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.Tennessee Valley Authority , 1101 Market Street, Chattanooga, Tennessee 37402

Richard L. Driggans

Vice President Environmental Science, Technology & Policy

December 17, 2008

Water Docket Environmental Protection Agency

Mailcode: 2822T 1200 Pennsylvania Avenue, NW Washington, DC 20460

Docket ID No. EPA-HQ-2008-0390

RE: FEDERAL REQUIREMENTS UNDER THE UNDERGROUND INJECTION CONTROL (UIC) PROGRAM FOR CARBON DIOXIDE (CO 2 ) GEOLOGIC SEQUESTRATION (GS) WELLS; PROPOSED RULE

As the nation’s largest public power provider, the Tennessee Valley Authority (TVA) generates electricity at 29 hydroelectric dams, 11 coal-fired plants, 6 combustion turbine sites, 3 nuclear plants, a pumped-storage hydropower plant, and 17 green power sites that employ wind turbines, methane gas, and solar panels. These assets currently provide electrical power to 158 local distributors that serve 8.8 million people and

650,000 businesses and industries in a seven-state service area.

TVA’s coal-fired plants and combustion turbines (CO 2 -emitting facilities) provide about 64 percent of this total generation of electrical energy to the Tennessee Valley Region of the Southeastern United States. As owner and operator of these facilities with responsibilities for meeting current and future power supply needs and as a Federal agency with resource stewardship responsibilities, TVA appreciates the opportunity to review and comment on this proposed rule that would (1) create a new category of injection wells (Category VI) under EPA’s Underground Injection Control (UIC) Program for protecting underground sources of drinking water (USDWs) and (2) establish Federal requirements for the underground injection of CO 2 for the purpose of geologic sequestration (GS). See 73 Fed. Reg. 43492 (July 25, 2008).

TVA offers the following comments on this proposed rule:

General Comment

1. TVA acknowledges the challenge of developing a rule to provide regulatory certainty for the GS of CO in order to foster industry adoption of carbon capture and storage (CCS) in the face of considerable technological and experiential uncertainty about safely injecting and sequestering the huge volumes of supercritical CO that would be required to meet the goals of future climate change legislation. In the face of such uncertainty, this rule is justifiably stringent for 2

2Water Docket - EPA Page 2

December 17, 2008

protecting USDWs, ecological resources, and the public. Because scale-up from experimental to fully operational wells will provide the experience necessary to have a rulemaking with the most appropriate protections, TVA requests that a provision be added to require periodic review (possibly every two years initially until sufficient operational experience is gained) and to revise the rule’s flexibility appropriately where justified. TVA agrees with EPA that the regulatory standard for permitting CO 2 GS wells should be the protection of USDWs, which must take precedence over the need to sequester CO 2 underground at any site. For this reason, TVA supports a stringent rule initially as long as a provision is made to revise the rule to incorporate operational experience as it is gained.

Specific Comments

1. Regulatory (“Director’s”) Discretion - TVA supports a flexible rule that vests in the Director the discretion to grant certain approvals. However, where the Director is provided such discretion (e.g., for imposing secondary containment, requesting additional testing, monitoring CO 2 fluxes in surface air and soil gas, changing the 50-year default post injection care requirement, shortening the notification period for plugging an injection well or approving site closure plans), the proposed rule should include factors that the Director must consider in exercising discretion.

2. Siting - The proposed rule provides the Director the discretion to require the owner or operator to identify and characterize additional (secondary) confining and containment zones above the primary (i.e., lowermost) confining zone to further impede vertical fluid movement and allow for pressure dissipation. There are situations that must require secondary containment, e.g., CO 2 GS well fields located in the vicinity of a designated sole-source aquifer or other aquifer widely used for water supply. Assurance of CO 2 containment must be near-absolute in such cases, and regulators must have discretion to require cap rock redundancy. As a further precaution, potential GS sites near sole-source aquifers, as well as those sites in high risk seismic locations, should initially be eliminated from consideration until sufficient experience with operational scale GS is gained.

As a related matter, at least for the near future, siting a fossil-fueled plant that utilizes GS near a sole-source aquifer should only be considered where the infrastructure is in place for transporting supercritical CO 2 to a distant injection well location. Because a large portion of the Nation’s fleet of fossil-fueled generating facilities were sited and built without consideration of CCS, there are considerable space, water supply, geologic, seismic, and financial constraints for retrofittingWater Docket - EPA Page 3

December 17, 2008

many existing facilities with this technology. Although the proposed rule does not require facilities to capture and/or sequester CO 2 , promulgation of this rule should acknowledge that GS of CO 2 will not be suitable at a large number of existing facilities and may be most applicable for new-generation facilities that are properly sited a priori for CCS.

3. Area of Review (AoR) - The proposed rule requested comment on requiring reevaluation of the site AoR on a periodic basis and the appropriateness of a 10 year minimum fixed frequency for AoR re-evaluat ion. TVA supports a re-evaluation frequency not to exceed 10 years. Periodic AoR re-evaluation will be needed given the enormous volumes of CO 2 that would be injected, the potentially high mobility of CO 2 in the subsurface, the lengthy timeframes likely for CO 2 GS operations, and the uncertainty of the original model-predicted AoR limits,especially where multiple injections might occur below the same aquifer (noncontiguous but merging CO 2 pressure fronts).

In practice, much of what is required in an AoR evaluation (e.g., well field monitoring, computational fluid dynamics model calibration/verification, and updated prediction of future limits of the CO 2 plume) will be performed on an ongoing basis to support well-field operation and monitoring. If after 10 years, updated modeling shows no significant change in AoR limits, the AoR re-evaluation should merely require presenting the latest modeling results and possibly confirming that no new penetrations have been identified and therefore no new corrective actions are necessary.

4. I njection Depth in Relation to USDWs - The proposed rule requested comment on alternative approaches that would allow injection between and/or above the lowermost USDW, and thus potentially allow for more areas to be available for GS while preventing USDW endangerment. Limiting CO 2 GS to geologic units below the lowest USDW is prudent and reasonable. Prohibiting injection between and/or above the lowermost USDW is essential to protecting valuable drinking water sources by avoiding unnecessary siting and operational risks. Once experience is gained with the long-term behavior and geologic containment of CO 2 , injectiondepths above the lowermost USDW may be considered appropriate on a sitespecific basis (e.g., where storage depth would be sufficient for maintaining CO 2 in a supercritical state and separate from USDWs).

5. Unspecified Operational Consequences - In the unfortunate event operational experience at a GS site shows the permitted geologic storage was ill advised and

that CO 2 injection from a fossil-fueled power plant sited and operated at (or transporting supercritical CO 2 to) that location must be terminated, TVA requests a provision be added to this rule to address what consequences, with regards to

resumed emissions of CO 2 , discontinuation of CCS would have for such a facility.Water Docket - EPA Page 4

December 17, 2008

TVA believes that a Class VI permitting pr ogram is reasonable and necessary before GS can be implemented at the operational scale necessary for mitigating power plant CO 2 emissions, and TVA applauds EPA for this initial effort to provide a regulatory framework and some degree of regulatory certainty for GS under the UIC program. TVA appreciates the opportunity to comment on EPA’s proposed rule and anticipates its comments will be useful in forging an effective and protective regulation. If you or other staff have comments or questions regarding these TVA comments, please call or email Michelle Cagley of my staff (865) 632-2072; amcagley@tva.gov.

Sincerely,

Richard L. DriggansLetter ID: 0145 Commenter: Richard Driggans Organization: Tennessee Valley Authority

Letter ID: 0145 Comment ID: 23147 Letter Lines: 59 to 77

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

Comment Code: 2400 1.8 Comments on EPA's adaptive rulemaking process

Comment: General Comment

1. TVA acknowledges the challenge of devel oping a rule to provide regulatory certainty for the GS of CO2 in order to foster industry adoption of carbon capture and storage (CCS) in the face of consid erable technological and experiential uncertainty about safely injecting an d sequestering the huge volumes of supercritical CO that would be required to meet the goals of future climate change legislation. In the face of such uncertainty, this rule is justifiably stringent for protecting USDWs, ecologi cal resources, and the public. Because scale-up from experimental to fully operational wells will provide the experience necessary to have a rulemaking with the most appropriate protections, TVA requests that a provision be added to require periodic review (possibly every two years initially until sufficient operational experience is gained) and to revise the rule’s flexibility appropriately where justified. TVA agrees with EPA that the regulatory standard for permitting CO2 GS wells should be the protection of USDWs, which must take pr ecedence over the need to sequester CO2 underground at any site. For this r eason, TVA supports a stringent rule initially as long as a provision is made to revise the rule to incorporate operational experience as it is gained.

Individual Response: EPA agrees that an adaptive approach to the UIC GS rulemaking is appropriate. The Agency plans to use such an appr oach to ensure that USDWs are protected from endangerment while making it possible to meet the potentially fast pace of GS deployment. EPA believes that an adaptive approach will allow regu latory development to proceed in time to meet the current and future demand for Class VI perm its while recognizing the need to: continue to gather data from pilot projects and other res earch as it becomes available; and to enhance understanding of the technical and administrative aspects of GS deployment, operation, and technology developments. EPA plans, every six year s, to collect and revi ew data on GS projects to determine whether the appropriate amount and types of information and appropriate documentation are being collected, and to determ ine if modifications to the requirements are appropriate or necessary.

However, the Agency cannot definitively predict that future requirements will be less stringent than those in the final GS rule. The Agency beli eves that the Class VI requirements appropriately address the unique challenges posed by large-sc ale GS–including large injection volumes, the

1relative buoyancy of CO2, its corro sivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility w ithin subsurface formations. Any changes implemented under the adaptive rulemaking would be based on technical information and data generated and collected during early GS projects or other research.

EPA believes that reevaluating the GS requireme nts every six years is appropriate to allow sufficient time for projects to be permitted, fo r State and Tribal programs to apply for and receive primacy, and for sufficient project data to be collected. For example, once the first GS projects are permitted, injection commences, and monitoring data are generated and analyzed, EPA can begin to review this data to verify the applicability and appropriateness of the requirements including the usefulness of AoR cal culation models, and the utility and design of monitoring plans and corrective action plans. As construction and operation of GS projects continue (e.g., as AoR reevaluati ons are conducted or when the first projects cease injecting), EPA will have additional opportunities to evaluate the requirements in the course of subsequent

reviews.

EPA believes that shorter review intervals, e.g., 2 years, as the commenter suggests, would not provide sufficient time for projects to be permitt ed, State and Tribal programs to apply for and receive primacy, and sufficient data to be collected. EPA clarifie s that, if early project data indicate before six years that revisions are ap propriate, EPA will publish new requirements prior

to then.

Letter ID: 0145 Comment ID: 23148 Letter Lines: 81 to 88

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

Comment: 1. Regulatory ("Director’s") Discretion - TVA supports a flexible rule that

vests in the Director the discretion to grant certain approvals. However, where the Director is provided such discretion (e.g., for imposing secondary containment, requesting additional testi ng, monitoring CO2 fluxes in surface air and soil gas, changing the 50-year defa ult post injection care requirement, shortening the notification period for pl ugging an injection well or approving site closure plans), the proposed rule s hould include factors that the Director must consider in exercising discretion.

Individual Response: The final GS rule includes a balance of specific criteria to be met by the owner or operator and areas of Directorial discretion and consider ations for how that discretion would be exercised. The Agency believes this ba lance allows for GS projects to be designed and permitted to address the unique, site-specific asp ects of each project, while providing consistency in permitting across the U.S.

EPA is developing guidances for States that describe the process of applying for and receiving primary enforcement authority (primacy) for GS Class VI wells under Section 1422 of SDWA,

2as well as the technical and administrative issu es on developing GS regul ations that are the equivalent of minimum federal criteria and requirements. The gui dance will describe areas of

Directorial discretion and consid erations for how that discre tion would be exercised. This guidance will be available on EPA’s website at http://water.epa.gov/type/groundwater /uic/wells_sequestration.cfm.

Letter ID: 0145 Comment ID: 23149 Letter Lines: 90 to 98

Comment Code: 3120 2.1.2 Need to identify additional confining and containment zones (seeking comment)

Comment: 2. Siting - The proposed rule provides th e Director the discretion to require the owner or operator to identify a nd characterize additional (secondary) confining and containment zones above th e primary (i.e., lowermost) confining zone to further impede vertical flui d movement and allow for pressure dissipation. There are situa tions that must require secondary containment, e.g., CO2 GS well fields located in the vicinity of a designated sole-source aquifer or other aquifer widely used for water supply. A ssurance of CO2

containment must be near-absolute in such cases, and regulators must have discretion to require cap rock redundancy. As a furt her precaution, potential

Individual Response: EPA retains the requirement to iden tify additional containment/confining zones, if required by the Di rector, as proposed (e.g., §146.83(b)). The Agency's decision is supported by commenters representing states, wate r associations, and an electric utility who assert that these requirements (at §146.83(b)) pr omote a flexible, risk-based, site-specific approach to characterizing and perm itting a site for GS projects.

The Agency believes that providing the Director di scretion will allow consideration of a range of sites for GS, based on site-specific conditions and ensure USDW protection. EPA believes that requiring appropriate site ch aracterization by the owner or operator (under §146.82) and providing an appropriate de gree of flexibility to the Director to evaluate site-specific geologic data will afford the greatest protec tion of USDWs from endangerment.

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regard ing characterizing the region al geology and hydrogeology of a proposed GS site as well as performing th e necessary geochemical, geomechanical, and geophysical analyses of the injection and confin ing zone. EPA expects that this guidance will assist permit writers in making an objective deci sion about requiring additional confining layers. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwat er/uic/wells_se questration.cfm.

Letter ID: 0145 Comment ID: 23150 Letter Lines: 98 to 114

3Comment Code: 3110 2.1.1 Proposed siting requirements (i.e., injection/confining zones, trapping mechanism)

Comment: discretion to require cap rock redundancy. As a furt her precaution, potential GS sites near sole-source aquifers, as we ll as those sites in high risk seismic locations, should initially be eliminated from consideration until sufficient experience with operational scale GS is gained.

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

that utilizes GS near a so le-source aquifer should only be considered where the infrastructure is in place for transpor ting supercritical CO2 to a distant injection well location. B ecause a large portion of the Nation’s fleet of fossil-fueled generating facilities were sited and built without consideration of CCS, there are considerable space, water supply, geologic, seismic, and financial constraints for retrofitting many existing facilities with this technology. Although the proposed rule does no t require facilities to capture and/or sequester CO2, promulgation of this rule should acknowledge that GS of CO2 will not be suitable at a large number of existing facilities and may be most applicable for new-generation faciliti es that are properly sited a priori

for CCS.

Individual Response: The GS requirements are designed to ensure protection of USDWs from endangerment by requiring that injection we lls are permitted, sited, constructed, operated, monitored, and plugged in a manner that does not endanger USDWs. GS in areas that may pose risks to USDWs, as assessed and identified by th e owner or operator and the Director during the site selection process, would not be permitted.

In response to the comment that GS should not be allowed in areas with high-risk for a seismic event, EPA clarifies that the GS rule does not allow GS to be performed in seismically active areas and requires that operators must submit information about the seismic history of and seismic sources near a proposed GS site (146.82( a)(3)(v)). This information, along with other required submissions, will be evaluated by the Director, who will determine the suitability of a potential project site for GS.

EPA clarifies that 146.82(a)(5) re quires prospective owners or operators to submit information on all USDWs (which would include sole source a quifers) within the AoR. The Director would consider this information and the potential impact of the GS project on any sole source aquifers in determining whether GS is acceptable.

Letter ID: 0145 Comment ID: 23152 Letter Lines: 116 to 133

Comment Code: 3530 2.2.3.1 AoR reevaluation fre quency (seeking comment)

4Comment: 3. Area of Review (AoR) - The proposed rule requested comment on requiring reevaluation of the site AoR on a periodic basis and the appropriateness of a 10 year minimum fixed frequency for Ao R re-evaluation. TVA supports a reevaluation frequency not to exceed 10 years. Periodic AoR re-evaluation will be needed given the enormous volumes of CO2 that would be injected, the potentially high mobility of CO2 in the subsurface, the lengthy timeframes likely for CO2 GS operations, and the uncertainty of the or iginal model-predicted AoR limits, especially where multiple injections might occur below the same aquifer (noncontiguous but merging CO 2 pressure fronts).

In practice, much of what is required in an AoR evaluation (e.g., well field monitoring, computational fluid dynamics model calibration/verification, and updated prediction of future limits of th e CO2 plume) will be performed on an on-going basis to support well-field ope ration and monitorin g. If after 10 years, updated modeling shows no significan t change in AoR limits, the AoR reevaluation should merely require presen ting the latest modeling results and possibly confirming that no new penetrations have been identified and therefore no new corrective actions are necessary.

Individual Response: EPA believes that reevaluations of the AoR every ten years may not be sufficient to appropriately model plume and pre ssure front movement, establish conditions for corrective action, and ensure pr otection of USDWs from endange rment. For these reasons, the Agency changed the minimum frequency for th e AoR reevaluation at §146.84(e) from 10 years to at least every 5 years in the final GS rule. EPA believes that this re vised 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 disc retion to require more frequent AoR reevaluation if he or she has reason to believe, based on site-specific inform ation, that a five-year reevaluation schedule is not sufficiently prot ective of USDWs.

EPA adds that if site monitoring data agr ees 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 ad equate based on site monitoring data.

Letter ID: 0145 Comment ID: 23153 Letter Lines: 135 to 141

Comment Code: 4322 2.4.4.1.1 Comments in favor of requiri ng injection below the lowermost

USDW

Comment: 4. Injection Depth in Relation to USDWs - The proposed rule requested comment on alternative approaches that would allow injection be tween and/or above the lowermost USDW, and thus potentially allow for more areas to be available for GS while preventing USDW endangerment. Limiti ng CO2 GS to geologic units below the

5lowest USDW is prudent and reasonable. Prohibiting injectio n between and/or

above the lowermost USDW is essential to protecting valuable drinking water sources by avoiding unnecessary siting a nd operational risks. Once experience

Individual Response: EPA agrees that protecting USDWs from endangerment must be a top priority. The Agency believes that there are limited circumstances where injection above the lowermost USDW can be performed in a manner that protects USDWs, 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 in jection depth requirement s for injection into nonUSDW formations above and/or between USDWs. The waiver approach requires the submission of extensive, site-specific information (in conj unction with the permit appl ication submission) to demonstrate that injection of CO2 into a non-US DW that is above or between USDWs can be done in a manner that is protective of USDWs. It establishes: 1) requirements specifying information that owners or operators must subm it, and Directors must consider, in consultation with PWSS Directors; 2) procedur es for public notice of a waiver application a nd for DirectorRegional Administrator communicat ion; 3) the waiver issuance process; and, 4) additional requirements that apply to owners or operators of Class VI wells granted a waiver of the injection depth requirements to ensure USDW protection above and below the injection zone.

EPA believes that the requirements at §146.95 w ill ensure USDW protection while providing flexibility to UIC Program Dir ectors and owners or operators who undertake CO2 injection for GS. The Agency believes this approach: 1) responds to concerns a bout 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) allo ws 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 injecti on depth variability thr ough a waiver process responds to concerns about future drinking water resource availability and the need to ensure that high quality water remains available in sufficien t quantities to supply dr inking water needs. For additional information on the waiver approach, pleas e 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: 0145 Comment ID: 23155 Letter Lines: 147 to 153

Comment Code: 5460 2.9.2 Comments on transfer of lia bility for long-term care

Comment Code: 5800 2.13 Comments on emergency and re medial response (40 CFR 146.94)

Comment: 5. Unspecified Operational Consequences - In the unfortunate event operational experience at a GS site shows the permitted geologic storage was ill advised and that CO2 injection from a fossil-fueled power plant sited and operated at (or transporting supercritical CO2 to) that location must be terminated, TVA requests a provision be added to this rule to address what consequences, with regards to resumed emissions of CO2, disc ontinuation of CCS would have for such a facility.

6Individual Response: EPA clarifies that EPA’s authority under the Safe Drinking Water Act is limited to and the focus of the GS regulation is on preventing USDW endangerment due to injection, and that any impacts to or procedures for fossil fuel pow er plants are ou tside the scope of the GS rule. EPA is, however, developing guidance on the development and implementation of emergency and remedial response plans for GS sites. To meet the requirements for developing an emergency and remedial response plan (speci fied at §146.94(a)), an owner or operator should identify people (in addition to the Director), such as first responders, w ho should be contacted in the event of an emergency associated with the we ll. EPA envisions that th e party that transports

the CO2 onsite should be notified as well.

See the final rule preamble for further discussion of EPA's final approach.

Letter ID: 0145 Comment ID: 23156 Letter Lines: 155 to 159

Comment Code: 1420 1.2.1.1 Support the GS rulemaking

Comment: TVA believes that a Class VI permitting program is reasonable and necessary before GS can be implemented at the operational scale necessary for mitigating power plant CO2 emissions, and TVA appla uds EPA for this initial effort to provide a regulatory framewor k and some degree of regulatory certainty for GS under the UIC program. TVA appreciates th e opportunity to comment on EPA’s

Individual Response: EPA agrees that the creation of a new injection well class (VI) under the existing UIC Program is necessary to enable the use of GS as a climate change mitigation technology in a manner that protects USDWs from endangerment. EPA agrees that the UIC Program, under the authority of the SDWA, provides a strong fram ework for regulating injection of CO2 for GS and adds that the GS regulati on tailors the UIC requirements to address the unique issues associated with large-scale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potenti al presence of impurities in captured CO2, and its mobility within subsurface geologic formations.

EPA acknowledges that GS falls within the broade r context of CCS and the need for regulatory clarity to ensure that USDWs are protected from endangerment. In develo ping the final GS rule,

the Office of Water coordinated with other Agency program offices and across federal agencies (e.g., with the Department of Energy; United Stat es Geological Survey; Bureau of Ocean Energy Management, Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of Land Management). The Agency continues to eval uate areas of potential applicability of other Federal environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and Recovery Act; the Comprehe nsive Environmental Response, Compensation, and Liability Act; and the Marine Protection, Resear ch and Sanctuaries Act to various aspects of GS and CCS. The Agency will continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies for owners or operators. For additional information, please see the discussion entitle d "How Does This Rulemaking Relate to Other Federal

Authorities and GS and CCS Activities?" in the preamble to the final GS rule.

78 Letter ID: 0145 Comment ID: 23157 Letter Lines: 141 to 145

Comment Code: 4322 2.4.4.1.1 Comments in favor of requiri ng 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: sources by avoiding unnecessary siting and operational risks. Once experience is gained with the long-term behavior a nd geologic containment of CO2, injection depths above the lowermost US DW may be considered appr opriate on a site-specific basis (e.g., where storage depth would be sufficient for maintaining CO2 in a supercritical state and se parate from USDWs).

Individual Response: EPA acknowledges that there are lim ited circumstances where injection above the lowermost USDW can be performe d 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 owne rs or operators can seek a waiv er of the Class VI injection depth requirements for injecti on into non-USDW formations a bove and/or between USDWs.

The waiver approach requires the submission of extensive, site-specific information (in conjunction with the permit application submission) to demonstrate that injection of CO2 into a

non-USDW that is above or be tween USDWs can be done in a manner that is protective of USDWs. The requirements are designed to ensure that the owner or opera tor, the Director, and the Regional Administrator consid er, on a site specific basis, the implications, benefits, and challenges associated with GS and ensuring water availability and USDW protection.

It establishes: 1) requirements specifying informa tion that owners or operators must submit, and

Directors must consider, in consultation with PW SS Directors; 2) procedures for public notice of a waiver application and for Director-Regiona l Administrator communicat ion; 3) the waiver issuance process; and, 4) additiona l requirements that apply to owne rs or operators of Class VI wells granted a waiver of the in jection depth requirements to en sure USDW protection above and below the injection zone. EPA believes that these requirements will ensure USDW protection while providing flexibility to UIC program Di rectors and owners or operators who undertake CO2 injection for GS.

For additional information on the waiver approa ch, please see the final rule and preamble, as well as EPA's responses to comments on the No tice of Data Availability and Request for

Comment.