information.

Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality

(MDEQ)

Comment ID:

22119

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and

post-injection site care 

Comment: 18. EPA seeks comment on frequency of all reporting requirements. MDEQ believes 

that the proposed timeframe for post-closure recordkeeping and reporting is too 

short (page 43517). These projects are major facilities that should require a 

longer period of monitoring at least similar to other major industries. A 10-year 

minimum would be consistent with, for example, many surface mining operations 

that allow for reclamation to meet requirements. EPA's discussion of other 

factors for post-closure site care suggests at least a 10-year period. Seismic 

and surface level carbon dioxide monitoring needs to be continued. Further, 

this requirement should include the annual reporting that EPA considered, 

including the content listed. 

Response: EPA agrees and believes that data collected during the post-injection phase should be

retained throughout the post-injection site care timeframe and for ten years following site closure.

EPA agrees with commenters who suggested that well plugging reports be retained for longer than

one year. EPA has clarified the recordkeeping requirements in the final GS rule, which includes
requirements that well plugging reports, as required at §146.92(d), post-injection site care data, as

required at §146.93(f), and site closure reports, as required at §146.93(h), be kept for ten years after

site closure.

EPA believes that longer record retention requirements for Class VI wells are appropriate and

necessary for the post-injection and site closure period to ensure that data are available to support

non-endangerment demonstrations and to address any concerns that may arise following site closure.

This data will also support EPA's review of project data as part of the adaptive rulemaking approach.

See the final rule and preamble for further discussion on EPA's final approach to post-injection site

care.

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22644

Comment: Much Data Is Collected; But how is it used and who has access to the data? 

o Page 43514 includes a requirement that mechanical integrity be demonstrated 

annually, but it does not say what is done with this information or what it is 

used for. How long is this data retained? 

o Page 43514 includes a requirement that owners / operators report semi-annually 

on the injection pressure, flow rate, temperature, volume and annular pressure 

and on MIT test results. What is the data collection method and who will have 

access to these data? Is it an open website like the Toxic Report Inventory 

(TRI) where any citizen could view this information, or is it a single hard copy 

report locked in a state or regional EPA office that can only be seen via a FOIA 

request by members of the public or other stakeholders? 

Response: EPA has clarified the recordkeeping requirements in the final GS rule, which includes

requirements that well plugging reports, as required at §146.92(d), post-injection site care data, as

required at §146.93(f), and site closure reports, as required at §146.93(h), be kept for ten years after

site closure. See the final rule and preamble for further discussion on EPA's final approach to postinjection site care. 

EPA will use the data to verify that the well and the site are behaving as predicted and within

permitted guidelines to ensure that USDWs are protected from endangerment. In addition, the data

may be used as evidence of a violation of a permit requirement that may result in an enforcement

action under SDWA. The Agency clarifies that owners or operators may claim confidential business

information under existing UIC regulations at §144.5. These requirements are applicable to all well

classes.

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22647

Comment: o Page 43517 contains a requirement to report various data on the performance of 

GS on a semi-annual basis, but again it is not clear how these data will be 

used, retained, or who has access to them. 
Response: EPA has clarified the recordkeeping requirements in the final GS rule, which includes

requirements that well plugging reports, as required at §146.92(d), post-injection site care data, as

required at §146.93(f), and site closure reports, as required at §146.93(h), be kept for ten years after

site closure. See the final rule and preamble for further discussion on EPA's final approach to postinjection site care. 

EPA will use the data to verify that the well and the site are behaving as predicted and within

permitted guidelines to ensure that USDWs are protected from endangerment. In addition, the data

may be used as evidence of a permit violation that would result into an enforcement action. The

Agency clarifies that owners or operators may claim confidential business information under existing

UIC regulations at §144.5. These requirements are applicable to all well classes.

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23418

Other EPA Comment Codes and Descriptions: 5800 2.13 Comments on emergency and remedial

response (40 CFR 146.94) 

Comment: data point. We also suggest that the EPA have some reasonable test for response 

to the state or Federal permitting agency in the event that a reporting event 

happens on a weekend or during nighttime hours. Some owner/operators will be on 

different time zones than the injection well operator. APPA suggests that a 

reasonable time be allowed for reporting to be sent in on routine data where 

there is no catastrophic reporting event. 

Response: EPA clarifies that the requirement at §146.94(b)(3) is to notify the Director within 24

hours of an emergency. The Agency believes that the 24 hour timeframe for notifying the Director is

a "reasonable" time period. Furthermore, permitting agency response personnel are typically "on

call" 24 hours a day, 7 days a week.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24186

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

language; 4520 2.5.1 Continuous internal mechanical integrity monitoring (seeking comment) 

Comment: Rule Provision: 146.89(b) 

API Comments: (b) To evaluate the absence of significant leaks under paragraph 

(a)(1) of this section, owners or operators must, following an initial annulus 

pressure test, continuously monitor AND RECORD AT LEAST DAILY, ANNULUS PRESSURE 

AND VOLUMES OF PACKER FLUID INJECTED OR REMOVED FROM injection pressure, rate,

injected volumes, and pressure on the annulus between THE tubing and long 

stem STRING casing and annulus fluid volume as specified in §146.88 (e);

Rationale: Technical clarification. 

Response: EPA agrees with the commenter regarding the importance of demonstrating internal

mechanical integrity (MI), but disagrees with the suggested changes. Class VI injection wells must

be equipped with dedicated computer-based continuous pressure monitoring devices in concert with
the shut-off systems required for GS wells, which typically take readings several times per second

(i.e., more frequently than daily) and record them electronically in a computer system. See §146.88.

For additional information, please see the discussion of MITs in the final rule preamble.

EPA also disagrees that it is necessary to report volumes of packer fluid injected or removed. EPA

agrees with the commenter that recording annulus fluid volume may not be appropriate. EPA

believes that knowing annulus fluid volume (146.88(e)) is a necessary component of monitoring well

mechanical integrity, but believes that knowing the annulus fluid volume added is sufficient to meet

the intent of the requirement. The final GS rule requires that owners or operators use continuous

recording devices to monitor injection pressure, rate, and volume, as well as the pressure on the

annulus between the tubing and the long string casing. It also modifies the requirement in the

proposed rule to continuously monitor annulus fluid volume; it now requires recording of annulus

fluid volume added. See §§146.88(e); 146.89(b); and 146.90 (b). 

The final rule includes the suggested change from “long-stem” to “long-string” casing.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24198

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

language 

Comment: Rule Provision: 146.91(a) 

API Comments: (a) Semi-annual OR LESS FREQUENT AT THE DISCRETION OF THE

DIRECTOR 

reports containing: 

(1) Any SIGNIFICANT changes to the physical, chemical and other relevant 

characteristics of the carbon dioxide stream from the proposed operating data; 

Rationale: Over the life of the project, the Director may decide that less 

reporting is acceptable 

(1) Technical clarification. Significance can be determined by a statistical 

analysis of the data. Rules should recognize that there will be minor variations 

in many data sets over time. 

Rule Provision: 146.91(a) 

API Comments: (3) A description of any SIGNIFICANT event that exceeds operating 

parameters for annulus pressure or injection pressure as specified in the 

permit; 

(4) A description of any SIGNIFICANT event which triggers a shutdown device 

required pursuant to §146.88(e) and the response taken; 

Rationale: EPA should consider some significance threshold on reporting these 

events to avoid reporting events that would be of limited interest or 

consequence. 

Response: EPA disagrees that less frequent than semi-annual reporting is appropriate to protect

USDWs from endangerment. The Agency believes semi-annual reporting is appropriate and
necessary for Class VI wells during the operational phase of the project. EPA believes that the

potentially large injection volumes and injection pressures associated with GS warrant more frequent

reporting than for other well classes. See the final rule and preamble for further discussion on EPA's

final approach to testing and monitoring. 

EPA also retained the provision at §146.91(a)(3) as proposed. The final rule at §146.91(a)(3)

requires reporting of all exceedances of operating parameters. EPA disagrees with the suggestion to

report only "significant" exceedances. Making a determination as to whether an exceedance is

"significant" is not the purpose of the requirement. EPA believes that the ability of an operator to

consistently meet operating requirements and avoid exceedances provides evidence of a wellmanaged GS project that is in compliance with the Class VI permit. If multiple exceedances occur,

the Director should be aware of such occurrences, determine whether these indicate problems at the

site, and determine the appropriate course of action (e.g., a well workover, modification of operating

parameters, or imposition of a penalty).

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24475

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

language; 4520 2.5.1 Continuous internal mechanical integrity monitoring (seeking comment) 

Comment: Rule Provision: 146.89(b) 

Proposed CCS Group Recommendations: (b) To evaluate the absence of significant 

leaks under paragraph (a)(1) of this section, owners or operators must, 

following an initial annulus pressure test, continuously monitor AND RECORD AT 

LEAST DAILY, ANNULUS PRESSURE AND VOLUMES OF FLUID ADDED TO OR

REMOVED FROM 

injection pressure, rate, injected volumes, and pressure on the annulus 

between the tubing and long stem string casing and annulus fluid volume as 

specified in §146.88 (e);

Basis for CCS Group Comments: We recommend continuous monitoring, but do not 

find continuous recording necessary as Class II requirements have proven 

sufficient. The alternative of continuous monitoring, which will alert operator 

to any problems, and daily recording to allow for daily check of wells. This is 

consistent with successful Class II operating experience. 

Response: EPA agrees with the commenter regarding the importance of demonstrating internal

mechanical integrity (MI). Class VI injection wells will be equipped with dedicated computer-based

continuous pressure monitoring devices, in concert with the shut-off systems required for GS wells,

which typically take readings several times per second (i.e., more frequently than daily) and record

them electronically in a computer system. 40 CFR §146.91(a)(2) requires that monthly averages of

the continuous annulus monitoring be reported on a semiannual basis.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24487

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

language 

Comment: Rule Provision: 146.91(a)(1) 
Proposed CCS Group Recommendations: (1) Any SIGNIFICANT changes to the physical, 

chemical and other relevant characteristics of the carbon dioxide stream from 

the proposed operating data; 

Basis for CCS Group Comments: (1) Technical clarification. Significance can be 

determined by a statistical analysis of the data. Rules should recognize that 

there will be minor variations in many data sets over time. 

Response: EPA retained this provision as proposed. The final rule at §146.91(a)(3) requires

reporting of all exceedances of operating parameters. EPA disagrees with the suggestion to report

only "significant" exceedances. Making a determination as to whether an exceedance is "significant"

is not the purpose of the requirement. EPA believes that the ability of an operator to consistently

meet operating requirements and avoid exceedances provides evidence of a well-managed GS

project that is in compliance with the Class VI permit. If multiple exceedances occur, the Director

should be aware of such occurrences, and that information will aid in his/her determination of

whether these indicate problems at the site, and what is the appropriate course of action (e.g., a well

workover, modification of operating parameters, or imposition of a penalty) to remediate such

problem(s).

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24488

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

language 

Comment: Rule Provision: 146.91(a)(3) & (4) 

Proposed CCS Group Recommendations: (3) A description of any SIGNIFICANT event 

that exceeds operating parameters for annulus pressure or injection pressure as 

specified in the permit; 

(4) A description of any SIGNIFICANT event which triggers a shutdown device 

required pursuant to §146.88(e) and the response taken; 

Basis for CCS Group Comments: EPA should consider some significance threshold on 

reporting these events to avoid reporting events that would be of limited 

interest or consequence. 

Response: EPA retained this provision as proposed. The final rule at §146.91(a)(3) requires

reporting of all exceedances of operating parameters. EPA disagrees with the suggestion to report

only "significant" exceedances. Making a determination as to whether an exceedance is "significant"

is not the purpose of the requirement. EPA believes that the ability of an operator to consistently

meet operating requirements and avoid exceedances provides evidence of a well-managed GS

project that is in compliance with the Class VI permit. If multiple exceedances occur, the Director

should be aware of such occurrences, and that information will aid in his/her determination of

whether these indicate problems at the site, and what is the appropriate course of action (e.g., a well

workover, modification of operating parameters, or imposition of a penalty) to remediate such

problem(s).
Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24489

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

language; 4740 2.7.4 Electronic reporting (seeking comment) 

Comment: Rule Provision: 146.91(b) & (c) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment and the final rule retains the text as proposed. See the

final rule and preamble for further discussion on EPA's final approach to reporting and

recordkeeping.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24698

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

language; 4520 2.5.1 Continuous internal mechanical integrity monitoring (seeking comment) 

Comment: Rule Provision: 146.89(b) 

Anadarko Petroleum Corporation (APC) Comments: (b) To evaluate the absence of 

significant leaks under paragraph (a)(1) of this section, owners or operators 

must, following an initial annulus pressure test, continuously monitor AND 

RECORD AT LEAST DAILY, ANNULUS PRESSURE AND VOLUMES OF PACKER FLUID

INJECTED OR 

REMOVED FROM injection pressure, rate, injected volumes, and pressure on the 

annulus between THE tubing and long stem STRING casing and annulus fluid 

volume as specified in §146.88 (e);

Rationale: Technical clarification. 

Response: EPA agrees with the commenter regarding the importance of demonstrating internal

mechanical integrity (MI), but disagrees with the suggested changes. Class VI injection wells will be

equipped with dedicated computer-based continuous pressure monitoring devices in concert with the

shut-off systems required for GS wells, which typically take readings several times per second (i.e.,

more frequently than daily) and record them electronically in a computer system. 40 CFR

§146.91(a)(2) requires that monthly averages of the continuous annulus monitoring be reported on a

semiannual basis.

40 CFR §146.91(a)(2) requires that monthly averages of the continuous annulus monitoring be

reported on a semiannual basis. EPA agrees with the commenter that recording annulus fluid volume

may not be appropriate. EPA believes that annulus fluid volume (146.88(e)) is a necessary

component of monitoring well mechanical integrity, but believes that knowing the annulus fluid

volume added is sufficient to meet the intent of the requirement. The final GS rule requires that

owners or operators use continuous recording devices to monitor injection pressure, rate, and

volume, as well as the pressure on the annulus between the tubing and the long string casing. It also

modifies the requirement in the proposed rule to continuously monitor annulus fluid volume; it now

requires recording of annulus fluid volume added. See §§146.88(e), 146.89(b), and 146.90 (b). The

final rule implements the suggested change from “long-stem” to “long-string” casing.
Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24711

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

language 

Comment: Rule Provision: 146.91(a) 

Anadarko Petroleum Corporation (APC) Comments: (a) Semi-annual OR LESS FREQUENT 

AT THE DISCRETION OF THE DIRECTOR reports containing: 

(1) Any SIGNIFICANT changes to the physical, chemical and other relevant 

characteristics of the carbon dioxide stream from the proposed operating data; 

Rationale: Over the life of the project, the Director may decide that less 

reporting is acceptable 

(1) Technical clarification. Significance can be determined by a statistical 

analysis of the data. Rules should recognize that there will be minor variations 

in many data sets over time. 

Response: EPA retained this provision as proposed. The final rule at §146.91(a)(3) requires

reporting of all exceedances of operating parameters. EPA disagrees with the suggestion to report

only "significant" exceedances. Making a determination as to whether an exceedance is "significant"

is not the purpose of the requirement. EPA believes that the ability of an operator to consistently

meet operating requirements and avoid exceedances provides evidence of a well-managed GS

project that is in compliance with the Class VI permit. If multiple exceedances occur, the Director

should be aware of such occurrences, and that information will aid in his/her determination of

whether these indicate problems at the site, and what is the appropriate course of action (e.g., a well

workover, modification of operating parameters, or imposition of a penalty) to remediate such

problem(s).

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24712

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

language 

Comment: Rule Provision: 146.91(3) & (4) 

Anadarko Petroleum Corporation (APC) Comments: (3) A description of any 

SIGNIFICANT event that exceeds operating parameters for annulus pressure or 

injection pressure as specified in the permit; 

(4) A description of any SIGNIFICANT event which triggers a shutdown device 

required pursuant to §146.88(e) and the response taken; 

Rationale: EPA should consider some significance threshold on reporting these 

events to avoid reporting events that would be of limited interest or 

consequence. 

Response: EPA retained this provision as proposed. The final rule at §146.91(a)(3) requires
reporting of all exceedances of operating parameters. EPA disagrees with the suggestion to report

only "significant" exceedances. Making a determination as to whether an exceedance is "significant"

is not the purpose of the requirement. EPA believes that the ability of an operator to consistently

meet operating requirements and avoid exceedances provides evidence of a well-managed GS

project that is in compliance with the Class VI permit. If multiple exceedances occur, the Director

should be aware of such occurrences, and that information will aid in his/her determination of

whether these indicate problems at the site, and what is the appropriate course of action (e.g., a well

workover, modification of operating parameters, or imposition of a penalty) to remediate such

problem(s).

Commenter Name: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22160

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

permit applications (seeking comment) 

Comment: Permit Application 

Southern Company opposes EPA's proposed requirements for Class VI permit 

applications to the extent that those requirements are more burdensome than 

current permit application requirements for other classes of UIC wells. id. at 

43517. C02 GS does not pose unique risks warranting many of the Proposal's 

additional requirements for detailed information. 

EPA should craft the Final Rule to require in the initial permit application 

information that the Director will need to determine whether issuance of a Class 

VI permit is appropriate. EPA could require submission of supplemental 

information as it becomes available through drilling, construction, and 

reevaluation of the well. This will not only prevent against the chilling effect 

that overly burdensome permit application requirements would have on the CO2 GS 

program, but will simultaneously ensure the ultimate collection of more thorough 

and reliable data. 

Response: EPA believes that the unique characteristics of CO2 injection (e.g., its relative buoyancy,

the large volume that may be injected, or the potential for chemical interaction with the subsurface)

warrant the additional information required to be submitted by Class VI operators under §146.82.

EPA disagrees that Directors should have the authority to waive some of the application

requirements. In order to protect USDWs from endangerment, Directors must have all the data

necessary to make well-informed decisions on establishing permit conditions and granting permits.

In response to concerns that some data will not be available until the well has been drilled, EPA

acknowledges 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 Class VI permit application. Based on

comments and evaluation of the proposed requirements, EPA revised this subpart so that the final

regulation specifies separate requirements for information to be submitted for approval with the

permit application before well construction, as required at §146.82(a), and information to be

submitted after the well is constructed; however, all data must be provided before injection is

authorized, as required at §146.82(c).

Commenter Name: Neeraj Gupta Letter ID: 0229
Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21862

Comment: Page 111, Semi-Annual Reporting- Some of our sites have required monthly 

operating reports. Would this reduce reporting to semi-annual? We would 

appreciate additional clarification. 

Response: Existing pilot projects will continue to be regulated under their Class V experimental

well permits and must meet the reporting requirements set forth in the individual permit. EPA

expects that, as the permits for these Class V projects expire or if owners or operators of Class V

projects seek to apply for a Class VI permit (provided construction components are grandfathered),

they would be re-permitted as Class VI wells (subject to reporting requirements at §146.91). If the

projects continue to be of an experimental nature, the wells may continue to be permitted as Class V

experimental technology wells (subject to the reporting requirements in the permit).

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24916

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

language; 4520 2.5.1 Continuous internal mechanical integrity monitoring (seeking comment) 

Comment: EPA Proposal: (b) To evaluate the absence of significant leaks under paragraph 

(a)(1) of this section, owners or operators must, following an initial annulus 

pressure test, continuously monitor injection pressure, rate, injected volumes, 

and pressure on the annulus between tubing and long stem casing and annulus 

fluid volume as specified in § 146.88(e); 

GWPC Recommendations: (b) To evaluate the absence of significant leaks under 

paragraph (a)(1) of this section, owners or operators must, following an initial 

annulus pressure test, continuously monitor and record at least daily injection 

pressure, rate, injected volumes, and pressure on the annulus between tubing 

and long stem casing and annulus fluid volume as specified in §146.88 (e); 

Rationale: We believe that injection parameters must not only be monitored but 

should be recorded at least daily. We further believe the use of monitoring with 

digital equipment which records readings on an appropriate frequency should be 

considered continuous for purposes of this section. 

Response: EPA believes that continuous pressure monitoring to demonstrate internal mechanical

integrity of Class VI wells required at §146.89(b) is important, given the potential corrosive impact

of CO2 and impurities on well materials, the potential geomechanical impacts to well integrity due to

CO2 phase changes, and the temperature and pressure effects associated with injecting supercritical

CO2. EPA also believes that the technology for continuous monitoring is practicable, available, and

is currently in fairly wide use. Class VI injection wells will be equipped with dedicated computerbased continuous pressure monitoring devices (in concert with the shut-off systems required for GS

wells), which typically take readings several times per second (i.e., more frequently than daily) and

record them electronically in a computer system. 40 CFR §146.91(a)(2) requires that monthly

averages of the continuous annulus monitoring be reported on a semiannual basis. For additional

information, please see the discussion of MITs in the final rule preamble.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24933
Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

Comment: Rule Provision: 146.91(a) 

EPA Proposal: (3) A description of any event that exceeds operating parameters 

for annulus pressure or injection pressure as specified in the permit; 

(4) A description of any event which triggers a shutdown device required 

pursuant to § 146.88(e) and the response taken; 

(5) The monthly volume of the carbon dioxide stream injected over the reporting 

period and project cumulatively; 

(6) Monthly annulus fluid volume added; and 

(7) The results of monitoring prescribed under § 146.90. 

GWPC Recommendations: (3) A description of any event that significantly exceeds 

operating parameters for annulus pressure or injection pressure as specified in 

the permit; 

(4) A description of any event which triggers a shutdown device required 

pursuant to §146.88(e) and the response taken; 

Rationale: EPA should consider some significance threshold on reporting these 

events, to avoid reporting events would be of limited interest or consequence. 

Response: EPA retained this provision as proposed. The final rule at §146.91(a)(3) requires

reporting of all exceedances of operating parameters. EPA disagrees with the suggestion to report

only "significant" exceedances. Making a determination as to whether an exceedance is "significant"

is not the purpose of the requirement. EPA believes that the ability of an operator to consistently

meet operating requirements and avoid exceedances provides evidence of a well-managed GS

project that is in compliance with the Class VI permit. If multiple exceedances occur, the Director

should be aware of such occurrences, and that information will aid in his/her determination of

whether these indicate problems at the site, and what is the appropriate course of action (e.g., a well

workover, modification of operating parameters, or imposition of a penalty) to remediate such

problem(s).

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24934

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

language; 4740 2.7.4 Electronic reporting (seeking comment) 

Comment: EPA Proposal: (b) Report, within 30 days the results of: 

(1) Periodic tests of mechanical integrity; 

(2) Any other test of the injection well conducted by the permittee if required 

by the Director; and 

(3) Any well workover. 

(c) Owners or operators must submit reports in an electronic format acceptable 

to the Director. At the discretion of the Director, other formats may be 

accepted. 

GWPC Recommendations: Support the proposed EPA language. 
Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. Please see the final rule and the discussion of reporting

preamble for additional information on EPA's final rulemaking approach.

EPA believes that electronic formatting is the most appropriate format for submitting Class VI

project information to the Director, and that many GS well owners or operators will have the

capability to report electronically.

Comment Code: 4730 2.7.3 Reporting associated with closure and post-injection site care 

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: 21988

Other EPA Comment Codes and Descriptions: 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: 146.93 (f): This will be impractical for large sequestration projects due to the 

paperwork and legal work to deal with a significant number of parties. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention

such as site closure reports. EPA believes that the requirements that the owner or operator retain for

ten years following site closure, records collected during the post-injection site care period at

§146.93(f) and §146.93(h) are appropriate for the post-injection and site closure period to ensure that

data are available to support non-endangerment demonstrations and to address any concerns that may

arise following site closure. This data will also support EPA's review of project data as part of the

adaptive rulemaking approach.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24801

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

language; 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Comment: (4) THE OWNER OR OPERATOR MAY May modify and resubmit the post-injection 

site care and site closure plan for the Director's approval within 30 days of 

such change. 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24805

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

language 
Comment: (c) Notice of intent for site closure. Must notify the Director at least 120 

days before site closure. At this time, if any changes have been made to the 

original post-injection site care and site closure plan, THE OWNER OR OPERATOR 

must also provide the revised plan. At the discretion of the Director, a shorter 

notice period may be allowed. 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment EPA has made many revisions to the GS Rule. See the final rule

and discussion of post-injection site care in the preamble to the rule for further discussion on EPA's

final approach.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24807

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

language; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: (e) Once the Director has authorized site closure, THE OWNER OR OPERATOR must 

submit a site closure report within 90 days that must thereafter be retained at 

a location designated by the Director. The report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. Must provide a copy of 

a survey plat which has been submitted to the local zoning authority designated 

by the Director, which indicates the location of the injection well relative to 

permanently surveyed benchmarks. Must also submit a copy of the plat to the 

regional administrator of the appropriate EPA Regional Office; 

{Why is this necessary? The EPA regional office will have access to all records 

at the State. } 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on

the deed to the facility property or other similar document examined during a title search that the

land has been used to sequester CO2 at the time of site closure.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24808

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

language; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: (f) THE OWNER OR OPERATOR MUSTMust record a notation on the deed to the 

facility property or any other document that is normally examined during title 

search that will in perpetuity provide any potential purchaser of the property 

the following information: 

(1) The fact that land has been used to sequester carbon dioxide; 

(2) The name of the State agency, local authority, and/or tribe with which the 

survey plat was filed, as well as the address of the Regional EPA Office to 

which it was submitted; and (3) The volume of fluid injected, the injection 

zone or zones into which it was injected, and the period over which 

injection occurred. 
Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation that

the land has been used to sequester CO2 on the deed to the facility property at the time of site

closure.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24809

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

language; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: (g) Must retain for three years following site closure, records collected during 

the post-injection site care period. THE OWNER OR OPERATOR MUST Must

deliver the records to the Director at the conclusion of the retention period, 

and the records must thereafter be retained at a location designated by the 

Director for that purpose. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention

such as site closure reports. EPA believes that the requirements that the owner or operator retain for

ten years following site closure, records collected during the post-injection site care period at

§146.93(f) and §146.93(h) are appropriate for the post-injection and site closure period to ensure that

data are available to support non-endangerment demonstrations and to address any concerns that may

arise following site closure. This data will also support EPA's review of project data as part of the

adaptive rulemaking approach.

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22611

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

language 

Comment: Proposed Rule: 146.92(b) 

Proposed revision: (b) Well Plugging Plan. The owner or operator of a Class VI 

well must prepare; maintain; including updating on the same schedule as the 

update to the Area of Review; and comply with a plan that is acceptable to the 

Director. The requirement to maintain and implement an approved plan is 

directly... 

Rationale: The Area of Review re-evaluation should trigger a review and updating 

of all the plans (MMV, financial, plugging, emergency response...) on the same 

interval that the AOR is updated. NGWA suggests EPA check all timelines and 

make them compatible. 

Response: EPA agrees that the AoR reevaluations offer a good opportunity to promote a dialogue

between the owner or operator and the permitting authority. Additionally, EPA recognizes that the

AoR reevaluation has the potential to change or add important data to the other project plans and

therefore the Agency agrees that the other Class VI plans must be updated when an AoR

reevaluation takes place. The final GS rule, at §§146.84(c), 146.90(j), and 146.94(d), requires owners

or operators to review and update the AoR and corrective action plan, the testing and monitoring

plan, and the emergency and remedial response plan throughout the life of the project. Owners or

operators must review each plan and identify necessary amendments to the plan or demonstrate to
the Director that no amendment is needed. These reviews must be performed within one year of an

AoR reevaluation, following any significant changes to the facility (e.g., the addition of monitoring

or injection wells), or when required by the Director. In no case can reviews occur less often than

once every five years. EPA is preparing guidance for owners or operators on developing and

updating all of the required GS project plans. The guidance will be available on EPA's web site, at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. See the final rule and preamble

for further discussion on EPA's final approach regarding the GS project plans.

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22612

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

language; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 146.92) 

Comment: Proposed Rule: 146.92(d) 

Proposed revision: (d) Plugging Reports for Class VI Wells. Within 60 days 

after completion of plugging and abandonment of a well or well field the 

permittee shall submit to the Director a final report which includes: 

Proposed addition: (1) Certification of completion in accordance with approved 

plans and specifications by an appropriately qualified engineer of record or 

professional geologist. 

Note: It is important that the engineer and/or geologist have expertise and 

training in injection well drilling technology, reservoir characterization and 

injection well construction and operation. 

Proposed addition: (2) Evidence, such as a sealed copy or certification from the 

county clerk, that a surveyor's plot of the location of the abandoned well has 

been recorded in the county courthouse property records. 

Response: EPA agrees that appropriately qualified personnel (e.g., engineers and geologists) should

be involved in all aspects of the GS operation, including the well plugging process. When the owner

or operator (and/or the person who performs the plugging operation) signs the plugging report and

certifies it as accurate; they are attesting to the fact that all required activities were performed by

qualified personnel. This is required under §146.92(d) and is a condition of the permit that is

enforceable under §1423 of the SDWA. EPA clarifies that, in addition to requiring appropriate well

plugging, the Director retains the option of witnessing any plugging activity or testing at the well. 

EPA clarifies that §146.93(g) requires the owner or operator, as part of the closure process, to record

a notation on the deed stating that the property was used for GS. In addition, §146.93(f)(1) requires

submission of a survey plat indicating the location of the well to the local zoning authority, as well

as to the Director. 

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22613

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

language; 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Proposed Rule: 146.93(a) 
Proposed revision: (a) The owner or operator of a Class VI well must prepare; 

maintain; including updating on the same schedule as the update to the Area of 

Review; and comply with a plan for post-injection site care and site closure 

that meets the requirements of paragraph (a)(2) of this section and is 

acceptable to the Director. 

Rationale: The Area of Review re-evaluation should trigger a review and updating 

of the well plugging plan, and the post injection site care and closure plan. 

NGWA suggests EPA check all timelines and make them compatible. 

Response: EPA agrees with the commenter that, in some cases, the appropriate post-injection

monitoring strategy may end up being different than initially projected at the time of permit

application and there may be a need to amend the post-injection site care and site closure plan. EPA

is requiring that upon the cessation of injection, the owner or operator submit an amended postinjection site care and site closure plan or demonstrate to the Director that no changes to the original

post-injection site care and site closure plan are necessary, as specified in §146.93(a)(3). EPA is not

requiring formal periodic review and updates to the PISC and site closure plan throughout the

injection phase. EPA does not expect that changes to this plan would be implemented until injection

operations cease. EPA envisions that owners or operators will take into account similar

considerations that guide updates to other project plans, e.g., monitoring and operational data and

results of AoR reevaluations. 

EPA has also added a new provision at §144.39(a)(5) requiring a modification, revocation, or

reissuance of a Class VI permit whenever the Director determines that a change in the permit is

necessary based on an amended AoR and corrective action plan, testing and monitoring plan,

injection well plugging plan, post-injection site care and site closure plan, or emergency and

remedial response plan is necessary. This would invoke the public notification procedures of 40 CFR

Part 124 and the modification would be incorporated into the permit. EPA adds that, if any

monitoring or other site data indicate a need for amending the post-injection site care plan, the

owner or operator is expected to amend the plan accordingly.

Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality

(MDEQ)

Comment ID:

22119

Other EPA Comment Codes and Descriptions: 4720 2.7.2 Operational recordkeeping and

reporting 

Comment: 18. EPA seeks comment on frequency of all reporting requirements. MDEQ believes 

that the proposed timeframe for post-closure recordkeeping and reporting is too 

short (page 43517). These projects are major facilities that should require a 

longer period of monitoring at least similar to other major industries. A 10-year 

minimum would be consistent with, for example, many surface mining operations 

that allow for reclamation to meet requirements. EPA's discussion of other 

factors for post-closure site care suggests at least a 10-year period. Seismic 

and surface level carbon dioxide monitoring needs to be continued. Further, 

this requirement should include the annual reporting that EPA considered, 

including the content listed. 

Response: EPA agrees and believes that data collected during the post-injection phase should be
retained throughout the post-injection site care timeframe and for ten years following site closure.

EPA agrees with commenters who suggested that well plugging reports be retained for longer than

one year. EPA has clarified the recordkeeping requirements in the final GS rule, which includes

requirements that well plugging reports, as required at §146.92(d), post-injection site care data, as

required at §146.93(f), and site closure reports, as required at §146.93(h), be kept for ten years after

site closure.

EPA believes that longer record retention requirements for Class VI wells are appropriate and

necessary for the post-injection and site closure period to ensure that data are available to support

non-endangerment demonstrations and to address any concerns that may arise following site closure.

This data will also support EPA's review of project data as part of the adaptive rulemaking approach.

See the final rule and preamble for further discussion on EPA's final approach to post-injection site

care.

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22650

Other EPA Comment Codes and Descriptions: 5280 2.8.2.4 USDW non-endangerment

demonstrations 

Comment: o Page 43517. Records retention of only 3 years after site closure. That seems 

incredibly short. Also it is not clear how this requirement to hold on to these 

data for three years after site closure is consistent with the owner operators 

requirement to discharge its responsibilities under the post closure period 

including establishing that non-endangerment continues to be the case. Wouldn’t 

access to baseline and data collected during the period of principal operations 

be needed to report out these findings during the period of post closure. This 

short record retention period also seems to undercut assertion of a open 

continuous dialogue being a center piece of how USEPA and any states that have 

Class VI primacy will ensure public safety. 

Response: EPA has changed the recordkeeping requirement in the final rule to require that owners

or operators retain records collected during the post-injection site care period for at least 10 years

following site closure. EPA believes that the requirements that the owner or operator retain for ten

years following site closure, records collected during the post-injection site care period at §146.93(f)

and §146.93(h) are appropriate to ensure that data are available to support non-endangerment

demonstrations and to address any concerns that may arise following site closure. This data will also

support EPA's review of project data as part of the adaptive rulemaking approach.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24202

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

language; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 146.92) 

Comment: Rule Provision: 146.92(d) 

API Comments: (d) Plugging report. Within 60 days after plugging the owner or 

operator must submit a plugging report to the Director. If the semi-annual 

report is due less than 15 days after completion of plugging, then the report 
must be submitted within 60 days after plugging. The report must be certified 

as accurate by the owner or operator and by the person who performed the 

plugging operation (if other than the owner or operator.) 

Rationale: The proposed changes are suggested to simplify and clarify a 

provision that API believes is needlessly complicated. 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads,

"Within 60 days after plugging, the owner or operator must submit a plugging report to the

Director."

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24205

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

language; 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Comment: Rule Provision: 146.93(a)(4) 

API Comments: (4) AT ANY TIME DURING THE POST-INJECTION SITE CARE PHASE, The 

owner or operator may modify and resubmit the post-injection site care and site 

closure plan for the Director‘s approval within 30 days of such change. 

Rationale: Technical Clarification. 

Response: EPA agrees that a post-injection site care monitoring plan is an important tool for GS,

and anticipates that, in some cases, the appropriate post-injection monitoring strategy may end up

being different than initially projected, and there may be a need to amend the post-injection site care

and site closure plan. EPA is requiring that upon the cessation of injection, the owner or operator

submit an amended post-injection site care and site closure plan or demonstrate to the Director that

no changes to the original post-injection site care and site closure plan are necessary (§146.93(a)(3)).

EPA is not requiring formal periodic review and updates to the PISC and site closure plan

throughout the injection phase. EPA does not expect that changes to this plan would be implemented

until injection operations cease. EPA envisions that owners or operators would take into account

similar considerations that guide updates to other project plans, e.g., monitoring and operational data

and results of AoR reevaluations. EPA adds that, if any monitoring or other site data indicate a need

for amending the post-injection site care plan, the owner or operator is expected to amend the plan

accordingly. 

EPA adds that, in the final rule, it has revised the text at §146.93(a)(4) as follows: "At any time

during the life of the geologic sequestration project, the owner or operator may modify and resubmit

the post-injection site care and site closure plan for the Director’s approval within 30 days of such

change."

EPA is issuing guidance on development and updating of the GS project plans, including the postinjection site care and site closure plan. The guidance will be available on EPA's web site, at

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

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24210
Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Rule Provision: 146.93(e) 

API Comments: (e) Once the Director has authorizeSd site closure, the 

owner or operator must submit a site closure report within 90 days that must 

thereafter be retained at a location designated by the Director. AFTER 

COMPLETION OF ALL CLOSURE OPERATIONS. The report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the location 

of the injection well(S) relative to permanently surveyed benchmarks. The owner 

or operator must also submit a copy of the plat to the Regional Administrator of 

the appropriate EPA Regional Office; 

Rationale: Once the site closure report is submitted to the Director, the 

operator cease to bear responsibility for any further record retention. At this 

point, EPA becomes the steward of information for the project. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention

such as site closure reports. EPA believes that the requirements that the owner or operator retain, for

ten years following site closure, records collected during the post-injection site care period at

§146.93(f) and §146.93(h) are appropriate for the post-injection and site closure period to ensure that

data are available to support non-endangerment demonstrations and to address any concerns that may

arise following site closure. This data will also support EPA's review of project data as part of the

adaptive rulemaking approach.

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 25116

Comment: [FN15] The proposed regulations would also require the permittee to record a 

notice on the deed (or other relevant document) to the "facility property" 

containing certain information. While EEI is not opposed to the concept of a 

deed notice, more clarity is needed in the regulations regarding how "facility 

property" is to be defined in order to better understand the scope of the 

proposed requirement. EEI recommends limiting "facility property" to the area 

immediately surrounding the injection well. 

Response: EPA believes the requirements for submitting of survey plats, as specified at §146.93(f),

and recording a notation on the deed to the facility property that the land has been used to sequester

CO2, as specified at §146.93(g) are sufficiently clear. Additionally, they are important to ensure that

future land owners do not inadvertently drill wells or perform other activities that may compromise

the injection zone and/or confining zone and cause CO2 or other fluids to migrate into USDWs or

other formations or to the surface. While EPA recognizes that this may entail a large area at large

GS sites, the Agency believes that this requirement is necessary to maximize protection of USDWs

from endangerment and human health. Please note that “facility” is defined at §144.3. See the final

rule and preamble for further discussion on EPA's final approach to site closure.
Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23848

Comment: 2. Records Retention 

Under the proposal, owners and operators would be required to maintain 

recordkeeping and reporting information for the duration of the project, as well 

as for three years after site closure (following the post-injection site care 

period). Owners and operators also would be required to keep their most recent 

plugging and abandonment report for one year following site closure. Under 

proposed requirement 40 C.F.R. $ 146.93(g), EPA would require that the owner or 

operator deliver to the Director records collected during the post-injection 

site care period at the conclusion of the 3-year retention period. The CCS 

Alliance is concerned that some of this information may be of a confidential 

financial or business operations nature and should be protected from public 

disclosure. Thus, the CCS Alliance recommends the inclusion of a "non-disclosure 

requirement" to protect certain sensitive and confidential business information 

from public disclosure. The CCS Alliance also requests EPA to consult with the 

U.S. Department of Homeland Security to determine whether CCS sites would 

constitute "critical infrastructure," thereby necessitating additional 

protection of sensitive information. 

Response: The Agency clarifies that owners or operators may claim confidential business

information under existing UIC regulations at 40 CFR 144.5. These requirements are applicable to

all well classes.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23702

Comment: With respect to the requirement for recordkeeping, AWWA recommends that the oneyear holding requirement for the plugging and abandonment report be extended. 

This is an extremely important report, and the owner/operator must be required 

to keep this report on file for a minimum of 10 years following the closure of 

the project site. 

Response: EPA is requiring that data collected during the post-injection phase be retained

throughout the post-injection site care timeframe and for ten years following site closure. EPA

agrees that well plugging reports should be retained for longer than one year. EPA has clarified the

recordkeeping requirements in the final GS rule, which includes requirements that well plugging

reports, as required at §146.92(d), post-injection site care data, as required at §146.93(f), and site

closure reports, as required at §146.93(h), be kept for ten years after site closure.

EPA believes that longer record retention times for GS wells are appropriate for the post-injection

and site closure period to ensure that data are available to support non-endangerment demonstrations

and to address any concerns that may arise following site closure. This data will also support EPA's

review of project data as part of the adaptive rulemaking approach.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24491

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule
language; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 146.92) 

Comment: Rule Provision: 146.92(c) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support and the final rule retains this approach.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24492

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

language; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 146.92) 

Comment: Rule Provision: 146.92(d) 

Proposed CCS Group Recommendations: (d) Plugging report. Within 60 days after 

plugging the owner or operator must submit a plugging report to the Director. 

If the semi-annual report is due less than 15 days after completion of 

plugging, then the report must be submitted within 60 days after plugging. The 

report must be certified as accurate by the owner or operator and by the person 

who performed the plugging operation (if other than the owner or operator.) 

Basis for CCS Group Comments: The proposed change will simplify and clarify a 

provision that is unnecessarily complicated. 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads,

"Within 60 days after plugging the owner or operator must submit a plugging report to the Director."

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24496

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

language; 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Comment: Rule Provision: 146.93(a)(4) 

Proposed CCS Group Recommendations: 4) AT ANY TIME DURING THE POST-INJECTION 

SITE CARE PHASE, The owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval within 30 

days of such change. 

Basis for CCS Group Comments: Technical Clarification. 

Response: EPA agrees that a post-injection site care monitoring plan is an important tool for GS and

anticipates that, in some cases, the appropriate post-injection monitoring strategy may end up being

different than initially projected and there may be a need to amend the post-injection site care and

site closure plan. EPA is requiring that upon the cessation of injection, the owner or operator submit

an amended post-injection site care and site closure plan or demonstrate to the Director that no

changes to the original post-injection site care and site closure plan are necessary (146.93(a)(3)).

EPA is not requiring formal periodic review and updates to the PISC and site closure plan
throughout the injection phase. EPA does not expect that changes to this plan would be implemented

until injection operations cease. EPA envisions that owners or operators would take into account

similar considerations that guide updates to other project plans, e.g., monitoring and operational data

and results of AoR reevaluations. EPA adds that, if any monitoring or other site data indicate a need

for amending the post-injection site care plan, the owner or operator is expected to amend the plan

accordingly under §146.93(a)(3). 

EPA adds that, in the final rule, it has revised the text at §146.93(a)(4) as follows: "At any time

during the life of the geologic sequestration project, the owner or operator may modify and resubmit

the post-injection site care and site closure plan for the Director’s approval within 30 days of such

change."

EPA is issuing guidance on development and updating of the GS project plans, including the postinjection site care and site closure plan. The guidance will be available on EPA's web site at

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

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24501

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

language 

Comment: Rule Provision: 146.93(c) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment and the final rule retains the text as proposed.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24503

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

language; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Rule Provision: 146.93(e) 

Proposed CCS Group Recommendations: (e) Once the Director has

authorizeSd site closure, the owner or operator must submit a site closure 

report within 90 days that must thereafter be retained at a location 

designated by the Director. AFTER COMPLETION OF ALL CLOSURE OPERATIONS. The 

report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the location 

of the injection well(S) relative to permanently surveyed benchmarks. The owner 

or operator must also submit a copy of the plat to the Regional Administrator of 

the appropriate EPA Regional Office; 
Basis for CCS Group Comments: Once the site closure report is submitted to the 

Director, the operator cease to bear responsibility for any further record 

retention. At this point, EPA becomes the steward of information for the 

project. 

Rule Provision: 146.93(e)(2) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Rule Provision: 146.93(f) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Rule Provision: 146.93(g) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention

such as site closure reports. EPA believes that the requirements that the owner or operator retain for

ten years following site closure, records collected during the post-injection site care period at

§146.93(f) and §146.93(h) are appropriate for the post-injection and site closure period to ensure that

data are available to support non-endangerment demonstrations and to address any concerns that may

arise following site closure. This data will also support EPA's review of project data as part of the

adaptive rulemaking approach.

The GS regulation at §146.93(g) requires the owner or operator to record a notation on the deed to

the facility property or other similar document examined during a title search that the land has been

used to sequester CO2 at the time of site closure.

EPA acknowledges the commenter’s support of the other parts; the final rule retains these provisions.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24715

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

language; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 146.92) 

Comment: Rule Provision: 146.92(d) 

Anadarko Petroleum Corporation (APC) Comments: (d) Plugging report. Within 60 

days after plugging the owner or operator must submit a plugging report to the 

Director. If the semi-annual report is due less than 15 days after completion 

of plugging, then the report must be submitted within 60 days after plugging.

The report must be certified as accurate by the owner or operator and by the 

person who performed the plugging operation (if other than the owner or 
operator.) 

Rationale: The proposed changes are suggested to simplify and clarify a 

provision that APC believes is needlessly complicated. 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads,

"Within 60 days after plugging the owner or operator must submit a plugging report to the Director."

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24718

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

language; 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Comment: Rule Provision: 146.93(a)(4) 

Anadarko Petroleum Corporation (APC) Comments: (4) AT ANY TIME DURING THE POSTINJECTION SITE CARE PHASE, The owner or operator may modify and resubmit the 

post-injection site care and site closure plan for the Director’s approval 

within 30 days of such change. 

Rationale: Technical Clarification. 

Response: EPA agrees that a post-injection site care monitoring plan is an important tool for GS and

anticipates that, in some cases, the appropriate post-injection monitoring strategy may end up being

different than initially projected and there may be a need to amend the post-injection site care and

site closure plan. EPA is requiring that upon the cessation of injection, the owner or operator submit

an amended post-injection site care and site closure plan or demonstrate to the Director that no

changes to the original post-injection site care and site closure plan are necessary (146.93(a)(3)).

EPA is not requiring formal periodic review and updates to the PISC and site closure plan

throughout the injection phase. EPA does not expect that changes to this plan would be implemented

until injection operations cease. EPA envisions that owners or operators would take into account

similar considerations that guide updates to other project plans, e.g., monitoring and operational data

and results of AoR reevaluations. EPA adds that, if any monitoring or other site data indicate a need

for amending the post-injection site care plan, the owner or operator is expected to amend the plan

accordingly. EPA is issuing guidance with recommended approaches for development and updating

of the GS project plans, including the post-injection site care and site closure plan. The guidance will

be available on EPA's web site at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

EPA adds that, in the final rule, it has revised the text at §146.93(a)(4) as follows: "At any time

during the life of the geologic sequestration project, the owner or operator may modify and resubmit

the post-injection site care and site closure plan for the Director’s approval within 30 days of such

change."

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24723

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

language; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Rule Provision: 146.93(e) 
Anadarko Petroleum Corporation (APC) Comments: (e) Once the Director has 

authorized site closure, the owner or operator must submit a site closure report 

within 90 days that must thereafter be retained at a location designated by 

the Director. AFTER COMPLETION OF ALL CLOSURE OPERATIONS. The report must 

include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the location 

of the injection well(S) relative to permanently surveyed benchmarks. The owner 

or operator must also submit a copy of the plat to the Regional Administrator of 

the appropriate EPA Regional Office; 

Rationale: Once the site closure report is submitted to the Director, the 

operator cease to bear responsibility for any further record retention. At this 

point, EPA becomes the steward of information for the project. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention

such as site closure reports. EPA believes that the requirements that the owner or operator retain for

ten years following site closure, records collected during the post-injection site care period at

§146.93(f) and §146.93(h) are appropriate for the post-injection and site closure period to ensure that

data are available to support non-endangerment demonstrations and to address any concerns that may

arise following site closure. This data will also support EPA's review of project data as part of the

adaptive rulemaking approach.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24938

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

language; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 146.92) 

Comment: EPA Proposal: (c) Notice of intent to plug. The owner or operator must notify 

the Director at least 60 days before plugging of a well. At this time, if any 

changes have been made to the original well plugging plan, the owner or operator 

must also provide the revised well plugging plan. At the discretion of the 

Director, a shorter notice period may be allowed. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24939

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

language; 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 146.92) 

Comment: Rule Provision: 146.92(d) 
EPA Proposal: (d) Plugging report. Within 60 days after plugging or at the time 

of the next semi-annual report (whichever occurs earlier) the owner or operator 

must submit a plugging report to the Director. If the semi-annual report is due 

less than 15 days after completion of plugging, then the report must be 

submitted within 60 days after plugging. The report must be certified as 

accurate by the owner or operator and by the person who performed the plugging 

operation (if other than the owner or operator.) 

GWPC Recommendations: (d) Plugging report. Within 60 days after plugging the 

owner or operator must submit a plugging report to the Director. The report 

must be certified as accurate by the owner or operator and by the person who 

performed the plugging operation (if other than the owner or operator.) 

Rationale: Simplification 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads,

"Within 60 days after plugging the owner or operator must submit a plugging report to the Director."

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24951

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

language; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: EPA Proposal: (e) Once the Director has authorized site closure, the owner or 

operator must submit a site closure report within 90 days that must thereafter 

be retained at a location designated by the Director. The report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in § 146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the 

location of the injection well relative to permanently surveyed benchmarks. The 

owner or operator must also submit a copy of the plat to the Regional 

Administrator of the appropriate EPA Regional Office; 

GWPC Recommendations: (e) Once the Director has authorized site closure, the 

owner or operator must submit a site closure report within 90 days after 

completion of all closure operations. The report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the location 

of the injection well(s) relative to permanently surveyed benchmarks. The owner 

or operator must also submit a copy of the plat to the Regional Administrator of 

the appropriate EPA Regional Office; 

Rationale: What is the retention period? Many other programs have a three year 

limit for retention of records. EPA is the steward of information at this point 

of the project, not the owner or operator. 
Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on

the deed to the facility property or other similar document examined during a title search that the

land has been used to sequester CO2 on the deed to the facility property at the time of site closure. 

Regarding record retention, EPA has clarified the recordkeeping requirements in the final GS rule,

which includes requirements that well plugging reports, as required at §146.92(d), post-injection site

care data, as required at §146.93(f), and site closure reports, as required at §146.93(h), must be kept

by the owner or operator for ten years after site closure. EPA believes that longer record retention

times for GS wells are appropriate and necessary for the post-injection and site closure period to

ensure that data are available to support non-endangerment demonstrations and to address any

concerns that may arise following site closure. This data will also support EPA's review of project

data as part of the adaptive rulemaking approach.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24952

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

language; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: EPA Proposal: (2) Documentation of appropriate notification and information to 

such State, local and tribal authorities as have authority over drilling 

activities to enable such State and local authorities to impose appropriate 

conditions on subsequent drilling activities that may penetrate the injection 

and confining zone(s); and 

(3) Records reflecting the nature, composition and volume of the carbon dioxide 

stream. 

GWPC Recommendations: No recommendation 

Rationale: Need for site-specific considerations and use of data 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on

the deed to the facility property or other similar document examined during a title search that the

land has been used to sequester CO2 on the deed to the facility property at the time of site closure.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24953

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

language; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Rule Provision: 146.93 

EPA Proposal: (f) Each owner or operator of a Class VI injection well must 

record a notation on the deed to the facility property or any other document 

that is normally examined during title search that will in perpetuity provide 

any potential purchaser of the property the following information: 

(1) The fact that land has been used to sequester carbon dioxide; 

(2) The name of the State agency, local authority, and/or tribe with which the 
survey plat was filed, as well as the address of the Regional Environmental 

Protection Agency Office to which it was submitted; and 

GWPC Recommendations: No recommendation 

Rationale: Need for site-specific considerations and use of data 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on

the deed to the facility property or other similar document examined during a title search that the

land has been used to sequester CO2 on the deed to the facility property at the time of site closure.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24954

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

language; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: EPA Proposal: (3) The volume of fluid injected, the injection zone or zones into 

which it was injected, and the period over which injection occurred. 

(g) The owner or operator must retain for three years following site closure, 

records collected during the post-injection site care period. The owner or 

operator must deliver the records to the Director at the conclusion of the 

retention period, and the records must thereafter be retained at a location 

designated by the Director for that purpose. 

GWPC Recommendations: No recommendation 

Rationale: Need for site-specific considerations and use of data 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on

the deed to the facility property or other similar document examined during a title search that the

land has been used to sequester CO2 on the deed to the facility property at the time of site closure. 

Comment Code: 4740 2.7.4 Electronic reporting (seeking comment) 

Individual Comments

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22645

Comment: o Page 43514. EPA asks for "comments on the requirements for monitoring" but it 

is not clear that there are any requirements articulated here. The USEPA should 

require that data on the areal extent of the CO2 plume and the pressure front as 

well as any other relevant data from MMV be reported to EPA on an annual / semiannual basis. USEPA still must come to some consensus on how these data will be 

collected, who will have access to them, ect. 
Response: EPA clarifies that the monitoring requirements for Class VI well owners or operators are

presented in the final rule at §146.90. EPA is retaining the requirement at §146.91(a) for semi-annual

reporting of monitoring and operational data, including data on monitoring and tracking the CO2

plume and pressure front. For additional information about monitoring requirements and reporting

requirements see the preamble to the final rule.

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with Class VI activities and provides recommended guidelines on

the types of data to be collected for tracking Class VI projects, reporting to EPA for compliance

tracking, and transfer of data to EPA's GS data system. The recordkeeping and reporting guidance

will be available on EPA's web site, at

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

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22646

Comment: o Page 43514 under "Monitoring CO2 Movement and Reservoir Pressure", USEPA 

states that the owner/operator must compare the results of monitoring to 

baseline data but the text of the proposed rule does not require that this 

information be shared with the USEPA or state permitting agency. Isn’t this 

critically important information on how GS is working at a site? Isn’t that 

information needed by USEPA to understand whether the Class VI rule is effective 

in protecting USDWs and the other goals of the SDWA? There should be a 

requirement that this data and comparison be shared with regulators. 

Response: EPA expects that CO2 plume and pressure front tracking data will be reviewed as part of

the AoR reevaluation and plan update process. The final GS rule, at §§146.84(c), 146.90(j), and

146.94(d), requires owners or operators to review and update the AoR and corrective action plan, the

testing and monitoring plan, and the emergency and remedial response plan throughout the life of

the project. Owners or operators must review each plan and identify necessary amendments to the

plan or demonstrate to the Director that no amendment is needed. These reviews must be performed

within one year of an AoR reevaluation, following any significant changes to the facility (e.g., the

addition of monitoring or injection wells), or when required by the Director. In no case can reviews

occur less often than once every five years. Furthermore, §146.90(b) requires that the owner or

operator continuously monitor injection pressure, rate and volume; the pressure on the annulus

between the tubing and the long string casing; and the annulus fluid volume added.

EPA believes that by requiring periodic reevaluations of the AoR, as required at §146.84(e), along

with any revisions to the required plans that may be required based on the AoR reevaluation or other

data collected during well operations, will promote an ongoing relationship between the permitting

authority and the owner or operator, including discussion of all monitoring results.

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22651

Comment: o Page 43517. USEPA asks for comments on electronic reporting. Yes, electronic 

reporting should be mandatory. USEPA also needs to find a way to ensure that 

electronic reports are eventually consolidated at a national level. Having the 
reports be submitted to a state but not having the reporting go any further will 

frustrate efforts to improve our knowledge about how CCS works in practice and 

it will frustrate efforts to cost effectively include GS in to the structure of 

a national climate policy. Page 43529. The USEPA should consider whether a 

requirement of being granted primacy for Class VI wells would be a requirement 

to share data collected at the state or Tribal area with the federal USEPA. EPA 

Response: EPA retains the requirement that owners or operators submit data electronically to an

EPA data system. EPA believes that it is prudent to provide assistance by developing a central

framework for the electronic system that will be used by States to gather and track owner or operator

data. This will enable owners or operators to submit data without having to wait for a State to

develop a system. It will also provide for standardized submissions across the country and enable

States to focus resources on reviewing and approving permit applications rather than building or

upgrading separate, independent databases for GS information. EPA believes that electronic

formatting is the most appropriate format for submitting Class VI project information to the Director,

and that many GS well owners or operators will have the capability to report electronically. In

addition to minimizing redundancy and streamlining reporting for GS projects, EPA intends to use

the data collected to support its evaluation associated with the adaptive process. 

EPA is developing guidance for states that describes the record keeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23788

Comment: EPA seeks comment on the requirement for electronic reporting in its proposed 

rule. EPA Notice 115, 

We recommend that EPA allow electronic reporting as an alternative to hardcopy 

submittals. The benefits are speed, efficiency, reduced cost and burden of 

paperwork, ease of document retrieval, public access, search and storage. 

Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director, and that, based on comments received on the proposed

rule, the majority of Class VI well owners or operators will have the capability to report

electronically, and requires this at §146.91(e). 

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Michael Mudd Letter ID: 0167

Commenter Organization: FutureGen Alliance (FGIA) Comment ID: 22474

Comment: To comply with a requirement for electronic record-keeping, new data storage 
tools will be required to deal with the diverse nature of information that will 

be generated during the course of a CCS project. 

Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director, and based on comments received on the proposed rule,

the majority of Class VI GS well owners or operators will have the capability to report

electronically, and requires this at §146.91(e).

EPA believes that it is prudent to provide assistance by developing a central framework for the

electronic system that will be used by States to gather and track owner or operator data. This will

enable owners or operators to submit data without having to wait for a State to develop a system. It

will also provide for standardized submissions across the country and enable States to focus State

resources on reviewing and approving permit applications rather than building or upgrading separate,

independent databases for GS information. EPA believes that electronic formatting is the most

appropriate format for submitting Class VI project information to the Director, and that many GS

well owners or operators will have the capability to report electronically.

EPA is developing guidance for states that describes the record keeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23366

Comment: Permit Application and Reporting Requirements -- Pg. 39 

APPA believes that electronic reporting should not be absolute but should 

instead permit the Director to allow other methods of reporting when he deems 

such methods more appropriate. In addition, APPA believes that annual 

Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director, and based on comments received on the proposed rule,

the majority of Class VI GS well owners or operators will have the capability to report

electronically, and requires this at §146.91(e). 

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23417

Comment: Permit Application and Reporting Requirements 

The EPA asks for comments about electronic reporting. Any requirement contained 

in the Final Rule for electronic reporting should not be absolute but should 
instead allow the Director to allow other methods of reporting when he deems 

such methods more appropriate. APPA imagines that by the time CCS is widely 

commercially viable, electronic filing (or whatever society considers 

"electronic filing of data" will be at that future date) will be the least of 

our cost or operational concerns. APPA would suggests that early projects, say 

in the first five years, have some modest leniency for ways to file effectively 

and responsibly without the presumption of real time data on every imaginable 

data point. We also suggest that the EPA have some reasonable test for response 

Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director, and based on comments received on the proposed rule,

the majority of Class VI well owners or operators will have the capability to report electronically,

and requires this at §146.91(e).

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, 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: 24253

Comment: Rule Provisions: 146.91(c) 

EPA Preamble Question: 36. EPA seeks comment on the requirement for electronic 

reporting in its proposed rule. EPA Notice 43518. 

API Response: API strongly supports the concept of electronic reporting. 

Industry’s objections to prior proposals for electronic reporting have been with 

the scope and breadth of information (incremental over written reports) that the 

Agency has previously proposed. Electronic reporting equivalent to existing 

written reports would be supported by API. Until these concerns related to 

electronic reporting are resolved, such reporting may be encouraged but should 

not be required. 

Response: EPA agrees and believes that electronic formatting is the most appropriate format for

submitting Class VI project information to the Director, and requires this at §146.91(e). Based on

comments received on the proposed rule, the majority of Class VI well owners or operators will have

the capability to report electronically.

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23502

Comment: Reporting - USWAG agrees that electronic reporting should be an option available 
to all states for data exchange related to Class VI wells, but believes that the 

Director should have the discretion to allow other modes of reporting. Id. at 

43517-18. We appreciate the important steps EPA has taken, including the 

awarding of grants, to ensure that all states will have the capability to 

exchange data electronically. Id. USWAG also realizes the benefits of electronic 

reporting, particularly in terms of facilitating the application process and 

streamlining review of CO2 GS projects. However, while it is likely that all 

states will eventually have the general capability to report electronically, 

some may not have that capacity yet. Additionally, it is foreseeable that 

extraordinary circumstances may arise that would preclude access to or limit 

availability of electronic resources. Accordingly, any requirement contained in 

the Final Rule for electronic reporting should not be absolute but should 

instead allow the Director to approve other methods of reporting when he deems 

such methods more appropriate. 

Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director, and based on comments received on the proposed rule,

the majority of Class VI well owners or operators will have the capability to report electronically,

and requires this at §146.91(e).

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, 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: 23703

Comment: EPA Request for Comment: EPA seeks comment on the requirement for electronic 

reporting in its proposed rule. EPA Notice 43518. 

AWWA Response: AWWA agrees with the electronic reporting requirements include as 

part of the proposed regulation. Electronic reporting allows for easier tracking 

of the operating data to observe any trends that might indicate potential 

contamination of a USDW. EPA should consider the infrastructure that will be 

required to collect information prior to publishing the first report and develop 

a model reporting plan for owner/operators to use when submitting data to state 

agencies. 

Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director, and based on comments received on the proposed rule,

the majority of Class VI well owners or operators will have the capability to report electronically,

and requires this at §146.91(e). 

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.
Commenter Name: Bradley J. Field Letter ID: 0186

Commenter Organization: New York State Dept. of Environmental Conservation

Div. of Mineral Resources

Comment ID:

25209

Comment: KK. EPA seeks comment on the requirement for electronic reporting in today’s 

proposed rule. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with electronic submittal in principle as 

long as there is sufficient flexibility to allow states to utilize existing or 

preferred state data processing systems or software. At this time, electronic 

reporting should be an option but not a requirement. 

Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director, and based on comments received on the proposed rule,

the majority of Class VI well owners or operators will have the capability to report electronically,

and requires this at §146.91(e). 

Acknowledging that some States may have to develop electronic data systems to receive electronic

information from the owner or operator, and that many States which already have electronic data

systems will have to make changes to accommodate a new class of UIC well (Class VI), EPA

believes that it is prudent to provide assistance by developing a central framework for the electronic

system that will be used by States to gather and track owner or operator data. This will enable

owners or operators to submit data without having to wait for a State to develop a system. It will also

provide for standardized submissions across the country and enable States to focus State resources on

reviewing and approving permit applications rather than building or upgrading separate, independent

databases for GS information.

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24489

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

language; 4720 2.7.2 Operational recordkeeping and reporting 

Comment: Rule Provision: 146.91(b) & (c) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment and the final rule retains the text as proposed. See the

final rule and preamble for further discussion on EPA's final approach to reporting and

recordkeeping.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190
Commenter Organization: Carbon Sequestration Council Comment ID: 24545

Comment: Rule Provisions or Federal Register Cite: 146.91(c) 

EPA Preamble Question: 36. EPA seeks comment on the requirement for electronic 

reporting in its proposed rule. EPA Notice 43518. 

CSC Response: Industry’s objections to prior proposals for electronic reporting 

have been with the scope and breadth of information (incremental over written 

reports) that the Agency has previously proposed. Electronic reporting 

equivalent to existing written reports would be acceptable to CSC. Until these 

concerns related to electronic reporting are resolved, such reporting may be 

encouraged but should not be required. 

Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director, and based on comments received on the proposed rule,

the majority of Class VI well owners or operators will have the capability to report electronically,

and requires this at §146.91(e).

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, 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: 24606

Comment: Rule Provisions: 146.91(c) 

EPA Rule Issue: 36. EPA seeks comment on the requirement for electronic 

reporting in its proposed rule. EPA Notice 43518. 

Anadarko Petroleum Corporation (APC) Response: APC strongly supports the concept 

of electronic reporting. Industry’s objections to prior proposals for electronic 

reporting have been with the scope and breadth of information (incremental over 

written reports) that the Agency has previously proposed. Electronic reporting 

equivalent to existing written reports would be supported by APC. Until these 

concerns related to electronic reporting are resolved, such reporting may be 

encouraged but should not be required. 

Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director and requires this at §146.91(e). Based on comments

received on the proposed rule, the majority of Class VI well owners or operators will have the

capability to report electronically. 

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's data system. The recordkeeping and reporting guidance will be available on

EPA's web site, 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: 22738

Comment: EPA seeks comment on the requirement for electronic reporting in its proposed 

rule. EPA Notice 115. 

We recommend that EPA allow electronic reporting as an alternative to hardcopy 

submittals. The benefits are speed, efficiency, reduced cost and burden of 

paperwork, ease of document retrieval, public access, search and storage. 

Response: EPA agrees and believes that electronic formatting is the most appropriate format for

submitting Class VI project information to the Director, and based on comments received on the

proposed rule, the majority of Class VI well owners or operators will have the capability to report

electronically, and requires this at §146.91(e). 

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, 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: 23259

Comment: 36. EPA seeks comment on the requirement for electronic reporting in its 

proposed rule. EPA Notice 43518. 

Electronic reporting should not be required. State systems may already be in 

place to collect data but may not be compatible with sending or receiving 

systems. 

Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director, and based on comments received on the proposed rule,

the majority of Class VI well owners or operators will have the capability to report electronically,

and requires this at §146.91(e).

Acknowledging that some States may have to develop electronic data systems to receive electronic

information from the owner or operator, and that many States which already have electronic data

systems will have to make changes to accommodate a new class of UIC well (Class VI), EPA

believes that it is prudent to provide assistance by developing a central framework for the electronic

system that will be used by States to gather and track owner or operator data. This will enable

owners or operators to submit data without having to wait for a State to develop a system. It will also

provide for standardized submissions across the country and enable States to focus State resources on

reviewing and approving permit applications rather than building or upgrading separate, independent

databases for GS information.

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, 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: 23304

Comment: 146.91(c) Electronic reporting should not be required. State systems may 

already be in place to collect data but may not be compatible with sending or 

receiving systems. 

Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director, and based on comments received on the proposed rule,

the majority of Class VI well owners or operators will have the capability to report electronically,

and requires this at §146.91(e). 

Acknowledging that some States may have to develop electronic data systems to receive electronic

information from the owner or operator, and that many States which already have electronic data

systems will have to make changes to accommodate a new class of UIC well (Class VI), EPA

believes that it is prudent to provide assistance by developing a central framework for the electronic

system that will be used by States to gather and track owner or operator data. This will enable

owners or operators to submit data without having to wait for a State to develop a system. It will also

provide for standardized submissions across the country and enable States to focus State resources on

reviewing and approving permit applications rather than building or upgrading separate, independent

databases for GS information.

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Walter L. Baker Letter ID: 0253

Commenter Organization: Utah Division of Water Quality Comment ID: 22353

Other EPA Comment Codes and Descriptions: 4700 2.7 Proposed Recordkeeping and Reporting

Requirements (40 CFR 146.91) 

Comment: ELECTRONIC REPORTING 

We agree with EPA that electronic reporting will reduce reporting burden and 

will facilitate tracking of CCGS projects. However, the "electronic format 

acceptable to the Director" should not constitute a financial or resource burden 

to the owner / operator or to the regulating agency required to report to EPA on 

UIC program activity. Until that time when the regulating agency has developed 

a data flow to the National UIC Database, we strongly urge EPA to develop an 

online service for submitting CCGS information such as is currently in place for 

submitting Program Activity Measures (PAMs) and UIC inventory. 

Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director, and based on comments received on the proposed rule,

the majority of Class VI well owners or operators will have the capability to report electronically,

and requires this at §146.91(e). 

Acknowledging that some States may have to develop electronic data systems to receive electronic
information from the owner or operator, and that many States which already have electronic data

systems will have to make changes to accommodate a new class of UIC well (Class VI), EPA

believes that it is prudent to provide assistance by developing a central framework for the electronic

system that will be used by States to gather and track owner or operator data. This will enable

owners or operators to submit data without having to wait for a State to develop a system. It will also

provide for standardized submissions across the country and enable States to focus State resources on

reviewing and approving permit applications rather than building or upgrading separate, independent

databases for GS information.

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24934

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

language; 4720 2.7.2 Operational recordkeeping and reporting 

Comment: EPA Proposal: (b) Report, within 30 days the results of: 

(1) Periodic tests of mechanical integrity; 

(2) Any other test of the injection well conducted by the permittee if required 

by the Director; and 

(3) Any well workover. 

(c) Owners or operators must submit reports in an electronic format acceptable 

to the Director. At the discretion of the Director, other formats may be 

accepted. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the comment. Please see the final rule and the discussion of reporting

preamble for additional information on EPA's final rulemaking approach.

EPA believes that electronic formatting is the most appropriate format for submitting Class VI

project information to the Director, and that many GS well owners or operators will have the

capability to report electronically.

Letter ID: 0263

Commenter Organization: Interstate Oil & Gas Compact Commission Comment ID: 22823

Comment: III A. 7 Proposed Recordkeeping andReporting Requirements 

MM. EPA seeks comment on the requirement for electronic reporting in today's 

proposed rule. 
IOGCC Response: The IOGCC agrees with electronic submittal in principle as long as 

there is sufficient flexibility to allow states to utilize existing or preferred 

state data processing systems or software. Electronic reporting should be an 

option but not a requirement. 

Response: EPA believes that electronic formatting is the most appropriate format for submitting

Class VI project information to the Director, and based on comments received on the proposed rule,

the majority of Class VI well owners or operators will have the capability to report electronically,

and requires this at §146.91(e).

Acknowledging that some States may have to develop electronic data systems to receive electronic

information from the owner or operator, and that many States which already have electronic data

systems will have to make changes to accommodate a new class of UIC well (Class VI), EPA

believes that it is prudent to provide assistance by developing a central framework for the electronic

system that will be used by States to gather and track owner or operator data. This will enable

owners or operators to submit data without having to wait for a State to develop a system. It will also

provide for standardized submissions across the country and enable States to focus State resources on

reviewing and approving permit applications rather than building or upgrading separate, independent

databases for GS information.

EPA is developing guidance for states that describes the recordkeeping, reporting, and additional

data management needs associated with GS activities and provides recommended guidelines on the

types of data to be collected for tracking GS projects, reporting to EPA for compliance tracking, and

transfer of data to EPA's GS data system. The recordkeeping and reporting guidance will be

available on EPA's web site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Comment Code: 4750 2.7.5 Comments on the merit of annual reports (seeking comment) 

Individual Comments

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23789

Comment: Although EPA has not included a requirement for this report in its proposal, EPA 

seeks comment regarding the necessity for such an annual report. EPA Notice 115. 

While reports on status are worthwhile, activity and changes in status are not 

going to be significant on an annual basis. Following a report after the first 

year of operation to ensure that requirements for later reporting are being met, 

once every 10 years coincident with the periods for AoR review should be 

adequate. 

Response: The final GS regulation retains the reporting requirements as proposed, which does not

include a requirement for an annual report. Instead, EPA believes that periodic reevaluation of the

AoR, as required at §146.84(e), along with any revisions to the required plans that may be necessary

based on the AoR reevaluation, will promote an ongoing relationship between the permitting

authority and the owner or operator. The final GS rule, at §§146.84(c), 146.90(j), and 146.94(d),

requires owners or operators to review and update the AoR and corrective action plan, the testing
and monitoring plan, and the emergency and remedial response plan throughout the life of the

project. Owners or operators must review each plan and identify necessary amendments to the plan

or demonstrate to the Director that no amendment is needed. These reviews must be performed

within one year of an AoR reevaluation, following any significant changes to the facility (e.g., the

addition of monitoring or injection wells), or when required by the Director. In no case can reviews

occur less often than once every five years. For additional information, please see the final rule and

the preamble for a discussion of EPA's final approach to recordkeeping and reporting.

While the Agency recognizes some concerns expressed by commenters about the burden associated

with an annual report, the Agency's decision to retain the semi-annual reporting requirement at

§146.91(a) is because the semi-annual report in conjunction with the continued dialogue associated

with AoR reevaluations and periodic updates to the plans is a preferred approach to an annual report.

EPA encourages and expects owners and operators to share monitoring and operating data with the

public voluntarily (e.g., through the Internet), however. Providing the public with information

throughout the Class VI project will help clear up and avoid public misperceptions about the nature

and safety of GS.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24254

Comment: Rule Provisions: 73 FR 43518 

EPA Preamble Question: 37. In addition to the above recordkeeping and reporting 

requirements, EPA considered a requirement for owners or operators of GS sites 

to provide an annual report during the lifetime of the project, including the 

post-injection period, regarding the GS operation. Although EPA has not included 

a requirement for this report in its proposal, EPA seeks comment regarding the 

necessity for such an annual report. EPA Notice 43518. 

API Response: An Annual report is not necessary given the other reporting 

requirements in the Rule. Alternatively, if this report was to replace the other 

reporting requirements, there would be value to the proposal. 

Response: The final GS regulation retains the reporting requirements as proposed, which does not

include a requirement for an annual report. Instead, EPA believes that periodic reevaluation of the

AoR, as required at §146.84(e), along with any revisions to the required plans that may be necessary

based on the AoR reevaluation, will promote an ongoing relationship between the permitting

authority and the owner or operator. The final GS rule, at §§146.84(c), 146.90(j), and 146.94(d),

requires owners or operators to review and update the AoR and corrective action plan, the testing

and monitoring plan, and the emergency and remedial response plan throughout the life of the

project. Owners or operators must review each plan and identify necessary amendments to the plan

or demonstrate to the Director that no amendment is needed. These reviews must be performed

within one year of an AoR reevaluation, following any significant changes to the facility (e.g., the

addition of monitoring or injection wells), or when required by the Director. In no case can reviews

occur less often than once every five years. See the final rule and preamble for further discussion on

EPA's final approach to reporting and recordkeeping.

While the Agency recognizes some concerns expressed by commenters about the burden associated

with an annual report, the Agency's decision to retain the semi-annual reporting requirement at

§146.91(a) is because the semi-annual report in conjunction with the continued dialogue associated
with AoR reevaluations and periodic updates to the plans is a preferred approach to an annual report.

EPA encourages and expects owners and operators to share monitoring and operating data with the

public voluntarily, however (e.g., through the Internet). Providing the public with information

throughout the GS project will help clear up and avoid public misperceptions about the nature and

safety of GS.

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23503

Comment: With respect to the Proposal's suggestion of an annual reporting requirement for 

CO2 GS projects, USWAG appreciates the importance of the information EPA seeks 

to gather but believes that annual reporting will not always be the best way to 

collect this information over the lifetime of the project. Id. at 43518. The 

Final Rule will require some form of periodic reevaluation of the AoR throughout 

the life of the project; much of the information sought through the proposed 

annual reporting requirement would be gathered and submitted to EPA through the 

AoR reevaluation process. Gathering this information through the AoR 

reevaluations alone, rather than imposing an unnecessary and duplicative annual 

reporting requirement, will provide a more cost-effective and manageable method 

of information exchange for regulators and Owners or Operators alike. 

Response: The final GS regulation retains the reporting requirements as proposed, which does not

include a requirement for an annual report. Instead, EPA believes that periodic reevaluation of the

AoR, as required at §146.84(e), along with any revisions to the required plans that may be necessary

based on the AoR reevaluation, will promote an ongoing relationship between the permitting

authority and the owner or operator. The final GS rule, at §§146.84(c), 146.90(j), and 146.94(d),

requires owners or operators to review and update the AoR and corrective action plan, the testing

and monitoring plan, and the emergency and remedial response plan throughout the life of the

project. Owners or operators must review each plan and identify necessary amendments to the plan

or demonstrate to the Director that no amendment is needed. These reviews must be performed

within one year of an AoR reevaluation, following any significant changes to the facility (e.g., the

addition of monitoring or injection wells), or when required by the Director. In no case can reviews

occur less often than once every five years. For additional information, please see the final rule and

the preamble for a discussion of EPA's final approach to recordkeeping and reporting.

EPA also encourages and expects owners and operators to share monitoring and operating data with

the public voluntarily (e.g., through the Internet), however. Providing the public with information

throughout the GS project will help clear up and avoid public misperceptions about the nature and

safety of GS.

The Agency plans to, every six years, evaluate the information and determine if modifications to the

requirements are appropriate or necessary to ensure protection of USDWs from endangerment.

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23847

Comment: EPA also seeks comment on whether owners or operators of GS sites should be 

required to provide an annual report on GS operation during the lifetime of the 

project, including the post-injection period. Such a report is not necessary in 
light of the other proposed semi-annual reporting obligations. 

Response: The final GS regulation retains the reporting requirements as proposed, which does not

include a requirement for an annual report. Instead, EPA believes that periodic reevaluation of the

AoR, as required at §146.84(e), along with any revisions to the required plans that may be necessary

based on the AoR reevaluation, will promote an ongoing relationship between the permitting

authority and the owner or operator. The final GS rule, at §§146.84(c), 146.90(j), and 146.94(d),

requires owners or operators to review and update the AoR and corrective action plan, the testing

and monitoring plan, and the emergency and remedial response plan throughout the life of the

project. Owners or operators must review each plan and identify necessary amendments to the plan

or demonstrate to the Director that no amendment is needed. These reviews must be performed

within one year of an AoR reevaluation, following any significant changes to the facility (e.g., the

addition of monitoring or injection wells), or when required by the Director. In no case can reviews

occur less often than once every five years. For additional information, please see the final rule and

the preamble for a discussion of EPA's final approach to recordkeeping and reporting.

While the Agency recognizes some concerns expressed by commenters about the burden associated

with an annual report, the Agency's decision to retain the semi-annual reporting requirement at

§146.91(a) is because the semi-annual report in conjunction with the continued dialogue associated

with AoR reevaluations and periodic updates to the plans is a preferred approach to an annual report.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23704

Comment: EPA Request for Comment: In addition to the above recordkeeping and reporting 

requirements, EPA considered a requirement for owners or operators of GS sites 

to provide an annual report during the lifetime of the project, including the 

post-injection period, regarding the GS operation. Although EPA has not included 

a requirement for this report in its proposal, EPA seeks comment regarding the 

necessity for such an annual report. EPA Notice 43518. 

AWWA Response: AWWA recommends that an annual reporting requirement be included 

n the proposed regulation. This report should summarize the operation of the 

system including standard operating criteria, information on well operation, 

details of plume movement, and any details on major changes in well operation. 

It should be similar to the Consumer Confidence Reports (CCR) that drinking 

water utilities must develop and it should be mailed or emailed to all relevant 

stakeholders. EPA should develop requirements for the report similar to those 

required for the CCR because the annual report should be developed by someone 

one of the team members involved in the operation of the geologic sequestration 

project. 

Response: Individual Response: The final GS regulation retains the semi-annual reporting

requirements as proposed and does not include a requirement for an annual report. Instead, EPA

believes that periodic reevaluation of the AoR, as required at §146.84(e), along with any revisions to

the required plans that may be necessary based on the AoR reevaluation, will promote an ongoing

relationship between the permitting authority and the owner or operator. The final GS rule, at

§§146.84(c), 146.90(j), and 146.94(d), requires owners or operators to review and update the AoR

and corrective action plan, the testing and monitoring plan, and the emergency and remedial

response plan throughout the life of the project. Owners or operators must review each plan and
identify necessary amendments to the plan or demonstrate to the Director that no amendment is

needed. These reviews must be performed within one year of an AoR reevaluation, following any

significant changes to the facility (e.g., the addition of monitoring or injection wells), or when

required by the Director. In no case can reviews occur less often than once every five years.

EPA also encourages and expects owners and operators to share monitoring and operating data with

the public voluntarily (e.g., through the Internet. Providing the public with information throughout

the GS project will help clear up and avoid public misperceptions about the nature and safety of GS.

For additional information, please see the final rule and the preamble for a discussion of EPA's final

approach to recordkeeping and reporting.

Commenter Name: Bradley J. Field Letter ID: 0186

Commenter Organization: New York State Dept. of Environmental Conservation

Div. of Mineral Resources

Comment ID:

25210

Comment: LL. Although EPA has not included a requirement for this report in today’s 

proposal, EPA seeks comment regarding the necessity for such an annual report. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with the concept and sees the merits of 

requiring an annual report that provides a narrative analysis of GS operations 

in addition to requiring semi-annual reporting of data. 

Response: The final GS regulation retains the reporting requirements as outlined in the proposed

rule and does not include a requirement for an annual report. EPA believes that periodic reevaluation

of the AoR, as required at §146.84(e), along with any revisions to the required plans that may be

necessary based on the AoR reevaluation or other data collected during well operations, will promote

an ongoing relationship between the permitting authority and the owner or operator. The final GS

rule, at §§146.84(c), 146.90(j), and 146.94(d), requires owners or operators to review and update the

AoR and corrective action plan, the testing and monitoring plan, and the emergency and remedial

response plan throughout the life of the project. Owners or operators must review each plan and

identify necessary amendments to the plan or demonstrate to the Director that no amendment is

needed. These reviews must be performed within one year of an AoR reevaluation, following any

significant changes to the facility (e.g., the addition of monitoring or injection wells), or when

required by the Director. In no case can reviews occur less often than once every five years. For

additional information, please see the final rule and the preamble for a discussion of EPA's final

approach to recordkeeping and reporting.

The semi-annual reporting required at §146.91(a) includes both operational data and data required as

part of the testing and monitoring plan, satisfying many of the concerns expressed commenters who

supported the annual report.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24546

Comment: Rule Provisions or Federal Register Cite: 73 FR 43518 

EPA Preamble Question: 37. In addition to the above recordkeeping and reporting 

requirements, EPA considered a requirement for owners or operators of GS sites 

to provide an annual report during the lifetime of the project, including the 

post-injection period, regarding the GS operation. Although EPA has not included 

a requirement for this report in its proposal, EPA seeks comment regarding the 
necessity for such an annual report. EPA Notice 43518. 

CSC Response: An additional annual report is not necessary given the other 

reporting requirements in the Rule. Alternatively, if this report was to replace 

the other reporting requirements, there would be value to the proposal. 

Response: The final GS regulation retains the reporting requirements as proposed and does not

include a requirement for an annual report. Instead, EPA believes that periodic reevaluation of the

AoR, as required at §146.84(e), along with any revisions to the required plans that may be necessary

based on the AoR reevaluation, will promote an ongoing relationship between the permitting

authority and the owner or operator. The final GS rule, at §§146.84(c), 146.90(j), and 146.94(d),

requires owners or operators to review and update the AoR and corrective action plan, the testing

and monitoring plan, and the emergency and remedial response plan throughout the life of the

project. Owners or operators must review each plan and identify necessary amendments to the plan

or demonstrate to the Director that no amendment is needed. These reviews must be performed

within one year of an AoR reevaluation, following any significant changes to the facility (e.g., the

addition of monitoring or injection wells), or when required by the Director. In no case can reviews

occur less often than once every five years. For additional information, please see the final rule and

the preamble for a discussion of EPA's final approach to recordkeeping and reporting.

While the Agency recognizes some concerns expressed by commenters about the burden associated

with an annual report, the Agency's decision to retain the semi-annual reporting requirement at

§146.91(a) is because the semi-annual report in conjunction with the continued dialogue associated

with AoR reevaluations and periodic updates to the plans is a preferred approach to an annual report.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24607

Comment: Rule Provisions: 73 FR 43518 

EPA Rule Issue: 37. In addition to the above recordkeeping and reporting 

requirements, EPA considered a requirement for owners or operators of GS sites 

to provide an annual report during the lifetime of the project, including the 

post-injection period, regarding the GS operation. Although EPA has not included 

a requirement for this report in its proposal, EPA seeks comment regarding the 

necessity for such an annual report. EPA Notice 43518. 

Anadarko Petroleum Corporation (APC) Response: An Annual report is not necessary 

given the other reporting requirements in the Rule. The addition of this report 

would not produce any new pertinent information to the regulating agency; and, 

therefore, only increases their administrative burden on the agency and requires 

the generation of needless documents. In keeping with the provisions of the 

Paperwork Reduction Act, EPA should not require an annual report. Alternatively, 

if this report was to replace the other reporting requirements, there would be 

value to the proposal. 

Response: The final GS regulation retains the reporting requirements as proposed and does not

include a requirement for an annual report. Instead, EPA believes that periodic reevaluation of the

AoR, as required at §146.84(e), along with any revisions to the required plans that may be necessary

based on the AoR reevaluation, will promote an ongoing relationship between the permitting

authority and the owner or operator. The final GS rule, at §§146.84(c), 146.90(j), and 146.94(d),
requires owners or operators to review and update the AoR and corrective action plan, the testing

and monitoring plan, and the emergency and remedial response plan throughout the life of the

project. Owners or operators must review each plan and identify necessary amendments to the plan

or demonstrate to the Director that no amendment is needed. These reviews must be performed

within one year of an AoR reevaluation, following any significant changes to the facility (e.g., the

addition of monitoring or injection wells), or when required by the Director. In no case can reviews

occur less often than once every five years. For additional information, please see the final rule and

the preamble for a discussion of EPA's final approach to recordkeeping and reporting.

While the Agency recognizes some concerns expressed by commenters about the burden associated

with an annual report, the Agency's decision to retain the semi-annual reporting requirement at

§146.91(a) is because the semi-annual report in conjunction with the continued dialogue associated

with AoR reevaluations and periodic updates to the plans is a preferred approach to an annual report.

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22739

Comment: Although EPA has not included a requirement for this report in its proposal, EPA 

seeks comment regarding the necessity for such an annual report. EPA Notice 115. 

While reports on status are worthwhile, activity and changes in status are not 

going to be significant on an annual basis. Following a report after the first 

year of operation to ensure that requirements for later reporting are being met, 

once every 10 years coincident with the periods for AoR review should be 

adequate. 

Response: EPA is requiring semi-annual reporting in addition to periodic reevaluations of required

Class VI projects plans. The final GS rule, at §§146.84(c), 146.90(j), and 146.94(d), requires owners

or operators to review and update the AoR and corrective action plan, the testing and monitoring

plan, and the emergency and remedial response plan throughout the life of the project. Owners or

operators must review each plan and identify necessary amendments to the plan or demonstrate to

the Director that no amendment is needed. These reviews must be performed within one year of an

AoR reevaluation, following any significant changes to the facility (e.g., the addition of monitoring

or injection wells), or when required by the Director. In no case can reviews occur less often than

once every five years. EPA adds that it has modified the AoR reevaluation frequency in the final

rule, from 10 years to 5 years. For additional information, please see the final rule and the preamble

for a discussion of EPA's final approach to AoR and corrective action.

Commenter Name: Neeraj Gupta Letter ID: 0229

Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21864

Comment: Page 115, Annual Report- Another annual report is mentioned. The overall 

reporting requirements are confusing. We would recommend monthly or quarterly 

operating reports and a single annual report. 

Response: The final rule remains unchanged from the proposal and requires semi-annual reporting

of monthly average, maximum and minimum values for injection pressure, flow rate and volume,

annular pressure, and monthly annulus fluid volume added at §146.91(a). EPA believes that monthly

reporting of routine operational data and monitoring results would provide no additional protection of

USDWs from endangerment. EPA adds, at §146.91(c), that it has included in the final rule a
requirement that operators must report within 24 hours of any event that may endanger USDWs.

EPA notes that states seeking primacy for Class VI wells are free to require more frequent reporting.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23260

Comment: 37. In addition to the above recordkeeping and reporting requirements, EPA 

considered a requirement for owners or operators of GS sites to provide an 

annual report during the lifetime of the project, including the post-injection 

period, regarding the GS operation. Although EPA has not included a requirement 

for this report in its proposal, EPA seeks comment regarding the necessity for 

such an annual report. EPA Notice 43518. 

During the active injection phase of a project, reports and frequencies similar 

to those which exist in other UIC classes should be sufficient. Once active 

injection ceases, an annual report may be appropriate. 

Response: EPA clarifies that reporting requirements for existing injection wells vary by well class.

The Agency believes semi-annual reporting is appropriate for Class VI GS wells during the

operational phase of the project. EPA believes that the potentially large injection volumes and

injection pressures associated with GS warrant more frequent reporting than for other well classes.

EPA adds, at §146.93(a)(2)(iv), that reporting during the post-injection site care timeframe would be

at the frequency described in the approved post-injection site care and site closure plan. For

additional information, please see the final rule and the preamble for a discussion of EPA's final

approach to recordkeeping and reporting.

Commenter Name: Kristin Henry Letter ID: 0242

Commenter Organization: Sierra Environmental Law Program, Sierra Club Comment ID: 23329

Other EPA Comment Codes and Descriptions: 3530 2.2.3.1 AoR reevaluation frequency (seeking

comment) 

Comment: An update or redefinition of the AOR at a minimum fixed frequency of ten years 

is not sufficient. The operator should be required to submit an annual 

assessment under stating whether they deem a revision of the AOR necessary, 

explaining their reasoning based on site-specific operational and other data. 

The Director should examine and approve or reject this submission, requiring a 

revision of the AOR as needed. The same updating procedure should apply to all 

other plans: monitoring, closure, etc. We believe that this arrangement 

encourages honest and truthful reporting of data and site performance without 

placing excessive burdens on redefining the AOR if such revision is not needed. 

It also leaves a clear accountability trail for both operator and Director in 

case of disputes. 

Response: EPA agrees with commenters that reevaluations of the AoR every ten years may not be

sufficient to appropriately model plume and pressure front movement, establish conditions for

corrective action, and ensure protection of USDWs from endangerment. For these reasons, the

Agency changed the minimum frequency for the AoR reevaluation at §146.84(e) from 10 years to at

least every 5 years in the final GS rule. EPA believes that this revised frequency addresses

commenters' concerns about the inherent uncertainties in modeling CO2 movement, the emerging

nature of GS technology, risk-based targeting of monitoring activities, and the unique nature of CO2
GS. In addition, the Director has discretion to require more frequent AoR reevaluation if he or she

has reason to believe, based on site-specific information, that a five-year reevaluation schedule is not

sufficiently protective of USDWs.

EPA also agrees that periodic reviews of the other plans based on the AoR reevaluation is

appropriate. The final GS rule includes provisions that owners or operators review and update the

AoR and corrective action plan, the testing and monitoring plan, and the emergency and remedial

response plan throughout the life of the project, as specified in §146.84(c), §146.90(j), and

§146.94(d). Owners or operators must review each plan and identify necessary amendments to the

plan or demonstrate to the Director that no amendment is needed. These reviews must be performed

within one year of an AoR reevaluation, following any significant changes to the facility (e.g., the

addition of monitoring or injection wells), or when required by the Director.

EPA agrees that the AoR reevaluations offer a good opportunity to promote a dialogue between the

owner or operator and the permitting authority. The final GS rule, at §§146.84(c), 146.90(j), and

146.94(d), requires owners or operators to review and update the AoR and corrective action plan, the

testing and monitoring plan, and the emergency and remedial response plan throughout the life of

the project. Owners or operators must review each plan and identify necessary amendments to the

plan or demonstrate to the Director that no amendment is needed. These reviews must be performed

within one year of an AoR reevaluation, following any significant changes to the facility (e.g., the

addition of monitoring or injection wells), or when required by the Director. In no case can reviews

occur less often than once every five years. For additional information, please see the final rule and

the preamble for a discussion of EPA's final approach to recordkeeping and reporting.

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22309

Other EPA Comment Codes and Descriptions: 3700 2.2.5 Comments on the requirement for an

AoR and corrective action plan 

Comment: The rule should require updating when warranted of all of the proposed "plans" 

and should require an annual report that summarizes whether not updates have 

been warranted, and whether or not updates have been undertaken 

We applaud EPA for proposing to require the creation, use, and updating of 

various "plans" during the operating life of a facility. By creating such an 

iterative process, and basing it on monitoring and other operational data that 

become available through time, EPA can assure that facilities are managed in a 

way that adapts to changing circumstances. This approach also has the potential 

to enable what the Preamble calls an "ongoing dialogue" between operators and 

regulators, especially if the rule is enhanced by the annual reporting 

requirement suggested below for inclusion in §146.91. 

Perhaps inadvertently, the proposed rule does not explicitly require updating of 

several of the required plans. In most but not all cases, there is a rather 

ambiguous requirement to "maintain" a given plan. Explicit requirements to make 

updates as warranted appear to be missing from provisions relating to: 

Response: EPA acknowledges the commenters' support of the AoR and corrective action plan, and

retains the requirement in the final regulation §146.84(b). EPA believes that the iterative process by

which monitoring and operational data are used to validate the original AoR calculation, along with
the combined knowledge and ongoing dialogue between the owner or operator and the Director on

the local geologic conditions will be critical in developing and implementing plans that protect

USDWs from endangerment.

EPA adds that the final rule includes provisions that owners or operators review and update the AoR

and corrective action plan, the testing and monitoring plan, and the emergency and remedial

response plan throughout the life of the project, as specified in §146.84(c), §146.90(j), and

§146.94(d). Owners or operators must review each plan and identify necessary amendments to the

plan or demonstrate to the Director that no amendment is needed. These reviews must be performed

within one year of an AoR reevaluation, following any significant changes to the facility (e.g., the

addition of monitoring or injection wells), or when required by the Director.

EPA clarifies that the final rule does not require an annual report.

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22314

Comment: An additional annual reporting requirement will enhance the ability of both 

Director and operators to keep track of which plans require updating and whether 

or not plans that ought to be updated have in fact been revised. Such a shared 

understanding is essential if there is to be the "ongoing dialogue" between 

regulators and operators that EPA anticipates. Our Environmental NGO Group 

considered supporting the inclusion of an annual report as described in the 

preamble at 73 Fed. Reg. 43518, but concluded that the benefits of that 

particular report would be outweighed by the burden. The annual report we are 

suggesting here, however, would be much simpler. We believe that EPA should 

require a report, signed by the appropriate company official, that: 

• lists all of the required plans; 

• confirms for each plan that the company has reviewed all monitoring and 

operational data since the previous annual report that is relevant to a decision 

on whether to update the plan; 

• states with regard to each plan whether an update was determined to be 

warranted; and 

• for those plans where the operator did decide that an update was appropriate, 

a statement that the update has or has not been completed and a summary of the 

modifications that have been made. 

The rule should further provide that the Director has authority to require 

submission of copies of updated plans and/or further information regarding the 

reasons why updates of particular plans have or have not been done. 

Response: The final GS regulation retains the reporting requirements as proposed and does not

include a requirement for an annual report. Instead, EPA believes that periodic reevaluation of the

AoR, as required at §146.84(e), along with any revisions to the required plans that may be required

based on the AoR reevaluation, will promote an ongoing relationship between the permitting

authority and the owner or operator. The final GS rule, at §§146.84(c), 146.90(j), and 146.94(d),

requires owners or operators to review and update the AoR and corrective action plan, the testing

and monitoring plan, and the emergency and remedial response plan throughout the life of the

project. 
Regarding the content of the reports on the updates, owners or operators must review each plan and

identify necessary amendments to the plan or demonstrate to the Director that no amendment is

needed. These reviews must be performed within one year of an AoR reevaluation, following any

significant changes to the facility (e.g., the addition of monitoring or injection wells), or when

required by the Director. In no case can reviews occur less often than once every five years. For

additional information, please see the final rule and the preamble for a discussion of EPA's final

approach to recordkeeping and reporting.

While the Agency recognizes some concerns expressed by commenters about the burden associated

with an annual report, the Agency's decision to retain the semi-annual reporting requirement at

§146.91(a) is because the semi-annual report in conjunction with the continued dialogue associated

with AoR reevaluations and periodic updates to the plans is a preferred approach to an annual report.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24820

Comment: EPA Notice Questions: 73 FR 43518 

EPA Rule Issue: 37. In addition to the above recordkeeping and reporting 

requirements, EPA considered a requirement for owners or operators of GS sites 

to provide an annual report during the lifetime of the project, including the 

post-injection period, regarding the GS operation. Although EPA has not included 

a requirement for this report in its proposal, EPA seeks comment regarding the 

necessity for such an annual report. EPA Notice 43518. 

GWPC CO2 Committee Response: See Workgroup recommendation 7.6 for further 

details. 

Report annually, or at a frequency acceptable to the Director, the 

characteristics and cumulative volumes (annual and total) of injected fluids, 

injection pressures, injection rates, annular pressures for each injection well, 

the results of any mechanical integrity tests conducted during this time period, 

available site integrity monitoring results, the extent of the injected CO2 and 

the pressure front based on current data. 

Update site operations as appropriate and site modeling results annually, or at 

a frequency acceptable to the Director, to reflect current data. 

Compare the updated results to the previous results. Identify and explain to 

the Director any discrepancies between the updated results and the previous 

results. 

Note: Technology transfer is a better forum for driving regulatory changes. Do 

not support annual reporting as outlined in the preamble. 

Response: EPA is retaining the semi-annual reporting requirements as proposed at §146.91(a).

These requirements ensure the Director has the information needed to take preventive action in a

timely manner to protect USDWs from endangerment. 
The final GS regulation does not include a requirement for an annual report. Instead, EPA believes

that periodic reevaluation of the AoR, as required at §146.84(e), along with any revisions to the

required plans that may be necessary based on the AoR reevaluation, will promote an ongoing

relationship between the permitting authority and the owner or operator. The final GS rule, at

§§146.84(c), 146.90(j), and 146.94(d), requires owners or operators to review and update the AoR

and corrective action plan, the testing and monitoring plan, and the emergency and remedial

response plan throughout the life of the project. Owners or operators must review each plan and

identify necessary amendments to the plan or demonstrate to the Director that no amendment is

needed. These reviews must be performed within one year of an AoR reevaluation, following any

significant changes to the facility (e.g., the addition of monitoring or injection wells), or when

required by the Director. In no case can reviews occur less often than once every five years.

For additional information, please see the final rule and the preamble for a discussion of EPA's final

approach to recordkeeping and reporting.

Letter ID: 0263

Commenter Organization: Interstate Oil & Gas Compact Commission Comment ID: 22824

Other EPA Comment Codes and Descriptions: 4760 2.7.6 Proposed reporting frequency (seeking

comment) 

Comment: III A. 7 Proposed Recordkeeping and Reporting Requirements 

NN. Although EPA has not included a requirement for this report in today's 

proposal, EPA seeks comment regarding the necessity for such an annual report. 

IOGCC Response: The IOGCC suggests that there be only one frequency of reporting, 

either annual or semi-annual. Thus, this requirement should be incorporated into 

the semi-annual reporting requirement enunciated by EPA in the rule for the 

physical and chemical characteristics of the injected fluids in a Class VI well. 

There should not be two different data reporting timeframe. 

Response: EPA is retaining the semi-annual reporting requirements as proposed at §146.91(a).

These requirements ensure the Director has the information needed to take preventive action in a

timely manner to protect USDWs from endangerment. 

The final GS regulation does not include a requirement for an annual report. Instead, EPA believes

that periodic reevaluation of the AoR, as required at §146.84(e), along with any revisions to the

required plans that may be required based on the AoR reevaluation, will promote an ongoing

relationship between the permitting authority and the owner or operator. The final GS rule, at

§§146.84(c), 146.90(j), and 146.94(d), requires owners or operators to review and update the AoR

and corrective action plan, the testing and monitoring plan, and the emergency and remedial

response plan throughout the life of the project. Owners or operators must review each plan and

identify necessary amendments to the plan or demonstrate to the Director that no amendment is

needed. These reviews must be performed within one year of an AoR reevaluation, following any

significant changes to the facility (e.g., the addition of monitoring or injection wells), or when

required by the Director. In no case can reviews occur less often than once every five years.

For additional information, please see the final rule and the preamble for a discussion of EPA's final

approach to recordkeeping and reporting.
As described above, EPA is retaining the semi-annual reporting requirements as proposed at

§146.91(a). These requirements ensure the Director has the information needed to take preventive

action in a timely manner to protect USDWs from endangerment. EPA notes that operators who

want to streamline their reporting schedules can negotiate with the permitting authority to establish a

schedule that allows reporting on all wells in a GS project at the same time; however, data for each

well must be reported separately and at least as frequently as required at §146.91. For additional

information, please see the final rule and the preamble for a discussion of EPA's final approach to

recordkeeping and reporting.

Commenter Name: Greg Shubel Letter ID: 0284

Commenter Organization: Inter-Tribal Council of Michigan, Inc Comment ID: 25302

Comment: requirements, EPA considered a requirement for owners or operators ofOS sites to 

provide an annual report during the lifetime of the project, including the postinjection period, regarding the GS operation." (Page 28 of 51) 

ITCMI ESD feels that this is a necessary requirement, and will provide 

invaluable data for future studies. 

Response: The final GS regulation retains the reporting requirements as outlined in the proposed

rule and does not include a requirement for an annual report. EPA believes that periodic reevaluation

of the AoR, as required at §146.84(e), along with any revisions to the required plans that may be

required based on the AoR reevaluation or other data collected during well operations, will promote

an ongoing relationship between the permitting authority and the owner or operator. The final GS

rule, at §§146.84(c), 146.90(j), and 146.94(d), requires owners or operators to review and update the

AoR and corrective action plan, the testing and monitoring plan, and the emergency and remedial

response plan throughout the life of the project. Owners or operators must review each plan and

identify necessary amendments to the plan or demonstrate to the Director that no amendment is

needed. These reviews must be performed within one year of an AoR reevaluation, following any

significant changes to the facility (e.g., the addition of monitoring or injection wells), or when

required by the Director. In no case can reviews occur less often than once every five years. 

The semi-annual reporting required at §146.91(a) includes both operational data and data required as

part of the testing and monitoring plan, satisfying many of the concerns expressed by commenters

who supported the annual report. EPA encourages and expects owners and operators to share

monitoring and operating data with the public voluntarily (e.g., through the Internet. Providing the

public with information throughout the GS project will help clear up and avoid public misperceptions

about the nature and safety of GS.

For additional information, please see the final rule and the preamble for a discussion of EPA's final

approach to recordkeeping and reporting.

Comment Code: 4760 2.7.6 Proposed reporting frequency (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: 21984

Comment: 146.91: We believe this should be monthly reporting. This is information that is 

important and needs to be reviewed at a frequency by the regulatory agency to 

ensure problems are identified and addressed in a timely manner. Think about 

this for example - quarterly reporting for say the third calendar quarter 

results in data that is collected July 1, 2008, would not be seen by the 

regulatory agency before October 30, 2009, if the operator is allowed say 30 

days after the end of the quarter to provide the report. Is that reasonable or 

appropriate? 

The timeframe for submittal of the quarterly report should be stated. 

Response: The final rule remains unchanged from the proposal and requires semi-annual reporting

of monthly average, maximum, and minimum values for injection pressure, flow rate and volume,

annular pressure, and monthly annulus fluid volume added at §146.91(a). EPA believes that monthly

reporting of routine operational data and monitoring results would provide no additional protection of

USDWs from endangerment. EPA adds that, at §146.91(c), it has included in the final rule a

requirement that operators must report within 24 hours of any event that may endanger USDWs.

EPA notes that states seeking primacy for Class VI wells are free to require more frequent reporting.

For additional information, please see the final rule and the preamble for a discussion of EPA's final

approach to recordkeeping and reporting.

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22573

Comment: regulations. The results of the MMV and modeling including the integrity of the 

wells, fluid properties and volumes, subsurface location of the plume, leakage 

monitoring, modeling, and size of the AoR should be reported at least annually 

or upon a sudden significant change. 

Response: EPA is retaining the requirement at §146.91(a) for semi-annual reporting of monitoring

and operational data. External mechanical integrity testing, which must be conducted annually, must

be reported within 30 days of the test. EPA clarifies that some monitoring frequencies (e.g.,

associated with ground water monitoring and plume tracking) will be established in the approved

testing and monitoring plan, which will be incorporated as a condition of the Class VI permit. The

frequency of these tests will be determined based on site-specific information. 

EPA clarifies the final rule includes a requirement at §146.91(c) that operators report within 24 hours

of any event that may endanger USDWs; any leakage that endangers a USDW would be addressed

in this requirement.

For additional information, please see the final rule and the preamble for a discussion of EPA's final

approach to recordkeeping and reporting.

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23367

Comment: such methods more appropriate. In addition, APPA believes that annual 

reporting will not always be the best way to collect this information over the 
lifetime of the project. 

Response: The final GS regulation retains the reporting requirements as proposed and does not

include a requirement for an annual report. Instead, EPA believes that periodic reevaluation of the

AoR, as required at §146.84(e), along with any revisions to the required plans that may be required

based on the AoR reevaluation, will promote an ongoing relationship between the permitting

authority and the owner or operator. The final GS rule, at §§146.84(c), 146.90(j), and 146.94(d),

requires owners or operators to review and update the AoR and corrective action plan, the testing

and monitoring plan, and the emergency and remedial response plan throughout the life of the

project. Owners or operators must review each plan and identify necessary amendments to the plan

or demonstrate to the Director that no amendment is needed. These reviews must be performed

within one year of an AoR reevaluation, following any significant changes to the facility (e.g., the

addition of monitoring or injection wells), or when required by the Director. In no case can reviews

occur less often than once every five years. See the final rule and preamble for further discussion on

EPA's final approach to reporting and recordkeeping.

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23419

Comment: With respect to the Proposal’s suggestion of an annual reporting requirement for 

CO2 GS projects, APPA appreciates the importance of the information EPA seeks to 

gather but believes that annual reporting will not always be the best way to 

collect this information over the lifetime of the project. Id. at 43518. The 

Final Rule will require some form of periodic reevaluation of the AoR throughout 

the life of the project; much of the information sought through the proposed 

annual reporting requirement would be gathered and submitted to EPA through the 

AoR reevaluation process. Gathering this information through the AoR 

reevaluations alone, rather than imposing an unnecessary and duplicative annual 

reporting requirement, will provide a more cost-effective and manageable method 

of information exchange for regulators and Owners or Operators alike. APPA 

prefers the idea of reporting every five years in the first 20 years of 

operations. 

Response: The final GS regulation retains the reporting requirements as proposed and does not

include a requirement for an annual report. EPA agrees that the AoR reevaluations offer a good

opportunity to promote a dialogue between the owner or operator and the permitting authority. The

final GS rule, at §§146.84(c), 146.90(j), and 146.94(d), requires owners or operators to review and

update the AoR and corrective action plan, the testing and monitoring plan, and the emergency and

remedial response plan throughout the life of the project. Owners or operators must review each plan

and identify necessary amendments to the plan or demonstrate to the Director that no amendment is

needed. These reviews must be performed within one year of an AoR reevaluation, following any

significant changes to the facility (e.g., the addition of monitoring or injection wells), or when

required by the Director. In no case can reviews occur less often than once every five years.

EPA encourages and expects owners and operators to share monitoring and operating data with the

public voluntarily (e.g., through the Internet), however. Providing the public with information

throughout the GS project will help clear up and avoid public misperceptions about the nature and

safety of GS. See the final rule and preamble for further discussion on EPA's final approach to

reporting and recordkeeping.
Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24252

Comment: Rule Provisions: 146.91 

EPA Preamble Question: 35. EPA seeks comment on the frequency of all proposed 

reporting requirements. EPA Notice 43517 

API Response: Frequency should reflect the level of risk associated with the 

activity. Semi-annual reporting is adequate. Reporting should be on a project 

basis as opposed to a well basis consistent with 146.23(c). 

Response: EPA agrees and is retaining the requirement at §146.91(a) for semi-annual reporting of

monitoring and operational data. External mechanical integrity testing, which must be conducted

annually, must be reported within 30 days of the test. EPA clarifies that some monitoring

frequencies (e.g., associated with ground water monitoring and plume tracking) will be established in

the approved testing and monitoring plan, which will be incorporated as a condition of the Class VI

permit. The frequency of these tests will be determined based on site-specific information. For

additional information, please see the final rule and the preamble for a discussion of EPA's final

approach to recordkeeping and reporting.

EPA disagrees that reporting should be on a project, rather than a per-well basis. EPA notes that

operators who want to streamline their reporting schedules can negotiate with the permitting

authority to establish a schedule that allows reporting on all wells in a GS project at the same time;

however, data for each well must be reported separately and at least as frequently as required at

§146.91.

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23846

Comment: 1. Reporting Requirements 

EPA proposes to require owners or operators of Class V1 wells to report semiannually to the permitting authority on: the physical and chemical 

characteristics of injection fluids; injection pressure, flow rate, temperature, 

volume and annular pressure; annulus fluid volume added; and the results of 

MITs, plume tracking, and atmospheric/soil gas monitoring. Additionally, owners 

and operators will be required to submit the results of AoR modeling revisions: 

any updates to the information on the type, number, and location of all wells 

within the site AoR; and information on additional corrective action performed 

or planned based on AoR reevaluations. 

A semi-annual reporting obligation with respect to the above information is 

reasonable. The CCS Alliance requests, however, that EPA streamline the final 

reporting requirements to ensure simplicity and to avoid unnecessary confusion 

or duplication of reporting obligations. For instance, proposed section 

146.91(b) requires a report within 30 days for certain tests or any well 

workover. These additional reports should be incorporated into the semi-annual 

report, as they are not so time-sensitive as to require a separate reporting 

obligation. 

Response: EPA is retaining the semi-annual reporting requirements as proposed at §146.91(a).
These requirements ensure the Director has the information needed to take preventive action in a

timely manner to protect USDWs from endangerment. EPA notes that operators who want to

streamline their reporting schedules can negotiate with the permitting authority to establish a

schedule that allows reporting on all wells in a GS project at the same time; however, data for each

well must be reported separately and at least as frequently as required at §146.91. For additional

information, please see the final rule and the preamble for a discussion of EPA's final approach to

recordkeeping and reporting.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23701

Comment: EPA Request for Comment: EPA seeks comment on the frequency of all proposed 

reporting requirements. EPA Notice 43517 

AWWA Response: AWWA recommends that the owner/operators of a Class VI well 

provide a monthly operating report to the Director instead of the semi-annual 

report as proposed. The operating information for the geologic sequestration 

project is extremely important and needs to be reviewed at a frequency by the 

regulatory agency to ensure problems are identified and addressed in a timely 

manner. For example, based on the proposed regulation, data collected on July 1, 

2008 would not be seen by the regulatory agency before January 15, 2009, if the 

operator is allowed 15 days to submit the report. This would allow for very 

little time to correct any potential issues in the operation of the project. We 

have provided example monthly reporting sheets that were developed as part of 

the AwwaRF project in Section III of our comments, and these reports are similar 

to the monthly reporting sheets used by water and wastewater treatment plants. 

Given the potential scale of carbon sequestration and the need to protect 

groundwater resources, a requirement for monthly operating reports is 

reasonable. 

Response: The final rule remains unchanged from the proposal and requires semi-annual reporting

of monthly average, maximum and minimum values for injection pressure, flow rate and volume,

annular pressure, and monthly annulus fluid volume added at §146.91(a). EPA believes that monthly

reporting of routine operational data and monitoring results would provide no additional protection of

USDWs from endangerment. EPA adds, at §146.91(c), that it has included in the final rule a

requirement that operators must report within 24 hours of any event that may endanger USDWs.

EPA notes that states seeking primacy for Class VI wells are free to require more frequent reporting. 

EPA reviewed the sample reporting forms submitted by AWWA (EPA-HQ-OW-2008-0390-0181).

The Agency will refer to these as it prepares guidance for complying with the reporting

requirements. However, EPA notes that most reporting will be done electronically.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23746

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

language 

Comment: Part 146.91(11)(a) AWWA believes that the reporting frequency should be on a 

monthly basis, similar to what water and wastewater treatment plants have to do. 

The operating information for the geologic sequestration project is extremely 
important and needs to be reviewed at a frequency by the regulatory agency to 

ensure problems are identified and addressed in a timely manner. For example, 

with the way the regulation is currently structured, data collected on July 1, 

2008 would not be seen by the regulatory agency before January 15, 2009, if the 

operator is allowed 15 days to submit the report. This would allow for very 

little time to correct any potential issues in the operation of the project. As 

such, AWWA recommends revising this part to read: 

Monthly reports, due on the 15th day of each month for the previous month’s 

activities, containing: 

Response: As described above, the final rule remains unchanged from the proposal and requires

semi-annual reporting of monthly average, maximum and minimum values for injection pressure,

flow rate and volume, annular pressure, and monthly annulus fluid volume added at §146.91(a). EPA

believes that monthly reporting of routine operational data and monitoring results would provide no

additional protection of USDWs from endangerment. 

For additional information, please see the final rule and the preamble for a discussion of EPA's final

approach to recordkeeping and reporting.

Commenter Name: Bradley J. Field Letter ID: 0186

Commenter Organization: New York State Dept. of Environmental Conservation

Div. of Mineral Resources

Comment ID:

25204

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

Monitoring Requirements (40 CFR 146.90) 

Comment: FF. EPA seeks comment on the appropriate amount and types of monitoring that should 

be conducted at a GS site. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with EPA’s proposal to require operators 

to report semi- annually on the characteristics of injection fluids, injection 

pressure, flow rate, temperature, volume and annular pressure, and on the 

results of MITs, ground water monitoring, and any required atmospheric/soil gas 

monitoring. However, the amount and types of monitoring to be required should be 

site specific. 

Response: EPA agrees that monitoring plans and methods need to be site-specific and believes that

the monitoring requirements for GS sites at §146.90 provide an appropriate level of flexibility in

structuring a testing and monitoring plan that protects USDWs from endangerment. 

The final regulation provides for flexibility in: 1) methodologies used to collect these data, 2) the

spatial resolution at which the data should be collected, and 3) how often the data should be

collected. The number and placement of monitoring wells will be based on site-specific information

such as the calculated AoR, injection rate and volume, site geology, baseline data, and the presence

of artificial penetrations within the AoR. In some instances, there may be a limited number of

options for complying with EPA's minimum requirements. For example, monitoring for geochemical

changes will require use of monitoring wells and collection of groundwater samples for chemical

analysis. Many options currently exist for complying with other requirements, such as tracking the

position of the plume and pressure front within the injection zone.
Flexibility is also provided regarding how to monitor for the specific data required by the final rule.

The testing and monitoring plan is developed by the owner or operator in consultation with the

Director and is designed to ensure that a detailed, Director-approved document describing how

monitoring will be conducted during the lifetime of the project exists. EPA is developing guidance

on testing and monitoring to assist owners or operators and Directors in evaluating requirements

under §146.90, including proposed monitoring plans. The guidance describes available technologies

and recommended approaches for implementing a testing and monitoring plan, including preoperational 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.

EPA is retaining the semi-annual reporting requirements as proposed at §146.91(a). These

requirements ensure the Director has the information needed to take preventive action in a timely

manner to protect USDWs from endangerment. EPA notes that operators who want to streamline

their reporting schedules can negotiate with the permitting authority to establish a schedule that

allows reporting on all wells in a GS project at the same time; however, data for each well must be

reported separately and at least as frequently as required at §146.91. For additional information,

please see the final rule and the preamble for a discussion of EPA's final approach to recordkeeping

and reporting.

EPA agrees that some monitoring types and frequencies (e.g., associated with ground water

monitoring and plume tracking) will be site-specific. These activities must be established in the

approved testing and monitoring plan, which will be incorporated as a condition of the Class VI

permit.

Commenter Name: Bradley J. Field Letter ID: 0186

Commenter Organization: New York State Dept. of Environmental Conservation

Div. of Mineral Resources

Comment ID:

25205

Other EPA Comment Codes and Descriptions: 4655 2.6.5.1 Plume tracking

techniques/geophysical methods (seeking comment) 

Comment: GG. Specifically, EPA seeks comment regarding the usefulness of indirect 

geophysical monitoring and surface air and soil gas monitoring. 

NYSDEC-DMN Response: NYSDEC-DMN agrees with EPA’s proposal to require operators 

to report semi- annually on the characteristics of injection fluids, injection 

pressure, flow rate, temperature, volume and annular pressure, and on the 

results of MITs, ground water monitoring, and any required atmospheric/soil gas 

monitoring. However, the amount and types of monitoring that are required should 

be site specific. Certain geophysical monitoring techniques that successfully 

monitor plume migration in the southern states may not have any monitoring 

capability in northern Paleozoic basins. 

Response: EPA agrees with commenters and believes that flexibility is important in developing and

implementing a monitoring plan that is appropriately tailored for a specific GS site. The purpose of

the requirement at §146.90 to develop site-specific testing and monitoring plans is to ensure that the

monitoring performed at a site is appropriate for site operational conditions and the geologic setting.

EPA believes that this is the best approach for addressing potential risks at GS sites. These flexible

provisions in the monitoring requirements for Class VI wells enable the owner or operator to tailor

monitoring programs to the specific needs of each project in consultation with the Director.
EPA clarifies that the final rule, at §146.90(g)(2), requires owners or operators to track the position

of the CO2 plume using indirect methods (e.g., seismic, electrical, gravity, or electromagnetic

surveys and/or down-hole CO2 detection tools), unless the Director determines based on site-specific

geology, that such methods are not appropriate. EPA is affording Director's discretion regarding the

use of geophysical techniques at some sites because the Agency recognizes that geophysical methods

are not appropriate in all geologic settings. For example, geophysical methods are difficult to execute

in areas that are structurally and topographically complex or where lithologies have limited contrast

in density, porosity, permeability, and other physical properties. EPA clarifies that this determination

will be made by the Director based on the site-specific geologic information submitted by the owner

or operator with their permit application. 

EPA believes that this approach provides flexibility to develop a site-specific monitoring plan,

ensures that direct monitoring is available to track the movement of the CO2 and validate models,

and recognizes that indirect techniques are not appropriate in all situations. The owner or operator's

approved testing and monitoring plan must include the site-specific details, technologies, testing and

monitoring frequencies, and other pertinent information.

As described above EPA is retaining the requirement at §146.91(a) for semi-annual reporting of

monitoring and operational data. For additional information, please see the final rule and the

preamble for a discussion of EPA's final approach to recordkeeping and reporting.

Commenter Name: Bradley J. Field Letter ID: 0186

Commenter Organization: New York State Dept. of Environmental Conservation

Div. of Mineral Resources

Comment ID:

25208

Comment: JJ. EPA seeks comment on the frequency of all proposed reporting requirements. 

NYSDEC-DMN Response: NYSDEC-DMN supports all stated reporting frequencies and 

requirements. 

Response: The final GS regulation retains the reporting requirements as outlined in the proposed

rule and does not include a requirement for an annual report. For additional information, please see

the final rule and the preamble for a discussion of EPA's final approach to recordkeeping and

reporting.

The semi-annual reporting required at §146.91(a) includes both operational data and data required as

part of the testing and monitoring plan, satisfying many of the concerns expressed by commenters

who supported the annual report.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24486

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

language 

Comment: Rule Provision: 146.91(a) 

Proposed CCS Group Recommendations: (a) Semi-annual OR LESS FREQUENT AT THE 

DISCRETION OF THE DIRECTOR reports containing: 
Basis for CCS Group Comments: Over the life of the project, the Director may 

decide that less reporting is acceptable 

Response: EPA is retaining the semi-annual reporting requirement in the final rule at §146.91(a) in

order to ensure that permitting authorities can maintain proper oversight of GS projects, particularly

in the early stages of rule implementation and deployment of GS technologies. The Agency also

clarifies that permitting authorities may choose to require more frequent reporting, at the discretion

of the Director. See the final rule and preamble for further discussion on EPA's final approach to

reporting and recordkeeping.

EPA is using an adaptive approach to regulating GS. The Agency plans to, every six years, collect

and review data on GS projects, including operational data, to determine whether the appropriate

amount and types of information and appropriate documentation are being collected, and to

determine if modifications to the requirements are appropriate or necessary.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24544

Comment: Rule Provisions or Federal Register Cite: 146.91 

EPA Preamble Question: 35. EPA seeks comment on the frequency of all proposed 

reporting requirements. EPA Notice 43517 

CSC Response: Frequency should reflect the level of risk associated with the 

activity. Semi-annual reporting is adequate. Reporting should be on a project 

basis as opposed to a well basis consistent with 146.23(c). 

Response: EPA is retaining the semi-annual reporting requirements as proposed at §146.91(a).

These requirements ensure the Director has the information needed to take preventive action in a

timely manner to protect USDWs from endangerment. See the final rule and preamble for further

discussion on EPA's final approach to reporting and recordkeeping.

EPA disagrees that reporting should be on a project, rather than a per well, basis. EPA notes that

operators who want to streamline their reporting schedules can negotiate with the permitting

authority to establish a schedule that allows reporting on all wells in a GS project at the same time;

however, data for each well must be reported separately and at least as frequently as required at

§146.91. 

EPA is using an adaptive approach to regulating GS. The Agency plans to, every six years, collect

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

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

the requirements are appropriate or necessary.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24605

Comment: Rule Provisions: 146.91 

EPA Rule Issue: 35. EPA seeks comment on the frequency of all proposed reporting 

requirements. EPA Notice 43517 

Anadarko Petroleum Corporation (APC) Response: Frequency should reflect the 
level of risk associated with the activity. Semi- annual reporting is adequate. 

Reporting should be on a project basis as opposed to a well basis consistent 

with 146.23(c). 

Response: EPA is retaining the semi-annual reporting requirements as proposed at §146.91(a).

These requirements ensure the Director has the information needed to take preventive action in a

timely manner to protect USDWs from endangerment. EPA notes that operators who want to

streamline their reporting schedules can negotiate with the permitting authority to establish a

schedule that allows reporting on all wells in a GS project at the same time; however, data for each

well must be reported separately and at least as frequently as required at §146.91. For additional

information, please see the final rule and the preamble for a discussion of EPA's final approach to

recordkeeping and reporting.

EPA agrees that some monitoring types and frequencies (e.g., associated with ground water

monitoring and plume tracking) will be site-specific. These activities must be established in the

approved testing and monitoring plan, which will be incorporated as a condition of the Class VI

permit.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23258

Comment: 35. EPA seeks comment on the frequency of all proposed reporting requirements. 

EPA Notice 43517. 

Reporting frequency should coincide with requirements for existing UIC injection 

well classes unless there is a need for more frequent reporting. 

Response: EPA clarifies that reporting requirements for existing injection wells vary by well class.

The Agency believes semi-annual reporting is appropriate for Class VI GS wells during the

operational phase of the project. EPA believes that the potentially large injection volumes and

injection pressures associated with GS warrant more frequent reporting than for other well classes.

See the final rule and preamble for further discussion on EPA's final approach to reporting and

recordkeeping.

EPA is using an adaptive approach to regulating GS. The Agency plans to, every six years, collect

and review data on GS projects 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: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24932

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

language 

Comment: Rule Provision: 146.91 

11. Reporting requirements. 

The owner or operator must, at a minimum, provide the following reports to the 

Director, for each permitted Class VI well: 
(a) Semi-annual reports containing: 

(1) Any changes to the physical, chemical and other relevant characteristics of 

the carbon dioxide stream from the proposed operating data; 

(2) Monthly average, maximum and minimum values for injection pressure, flow 

rate and volume, and annular pressure; 

GWPC Recommendations: (a) Semi-annual or at a frequency determined by the 

Director reports containing: 

(1) Any significant changes to the physical, chemical and other relevant 

characteristics of the carbon dioxide stream from the proposed operating data; 

Rationale: Should be semi-annual unless otherwise determined 

Response: EPA is retaining the semi-annual reporting requirements as proposed at §146.91(a).

These requirements ensure the Director has the information needed to take preventive action in a

timely manner to protect USDWs from endangerment. For additional information, please see the

final rule and the preamble for a discussion of EPA's final approach to recordkeeping and reporting.

Letter ID: 0263

Commenter Organization: Interstate Oil & Gas Compact Commission Comment ID: 22822

Comment: III A. 7 Proposed Recordkeeping and Reporting Requirements 

LL. EPA seeks comment on the frequency of all proposed reporting requirements. 

IOGCC Response: As concerns the frequency of reporting for the physical and 

chemical characteristics of the injected fluids in a Class VI well, IOGCC 

model regulations specified annual reporting although semiannual reporting (as 

proposed by EPA in the rule) would be acceptable. 

Response: EPA is retaining the semi-annual reporting requirements as proposed at §146.91(a).

These requirements ensure the Director has the information needed to take preventive action in a

timely manner to protect USDWs from endangerment. For additional information, please see the

final rule and the preamble for a discussion of EPA's final approach to recordkeeping and reporting.

Letter ID: 0263

Commenter Organization: Interstate Oil & Gas Compact Commission Comment ID: 22824

Other EPA Comment Codes and Descriptions: 4750 2.7.5 Comments on the merit of annual

reports (seeking comment) 

Comment: III A. 7 Proposed Recordkeeping and Reporting Requirements 

NN. Although EPA has not included a requirement for this report in today's 

proposal, EPA seeks comment regarding the necessity for such an annual report. 

IOGCC Response: The IOGCC suggests that there be only one frequency of reporting, 

either annual or semi-annual. Thus, this requirement should be incorporated into 
the semi-annual reporting requirement enunciated by EPA in the rule for the 

physical and chemical characteristics of the injected fluids in a Class VI well. 

There should not be two different data reporting timeframe. 

Response: EPA is retaining the semi-annual reporting requirements as proposed at §146.91(a).

These requirements ensure the Director has the information needed to take preventive action in a

timely manner to protect USDWs from endangerment. 

The final GS regulation does not include a requirement for an annual report. Instead, EPA believes

that periodic reevaluation of the AoR, as required at §146.84(e), along with any revisions to the

required plans that may be required based on the AoR reevaluation, will promote an ongoing

relationship between the permitting authority and the owner or operator. The final GS rule, at

§§146.84(c), 146.90(j), and 146.94(d), requires owners or operators to review and update the AoR

and corrective action plan, the testing and monitoring plan, and the emergency and remedial

response plan throughout the life of the project. Owners or operators must review each plan and

identify necessary amendments to the plan or demonstrate to the Director that no amendment is

needed. These reviews must be performed within one year of an AoR reevaluation, following any

significant changes to the facility (e.g., the addition of monitoring or injection wells), or when

required by the Director. In no case can reviews occur less often than once every five years.

For additional information, please see the final rule and the preamble for a discussion of EPA's final

approach to recordkeeping and reporting.

As described above, EPA is retaining the semi-annual reporting requirements as proposed at

§146.91(a). These requirements ensure the Director has the information needed to take preventive

action in a timely manner to protect USDWs from endangerment. EPA notes that operators who

want to streamline their reporting schedules can negotiate with the permitting authority to establish a

schedule that allows reporting on all wells in a GS project at the same time; however, data for each

well must be reported separately and at least as frequently as required at §146.91. For additional

information, please see the final rule and the preamble for a discussion of EPA's final approach to

recordkeeping and reporting.

Comment Code: 5000 2.8 Proposed Well Plugging and Post-Injection Site Care Requirements 

Individual Comments

Commenter Name: Herbert Skolnick, Ph.D. Letter ID: 0110

Commenter Organization: Group Against Smog and Pollution, Inc. (GASP) Comment ID: 22038

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

Long-Term Care Requirements 

Comment: Finally, given the lower costs of CO2 sequestration in existing oil fields and 

the attendant increased oil production, sequestration in existing oil fields is 

also more likely to provide storage site operators with the financial resources 

necessary to ensure proper site closure and post-closure care, and to meet longterm financial assurance requirements. 

Response: EPA agrees with the commenter that depleted oil and gas reservoirs associated with ER
operations may be used for CO2 storage and that these sites may be some of the first sites where

commercial-scale GS is deployed. 

EPA clarifies that the goal of financial responsibility is to ensure that financial resources are

available to prevent or remediate the endangerment of USDWs from improper plugging,

remediation, and management of wells in the event that the owner or operator experiences financial

difficulties. Assuring financial responsibility for corrective action on wells in the AoR, injection well

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

component of ensuring that USDWs are protected. 

EPA is developing guidance on financial responsibility for Class VI wells (available on EPA's

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm) that describes the

types of financial instruments that owners or operators may use to meet financial responsibility

requirements for Class VI wells. 

Commenter Name: Paul Pike Letter ID: 0111

Commenter Organization: Ameren Corporation on behalf of USWAG Comment ID: 22405

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards); 3500 2.2.3 Area of Review Reevaluation (seeking comment) 

Comment: 6. Because of the widely varied characteristics and limitations of different 

carbon dioxide sequestration projects, it is essential to incorporate 

performance-based standards into the Final Rule, leading to a site-specific 

approach to requirements for Area of Review reevaluation and post-injection site 

care and closure periods. 

Response: The post-injection site care requirements in the final GS rule, as specified in §146.93(b),

incorporate a combination of a fixed timeframe and a performance standard approach. The GS rule

offers owners or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing

the Director discretion to shorten or lengthen the PISC timeframe during the PISC period based on

site-specific data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to

allow a Class VI well owner or operator to demonstrate, based on substantial data during the

permitting process, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available on EPA's web

site, at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.
In response to comments about AoR evaluation, EPA disagrees that the GS regulation should include

performance-based standards for AoR calculation. However, EPA believes that consideration of sitespecific conditions is appropriate for the AoR calculation and reevaluation process. EPA believes

that the flexibility incorporated into the AoR and corrective action plans and the provision for AoR

reevaluation as required at §146.84(e) provide for an ongoing review of the site and a dialogue

between the Director and the owner or operator to ensure that the most appropriate modeling and

corrective action technologies are used to protect USDWs from endangerment. 

Commenter Name: George Holliday, PhD, PE, BCEE Letter ID: 0114

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 22519

Other EPA Comment Codes and Descriptions: 1340 1.1.3.2 Oppose use of GS in general; 3800

2.3 Proposed Injection Well Construction Requirements (40 CFR 146.86) 

Comment: passing a written examination. Further, the Agency proposes to sequester 

buoyant CO2 until the end-of-time by only requiring 50 years of monitoring (40 

CFR 146.93(b)(1)). In addition, EPA proposes using well completion materials 

not currently developed and proven corrosion-resistant under carbonic acid 

corrosive conditions. 

The proposed regulations are a formula for future disaster: 1) Dangerous to 

sequester CO2, a supercritical fluid stored at high pressure (2200± psi): 2) 

Response: EPA does not believe that a properly managed GS site is dangerous. The Class VI GS

regulation builds upon the long-standing protective framework of the UIC program, which has been

regulating the injection of billions of gallons of liquids for decades. The Class VI GS regulation

enhances this existing framework with requirements for Class VI wells that are tailored to the unique

nature of large scale GS of CO2. 

EPA believes that a 50 year post-injection site care timeframe represents a reasonable and protective

post-injection site monitoring period for most GS projects and available data, including data

submitted by commenters, do not support a different default timeframe. EPA bases this on a review

of research studies, industry reports, and existing environmental programs, and evaluation of public

comments. EPA adds that the GS regulation includes a provision that the Director may, at their

lengthen the post-injection site care timeframe if the owner or operator cannot demonstrate that

movement of the plume and pressure front have ceased and the injectate does not pose a risk to

USDWs (146.93(b)(2)).

EPA disagrees that corrosion-resistant materials and cement do not exist. Industry experience of

many decades in corrosive down-hole situations such as acid gas injection and production of natural

gas with carbon dioxide and hydrogen sulfide impurities shows that materials are available that can

resist corrosive environments. Meyer (2007) lists several types of cements that have been used under

such corrosive conditions. EPA acknowledges that studies have likely not been performed to prove a

50-year life span for corrosion-resistant materials. However, there are two studies of wells that were

exposed to CO2 for approximately 30 years by Carey et al. (2007) and Crow et al. (2008). Although

these studies are limited in the number of well material samples and the number of wells examined,

the casing and cement sampled indicate fairly good condition (i.e., fairly significant corrosion

resistance) of well materials installed three decades ago. The best available corrosion-resistant

materials suited for each GS project will be determined by the Director. 

EPA adds that, to address potential risks associated with high pressures associated with CO2
injection for GS, the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class

VI wells install automatic surface shut-off devices. Owners or operators must also monitor pressure

in the injection zone, as required at §146.90(g).

EPA acknowledges that there are limited data on this subject, and believes that providing multiple

barriers of protection is the most appropriate approach to protecting USDWs from endangerment.

See the discussion of Class VI well construction requirements in the preamble to the final GS rule

for additional information. Additionally, EPA is developing guidance on the construction of Class VI

wells. This guidance will be available on EPA’s website at

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

The Agency plans to, every six years, collect and review project data on early GS projects to

determine whether the appropriate amount and types of information and appropriate documentation

are being collected, and to determine if modifications to the requirements are appropriate or

necessary. 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24810

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

language 

Comment: §146.94 Emergency and remedial response. 

(a) As part of the permit application, THE OWNER OR OPERATOR must provide the 

Director with an emergency and remedial response plan that describes actions to 

be taken to address movement of the injection or formation fluids that may cause 

an endangerment to a USDW during construction, operation, closure and postclosure periods. 

{Redundant - See 146.82(X)} 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

Commenter Name: Emily Rochon Letter ID: 0129

Commenter Organization: Greenpeace International Comment ID: 23068

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

Long-Term Care Requirements 

Comment: It must be reiterated that monitoring and verification of CO2 storage sites is a 

long-term task. It does not end when the storage reservoir is capped. Postoperational monitoring over hundreds of years is essential. Significant risks 

continue to exist and must be monitored both to prevent a catastrophic short 

term release as well as long-term slow leakage. Even if it is feasible to bury 

hundreds of thousands of gigatons of CO2, there is no way to guarantee that 

storage locations will be appropriately designed and managed over the timescales 

required. 

Response: EPA agrees that post-injection monitoring should continue for an extended time, but
disagrees that hundreds of years of monitoring would be needed. EPA believes that a 50 year postinjection site care timeframe represents a reasonable and protective monitoring period. EPA bases

this on a review of research studies, industry reports, existing environmental programs, and

evaluation of public comments. Furthermore, EPA believes that a 50-year default post-injection site

care timeframe is not overly burdensome, does not exaggerate the risks associated with GS, is

consistent with other environmental programs, and sufficiently protects USDWs from endangerment.

For this reason, the final GS regulation retains the 50 year post-injection site care timeframe, as

specified in §146.93(b)(1).

The GS rule provides the Director with discretion to extend the timeframe (e.g., if, after 50 years,

monitoring data indicates that the CO2 plume may endanger a USDW), or shorten the timeframe (if

the owner or operator can demonstrate that the GS project does not pose an endangerment to

USDWs), under 146.93(b)(2). Such a demonstration will be site-specific, and based on pressure

monitoring and USDW impacts. EPA clarifies that in no cases will site closure be authorized until

the owner or operator demonstrates to the satisfaction of the Director that the site no longer poses a

risk of endangerment to USDWs. 

Under SDWA authority, owners or operators of injection wells must ensure protection of USDWs

from endangerment and are subject to liability for enforcement under the Act. 

Once an owner or operator has met all regulatory requirements under Part 146 for Class VI wells and

the Director has approved site closure pursuant to requirements at §146.93, the owner or operator

will generally no longer be subject to enforcement for regulatory noncompliance. Furthermore, his or

her financial instrument as required under §146.85 will be released if it was not used. However, even

if a site closure is approved under §146.93, an owner or operator may be held liable for regulatory

noncompliance (including violation of 40 CFR 144.12) in certain circumstances. For example, an

owner or operator may be held liable for regulatory noncompliance even after site closure was

approved if the Director relied on erroneous information (e.g., erroneous modeling data) provided by

the owner or operator when approving site closure. 

Additionally, an owner or operator may always be subject to any action, such as administrative

orders or civil actions, the Administrator deems necessary to protect the health of persons under

§1431 of the SDWA after site closure if there is unanticipated migration towards or into a USDW

that causes or threatens imminent and substantial endangerment to public health. If the owner or

operator fails to comply with the order, he or she may be subject to a civil penalty for each day in

which such violation occurs or failure to comply continues. 

The Agency clarifies that Class VI well permits may be transferred to another owner or operator

pursuant to §144.38 whereby generally all other regulatory responsibilities are transferred to that new

owner and operator, including all potential liabilities associated with meeting the requirements of that

permit. Please see further clarification on the issue of long term liability in the preamble of the final

rule.

Furthermore, after site closure an owner or operator may remain liable under tort and other remedies,

or under other federal statutes including, but not limited to, the Clean Air Act, 42 U.S.C. §§ 7401-

7671; CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. EPA does not have

authority to transfer SDWA or other legal liability for Class VI wells to the State or federal

government or a third-party fund. See the final rule preamble for further discussion of EPA's final

approach.
Commenter Name: Brianne Metzger Letter ID: 0151

Commenter Organization: Spectra Energy Corp Comment ID: 21877

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards); 5400 2.9 Proposed Financial Responsibility and Long-Term Care Requirements 

Comment: IV. EPA MUST DEVELOP A FLEXIBLE FRAMEWORK TO ADDRESS POSTINJECTION SITE CARE, 

FINANCIAL ASSURANCE, AND LONG TERM LIABILITY THAT ELIMINATES OBSTACLES

TO 

COMMERCIAL-SCALE DEPLOYMENT OF CCS. 

Numerous studies and commentators have recognized that the principle obstacle 

to commercial-scale deployment of CCS is regulatory uncertainty over the 

capture, transport, injection, and storage of CO2. As stated by a recent GAO 

report: 

The IPCC, two federal advisory committee reports, and many stakeholders we 

contacted agreed that key regulatory and legal issues will need to be addressed 

if CCS is to be deployed at commercial scale. Among these issues are (1) 

confusion over the rules for injecting large volumes of CO2, (2) long-term 

liability issues concerning CO2 storage and potential leakage, (3) how property 

ownership patterns may affect CO2 storage, and (4) how the Clean Air Act will 

apply to facilities that capture CO2. - EPA’s 2007 UIC workshop, attended by 

more than 200 stakeholders, revealed liability associated with unintended 

migration of injected CO2 to be a critical concern. Similarly, 19 of the 20 

stakeholders we interviewed told us that liability related to CO2 storage was a 

large or very large barrier to deployment of CCS at a commercial scale, with 

some noting that liability concerns have already negatively impacted companies’ 

ability to initiate CCS projects. For example, two stakeholders reported that 

these concerns had already made it difficult to obtain insurance for CCS 

projects. They noted specifically that insurers have difficulty writing 

insurance policies because of uncertainties associated with and limited data 

available for CCS, while another added that investors will not support projects 

like CCS if they expose them to unlimited and undefined long-term liabilities, 

especially when future revenue streams are uncertain.[14] 

The promise of CCS as a strategy to address climate change and promote national 

energy security hinges on resolving this regulatory uncertainty in a way that 

does not place an unreasonable burden on site owners and operators that would 

effectively prevent the development of commercial-scale CCS projects in the 

United States. The EPA has the authority under SDWA and the UIC Program to 

create a flexible framework to address issues such as post-injection site care, 

financial assurance, and long-term liability in a manner that places enough 

responsibility on owners and operators to ensure that all applicable best 

practices are followed, but not so much that it becomes virtually impossible to 

secure the requisite financing and insurance needed for CCS projects to be 

commercially viable. 

The potentially unique challenge of resolving the regulatory uncertainty 

currently inhibiting the development of CCS projects, if done with inadequate 

attention to existing market dynamics and economic realities, likely will 
preclude any commercial-scale deployment of CCS and undermine its effectiveness 

as a strategy to reduce greenhouse gas emissions. Addressing the regulatory 

uncertainty surrounding post-injection site care, financial assurance, and 

long-term liability effectively boils down to four overarching questions 

confronting entities involved in the capture, transport, injection, and storage 

of CO2: (1) length of the post-injection site care time period; (2) aspects of 

post-injection site care for which entities will be responsible; (3) 

availability and suitability of different risk management instruments for 

meeting financial assurance requirements; and (4) permanent transfer of all 

liability to the State. Spectra’s comments on post-injection site care, 

financial assurance, and long-term liability focus broadly on these issues. 

14 GAO Report, Climate Change, Federal Actions Will Greatly Affect the 

Viability of Carbon Capture and Storage As a Key Mitigation Option, Report to 

the Chairman on the Select Committee on Energy Independence and Global Warming, 

House of Representatives, GAO-08-1080, September 2008, at 23, 25. See also 

Capturing King Coal: Deploying Carbon Capture and Storage Systems in the US at 

Scale, WORLD RESOURCES INSTITUTE (2008) at 24 ("In the event of an accident or 

damage years after the well is closed, who is financially and legally 

responsible? Current law and policy is unclear on this matter, and more 

generally on the matter of responsibility for long-term measuring and 

monitoring of the site. In particular, the degree to which private parties 

remain responsible, or the government assumes a measure of responsibility, is 

important."). 

Response: EPA acknowledges the commenter¿s request for certainty regarding post-injection site

care (PISC) requirements for GS wells. However, EPA believes that a certain amount of flexibility is

appropriate for setting the PISC timeframe, given the variety of circumstances that may occur at GS

sites. The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a

combination of a fixed timeframe and a performance standard approach. The GS rule offers owners

or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director

discretion to shorten or lengthen the PISC timeframe during the post-injection period based on sitespecific data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to

allow a Class VI well owner or operator to demonstrate, during the permitting process based on

substantial data, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA recognizes that there are challenges associated with financial responsibility for GS projects.

However, the Agency believes that in order to protect USDWs from endangerment under the SDWA

operators must demonstrate under §146.85 that financial resources are available to plug the injection

well and provide PISC when injection begins.
Under the final GS rule owners or operators may choose from a variety of financial instruments to

demonstrate that they meet the financial responsibility requirements under §146.85, provided the

Director determines that the demonstration is adequate to pay for each activity for which financial

responsibility is required. EPA is developing guidance (available on EPA¿s website at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm) to help owners or operators,

permitting authorities, and third parties choose and evaluate appropriate financial methods.

Under SDWA authority, owners or operators of injection wells must ensure protection of USDWs

from endangerment and are subject to liability for enforcement under the Act. The final rule requires

an owner or operator to conduct monitoring as specified in the Director-approved PISC and site

closure plan following the cessation of injection until he or she can demonstrate that the GS project

no longer poses an endangerment to USDWs.

Once an owner or operator has met all requirements under Part 146 for Class VI wells and the

Director has approved site closure pursuant to §146.93, the owner or operator will generally no

longer be subject to enforcement for regulatory noncompliance. Furthermore, the financial instrument

required under §146.85 will be released if it was not used. However, even if site closure is approved,

an owner or operator may be held liable for regulatory noncompliance (e.g., violation of 40 CFR

144.12) in certain circumstances. For example, an owner or operator may be held liable for

noncompliance even after site closure if the Director relied on erroneous information (e.g., erroneous

modeling data) provided by the owner or operator when approving site closure.

Additionally, an owner or operator may always be subject to any action, such as administrative

orders or civil actions, the Administrator deems necessary under §1431 of the SDWA after site

closure if there is unanticipated migration towards or into a USDW that causes or threatens imminent

and substantial endangerment to public health. If the owner or operator fails to comply with the

order, he or she may be subject to a civil penalty for each day such violation occurs or failure to

comply continues.

The Agency clarifies that Class VI well permits may be transferred to another owner or operator

pursuant to §144.38 whereby all potential liabilities associated with meeting the requirements of that

permit are transferred to that new owner or operator.

Furthermore, after site closure an owner or operator may remain liable under tort and other remedies,

or under other federal statutes including, but not limited to, the Clean Air Act, 42 U.S.C. §§ 7401-

7671; CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. EPA does not have

authority to transfer SDWA or other legal liability for Class VI wells to the State or federal

government or a third-party fund. See the final rule preamble for further discussion of EPA's final

approach.

Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality

(MDEQ)

Comment ID:

22120

Comment: 19. EPA is seeking comments on the proposed requirements for well plugging, postinjection site care, and site closure, including the proposed requirements for 

the post-injection time period. MDEQ agrees with EPA's approach and with the 

discretion for the Director to shorten the period based upon performance 

information. 
Response: EPA acknowledges the commenter’s support and agrees that there will be circumstances

where it can be demonstrated in less than 50 years that the plume and pressure front no longer pose a

risk of endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the PISC period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, based on substantial data during the permitting process, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Olon Plunk Letter ID: 0536

Commenter Organization: Xcel Energy Comment ID: 21378

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

(40 CFR 146.83); 3800 2.3 Proposed Injection Well Construction Requirements (40 CFR 146.86);

4000 2.4 Proposed Injection Well Operating Requirements (40 CFR 146.88) 

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: 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 146.92) 

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: 21985

Comment: 146.92 (a): We believe the sequence of work listed is not appropriate. The 

bottom hole pressure should be determined prior to flushing the well to obtain a 

more accurate reading. 146.93 (b) (3): Plume stabilization needs to be 

Response: EPA is retaining the proposed approach to well plugging in the final rule at §146.92(a),

including the requirement to determine bottomhole reservoir pressure. In addition, the injection well

plugging plan must include an appropriate test or measure to determine bottomhole reservoir

pressure. EPA believes that the plugging procedures in the GS rule are necessary to ensure the

injection well does not become a conduit for future fluid movement that could result in

endangerment to USDWs.

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22570

Comment: Once injection ceases permanently, the operational portion of MMV can also 

cease. This period, called the closure period, is the time in which the 

operator will plug and abandon all wells that will not be used for further 

monitoring. Environmental MMV operations should continue throughout this period 

using the same suite of techniques as in the operational phase. 

Response: EPA clarifies that, following plugging of the injection well and until site closure is

authorized, owners or operators of GS wells must perform monitoring and provide post-injection site

care as specified in the post-injection site care and site closure plan for at least 50 years or for the

duration of the alternative timeframe approved by the Director pursuant to requirements in

§146.93(c), unless the owner or operator can make a demonstration earlier that the geologic

sequestration project no longer poses a risk of endangerment to USDWs.

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22612

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 
Comment: Proposed Rule: 146.92(d) 

Proposed revision: (d) Plugging Reports for Class VI Wells. Within 60 days 

after completion of plugging and abandonment of a well or well field the 

permittee shall submit to the Director a final report which includes: 

Proposed addition: (1) Certification of completion in accordance with approved 

plans and specifications by an appropriately qualified engineer of record or 

professional geologist. 

Note: It is important that the engineer and/or geologist have expertise and 

training in injection well drilling technology, reservoir characterization and 

injection well construction and operation. 

Proposed addition: (2) Evidence, such as a sealed copy or certification from the 

county clerk, that a surveyor's plot of the location of the abandoned well has 

been recorded in the county courthouse property records. 

Response: EPA agrees that appropriately qualified personnel (e.g., engineers and geologists) should

be involved in all aspects of the GS operation, including the well plugging process. When the owner

or operator (and/or the person who performs the plugging operation) signs the plugging report and

certifies it as accurate; they are attesting to the fact that all required activities were performed by

qualified personnel. This is required under §146.92(d) and is a condition of the permit that is

enforceable under §1423 of the SDWA. EPA clarifies that, in addition to requiring appropriate well

plugging, the Director retains the option of witnessing any plugging activity or testing at the well. 

EPA clarifies that §146.93(g) requires the owner or operator, as part of the closure process, to record

a notation on the deed stating that the property was used for GS. In addition, §146.93(f)(1) requires

submission of a survey plat indicating the location of the well to the local zoning authority, as well

as to the Director. 

Commenter Name: Michael J. Miller Letter ID: 0168

Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22498

Other EPA Comment Codes and Descriptions: 3862 2.3.3.1 Use of corrosion-resistant

construction materials (seeking comment); 3864 2.3.3.2 Use of corrosion-resistant cements (seeking

comment) 

Comment: Preamble, page 43507: "Today’s proposal does not prescribe the specific cements 

to be used to plug abandoned wells..." 

Also, preamble, page 43510: "EPA seeks comment regarding requirements for 

degradation-resistant well construction materials, such as acid-resistant 

cements and corrosion resistant casing." 

EPRI COMMENT #5: We question the adequacy of the evidence employed to justify 

requiring the use of corrosion resistant cements in all cases. The laboratory 

study performed by Duguid, et al. (2004) cited by EPA exposed portland cement 

samples to acidified waters in an aggressive flow configuration uncharacteristic 

of a borehole environment. In contrast, the field study by Crow, et al. (2008) 

performed on a 30 year old production well is characteristic of a borehole 
environment. Side-wall cores of the casing, acoustic bond logs and well 

integrity tests did not show signs of casing corrosion, leakage or cement-bond 

degradation. While side-wall cores of the cement indicated that CO2-induced 

cement alteration had occurred, the hydraulic integrity of the cement seal was 

still highly effective. EPA states that the cement alteration found in the study 

demonstrates that CO2 migrated up the borehole. We question this conclusion and 

believe the study is not conclusive on this point. Given that the study was 

performed on a natural CO2 reservoir, free and dissolved CO2 are expected to be 

present throughout the stratigraphic column from the top of the reservoir 

through the confining unit to the surface. Therefore, an alternative hypothesis 

is that the native CO2 present in the confining unit or caprock adjacent to the 

cement seal caused the observed alteration. Evidence that the cement underwent 

greater alteration at the cement-formation interface adjacent to the caprock 

compared to the cement-casing interface located further from the caprock helps 

support this hypothesis. Most importantly, the seal maintained its integrity, 

exhibiting very low cement matrix, and low interface permeabilities, as 

determined by laboratory and vertical interference tests in the field, 

respectively. However, should the EPA eventually adopt a requirement for 

corrosion-resistant materials, we believe EPA is taking the correct approach by 

not prescribing the type of corrosion-resistant cements and casing to be used in 

well completions and abandonments; a number of materials are available and 

selection of a given material may be driven by site-specific well 

characteristics. 

Duguid, A., M. Radonjic, R. Bruant, T. Mandecki, G. Scherer, and M. Celia. 2004. 

The Effect of CO2 Sequestration on Oil Well Cements. Presented at the Greenhouse 

Gas Technologies Conference (GHGT-7), September 5-9, 2004. Vancouver, Canada. 

Crow, W., D.B. Williams., B. Carey, M. Celia, and S. Gasda. 2008. CO2 Capture 

Project Field Study of A Wellbore from a Natural CO2 Reservoir. Presented at the 

7th Annual Conference on Carbon Capture and Sequestration, May 5-8, 2008. 

Pittsburgh, Pennsylvania. 

Response: EPA considered both field and lab studies in developing the requirements for Class VI

well construction. The Duguid study referenced by the commenter examined a CO2-saturated brine

flux condition that may be found in some injection environments such as a saline aquifer. The Crow

study mentioned was a well that produced gaseous CO2 from a natural CO2 deposit. In the studies

examined, cement alteration and corrosion was found to occur at differing rates. Factors such as

contact with brine, temperature, CO2 flux, and time between cement curing and CO2 exposure may

all be relevant. See the discussion of Class VI well construction requirements in the preamble to the

final GS rule for additional information. 

EPA clarifies that corrosion-resistant cement is not specifically required in a Class VI injection well.

Rather, as stated in §146.86(b)(1), casings and cement used must have sufficient strength and be

designed for the life of the sequestration project. Further, materials must meet standards listed in the

rule and be compatible with fluids with which the materials may be expected to come into contact.

Therefore, some well materials may need to be acid-resistant and some may not if they do not come

in contact with the CO2 stream or other corrosive fluids and if approved by the Director. 

EPA clarifies that the GS rule does not prescribe the specific cements to be used to plug abandoned
wells in the AoR because industry standards, such as those developed by API or ASTM

International, reflect the current state of the science and the expertise of industrial users on CO2-

compatible materials, as specified in §146.92(b). Providing flexibility to choose materials for

plugging, provided they are compatible with the injected fluid, is consistent with requirements for

other injection well classes and will allow operators to utilize improved well technologies as they

become available in the future without a need to amend the regulation.

EPA plans to, every six years, collect and review project data on early GS projects and continue to

monitor field and laboratory research 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: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24199

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

language 

Comment: Rule Provision: 146.92(a) 

API Comments: (a) Prior to the well plugging, the owner or operator must flush 

each Class VI injection well with a buffer fluid, determine bottomhole reservoir 

pressure, and perform a final EXTERNAL mechanical integrity test OF ANY RELEVANT 

WELLBORE MATERIALS REMAINING. 

Rationale: Many of the components that would be tested by an internal MIT are 

removed or tested during the plugging process. 

Response: EPA agrees that only an external MIT is required, and has modified the GS rule at

§146.92(a) to require owners or operators to perform a final external mechanical integrity test prior

to the well plugging.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24200

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

language 

Comment: Rule Provision: 146.92(b)(2) 

API Comments: (2) Appropriate testing methods to ensure FINAL EXTERNAL 

mechanical integrity as specified in §146.89(C); 

Rationale: Many of the components that would be tested by an internal MIT are 

removed or tested during the plugging process. 

Response: EPA agrees that only an external MIT is required, and has modified the GS rule at

§146.92(a) to require owners or operators to perform a final external mechanical integrity test prior

to the well plugging.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24201
Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language 

Comment: Rule Provision: 146.92(b)(5) 

API Comments: (5) The type and grade and quantity of material to be used in 

plugging. The material must be SUITABLE FOR USE with the carbon dioxide stream; 

and 

No rationale provided 

Response: EPA believes, considering the potentially corrosive nature of CO2 when it is in contact

with water, that the requirement that the material must be compatible with the CO2 stream is

appropriate. The final rule retains this requirement.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24202

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: Rule Provision: 146.92(d) 

API Comments: (d) Plugging report. Within 60 days after plugging the owner or 

operator must submit a plugging report to the Director. If the semi-annual 

report is due less than 15 days after completion of plugging, then the report 

must be submitted within 60 days after plugging. The report must be certified 

as accurate by the owner or operator and by the person who performed the 

plugging operation (if other than the owner or operator.) 

Rationale: The proposed changes are suggested to simplify and clarify a 

provision that API believes is needlessly complicated. 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads,

"Within 60 days after plugging, the owner or operator must submit a plugging report to the

Director."

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23839

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

permit applications (seeking comment) 

Comment: A. WELL PLUGGING PLAN 

EPA's Proposed Rule would require owners and operators to develop a well 

plugging plan to be approved by the Director as part of each permit application. 

Such a plan would include: (1) a determination of bottom-hole reservoir 

pressure; (2) the identification of type and numbers of plugs to be used; (3) 

the placement of each plug; (4) testing methods to ensure mechanical integrity 

testing ("MIT"); (5) the method of plug placement; and (6) the type, grade and 

quantity of material to be used in plugging. By not mandating specific types, 

materials, or testing methods, EPA is giving applicants broad flexibility to 
accommodate the varying types of GS projects contemplated by this rulemaking. 

The CCS Alliance agrees with this approach. Such flexibility also accounts for 

the fact that supercritical CO2 has different properties than current injectants 

under the UIC program and, therefore. may require different plugging methods and 

materials. For instance, cement plugs can degrade over time from the build up of 

carbonic acid, which forms when CO2 is injected in subsurface formations 

containing brine. However. well integrity should be considered the function of 

well materials collectively in maintaining a fluid barrier (as opposed to 

individual components susceptibility, particularly from laboratory tests). 

Response: EPA agrees with commenters that a flexible approach is appropriate for GS wells. The

GS rule does not prescribe the specific cements to be used to plug injection wells because industry

standards, such as those developed by API or ASTM International, reflect the current state of the

science and the expertise of industrial users on CO2-compatible materials, as specified in

§146.92(b). Providing flexibility to choose materials for plugging, provided they are compatible with

the injected fluid, is consistent with requirements for other injection well classes and will allow

operators to utilize improved well technologies as they become available in the future without a need

to amend the regulation.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23747

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

language 

Comment: Part 146.92(b) As previously stated AWWA believes that potential changes in the 

size of the area of review require that all site plans be reevaluated at the 

same frequency as the area of review. Therefore, AWWA recommends revising this 

part to read: 

Well Plugging Plan. The owner or operator of a Class VI well must prepare, 

maintain, and comply with a plan that is acceptable to the Director. The plan 

must be reviewed and revised by the owner or operator, and submitted to the 

Director for approval, at the same frequency and time as the AOR reevaluation. 

The requirement to maintain and implement an approved plan is directly 

enforceable regardless of whether the requirement is a condition of the permit. 

The well plugging plan must be submitted as part of the permit application and 

must include the following information: 

Response: EPA agrees that developing, maintaining, and implementing an injection well plugging

plan is important to assuring that GS wells are plugged in a manner that will ensure that the well will

not serve as a conduit for CO2 leakage preventing endangerment of USDWs. 

EPA disagrees with the suggested change, however. The final rule requirement at §146.92(c) for the

owner or operator to notify the Director of any changes to the injection well plugging plan at least 60

days before plugging the well will allow the owner or operator (through communication with the

Director) to address any issues associated with the initial well plugging plan submitted with the

permit application. EPA is not requiring formal periodic review and updates to the injection well

plugging plan throughout the injection phase. EPA does not expect that changes to this plan would

be implemented until injection operations cease. EPA envisions that owners or operators will take

into account similar considerations that guide updates to other project plans, e.g., monitoring and
operational data and results of AoR reevaluations.

EPA clarifies that the owner or operator's injection well plugging plan will be incorporated as a

condition of their UIC permit and is therefore enforceable; failure to follow the approved plan would

be considered a violation of the permit and would be subject to applicable civil, criminal, or

administrative penalties under §1423 of the SDWA. 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24371

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

language 

Comment: Part 146.92(b)(5) AWWA recommends revising this part to read: 

The type and grade and quantity of material to be used in plugging. The material 

must be compatible with the carbon dioxide stream and pre-injection formation 

conditions; and 

Response: EPA believes, considering the potentially corrosive nature of CO2 when it is in contact

with water, that the requirement that the material must be compatible with the CO2 stream is

appropriate. The final rule retains this requirement.

Commenter Name: Wendy Jacobs Letter ID: 0183

Commenter Organization: Harvard Law School Environmental Law and Policy

Center

Comment ID:

25143

Comment: B. EPA Should Impose More Specific Well Plugging Standards 

In the preamble, EPA states that the proposed regulation will ensure that

injection wells are plugged at the end of an injection project so that the wells

will not serve as conduits for CO2 movement into USDWs. See 73 Fed. Reg. at

43,499, 43,518. If an improperly plugged well allows CO2 to escape into the

atmosphere, the climate change mitigation purpose underlying Class VI wells is

undermined. See id. at 43,492 (discussing how improper well plugging of an

abandoned oil exploration well allows a geyser of CO2 and water to erupt

periodically from the well, releasing 12,000 gigatons per year of CO2 into the

atmosphere). The proposed regulation, however, does not provide enough

meaningful guidance for owners/operators regarding how to "plug wells in a

manner that does not endanger USDWs." Id. at 43,518. Owners/operators are

directed simply to "prepare, maintain, and comply with a [well plugging] plan

that is acceptable to the Director." Id. at 43,540 (proposed 40 C.F.R. §

146.92(b)). EPA neglects to specify "the types of materials or tests that must

be used during well plugging because there are a variety of methods that are

appropriate and new materials and tests may become available in the future."

Id. at 43,518. Its general outline for the well plugging plan is intended "to

give owners or operators flexibility in . . . choos[ing] from available

materials and tests to carry out the proposed requirements." Id. Allowing

flexibility is certainly important. It does not, however, preclude EPA from

providing specific performance requirements, preferred methods, or a nonexhaustive list of approved materials and techniques.
EPA’s existing regulations for other UIC wells and surface impoundments and

landfills under the Resource Conservation and Recovery Act, 42 U.S.C. § 6901,

et. seq., ("RCRA"), provide good models in this regard. The existing

regulations for Class I, II, and III wells require plugging in a manner to

"prevent the movement of fluids" into a USDW. 40 C.F.R.

§ 146.10(a)(1). In addition, the existing regulation lists three accepted

plugging techniques. 40 C.F.R. § 146.10(a)(2)(i)-(iii)). It builds in

flexibility by allowing the Director to approve plugging techniques outside of

the enumerated categories if the technique will "reliably provide a comparable

level of protection to USDWs." 40 C.F.R. § 146.10(a)(2)(iv); see also 40 C.F.R.

§§ 264.228(a)(2)(iii)(A)-(E), 264.310(a)(1)-(5) (plugging requirements for

surface impoundments and landfills, respectively, which include specific targets

to be met (permeability) as well as general performance goals (minimum

maintenance and migration)).

By specifying a baseline of plugging techniques that EPA already knows will work

for GS, EPA would provide valuable GS-specific guidance to owners/operators (and

Directors). This may be especially valuable in this early stage of development

for GS technology as it will give all involved parties a brighter line by which

to measure compliance. Additionally, existing regulations demonstrate that more

specificity need not, as EPA suggests in the preamble to the proposed regulation

(73 Fed. Reg. at 43,518), constrain the use of future technologies. The

proposed regulations can preserve flexibility by vesting the Director with the

authority to consider and approve new plugging techniques. Accordingly, EPA

should revise the proposed Class VI UIC program regulation to include a list of

specific materials and tests that it deems suitable for plugging GS wells, in

addition to providing the Director with the discretion to approve new techniques

as they become available, provided they will perform at least as well.

Response: EPA believes that the required information required to be included in the injection well

plugging plan, as specified in §146.92(b), provides a framework for acceptable well plugging

procedures. EPA clarifies that the injection well plugging plan must include the following

information: (1) appropriate test or measure to determine bottomhole reservoir pressure; (2)

appropriate testing methods to ensure mechanical integrity as specified in §146.89; (3) the type and

number of plugs to be used; (4) the placement of each plug including the elevation of the top and

bottom of each plug; (5) the type and grade and quantity of material to be used in plugging (the

material must be compatible with the CO2 stream); and (6) the method of placement of the plugs.

EPA believes that these requirements in conjunction with Agency technical guidance provide

sufficient information to the owner or operator and the Director to allow for the development of a

well plugging plan and will help ensure protection of USDWs from endangerment.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans required under §146.92 and §146.93. The guidance describes recommended approaches

for how an owner or operator could plug injection and monitoring wells; perform post-injection

monitoring; demonstrate non-endangerment; and perform site closure activities. The guidance will

be available at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 
Commenter Name: Daniel Plath Letter ID: 0188

Commenter Organization: NiSource, Inc. Comment ID: 25229

Other EPA Comment Codes and Descriptions: 1610 1.3.1 Risks to USDWs; 3400 2.2.2 Corrective

Action; 3800 2.3 Proposed Injection Well Construction Requirements (40 CFR 146.86) 

Comment: aspects. The following points summarize four primary lessons learned through 

operation of natural gas storage that would be applicable to GS: 

1. History has shown that the one component in the system that has caused the 

most safety issues is the wells; specifically the operator's wells, plugged and 

abandoned (P&A) wells and third party operating wells (e.g. oil and gas 

production wells). The casing and cement in the storage well is the "first line 

of defense" in the containment of high pressure gas and a properly designed, 

constructed and maintained well is critical. Even after several decades of 

operations over a four State area, NiSource subsidiaries have never experienced 

loss of containment from cap rock leakage, migration up faults, re-activation of 

faults, earthquakes, or the other potential leakage pathways that EPA discusses 

in the Proposed Rule. While history will ultimately reveal the root causes of 

future problems, if any, with GS, NiSource submits that the predominant cause 

will likely be identified as being related to an active well, abandoned well or 

third party well if not properly addressed in the Final Rule. This is based on 

the belief that the rigorous site selection process will preclude the other 

sites that would have had other issues, e.g. cap rock leakage, from even being 

activated in the first place. 

Response: EPA agrees that proper site characterization should minimize leakage through faults,

breaks in the seal of the confining layer, and other geologic pathways. EPA believes that the

construction, operating, and monitoring requirements in the GS rule will prevent leakage from

occurring through active wells. 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 also agrees that the AoR and corrective action process should identify both abandoned wells

and third party wells that could serve as leakage pathways. The UIC Program's long-standing

approach to corrective action, tailored to the potential corrosivity of and impurities in the CO2

stream, can address the potential risk associated with improperly plugged wells in the AoR.

EPA notes that the final rule, at 40 CFR §124.10(c)(1)(xi), requires the notification of state oil and

gas agencies, state mineral exploration agencies, and state public water supply supervision directors

about the availability of the draft permit . EPA expects that such notification can help with further

identifying wells in the area of review.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24490

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

language 

Comment: Rule Provision: 146.92(a) 
Proposed CCS Group Recommendations: (a) Prior to the well plugging, the owner or 

operator must flush each Class VI injection well with a buffer fluid, determine 

bottomhole reservoir pressure, and perform a final EXTERNAL mechanical integrity 

test OF ANY RELEVANT WELLBORE MATERIALS REMAINING. 

Basis for CCS Group Comments: Many of the components that would be tested by an 

internal MIT are removed or tested during the plugging process. 

Rule Provision: 146.92(b) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Rule Provision: 146.192(b)(2) & (5) 

Proposed CCS Group Recommendations: (2) Appropriate testing methods to ensure 

FINAL EXTERNAL mechanical integrity as specified in §146.89(C); ... 

(5) The type and grade and quantity of material to be used in plugging. The 

material must be SUITABLE FOR USE with the carbon dioxide stream; and 

Basis for CCS Group Comments: Many of the components that would be tested by an 

internal MIT are removed or tested during the plugging process. 

Response: Regarding the suggested edit at 146.92(b)(2), EPA agrees that only an external MIT is

required, and has modified the GS rule at §146.92(a) and 146.92(b) to require owners or operators to

perform a final external mechanical integrity test prior to the well plugging. 

Regarding the edit at 146.92(b)(5), EPA believes, considering the potentially corrosive nature of

CO2 when it is in contact with water, that the requirement that the material must be compatible with

the CO2 stream is appropriate. The final rule retains this requirement.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24491

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: Rule Provision: 146.92(c) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support and the final rule retains this approach.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24492

Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule
language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: Rule Provision: 146.92(d) 

Proposed CCS Group Recommendations: (d) Plugging report. Within 60 days after 

plugging the owner or operator must submit a plugging report to the Director. 

If the semi-annual report is due less than 15 days after completion of 

plugging, then the report must be submitted within 60 days after plugging. The 

report must be certified as accurate by the owner or operator and by the person 

who performed the plugging operation (if other than the owner or operator.) 

Basis for CCS Group Comments: The proposed change will simplify and clarify a 

provision that is unnecessarily complicated. 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads,

"Within 60 days after plugging the owner or operator must submit a plugging report to the Director."

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24713

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

language 

Comment: Rule Provision: 146.92(a) 

Anadarko Petroleum Corporation (APC) Comments: (a) Prior to the well plugging, 

the owner or operator must flush each Class VI injection well with a buffer 

fluid, determine bottomhole reservoir pressure, and perform a final EXTERNAL 

mechanical integrity test OF ANY RELEVANT WELLBORE MATERIALS REMAINING. 

Rationale: Many of the components that would be tested by an internal MIT are 

removed or tested during the plugging process. 

Response: EPA agrees that only an external MIT is required, and has modified the GS rule at

§146.92(a) to require owners or operators to perform a final external mechanical integrity test prior

to the well plugging.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24714

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

language 

Comment: Rule Provision: 146.92(b)(2) 

Anadarko Petroleum Corporation (APC) Comments: (2) Appropriate testing methods 

to ensure FINAL EXTERNAL mechanical integrity as specified in §146.89(C); ... 

(5) The type and grade and quantity of material to be used in plugging. The 

material must be SUITABLE FOR USE with the carbon dioxide stream; and 

Rationale: Many of the components that would be tested by an internal MIT are 

removed or tested during the plugging process. 
Response: Regarding the suggested edit at 146.92(b)(2), EPA agrees that only an external MIT is

required, and has modified the GS rule at §146.92(a) to require owners or operators to perform a

final external mechanical integrity test prior to the well plugging. 

Regarding the edit at 146.92(b)(5), EPA believes, considering the potentially corrosive nature of

CO2 when it is in contact with water, that the requirement that the material must be compatible with

the CO2 stream is appropriate. The final rule retains this requirement.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24715

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: Rule Provision: 146.92(d) 

Anadarko Petroleum Corporation (APC) Comments: (d) Plugging report. Within 60 

days after plugging the owner or operator must submit a plugging report to the 

Director. If the semi-annual report is due less than 15 days after completion 

of plugging, then the report must be submitted within 60 days after plugging.

The report must be certified as accurate by the owner or operator and by the 

person who performed the plugging operation (if other than the owner or 

operator.) 

Rationale: The proposed changes are suggested to simplify and clarify a 

provision that APC believes is needlessly complicated. 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads,

"Within 60 days after plugging the owner or operator must submit a plugging report to the Director."

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24312

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

language 

Comment: H. § 146.92 Injection well plugging. 

1. EPA Proposed §146.92 (b) Well Plugging Plan. (5) The type and grade 

and quantity of material to be used in plugging. The material must be 

compatible with the carbon dioxide stream; 

The proposed regulation requires the wellbore to be flushed prior to plugging 

and thus it is unnecessary to use cement "compatible with the carbon dioxide 

stream." In the absence of water, CO2 is non-corrosive and compatible with 

conventional cements (see discussion under Comment #G). Accordingly, the rule 

should be revised as follows: 

§146.92 (b) Well Plugging Plan. (5) The type and grade and quantity of 

material to be used in plugging. The material must be compatible with 

the carbon dioxide stream;
Response: EPA believes, considering the potentially corrosive nature of CO2 when it is in contact

with water, that the requirement that the material must be compatible with the CO2 stream is

appropriate. The final rule retains this requirement because CO2 and water will be present in the

subsurface.

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23992

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

language 

Comment: 9. § 146.92 Injection well plugging. 

EPA Proposed §146.92 (b) Well Plugging Plan. (5) The type and grade and 

quantity of material to be used in plugging. The material must be 

compatible with the carbon dioxide stream; 

The proposed regulation requires the wellbore to be flushed prior to plugging 

and thus it is unnecessary to use cement "compatible with the carbon dioxide 

stream". In the absence of water, CO2 is non-corrosive and compatible with 

conventional cements (see discussion under Comment #7). Accordingly, the rule 

should be revised as follows: 

§146.92 (b) Well Plugging Plan. (5) The type and grade and quantity of 

material to be used in plugging. The material must be compatible with 

the carbon dioxide stream;

Response: EPA believes, considering the potentially corrosive nature of CO2 when it is in contact

with water, that the requirement that the material must be compatible with the CO2 stream is

appropriate. The final rule retains this requirement because CO2 and water will be present in the

subsurface.

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24027

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

language; 3400 2.2.2 Corrective Action 

Comment: Proposed Rule: (3) Determine which abandoned wells in the area of review have 

been plugged (as required by §146.92) in a manner that prevents the movement of 

carbon dioxide or associated fluids that may endanger USDWs. 

Schlumberger Suggested Revision: (3) Determine which abandoned wells identified 

in 146.84 (c) (2) have been plugged (as required by §146.92) in a manner that 

prevents the movement of carbon dioxide or formation fluids that may endanger 

USDWs. 

Schlumberger Rationale: - 

Response: EPA acknowledges the comment. Based on its evaluation of all public comments and

input on the proposed rule and NODA and Request for Comment, EPA has made many revisions to
the GS Rule. See the final rule and preamble for further discussion on EPA's final approach.

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24067

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

language 

Comment: §146.92 Injection well plugging. 

Proposed Rule: (a) Prior to the well plugging, the owner or operator must flush 

each Class VI injection well with a buffer fluid, determine bottomhole reservoir 

pressure, and perform a final mechanical integrity test. 

Schlumberger Suggested Revision: (a) Prior to the well plugging, the owner or 

operator must flush each Class VI injection well with a buffer fluid, determine 

bottomhole reservoir pressure, and perform a final external mechanical integrity 

test. 

Schlumberger Rationale: Many of the components that would be tested by an 

internal MIT are removed or tested during the plugging process. 

Response: EPA agrees that only an external MIT is required, and has modified the GS rule at

§146.92(a) to require owners or operators to perform a final external mechanical integrity test prior

to the well plugging.

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24068

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

language 

Comment: Proposed Rule: (2) Appropriate testing methods to ensure mechanical integrity as 

specified in §146.89; 

Schlumberger Suggested Revision: (2) Appropriate testing methods to ensure final 

external mechanical integrity as specified in §146.89(c); 

Schlumberger Rationale: Many of the components that would be tested by an 

internal MIT are removed or tested during the plugging process. 

Response: EPA agrees that only an external MIT is required, and has modified the GS rule at

§146.92(a) to require owners or operators to perform a final external mechanical integrity test prior

to the well plugging.

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24069

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

language 

Comment: Proposed Rule: (5) The type and grade and quantity of material to be used in 

plugging. The material must be compatible with the carbon dioxide stream; and 
Schlumberger Suggested Revision: (5) The type and grade and quantity of material 

to be used in plugging. The material must be suitable for use with the carbon 

dioxide stream; and 

Schlumberger Rationale: - 

Response: EPA believes, considering the potentially corrosive nature of CO2 when it is in contact

with water, that the requirement that the material must be compatible with the CO2 stream is

appropriate. The final rule retains this requirement.

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24070

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

language 

Comment: Proposed Rule: (d) Plugging report. Within 60 days after plugging or at the time 

of the next semi-annual report (whichever occurs earlier) the owner or operator 

must submit a plugging report to the Director. If the semi-annual report is due 

less than 15 days after completion of plugging, then the report must be 

submitted within 60 days after plugging. The report must be certified as 

accurate by the owner or operator and by the person who performed the plugging 

operation (if other than the owner or operator.) 

Schlumberger Suggested Revision: (d) Plugging report. Within 60 days after 

plugging the owner or operator must submit a plugging report to the Director. 

The report must be certified as accurate by the owner or operator and by the 

person who performed the plugging operation (if other than the owner or 

operator.) 

Schlumberger Rationale: Simplification 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads,

"Within 60 days after plugging the owner or operator must submit a plugging report to the Director."

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23305

Comment: 146.92(d) Simplify. Plugging reports should be required within a consistent 

time frame. 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads,

"Within 60 days after plugging the owner or operator must submit a plugging report to the Director."

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22311

Comment: Perhaps inadvertently, the proposed rule does not explicitly require updating of 

several of the required plans. In most but not all cases, there is a rather 

ambiguous requirement to "maintain" a given plan. Explicit requirements to make 

updates as warranted appear to be missing from provisions relating to: 
• the plugging plan required by §146.92 (again the ambiguous word "maintain" is 

used); 

Response: EPA believes that developing and implementing an injection well plugging plan is

important to assuring that GS wells are plugged in a manner that will ensure that the well will not

serve as a conduit for CO2 leakage, preventing endangerment of USDWs. 

EPA disagrees that explicit requirements to make updates to the injection plugging plan is necessary.

The final rule at §146.92(c) requires the owner or operator to notify the Director of any changes to

the injection well plugging plan at least 60 days before plugging the well. This will allow the owner

or operator (through communication with the Director) to address any issues associated with the

initial well plugging plan submitted with the permit application and will require the owner or

operator to maintain the plugging plan in order to communicate such changes. EPA is not requiring

formal periodic review and updates to the injection well plugging plan throughout the injection

phase. EPA does not expect that changes to this plan would be implemented until injection

operations cease.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24935

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

language 

Comment: Rule Provision: 146.92 

EPA Proposal: 12. Injection well plugging. 

(a) Prior to the well plugging, the owner or operator must flush each Class VI 

injection well with a buffer fluid, determine bottomhole reservoir pressure, and 

perform a final mechanical integrity test. 

GWPC Recommendations: (a) Prior to the well plugging, the owner or operator must 

flush each Class VI injection well with a buffer fluid, determine bottomhole 

reservoir pressure, and perform a final external mechanical integrity test. 

Rationale: Many of the components that would be tested by an internal MIT are 

removed or tested during the plugging process. Consequently, the GWPC suggests 

including the term internal to the language for clarification. 

Response: EPA agrees that only an external MIT is required, and has modified the GS rule at

§146.92(a) to require owners or operators to perform a final external mechanical integrity test prior

to the well plugging.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24936

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

language 

Comment: Rule Provision: 146.92(b) 

EPA Proposal: (b) Well Plugging Plan. The owner or operator of a Class VI well 
must prepare, maintain, and comply with a plan that is acceptable to the 

Director. The requirement to maintain and implement an approved plan is 

directly enforceable regardless of whether the requirement is a condition of the 

permit. The well plugging plan must be submitted as part of the permit 

application and must include the following information: 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24937

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

language 

Comment: EPA Proposal: (1) Appropriate test or measure to determine bottomhole reservoir 

pressure; 

(2) Appropriate testing methods to ensure mechanical integrity as specified in § 

146.89; 

(3) The type and number of plugs to be used; 

(4) The placement of each plug including the elevation of the top and bottom of 

each plug; 

(5) The type and grade and quantity of material to be used in plugging. The 

material must be compatible with the carbon dioxide stream; and 

(6) The method of placement of the plugs. 

GWPC Recommendations: Support the proposed EPA language for (1), (3), (4) and 

(6) 

(2) Appropriate testing methods to ensure final external mechanical integrity as 

specified in §146.89(c); 

(5) The type and grade and quantity of material to be used in plugging. The 

material must be suitable for use with the carbon dioxide stream; and 

Rationale: Many of the components that would be tested by an internal MIT are 

removed or tested during the plugging process. Consequently, the GWPC suggests 

adding the term external to the language for clarification. 

Response: Regarding the suggested edit at 146.92(b)(2), EPA agrees that only an external MIT is

required, and has modified the GS rule at §146.92(a) to require owners or operators to perform a

final external mechanical integrity test prior to the well plugging. 

Regarding the edit at 146.92(b)(5), EPA believes, considering the potentially corrosive nature of

CO2 when it is in contact with water, that the requirement that the material must be compatible with

the CO2 stream is appropriate. The final rule retains this requirement.
Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24938

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: EPA Proposal: (c) Notice of intent to plug. The owner or operator must notify 

the Director at least 60 days before plugging of a well. At this time, if any 

changes have been made to the original well plugging plan, the owner or operator 

must also provide the revised well plugging plan. At the discretion of the 

Director, a shorter notice period may be allowed. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24939

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: Rule Provision: 146.92(d) 

EPA Proposal: (d) Plugging report. Within 60 days after plugging or at the time 

of the next semi-annual report (whichever occurs earlier) the owner or operator 

must submit a plugging report to the Director. If the semi-annual report is due 

less than 15 days after completion of plugging, then the report must be 

submitted within 60 days after plugging. The report must be certified as 

accurate by the owner or operator and by the person who performed the plugging 

operation (if other than the owner or operator.) 

GWPC Recommendations: (d) Plugging report. Within 60 days after plugging the 

owner or operator must submit a plugging report to the Director. The report 

must be certified as accurate by the owner or operator and by the person who 

performed the plugging operation (if other than the owner or operator.) 

Rationale: Simplification 

Response: EPA has revised the text at §146.92(d) to reduce confusion. The final rule text reads,

"Within 60 days after plugging the owner or operator must submit a plugging report to the Director."

Commenter Name: Donn Miller Letter ID: 0270

Commenter Organization: State of Oregon, Water Resources Department Comment ID: 22890

Comment: 146.92 Injection Well Plugging. 

The rules describe plugs as a way to abandon class VI wells. 

In order to ensure that these wells are properly abandoned and that they don't 

become a health hazard or a health threat in the future the abandonment of class VI 
wells should consist of completely filling them from the bottom up to land surface 

with an approved sealant (i.e. cement). This assumes that the well was properly 

constructed in the first place. If the well wasn't constructed properly in the 

first place then another abandonment method maybe necessary to properly protect 

the groundwater resource. 

Response: EPA requires that, to protect USDWs from endangerment, injection wells must be

plugged in a manner to ensure that the well will not serve as a conduit for future fluid movement into

USDWs. This may be accomplished in a number of ways using a number of different types of

materials. In the case of GS wells, the plugging materials must be compatible with CO2.

EPA disagrees that Class VI wells need to be completely filled from the bottom of the well to the

land surface with an approved cement in order to protect USDWs from endangerment. Most experts

agree that a series of plugs separated by adequate well bore fluid (e.g., drilling mud) is considered to

be adequate protection, and that the time and expense of continuous cementing may not be practical

or necessary to prevent fluid migration and in some cases, other methods are equally protective.

(Source: Technical Assistance Document: Cementing for the Plugging and Abandonment of

Injection Wells, 1989) The Class VI well plugging requirements at §146.92 are very similar to those

for Class I wells, with additional considerations that the materials used are compatible with CO2. 

EPA adds that the Director must approve the owner or operator's injection well plugging plan.

Additionally, while EPA believes the requirements for well plugging are adequately protective of

USDWs, if there is reason to believe that completely filling the well is necessary to protect USDWs

from endangerment, nothing in the federal regulation precludes this. 

Comment Code: 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Individual Comments

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24795

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

language 

Comment: (e) A demonstration of external mechanical integrity pursuant to §146.89(c) at 

least once per year throughout the duration of INJECTION the geologic 

sequestration project;

{Demonstration of external mechanical integrity should not be necessary after 

cessation of injection and (relatively immediate) dissipation of pressure near 

the wellbore resulting from injection.} 

Response: In the final rule, EPA has revised the text at §144.90(e) to specify that owners or

operators must demonstrate internal MI at least once per year until the well is plugged.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24799

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

Comment: (i) The pressure differential between pre-injection and predicted post-injection 

pressures in the injection zone; (ii) The predicted position of the carbon 

dioxide plume and associated pressure front at site closure as demonstrated in 

the AOR evaluation required under §146.84(b); (iii) A description of postinjection monitoring location, methods, and proposed frequency; and (iv) A 

proposed schedule for submitting post-injection site care monitoring results to 

the Director. 

{This should be referenced in 146.82(w).} 

Response: EPA clarifies that the reference to the post-injection site care and site closure plan, in the

final rule at §146.82(a)(17), is to require that the plan be included in the attachments to the Class VI

permit application. The details of the plan contents are included in §146.93 and are enforceable

permit conditions, along with other requirements related to post-injection site care and site closure.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24800

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

language 

Comment: (3) Upon cessation of injection, THE OWNER OR OPERATOR MUST either submit an

amended post-injection site care and site closure plan or demonstrate to the 

Director through monitoring data and modeling results that no amendment to the 

plan is needed. 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24801

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: (4) THE OWNER OR OPERATOR MAY May modify and resubmit the post-injection 

site care and site closure plan for the Director's approval within 30 days of 

such change. 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24806

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

language 

Comment: (d) After the Director has authorized site closure, THE OWNER OR OPERATOR must 

plug all monitoring wells in a manner which will not allow movement of injection 
or formation fluids that endangers a USDW. 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22564

Comment: Closure 

When all injection operations are finished the site will be closed and the post 

closure period will begin. At this juncture the injection wells will be plugged 

and abandoned. The plugging needs to be done such that the CO2 and formation 

fluids cannot use the wellbore as a conduit when it is complete. No wells 

should be abandoned until there has been a final round of measurements to verify 

the integrity of the well in case remedial action is needed prior to plugging. 

Wells plugged prior to the site closure phase should be plugged and abandoned 

following the same procedures as those in the closure phase. Any requirements 

need to ensure that all wells are properly plugged and abandoned using material 

and methods that will allow the well to remain safe and not become an avenue for 

leakage. 

Response: EPA agrees that Class VI injection wells must be plugged in a manner that protects

USDWs from endangerment, and believes that the final rule requirements address the commenter’s

concerns. EPA requires that, to protect human health as it relates to endangered USDWs, injection

wells be plugged in a manner to ensure that the well will not serve as a conduit for future fluid

movement into USDWs. In the case of GS wells, the plugging materials must be compatible with

CO2, as specified at 146.92(b). EPA clarifies that the final GS rule at 146.92(a) requires owners or

operators to perform a final external mechanical integrity test prior to the well plugging. These

requirements apply whether the well is plugged upon cessation of injection or at the time of site

closure.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24147

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

Comment: Rule Provision: 146.81(d) [Definition - Post-injection site care] 

API Comments: Post-injection site care means appropriate monitoring and 

other actions (including corrective action) needed following cessation of 

injection to assure that USDWs are not endangered, AS REQUIRED UNDER 

§146.93. 

Rationale: Deleted "appropriate" because the definition of it is not clear. 

Deleted USDW phrase because it is incorporated in 146 requirements. 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach. EPA adds that the owner or operator
must monitor as specified in the post-injection site care and site closure plan for at least 50 years or

for the duration of the alternative timeframe approved by the Director pursuant to requirements in

§146.93(c), unless the owner or operator can make a demonstration earlier that the geologic

sequestration project no longer poses a risk of endangerment to USDWs.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24149

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

Comment: Rule Provision: 146.81(d) [Definition - Site closure] 

API Comments: Site closure MEANS the point/time, as determined by the Director 

following the requirements under §146.93, at which the owner or operator of a GS 

site PROJECT is released from post-injection site care responsibilities. 

Rationale: "GS project" is consistent with other definitions. 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24204

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

language 

Comment: Rule Provision: 146.93(a)(2) 

API Comments: (2) The post-injection site care and site closure plan must 

include the following information: 

(i) The pressure differential between preinjection and predicted post-injection 

pressures in the injection zone; 

(ii) The predicted position of the carbon dioxide plume and associated pressure 

front at site closure as demonstrated in the area of review evaluation required 

under § 146.84(b); 

(iii) A description of post-injection monitoring location, methods, and proposed 

frequency; and 

(iv) A proposed schedule for submitting post-injection site care monitoring 

results to the Director.

Rationale: Revisions here reflect changes to §146.93(b)(3) 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24205

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 
Comment: Rule Provision: 146.93(a)(4) 

API Comments: (4) AT ANY TIME DURING THE POST-INJECTION SITE CARE PHASE, The 

owner or operator may modify and resubmit the post-injection site care and site 

closure plan for the Director‘s approval within 30 days of such change. 

Rationale: Technical Clarification. 

Response: EPA agrees that a post-injection site care monitoring plan is an important tool for GS,

and anticipates that, in some cases, the appropriate post-injection monitoring strategy may end up

being different than initially projected, and there may be a need to amend the post-injection site care

and site closure plan. EPA is requiring that upon the cessation of injection, the owner or operator

submit an amended post-injection site care and site closure plan or demonstrate to the Director that

no changes to the original post-injection site care and site closure plan are necessary (§146.93(a)(3)).

EPA is not requiring formal periodic review and updates to the PISC and site closure plan

throughout the injection phase. EPA does not expect that changes to this plan would be implemented

until injection operations cease. EPA envisions that owners or operators would take into account

similar considerations that guide updates to other project plans, e.g., monitoring and operational data

and results of AoR reevaluations. EPA adds that, if any monitoring or other site data indicate a need

for amending the post-injection site care plan, the owner or operator is expected to amend the plan

accordingly. 

EPA adds that, in the final rule, it has revised the text at §146.93(a)(4) as follows: "At any time

during the life of the geologic sequestration project, the owner or operator may modify and resubmit

the post-injection site care and site closure plan for the Director’s approval within 30 days of such

change."

EPA is issuing guidance on development and updating of the GS project plans, including the postinjection site care and site closure plan. The guidance will be available on EPA's web site, at

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

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24256

Comment: Rule Provisions: 146.93 

EPA Preamble Question: 39. EPA is requesting comments on the proposed 

requirements for well plugging, post-injection site care, and site closure, 

including the proposed requirements for the post-injection time period. EPA 

Notice 43520. 

API Response: See question 38 above regarding post closure time periods. 

Response: As described above, EPA acknowledges that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the final GS regulation includes a provision that the

Director may, at his/her discretion, shorten the post-injection site care timeframe if the owner or

operator can demonstrate that the GS project does not pose a risk to USDWs, as specified in

§146.93(b)(2). Such a demonstration will be site-specific, and based on pressure monitoring and

USDW impacts. Alternatively, the final rule at §146.93(c), also allows the Director to approve an

alternative post-injection site care timeframe where an owner or operator can demonstrate during the
permitting process that an alternative post-injection site care timeframe, other than the 50 year

default, is appropriate and ensures non-endangerment of USDWs. The demonstration must be based

on site-specific information, including the results of site-specific computational modeling; the

predicted timeframe for pressure decline; the predicted rate of carbon dioxide plume migration; sitespecific chemical processes that will result in carbon dioxide trapping; the predicted rate of carbon

dioxide trapping; characterization of the confining zone(s); laboratory analyses or studies to verify

the information on trapping; the presence of potential conduits for fluid movement and the quality of

abandoned well plugs within the AoR; the distance between the injection zone and the USDWs

above and/or below the injection zone; and any additional site-specific factors determined by the

Director. The demonstration must meet the criteria at §146.93(c)(2) for ensuring the quality and

accuracy of the data and models on which the demonstration is based. This demonstration would be

submitted as part of the permit application, per §146.82(a)(18), in addition to the PISC and site

closure plan required at §146.82(a)(17).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans required under §146.92 and §146.93. The guidance describes recommended approaches

for how an owner or operator could plug injection and monitoring wells, perform post-injection

monitoring, demonstrate the appropriateness of an alternative post-injection site care time frame,

demonstrate non-endangerment, and perform site closure activities. This guidance will be available

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

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23840

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

permit applications (seeking comment) 

Comment: B. POST-INJECTION SITE CARE PLAN 

The Proposed Rule would require that owners or operators develop a postinjection site care and closure plan, submitted as part of the permit 

application and approved by the Director. The proposed regulation at 40 C.F.R. $ 

146.93 would require the plan to describe: (1) the pressure differential between 

pre-injection and anticipated post-injection pressures in the injection zone; 

(2) predicted position of the plume and associated pressure front at the time 

the site is closed; (3) post-injection monitoring location(s), methods, and 

proposed frequency of monitoring; and (4) a schedule for submitting postinjection site care and monitoring results to the Director. 

These requirements are reasonable given the long-term nature of GS projects. The 

CCS Alliance also supports the ability to amend the plan should the plan no 

longer reflect what is likely to occur upon closing the site. Likewise, the CCS 
Alliance agrees that, upon permanent cessation of injection, the owner or 

operator should be provided the opportunity to demonstrate that no amendment to 

the plan is necessary through monitoring and modeling results. 

Response: EPA agrees that a post-injection site care monitoring plan is an important tool for GS,

and retains this requirement in the final rule, at 146.93(a). Regarding updates to the plan, EPA is

requiring that upon the cessation of injection, the owner or operator submit an amended postinjection site care and site closure plan or demonstrate to the Director that no changes to the original

post-injection site care and site closure plan are necessary, as specified in §146.93(a)(3). EPA is not

requiring formal periodic review and updates to the PISC and site closure plan throughout the

injection phase. EPA does not expect that changes to this plan would be implemented until injection

operations cease.

Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23642

Comment: (b)(3) 

What is the definition of a stable plume? Is it related to no detectable change 

with a given assessment technique; what technique(s) form the standard? If we 

were able to document that a plume is shrinking, say in a confined geologic 

structure, due to dissolution into brine and decrease in the supercritical CO2 

phase, is that plume unstable? 

Response: EPA acknowledges that many site-specific factors will influence the determination of

when the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for

this reason that EPA believes that individual UIC Directors, in consultation with operators, will be in

the best position to determine whether additional post-injection site care is needed. EPA expects this

decision to be made based on relevant site data and in consultation with all potentially impacted

parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that

a complete cessation of plume movement is not required, only a demonstration that the plume and

pressure front no longer pose a risk of endangerment to USDWs. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23700

Other EPA Comment Codes and Descriptions: 4610 2.6.1 Testing and monitoring plan

requirement (seeking comment) 

Comment: Category: Required Project Plans 
EPA Request for Comment: EPA seeks comment on the merits of requiring plans for 

monitoring, AoR, and post-injection site care as part of a permit application. 

EPA Notice 43517. 

AWWA Response: The requirement for the development of plans for monitoring, AoR, 

and post-injection site care is necessary and is a very important part of the 

permit process. The information will provide outside stakeholders with a much 

better idea of how the project will proceed and can help to assure them that the 

owner/operator has a clear vision for the life of the project. AWWA recommends 

that these plans be reviewed at the same time that the area of review is 

reevaluated. During this review, the plans should be updated based on any 

operational changes since the last project review period and submitted to the 

Director for approval. AWWA recommends that a review occur every year for the 

first ten years of the project, and then should be reviewed every five years 

until injection ceases. 

Response: EPA agrees with the commenter. Owners or operators are required to submit an AoR and

corrective action plan, a testing and monitoring plan, and a post-injection site care and site closure

plan as part of the permit application, as specified in §146.82(a), to outline how these activities will

be performed and how non-endangerment of USDWs will be demonstrated throughout the

operational and post-injection site care periods. EPA is developing guidance on how best to develop

the various required project plans, including the testing and monitoring plan. The guidance can be

found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

The GS rule also requires owners or operators to review and update the AoR and corrective action

plan and the testing and monitoring plan throughout the life of the project, as described at

§146.84(c) and §146.90(j). The rule requires at §146.90(j) that the operator revise the testing and

monitoring plan to incorporate the results of the most recent AoR reevaluation and recent

operational and monitoring data. Owners or operators must review each plan and identify necessary

amendments to the plan or demonstrate to the Director that no amendment is needed. These reviews

must be performed within one year of an AoR reevaluation, following any significant changes to the

facility (e.g., the addition of monitoring or injection wells), or when required by the Director. In no

case can reviews occur less often than once every five years. This review frequency is appropriate to

ensure that reviews of the plans are conducted on a defined schedule or when there is a change in the

AoR or significant change, while adding little burden if an AoR reevaluation confirms that the plans

are appropriate as written. See the preamble sections on the plans for additional information. 

EPA is not requiring formal periodic review and updates to the PISC and site closure plan

throughout the injection phase as with the AoR reevaluation that is required at least every 5 years.

EPA does not expect that changes to this plan would be implemented until injection operations

cease. EPA is requiring that upon the cessation of injection, the owner or operator submit an

amended post-injection site care and site closure plan or demonstrate to the Director that no changes

to the original post-injection site care and site closure plan are necessary, as specified in

§146.93(a)(3). EPA envisions that owners or operators would take into account similar

considerations that guide updates to other project plans, e.g., monitoring and operational data and

results of AoR reevaluations.

EPA has also added a new provision at §144.39(a)(5) identifying the basis for a modification,

revocation, or reissuance of a Class VI permit whenever the Director determines that a change in the
permit is necessary based on an amended AoR and corrective action plan, testing and monitoring

plan, injection well plugging plan, post-injection site care and site closure plan, or emergency and

remedial response plan is necessary.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23748

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

language 

Comment: Part 146.93(a) As previously stated AWWA believes that potential changes in the 

size of the area of review require that all site plans be reevaluated at the 

same frequency as the area of review. Therefore, AWWA recommends revising this 

part to read: 

The owner or operator of a Class VI well must prepare, maintain, and comply with 

a plan for post-injection site care and site closure that meets the requirements 

of paragraph (a)(2) of this section and is acceptable to the Director. The plan 

must be reviewed and revised by the owner or operator, and submitted to the 

Director for approval, at the same frequency and time as the AOR reevaluation. 

Response: As described above, the final rule requires review and revision of the post-injection and

site care closure plan when injection ceases, as described in §146.93(a)(3). EPA is not requiring

formal periodic review and updates to the PISC and site closure plan throughout the injection phase.

EPA does not expect that changes to this plan would be implemented until injection operations

cease. See the final rule and preamble for further discussion on EPA's final approach.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23750

Other EPA Comment Codes and Descriptions: 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Part 146.93(d) There may be cases where the Director would want some of the 

monitoring wells to remain in service after site closure. While this may not be 

the case for all projects, for some of the earlier sites, the Director may want 

to continue minimal monitoring to continue to verify that the plume 

characteristics have remained stable. 

Response: EPA clarifies that the owner or operator must conduct post-injection site care that is

consistent with the approved PISC plan or for the duration of the alternative timeframe approved by

the Director pursuant to requirements in §146.93(c), until a demonstration can be made to the

satisfaction of the Director that the plume and pressure front no longer pose a risk of endangerment

to USDWs. After this determination is made, site closure is approved and the post-injection site care

period would end, as specified in §146.93 (b)(1). 

If, however, there is reason to believe that additional minimal monitoring is necessary to verify that

the plume characteristics have remained stable, this would be considered post-injection site care

monitoring. If a reduction in monitoring frequency or methods is appropriate (i.e., an additional year

or so of verification of the non-endangerment demonstration), the Director has discretion to

authorize an amendment to the post-injection site care and site closure plan. This is consistent with

the requirements at §146.93(b)(2).
Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24407

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

Comment: Rule Provision: 146.81(d) [Definition - Post-injection site care] 

Proposed CCS Group Recommendations: Post-injection site care means 

appropriate monitoring and other actions (including corrective action) 

needed following cessation of injection to assure that USDWs are not 

endangered, AS REQUIRED UNDER §146.93. 

Basis for CCS Group Comments: Deleted "appropriate" because the definition of it 

is not clear. Deleted USDW phrase because it is incorporated in 146 

requirements. 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach. EPA adds that all post-injection site

care must be performed pursuant to the post-injection site care and site closure plan, which must be

approved by the Director and demonstrated to include monitoring activities that protect USDWs

from endangerment.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24409

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

Comment: Rule Provision: 146.81(d) [Definition - Site closure] 

Proposed CCS Group Recommendations: Site closure MEANS the point/time, as 

determined by the Director following the requirements under §146.93, at which 

the owner or operator of a GS site PROJECT is released from post-injection 

site care responsibilities. 

Basis for CCS Group Comments: "GS project" is consistent with other definitions. 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24494

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

language; 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Rule Provision: 146.93(a)(2) 

Proposed CCS Group Recommendations: (2) The post-injection site care and site 

closure plan must include the following information: 

(i) The pressure differential between pre-injection and predicted post-injection 

pressures in the injection zone; 
(ii) The predicted position of the carbon dioxide plume and associated pressure 

front at site closure as demonstrated in the area of review evaluation required 

under § 146.84(b); 

(iii) A description of post-injection monitoring location, methods, and proposed 

frequency; and 

(iv) A proposed schedule for submitting post-injection site care monitoring 

results to the Director.

Basis for CCS Group Comments: Revisions here reflect changes to §146.93(b)(3) 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24495

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

language 

Comment: Rule Provision: 146.93(a)(3) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA agrees that a post-injection site care monitoring plan is an important tool for GS and

anticipates that, in some cases, the appropriate post-injection monitoring strategy may end up being

different than initially projected and there may be a need to amend the post-injection site care and

site closure plan. EPA is requiring that, upon the cessation of injection, the owner or operator submit

an amended post-injection site care and site closure plan or demonstrate to the Director that no

changes to the original post-injection site care and site closure plan are necessary (146.93(a)(3)).

EPA is not requiring formal periodic review and updates to the PISC and site closure plan

throughout the injection phase.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24496

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: Rule Provision: 146.93(a)(4) 

Proposed CCS Group Recommendations: 4) AT ANY TIME DURING THE POST-INJECTION 

SITE CARE PHASE, The owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval within 30 

days of such change. 

Basis for CCS Group Comments: Technical Clarification. 
Response: EPA agrees that a post-injection site care monitoring plan is an important tool for GS and

anticipates that, in some cases, the appropriate post-injection monitoring strategy may end up being

different than initially projected and there may be a need to amend the post-injection site care and

site closure plan. EPA is requiring that upon the cessation of injection, the owner or operator submit

an amended post-injection site care and site closure plan or demonstrate to the Director that no

changes to the original post-injection site care and site closure plan are necessary (146.93(a)(3)).

EPA is not requiring formal periodic review and updates to the PISC and site closure plan

throughout the injection phase. EPA does not expect that changes to this plan would be implemented

until injection operations cease. EPA envisions that owners or operators would take into account

similar considerations that guide updates to other project plans, e.g., monitoring and operational data

and results of AoR reevaluations. EPA adds that, if any monitoring or other site data indicate a need

for amending the post-injection site care plan, the owner or operator is expected to amend the plan

accordingly under §146.93(a)(3). 

EPA adds that, in the final rule, it has revised the text at §146.93(a)(4) as follows: "At any time

during the life of the geologic sequestration project, the owner or operator may modify and resubmit

the post-injection site care and site closure plan for the Director’s approval within 30 days of such

change."

EPA is issuing guidance on development and updating of the GS project plans, including the postinjection site care and site closure plan. The guidance will be available on EPA's web site at

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

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24502

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

language 

Comment: Rule Provision: 146.93(d) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24548

Comment: Rule Provisions or Federal Register Cite: 146.93 

EPA Preamble Question: 39. EPA is requesting comments on the proposed 

requirements for well plugging, post-injection site care, and site closure, 

including the proposed requirements for the post-injection time period. EPA 

Notice 43520. 

CSC Response: See response to Question 38 above regarding post closure time 

periods. 

Response: As described above, EPA acknowledges that there will be circumstances where it can be
demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the final GS regulation includes a provision that the

Director may, at his/her discretion, shorten the post-injection site care time frame if the owner or

operator can demonstrate that the GS project does not pose a risk to USDWs, as specified in

§146.93(b)(2). Alternatively, the final rule at §146.93(c), also allows the Director to approve an

alternative post-injection site care timeframe where an owner or operator can demonstrate during the

permitting process that an alternative post-injection site care timeframe, other than the 50 year

default, is appropriate and ensures non-endangerment of USDWs. The demonstration must be based

on site-specific information, including the results of site-specific computational modeling; the

predicted timeframe for pressure decline; the predicted rate of carbon dioxide plume migration; sitespecific chemical processes that will result in carbon dioxide trapping; the predicted rate of carbon

dioxide trapping; characterization of the confining zone(s); laboratory analyses or studies to verify

the information on trapping; the presence of potential conduits for fluid movement and the quality of

abandoned well plugs within the AoR; the distance between the injection zone and the USDWs

above and/or below the injection zone; and any additional site-specific factors determined by the

Director. The demonstration must meet the criteria at §146.93(c)(2) for ensuring the quality and

accuracy of the data and models on which the demonstration is based. This demonstration would be

submitted as part of the permit application, per §146.82(a)(18), in addition to the PISC and site

closure plan required at §146.82(a)(17). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans required under §146.92 and §146.93. The guidance describes recommended approaches

for how an owner or operator could plug injection and monitoring wells, perform post-injection

monitoring, demonstrate the appropriateness of an alternative post-injection site care time frame,

demonstrate non-endangerment, and perform site closure activities. This guidance will be available

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

Commenter Name: Kyle Isakower Letter ID: 0191

Commenter Organization: American Petroleum Institute Comment ID: 23883

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

language 

Comment: We recommend the standard in the proposed alternative language for section 

146.93(b) below because it sets forth detailed criteria, all of which must be 

satisfied, to demonstrate that the site does not pose an endangerment to USDWs. 

The specific criteria listed in our proposal will serve to provide the Director 

with the requisite information to make the appropriate determination. The 

advantage of this approach is that it establishes clear criteria that an 

operator must demonstrate before obtaining site closure based upon particular 

site characteristics and is, therefore, reasonably applicable to any storage 

site as opposed to a standard based upon a fixed-duration. Furthermore, it is 
more stringent than a purely discretionary approach because it establishes 

specific criteria that must be shown before site closure may be granted. We 

believe this language, which is an extension of work done by the World Resources 

Institute and the Ground Water Protection Council, avoids the noted shortcomings 

and provides stronger protection for USDWs. 

146.93 (b) The owner or operator shall monitor the site following the 

cessation of injection. 

(1) The owner or operator shall continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site 

closure plan until closure is authorized pursuant to 146.93(b)(3). 

(2) The owner or operator can request and demonstrate to the 

satisfaction of the Director that the post-injection site care and site 

closure plan should be revised to reduce the frequency of monitoring. 

Response: EPA disagrees with the suggested edits, but believes that the provisions of the final GS

rule at §146.93(b) address the commenter’s suggestions. Specifically, the owner or operator must

monitor the site until it can be demonstrated that the CO2 plume and pressure front no longer pose a

risk of endangerment to USDWs and that monitoring must continue until the owner or operator

demonstrates, based on monitoring and other site-specific data, that no additional monitoring is

needed to ensure that the GS project does not pose a risk of endangerment to USDWs, as required at

§146.93(b)(3). See the final rule and preamble for further discussion on EPA's final approach.

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23904

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

language 

Comment: We recommend the standard in the proposed alternative language for section 

146.93(b) below because it sets forth detailed criteria, all of which must be 

satisfied, to demonstrate that the site does not pose an endangerment to USDWs. 

The specific criteria listed in our proposal will serve to provide the Director 

with the requisite information to make the appropriate determination. The 

advantage of this approach is that it establishes clear criteria that an 

operator must demonstrate before obtaining site closure based upon particular 

site characteristics and is, therefore, reasonably applicable to any storage 

site as opposed to a standard based upon a fixed duration. Furthermore, it is 

more stringent than a purely discretionary approach because it establishes 

specific criteria that must be presented before site closure may be granted. We 

believe this language, which is an extension of work done by the World Resources 

Institute and the Ground Water Protection Council, avoids the noted shortcomings 

and provides stronger protection for USDWs. 

146.93 (b) The owner or operator shall monitor the site following the 

cessation of injection. 

(1) The owner or operator shall continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site 
closure plan, until closure is authorized pursuant to 146.93(b)(3). 

(2) The owner or operator can request and demonstrate to the 

satisfaction of the Director that the post-injection site care and site 

closure plan should be revised to reduce the frequency of monitoring. 

Response: EPA disagrees with the suggested edits, but believes that the provisions of the final GS

rule at §146.93(b) address the commenter’s suggestions. Specifically, the owner or operator must

monitor the site until it can be demonstrated that the CO2 plume and pressure front no longer pose a

risk of endangerment to USDWs and that monitoring must continue until the owner or operator

demonstrates, based on monitoring and other site-specific data, that no additional monitoring is

needed to ensure that the GS project does not pose a risk of endangerment to USDWs, as required at

§146.93(b)(3). See the final rule and preamble for further discussion on EPA's final approach.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24609

Comment: Rule Provisions: 146.93 

EPA Rule Issue: 39. EPA is requesting comments on the proposed requirements for 

well plugging, postinjection site care, and site closure, including the proposed 

requirements for the post-injection time period. EPA Notice 43520. 

Anadarko Petroleum Corporation (APC) Response: It is inappropriate to utilize a 

fixed period as this does not provide the flexibility to address site-specific 

issues; instead EPA should adopt a standard that is based on a demonstration of 

non-endangerment to determine when monitoring is no longer needed. Please see 

response to EPA 43519. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the final GS regulation includes a provision that the

Director may, at his or her discretion, shorten the post-injection site care timeframe if the owner or

operator can demonstrate that the GS project does not pose an endangerment to USDWs, as

specified in §146.93(b)(2). Alternatively, the final rule at §146.93(c), also allows the Director to

approve an alternative post-injection site care timeframe where an owner or operator can

demonstrate during the permitting process that an alternative post-injection site care timeframe, other

than the 50 year default, is appropriate and ensures non-endangerment of USDWs. The

demonstration must be based on site-specific information, including the results of site-specific

computational modeling; the predicted timeframe for pressure decline; the predicted rate of carbon

dioxide plume migration; site-specific chemical processes that will result in carbon dioxide trapping;

the predicted rate of carbon dioxide trapping; characterization of the confining zone(s); laboratory

analyses or studies to verify the information on trapping; the presence of potential conduits for fluid

movement and the quality of abandoned well plugs within the AoR; the distance between the

injection zone and the USDWs above and/or below the injection zone; and any additional sitespecific factors determined by the Director. The demonstration must meet the criteria at

§146.93(c)(2) for ensuring the quality and accuracy of the data and models on which the

demonstration is based. This demonstration would be submitted as part of the permit application, per

§146.82(a)(18), in addition to the PISC and site closure plan required at §146.82(a)(17). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust
the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes, however, that to ensure USDW protection from endangerment, a default timeframe

for post-injection site care is necessary in most cases. A 50-year post-injection site care timeframe

represents a reasonable and protective monitoring period for most GS projects and available data,

including data submitted by commenters, do not support a different default timeframe. This

determination is based on a review of research studies, industry reports, existing environmental

programs, and evaluation of public comments.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24637

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

Comment: Rule Provision: 146.81(d) [Definition - Post-injection site care] 

Anadarko Petroleum Corporation (APC) Comments: Post-injection site care means 

appropriate monitoring and other actions (including corrective action) 

needed following cessation of injection to assure that USDWs are not 

endangered , as required under §146.93. 

Rationale: Deleted "appropriate" because the definition of it is not clear. 

Deleted USDW phrase because it is incorporated in 146 requirements. 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach. EPA adds that all post-injection site

care must be performed pursuant to the post-injection site care and site closure plan, which must be

approved by the Director and demonstrated to include monitoring activities that protect USDWs

from endangerment.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24639

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

Comment: Rule Provision: 146.81(d) [Definition - Site closure] 

Anadarko Petroleum Corporation (APC) Comments: Site closure MEANS the 

point/time, as determined by the Director following the requirements under 

§146.93, at which the owner or operator of a GS site PROJECT is released 

from post-injection site care responsibilities. 

Rationale: "GS project" is consistent with other definitions. 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach. 
Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24717

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

language 

Comment: Rule Provision: 146.93(a)(2) 

Anadarko Petroleum Corporation (APC) Comments: (2) The post-injection site 

care and site closure plan must include the following information: 

(i) The pressure differential between preinjection and predicted post-injection 

pressures in the injection zone; 

(ii) The predicted position of the carbon dioxide plume and associated pressure 

front at site closure as demonstrated in the area of review evaluation required 

under § 146.84(b); 

(iii) A description of post-injection monitoring location, methods, and proposed 

frequency; and 

(iv) A proposed schedule for submitting post-injection site care monitoring 

results to the Director.

Rationale: Revisions here reflect changes to §146.93(b)(3) 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24718

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: Rule Provision: 146.93(a)(4) 

Anadarko Petroleum Corporation (APC) Comments: (4) AT ANY TIME DURING THE POSTINJECTION SITE CARE PHASE, The owner or operator may modify and resubmit the 

post-injection site care and site closure plan for the Director’s approval 

within 30 days of such change. 

Rationale: Technical Clarification. 

Response: EPA agrees that a post-injection site care monitoring plan is an important tool for GS and

anticipates that, in some cases, the appropriate post-injection monitoring strategy may end up being

different than initially projected and there may be a need to amend the post-injection site care and

site closure plan. EPA is requiring that upon the cessation of injection, the owner or operator submit

an amended post-injection site care and site closure plan or demonstrate to the Director that no
changes to the original post-injection site care and site closure plan are necessary (146.93(a)(3)).

EPA is not requiring formal periodic review and updates to the PISC and site closure plan

throughout the injection phase. EPA does not expect that changes to this plan would be implemented

until injection operations cease. EPA envisions that owners or operators would take into account

similar considerations that guide updates to other project plans, e.g., monitoring and operational data

and results of AoR reevaluations. EPA adds that, if any monitoring or other site data indicate a need

for amending the post-injection site care plan, the owner or operator is expected to amend the plan

accordingly. EPA is issuing guidance with recommended approaches for development and updating

of the GS project plans, including the post-injection site care and site closure plan. The guidance will

be available on EPA's web site at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

EPA adds that, in the final rule, it has revised the text at §146.93(a)(4) as follows: "At any time

during the life of the geologic sequestration project, the owner or operator may modify and resubmit

the post-injection site care and site closure plan for the Director’s approval within 30 days of such

change."

Commenter Name: John King Letter ID: 0211

Commenter Organization: Shell Exploration and Production Company

(SEPCo)

Comment ID:

22782

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: G. Post-Injection Site Care Responsibility 

The proposed rule contemplates a long post-operational period of observation and 

"site care" prior to closure. The requirements contemplated -- including a 

presumptive 50-year post-injection monitoring period -- are unwarranted and 

completely unprecedented in the UIC program. Not even hazardous waste injection 

wells -- which generally operate subject to a demonstration that waste will be 

contained for at least ten thousand years -- are subject to such burdensome 

post-injection requirements. 

Long term protection of USDWs is ensured up-front, primarily through proper 

siting as confirmed through the technical evaluation that occurs in the 

permitting process. Proper well construction, operating, monitoring and testing 

provide assurance against problems during the operational life of an injection 

well, but siting doesn’t change, and proper siting must be ensured at the start. 

Once injection operations cease, there should generally be no need to do more 

than monitor pressure decay in the injection zone and ensure proper plugging of 

the injection well. This approach is sufficient for the injection of hazardous 

waste, and it certainly should be sufficient for the injection of CO2. The 

premise that careful siting and AOR evaluation are not enough -- that actual 

monitoring for decades after the cessation of injection is needed -- is foreign 

to the UIC program and inconsistent with the long and thoroughly-documented 

success of UIC regulation in the United States. 

There is certainly no justification for a presumptive 50-year minimum timeframe 

for post-injection site care, and such a requirement would likely kill-off 

commercial investment in geo-sequestration projects. It does not help that the 

proposed rule provides a mechanism for shortening the presumptive 50-year 
requirement, because the ability to shorten the post-injection site care period 

would depend on the apparently unlimited discretion of the Director and could 

not be assessed in any meaningful way before injection operations near 

completion. Moreover, the possibility of a shorter post-injection site care 

period is balanced by the possibility that the Director may seek to impose an 

even longer post-injection site care period. The burdens and regulatory 

uncertainties of an extended post-injection site care requirement cannot be 

justified, especially in the context of a regulatory program that requires a 

"non-endangerment" demonstration before injection can even commence. 

Recommendation: 

1. EPA should operate from the premise that the UIC program is preventive in 

nature. 

2. Release from post-injection site care should be determined not by a fixed 

period of time but rather a performance-based standard that is designed to 

ensure protection of USDW’s. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care is necessary in most cases. A 50 year post-injection site care timeframe

represents a reasonable and protective monitoring period for most GS projects and available data,

including data submitted by commenters, do not support a different default timeframe. This

determination is based on a review of research studies, industry reports, and existing environmental

programs, and evaluation of public comments.

EPA agrees that proper site characterization, well construction, and operation are important

components of ensuring that USDWs are protected. However, EPA disagrees that this is a substitute

for post-injection site care. EPA believes that extensive post-injection monitoring is necessary to

protect USDWs from endangerment. 

EPA disagrees that the rule affords ¿unlimited discretion¿ to the Director to lengthen the postinjection site care timeframe. Because of the variety of site-specific circumstances at GS sites, EPA

believes that Directors, in consultation with operators, will be in the best position to determine

whether additional post-injection site care monitoring is needed (or whether the timeframe may be

shortened), based on the circumstances of a particular project. EPA expects this decision to be made

based on relevant site data, including information at §146.93(c)(2), to determine the appropriateness

of an alternative post-injection site care time frame if applicable, and in consultation with all

potentially impacted parties.

EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most Class VI
wells. EPA proposed a default post-injection site care timeframe of 50 years based on a review of

research studies, industry reports, and existing environmental programs. This analysis was included

in an EPA-prepared background document that is available in the federal docket, titled

Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water. EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances,

which is why EPA is providing the Director discretion to approve an alternative post-injection site

care timeframe as long as the owner or operator can meet the requirements provided at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; demonstrate the appropriateness of

an alternative post-injection site care time frame; perform post-injection monitoring; demonstrate

non endangerment; and perform site closure activities. This guidance will be available at

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

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 22906

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards); 3500 2.2.3 Area of Review Reevaluation (seeking comment) 

Comment: - Because carbon sequestration technology is still developing and the 

characteristics and limitations of CO2 GS projects will vary greatly from one 

site to another it is essential to incorporate performance-based standards into 

the Final Rule, leading to a site-tailored approach to requirements for Area of 

Review ("AoR") reevaluation and post-injection site care and closure periods. 

Response: The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a

combination of a fixed timeframe and a performance standard approach. EPA believes that a default

PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this timeframe,

combined with a site-specific Director’s discretion to create an alternative PISC time frame, ensures

that USDWs are protected. The GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC
timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c). EPA expects that the Director will consider the types of information the commenter

describes in determining whether the plume and pressure front no longer pose a risk of

endangerment to USDWs and post-injection site care monitoring may be discontinued.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA disagrees that the GS regulation should include performance-based standards for AoR

calculation. However, EPA believes that consideration of site-specific conditions is appropriate for

the AoR calculation and reevaluation process. EPA believes that the flexibility incorporated into the

AoR and corrective action plans and the provision for AoR reevaluation as required at §146.84(e)

provide for an ongoing review of the site and a dialogue between the Director and the owner or

operator to ensure that the most appropriate modeling and corrective action technologies are used to

protect USDWs from endangerment. However, EPA believes that setting a minimum reevaluation

frequency is appropriate. In the final rule, the Agency changed the minimum frequency for the AoR

reevaluation at §146.84(e) from 10 years to at least every 5 years in the final GS rule. EPA believes

that this revised frequency addresses commenters' concerns about the inherent uncertainties in

modeling CO2 movement, the emerging nature of GS technology, risk-based targeting of monitoring

activities, and the unique nature of CO2 GS. 

Commenter Name: Paul L. Carpinone Letter ID: 0212

Commenter Organization: Tampa Electric Company Comment ID: 22908

Other EPA Comment Codes and Descriptions: 5432 2.9.1.1 Need to adjust financial responsibility

mechanisms (seeking comment) 

Comment: - In developing guidance identifying financial responsibility mechanisms 

available for post-injection care, EPA should retain the option of selfinsurance instruments including the corporate financial test. Self-insurance has 

worked successfully for over two decades under the RCRA program and there is no 

reason why this option should not also be available for Class VI UIC wells. EPA 

must also take steps to mitigate the specter of open-ended financial liability 

for CO2 injection operations after the cessation of the post-injection site care 

period. Such open-end liability is one of the major impediments to the 

successful development of a commercial CO2 GS program. 

Response: EPA will retain self insurance as an option for financial responsibility for Class VI wells.

Owners or operators who choose to self-insure and use the financial test must be able to demonstrate

profitability, with a margin sufficient to cover contingencies and unknown obligations, and stability.

If the owner or operator meets corporate financial test criteria, this is an indication that the owner or

operator can guarantee its ability to satisfy financial obligations based solely on the strength of the

company’s financial condition. If an operator or operator is not able to meet the corporate financial

test criteria it may arrange a corporate guarantee by demonstrating that its corporate parent meets the

financial requirements on its behalf.
Under SDWA authority, owners or operators of injection wells must ensure protection of USDWs

from endangerment and are subject to liability for enforcement under the Act. The final rule requires

that an owner or operator must conduct post-injection site care that is consistent with the approved

PISC plan or for the duration of the alternative timeframe approved by the Director pursuant to

requirements in §146.93(c), until a demonstration can be made to the satisfaction of the Director that

the plume and pressure front no longer pose a risk of endangerment to USDWs. For additional

information about the PISC and site closure requirements, see the preamble to the final GS rule. 

Once an owner or operator has met all regulatory requirements under Part 146 for Class VI wells and

the Director has approved site closure pursuant to requirements at §146.93, the owner or operator

will generally no longer be subject to enforcement for regulatory noncompliance. Furthermore, their

financial instrument as required under §146.85 will be released if it was not used. However, even if a

site closure is approved under §146.93, an owner or operator may be held liable for regulatory

noncompliance (including violation of 40 CFR 144.12) in certain circumstances. For example, an

owner or operator may be held liable for regulatory noncompliance even after site closure was

approved if the Director relied on erroneous information (e.g., erroneous modeling data) provided by

the owner or operator when approving site closure. 

Additionally, an owner or operator may always be subject to any action the Administrator deems

necessary to protect the health of persons under §1431 of the SDWA after site closure if there is

unanticipated migration towards or into a USDW that causes or threatens imminent and substantial

endangerment to public health. The action may include issuing administrative orders or commencing

a civil action for appropriate relief. If the owner or operator fails to comply with the order, they may

be subject to a civil penalty for each day in which such violation occurs or failure to comply

continues. 

The Agency clarifies that Class VI well permits may be transferred to another owner or operator

pursuant to §144.38 whereby generally all other regulatory responsibilities are transferred to that new

owner and operator, which includes all potential liabilities associated with meeting the requirements

of that permit. Please see further clarification on the issue of long term liability in the preamble of

the final rule.

Furthermore, after site closure an owner or operator may remain liable under tort and other remedies,

or under other federal statutes including, but not limited to, Clean Air Act, 42 U.S.C. §§ 7401-7671;

CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. EPA does not have authority

to transfer SDWA or other legal liability for Class VI wells to the State or federal government or a

third-party fund. See the final rule preamble for further discussion of EPA's final approach. 

Commenter Name: Diane VanDe Hei Letter ID: 0213

Commenter Organization: Association of Metropolitan Water Agencies

(AMWA)

Comment ID:

22952

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

Comment: stabilization may continue for several decades." AMWA also recommends that 

additional research be conducted to better understand the movement of CO2 plumes 

and that EPA provide guidance to owner/operators about the criteria for 

monitoring and modeling data that would be necessary to demonstrate that the 

plume has stabilized and justify site closure. 
Response: EPA is developing guidance to assist owners or operators in evaluating well plugging,

post-injection site care, and site closure requirements of §146.92 and §146.93. Additionally, the

guidance will assist Directors in evaluating proposed well plugging plans and post-injection site care

and site closure plans under §146.92 and §146.93. The guidance describes recommended approaches

for how an owner or operator could plug injection and monitoring wells; perform post-injection

monitoring; demonstrate non-endangerment; and perform site closure activities. The guidance will

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

EPA agrees that continued research in all GS associated fields will be integral to development of GS

technology. 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.

For additional information on these requirements, please also see the discussion of testing and

monitoring under EPA’s Final Regulatory Approach in the preamble to the final GS rule.

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23994

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

language; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Director affirmatively acts to extend the post-injection site care period. These 

changes are contained in the suggested text below: 

§ 146.93 Post-injection site care and site closure. 

(a) The owner or operator of a Class VI well must prepare, maintain, and 

comply with a plan for post-injection site care and site closure that 

meets the requirements of paragraph (a)(2) of this section and is 

acceptable to the Director. 

(1) The owner or operator must submit the post-injection site 

care and site closure plan as a part of the permit application to be 

approved by the Director. 

(2) The post-injection site care and site closure plan must 

include the following information: 

(i) The pressure differential between pre-injection and 

predicted post-injection pressures in the injection zone; 

(ii) The predicted position of the carbon dioxide plume 

and associated pressure front at site closure as demonstrated in 

the area of review evaluation required under § 146.84(b); 

(iii) A description of post-injection monitoring 

location, methods, and proposed frequency; and 

(iv) A proposed schedule for submitting post-injection 

site care monitoring results to the Director. 

(3) Upon cessation of injection, owners or operators of Class VI 

wells must either submit an amended post-injection site care and site 

closure plan or demonstrate to the Director through monitoring data and 

modeling results that no amendment to the plan is needed. 

(4) The owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval 
within 30 days of such change. 

(b) The owner or operator shall monitor the site following the cessation 

of injection to show the position of the carbon dioxide plume and 

pressure front and demonstrate that USDWs are not being endangered. 

* 

* 

* 

(3) Prior to authorization for THE EXPIRATION OF THE PERIOD 

SPECIFIED IN SUBPART (B)(1), site closure, the owner or operator 

must submit to the Director a demonstration, based on monitoring and 

other site specific data, that the carbon dioxide plume and pressure 

front have stabilized and that no additional monitoring is needed to 

assure that the geologic sequestration project does not pose an 

endangerment to USDWs. 

(4) IF WITHIN 180 DAYS AFTER THE SUBMITTAL OF THE DATA REQUIRED 

UNDER SUBPARAGRAPH (3), THE DIRECTOR DETERMINES THAT THE GEOLOGICAL 

SEQUESTRATION PROJECT MAY CONTINUE TO POSE AN ENDANGERMENT TO

USDWS, HE 

SHALL SO NOTIFY THE OWNER OR OPERATOR OF HIS DETERMINATION AND THE

BASIS 

THEREFORE, AND If such a demonstration cannot be made (i.e., if the 

carbon dioxide plume and pressure front have not stabilized) after the 

50-year period, the owner or operator must submit to the Director a 

plan to continue post-injection site care. 

(5) IF WITHIN 180 DAYS AFTER THE SUBMITTAL OF THE DATA REQUIRED 

UNDER SUBPARAGRAPH (3) ABOVE THE DIRECTOR FAILS TO DETERMINE AND TO 

NOTIFY THE OWNER OR OPERATOR THAT THE GEOLOGICAL SEQUESTRATION

PROJECT 

MAY CONTINUE TO POSE AN ENDANGERMENT TO USDWS, SITE CLOSURE SHALL BE 

DEEMED AUTHORIZED BY RULE 

(c) Notice of intent for site closure. The owner or operator must notify 

the Director at least 120 days before site closure. At this time, if any 

changes have been made to the original post- injection site care and 

site closure plan, the owner or operator must also provide the revised 

plan. At the discretion of the Director, a shorter notice period may be 

allowed. 

(d) After the Director has authorized site closure OR SITE CLOSURE IS 

AUTHORIZED BY RULE, the owner or operator must plug all monitoring wells 

in a manner which will not allow movement of injection or formation 

fluids that endangers a USDW. 

(e) Once the Director has authorized site closure, OR SITE CLOSURE IS 

AUTHORIZED BY RULE, the owner or operator must submit a site closure 

report within 90 days that must thereafter be retained at a location 

designated by the Director. The report must include: 

(1) Documentation of appropriate injection and monitoring well 

plugging as specified in § 146.92 and paragraph (c) of this section. The 

owner or operator must provide a copy of a survey plat which has been 

submitted to the local zoning authority designated by the Director. The 

plat must indicate the location of the injection well relative to 

permanently surveyed benchmarks. The owner or operator must also submit 
a copy of the plat to the Regional Administrator of the appropriate EPA 

Regional Office; 

(2) Documentation of appropriate notification and information to 

such State, local and tribal authorities as have authority over drilling 

activities to enable such State and local authorities to impose 

appropriate conditions on subsequent drilling activities that may 

penetrate the injection and confining zone(s); and (3) Records 

reflecting the nature, composition and volume of the carbon dioxide 

stream. 

(f) Each owner or operator of a Class VI injection well must record a 

notation on the deed to the facility property or any other document that 

is normally examined during title search that will in perpetuity provide 

any potential purchaser of the property the following information: 

(1) The fact that land has been used to sequester carbon 

dioxide; 

(2) The name of the State agency, local authority, and/or tribe 

with which the survey plat was filed, as well as the address of the 

Regional Environmental Protection Agency Office to which it was 

submitted; and 

(3) The volume of fluid injected, the injection zone or zones 

into which it was injected, and the period over which injection 

occurred. 

(g) The owner or operator must retain for three years following site 

closure, records collected during the post-injection site care period. 

The owner or operator must deliver the records to the Director at the 

conclusion of the retention period, and the records must thereafter be 

retained at a location designated by the Director for that purpose. 

Response: The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a

combination of a fixed timeframe and a performance standard approach. EPA believes that a default

PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this timeframe,

combined with a site-specific Director’s discretion to create an alternative PISC time frame, ensures

that USDWs are protected. The GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA expects that the Director would consider the types of information the commenter describes in

determining whether the plume and pressure front no longer pose a risk of endangerment to USDWs

and post-injection site care monitoring may be discontinued. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.
EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21784

Comment: -The open-ended requirement for post-injection site care (§146.93(b)). 

Response: Please see EPA’s response to the more detailed comment below.

Commenter Name: Neeraj Gupta Letter ID: 0229

Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21865

Comment: Page 118, Post-injection Site Care Plan- The post injection site care plan would 

seem to require monitoring of pressures, plume extent, and other items after 

injection stops. However, this would prevent plugging and abandoning wells. It 

is recommended that the post-injection site care requirements allow for the 

plugging and abandoning of wells that are not being used for monitoring. 

Response: EPA acknowledges that owners or operators may wish to use injection wells for

monitoring purposes to meet the post-injection monitoring requirements. Nothing in the GS rule

precludes this. EPA clarifies that Class VI injection wells must be plugged in a manner that protects

USDWs from endangerment, as specified in 146.92(b). These requirements apply whether the well is

plugged upon cessation of injection or at the time of site closure.

Commenter Name: A. James Mayer Letter ID: 0230

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

Energy Security Initiative

Comment ID:

21889

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: 6. EPA should provide for performance-based requirements for Closure and Post 

Closure Care. The duration of post-injection site care should be determined by 

specific conditions and characteristics of the site, and monitoring of the 

pressure to determine the point at which the injection zone pressure is such 

that USDWs cannot be impacted. 

Response: The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a

combination of a fixed timeframe and a performance standard approach. EPA believes that a default

PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this timeframe,

combined with a site-specific Director’s discretion to create an alternative PISC time frame, ensures

that USDWs are protected. The GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to
demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating the well plugging, postinjection site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance

will assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes how an owner or operator should

plug injection and monitoring wells, perform post-injection monitoring, demonstrate the

appropriateness of an alternative post-injection site care time frame, demonstrate non-endangerment,

and perform site closure activities.

Commenter Name: M. Granger Morgan Letter ID: 0233

Commenter Organization: Carnegie Mellon University on behalf of the CCS

Reg Project

Comment ID:

21910

Comment: 19. Post-injection site care: We support the site-specific approach to postinjection site care that EPA proposes in section 146.93. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision.

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22312

Comment: Perhaps inadvertently, the proposed rule does not explicitly require updating of 

several of the required plans. In most but not all cases, there is a rather 

ambiguous requirement to "maintain" a given plan. Explicit requirements to make 

updates as warranted appear to be missing from provisions relating to: 

• the post- injection site care and site closure plan required by §146.93 (not 

only is the word "maintain" used, but the ambiguity inherent in this term is 

revealed by the instruction in §146.93(a)(3) to consider amendments to this plan 

"upon cessation of injection" - §146.93 might be read to mean that operators 

could "maintain" this particular plan simply by considering the need for 

amendment on one occasion over the life of the facility); and 

Response: EPA believes that developing and implementing a post-injection site care and site closure

plan is important to ensure protection of USDWs, and agrees that the plan should be revised as

needed to account for the most recent information about the site. EPA anticipates that, in some cases,

the appropriate post-injection monitoring strategy may end up being different than initially projected

and there may be a need to amend the post-injection site care and site closure plan. EPA is requiring

that upon the cessation of injection, the owner or operator submit an amended post-injection site care

and site closure plan or demonstrate to the Director that no changes to the original post-injection site

care and site closure plan are necessary, as specified in §146.93(a)(3). EPA is not requiring formal
periodic review and updates to the PISC and site closure plan throughout the injection phase. EPA

does not expect that changes to this plan would be implemented until injection operations cease.

EPA envisions that owners or operators would take into account similar considerations that guide

updates to other project plans, e.g., monitoring and operational data and results of AoR

reevaluations. EPA adds that, if any monitoring or other site data indicate a need for amending the

post-injection site care plan, the owner or operator is expected to amend the plan accordingly.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24864

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

Comment: EPA Proposal: Post-injection site care means appropriate monitoring and other 

actions (including corrective action) needed following cessation of injection to 

assure that USDWs are not endangered as required under § 146.93. 

GWPC Recommendations: Post-injection site care means monitoring and other 

actions (including corrective action) following cessation of injection, as 

required under 146.93. 

Rationale: The definition should explain the meaning and not impose substantive 

requirements. These requirements are already addressed in other sections. 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24866

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

Comment: EPA Proposal: Site closure the point/time, as determined by the Director 

following the requirements under § 146.93, at which the owner or operator of a 

GS site is released from post-injection site care responsibilities. 

GWPC Recommendations: Site closure means the point/time, as determined by the 

Director following the requirements under §146.93, at which the owner or 

operator of a GS project is released from post-injection site care 

responsibilities. 

Rationale: Add "means" 

Suggest using "GS project" to be consistent with other definitions 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24941

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

Comment: EPA Proposal: (2) The post-injection site care and site closure plan must 

include the following information: 

(i) The pressure differential between pre-injection and predicted post-injection 

pressures in the injection zone; 

(ii) The predicted position of the carbon dioxide plume and associated pressure 

front at site closure as demonstrated in the area of review evaluation required 

under § 146.84(b); 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24943

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

language 

Comment: EPA Proposal: (3) Upon cessation of injection, owners or operators of Class VI 

wells must either submit an amended post-injection site care and site closure 

plan or demonstrate to the Director through monitoring data and modeling results 

that no amendment to the plan is needed. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24944

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

language 

Comment: EPA Proposal: (4) The owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval within 30 

days of such change. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision.

Comment Code: 5220 2.8.2.1 Post-injection monitoring activities 
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: 21986

Comment: more accurate reading. 146.93 (b) (3): Plume stabilization needs to be 

clarified as to what this means. The plume will never be completely stabile. The 

CO2 plume will continue to move by a combination of methods including density 

differences, natural formation flow gradients and diffusion. Recommend dropping 

the reference to the plume or pressure front having stabilized. 

Response: EPA clarifies that in the final rule, §146.93(b)(3) no longer requires the plume and

pressure front to have stabilized. EPA acknowledges that many site-specific factors will influence

the determination of when the CO2 plume and pressure front no longer pose a risk of endangerment

to USDWs. It is for this reason that EPA believes that Directors, in consultation with operators, will

be in the best position to determine whether additional post-injection site care is needed. EPA

expects this decision to be made based on relevant site data and in consultation with all potentially

impacted parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time

periods due to density differences, natural formation flow gradients, and diffusion. EPA clarifies that

a complete cessation of plume movement is not required, only a demonstration that the plume and

pressure front no longer pose a risk of endangerment to USDWs. 

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24798

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

language 

Comment: (1) The owner or operator must submit the post-injection site care and site 

closure plan as a part of the permit application to be approved by the 

Director.

{Redundant - See 146.82(w).} 

Response: EPA clarifies that the reference to the post-injection site care and site closure plan, in the

final rule at §146.82(a)(17), requires that the plan be included in the attachments to the Class VI

permit application. The details of the plan contents are included in §146.93, along with other

requirements related to post-injection site care and site closure.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24802

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: (b) THE OWNER OR OPERATOR MUST Must monitor the site following the

cessation 

of injection to show the position of the carbon dioxide plume and pressure front 

and demonstrate that USDWs are not being endangered. 
(1) THE OWNER OR OPERATOR MUST Must continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site closure 

plan for THE PERIOD OF TIME at least 50 years following the cessation of 

injection . At the Director's discretion, the monitoring will continue until 

THE DIRECTOR DETERMINES THAT the geologic sequestration project no longer poses 

an endangerment to USDWs. 

Response: EPA disagrees with the suggested edits. However, EPA agrees with commenters that

there will be circumstances where it can be demonstrated in less than 50 years that the plume and

pressure front no longer pose a risk of endangerment to USDWs. For this reason, the final GS rule

offers owners or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing

the Director discretion to shorten or lengthen the PISC timeframe during the PISC period based on

site-specific data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to

allow a Class VI well owner or operator to demonstrate, based on substantial data during the

permitting process, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24974

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: (2) If the owner or operator can demonstrate to the satisfaction of the 

Director before 50 years, based on monitoring and other site-specific data, that 

the GS project no longer poses an endangerment to USDWs, the Director may 

approve an amendment to the post-injection site care and site closure plan to 

reduce the frequency of monitoring or may authorize site closure before the end 

of the 50-year period.

{The period of time an owner or operator is required to conduct post-closure 

care monitoring should be based on the ability of the pressure to cause 

endangerment of USDWs. A 50-year post-closure care monitoring period is 

unprecedented and implies that CO2 presents a greater risk than it does. RRC 

suggests that EPA strike the phrase "for at least 50 years" and make the time 

for continued monitoring be based on site specific data. } 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Area-
of-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances,

which is why EPA is providing the Director discretion to approve an alternative post-injection site

care timeframe as long as the owner or operator can meet the requirements provided at §146.93(c).

EPA acknowledges there will be circumstances where it can be demonstrated in less than 50 years

that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this reason,

the GS rule offers owners or operators flexibility regarding the duration of the PISC timeframe by:

(1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the postinjection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the

permitting process based on substantial data, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22613

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: Proposed Rule: 146.93(a) 

Proposed revision: (a) The owner or operator of a Class VI well must prepare; 

maintain; including updating on the same schedule as the update to the Area of 

Review; and comply with a plan for post-injection site care and site closure 

that meets the requirements of paragraph (a)(2) of this section and is 

acceptable to the Director. 

Rationale: The Area of Review re-evaluation should trigger a review and updating 

of the well plugging plan, and the post injection site care and closure plan. 

NGWA suggests EPA check all timelines and make them compatible. 
Response: EPA agrees with the commenter that, in some cases, the appropriate post-injection

monitoring strategy may end up being different than initially projected at the time of permit

application and there may be a need to amend the post-injection site care and site closure plan. EPA

is requiring that upon the cessation of injection, the owner or operator submit an amended postinjection site care and site closure plan or demonstrate to the Director that no changes to the original

post-injection site care and site closure plan are necessary, as specified in §146.93(a)(3). EPA is not

requiring formal periodic review and updates to the PISC and site closure plan throughout the

injection phase. EPA does not expect that changes to this plan would be implemented until injection

operations cease. EPA envisions that owners or operators will take into account similar

considerations that guide updates to other project plans, e.g., monitoring and operational data and

results of AoR reevaluations. 

EPA has also added a new provision at §144.39(a)(5) requiring a modification, revocation, or

reissuance of a Class VI permit whenever the Director determines that a change in the permit is

necessary based on an amended AoR and corrective action plan, testing and monitoring plan,

injection well plugging plan, post-injection site care and site closure plan, or emergency and

remedial response plan is necessary. This would invoke the public notification procedures of 40 CFR

Part 124 and the modification would be incorporated into the permit. EPA adds that, if any

monitoring or other site data indicate a need for amending the post-injection site care plan, the

owner or operator is expected to amend the plan accordingly.

Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality

(MDEQ)

Comment ID:

22107

Other EPA Comment Codes and Descriptions: 1620 1.3.2 Induced seismicity 

Comment: 7. EPA clearly identifies the risks of seismic effects from geologic 

sequestration and indicates the need to only select sites that are geologically 

stable. Each state has a geologic survey which monitors seismic activity. 

Further, any area can surprise geologists with activity that was unexpected. [An 

example in Montana would be the usually seismically quiet area near Grass Range 

that surprisingly had a recent event at over 4 on the Richter scale. In fact, 

no areas of Montana are seismically at zero on the Richter scale, but may still 

be appropriate for sequestration.] Each geologic sequestration site should be 

required to add seismic monitoring that is added to the state's monitoring 

network. This monitoring should be started as baseline and continued well after 

closure of injection activities. 

Response: EPA acknowledges that induced seismicity is a risk that may be associated with GS but

maintains that the risk is low (IPCC, 2005). The GS rule contains several requirements to address

seismic risk. First, as part of the site characterization process, owners or operators must submit

information about the seismic history of and seismic sources near a proposed GS site, data on known

or suspected faults in the AoR, geomechanical information on fractures, stress, ductility, rock

strength, and in situ fluid pressures within the confining zone as specified in §146.82(a)(3). This

information is evaluated by the Director, who determines the suitability of a potential project site for

GS. Any sites with the potential for reopening or reactivation of faults or unacceptable seismic risk

that could otherwise interfere with containment will not be permitted as GS sites. During injection,

the pressure in the injection zone must not exceed 90 percent of the fracture pressure of the injection

zone as specified in §146.88(a); this requirement is intended to prevent the opening of fractures or
faults through over pressurization of the injection zone.

Given the emphasis on site selection to reduce the potential for induced seismicity, EPA disagrees

that seismic monitoring is necessary at all GS sites. However, EPA adds that the Director has the

authority to require such monitoring under §146.90(i) if he or she believes this to be appropriate

based on site-specific information. 

EPA does not believe that limiting GS to "stable areas" will provide certainty that seismic events will

not occur. The Agency acknowledges that some regions of the country are at risk for infrequent,

damage-causing seismic events even if such events have not been recorded in the recent historical

record (i.e., in the past several hundred years). For this reason, EPA requires seismic risk to be

evaluated on a site-specific basis, through an analysis of seismic history and an evaluation of 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). In

addition, if an adverse event, such as a well failure or evidence of fluid movement were to occur, the

monitoring requirements at §146.90 and emergency and remedial response requirements as specified

in §146.94 provide additional protection.

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22670

Comment: o Page 43540 under "Post-injection site care and site closure." The USEPA 

should ask for a seismic image or other data that depicts the current extent and 

placement of the CO2 plume. The current language asks for "the predicted 

position." If the EPA would like modeling of the predicted position for some 

purpose that is fine but there is no reason not to ask for data that shows where 

the plume really is. 

Response: EPA clarifies that the purpose of the requirement that the PISC and site closure plan

include a prediction of the magnitude of the pressure differential between pre-injection and during

post-injection at §146.93(a)(2)(i) is to support planning of the amount of monitoring that is necessary

during PISC and planning the length of the PISC timeframe. EPA anticipates that this information

will be provided by the computational modeling performed for the AoR delineation. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non-endangerment; and perform site closure activities. The guidance will be available at

http://www.epa.gov/safewater/wells_sequestration.html. 

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24203

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

language 

Comment: Rule Provision: 146.93(a)(1) 
API Comments: (1) The owner or operator must submit the postinjection site 

care and site closure plan as a part of the permit application to be approved by 

the Director. SHALL CONTINUE TO CONDUCT MONITORING AS SPECIFIED IN THE 

DIRECTOR-APPROVED POST-INJECTION SITE CARE AND SITE CLOSURE PLAN,

PURSUANT TO 

THE PERFORMANCE BASED CRITERIA DESCRIBED IN 146.93(B)(3). 

Rationale: Revisions here reflect changes to §146.93(b)(3) 

Response: EPA disagrees with the suggested changes, and disagrees that the post-injection

monitoring period should be strictly performance-based. The Agency agrees that there will be limited

circumstances where it can be demonstrated in less than 50 years that the plume and pressure front

no longer pose a risk of endangerment to USDWs, and has included requirements in the final Class

VI rule at §146.93(c) for an owner or operator to substantially demonstrate that an alternative time

frame ensures the protection of USDWs. However, EPA anticipates that a default timeframe for

post-injection site care will necessary for most GS sites to ensure the protection of USDWs. A 50-

year post-injection site care timeframe represents a reasonable and protective monitoring period

based on a review of research studies, industry reports, and existing environmental programs, and

evaluation of public comments. For this reason, the final GS regulation includes a provision that the

Director may, at his or her discretion, shorten the post-injection site care timeframe if the owner or

operator can demonstrate that the GS project does not pose an endangerment to USDWs, as

specified in §146.93(b)(2). Such a demonstration will be site-specific, and based on pressure

monitoring and USDW impacts.

The GS rule requires owners or operators to submit a post-injection site care and site closure plan as

part of the permit application, as specified in §146.82(a), in order to outline how these activities will

be performed and how non-endangerment of USDWs will be demonstrated throughout the postinjection site care period. 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23706

Other EPA Comment Codes and Descriptions: 5280 2.8.2.4 USDW non-endangerment

demonstrations 

Comment: AWWA has observed that the proposed regulation is lacking in details on the 

requirements to demonstrate that the carbon dioxide plume has stabilized. For 

example, the proposal does not include requirements that the plume pressure must 

be constant for a certain number of years or that the plume has not migrated for 

a set period of time. Since AWWA does not claim to be experts on the behavior of 

carbon dioxide plumes and can not provide recommendations on this topic, AWWA 

recommends that EPA should engage in research on determining exactly what these 

criteria should be. For example, when referencing lack of plume movement, what 

should the trigger time period be (no movement of plume for 10, 15, 20 or more 

years??). AWWA recommends that EPA clarify what is an acceptable frequency for a 

lack of change in the plume characteristics and also needs to clarify plume 

stabilization as this issue could be interpreted differently by different 

states. Guidance should be prepared by EPA on this topic so that there is 

consistent application of this requirement across all sequestration projects. A 

performance based system could also be developed that would require the operator 

to meet certain criteria to prove that the plume has stabilized. This could be 
used to justify the closing of the site after the 50-year period of postinjection site care has elapsed. This would allow for a process where long-term 

monitoring decisions are made in response to the specific characteristics of 

each project. 

AWWA believes that the proposed post-injection site care requirements have been 

established to prevent endangerment to USDWs. Carbon dioxide can potentially 

leak from the confining layer into other aquifers that, while not classified as 

USDWs, may still be considered drinking water sources in some areas of the 

county. EPA should also consider including requirements in the regulation to 

address the potential for endangerment of these aquifers during the postinjection period. Monitoring requirements should be extended to cover these 

aquifers, and the post-injection site care plan should include provisions for 

the protection of aquifers that are not classified as USDWs, but are still 

considered a future drinking water source. 

Response: EPA acknowledges that many site-specific factors will influence the determination of

when the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for

this reason that EPA believes that individual UIC Directors, in consultation with operators, will be in

the best position to determine whether additional post-injection site care is needed. EPA expects this

decision to be made based on relevant site data and in consultation with all potentially impacted

parties. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

EPA has conducted research regarding stabilization timeframes. As described in the preamble to the

proposed rule, in determining the post-injection site care-timeframe for the proposed regulation, EPA

reviewed industry reports, existing environmental programs, and initial GS research studies. EPA

provided a synthesis of pertinent results from GS modeling studies in the preamble to the proposed

regulation. Further explanation of this analysis was included in an EPA-prepared background

document that is available in the federal docket, titled "Computational Modeling of Underground

Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk to

Underground Sources of Drinking Water." Based on review of these studies, modeling results

indicate that the CO2 plume stabilization may occur on the timeframe of 10-100 years after the

cessation of injection. EPA believes that a 50-year default post-injection site care timeframe is a

reasonable midpoint for most GS projects and available data, including data submitted by

commenters, do not support a different default timeframe, and has retained this in the final

regulation. EPA will continue research in this area and plans, every six years, to collect and review

data on GS projects to determine whether the appropriate amount and types of information and

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

are appropriate or necessary.
Commenter Name: Robert F. Van Voorhees Letter ID: 0190

Commenter Organization: Carbon Sequestration Council Comment ID: 24493

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

language 

Comment: Rule Provision: 146.93(a)(1) 

Proposed CCS Group Recommendations: (1) The owner or operator must submit the 

post-injection site care and site closure plan as a part of the permit 

application to be approved by the Director. SHALL CONTINUE TO CONDUCT 

MONITORING AS SPECIFIED IN THE DIRECTOR-APPROVED POST-INJECTION SITE

CARE AND 

SITE CLOSURE PLAN, PURSUANT TO THE PERFORMANCE BASED CRITERIA

DESCRIBED IN 

146.93(B)(3). 

Basis for CCS Group Comments: Revisions here reflect changes to §146.93(b)(3) 

Response: EPA disagrees with the suggested changes, and disagrees that the post-injection

monitoring period should be strictly performance-based. The Agency agrees that there will be limited

circumstances where it can be demonstrated in less than 50 years that the plume and pressure front

no longer pose a risk of endangerment to USDWs, and has included requirements in the final Class

VI rule at §146.93(c) for an owner or operator to substantially demonstrate that an alternative time

frame ensures the protection of USDWs. However, EPA anticipates that a default timeframe for

post-injection site care will necessary for most GS sites to ensure the protection of USDWs. A 50-

year post-injection site care timeframe represents a reasonable and protective monitoring period

based on a review of research studies, industry reports, and existing environmental programs, and

evaluation of public comments. For this reason, the final GS regulation includes a provision that the

Director may, at his or her discretion, shorten the post-injection site care timeframe if the owner or

operator can demonstrate that the GS project does not pose an endangerment to USDWs, as

specified in §146.93(b)(2). Such a demonstration will be site-specific, and based on pressure

monitoring and USDW impacts.

The GS rule requires owners or operators to submit a post-injection site care and site closure plan as

part of the permit application, as specified in §146.82(a), in order to outline how these activities will

be performed and how non-endangerment of USDWs will be demonstrated throughout the postinjection site care period. 

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24494

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

language; 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Comment: Rule Provision: 146.93(a)(2) 

Proposed CCS Group Recommendations: (2) The post-injection site care and site 

closure plan must include the following information: 

(i) The pressure differential between pre-injection and predicted post-injection 

pressures in the injection zone; 
(ii) The predicted position of the carbon dioxide plume and associated pressure 

front at site closure as demonstrated in the area of review evaluation required 

under § 146.84(b); 

(iii) A description of post-injection monitoring location, methods, and proposed 

frequency; and 

(iv) A proposed schedule for submitting post-injection site care monitoring 

results to the Director.

Basis for CCS Group Comments: Revisions here reflect changes to §146.93(b)(3) 

Response: Based on its evaluation of all public comments and input on the proposed rule and

NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule

and preamble for further discussion on EPA's final approach.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24497

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b) 

Proposed CCS Group Recommendations: (b) The owner or operator shall monitor the 

site following the cessation of injection to show the position of the carbon 

dioxide plume and pressure front and demonstrate that USDWs are not being 

endangered.

(1) The owner or operator shall continue to conduct monitoring as specified in 

the Director-approved post-injection site care and site closure plan, UNTIL 

CLOSURE IS AUTHORIZED PURSUANT TO 146.93(B)(3). 

Basis for CCS Group Comments: EPA should also reconsider its proposed 50-year 

default period for post-injection site care. EPA offers no rationale for this 

arbitrarily-selected period of 50 years. Establishing a fixed and unusually long 

time period may create a significant barrier for operators considering entry 

into CCS operations. Criteria for determining the period for post-injection site 

care should be performance-based and a function of the site specific 

characteristics of a project such as project size, geologic factors, and 

relative risk of the project. Such criteria are provided in our edits to 

§146.93(b)(3). 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most

cases or arbitrary. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,
none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

acknowledges there will be circumstances where it can be demonstrated in less than 50 years that the

plume and pressure front no longer pose a risk of endangerment to USDWs. For this reason, the GS

rule offers owners or operators flexibility regarding the duration of the PISC timeframe by: (1)

allowing the Director discretion to shorten or lengthen the PISC timeframe during the post-injection

period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the

Director discretion to allow a Class VI well owner or operator to demonstrate, during the permitting

process based on substantial data, that an alternative PISC timeframe may be appropriate if it ensures

non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24498

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(2) 

Proposed CCS Group Recommendations: (2) If the owner or operator can request and 

demonstrate to the satisfaction of the Director before 50 years, based on 

monitoring and other site-specific data, that the geologic sequestration project 

no longer poses an endangerment to USDWs, the Director may approve an amendment 

to THAT the post-injection site care and site closure plan SHOULD BE REVISED 

to reduce the frequency of monitoring, THE DIRECTOR SHALL APPROVE THE REDUCTION. 

or may authorize site closure before the end of the 50-year period.

Basis for CCS Group Comments: See rationale stated above for eliminating 50-year 

period. 

Response: As described above, EPA disagrees that a post-injection site care timeframe of 50 years is

excessive in most cases or arbitrary, and retains the default 50-year post-injection site care
timeframe in the final rule.

Commenter Name: Kyle Isakower Letter ID: 0191

Commenter Organization: American Petroleum Institute Comment ID: 23881

Comment: performance and as such is more protective of USDWs. Second, the proposal 

requires a showing that the CO2 plume has "stabilized", which is undefined. 

Cessation of plume movement is not necessarily essential to show that a project 

poses no threat of endangerment to USDWs - plumes that are still moving may, 

nonetheless, remain contained. Instead, it is more protective to show that the 

plume is not expected to encounter a leakage pathway. Third, the required 

Response: EPA agrees that a complete cessation of plume movement may not occur at some sites

for long time periods due to density differences, natural formation flow gradients and diffusion. EPA

clarifies that under the final rule, a complete cessation of plume movement is not required, only a

demonstration that the plume and pressure front no longer pose a risk of endangerment to USDWs. 

EPA acknowledges that many site-specific factors will influence the determination of when the CO2

plume and pressure front no longer pose a risk of endangerment to USDWs. It is for this reason that

EPA believes that Directors, in consultation with operators, will be in the best position to determine

whether additional post-injection site care is needed. EPA expects this decision to be made based on

relevant site data and in consultation with all potentially impacted parties. EPA also recognizes that

there may be sites where the 50 year post injection site care timeframe may be either not appropriate

or more burdensome than necessary based on site-specific conditions. For this reason, the GS rule

offers owners or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing

the Director discretion to shorten or lengthen the PISC timeframe during the post-injection period

based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the Director

discretion to allow a Class VI well owner or operator to demonstrate, during the permitting process

based on substantial data, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Kyle Isakower Letter ID: 0191

Commenter Organization: American Petroleum Institute Comment ID: 23882

Comment: plume is not expected to encounter a leakage pathway. Third, the required 

showing that "no additional monitoring is needed" does not provide guidance 

regarding how an operator is to show that no additional monitoring is needed. 

The proposal below provides specific guidance on what the operator must show. 

Response: EPA acknowledges that many site-specific factors will influence the determination of

when the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for
this reason that EPA believes that Directors, in consultation with operators, will be in the best

position to determine whether additional post-injection site care is needed. EPA expects this decision

to be made based on relevant site data and in consultation with all potentially impacted parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that

under the final rule, a complete cessation of plume movement is not required, only a demonstration

that the plume and pressure front no longer pose a risk of endangerment to USDWs is. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23902

Comment: USDWs. Second, the proposal requires demonstration that the CO2 plume has 

"stabilized", which is undefined. Cessation of plume movement is not necessarily 

essential, and may not be applicable, to show that a project poses no threat of 

endangerment to USDWs-plumes that are still moving may, nonetheless, be in 

geological settings which ensure that they remain contained. Instead, it is more 

protective to show that the plume is not expected to encounter a leakage 

pathway. Third, the required demonstration that "no additional monitoring is 

Response: EPA acknowledges that many site-specific factors will influence the determination of

when the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for

this reason that EPA believes that Directors, in consultation with operators, will be in the best

position to determine whether additional post-injection site care is needed. EPA expects this decision

to be made based on relevant site data and in consultation with all potentially impacted parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that

under the final rule, a complete cessation of plume movement is not required, only a demonstration

that the plume and pressure front no longer pose a risk of endangerment to USDWs is. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities. The guidance will be available at

http://www.epa.gov/safewater/wells_sequestration.html. 

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23903
Comment: pathway. Third, the required demonstration that "no additional monitoring is 

needed" does not provide guidance regarding how an operator is to show that no 

additional monitoring is needed. The proposal below provides specific guidance 

on what the operator must show. 

Response: As described above, EPA acknowledges that many site-specific factors will influence the

determination of when the CO2 plume and pressure front no longer pose a risk of endangerment to

USDWs. It is for this reason that EPA believes that Directors, in consultation with operators, will be

in the best position to determine whether additional post-injection site care is needed. EPA expects

this decision to be made based on relevant site data and in consultation with all potentially impacted

parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that

under the final rule, a complete cessation of plume movement is not required, only a demonstration

that the plume and pressure front no longer pose a risk of endangerment to USDWs is. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24716

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

language 

Comment: Rule Provision: 146.93(a)(1) 

Anadarko Petroleum Corporation (APC) Comments: (1) The owner or operator must 

submit the postinjection site care and site closure plan as a part of the permit 

application to be approved by the Director. SHALL CONTINUE TO CONDUCT 

MONITORING AS SPECIFIED IN THE DIRECTOR-APPROVED POST-INJECTION SITE

CARE AND 

SITE CLOSURE PLAN, PURSUANT TO THE PERFORMANCE BASED CRITERIA

DESCRIBED IN 

146.93(3). 

Rationale: Revisions here reflect changes to §146.93(b)(3) 

Response: EPA disagrees with the suggested changes, and disagrees that the post-injection

monitoring period should be strictly performance-based. The Agency agrees that there will be limited

circumstances where it can be demonstrated in less than 50 years that the plume and pressure front

no longer pose a risk of endangerment to USDWs.

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)
affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

The GS rule requires owners or operators to submit a post-injection site care and site closure plan as

part of the permit application, as specified in §146.82(a), in order to outline how these activities will

be performed and how non-endangerment of USDWs will be demonstrated throughout the postinjection site care period. 

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24719

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(1) 

Anadarko Petroleum Corporation (APC) Comments: (1) The owner or operator shall 

continue to conduct monitoring as specified in the Director-approved postinjection site care and site closure plan, for at least 50 years following the 

cessation of injection. At the Director’s discretion, the monitoring will 

continue until the geologic sequestration project no longer poses an 

endangerment to USDWs. PURSUANT TO THE PERFORMANCE BASED CRITERIA

DESCRIBED IN 

§146.93(B)(3). 

Rationale: EPA should also reconsider its proposed 50- year default period for 

post-injection site care. EPA offers no rationale for this arbitrarily selected 

period of 50 years. Establishing a fixed and unusually long time period may 

create a significant barrier for operators considering entry into CCS 

operations. Criteria for determining the period for postinjection site care 

should be performance based and a function of the site specific characteristics 

of a project such as project size, geologic factors, and relative risk of the 

project. APC offers such criteria in our edits to §146.93(b)(3). 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most

cases or arbitrary. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Area-
of-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances.

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS. Rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24720

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(2) 

Anadarko Petroleum Corporation (APC) Comments: (2) If the owner or operator can 

request and demonstrate to the satisfaction of the Director before 50 years, 

based on monitoring and other site-specific data, that the geologic 

sequestration project no longer poses an endangerment to USDWs, the Director may 

approve an amendment to THAT the post-injection site care and site closure 

plan SHOULD BE REVISED to reduce the frequency of monitoring. or may authorize 

site closure before the end of the 50-year period.
Rationale: (See above) 

Response: As described above, EPA disagrees that a post-injection site care timeframe of 50 years is

excessive in most cases or arbitrary, and retains the default 50-year post-injection site care

timeframe in the final rule.

Commenter Name: Kurt Waltzer Letter ID: 0250

Commenter Organization: Clean Air Task Force Comment ID: 22290

Comment: Site closure standards and framework for long-term stewardship 

Our Environmental NGO Group did not come to a common set of recommendations on 

site closure and are either submitting individual comments on this issue or are 

submitting comments jointly with other groups. We do agree, however, that EPA’s 

proposed closure standards in §146.93 need revision. In order to assure that 

site risks have diminished to the point that it is reasonable to discontinue or 

significantly reduce monitoring, it is essential that the rule require a 

demonstration of much more than merely ‘plume stabilization’ and that the nature 

of what must be demonstrated be precisely described. In addition, given the 

desired permanent nature of CO2 sequestration in the subsurface and the 

importance to the public of ensuring long-term oversight of project sites, EPA 

should use its existing regulatory authorities to establish a framework for 

long-term stewardship and seek whatever additional authorities may be required 

for this purpose from Congress. This framework should include an entity with 

responsibility for monitoring and managing sites after closure has been 

authorized. The proposed rule authorizes operators to stop monitoring, but does 

not provide for the stewardship of sites following closure.. EPA must rectify 

this omission. It is important that the post-closure framework include financing 

provisions that are adequate to ensure proper site stewardship in the long-term. 

Response: EPA acknowledges that many site-specific factors will influence the determination of

when the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for

this reason that EPA believes that individual UIC Directors, in consultation with operators, will be in

the best position to determine whether additional post-injection site care is needed. EPA expects this

decision to be made based on relevant site data and in consultation with all potentially impacted

parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that

under the final rule, a complete cessation of plume movement is not required; only a demonstration

that the plume and pressure front no longer pose a risk of endangerment to USDWs is required. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities.

Regarding establishing a framework for long-term stewardship, EPA clarifies that, once site closure
is authorized, the UIC program has no authority over a site. EPA clarifies that long-term liability for

GS sites is outside the scope of this rulemaking after a the CO2 plume has been demonstrated to no

longer pose an endangerment to USDWs and the site has been properly closed pursuant to §146.93.

Once an owner or operator has met all regulatory requirements under Part 146 for Class VI wells and

the Director has approved site closure pursuant to requirements at §146.93, the owner or operator

will generally no longer be subject to enforcement for regulatory noncompliance. 

Separate from EPA’s authority to enforce regulatory compliance, an owner or operator may be

subject to a §1431 response order even after proper site closure is approved under §146.93. Under

§1431 the Administrator may require an owner or operator to take necessary response measures if he

or she receives information that a contaminant is present or is likely to enter a public water system

or an USDW, which may present an imminent and substantial endangerment to the health of

persons, and the appropriate State and local authorities have not acted to protect the health of such

persons. The action may include issuing administrative orders or commencing a civil action for

appropriate relief against the owner or operator of a Class VI well. If the owner or operator fails to

comply with the order, they may be subject to a civil penalty for each day in which such violation

occurs or failure to comply continues.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24940

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

language 

Comment: Rule Provision: 146.93 

EPA Proposal: 13. Post-injection site care and site closure 

(a) The owner or operator of a Class VI well must prepare, maintain, and comply 

with a plan for post-injection site care and site closure that meets the 

requirements of paragraph (a)(2) of this section and is acceptable to the 

Director. 

(1) The owner or operator must submit the post-injection site care and site 

closure plan as a part of the permit application to be approved by the Director. 

GWPC Recommendations: Support the proposed EPA language 

Rationale: Agree with EPA’s rationale 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24942

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

language 

Comment: Rule Provision: 146.93(a)(2) 

(iii) A description of post-injection monitoring location, methods, and proposed 

frequency; and 
(iv) A proposed schedule for submitting post-injection site care monitoring 

results to the Director. 

GWPC Recommendations: Support the proposed EPA language. 

Rationale: Agree with EPA’s rationale. 

Response: EPA acknowledges the commenter’s support; the final rule retains this provision.

Comment Code: 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Individual Comments

Commenter Name: Karl R. Moor Letter ID: 0109

Commenter Organization: Southern Company, on behalf of Edison Electric

Institute (EEI)

Comment ID:

22003

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: EEI urges EPA to defer to site-specific characteristic wherever possible in the 

regulations. 

For example, the proposed regulations contemplate a 50-year post- injection site 

care period, but the UIC program director can require continued monitoring if he 

or she deems it necessary to protect underground sources of drinking water. In 

the notice of proposed rulemaking, EPA states that it is willing to consider 

other time frames for the post-injection site care period, but instead of a 

default, the Agency should let the characteristics of each site determine the 

appropriate length of time for post-injection site care. If the director has 

the discretion to vary the length of the monitoring period based on sitespecific characteristics, establishing a lengthy default period would place an 

unnecessary burden on those owners and operators who can show that their 

projects pose no threat to underground sources of drinking water in less than 50 

years. In fact, EEI and its members believe that appropriately sited CCS 

projects will be able to make such a demonstration in substantially less than 50 

years, perhaps only 10 years since data suggest that the risk profile of carbon 

dioxide injection tails off markedly after a decade. Consequently, a lengthy 

default period would penalize those owners and operators who have taken steps to 

ensure proper site characterization. Surely, EPA would rather reward - and, 

therefore, encourage - appropriate siting: Properly managed site 

characterization and operations are the best way to ensure the highest level of 

protection for underground sources of drinking water. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the final GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording
the Director discretion to allow a Class VI well owner or operator to demonstrate, based on

substantial data during the permitting process, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

Because of the variety of site-specific circumstances at GS sites, EPA believes that Directors, in

consultation with operators, will be in the best position to determine whether additional postinjection site care monitoring is needed (or whether the timeframe may be shortened), based on the

circumstances of a particular project. EPA expects this decision to be made based on relevant site

data and in consultation with all potentially impacted parties. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA agrees that proper site characterization is a critical component of ensuring that USDWs are

protected. However, EPA disagrees that this is a substitute for post-injection site care. EPA believes

that extensive post-injection monitoring is necessary to protect USDWs from endangerment. 

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

Commenter Name: George Holliday, PhD, PE, BCEE Letter ID: 0114

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 22522

Comment: A review of the existing technical literature suggests no author has considered 

how long sequestration is expected to last. Schlumberger says in their 

advertising, sequestration is "permanent" separation of CO2 from the near 

surface waters. Webster Unabridged Dictionary defines "permanent" as meaning 

unchanging, a very long time, to last indefinitely. Indefinitely is for ever 

without end. This appears to be an impossible assignment. Governments come and 

go, people come and to, and most importantly companies (permittees) come and go. 

The cost of carbon dioxide sequestrations monitoring until the end of time is a 

monumental expenditure. To circumvent this problem EPA states 50 years should 

be long enough, even though EPA offers no technical support for this claim. 

Then EPA says "not to worry," EPA will allow the non-technically trained 

Regional Director to lengthen or shorten the sequestration reservoir monitoring 

time based on his vast "inexperience". EPA offers no guidance to assist the 

untrained, non-engineer Regional Directors in making that determination. 

Response: EPA disagrees with this comment. In determining the post-injection site care -timeframe

for the proposed regulation, EPA reviewed industry reports, existing environmental programs, and

initial GS research studies. EPA provided a synthesis of pertinent results from GS modeling studies

in the preamble to the proposed regulation. Further explanation of this analysis was included in an

EPA-prepared background document that is available in the federal docket for the GS rule, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." Based on review of these

studies, modeling results indicate that the CO2 plume stabilization may occur on the timeframe of
10-100 years after the cessation of injection. EPA believes that a 50-year default post-injection site

care timeframe is a reasonable midpoint for most GS projects and available data, including data

submitted by commenters, do not support a different default timeframe, and has retained this in the

final regulation. To address concerns that, in some situations, it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs, the final

GS rule offers owners or operators flexibility regarding the duration of the PISC timeframe by: (1)

allowing the Director discretion to shorten or lengthen the PISC timeframe during the PISC period

based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the Director

discretion to allow a Class VI well owner or operator to demonstrate, based on substantial data

during the permitting process, that an alternative PISC timeframe may be appropriate if it ensures

non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA disagrees that the staff making determinations regarding whether to shorten or lengthen the

post-injection site care timeframe lack technical training for effective oversight of Class VI wells.

Most permitting authority staff have years of experience with the current UIC injection well classes

and have relevant specialties in geology, engineering, and related disciplines. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available on EPA's web

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

Commenter Name: George Holliday, PhD, PE, BCEE Letter ID: 0114

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 22533

Comment: EPA GUESSES AT THE REQUIRED CLASS VI MONITORING PERIOD 

EPA at 73 FR 43518 - 43527 discusses how EPA decided to monitor a sequestration 

project for 50 years. EPA said 50 years is a long time and if EPA extends the 

time longer the cost will be too high! EPA provide no rational argument for 

selecting 50 years: EPA says at 73 FR 43519, "EPA is tentatively proposing a 

post-injection site care (monitoring) period of 50 years with Director’s 

discretion to change that period to lengthen or shorten the 50- year period, if 

appropriate." The best support EPA offers (73 FR 43520) for the 50 year 

monitoring period is: 

"To ensure that the post-injection site care monitoring timeframe is long enough 

to determine that there is no threat of endangerment to USDWs from injection 

activities; EPA is proposing a default post-injection site care period of 50 
years. During this 50-year period, the owner or operator would be required to 

submit periodic reports providing monitoring results and updated modeling 

results as appropriate until a demonstration of non-endangerment to USDWs can be 

made." 

EPA is willing to rely on a technically untrained Regional Administrator 

counseled by uncertified EPA employees, because EPA does not have technical 

know-how to determine the appropriate monitoring time period! We question the 

probability of speculators being in business 50 years after the injectors stop 

producing income and become a liability. Since EPA is charged only with 

protecting USDWs and not human life, EPA can, by default, slough the real 

burden, e.g., protecting human life, onto some other agency. In our opinion 

this is an Arbitrary and Capricious and a life threatening action on the part of 

EPA. 

Response: As described above, EPA disagrees with this comment. In determining the post-injection

site care-timeframe for the proposed regulation, EPA reviewed industry reports, existing

environmental programs, and initial GS research studies. EPA provided a synthesis of pertinent

results from GS modeling studies in the preamble to the proposed regulation. Further explanation of

this analysis was included in an EPA-prepared background document that is available in the federal

docket, titled "Computational Modeling of Underground Injection of Carbon Dioxide for

Determination of Area-of-Review and Potential Risk to Underground Sources of Drinking Water."

Based on review of these studies, modeling results indicate that the CO2 plume stabilization may

occur on the timeframe of 10-100 years after the cessation of injection. EPA believes that a 50-year

default post-injection site care timeframe is a reasonable midpoint for most GS projects and

available data, including data submitted by commenters, do not support a different default timeframe,

and has retained this in the final regulation. 

EPA disagrees that the staff making determinations regarding whether to shorten or lengthen the

post-injection site care timeframe lack technical training for effective oversight of Class VI wells.

Most permitting authority staff have years of experience with the current UIC injection well classes

and have relevant specialties in geology, engineering, and related disciplines. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available on EPA's web

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

Commenter Name: Iain Wright Letter ID: 0118

Commenter Organization: BP Alternative Energy Comment ID: 22068

Comment: My third and final point concerns the appropriate timeframe for site closure. 

There is no rational basis to mandate a universal, 50-year minimum timeframe for 

post-injection site care. Such a mandate would kill-off commercial investment in 

geo-sequestration projects. Worse than that, it would preferentially kill-off 

the best sites - those with proven seals and the lowest risk of leakage - oil 
and gas fields. 

As the EPA proposal states - the actual time for CO2 plume stabilization will be 

very "site-specific". A well-selected and managed sequestration site (such as an 

oil or gas field) that has met its performance objectives (including plume 

stabilization) will be much more secure and could be closed quickly (say a 

couple of years). However, (as EPA’s cited examples show), CO2 injected in a 

poorly-confined deep saline formation could move around for quite a while such 

that the closure period will have to wait on residual and solubility trapping, 

and hence, a closure period of several years could be more appropriate. WE 

RECOMMEND THAT EPA DOES NOT MANDATE ANY FIXED TIMEFRAME FOR SITE

CLOSURE. BETTER 

WOULD BE A SITE-SPECIFIC ASSESSMENT THAT IS RISK AND PERFORMANCE BASED. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the final GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording

the Director discretion to allow a Class VI well owner or operator to demonstrate, based on

substantial data during the permitting process, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24739

Comment: - The Proposal’s default 50-year post-injection monitoring period, while 

groundwater monitoring for a Class I hazardous waste injection well is required 

only until the injection zone pressure is such that USDWs cannot be impacted. 

Response: The GS regulations have been tailored to these unique characteristics of GS injection

wells. EPA developed the Class VI regulations in recognition that the risks posed by GS to USDWs

are fundamentally different than those associated with current injection practices regulated by the

UIC program, including Class I hazardous waste injection wells. For example, CO2 is more buoyant,

less viscous (i.e., more mobile), and in some cases more corrosive than fluids injected into Class I

hazardous waste wells. In addition, the large injection volumes anticipated for GS will likely be

much greater than current injection practices. Lastly, CO2 movement in the subsurface is not as well

understood as fluids currently injected under the Class I program.
In combination, these unique characteristics result in CO2 plumes that may be highly mobile in the

subsurface and move vertically upwards. There will also be some unavoidable levels of uncertainty

as to the direction and speed of plume movement during and after injection. EPA-funded research by

Lawrence Berkeley National Laboratory has shown in preliminary modeling studies of ideal basins

for GS that pressure perturbations great enough to force saline fluids into USDWs may cover large

areas compared to current injection projects (10s to 100s km2). This research report, entitled

"Research Project on CO2 Geological Storage and Groundwater Resources: Large-Scale

Hydrological Evaluation and Modeling of the Impact on Groundwater Systems," is available in the

rulemaking docket. EPA developed regulations that would appropriately address the larger the area

influenced by a GS project, and the resultant, higher likelihood that there may be potential faults,

fractures, or abandoned wells that could act as a conduit for USDW contamination. Furthermore, a

level of site-characterization typical for Class I hazardous waste injection wells will be extremely

difficult over these vast areas.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24754

Comment: 7. EPA should provide for performance-based requirements for Closure and Post 

Closure Care. For example, the appropriate length of time for post-injection 

site care should be determined by specific conditions and characteristics of the 

site, and monitoring of the pressure to determine the point at which the 

injection zone pressure is such that USDWs cannot be impacted. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the final GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the PISC period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, based on substantial data during the permitting process, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24802

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

language; 5220 2.8.2.1 Post-injection monitoring activities 

Comment: (b) THE OWNER OR OPERATOR MUST Must monitor the site following the

cessation 

of injection to show the position of the carbon dioxide plume and pressure front 
and demonstrate that USDWs are not being endangered. 

(1) THE OWNER OR OPERATOR MUST Must continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site closure 

plan for THE PERIOD OF TIME at least 50 years following the cessation of 

injection . At the Director's discretion, the monitoring will continue until 

THE DIRECTOR DETERMINES THAT the geologic sequestration project no longer poses 

an endangerment to USDWs. 

Response: EPA disagrees with the suggested edits. However, EPA agrees with commenters that

there will be circumstances where it can be demonstrated in less than 50 years that the plume and

pressure front no longer pose a risk of endangerment to USDWs. For this reason, the final GS rule

offers owners or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing

the Director discretion to shorten or lengthen the PISC timeframe during the PISC period based on

site-specific data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to

allow a Class VI well owner or operator to demonstrate, based on substantial data during the

permitting process, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24804

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

language; 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: (4) If such a demonstration cannot be made after the 50-year period, must 

submit to the Director a plan to continue post-injection site care.

{See comment above.} 

Response: As described above, the post-injection site care timeframe may be reduced by the

Director if the owner or operator can demonstrate that the remaining pressure front and plume no

longer pose a risk of endangerment to USDWs. The non-endangerment finding is left to the

discretion of the Director, based on site-specific information such as plume movement, pressure

decay, and the location of potential leakage pathways. As suggested by the commenter, a complete

cessation of plume movement is not required, only a demonstration that the plume and pressure front

no longer pose a risk of endangerment to USDWs, as specified in §146.93(b)(2-4). EPA retains this

provision in the final GS regulation 

GS rule also offers owners or operators flexibility regarding the duration of the PISC timeframe by

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, based on

substantial data during the permitting process, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust
the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24974

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

language; 5220 2.8.2.1 Post-injection monitoring activities 

Comment: (2) If the owner or operator can demonstrate to the satisfaction of the 

Director before 50 years, based on monitoring and other site-specific data, that 

the GS project no longer poses an endangerment to USDWs, the Director may 

approve an amendment to the post-injection site care and site closure plan to 

reduce the frequency of monitoring or may authorize site closure before the end 

of the 50-year period.

{The period of time an owner or operator is required to conduct post-closure 

care monitoring should be based on the ability of the pressure to cause 

endangerment of USDWs. A 50-year post-closure care monitoring period is 

unprecedented and implies that CO2 presents a greater risk than it does. RRC 

suggests that EPA strike the phrase "for at least 50 years" and make the time 

for continued monitoring be based on site specific data. } 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances,

which is why EPA is providing the Director discretion to approve an alternative post-injection site

care timeframe as long as the owner or operator can meet the requirements provided at §146.93(c).

EPA acknowledges there will be circumstances where it can be demonstrated in less than 50 years

that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this reason,

the GS rule offers owners or operators flexibility regarding the duration of the PISC timeframe by:

(1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the postinjection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the

permitting process based on substantial data, that an alternative PISC timeframe may be appropriate
if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Jonathan Pershing Letter ID: 0124

Commenter Organization: World Resources Institute (WRI) Comment ID: 23043

Comment: Despite the many consistencies, there are a few important technical differences 

which are outlined in the GHGT-9 paper. These differences include the definition 

of faults that pose risk of leakage, injection pressure limits, well 

construction requirements and capacity estimates, as well as the differences in 

definition of the post-injection phases of a project. On this last item, EPA 

proposes a default 50- year monitoring time-frame, while the CCS Guidelines 

require an operator to demonstrate (via six criteria) that the site no longer 

poses a danger to human health or the environment, rather than using a default 

timeframe. This approach was taken because of the expected difference in the 

time it may take the CO2 plume to stabilize among sites. The CCS Guidelines also 

mention a more detailed framework for what happens after an operator is no 

longer responsible for a site. Specifically, the CCS Guidelines encourage 

stewardship of a site by an entity that would be responsible for any needed 

monitoring, maintenance of a site, and establishment and operation of a registry 

for information about CCS sites. 

Response: EPA acknowledges that there will be circumstances where it can be demonstrated in less

than 50 years that the plume and pressure front no longer pose a risk of endangerment to USDWs.

For this reason, the final GS rule offers owners or operators flexibility regarding the duration of the

PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe

during the PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, based on

substantial data during the permitting process, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for
post-injection site care is necessary. A 50 year post-injection site care timeframe represents a

reasonable and protective monitoring period based on a review of research studies, industry reports,

and existing environmental programs, and evaluation of public comments.

Commenter Name: Sam Kitto Letter ID: 0126

Commenter Organization: National Tribal Air Association Comment ID: 23045

Comment: Monitoring 

Aside from how the GS rules addresses hazardous substances, the rule includes a 

default monitoring period of 50-years after closure of an injection well, 

Unfortunately, the EPA provides no objective, technical rationale as to how it 

arrived at this monitoring period, such as an engineering analysis, and gets 

around it by giving discretion to Agency Regional Administrators or 

jurisdictions with primacy for UIC programs for shortening or lengthening the 

monitoring period on a case-by-case basis. While the NTAA agrees that there 

should be such discretion with respect to defining post-closure monitoring 

periods for injection wells, it should involve substantive input by qualified 

engineers trained in geologic sequestration. Otherwise, USDWs could end up being 

adversely impacted as a result of monitoring periods improperly defined by 

unqualified individuals. 

The NTAA therefore recommends that an objective, technical rationale be provided 

for deciding upon the 50-year monitoring period. In addition, our organization 

Response: EPA disagrees with this comment. In determining the post-injection site care-timeframe

for the proposed regulation, EPA reviewed industry reports, existing environmental programs, and

initial GS research studies. EPA provided a synthesis of pertinent results from GS modeling studies

in the preamble to the proposed regulation. Further explanation of this analysis was included in an

EPA-prepared background document that is available in the federal docket for the GS rule, titled

Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water. Based on review of these

studies, modeling results indicate that the CO2 plume stabilization may occur on the timeframe of

10-100 years after the cessation of injection. EPA believes that a 50-year default post-injection site

care timeframe is a reasonable midpoint for most GS projects and available data, including data

submitted by commenters, do not support a different default timeframe, and has retained this in the

final regulation. To address concerns that, in some situations, it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs, the GS

regulation includes a provision that the Director may, at his or her discretion shorten or lengthen the

post-injection site care timeframe if the owner or operator can demonstrate that the GS project does

not pose a risk to USDWs, as specified in §146.93(b)(2). 

Alternatively, the final rule at §146.93(c), also allows the Director to approve an alternative postinjection site care timeframe where an owner or operator can demonstrate during the permitting

process that an alternative post-injection site care timeframe, other than the 50 year default, is

appropriate and ensures non-endangerment of USDWs. The demonstration must be based on sitespecific information, including the results of site-specific computational modeling; the predicted

timeframe for pressure decline; the predicted rate of carbon dioxide plume migration; site-specific

chemical processes that will result in carbon dioxide trapping; the predicted rate of carbon dioxide

trapping; characterization of the confining zone(s); laboratory analyses or studies to verify the
information on trapping; the presence of potential conduits for fluid movement and the quality of

abandoned well plugs within the AoR; the distance between the injection zone and the USDWs

above and/or below the injection zone; and any additional site-specific factors determined by the

Director. The demonstration must meet the criteria at §146.93(c)(2) for ensuring the quality and

accuracy of the data and models on which the demonstration is based. This demonstration would be

submitted as part of the permit application, per §146.82(a)(18), in addition to the PISC and site

closure plan required at §146.82(a)(17). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Because of the variety of site-specific circumstances at GS sites, EPA believes that Directors, in

consultation with operators, will be in the best position to determine whether additional postinjection site care monitoring is needed (or whether the timeframe may be shortened), based on the

circumstances of a particular project. EPA expects this decision to be made based on relevant site

data and in consultation with all potentially impacted parties. EPA agrees that qualified scientists and

engineers should be included in any decision to lengthen or shorten the post-injection site care

monitoring period, but is not requiring this at §146.93.

Commenter Name: George Holliday, PhD, PE, BCEE Letter ID: 0127

Commenter Organization: Holliday Environmental Services, Inc. Comment ID: 23056

Other EPA Comment Codes and Descriptions: 6210 3.2.1 Comments on the timeframe of the

costing analysis (seeking comment) 

Comment: C: WITHOUT TECHNICAL SUPPORT, EPA REQUIREs 50 YEARS OF

MONITORING EXECPT BY 

SAYING MORE MONITORING IS EXPENSIVE. 

1. Sequestration of CO2 is forever, or we don’t need capture the CO2 in the 

first place. If the CO2 escapes the Earth the World population is doomed, in 

accordance with the IPPC theory. 

2. EPA provides no justification for selecting 50 years, in fact the proposed 

rule states the economic contractor was told to develop the cost on the basis of 

25 years. 

3. It is unclear if the cost is based on 25 or 50 years. 

Response: EPA disagrees that the monitoring timeframe was selected based on cost. In determining

the post-injection site care-timeframe for the proposed regulation, EPA reviewed industry reports,

existing environmental programs, and initial GS research studies. EPA provided a synthesis of

pertinent results from GS modeling studies in the preamble to the proposed regulation. Further

explanation of this analysis was included in an EPA-prepared background document that is available

in the federal docket for the GS rule, titled "Computational Modeling of Underground Injection of

Carbon Dioxide for Determination of Area-of-Review and Potential Risk to Underground Sources of
Drinking Water." Based on review of these studies, modeling results indicate that the CO2 plume

stabilization may occur on the timeframe of 10-100 years after the cessation of injection. EPA

believes that a 50-year default post-injection site care timeframe is a reasonable midpoint for most

GS projects and available data, including data submitted by commenters, do not support a different

default timeframe, and has retained this in the final regulation. 

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Emily Rochon Letter ID: 0129

Commenter Organization: Greenpeace International Comment ID: 23073

Comment: water reservoir and pose the most severe risk to the water supply. Another part 

of the proposal that we support is the language detailing the procedure for 

post-closure site care. It is key that after a carbon storage site is closed 

that it continues to be monitored and we support the 50-year timeframe written 

in the proposal. Greenpeace however could not be supportive of any length of 

time shorter than this or any potential allowance for early termination of the 

ost-closure site care. 

Response: EPA agrees with commenters that a 50 year post-injection site care timeframe represents

a reasonable and protective post-injection site monitoring period in most cases and available data,

including data submitted by commenters, do not support a different default timeframe. EPA bases

this on a review of research studies, industry reports, and existing environmental programs, and

evaluation of public comments. Furthermore, EPA believes that a 50-year default post-injection site

care timeframe is not overly burdensome, does not exaggerate the risks associated with GS, is

consistent with other environmental programs, and sufficiently protects USDWs from endangerment.

For this reason, the final GS regulation retains the 50 year post-injection site care timeframe, as

specified in §146.93(b)(1).

However, EPA disagrees that a 50 year post-injection site care timeframe should be an absolute

minimum. Rather, EPA believes, as some commenters suggest, that there will be circumstances

where it can be demonstrated in less than 50 years that the plume and pressure front no longer pose a

risk of endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to
requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts as the commenter

suggests.

Commenter Name: Carl Carlsson Letter ID: 0131

Commenter Organization: SUEZ Energy Generation NA, LLC Comment ID: 21537

Comment: Post-injection Site Care 

SEGNA disagrees with EPA's proposal to lengthen the post-injection site 

monitoring period to 50 years versus the current 30 year standard. EPA has 

provided insufficient justification for such an extension, which will add significant 

costs and adversely impact sequestration projects and their ability to obtain 

financing. As it currently reads, the proposed rule has provisions for extending 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket for the GS

rule, titled "Computational Modeling of Underground Injection of Carbon Dioxide for Determination

of Area-of-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed

various default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances.

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is
anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

To the commenters who expressed concern about the cost of post-injection site care, EPA does not

agree that post-injection site care timeframes longer than 30 years will be prohibitively expensive. In

fact, EPA believes that post-injection site care monitoring will represent a relatively minor

component of total project cost, and will provide an essential level of protection from endangerment

for USDWs. A discussion of the costs attributed to monitoring technologies (used during injection

and the post-injection site care timeframes) is available in the Technology and Cost Document for

the GS rule, which is in the federal docket for this rulemaking. EPA believes that it is logical to

make use of existing monitoring infrastructure at a GS site in order to ensure USDWs are not

endangered. 

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: 21659

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: - Section 146.93(b)(1) "The owner or operator shall continue to conduct 

monitoring as specified in the Director-approved post-injection site care and 

site closure plan for at least 50 years following the cessation of injection. At 

the Director's discretion, the monitoring will continue until the geologic 

sequestration project no longer poses an endangerment to USDWs." 

Response/Discussion: The SWP recommends adopting a performance-based approach to 

the site care period so that each site is monitored for as long as necessary, 

but not longer than necessary in order to avoid an extra cost burden to 

regulators and owners/operators. The required site-specific "post-injection site 

care and site closure plan" appears sufficient to convey appropriate monitoring 

techniques and timescales to the EPA Director. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on
data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA acknowledges the commenter’s support of the post-injection site care and site closure plan; the

final GS regulation retains this provision.

Commenter Name: Robert Bessette Letter ID: 0139

Commenter Organization: Council of Industrial Boiler Owners (CIBO) Comment ID: 23085

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

Long-Term Care Requirements 

Comment: 

The 50-year post-closure period for continuing liability, from a practical 

perspective, is not workable. For example, some CIBO members generate power for 

a range of applications. It is difficult to imagine a generator taking on 

liability that would include the construction of a generating plant, the long 

term operation of that plant, and then the 50-year period after closing the well 

site. Compounding that difficulty is the possibility that the closure of the 

well does not coincide with the shut down of the power plant, potentially 

extending liability to 100 years or beyond, per the discretion of the 

Director.[FN7 73 Fed. Reg. 43519-20.] This raises the question of why a company 

would take on a 100-year liability that is essentially out of their control and 

not really a part of their business. The insurance issue is also a major 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. 

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).
EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA also recognizes the concerns associated with ensuring financial responsibility for the long time

frames over which post-injection site care will be conducted. EPA is developing guidance on

financial responsibility to assist owners or operators in evaluating the requirements of §146.85 and to

assist Directors in evaluating financial responsibility demonstrations. The guidance describes the

types of financial mechanisms that operators may choose to use when evaluating the financial

responsibility requirements for GS wells and it will also include a section on recommended

approaches to estimate costs to support accurate financial responsibility demonstrations. The

guidance will be available at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

As described above, the GS regulation applies to the owner or operator of the GS project, not the

generator of the CO2. 

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

Commenter Organization: Global Energy, Inc. Comment ID: 23099

Other EPA Comment Codes and Descriptions: 3820 2.3.1 Well construction procedures 

Comment: 1.Global strongly believes that excessive rigor in siting and well installation 

criteria, as well as post closure care and financial assurance for 50-years, 

would adversely impact acceptance of the program as well as the speed with which 

large (meaningful) scale carbon management develops. 

We appreciate the challenge in balancing security of sequestration. However 

advocating proven and reliable applications based on use of oil & gas based 

technology should be adequate to ensure long-term safety and reliability. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive or that it

overstates the risk of GS. EPA proposed a default post-injection site care timeframe of 50 years

based on a review of research studies, industry reports, and existing environmental programs. This

analysis was included in an EPA-prepared background document that is available in the federal

docket, titled Computational Modeling of Underground Injection of Carbon Dioxide for

Determination of Area-of-Review and Potential Risk to Underground Sources of Drinking Water.

EPA assessed various default timeframes based on additional review of research studies and

evaluation of public comments. While numerous commenters suggested that EPA shorten the

monitoring timeframe, none of the commenters provided sufficient data or other evidence to warrant

a change in the proposed timeframe. While the 10- or 30-year timeframe suggested by some of these

commenters may be within the timeframe suggested in some studies, EPA believes that the potential

risks of endangering USDWs will likely not decline within these timeframes and available data,
including data submitted by commenters, do not support a different default timeframe.

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

To the comment about the cost of post-injection site care, EPA does not agree that post-injection site

care timeframes longer than 30 years will be prohibitively expensive. In fact, EPA believes that postinjection site care monitoring will represent a relatively minor component of total project cost, and

will provide an essential level of protection from endangerment for USDWs. A discussion of the

costs attributed to monitoring technologies (used during injection and the post-injection site care

timeframes) is available in the Technology and Cost Document for the GS rule, which is in the

federal docket for this rulemaking. EPA believes that it is logical to make use of existing monitoring

infrastructure at a GS site in order to ensure USDWs are not endangered. 

EPA also recognizes the concerns associated with ensuring financial responsibility for the long time

frames over which post-injection site care will be conducted. EPA is developing guidance on

financial responsibility to assist owners or operators in evaluating the requirements of §146.85 and to

assist Directors in evaluating financial responsibility demonstrations. The guidance describes the

types of financial mechanisms that operators may choose to use when evaluating the financial

responsibility requirements for GS wells and it will also include a section on how to estimate costs to

support accurate financial responsibility demonstrations. The guidance will be available at

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

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

purpose of enhanced recovery and that many of the wells used for ER may be suitable for GS.

However, EPA believes that GS is sufficiently different from Class II ER operations to warrant the

tailored construction requirements for Class VI wells at §146.86. For example, the volume of CO2

anticipated to be injected in Class VI wells is significantly greater than for Class II wells. Reservoir

pressure conditions will be different, with Class VI injection operations involving large volumes of
CO2 and likely having higher pressures within their storage formations than Class II ER projects.

Therefore, Class VI GS reservoir pressures will increase more in comparison to Class II ER during

the injection phase of the GS project.

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

Commenter Organization: Global Energy, Inc. Comment ID: 23100

Comment: Our view is that the likelihood of leakage from a GS well is relatively low, 

making 50-years of post closure monitoring wholly unreasonable. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive or

unreasonable. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. 

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts, as the commenter

suggests.

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

Commenter Organization: Global Energy, Inc. Comment ID: 23106

Comment: BUT, once that is done, the closure, post-closure and long-term care and 

monitoring (50-years of financial responsibility) with attendant financial 

responsibility, needs to be significantly relaxed and made much more reasonable. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a
review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. 

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts, as the commenter

suggests.

To the comment expressing concern about financial responsibility, EPA recognizes that there are

challenges associated with ensuring funding for activities that will occur far in the future. However,

the Agency believes that in order to protect USDWs from endangerment under the SDWA owners or

operators must demonstrate under §146.85 that financial resources are available to plug the injection

well and provide post-injection site care at the point in time that the first CO2 is injected.

Commenter Name: Christine Reimer Letter ID: 0142

Commenter Organization: National Ground Water Association Comment ID: 22614

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

language 

Comment: Proposed Rule: 146.93(b)(1) 

Proposed revision: (1) The owner or operator shall continue to conduct 

monitoring as specified in the Director-approved post-injection site care and 

site closure plan for at least 30 years following the cessation of injection. 

At the Director's discretion, the monitoring will continue until the geologic 

sequestration project no longer poses an endangerment to USDWs. 

Rationale: NGWA believes some number should be included. 30 years is a number 

used in other EPA programs. The next question was whether the burden should be 
placed on the director to justify the longer number or on the operator to prove 

the site is stabilizing. It is suggested that the director be allowed to 

approve both a shorter or longer timeframe. With the next subsection, the 

burden is placed on the owner or operator to prove a shorter timeframe is 

acceptable, while allowing in this subsection the director to require monitoring 

beyond 30 years. 

Proposed Rule: 146.93(b)(2) 

Proposed revision: (2) If the owner or operator can demonstrate to the 

satisfaction of the Director that the geologic sequestration project no longer 

poses an endangerment to USDWs, the Director may approve an amendment to the 

post-injection site care and site closure plan to reduce the frequency of 

monitoring or may authorize site closure before the end of the 30-year period. 

Rationale: Makes this subsection compatible with 30 year timeframe proposed by 

NGWA in 146.93(b)(1) 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. 

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts, as the commenter

suggests. 
Commenter Name: Patrick Nugent Letter ID: 0143

Commenter Organization: Texas Pipeline Association (TPA) Comment ID: 23131

Comment: 2. The proposed post-closure care period similarly spans an unrealistic and 

unnecessarily lengthy period of time. TPA disagrees with the imposition of a 

default 50-year post-injection site care period. As stated in the preceding 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. 

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts, as the commenter

suggests.

Commenter Name: Patrick Nugent Letter ID: 0143

Commenter Organization: Texas Pipeline Association (TPA) Comment ID: 23132

Comment: default 50-year post-injection site care period. As stated in the preceding 

comment, TPA urges the provision of flexible, site-specific requirements 

concerning the length of the post-injection site care period that coincide with 

the timeframe established for financial assurance. A blanket 50-year period 

Response: As stated above, EPA disagrees that a post-injection site care timeframe of 50 years is

excessive for most Class VI wells. However, EPA recognizes that there may be sites where the 50

year post injection site care timeframe may be either not appropriate or more burdensome than

necessary based on site-specific conditions. For this reason, the GS rule offers owners or operators

flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to
shorten or lengthen the PISC timeframe during the post-injection period based on site-specific data,

pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI

well owner or operator to demonstrate, during the permitting process based on substantial data, that

an alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs

pursuant to requirements at §146.93(c).

EPA clarifies that owners or operators will need to demonstrate and maintain financial responsibility

throughout the post-injection site care period, as required at 146.85. EPA recognizes that there are

challenges associated with ensuring funding for activities that will occur far in the future. However,

the Agency believes that in order to protect USDWs from endangerment under the SDWA operators

must demonstrate under §146.85 that financial resources are available to plug the injection well and

provide post-injection site care at the point in time that the first CO2 is injected.

Commenter Name: Patrick Nugent Letter ID: 0143

Commenter Organization: Texas Pipeline Association (TPA) Comment ID: 23133

Comment: the timeframe established for financial assurance. A blanket 50-year period 

would unduly discourage the use of geologic sequestration technology and reduce 

the number of willing participants in this program. Creation of a default period 

of 50 years would discourage investment in geologic sequestration technology, 

and it might also remove the incentive to locate and develop storage sites with 

the most favorable conditions. While EPA has provided a mechanism to reduce this 

time frame on a case-by-case basis, the imposition of a default 50-year postinjection site care period by itself could deter many otherwise-willing 

participants. Accordingly, TPA recommends that EPA provide that the postResponse: EPA recognizes that there are challenges associated with assuring funding for activities

that will occur far in the future. However, the Agency believes that operators must demonstrate that

financial resources are available to plug the injection well and provide post-injection care at the point

in time that the first CO2 is injected. EPA is developing guidance on financial responsibility to assist

owners or operators in evaluating the requirements of §146.85 and to assist Directors in evaluating

financial responsibility demonstrations. The guidance describes the types of financial mechanisms

that operators may choose to use when evaluating the financial responsibility requirements for GS

wells and it will also include a section on how to estimate costs to support accurate financial

responsibility demonstrations. The guidance will be available at

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

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

Commenter Name: Patrick Nugent Letter ID: 0143

Commenter Organization: Texas Pipeline Association (TPA) Comment ID: 23134

Comment: participants. Accordingly, TPA recommends that EPA provide that the postinjection site care period be established on a case-by-case basis as a part of 

the permitting process. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC
timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; demonstrate the appropriateness of

an alternative post-injection site care time frame; perform post-injection monitoring; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

http://www.epa.gov/safewater/wells_sequestration.html.

Commenter Name: William Kovacs Letter ID: 0148

Commenter Organization: U.S. Chamber of Commerce Comment ID: 21775

Comment: Consider that the proposed regulations contemplate a 50-year post-injection site 

care period. EPA’s reasoning for proposing this time frame is based on CO2 plume 

stabilization and protection of USDWs. EPA attempts to ameliorate the harshness 

of this time frame by stating that the UIC program director can modify it under 

certain circumstances. A better approach would be to allow the characteristics 

of each site determine the appropriate length of time for post-injection site 

care. This would prevent placing an unnecessary burden on those owners and 

operators who can show that their projects pose no threat to underground sources 

of drinking water in less than 50 years. In fact, the Chamber believes that 

appropriately sited CCS projects will need substantially less than 50 years, 

especially since research suggests that the risk profile of carbon dioxide 

injection diminishes dramatically after a decade. Consequently, a lengthy postinjection care period would only serve to penalize those owners and operators 

who have taken steps to ensure proper site characterization. 

As a result, the 50-year timeframe (if retained in the final rule) could have an 

inhibiting effect on insurers, investors, owners, and operators hoping to 

participate or invest in CCS activities. 

Response: EPA agrees that some owners or operators will be able to demonstrate, in less than 50

years, that the pressure front and plume no longer pose a risk of endangerment to USDWs. However,
based on studies, EPA believes that the 50 year default time frame is warranted in most cases based

on additional review of research studies and reports and evaluation of public comments. 

EPA believes that the best way to address all possibilities, while ensuring USDW protection from

endangerment, is to set a 50 year default post-injection site care timeframe, with flexibility to: (1)

allow the Director discretion to shorten or lengthen the PISC timeframe during the PISC period

based on site-specific data, pursuant to requirements at §146.93(b); or (2) afford the Director

discretion to allow a Class VI well owner or operator to demonstrate, based on substantial data

during the permitting process, that an alternative PISC timeframe may be appropriate if it ensures

non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA does not believe that performing the demonstration before 50 years places an additional burden

on these owners or operators. EPA clarifies that all operators will need to make this demonstration

prior to the Director authorizing site closure; the difference is that some operators will be performing

the demonstration earlier than others. As indicated by the commenter, ideally this demonstration will

be part of an ongoing communication between the owner or operator and the UIC Director. If an

owner or operator believes that an earlier demonstration will be burdensome, nothing in the GS rule

requires them to make the demonstration prior to 50 years. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Larry Myer Letter ID:

0149

Commenter Organization: Lawrence Berkeley National Laboratory (Berkeley Lab)

U.S. Department of Energy (DOE)

Comment ID:

21797

Comment: A 50 year site care period is unnecessary and certainly impractical, and should 

be removed from the rule. It is unlikely that any owner/operator would, or 

could, provide assurance of its ability to take responsibility for the fate of 

the CO2 for 50 years. The risks associated with storage decrease rapidly after 

injection stops because of stabilization of the plume and dissipation of 

pressure, so the concept of linking post-injection site care to plume 

stabilization and pressure decrease is a good one. However, there is not 

sufficient knowledge at this time to quantify the required time. It is known 

that the time required for trapping processes, such as residual gas trapping, to 

immobilize the plume varies, so a single number for the site care period is not 

appropriate in any event. Given the current state of knowledge the rule should 

only state that the operator should demonstrate at closure that the plume has 

sufficiently stabilized and pressure decreased so as to not adversely impact the 

USDW. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive or

unnecessary in most cases. EPA proposed a default post-injection site care timeframe of 50 years

based on a review of research studies, industry reports, and existing environmental programs. This
analysis was included in an EPA-prepared background document that is available in the federal

docket, titled Computational Modeling of Underground Injection of Carbon Dioxide for

Determination of Area-of-Review and Potential Risk to Underground Sources of Drinking Water.

EPA assessed various default timeframes based on additional review of research studies and

evaluation of public comments. While numerous commenters suggested that EPA shorten the

monitoring timeframe, none of the commenters provided sufficient data or other evidence to warrant

a change in the proposed timeframe. While the 10- or 30-year timeframe suggested by some of these

commenters may be within the timeframe suggested in some studies, EPA believes that the potential

risks of endangering USDWs will likely not decline within these timeframes and available data,

including data submitted by commenters, do not support a different default timeframe. 

EPA acknowledges that some studies indicate that trapping may begin in less than 50 years, as the

commenter notes; however, this trapping may also take up to hundreds or thousands of years to be

complete (IPCC, 2005). If this trapping is not complete, the potential for USDW endangerment still

exists as CO2 may persist as a buoyant plume. EPA therefore believes that to ensure USDW

protection from endangerment, a default timeframe for post-injection site care will be necessary in

most cases. The default 50 year post-injection site care timeframe represents a reasonable and

protective monitoring period based on a review of research studies, industry reports, and existing

environmental programs, and evaluation of public comments.

However, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording

the Director discretion to allow a Class VI well owner or operator to demonstrate, based on

substantial data during the permitting process, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA recognizes that there are challenges associated with assuring funding for activities that will

occur far in the future. However, the Agency believes that in order to protect USDWs from

endangerment under the SDWA, operators must demonstrate under §146.85 that financial resources

are available to plug the injection well and provide post-injection site care at the point in time that

the first CO2 is injected.

To the comment about the cost of post-injection site care, EPA does not agree that post-injection site

care timeframes longer than 30 years will be prohibitively expensive. In fact, EPA believes that postinjection site care monitoring will represent a relatively minor component of total project cost, and

will provide an essential level of protection from endangerment for USDWs. A discussion of the

costs attributed to monitoring technologies (used during injection and the post-injection site care

timeframes) is available in the Technology and Cost Document for the GS rule, which is in the

federal docket for this rulemaking. EPA believes that it is logical to make use of existing monitoring

infrastructure at a GS site in order to ensure USDWs are not endangered.
Commenter Name: Brianne Metzger Letter ID: 0151

Commenter Organization: Spectra Energy Corp Comment ID: 21879

Comment: B. EPA’s Selection Of A 50-Year Post-Injection Site Care Period Is Arbitrary. 

Spectra respectfully disagrees with EPA’s selection of a 50-year default 

timeframe. As an alternative, Spectra recommends that EPA adopt a postinjection site care period of 30 years, similar to that used under RCRA for 

post-closure care for hazardous waste management units, 40 C.F.R. § 264.117, 

after which time all responsibility and liability would transfer to the State. 

The Director should be granted discretion to shorten this timeframe upon a 

showing that certain performance criteria are met that indicate USDWs are not 

at any recognizable risk, as discussed more fully above.[15] 

A 30-year timeframe with Director discretion to shorten represents a better 

approach because it provides greater regulatory certainty for owners and 

operators, financiers, insurers, and other entities involved in CCS projects.[16] 

By contrast, a 50-year period that could be extended or reduced depending upon 

periodic assessments of the CO2 plume creates significant uncertainty, 

subjecting owners and operators to a post-injection site care period that 

either could end at any time after approximately 10 years or continue 

indefinitely up to and beyond 100 years. In practice, it is far easier for 

owners and operators to plan for a 10-year period with the possibility of an 

extension than a 50-year period that could fluctuate in either direction at the 

Agency’s discretion, as discussed more fully above. 

Furthermore, with respect to USDW endangerment, projects with plumes likely to 

stabilize within 10 years represent the safest types of projects. A 50-year 

post-injection site care period would place an undue regulatory and financial 

burden on these safest of projects. Even with Director discretion to shorten 

this time period, owners and operators nevertheless would have to plan for a 

post-injection site care period of at least 50 years, significantly affecting 

the prospective costs of the project. By comparison, a 30-year timeframe with 

Director discretion to shorten would seem to favor the development of projects 

likely to have CO2 plumes that stabilize early and avoid an unnecessarily long 

post-injection site care period. Similarly, the potential of reduced 

regulatory and financial burdens that would accompany a 30-year period with 

Director discretion to shorten creates incentives for project owners and 

operators to develop and manage projects in a way that maximizes the likelihood 

of the CO2 plume stabilizing early. 

For the foregoing reasons, the EPA’s 50-year post-injection site care period is 

arbitrary and risks adding to the barriers and obstacles that are currently 

preventing commercial-scale deployment of CCS. A 30-year period with Director 

discretion to shorten would provide the same level of protection for USDWs 

while minimizing regulatory and financial burdens on site owners and operators. 

C. After The Post-Injection Site Care Period And Determination That The CO2 

Plume Has Stabilized, Owners And Operators Should Be Released From All Site Care 

Responsibility, Such As Monitoring And Verification Requirements, And Any 

Financial Assurance Instruments Should Be Released. 
The GS Rule provides that owners or operators must demonstrate and maintain 

financial responsibility for certain corrective actions described in 40 C.F.R. 

§ 146.84 of the Rule. The GS Rule releases owners and operators from financial 

responsibility requirements at the conclusion of the post-injection site care 

period once the Director has determined that the injected fluid no longer poses 

a threat of endangerment to USDWs. 

Spectra supports EPA’s approach to releasing owners and operators from any 

further financial responsibility requirement at the conclusion of the postinjection site care period and upon a determination by the Director that the 

CO2 plume poses no further risk to USDWs. Establishing firm and discrete 

limits for post-injection obligations on behalf of owners and operators is 

essential to the viability of commercial-scale CCS. Open-ended requirements 

that could continue indefinitely, even after a showing that the CO2 plume has 

stabilized, would impose an unreasonable burden and likely inhibit project 

development. 

Spectra also proposes that owners and operators be released from any monitoring 

or verification requirements at the conclusion of the post-injection site-care 

period and upon a showing that the CO2 plume has stabilized. This approach 

would have the effect of dovetailing the responsibilities of owners and 

operators in the post-injection site care period with the transfer of long-term 

liability to the State. As discussed more fully below, Spectra believes that 

the eventual transfer of long-term liability to the State should encompass all 

potential liability - both anticipated site care responsibilities, such as 

monitoring and verification requirements, as well as any unanticipated 

migration of the CO2 plume and potential endangerment of USDWs. 

15 Modeling results indicate that a CO2 plume will stabilize within 10 to 100 

years after the cessation of injection. See Computational Modeling of 

Underground Injection of Carbon Dioxide for Determine of Are-of-Review and 

Potential Risk to Underground Sources of Drinking Water, U.S. EPA (2008). 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most

cases or arbitrary. EPA proposed a default timeframe of 50 years based on a review of research

studies, industry reports, and existing environmental programs. This analysis was included in an

EPA background document available in the federal docket, "Computational Modeling of

Underground Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk

to Underground Sources of Drinking Water." EPA assessed various default timeframes based on

additional review of research studies and evaluation of public comments. While numerous

commenters suggested that EPA shorten the monitoring timeframe, none of the commenters

provided sufficient data to warrant a change in the proposed timeframe. While the 10- or 30-year

timeframe suggested by some of these commenters may be within the timeframe suggested in some

studies, EPA believes that the potential risks of endangering USDWs will likely not decline within

these timeframes and available data, including data submitted by commenters, do not support a

different default timeframe. However, EPA recognizes that alternative timeframes may be

appropriate under limited, specific circumstances, which is why EPA is providing the Director

discretion to approve an alternative post-injection site care timeframe as long as the owner or

operator can meet the requirements provided at §146.93(c). 
The GS rule offers owners or operators flexibility regarding the duration of the PISC timeframe by:

(1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the PISC

period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the

Director discretion to allow a Class VI well owner or operator to demonstrate, based on substantial

data during the permitting process, that an alternative PISC timeframe may be appropriate if it

ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA agrees that owners or operators should not be subject to additional monitoring or financial

responsibility requirements following site closure. The final rule releases owners or operators from

these requirements once closure has occurred.

Commenter Name: Jeff Moseley Letter ID: 0155

Commenter Organization: Greater Houston Partnership (GHP) Comment ID: 21260

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: 7. Revise the standard for determining site closure. Criteria should be 

performance based and a function of site-specific geologic and other risk 

criteria, rather than being dependent on a 50-year-period or any other fixed 

period of time; and, 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the final GS regulation offers owners or operators

flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to

shorten or lengthen the PISC timeframe during the PISC period based on site-specific data, pursuant

to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well

owner or operator to demonstrate, based on substantial data during the permitting process, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care is necessary in most cases. A 50 year post-injection site care timeframe

represents a reasonable and protective monitoring period for most GS projects based on a review of

research studies, industry reports, and existing environmental programs, and evaluation of public

comments.
Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22634

Comment: It is Appropriate to Utilize both a Fixed Time Frame and Performance Standard 

for Establishing the Period of Post Closure Monitoring 

Given humanity’s knowledge about GS deployed at the scale of millions of tons 

per year for decades at a given injection field is quite slim, the USEPA’s 

proposal of a fixed time frame in conjunction with a performance standard 

appears to be an appropriate balance between discharging its responsibilities to 

protect human health and the environment and not placing overly burdensome, 

unneeded requirements on prospective GS owner / operators (pp 43519-43520). The 

50 year time frame will allow owners / operators to budget for post site closure 

within the bounds of what is currently known. The performance standard is an 

assurance to the public that a site will not be released until it has reached a 

certain point of stability. Given where humanity is with GS, the USEPA should 

be commended for crafting this compromise and should retain this language in 

subsequent versions of this draft Class VI rule. 

Response: EPA acknowledges the commenter’s support and has implemented a combination fixed

timeframe and performance standard approach for post-injection site care monitoring for Class VI

wells in the final GS rule. The PISC requirements in the final GS rule, as specified in §146.93(b),

incorporate a combination of a fixed timeframe and a performance standard approach. EPA believes

that a default PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this

timeframe, combined with a site-specific Director’s discretion to create an alternative PISC time

frame, ensures that USDWs are protected. The GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the PISC period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, based on substantial data during the permitting process, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23763

Comment: Concern #8: The owner or operator shall continue to conduct monitoring as 

specified in the Director- approved post-injection site care and site closure 

plan for at least 50 years following the cessation of injection. At the 

Director's discretion, the monitoring will continue until the geologic 

sequestration project no longer poses an endangerment to USDWs. (Ref: page 

43519, Sec. 8. Post-Injection Site Care Timeframe) 
The time required for post-injection site management should not be arbitrarily 

set at 50 years. Criteria for defining the time for post-injection management 

should be performance based and site specific. The choice of 50 years is 

arbitrary and does not take into account the data and knowledge and modeling 

verification obtained over a preceding operating and injection period of years 

and likely decades. The maximum post-injection monitoring period should be 

defined on reasonable but quantitative, performance-based metrics - for example, 

that the validated model predicts that 95% of the plume is or will be trapped 

and that a sensitivity analysis predicts a comfortable margin of safety to 

minimize approach to any USDWs, thus preventing potential endangerment. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the final GS regulation offers owners or operators flexibility regarding the duration of the

PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe

during the PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, based on

substantial data during the permitting process, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care is necessary in most cases. A 50 year post-injection site care timeframe

represents a reasonable and protective monitoring period for most GS sites based on a review of

research studies, industry reports, and existing environmental programs, and evaluation of public

comments.

EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most cases or

arbitrary. EPA proposed a default post-injection site care timeframe of 50 years based on a review of

research studies, industry reports, and existing environmental programs. This analysis was included

in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances,

which is why EPA is providing the Director discretion to approve an alternative post-injection site

care timeframe as long as the owner or operator can meet the requirements provided at §146.93(c). 
Commenter Name: Sandi Tabor Letter ID: 0162

Commenter Organization: Lignite Energy Council (LEC) Comment ID: 21304

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: 5. Combination of Fixed Timeframe and Performance Standard -EPA is seeking 

comments on the imposition of a 50-year post-injection site care (PISC) standard 

as a default timeframe with state UIC directors having discretion to adjust the 

default time period. We urge EPA to remove all reference to default PISC periods 

and instead require directors to base post-injection site care on site and 

project specific characteristics. By so doing the goal of supporting the 

commercialization of CCS technology is better served. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the final GS regulation offers owners or operators flexibility regarding the duration of the

PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe

during the PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, based on

substantial data during the permitting process, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care is necessary in most cases. A 50 year post-injection site care timeframe

represents a reasonable and protective monitoring period for most GS projects based on a review of

research studies, industry reports, and existing environmental programs, and evaluation of public

comments. 

Commenter Name: Michael Mudd Letter ID: 0167

Commenter Organization: FutureGen Alliance (FGIA) Comment ID: 22463

Comment: Post-Injection Monitoring Period p. 43540-43541 

The owner or operator shall continue to conduct monitoring as specified in the 

Director-approved post-injection site care and site closure plan for at least 50 

years following the cessation of injection.If the owner or operator can 

demonstrate to the satisfaction of the Director before 50 years, based on 

monitoring and other site-specific data, that the geologic sequestration project 

no longer poses an endangerment to USDWs. 

Comment: The basis for the 50 year minimum period is not clear. The minimum 

period should be tied to both risk and project specific information. Although 

there is the possibility that post-injection monitoring period can be reduced 

given sufficient data, this approach adds significant uncertainty to both the 

project schedule and cost. It appears unlike that an owner or operator will be 
able to know with certainty during the planning stage for GS what the postinjection monitoring period will be. The end result is for owners and operators 

to assume the entire 50 year period, which will have an adverse effect on the 

cost, schedule and feasibility of the project. A time period of 10 years seems 

more reasonable, but would need to be confirmed by risk and project specific 

information. 

Response: EPA clarifies that it proposed a default post-injection site care timeframe of 50 years

based on a review of research studies, industry reports, and existing environmental programs. This

analysis was included in an EPA-prepared background document that is available in the federal

docket, titled "Computational Modeling of Underground Injection of Carbon Dioxide for

Determination of Area-of-Review and Potential Risk to Underground Sources of Drinking Water."

EPA assessed various default timeframes based on additional review of research studies and

evaluation of public comments. 

While numerous commenters suggested that EPA shorten the monitoring timeframe, none of the

commenters provided sufficient data or other evidence to warrant a change in the proposed

timeframe. While the 10- or 30-year timeframe suggested by some of these commenters may be

within the timeframe suggested in some studies, EPA believes that the potential risks of endangering

USDWs will likely not decline within these timeframes and available data, including data submitted

by commenters, do not support a different default timeframe. However, EPA recognizes that

alternative timeframes may be appropriate under limited, specific circumstances, which is why EPA

is providing the Director discretion to approve an alternative post-injection site care timeframe as

long as the owner or operator can meet the requirements provided at §146.93(c). 

The GS rule offers owners or operators flexibility regarding the duration of the PISC timeframe by:

(1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the PISC

period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the

Director discretion to allow a Class VI well owner or operator to demonstrate, based on substantial

data during the permitting process, that an alternative PISC timeframe may be appropriate if it

ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes that a 50 year post-injection site care timeframe represents a reasonable and protective

monitoring period and available data, including data submitted by commenters, do not support a

different default timeframe. Furthermore, EPA believes that a 50-year default post-injection site care

timeframe, as required at §146.93(b)(1), is not overly burdensome, does not exaggerate the risks

associated with GS, is consistent with other environmental programs, and sufficiently protects

USDWs from endangerment. 

Commenter Name: Michael J. Miller Letter ID: 0168

Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22510

Comment: Preamble, page 43519-43520: "EPA requests comment on the proposed use of a 

tentative 50-year fixed timeframe that could be modified at the Director’s 

discretion based on monitoring and modeling data." 
EPRI COMMENT #17: EPA’s 50-year fixed timeframe described in the preamble 

appears to be based on professional judgment interpreting a limited number of 

citations and/or modeling scenarios. We question the need for defining a fixed 

timeframe of any length because it runs counter to the EPA’s implied intent to 

close sites based on the owner/operator’s ability to meet specific performance 

criteria defined in §146.93(b). (See EPRI comment #2, #13, and #18 regarding 

these criteria (i.e., front tracking and stability)). 

Response: EPA disagrees with this comment. In determining the post-injection site care-timeframe

for the proposed regulation, EPA reviewed industry reports, existing environmental programs, and

initial GS research studies. EPA provided a synthesis of pertinent results from GS modeling studies

in the preamble to the proposed regulation. Further explanation of this analysis was included in an

EPA-prepared background document that is available in the federal docket, titled "Computational

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and

Potential Risk to Underground Sources of Drinking Water." Based on review of these studies,

modeling results indicate that the CO2 plume stabilization may occur on the timeframe of 10-100

years after the cessation of injection. EPA believes that a 50-year default post-injection site care

timeframe is a reasonable midpoint for most GS projects and available data, including data submitted

by commenters, do not support a different default timeframe, and has retained this in the final

regulation. 

EPA agrees that some owners or operators will be able to demonstrate, in less than 50 years, that the

pressure front and plume no longer pose a risk of endangerment to USDWs. However, based on

studies, EPA believes that the 50 year default time frame is warranted in most cases based on

additional review of research studies and reports and evaluation of public comments. EPA believes

that the best way to address all possibilities, while ensuring USDW protection from endangerment, is

to set a 50 year default post-injection site care timeframe, with flexibility to: (1) allow the Director

discretion to shorten or lengthen the PISC timeframe during the PISC period based on site-specific

data, pursuant to requirements at §146.93(b); or (2) afford the Director discretion to allow a Class VI

well owner or operator to demonstrate, based on substantial data during the permitting process, that

an alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs

pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23368

Comment: Well Plugging and Post-Injection Site Care -- Pg. 41 

APPA believes that the Proposal’s suggested fifty-year default fixed timeframe 

for the post-injection site care period is arbitrary and will serve to discourage 

Owners or Operators of CO2 GS sites from seeking to develop innovative ways to 
safely close wells in a shorter time period. While there is no single time period 

that can apply across the board, APPA suggests that 10 years or until the plume 

is determined to be stable is sufficient. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is arbitrary. EPA

proposed a default post-injection site care timeframe of 50 years based on a review of research

studies, industry reports, and existing environmental programs. This analysis was included in an

EPA-prepared background document that is available in the federal docket, titled "Computational

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and

Potential Risk to Underground Sources of Drinking Water." EPA assessed various default

timeframes based on additional review of research studies and evaluation of public comments. While

numerous commenters suggested that EPA shorten the monitoring timeframe, none of the

commenters provided sufficient data or other evidence to warrant a change in the proposed

timeframe. While the 10- or 30-year timeframe suggested by some of these commenters may be

within the timeframe suggested in some studies, EPA believes that the potential risks of endangering

USDWs will likely not decline within these timeframes and available data, including data submitted

by commenters, do not support a different default timeframe. 

However, EPA recognizes that alternative timeframes may be appropriate under limited, specific

circumstances. For this reason, the Class VI rule offers owners or operators flexibility regarding the

duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the

PISC timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a 50 year post-injection site care timeframe represents a reasonable and protective

monitoring period and available data, including data submitted by commenters, do not support a

different default timeframe. Furthermore, EPA believes that a 50-year default post-injection site care

timeframe, as required at §146.93(b)(1), is not overly burdensome, does not exaggerate the risks

associated with GS, is consistent with other environmental programs, and sufficiently protects

USDWs from endangerment.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

Commenter Name: Theresa Pugh Letter ID: 0169

Commenter Organization: American Public Power Association Comment ID: 23420

Comment: Well Plugging and Post-Injection Site Care 

APPA acknowledges that for some potential power plant owner/operators that the 

Proposal’s suggested fifty-year default fixed timeframe for the post-injection 

site care period is arbitrary and will serve to discourage Owners or Operators 

of CO2 GS sites from seeking to develop innovative ways to safely close wells in 

a shorter time period. Id. at 43519. EPA acknowledges in the Preamble to the 

Proposal that it is likely "that the actual time for CO2 plume 

stabilization...will be very site specific, being influenced by geologic factors 

such as formation permeability, geochemistry, and the degree of capillary 

trapping." Id. (emphasis added). EPA then goes on to note that the studies used 
for their preliminary analysis suggest that the length of time required before 

plume stabilization ranges from ten to one hundred years after cessation of 

injection - quite a significant range. Id, emphasis added. In the same 

discussion, EPA reviews a range of suggested time periods, acknowledging that 

even a ten-year timeframe is suggested by some studies. 

APPA understands that a ten-year site closure period may be insufficient in some 

cases; there is no single time period that would apply to every CO2 GS site 

across the board. Because of the greatly varied geologic characteristics, APPA 

believes a post closure period of 10 years or until the plume is determined to 

be stable. Stability is to be defined by the state Director that he/she does not 

believe that it can harm USDWs. Given the concerns by the water utilities, APPA 

defers to AWWA for their expertise in this matter. 

Response: As noted above, EPA disagrees that a post-injection site care timeframe of 50 years is

arbitrary. In determining the post-injection site care-timeframe for the proposed regulation, EPA

reviewed industry reports, existing environmental programs, and initial GS research studies. EPA

provided a synthesis of pertinent results from GS modeling studies in the preamble to the proposed

regulation. Further explanation of this analysis was included in an EPA-prepared background

document that is available in the federal docket, titled "Computational Modeling of Underground

Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk to

Underground Sources of Drinking Water." Based on review of these studies, modeling results

indicate that the CO2 plume stabilization may occur on the timeframe of 10-100 years after the

cessation of injection. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. 

However, EPA recognizes that alternative timeframes may be appropriate under limited, specific

circumstances. For this reason, the Class VI rule offers owners or operators flexibility regarding the

duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the

PISC timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a 50 year post-injection site care timeframe represents a reasonable and protective

monitoring period and available data, including data submitted by commenters, do not support a

different default timeframe. Furthermore, EPA believes that a 50-year default post-injection site care

timeframe, as required at §146.93(b)(1), is not overly burdensome, does not exaggerate the risks

associated with GS, is consistent with other environmental programs, and sufficiently protects

USDWs from endangerment.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24122

Comment: 50-year Default Post-Injection Site Care 

EPA should also reconsider its proposed 50-year default period for 

post-injection site care. EPA offers no rationale for this arbitrarily-selected 

period of 50 years. Establishing a fixed and unusually long time period, even 
with the Director discretion provided, may create a significant barrier for 

operators considering entry into CCS operations. Criteria for determining the 

period for post-injection site care should be performance-based and a function 

of the site specific characteristics of a project such as project size, geologic 

factors, and relative risk of the project. Clear guidelines also need to be 

established regarding when operators have met the performance standards that 

determine site closure. Specifically, the standard that the project no longer 

poses an endangerment to USDWs needs to be defined using reasonable risk-based 

criteria. 

A related concern is that EPA is proposing imposition of financial assurance 

requirements for activities that may occur more than 50 years in the future, 

with requirements to be satisfied at the time of permitting. EPA should 

carefully examine whether at this time, or at the time of permitting, the cost 

of such activities can be accurately estimated and assumed to be relatively 

accurate going forward. If not, financial assurance is no better than a guess, 

and serves only to introduce significant uncertainties into project economics 

and project finance. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is arbitrary. EPA

proposed a default post-injection site care timeframe of 50 years based on a review of research

studies, industry reports, and existing environmental programs. This analysis was included in an

EPA-prepared background document that is available in the federal docket, titled "Computational

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and

Potential Risk to Underground Sources of Drinking Water." EPA assessed various default

timeframes based on additional review of research studies and evaluation of public comments. While

numerous commenters suggested that EPA shorten the monitoring timeframe, none of the

commenters provided sufficient data or other evidence to warrant a change in the proposed

timeframe. While the 10- or 30-year timeframe suggested by some of these commenters may be

within the timeframe suggested in some studies, EPA believes that the potential risks of endangering

USDWs will likely not decline within these timeframes and available data, including data submitted

by commenters, do not support a different default timeframe. 

However, EPA recognizes that alternative timeframes may be appropriate under limited, specific

circumstances. For this reason, the Class VI rule offers owners or operators flexibility regarding the

duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the

PISC timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a 50 year post-injection site care timeframe represents a reasonable and protective

monitoring period and available data, including data submitted by commenters, do not support a

different default timeframe. Furthermore, EPA believes that a 50-year default post-injection site care

timeframe, as required at §146.93(b)(1), is not overly burdensome, does not exaggerate the risks

associated with GS, is consistent with other environmental programs, and sufficiently protects

USDWs from endangerment.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 
EPA recognizes that there are challenges associated with assuring funding for activities that will

occur far in the future. However, the Agency believes that in order to protect USDWs from

endangerment under the SDWA, operators must demonstrate under §146.85 that financial resources

are available to plug the injection well and provide post-injection site care at the point in time that

the first CO2 is injected.

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24206

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

language 

Comment: Rule Provision: 146.93(b) 

API Comments: (b) The owner or operator shall monitor the site following the 

cessation of injection to show the position of the carbon dioxide plume and 

pressure front and demonstrate that USDWs are not being endangered.

(1) The owner or operator shall continue to conduct monitoring as specified in 

the Director-approved post-injection site care and site closure plan, for at 

least 50 years following the cessation of injection. At the Director‘s 

discretion, the monitoring will continue until the geologic sequestration 

project no longer poses an endangerment to USDWs. UNTIL CLOSURE IS AUTHORIZED 

PURSUANT TO §146.93(B)(3). 

(2) If The owner or operator can request and demonstrate to the satisfaction 

of the Director before 50 years, based on monitoring and other site-specific 

data, that the geologic sequestration project no longer poses an endangerment to 

USDWs, the Director may approve an amendment to THAT the post-injection site 

care and site closure plan SHOULD BE REVISED to reduce the frequency of 

monitoring or may authorize site closure before the end of the 50-year 

period.

Rationale: API, along with the MSDG, believes there are three problems with the 

closure standard in proposed section 146.93(b). First, the presumption that 

monitoring should continue for 50 years is unnecessary and counterproductive. A 

straight performance standard is preferable to this or any other fixed time 

period because it provides a clearer standard and an incentive to maximize the 

understanding of site and project performance and as such is more protective of 

USDWs. Second, the proposal requires a showing that the CO2 plume has 

"stabilized", which is undefined. Cessation of plume movement is not necessarily 

essential to show that a project poses no threat of endangerment to USDWs-plumes 

that are still moving may, nonetheless, remain contained. Instead, it is more 

protective to show that the plume is not expected to encounter a leakage 

pathway. Third, the required showing that "no additional monitoring is needed" 

does not provide guidance regarding how an operator is to show that no 

additional monitoring is needed. The proposal below provides specific guidance 

on what the operator must show. 

API, in concert with the MSDG, recommends the standard in the proposed 

alternative language for section 146.93(b) below because it sets forth detailed 

criteria, all of which must be satisfied, to demonstrate that the site does not 
pose an endangerment to USDWs. The specific criteria listed in our proposal will 

serve to provide the Director with the requisite information to make the 

appropriate determination. The advantage of this approach is that it establishes 

clear criteria that an operator must demonstrate before obtaining site closure 

based upon particular site characteristics and is, therefore, reasonably 

applicable to any storage site as opposed to a standard based upon a 

fixedduration. Furthermore, it is more stringent than a purely discretionary 

approach because it establishes specific criteria that must be shown before site 

closure may be granted. We believe this language, which is an extension of work 

done by the World Resources Institute and the Ground Water Protection Council, 

avoids the noted shortcomings and provides stronger protection for USDWs. 

Response: EPA disagrees with the suggested changes. As noted above, EPA disagrees that a postinjection site care timeframe of 50 years is excessive for most Class VI wells. EPA believes that a

50-year default post-injection site care timeframe, as required at §146.93(b)(1), is not overly

burdensome, does not exaggerate the risks associated with GS, is consistent with other

environmental programs, and sufficiently protects USDWs from endangerment.

EPA acknowledges the concerns of some commenters that there will be circumstances where it can

be demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the Class VI rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the PISC period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, based on substantial data during the permitting process, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a 50 year post-injection site care timeframe represents a reasonable and protective

monitoring period and available data, including data submitted by commenters, do not support a

different default timeframe. Furthermore, EPA believes that a 50-year default post-injection site care

timeframe, as required at §146.93(b)(1), is not overly burdensome, does not exaggerate the risks

associated with GS, is consistent with other environmental programs, and sufficiently protects

USDWs from endangerment. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist

Directors in evaluating proposed well plugging plans and post-injection site care and site closure

plans required under 146.92 and 146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells, perform post-injection monitoring,

demonstrate the appropriateness of an alternative post-injection site care time frame, demonstrate

non-endangerment, and perform site closure activities. This guidance will be available at

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

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24209

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

language; 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(4) 
API Comments: (4) If such a demonstration cannot be made (i.e., if the carbon 

dioxide plume and pressure front have not stabilized) after the 50-year period, 

the owner or operator must submit to the Director a plan to continue postinjection site care.

Rationale: No longer necessary given changes above. 

Response: As described above, EPA believes that to ensure USDW protection from endangerment, a

default timeframe for post-injection site care is necessary in most cases. A 50-year post-injection site

care timeframe represents a reasonable and protective monitoring period for most GS projects based

on a review of research studies, industry reports, and existing environmental programs, and

evaluation of public comments. However, EPA recognizes that alternative timeframes may be

appropriate under limited, specific circumstances. For this reason, the Class VI rule offers owners or

operators flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director

discretion to shorten or lengthen the PISC timeframe during the PISC period based on site-specific

data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class

VI well owner or operator to demonstrate, based on substantial data during the permitting process,

that an alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs

pursuant to requirements at §146.93(c).

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24255

Comment: Rule Provisions: 73 FR 43519-20, 146.93(b) 

EPA Preamble Question: 38. EPA is proposing using a combination of fixed 

timeframe and a performance standard as described above. EPA is tentatively 

proposing a post-injection site care (monitoring) period of 50 years with 

Director’s discretion to change that period to lengthen or shorten the 50 year 

period if appropriate. EPA requests comment on the proposed use of a tentative 

50 year fixed timeframe that could be modified at the Director’s discretion 

based on monitoring and modeling data. EPA Notice 43519. 

API Response: API strongly objects to the use of a 50-year default monitoring 

period. EPA offers no rationale for this arbitrarily-selected period of 50 

years. Establishing a fixed and unusually long time period may create a 

significant barrier for operators considering entry into CCS operations. 

Criteria for determining the period for post-injection site care should be 

Performance-based and a function of the site specific characteristics of a 

project such as project size, geologic factors, and relative risk of the 

project. (API offers such criteria in our edits to §146.93(b)(3).) 

Clear guidelines also need to be established regarding when operators have met 

the performance standards that determine site closure. Specifically, the 

standard that the project no longer poses an endangerment to USDWs needs to be 

defined using reasonable risk-based criteria. 

Response: EPA disagrees that the post-injection monitoring period is arbitrary. In determining the

post-injection site care-timeframe for the proposed regulation, EPA reviewed industry reports,

existing environmental programs, and initial GS research studies. EPA provided a synthesis of

pertinent results from GS modeling studies in the preamble to the proposed regulation. Further
explanation of this analysis was included in an EPA-prepared background document that is available

in the federal docket, titled "Computational Modeling of Underground Injection of Carbon Dioxide

for Determination of Area-of-Review and Potential Risk to Underground Sources of Drinking

Water." Based on review of these studies, modeling results indicate that the CO2 plume stabilization

may occur on the timeframe of 10-100 years after the cessation of injection. EPA believes that a 50-

year default post-injection site care timeframe is a reasonable midpoint for most GS projects and

available data, including data submitted by commenters, do not support a different default timeframe,

and has retained this in the final regulation. 

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist

Directors in evaluating proposed well plugging plans and post-injection site care and site closure

plans required under 146.92 and 146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells, perform post-injection monitoring,

demonstrate the appropriateness of an alternative post-injection site care time frame, demonstrate

non-endangerment, and perform site closure activities. This guidance will be available at

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

Commenter Name: James Rower Letter ID: 0173

Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23504

Comment: 12. Well Plugging and Post-Injection Site Care 

USWAG believes that the Proposal's suggested fifty-year default fixed timeframe 

for the post-injection site care period is arbitrary and will serve to 

discourage Owners or Operators of CO2 GS sites from seeking to develop 

innovative ways to safely close wells in a shorter time period. Id. at 43519. 

EPA acknowledges that it is likely "that the actual time for CO2 plume 

stabilization ... will be very site specific, being influenced by geologic 

factors such as formation permeability, geochemistry, and the degree of 

capillary trapping." Id. (emphasis added). In fact, EPA observes that the 

studies used for their preliminary analysis suggest that the length of time 

required before plume stabilization ranges from ten to one hundred years after 
cessation of injection - quite a significant range. Id. 

While a ten-year site closure period may be insufficient in some cases, it is 

clear that there is no single time period that would apply to every CO2 GS site 

across the board. Because of the greatly varied characteristics and needs of 

different CO2 GS projects, application of a performance-based standard which is 

highly site-specific, rather than any default time period, is the most 

appropriate approach to the postinjection site care requirements. While the 

Proposal would give the Director discretion to decrease or increase the postinjection site care and closure period, the inclusion of a fifty-year default 

timeframe is likely to discourage Owners or Operators from working to develop 

technology that would facilitate safe and quick site closure; the fifty-year 

default may even have a chilling effect on the Program as a whole, discouraging 

would-be Owners or Operators from undertaking a CO2 GS project that could impose 

requirements decades into the future even when unnecessary. In contrast, by 

tailoring requirements to a given site, a performance-based standard would 

encourage the development of methods and technology that would achieve long-term 

protection of USDWs with well closure after a shorter period of time. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the final GS regulation offers owners or operators

flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to

shorten or lengthen the PISC timeframe during the post-injection period based on site-specific data,

pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI

well owner or operator to demonstrate, during the permitting process based on substantial data, that

an alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs

pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment.

Commenter Name: Pamela Faggert Letter ID: 0175

Commenter Organization: Dominion Comment ID: 23525

Comment: 4. Post-injection Site Care 

The proposed rule's post injection site care (PISC) period of 50 years, subject 
to Director discretion, is arbitrary and unnecessary. The PISC should be set 

based on a site-specific performance-based approach. 

The PISC period should be based not on an arbitrary default but on a 

site specific performance-based approach. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is arbitrary. In

determining the post-injection site care-timeframe for the proposed regulation, EPA reviewed

industry reports, existing environmental programs, and initial GS research studies. EPA provided a

synthesis of pertinent results from GS modeling studies in the preamble to the proposed regulation.

Further explanation of this analysis was included in an EPA-prepared background document that is

available in the federal docket, titled "Computational Modeling of Underground Injection of Carbon

Dioxide for Determination of Area-of-Review and Potential Risk to Underground Sources of

Drinking Water." Based on review of these studies, modeling results indicate that the CO2 plume

stabilization may occur on the timeframe of 10-100 years after the cessation of injection. EPA

believes that a 50-year default post-injection site care timeframe is a reasonable midpoint for most

GS projects and available data, including data submitted by commenters, do not support a different

default timeframe, and has retained this in the final regulation.

To address concerns that, in some situations, it can be demonstrated in less than 50 years that the

plume and pressure front no longer pose a risk of endangerment to USDWs, the GS regulation offers

owners or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing the

Director discretion to shorten or lengthen the PISC timeframe during the post-injection period based

on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion

to allow a Class VI well owner or operator to demonstrate, during the permitting process based on

substantial data, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Kenneth Nemeth Letter ID: 0176

Commenter Organization: Southern States Energy Board Comment ID: 23545

Comment: casing should not be required. No specific timeframe for post closure care 

should be specified, and it should be based on performance standards 

demonstrated by the owner/operator. Corrosion monitoring is unnecessary, as it 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the final GS regulation offers owners or operators

flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to
shorten or lengthen the PISC timeframe during the post-injection period based on site-specific data,

pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI

well owner or operator to demonstrate, during the permitting process based on substantial data, that

an alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs

pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23554

Comment: Another general area of concern discussed in our comments involves the proposed 

rule‘s provisions for closure and post-injection site care (PISC). In 

particular, EEI is concerned with the proposed imposition of a PISC period 

spanning, as a matter of default, 50 years after cessation of injection. 

Establishing a default time period for PISC, in particular one as lengthy as 50 

years, is unnecessary and undesirable. The dual goals of protecting USDW and 

supporting the commercialization of CCS technology are far better served through 

a site-specific, performance-based approach. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the final GS regulation offers owners or operators

flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to

shorten or lengthen the PISC timeframe during the post-injection period based on site-specific data,

pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI

well owner or operator to demonstrate, during the permitting process based on substantial data, that

an alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs

pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize
site-specific data, and be based on pressure monitoring and USDW impacts.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23566

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial

responsibility requirements (40 CFR 146.85) 

Comment: iii. Appropriate risk management approaches. The Agency should avoid 

development of risk management approaches that discourage CCS deployment or 

create additional uncertainty, and should seek where possible to bring greater 

certainty to the long-term obligations and risks associated with a GS project. 

For example, requiring financial assurance for potential liabilities more than 

50 years in the future may deter and even prevent investment in CCS projects. 

Post-injection monitoring and financial assurance requirements are both 

important, but should not undermine the goals of the regulations, particularly 

when potential risks decrease substantially after injection is complete. 

Response: EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the

purpose of the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that

protects USDWs from endangerment. 

EPA disagrees that the requirements for financial responsibility are overly stringent. The goal of

financial responsibility is to ensure that financial resources are available to prevent the endangerment

of USDWs from improper plugging, remediation, and management of wells in the event that the

owner or operator experiences financial difficulties throughout the life of the project. 

EPA believes that minimum financial responsibility requirements are necessary to hold well owners

or operators accountable for the safe operation and closure of the well to avoid endangerment of

USDWs while avoiding expense and risk to the public. 

Regarding the need for financial assurance for a 50-year post-injection period, EPA believes that to

ensure USDW protection from endangerment, a default timeframe for post-injection site care is

necessary. A 50 year post-injection site care timeframe represents a reasonable and protective

monitoring period based on a review of research studies, industry reports, and existing

environmental programs, and evaluation of public comments.

EPA agrees with commenters that there will be circumstances where it can be demonstrated in less

than 50 years that the plume and pressure front no longer pose a risk of endangerment to USDWs.

For this reason, the final GS regulation offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust
the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts. 

Commenter Name: Quinlan J. Shea Letter ID: 0177

Commenter Organization: Edison Electric Institute Comment ID: 23592

Comment: E. Closure and Post-Injection Site Care 

The fourth general area of concern discussed in these comments involves the 

proposed rules‘ provisions for closure and post-injection site care (PISC). In 

particular, EEI is concerned with the proposed imposition of a PISC period 

spanning, as a matter of default, 50 years after cessation of injection. The 

proposed rules would vest discretion in the UIC program director to adjust the 

50-year default time period upward or downward, with monitoring to continue 

"until the geologic sequestration project no longer poses an endangerment to 

USDWs." 

Establishing a default time period for PISC, in particular a default time period 

as lengthy as 50 years, is unnecessary and undesirable, and the dual goals of 

protecting USDW and supporting the commercialization of CCS technology are far 

better served through a site-specific, performance-based approach. To EEI 

offers the following supporting points: 

- A default time period is unnecessary: As noted above, the proposed rules 

would, in conjunction with establishing the 50-year default period for postinjection activities, vest discretion in the UIC program director to shorten or 

lengthen the PISC period based on the characteristics of a particular project. 

As discussed further below, a PISC period based on site- and project-specific 

characteristics ably serves to meet the dual goals of EPA‘s rulemaking effort; 

given the proposed performance-based, discretionary aspect of the PISC-period 

determination, a default overlay period is unnecessary. Further, from the 

perspective of offering protection to USDW, such a default period offers no 

additional protection above and beyond what a performance-based standard will 

offer. 

- A default time period is unduly burdensome for operators: Establishing a 

default time period also risks placing unnecessary regulatory burdens on owners 

and operators who can clearly establish from the outset that no threat to USDW 

will be posed within a shorter time frame than whatever default may be 

established. 

- A 50-year default time period is unprecedented under the UIC program and 

unwarranted for CO2: Even assuming that imposition of a default period were 

appropriate, the unique characteristics of CO2 do not justify imposition of such 

a lengthy default PISC period for GS projects. EEI and its members believe that 

appropriately sited projects could demonstrate the absence of endangerment to 
USDW in substantially less than 50 years; indeed, data suggest the risk profile 

of injected CO2 drops rapidly just 10 years after cessation.[FN7] Further, 

imposing requirements on CO2 storage projects that are far beyond those 

currently in place even for injection of hazardous wastes is unnecessary and 

will only engender public misperceptions regarding the safety of such projects. 

- A default time period may not appropriately incentivize proper site 

characterization: Proper siting is the key to ensuring safety and effectiveness 

of storage projects, and the rules should work to incentivize, rather than 

discourage, the utmost due diligence in the siting process. While EPA‘s 

proposal would provide for the exercise of discretion to lengthen or shorten the 

PISC period, placing the burden of proof on permittees that a departure from the 

default is justified fails to recognize the enormous efforts associated with 

proper site characterization. 

- A 50-year default period may introduce unnecessary financial uncertainty: As 

currently proposed, the rules would require operators to obtain, as a baseline 

and at the time of permitting, financial assurance running through the default 

50-year PISC period. Thus, operators would be likely required to assure 

activities that would not occur for more than 50 years, with discretion vested 

n the UIC program director to extend that time period--and thus the required 

period for demonstrating financial assurance. The end result could be an 

obligation to provide financial assurance for activities running through at 

least 70 years in the future (according to EPA‘s assumption of a 20-year 

injection period), or more. Further, in actuality, the PISC period could prove 

to be considerably shorter, rendering the initial burden placed upon the 

operator unnecessary. EEI urges the Agency to consider carefully, in connection 

with each proposed requirement that is tied to a financial assurance 

requirement, the ability for operators to quantify the activities being assured 

at the time of permitting--the basis of any financial assurance mechanism--as 

well as the potential burden and expense associated with the proposal. Given 

the ongoing credit crisis, an unjustifiably lengthy PISC period may make 

obtaining the necessary financial assurance impossible, stunting or stopping 

commercial development of CCS. 

Instead of a default time period--particularly one as lengthy as 50 years--EEI 

urges EPA to implement a performance-based approach that considers the 

circumstances of a particular project, bounded by appropriate parameters for its 

application. As discussed throughout these comments, EEI also encourages the 

Agency to establish clear parameters for such a performance-based approach--and 

in particular a clear set of guidelines for demonstrating that the injectate has 

"stabilized" and for meeting the non-endangerment standard. 

[FN7] S. Benson, Carbon Dioxide Capture and Storage: Research Pathways, 

Progress and Potential, GCEP Annual Symposium, October 2007: 

http://pangea.stanford.edu/research/bensonlab/presentations/index.html. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the final GS regulation offers owners or operators flexibility regarding the duration of the
PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe

during the post-injection period based on site-specific data, pursuant to requirements at §146.93(b);

or (2) affording the Director discretion to allow a Class VI well owner or operator to demonstrate,

during the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

EPA does not believe that performing the demonstration before 50 years places an additional burden

on these owners or operators. EPA clarifies that all operators will need to make this demonstration

prior to the Director authorizing site closure; the difference is that some operators will be performing

the demonstration earlier than others. As indicated by the commenters, ideally this demonstration

will be part of an ongoing communication between the owner or operator and the UIC Director. If an

owner or operator believes that an earlier demonstration will be burdensome, they are not required to

make the demonstration. 

EPA recognizes that there are challenges associated with assuring funding for activities that will

occur far in the future. However, the Agency believes that in order to protect USDWs from

endangerment under the SDWA operators must demonstrate under §146.85 that financial resources

are available to plug the injection well and provide post-injection site care at the point in time that

the first CO2 is injected.

EPA also recognizes the concerns associated with assuring financial responsibility for the long time

frames over which post-injection site care will be conducted. EPA is developing guidance on

financial responsibility to assist owners or operators in evaluating the requirements of §146.85 and to

assist Directors in evaluating financial responsibility demonstrations. The guidance describes the

types of financial mechanisms that operators may choose to use when evaluating the financial

responsibility requirements for GS wells and it will also include a section on how to estimate costs to

support accurate financial responsibility demonstrations. The guidance will be available at

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

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23814

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

Long-Term Care Requirements 

Comment: A. FIFTY YEAR TIME FRAME FOR POST-CLOSURE SITE CARE
RESPONSIBILITY 

The Proposed Rule states that the timeframe over which CO2 will be trapped 

depends on the properties of the receiving formation and the injected CO2 

stream. Currently available information does not provide a complete 

understanding of the time required to stabilize geologically sequestered CO2 

under various conditions: however, some experience does exist and has led some 

to develop extrapolative estimates for related geologies. Some believe that in a 

significant number of cases, a 10 to 30 year timeframe will be sufficient to 

determine that the remaining pressure in plugged wells will not lift fluid to 

overlying strata. Any uncertainty in characterizing post-injection site care 

timeframes for GS, while challenging, could be dealt with through a maximum time 

period, performance standards, and Director discretion. 

The CCS Alliance recommends establishing a maximum 30-year post-operation site 

care and financial responsibility period. The Director would have discretion to 

shorten -- but not to lengthen -- this period if the owner or operator meets 

certain enumerated performance standards based on available data on pressure. 

fluid movement, mineralization and/or dissolution reactions to show whether 

movement of the plume and pressure front have ceased. Once the thirty-year 

period is reached -- or shorter if the performance standards are met -- a 

government backstop would be triggered, thereby ensuring that a risk management 

mechanism is in place beyond the responsibility of the owner or operator. 

Investment requires assumptions about the amount of capital required and for how 

long it is required. If either the maximum amount of capital or the term cannot 

be established, investment is deterred. Further, because most capital available 

will not commit for terms longer than thirty years, and the duration for which 

it is available is generally inversely proportional to risk. Thus, long term 

capital for even low frequency but high severity risks is difficult to obtain. 

To assure public funds can be leveraged with private investment to assure 

widespread deployment of this climate risk mitigating technology, a balance of 

risk and reward is required in the policy development that underpins this UIC 

regulation. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances. 

For this reason, the Class VI rule offers owners or operators flexibility regarding the duration of the

PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe
during the PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, based on

substantial data during the permitting process, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a 50 year post-injection site care timeframe represents a reasonable and protective

monitoring period and available data, including data submitted by commenters, do not support a

different default timeframe. Furthermore, EPA believes that a 50-year default post-injection site care

timeframe, as required at §146.93(b)(1), is not overly burdensome, does not exaggerate the risks

associated with GS, is consistent with other environmental programs, and sufficiently protects

USDWs from endangerment.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA disagrees that the requirements on financial responsibility are overly stringent. The goal of

financial responsibility is to ensure that financial resources are available to prevent the endangerment

of USDWs from improper plugging, remediation, and management of wells in the event that the

owner or operator experiences financial difficulties. EPA adds that the purpose of the GS rule is not

to encourage the use of GS; rather, the purpose of the GS rule is to ensure that, where GS is

deployed, it is conducted in a manner that protects USDWs from endangerment. 

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23822

Comment: VI. SPECIAL FOCUS: FINANCIAL ASSURANCE AND LONG TERM SITE 

RESPONSIBILITY 

Financial assurance and long-term site responsibility are an area of special 

focus for the CCS Alliance. As noted above. we believe the proposed 50-year time 

frame for site care responsibility after a GS facility has ceased operation is 

too long, and there should be a known end point fur site care responsibility up 

front. In addition to these concerns, we offer the following comments on 

financial assurance. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

""Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water."" EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including
data submitted by commenters, do not support a different default timeframe. 

However, EPA recognizes that alternative timeframes may be appropriate under limited, specific

circumstances. For this reason, the Class VI rule offers owners or operators flexibility regarding the

duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the

PISC timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a 50 year post-injection site care timeframe represents a reasonable and protective

monitoring period and available data, including data submitted by commenters, do not support a

different default timeframe. Furthermore, EPA believes that a 50-year default post-injection site care

timeframe, as required at §146.93(b)(1), is not overly burdensome, does not exaggerate the risks

associated with GS, is consistent with other environmental programs, and sufficiently protects

USDWs from endangerment.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA recognizes that there are challenges associated with assuring funding for activities that will

occur far in the future. However, the Agency believes that in order to protect USDWs from

endangerment under the SDWA operators must demonstrate under §146.85 that financial resources

are available to plug the injection well and provide post-injection site care at the point in time that

the first CO2 is injected.

EPA also recognizes the concerns associated with assuring financial responsibility for the long time

frames over which post-injection site care will be conducted. EPA is developing guidance on

financial responsibility to assist owners or operators in evaluating the requirements of §146.85 and to

assist Directors in evaluating financial responsibility demonstrations. The guidance describes the

types of financial mechanisms that operators may choose to use when evaluating the financial

responsibility requirements for GS wells and it will also include a section on how to estimate costs to

support accurate financial responsibility demonstrations. The guidance will be available at

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

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23841

Comment: C. POST-INJECTION SITE CARE PERIOD AND FINANCIAL RESPONSIBILITY 

The Agency has proposed a post-injection site care and financial responsibility 

period of 50 years, which can be shortened or lengthened based on the discretion 

of the Director. The CCS Alliance agrees, in part, with this suggested use of a 

combination of a fixed timeframe and performance standard. However, as 
previously explained, the CCS Alliance recommends establishing a maximum 30-year 

post-closure period and providing the Director with discretion to shorten -- but 

not lengthen -- this period if the owner or operator meets certain enumerated 

performance standards based on available data on pressure, fluid movement. 

mineralization and/or dissolution reactions to show whether the plume and 

pressure front have stabilized. 

CCS is an activity the Agency hopes to encourage. A 50-year post-injection site 

care default is longer than any period of post-operation site care of which the 

Alliance is aware. The potential for threats to USDWs will have been considered 

prior to site operation. and will have been reconsidered throughout the life of 

the project, not only by the regulator, but by the owner or operator, entities 

providing financial support, and providers of risk management products and 

services. Continuance of injection will have depended upon an assessment of the 

potential for threats to USDWs at numerous points during the site's operation. 

EPA suggests that when owners or operators show that "models predicting CO2 

movement are consistent with monitoring results and that there are no longer 

risks of endangerment to USDWs. they could request that the Director authorize 

site closure."[FN43] The CCS Alliance suggests that if EPA considers the 

relationship between modeling results and actual plume movement in determining 

the continuation of post- injection site responsibility, the standard need not 

be "consistency." Models may predict a range of outcomes. Notwithstanding 

falling outside the modeled range, actual plume movement may be safe. including 

when there are no USDWs in the area. The Alliance recommends that the rule 

authorize Directors to end the post-injection site responsibility period prior 

to the 30-year period, taking into account their ability reasonably to predict 

the likelihood of minimal or no risk to USDWs. 

[FN43] Proposed Rule. 73 Fed. Reg. at p. 43491 (emphasis added). 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the Class VI rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording

the Director discretion to allow a Class VI well owner or operator to demonstrate, based on

substantial data during the permitting process, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA agrees that proper site characterization is a critical component of ensuring that USDWs are

protected. However, EPA disagrees that this is a substitute for post-injection site care. EPA believes

that extensive post-injection monitoring is necessary to protect USDWs from endangerment. 
Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23641

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: 146.93 

(b)(1) 

Monitoring for 50 years following cessation of injection has no particular basis 

in research and should not be the rule against which an operator should be 

required to seek an exception as provided for in (b)(2). Rather, the regulations 

should require a maximum post-injection site monitoring plan for, for example, 

15 years to include comprehensive reservoir assessment, modeling, and simulation 

based on data collection during injection and then specifically at closure, 

followed by five years after closure, 10 years after closure, and 15 years after 

closure. These suggested intervals have a basis in the changes seen in the 4D 

seismic as Sleipner that show demonstrable geophysical responses based on 

injection and plume development over about a 10 year period. Other groups have 

suggested 10 years of total post-closure monitoring, thus other repeat periods 

for site surveys may be suggested and should be considered. For the example 

suggested here, the data taken at closure forms a baseline, such as plume extent 

based on a 3D seismic survey or other geophysical techniques, and three 

subsequent surveys at five-year intervals could document plume migration and 

would serve to validate reservoir simulation. If the total of four such example 

surveys (closure, +5, +10, and +15) and/or other appropriate monitoring 

techniques, and the reservoir modeling and simulation, demonstrate a consistent 

and predictable understanding of subsurface behavior that does not endanger 

USDWs going forward, then the operator should be deemed to have fulfilled site 

closure responsibilities. To repeat, there is no basis for the suggested 50 

years of monitoring. 

Response: EPA disagrees that there is no basis for the 50 year timeframe. In determining the postinjection site care-timeframe for the proposed regulation, EPA reviewed industry reports, existing

environmental programs, and initial GS research studies. EPA provided a synthesis of pertinent

results from GS modeling studies in the preamble to the proposed regulation. Further explanation of

this analysis was included in an EPA-prepared background document that is available in the federal

docket, titled "Computational Modeling of Underground Injection of Carbon Dioxide for

Determination of Area-of-Review and Potential Risk to Underground Sources of Drinking Water."

Based on review of these studies, modeling results indicate that the CO2 plume stabilization may

occur on the timeframe of 10-100 years after the cessation of injection. EPA believes that a 50-year

default post-injection site care timeframe is a reasonable midpoint for most GS projects and

available data, including data submitted by commenters, do not support a different default timeframe,

and has retained this in the final regulation.

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the Class VI rule offers owners or operators flexibility regarding the

duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the

PISC timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to
demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA clarifies that, throughout the post-injection site care timeframe, owners and operators must

submit monitoring data results to the Director. At these times (or at 5 year intervals), the owner or

operator may wish to discuss whether performing a non-endangerment demonstration may be

appropriate. This scenario affords many of the suggestions the commenter offers. 

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23705

Comment: Category: Post-Injection 

EPA Request for Comment: EPA requests comment on the proposed use of a tentative 

50-year fixed timeframe that could be modified at the Director’s discretion 

based on monitoring and modeling data. EPA Notice 43519. 

EPA is requesting comments on the proposed requirements for well plugging, postinjection site care, and site closure, including the proposed requirements for 

the post-injection time period. EPA Notice 43520. 

AWWA Response: AWWA recommends that the time period for post-injection site care 

be set at a minimum of 50-years and that the Director not be given any 

discretion to shorten this time period. After this 50-year period, the operator 

must continue to monitor until such time as they can demonstrate that the plume 

has stabilized and that it does not present any potential danger to USDWs or 

other potential sources of drinking water. This requirement is not overly 

prescriptive or burdensome given the information available on the long-term 

behavior of carbon dioxide plumes. This time period is necessary to monitor the 

site for changes that may occur over a longer amount of time, such as gradual 

leakages, fault movement, or sudden seismic shifts. After this time period, the 

owner/operator may apply to the Director for a modification or termination of 

the monitoring requirements. 

Response: EPA agrees that a 50 year post-injection site care timeframe represents a reasonable and

protective post-injection site monitoring period for most GS projects and available data, including

data submitted by commenters, do not support a different default timeframe. EPA bases this on a

review of research studies, industry reports, and existing environmental programs, and evaluation of

public comments. Furthermore, EPA believes that a 50-year default post-injection site care

timeframe is not overly burdensome, does not exaggerate the risks associated with GS, is consistent

with other environmental programs, and sufficiently protects USDWs from endangerment. For this

reason, the final GS regulation retains the 50 year post-injection site care timeframe, as specified in

§146.93(b)(1).
However, EPA disagrees that a 50 year post-injection site care timeframe should be an absolute

minimum. Rather, EPA believes, as some commenters suggest, that there will be circumstances

where it can be demonstrated in less than 50 years that the plume and pressure front no longer pose a

risk of endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24372

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

language 

Comment: Part 146.93(b)(2) AWWA recommends that there should be a minimum 50 year postinjection monitoring period for all carbon sequestration projects. This time 

period is necessary to monitor the site for changes that may occur over a longer 

amount of time, such as gradual leakages, or sudden seismic shifts. After this 

time period, the owner/operator may apply to the Director for a modification or 

termination of the monitoring requirements. AWWA recommends revising this part 

to read: 

If, after the 50-year post-injection monitoring period, the owner or operator 

can demonstrate to the satisfaction of the Director, based on monitoring and 

other site-specific data, that the geologic sequestration project no longer 

poses an endangerment to USDWs, the Director may approve an amendment to the 

post-injection site care and site closure plan to reduce the frequency of 

monitoring or may authorize site closure before the end of the 50-year period. 

Response: As described above, EPA agrees with commenters that a 50 year post-injection site care

timeframe represents a reasonable and protective post-injection site monitoring period in most cases

and available data, including data submitted by commenters, do not support a different default

timeframe. EPA bases this on a review of research studies, industry reports, and existing

environmental programs, and evaluation of public comments. Furthermore, EPA believes that a 50-

year default post-injection site care timeframe is not overly burdensome, does not exaggerate the

risks associated with GS, is consistent with other environmental programs, and sufficiently protects

USDWs from endangerment. For this reason, the final GS regulation retains the 50 year postinjection site care timeframe, as specified in §146.93(b)(1).
However, EPA disagrees that a 50 year post-injection site care timeframe should be an absolute

minimum. Rather, EPA believes, as some commenters suggest, that there will be circumstances

where it can be demonstrated in less than 50 years that the plume and pressure front no longer pose a

risk of endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Wendy Jacobs Letter ID: 0183

Commenter Organization: Harvard Law School Environmental Law and Policy

Center

Comment ID:

25144

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: C. EPA Should Clarify the Site Closure Standard 

EPA is proposing a "combination of fixed timeframe and performance standard"

approach to site closure. 73 Fed. Reg. at 43,519. Under the proposal, the owner

or operator would be required to undertake "post-injection site care" following

the permanent cessation of injection activities at the site, which would include

"submit[ting] periodic reports providing monitoring results and updated modeling

results as appropriate until a demonstration of nonendangerment to USDWs can be

made." Id. at 43,520. Specifically, the owner or operator would need to

demonstrate "that the carbon dioxide plume and pressure front have stabilized

and that no additional monitoring is needed to assure that the geologic

sequestration project does not pose an endangerment to USDWs." Id. at 43,541

(proposed 40 C.F.R. § 146.93(b)(3)). Once the owners or operators provide

documentation to show that this standard has been met, they can request that the

Director authorize site closure. Id. at 43,520. By default, the "post-injection

site care" period would last for 50 years following cessation of injection

activities; however, the Director would have discretion to shorten the 50-year

timeframe if the owner or operator could demonstrate "stabilization/no

endangerment" in less than 50 years, or conversely, to lengthen the timeframe if

the owner or operator failed to make a demonstration within 50 years. Id.
As a general matter, ELPC and ETIP agree that a combination of a fixed timeframe

and a performance standard strikes a good balance and is preferable to relying

upon only one of those elements. Adherence to an exacting performance standard

alone, defined before commercial deployment of CCS technologies, could preclude

owner or operators from taking advantage of best practices as they are

developed. Adherence to a single fixed timeframe could allow owner or operators

to abandon well sites even as monitoring data indicates a threat to a USDW.

Requiring the owner or operator to meet a flexible performance standard

throughout a baseline period of 50 years would ensure that post-injection site

care, including monitoring and verification, would continue as long as necessary

to prevent endangerment of USDWs and require post-injection monitoring and

modeling even if the data appear to show "stabilization" within a short

timeframe. This would be especially prudent in the short term, given lack of

data and experience with large-scale, long-term GS projects.

Response: EPA agrees and has implemented a combination fixed timeframe and performance

standard approach for post-injection site care monitoring for Class VI wells. EPA believes that a

default PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this timeframe,

combined with a site-specific Director’s discretion to create an alternative PISC time frame, ensures

that USDWs are protected. The GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Bradley J. Field Letter ID: 0186

Commenter Organization: New York State Dept. of Environmental Conservation

Div. of Mineral Resources

Comment ID:

25211

Comment: III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

MM. EPA requests comment on the proposed use of a tentative 50-year fixed 

timeframe that could be modified at the Director’s discretion based on 

monitoring and modeling data. 

NYSDEC-DMN Response: Given that current injection and reservoir behavior data 

demonstrates a decreasing risk of leakage after injection ceases, NYSDEC-DMN 

believes that a 50-year default time frame for post-injection site care is too 

long and that a 30-year starting period may be more appropriate to allow GS 
projects to move forward. It would be better to prescribe a shorter period with 

discretion to go longer, rather than vice versa, as such would better facilitate 

project planning. Regardless, it is critical that the Director have the 

discretion to increase or decrease the period based on the specifics of a 

particular project. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances.

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Bradley J. Field Letter ID: 0186

Commenter Organization: New York State Dept. of Environmental Conservation

Div. of Mineral Resources

Comment ID:

25212

Comment: NN. EPA is requesting comments on the proposed requirements for well plugging, 

post- injection site care, and site closure, including the proposed requirements 

for the post-injection time period. 
NYSDEC-DMN Response: Given that current injection and reservoir behavior data 

demonstrates a decreasing risk of leakage after injection ceases, NYSDEC-DMN 

believes that a 50-year default time frame for post-injection site care is too 

long and that a 30-year starting period may be more appropriate to allow GS 

projects to move forward. It would be better to prescribe a shorter period with 

discretion to go longer, rather than vice versa, as such would better facilitate 

project planning. Regardless, it is critical that the Director have the 

discretion to increase or decrease the period based on the specifics of a 

particular project. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances.

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Daniel Plath Letter ID: 0188

Commenter Organization: NiSource, Inc. Comment ID: 25240

Comment: 7. Post Site Care and Site Closure (146.93) 
A fixed time period of 50 years of post injection site monitoring before site 

closure can occur is highly speculative as noted by EPA in the Preamble. 

NiSource believes that the appropriate method is a performance-based standard 

which is site specific. While we recognize the potential flexibility granted in 

146.92(b)(2) for the Director to permit a shorter time period if supported by 

the data, the reality is that when a potential operator is evaluating 

development of a site, the 50 year monitoring period will be used. This may have 

the chilling effect of discouraging would-be developers from undertaking a GS 

project in the first place. On the other hand, if while collecting site 

evaluation data a potential operator has the ability to model the potential 

closure period based on the expected performance of the reservoir, then they are 

likely to be more willing to undertake the project if the initial data indicates 

a more reasonable site closure time frame. This would also encourage the 

development of new technologies to more efficiently manage the closure period. 

Based on many of the other discussions taking place on the GS topic, such as the 

Interstate Oil and Gas Compact Commission's recommendations, this is a topic 

that may likely have a legislative solution as opposed to a regulatory solution. 

The primary outcome of EPA's inclusion of this feature in the Final Rule has the 

potential of encumbering efforts to develop GS as a viable means of long-term 

storage of CO2. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24497

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

language; 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Rule Provision: 146.93(b) 

Proposed CCS Group Recommendations: (b) The owner or operator shall monitor the 

site following the cessation of injection to show the position of the carbon 

dioxide plume and pressure front and demonstrate that USDWs are not being 

endangered.

(1) The owner or operator shall continue to conduct monitoring as specified in 

the Director-approved post-injection site care and site closure plan, UNTIL 

CLOSURE IS AUTHORIZED PURSUANT TO 146.93(B)(3). 

Basis for CCS Group Comments: EPA should also reconsider its proposed 50-year 

default period for post-injection site care. EPA offers no rationale for this 

arbitrarily-selected period of 50 years. Establishing a fixed and unusually long 

time period may create a significant barrier for operators considering entry 

into CCS operations. Criteria for determining the period for post-injection site 

care should be performance-based and a function of the site specific 

characteristics of a project such as project size, geologic factors, and 

relative risk of the project. Such criteria are provided in our edits to 

§146.93(b)(3). 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most

cases or arbitrary. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

acknowledges there will be circumstances where it can be demonstrated in less than 50 years that the

plume and pressure front no longer pose a risk of endangerment to USDWs. For this reason, the GS

rule offers owners or operators flexibility regarding the duration of the PISC timeframe by: (1)

allowing the Director discretion to shorten or lengthen the PISC timeframe during the post-injection

period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the

Director discretion to allow a Class VI well owner or operator to demonstrate, during the permitting

process based on substantial data, that an alternative PISC timeframe may be appropriate if it ensures

non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research
studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24498

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

language; 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Rule Provision: 146.93(b)(2) 

Proposed CCS Group Recommendations: (2) If the owner or operator can request and 

demonstrate to the satisfaction of the Director before 50 years, based on 

monitoring and other site-specific data, that the geologic sequestration project 

no longer poses an endangerment to USDWs, the Director may approve an amendment 

to THAT the post-injection site care and site closure plan SHOULD BE REVISED 

to reduce the frequency of monitoring, THE DIRECTOR SHALL APPROVE THE REDUCTION. 

or may authorize site closure before the end of the 50-year period.

Basis for CCS Group Comments: See rationale stated above for eliminating 50-year 

period. 

Response: As described above, EPA disagrees that a post-injection site care timeframe of 50 years is

excessive in most cases or arbitrary, and retains the default 50-year post-injection site care

timeframe in the final rule.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24500

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

language; 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(4) 

Proposed CCS Group Recommendations: (4) If such a demonstration cannot be made 

(i.e., if the carbon dioxide plume and pressure front have not stabilized) after 

the 50-year period, the owner or operator must submit to the Director a plan to 

continue post-injection site care.

Basis for CCS Group Comments: No longer necessary with 50-year period deletion. 

Response: As described above, EPA believes that to ensure USDW protection from endangerment, a
default timeframe for post-injection site care is necessary in most cases. A 50-year post-injection site

care timeframe represents a reasonable and protective monitoring period for most GS sites based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24547

Comment: Rule Provisions or Federal Register Cite: 73 FR 43519-20, 146.93(b) 

EPA Preamble Question: 38. EPA is proposing using a combination of fixed 

timeframe and a performance standard as described above. EPA is tentatively 

proposing a post-injection site care (monitoring) period of 50 years with 

Director’s discretion to change that period to lengthen or shorten the 50 year 

period if appropriate. EPA requests comment on the proposed use of a tentative 

50 year fixed timeframe that could be modified at the Director’s discretion 

based on monitoring and modeling data. EPA Notice 43519. 

CSC Response: We believe there are three problems with the closure standard in 

proposed section 146.93(b). First, the presumption that monitoring should 

continue for 50 years is unnecessary and counterproductive. A straight 

performance standard is preferable to this or any other fixed time period 

because it provides a clearer standard and an incentive to maximize the 

understanding of site and project performance and as such is more protective of 

USDWs. Second, the proposal requires a showing that the CO2 plume has 

"stabilized", which is undefined. Cessation of plume movement is not necessarily 

essential to show that a project poses no threat of endangerment to USDWs-plumes 

that are still moving may, nonetheless, remain contained. Instead, it is more 

protective to show that the plume is not expected to encounter a leakage 

pathway. Third, the required showing that "no additional monitoring is needed" 

does not provide guidance regarding how an operator is to show that no 

additional monitoring is needed. The proposal below provides specific guidance 

on what the operator must show. 

We recommend the standard in the proposed alternative language for section 

146.93(b) because it sets forth detailed criteria, all of which must be 

satisfied, to demonstrate that the site does not pose an endangerment to USDWs. 

The specific criteria listed in our proposal will serve to provide the Director 

with the requisite information to make the appropriate determination. The 

advantage of this approach is that it establishes clear criteria that an 

operator must demonstrate before obtaining site closure based upon particular 

site characteristics and is, therefore, reasonably applicable to any storage 

site as opposed to a standard based upon a fixed-duration. Furthermore, it is 

more stringent than a purely discretionary approach because it establishes 

specific criteria that must be shown before site closure may be granted. We 

believe this language, which is an extension of work done by the World Resources 

Institute and the Ground Water Protection Council, avoids the noted shortcomings 

and provides stronger protection for USDWs. 

This is the same recommendation as presented by the multi-stakeholder group, in 

which the Carbon Sequestration Council participated 
Response: EPA disagrees with the suggested changes. As noted above, EPA disagrees that a postinjection site care timeframe of 50 years is excessive for most Class VI wells. 

EPA acknowledges the concerns of some commenters that there will be circumstances where it can

be demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist

Directors in evaluating proposed well plugging plans and post-injection site care and site closure

plans required under 146.92 and 146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells, perform post-injection monitoring,

demonstrate the appropriateness of an alternative post-injection site care time frame, demonstrate

non-endangerment, and perform site closure activities. This guidance will be available at

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

Commenter Name: Kyle Isakower Letter ID: 0191

Commenter Organization: American Petroleum Institute Comment ID: 23880

Comment: Closure Standard 

We believe there are three problems with the closure standard in proposed 

section 146.93(b). First, the presumption that monitoring should continue for 50 

years is unnecessary and counterproductive. A straight performance standard is 

preferable to this or any other fixed time period because it provides a clearer 

standard and an incentive to maximize the understanding of site and project 

performance and as such is more protective of USDWs. Second, the proposal 

Response: The post-injection site care requirements in the final GS rule, §146.93(b), incorporate a

combination of a 50-year default post-injection site care timeframe, in conjunction with a

performance standard, for Class VI wells. The GS rule offers owners or operators flexibility
regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts. EPA expects that the

Director will consider the types of information the commenter describes in determining whether the

plume and pressure front no longer pose a risk of endangerment to USDWs and post-injection site

care monitoring may be discontinued. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23901

Comment: Closure Standard 

ConocoPhillips believes there are three problems with the closure standard in 

proposed section 146.93(b). First, the presumption that monitoring should 

continue for 50 years is unnecessary and potentially counterproductive. A 

straight performance standard is preferable to this or any other fixed time 

period because it provides a clearer standard and an incentive to maximize the 

understanding of site and project performance and as such is more protective of 

USDWs. Second, the proposal requires demonstration that the CO2 plume has 
Response: The post-injection site care requirements in the final GS rule, §146.93(b), incorporate a

combination of a 50-year default post-injection site care timeframe, in conjunction with a

performance standard, for Class VI wells. The GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts. EPA expects that the

Director will consider the types of information the commenter describes in determining whether the

plume and pressure front no longer pose a risk of endangerment to USDWs and post-injection site

care monitoring may be discontinued.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. This guidance will be available at

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

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment.

Commenter Name: John R. Baza Letter ID: 0193

Commenter Organization: Utah Division of Oil, Gas, and Mining Comment ID: 23917

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: Post Site Care Responsibility 

EPAs proposed rule sets the post-injection care period at 50 years. This may be 

modified if it can be demonstrated that the plume has stabilized and the 

pressure has dissipated. Setting a 50-year period may be unnecessarily long. The 
Division’s recommendation is that a shorter period be prescribed and then the 

regulating agency may have the discretion to set a longer post-injection care 

period if the specifics of a project indicate such a need. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. 

However, EPA acknowledges there will be circumstances where it can be demonstrated in less than

50 years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For

this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Andy Horn Letter ID: 0196

Commenter Organization: Colorado Ground Water Association (CGWA) Comment ID: 23933

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: Issue 11. The post-closure operator liability timeframe of 50 years should be 

considered a minimum and should be extended in the event monitoring and modeling 

data indicate potential failure may require mitigation. 

Response: EPA agrees with commenters that a 50 year post-injection site care timeframe represents

a reasonable and protective monitoring period for most cases. EPA bases this on a review of
research studies, industry reports, existing environmental programs, and evaluation of public

comments. Furthermore, EPA believes that a 50-year default post-injection site care timeframe is not

overly burdensome, does not exaggerate the risks associated with GS, is consistent with other

environmental programs, and sufficiently protects USDWs from endangerment. For this reason, the

final GS regulation retains the 50 year post-injection site care timeframe, as specified in

§146.93(b)(1). 

However, EPA disagrees that a 50-year post-injection site care timeframe should be an absolute

minimum. Rather, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c). 

Such a demonstration will be site-specific, and based on pressure monitoring and USDW impacts.

EPA clarifies that in no cases will site closure be authorized until the owner or operator demonstrates

to the satisfaction of the Director that the site no longer poses a risk of endangerment to USDWs. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Paul Pike Letter ID: 0198

Commenter Organization: Ameren Corporation Comment ID: 23953

Comment: POST-INJECTION SITE CARE 

The imposition of a fifty-year default fixed timeframe for the post-injection 

site care period will discourage Ameren from seeking to develop CO2 GS wells. 

We agree with EPA that it is likely "that the actual time for CO2 plume 

stabilization ... will be very site specific, being influenced by geologic 

factors such as formation permeability, geochemistry, and the degree of 

capillary trapping." 73 Fed. Reg. at 43519. (emphasis added). We believe that 

there is no single time period that would apply to every CO2 GS site across the 

board, due to the greatly varied characteristics and needs of different CO2 GS 

projects, application of a performance-based standard which is highly sitespecific, rather than a default time period, is an appropriate approach to the 

post-injection site care requirements. Tailoring requirements to a given site, 

a performance-based standard could also encourage the development of methods and 

technology that would achieve long-term protection of USDWs. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of
endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24608

Comment: Rule Provisions: 73 FR 43519-20, 146.93(b) 

EPA Rule Issue: 38. EPA is proposing using a combination of fixed timeframe and 

a performance standard as described above. EPA is tentatively proposing a postinjection site care (monitoring) period of 50 years with Director’s discretion 

to change that period to lengthen or shorten the 50 year period if appropriate. 

EPA requests comment on the proposed use of a tentative 50 year fixed timeframe 

that could be modified at the Director’s discretion based on monitoring and 

modeling data. EPA Notice 43519. 

Anadarko Petroleum Corporation (APC) Response: APC strongly objects to the use 

of a 50-year default monitoring period. EPA offers no rationale for this 

arbitrarily-selected period of 50 years. Establishing a fixed and unusually long 

time period may create a significant barrier for operators considering entry 

into CCS operations. Criteria for determining the period for post-injection site 

care should be performancebased and a function of the site specific 

characteristics of a project such as project size, geologic factors, and 

relative risk of the project. (APC offers such criteria in the edits to 

§146.93(b)(3).) 

Clear guidelines also need to be established regarding when operators have met 

the performance standards that determine site closure. Specifically, the 

standard that the project no longer poses an endangerment to USDWs needs to be 
defined using reasonable risk-based criteria. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most

cases or arbitrary. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances.

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. The guidance describes

recommended approaches for how an owner or operator could plug injection and monitoring wells,

perform post-injection monitoring, demonstrate the appropriateness of an alternative post-injection

site care time frame, demonstrate non-endangerment, and perform site closure activities.

Additionally, the guidance will assist Directors in evaluating proposed well plugging plans and postinjection site care and site closure plans under §146.92 and §146.93. This guidance will be available

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: 24719
Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule

language; 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Rule Provision: 146.93(b)(1) 

Anadarko Petroleum Corporation (APC) Comments: (1) The owner or operator shall 

continue to conduct monitoring as specified in the Director-approved postinjection site care and site closure plan, for at least 50 years following the 

cessation of injection. At the Director’s discretion, the monitoring will 

continue until the geologic sequestration project no longer poses an 

endangerment to USDWs. PURSUANT TO THE PERFORMANCE BASED CRITERIA

DESCRIBED IN 

§146.93(B)(3). 

Rationale: EPA should also reconsider its proposed 50- year default period for 

post-injection site care. EPA offers no rationale for this arbitrarily selected 

period of 50 years. Establishing a fixed and unusually long time period may 

create a significant barrier for operators considering entry into CCS 

operations. Criteria for determining the period for postinjection site care 

should be performance based and a function of the site specific characteristics 

of a project such as project size, geologic factors, and relative risk of the 

project. APC offers such criteria in our edits to §146.93(b)(3). 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most

cases or arbitrary. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances.

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize
site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS. Rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24720

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

language; 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Rule Provision: 146.93(b)(2) 

Anadarko Petroleum Corporation (APC) Comments: (2) If the owner or operator can 

request and demonstrate to the satisfaction of the Director before 50 years, 

based on monitoring and other site-specific data, that the geologic 

sequestration project no longer poses an endangerment to USDWs, the Director may 

approve an amendment to THAT the post-injection site care and site closure 

plan SHOULD BE REVISED to reduce the frequency of monitoring. or may authorize 

site closure before the end of the 50-year period.

Rationale: (See above) 

Response: As described above, EPA disagrees that a post-injection site care timeframe of 50 years is

excessive in most cases or arbitrary, and retains the default 50-year post-injection site care

timeframe in the final rule.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24722

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

language; 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(4) 

Anadarko Petroleum Corporation (APC) Comments: (4) If such a demonstration 

cannot be made (i.e., if the carbon dioxide plume and pressure front have not 

stabilized) after the 50-year period, the owner or operator must submit to the 

Director a plan to continue post-injection site care.

Rationale: No longer necessary given changes above. 

Response: As described above, EPA disagrees that a post-injection site care timeframe of 50 years is

excessive in most cases or arbitrary, and retains the default 50-year post-injection site care

timeframe in the final rule. .
Commenter Name: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22175

Other EPA Comment Codes and Descriptions: 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: Post-Injection Site Care and Closure 

Southern Company opposes a default fifty-year timeframe - or any fixed default 

length of time - for the post-injection site care period. ¡d. at 43519. A 

default post-injection site care period is of little value given the widely 

varied characteristics of future CO2 GS sites, and the significant discrepancy 

between the appropriate post-injection site care period for various Class VI 

wells. As EPA itself recognizes, the actual time required for plume 

stabilization following cessation of injection will be "very site specific." ¡d. 

A site-specific determination, based on conditions at a particular Class VI 

well, will be necessary in the case of every CO2 GS project under the UIC 

Program. The Final Rule should define a performance-based standard for site 

closure and leave the site-specific analysis and determination of appropriate 

post-injection site care period to the Director. Potential Owners or Operators 

are likely to shy away from undertaking a CO2 GS project if the Program's 

requirements may extend decades into the future even when those requirements are 

no longer necessary. A performance-based standard allowing for site-specific 

closure period determinations will avoid the chilling effect that any default 

fixed timeframe for post-injection site care and closure will have on 

participation and investment in C02 GS projects. Moreover, the site-specific 

approach will ensure that an appropriate post-injection site care period is 

identified to meet the needs of each individual Class VI operation. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.
Commenter Name: John Corra Letter ID: 0205

Commenter Organization: Wyoming Department of Environmental Quality

(DEQ)

Comment ID:

22198

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: 4.Requiring a fixed timeframe post-injection site care (monitoring) period of 50 

years: 

a.We recommend that a performance standard be applied to determine the period of 

post-injection site care -that post-injection site care continues until the 

plume is stabilized and will not endanger USDWs. 

b. We recommend that the Director should be provided discretion to shorten or 

lengthen the proposed post-injection site care period of 50 years accordingly. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Michael Stroben Letter ID: 0209

Commenter Organization: Duke Energy Comment ID: 22687

Comment: FINANCIAL RESPONSIBIILITY AND RISK MANAGEMENT APPROACH 

EPA is proposing a default time period of fifty years for post-injection 

activities. Although the proposed rules would gives the Director the discretion 

to adjust the default time period, such a provision will create tremendous 

uncertainty and impose unnecessary regulatory burden and cost on regulators. 

Protecting USDW and commercializing GS technology for CO2 would be better served 
by focusing on site characterization and a site-specific performance based 

approach to well closure that takes into consideration the particular needs of 

each CO2 sequestration site. In addition, a fifty-year default period could 

actually discourage owners or operators from undertaking proper site 

characterization and working to develop innovative ways to safety close wells in 

a shorter time period. It would also introduce significant financial uncertainty 

that could make actually obtaining necessary financial assurances Difficult if 

not impossible. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

To the comment expressing concern about financial responsibility, EPA recognizes that there are

challenges associated with assuring funding for activities that will occur far in the future. However,

the Agency believes that in order to protect USDWs from endangerment under the SDWA operators

must demonstrate under §146.85 that financial resources are available to plug the injection well and

provide post-injection site care at the point in time that the first CO2 is injected.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

EPA agrees that proper site characterization is a critical component of ensuring that USDWs are

protected. However, EPA disagrees that this is a substitute for post-injection site care. EPA believes

that extensive post-injection monitoring is necessary to protect USDWs from endangerment.

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22699

Comment: 8. The period of post-injection site management should be performance-based and 
not be arbitrarily set at 50 years. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA disagrees that the post-injection site care timeframe of 50 years in the final rule is excessive in

most cases or arbitrary. In determining the post-injection site care-timeframe for the proposed

regulation, EPA reviewed industry reports, existing environmental programs, and initial GS research

studies. EPA provided a synthesis of pertinent results from GS modeling studies in the preamble to

the proposed regulation. Further explanation of this analysis was included in an EPA-prepared

background document that is available in the federal docket, titled "Computational Modeling of

Underground Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk

to Underground Sources of Drinking Water." Based on review of these studies, modeling results

indicate that the CO2 plume stabilization may occur on the timeframe of 10-100 years after the

cessation of injection. EPA believes that a 50-year default post-injection site care timeframe is a

reasonable midpoint for most GS projects and available data, including data submitted by

commenters, do not support a different default timeframe, and has retained this in the final

regulation. 

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22740

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: In addition, EPA seeks comment on whether the Director should be allowed to 

shorten the timeframe based on performance information, and whether EPA should 

require a shorter or longer post injection period if data suggests the time 

frame should be adjusted. EPA Notice 125-26. 

EPA should allow the Director to shorten the timeframe based on performance 
information. However, an open-ended time period results in a high degree of 

uncertainty regarding cost exposure to a project developer. It also leaves a 

site open to future liability from "reopeners" by the regulatory community. To 

avoid this latter scenario, a maximum monitoring period should be defined in 

terms of clear, performance-based risk metrics - for example, that the validated 

model predicts that 95% of the plume is or will be trapped and that a 

sensitivity analysis predicts a comfortable margin of safety and diminimus risk 

of endangerment to any USDWs. 

Response: EPA disagrees that the Director should not have discretion to shorten or lengthen the

post-injection site care monitoring period. Because of the variety of site-specific circumstances at

GS sites, EPA believes that Directors, in consultation with operators, will be in the best position to

determine whether additional post-injection site care monitoring is needed (or whether the timeframe

may be shortened), based on the circumstances of a particular project. EPA expects this decision to

be made based on relevant site data and in consultation with all potentially impacted parties to

ensure USDW protection. The final GS regulation retains the provision that the Director may, at his

or her discretion, shorten the post-injection site care timeframe if the owner or operator can

demonstrate that the GS project does not pose an endangerment to USDWs, as specified in

§146.93(b)(2).

Alternatively, the final rule at §146.93(c), also allows the Director to approve an alternative postinjection site care timeframe where an owner or operator can demonstrate during the permitting

process that an alternative post-injection site care timeframe, other than the 50 year default, is

appropriate and ensures non-endangerment of USDWs. The demonstration must be based on sitespecific information, including the results of site-specific computational modeling; the predicted

timeframe for pressure decline; the predicted rate of carbon dioxide plume migration; site-specific

chemical processes that will result in carbon dioxide trapping; the predicted rate of carbon dioxide

trapping; characterization of the confining zone(s); laboratory analyses or studies to verify the

information on trapping; the presence of potential conduits for fluid movement and the quality of

abandoned well plugs within the AoR; the distance between the injection zone and the USDWs

above and/or below the injection zone; and any additional site-specific factors determined by the

Director. The demonstration must meet the criteria at §146.93(c)(2) for ensuring the quality and

accuracy of the data and models on which the demonstration is based. This demonstration would be

submitted as part of the permit application, per §146.82(a)(18), in addition to the PISC and site

closure plan required at §146.82(a)(17).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: John King Letter ID: 0211

Commenter Organization: Shell Exploration and Production Company

(SEPCo)

Comment ID:

22762

Comment: F. 50-year Default Post-Injection Site Care 

SEPCO objects to the use of a 50-year default monitoring period. EPA offers no 
rationale for this arbitrarily selected period of 50 years and establishing a 

fixed and unusually long time period may create a significant barrier for 

operators considering entry into CCS operations. 

Response: EPA disagrees with this comment. In determining the post-injection site care-timeframe

for the proposed regulation, EPA reviewed industry reports, existing environmental programs, and

initial GS research studies. EPA provided a synthesis of pertinent results from GS modeling studies

in the preamble to the proposed regulation. Further explanation of this analysis was included in an

EPA-prepared background document that is available in the federal docket, titled "Computational

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and

Potential Risk to Underground Sources of Drinking Water." Based on review of these studies,

modeling results indicate that the CO2 plume stabilization may occur on the timeframe of 10-100

years after the cessation of injection. EPA believes that a 50-year default post-injection site care

timeframe is a reasonable midpoint for most GS projects and available data, including data submitted

by commenters, do not support a different default timeframe, and has retained this in the final

regulation.

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: John King Letter ID: 0211

Commenter Organization: Shell Exploration and Production Company

(SEPCo)

Comment ID:

22782

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking

comment) (40 CFR 146.93) 

Comment: G. Post-Injection Site Care Responsibility 

The proposed rule contemplates a long post-operational period of observation and 

"site care" prior to closure. The requirements contemplated -- including a 

presumptive 50-year post-injection monitoring period -- are unwarranted and 

completely unprecedented in the UIC program. Not even hazardous waste injection 

wells -- which generally operate subject to a demonstration that waste will be 

contained for at least ten thousand years -- are subject to such burdensome 

post-injection requirements. 
Long term protection of USDWs is ensured up-front, primarily through proper 

siting as confirmed through the technical evaluation that occurs in the 

permitting process. Proper well construction, operating, monitoring and testing 

provide assurance against problems during the operational life of an injection 

well, but siting doesn’t change, and proper siting must be ensured at the start. 

Once injection operations cease, there should generally be no need to do more 

than monitor pressure decay in the injection zone and ensure proper plugging of 

the injection well. This approach is sufficient for the injection of hazardous 

waste, and it certainly should be sufficient for the injection of CO2. The 

premise that careful siting and AOR evaluation are not enough -- that actual 

monitoring for decades after the cessation of injection is needed -- is foreign 

to the UIC program and inconsistent with the long and thoroughly-documented 

success of UIC regulation in the United States. 

There is certainly no justification for a presumptive 50-year minimum timeframe 

for post-injection site care, and such a requirement would likely kill-off 

commercial investment in geo-sequestration projects. It does not help that the 

proposed rule provides a mechanism for shortening the presumptive 50-year 

requirement, because the ability to shorten the post-injection site care period 

would depend on the apparently unlimited discretion of the Director and could 

not be assessed in any meaningful way before injection operations near 

completion. Moreover, the possibility of a shorter post-injection site care 

period is balanced by the possibility that the Director may seek to impose an 

even longer post-injection site care period. The burdens and regulatory 

uncertainties of an extended post-injection site care requirement cannot be 

justified, especially in the context of a regulatory program that requires a 

"non-endangerment" demonstration before injection can even commence. 

Recommendation: 

1. EPA should operate from the premise that the UIC program is preventive in 

nature. 

2. Release from post-injection site care should be determined not by a fixed 

period of time but rather a performance-based standard that is designed to 

ensure protection of USDW’s. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care is necessary in most cases. A 50 year post-injection site care timeframe

represents a reasonable and protective monitoring period for most GS projects and available data,

including data submitted by commenters, do not support a different default timeframe. This
determination is based on a review of research studies, industry reports, and existing environmental

programs, and evaluation of public comments.

EPA agrees that proper site characterization, well construction, and operation are important

components of ensuring that USDWs are protected. However, EPA disagrees that this is a substitute

for post-injection site care. EPA believes that extensive post-injection monitoring is necessary to

protect USDWs from endangerment. 

EPA disagrees that the rule affords ¿unlimited discretion¿ to the Director to lengthen the postinjection site care timeframe. Because of the variety of site-specific circumstances at GS sites, EPA

believes that Directors, in consultation with operators, will be in the best position to determine

whether additional post-injection site care monitoring is needed (or whether the timeframe may be

shortened), based on the circumstances of a particular project. EPA expects this decision to be made

based on relevant site data, including information at §146.93(c)(2), to determine the appropriateness

of an alternative post-injection site care time frame if applicable, and in consultation with all

potentially impacted parties.

EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most Class VI

wells. EPA proposed a default post-injection site care timeframe of 50 years based on a review of

research studies, industry reports, and existing environmental programs. This analysis was included

in an EPA-prepared background document that is available in the federal docket, titled

Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water. EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances,

which is why EPA is providing the Director discretion to approve an alternative post-injection site

care timeframe as long as the owner or operator can meet the requirements provided at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; demonstrate the appropriateness of

an alternative post-injection site care time frame; perform post-injection monitoring; demonstrate

non endangerment; and perform site closure activities. This guidance will be available 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:

22951

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: - 73 FR 43519 -EPA requests comment on the proposed use of a tentative 50-year 

fixed [post injection site care] timeframe that could be modified at the 

Director’s discretion based on monitoring and modeling data. 

Response: AMWA supports a minimum 50-year time frame for post-injection site 

care and recommends that the Director not be given any discretion to shorten 

this time period. EPA notes in the proposal that "the potential risks of 

endangering USDWs will not decline within that timeframe given that 

stabilization may continue for several decades." AMWA also recommends that 

Response: EPA disagrees that the Director should not have discretion to shorten or lengthen the

post-injection site care monitoring period. EPA believes that 50 years is an appropriate default postinjection site care timeframe. However, EPA recognizes that there may be sites where the 50 year

post injection site care timeframe may be either not appropriate or more burdensome than necessary

based on site-specific conditions. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24282

Other EPA Comment Codes and Descriptions: 1360 1.1.3.4 Effectiveness of trapping mechanisms

Comment: B. The Proposed 50-year Term for Post-Injection Site Care Is Unreasonably Long 

Denbury strongly objects to the use of a 50-year timeframe for continuous 

monitoring during post-injection site care. Our objection stems from the 
relative risks associated with the various phases of geologic storage 

operations, the recognized progression of various geologic trapping mechanisms 

(which means that risks of unexpected migration diminish over time), the 

creation of artificial impediments to financial assurance and the sagacity of 

other regulatory proposals. 

First, we believe that published and reputable literature suggests that a 50- 

year timeframe for post-injection site care is too long and wholly unrelated to 

the risks associated with geologic storage. For well-sited, characterized, 

operated and managed sites, the risks accumulate during the operational phase, 

but decline as sites move from post-injection site care to closure to eventual 

long-term care. Prevailing scientific opinion expects the risk profile to 

diminish with time.[FN35] As Lindene and Trabucchi suggest, "the risk of some 

events occurring that result in an unexpected release of carbon dioxide more 

than 10 years after termination of injection will become increasingly remote due 

to geochemistry conditions."[FN36] The geochemistry conditions they reference 

include the four main mechanisms which trap CO2 in well-chosen geological 

formations - 1) structural trapping -- which is addressed in the proposed rule 

and is not necessary to discuss further here; 2) residual CO2 trapping -- where 

CO2 is trapped by capillary forces in the interstices of the rock formation, a 

process which develops about 10 years after injection; 3) dissolution or 

solubility trapping -- where the CO2 dissolves into the brine found in the 

geological formation and sinks because the CO2 saturated brine is more dense 

than non-CO2 saturated brine, a process taking place between 10 and 100 years 

after injection; and finally, 4) mineralization or mineral trapping -- which 

occurs when dissolved CO2 chemically reacts with the formation rock to produce 

minerals, a process requiring hundreds of years.[FN37] 

Given that the greatest risk of a release occurs during the operational stage of 

a storage project, and that residual and dissolution trapping start well in 

advance of 50 years, it is difficult to understand why a 50-year timeframe for 

post-injection site care was chosen. A 50-year post-injection site care 

timeframe simply does not correlate to the relative risks associated with 

geological storage and the function of geologic trapping mechanisms that limit 

the risk of unexpected releases of CO2 after the termination of injection 

activity. 

Furthermore, other respected models use a much shorter period. For instance, the 

IOGCC Model Rules and Legislation stipulate a 10 year post-injection site care 

period.[FN38] Under the IOGCC Model, the operator of the storage site is the 

responsible party and is required to maintain an operational bond for the 

equivalent of a post-injection site care period and until closure. This 10 year 

post-injection site care period is more plainly related to the relative risks of 

geologic storage and the geochemical reactions discussed above. Also, in the 

preamble, EPA acknowledges that a 30-year post-closure care period is recognized 

as the industry standard for the injection of hazardous waste.[FN39] 

[35] See Intergovernmental Panel on Climate Change, Special Report on Carbon 

Dioxide Capture and Storage, 208 (Bert, Metz, et al. eds., 2005); see also Sally 

Benson, "Carbon Dioxide Capture and Storage: Research Pathways, Progress and 
Potential," Global Climate & Energy Project Annual Symposium, October 2007, 

available at 

http://pangea.stanford.edu/research/bensonlab/presentations/Carbon%20Dioxide%20C 

apture%20and%20St 

orage%20-%20Research%20Pathways%20Progress%20and%20Potential.pdf (hereafter 

"Benson 2007"). 

[36] Chiara Trabucchi and Lindene Patton, "Storing Carbon: Options for Liability 

Risk Management, Financial Responsibility," Daily Environment Report, Bureau of 

National Affairs, pg. 8 (Sept. 3, 2008). 

[37] See IPCC Special Report on CCS, supra n.2, at 208; see also Benson 2007, 

supra n.35. 

[38] See generally IOGCC, "Storage of Carbon Dioxide in Geologic Structures: A 

Legal and Regulatory Guide for States and Provinces" (September 2007) 

(publishing Model Statute and Rules for CO2 storage). The proposed 10 year 

default period for maintaining operator responsibility is at Model General Rules 

and Regulations, Section 2.0 (f) (defining "CSP Closure Period" as 10 years 

unless otherwise designated by the State Regulatory Agency). See also at Section 

4.0 (b) (10) (requiring performance bond to be maintained for 10 years after 

closure of the facility in accordance with Section 9.0). The discussion of the 

Model Statute and Regulation also mentions other potential periods of "10 or 29 

years, etc." IOGCC, supra, at 30. 

[39] See 73 Fed. Reg. at 43,510. 

Response: EPA agrees that some owners or operators will be able to demonstrate, in less than 50

years, that the pressure front and plume no longer pose a risk of endangerment to USDWs. However,

based on studies, EPA believes that the 50-year default time frame is warranted in most cases based

on additional review of research studies and reports and evaluation of public comments.

EPA believes that the best way to address all possibilities, while ensuring USDW protection from

endangerment, is to set a 50 year default post-injection site care timeframe, with flexibility to: (1)

allow the Director discretion to shorten or lengthen the PISC timeframe during the PISC period

based on site-specific data, pursuant to requirements at §146.93(b); or (2) afford the Director

discretion to allow a Class VI well owner or operator to demonstrate, based on substantial data

during the permitting process, that an alternative PISC timeframe may be appropriate if it ensures

non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA clarifies that, in determining the post-injection site care-timeframe for the proposed regulation,

EPA reviewed industry reports, existing environmental programs, and initial GS research studies.
EPA provided a synthesis of pertinent results from GS modeling studies in the preamble to the

proposed regulation. Further explanation of this analysis was included in an EPA-prepared

background document that is available in the federal docket, titled ""Computational Modeling of

Underground Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk

to Underground Sources of Drinking Water."" Based on review of these studies, modeling results

indicate that the CO2 plume stabilization may occur on the timeframe of 10-100 years after the

cessation of injection. EPA believes that a 50-year default post-injection site care timeframe is a

reasonable midpoint for most GS projects and available data, including data submitted by

commenters, do not support a different default timeframe, and has retained this in the final

regulation. 

To the comment about the cost of post-injection site care, EPA does not agree that post-injection site

care timeframes longer than 30 years will be prohibitively expensive. In fact, EPA believes that postinjection site care monitoring will represent a relatively minor component of total project cost, and

will provide an essential level of protection from endangerment for USDWs. A discussion of the

costs attributed to monitoring technologies (used during injection and the post-injection site care

timeframes) is available in the Technology and Cost Document for the GS rule, which is in the

federal docket for this rulemaking. EPA believes that it is logical to make use of existing monitoring

infrastructure at a GS site in order to ensure USDWs are not endangered. 

EPA also recognizes the concerns associated with assuring financial responsibility for the long timeframes over which post-injection site care will be conducted. However, the Agency believes that, in

order to protect USDWs from endangerment under the SDWA, operators must demonstrate under

§146.85 that financial resources are available to plug the injection well and provide post-injection

site care at the point in time that the first CO2 is injected. EPA is developing guidance on financial

responsibility to assist owners or operators in evaluating the requirements of §146.85 and to assist

Directors in evaluating financial responsibility demonstrations. The guidance describes the types of

financial mechanisms that operators may choose to use when evaluating the financial responsibility

requirements for GS wells and it will also include a section on how to estimate costs to support

accurate financial responsibility demonstrations. The guidance will be available at

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

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24283

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

Long-Term Care Requirements 

Comment: Finally, this 50-year timeframe raises barriers to obtaining financial assurance 

for prospective projects. Section 146.85 of the Proposed Rule requires the owner 

or operator to maintain financial responsibility for corrective action, 

injection well plugging, post-injection site care and site closure. Undoubtedly 

owners/operators will enter the private sector financial assurance market for 

some period in order to meet this requirement. An uncertain or a 50-year postinjection site care timeframe creates impediments to managing this financial 

responsibility. We believe that both an indeterminate or an exceedingly long 

post-injection site-care period will discourage the development of private 

sector products to address financial responsibility and discourage sequestration 

in general. 

Response: EPA disagrees that the requirements for financial responsibility are overly stringent or
unreasonable. The goal of financial responsibility is to ensure that financial resources are available to

prevent the endangerment of USDWs from improper plugging, remediation, and management of

wells in the event that the owner or operator experiences financial difficulties throughout the life of

the project. See the final rule and preamble for further discussion of EPA's final approach to

financial responsibility.

EPA believes that minimum financial responsibility requirements are necessary to hold well owners

or operators accountable for the safe operation and proper site closure of the well in order to protect

USDWs while also avoiding expense and risk to the public. EPA adds that the purpose of the GS

rule is not to encourage the use of GS; rather, the purpose of the GS rule is to ensure that, where GS

is deployed, it is conducted in a manner that protects USDWs from endangerment. 

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24284

Comment: Given the limited risk profile of the post-operational phase of geologic 

storage, the precedent set by other proposals, and the likely impediments to 

financial responsibility and insurance caused by an uncertain or exceedingly 

lengthy post-injection site care period, we think that a 50-year post-injection 

site care period is unsupported by the science, unnecessary to protect USDWs and 

unwarranted by current EOR experience. While we agree that in most instances 

site-specific performance standards are most appropriate, we believe that in 

this instance a definite and reasonable timeframe should be established that is 

supported by the relative risks involved and that facilitates the development of 

financial assurance products. We believe a 10 year post-injection site care 

period protects USDWs, facilitates post-injection financial assurance and is 

consistent with our understanding of how geologic trapping of CO2 occurs. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most

cases or arbitrary. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances.

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).
EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

To the comment about the cost of post-injection site care, EPA does not agree that post-injection site

care timeframes longer than 30 years will be prohibitively expensive. In fact, EPA believes that postinjection site care monitoring will represent a relatively minor component of total project cost, and

will provide an essential level of protection from endangerment for USDWs. A discussion of the

costs attributed to monitoring technologies (used during injection and the post-injection site care

timeframes) is available in the Technology and Cost Document for the GS rule, which is in the

federal docket for this rulemaking. EPA believes that it is logical to make use of existing monitoring

infrastructure at a GS site in order to ensure USDWs are not endangered.

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24313

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

language; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: I. § 146.93 Post-injection site care and site closure. 

The proposed rule establishes a 50 year default period for post-injection site 

care. There is, however, no factual or scientific basis for such an extensive 

period. Under EPA’s Resource Conservation and Recovery Act rules, which regulate 

the disposal of hazardous wastes, post closure care is limited to 30 

years.[FN45] Defaulting to an excessively long period will increase costs and 

introduce greater regulatory uncertainty, which will discourage capital 

formation around CO2 sequestration. A more prudent regulatory approach is to set 

a minimum period for site care, ten years, with allowance for the Director to 

extend the period if facts and circumstances warrant a longer post-injection 

site care period. 

Additionally, the proposed rule’s 50 year default post injection site care 

period, is an illusory deadline, as it is not self-executing. Under the rules, 

post injection site care must continue indefinitely until the Director 

authorizes closure. The closure approval process could take years, even decades, 

as the Director has no regulatory incentive to act on any post injection site 

care report. Meanwhile, a permittee may be required to continue unnecessary and 
expensive monitoring and reporting indefinitely. 

Denbury suggests that the post-injection site care rules be reconfigured to 

require a more limited mandatory post-injection site care timeframe, and to 

allow for closure at the end of that period unless the Director affirmatively 

acts to extend the post-injection site care period. These changes are contained 

in the suggested text below: 

§ 146.93 Post-injection site care and site closure. 

(a) The owner or operator of a Class VI well must prepare, maintain, and 

comply with a plan for post-injection site care and site closure that 

meets the requirements of paragraph (a)(2) of this section and is 

acceptable to the Director. 

(1) The owner or operator must submit the post-injection site 

care and site closure plan as a part of the permit application to be 

approved by the Director. 

(2) The post-injection site care and site closure plan must 

include the following information: 

(i) The pressure differential between pre-injection and 

predicted post-injection pressures in the injection zone; 

(ii) The predicted position of the carbon dioxide plume 

and associated pressure front at site closure as demonstrated in 

the area of review evaluation required under § 146.84(b); 

(iii) A description of post-injection monitoring 

location, methods, and proposed frequency; and 

(iv) A proposed schedule for submitting post-injection 

site care monitoring results to the Director. 

(3) Upon cessation of injection, owners or operators of Class VI 

wells must either submit an amended post-injection site care and site 

closure plan or demonstrate to the Director through monitoring data and 

modeling results that no amendment to the plan is needed. 

(4) The owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval 

within 30 days of such change. 

(b) The owner or operator shall monitor the site following the cessation 

of injection to show the position of the carbon dioxide plume and 

pressure front and demonstrate that USDWs are not being endangered. 

(1) The owner or operator shall continue to conduct monitoring 

as specified in the Director-approved post-injection site care and site 

closure plan for at least 50 10 years following the cessation of 

injection. At the UPON A DETERMINATION BY THE Director ’s

THAT THE GEOLOGIC SEQUESTRATION PROJECT MAY POSE AN ENDANGERMENT TO 

USDWS discretion , THE DIRECTOR, AT HIS DISCRETION, MAY REQUIRE 

the monitoring will TO continue FOR A TIME PERIOD SPECIFIED BY 

THE DIRECTOR until the geologic sequestration project no longer poses 

an endangerment to USDWs.

(2) If the owner or operator can demonstrate to the satisfaction 

of the Director before 50 10 years, based on monitoring and other 

site-specific data, that the geologic sequestration project no longer 

poses an endangerment to USDWs, the Director may approve an amendment to 
the post injection site care and site closure plan to reduce the 

frequency of monitoring or may authorize site closure before the end of 

the 50 10 year period. 

(3) Prior to authorization for THE EXPIRATION OF THE 10 

YEAR POST-INJECTION SITE CARE PERIOD, site closure, the owner or 

operator must submit to the Director a demonstration, based on 

monitoring and other site specific data, that the carbon dioxide plume 

and pressure front have stabilized and that no additional monitoring is 

needed to assure that the geologic sequestration project does not pose 

an endangerment to USDWs. 

(4) IF WITHIN 180 DAYS AFTER THE SUBMITTAL OF THE DATA REQUIRED 

UNDER SUBPARAGRAPH (3) ABOVE THE DIRECTOR DETERMINES THAT THE

GEOLOGICAL 

SEQUESTRATION PROJECT MAY CONTINUE TO POSE AN ENDANGERMENT TO

USDWS, HE 

SHALL SO NOTIFY THE OWNER OR OPERATOR OF HIS DETERMINATION AND THE

BASIS 

THEREFORE, AND If such a demonstration cannot be made (i.e., if the 

carbon dioxide plume and pressure front have not stabilized) after the 

50-year period, the owner or operator must submit to the Director a 

plan to continue post-injection site care. 

(5) IF WITHIN 180 DAYS AFTER THE SUBMITTAL OF THE DATA REQUIRED 

UNDER SUBPARAGRAPH (3) ABOVE THE DIRECTOR FAILS TO DETERMINE AND TO 

NOTIFY THE OWNER OR OPERATOR THAT THE GEOLOGICAL SEQUESTRATION

PROJECT 

MAY CONTINUE TO POSE AN ENDANGERMENT TO USDWS, SITE CLOSURE SHALL BE 

DEEMED AUTHORIZED BY RULE 

(c) Notice of intent for site closure. 

The owner or operator must notify the Director at least 120 days before 

site closure. At this time, if any changes have been made to the 

original post-injection site care and site closure plan, the owner or 

operator must also provide the revised plan. At the discretion of the 

Director, a shorter notice period may be allowed. 

(d) After the Director has authorized site closure OR SITE CLOSURE IS 

AUTHORIZED BY RULE, the owner or operator must plug all monitoring wells 

in a manner which will not allow movement of injection or formation 

fluids that endangers a USDW. 

(e) Once the Director has authorized site closure, OR SITE CLOSURE IS 

AUTHORIZED BY RULE, the owner or operator must submit a site closure 

report within 90 days that must thereafter be retained at a location 

designated by the Director. The report must include: 

(1) Documentation of appropriate injection and monitoring well 

plugging as specified in § 146.92 and paragraph (c) of this section. The 

owner or operator must provide a copy of a survey plat which has been 

submitted to the local zoning authority designated by the Director. The 

plat must indicate the location of the injection well relative to 

permanently surveyed benchmarks. The owner or operator must also submit 

a copy of the plat to the Regional Administrator of the appropriate EPA 

Regional Office; 

(2) Documentation of appropriate notification and information to 
such State, local and tribal authorities as have authority over drilling 

activities to enable such State and local authorities to impose 

appropriate conditions on subsequent drilling activities that may 

penetrate the injection and confining zone(s); and 

(3) Records reflecting the nature, composition and volume of the 

carbon dioxide stream. 

(f) Each owner or operator of a Class VI injection well must record a 

notation on the deed to the facility property or any other document that 

is normally examined during title search that will in perpetuity provide 

any potential purchaser of the property the following information: 

(1) The fact that land has been used to sequester carbon dioxide; 

(2) The name of the State agency, local authority, and/or tribe 

with which the survey plat was filed, as well as the address of the 

Regional Environmental Protection Agency Office to which it was 

submitted; and 

(3) The volume of fluid injected, the injection zone or zones 

into which it was injected, and the period over which injection 

occurred. 

(g) The owner or operator must retain for three years following site 

closure, records collected during the post-injection site care period. 

The owner or operator must deliver the records to the Director at the 

conclusion of the retention period, and the records must thereafter be 

retained at a location designated by the Director for that purpose. 

[45] 40 C.F.R. § 264.117(a)(1) 

Response: The post-injection site care requirements in the final GS rule, §146.93(b), incorporate a

combination of a 50-year default post-injection site care timeframe, in conjunction with a

performance standard, for Class VI wells. The GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts. EPA expects that the

Director will consider the types of information the commenter describes in determining whether the
plume and pressure front no longer pose a risk of endangerment to USDWs and post-injection site

care monitoring may be discontinued.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells, perform post-injection monitoring,

demonstrate the appropriateness of an alternative post-injection site care time frame, demonstrate

non-endangerment, and perform site closure activities. The guidance will be available at

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

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the

University of North Dakota

Comment ID:

21627

Comment: Page 43519. Combination of Fixed Time Frame and Performance Standard 

(monitoring). The EPA is proposing a postinjection monitoring period of 50 

years, with the director having some discretion to either shorten or lengthen 

that time period. Based on the proposed text, 50 years is the default time 

period for postinjection monitoring until data on pressure, fluid movement, 

mineralization, and/or dissolution reactions support a determination that the 

plume has stabilized and does not pose a risk to USDWs. Referring to this as the 

"default" time period and requiring the acquisition of described data sets to 

modify the time period for monitoring indicate that a significant amount of 

characterization effort would have to be conducted during the postinjection 

period, perhaps over several years, to get such a change. The EPA acknowledges 

that modeling results indicate that CO2 plume stabilization likely occurs on the 

time frame of 10 to 100 years after injection stops. One example of a GS site 

where plume stabilization could very well take 50 years or more is a site where 

there is no significant structural trapping element to the reservoir. A plume at 

such a location may behave in a less predictable manner and expand or migrate a 

significant distance before it stabilizes. However, CO2 injected into a 

thoroughly confined high-relief structure (e.g., pinnacle reef, carbonate mound, 

anticline, etc.) would likely stabilize relatively quickly. Barring a seismic 

event that breaches the seal, the movement of such a plume would be nil because 

it would literally have nowhere to go. In those cases, requiring the continued 

collection of several types of data for several years in order to prove what was 

probably obvious years before injection ceased would serve no real purpose other 

than to satisfy an arbitrary regulation. The nature of structural 

characteristics at each site under consideration for GS will be identified 

almost immediately, defined in detail during the earliest stages of site 

evaluation, and the understanding of their geometry will likely be further 

refined over the course of monitoring during the injection phase of the project. 

It is also important to keep in mind that the injection phase of GS projects, 

and the monitoring that goes with them, will, in most cases, be conducted for 

decades. Over those years, knowledge of the reservoir system will increase, and 

by the time the injection phase comes to an end, there will be ample data to 

make informed decisions regarding an appropriate postinjection monitoring 

period. All of this leads to a logical conclusion that the establishment of 
postinjection monitoring periods should be site-specific and flexible. The 50- 

year site monitoring statement appears to have no rational basis and might 

effectively eliminate commercial activity. 

In summary, the proposed default monitoring time frame should be eliminated and 

replaced with a solely performance-based standard that reflects the specifics of 

a project and the knowledge of that project gained through the procedures and 

processes that are already required. The proposed rule gives the program 

director discretion to extend or shorten the postinjection site care period 

based on project-specific considerations; therefore, it seems unnecessary to, by 

rule, establish a lengthy default period. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the final GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23963

Comment: Point #6: The proposed Post-injection Site Care period is too long based on 

prevailing science and risk profiles. The proposed rule establishes a default 

50-year timeframe for the length of the post-injection site care period. TxCCSA 

strongly objects to the use of a 50-year timeframe for post-injection site care. 

Our objection stems from the relative risks associated with the various phases 

of geologic storage operations, the function of various geologic trapping 

mechanisms, the creation of artificial impediments to financial assurance and 

the sagacity of other regulatory proposals. 

First, we believe as the literature suggests that a 50-year timeframe for postinjection site care is too long and wholly unrelated to the risks associated 

with geologic storage. For well-sited, characterized, operated and managed 
sites, the risks accumulate during the operational phase, and decline as sites 

move from post-injection site care to closure to eventual long-term care. 

Therefore, prevailing scientific opinion expects the risk profile to diminish 

with time.[FN6] As Patton and Trabucchi suggest "the likelihood that the risk of 

some events occurring that result in an unexpected release of carbon djoxide 

more than 10 years after termination of injection will become increasingly 

remote due to geochemistry conditions." [FN7] The geochemistry conditions they 

reference include the four main mechanisms which trap CO2 in well-chosen 

geological formations -- 1) structural trapping - which is addressed in the 

proposed rule and is not necessary to discuss further here; 2) residual trapping 

-where CO2 is trapped by capillary forces in the interstices of the rock 

formation which develops about 10 years after injection; 3) dissolution or 

solubility trapping -where the CO2 dissolves into the brine found in the 

geological formation and sinks because the CO2 saturated brine is heavier than 

non-CO2 saturated brine, taking place between 10 and 100 years after injection; 

and 4) finally mineralization or mineral trapping - which happens when dissolved 

CO2 chemically reacts with the formation rock to produce minerals, a process 

requiring hundreds of years.[FN8] 

Given that the greatest risk occurs during the operational stage of a geologic 

storage project and that residual and dissolution trapping start well in advance 

of 50 years, it is difficult to understand why a 50year timeframe for postinjection site care was chosen. A 50-year post-injection site care timeframe is 

simply unrelated to the relative risks associated with geological storage and 

the function of geologic trapping mechanisms that limit the risk of unexpected 

release of CO2 after the termination of injection activity. 

Furthermore, other respected models suggest a much shorter period. For instance. 

the IOGCC Model Rules and Legislation stipulate a 10-29 year post-injection site 

care period.[FN9] Under the IOGCC Model, the operator of the storage site is the 

responsible party and is required to maintain an operational bond during the 

equivalent of a post-injection site care period and until closure. This 10-29 

year post-injection site care period more easily relates to the relative risks 

of geologic storage and the geochemical reactions discussed above. Also, in the 

Preamble, EPA acknowledges that a 30-year post-closure care period is recognized 

as the industry standard for the injection of hazardous waste.[FN10] 

6 See Intergovernmental Panel on Climate Change, Special Report on Carbon 

Dioxide Capture und Storage, 208 (Bert, Metz, et al. eds., 2005); see also Sally 

M. Benson, Carbon Dioxide Capture and Storage: Research Pathways, Progress and 

Potential, Global Climate & Energy Project Annual Symposium, October 2007, 

available at 

http://pangea.stanford.edulresearctv'bensonlab/presentations/Carbon%20Dioxide%20 

CaptureYa20and%20Storage%2OY020ResearchO/020Palhways%20Progress'Y020and%20Potential.pdf. 

7 Chiara Trabucchi and Lindene Patton, Storing Carbon: Optionsfor Liability 

Risk. Management, Financial Responsibility, Daily Environment Report, Bureau 

of National Affairs, pg. 8 (Sept. 3, 2008). 

8 See IPCC 2005 Repon, supra, at 208; see also Benson 

9 See Task Force on Carbon Capture and Geologic Storage, The Interstate Oil and 
Gas Compact Commission, Storage of Carbon Dioxide in Geologic Structures: A Legal 

and Regulatory Guide for States and Provinces (Sept. 25,2007) available at 

http://iogcc.mysbopify.comlcollectionslfrontpagelproductslco2-storage-a 

·Legal·andregulatory-guide-for-states-2008. 

10 See 73 Fed. Reg. at 43510. 

Response: EPA agrees that some owners or operators will be able to demonstrate, in less than 50

years, that the pressure front and plume no longer pose a risk of endangerment to USDWs. However,

based on studies, EPA believes that the 50 year default time frame is warranted based on additional

review of research studies and reports and evaluation of public comments. 

EPA believes that the best way to address all possibilities, while ensuring USDW protection from

endangerment, is to set a 50 year default post-injection site care timeframe, with flexibility to: (1)

allow the Director discretion to shorten or lengthen the PISC timeframe during the PISC period

based on site-specific data, pursuant to requirements at §146.93(b); or (2) afford the Director

discretion to allow a Class VI well owner or operator to demonstrate, based on substantial data

during the permitting process, that an alternative PISC timeframe may be appropriate if it ensures

non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA clarifies that, in determining the post-injection site care-timeframe for the proposed regulation,

EPA reviewed industry reports, existing environmental programs, and initial GS research studies.

EPA provided a synthesis of pertinent results from GS modeling studies in the preamble to the

proposed regulation. Further explanation of this analysis was included in an EPA-prepared

background document that is available in the federal docket, titled ""Computational Modeling of

Underground Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk

to Underground Sources of Drinking Water."" Based on review of these studies, modeling results

indicate that the CO2 plume stabilization may occur on the timeframe of 10-100 years after the

cessation of injection. EPA believes that a 50-year default post-injection site care timeframe is a

reasonable midpoint for most GS projects and available data, including data submitted by

commenters, do not support a different default timeframe, and has retained this in the final

regulation.

To the comment about the cost of post-injection site care, EPA does not agree that post-injection site

care timeframes longer than 30 years will be prohibitively expensive. In fact, EPA believes that postinjection site care monitoring will represent a relatively minor component of total project cost, and

will provide an essential level of protection from endangerment for USDWs. A discussion of the

costs attributed to monitoring technologies (used during injection and the post-injection site care

timeframes) is available in the Technology and Cost Document for the GS rule, which is in the

federal docket for this rulemaking. EPA believes that it is logical to make use of existing monitoring

infrastructure at a GS site in order to ensure USDWs are not endangered. 

EPA also recognizes the concerns associated with assuring financial responsibility for the long time
frames over which post-injection site care will be conducted. However, the Agency believes that in

order to protect USDWs from endangerment under the SDWA operators must demonstrate under

§146.85 that financial resources are available to plug the injection well and provide post-injection

site care at the point in time that the first CO2 is injected. EPA is developing guidance on financial

responsibility to assist owners or operators in evaluating the requirements of §146.85 and to assist

Directors in evaluating financial responsibility demonstrations. The guidance describes the types of

financial mechanisms that operators may choose to use when evaluating the financial responsibility

requirements for GS wells and it will also include a section on how to estimate costs to support

accurate financial responsibility demonstrations. The guidance will be available at

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

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23964

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial

responsibility requirements (40 CFR 146.85) 

Comment: Finally, when mapped to the requirement for financial assurance, this 50-year 

timeframe requirement raises barriers to obtaining financial assurance for 

prospective projects. Section 146.85 of the Proposed Rule requires the owner or 

operator to maintain financial responsibility for corrective action, injection 

well plugging, post-injection site care and site closure. Undoubtedly 

owners/operators will enter the private sector financial assurance market for 

some period in order to meet this requirement. Both an uncertain or 50-year 

post-injection site care timeframe create impediments to financial 

responsibility. We believe that an uncertain or exceedingly long post-injection 

site-care period will discourage the development of private sector products to 

address financial responsibility and discourage geologic storage in general. 

Given the limited risk profile of the post-operational phase of geologic 

storage, the impediments to financial responsibility and insurance caused by an 

uncertain or exceedingly lengthy post-injection site care period and the 

precedent set by other proposals, we think that a 50-year post-injection site 

care period is unsupported by the science, unnecessary to protect USDWs and 

unwarranted by current EOR experience. 

Response: As described above, EPA disagrees that a post-injection site care timeframe of 50 years is

excessive. EPA proposed a default post-injection site care timeframe of 50 years based on a review

of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, there are circumstances (e.g., little

development of mineral trapping of CO2) under which the potential risks of endangering USDWs

will likely not decline within these timeframes. EPA believes that a 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period and available data do not support

a different timeframe. Furthermore, EPA believes that a 50-year default post-injection site care
timeframe, as required at §146.93(b)(1), is not overly burdensome, does not exaggerate the risks

associated with GS, is consistent with other environmental programs, and sufficiently protects

USDWs from endangerment.

To the comment expressing concern about financial responsibility, EPA recognizes that there are

challenges associated with assuring funding for activities that will occur far in the future. However,

the Agency believes that in order to protect USDWs from endangerment under the SDWA operators

must demonstrate under §146.85 that financial resources are available to plug the injection well and

provide post-injection site care at the point in time that the first CO2 is injected. EPA is developing

guidance on financial responsibility to assist owners or operators in evaluating the requirements of

§146.85 and to assist Directors in evaluating financial responsibility demonstrations. The guidance

describes the types of financial mechanisms that operators may choose to use when evaluating the

financial responsibility requirements for GS wells and it will also include a section on how to

estimate costs to support accurate financial responsibility demonstrations. The guidance will be

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

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

EPA acknowledges the concerns of some commenters that there will be circumstances where it can

be demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the final GS regulation includes a provision that the

Director may, at his/her discretion, shorten the post-injection site care timeframe if the owner or

operator can demonstrate that the GS project does not pose a risk to USDWs, as specified in

§146.93(b)(2). Such a demonstration will be site-specific, and based on pressure monitoring and

USDW impacts.

EPA disagrees that the requirements for financial responsibility are overly stringent. The goal of

financial responsibility is to ensure that resources are available to prevent the endangerment of

USDWs from improper plugging, remediation, and management of wells in the event that the owner

or operator experiences financial difficulties throughout the life of the project.

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23993

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: 10. § 146.93 Post-injection site care and site closure. 

The proposed rule establishes a 50 year default period for post-injection site 

care. There is, however, no factual or scientific basis for such an extensive 

period. Under EPA’s Resource Conservation and Recovery Act rules, which regulate 

the disposal of hazardous wastes, post closure care is limited to 30 years. 

Defaulting to an excessively long period will increase costs and introduce 

greater regulatory uncertainty, which will discourage capital formation around 

CO2 sequestration. 

Additionally, even though the proposed rule appears to include a 50 year default 

post injection site care period, in reality, that deadline is illusory as it is 
not self executing. Under the rules, post injection site care must continue 

indefinitely until the Director authorizes closure. The closure approval process 

could take years, even decades, as the Director has no regulatory incentive to 

act on any post injection site care report. Meanwhile, a permittee may be 

required to continue unnecessary and expensive monitoring and reporting 

indefinitely. 

Whether the post-injection site care period is site-specific, or 10 to 50 years, 

TxCCSA suggests that the post-injection site care provision be reconfigured to 

be self-executing and allow for closure at the end of that period unless the 

Director affirmatively acts to extend the post-injection site care period. These 

Response: Because of the variety of site-specific circumstances at GS sites, EPA believes that

individual UIC Directors, in consultation with operators, will be in the best position to determine

whether additional post-injection site care monitoring is needed (or whether the timeframe may be

shortened), based on the circumstances of a particular project. EPA expects this decision to be made

based on relevant site data and in consultation with all potentially impacted parties, and will not be

made arbitrarily. 

EPA believes that 50 years is an appropriate default post-injection site care timeframe. However,

EPA recognizes that, in some cases, the post-injection site care timeframe may need to be

lengthened or shortened based on site-specific circumstances. For instance, if after 50 years,

monitoring data indicates that the CO2 plume is still moving and may endanger a USDW,

monitoring should continue on a regular basis. Conversely, if it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs, continuing

post-injection site care would be unnecessary (see 146.93(b)(2)).

EPA disagrees that the 50 year timeframe is unsupported. In determining the post-injection site caretimeframe for the proposed regulation, EPA reviewed industry reports, existing environmental

programs, and initial GS research studies. EPA provided a synthesis of pertinent results from GS

modeling studies in the preamble to the proposed regulation. Further explanation of this analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." Based on review of these

studies, modeling results indicate that the CO2 plume stabilization may occur on the timeframe of

10-100 years after the cessation of injection. EPA believes that a 50-year default post-injection site

care timeframe is a reasonable midpoint, and has retained this in the final regulation. 

EPA believes that, given the unique challenges associated with GS of large volumes of injected

CO2, post-injection site care should continue until it can be demonstrated that the CO2 plume and

pressure front no longer pose a risk of endangerment to USDWs. For this reason, the final regulation

retains the requirement at §146.93(b)(3) that the owner or operator must submit to the Director a

demonstration, based on monitoring and other site-specific data, that no additional monitoring is

needed to ensure that the GS project does not pose a risk of endangerment to USDWs. Additionally,

the permitting authorities responsible for Class VI wells will maintain an active role with the owner

or operator in order to ensure protection of USDWs from endangerment.

EPA disagrees with the commenter's suggestion regarding self-execution. EPA believes that, given

the unique challenges associated with GS of large volumes of injected CO2, post-injection site care

should continue until it can be demonstrated that the CO2 plume and pressure front no longer pose a
risk of endangerment to USDWs. For this reason, the final regulation retains the requirement at

146.93(b)(3) that the owner or operator must submit to the Director a demonstration, based on

monitoring and other site-specific data, that no additional monitoring is needed to ensure that the GS

project does not pose a risk of endangerment to USDWs. Additionally, the permitting authorities

responsible for Class VI wells will maintain an active role with the owner or operator in order to

ensure protection of USDWs from endangerment.

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21695

Comment: (C) SITE CLOSURE PERIOD 

EPA correctly states in its Preamble that defining the post-injection site care 

period is "difficult to define because it is based on site-specific 

considerations." (73 Fed. Reg. at 43519.) The three studies cited by EPA also 

concluded that "the actual time for CO2 plume stabiliziation . . . will be very 

site-specific, being influenced by geologic factors such as formation 

permeability, geochemistry, and the degree of capillary trapping." (Id.) 

However, the Proposed Rule establishes a default 50-year period (following the 

cessation of injection) during which the operator must conduct monitoring to 

demonstrate that "the carbon dioxide plume and pressure front have stabilized 

and the geologic sequestration project does not pose an endangerment to USDWs." 

(See § 146.93(b).) The designation of a 50year time-period without regard to 

particular site characteristics is arbitrary and not supported by existing 

scientific studies or industry experience. Moreover, the 50-year timeframe does 

not provide any incremental benefit as compared with a performance standard to 

protecting USDWs; rather, it will be a significant deterrent to commercial 

investment in geologic sequestration projects. 

Response: EPA disagrees that the 50 year time frame is unsupported. In determining the postinjection site care-timeframe for the proposed regulation, EPA reviewed industry reports, existing

environmental programs, and initial GS research studies. EPA provided a synthesis of pertinent

results from GS modeling studies in the preamble to the proposed regulation. Further explanation of

this analysis was included in an EPA-prepared background document that is available in the federal

docket, titled "Computational Modeling of Underground Injection of Carbon Dioxide for

Determination of Area-of-Review and Potential Risk to Underground Sources of Drinking Water."

Based on review of these studies, modeling results indicate that the CO2 plume stabilization may

occur on the timeframe of 10-100 years after the cessation of injection. EPA believes that a 50-year

default post-injection site care timeframe is a reasonable midpoint for most GS projects and

available data, including data submitted by commenters, do not support a different default timeframe,

and has retained this in the final regulation.

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at
§146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21696

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: HEI urges EPA to adopt the performance standard that EPA considered in its 

review. EPA considered three options: (1) fixed period; (2) performance 

standard; and (3) combination of fixed period and performance standard; EPA 

states it adopted the latter approach. (73 Fed. Reg. at 43519.) While the 

Proposed Rule allows a Director to reduce the 50-year minimum (§146.93(b)(2)), 

the practical effect will be the 50-year timeframe applies unless an operator is 

able to overcome the presumption built into the Proposed Rule that 50 years is 

adequate. Indeed, this is more prescriptive than the requirement for Class I 

hazardous wells, which provides that the timeframe for post-injection site care 

ends when the plume has stabilized and cannot endanger USDWs. (Id.; 40 CFR 

§146.71.) 

Response: EPA agrees that some owners or operators will be able to demonstrate, in less than 50

years, that the pressure front and plume no longer pose a risk of endangerment to USDWs. However,

based on studies, EPA believes that the 50 year default time frame is warranted based on additional

review of research studies and reports and evaluation of public comments. 

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. EPA believes that the best way to address all possibilities, while ensuring USDW

protection from endangerment, is to set a 50 year default post-injection site care timeframe, with

flexibility to: (1) allow the Director discretion to shorten or lengthen the PISC timeframe during the

PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2) afford the

Director discretion to allow a Class VI well owner or operator to demonstrate, based on substantial

data during the permitting process, that an alternative PISC timeframe may be appropriate if it

ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial
data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21746

Comment: (C) SITE CLOSURE PERIOD 

EPA correctly states in its Preamble that defining the post-injection site care 

period is "difficult to define because it is based on site-specific 

considerations." (73 Fed. Reg. at 43519.) The three studies cited by EPA also 

concluded that "the actual time for CO2 plume stabiliziation . . . will be very 

site-specific, being influenced by geologic factors such as formation 

permeability, geochemistry, and the degree of capillary trapping." (Id.) 

However, the Proposed Rule establishes a default 50-year period (following the 

cessation of injection) during which the operator must conduct monitoring to 

demonstrate that "the carbon dioxide plume and pressure front have stabilized 

and the geologic sequestration project does not pose an endangerment to USDWs." 

(See § 146.93(b).) The designation of a 50-year time-period without regard to 

particular site characteristics is arbitrary and not supported by existing 

scientific studies or industry experience. Moreover, the 50-year timeframe does 

not provide any incremental benefit as compared with a performance standard to 

protecting USDWs; rather, it will be a significant deterrent to commercial 

investment in geologic sequestration projects. 

Response: EPA disagrees that the 50 year time frame is unsupported. In determining the postinjection site care-timeframe for the proposed regulation, EPA reviewed industry reports, existing

environmental programs, and initial GS research studies. EPA provided a synthesis of pertinent

results from GS modeling studies in the preamble to the proposed regulation. Further explanation of

this analysis was included in an EPA-prepared background document that is available in the federal

docket, titled "Computational Modeling of Underground Injection of Carbon Dioxide for

Determination of Area-of-Review and Potential Risk to Underground Sources of Drinking Water."

Based on review of these studies, modeling results indicate that the CO2 plume stabilization may

occur on the timeframe of 10-100 years after the cessation of injection. EPA believes that a 50-year

default post-injection site care timeframe is a reasonable midpoint for most GS projects and

available data, including data submitted by commenters, do not support a different default timeframe,

and has retained this in the final regulation. 

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).
EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21753

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: BP urges EPA to adopt the performance standard that EPA considered in its 

review. EPA considered three options: (1) fixed period; (2) performance 

standard; and (3) combination of fixed period and performance standard; EPA 

states it adopted the latter approach. (73 Fed. Reg. at 43519.) While the 

Proposed Rule allows a Director to reduce the 50-year minimum (§146.93(b)(2)), 

the practical effect will be the 50-year timeframe applies unless an operator is 

able to overcome the presumption built into the Proposed Rule that 50 years is 

adequate. Indeed, this is more prescriptive than the requirement for Class I 

hazardous wells, which provides that the timeframe for post-injection site care 

ends when the plume has stabilized and cannot endanger USDWs. (Id.; 40 CFR 

§146.71.) 

Response: EPA agrees that some owners or operators will be able to demonstrate, in less than 50

years, that the pressure front and plume no longer pose a risk of endangerment to USDWs. However,

based on studies, EPA believes that the 50 year default time frame is warranted based on additional

review of research studies and reports and evaluation of public comments. 

EPA believes that the best way to address all possibilities, while ensuring USDW protection from

endangerment, is to set a 50 year default post-injection site care timeframe, with flexibility to: (1)

allow the Director discretion to shorten or lengthen the PISC timeframe during the PISC period

based on site-specific data, pursuant to requirements at §146.93(b); or (2) afford the Director

discretion to allow a Class VI well owner or operator to demonstrate, based on substantial data

during the permitting process, that an alternative PISC timeframe may be appropriate if it ensures

non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,
and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24071

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

language; 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: §146.93 Post-injection site care and site closure. 

Proposed Rule: (1) The owner or operator shall continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site closure 

plan for at least 50 years following the cessation of injection. At the 

Director’s discretion, the monitoring will continue until the geologic 

sequestration project no longer poses an endangerment to USDWs. 

Schlumberger Suggested Revision: (1) The owner or operator shall continue to 

conduct monitoring as specified in the Director-approved post-injection site 

care and site closure plan, pursuant to the performance based criteria described 

in 146.93(3). 

Schlumberger Rationale: The 50 year default period is not based on any 

scientific or technical information and could be considered arbitrary and 

capricious. 

Proposed Rule: (2) If the owner or operator can demonstrate to the satisfaction 

of the Director before 50 years, based on monitoring and other site-specific 

data, that the geologic sequestration project no longer poses an endangerment to 

USDWs, the Director may approve an amendment to the post-injection site care and 

site closure plan to reduce the frequency of monitoring or may authorize site 

closure before the end of the 50-year period. 

Schlumberger Suggested Revision: (2) If the owner or operator can demonstrate to 

the satisfaction of the Director that the geologic sequestration project no 

longer poses an endangerment to USDWs, the Director may approve an amendment to 

the post- injection site care and site closure plan to reduce the frequency of 

monitoring or may authorize site closure. 

Schlumberger Rationale: - 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most

cases or is arbitrary and capricious. EPA proposed a default post-injection site care timeframe of 50

years based on a review of research studies, industry reports, and existing environmental programs.

This analysis was included in an EPA-prepared background document that is available in the federal

docket, titled "Computational Modeling of Underground Injection of Carbon Dioxide for

Determination of Area-of-Review and Potential Risk to Underground Sources of Drinking Water."

EPA assessed various default timeframes based on additional review of research studies and

evaluation of public comments. While numerous commenters suggested that EPA shorten the

monitoring timeframe, none of the commenters provided sufficient data or other evidence to warrant

a change in the proposed timeframe. While the 10- or 30-year timeframe suggested by some of these
commenters may be within the timeframe suggested in some studies, EPA believes that the potential

risks of endangering USDWs will likely not decline within these timeframes and available data,

including data submitted by commenters, do not support a different default timeframe. However,

EPA recognizes that alternative timeframes may be appropriate under limited, specific

circumstances.

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Ben Yamagata Letter ID: 0227

Commenter Organization: Coal Utilization Research Council Comment ID: 21790

Comment: Post-Injection Site Care 

EPA’s proposed 50-years default timeframe for Class VI wells post-injection site 

care (PISC) is not justifiable, and likely will raise long-term uncertainty 

about liability associated with a CO2 injection project. Furthermore, the hybrid 

default/performancebased standard permits the agency to lengthen this period, 

making it impossible for a CCS project developer to understand the timeframe of 

its regulatory obligation at project inception. This long-term regulatory 

uncertainty presents an insurmountable risk. There is documented data that the 

risk drops off considerably after ten years. [FN3] CURC endorses the Interstate 

Oil and Gas Compact Commission (IOGCC)’s recommendation for a 10year post 
closure site care period. [FN4] The IOGCC proposed rules draw from two decades 

of state regulatory and industry experience with compression transport, and 

injection of CO2 from enhanced oil recovery. 

[FN3: Sally M. Benson, "Monitoring Carbon Dioxide Sequestration in Deep 

Geological Formations for Inventory Verification and Carbon Credits" (2006). 

[FN4: The Interstate Oil and Gas Compact Commission Task Force on Carbon Capture 

and Geologic Storage, "Storage of Carbon Dioxide in Geologic Structures: A Legal 

and Regulatory Guide for States and Provinces" (2007) [hereinafter IOGCC Model 

Rules].] 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive. EPA

proposed a default post-injection site care timeframe of 50 years based on a review of research

studies, industry reports, and existing environmental programs. This analysis was included in an

EPA-prepared background document that is available in the federal docket, titled "Computational

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and

Potential Risk to Underground Sources of Drinking Water." EPA assessed various default

timeframes based on additional review of research studies and evaluation of public comments. While

numerous commenters suggested that EPA shorten the monitoring timeframe, none of the

commenters provided sufficient data or other evidence to warrant a change in the proposed

timeframe. While the 10- or 30-year timeframe suggested by some of these commenters may be

within the timeframe suggested in some studies, there are circumstances (e.g., little development of

mineral trapping of CO2) under which the potential risks of endangering USDWs will likely not

decline within these timeframes. EPA believes that a 50 year post-injection site care timeframe

represents a reasonable and protective monitoring period and available data do not support a

different timeframe. Furthermore, EPA believes that a 50-year default post-injection site care

timeframe, as required at §146.93(b)(1), is not overly burdensome, does not exaggerate the risks

associated with GS, is consistent with other environmental programs, and sufficiently protects

USDWs from endangerment.

To the comment expressing concern about financial responsibility, EPA recognizes that there are

challenges associated with assuring funding for activities that will occur far in the future. However,

the Agency believes that in order to protect USDWs from endangerment under the SDWA operators

must demonstrate under §146.85 that financial resources are available to plug the injection well and

provide post-injection site care at the point in time that the first CO2 is injected. EPA is developing

guidance on financial responsibility to assist owners or operators in evaluating the requirements of

§146.85 and to assist Directors in evaluating financial responsibility demonstrations. The guidance

describes the types of financial mechanisms that operators can use to meet the financial

responsibility requirements for GS wells and it will also include a section on how to estimate costs to

support accurate financial responsibility demonstrations. The guidance will be available at

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

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

EPA acknowledges the concerns of some commenters that there will be circumstances where it can

be demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the final GS regulation includes a provision that the

Director may, at his/her discretion, shorten the post-injection site care timeframe if the owner or
operator can demonstrate that the GS project does not pose a risk to USDWs, as specified in

§146.93(b)(2). Such a demonstration will be site-specific, and based on pressure monitoring and

USDW impacts.

Commenter Name: Neeraj Gupta Letter ID: 0229

Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21866

Comment: Page 123- 50 year Post Injection Period- We strongly encourage EPA to not 

include a recommendation for 50 years of monitoring. We are concerned that most 

directors will choose to apply this as a default value, even for shorter 

duration projects or at low risk sites. Instead a site-specific post injection 

monitoring plan with clearly defined performance criteria such as pressure 

reduction, plume stabilization, lack of leakage, or stable parameter values over 

a period of time, should be used. This approach will give EPA the flexibility 

to design site-specific requirement but will also provide a level of certainty 

to the operators in terms of performance expectations. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. The guidance describes

recommended approaches for how an owner or operator could plug injection and monitoring wells;

perform post-injection monitoring; demonstrate the appropriateness of an alternative post-injection

site care time frame; demonstrate non endangerment; and perform site closure activities.

Additionally, the guidance will assist Directors in evaluating proposed well plugging plans and postinjection site care and site closure plans under §146.92 and §146.93. This guidance will be available

at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.
Commenter Name: A. James Mayer Letter ID: 0230

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

Energy Security Initiative

Comment ID:

21874

Comment: 3. The proposed 50-year post-injection site care timeframe discriminates against 

smaller operators. The extraordinarily long-term obligation this provision 

creates will almost certainly prevent some small and middle-size companies from 

undertaking otherwise successful and beneficial CO2 injection projects because 

of the significant financial burden imposed. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances.

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment, regardless of the size of the project. EPA adds that as part of the rulemaking

process, the Agency has evaluated the impacts of the GS rule on small entities and determined that it

will not have a significant economic impact on a substantial number of small entities. See the
discussion of the Regulatory Flexibility Act in the preamble to the final GS rule.

Commenter Name: A. James Mayer Letter ID: 0230

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

Energy Security Initiative

Comment ID:

21889

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking

comment) (40 CFR 146.93) 

Comment: 6. EPA should provide for performance-based requirements for Closure and Post 

Closure Care. The duration of post-injection site care should be determined by 

specific conditions and characteristics of the site, and monitoring of the 

pressure to determine the point at which the injection zone pressure is such 

that USDWs cannot be impacted. 

Response: The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a

combination of a fixed timeframe and a performance standard approach. EPA believes that a default

PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this timeframe,

combined with a site-specific Director’s discretion to create an alternative PISC time frame, ensures

that USDWs are protected. The GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating the well plugging, postinjection site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance

will assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes how an owner or operator should

plug injection and monitoring wells, perform post-injection monitoring, demonstrate the

appropriateness of an alternative post-injection site care time frame, demonstrate non-endangerment,

and perform site closure activities.

Commenter Name: M. Granger Morgan Letter ID: 0233

Commenter Organization: Carnegie Mellon University on behalf of the CCS

Reg Project

Comment ID:

21911

Other EPA Comment Codes and Descriptions: 5280 2.8.2.4 USDW non-endangerment

demonstrations 

Comment: 20. Site closure: We support the general approach that EPA proposes to determine 

the length of the post-injection site care period (a performance standard, 

anchored by a suggested duration of several decades). However, we suggest three 

modifications: 1) The rule should require that the post-injection site care and 
site-closure plan specify thresholds for demonstrating that the GS project no 

longer poses an endangerment to USDWs; 2) The rule should provide mechanisms to 

coordinate information and allocate responsibility if site conditions during the 

post-injection site care period are altered by operations of another GS project 

in the basin; and, 3) The 50-year time period should not become a prescriptive 

default. There is not yet enough experience to set this as the suggested 

duration of the post-injection site care period. For now, a performance standard 

alone is preferable and creates the right incentives to protect USDWs. After 

experience has been gained from early projects, the rule could be amended to 

include a suggested duration. 

Response: EPA agrees that the rule should not specify the criteria for setting the monitoring

timeframe. Instead, EPA believes that such determinations are site-specific and should be described

in a project-specific post-injection site care and site closure plan. However, EPA disagrees that the

plan should specify thresholds for demonstrating that the GS project no longer poses a risk of

endangerment to USDWs, but agrees that this demonstration should be an important consideration.

EPA is developing guidances with recommended approaches for developing and implementing postinjection site care and site closure plans and guidance that describes recommended approaches for

how an owner or operator could plug injection and monitoring wells, perform post-injection

monitoring, demonstrate non endangerment, and perform site closure activities. The guidances will

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

EPA agrees with commenters that there will be circumstances where it can be demonstrated in less

than 50 years that the plume and pressure front no longer pose a risk of endangerment to USDWs.

For this reason, the final GS regulation includes a provision that the Director may, at his or her

discretion, shorten the post-injection site care timeframe if the owner or operator can demonstrate

that the GS project does not pose an endangerment to USDWs, as specified in §146.93(b)(2). Such a

demonstration will be site-specific, and based on pressure monitoring and USDW impacts. EPA

believes however, that to ensure USDW protection from endangerment, a default timeframe for postinjection site care is necessary. A 50-year post-injection site care timeframe represents a reasonable

and protective monitoring period based on a review of research studies, industry reports, and existing

environmental programs, and evaluation of public comments.

Commenter Name: Abbie Krebsbach Letter ID: 0235

Commenter Organization: Montana-Dakota Utilities Co. Comment ID: 23186

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial

responsibility requirements (40 CFR 146.85) 

Comment: Closure and Post Injection Site Care (PISC) 

Establishing a default time period for PISC, in particular a default time period 

as lengthy as 50 years as proposed in the rule, is unnecessary and undesirable, 

and the dual goals of protecting USDW and supporting the commercialization of 

CCS technology are far better served through a site-specific, performance-based 

approach. Montana-Dakota believes that the unique characteristics of CO2 do not 

justify imposition of such a lengthy default PISC period for GS projects. 

Appropriately sited projects should demonstrate the absence of endangerment to 

USDW in substantially less than 50 years. 
Further, imposing requirements on CO2 storage projects that are far beyond those 

currently in place even for injection of hazardous wastes is unnecessary and 

will only engender public misperceptions regarding the safety of such projects. 

There is potential for an obligation to provide financial assurance for 

activities running through 70 years into the future (according to EPA's 

assumption of a 20-year injection period), or more. Especially, given the 

ongoing credit crisis, an unjustifiably lengthy PISC period may make obtaining 

the necessary financial assurance impossible, stunting or stopping commercial 

development of CCS. 

Montana-Dakota urges EPA to implement a performance-based approach that 

considers the circumstances of a particular project, bounded by appropriate 

parameters for its application, and also encourages the EPA to establish clear 

parameters for such a performance-based approach, and in particular, a clear set 

of guidelines for demonstrating that the injectate has "stabilized", and for 

meeting the non-endangerment standard. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive. EPA

proposed a default post-injection site care timeframe of 50 years based on a review of research

studies, industry reports, and existing environmental programs. This analysis was included in an

EPA background document in the federal docket, "Computational Modeling of Underground

Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk to

Underground Sources of Drinking Water." While numerous commenters suggested that EPA shorten

the monitoring timeframe, none of the commenters provided sufficient data to warrant a change in

the proposed timeframe. While the 10- or 30-year timeframe suggested by some of these

commenters may be within the timeframe suggested in some studies, there are circumstances (e.g.,

little development of mineral trapping of CO2) under which the potential risks of endangering

USDWs will likely not decline within these timeframes. EPA believes that a 50-year default postinjection site care timeframe, as required at §146.93(b)(1), is not overly burdensome, does not

exaggerate the risks associated with GS, is consistent with other environmental programs, and

sufficiently protects USDWs from endangerment.

EPA acknowledges that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the final GS regulation allows the Director to shorten the post-injection site care timeframe if

the owner or operator can demonstrate that the GS project does not pose a risk to USDWs, as

specified in §146.93(b)(2). Such a demonstration will be site-specific, and based on pressure

monitoring and USDW impacts. EPA believes however, that to ensure USDW protection from

endangerment, a default timeframe for post-injection site care is necessary. 

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

EPA also recognizes the concerns associated with assuring financial responsibility for the long timeframes over which post-injection site care will be conducted. EPA is developing guidance on

financial responsibility to assist owners or operators in evaluating the requirements of §146.85 and to

assist Directors in evaluating financial responsibility demonstrations. The guidance describes the

types of financial mechanisms that operators may choose to use when evaluating the financial

responsibility requirements for GS wells and it will also include a section on how to estimate costs to
support accurate financial responsibility demonstrations. The guidance will be available at

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

EPA disagrees that the requirements for financial responsibility are overly stringent. The goal of

financial responsibility is to ensure that financial resources are available to prevent the endangerment

of USDWs from improper plugging, remediation, and management of wells in the event that the

owner or operator experiences financial difficulties throughout the life of the project. 

EPA believes that minimum financial responsibility requirements are necessary to prevent

endangerment of USDWs by holding well owners or operators accountable for the safe operation and

closure of the well and to avoid expense and risk to the public. See the final rule and preamble for

further discussion of EPA's final approach to financial responsibility. EPA adds that the purpose of

the GS rule is not to encourage the use of GS; rather, the purpose of the GS rule is to ensure that,

where GS is deployed, it is conducted in a manner that protects USDWs from endangerment.

Commenter Name: Robert E. Carter Jr. Letter ID: 0236

Commenter Organization: Indiana Department of Natural Resources (IDNR) Comment ID: 29222

Comment: States like Indiana with a proven track record of effectively managing similar 

programs have indeed demonstrated an ability to adapt to evolving technologies 

and we believe do possess the capability to effectively address long-term 

storage issues. In fact, as indicated earlier in our comments, many of the longterm issues associated with CCGS operations will be outside the purview of the 

UIC Program and will need to be addressed by states as they enact appropriate 

CCGS legislation. EPA should consider implementing rules which afford states 

with the greatest flexibility to select regulatory options that are best suited 

to their specific needs and conditions. Specific examples of requirements that 

may be too prescriptive include: 

7. Fixed 50-year post-injection time period. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive and

clarifies that the 50 year period is not fixed. For example, EPA acknowledges that there will be

circumstances where it can be demonstrated in less than 50 years that the plume and pressure front

no longer pose a risk of endangerment to USDWs. For this reason, the final GS regulation includes a

provision that the Director may, at his/her discretion, shorten the post-injection site care timeframe if

the owner or operator can demonstrate that the GS project does not pose a risk to USDWs, as

specified in §146.93(b)(2). Such a demonstration will be site-specific, and based on pressure

monitoring and USDW impacts. EPA believes however, that to ensure USDW protection from

endangerment, a default timeframe for post-injection site care is necessary. A 50 year post-injection

site care timeframe represents a reasonable and protective monitoring period based on a review of

research studies, industry reports, and existing environmental programs, and evaluation of public

comments.

Commenter Name: Philip Papadeas Letter ID: 0238

Commenter Organization: Sandia Technologies, LLC Comment ID: 23358

Comment: §146.93 (a)(4)(b)(1) 

Re:Monitoring for 50 years 

How is the operator going to monitor for 50 years, when their facility is 
closed, bankrupt, or remains insolvent, while other sites adjacent and in direct 

influence may remain active and operational? This time is not work-able, and 

should be consistent with EPA’s best analog, the 30-year post-closure rule from 

UIC Class I wells. Monitoring should continue only to the point when pressure 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive. EPA

proposed a default post-injection site care timeframe of 50 years based on a review of research

studies, industry reports, and existing environmental programs. This analysis was included in an

EPA-prepared background document that is available in the federal docket, titled "Computational

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and

Potential Risk to Underground Sources of Drinking Water." EPA assessed various default

timeframes based on additional review of research studies and evaluation of public comments. While

numerous commenters suggested that EPA shorten the monitoring timeframe, none of the

commenters provided sufficient data or other evidence to warrant a change in the proposed

timeframe. While the 10- or 30-year timeframe suggested by some of these commenters may be

within the timeframe suggested in some studies, there are circumstances (e.g., little development of

mineral trapping of CO2) under which the potential risks of endangering USDWs will likely not

decline within these timeframes. EPA believes that a 50 year post-injection site care timeframe

represents a reasonable and protective monitoring period and available data do not support a

different timeframe. Furthermore, EPA believes that a 50-year default post-injection site care

timeframe, as required at §146.93(b)(1), is not overly burdensome, does not exaggerate the risks

associated with GS, is consistent with other environmental programs, and sufficiently protects

USDWs from endangerment.

EPA acknowledges the concerns of some commenters that there will be circumstances where it can

be demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the final GS regulation includes a provision that the

Director may, at his/her discretion, shorten the post-injection site care timeframe if the owner or

operator can demonstrate that the GS project does not pose a risk to USDWs, as specified in

§146.93(b)(2). Such a demonstration will be site-specific, and based on pressure monitoring and

USDW impacts. 

To the comment expressing concern about financial responsibility, EPA recognizes that there are

challenges associated with assuring funding for activities that will occur far in the future. However,

the Agency believes that in order to protect USDWs from endangerment under the SDWA operators

must demonstrate under §146.85 that financial resources are available to plug the injection well and

provide post-injection site care at the point in time that the first CO2 is injected.. EPA is developing

guidance on financial responsibility to assist owners or operators in evaluating the requirements of

§146.85 and to assist Directors in evaluating financial responsibility demonstrations. The guidance

describes the types of financial mechanisms that operators may choose to use when evaluating the

financial responsibility requirements for GS wells and it will also include a section on how to

estimate costs to support accurate financial responsibility demonstrations.

http://www.epa.gov/safewater/uic/wells_sequestration.htm. 

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

Commenter Name: Philip Papadeas Letter ID: 0238
Commenter Organization: Sandia Technologies, LLC Comment ID: 23360

Comment: 50-year monitoring is severe, and has no basis in other EPA operational 

considerations. No site continuity would be present, well operational records 

lost, and personnel retired with expertise dissipated. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive and

clarifies that the record supports EPA’s final approach. EPA proposed a default post-injection site

care timeframe of 50 years based on a review of research studies, industry reports, and existing

environmental programs. This analysis was included in an EPA-prepared background document that

is available in the federal docket, titled "Computational Modeling of Underground Injection of

Carbon Dioxide for Determination of Area-of-Review and Potential Risk to Underground Sources of

Drinking Water." EPA assessed various default timeframes based on additional review of research

studies and evaluation of public comments. While numerous commenters suggested that EPA

shorten the monitoring timeframe, none of the commenters provided sufficient data or other evidence

to warrant a change in the proposed timeframe. While the 10- or 30-year timeframe suggested by

some of these commenters may be within the timeframe suggested in some studies, there are

circumstances (e.g., little development of mineral trapping of CO2) under which the potential risks

of endangering USDWs will likely not decline within these timeframes. EPA believes that a 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period and

available data do not support a different timeframe. Furthermore, EPA believes that a 50-year default

post-injection site care timeframe, as required at §146.93(b)(1), is not overly burdensome, does not

exaggerate the risks associated with GS, is consistent with other environmental programs, and

sufficiently protects USDWs from endangerment.

EPA acknowledges that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the final GS regulation includes a provision that the Director may, at his/her discretion,

shorten the post-injection site care timeframe if the owner or operator can demonstrate that the GS

project does not pose a risk to USDWs, as specified in §146.93(b)(2). Such a demonstration will be

site-specific, and based on pressure monitoring and USDW impacts. 

EPA disagrees that a 50 year post-injection site care period would contribute to lack of site

continuity or loss of operational records or staff expertise. EPA understands that changes in staff or

ownership occur associated with all injection operations that operate over timeframes of several years

or decades, and believes that owners and operators granted UIC permits have a responsibility to

maintain continuity in expertise and data associated with the project. 

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23261

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: 38. EPA is proposing using a combination of fixed timeframe and a performance 

standard as described above. EPA is tentatively proposing a post-injection site 

care (monitoring) period of 50 years with Director’s discretion to change that 

period to lengthen or shorten the 50-year period if appropriate. EPA requests 

comment on the proposed use of a tentative 50-year fixed timeframe that could be 

modified at the Director’s discretion based on monitoring and modeling data. EPA 

Notice 43519. 
A performance-based time period is appropriate rather than a fixed timeframe. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23262

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: 39. EPA is requesting comments on the proposed requirements for well plugging, 

post-injection site care, and site closure, including the proposed requirements 

for the post-injection time period. EPA Notice 43520. 

A performance-based time period is appropriate rather than a fixed timeframe. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.
EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23306

Comment: 146.93(b) A performance-based time period is appropriate rather than a fixed 

timeframe. Establishing an arbitrary and long time frame will inhibit operators 

from entering into this activity. 

Response: EPA acknowledges that there will be circumstances where it can be demonstrated in less

than 50 years that the plume and pressure front no longer pose a risk of endangerment to USDWs.

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Kevin Wanttaja Letter ID: 0248

Commenter Organization: Western Energy Supply and Transmission

Associates

Comment ID:

22243

Other EPA Comment Codes and Descriptions: 5430 2.9.1 Comments on proposed financial

responsibility requirements (40 CFR 146.85) 

Comment: – WEST urges EPA to avoid utilizing risk management approaches that discourage 

CCS development. WEST strongly believes that regulatory certainty is crucial, 

if meaningful investment is going to flow to CCS technologies and deployment. 

Certainty needs to be brought to long-term obligations, liabilities and risks 

associated with GS projects. To assist in this regard, EPA should set a limit 
of 50 years in the future for liabilities to GS project owners and operators. 

Extending this limit beyond 50 years may severely limit financial investments in 

CCS projects. Post injection monitoring and financial assurance requirements 

are important, but need to be tailored to comport with the potential risks, 

which decrease significantly after injection is complete. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. However, EPA acknowledges that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA recognizes that there are challenges associated with ensuring funding for activities that will

occur far in the future. However, the Agency believes that operators must demonstrate that financial

resources are available to plug the injection well and provide post-injection care at the point in time

that the first CO2 is injected. EPA also recognizes the concerns associated with ensuring financial

responsibility for the long time frames over which post-injection site care will be conducted. EPA is

developing guidance on financial responsibility to assist owners or operators in evaluating the

requirements of §146.85 and to assist Directors in evaluating financial responsibility demonstrations.

The guidance describes the types of financial mechanisms that operators may choose to use when

evaluating the financial responsibility requirements for GS wells and it will also include a section on

how to estimate costs to support accurate financial responsibility demonstrations. The guidance will

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

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

EPA disagrees that the requirements for financial responsibility are overly stringent. The goal of

financial responsibility for purposes of this rule is to ensure that financial resources are available to

prevent the endangerment of USDWs from improper plugging, remediation, and management of

wells in the event that the owner or operator experiences financial difficulties throughout the life of

the project. 

EPA expects the cost of meeting the financial responsibility requirements to be proportionate to the

expected costs of each GS activity. The minimum financial responsibility requirements provided are

necessary to prevent endangerment of USDWs by holding well owners or operators accountable for

the safe operation and closure of the well while avoiding expense and risk to the public. See the final
rule and preamble for further discussion of EPA's final approach to financial responsibility. EPA

adds that the purpose of the GS rule is not to encourage the use of GS; rather, the purpose of the GS

rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs from

endangerment.

Commenter Name: James T. Sims Letter ID: 0249

Commenter Organization: Western Business Roundtable Comment ID: 22264

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

Long-Term Care Requirements 

Comment: 5. Make Risk Management Approaches Reasonable - We strongly urge EPA to avoid 

utilizing risk management approaches that discourage CCS deployment. Regulatory 

certainty is absolutely crucial, if meaningful investment is going to flow to 

CCS technologies and implementation. 

EPA can be helpful in that regard by bringing certainty to the long-term 

obligations and risks associated with geologic sequestration projects. For 

example, EPA should refrain from requiring financial assurance for potential 

liabilities more than 50 years in the future. Extending those requirements any 

further may deter and even prevent investment in CCS projects. Likewise, postinjection monitoring and financial assurance requirements are important, but 

need to be tailored to comport with the potential risks, which decrease 

substantially after injection is complete. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA recognizes that there are challenges associated with assuring funding for

activities that will occur far in the future. However, the Agency believes that operators must

demonstrate that financial resources are available to plug the injection well and provide postinjection care at the point in time that the first CO2 is injected. 

EPA disagrees that the requirements for financial responsibility are overly stringent. The goal of

financial responsibility is to ensure that financial resources are available to prevent the endangerment

of USDWs from improper plugging, remediation, and management of wells in the event that the

owner or operator experiences financial difficulties throughout the life of the project. 

EPA believes that minimum financial responsibility requirements are necessary to hold well owners

or operators accountable for the safe operation and through closure of the well and avoid expense

and risk to the public. EPA adds that the purpose of the GS rule is not to encourage the use of GS;

rather, the purpose of the GS rule is to ensure that, where GS is deployed, it is conducted in a

manner that protects USDWs from endangerment. See the final rule and preamble for further

discussion of EPA's final approach to financial responsibility.

Under SDWA authority, owners or operators of injection wells must ensure protection of USDWs

from endangerment and are subject to liability for enforcement under the Act. The final rule requires

that an owner or operator must conduct post-injection site care that is consistent with the approved

PISC plan or for the duration of the alternative timeframe approved by the Director pursuant to

requirements in §146.93(c), until a demonstration can be made to the satisfaction of the Director that

the plume and pressure front no longer pose a risk of endangerment to USDWs. For additional

information about the PISC and site closure requirements, see the preamble to the final GS rule. 
EPA also recognizes the concerns associated with assuring financial responsibility for the long timeframes over which post-injection site care will be conducted. EPA is developing guidance on

financial responsibility to assist owners or operators in evaluating the requirements of §146.85 and to

assist Directors in evaluating financial responsibility demonstrations. The guidance describes the

types of financial mechanisms that operators may choose to use when evaluating the financial

responsibility requirements for GS wells, and it will also include a section on how to estimate costs

to support accurate financial responsibility demonstrations. The guidance will be available at

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

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. See the final rule and preamble for further discussion of EPA's final approach to

financial responsibility. 

EPA acknowledges that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Mike Nasi Letter ID: 0254

Commenter Organization: Clean Coal Technology Foundation of Texas Comment ID: 22366

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

Comment: 3. Post-Closure Care 

The proposal includes a default monitoring period of 50 years after closure of 

an injection well, but fails to provide the necessary justification for setting 

the default monitoring period for this time period. CCTF does not believe that 

there is a sufficient connection between this time period and the relative risks 

associated with geologic sequestration of CO2. Consistent with our previous 

comments, we urge EPA to incorporate performance-based standards, so as to lead 

to site specific approaches. In this context, we believe that post-injection 

site care should be based on site and project specific characteristics rather 

than a prescribed and lengthy time period, especially a default time period that 

does not seem to be supported by relevant literature. 

Although provision is made in the proposed rule for a potential shortening of 
the post-closure monitoring period, the reality under the existing program is 

that permitting authorities almost without exception default to the maximum 

statutory monitoring period. Because there is no reason to believe that 

permitting authorities will take a different approach here, the practical impact 

of including the 50 year period in the rule will be that operators will be 

required to monitor for that time period with only rare exceptions. There is 

simply no technical justification for such an extended monitoring period, 

especially given the decades of experience showing the 30 year monitoring period 

to be fully protective of human health and the environment. 

Response: EPA disagrees with this comment. In determining the post-injection site care timeframe

for the proposed regulation, EPA reviewed industry reports, existing environmental programs, and

initial GS research studies. EPA provided a synthesis of pertinent results from GS modeling studies

in the preamble to the proposed regulation. Further explanation of this analysis was included in an

EPA-prepared background document that is available in the federal docket, titled "Computational

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and

Potential Risk to Underground Sources of Drinking Water." Based on review of these studies,

modeling results indicate that the CO2 plume stabilization may occur on the timeframe of 10-100

years after the cessation of injection. EPA believes that a 50-year default post-injection site care

timeframe is a reasonable midpoint, and has retained this in the final regulation. 

EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most Class VI

wells. While the 10- or 30-year timeframe suggested by some of these commenters may be within

the timeframe suggested in some studies, EPA believes that the potential risks of endangering

USDWs will likely not decline within these timeframes and available data, including data submitted

by commenters, do not support a different default timeframe. However, EPA recognizes that

alternative timeframes may be appropriate under limited, specific circumstances. 

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.
Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24821

Comment: EPA Rule Issue: 38. EPA is proposing using a combination of fixed timeframe and 

a performance standard as described above. EPA is tentatively proposing a postinjection site care (monitoring) period of 50 years with Director’s discretion 

to change that period to lengthen or shorten the 50 year period if appropriate. 

EPA requests comment on the proposed use of a tentative 50 year fixed timeframe 

that could be modified at the Director’s discretion based on monitoring and 

modeling data. EPA Notice 43519. 

GWPC CO2 Committee Response: It is inappropriate to utilize a fixed period. A 

demonstration of non endangerment is an appropriate means of deciding when 

monitoring is no longer needed. The Committee recommends using a combination of 

the non-endangerment standard with specific performance standards as follows: 

Prior to authorization for site closure, the owner or operator must demonstrate 

to the Director, based on monitoring, other site-specific data, and modeling 

that is reasonably consistent with site performance, that no additional 

monitoring is needed to assure that the geologic sequestration project does not 

and is not expected to pose an endangerment to USDWs. The Director shall approve 

closure if the owner or operator demonstrates, based on the current 

understanding of the site, including monitoring data and/or modeling, all of the 

following: (i) the estimated magnitude and extent of the project footprint (CO2 

plume and the area of elevated pressure) ; (ii) the estimated location of the 

detectable CO2 plume; (iii) that there is no significant leakage of either CO2 

or displaced formation fluids that is endangering USDWs; (iv) that the injected 

or displaced fluids are not expected to migrate in the future in a manner that 

encounters a potential leakage pathway into a USDW; (v) that the injection wells 

at the site completed into or through the injection zone or confining zone are 

plugged and abandoned in accordance with these requirements; and (vi) any 

remaining project monitoring wells at the site are being managed by a person and 

in a manner acceptable to the Director. 

Rationale: The fixed timeframe is not adequately supported by scientific and 

technical evidence and represents an unnecessary departure from the use of 

performance standards, which EPA has recognized as the preferred approach in 

most other situations. The use of "stabilization" as a performance standard is 

not advised because of the difficulties of dealing with background 

movement within the injection zone. The most important demonstration is 

containment, not just movement. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).
EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24945

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

language; 5280 2.8.2.4 USDW non-endangerment demonstrations 

Comment: Rule Provision: 146.93(b) 

EPA Proposal: (b) The owner or operator shall monitor the site following the 

cessation of injection to show the position of the carbon dioxide plume and 

pressure front and demonstrate that USDWs are not being endangered. 

(1) The owner or operator shall continue to conduct monitoring as specified in 

the Director-approved post-injection site care and site closure plan for at 

least 50 years following the cessation of injection. At the Director’s 

discretion, the monitoring will continue until the geologic sequestration 

project no longer poses an endangerment to USDWs. 

GWPC Recommendations: (b) The owner or operator shall monitor the site following 

the cessation of injection. 

(1) The owner or operator shall continue to conduct monitoring as specified in 

the Director-approved post-injection site care and site closure plan until 

closure is authorized pursuant to 146.93(b)(3). 

Rationale: Eliminate the 50 year requirement. 

There is no justification for extending completed projects for the presumptive 

50 years, and it will be difficult to accept much shorter demonstration periods 

with the 50 year presumption in the regulations. Default 50-year period defeats 

incentives for best site identification and best MMV 

Need for site-specific considerations and use of data 

Need achievable and definable standard 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this
reason, the final GS regulation includes a provision that the Director may, at his or her discretion,

shorten the post-injection site care timeframe if the owner or operator can demonstrate that the GS

project does not pose an endangerment to USDWs, as specified in §146.93(b)(2). Such a

demonstration will be site-specific, and based on pressure monitoring and USDW impacts.

Alternatively, the final rule at §146.93(c), also allows the Director to approve an alternative postinjection site care timeframe where an owner or operator can demonstrate during the permitting

process that an alternative post-injection site care timeframe, other than the 50 year default, is

appropriate and ensures non-endangerment of USDWs. The demonstration must be based on sitespecific information, including the results of site-specific computational modeling; the predicted

timeframe for pressure decline; the predicted rate of carbon dioxide plume migration; site-specific

chemical processes that will result in carbon dioxide trapping; the predicted rate of carbon dioxide

trapping; characterization of the confining zone(s); laboratory analyses or studies to verify the

information on trapping; the presence of potential conduits for fluid movement and the quality of

abandoned well plugs within the AoR; the distance between the injection zone and the USDWs

above and/or below the injection zone; and any additional site-specific factors determined by the

Director. The demonstration must meet the criteria at §146.93(c)(2) for ensuring the quality and

accuracy of the data and models on which the demonstration is based. This demonstration would be

submitted as part of the permit application, per §146.82(a)(18), in addition to the PISC and site

closure plan required at §146.82(a)(17). 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24946

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

language; 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b) 

EPA Proposal: (2) If the owner or operator can demonstrate to the satisfaction 

of the Director before 50 years, based on monitoring and other site-specific 

data, that the geologic sequestration project no longer poses an endangerment to 

USDWs, the Director may approve an amendment to the post-injection site care and 

site closure plan to reduce the frequency of monitoring or may authorize site 

closure before the end of the 50-year period. 

GWPC Recommendations: (2) The owner or operator can request and demonstrate to 

the satisfaction of the Director that the post-injection site care and site 
closure plan should be revised to reduce the frequency of monitoring. 

Rationale: See above regarding elimination of 50-year presumptive time period. 

Response: As described above, EPA disagrees that a post-injection site care timeframe of 50 years is

excessive for most Class VI wells. However, EPA agrees that there will be circumstances where it

can be demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24948

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

language; 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: EPA Proposal: (4) If such a demonstration cannot be made (i.e., if the carbon 

dioxide plume and pressure front have not stabilized) after the 50-year period, 

the owner or operator must submit to the Director a plan to continue postinjection site care. 

GWPC Recommendations: Delete 

Rationale: No longer necessary if 50 year time period is removed. 

Response: As described above, EPA believes that, to ensure USDW protection from endangerment,

a default timeframe for post-injection site care is necessary in most cases. A 50 year post-injection

site care timeframe represents a reasonable and protective monitoring period for most GS sites based

on a review of research studies, industry reports, and existing environmental programs, and

evaluation of public comments.

EPA believes that a 50-year default post-injection site care timeframe, as required at §146.93(b)(1),

is not overly burdensome, does not exaggerate the risks associated with GS, is consistent with other

environmental programs, and sufficiently protects USDWs from endangerment.

Commenter Name: Claire Olson Letter ID: 0260

Commenter Organization: Basin Electric Power Cooperative Comment ID: 22400
Comment: "8. Proposed Well Plugging, Post-Injection Site Care, and Site Closure Requirements" 

EPA is proposing to impose a 50-year post-injection site care (PISC) standard as 

the default timeframe with the UIC State Director having the discretion to 

adjust this time period. Setting the tentative 50-year fixed timeframe that 

could be modified at the State Director's discretion based on monitoring and 

modeling data does provide some flexibility. However, Basin Electric urges the 

EPA to set the timeframe rules in an order that minimizes early risk projects 

and rewards early movers. The recently passed Emergency Economic Stabilization 

bill that has become law (HR. 1428) provides in Division B sec. 115 tax 

incentives for carbon dioxide sequestration either in secure geological storage 

or used as a tertiary injectant in a qualified enhanced oil or natural gas 

recovery project. It is imperative that the monitoring rules do not inhibit the 

ability of the Secretary of Treasury to give the credit to the appropriate 

taxpayer who has captured the carbon dioxide. Requiring 50 years of monitoring 

could preclude early commercial activity. The operator should be responsible for 

the fixed timeframe of 10 years; however, provisions must be enacted for an 

eventual transfer of liability and long-term monitoring to the government, most 

likely the state. The Interstate Oil and Gas Commission 10-year recommendation 

was reviewed and rejected. However, since the State Director could modify the 

timeframe by extending the monitoring time based on monitoring and modeling 

data, Basin Electric suggests lowering the fixed timeframe to 10 years. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances. 

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,
and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA adds that the comment related to the Emergency Economic Stabilization bill is outside the

scope of this rulemaking. EPA adds that the purpose of the GS rule is not to incentivize the use of

GS; rather, the purpose of the GS rule is to ensure that, where GS is deployed, it is conducted in a

manner that protects USDWs from endangerment.

Letter ID: 0263

Commenter Organization: Interstate Oil & Gas Compact Commission Comment ID: 22825

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

00. EPA requests comment on the proposed use of a tentative 50-year fixed timeframe 

that could be modified at the Director's discretion based on monitoring and 

modeling data. 

IOGCC Response: Given that current injection and reservoir behavior data 

demonstrates a decreasing risk of leakage after injection ceases, the IOGCC has 

concluded that a 50 year fixed timeframe is both unnecessary and too long. What 

is absolutely critical here is that the Director has discretion to increase or 

decrease the period based on the specifics of a particular project. In the view 

of the IOGCC, it would be better to prescribe a shorter period with discretion to 

go longer, rather than vice versa, as such would better facilitate project 

planning. 

III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

PP. EPA is requesting comments on the proposed requirements for well plugging, 

post-injection site care, and site closure, including the proposed requirements 

for the post-injection time period. 

IOGCC Response: Given documented evidence to date that there is a decreasing risk 

of leakage after injection ceases, The IOGCC has concluded that a 50 year fixed 

timeframe is both unnecessary and too long. What is absolutely critical here is 

that there be Director discretion to increase or decrease the period based on 

the specifics of a particular project. In the view of the IOGCC, it would be 

better to prescribe a shorter period with discretion to go longer, rather than 

vice versa, as such would better facilitate project planning. 
III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

QQ. In addition, EPA seeks comment on whether the Director should be allowed to 

shorten the timeframe based on performance information, and whether EPA should 

require a shorter or longer post-injection period if data suggests the time frame 

should be adjusted. 

IOGCC Response: Given documented evidence to date that there is a decreasing risk 

of leakage after injection ceases, The IOGCC has concluded that a 50 year fixed 

timeframe is both unnecessary and too long. What is absolutely critical here is 

that there be Director discretion to increase or decrease the period based on 

the specifics of a particular project. In the view of the IOGCC, it would be 

better to prescribe a shorter period with discretion to go longer, rather than 

vice versa, as such would better facilitate project planning. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive or

unnecessary for most GS sites. EPA proposed a default post-injection site care timeframe of 50 years

based on a review of research studies, industry reports, and existing environmental programs. This

analysis was included in an EPA-prepared background document that is available in the federal

docket, titled "Computational Modeling of Underground Injection of Carbon Dioxide for

Determination of Area-of-Review and Potential Risk to Underground Sources of Drinking Water."

EPA assessed various default timeframes based on additional review of research studies and

evaluation of public comments. While numerous commenters suggested that EPA shorten the

monitoring timeframe, none of the commenters provided sufficient data or other evidence to warrant

a change in the proposed timeframe. While the 10- or 30-year timeframe suggested by some of these

commenters may be within the timeframe suggested in some studies, EPA believes that the potential

risks of endangering USDWs will likely not decline within these timeframes and available data,

including data submitted by commenters, do not support a different default timeframe. However,

EPA recognizes that alternative timeframes may be appropriate under limited, specific

circumstances. 

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on
a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

Commenter Name: Steven Chester Letter ID: 0264

Commenter Organization: Michigan Department of Environmental Quality

(MDEQ)

Comment ID:

22845

Comment: EPA (III . A. 8.) proposes a 50-year post-closure monitoring period . 

- Staff believes that the 50-year time period is probably too long as 

there is no certainty that the entity that originated the sequestration project 

will be in existence for such a long period. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

GS sites. However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

To the comment that the entity that originated the project may not be in existence for such a long

period, the Agency believes that in order to protect USDWs from endangerment under the SDWA,

operators must demonstrate under §146.85 that financial resources are available to plug the injection

well and provide post-injection site care at the point in time that the first CO2 is injected. EPA

understands that changes in staff or ownership occur associated with all injection operations that

operate over timeframes of several years or decades, and believes that owners and operators granted

UIC permits have a responsibility to maintain continuity in expertise and data associated with the

project.

Commenter Name: Michael Moore Letter ID: 0265

Commenter Organization: North American Carbon Capture & Storage

Association (NACCSA)

Comment ID:

22867
Comment: 5. Closure and Post-Injection Site Care 

An additional key area of concern for NACCSA is the proposed rule's provision 

imposing a 50 year default time period following cessation of injection 

activities to serve as the closure and post-injection site care ("PISC") period, 

throughout which monitoring activities and corresponding financial assurance 

requirements would continue. Under the proposal, the program director would have 

discretion to adjust the time period upward or downward, with the effect that 

the PISC period would continue "until the geologic sequestration project no longer 

poses an endangerment to USDWs." 

NACCSA understands that a fair amount of certainty may be achieved through setting 

some default period of time for the PISC. Establishing such a lengthy default 

time period also places unnecessary burdens on owners and operators who can 

clearly establish that no threat to USDWs will be posed within a shorter time 

frame than whatever default may be established. 

Response: EPA agrees that some owners or operators will be able to demonstrate, in less than 50

years, that the pressure front and plume no longer pose a risk of endangerment to USDWs. However,

based on studies, EPA believes that the 50 year default time frame is warranted in most cases based

on additional review of research studies and reports and evaluation of public comments. 

EPA believes that the best way to address all possibilities, while ensuring USDW protection from

endangerment, is to set a 50 year default post-injection site care timeframe, with flexibility to: (1)

allow the Director discretion to shorten or lengthen the PISC timeframe during the PISC period

based on site-specific data, pursuant to requirements at §146.93(b); or (2) afford the Director

discretion to allow a Class VI well owner or operator to demonstrate, based on substantial data

during the permitting process, that an alternative PISC timeframe may be appropriate if it ensures

non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Michael Moore Letter ID: 0265

Commenter Organization: North American Carbon Capture & Storage

Association (NACCSA)

Comment ID:

22868

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards); 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: NACCSA urges the Agency to adopt a performance-based approach more in keeping 

with the actual risks posed by CCS projects. NACCSA believes that the site specific 

nature of CO2 storage projects will require each project to be judged on its own 

merit. If a project can show, at any time after the cessation of injection, that 

there is sufficiently small risk of endangerment to USDWs, monitoring should no 

longer be required. Given that under the proposed rule, the program director would 
retain discretion to lengthen or shorten the PISC period as necessary to protect 

USDWs, a performance based approach is in keeping with the spirit of the draft 

rule. Furthermore, performance based approach is more in keeping with the 

realty of potential risks associated with CO2 storage would minimize 

disincentivization of CCS projects while providing an equivalent degree 

of protection for USDWs. NACCSA believes that the performance-based approach, 

currently proposed by EPA as an element of the rule, would be beneficial to 

project operators and investors and for the protection of USDWs. The final rule 

should include specific and appropriate circumstances that the program director 

will consider in exercising discretion in this regard, so that project operators 

and investors have a clear idea of the bar they will be required to meet in order 

to close out the PISC period. 

Response: As described above, EPA agrees that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: David Hawkins Letter ID: 0272

Commenter Organization: Natural Resources Defense Council Comment ID: 24079

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

language 

Comment: D. Closure 

[FR p. 43540, §146.93(b)] EPA has proposed an arrangement whereby the operator 

continues to monitor the site for a minimum of 50 years after the cessation of 

injection, unless the operator can demonstrate to the satisfaction of the 

Director that the project no longer poses an endangerment to USDWs and that the 

CO2 plume and pressure front have stabilized. 

While 50 years is not a number that will apply in all cases and projects, we do 

believe that it is appropriate as a default at today’s level of our 

understanding and operational experience with GS. The option that operators have 

under the current proposal to obtain approval for a lower number, based on 

actual project performance, should be sufficient to deal with situations where 

50 years can be demonstrated to be unnecessarily long. Along the same lines, 
there might be situations where 50 years would not suffice, and where the 

Director should require a longer period, as per the current proposal. In 

assessing non-endangerment to USDWs and plume/pressure front stabilization, we 

believe that the EPA should be far more specific in its requirements. We offer 

the following language as a suggested revision to §146.93(b): 

"(b) The owner or operator shall monitor the site following the cessation of 

injection. 

(1) The owner or operator shall continue to conduct monitoring as specified in 

the Director-approved post-injection site care and site closure plan for at 

least 50 years following the cessation of injection or until closure is 

authorized. 

(2)If the owner or operator can demonstrate to the satisfaction of the Director 

before 50 years, based on/pursuant to the criteria in (b), that the geologic 

sequestration project does not and is not expected to pose an endangerment to 

USDWs or result in releases to the atmosphere, the Director may approve an 

amendment to the post-injection site care and site closure plan to reduce the 

frequency of monitoring or may authorize site closure before the end of the 50- 

year period. 

(3) Prior to authorization for site closure, the owner or operator must 

demonstrate to the Director, based on monitoring, other site-specific data, and 

modeling that is consistent with site performance, that no additional monitoring 

is needed to assure that the geologic sequestration project does not and is not 

expected to pose an endangerment to USDWs or any release to the atmosphere. The 

owner or operator must demonstrate, based on the current understanding of the 

site, including monitoring data and modeling, all of the following: (i) the 

magnitude and extent of the project footprint (CO2 plume and the area of 

elevated pressure); (ii) the location of the detectable CO2 plume; (iii) that 

there is no significant leakage of either CO2 or displaced formation fluids that 

is endangering USDWs or creating a potential release to the atmosphere; (iv) 

that the injected or displaced fluids are not expected to migrate in the future 

in a manner that encounters a potential leakage pathway into a USDW or to the 

atmosphere; (v) that the injection wells at the site completed into or through 

the injection zone or confining zone are plugged and abandoned in accordance 

with these requirements; and (vi) any remaining project monitoring wells at the 

site are being managed by a person and in a manner acceptable to the Director. 

(4) If such a demonstration cannot be made after the 50-year period, the owner 

or operator must submit to the Director a plan to continue post-injection site 

care." 

Response: EPA agrees that a 50 year post-injection site care timeframe represents a reasonable and

protective post-injection site monitoring period for most projects and available data, including data

submitted by commenters, do not support a different default timeframe. EPA bases this on a review

of research studies, industry reports, and existing environmental programs, and evaluation of public

comments.
However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

In response to comments to be more specific, EPA believes §146.93 is sufficiently specific for the

purposes of protecting USDWs. Furthermore, the commenter’s proposed language regarding released

CO2 emissions into the air are outside the scope of this rulemaking and EPA’s authority under the

SDWA.

Commenter Name: Mark Vickery Letter ID: 0280

Commenter Organization: Texas Commission on Environmental Quality Comment ID: 24104

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions; 5280

2.8.2.4 USDW non-endangerment demonstrations 

Comment: (e) Concern exists regarding the need for (i) a standard (in concentration or 

saturation) for defining the edge of a CO2 plume, (ii) clear definition of the 

term "stabilization" as applied to fate and transport of an injected CO2 plume 

and pressure front, and (iii) a clarified specification of the performance 

standard for the necessary demonstration to enable termination of the iterative 

process of monitoring/modeling and related corrective action. If "stabilization" 

means absence of plume movement or pressure change, it is our understanding from 

CO2-GS research efforts that indefinitely long periods of monitoring, modeling, 

and corrective action may be required in contrast to the default period of fifty 

years cited in the proposed rules and preamble. A more appropriate basis for 

demonstrations of protection of underground sources of drinking water (USDW) 

would be keyed to the presence of induced pressure conditions in the injection 

zone, spatially and temporally. When and where such pressure conditions are 

insufficient to cause endangerment of a USDW through leakage pathways such as 

improperly constructed or plugged wells or transmissible faults, the required 

USDW protection should be considered to be present. Accordingly, if the 

termination of monitoring, modeling, and corrective action is ultimately 
dependent on making the subject demonstration, it is recommended that the "fifty 

year" specification be deleted from the rule. This would conform the 

requirements for post-injection site care for Class VI wells more closely to the 

post-closure care specifications and concepts existing for Class I wells. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring

timeframe. Instead, EPA believes that such determinations are site-specific and should be described

in a project specific post-injection site care and site closure plan. EPA also believes that periodic

reviews and updates, where necessary, to the plan are important to ensuring that the site continues to

be managed effectively and to determine whether shortening the monitoring timeframe is

appropriate. 

EPA acknowledges that many site-specific factors will influence the determination of when the CO2

plume and pressure front no longer pose a risk of endangerment to USDWs. It is for this reason that

EPA believes that individual UIC Directors, in consultation with operators, will be in the best

position to determine whether additional post-injection site care is needed. EPA expects this decision

to be made based on relevant site data and in consultation with all potentially impacted parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that

a complete cessation of plume movement is not required, only a demonstration that the plume and

pressure front no longer pose a risk of endangerment to USDWs. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist

Directors in evaluating proposed well plugging plans and post-injection site care and site closure

plans under 146.92 and 146.93. The guidance describes recommended approaches for how an owner

or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Mark Vickery Letter ID: 0280

Commenter Organization: Texas Commission on Environmental Quality Comment ID: 24110

Other EPA Comment Codes and Descriptions: 5280 2.8.2.4 USDW non-endangerment

demonstrations 

Comment: (f) TCEQ agrees with EPA's approach that financial assurance for post-injection 

site care may be required for a period less than or greater than fifty years as 

proposed in 146.93, depending on a site specific demonstration to the Director. 

However, consistent with TCEQ's comments under Principal Concern 1, TCEQ also 

encourages EPA to delete the fifty-year threshold requirement in consideration 

of EPA's indication that the duration of financial assurance should ultimately 

be keyed to whatever site-specific time is necessary to meet the post-injection 

site care performance standard of demonstration of non-endangerment ofUSDWs. 

Response: EPA agrees that financial responsibility must be maintained throughout the post-injection

site care timeframe, regardless of its ultimate length. The GS rule requires this, at 146.85. 

EPA also agrees that there will be circumstances where it can be demonstrated in less than 50 years

that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this reason,
the GS rule offers owners or operators flexibility regarding the duration of the PISC timeframe by:

(1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the postinjection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the

permitting process based on substantial data, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Greg Shubel Letter ID: 0284

Commenter Organization: Inter-Tribal Council of Michigan, Inc Comment ID: 25303

Comment: "Based on a review of the three studies used for this preliminary analysis, 

modeling results indicate that the CO2 plume stabilized on the time frame of 

10-100 years after the cessation of injection (USEPA, 2008d). EPA requests 

comment on the proposed use of a tentative 50-year fixed timeframe that could be 

modified at the Director's discretion based on monitoring and modeling data." 

(Page 29 of 51) 

ITCMI ESD would like to see monitoring and modeling data at a minimum 100 years, 

this will ensure the owner/operator be responsible for remediation efforts for a 

longer period. .. 

Response: EPA acknowledges that monitoring for a significant period of time may be necessary in

most cases; however, the Agency believes that setting a fixed monitoring timeframe of 100 years, as

the commenter suggests, is overly burdensome and is not necessary at most GS sites to ensure

protection of USDWs from endangerment. EPA bases this on a review of research studies, industry

reports, existing environmental programs, and evaluation of public comments. 

Instead, the final GS rule retains the 50-year default post-injection site care timeframe, in

conjunction with a performance standard, for Class VI wells. The GS rule provides the Director with

discretion to extend the timeframe (e.g., if, after 50 years, monitoring data indicates that the CO2

plume may endanger a USDW), or shorten the timeframe (if the owner or operator can demonstrate

that the GS project does not pose an endangerment to USDWs), under §146.93(b)(2). Such a

demonstration will be site-specific, and based on pressure monitoring and USDW impacts. Thus, the

GS rule offers owners or operators flexibility regarding the duration of the PISC timeframe by: (1)

allowing the Director discretion to shorten or lengthen the PISC timeframe during the post-injection

period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the

Director discretion to allow a Class VI well owner or operator to demonstrate, during the permitting
process based on substantial data, that an alternative PISC timeframe may be appropriate if it ensures

non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Michele Schoepper Letter ID: 0503

Commenter Organization: American Petroleum Institute Comment ID: 21174

Comment: EPA should also reconsider its proposed 50-year default period post injection 

site care. EPA offers no rationale for this arbitrarily selected period of 50 

years. Establishing a fixed and unusually long time period may create a 

significant barrier for operators considering entry into CCS operations. 

Criteria for determining the period for proposed injection site care should be 

performance based and a function of the site-specific characteristics of a 

project, such as the project's size, the geologic factors, and the relative 

risks of the project. 

Response: EPA disagrees with this comment. In determining the post-injection site care-timeframe

for the proposed regulation, EPA reviewed industry reports, existing environmental programs, and

initial GS research studies. EPA provided a synthesis of pertinent results from GS modeling studies

in the preamble to the proposed regulation. Further explanation of this analysis was included in an

EPA-prepared background document that is available in the federal docket, titled "Computational

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and

Potential Risk to Underground Sources of Drinking Water." Based on review of these studies,

modeling results indicate that the CO2 plume stabilization may occur on the timeframe of 10-100

years after the cessation of injection. EPA believes that a 50-year default post-injection site care

timeframe is a reasonable midpoint for most GS projects and available data, including data submitted

by commenters, do not support a different default timeframe, and has retained this in the final

regulation.

To address concerns that, in some situations, it can be demonstrated in less than 50 years that the

plume and pressure front no longer pose a risk of endangerment to USDWs, the GS rule offers

owners or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing the

Director discretion to shorten or lengthen the PISC timeframe during the post-injection period based

on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion

to allow a Class VI well owner or operator to demonstrate, during the permitting process based on

substantial data, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.
EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Iain Wright Letter ID: 0508

Commenter Organization: BP Alternative Energy Comment ID: 21184

Comment: So moving to my third and final point concerns the appropriate time frame for 

site closure. There is no rational basis to mandate the universal 50-year 

minimum time frame for post-injection site care. Such a mandate would kill off 

commercial investment in geo-sequestration projects. Worse than that, it would 

preferentially kill off all the best sites. It is with proven seals and the 

lowest risk of leakage - oil and gas fields. 

As the EPA proposal states the actual time for CO2 -plume stabilization will be 

very site-specific. Well selected and managed sequestration sites, such as an 

oil or gas field that has met its performance objectives, including plume 

stabilization, would be much more secure and could be closed relatively quickly, 

say a couple of years. 

However, as the EPA's cited examples show, CO2 injection in a poorly confined 

saline formation could be run for a while, such that the closure period and have 

to wait on residual and solubility trapping. Hence, a closure period of several 

years would be more appropriate. 

We recommend that EPA does not mandate any fixed time frame for site closure. 

Much better would be a site-specific assessment that is risk and performance 

based. Thank you. 

Response: EPA disagrees with this comment. In determining the post-injection site care-timeframe

for the proposed regulation, EPA reviewed industry reports, existing environmental programs, and

initial GS research studies. EPA provided a synthesis of pertinent results from GS modeling studies

in the preamble to the proposed regulation. Further explanation of this analysis was included in an

EPA-prepared background document that is available in the federal docket, titled "Computational

Modeling of Underground Injection of Carbon Dioxide for Determination of Area-of-Review and

Potential Risk to Underground Sources of Drinking Water." Based on review of these studies,

modeling results indicate that the CO2 plume stabilization may occur on the timeframe of 10-100

years after the cessation of injection. EPA believes that a 50-year default post-injection site care

timeframe is a reasonable midpoint for most GS projects and available data, including data submitted

by commenters, do not support a different default timeframe, and has retained this in the final

regulation.

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration
of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Scott Anderson Letter ID: 0510

Commenter Organization: Environmental Defense Fund Comment ID: 21217

Comment: We disagree, however, with API and differ with BP that, that the 50-year default 

period is being used in an arbitrary way. It's only being used as a default, 

one that can be shortened or lengthened depending on the circumstances of the 

particular case. 

The problem that we see with the proposed closure standard, and the reason that 

we agree that it needs to be improved, is really two-fold, which is about, 

frankly, as many folds as we'd like to come up with since it's a two-fold 

standard. 

The proposal, the bottom line says that you can either extend the 50-year period 

or decrease it upon a demonstration based on monitoring and other site-specific 

data, that the carbon dioxide plume and pressure front have stabilized. And, 

the second con, and that no additional monitoring is needed to assure that the 

geologic sequestration project does not pose an endangerment to USDWs. 

But the problem with the first part is that performance standard is that, as 

studies included in this docket, support documents that show there are 

circumstances where it could take centuries, or even in excess of a thousand 

years for the CO2 plume to completely stabilize. That part of the standard is 

not very realistic. 

The second part of the standard, showing that, that no additional monitoring 

needed, is needed is really just a restatement of the question. The question 

that we all need answered, regulators, the public, industry, is what does it 

take in order to decide whether additional monitoring is necessary. 
So that's why we agree with API and BP that this standard does need to work, and 

that what we need is a performance standard that really tells us when we can be 

sure that no additional monitoring is needed and it's time to -- that 

performance standards should be site-specific, which is really to say that it 

should depend on the circumstances and not the, something that's triggered by 

the simple passage time whether it's 50 years, or 150 years, or five years. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA agrees that a determination of when the post-injection site care timeframe ends will be sitespecific. EPA is developing guidance to assist owners or operators in evaluating well plugging, postinjection site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance

will assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under 146.92 and 146.93. The guidance describes recommended approaches for how an

owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Scott Anderson Letter ID: 0520

Commenter Organization: Environmental Defense Fund Comment ID: 21426

Comment: I would also like to agree in part and strongly disagree in part with my good 

friends from API and the National Association of Carbon Capture and Storage 

folks on this closure standard. The disagreement is this; we think that to call 

the fifty year default period arbitrary is just not accurate. If it said fifty 

years period without any ability to flex either direction, perhaps that would be 

arbitrary. Now that said, that does not mean that we support the proposed rule 

standard for approving site closure. In fact, the opposite. We think it needs to 

be substantially reworked and we do not even think you necessarily need a 
default period in order to have a solid performance standard for this. I am not 

going to go into exactly what we would substitute instead, but I can say that it 

will be generally consistent and perhaps precisely the same as comments that are 

being developed by the Ground Water Protection Council. 

Response: EPA based the GS post-injection site care and site closure requirements at §146.93 on

existing experience with injection activities, available data from GS pilot projects, and research

studies. EPA believes that all available data indicates that the injection well plugging and site closure

provisions provide appropriate safeguards for protection of USDWs from endangerment. 

EPA acknowledges that there are unknowns associated with early GS project deployment and the

long term storage of CO2 for GS. For these reasons, the Agency is using an adaptive approach to

regulating GS injection. The Agency plans, every six years, to collect and review data on GS projects

to determine whether the appropriate amount and types of information and appropriate

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

appropriate or necessary.

Commenter Name: Steve Crookshank Letter ID: 0523

Commenter Organization: American Petroleum Institute (API) Comment ID: 21357

Comment: EPA should also reconsider a proposed fifty year default period proposed 

injection site care. EPA offers no rationale for this arbitrarily selected 

period of fifty years. Establishing a fixed and unusually long time period may 

create a significant barrier for operators considering entry into CCS 

operations. Criteria for determining the period post injection site care should 

be performance based and a function of the site specific characteristics of the 

project such as project size, geologic factors and the relative risks of the 

project. 

Response: EPA disagrees that the decision to use a default 50 year period for PISC was arbitrarily

made. In determining the post-injection site care-timeframe for the proposed regulation, EPA

reviewed industry reports, existing environmental programs, and initial GS research studies. EPA

provided a synthesis of pertinent results from GS modeling studies in the preamble to the proposed

regulation. Further explanation of this analysis was included in an EPA-prepared background

document that is available in the federal docket, titled "Computational Modeling of Underground

Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk to

Underground Sources of Drinking Water." Based on review of these studies, modeling results

indicate that the CO2 plume stabilization may occur on the timeframe of 10-100 years after the

cessation of injection. EPA believes that a 50 year post-injection site care timeframe represents a

reasonable and protective monitoring period and available data, including data submitted by

commenters, do not support a different default timeframe. Furthermore, EPA believes that a 50-year

default post-injection site care timeframe, as required at §146.93(b)(1), is not overly burdensome,

does not exaggerate the risks associated with GS, is consistent with other environmental programs,

and sufficiently protects USDWs from endangerment.

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at
§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Kevin Frederick Letter ID: 0525

Commenter Organization: Wyoming Department of Environmental Quality Comment ID: 21405

Comment: We do not support requiring a fixed time frame for post injection site care of 

fifty years. We recommend that a performance standard be applied to determine a 

period of post injection site care. That post injection site care continues 

until the plume is stabilized and cannot endanger USDW's. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.
Commenter Name: Cynthia Lane Letter ID: 0528

Commenter Organization: American Water Works Association (AWWA) Comment ID: 21390

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: Finally, AWWA supports the rule requirement for the fifty year period for post 

injection site care. However, we suggest that it be set at a fifty year minimum 

with no discretion to shorten. Given the potential scope of carbon 

sequestration, this will provide for consistent approach across the U.S., 

provide strong long term protective measures of USDW's. 

In conclusion, AWWA is concerned that the proposed large scale sequestration of 

carbon dioxide in underground aquifers may have a significant impact on the 

public, the environment and drinking water utilities. We are also concerned that 

Response: EPA agrees that a 50 year post-injection site care timeframe represents a reasonable and

protective post-injection site monitoring period for most projects and available data, including data

submitted by commenters, do not support a different default timeframe. EPA bases this on a review

of research studies, industry reports, and existing environmental programs, and evaluation of public

comments. Furthermore, EPA believes that a 50-year default post-injection site care timeframe is not

overly burdensome, does not exaggerate the risks associated with GS, is consistent with other

environmental programs, and sufficiently protects USDWs from endangerment. For this reason, the

final GS regulation retains the 50 year post-injection site care timeframe, as specified in

§146.93(b)(1).

However, EPA disagrees that a 50 year post-injection site care timeframe should be an absolute

minimum. Rather, EPA believes, as some commenters suggest, that there will be circumstances

where it can be demonstrated in less than 50 years that the plume and pressure front no longer pose a

risk of endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Mike Moore Letter ID: 0532
Commenter Organization: North American Carbon Capture and Storage

Association (NACCSA)

Comment ID:

21369

Comment: The third area of concern is the proposed fifty year default post injection site 

care period. While some minimum period may be appropriate, a fifty year period 

is arbitrary and unwarranted by the specific characteristics of carbon dioxide. 

We note that the program director has discretion to extend or shorten the period 

without guidance. NACSA proposes that the rule adopt a period of performance 

based standard based on project specific information gained through the site 

characterization and monitoring phase. Alternatively the Agency should shorten 

the default period significantly to reflect the time required to assess CCS 

project work. 

Response: EPA disagrees that the decision to use a default 50 year time period for PISC was

arbitrarily made. In determining the post-injection site care-timeframe for the proposed regulation,

EPA reviewed industry reports, existing environmental programs, and initial GS research studies.

EPA provided a synthesis of pertinent results from GS modeling studies in the preamble to the

proposed regulation. Further explanation of this analysis was included in an EPA-prepared

background document that is available in the federal docket, titled "Computational Modeling of

Underground Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk

to Underground Sources of Drinking Water." Based on review of these studies, modeling results

indicate that the CO2 plume stabilization may occur on the timeframe of 10-100 years after the

cessation of injection. EPA believes that a 50 year post-injection site care timeframe represents a

reasonable and protective monitoring period and available data, including data submitted by

commenters, do not support a different default timeframe. Furthermore, EPA believes that a 50-year

default post-injection site care timeframe, as required at §146.93(b)(1), is not overly burdensome,

does not exaggerate the risks associated with GS, is consistent with other environmental programs,

and sufficiently protects USDWs from endangerment.

To address concerns that, in some situations, it can be demonstrated in less than 50 years that the

plume and pressure front no longer pose a risk of endangerment to USDWs, the GS rule offers

owners or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing the

Director discretion to shorten or lengthen the PISC timeframe during the post-injection period based

on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion

to allow a Class VI well owner or operator to demonstrate, during the permitting process based on

substantial data, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: George Peridas Letter ID: 0534

Commenter Organization: Natural Resources Defense Council (NRDC) Comment ID: 21458

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 
Comment: The closure standards I agree with Scott, I do not think that fifty years is 

arbitrary. I do not think that it is the magic number or that it will be 

appropriate for every single site. Nonetheless, I think it is a good benchmark, 

but we do need to have other flexibility to revise this upwards or downwards as 

project data comes in. 

I think what needs a little bit of refinement is the phrase at the discretion of 

the administrator. I think that should be some more concrete criteria as to when 

the administrator should reserve the rights to require certain techniques to be 

used on other requirements in the rule. 

Response: EPA agrees that the Director should have discretion to shorten or lengthen the postinjection site care monitoring period, and has retained this provision in the final GS rule at

146.93(b)(2). The GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

Because of the variety of site-specific circumstances at GS sites, EPA believes that individual UIC

Directors, in consultation with operators, will be in the best position to determine whether additional

post-injection site care monitoring is needed (or whether the timeframe may be shortened), based on

the circumstances of a particular project. EPA expects this decision to be made based on relevant

site data and in consultation with all potentially impacted parties. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

EPA is using an adaptive approach to regulate GS injection. The Agency plans, every six years, to

collect and review data on GS projects to determine whether the appropriate amount and types of

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

the requirements are appropriate or necessary.

Commenter Name: George Peridas Letter ID: 0534
Commenter Organization: Natural Resources Defense Council (NRDC) Comment ID: 21463

Comment: and I do also agree with the performance based closure standard rather than the 

mere passage of a number of years which could be ten, it could be fifty. I 

really do think that we need to look at what happens in each project rather than 

saying if you have been through a number of years, then it is fine. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Comment Code: 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Individual Comments

Commenter Name: Karl R. Moor Letter ID: 0109

Commenter Organization: Southern Company, on behalf of Edison Electric

Institute (EEI)

Comment ID:

22003

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: EEI urges EPA to defer to site-specific characteristic wherever possible in the 

regulations. 

For example, the proposed regulations contemplate a 50-year post- injection site 

care period, but the UIC program director can require continued monitoring if he 

or she deems it necessary to protect underground sources of drinking water. In 

the notice of proposed rulemaking, EPA states that it is willing to consider 

other time frames for the post-injection site care period, but instead of a 

default, the Agency should let the characteristics of each site determine the 

appropriate length of time for post-injection site care. If the director has 
the discretion to vary the length of the monitoring period based on sitespecific characteristics, establishing a lengthy default period would place an 

unnecessary burden on those owners and operators who can show that their 

projects pose no threat to underground sources of drinking water in less than 50 

years. In fact, EEI and its members believe that appropriately sited CCS 

projects will be able to make such a demonstration in substantially less than 50 

years, perhaps only 10 years since data suggest that the risk profile of carbon 

dioxide injection tails off markedly after a decade. Consequently, a lengthy 

default period would penalize those owners and operators who have taken steps to 

ensure proper site characterization. Surely, EPA would rather reward - and, 

therefore, encourage - appropriate siting: Properly managed site 

characterization and operations are the best way to ensure the highest level of 

protection for underground sources of drinking water. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the final GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording

the Director discretion to allow a Class VI well owner or operator to demonstrate, based on

substantial data during the permitting process, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

Because of the variety of site-specific circumstances at GS sites, EPA believes that Directors, in

consultation with operators, will be in the best position to determine whether additional postinjection site care monitoring is needed (or whether the timeframe may be shortened), based on the

circumstances of a particular project. EPA expects this decision to be made based on relevant site

data and in consultation with all potentially impacted parties. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA agrees that proper site characterization is a critical component of ensuring that USDWs are

protected. However, EPA disagrees that this is a substitute for post-injection site care. EPA believes

that extensive post-injection monitoring is necessary to protect USDWs from endangerment. 

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment. 

Commenter Name: Doug Louis Letter ID: 0121

Commenter Organization: Kansas Corporation Commission Comment ID: 22084

Comment: The proposed rule sets the post-injection site care period at a default period 

of 50 years. 

KCC staff agrees the UIC program Director should have the authority to shorten 
or lengthen the post-injection site care period if the owner/operator 

demonstrates a different time period is appropriate. 

Response: EPA acknowledges the commenter’s support; the final GS regulation retains this

provision at §146.93(b)(2). Such a demonstration will be site-specific, and based on pressure

monitoring and USDW impacts.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24804

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: (4) If such a demonstration cannot be made after the 50-year period, must 

submit to the Director a plan to continue post-injection site care.

{See comment above.} 

Response: As described above, the post-injection site care timeframe may be reduced by the

Director if the owner or operator can demonstrate that the remaining pressure front and plume no

longer pose a risk of endangerment to USDWs. The non-endangerment finding is left to the

discretion of the Director, based on site-specific information such as plume movement, pressure

decay, and the location of potential leakage pathways. As suggested by the commenter, a complete

cessation of plume movement is not required, only a demonstration that the plume and pressure front

no longer pose a risk of endangerment to USDWs, as specified in §146.93(b)(2-4). EPA retains this

provision in the final GS regulation 

GS rule also offers owners or operators flexibility regarding the duration of the PISC timeframe by

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, based on

substantial data during the permitting process, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Sam Kitto Letter ID: 0126

Commenter Organization: National Tribal Air Association Comment ID: 23046

Comment: for deciding upon the 50-year monitoring period. In addition, our organization 

recommends that the GS rule specifically require that qualified engineers 

trained in geologic sequestration be substantively involved in any decision 

regarding the shortening or lengthening of the post-closure monitoring period of 

an injection well. 

Response: EPA agrees and expects that qualified scientists and engineers will be involved in any

decision by the Director to lengthen or shorten the post-injection site care monitoring period, but is

not requiring this at §146.93.
The GS rule offers owners or operators flexibility regarding the duration of the PISC timeframe by:

(1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the postinjection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the

permitting process based on substantial data, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

Because of the variety of site-specific circumstances at GS sites, EPA believes that individual UIC

Directors, in consultation with operators, will be in the best position to determine whether additional

post-injection site care monitoring is needed (or whether the timeframe may be shortened) or if an

alternative PISC timeframe is appropriate, based on the circumstances of a particular project. EPA

expects this decision to be made based on relevant site data and in consultation with all potentially

impacted parties.

Commenter Name: Carl Carlsson Letter ID: 0131

Commenter Organization: SUEZ Energy Generation NA, LLC Comment ID: 21538

Comment: financing. As it currently reads, the proposed rule has provisions for extending 

this period in the event that performance standards are not met, so the standard 

would be adequately protective with a 30-year requirement. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, there are circumstances (e.g., little

development of mineral trapping of CO2) under which the potential risks of endangering USDWs

will likely not decline within these timeframes and available data, including data submitted by

commenters, do not support a different default timeframe. 

EPA acknowledges there will be circumstances where it can be demonstrated in less than 50 years

that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this reason,

the GS rule offers owners or operators flexibility regarding the duration of the PISC timeframe by:

(1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the postinjection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the

permitting process based on substantial data, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Dawn A. Thorne Letter ID:

0134
Commenter Organization: University of Utah Energy and Geoscience Institute on

behalf of the Southwest Regional Partnership

Comment

ID: 21659

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: - Section 146.93(b)(1) "The owner or operator shall continue to conduct 

monitoring as specified in the Director-approved post-injection site care and 

site closure plan for at least 50 years following the cessation of injection. At 

the Director's discretion, the monitoring will continue until the geologic 

sequestration project no longer poses an endangerment to USDWs." 

Response/Discussion: The SWP recommends adopting a performance-based approach to 

the site care period so that each site is monitored for as long as necessary, 

but not longer than necessary in order to avoid an extra cost burden to 

regulators and owners/operators. The required site-specific "post-injection site 

care and site closure plan" appears sufficient to convey appropriate monitoring 

techniques and timescales to the EPA Director. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA acknowledges the commenter’s support of the post-injection site care and site closure plan; the

final GS regulation retains this provision.

Commenter Name: Brianne Metzger Letter ID: 0151

Commenter Organization: Spectra Energy Corp Comment ID: 21878

Comment: A. The Director Should Have the Discretion To Shorten The Post-Injection Site 

Care Period, But Not Extend It. 

EPA is proposing a post-injection site care period of 50 years. The Director 

would have discretion to extend this period if after 50 years USDWs still face 

potential endangerment or modeling and monitoring results demonstrate that the 

CO2 plume and pressure front have not yet stabilized. The Director also could 

reduce this period if data on pressure, fluid movement, mineralization, and/or 

dissolution reactions indicate that the plume and pressure front have ceased 

and the injectate does not pose a risk to USDWs. EPA requested comment on the 

proposed use of a tentative 50-year fixed timeframe that could be modified at 
the Director’s discretion based on monitoring and modeling data. 

Spectra supports EPA’s approach granting the Director discretion to adjust the 

timeframe based on the risk posed to USDWs. This approach takes into account 

the site-specific nature of CCS projects and recognizes the importance of 

creating a rule that does not place unnecessary regulatory, financial, or 

technical burdens on site owners and operators. However, Spectra proposes 

limiting Director discretion to the ability to shorten the post-injection site 

care period, upon meeting certain performance-based criteria that indicate the 

CO2 plume has stabilized and poses no recognizable risk to USDWs. This creates 

an incentive for project operators to adhere to best practices and could 

potentially encourage CCS project development. 

Spectra respectfully disagrees with granting the Director the discretion to 

extend the post-injection site care period beyond the fixed, pre-determined 

time period, on grounds that this places an unreasonable and potentially 

prohibitive financial risk on site operators. Specifically, owners or 

operators whose post-injection site care period is extended may be unable to 

secure additional financial assurance to cover the additional period of time. 

EPA cannot assume that owners or operators would be able to renew or extend the 

risk management instrument it procured prior to commencing injection and 

storage operations, nor can it assume that an owner or operator would be able 

to secure a new risk management instrument in the market. The possibility of 

an extension creates a risk for owners or operators that they may have to 

finance post-injection site care well beyond the default period, which would 

increase project costs and potentially inhibit CCS project development 

altogether. Furthermore, the extension of a post-injection site care period 

for an owner or operator that is no longer solvent exposes the public to 

unnecessary risk and would require governmental intervention. Rather than the 

possibility of an extension at the Director’s discretion, Spectra believes that 

a fixed post-injection site care period with the possibility of it being 

shortened upon meeting certain performance criteria that are evaluated on a 

site-by-site basis creates an incentive for operators to adhere to best 

practices and removes what would be a major deterrent from CCS project 

development. Spectra further believes that EPA should develop such performance 

criteria as soon as possible and in a manner that provides a realistic 

possibility that sites with stabilized CO2 plumes would qualify for a shorter 

post-injection site care period. 

Response: EPA disagrees that the Director should not have discretion to lengthen the post-injection

site care monitoring period. EPA believes that 50 years is an appropriate default post-injection site

care timeframe in most cases. However, EPA recognizes that, in some cases, the post-injection site

care timeframe may need to be lengthened based on site-specific circumstances. For instance, if after

50 years, monitoring data indicates that the CO2 plume is still moving and may endanger a USDW,

monitoring should continue on a regular basis, as specified in §146.93(b)(2).

Because of the variety of site-specific circumstances at GS sites, EPA believes that Directors, in

consultation with operators, will be in the best position to determine whether additional postinjection site care monitoring is needed (or whether the timeframe may be shortened), based on the

circumstances of a particular project. EPA expects this decision to be made based on relevant site
data and in consultation with all potentially impacted parties.

Commenter Name: Jeff Moseley Letter ID: 0155

Commenter Organization: Greater Houston Partnership (GHP) Comment ID: 21260

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: 7. Revise the standard for determining site closure. Criteria should be 

performance based and a function of site-specific geologic and other risk 

criteria, rather than being dependent on a 50-year-period or any other fixed 

period of time; and, 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the final GS regulation offers owners or operators

flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to

shorten or lengthen the PISC timeframe during the PISC period based on site-specific data, pursuant

to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well

owner or operator to demonstrate, based on substantial data during the permitting process, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care is necessary in most cases. A 50 year post-injection site care timeframe

represents a reasonable and protective monitoring period for most GS projects based on a review of

research studies, industry reports, and existing environmental programs, and evaluation of public

comments.

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23790

Comment: In addition, EPA seeks comment on whether the Director should be allowed to 

shorten the timeframe based on performance information, and whether EPA should 

require a shorter or longer post injection period if data suggests the time 

frame should be adjusted. EPA Notice 125-26. 

EPA should allow the Director to shorten the timeframe based on performance 

information. However, an open-ended time period results in a high degree of 

uncertainty regarding cost exposure to a project developer. It also leaves a 

site open to future liability from "reopeners" by the regulatory community. To 

avoid this latter scenario, a maximum monitoring period should be defined in 

terms of clear, performance-based risk metrics - for example, that the validated 

model predicts that 95% of the plume is or will be trapped and that a 

sensitivity analysis predicts a comfortable margin of safety and diminimus risk 
of endangerment to any USDWs. 

Response: EPA disagrees that the Director should not have discretion to shorten or lengthen the

post-injection site care monitoring period or that it creates a “high degree of uncertainty regarding

cost exposure.” Because of the variety of site-specific circumstances at GS sites, EPA believes that

individual UIC Directors, in consultation with operators, will be in the best position to determine

whether additional post-injection site care monitoring is needed (or whether the timeframe may be

shortened), based on the circumstances of a particular project. EPA expects this decision to be made

based on relevant site data and in consultation with all potentially impacted parties to ensure USDW

protection. 

EPA recognizes that there are challenges associated with assuring funding for activities that will

occur far in the future. However, the Agency believes that operators must demonstrate that financial

resources are available to plug the injection well and provide post-injection care at the point in time

that the first CO2 is injected. EPA also recognizes the concerns associated with assuring financial

responsibility for the long time frames over which post-injection site care will be conducted. EPA is

developing guidance on financial responsibility to assist owners or operators in evaluating the

requirements of §146.85 and to assist Directors in evaluating financial responsibility demonstrations.

The guidance describes the types of financial mechanisms that operators may choose to use when

evaluating the financial responsibility requirements for GS wells and it will also include a section on

how to estimate costs to support accurate financial responsibility demonstrations. The guidance will

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

Commenter Name: Sandi Tabor Letter ID: 0162

Commenter Organization: Lignite Energy Council (LEC) Comment ID: 21304

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: 5. Combination of Fixed Timeframe and Performance Standard -EPA is seeking 

comments on the imposition of a 50-year post-injection site care (PISC) standard 

as a default timeframe with state UIC directors having discretion to adjust the 

default time period. We urge EPA to remove all reference to default PISC periods 

and instead require directors to base post-injection site care on site and 

project specific characteristics. By so doing the goal of supporting the 

commercialization of CCS technology is better served. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the final GS regulation offers owners or operators flexibility regarding the duration of the

PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe

during the PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, based on

substantial data during the permitting process, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize
site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care is necessary in most cases. A 50 year post-injection site care timeframe

represents a reasonable and protective monitoring period for most GS projects based on a review of

research studies, industry reports, and existing environmental programs, and evaluation of public

comments. 

Commenter Name: Michael J. Miller Letter ID: 0168

Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22511

Other EPA Comment Codes and Descriptions: 5280 2.8.2.4 USDW non-endangerment

demonstrations 

Comment: Preamble, page 43520: "Once the owners or operators provide documentation that 

demonstrates that the models predicting CO2 movement are consistent with 

monitoring results and that there are no longer risks of endangerment to USDWs, 

they could request that the Director authorize site closure. EPA is also 

proposing to allow the Director to shorten or lengthen the 50-year time frame 

based on performance of the site... EPA wishes to emphasize that site closure 

cannot occur until monitoring and modeling data establish to the Director’s 

satisfaction that potential risks of endangerment to USDWs have ceased." 

EPRI COMMENT #18: EPA’s requirement for demonstrating plume stability for site 

closure is based on the ability to both observe and successfully model the speed 

and stability of the advancing CO2 front, a very discrete boundary that is 

difficult to define, model accurately when complex reservoir heterogeneity and 

fast flow pathways are present, and measure in the field on a large scale. (See 

also EPRI’s comment #2 on defining the front). If remote methods like surface 

seismic, cross-well seismic or gravity are not successful in tracking front 

position, and CO2 is never directly detected in sentinel observations wells, 

then model validation based on CO2 front position may be questioned. In such a 

case, if the model predicts the continued advance of the CO2 front while the 

observed data do not, the EPA Director may not be satisfied with the absence of 

a potential risk of endangerment to USDWs and may unnecessarily delay site 

closure for decades. EPRI recommends that the final rule contain alternative 

provisions for site closure if model validation is unsuccessful. 

Response: EPA acknowledges that many site-specific factors will influence the determination of

when the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for

this reason that EPA believes that individual UIC Directors, in consultation with operators, will be in

the best position to determine whether additional post-injection site care is needed. EPA expects this

decision to be made based on relevant site data and in consultation with all potentially impacted

parties. 

EPA also agrees that a complete cessation of plume movement may not occur at some sites for long

time periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies

that a complete cessation of plume movement is not required, only a demonstration that the plume

and pressure front no longer pose a risk of endangerment to USDWs. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will
assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24209

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(4) 

API Comments: (4) If such a demonstration cannot be made (i.e., if the carbon 

dioxide plume and pressure front have not stabilized) after the 50-year period, 

the owner or operator must submit to the Director a plan to continue postinjection site care.

Rationale: No longer necessary given changes above. 

Response: As described above, EPA believes that to ensure USDW protection from endangerment, a

default timeframe for post-injection site care is necessary in most cases. A 50-year post-injection site

care timeframe represents a reasonable and protective monitoring period for most GS projects based

on a review of research studies, industry reports, and existing environmental programs, and

evaluation of public comments. However, EPA recognizes that alternative timeframes may be

appropriate under limited, specific circumstances. For this reason, the Class VI rule offers owners or

operators flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director

discretion to shorten or lengthen the PISC timeframe during the PISC period based on site-specific

data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class

VI well owner or operator to demonstrate, based on substantial data during the permitting process,

that an alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs

pursuant to requirements at §146.93(c).

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24257

Comment: Rule Provisions: 146.93(b)(2) 

EPA Preamble Question: 40. In addition, EPA seeks comment on whether the 

Director should be allowed to shorten the timeframe based on performance 

information, and whether EPA should require a shorter or longer post injection 

period if data suggests the time frame should be adjusted. EPA Notice 43520. 

API Response: See question 38 above regarding post closure time periods. 

Response: As described above, EPA recognizes that there may be sites where the 50 year post

injection site care timeframe may be either not appropriate or more burdensome than necessary

based on site-specific conditions. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner
or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist

Directors in evaluating proposed well plugging plans and post-injection site care and site closure

plans required under 146.92 and 146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells, perform post-injection monitoring,

demonstrate the appropriateness of an alternative post-injection site care time frame, demonstrate

non-endangerment, and perform site closure activities. This guidance will be available at

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

Commenter Name: Robert J. Finley Letter ID: 0180

Commenter Organization: Illinois State Geological Survey Comment ID: 23641

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: 146.93 

(b)(1) 

Monitoring for 50 years following cessation of injection has no particular basis 

in research and should not be the rule against which an operator should be 

required to seek an exception as provided for in (b)(2). Rather, the regulations 

should require a maximum post-injection site monitoring plan for, for example, 

15 years to include comprehensive reservoir assessment, modeling, and simulation 

based on data collection during injection and then specifically at closure, 

followed by five years after closure, 10 years after closure, and 15 years after 

closure. These suggested intervals have a basis in the changes seen in the 4D 

seismic as Sleipner that show demonstrable geophysical responses based on 

injection and plume development over about a 10 year period. Other groups have 

suggested 10 years of total post-closure monitoring, thus other repeat periods 

for site surveys may be suggested and should be considered. For the example 

suggested here, the data taken at closure forms a baseline, such as plume extent 

based on a 3D seismic survey or other geophysical techniques, and three 

subsequent surveys at five-year intervals could document plume migration and 

would serve to validate reservoir simulation. If the total of four such example 

surveys (closure, +5, +10, and +15) and/or other appropriate monitoring 

techniques, and the reservoir modeling and simulation, demonstrate a consistent 

and predictable understanding of subsurface behavior that does not endanger 

USDWs going forward, then the operator should be deemed to have fulfilled site 
closure responsibilities. To repeat, there is no basis for the suggested 50 

years of monitoring. 

Response: EPA disagrees that there is no basis for the 50 year timeframe. In determining the postinjection site care-timeframe for the proposed regulation, EPA reviewed industry reports, existing

environmental programs, and initial GS research studies. EPA provided a synthesis of pertinent

results from GS modeling studies in the preamble to the proposed regulation. Further explanation of

this analysis was included in an EPA-prepared background document that is available in the federal

docket, titled "Computational Modeling of Underground Injection of Carbon Dioxide for

Determination of Area-of-Review and Potential Risk to Underground Sources of Drinking Water."

Based on review of these studies, modeling results indicate that the CO2 plume stabilization may

occur on the timeframe of 10-100 years after the cessation of injection. EPA believes that a 50-year

default post-injection site care timeframe is a reasonable midpoint for most GS projects and

available data, including data submitted by commenters, do not support a different default timeframe,

and has retained this in the final regulation.

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the Class VI rule offers owners or operators flexibility regarding the

duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the

PISC timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA clarifies that, throughout the post-injection site care timeframe, owners and operators must

submit monitoring data results to the Director. At these times (or at 5 year intervals), the owner or

operator may wish to discuss whether performing a non-endangerment demonstration may be

appropriate. This scenario affords many of the suggestions the commenter offers. 

Commenter Name: Wendy Jacobs Letter ID: 0183

Commenter Organization: Harvard Law School Environmental Law and Policy

Center

Comment ID:

25144

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: C. EPA Should Clarify the Site Closure Standard 

EPA is proposing a "combination of fixed timeframe and performance standard"

approach to site closure. 73 Fed. Reg. at 43,519. Under the proposal, the owner

or operator would be required to undertake "post-injection site care" following

the permanent cessation of injection activities at the site, which would include

"submit[ting] periodic reports providing monitoring results and updated modeling
results as appropriate until a demonstration of nonendangerment to USDWs can be

made." Id. at 43,520. Specifically, the owner or operator would need to

demonstrate "that the carbon dioxide plume and pressure front have stabilized

and that no additional monitoring is needed to assure that the geologic

sequestration project does not pose an endangerment to USDWs." Id. at 43,541

(proposed 40 C.F.R. § 146.93(b)(3)). Once the owners or operators provide

documentation to show that this standard has been met, they can request that the

Director authorize site closure. Id. at 43,520. By default, the "post-injection

site care" period would last for 50 years following cessation of injection

activities; however, the Director would have discretion to shorten the 50-year

timeframe if the owner or operator could demonstrate "stabilization/no

endangerment" in less than 50 years, or conversely, to lengthen the timeframe if

the owner or operator failed to make a demonstration within 50 years. Id.

As a general matter, ELPC and ETIP agree that a combination of a fixed timeframe

and a performance standard strikes a good balance and is preferable to relying

upon only one of those elements. Adherence to an exacting performance standard

alone, defined before commercial deployment of CCS technologies, could preclude

owner or operators from taking advantage of best practices as they are

developed. Adherence to a single fixed timeframe could allow owner or operators

to abandon well sites even as monitoring data indicates a threat to a USDW.

Requiring the owner or operator to meet a flexible performance standard

throughout a baseline period of 50 years would ensure that post-injection site

care, including monitoring and verification, would continue as long as necessary

to prevent endangerment of USDWs and require post-injection monitoring and

modeling even if the data appear to show "stabilization" within a short

timeframe. This would be especially prudent in the short term, given lack of

data and experience with large-scale, long-term GS projects.

Response: EPA agrees and has implemented a combination fixed timeframe and performance

standard approach for post-injection site care monitoring for Class VI wells. EPA believes that a

default PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this timeframe,

combined with a site-specific Director’s discretion to create an alternative PISC time frame, ensures

that USDWs are protected. The GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Bradley J. Field Letter ID: 0186
Commenter Organization: New York State Dept. of Environmental Conservation

Div. of Mineral Resources

Comment ID:

25213

Comment: OO. In addition, EPA seeks comment on whether the Director should be allowed to 

shorten the timeframe based on performance information, and whether EPA should 

require a shorter or longer post-injection period if data suggests the time 

frame should be adjusted. 

NYSDEC-DMN Response: Given that current injection and reservoir behavior data 

demonstrates a decreasing risk of leakage after injection ceases, NYSDEC-DMN 

believes that a 50-year default time frame for post-injection site care is too 

long and that a 30-year starting period may be more appropriate to allow GS 

projects to move forward. It would be better to prescribe a shorter period with 

discretion to go longer, rather than vice versa, as such would better facilitate 

project planning. Regardless, it is critical that the Director have the 

discretion to increase or decrease the period based on the specifics of a 

particular project. 

Response: EPA acknowledges that there will be circumstances where it can be demonstrated in less

than 50 years that the plume and pressure front no longer pose a risk of endangerment to USDWs.

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

As described above, EPA disagrees that a post-injection site care timeframe of 50 years is excessive

for most Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based

on a review of research studies, industry reports, and existing environmental programs. While the

10- or 30-year timeframe suggested by some of these commenters may be within the timeframe

suggested in some studies, there are circumstances (e.g., little development of mineral trapping of

CO2) under which the potential risks of endangering USDWs will likely not decline within these

timeframes and available data, including data submitted by commenters, do not support a different

default timeframe. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190
Commenter Organization: Carbon Sequestration Council Comment ID: 24500

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(4) 

Proposed CCS Group Recommendations: (4) If such a demonstration cannot be made 

(i.e., if the carbon dioxide plume and pressure front have not stabilized) after 

the 50-year period, the owner or operator must submit to the Director a plan to 

continue post-injection site care.

Basis for CCS Group Comments: No longer necessary with 50-year period deletion. 

Response: As described above, EPA believes that to ensure USDW protection from endangerment, a

default timeframe for post-injection site care is necessary in most cases. A 50-year post-injection site

care timeframe represents a reasonable and protective monitoring period for most GS sites based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24549

Comment: Rule Provisions or Federal Register Cite: 146.93(b)(2) 

EPA Preamble Question: 40. In addition, EPA seeks comment on whether the 

Director should be allowed to shorten the timeframe based on performance 

information, and whether EPA should require a shorter or longer post injection 

period if data suggests the time frame should be adjusted. EPA Notice 43520. 

CSC Response: See response to Question 38 above regarding post closure time 

periods. 

Response: As described above, EPA acknowledges that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist

Directors in evaluating proposed well plugging plans and post-injection site care and site closure

plans required under 146.92 and 146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells, perform post-injection monitoring,

demonstrate the appropriateness of an alternative post-injection site care time frame, demonstrate

non-endangerment, and perform site closure activities. This guidance will be available at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.
Commenter Name: John R. Baza Letter ID: 0193

Commenter Organization: Utah Division of Oil, Gas, and Mining Comment ID: 23917

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: Post Site Care Responsibility 

EPAs proposed rule sets the post-injection care period at 50 years. This may be 

modified if it can be demonstrated that the plume has stabilized and the 

pressure has dissipated. Setting a 50-year period may be unnecessarily long. The 

Division’s recommendation is that a shorter period be prescribed and then the 

regulating agency may have the discretion to set a longer post-injection care 

period if the specifics of a project indicate such a need. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. 

However, EPA acknowledges there will be circumstances where it can be demonstrated in less than

50 years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For

this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Andy Horn Letter ID: 0196
Commenter Organization: Colorado Ground Water Association (CGWA) Comment ID: 23933

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: Issue 11. The post-closure operator liability timeframe of 50 years should be 

considered a minimum and should be extended in the event monitoring and modeling 

data indicate potential failure may require mitigation. 

Response: EPA agrees with commenters that a 50 year post-injection site care timeframe represents

a reasonable and protective monitoring period for most cases. EPA bases this on a review of

research studies, industry reports, existing environmental programs, and evaluation of public

comments. Furthermore, EPA believes that a 50-year default post-injection site care timeframe is not

overly burdensome, does not exaggerate the risks associated with GS, is consistent with other

environmental programs, and sufficiently protects USDWs from endangerment. For this reason, the

final GS regulation retains the 50 year post-injection site care timeframe, as specified in

§146.93(b)(1). 

However, EPA disagrees that a 50-year post-injection site care timeframe should be an absolute

minimum. Rather, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. For this reason, the GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c). 

Such a demonstration will be site-specific, and based on pressure monitoring and USDW impacts.

EPA clarifies that in no cases will site closure be authorized until the owner or operator demonstrates

to the satisfaction of the Director that the site no longer poses a risk of endangerment to USDWs. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24610

Comment: Rule Provisions: 146.93(b)(2) 

EPA Rule Issue: 40. In addition, EPA seeks comment on whether the Director 

should be allowed to shorten the timeframe based on performance information, and 

whether EPA should require a shorter or longer post injection period if data 

suggests the time frame should be adjusted. EPA Notice 43520. 

Anadarko Petroleum Corporation (APC) Response: It is inappropriate to utilize a 

fixed period; instead a demonstration of non endangerment is an appropriate 

means of deciding when monitoring is no longer needed. Please see response to 
EPA 43519. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24722

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b)(4) 

Anadarko Petroleum Corporation (APC) Comments: (4) If such a demonstration 

cannot be made (i.e., if the carbon dioxide plume and pressure front have not 

stabilized) after the 50-year period, the owner or operator must submit to the 

Director a plan to continue post-injection site care.

Rationale: No longer necessary given changes above. 

Response: As described above, EPA disagrees that a post-injection site care timeframe of 50 years is

excessive in most cases or arbitrary, and retains the default 50-year post-injection site care

timeframe in the final rule. .

Commenter Name: John Corra Letter ID: 0205

Commenter Organization: Wyoming Department of Environmental Quality

(DEQ)

Comment ID:

22198

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: 4.Requiring a fixed timeframe post-injection site care (monitoring) period of 50 

years: 
a.We recommend that a performance standard be applied to determine the period of 

post-injection site care -that post-injection site care continues until the 

plume is stabilized and will not endanger USDWs. 

b. We recommend that the Director should be provided discretion to shorten or 

lengthen the proposed post-injection site care period of 50 years accordingly. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22714

Comment: Concern #8: The owner or operator shall continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site closure 

plan for at least 50 years following the cessation of injection. At the 

Director’s discretion, the monitoring will continue until the geologic 

sequestration project no longer poses an endangerment to USDWs. (Ref: page 

43519, Sec. 8. Post-Injection Site Care Timeframe) 

The time required for post-injection site management should not be arbitrarily 

set at 50 years. Criteria for defining the time for post-injection management 

should be performance based and site specific. The choice of 50 years is 

arbitrary and does not take into account the data and knowledge and modeling 

verification obtained over a preceding operating and injection period of years 

and likely decades. The maximum post-injection monitoring period should be 

defined on reasonable but quantitative, performance-based metrics - for example, 

that the validated model predicts that 95% of the plume is or will be trapped 
and that a sensitivity analysis predicts a comfortable margin of safety to 

minimize approach to any USDWs, thus preventing potential endangerment. Concern 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most cases or

arbitrary. EPA proposed a default post-injection site care timeframe of 50 years based on a review of

research studies, industry reports, and existing environmental programs. This analysis was included

in an EPA-prepared background document that is available in the federal docket, titled

Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water. EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, there are circumstances (e.g., little

development of mineral trapping of CO2) under which the potential risks of endangering USDWs

will likely not decline within these timeframes and available data, including data submitted by

commenters, do not support a different default timeframe. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA recognizes that there are challenges associated with assuring funding for activities that will

occur far in the future. However, the Agency believes that operators must demonstrate that financial

resources are available to plug the injection well and provide post-injection care at the point in time

that the first CO2 is injected. EPA also recognizes the concerns associated with assuring financial

responsibility for the long time frames over which post-injection site care will be conducted. EPA is

developing guidance on financial responsibility to assist owners or operators in evaluating the

requirements of §146.85 and to assist Directors in evaluating financial responsibility demonstrations.

The guidance describes the types of financial mechanisms that operators may choose to use when

evaluating the financial responsibility requirements for GS wells and it will also include a section on

how to estimate costs to support accurate financial responsibility demonstrations. The guidance will
be available at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22740

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: In addition, EPA seeks comment on whether the Director should be allowed to 

shorten the timeframe based on performance information, and whether EPA should 

require a shorter or longer post injection period if data suggests the time 

frame should be adjusted. EPA Notice 125-26. 

EPA should allow the Director to shorten the timeframe based on performance 

information. However, an open-ended time period results in a high degree of 

uncertainty regarding cost exposure to a project developer. It also leaves a 

site open to future liability from "reopeners" by the regulatory community. To 

avoid this latter scenario, a maximum monitoring period should be defined in 

terms of clear, performance-based risk metrics - for example, that the validated 

model predicts that 95% of the plume is or will be trapped and that a 

sensitivity analysis predicts a comfortable margin of safety and diminimus risk 

of endangerment to any USDWs. 

Response: EPA disagrees that the Director should not have discretion to shorten or lengthen the

post-injection site care monitoring period. Because of the variety of site-specific circumstances at

GS sites, EPA believes that Directors, in consultation with operators, will be in the best position to

determine whether additional post-injection site care monitoring is needed (or whether the timeframe

may be shortened), based on the circumstances of a particular project. EPA expects this decision to

be made based on relevant site data and in consultation with all potentially impacted parties to

ensure USDW protection. The final GS regulation retains the provision that the Director may, at his

or her discretion, shorten the post-injection site care timeframe if the owner or operator can

demonstrate that the GS project does not pose an endangerment to USDWs, as specified in

§146.93(b)(2).

Alternatively, the final rule at §146.93(c), also allows the Director to approve an alternative postinjection site care timeframe where an owner or operator can demonstrate during the permitting

process that an alternative post-injection site care timeframe, other than the 50 year default, is

appropriate and ensures non-endangerment of USDWs. The demonstration must be based on sitespecific information, including the results of site-specific computational modeling; the predicted

timeframe for pressure decline; the predicted rate of carbon dioxide plume migration; site-specific

chemical processes that will result in carbon dioxide trapping; the predicted rate of carbon dioxide

trapping; characterization of the confining zone(s); laboratory analyses or studies to verify the

information on trapping; the presence of potential conduits for fluid movement and the quality of

abandoned well plugs within the AoR; the distance between the injection zone and the USDWs

above and/or below the injection zone; and any additional site-specific factors determined by the

Director. The demonstration must meet the criteria at §146.93(c)(2) for ensuring the quality and

accuracy of the data and models on which the demonstration is based. This demonstration would be

submitted as part of the permit application, per §146.82(a)(18), in addition to the PISC and site

closure plan required at §146.82(a)(17).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial
data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Diane VanDe Hei Letter ID: 0213

Commenter Organization: Association of Metropolitan Water Agencies

(AMWA)

Comment ID:

22951

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: - 73 FR 43519 -EPA requests comment on the proposed use of a tentative 50-year 

fixed [post injection site care] timeframe that could be modified at the 

Director’s discretion based on monitoring and modeling data. 

Response: AMWA supports a minimum 50-year time frame for post-injection site 

care and recommends that the Director not be given any discretion to shorten 

this time period. EPA notes in the proposal that "the potential risks of 

endangering USDWs will not decline within that timeframe given that 

stabilization may continue for several decades." AMWA also recommends that 

Response: EPA disagrees that the Director should not have discretion to shorten or lengthen the

post-injection site care monitoring period. EPA believes that 50 years is an appropriate default postinjection site care timeframe. However, EPA recognizes that there may be sites where the 50 year

post injection site care timeframe may be either not appropriate or more burdensome than necessary

based on site-specific conditions. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23993
Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: 10. § 146.93 Post-injection site care and site closure. 

The proposed rule establishes a 50 year default period for post-injection site 

care. There is, however, no factual or scientific basis for such an extensive 

period. Under EPA’s Resource Conservation and Recovery Act rules, which regulate 

the disposal of hazardous wastes, post closure care is limited to 30 years. 

Defaulting to an excessively long period will increase costs and introduce 

greater regulatory uncertainty, which will discourage capital formation around 

CO2 sequestration. 

Additionally, even though the proposed rule appears to include a 50 year default 

post injection site care period, in reality, that deadline is illusory as it is 

not self executing. Under the rules, post injection site care must continue 

indefinitely until the Director authorizes closure. The closure approval process 

could take years, even decades, as the Director has no regulatory incentive to 

act on any post injection site care report. Meanwhile, a permittee may be 

required to continue unnecessary and expensive monitoring and reporting 

indefinitely. 

Whether the post-injection site care period is site-specific, or 10 to 50 years, 

TxCCSA suggests that the post-injection site care provision be reconfigured to 

be self-executing and allow for closure at the end of that period unless the 

Director affirmatively acts to extend the post-injection site care period. These 

Response: Because of the variety of site-specific circumstances at GS sites, EPA believes that

individual UIC Directors, in consultation with operators, will be in the best position to determine

whether additional post-injection site care monitoring is needed (or whether the timeframe may be

shortened), based on the circumstances of a particular project. EPA expects this decision to be made

based on relevant site data and in consultation with all potentially impacted parties, and will not be

made arbitrarily. 

EPA believes that 50 years is an appropriate default post-injection site care timeframe. However,

EPA recognizes that, in some cases, the post-injection site care timeframe may need to be

lengthened or shortened based on site-specific circumstances. For instance, if after 50 years,

monitoring data indicates that the CO2 plume is still moving and may endanger a USDW,

monitoring should continue on a regular basis. Conversely, if it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs, continuing

post-injection site care would be unnecessary (see 146.93(b)(2)).

EPA disagrees that the 50 year timeframe is unsupported. In determining the post-injection site caretimeframe for the proposed regulation, EPA reviewed industry reports, existing environmental

programs, and initial GS research studies. EPA provided a synthesis of pertinent results from GS

modeling studies in the preamble to the proposed regulation. Further explanation of this analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

"Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water." Based on review of these

studies, modeling results indicate that the CO2 plume stabilization may occur on the timeframe of

10-100 years after the cessation of injection. EPA believes that a 50-year default post-injection site
care timeframe is a reasonable midpoint, and has retained this in the final regulation. 

EPA believes that, given the unique challenges associated with GS of large volumes of injected

CO2, post-injection site care should continue until it can be demonstrated that the CO2 plume and

pressure front no longer pose a risk of endangerment to USDWs. For this reason, the final regulation

retains the requirement at §146.93(b)(3) that the owner or operator must submit to the Director a

demonstration, based on monitoring and other site-specific data, that no additional monitoring is

needed to ensure that the GS project does not pose a risk of endangerment to USDWs. Additionally,

the permitting authorities responsible for Class VI wells will maintain an active role with the owner

or operator in order to ensure protection of USDWs from endangerment.

EPA disagrees with the commenter's suggestion regarding self-execution. EPA believes that, given

the unique challenges associated with GS of large volumes of injected CO2, post-injection site care

should continue until it can be demonstrated that the CO2 plume and pressure front no longer pose a

risk of endangerment to USDWs. For this reason, the final regulation retains the requirement at

146.93(b)(3) that the owner or operator must submit to the Director a demonstration, based on

monitoring and other site-specific data, that no additional monitoring is needed to ensure that the GS

project does not pose a risk of endangerment to USDWs. Additionally, the permitting authorities

responsible for Class VI wells will maintain an active role with the owner or operator in order to

ensure protection of USDWs from endangerment.

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21696

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: HEI urges EPA to adopt the performance standard that EPA considered in its 

review. EPA considered three options: (1) fixed period; (2) performance 

standard; and (3) combination of fixed period and performance standard; EPA 

states it adopted the latter approach. (73 Fed. Reg. at 43519.) While the 

Proposed Rule allows a Director to reduce the 50-year minimum (§146.93(b)(2)), 

the practical effect will be the 50-year timeframe applies unless an operator is 

able to overcome the presumption built into the Proposed Rule that 50 years is 

adequate. Indeed, this is more prescriptive than the requirement for Class I 

hazardous wells, which provides that the timeframe for post-injection site care 

ends when the plume has stabilized and cannot endanger USDWs. (Id.; 40 CFR 

§146.71.) 

Response: EPA agrees that some owners or operators will be able to demonstrate, in less than 50

years, that the pressure front and plume no longer pose a risk of endangerment to USDWs. However,

based on studies, EPA believes that the 50 year default time frame is warranted based on additional

review of research studies and reports and evaluation of public comments. 

However, EPA recognizes that there may be sites where the 50 year post injection site care

timeframe may be either not appropriate or more burdensome than necessary based on site-specific

conditions. EPA believes that the best way to address all possibilities, while ensuring USDW

protection from endangerment, is to set a 50 year default post-injection site care timeframe, with

flexibility to: (1) allow the Director discretion to shorten or lengthen the PISC timeframe during the

PISC period based on site-specific data, pursuant to requirements at §146.93(b); or (2) afford the

Director discretion to allow a Class VI well owner or operator to demonstrate, based on substantial
data during the permitting process, that an alternative PISC timeframe may be appropriate if it

ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Tiffany Rau Letter ID: 0224

Commenter Organization: Hydrogen Energy International Comment ID: 21697

Comment: EPA should adopt the performance-based standard that it considered previously. 

Accordingly, the post-injection site care period ends when monitoring and other 

site-specific data demonstrate that the geologic sequestration project does not 

pose an endangerment to USDWs. (See e.g., 73 Fed. Reg. 43520.) A performancebased approach is consistent with technical knowledge and historic industry 

experience. The site closure period would be appropriately based on particular 

site characteristics and historic site performance. For example, a wellselected and -managed sequestration site (such as an existing oil or gas field) 

that has met its performance objectives (including plume stabilization) will be 

much more secure and could be closed reasonably quickly (potentially, in as few 

as 2-3 years). At other sites that are less well confined (e.g., deep saline 

formation without a conventional 4-way closure), the CO2 could move around for 

some time even after injection ceases before stabilizing, and might therefore 

require a longer period to allow for additional residual and solubility 

trapping. 

In summary, HEI recommends that EPA adopt a performance-based approach to 

determine the timeframe for site closure. We also support the site closure 

standard offered in the MSDG Proposal for section 146.93(b), which sets forth 

detailed criteria that must be satisfied to demonstrate that the site does not 

pose an endangerment to USDWs. The advantage of the MSDG Proposal as opposed to 

a fixed period is it establishes clear criteria that an operator must 

demonstrate before obtaining site closure based upon particular site 

characteristics and is, therefore, reasonable applicable to any storage site as 

opposed to a standard based upon a fixed-duration. The current proposal of 50- 

years minimum, even subject to potential reduction, would result in 

significantly discouraging the deployment of this technology at commercial scale 

without providing measurable additional protection of USDWs. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be
appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment.

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21753

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: BP urges EPA to adopt the performance standard that EPA considered in its 

review. EPA considered three options: (1) fixed period; (2) performance 

standard; and (3) combination of fixed period and performance standard; EPA 

states it adopted the latter approach. (73 Fed. Reg. at 43519.) While the 

Proposed Rule allows a Director to reduce the 50-year minimum (§146.93(b)(2)), 

the practical effect will be the 50-year timeframe applies unless an operator is 

able to overcome the presumption built into the Proposed Rule that 50 years is 

adequate. Indeed, this is more prescriptive than the requirement for Class I 

hazardous wells, which provides that the timeframe for post-injection site care 

ends when the plume has stabilized and cannot endanger USDWs. (Id.; 40 CFR 

§146.71.) 

Response: EPA agrees that some owners or operators will be able to demonstrate, in less than 50

years, that the pressure front and plume no longer pose a risk of endangerment to USDWs. However,

based on studies, EPA believes that the 50 year default time frame is warranted based on additional

review of research studies and reports and evaluation of public comments. 

EPA believes that the best way to address all possibilities, while ensuring USDW protection from

endangerment, is to set a 50 year default post-injection site care timeframe, with flexibility to: (1)

allow the Director discretion to shorten or lengthen the PISC timeframe during the PISC period

based on site-specific data, pursuant to requirements at §146.93(b); or (2) afford the Director

discretion to allow a Class VI well owner or operator to demonstrate, based on substantial data

during the permitting process, that an alternative PISC timeframe may be appropriate if it ensures

non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust
the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Brian Williams Letter ID: 0225

Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21754

Comment: EPA should adopt the performance-based standard that it considered previously. 

Accordingly, the post-injection site care period ends when monitoring and other 

site-specific data demonstrate that the geologic sequestration project does not 

pose an endangerment to USDWs. (See e.g., 73 Fed. Reg. 43520.) A 

performancebased approach is consistent with technical knowledge and historic 

industry experience. The site closure period would be appropriately based on 

particular site characteristics and historic site performance. For example, a 

well-selected and managed sequestration site (such as an existing oil or gas 

field) that has met its performance objectives (including plume stabilization) 

will be much more secure and could be closed reasonably quickly (potentially, in 

as few as 2-3 years). At other sites that are less well confined (e.g., deep 

saline formation without a conventional 4-way closure), the CO2 could move 

around for some time even after injection ceases before stabilizing, and might 

therefore require a longer period to allow for additional residual and 

solubility trapping. 

In summary, BP recommends that EPA adopt a performance-based approach to 

determine the timeframe for site closure. We also support the site closure 

standard offered in the MSDG Proposal for section 146.93(b), which sets forth 

detailed criteria that must be satisfied to demonstrate that the site does not 

pose an endangerment to USDWs. The advantage of the MSDG Proposal as opposed to 

a fixed period is it establishes clear criteria that an operator must 

demonstrate before obtaining site closure based upon particular site 

characteristics and is, therefore, reasonable applicable to any storage site as 

opposed to a standard based upon a fixed-duration. The current proposal of 50- 

years minimum, even subject to potential reduction, would result in 

significantly discouraging the deployment of this technology at commercial scale 

without providing measurable additional protection of USDWs. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care
timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose of

the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs

from endangerment.

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 23998

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

language; 5300 2.8.3 Site closure activities (40 CFR 146.93) 

Comment: 3. Schlumberger does not support the default post injection site care period of 

50 years. We feel that because the characterization and operation of the site 

will be based on the specific attributes of the site that the length of post 

injection site care should also be site specific information. In particular the 

criteria for ending the PISC period should be based on site performance and 

risk. We support the idea that the director approves final site closure. We 

suggest the following language for Section 146.93(b)(1): 

(1) The owner or operator shall continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site 

closure plan, pursuant to the performance based criteria described in 

146.93(b)(3). 

We suggest the following language for section 146.93(b)(2) 

(2) If the owner or operator can demonstrate to the satisfaction of the 

Director that the geologic sequestration project no longer poses an 

endangerment to USDWs, the Director may approve an amendment to the 

post- injection site care and site closure plan to reduce the 

frequency of monitoring or may authorize site closure. 

And we suggest the following language for section 146.93(b)(3) 

(3) Prior to authorization for site closure, the owner or operator must 

demonstrate to the Director, based on monitoring and other sitespecific data that no additional monitoring is needed to assure that 

the geologic sequestration project does not pose an endangerment to 

USDWs, considering the following:. 

(i) the estimated magnitude and extent of the AOR based on measurements 
and modeling; (ii) that CO2 movement and pressure changes match model 

predictions, (iii) the estimated location of the detectable CO2 plume 

based on measurement and modeling (measuring magnitude of saturation 

within the plume or mapping the edge of it); (iv) that there is no 

evidence of significant leakage of either CO2 or formation fluids that 

endanger USDWs; (v) that the CO2 plume and displaced formation fluid are 

not expected to migrate in the future in a manner that encounters a 

potential leakage pathway; and, (vi) that wells at the site are not 

leaking and have maintained integrity. 

Response: The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a

combination of a fixed timeframe and a performance standard approach. EPA believes that a default

PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this timeframe,

combined with a site-specific Director’s discretion to create an alternative PISC time frame, ensures

that USDWs are protected. The GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA expects that the Director would consider the types of information the commenter describes in

determining whether the plume and pressure front no longer pose a risk of endangerment to USDWs

and post-injection site care monitoring may be discontinued. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24071

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: §146.93 Post-injection site care and site closure. 
Proposed Rule: (1) The owner or operator shall continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site closure 

plan for at least 50 years following the cessation of injection. At the 

Director’s discretion, the monitoring will continue until the geologic 

sequestration project no longer poses an endangerment to USDWs. 

Schlumberger Suggested Revision: (1) The owner or operator shall continue to 

conduct monitoring as specified in the Director-approved post-injection site 

care and site closure plan, pursuant to the performance based criteria described 

in 146.93(3). 

Schlumberger Rationale: The 50 year default period is not based on any 

scientific or technical information and could be considered arbitrary and 

capricious. 

Proposed Rule: (2) If the owner or operator can demonstrate to the satisfaction 

of the Director before 50 years, based on monitoring and other site-specific 

data, that the geologic sequestration project no longer poses an endangerment to 

USDWs, the Director may approve an amendment to the post-injection site care and 

site closure plan to reduce the frequency of monitoring or may authorize site 

closure before the end of the 50-year period. 

Schlumberger Suggested Revision: (2) If the owner or operator can demonstrate to 

the satisfaction of the Director that the geologic sequestration project no 

longer poses an endangerment to USDWs, the Director may approve an amendment to 

the post- injection site care and site closure plan to reduce the frequency of 

monitoring or may authorize site closure. 

Schlumberger Rationale: - 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive in most

cases or is arbitrary and capricious. EPA proposed a default post-injection site care timeframe of 50

years based on a review of research studies, industry reports, and existing environmental programs.

This analysis was included in an EPA-prepared background document that is available in the federal

docket, titled "Computational Modeling of Underground Injection of Carbon Dioxide for

Determination of Area-of-Review and Potential Risk to Underground Sources of Drinking Water."

EPA assessed various default timeframes based on additional review of research studies and

evaluation of public comments. While numerous commenters suggested that EPA shorten the

monitoring timeframe, none of the commenters provided sufficient data or other evidence to warrant

a change in the proposed timeframe. While the 10- or 30-year timeframe suggested by some of these

commenters may be within the timeframe suggested in some studies, EPA believes that the potential

risks of endangering USDWs will likely not decline within these timeframes and available data,

including data submitted by commenters, do not support a different default timeframe. However,

EPA recognizes that alternative timeframes may be appropriate under limited, specific

circumstances.

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during
the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24970

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

language 

Comment: Proposed Rule: (4) If such a demonstration cannot be made (i.e., if the carbon 

dioxide plume and pressure front have not stabilized) after the 50 year period, 

the owner or operator must submit to the Director a plan to continue postinjection site care. 

Schlumberger Suggested Revision: Delete 

Schlumberger Rationale: No longer necessary 

Response: As described above, EPA believes that a default post-injection site care timeframe of 50

years, with allowance of Director's discretion to shorten or lengthen this timeframe or approve an

alternative PISC timeframe, is appropriate to ensure that USDWs are protected, while accounting for

the variety of site-specific circumstances that may come in to play at GS sites. EPA expects that the

Director would consider the types of information the commenter describes in determining whether

the plume and pressure front no longer pose a risk of endangerment to USDWs and post-injection

site care monitoring may be discontinued.

Commenter Name: Philip Papadeas Letter ID: 0238
Commenter Organization: Sandia Technologies, LLC Comment ID: 23359

Comment: UIC Class I wells. Monitoring should continue only to the point when pressure 

dissipates to below minimum driving force pressures required to move fluid to a 

USDW. 

Response: EPA agrees that determinations about when post-injection site monitoring may be

discontinued will be based on pressure observations. However, EPA clarifies that the nonendangerment demonstration should address more than changes in pressure; for example, fluid

movement within the subsurface must also be considered. EPA expects that the Director would

consider the types of information the commenter describes in determining whether the plume and

pressure front no longer pose a risk of endangerment to USDWs and post-injection site care

monitoring may be discontinued. 

Under the combined fixed timeframe and performance standard approach for Class VI wells, the

post-injection site care timeframe may be reduced by the Director if the owner or operator can

demonstrate that the remaining pressure front and plume no longer pose a risk of endangerment to

USDWs. The non-endangerment finding is left to the discretion of the Director, based on sitespecific information such as plume movement, pressure decay, and the location of potential leakage

pathways. 

EPA adds that the final GS rule at §146.93(c), also allows the Director to approve an alternative

post-injection site care timeframe where an owner or operator can demonstrate during the permitting

process that an alternative post-injection site care timeframe, other than the 50 year default, is

appropriate and ensures non-endangerment of USDWs. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23261

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: 38. EPA is proposing using a combination of fixed timeframe and a performance 

standard as described above. EPA is tentatively proposing a post-injection site 

care (monitoring) period of 50 years with Director’s discretion to change that 

period to lengthen or shorten the 50-year period if appropriate. EPA requests 

comment on the proposed use of a tentative 50-year fixed timeframe that could be 

modified at the Director’s discretion based on monitoring and modeling data. EPA 

Notice 43519. 

A performance-based time period is appropriate rather than a fixed timeframe. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50
years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23262

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: 39. EPA is requesting comments on the proposed requirements for well plugging, 

post-injection site care, and site closure, including the proposed requirements 

for the post-injection time period. EPA Notice 43520. 

A performance-based time period is appropriate rather than a fixed timeframe. 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial
data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Mark Bohrer Letter ID: 0241

Commenter Organization: North Dakota Industrial Commission Comment ID: 23263

Comment: 40. In addition, EPA seeks comment on whether the Director should be allowed to 

shorten the timeframe based on performance information, and whether EPA should 

require a shorter or longer post injection period if data suggests the time 

frame should be adjusted. EPA Notice 43520. 

A performance-based time period is appropriate rather than a fixed timeframe. 

Response: The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a

combination of a fixed timeframe and a performance standard approach. EPA believes that a default

PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this timeframe,

combined with a site-specific Director’s discretion to create an alternative PISC time frame, ensures

that USDWs are protected. The GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24946

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b) 

EPA Proposal: (2) If the owner or operator can demonstrate to the satisfaction 

of the Director before 50 years, based on monitoring and other site-specific 
data, that the geologic sequestration project no longer poses an endangerment to 

USDWs, the Director may approve an amendment to the post-injection site care and 

site closure plan to reduce the frequency of monitoring or may authorize site 

closure before the end of the 50-year period. 

GWPC Recommendations: (2) The owner or operator can request and demonstrate to 

the satisfaction of the Director that the post-injection site care and site 

closure plan should be revised to reduce the frequency of monitoring. 

Rationale: See above regarding elimination of 50-year presumptive time period. 

Response: As described above, EPA disagrees that a post-injection site care timeframe of 50 years is

excessive for most Class VI wells. However, EPA agrees that there will be circumstances where it

can be demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24948

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: EPA Proposal: (4) If such a demonstration cannot be made (i.e., if the carbon 

dioxide plume and pressure front have not stabilized) after the 50-year period, 

the owner or operator must submit to the Director a plan to continue postinjection site care. 

GWPC Recommendations: Delete 

Rationale: No longer necessary if 50 year time period is removed. 

Response: As described above, EPA believes that, to ensure USDW protection from endangerment,

a default timeframe for post-injection site care is necessary in most cases. A 50 year post-injection

site care timeframe represents a reasonable and protective monitoring period for most GS sites based

on a review of research studies, industry reports, and existing environmental programs, and

evaluation of public comments.
EPA believes that a 50-year default post-injection site care timeframe, as required at §146.93(b)(1),

is not overly burdensome, does not exaggerate the risks associated with GS, is consistent with other

environmental programs, and sufficiently protects USDWs from endangerment.

Letter ID: 0263

Commenter Organization: Interstate Oil & Gas Compact Commission Comment ID: 22825

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

00. EPA requests comment on the proposed use of a tentative 50-year fixed timeframe 

that could be modified at the Director's discretion based on monitoring and 

modeling data. 

IOGCC Response: Given that current injection and reservoir behavior data 

demonstrates a decreasing risk of leakage after injection ceases, the IOGCC has 

concluded that a 50 year fixed timeframe is both unnecessary and too long. What 

is absolutely critical here is that the Director has discretion to increase or 

decrease the period based on the specifics of a particular project. In the view 

of the IOGCC, it would be better to prescribe a shorter period with discretion to 

go longer, rather than vice versa, as such would better facilitate project 

planning. 

III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

PP. EPA is requesting comments on the proposed requirements for well plugging, 

post-injection site care, and site closure, including the proposed requirements 

for the post-injection time period. 

IOGCC Response: Given documented evidence to date that there is a decreasing risk 

of leakage after injection ceases, The IOGCC has concluded that a 50 year fixed 

timeframe is both unnecessary and too long. What is absolutely critical here is 

that there be Director discretion to increase or decrease the period based on 

the specifics of a particular project. In the view of the IOGCC, it would be 

better to prescribe a shorter period with discretion to go longer, rather than 

vice versa, as such would better facilitate project planning. 

III A. 8 Proposed Well Plugging, Post-Injection site Care, and Site Closure 

Requirements 

QQ. In addition, EPA seeks comment on whether the Director should be allowed to 

shorten the timeframe based on performance information, and whether EPA should 

require a shorter or longer post-injection period if data suggests the time frame 

should be adjusted. 

IOGCC Response: Given documented evidence to date that there is a decreasing risk 

of leakage after injection ceases, The IOGCC has concluded that a 50 year fixed 
timeframe is both unnecessary and too long. What is absolutely critical here is 

that there be Director discretion to increase or decrease the period based on 

the specifics of a particular project. In the view of the IOGCC, it would be 

better to prescribe a shorter period with discretion to go longer, rather than 

vice versa, as such would better facilitate project planning. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive or

unnecessary for most GS sites. EPA proposed a default post-injection site care timeframe of 50 years

based on a review of research studies, industry reports, and existing environmental programs. This

analysis was included in an EPA-prepared background document that is available in the federal

docket, titled "Computational Modeling of Underground Injection of Carbon Dioxide for

Determination of Area-of-Review and Potential Risk to Underground Sources of Drinking Water."

EPA assessed various default timeframes based on additional review of research studies and

evaluation of public comments. While numerous commenters suggested that EPA shorten the

monitoring timeframe, none of the commenters provided sufficient data or other evidence to warrant

a change in the proposed timeframe. While the 10- or 30-year timeframe suggested by some of these

commenters may be within the timeframe suggested in some studies, EPA believes that the potential

risks of endangering USDWs will likely not decline within these timeframes and available data,

including data submitted by commenters, do not support a different default timeframe. However,

EPA recognizes that alternative timeframes may be appropriate under limited, specific

circumstances. 

For this reason, the GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

Commenter Name: Michael Moore Letter ID: 0265

Commenter Organization: North American Carbon Capture & Storage

Association (NACCSA)

Comment ID:

22854

Comment: - Closure and Post-Injection Site Care: NACCSA urges the Agency to adopt 

a shorter default time period than the 50 year period currently proposed. 

Although a fair amount of certainty may be achieved through setting some default 
period of time for the post-injection site care period, the proposed 50 year 

default is both arbitrary and unjustifiably long. Further, while NACCSA supports 

the concept of a performance-based component, the rules should include specific 

and appropriate circumstances that the program director will consider in 

exercising any discretion in this regard. 

Response: EPA disagrees that a post-injection site care timeframe of 50 years is excessive for most

Class VI wells. EPA proposed a default post-injection site care timeframe of 50 years based on a

review of research studies, industry reports, and existing environmental programs. This analysis was

included in an EPA-prepared background document that is available in the federal docket, titled

Computational Modeling of Underground Injection of Carbon Dioxide for Determination of Areaof-Review and Potential Risk to Underground Sources of Drinking Water. EPA assessed various

default timeframes based on additional review of research studies and evaluation of public

comments. While numerous commenters suggested that EPA shorten the monitoring timeframe,

none of the commenters provided sufficient data or other evidence to warrant a change in the

proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters

may be within the timeframe suggested in some studies, EPA believes that the potential risks of

endangering USDWs will likely not decline within these timeframes and available data, including

data submitted by commenters, do not support a different default timeframe. However, EPA

recognizes that alternative timeframes may be appropriate under limited, specific circumstances,

which is why EPA is providing the Director discretion to approve an alternative post-injection site

care timeframe as long as the owner or operator can meet the requirements provided at §146.93(c).

EPA acknowledges there will be circumstances where it can be demonstrated in less than 50 years

that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this reason,

the GS rule offers owners or operators flexibility regarding the duration of the PISC timeframe by:

(1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the postinjection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the

permitting process based on substantial data, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters¿ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist

Directors in evaluating proposed well plugging plans and post-injection site care and site closure

plans under 146.92 and 146.93. The guidance describes recommended approaches for how an owner
or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Michael Moore Letter ID: 0265

Commenter Organization: North American Carbon Capture & Storage

Association (NACCSA)

Comment ID:

22868

Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards); 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: NACCSA urges the Agency to adopt a performance-based approach more in keeping 

with the actual risks posed by CCS projects. NACCSA believes that the site specific 

nature of CO2 storage projects will require each project to be judged on its own 

merit. If a project can show, at any time after the cessation of injection, that 

there is sufficiently small risk of endangerment to USDWs, monitoring should no 

longer be required. Given that under the proposed rule, the program director would 

retain discretion to lengthen or shorten the PISC period as necessary to protect 

USDWs, a performance based approach is in keeping with the spirit of the draft 

rule. Furthermore, performance based approach is more in keeping with the 

realty of potential risks associated with CO2 storage would minimize 

disincentivization of CCS projects while providing an equivalent degree 

of protection for USDWs. NACCSA believes that the performance-based approach, 

currently proposed by EPA as an element of the rule, would be beneficial to 

project operators and investors and for the protection of USDWs. The final rule 

should include specific and appropriate circumstances that the program director 

will consider in exercising discretion in this regard, so that project operators 

and investors have a clear idea of the bar they will be required to meet in order 

to close out the PISC period. 

Response: As described above, EPA agrees that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Kevin Frederick Letter ID: 0525
Commenter Organization: Wyoming Department of Environmental Quality Comment ID: 21397

Comment: We agree that the directors should be provided discretion to shorten or lengthen 

the proposed post injection site care monitoring period based on performance 

information. 

Response: EPA agrees that the Director should have discretion to shorten or lengthen the postinjection site care monitoring period, and has retained this provision in the final GS rule at

146.93(b)(2). EPA adds that the final rule at §146.93(c), also allows the Director to approve an

alternative post-injection site care timeframe where an owner or operator can demonstrate during the

permitting process that an alternative post-injection site care timeframe, other than the 50 year

default, is appropriate and ensures non-endangerment of USDWs.

Because of the variety of site-specific circumstances at GS sites, EPA believes that individual UIC

Directors, in consultation with operators, will be in the best position to determine whether additional

post-injection site care monitoring is needed (or whether the timeframe may be shortened) or

whether an alternative PISC timeframe is appropriate, based on the circumstances of a particular

project. EPA expects this decision to be made based on relevant site data and in consultation with all

potentially impacted parties.

Commenter Name: Cynthia Lane Letter ID: 0528

Commenter Organization: American Water Works Association (AWWA) Comment ID: 21390

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: Finally, AWWA supports the rule requirement for the fifty year period for post 

injection site care. However, we suggest that it be set at a fifty year minimum 

with no discretion to shorten. Given the potential scope of carbon 

sequestration, this will provide for consistent approach across the U.S., 

provide strong long term protective measures of USDW's. 

In conclusion, AWWA is concerned that the proposed large scale sequestration of 

carbon dioxide in underground aquifers may have a significant impact on the 

public, the environment and drinking water utilities. We are also concerned that 

Response: EPA agrees that a 50 year post-injection site care timeframe represents a reasonable and

protective post-injection site monitoring period for most projects and available data, including data

submitted by commenters, do not support a different default timeframe. EPA bases this on a review

of research studies, industry reports, and existing environmental programs, and evaluation of public

comments. Furthermore, EPA believes that a 50-year default post-injection site care timeframe is not

overly burdensome, does not exaggerate the risks associated with GS, is consistent with other

environmental programs, and sufficiently protects USDWs from endangerment. For this reason, the

final GS regulation retains the 50 year post-injection site care timeframe, as specified in

§146.93(b)(1).

However, EPA disagrees that a 50 year post-injection site care timeframe should be an absolute

minimum. Rather, EPA believes, as some commenters suggest, that there will be circumstances

where it can be demonstrated in less than 50 years that the plume and pressure front no longer pose a

risk of endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to
requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Doug Louis Letter ID: 0530

Commenter Organization: Kansas Corporation Commission Comment ID: 21347

Comment: Proposed well plugging post injection site care and site closure requirements. 

The proposed rule sets the post injection site care period at a default period 

of fifty years. KCC agrees that the UIC program director should have the 

authority to shorten or lengthen the post injection site care period if the 

owner/operator demonstrates a different time period is appropriate. 

Response: EPA agrees that the Director should have discretion to shorten or lengthen the postinjection site care monitoring period, and has retained this provision in the final GS rule at

146.93(b)(2). EPA adds that the final rule at §146.93(c), also allows the Director to approve an

alternative post-injection site care timeframe where an owner or operator can demonstrate during the

permitting process that an alternative post-injection site care timeframe, other than the 50 year

default, is appropriate and ensures non-endangerment of USDWs.

Because of the variety of site-specific circumstances at GS sites, EPA believes that individual UIC

Directors, in consultation with operators, will be in the best position to determine whether additional

post-injection site care monitoring is needed (or whether the timeframe may be shortened) or

whether an alternative PISC timeframe is appropriate, based on the circumstances of a particular

project. EPA expects this decision to be made based on relevant site data and in consultation with all

potentially impacted parties.

Commenter Name: George Peridas Letter ID: 0534

Commenter Organization: Natural Resources Defense Council (NRDC) Comment ID: 21458

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: The closure standards I agree with Scott, I do not think that fifty years is 

arbitrary. I do not think that it is the magic number or that it will be 

appropriate for every single site. Nonetheless, I think it is a good benchmark, 

but we do need to have other flexibility to revise this upwards or downwards as 
project data comes in. 

I think what needs a little bit of refinement is the phrase at the discretion of 

the administrator. I think that should be some more concrete criteria as to when 

the administrator should reserve the rights to require certain techniques to be 

used on other requirements in the rule. 

Response: EPA agrees that the Director should have discretion to shorten or lengthen the postinjection site care monitoring period, and has retained this provision in the final GS rule at

146.93(b)(2). The GS rule offers owners or operators flexibility regarding the duration of the PISC

timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during

the post-injection period based on site-specific data, pursuant to requirements at §146.93(b); or (2)

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, during

the permitting process based on substantial data, that an alternative PISC timeframe may be

appropriate if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

Because of the variety of site-specific circumstances at GS sites, EPA believes that individual UIC

Directors, in consultation with operators, will be in the best position to determine whether additional

post-injection site care monitoring is needed (or whether the timeframe may be shortened), based on

the circumstances of a particular project. EPA expects this decision to be made based on relevant

site data and in consultation with all potentially impacted parties. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

EPA is using an adaptive approach to regulate GS injection. The Agency plans, every six years, to

collect and review data on GS projects to determine whether the appropriate amount and types of

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

the requirements are appropriate or necessary.

Comment Code: 5280 2.8.2.4 USDW non-endangerment demonstrations 

Individual Comments
Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24803

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

language 

Comment: (3) Prior to authorization for site closure, must submit to the Director a 

demonstration, based on monitoring and other site-specific data, that the 

carbon dioxide plume and pressure front have stabilized and that no 

additional monitoring is needed to assure that the GS project does not pose an 

endangerment to USDWs. 

{The carbon dioxide plume will continue to move with other formation fluids - 

they are never static. The real test should be whether or not the pressure has 

dissipated and the pressure front stabilized to the point that there is no 

threat of endangering USDWs.} 

Response: EPA did not make the suggested change. EPA agrees that a complete cessation of plume

movement may not occur at some sites for long time periods due to density differences, natural

formation flow gradients and diffusion. EPA clarifies that a complete cessation of plume movement

is not required, only a demonstration that the plume and pressure front no longer pose a risk of

endangerment to USDWs. 

EPA acknowledges that many site-specific factors will influence the determination of when the CO2

plume and pressure front no longer pose a risk of endangerment to USDWs. It is for this reason that

EPA believes that individual UIC Directors, in consultation with operators, will be in the best

position to determine whether additional post-injection site care is needed. EPA expects this decision

to be made based on relevant site data and in consultation with all potentially impacted parties. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22650

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and

post-injection site care 

Comment: o Page 43517. Records retention of only 3 years after site closure. That seems 

incredibly short. Also it is not clear how this requirement to hold on to these 

data for three years after site closure is consistent with the owner operators 

requirement to discharge its responsibilities under the post closure period 

including establishing that non-endangerment continues to be the case. Wouldn’t 

access to baseline and data collected during the period of principal operations 

be needed to report out these findings during the period of post closure. This 

short record retention period also seems to undercut assertion of a open 

continuous dialogue being a center piece of how USEPA and any states that have 
Class VI primacy will ensure public safety. 

Response: EPA has changed the recordkeeping requirement in the final rule to require that owners

or operators retain records collected during the post-injection site care period for at least 10 years

following site closure. EPA believes that the requirements that the owner or operator retain for ten

years following site closure, records collected during the post-injection site care period at §146.93(f)

and §146.93(h) are appropriate to ensure that data are available to support non-endangerment

demonstrations and to address any concerns that may arise following site closure. This data will also

support EPA's review of project data as part of the adaptive rulemaking approach.

Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22665

Other EPA Comment Codes and Descriptions: 1360 1.1.3.4 Effectiveness of trapping mechanisms

Comment: - Page 43519. Consider explicitly referencing the work laid out by Benson to 

support the statement that physical and geochemical trapping mechanisms will 

help to improve the integrity of storage as time moves forward. This is a 

critically important "but widely misunderstood" point about how GS will work 

in practice. It would be good to include at least one citation to technical 

work to back up this point. 

o OTC 19244. Multi-Phase Flow and Trapping of CO2 in Saline Aquifers. Sally M. 

Benson, SPE, Stanford University. Copyright 2008, Offshore Technology Conference 

This paper was prepared for presentation at the 2008 Offshore Technology 

Conference held in Houston, Texas, U.S.A., 5-8 May 2008. 

Response: EPA added the Benson study to the final rule preamble (and has made it available in the

rulemaking docket).

Commenter Name: Michael J. Miller Letter ID: 0168

Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22511

Other EPA Comment Codes and Descriptions: 5260 2.8.2.3 Adjusting the post-injection

timeframe (seeking comment) 

Comment: Preamble, page 43520: "Once the owners or operators provide documentation that 

demonstrates that the models predicting CO2 movement are consistent with 

monitoring results and that there are no longer risks of endangerment to USDWs, 

they could request that the Director authorize site closure. EPA is also 

proposing to allow the Director to shorten or lengthen the 50-year time frame 

based on performance of the site... EPA wishes to emphasize that site closure 

cannot occur until monitoring and modeling data establish to the Director’s 

satisfaction that potential risks of endangerment to USDWs have ceased." 

EPRI COMMENT #18: EPA’s requirement for demonstrating plume stability for site 

closure is based on the ability to both observe and successfully model the speed 

and stability of the advancing CO2 front, a very discrete boundary that is 

difficult to define, model accurately when complex reservoir heterogeneity and 

fast flow pathways are present, and measure in the field on a large scale. (See 
also EPRI’s comment #2 on defining the front). If remote methods like surface 

seismic, cross-well seismic or gravity are not successful in tracking front 

position, and CO2 is never directly detected in sentinel observations wells, 

then model validation based on CO2 front position may be questioned. In such a 

case, if the model predicts the continued advance of the CO2 front while the 

observed data do not, the EPA Director may not be satisfied with the absence of 

a potential risk of endangerment to USDWs and may unnecessarily delay site 

closure for decades. EPRI recommends that the final rule contain alternative 

provisions for site closure if model validation is unsuccessful. 

Response: EPA acknowledges that many site-specific factors will influence the determination of

when the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for

this reason that EPA believes that individual UIC Directors, in consultation with operators, will be in

the best position to determine whether additional post-injection site care is needed. EPA expects this

decision to be made based on relevant site data and in consultation with all potentially impacted

parties. 

EPA also agrees that a complete cessation of plume movement may not occur at some sites for long

time periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies

that a complete cessation of plume movement is not required, only a demonstration that the plume

and pressure front no longer pose a risk of endangerment to USDWs. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24123

Comment: factors, and relative risk of the project. Clear guidelines also need to be 

established regarding when operators have met the performance standards that 

determine site closure. Specifically, the standard that the project no longer 

poses an endangerment to USDWs needs to be defined using reasonable risk-based 

criteria. 

Response: EPA believes that many site-specific factors will influence the determination of when the

CO2 plume and pressure front no longer pose a risk of endangerment to USDWs, and therefore is

not defining the criteria in the final rule. It is for this reason that EPA believes that individual UIC

Directors, in consultation with operators, will be in the best position to determine whether additional

post-injection site care is needed. EPA expects this decision to be made based on relevant site data

and in consultation with all potentially impacted parties. 

The post-injection site care requirements in the final GS rule incorporate a combination of a fixed

timeframe and a performance standard approach. The final GS rule offer owners or operators

flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to

shorten or lengthen the PISC timeframe during the post-injection period based on site-specific data,
pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI

well owner or operator to demonstrate, during the permitting process based on substantial data, that

an alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs

pursuant to requirements at §146.93(c).

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist

Directors in evaluating proposed well plugging plans and post-injection site care and site closure

plans under 146.92 and 146.93. The guidance describes recommended approaches for how an owner

or operator could plug injection and monitoring wells; demonstrate the appropriateness of an

alternative post-injection site care time frame; perform post-injection monitoring; demonstrate non

endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24207

Comment: API, in concert with the MSDG, recommends the standard in the proposed 

alternative language for section 146.93(b) below because it sets forth detailed 

criteria, all of which must be satisfied, to demonstrate that the site does not 

pose an endangerment to USDWs. The specific criteria listed in our proposal will 

serve to provide the Director with the requisite information to make the 

appropriate determination. The advantage of this approach is that it establishes 

clear criteria that an operator must demonstrate before obtaining site closure 

based upon particular site characteristics and is, therefore, reasonably 

applicable to any storage site as opposed to a standard based upon a 

fixedduration. Furthermore, it is more stringent than a purely discretionary 

approach because it establishes specific criteria that must be shown before site 

closure may be granted. We believe this language, which is an extension of work 

done by the World Resources Institute and the Ground Water Protection Council, 

avoids the noted shortcomings and provides stronger protection for USDWs. 

Response: EPA believes that many site-specific factors will influence the determination of when the

CO2 plume and pressure front no longer pose a risk of endangerment to USDWs, and therefore is

not defining the criteria in the final rule. It is for this reason that EPA believes that individual UIC

Directors, in consultation with operators, will be in the best position to determine whether additional

post-injection site care is needed. EPA expects this decision to be made based on relevant site data

and in consultation with all potentially impacted parties. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells, perform post-injection monitoring,

demonstrate non-endangerment, and perform site closure activities. The guidance will be available at

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

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24208

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

Comment: Rule Provision: 146.93(b)(3) 

API Comments: (3) Prior to authorization for site closure, the owner or operator 

MUST submit to the Director a demonstration, DEMONSTRATE TO THE DIRECTOR, 

based on monitoring, and other site-specific data, AND MODELING THAT IS 

REASONABLY CONSISTENT WITH SITE PERFORMANCE that the carbon dioxide plume and 

pressure front have stabilized and that no additional monitoring is needed to 

assure that the geologic sequestration project does not AND IS NOT EXPECTED TO 

pose an endangerment to USDWs. THE DIRECTOR SHALL APPROVE CLOSURE IF THE

OWNER 

OR OPERATOR DEMONSTRATES, BASED ON THE CURRENT UNDERSTANDING OF THE

SITE, 

INCLUDING MONITORING DATA AND/OR MODELING, ALL OF THE FOLLOWING: (I)

THE 

ESTIMATED MAGNITUDE AND EXTENT OF THE PROJECT FOOTPRINT (CO2 PLUME

AND THE AREA 

OF ELEVATED PRESSURE), (II) THE ESTIMATED LOCATION OF THE DETECTABLE CO2

PLUME; 

(III) THAT THERE IS NO SIGNIFICANT LEAKAGE OF EITHER CO2 OR DISPLACED

FORMATION 

FLUIDS THAT IS ENDANGERING USDWS; (IV) THAT THE INJECTED OR DISPLACED

FLUIDS ARE 

NOT EXPECTED TO MIGRATE IN THE FUTURE IN A MANNER THAT ENCOUNTERS A

POTENTIAL 

LEAKAGE PATHWAY INTO A USDW; (V) THAT THE INJECTION WELLS AT THE SITE

COMPLETED 

INTO OR THROUGH THE INJECTION ZONE OR CONFINING ZONE ARE PLUGGED AND

ABANDONED 

IN ACCORDANCE WITH THESE REQUIREMENTS; AND (VI) ANY REMAINING PROJECT

MONITORING 

WELLS AT THE SITE ARE BEING MANAGED BY A PERSON AND IN A MANNER

ACCEPTABLE TO 

THE DIRECTOR. 

Rationale: API edits establish the performance based criteria for selecting the 

monitoring period. EPA should recognize that under any given set of site 

specific conditions some of these criteria may not be fully satisfied. EPA 

should retain the ability to waive individual monitoring criteria described here 

to reflect that situation. 

Rule Provision: 146.93(b)(4) 

API Comments: (4) If such a demonstration cannot be made (i.e., if the carbon 

dioxide plume and pressure front have not stabilized) after the 50-year period, 

the owner or operator must submit to the Director a plan to continue postinjection site care.

Rationale: No longer necessary given changes above. 
Response: EPA disagrees that the rule should specify the criteria for setting the monitoring

timeframe. Instead, EPA believes that such determinations are site-specific and should be described

in a project specific post-injection site care and site closure plan. EPA also believes that periodic

reviews and updates, where necessary, to the plan are important to ensuring that the site continues to

be managed effectively and to determine whether shortening the monitoring timeframe is

appropriate. The post-injection site care requirements in the final GS rule incorporate a combination

of a fixed timeframe and a performance standard approach. The final GS rule offer owners or

operators flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director

discretion to shorten or lengthen the PISC timeframe during the post-injection period based on sitespecific data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to

allow a Class VI well owner or operator to demonstrate, during the permitting process based on

substantial data, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells, perform post-injection monitoring,

demonstrate the appropriateness of an alternative post-injection site care time frame, demonstrate

non-endangerment, and perform site closure activities. The guidance will be available at

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

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23706

Other EPA Comment Codes and Descriptions: 5220 2.8.2.1 Post-injection monitoring activities 

Comment: AWWA has observed that the proposed regulation is lacking in details on the 

requirements to demonstrate that the carbon dioxide plume has stabilized. For 

example, the proposal does not include requirements that the plume pressure must 

be constant for a certain number of years or that the plume has not migrated for 

a set period of time. Since AWWA does not claim to be experts on the behavior of 

carbon dioxide plumes and can not provide recommendations on this topic, AWWA 

recommends that EPA should engage in research on determining exactly what these 

criteria should be. For example, when referencing lack of plume movement, what 

should the trigger time period be (no movement of plume for 10, 15, 20 or more 

years??). AWWA recommends that EPA clarify what is an acceptable frequency for a 

lack of change in the plume characteristics and also needs to clarify plume 

stabilization as this issue could be interpreted differently by different 

states. Guidance should be prepared by EPA on this topic so that there is 

consistent application of this requirement across all sequestration projects. A 

performance based system could also be developed that would require the operator 

to meet certain criteria to prove that the plume has stabilized. This could be 

used to justify the closing of the site after the 50-year period of post- 
injection site care has elapsed. This would allow for a process where long-term 

monitoring decisions are made in response to the specific characteristics of 

each project. 

AWWA believes that the proposed post-injection site care requirements have been 

established to prevent endangerment to USDWs. Carbon dioxide can potentially 

leak from the confining layer into other aquifers that, while not classified as 

USDWs, may still be considered drinking water sources in some areas of the 

county. EPA should also consider including requirements in the regulation to 

address the potential for endangerment of these aquifers during the postinjection period. Monitoring requirements should be extended to cover these 

aquifers, and the post-injection site care plan should include provisions for 

the protection of aquifers that are not classified as USDWs, but are still 

considered a future drinking water source. 

Response: EPA acknowledges that many site-specific factors will influence the determination of

when the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for

this reason that EPA believes that individual UIC Directors, in consultation with operators, will be in

the best position to determine whether additional post-injection site care is needed. EPA expects this

decision to be made based on relevant site data and in consultation with all potentially impacted

parties. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

EPA has conducted research regarding stabilization timeframes. As described in the preamble to the

proposed rule, in determining the post-injection site care-timeframe for the proposed regulation, EPA

reviewed industry reports, existing environmental programs, and initial GS research studies. EPA

provided a synthesis of pertinent results from GS modeling studies in the preamble to the proposed

regulation. Further explanation of this analysis was included in an EPA-prepared background

document that is available in the federal docket, titled "Computational Modeling of Underground

Injection of Carbon Dioxide for Determination of Area-of-Review and Potential Risk to

Underground Sources of Drinking Water." Based on review of these studies, modeling results

indicate that the CO2 plume stabilization may occur on the timeframe of 10-100 years after the

cessation of injection. EPA believes that a 50-year default post-injection site care timeframe is a

reasonable midpoint for most GS projects and available data, including data submitted by

commenters, do not support a different default timeframe, and has retained this in the final

regulation. EPA will continue research in this area and plans, every six years, to collect and review

data on GS projects to determine whether the appropriate amount and types of information and

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

are appropriate or necessary.

Commenter Name: Wendy Jacobs Letter ID: 0183
Commenter Organization: Harvard Law School Environmental Law and Policy

Center

Comment ID:

25145

Comment: EPA should, however, clarify the performance standard element by defining the

key term "stabilized" in the context of GS.[FN6] See 73 Fed. Reg. at 43,540-41

(proposed 40 C.F.R. § 146.93(b)(2)). It is unclear whether "stabilized" refers

to certain measurable physical properties of the "carbon dioxide plume and

pressure front" (such as pressure), or broadly describes some macro-state (for

example, no movement of the CO2 over a specified period of time) that EPA is

using as a proxy for USDW safety, or something else. EPA has promulgated more

specific closure and post-closure standards for Class I wells and should follow

suit here to avoid confusion, uncertainty, and potential threats to drinking

water supplies.

[FN6] The term "stabilize" is also used in existing regulations governing

surface impoundments under RCRA. See 40 C.F.R. § 264.228(a)(2)(ii) ("At closure,

the owner or operator must . . . stabilize remaining wastes to a bearing

capacity sufficient to support final cover . . . ."). Although the term is not

defined in those regulations either, those regulations do impose other specific

requirements on the owner or operator (e.g., cover the surface impoundment with

a final cover) that are measured in terms of specific factors like migration,

erosion, maintenance, and permeability. See 40 C.F.R. § 264.228(a)(2)(iii)

(A)-(E).

The owner or operator of a Class I hazardous waste injection well must observe

and record "pressure decay" observations and show conformance to predicted

values before site closure will be authorized. 40 C.F.R. § 146.71(d). During

post-closure care, the owner or operator of a Class I well is required to

continue monitoring "until pressure in the injection zone decays to the point

that the well’s cone of influence no longer intersects the base of the lowermost

USDW." 40 C.F.R. § 146.72(b)(2). These standards provide more guidance than

does the proposed regulation.

ELPC and ETIP are sensitive to the numerous outstanding technical issues

surrounding wide-scale use of CCS technologies and the importance of

demonstration projects to solve many of those questions. Accordingly, while we

view the EPA’s undefined use of the term "stabilization" as problematic for a

closure standard, we are not prepared to recommend numerical monitoring targets

or reach the specificity of the Class I well regulations. Even so, there is

ample room for the EPA to adopt a stronger and better-defined post-injection

site care standard that gives greater assurances that USDWs will not be

threatened while still allowing flexibility for innovation.

The World Resources Institute (WRI) recommendations avoid explicit use of the

term "stabilization" and instead focus on the endangerment issue. Completion of

the WRI post-injection monitoring requirements occurs when the owner or operator

demonstrates "with a high degree of confidence that the storage project does not

endanger human health or the environment." SARAH M. FORBES ET AL., WORLD

RESOURCES INSTITUTE, CCS GUIDELINES: GUIDELINES FOR CARBON DIOXIDE

CAPTURE,
TRANSPORT, AND STORAGE 103 (2008) [hereinafter WRI GUIDELINES]. WRI suggests

that an owner or operator can make this demonstration by showing:

1.the estimated magnitude and extent of the project footprint (CO2 plume and the

area of elevated pressure), based on measurements and modeling;

2.that CO2 movement and pressure changes match model predictions; 

3.the estimated location of the detectable CO2 plume based on measurement and

modeling (measuring magnitude of saturation within the plume or mapping the edge

of it);

4.either (a) no evidence of significant leakage of injected or displaced fluids

into formations outside the confining zone, or (b) the integrity of the

confining zone;

5.that, based on the most recent geologic understanding of the site, including

monitoring data and modeling, the [CO2 plume and formation water] are not

expected to migrate in the future in a manner that encounters a potential

leakage pathway; and

6.that wells at the site are not leaking and have maintained integrity. 

Id. Requirements four, five, and six all address stabilization, but in language

more precise than the approach offered by EPA. Where EPA leaves open the

definition of "stabilize," WRI offers a more exacting standard built from terms

like "leakage," "integrity," and "migrate." The WRI approach provides a

standard more certain to ensure that non-endangerment is achieved while

preserving flexibility for owner or operators to develop best practices as CCS

continues to develop. In addition, WRI’s more specific closure standard is more

consistent with the models employed in existing EPA regulations for Class I

wells. See supra pp. 9-10.

Response: EPA acknowledges that many site-specific factors will influence the determination of

when the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for

this reason that EPA believes that individual UIC Directors, in consultation with operators, will be in

the best position to determine whether additional post-injection site care is needed. EPA expects this

decision to be made based on relevant site data and in consultation with all potentially impacted

parties. 

EPA disagrees that the rule should specify the criteria for setting the monitoring timeframe. Instead,

EPA believes that such determinations are site-specific and should be described in a project specific

post-injection site care and site closure plan. EPA also believes that periodic reviews and updates,

where necessary, to the plan are important to ensuring that the site continues to be managed

effectively and to determine whether shortening the monitoring timeframe is appropriate. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that

a complete cessation of plume movement is not required, only a demonstration that the plume and

pressure front no longer pose a risk of endangerment to USDWs. 
EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities. The guidance will be available at

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

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24499

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

language 

Comment: Rule Provision: 146.93(b)(3) 

Proposed CCS Group Recommendations: (3) Prior to authorization for site closure, 

the owner or operator must DEMONSTRATE TO THE DIRECTOR, BASED ON MONITORING, 

OTHER SITE-SPECIFIC DATA, AND MODELING THAT IS REASONABLY CONSISTENT

WITH SITE 

PERFORMANCE, THAT NO ADDITIONAL MONITORING IS NEEDED TO ASSURE THAT

THE GEOLOGIC 

SEQUESTRATION PROJECT DOES NOT AND IS NOT EXPECTED TO POSE AN

ENDANGERMENT TO 

USDWS. THE DIRECTOR SHALL APPROVE CLOSURE IF THE OWNER OR OPERATOR

DEMONSTRATES, 

BASED ON THE CURRENT UNDERSTANDING OF THE SITE, INCLUDING MONITORING

DATA AND/OR 

MODELING, ALL OF THE FOLLOWING: (I) THE ESTIMATED MAGNITUDE AND EXTENT

OF THE 

PROJECT FOOTPRINT (CO2 PLUME AND THE AREA OF ELEVATED PRESSURE) ; (II) THE

ESTIMATED LOCATION OF THE DETECTABLE CO2 PLUME; (III) THAT THERE IS NO 

SIGNIFICANT LEAKAGE OF EITHER CO2 OR DISPLACED FORMATION FLUIDS THAT IS 

ENDANGERING USDWS; (IV) THAT THE INJECTED OR DISPLACED FLUIDS ARE NOT

EXPECTED 

TO MIGRATE IN THE FUTURE IN A MANNER THAT ENCOUNTERS A POTENTIAL

LEAKAGE PATHWAY 

INTO A USDW; (V) THAT THE INJECTION WELLS AT THE SITE COMPLETED INTO OR

THROUGH 

THE INJECTION ZONE OR CONFINING ZONE ARE PLUGGED AND ABANDONED IN

ACCORDANCE 

WITH THESE REQUIREMENTS; AND (VI) ANY REMAINING PROJECT MONITORING

WELLS AT THE 

SITE ARE BEING MANAGED BY A PERSON AND IN A MANNER ACCEPTABLE TO THE

DIRECTOR. 

Basis for CCS Group Comments: We believe there are three problems with the 

closure standard in proposed section 146.93(b). First, the presumption that 

monitoring should continue for 50 years is unnecessary and counterproductive. A 
straight performance standard is preferable to this or any other fixed time 

period because it provides a clearer standard and an incentive to maximize the 

understanding of site and project performance and as such is more protective of 

USDWs. Second, the proposal requires a showing that the CO2 plume has 

"stabilized", which is undefined. Cessation of plume movement is not necessarily 

essential to show that a project poses no threat of endangerment to USDWs-plumes 

that are still moving may, nonetheless, remain contained. Instead, it is more 

protective to show that the plume is not expected to encounter a leakage 

pathway. Third, the required showing that "no additional monitoring is needed" 

does not provide guidance regarding how an operator is to show that no 

additional monitoring is needed. The proposal below provides specific guidance 

on what the operator must show. 

We recommend the standard in the proposed alternative language for section 

146.93(b) below because it sets forth detailed criteria, all of which must be 

satisfied, to demonstrate that the site does not pose an endangerment to USDWs. 

The specific criteria listed in our proposal will serve to provide the Director 

with the requisite information to make the appropriate determination. The 

advantage of this approach is that it establishes clear criteria that an 

operator must demonstrate before obtaining site closure based upon particular 

site characteristics and is, therefore, reasonably applicable to any storage 

site as opposed to a standard based upon a fixed-duration. Furthermore, it is 

more stringent than a purely discretionary approach because it establishes 

specific criteria that must be shown before site closure may be granted. We 

believe this language, which is an extension of work done by the World Resources 

Institute and the Ground Water Protection Council, avoids the noted shortcomings 

and provides stronger protection for USDWs. 

This is the same recommendation as presented by the multi-stakeholder group, in 

which the Carbon Sequestration Council participated. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring

timeframe. Instead, EPA believes that such determinations are site-specific and should be described

in a project specific post-injection site care and site closure plan. EPA also believes that periodic

reviews and updates, where necessary, to the plan are important to ensuring that the site continues to

be managed effectively and to determine whether shortening the monitoring timeframe is

appropriate. 

The post-injection site care requirements in the final GS rule incorporate a combination of a fixed

timeframe and a performance standard approach. The final GS rule offer owners or operators

flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to

shorten or lengthen the PISC timeframe during the post-injection period based on site-specific data,

pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI

well owner or operator to demonstrate, during the permitting process based on substantial data, that

an alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs

pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is
anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells, perform post-injection monitoring,

demonstrate the appropriateness of an alternative post-injection site care time frame, demonstrate

non-endangerment, and perform site closure activities. The guidance will be available at

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

Commenter Name: Kyle Isakower Letter ID: 0191

Commenter Organization: American Petroleum Institute Comment ID: 23884

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

language 

Comment: (3) Prior to authorization for site closure, the owner or operator must 

demonstrate to the Director, based on monitoring, other site-specific 

data, and modeling that is reasonably consistent with site performance, 

that no additional monitoring is needed to assure that the geologic 

sequestration project does not and is not expected to pose an 

endangerment to USDWs. The Director shall approve closure if the owner 

or operator demonstrates, based on the current understanding of the 

site, including monitoring data and/or modeling, all of the following: 

(i) the estimated magnitude and extent of the project footprint (CO2 

plume and the area of elevated pressure) ; (ii) the estimated location 

of the detectable CO2 plume; (iii) that there is no significant leakage 

of either CO2 or displaced formation fluids that is endangering USDWs; 

(iv) that the injected or displaced fluids are not expected to migrate 

in the future in a manner that encounters a potential leakage pathway 

into a USDW; (v) that the injection wells at the site completed into or 

through the injection zone or confining zone are plugged and abandoned 

in accordance with these requirements; and (vi) any remaining project 

monitoring wells at the site are being managed by a person and in a 

manner acceptable to the Director. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring

timeframe. Instead, EPA believes that such determinations are site-specific and should be described

in a project specific post-injection site care and site closure plan. EPA also believes that periodic

reviews and updates, where necessary, to the plan are important to ensuring that the site continues to

be managed effectively and to determine whether shortening the monitoring timeframe is

appropriate. 

The post-injection site care requirements in the final GS rule offer owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).
EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Jeff W. Sheets Letter ID: 0192

Commenter Organization: ConocoPhillips Comment ID: 23905

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

language 

Comment: (3) Prior to authorization for site closure, the owner or operator must 

demonstrate to the Director, based on monitoring, other site-specific 

data, and modeling that is reasonably consistent with site performance, 

that no additional monitoring is needed to assure that the geologic 

sequestration project does not and is not expected to pose an 

endangerment to USDWs. The Director shall approve closure if the owner 

or operator demonstrates, based on the current understanding of the 

site, including monitoring data and/or modeling, all of the following: 

(i) the estimated magnitude and extent of the project footprint (CO2 

plume and the area of elevated pressure) ; (ii) the estimated location 

of the detectable CO2 plume; (iii) that there is no significant leakage 

of either CO2 or displaced formation fluids that is endangering USDWs; 

(iv) that the injected or displaced fluids are not expected to migrate 

in the future in a manner that encounters a potential leakage pathway 

into a USDW; (v) that the injection wells at the site completed into or 

through the injection zone or confining zone are plugged and abandoned 

in accordance with these requirements; and (vi) any remaining project 

monitoring wells at the site are being managed by a person and in a 

manner acceptable to the Director. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring

timeframe. Instead, EPA believes that such determinations are site-specific and should be described

in a project specific post-injection site care and site closure plan. EPA also believes that periodic

reviews and updates, where necessary, to the plan are important to ensuring that the site continues to

be managed effectively and to determine whether shortening the monitoring timeframe is

appropriate. The post-injection site care requirements in the final GS rule offer owners or operators

flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to

shorten or lengthen the PISC timeframe during the post-injection period based on site-specific data,
pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI

well owner or operator to demonstrate, during the permitting process based on substantial data, that

an alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs

pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24721

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

language 

Comment: Rule Provision: 146.93(b)(3) 

Anadarko Petroleum Corporation (APC) Comments: (3) Prior to authorization for 

site closure, the owner or operator must submit to the Director a 

demonstration, DEMONSTRATE TO THE DIRECTOR, based on monitoring, and other 

site-specific data, AND MODELING THAT IS REASONABLY CONSISTENT WITH SITE 

PERFORMANCE that the carbon dioxide plume and pressure front have stabilized 

and that no additional monitoring is needed to assure that the geologic 

sequestration project does not pose an endangerment to USDWs. 

THE OWNER OR OPERATOR MUST DEMONSTRATE, BASED ON THE CURRENT

UNDERSTANDING OF 

THE SITE, INCLUDING MONITORING DATA AND/OR MODELING, ALL OF THE

FOLLOWING: (I) 

THE ESTIMATED MAGNITUDE AND EXTENT OF THE PROJECT FOOTPRINT (CO2

PLUME AND THE 

AREA OF ELEVATED PRESSURE); (II) THE ESTIMATED LOCATION OF THE

DETECTABLE CO2 

PLUME ; (III) THAT THERE IS NO SIGNIFICANT LEAKAGE OF EITHER CO2 OR

DISPLACED 

FORMATION FLUIDS THAT IS ENDANGERING USDWS; (IV) THAT THE INJECTED OR

DISPLACED 

FLUIDS ARE NOT EXPECTED TO MIGRATE IN THE FUTURE IN A MANNER THAT

ENCOUNTERS A 

POTENTIAL LEAKAGE PATHWAY INTO A USDW; (V) THAT THE INJECTION WELLS AT
THE SITE 

COMPLETED INTO OR THROUGH THE INJECTION ZONE OR CONFINING ZONE ARE

PLUGGED AND 

ABANDONED IN ACCORDANCE WITH THESE REQUIREMENTS; AND (VI) ANY

REMAINING PROJECT 

MONITORING WELLS AT THE SITE ARE BEING MANAGED BY A PERSON AND IN A

MANNER 

ACCEPTABLE TO THE DIRECTOR. 

Rationale: APC edits establish the performance based criteria for selecting the 

monitoring period. 

EPA should recognize that under any given set of site specific conditions some 

of these criteria may not be fully satisfied. EPA should retain the ability to 

waive individual monitoring criteria described here to reflect that situation. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring

timeframe. Instead, EPA believes that such determinations are site-specific and should be described

in a project-specific post-injection site care and site closure plan. EPA also believes that periodic

reviews and updates, where necessary, to the plan are important to ensuring that the site continues to

be managed effectively and to determine whether shortening the monitoring timeframe is

appropriate. The post-injection site care requirements in the final GS rule incorporate a combination

of a fixed timeframe and a performance standard approach. The final GS rule offer owners or

operators flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director

discretion to shorten or lengthen the PISC timeframe during the post-injection period based on sitespecific data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to

allow a Class VI well owner or operator to demonstrate, during the permitting process based on

substantial data, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells, perform post-injection monitoring,

demonstrate the appropriateness of an alternative post-injection site care time frame, demonstrate

non-endangerment, and perform site closure activities. The guidance will be available at

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

Commenter Name: John King Letter ID: 0211

Commenter Organization: Shell Exploration and Production Company

(SEPCo)

Comment ID:

22752

Comment: - Closure and Post-Injection Site Care: Criteria for determining the period for 
post-injection site care should be performance-based and a function of the sitespecific characteristics of a project such as project size, geologic factors, 

and relative risk of the project. (API offers such criteria in their edits to 

§146.93(b)(3).) Clear guidelines also need to be established regarding when 

operators have met the performance standards that determine site closure. 

Specifically, the standard that the project no longer poses an endangerment to 

USDWs needs to be defined using reasonable risk-based criteria. 

Response: The post-injection site care requirements in the final GS rule incorporate a combination

of a fixed timeframe and a performance standard approach. The final GS rule offer owners or

operators flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director

discretion to shorten or lengthen the PISC timeframe during the post-injection period based on sitespecific data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to

allow a Class VI well owner or operator to demonstrate, during the permitting process based on

substantial data, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non-endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Edward Steadman Letter ID: 0220

Commenter Organization: The Energy and Environmental Research Center at the

University of North Dakota

Comment ID:

21589

Other EPA Comment Codes and Descriptions: 1670 1.3.7 Other/miscellaneous risks 

Comment: Page 43498. Regarding the statement, "the measures outlined in today’s proposed 

rulemaking to prevent endangerment of USDWs may also prevent migration of CO2 to 

the subsurface." 

This statement is fine, as long as protecting leakage to the atmosphere does not 

lead to stricter measures than would be required to protect USDWs. For example, 

regulations should be driven by a desire to maintain a leakage rate below a 

certain percentage of the injected volume, unless that percentage can be 

demonstrated to adversely affect USDWs. Another way to state it is this: a 1% 

leakage rate may or may not adversely affect USDWs; therefore, a 1% rate should 

not necessarily be unacceptable. 

Response: EPA clarifies that all requirements in the GS rule are for the purpose of preventing
endangerment to USDWs, and that the tailored permitting, siting, construction, operation,

monitoring, and post-injection site care requirements in the GS rule are intended to prevent leakage

from injection formations and protect USDWs. 

EPA acknowledges that there are potential risks associated with GS. The purpose of the Class VI

requirements is to minimize and mitigate potential/identified risks through proper site

characterization, well construction, operation, monitoring, post-injection site care, and site closure

and to ensure protection of USDWs. The Agency clarifies that, under SDWA, EPA does not have

the authority to directly regulate air emissions via CO2 leakage to the surface. However, the GS rule

requires that CO2 injected for GS remain confined in the injection zone. Leakage outside of the

injection zone as defined in a Class VI permit, which may be evidenced by leakage to the surface,

would be a permit violation if a USDW is endangered.

Commenter Name: M. Granger Morgan Letter ID: 0233

Commenter Organization: Carnegie Mellon University on behalf of the CCS

Reg Project

Comment ID:

21911

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: 20. Site closure: We support the general approach that EPA proposes to determine 

the length of the post-injection site care period (a performance standard, 

anchored by a suggested duration of several decades). However, we suggest three 

modifications: 1) The rule should require that the post-injection site care and 

site-closure plan specify thresholds for demonstrating that the GS project no 

longer poses an endangerment to USDWs; 2) The rule should provide mechanisms to 

coordinate information and allocate responsibility if site conditions during the 

post-injection site care period are altered by operations of another GS project 

in the basin; and, 3) The 50-year time period should not become a prescriptive 

default. There is not yet enough experience to set this as the suggested 

duration of the post-injection site care period. For now, a performance standard 

alone is preferable and creates the right incentives to protect USDWs. After 

experience has been gained from early projects, the rule could be amended to 

include a suggested duration. 

Response: EPA agrees that the rule should not specify the criteria for setting the monitoring

timeframe. Instead, EPA believes that such determinations are site-specific and should be described

in a project-specific post-injection site care and site closure plan. However, EPA disagrees that the

plan should specify thresholds for demonstrating that the GS project no longer poses a risk of

endangerment to USDWs, but agrees that this demonstration should be an important consideration.

EPA is developing guidances with recommended approaches for developing and implementing postinjection site care and site closure plans and guidance that describes recommended approaches for

how an owner or operator could plug injection and monitoring wells, perform post-injection

monitoring, demonstrate non endangerment, and perform site closure activities. The guidances will

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

EPA agrees with commenters that there will be circumstances where it can be demonstrated in less

than 50 years that the plume and pressure front no longer pose a risk of endangerment to USDWs.

For this reason, the final GS regulation includes a provision that the Director may, at his or her

discretion, shorten the post-injection site care timeframe if the owner or operator can demonstrate

that the GS project does not pose an endangerment to USDWs, as specified in §146.93(b)(2). Such a
demonstration will be site-specific, and based on pressure monitoring and USDW impacts. EPA

believes however, that to ensure USDW protection from endangerment, a default timeframe for postinjection site care is necessary. A 50-year post-injection site care timeframe represents a reasonable

and protective monitoring period based on a review of research studies, industry reports, and existing

environmental programs, and evaluation of public comments.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24945

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Rule Provision: 146.93(b) 

EPA Proposal: (b) The owner or operator shall monitor the site following the 

cessation of injection to show the position of the carbon dioxide plume and 

pressure front and demonstrate that USDWs are not being endangered. 

(1) The owner or operator shall continue to conduct monitoring as specified in 

the Director-approved post-injection site care and site closure plan for at 

least 50 years following the cessation of injection. At the Director’s 

discretion, the monitoring will continue until the geologic sequestration 

project no longer poses an endangerment to USDWs. 

GWPC Recommendations: (b) The owner or operator shall monitor the site following 

the cessation of injection. 

(1) The owner or operator shall continue to conduct monitoring as specified in 

the Director-approved post-injection site care and site closure plan until 

closure is authorized pursuant to 146.93(b)(3). 

Rationale: Eliminate the 50 year requirement. 

There is no justification for extending completed projects for the presumptive 

50 years, and it will be difficult to accept much shorter demonstration periods 

with the 50 year presumption in the regulations. Default 50-year period defeats 

incentives for best site identification and best MMV 

Need for site-specific considerations and use of data 

Need achievable and definable standard 

Response: EPA agrees that there will be circumstances where it can be demonstrated in less than 50

years that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this

reason, the final GS regulation includes a provision that the Director may, at his or her discretion,

shorten the post-injection site care timeframe if the owner or operator can demonstrate that the GS

project does not pose an endangerment to USDWs, as specified in §146.93(b)(2). Such a

demonstration will be site-specific, and based on pressure monitoring and USDW impacts.

Alternatively, the final rule at §146.93(c), also allows the Director to approve an alternative postinjection site care timeframe where an owner or operator can demonstrate during the permitting
process that an alternative post-injection site care timeframe, other than the 50 year default, is

appropriate and ensures non-endangerment of USDWs. The demonstration must be based on sitespecific information, including the results of site-specific computational modeling; the predicted

timeframe for pressure decline; the predicted rate of carbon dioxide plume migration; site-specific

chemical processes that will result in carbon dioxide trapping; the predicted rate of carbon dioxide

trapping; characterization of the confining zone(s); laboratory analyses or studies to verify the

information on trapping; the presence of potential conduits for fluid movement and the quality of

abandoned well plugs within the AoR; the distance between the injection zone and the USDWs

above and/or below the injection zone; and any additional site-specific factors determined by the

Director. The demonstration must meet the criteria at §146.93(c)(2) for ensuring the quality and

accuracy of the data and models on which the demonstration is based. This demonstration would be

submitted as part of the permit application, per §146.82(a)(18), in addition to the PISC and site

closure plan required at §146.82(a)(17). 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24947

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

language 

Comment: EPA Proposal: (3) Prior to authorization for site closure, the owner or operator 

must submit to the Director a demonstration, based on monitoring and other sitespecific data, that the carbon dioxide plume and pressure front have stabilized 

and that no additional monitoring is needed to assure that the geologic 

sequestration project does not pose an endangerment to USDWs. 

GWPC Recommendations: (3) Prior to authorization for site closure, the owner or 

operator must demonstrate to the Director, based on monitoring, other sitespecific data, and modeling that is reasonably consistent with site performance, 

that no additional monitoring is needed to assure that the geologic 

sequestration project does not and is not expected to pose an endangerment to 

USDWs. The Director shall approve closure if the owner or operator demonstrates, 

based on the current understanding of the site, including monitoring data and/or 

modeling, all of the following: (i) the estimated magnitude and extent of the 

project footprint (CO2 plume and the area of elevated pressure) ; (ii) the 

estimated location of the detectable CO2 plume; (iii) that there is no 

significant leakage of either CO2 or displaced formation fluids that is 
endangering USDWs; (iv) that the injected or displaced fluids are not expected 

to migrate in the future in a manner that encounters a potential leakage pathway 

into a USDW; (v) that the injection wells at the site completed into or through 

the injection zone or confining zone are plugged and abandoned in accordance 

with these requirements; and (vi) any remaining project monitoring wells at the 

site are being managed by a person and in a manner acceptable to the Director. 

Rationale: The GWPC revised this section to establish the performance based 

criteria for selecting the monitoring period. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring

timeframe. Instead, EPA believes that such determinations are site-specific and should be described

in a project specific post-injection site care and site closure plan. EPA also believes that periodic

reviews and updates, where necessary, to the plan are important to ensuring that the site continues to

be managed effectively and to determine whether shortening the monitoring timeframe is

appropriate. 

As described above, EPA agrees that there will be circumstances where it can be demonstrated in

less than 50 years that the plume and pressure front no longer pose a risk of endangerment to

USDWs. For this reason, the GS rule offers owners or operators flexibility regarding the duration of

the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the post-injection period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, during the permitting process based on substantial data, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Mark Vickery Letter ID: 0280

Commenter Organization: Texas Commission on Environmental Quality Comment ID: 24104

Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions; 5240

2.8.2.2 Post injection timeframe (seeking comment) 

Comment: (e) Concern exists regarding the need for (i) a standard (in concentration or 

saturation) for defining the edge of a CO2 plume, (ii) clear definition of the 

term "stabilization" as applied to fate and transport of an injected CO2 plume 

and pressure front, and (iii) a clarified specification of the performance 

standard for the necessary demonstration to enable termination of the iterative 

process of monitoring/modeling and related corrective action. If "stabilization" 

means absence of plume movement or pressure change, it is our understanding from 

CO2-GS research efforts that indefinitely long periods of monitoring, modeling, 

and corrective action may be required in contrast to the default period of fifty 

years cited in the proposed rules and preamble. A more appropriate basis for 
demonstrations of protection of underground sources of drinking water (USDW) 

would be keyed to the presence of induced pressure conditions in the injection 

zone, spatially and temporally. When and where such pressure conditions are 

insufficient to cause endangerment of a USDW through leakage pathways such as 

improperly constructed or plugged wells or transmissible faults, the required 

USDW protection should be considered to be present. Accordingly, if the 

termination of monitoring, modeling, and corrective action is ultimately 

dependent on making the subject demonstration, it is recommended that the "fifty 

year" specification be deleted from the rule. This would conform the 

requirements for post-injection site care for Class VI wells more closely to the 

post-closure care specifications and concepts existing for Class I wells. 

Response: EPA disagrees that the rule should specify the criteria for setting the monitoring

timeframe. Instead, EPA believes that such determinations are site-specific and should be described

in a project specific post-injection site care and site closure plan. EPA also believes that periodic

reviews and updates, where necessary, to the plan are important to ensuring that the site continues to

be managed effectively and to determine whether shortening the monitoring timeframe is

appropriate. 

EPA acknowledges that many site-specific factors will influence the determination of when the CO2

plume and pressure front no longer pose a risk of endangerment to USDWs. It is for this reason that

EPA believes that individual UIC Directors, in consultation with operators, will be in the best

position to determine whether additional post-injection site care is needed. EPA expects this decision

to be made based on relevant site data and in consultation with all potentially impacted parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that

a complete cessation of plume movement is not required, only a demonstration that the plume and

pressure front no longer pose a risk of endangerment to USDWs. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist

Directors in evaluating proposed well plugging plans and post-injection site care and site closure

plans under 146.92 and 146.93. The guidance describes recommended approaches for how an owner

or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Mark Vickery Letter ID: 0280

Commenter Organization: Texas Commission on Environmental Quality Comment ID: 24110

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: (f) TCEQ agrees with EPA's approach that financial assurance for post-injection 

site care may be required for a period less than or greater than fifty years as 

proposed in 146.93, depending on a site specific demonstration to the Director. 

However, consistent with TCEQ's comments under Principal Concern 1, TCEQ also 

encourages EPA to delete the fifty-year threshold requirement in consideration 

of EPA's indication that the duration of financial assurance should ultimately 

be keyed to whatever site-specific time is necessary to meet the post-injection 
site care performance standard of demonstration of non-endangerment ofUSDWs. 

Response: EPA agrees that financial responsibility must be maintained throughout the post-injection

site care timeframe, regardless of its ultimate length. The GS rule requires this, at 146.85. 

EPA also agrees that there will be circumstances where it can be demonstrated in less than 50 years

that the plume and pressure front no longer pose a risk of endangerment to USDWs. For this reason,

the GS rule offers owners or operators flexibility regarding the duration of the PISC timeframe by:

(1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the postinjection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording

the Director discretion to allow a Class VI well owner or operator to demonstrate, during the

permitting process based on substantial data, that an alternative PISC timeframe may be appropriate

if it ensures non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: A. Scott Anderson Letter ID: 0293

Commenter Organization: Environmental Defense Fund Comment ID: 25278

Comment: (1). It is critical that the rule contain a "closure standard" for GS projects 

that is feasible, scientifically rigorous, and adequate for purposed of 

fostering public confidence in GS technology. Unless EPA develops an adequate 

closure standard, there is no reason to expect the public to have confidence in 

this technology. We believe that the standard ought to be based on the 

suggestions made in the December 23 letter; 

Response: EPA agrees that authorization of site closure must be feasible, scientifically rigorous, and

foster public confidence in GS technology, but disagrees that the rule should set specific criteria.

EPA believes that many site-specific factors will influence the determination of when the CO2

plume and pressure front no longer pose a risk of endangerment to USDWs. It is for this reason that

EPA believes that individual UIC Directors, in consultation with operators, will be in the best

position to determine whether additional post-injection site care is needed. EPA expects this decision

to be made based on relevant site data and in consultation with all potentially impacted parties. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist

Directors in evaluating proposed well plugging plans and post-injection site care and site closure

plans under 146.92 and 146.93. The guidance describes recommended approaches for how an owner

or operator could plug injection and monitoring wells; perform post-injection monitoring;
demonstrate non endangerment; and perform site closure activities. The guidance will be available at

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

Comment Code: 5300 2.8.3 Site closure activities (40 CFR 146.93) 

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: 21988

Other EPA Comment Codes and Descriptions: 4730 2.7.3 Reporting associated with closure and

post-injection site care 

Comment: 146.93 (f): This will be impractical for large sequestration projects due to the 

paperwork and legal work to deal with a significant number of parties. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention

such as site closure reports. EPA believes that the requirements that the owner or operator retain for

ten years following site closure, records collected during the post-injection site care period at

§146.93(f) and §146.93(h) are appropriate for the post-injection and site closure period to ensure that

data are available to support non-endangerment demonstrations and to address any concerns that may

arise following site closure. This data will also support EPA's review of project data as part of the

adaptive rulemaking approach.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24807

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: (e) Once the Director has authorized site closure, THE OWNER OR OPERATOR must 

submit a site closure report within 90 days that must thereafter be retained at 

a location designated by the Director. The report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. Must provide a copy of 

a survey plat which has been submitted to the local zoning authority designated 

by the Director, which indicates the location of the injection well relative to 

permanently surveyed benchmarks. Must also submit a copy of the plat to the 

regional administrator of the appropriate EPA Regional Office; 

{Why is this necessary? The EPA regional office will have access to all records 

at the State. } 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on

the deed to the facility property or other similar document examined during a title search that the

land has been used to sequester CO2 at the time of site closure.
Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24808

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: (f) THE OWNER OR OPERATOR MUSTMust record a notation on the deed to the 

facility property or any other document that is normally examined during title 

search that will in perpetuity provide any potential purchaser of the property 

the following information: 

(1) The fact that land has been used to sequester carbon dioxide; 

(2) The name of the State agency, local authority, and/or tribe with which the 

survey plat was filed, as well as the address of the Regional EPA Office to 

which it was submitted; and (3) The volume of fluid injected, the injection 

zone or zones into which it was injected, and the period over which 

injection occurred. 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation that

the land has been used to sequester CO2 on the deed to the facility property at the time of site

closure.

Commenter Name: Leslie Savage Letter ID: 0122

Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24809

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: (g) Must retain for three years following site closure, records collected during 

the post-injection site care period. THE OWNER OR OPERATOR MUST Must

deliver the records to the Director at the conclusion of the retention period, 

and the records must thereafter be retained at a location designated by the 

Director for that purpose. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention

such as site closure reports. EPA believes that the requirements that the owner or operator retain for

ten years following site closure, records collected during the post-injection site care period at

§146.93(f) and §146.93(h) are appropriate for the post-injection and site closure period to ensure that

data are available to support non-endangerment demonstrations and to address any concerns that may

arise following site closure. This data will also support EPA's review of project data as part of the

adaptive rulemaking approach.

Commenter Name: Bonnie Lovelace Letter ID: 0152

Commenter Organization: Montana Department of Environmental Quality

(MDEQ)

Comment ID:

22132

Comment: 146.93(f): MDEQ supports the requirement to make known to any land owners or 

future purchasers the existence of the plume below their land. 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation that

the land has been used to sequester CO2 on the deed to the facility property at the time of site

closure.
Commenter Name: James Dooley Letter ID: 0156

Commenter Organization: Joint Global Change Research Institute, Pacific

Northwest National Laboratory

Comment ID:

22635

Comment: Requirement to Document GS Sites and Pass that Information on to Future 

Potential Users of the Land Above as well as any Subsurface Zones Is Appropriate 

Page 43541. It is appropriate for the USEPA to require that steps be taken to 

document the CO2 injection formation and to ensure that information is passed on 

into the future. The steps spelled out here are reasonable and not overly 

burdensome (e.g., survey plat and deed for land must include a notation that the 

deep subsurface was used for CO2 storage). This language should be retained in 

subsequent versions of the Class VI rule. 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation that

the land has been used to sequester CO2 on the deed to the facility property at the time of site

closure.

Commenter Name: James Childress Letter ID: 0158

Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23777

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

Comment: §146.93 Post-injection site care and site closure (b)(3) "Prior to authorization 

for site closure, the owner or operator must submit to the Director a 

demonstration, based on monitoring and other site-specific data, that the carbon 

dioxide plume and pressure front have stabilized and that no additional 

monitoring is needed to assure that the geologic sequestration project does not 

pose an endangerment to USDWs." 

Clarification of the term "stabilized" is needed. We recommend that the term 

"stabilized" does not necessarily mean the plume and pressure front are no 

longer moving, but that the rate and direction as defined by confinement zones 

no longer place an USDW at risk. Long-term monitoring should have an "end point" 

defined. Often termed an "exit strategy", this is a key point that is agreed 

upon by all parties about what is a "stable condition". Monitoring data includes 

a prescribed amount of error, thus statistics or other analyses may be required 

to define a "stable condition". 

Response: EPA acknowledges that many site-specific factors will influence the determination of

when the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for

this reason that EPA believes that individual UIC Directors, in consultation with operators, will be in

the best position to determine whether additional post-injection site care is needed. EPA expects this

decision to be made based on relevant site data and in consultation with all potentially impacted

parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that

a complete cessation of plume movement is not required, only a demonstration that the plume and

pressure front no longer pose a risk of endangerment to USDWs. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will
assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Kyle Isakower Letter ID: 0170

Commenter Organization: American Petroleum Institute Comment ID: 24210

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: Rule Provision: 146.93(e) 

API Comments: (e) Once the Director has authorizeSd site closure, the 

owner or operator must submit a site closure report within 90 days that must 

thereafter be retained at a location designated by the Director. AFTER 

COMPLETION OF ALL CLOSURE OPERATIONS. The report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the location 

of the injection well(S) relative to permanently surveyed benchmarks. The owner 

or operator must also submit a copy of the plat to the Regional Administrator of 

the appropriate EPA Regional Office; 

Rationale: Once the site closure report is submitted to the Director, the 

operator cease to bear responsibility for any further record retention. At this 

point, EPA becomes the steward of information for the project. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention

such as site closure reports. EPA believes that the requirements that the owner or operator retain, for

ten years following site closure, records collected during the post-injection site care period at

§146.93(f) and §146.93(h) are appropriate for the post-injection and site closure period to ensure that

data are available to support non-endangerment demonstrations and to address any concerns that may

arise following site closure. This data will also support EPA's review of project data as part of the

adaptive rulemaking approach.

Commenter Name: Frederick R. Eames Letter ID: 0178

Commenter Organization: CCS Alliance Comment ID: 23843

Comment: D. SITE CLOSURE 

The CCS Alliance recommends including a provision releasing sites certified as 

closed from further monitoring and verification requirements, as well as 

releasing any outstanding financial assurance instruments. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention

such as site closure reports. EPA believes that the requirements that the owner or operator retain for

ten years following site closure, records collected during the post-injection site care period at
§146.93(f) and §146.93(h) are appropriate for the post-injection and site closure period to ensure that

data are available to support non-endangerment demonstrations and to address any concerns that may

arise following site closure. This data will also support EPA's review of project data as part of the

adaptive rulemaking approach.

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23749

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

language 

Comment: Part 146.93(b)(3) When addressing plume stabilization in association with site 

closure, it is important to realize that the carbon dioxide plume will never be 

completely stable. The carbon dioxide plume will continue to move by a 

combination of methods including density differences, natural formation flow 

gradients and diffusion. AWWA recommends that EPA engage in research to provide 

specific criteria on what exactly it would mean for the plume to have 

stabilized. If left up to the discretion of the various Directors, stabilization 

could be defined in many different ways. In order to have a consistent 

application of this part of the regulation, EPA should define the specific 

situations in which the plume could be considered "stable." AWWA recommends 

revising this part to read: 

Prior to authorization for site closure, the owner or operator must demonstrate 

to the Director, based on monitoring and other site-specific data that no 

additional monitoring is needed to assure that the geologic sequestration 

project does not pose an endangerment to USDWs. The demonstration must 

demonstrate all of the following: 

(i) the estimated magnitude and extent of the project footprint (CO2 plume and 

the area of elevated pressure) based on measurements and modeling; 

(ii) that CO2 movement and pressure changes match model predictions, 

(iii) the estimated location of the detectable CO2 plume based on measurement 

and modeling (measuring magnitude of saturation within the plume or mapping the 

edge of it); 

(iv) that there is no evidence of significant leakage of either CO2 or displaced 

formation fluids that endanger USDWs; 

(v) that the CO2 plume and displaced formation fluid are not expected to migrate 

in the future in a manner that encounters a potential leakage pathway; 

(vi) that the injection wells at the site completed into or through the 

injection zone or confining zone are properly plugged and abandoned; and, 

(vii) any remaining project monitoring wells at the site are being managed by a 

person and in a manner acceptable to the Director. 

Response: EPA acknowledges that many site-specific factors will influence the determination of

when the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for

this reason that EPA believes that individual UIC Directors, in consultation with operators, will be in

the best position to determine whether additional post-injection site care is needed. EPA expects this

decision to be made based on relevant site data and in consultation with all potentially impacted

parties. 
EPA agrees that a complete cessation of plume movement may not occur at some sites for long time

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that

a complete cessation of plume movement is not required, only a demonstration that the plume and

pressure front no longer pose a risk of endangerment to USDWs. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 23750

Other EPA Comment Codes and Descriptions: 5200 2.8.2 Post injection site care (seeking

comment) (40 CFR 146.93) 

Comment: Part 146.93(d) There may be cases where the Director would want some of the 

monitoring wells to remain in service after site closure. While this may not be 

the case for all projects, for some of the earlier sites, the Director may want 

to continue minimal monitoring to continue to verify that the plume 

characteristics have remained stable. 

Response: EPA clarifies that the owner or operator must conduct post-injection site care that is

consistent with the approved PISC plan or for the duration of the alternative timeframe approved by

the Director pursuant to requirements in §146.93(c), until a demonstration can be made to the

satisfaction of the Director that the plume and pressure front no longer pose a risk of endangerment

to USDWs. After this determination is made, site closure is approved and the post-injection site care

period would end, as specified in §146.93 (b)(1). 

If, however, there is reason to believe that additional minimal monitoring is necessary to verify that

the plume characteristics have remained stable, this would be considered post-injection site care

monitoring. If a reduction in monitoring frequency or methods is appropriate (i.e., an additional year

or so of verification of the non-endangerment demonstration), the Director has discretion to

authorize an amendment to the post-injection site care and site closure plan. This is consistent with

the requirements at §146.93(b)(2).

Commenter Name: Thomas Curtis Letter ID: 0181

Commenter Organization: American Water Works Association (AWWA) Comment ID: 24373

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

language 

Comment: Part 146.93(c) AWWA recommends that this part of the rule needs to include a 

directive that the Director needs to provide approval for site closure prior to 

implementation of the site-closure plan. AWWA recommends revising this part to 

read: 

Notice of intent for site closure. The owner or operator must notify the 

Director at least 120 days before site closure. At this time, if any changes 
have been made to the original post-injection site care and site closure plan, 

the owner or operator must also provide the revised plan. The Director must 

provide approval for site closure prior to the implementation of the site 

closure plan. At the discretion of the Director, a shorter notice period may be 

allowed. 

Response: EPA considers the combination of the Director's evaluation of the data submitted to

support a demonstration of non-endangerment of USDWs, as specified in §146.93(b)(3), and the

Director's receipt of and agreement with the notification of intent for site closure as confirmation that

GS site closure can proceed.

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

Commenter Organization: Carbon Sequestration Council Comment ID: 24503

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: Rule Provision: 146.93(e) 

Proposed CCS Group Recommendations: (e) Once the Director has

authorizeSd site closure, the owner or operator must submit a site closure 

report within 90 days that must thereafter be retained at a location 

designated by the Director. AFTER COMPLETION OF ALL CLOSURE OPERATIONS. The 

report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the location 

of the injection well(S) relative to permanently surveyed benchmarks. The owner 

or operator must also submit a copy of the plat to the Regional Administrator of 

the appropriate EPA Regional Office; 

Basis for CCS Group Comments: Once the site closure report is submitted to the 

Director, the operator cease to bear responsibility for any further record 

retention. At this point, EPA becomes the steward of information for the 

project. 

Rule Provision: 146.93(e)(2) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Rule Provision: 146.93(f) 

Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Rule Provision: 146.93(g) 
Proposed CCS Group Recommendations: Support the proposed language. 

Basis for CCS Group Comments: Agree with EPA’s rationale. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention

such as site closure reports. EPA believes that the requirements that the owner or operator retain for

ten years following site closure, records collected during the post-injection site care period at

§146.93(f) and §146.93(h) are appropriate for the post-injection and site closure period to ensure that

data are available to support non-endangerment demonstrations and to address any concerns that may

arise following site closure. This data will also support EPA's review of project data as part of the

adaptive rulemaking approach.

The GS regulation at §146.93(g) requires the owner or operator to record a notation on the deed to

the facility property or other similar document examined during a title search that the land has been

used to sequester CO2 at the time of site closure.

EPA acknowledges the commenter’s support of the other parts; the final rule retains these provisions.

Commenter Name: Craig R. Walters Letter ID: 0200

Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24723

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: Rule Provision: 146.93(e) 

Anadarko Petroleum Corporation (APC) Comments: (e) Once the Director has 

authorized site closure, the owner or operator must submit a site closure report 

within 90 days that must thereafter be retained at a location designated by 

the Director. AFTER COMPLETION OF ALL CLOSURE OPERATIONS. The report must 

include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the location 

of the injection well(S) relative to permanently surveyed benchmarks. The owner 

or operator must also submit a copy of the plat to the Regional Administrator of 

the appropriate EPA Regional Office; 

Rationale: Once the site closure report is submitted to the Director, the 

operator cease to bear responsibility for any further record retention. At this 

point, EPA becomes the steward of information for the project. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention

such as site closure reports. EPA believes that the requirements that the owner or operator retain for

ten years following site closure, records collected during the post-injection site care period at

§146.93(f) and §146.93(h) are appropriate for the post-injection and site closure period to ensure that

data are available to support non-endangerment demonstrations and to address any concerns that may

arise following site closure. This data will also support EPA's review of project data as part of the
adaptive rulemaking approach.

Commenter Name: Chris M. Hobson Letter ID: 0201

Commenter Organization: Southern Company Comment ID: 22175

Other EPA Comment Codes and Descriptions: 5240 2.8.2.2 Post injection timeframe (seeking

comment) 

Comment: Post-Injection Site Care and Closure 

Southern Company opposes a default fifty-year timeframe - or any fixed default 

length of time - for the post-injection site care period. ¡d. at 43519. A 

default post-injection site care period is of little value given the widely 

varied characteristics of future CO2 GS sites, and the significant discrepancy 

between the appropriate post-injection site care period for various Class VI 

wells. As EPA itself recognizes, the actual time required for plume 

stabilization following cessation of injection will be "very site specific." ¡d. 

A site-specific determination, based on conditions at a particular Class VI 

well, will be necessary in the case of every CO2 GS project under the UIC 

Program. The Final Rule should define a performance-based standard for site 

closure and leave the site-specific analysis and determination of appropriate 

post-injection site care period to the Director. Potential Owners or Operators 

are likely to shy away from undertaking a CO2 GS project if the Program's 

requirements may extend decades into the future even when those requirements are 

no longer necessary. A performance-based standard allowing for site-specific 

closure period determinations will avoid the chilling effect that any default 

fixed timeframe for post-injection site care and closure will have on 

participation and investment in C02 GS projects. Moreover, the site-specific 

approach will ensure that an appropriate post-injection site care period is 

identified to meet the needs of each individual Class VI operation. 

Response: EPA agrees with commenters that there will be circumstances where it can be

demonstrated in less than 50 years that the plume and pressure front no longer pose a risk of

endangerment to USDWs. For this reason, the GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an

alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is
anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

Commenter Name: Richard Guinn Letter ID: 0210

Commenter Organization: Eastman Chemical Company Comment ID: 22727

Comment: §146.93 Post-injection site care and site closure (b)(3) "Prior to authorization 

for site closure, the owner or operator must submit to the Director a 

demonstration, based on monitoring and other site-specific data, that the carbon 

dioxide plume and pressure front have stabilized and that no additional 

monitoring is needed to assure that the geologic sequestration project does not 

pose an endangerment to USDWs." 

Clarification of the term "stabilized" is needed. We recommend that the term 

"stabilized" does not necessarily mean the plume and pressure front are no 

longer moving, but that the rate and direction as defined by confinement zones 

no longer place an USDW at risk. Long-term monitoring should have an "end point" 

defined. Often termed an "exit strategy", this is a key point that is agreed 

upon by all parties about what is a "stable condition". Monitoring data includes 

a prescribed amount of error , thus statistics or other analyses may be required 

to define a "stable condition". 

Response: EPA acknowledges that many site-specific factors will influence the determination of

when the CO2 plume and pressure front no longer pose a risk of endangerment to USDWs. It is for

this reason that EPA believes that individual UIC Directors, in consultation with operators, will be in

the best position to determine whether additional post-injection site care is needed. EPA expects this

decision to be made based on relevant site data and in consultation with all potentially impacted

parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long time

periods due to density differences, natural formation flow gradients and diffusion. EPA clarifies that

a complete cessation of plume movement is not required, only a demonstration that the plume and

pressure front no longer pose a risk of endangerment to USDWs. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Ronald Evans Letter ID: 0215

Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24313

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

language; 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: I. § 146.93 Post-injection site care and site closure. 
The proposed rule establishes a 50 year default period for post-injection site 

care. There is, however, no factual or scientific basis for such an extensive 

period. Under EPA’s Resource Conservation and Recovery Act rules, which regulate 

the disposal of hazardous wastes, post closure care is limited to 30 

years.[FN45] Defaulting to an excessively long period will increase costs and 

introduce greater regulatory uncertainty, which will discourage capital 

formation around CO2 sequestration. A more prudent regulatory approach is to set 

a minimum period for site care, ten years, with allowance for the Director to 

extend the period if facts and circumstances warrant a longer post-injection 

site care period. 

Additionally, the proposed rule’s 50 year default post injection site care 

period, is an illusory deadline, as it is not self-executing. Under the rules, 

post injection site care must continue indefinitely until the Director 

authorizes closure. The closure approval process could take years, even decades, 

as the Director has no regulatory incentive to act on any post injection site 

care report. Meanwhile, a permittee may be required to continue unnecessary and 

expensive monitoring and reporting indefinitely. 

Denbury suggests that the post-injection site care rules be reconfigured to 

require a more limited mandatory post-injection site care timeframe, and to 

allow for closure at the end of that period unless the Director affirmatively 

acts to extend the post-injection site care period. These changes are contained 

in the suggested text below: 

§ 146.93 Post-injection site care and site closure. 

(a) The owner or operator of a Class VI well must prepare, maintain, and 

comply with a plan for post-injection site care and site closure that 

meets the requirements of paragraph (a)(2) of this section and is 

acceptable to the Director. 

(1) The owner or operator must submit the post-injection site 

care and site closure plan as a part of the permit application to be 

approved by the Director. 

(2) The post-injection site care and site closure plan must 

include the following information: 

(i) The pressure differential between pre-injection and 

predicted post-injection pressures in the injection zone; 

(ii) The predicted position of the carbon dioxide plume 

and associated pressure front at site closure as demonstrated in 

the area of review evaluation required under § 146.84(b); 

(iii) A description of post-injection monitoring 

location, methods, and proposed frequency; and 

(iv) A proposed schedule for submitting post-injection 

site care monitoring results to the Director. 

(3) Upon cessation of injection, owners or operators of Class VI 

wells must either submit an amended post-injection site care and site 

closure plan or demonstrate to the Director through monitoring data and 

modeling results that no amendment to the plan is needed. 

(4) The owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval 
within 30 days of such change. 

(b) The owner or operator shall monitor the site following the cessation 

of injection to show the position of the carbon dioxide plume and 

pressure front and demonstrate that USDWs are not being endangered. 

(1) The owner or operator shall continue to conduct monitoring 

as specified in the Director-approved post-injection site care and site 

closure plan for at least 50 10 years following the cessation of 

injection. At the UPON A DETERMINATION BY THE Director ’s

THAT THE GEOLOGIC SEQUESTRATION PROJECT MAY POSE AN ENDANGERMENT TO 

USDWS discretion , THE DIRECTOR, AT HIS DISCRETION, MAY REQUIRE 

the monitoring will TO continue FOR A TIME PERIOD SPECIFIED BY 

THE DIRECTOR until the geologic sequestration project no longer poses 

an endangerment to USDWs.

(2) If the owner or operator can demonstrate to the satisfaction 

of the Director before 50 10 years, based on monitoring and other 

site-specific data, that the geologic sequestration project no longer 

poses an endangerment to USDWs, the Director may approve an amendment to 

the post injection site care and site closure plan to reduce the 

frequency of monitoring or may authorize site closure before the end of 

the 50 10 year period. 

(3) Prior to authorization for THE EXPIRATION OF THE 10 

YEAR POST-INJECTION SITE CARE PERIOD, site closure, the owner or 

operator must submit to the Director a demonstration, based on 

monitoring and other site specific data, that the carbon dioxide plume 

and pressure front have stabilized and that no additional monitoring is 

needed to assure that the geologic sequestration project does not pose 

an endangerment to USDWs. 

(4) IF WITHIN 180 DAYS AFTER THE SUBMITTAL OF THE DATA REQUIRED 

UNDER SUBPARAGRAPH (3) ABOVE THE DIRECTOR DETERMINES THAT THE

GEOLOGICAL 

SEQUESTRATION PROJECT MAY CONTINUE TO POSE AN ENDANGERMENT TO

USDWS, HE 

SHALL SO NOTIFY THE OWNER OR OPERATOR OF HIS DETERMINATION AND THE

BASIS 

THEREFORE, AND If such a demonstration cannot be made (i.e., if the 

carbon dioxide plume and pressure front have not stabilized) after the 

50-year period, the owner or operator must submit to the Director a 

plan to continue post-injection site care. 

(5) IF WITHIN 180 DAYS AFTER THE SUBMITTAL OF THE DATA REQUIRED 

UNDER SUBPARAGRAPH (3) ABOVE THE DIRECTOR FAILS TO DETERMINE AND TO 

NOTIFY THE OWNER OR OPERATOR THAT THE GEOLOGICAL SEQUESTRATION

PROJECT 

MAY CONTINUE TO POSE AN ENDANGERMENT TO USDWS, SITE CLOSURE SHALL BE 

DEEMED AUTHORIZED BY RULE 

(c) Notice of intent for site closure. 

The owner or operator must notify the Director at least 120 days before 

site closure. At this time, if any changes have been made to the 

original post-injection site care and site closure plan, the owner or 

operator must also provide the revised plan. At the discretion of the 

Director, a shorter notice period may be allowed. 
(d) After the Director has authorized site closure OR SITE CLOSURE IS 

AUTHORIZED BY RULE, the owner or operator must plug all monitoring wells 

in a manner which will not allow movement of injection or formation 

fluids that endangers a USDW. 

(e) Once the Director has authorized site closure, OR SITE CLOSURE IS 

AUTHORIZED BY RULE, the owner or operator must submit a site closure 

report within 90 days that must thereafter be retained at a location 

designated by the Director. The report must include: 

(1) Documentation of appropriate injection and monitoring well 

plugging as specified in § 146.92 and paragraph (c) of this section. The 

owner or operator must provide a copy of a survey plat which has been 

submitted to the local zoning authority designated by the Director. The 

plat must indicate the location of the injection well relative to 

permanently surveyed benchmarks. The owner or operator must also submit 

a copy of the plat to the Regional Administrator of the appropriate EPA 

Regional Office; 

(2) Documentation of appropriate notification and information to 

such State, local and tribal authorities as have authority over drilling 

activities to enable such State and local authorities to impose 

appropriate conditions on subsequent drilling activities that may 

penetrate the injection and confining zone(s); and 

(3) Records reflecting the nature, composition and volume of the 

carbon dioxide stream. 

(f) Each owner or operator of a Class VI injection well must record a 

notation on the deed to the facility property or any other document that 

is normally examined during title search that will in perpetuity provide 

any potential purchaser of the property the following information: 

(1) The fact that land has been used to sequester carbon dioxide; 

(2) The name of the State agency, local authority, and/or tribe 

with which the survey plat was filed, as well as the address of the 

Regional Environmental Protection Agency Office to which it was 

submitted; and 

(3) The volume of fluid injected, the injection zone or zones 

into which it was injected, and the period over which injection 

occurred. 

(g) The owner or operator must retain for three years following site 

closure, records collected during the post-injection site care period. 

The owner or operator must deliver the records to the Director at the 

conclusion of the retention period, and the records must thereafter be 

retained at a location designated by the Director for that purpose. 

[45] 40 C.F.R. § 264.117(a)(1) 

Response: The post-injection site care requirements in the final GS rule, §146.93(b), incorporate a

combination of a 50-year default post-injection site care timeframe, in conjunction with a

performance standard, for Class VI wells. The GS rule offers owners or operators flexibility

regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or

lengthen the PISC timeframe during the post-injection period based on site-specific data, pursuant to

requirements at §146.93(b); or (2) affording the Director discretion to allow a Class VI well owner

or operator to demonstrate, during the permitting process based on substantial data, that an
alternative PISC timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant

to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in all but a limited number of cases. This default 50 year

post-injection site care timeframe represents a reasonable and protective monitoring period based on

a review of research studies, industry reports, and existing environmental programs, and evaluation

of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts. EPA expects that the

Director will consider the types of information the commenter describes in determining whether the

plume and pressure front no longer pose a risk of endangerment to USDWs and post-injection site

care monitoring may be discontinued.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells, perform post-injection monitoring,

demonstrate the appropriateness of an alternative post-injection site care time frame, demonstrate

non-endangerment, and perform site closure activities. The guidance will be available at

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

Commenter Name: Darrick Eugene Letter ID: 0223

Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23994

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

language; 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Comment: Director affirmatively acts to extend the post-injection site care period. These 

changes are contained in the suggested text below: 

§ 146.93 Post-injection site care and site closure. 

(a) The owner or operator of a Class VI well must prepare, maintain, and 

comply with a plan for post-injection site care and site closure that 

meets the requirements of paragraph (a)(2) of this section and is 

acceptable to the Director. 

(1) The owner or operator must submit the post-injection site 

care and site closure plan as a part of the permit application to be 

approved by the Director. 

(2) The post-injection site care and site closure plan must 

include the following information: 

(i) The pressure differential between pre-injection and 

predicted post-injection pressures in the injection zone; 

(ii) The predicted position of the carbon dioxide plume 
and associated pressure front at site closure as demonstrated in 

the area of review evaluation required under § 146.84(b); 

(iii) A description of post-injection monitoring 

location, methods, and proposed frequency; and 

(iv) A proposed schedule for submitting post-injection 

site care monitoring results to the Director. 

(3) Upon cessation of injection, owners or operators of Class VI 

wells must either submit an amended post-injection site care and site 

closure plan or demonstrate to the Director through monitoring data and 

modeling results that no amendment to the plan is needed. 

(4) The owner or operator may modify and resubmit the postinjection site care and site closure plan for the Director’s approval 

within 30 days of such change. 

(b) The owner or operator shall monitor the site following the cessation 

of injection to show the position of the carbon dioxide plume and 

pressure front and demonstrate that USDWs are not being endangered. 

* 

* 

* 

(3) Prior to authorization for THE EXPIRATION OF THE PERIOD 

SPECIFIED IN SUBPART (B)(1), site closure, the owner or operator 

must submit to the Director a demonstration, based on monitoring and 

other site specific data, that the carbon dioxide plume and pressure 

front have stabilized and that no additional monitoring is needed to 

assure that the geologic sequestration project does not pose an 

endangerment to USDWs. 

(4) IF WITHIN 180 DAYS AFTER THE SUBMITTAL OF THE DATA REQUIRED 

UNDER SUBPARAGRAPH (3), THE DIRECTOR DETERMINES THAT THE GEOLOGICAL 

SEQUESTRATION PROJECT MAY CONTINUE TO POSE AN ENDANGERMENT TO

USDWS, HE 

SHALL SO NOTIFY THE OWNER OR OPERATOR OF HIS DETERMINATION AND THE

BASIS 

THEREFORE, AND If such a demonstration cannot be made (i.e., if the 

carbon dioxide plume and pressure front have not stabilized) after the 

50-year period, the owner or operator must submit to the Director a 

plan to continue post-injection site care. 

(5) IF WITHIN 180 DAYS AFTER THE SUBMITTAL OF THE DATA REQUIRED 

UNDER SUBPARAGRAPH (3) ABOVE THE DIRECTOR FAILS TO DETERMINE AND TO 

NOTIFY THE OWNER OR OPERATOR THAT THE GEOLOGICAL SEQUESTRATION

PROJECT 

MAY CONTINUE TO POSE AN ENDANGERMENT TO USDWS, SITE CLOSURE SHALL BE 

DEEMED AUTHORIZED BY RULE 

(c) Notice of intent for site closure. The owner or operator must notify 

the Director at least 120 days before site closure. At this time, if any 

changes have been made to the original post- injection site care and 

site closure plan, the owner or operator must also provide the revised 

plan. At the discretion of the Director, a shorter notice period may be 

allowed. 

(d) After the Director has authorized site closure OR SITE CLOSURE IS 

AUTHORIZED BY RULE, the owner or operator must plug all monitoring wells 
in a manner which will not allow movement of injection or formation 

fluids that endangers a USDW. 

(e) Once the Director has authorized site closure, OR SITE CLOSURE IS 

AUTHORIZED BY RULE, the owner or operator must submit a site closure 

report within 90 days that must thereafter be retained at a location 

designated by the Director. The report must include: 

(1) Documentation of appropriate injection and monitoring well 

plugging as specified in § 146.92 and paragraph (c) of this section. The 

owner or operator must provide a copy of a survey plat which has been 

submitted to the local zoning authority designated by the Director. The 

plat must indicate the location of the injection well relative to 

permanently surveyed benchmarks. The owner or operator must also submit 

a copy of the plat to the Regional Administrator of the appropriate EPA 

Regional Office; 

(2) Documentation of appropriate notification and information to 

such State, local and tribal authorities as have authority over drilling 

activities to enable such State and local authorities to impose 

appropriate conditions on subsequent drilling activities that may 

penetrate the injection and confining zone(s); and (3) Records 

reflecting the nature, composition and volume of the carbon dioxide 

stream. 

(f) Each owner or operator of a Class VI injection well must record a 

notation on the deed to the facility property or any other document that 

is normally examined during title search that will in perpetuity provide 

any potential purchaser of the property the following information: 

(1) The fact that land has been used to sequester carbon 

dioxide; 

(2) The name of the State agency, local authority, and/or tribe 

with which the survey plat was filed, as well as the address of the 

Regional Environmental Protection Agency Office to which it was 

submitted; and 

(3) The volume of fluid injected, the injection zone or zones 

into which it was injected, and the period over which injection 

occurred. 

(g) The owner or operator must retain for three years following site 

closure, records collected during the post-injection site care period. 

The owner or operator must deliver the records to the Director at the 

conclusion of the retention period, and the records must thereafter be 

retained at a location designated by the Director for that purpose. 

Response: The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a

combination of a fixed timeframe and a performance standard approach. EPA believes that a default

PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this timeframe,

combined with a site-specific Director’s discretion to create an alternative PISC time frame, ensures

that USDWs are protected. The GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at
§146.93(c).

EPA expects that the Director would consider the types of information the commenter describes in

determining whether the plume and pressure front no longer pose a risk of endangerment to USDWs

and post-injection site care monitoring may be discontinued. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 23998

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

language; 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: 3. Schlumberger does not support the default post injection site care period of 

50 years. We feel that because the characterization and operation of the site 

will be based on the specific attributes of the site that the length of post 

injection site care should also be site specific information. In particular the 

criteria for ending the PISC period should be based on site performance and 

risk. We support the idea that the director approves final site closure. We 

suggest the following language for Section 146.93(b)(1): 

(1) The owner or operator shall continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site 

closure plan, pursuant to the performance based criteria described in 

146.93(b)(3). 

We suggest the following language for section 146.93(b)(2) 

(2) If the owner or operator can demonstrate to the satisfaction of the 

Director that the geologic sequestration project no longer poses an 

endangerment to USDWs, the Director may approve an amendment to the 

post- injection site care and site closure plan to reduce the 

frequency of monitoring or may authorize site closure. 

And we suggest the following language for section 146.93(b)(3) 

(3) Prior to authorization for site closure, the owner or operator must 
demonstrate to the Director, based on monitoring and other sitespecific data that no additional monitoring is needed to assure that 

the geologic sequestration project does not pose an endangerment to 

USDWs, considering the following:. 

(i) the estimated magnitude and extent of the AOR based on measurements 

and modeling; (ii) that CO2 movement and pressure changes match model 

predictions, (iii) the estimated location of the detectable CO2 plume 

based on measurement and modeling (measuring magnitude of saturation 

within the plume or mapping the edge of it); (iv) that there is no 

evidence of significant leakage of either CO2 or formation fluids that 

endanger USDWs; (v) that the CO2 plume and displaced formation fluid are 

not expected to migrate in the future in a manner that encounters a 

potential leakage pathway; and, (vi) that wells at the site are not 

leaking and have maintained integrity. 

Response: The PISC requirements in the final GS rule, as specified in §146.93(b), incorporate a

combination of a fixed timeframe and a performance standard approach. EPA believes that a default

PISC timeframe of 50 years, with Director's discretion to shorten or lengthen this timeframe,

combined with a site-specific Director’s discretion to create an alternative PISC time frame, ensures

that USDWs are protected. The GS rule offers owners or operators flexibility regarding the duration

of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC

timeframe during the PISC period based on site-specific data, pursuant to requirements at

§146.93(b); or (2) affording the Director discretion to allow a Class VI well owner or operator to

demonstrate, based on substantial data during the permitting process, that an alternative PISC

timeframe may be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at

§146.93(c).

EPA expects that the Director would consider the types of information the commenter describes in

determining whether the plume and pressure front no longer pose a risk of endangerment to USDWs

and post-injection site care monitoring may be discontinued. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of §146.92 and §146.93. Additionally, the guidance will

assist Directors in evaluating proposed well plugging plans and post-injection site care and site

closure plans under §146.92 and §146.93. The guidance describes recommended approaches for how

an owner or operator could plug injection and monitoring wells; perform post-injection monitoring;

demonstrate the appropriateness of an alternative post-injection site care time frame; demonstrate

non endangerment; and perform site closure activities. The guidance will be available at

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.
Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24072

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

language 

Comment: Proposed Rule: (3) Prior to authorization for site closure, the owner or 

operator must submit to the Director a demonstration, based on monitoring and 

other site-specific data, that the carbon dioxide plume and pressure front have 

stabilized and that no additional monitoring is needed to assure that the 

geologic sequestration project does not pose an endangerment to USDWs. 

Schlumberger Suggested Revision: (3) Prior to authorization for site closure, 

the owner or operator must demonstrate to the Director, based on monitoring and 

other site-specific data that no additional monitoring is needed to assure that 

the geologic sequestration project does not pose an endangerment to USDWs, 

considering the following:. (i) the estimated magnitude and extent of the AOR 

based on measurements and modeling; (ii) that CO2 movement and pressure changes 

match model predictions, (iii) the estimated location of the detectable CO2 

plume based on measurement and modeling (measuring magnitude of saturation 

within (iv) that there is no evidence of significant leakage of either CO2 or 

formation fluids that endanger USDWs; (v) that the CO2 plume and displaced 

formation fluid are not expected to migrate in the future in a manner that 

encounters a potential leakage pathway; and, (vi) that wells at the site are not 

leaking and have maintained integrity. 

Schlumberger Rationale: Establishes the performance based criteria for selecting 

the monitoring period. the plume or mapping the edge of it); 

Response: The post-injection site care requirements in the final GS rule, §146.93(b), incorporate a

combination of a fixed timeframe and a performance standard approach. Specifically , the GS rule

offers owners or operators flexibility regarding the duration of the PISC timeframe by: (1) allowing

the Director discretion to shorten or lengthen the PISC timeframe during the post-injection period

based on site-specific data, pursuant to requirements at §146.93(b); or (2) affording the Director

discretion to allow a Class VI well owner or operator to demonstrate, during the permitting process

based on substantial data, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe for

post-injection site care will be necessary in most cases. The default 50 year post-injection site care

timeframe represents a reasonable and protective monitoring period based on a review of research

studies, industry reports, and existing environmental programs, and evaluation of public comments.

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to adjust

the timeframe for a limited number of GS projects during the permitting process where substantial

data exists to demonstrate that an alternative timeframe would be protective of USDWs, or based on

data collected during the PISC period, is appropriate to address the range of sites where GS is

anticipated to occur, to accommodate site-specific circumstances and various geologic conditions,

and addresses commenters’ concerns, while ensuring USDW protection. Both approaches will utilize

site-specific data, and be based on pressure monitoring and USDW impacts.

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist

Directors in evaluating proposed well plugging plans and post-injection site care and site closure
plans under 146.92 and 146.93. The guidance describes recommended approaches for how an owner

or operator could plug injection and monitoring wells; demonstrate the appropriateness of an

alternative post-injection site care time frame; perform post-injection monitoring; demonstrate non

endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24073

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

language 

Comment: Proposed Rule: (e) Once the Director has authorized site closure, the owner or 

operator must submit a site closure report within 90 days that must thereafter 

be retained at a location designated by the Director. The report must include: 

Schlumberger Suggested Revision: (e) Once the Director has authorized site 

closure, the owner or operator must submit a site closure report within 90 days 

after completion of all closure operations. The report must include: 

Schlumberger Rationale: What is the retention period? Many other programs have a 

three year limit for retention of records. EPA is the steward of information at 

this point of the project, not the owner or operator. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention

such as site closure reports. EPA believes that the requirements that the owner or operator retain for

ten years following site closure, records collected during the post-injection site care period at

§146.93(f) and §146.93(h) are appropriate for the post-injection and site closure period to ensure that

data are available to support non-endangerment demonstrations and to address any concerns that may

arise following site closure. This data will also support EPA's review of project data as part of the

adaptive rulemaking approach.

Commenter Name: Andrew Duguid Letter ID: 0226

Commenter Organization: Schlumberger Carbon Services Comment ID: 24074

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

language 

Comment: Proposed Rule: (1) Documentation of appropriate injection and monitoring well 

plugging as specified in §146.92 and paragraph (c) of this section. The owner or 

operator must provide a copy of a survey plat which has been submitted to the 

local zoning authority designated by the Director. The plat must indicate the 

location of the injection well relative to permanently surveyed benchmarks. The 

owner or operator must also submit a copy of the plat to the Regional 

Administrator of the appropriate EPA Regional Office; 

Schlumberger Suggested Revision: (1) Documentation of appropriate injection and 

monitoring well plugging as specified in §146.92 and paragraph (c) of this 

section. The owner or operator must provide a copy of a survey plat which has 

been submitted to the local zoning authority designated by the Director. The 

plat must indicate the location of the injection well(s) relative to permanently 

surveyed benchmarks. The owner or operator must also submit a copy of the plat 
to the Regional Administrator of the appropriate EPA Regional Office; 

Schlumberger Rationale: - 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on

the deed to the facility property or other similar document examined during a title search that the

land has been used to sequester CO2 on the deed to the facility property at the time of site closure.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24949

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

language 

Comment: Rule Provision: 146.93(c) 

EPA Proposal: (c) Notice of intent for site closure. The owner or operator must 

notify the Director at least 120 days before site closure. At this time, if any 

changes have been made to the original post-injection site care and site closure 

plan, the owner or operator must also provide the revised plan. At the 

discretion of the Director, a shorter notice period may be allowed. 

GWPC Recommendations: No recommendation 

Rationale: Need for site-specific considerations and use of data 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory

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

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24950

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

language 

Comment: Rule Provision: 146.93(d) 

EPA Proposal: (d) After the Director has authorized site closure, the owner or 

operator must plug all monitoring wells in a manner which will not allow 

movement of injection or formation fluids that endangers a USDW. 

GWPC Recommendations: No recommendation 

Rationale: Need for site-specific considerations and use of data 

Response: EPA acknowledges the comment. For additional information on EPA's final regulatory

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

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24951

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 
Comment: EPA Proposal: (e) Once the Director has authorized site closure, the owner or 

operator must submit a site closure report within 90 days that must thereafter 

be retained at a location designated by the Director. The report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in § 146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the 

location of the injection well relative to permanently surveyed benchmarks. The 

owner or operator must also submit a copy of the plat to the Regional 

Administrator of the appropriate EPA Regional Office; 

GWPC Recommendations: (e) Once the Director has authorized site closure, the 

owner or operator must submit a site closure report within 90 days after 

completion of all closure operations. The report must include: 

(1) Documentation of appropriate injection and monitoring well plugging as 

specified in §146.92 and paragraph (c) of this section. The owner or operator 

must provide a copy of a survey plat which has been submitted to the local 

zoning authority designated by the Director. The plat must indicate the location 

of the injection well(s) relative to permanently surveyed benchmarks. The owner 

or operator must also submit a copy of the plat to the Regional Administrator of 

the appropriate EPA Regional Office; 

Rationale: What is the retention period? Many other programs have a three year 

limit for retention of records. EPA is the steward of information at this point 

of the project, not the owner or operator. 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on

the deed to the facility property or other similar document examined during a title search that the

land has been used to sequester CO2 on the deed to the facility property at the time of site closure. 

Regarding record retention, EPA has clarified the recordkeeping requirements in the final GS rule,

which includes requirements that well plugging reports, as required at §146.92(d), post-injection site

care data, as required at §146.93(f), and site closure reports, as required at §146.93(h), must be kept

by the owner or operator for ten years after site closure. EPA believes that longer record retention

times for GS wells are appropriate and necessary for the post-injection and site closure period to

ensure that data are available to support non-endangerment demonstrations and to address any

concerns that may arise following site closure. This data will also support EPA's review of project

data as part of the adaptive rulemaking approach.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24952

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: EPA Proposal: (2) Documentation of appropriate notification and information to 

such State, local and tribal authorities as have authority over drilling 

activities to enable such State and local authorities to impose appropriate 

conditions on subsequent drilling activities that may penetrate the injection 
and confining zone(s); and 

(3) Records reflecting the nature, composition and volume of the carbon dioxide 

stream. 

GWPC Recommendations: No recommendation 

Rationale: Need for site-specific considerations and use of data 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on

the deed to the facility property or other similar document examined during a title search that the

land has been used to sequester CO2 on the deed to the facility property at the time of site closure.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24953

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: Rule Provision: 146.93 

EPA Proposal: (f) Each owner or operator of a Class VI injection well must 

record a notation on the deed to the facility property or any other document 

that is normally examined during title search that will in perpetuity provide 

any potential purchaser of the property the following information: 

(1) The fact that land has been used to sequester carbon dioxide; 

(2) The name of the State agency, local authority, and/or tribe with which the 

survey plat was filed, as well as the address of the Regional Environmental 

Protection Agency Office to which it was submitted; and 

GWPC Recommendations: No recommendation 

Rationale: Need for site-specific considerations and use of data 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on

the deed to the facility property or other similar document examined during a title search that the

land has been used to sequester CO2 on the deed to the facility property at the time of site closure.

Commenter Name: Michel Paque Letter ID: 0259

Commenter Organization: Ground Water Protection Council Comment ID: 24954

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

language; 4730 2.7.3 Reporting associated with closure and post-injection site care 

Comment: EPA Proposal: (3) The volume of fluid injected, the injection zone or zones into 

which it was injected, and the period over which injection occurred. 

(g) The owner or operator must retain for three years following site closure, 

records collected during the post-injection site care period. The owner or 

operator must deliver the records to the Director at the conclusion of the 

retention period, and the records must thereafter be retained at a location 
designated by the Director for that purpose. 

GWPC Recommendations: No recommendation 

Rationale: Need for site-specific considerations and use of data 

Response: The GS regulation at §146.93(g) requires the owner or operator to record a notation on

the deed to the facility property or other similar document examined during a title search that the

land has been used to sequester CO2 on the deed to the facility property at the time of site closure. 

Commenter Name: Donn Miller Letter ID: 0270

Commenter Organization: State of Oregon, Water Resources Department Comment ID: 22891

Comment: 146.93 Post-Injection Site Care and Site Closure. 

(e) We ask that the site closure reports be posted on-line. 

Response: EPA disagrees that the owner or operator should not be responsible for record retention

such as site closure reports. EPA believes that the requirements that the owner or operator retain for

ten years following site closure, records collected during the post-injection site care period at

§146.93(f) and §146.93(h) are appropriate for the post-injection and site closure period to ensure that

data are available to support non-endangerment demonstrations and to address any concerns that may

arise following site closure. This data will also support EPA's review of project data as part of the

adaptive rulemaking approach.

In response to the suggestion that the site closure reports be posted on-line, this information would

be part of the administrative record on the site, and specific options for access to those records would

be the decision of the permitting authority.

Commenter Name: Michele Schoepper Letter ID: 0503

Commenter Organization: American Petroleum Institute Comment ID: 21175

Comment: Clear guidelines also need to be established regarding when operators have met 

the performance standards that determine site closure. Specifically, the 

standard that the project no longer poses an endangerment to USDWs needs to be 

defined using reasonable site- specific criteria. 

Response: EPA is developing guidance to assist owners or operators in evaluating well plugging,

post-injection site care, and site closure requirements of 146.92 and 146.93. Additionally, the

guidance will assist Directors in evaluating proposed well plugging plans and post-injection site care

and site closure plans under 146.92 and 146.93. The guidance describes recommended approaches

for how an owner or operator could plug injection and monitoring wells; demonstrate the

appropriateness of an alternative post-injection site care time frame; perform post-injection

monitoring; demonstrate non endangerment; and perform site closure activities. The guidance will be

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

Commenter Name: Scott Anderson Letter ID: 0510

Commenter Organization: Environmental Defense Fund Comment ID: 21230

Comment: And my final point I've actually already made, which is that we suggest that you 

need to improve the standards for authorizing and site closure. 
Thank you. 

Response: As described above, EPA disagrees that the rule should set specific criteria. EPA believes

that many site-specific factors will influence the determination of when the CO2 plume and pressure

front no longer pose a risk of endangerment to USDWs. It is for this reason that EPA believes that

individual UIC Directors, in consultation with operators, will be in the best position to determine

whether additional post-injection site care is needed. EPA expects this decision to be made based on

relevant site data and in consultation with all potentially impacted parties. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, post-injection

site care, and site closure requirements of 146.92 and 146.93. Additionally, the guidance will assist

Directors in evaluating proposed well plugging plans and post-injection site care and site closure

plans under 146.92 and 146.93. The guidance describes recommended approaches for how an owner

or operator could plug injection and monitoring wells; demonstrate the appropriateness of an

alternative post-injection site care time frame; perform post-injection monitoring; demonstrate non

endangerment; and perform site closure activities. The guidance will be available at

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

Commenter Name: Steve Crookshank Letter ID: 0523

Commenter Organization: American Petroleum Institute (API) Comment ID: 21358

Comment: Clear guidelines also need to be established regarding when operators have met 

the performance standards that determine site closure. Specifically, the 

standard that the project no longer poses an endangerment to USDW's needs to be 

defined using reasonable risk based criteria. EPA should also reconsider its 

Response: EPA is developing guidance to assist owners or operators in evaluating well plugging,

post-injection site care, and site closure requirements of 146.92 and 146.93. Additionally, the

guidance will assist Directors in evaluating proposed well plugging plans and post-injection site care

and site closure plans under 146.92 and 146.93. The guidance describes recommended approaches

for how an owner or operator could plug injection and monitoring wells; demonstrate the

appropriateness of an alternative post-injection site care time frame; perform post-injection

monitoring; demonstrate non endangerment; and perform site closure activities. The guidance will be

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