This comment letter response contains two parts:   

(1) The original submittal from the commenter.

(2) A data base printout of EPA’s response to each point raised by the commenter.

Notes about the response letters:

• The response letters were generated by a data base used to track the content of all public

comment submittals and ensure that the Agency responds to each. Each comment letter

was assigned a Letter ID that corresponds to the last four digits of the docket number of the

original comment (as posted on www.regulations.gov).

• Each response letter includes: comment text; an EPA‐assigned comment code; and an

individual response. These are described and explained below.  

• The data base contains Comment text from the letters submitted by commenters.  

Many hard copy letters were scanned into electronic format for inclusion in the data

base. As a result, there may be some typographical errors attributable to optical

character recognition issues.  However, all original submittals were reviewed in the

process of drafting responses to ensure that the comment content was understood and

appropriately addressed.

• The content of each comment letter was divided into topic areas and assigned a unique

Comment ID.  Additionally, one or more Comment Codes (i.e., unique topic area ID) was

assigned to each discrete point raised by a commenter. This information was added to

the data base. To inform final rulemaking decisions, all comments and information

received on a given topic were reviewed by technical experts in each rule area (e.g., on

construction requirements).  

• Following decisions on the final rule requirements, Individual responses were drafted

by topic area to ensure completeness and consistency of the responses with the final

rule and other responses to similar comments.  Each discrete point made by a

commenter was given a unique response.

• Upon completion of comment responses, all information was entered into the data base.

Each letter response is a compilation of each comment and its individual response,

compiled in the order of the original comment letter.  As a result of this process, there is

repetition in the response text.  The Agency believes this approach ensures completeness

and attention to each comment letter that was submitted.   

• All comments in a topic area were reviewed, evaluated, and responded to concurrently.  

Responses on each topic area are compiled and are also available in the rulemaking docket.
11/17/08 DRAFT

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Paul R. Pike

Environmental Services

314.554.2388 (Phone)

314.554.4182 (Facsimile)

prpike@ameren.com

December 23, 2008

U.S. Environmental Protection Agency

Water Docket, Environmental

Protection Agency, Mailcode: 2822T

1200 Pennsylvania Ave., NW

Washington, DC 20460

Submitted on-line: www.regulations.gov

Docket No. No. EPA-HQ-OW-2008-0390

Re: Federal Requirements Under the Underground Injection Control Program for Carbon 

Dioxide Geologic Sequestration Wells, 73 Fed. Reg. 43492 (July 25, 2008)

To whom it may concern:

Ameren Corporation appreciates the opportunity to comment on the Environmental Protection 

Agency’s (“EPA”) Proposal to establish a regulatory framework for geologic sequestration 

(“GS”) of carbon dioxide (“CO2”) under the Underground Injection Control (“UIC”) Program 

pursuant to the Safe Drinking Water Act ("SDWA"). 73 Fed. Reg. 43492 (July 25, 2008). 

Ameren Corporation (or Ameren) is based in St. Louis, MO, and through its operating 

companies serves 2.4 million electric and nearly one million natural gas customers across a 

64,000-square-mile area in Illinois and Missouri. Ameren companies’ net generating capacity is 

more than 16,400 megawatts. Our power plants use a variety of fuels to generate electricity—

principally coal, nuclear, hydro and natural gas. In 2007, coal-fired generation accounted for 84 

percent of our total electric generation; 12 percent came from the company’s single-unit nuclear 

plant; 2 percent from natural gas-fired units; and 2 percent from hydroelectric plants. 

The Ameren family of companies operates through multiple subsidiaries in different regulatory 

environments. In Missouri, Ameren’s utility subsidiary, AmerenUE, generates electricity, 

delivers natural gas and electricity and is regulated by a state-appointed commission. Ameren is 

the parent company to three Illinois utilities (collectively referred to as the Ameren Illinois 

Utilities) which deliver natural gas and electricity and are regulated by a state-appointed 

commission. Ameren also owns a number of non-rate-regulated subsidiaries, including 

AmerenEnergy Resources, which is the holding company for some of Ameren’s non-rateregulated power marketing and generating companies. Regulation of GS under the UIC program

will have a direct impact on Ameren, particularly our fossil-fired facilities involved in the 
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2

production of electricity and we have a substantial interest in EPA's development of a realistic 

and cost-effective UIC program for Class VI CO2 GS wells

Ameren is a member of the Utility Solid Waste Activities Group (“USWAG”), the Edison 

Electric Institute (“EEI”), and the Electric Power Research Institute (“EPRI)”. We endorse the 

comments filed by USWAG, EEI, and EPRI. In addition, I provided oral and written testimony 

on behalf of USWAG at EPA’s October 2, 2008, public hearing on the proposed rules

Flexible Regulatory Scheme

Ameren generally supports the creation of Class VI, a new class of injection wells for CO2

injection and storage. We also appreciate the attempt that EPA has taken to bring "certainty" and 

"transparency" to the future CO2 underground injection regulatory regime. However, it is 

imperative that the Final Rule be flexible enough to deal with the current investigative phase and 

when large-scale commercial operations are in place. We recognize that GS has significant 

potential to be a major portion of any future CO2 emission reduction scheme, but that can only 

occur if the regulations adapt to the actual hazard posed by the technology which may not be 

fully understood until some time in the future.

Clearly the Agency understands the need for flexibility by allowing a Director to provide 

guidance on regulatory compliance. We understand that this can allow the regulatory framework 

to evolve; however, there also needs to be some definition and limits to that discretion so that the 

public and regulated community can provide comments on that guidance. This means that 

technical and financial aspects are considered in the development of guidance. 

We also recognize that the underlying basis for these regulations is the protection of underground 

sources of drinking water (“USDWs”), but we urges EPA to avoid blanket prohibitions or 

arbitrary absolutes in the Final Rule. It is impossible to know what methods or technology will 

be developed for injection and long-term storage of CO2 and the Agency should not prematurely 

preclude the use of specific types of sites or methods for Class VI CO2 injection. The Final Rule 

should allow a range of injection sites and methods, provided that the Owner or Operator can 

show that the injection and storage will be protective of USDWs.

State Issues

We believe that the Final Rule should include a process that will allow delegation as well as 

encourage adoption and implementation of the program by states. If there is to be a smooth 

implementation of the Class VI wells, it will mean working closely with State regulators who are 

familiar local concerns and can work with the regulated community to address those specific 

concerns. Associated with the State primacy issue is how to address cross-state boundaries. We 

feel that some injection activities will cross State boundaries and that the State in which the 

wellhead is located should consult and coordinate with the other impacted State(s). Duel or 

duplicative regulatory systems will only unnecessarily burden potential injection projects 

limiting the value of this overall program. A final aspect for the states will be the Agency’s 

ability to provide funding to the states to aid them in implementing the program. Some States 
11/17/08 DRAFT

3

will not have the adequate expertise or manpower to respond to the potential of this program and 

will need assistance to ensure that adequate staff is available.

Grandfathering

Ameren and many other companies are participating in the DOE Regional Carbon Sequestration 

Partnerships as well as individual projects and believe that it is important that wells developed 

solely for the purpose of demonstrating the viability of CO2 sequestration should be 

grandfathered into the Class VI program. This means that regardless of the original permitting 

status of the well, it can be eventually transition to Class VI. These “demonstration” wells may

have included requirements valuable to understand the process, but unnecessary for a routinely 

operated facility and those could be dropped in the transition. If necessary, the Director could 

identify why continued operation of the well necessitates additional requirements which the 

permitee would be allowed the opportunity to respond. 

Siting

Ameren understands that EPA must consider the potential impact of CO2 GS projects on USDWs 

and other pre-existing subsurface activities (e.g., natural gas storage operations). However, we 

believe that at this point, the imposition of prohibition on certain sites will limit the benefits of 

this program. The important criteria is protecting USDWs and meeting other applicable 

conditions for Class VI CO2 GS wells. As stated earlier, CO2 GS is still being developed for 

commercial scale use and methods may be developed to address all issues that would otherwise 

result in impacts on other subsurface activities. This means that there should not be a prohibition 

on injection of CO2 into coal seams (whether above or below the lowermost USDW) or into 

other formations such as basalts, salt domes, or shales. 73 Fed. Reg. at 43503. 

A related subject is the requirement to identify and characterize additional confining and 

containment zones above the primary (i.e., lowermost) confining zone that could further impede 

vertical fluid movement and allow for pressure dissipation – in effect, a "secondary containment" 

requirement. 73 Fed. Reg. at 43505-06. We believe that only in the most unusual situations 

would circumstances warrant the requirement of an additional protective layer and oppose the 

inclusion of a "secondary containment" requirement.

RCRA Issues

Ameren is concerned that the CO2 stream being regulated under the Safe Drinking Water Act 

(“SDWA”) may be wrongly classified under the Resource Conservation and Recovery Act

(“RCRA”). It should be unnecessary to label CO2 a waste or a commodity for purposes of 

proposing and implementing UIC regulations for its injection and storage, because sites should 

be developed based on site-specific conditions. However, the preamble includes a discussion of 

whether injected CO2 may be a hazardous waste, thus perhaps implying the assumption that CO2

is a solid waste to begin with. The preamble states: 

“Because the types of impurities and their concentrations in the CO2 stream are likely to 

vary by facility, coal composition, plant operating conditions, and pollution removal 
11/17/08 DRAFT

4

technologies, EPA cannot make a categorical determination as to whether injected CO2 is 

hazardous under RCRA.” 73 Fed. Reg. at 43503

First, we do not believe that it is the within the jurisdiction of the SDWA to evaluate the nature 

of a material, or if a waste determine whether it is hazardous or not. Secondly if we assume, for 

purposes of argument, that CO2 is “discarded” and exhibits a hazardous waste characteristic 

when injected for long-term sequestration, there are compelling policy reasons to exclude such 

activities from RCRA regulation. Subjecting these injection operations to regulation under a 

Class I UIC hazardous waste injection permit could expose all other waste management units at 

the facility, including units that are in no way related to the injection operations, to all of 

RCRA’s Subtitle C corrective action program. This is because a Class I UIC hazardous waste 

injection permit is classified as a RCRA “permit by rule” under RCRA’s hazardous waste permit 

program. See 40 C.F.R. §§ 270.1(c)(1)(i) and 270.64. Facilities that have obtained a RCRA 

permit by rule for the operation of a Class I UIC hazardous waste injection well are potentially 

subject to the full scope of RCRA’s corrective action program for all solid waste management 

units located at the facility. See EPA RCRA/Superfund Hotline Monthly Summary, "Corrective 

Action for UIC Wells," 9502.1986(07) (April 1986). The specter of RCRA corrective action is a 

significant economic and practical obstacle for any facility considering whether to seek a permit 

for a new Class VI well, as facility-wide RCRA corrective action is an administratively complex 

and exceedingly expensive undertaking.

The imposition of facility-wide RCRA corrective action is unwarranted because any well 

receiving a permit under the UIC Program for CO2 GS will be, by definition, protective of 

USDWs. EPA’s RCRA program has established a legally sound process, referred to as 

"contingent management," for the exclusion of materials from hazardous waste regulation when 

such materials are already subject to an alternate regulatory regime that ensures the wastes are 

managed in an environmentally protective manner. As discussed below, where the potential for 

mismanagement of a waste is already adequately addressed by another regulatory regime – as 

would be the case with the injection of CO2 under the Class VI UIC program – regulation of such 

materials under the RCRA’s hazardous waste program is duplicative and unwarranted. EPA has 

successfully employed the contingent management concept in various contexts where the 

Agency determined that other regulatory regimes adequately addressed any potential 

mismanagement scenarios related to certain materials; examples include regulation of used oil, 

mixed radioactive/hazardous waste, and military munitions. 

The D.C. Circuit has reviewed EPA's legal theory underlying the contingent management 

concept and found it to be a "permissible construction of the statute" – namely, that the statutory

definition of "hazardous waste" is predicated upon the risks posed by a solid waste when 

"improperly" managed; therefore, "where a waste might pose a hazard only under limited 

management scenarios, and other regulatory programs already address such scenarios, EPA is 

not required to classify a waste as hazardous waste subject to regulation under [RCRA] Subtitle 

C." Military Toxics Project v. EPA, 146 F.3d 948, 958 (D.C. Cir 1998) (emphasis added).

Even if such operations were deemed subject to RCRA regulation, including a RCRA permit by 

rule, EPA could – and should – establish a conditional exclusion from RCRA regulation for CO2

GS operations. Such an exclusion would be legally justified, consistent with the Agency's past 
11/17/08 DRAFT

5

promulgation of conditional exclusion rules, and would make sound policy sense by removing a 

potentially significant regulatory barrier to the commercial development of CO2 GS operations. 

Modeling

Ameren believes that any model used in evaluating Class VI CO2 GS project is acceptable 

provided that it is based on accepted science and has been validated, and as long as we if are 

using a proprietary model disclose, as necessary, the code assumptions, relevant equations, and 

scientific basis of the model. 

Area of Review and Corrective Action

Ameren will be required to invest a significant amount of time and resources in the initial 

delineation of the Area of Review (“AoR”), but we believe that requiring AoR reevaluations 

every ten years or at any other fixed period is unnecessary. A performance-based approach 

would be more appropriate, with reevaluation required upon occurrence of some triggering 

event; one example of a triggering event could be a significant deviation from previously

modeled scenarios, provided that the level of deviation that would require reevaluation is agreed 

to be the permitee and the regulating agency in the permitting process. 

We believe that use of the phrase “corrective action” to describe well plugging and repair risks 

confusion with the concept of corrective action under either RCRA or CERCLA. This potential 

confusion can lead to unwarranted negative associations with the phrase “corrective action,” and 

we would suggest abandoning this phrase and instead use a phrase such as “well plugging and 

repair.” We would then also support a phased approach to well plugging and repair (“corrective 

action”) for CO2 GS wells as contemplated in the Proposal and it should be available to all

Owners or Operators of CO2 GS wells rather than be available only at the discretion of the 

Director. 73 Fed. Reg. at 43507-08. 

A CO2 GS site may have an extensive AoR and requiring well plugging and repair to be 

complete for all wells in a CO2 GS AoR prior to commencement of the injection project would 

be unnecessary, and unrealistic. We instead support an approach that would require the Owner 

or Operator of a Class VI well to perform pre-injection well plugging and repair on only those 

wells within the portion of the AoR that would be intersected by the CO2 plume or pressure front 

during the initial years of injection. Well plugging and repair for the rest of the AoR should be 

allowed to take place as the injection project progresses, ensuring that, eventually, “all wells in 

the AoR that need corrective action [well plugging and repair] eventually receive it.” 73 Fed. 

Reg. at 43508.

Injection Well Operating Requirements

Ameren supports allowing injection between and/or above the lowermost USDW, provided that 

the Class VI wells can be shown that their operations will be protective of USDWs. 73 Fed. 

Reg. at 43512. This could be particularly important in areas of the country with deep USDWs, 

where an absolute requirement that Class VI wells be constructed beneath the lowermost USDW 

could render the program impractical. We also support this approach in areas where it can be 
11/17/08 DRAFT

6

shown that geologic conditions would prevent fluid movement into adjacent USDWs. Id. 

Therefore, we oppose an absolute prohibition on use of exempt aquifers for Class VI injection; 

again use of exempt aquifers could be permitted where the specific aquifer exemption criteria are 

satisfied. Id.

While hydraulic fracturing is not appropriate in all geologic settings, it should be an available 

option. For years, EOR operations have employed hydraulic fracturing to enlarge fractures in 

rock; hydraulic fracturing has proven an effective way to create permeability and increase well 

capacity with minimal risk to USDWs. This technique has been used for many years, and we 

believe that regulatory protocols could be established to ensure safe and effective hydraulic 

fracturing where appropriate for Class VI CO2 GS operations. Again, hydraulic fracturing would

only be used when the Owner or Operator can demonstrate that such fracturing will not 

jeopardize USDWs or other important subsurface activities

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 site-specific, 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. 

Public Participation

Ameren agrees that public participation is an important part of any CO2 GS project, but we urge 

EPA to require public participation after an application has been deemed complete but before it 

has been approved. We believe that the initial application will require some degree of 

interaction between an Agency and the permitee. Therefore, the best time to involve the public 

is when basic information needs have been fulfilled and there is a belief that the project can 

move proceed to permitting. The public can then voice their concerns or support based on the 

best available information on a project.

Ameren appreciates the opportunity to comment on this important rule and would welcome the 

opportunity to work further with the Agency. Please feel free to contact me with any questions.

Sincerely,

Paul R. Pike

Strategic Analyst-Environmental Services
Letter ID: 0198 

Commenter: Paul Pike 

Organization: Ameren Corporation 

Letter ID: 0198 Comment ID: 23936 Letter Lines: 47 to 50 

Comment Code: 1320 1.1.3 General comments about GS 

Comment: Regulation of GS under the UIC program will have a direct impact on Ameren, 

particularly our fossil-fired facilities involved in the production of 

electricity and we have a substantial interest in EPA's development of a 

realistic and cost-effective UIC program for Class VI CO2 GS wells 

Individual Response: EPA acknowledges the comment. EPA clarifies that the GS rule does not 

require any facilities to capture and/or sequester CO2. Please see the remainder of EPA’s 

responses to this comment for further details. For additional information on EPA’s final 

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

Letter ID: 0198 Comment ID: 23937 Letter Lines: 52 to 56 

Comment Code: 1000 1. General and Administrative Comments 

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

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

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

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

public hearing on the proposed rules 

Individual Response: EPA acknowledges the comment. Please see the remainder of EPA's 

responses to this comment, USWAG’s comment, EEI’s comment, and EPRI’s comment for 

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

final rule and preamble as well as the rulemaking docket. 

Letter ID: 0198 Comment ID: 23938 Letter Lines: 58 to 85 

Comment Code: 1250 1.1.1.4 Flexibility is needed (performance-based standards) 

Comment: FLEXIBLE REGULATORY SCHEME 

Ameren generally supports the creation of Class VI, a new class of injection 

wells for CO2 injection and storage. We also appreciate the attempt that EPA 

has taken to bring "certainty" and "transparency" to the future CO2 underground 

injection regulatory regime. However, it is imperative that the Final Rule be 

flexible enough to deal with the current investigative phase and when large1
scale commercial operations are in place. We recognize that GS has significant 

potential to be a major portion of any future CO2 emission reduction scheme, but 

that can only occur if the regulations adapt to the actual hazard posed by the 

technology which may not be fully understood until some time in the future. 

Clearly the Agency understands the need for flexibility by allowing a Director 

to provide guidance on regulatory compliance. We understand that this can allow 

the regulatory framework to evolve; however, there also needs to be some 

definition and limits to that discretion so that the public and regulated 

community can provide comments on that guidance. This means that technical and 

financial aspects are considered in the development of guidance. 

We also recognize that the underlying basis for these regulations is the 

protection of underground sources of drinking water ("USDWs"), but we urges EPA 

to avoid blanket prohibitions or arbitrary absolutes in the Final Rule. It is 

impossible to know what methods or technology will be developed for injection 

and long-term storage of CO2 and the Agency should not prematurely preclude the 

use of specific types of sites or methods for Class VI CO2 injection. The Final 

Rule should allow a range of injection sites and methods, provided that the 

Owner or Operator can show that the injection and storage will be protective of 

USDWs. 

Individual Response: The Agency believes that the Class VI requirements balance site-specific 

flexibility with USDW protection. Rather than setting performance or technology-based 

standards for GS projects, EPA is adopting a flexible approach, where operators of GS projects 

would develop and implement site-specific plans for delineating the AoR, testing and monitoring 

the site, performing corrective action, and post-injection site care. EPA believes that the plans—

which would be reviewed and approved by the Director and periodically updated throughout the 

life of the project—promote an ongoing dialogue between the operator and the Director that will 

encourage use of the most appropriate technologies for a particular project. 

EPA is developing guidances for States that describe the process of applying for and receiving 

primary enforcement authority (primacy) for GS Class VI wells under Section 1422 of SDWA, 

as well as the technical and administrative issues on developing GS regulations that are the 

equivalent of minimum federal criteria and requirements. The guidance will describe areas of 

Directorial discretion and considerations for how that discretion would be exercised. This 

guidance will be available on EPA’s website at 

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

EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS 

is conducted in a manner that protects USDWs from endangerment. Encouraging investment in 

CCS projects and facilitating deployment are outside the scope of the GS rulemaking. 

Letter ID: 0198 Comment ID: 23939 Letter Lines: 87 to 93 

Comment Code: 5600 2.11 Comments related to UIC Program primacy for Class VI wells 

2
Comment: STATE ISSUES 

We believe that the Final Rule should include a process that will allow 

delegation as well as encourage adoption and implementation of the program by 

states. If there is to be a smooth implementation of the Class VI wells, it 

will mean working closely with State regulators who are familiar local concerns 

and can work with the regulated community to address those specific concerns. 

Individual Response: EPA agrees with commenters on the importance of states having primacy 

for GS wells given the variety of geologic settings in which GS will be applied. EPA recognizes 

that State, Tribal, Territorial and DI UIC Program Directors are in the best position to evaluate 

the unique issues related to well depth, geology, and hydrogeology that are posed by a Class VI 

well. Some degree of flexibility is needed for Class VI wells because each decision made will be 

site-specific and conditions will differ from state to state. The GS rule balances the need for 

these site-specific decisions with the need for minimum standards to ensure national consistency. 

The Agency believes that it is important for states to use their unique efficiencies to promote 

adoption of this burgeoning and important technology, while assuring that USDWs are protected 

from endangerment through the UIC regulatory framework. EPA encourages states to accept 

primacy for Class VI, and believes that, due to the importance of implementing an effective, 

comprehensive, and seamless CCS program, States should be provided the flexibility to obtain 

primacy for Class VI only. 

Given the potential for CCS (encompassing capture, transportation, and geologic sequestration) 

to be an important part of a national priority to address climate change, EPA believes that 

providing states the flexibility to obtain primacy for Class VI wells independently of other well 

classes can help foster effective management of CCS. EPA believes that allowing independent 

Class VI primacy may encourage states to take responsibility for implementation of Class VI 

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

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

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

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

space ownership, land use rights, and surface access) for which states can call upon other 

authorities that exist at the state level (but outside UIC authority) to provide a more 

comprehensive CCS management approach. 

Letter ID: 0198 Comment ID: 23940 Letter Lines: 94 to 99 

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

ownership 

Comment: Associated with the State primacy issue is how to address cross-state 

boundaries. We feel that some injection activities will cross State boundaries 

and that the State in which the wellhead is located should consult and 

3
coordinate with the other impacted State(s). Duel or duplicative regulatory 

systems will only unnecessarily burden potential injection projects limiting the 

value of this overall program. A final aspect for the states will be the 

Individual Response: EPA acknowledges that CO2 plumes may cross state or even international 

boundaries and encourages cooperation and coordination among permitting authorities. The final 

Class VI GS rule, at §146.82(a)(2), requires the owner or operator to identify all State, Tribal, 

and Territorial boundaries within the AoR. Based on this information, the Director must provide 

written notification to all States, Tribes, and Territories to inform them of the permit application 

and ensure that they are involved in any necessary processes; this new requirement was added to 

the final rule at §146.82(b). The Agency encourages transparency in the permitting process and 

anticipates that State-State/State-Tribal communication on GS permitting will facilitate 

information sharing and encourage safe, protective projects. 

EPA clarifies that the Class VI permit would be issued by the permitting authority in the state 

where the wellhead is located. 

Letter ID: 0198 Comment ID: 23941 Letter Lines: 99 to 103 

Comment Code: 5600 2.11 Comments related to UIC Program primacy for Class VI wells 

Comment: value of this overall program. A final aspect for the states will be the 

Agency’s ability to provide funding to the states to aid them in implementing 

the program. Some States will not have the adequate expertise or manpower to 

respond to the potential of this program and will need assistance to ensure that 

adequate staff is available. 

Individual Response: EPA acknowledges that there may be technical and administrative 

challenges including resource concerns, and will work closely with the states to assist them in 

resolving funding issues or acquiring the resources, personnel, and training needed to address the 

unique technical challenges associated with GS. 

EPA will also incorporate Class VI wells into the UIC Program's grant allocation process. The 

States/Tribes/Territories must also demonstrate that they have adequate resources to implement 

the program through matching resources against those allocated by the UIC Program's grant 

allocation formula. Currently, primacy programs are required to meet a minimum of 25 percent 

matching requirement. 

Letter ID: 0198 Comment ID: 23942 Letter Lines: 105 to 117 

Comment Code: 2066 1.5.3.3 Grandfathering construction of Class V wells (seeking comment) 

Comment: GRANDFATHERING 

4
Ameren and many other companies are participating in the DOE Regional Carbon 

Sequestration Partnerships as well as individual projects and believe that it is 

important that wells developed solely for the purpose of demonstrating the 

viability of CO2 sequestration should be grandfathered into the Class VI 

program. This means that regardless of the original permitting status of the 

well, it can be eventually transition to Class VI. These "demonstration" wells 

may have included requirements valuable to understand the process, but 

unnecessary for a routinely operated facility and those could be dropped in the 

transition. If necessary, the Director could identify why continued operation 

of the well necessitates additional requirements which the permitee would be 

allowed the opportunity to respond. 

Individual Response: EPA agrees that, when the Regional Carbon Sequestration Partnership 

projects are no longer of an experimental nature, they should be re-permitted as Class VI wells 

and subject to the Class VI requirements if they are to be used for commercial-scale GS. 

EPA is providing for the construction of Class V experimental technology wells to be 

grandfathered per §146.81(c), provided the owner or operator can demonstrate to the Director 

that the wells were engineered and constructed to meet the requirements at §146.86(a) and 

ensure protection of USDWs, in lieu of requirements at §146.86(b) and §146.87(a). EPA 

understands based on reviews of several Class V pilot project permits, that many Class V 

experimental technology wells, including those used in the RCSP projects, are specifically 

designed for injection of CO2 and are being built to Class I non-hazardous well specifications, 

which should facilitate re-permitting as Class VI wells. 

EPA is preparing an addendum to UICPG #83 that describes the use of the Class V experimental 

technology well classification to clarify permitting for Class V wells. This addendum will 

address shifting of Class V experimental projects to full-scale GS projects and the future use of 

the Class V experimental technology well subclass for research and testing of new GS 

technologies. 

Letter ID: 0198 Comment ID: 23943 Letter Lines: 119 to 131 

Comment Code: 2163 1.6.3.1 Comments in favor of injection into unmineable coal seams 

Comment Code: 2200 1.6.4 Other formation types 

Comment: SITING 

Ameren understands that EPA must consider the potential impact of CO2 GS 

projects on USDWs and other pre-existing subsurface activities (e.g., natural 

gas storage operations). However, we believe that at this point, the imposition 

of prohibition on certain sites will limit the benefits of this program. The 

important criteria is protecting USDWs and meeting other applicable conditions 

for Class VI CO2 GS wells. As stated earlier, CO2 GS is still being developed 

for commercial scale use and methods may be developed to address all issues that 

would otherwise result in impacts on other subsurface activities. This means 

5
that there should not be a prohibition on injection of CO2 into coal seams 

(whether above or below the lowermost USDW) or into other formations such as 

basalts, salt domes, or shales. 73 Fed. Reg. at 43503. 

Individual Response: EPA agrees that GS into unmineable coal seams has the potential to allow 

sequestration while ensuring USDW protection from endangerment, as described by commenters 

citing the process of enhanced methane recovery. The final GS rule does not preclude injection 

into unmineable coal seams, or into basalts, salt domes, or shales, provided owners or operators 

can demonstrate that GS can be performed in a manner that protects USDWs from 

endangerment. The Agency clarifies that owners or operators of Class VI wells used for injecting 

CO2 into these formation types are subject to the same site characterization, well construction, 

operation, monitoring, post-injection site care and site closure requirements that are required of 

projects injecting into other formation types. 

EPA acknowledges that there are unknowns associated with GS, particularly regarding GS into 

formations such as coal seams, basalts, salt domes, or shales, which have been the subject of 

limited experimental projects in the past. For this reason, the Agency is using an adaptive 

approach to regulate GS injection. EPA will collect and review project data on early GS projects, 

including those that inject into various formation types, to determine whether the appropriate 

amount and types of information and documentation are being collected. EPA plans, every six 

years, to collect and review data on GS projects to determine whether the appropriate amount 

and types of information and appropriate documentation are being collected, and to determine if 

modifications to the requirements are appropriate or necessary. 

EPA clarifies that the final rule requires that injection for GS be into non-USDWs below the 

lowermost USDW; however, owners or operators may apply for a waiver from this requirement, 

as described in §146.95. For more information, see the discussion of waivers in the preamble to 

the final rule. 

Letter ID: 0198 Comment ID: 23944 Letter Lines: 133 to 139 

Comment Code: 3120 2.1.2 Need to identify additional confining and containment zones 

(seeking comment) 

Comment: A related subject is the requirement to identify and characterize additional 

confining and containment zones above the primary (i.e., lowermost) confining 

zone that could further impede vertical fluid movement and allow for pressure 

dissipation - in effect, a "secondary containment" requirement. 73 Fed. Reg. at 

43505-06. We believe that only in the most unusual situations would 

circumstances warrant the requirement of an additional protective layer and 

oppose the inclusion of a "secondary containment" requirement. 

Individual Response: EPA believes that the Class VI requirements, including the level of site 

characterization required under §§146.82 and 146.83, appropriately address the unique 

challenges posed by large-scale GS including large injection volumes, the relative buoyancy of 

6
CO2, its corrosivity in the presence of water, the potential presence of impurities in captured 

CO2, and its mobility within subsurface geologic formations. EPA acknowledges that such 

additional zones may not be needed in all circumstances, and clarifies that this requirement is at 

the Director's discretion, based on his or her understanding of a particular site. The Agency 

believes that in some geologic settings, the presence and identification of additional confining 

and containment zones above the primary (i.e., lowermost) confining zone can improve USDW 

protection. These formations could further impede vertical fluid movement, allow for pressure 

dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also 

affording the greatest protection of USDWs from endangerment. 

Letter ID: 0198 Comment ID: 23945 Letter Lines: 141 to 210 

Comment Code: 1630 1.3.3 RCRA/hazardous waste issues (seeking comment) 

Comment: RCRA Issues 

Ameren is concerned that the CO2 stream being regulated under the Safe Drinking 

Water Act ("SDWA") may be wrongly classified under the Resource Conservation and 

Recovery Act ("RCRA"). It should be unnecessary to label CO2 a waste or a 

commodity for purposes of proposing and implementing UIC regulations for its 

injection and storage, because sites should be developed based on site-specific 

conditions. However, the preamble includes a discussion of whether injected CO2 

may be a hazardous waste, thus perhaps implying the assumption that CO2 is a 

solid waste to begin with. The preamble states: 

"Because the types of impurities and their concentrations in the CO2 

stream are likely to vary by facility, coal composition, plant operating 

conditions, and pollution removal technologies, EPA cannot make a 

categorical determination as to whether injected CO2 is hazardous under 

RCRA." 73 Fed. Reg. at 43503 

First, we do not believe that it is the within the jurisdiction of the SDWA to 

evaluate the nature of a material, or if a waste determine whether it is 

hazardous or not. Secondly if we assume, for purposes of argument, that CO2 is 

"discarded" and exhibits a hazardous waste characteristic when injected for 

long-term sequestration, there are compelling policy reasons to exclude such 

activities from RCRA regulation. Subjecting these injection operations to 

regulation under a Class I UIC hazardous waste injection permit could expose all 

other waste management units at the facility, including units that are in no way 

related to the injection operations, to all of RCRA’s Subtitle C corrective 

action program. This is because a Class I UIC hazardous waste injection permit 

is classified as a RCRA "permit by rule" under RCRA’s hazardous waste permit 

program. See 40 C.F.R. §§ 270.1(c)(1)(i) and 270.64. Facilities that have 

obtained a RCRA permit by rule for the operation of a Class I UIC hazardous 

waste injection well are potentially subject to the full scope of RCRA’s 

corrective action program for all solid waste management units located at the 

7
facility. See EPA RCRA/Superfund Hotline Monthly Summary, "Corrective Action 

for UIC Wells," 9502.1986(07) (April 1986). The specter of RCRA corrective 

action is a significant economic and practical obstacle for any facility 

considering whether to seek a permit for a new Class VI well, as facility-wide 

RCRA corrective action is an administratively complex and exceedingly expensive 

undertaking. 

The imposition of facility-wide RCRA corrective action is unwarranted because 

any well receiving a permit under the UIC Program for CO2 GS will be, by 

definition, protective of USDWs. EPA’s RCRA program has established a legally 

sound process, referred to as "contingent management," for the exclusion of 

materials from hazardous waste regulation when such materials are already 

subject to an alternate regulatory regime that ensures the wastes are managed in 

an environmentally protective manner. As discussed below, where the potential 

for mismanagement of a waste is already adequately addressed by another 

regulatory regime -- as would be the case with the injection of CO2 under the 

Class VI UIC program -- regulation of such materials under the RCRA’s hazardous 

waste program is duplicative and unwarranted. EPA has successfully employed the 

contingent management concept in various contexts where the Agency determined 

that other regulatory regimes adequately addressed any potential mismanagement 

scenarios related to certain materials; examples include regulation of used oil, 

mixed radioactive/hazardous waste, and military munitions. 

The D.C. Circuit has reviewed EPA's legal theory underlying the contingent 

management concept and found it to be a "permissible construction of the 

statute" -- namely, that the statutory definition of "hazardous waste" is 

predicated upon the risks posed by a solid waste when "improperly" managed; 

therefore, "where a waste might pose a hazard only under limited management 

scenarios, and other regulatory programs already address such scenarios, EPA is 

not required to classify a waste as hazardous waste subject to regulation under 

[RCRA] Subtitle C." Military Toxics Project v. EPA, 146 F.3d 948, 958 (D.C. Cir 

1998) (emphasis added).Even if such operations were deemed subject to RCRA 

regulation, including a RCRA permit by rule, EPA could -- and should -- 

establish a conditional exclusion from RCRA regulation for CO2 GS operations. 

Such an exclusion would be legally justified, consistent with the Agency's past 

promulgation of conditional exclusion rules, and would make sound policy sense 

by removing a potentially significant regulatory barrier to the commercial 

development of CO2 GS operations. 

Individual Response: EPA agrees CO2 itself is not listed as a hazardous substance under 

CERCLA; however, the CO2 stream may contain a listed hazardous substance (such as mercury) 

or may mobilize substances in the subsurface that could react with ground water to produce 

listed hazardous substances (such as sulfuric acid). Whether such substances may result in 

CERCLA liability from a sequestration facility depends entirely on the composition of the 

specific CO2 stream and the environmental media in which it is stored (e.g., soil or ground 

water). CERCLA exempts from liability, under CERCLA section 107, 42 U.S.C. 9607, certain 

8
“federally permitted releases” (FPR) as defined in CERCLA, 42 U.S.C. 9601(10). Class VI 

permits will need to be carefully structured to ensure that they prevent potential releases from the 

well which are outside the scope of the Class VI permit. 

Under the final GS rule, owners or operators will need to determine whether the CO2 stream is 

hazardous under EPA’s RCRA regulations, and if so, any injection of the hazardous CO2 stream 

may only occur in a Class I hazardous waste injection well under 40 CFR Part 146 Subpart G. 

Conversely, Class VI wells cannot be used for the co-injection of RCRA hazardous wastes (i.e., 

hazardous wastes that are injected along with the CO2 stream). 

With respect to RCRA, EPA has decided to initiate a separate proposed rulemaking specifically 

to examine the issue of RCRA applicability to CO2 streams being geologically sequestered, 

including the possible option of a conditional exemption from the RCRA requirements for CO2 

GS in Class VI wells. EPA will consider these comments as part of its development of that 

proposal. The Agency will consider issues particular to RCRA in the context of that separate 

rulemaking, and recommends that the commenter read that proposed rule when it is published. 

The Agency notes that commenters who wish to submit comments on the RCRA proposal will 

need to do so during the comment period for that rule. Finally, EPA also notes that the final GS 

rule, which adds new regulations for Class VI wells under the Safe Drinking Water Act 

(SDWA), is not making any changes to the RCRA regulations. 

Letter ID: 0198 Comment ID: 23946 Letter Lines: 212 to 217 

Comment Code: 3350 2.2.1.5 Use of proprietary models for GS sites (seeking comment) 

Comment: MODELING 

Ameren believes that any model used in evaluating Class VI CO2 GS project is 

acceptable provided that it is based on accepted science and has been validated, 

and as long as we if are using a proprietary model disclose, as necessary, the 

code assumptions, relevant equations, and scientific basis of the model. 

Individual Response: EPA agrees with commenters that available proprietary models may meet 

the complex needs for calculating the AoRs of GS sites, and shares their concern about the need 

to evaluate the inputs and assumptions used. EPA will allow the use of proprietary models in 

meeting the requirements for the GS regulation, as long as GS well operators using a proprietary 

model clearly disclose, to the Director's satisfaction, the code assumptions, relevant equations, 

and scientific basis. EPA adds that its Confidential Business Information requirements at 40 CFR 

144.5 will apply to the use of proprietary models. 

In response to comments suggesting that history matching or validation of these models is 

needed, EPA believes this is true for any model. EPA notes that the GS rule requires at 

§146.84(e) that the AoR be reevaluated to verify the CO2 plume is moving as predicted and to 

allow for necessary revisions to the AoR and corrective action, testing and monitoring, injection 

well plugging, post-injection site care and site closure, and emergency and remedial response 

plans. EPA clarifies, however, that the Agency will not perform independent validation of 

9
individual modeling products. 

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. 

Letter ID: 0198 Comment ID: 23947 Letter Lines: 219 to 229 

Comment Code: 3530 2.2.3.1 AoR reevaluation frequency (seeking comment) 

Comment: AREA OF REVIEW AND CORRECTIVE ACTION 

Ameren will be required to invest a significant amount of time and resources in 

the initial delineation of the Area of Review ("AoR"), but we believe that 

requiring AoR reevaluations every ten years or at any other fixed period is 

unnecessary. A performance-based approach would be more appropriate, with 

reevaluation required upon occurrence of some triggering event; one example of a 

triggering event could be a significant deviation from previously modeled 

scenarios, provided that the level of deviation that would require reevaluation 

is agreed to be the permitee and the regulating agency in the permitting 

process. 

Individual Response: EPA believes that periodic AoR reevaluation at a set frequency is 

necessary to ensure protection of USDWs from endangerment and address the uncertainties 

inherent in predictive modeling. Periodic AoR reevaluations at §146.84(e) ensure that a 

deliberate effort is made to verify, based on monitoring and operational data, that the CO2 plume 

is moving within the subsurface as predicted. EPA believes that less frequent reevaluations may 

not be sufficient to appropriately model plume and pressure front movement, establish conditions 

for corrective action, and ensure protection of USDWs from endangerment. 

EPA clarifies that if site monitoring data agrees with the existing AoR delineation, a model 

recalibration may not be necessary, and the AoR reevaluation may consist of a demonstration 

that the current AoR delineation is adequate based on site monitoring data. 

Letter ID: 0198 Comment ID: 23948 Letter Lines: 231 to 240 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 3400 2.2.2 Corrective Action 

Comment: We believe that use of the phrase "corrective action" to describe well plugging 

and repair risks confusion with the concept of corrective action under either 

RCRA or CERCLA. This potential confusion can lead to unwarranted negative 

10
associations with the phrase "corrective action," and we would suggest 

abandoning this phrase and instead use a phrase such as "well plugging and 

repair." We would then also support a phased approach to well plugging and 

repair ("corrective action") for CO2 GS wells as contemplated in the Proposal 

and it should be available to all Owners or Operators of CO2 GS wells rather 

than be available only at the discretion of the Director. 73 Fed. Reg. at 

43507-08. 

Individual Response: EPA notes that the term "corrective action" at §146.84(d) has been used 

to describe the process of addressing improperly plugged wells in the AoR of injection wells 

since the inception of the UIC Program, e.g., at §146.7 and §146.64. While EPA is aware that the 

term has a different meaning under RCRA and CERCLA, this has not caused confusion in the 

past. The alternative term, "well plugging," suggested by the commenter is reserved for injection 

well plugging as indicated at §146.92. 

Letter ID: 0198 Comment ID: 23949 Letter Lines: 242 to 251 

Comment Code: 3630 2.2.4.1 Comments in favor of allowing phased corrective action 

Comment: A CO2 GS site may have an extensive AoR and requiring well plugging and repair 

to be complete for all wells in a CO2 GS AoR prior to commencement of the 

injection project would be unnecessary, and unrealistic. We instead support an 

approach that would require the Owner or Operator of a Class VI well to perform 

pre-injection well plugging and repair on only those wells within the portion of 

the AoR that would be intersected by the CO2 plume or pressure front during the 

initial years of injection. Well plugging and repair for the rest of the AoR 

should be allowed to take place as the injection project progresses, ensuring 

that, eventually, "all wells in the AoR that need corrective action [well 

plugging and repair] eventually receive it." 73 Fed. Reg. at 43508. 

Individual Response: EPA acknowledges the commenter’s support of phased corrective action 

and agrees that phased corrective action may provide many benefits to a project including, but 

not limited to, spreading the burden of cost, avoiding delays in project start-up, allowing for use 

of future, improved corrective action techniques and addressing unanticipated changes in the 

movement of the CO2 plume or pressure front. EPA believes that the phased corrective action 

approach is appropriate for GS projects, and retained it at §146.84(b)(2)(iv) in the final GS 

regulation. 

Letter ID: 0198 Comment ID: 23950 Letter Lines: 253 to 264 

Comment Code: 4324 2.4.4.1.2 Comments opposed to requiring injection below the lowermost 

USDW 

Comment Code: 4410 2.4.4.3.1 Comments in favor of allowing injection above/between 

USDWs in certain circumstances 

Comment Code: 4460 2.4.4.4.1 Comments in favor of allowing aquifer exemptions in certain 

11
circumstances 

Comment: INJECTION WELL OPERATING REQUIREMENTS 

Ameren supports allowing injection between and/or above the lowermost USDW, 

provided that the Class VI wells can be shown that their operations will be 

protective of USDWs. 73 Fed. Reg. at 43512. This could be particularly 

important in areas of the country with deep USDWs, where an absolute requirement 

that Class VI wells be constructed beneath the lowermost USDW could render the 

program impractical. We also support this approach in areas where it can be 

shown that geologic conditions would prevent fluid movement into adjacent USDWs. 

Id. Therefore, we oppose an absolute prohibition on use of exempt aquifers for 

Class VI injection; again use of exempt aquifers could be permitted where the 

specific aquifer exemption criteria are satisfied. Id. 

Individual Response: EPA acknowledges that there are limited circumstances where injection 

above the lowermost USDW can be performed in a manner that protects USDWs from 

endangerment, as long as appropriate protections are in place. The final GS rule at §146.95 

establishes a process by which owners or operators can seek a waiver of the Class VI injection 

depth requirements for injection into non-USDW formations above and/or between USDWs. The 

final rule also establishes limited circumstances under which expansions of the areal extent of 

aquifer exemptions may be granted for owners or operators of Class II EOR/EGR wells 

transitioning to Class VI injection for GS. 

EPA believes that these requirements will ensure USDW protection while providing flexibility to 

UIC program Directors and owners or operators who undertake CO2 injection for GS. The 

Agency believes this approach: 1) responds to concerns about local and regional geologic storage 

capacity limitations imposed by the proposed injection depth requirements; 2) allows for a more 

site-specific assessment of injection depth for GS projects; 3) accommodates injection into 

different formation types; 4) allows for injection of CO2 for GS into non-USDWs above and/or 

between USDWs when appropriate and where it can be demonstrated that USDWs will be 

protected; and 5) responds to concerns about the use of aquifer exemptions for GS. Finally, 

EPA’s approach to addressing injection depth variability through a waiver process responds to 

concerns about future drinking water resource availability and the need to ensure that high 

quality water remains available in sufficient quantities to supply drinking water needs. For 

additional information on the waiver approach, please see the final rule and preamble, as well as 

EPA's responses to comments on the Notice of Data Availability and Request for Comment. 

Letter ID: 0198 Comment ID: 23952 Letter Lines: 266 to 275 

Comment Code: 4120 2.4.1.2 Allowing hydraulic fracturing during GS (seeking comment) 

Comment: While hydraulic fracturing is not appropriate in all geologic settings, it 

should be an available option. For years, EOR operations have employed 

hydraulic fracturing to enlarge fractures in rock; hydraulic fracturing has 

proven an effective way to create permeability and increase well capacity with 

12
minimal risk to USDWs. This technique has been used for many years, and we 

believe that regulatory protocols could be established to ensure safe and 

effective hydraulic fracturing where appropriate for Class VI CO2 GS operations. 

A gain, hydraulic fracturing would only be used when the Owner or Operator can 

demonstrate that such fracturing will not jeopardize USDWs or other important 

subsurface activities 

Individual Response: The final rule allows the use of hydraulic fracturing at GS sites, where 

approved by the Director. Hydraulic fracturing is one of several stimulation technologies 

available to improve wellbore and formation injectivity. 

EPA clarifies that all stimulation, including hydraulic fracturing, must be approved by the 

Director. Owners or operators must submit a proposed stimulation program as part of the permit 

application under §146.82(a)(9); the plan must demonstrate that any stimulation activities will 

not compromise the integrity of the confining zone. The Director will evaluate the owner or 

operator's proposed stimulation plan in the context of all information about the site, and the 

owner or operator must perform stimulation only as approved. 

The final rule at §146.91(d)(2) also requires that the owner or operator notify the Director 30 

days before performing stimulation during the operational phase of a GS project; this will 

provide an additional opportunity for the Director to review the owner or operator's plans for 

stimulation and add other requirements as needed. EPA clarifies that UIC regulations prohibit 

fracturing of the confining zone at any time during injection or stimulation in order to protect 

USDWs from endangerment. 

Letter ID: 0198 Comment ID: 23953 Letter Lines: 277 to 291 

Comment Code: 5240 2.8.2.2 Post injection timeframe (seeking comment) 

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. 

Individual Response: EPA agrees with commenters that there will be circumstances where it 

13
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. 

Letter ID: 0198 Comment ID: 23954 Letter Lines: 293 to 306 

Comment Code: 5520 2.10.1 Appropriateness of existing public participation requirements 

(Part 25 and Part 124) for GS (seeking comment) 

Comment: PUBLIC PARTICIPATION 

Ameren agrees that public participation is an important part of any CO2 GS 

project, but we urge EPA to require public participation after an application 

has been deemed complete but before it has been approved. We believe that the 

initial application will require some degree of interaction between an Agency 

and the permitee. Therefore, the best time to involve the public is when basic 

information needs have been fulfilled and there is a belief that the project can 

move proceed to permitting. The public can then voice their concerns or support 

based on the best available information on a project. 

Ameren appreciates the opportunity to comment on this important rule and would 

welcome the opportunity to work further with the Agency. Please feel free to 

contact me with any questions. 

14
15

Individual Response: The Agency believes that public participation is an important part of the 

UIC permitting process and wants to ensure wide access to decision-making processes and 

information on projects that may affect the public. GS permitting authorities must follow the 

existing public participation requirements for UIC permits as specified in 40 CFR Part 124. 

These regulations lay out the procedures for decision making and include requirements such as 

requiring the Director to notify the public regarding the availability of the draft permit and allow 

him or her to require a public hearing on the draft permit. EPA encourages operators and 

permitting agencies to begin involving the public by providing information as early in the 

process as possible. Encouraging public participation allows the permitting authority to 

understand public viewpoints, preferences, and concerns about the project, which might help 

avoid public misperceptions about the nature and safety of GS projects and forestall resistance 

later in the permitting effort.