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.Letter ID: 0131

Commenter: Carl Carlsson Organization: SUEZ Energy Generation NA, LLC

Letter ID: 0131 Comment ID: 21524 Letter Lines: 49 to 52

Comment Code: 1330 1.1.3.1 Support use of GS in general

Comment: As the owner of power generation faci lities, SEGNA respectfully submits the following comments for consideration by EP A. SEGNA supports efforts to curb greenhouse gas emissions, including research and investment in carbon capture and sequestration (CCS) technology.

Individual Response: EPA acknowledges the comment. Pleas e see the remainder of EPA’s responses to this comment for further deta ils. For additional information on EPA’s final regulatory approach, please see the final rule and preamble as well as the rulemaking docket.

Letter ID: 0131 Comment ID: 21525 Letter Lines: 54 to 64

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

Comment: General Comments

Effort should be made, to the extent practicable, to keep provisions for Underground Injection Contro l (UIC) of CO2 consistent with already known and understood UIC principles and regulations . Care should be taken to avoid overestimating the risks associated with GS, in order to ensure that the final rules are not excessively burdensome or co mplex. Of course, the rules must simultaneously ensure adequate protection of human health and the environment. However, excessive, complex regulatory re quirements have the potential to limit development of a technology that will be critical to our efforts to address climate change effectively, adding significantly to costs for a program that will already result in significant additional costs to th e energy sector, industry and consumers.

Individual Response: EPA disagrees that the requirements in the GS rule overstate the risk associated with GS. The UIC Program, under th e authority of the SDWA, provides a strong framework for regulating inje ction of CO2 for GS; the GS regulation tailors the UIC requirements to address the unique issues asso ciated with large-sc ale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic

formations.

EPA recognizes the importance of providing cl ear, flexible, scalable, and appropriate regulations. EPA believes that th e GS regulation will provide certa inty to industry and the public by providing consistency in requirements acr oss the U.S. and transparency about what requirements apply to owners or operators.

1EPA clarifies that the Class VI GS requirements are designed to ensure that, where deployed, GS is conducted in a manner that protects USDWs fr om endangerment. Encouraging investment in CCS projects and facilitating deployment are outside the scope of the GS rulemaking.

Letter ID: 0131 Comment ID: 21526 Letter Lines: 66 to 75

Comment Code: 1655 1.3.5.1 Concerns about Lake Nyos a nd Mammoth Mountain-type events

Comment Code: 1680 1.3.8 Don't overstate ris k, don't stigmatize CO2

Comment: Risks Associated with CO2 GS SEGNA agrees that all potential risks associ ated with geological sequestration of CO2 should be addressed, and that the pub lic must be adequately informed. However, references to the large and rapi d releases of CO2 fr om volcanic lakes, as occurred in Cameroon in the 1980's, must be presented carefully to more clearly demonstrate that geological sequestration--deep underground and under confining strata--is a completely different process and does not represent a risk to human health and the environment compar able to the referenced incident in Cameroon. The language in any subsequent documents issued by EPA should make this point more forcefully to avoid public confusion regardi ng the actual risk.

Individual Response: The Agency believes it appropriately characterized the limnic eruption at Lake Nyos as a rare and naturally-occurring lake turnover event that is ch aracteristic of stratified

lakes in warm climates. The event at Lake N yos, during which naturally-occurring CO2 trapped

at the bottom of the Lake was released to the atmosphere, is not a valid analogue for GS. The preamble highlighted differences between the lithologic reservoirs that may serve as storage formations for CO2 and the processes occurring at Lake Nyos and other st ratified tropical lakes (73 FR 43498).

Letter ID: 0131 Comment ID: 21527 Letter Lines: 77 to 82

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

Comment: CO2 as a Hazardous Waste Regarding the question of ch aracterizing CO2 streams to determine if they need to be regulated as a hazardous waste, SEGNA feels that it is de sirable to provide regulatory clarity on this issue, and therefore it is appropr iate to consider, either as part of the rule or as a separate rulemaking, a categorical exemption for CO2

streams.

Individual Response: EPA agrees that any requirements for the CO2 stream should be clearly identified. EPA received many comments regardi ng the applicability of the RCRA regulations

and statute to CO2 streams that are geologically sequestered unde r the final Class VI UIC well requirements. As a result, EPA has decided to initiate a separate proposed rulemaking specifically to examine the issue of RCRA appl icability to CO2 streams being geologically

2sequestered, 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 pa rticular 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 comment ers who wish to submit comments on the RCRA proposal will need to do so during the comment pe riod for that rule. Finall y, EPA also notes that

the final GS rule, which adds ne w regulations for Class VI wells under the Safe Drinking Water Act (SDWA), is not making any changes to the RCRA regulations.

EPA clarifies that the GS rule requires owner or operators of Class VI we lls to characterize their injection stream prior to injection, and throughout the operational life of the injection facility. Since the GS rule, at §146.81(d), prohibits CO2 st reams that meet the definition of a hazardous waste under 40 CFR part 261, owners or operators w ill need to characterize their CO2 stream as part of their permit application to determine if the injectate is a RCRA hazardous waste. If so, injection may only occur in a Class I hazardous waste injection well.

Letter ID: 0131 Comment ID: 21528 Letter Lines: 84 to 91

Comment Code: 2300 1.7 Comments on the Alternatives Considered

Comment: Proposed Regulatory Alternatives SEGNA agrees that options 1 and 4 (" Non-Specific Requirements Approach" and "Highly Specific Requirements Approach", respectively) are not appropriate for the reasons stated by EPA. Alternativ e 3, "Tailored Requirements Approach" suggested by EPA might be the best altern ative since it builds on the existing UIC regulatory framework, though flexibility re garding specific program elements should be considered on a case-by-case ba sis, as appropriate, pursuant to the "General Requirements A pproach" under Alternative 2.

Individual Response: EPA agrees with the commenters that Regulatory Alternative 3 is appropriate. The technical requirements in Alte rnative 3 (and the final GS rule) build upon the long-standing UIC regulatory framework for deep we lls and are appropriately tailored to address the unique nature of full-scale CO2 GS, includi ng the volumes of CO2 to be injected, the buoyant and mobile nature of the injectate, and its corrosivity in the presence of water.

Even though the Agency did not choose Alternatives 1 or 2, EP A agrees that flexibility is important to accommodate the varied conditions that may be encountered at GS sites while ensuring the protection of USDWs. The regula tion provides flexibility for selection of appropriate sites and target formations ( under §146.82), well construc tion specifics (under §146.86), and testing and monitoring regimes ( under §146.90), provided the owner or operator can demonstrate that the injection and storag e will not endanger USDWs and that minimum requirements for the site are met.

Letter ID: 0131 Comment ID: 21529 Letter Lines: 93 to 98

3Comment Code: 3350 2.2.1.5 Use of proprietary models for GS sites (seeking comment)

Comment: Use of Proprietary Models to Delineate the Area of Review SEGNA agrees with EPA that models used for GS analysis should be based on accepted science and should be validated. In addition to requiring operators to disclose code assumptions, relevant e quations and the scientific basis for proprietary models, SEGNA suggests that EP A consider establishing a validation process for such models using empirical data to ensure such models are sound.

Individual Response: EPA agrees with commenters that av ailable proprietary models may meet the complex needs for calculating the AoRs of GS sites, and shar es their concern about the need to evaluate the inputs and assump tions used. EPA plans to 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 satisf action, the code assumptions, relevant equations,

and scientific basis. EPA adds that its Confid ential Business Information requirements at 40 CFR 144.5 will apply to the use of proprietary models.

In response to comments suggesting that histor y matching or validation of these models is needed, EPA believes this is true for any mode l. EPA notes that the GS rule requires at §146.84(e) that the AoR be reevaluated to verify that the CO2 plume is moving as predicted and to allow for necessary revisions to the Ao R and corrective action, testing and monitoring, injection well plugging, pos t-injection site care a nd site closure, and emergency and remedial response plans. EPA clarifies, however, that the Agency will not perform independent validation of 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 modificatio ns to the requirements are appropriate or

necessary.

Letter ID: 0131 Comment ID: 21530 Letter Lines: 100 to 103

Comment Code: 3840 2.3.2 Horizontal well drilling techniques (seeking comment)

Comment: Horizontal Well Construction SEGNA supports the allowance of horizontal drilling for well construction, provided that the construction and operation requireme nts are consistent with those applied

to vertical wells.

Individual Response: In the final rule, EPA allows the use of horizontal wells at GS projects. In the proposed rule, EPA sought comment on the appr opriateness of horizontal drilling techniques

for Class VI wells, and commenters representing energy companies, el ectric utilities, the oil and gas industry, CCS associations, states, and the public, unanimously suppo rted the concept and provided many reasons why horizonta l wells could be beneficial at GS sites. Based on an evaluation of these comments and additional research by EPA, the Agency has concluded that

4horizontal wells that are properly constructed, logged, and tested for mechanical integrity (i.e., to meet the requirements of the GS rule) can ensu re the protection of US DWs from endangerment.

EPA clarifies that horizontal wells will be subject to the same tailored requirements as vertical

wells.

Letter ID: 0131 Comment ID: 21531 Letter Lines: 105 to 111

Comment Code: 3820 2.3.1 Well construction procedures

Comment: Specification of Well C onstruction Materials SEGNA agrees with EPA's position that th e proposed rules should not specify materials that may be used, but rather should allow the ow ner or operator flexibility to choose, provided that the ma terials used are corr osion-resistant and meet appropriate standards. Well casing ma terials should be appropriate to the application, taking into account the chemical nature of th e injected fluids and any

additives, as well as the subsurface environment.

Individual Response: EPA acknowledges the comment and ag rees that, given the continuing evolution of material design a nd the numerous variables possibl e in a long-term GS project, listing specific requirements for casing and cemen t would not be appropriate. Rather, requiring that materials have sufficient structural strength and be compatible with fluids with which they may come in contact, in §146.86(b)(1), allows the owner or operator to determine the best casing and cementing design for each project based on in formation about the site and the planned injection and allows the Direct or to approve that design.

See the discussion of Class VI well construction requirements in the preamble to the final GS rule for additional information. Additionally, EPA is developing guidance on the construction of Class VI wells. This guidance will be available on EPA’s website at http://water.epa.gov/type/groundwater /uic/wells_sequestration.cfm.

Letter ID: 0131 Comment ID: 21532 Letter Lines: 113 to 119

Comment Code: 4340 2.4.4.2 Minimum injection de pth (seeking comment)

Comment: Minimum Injection Depths EPA is not prescribing a minimum injection depth to keep CO2 in a supercritical state since some operators may inject CO2 in a gaseous state, but describes the potential deleterious effects of a change in state (for supercri tical CO2) and the expansion of gaseous CO2. SEGNA believes it would be reasonable to stipulate a minimum injection / storage depth for supercritical CO2, but allow a discretionary lower depth for injection of gaseous CO2.

Individual Response: EPA agrees that it is not appropriate to set a mi nimum injection depth for GS projects or require that the CO2 be injected in a supercriti cal state. EPA believes that a

5determination of site-suitability for GS (i.e., th at subsurface formations will receive and confine injected CO2) should be made on a site-speci fic basis. The GS rule, at §146.82, requires the owner or operator to provide extensive site- and project-specific information to the Director to

demonstrate that the site meets the minimum site criteria at §146.83, that the CO2 will be contained within the injection formation, and that USDWs will be protected from endangerment.

EPA acknowledges that there are limited circum stances where injectio n above the lowermost USDW can be performed in a manner that protec ts USDWs, as long as appropriate protections are in place. The final GS rule at §146.95 establis hes a process by which owners or operators can seek a waiver of the Class VI injection de pth requirements for in jection into non-USDW

formations above and/or between USDWs. The waiver approach requires the submission of extensive, site-specific information (in conjunc tion 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. The requirements are designed to ensure that the owner or operator, the Director, and the Regional Administrator cons ider, on a site specific basis, the implications, benefits, and challenges associat ed with GS and ensuring water availability and USDW protection. For additional information on the waiver approach, please see the final rule and preamble, as well as EPA's responses to comments on the Notice of Data Availability and Request for Comment.

Letter ID: 0131 Comment ID: 21533 Letter Lines: 121 to 124

Comment Code: 4320 2.4.4.1 Injection beneath the lowermos t formation containing a USDW

Comment: Injection Well Operating Requirements SEGNA agrees with EPA's proposal to al low Directors to exempt Underground Sources of Drinking Water (USDWs) below th e injection zone, a nd allow injection below the lowermost non-exempted USDW. SEGNA also supports the

Individual Response: EPA acknowledges that there are lim ited circumstances where aquifer exemptions for GS may be warranted. The final rule allows for the expansion of the areal extent of existing aquifer exemptions for Class II EOR/ EGR wells transitioning to Class VI injection for GS pursuant to requirements at §§146.4 and 144.7( d). Class VI owners or operators granted expansions of existing Class II EOR/EGR aquifer exemptions for GS projects must meet all of the tailored requirements for Class VI wells in the final GS rule.

However, the final rule precludes the issuance of new aquifer exemptions for Class VI wells; that is, aquifer exemptions will only be granted for projects that are transitioning from Class II

EOR/EGR wells to Class VI. For additional info rmation on aquifer exemptions for Class VI wells, 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: 0131 Comment ID: 21534 Letter Lines: 124 to 128

Comment Code: 4490 2.4.5 Use of tracers and potential im pact on human health or ecosystems

6(seeking comment)

Comment: below the lowermost non-exempted USDW. SEGNA also supports the development of guidelines for cost-effectiv e use of tracers, but the decision to require their use should be made by the permitting authority. Of the technical options suggested in the proposed rule, uni que suites of perflu orocarbons (PFCs) appeared to be the best option.

Individual Response: EPA agrees that tracers can be useful tools for monitoring GS projects. However, EPA agrees that tracer use is not appr opriate in all situations. For this reason, EPA does not require the use of tracers at all GS sites; however, the Dire ctor has discretion to require

their use if he/she determines that the use of tracers could improve monitoring of the site and enhance USDW protection from endangerment. The rule will also allow their use if proposed by the owner or operator and approved by the Director.

EPA will continue to track research related to tr acer use, and plans to, every six years, collect and review data on GS projects to determin e 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: 0131 Comment ID: 21535 Letter Lines: 130 to 133

Comment Code: 4520 2.5.1 Continuous internal mechani cal integrity monitoring (seeking comment)

Comment: Mechanical Integrity Testing SEGNA agrees with EPA's proposal to require continuous downhole monitoring, as the required technology is currently av ailable and should no t present an undue cost when required on new wells. However, SEGNA is opposed to requiring

Individual Response: EPA acknowledges the comment and be lieves that continuous pressure monitoring to demonstrate internal mechanical integrity of Cla ss VI wells required at §146.89(b), instead of periodic testing, which is required for most other types of deep injection wells is important given the potential corrosive impact of CO2 and impurities on well materials, the potential geomechanical impacts to well inte grity due to CO2 phase changes, and the temperature and pressure effects associated w ith injecting supercritical CO2. For additional information, please see the discussion of MITs in the final rule preamble.

Letter ID: 0131 Comment ID: 21536 Letter Lines: 133 to 138

Comment Code: 4546 2.5.2.2 MIT frequency (seeking comment)

Comment: cost when required on new wells. However, SEGNA is opposed to requiring Mechanical Integrity (MI) testing more fr equently than the 5 year frequency typically required for deep wells, particul arly if such testing results in well

7downtime. Unnecessary testing and associated downtime will significantly add to costs, and may have additional upst ream impacts on generation that may introduce expensive stor age requirements.

Individual Response: EPA disagrees that a five-year extern al MIT is appropriate. The final GS regulation retains the requirement that owners or operators of Class VI wells must demonstrate injection well external mech anical integrity at least once annually under §146.89(c). EPA believes this is justifiable for the protecti on of USDWs from endangerment given the unique nature of CO2 GS relative to other injection operations, including the pote ntial corrosive impact of CO2 in the presence of water and impurities on well materials, the potential geomechanical impacts to well integrity due to CO2 phase ch anges, the temperature and pressure effects associated with injecting supercritical CO2, and the buoyant nature of th e injected CO2. Because of the unknown long-term effects of CO2 GS, EPA chose a more cons ervative initial approach in the early stages of deployment for GS. EPA be lieves that the USDW protectiveness of MITs justifies their cost. Please see the Cost Analysis, which is available in the rulemaking docket, for

additional information on the costs of MITs.

EPA adds that it is using an ad aptive approach to regulating GS. The Agency plans to collect and review data every six years on GS projects, including MIT da ta, to determine whether the appropriate amount and types of information a nd appropriate documentation are being collected,

and to determine if modifications to the requirements are appropriate or necessary.

Letter ID: 0131 Comment ID: 21537 Letter Lines: 140 to 145

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

Comment: Post-injection Site Care SEGNA disagrees with EPA's proposal to lengthen the post-injection site monitoring period to 50 year s versus the current 30 y ear standard. EPA has provided insufficient justification for such an extension, which will add significant costs and adversely impact sequestration projects and their ability to obtain financing. As it currently r eads, the proposed rule has provisions for extending

Individual Response: EPA disagrees that a post-injection si te care timeframe of 50 years is excessive for most Class VI wells. EPA proposed a default post-injection s ite care timeframe of 50 years based on a review of research studies , industry reports, and existing environmental programs. This analysis was included in an EPA- prepared background document that is available

in the federal docket for the GS rule, titled "C omputational Modeling of Underground Injection

of Carbon Dioxide for Determination of Area- of-Review and Potential Risk to Underground Sources of Drinking Water." EPA assessed vari ous default timeframes based on additional

review of research studies and evaluation of public comments. While numerous commenters suggested that EPA shorten the monitoring timeframe, none of the commenters provided

sufficient data or other evidence to warrant a ch ange in the proposed timeframe. While the 10- or 30-year timeframe suggested by some of thes e commenters may be within the timeframe suggested in some studies, EPA believes that the potential risks of endangering USDWs will

8likely not decline within these timeframes a nd available data, including data submitted by commenters, do not support a different defau lt timeframe. However, EPA recognizes that alternative timeframes may be appropri ate under limited, specific circumstances.

For this reason, the GS rule offers owners or op erators flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion to shorten or lengthen the PISC timeframe during the post-injecti on period based on site-specific da ta, 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 ensu res non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site car e 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 ac commodate site-specific circumstances and various geologic conditions, and addre sses commenters’ concerns, wh ile ensuring USDW protection. Both approaches will utilize si te-specific data, and be based on pressure monitoring and USDW impacts. EPA believes however, that to ensure USDW protection from enda ngerment, a default timeframe for post-injection site care will be necessary in al l but a limited number of cases. This default 50 year post-injection site care ti meframe represents a reasonable and protective monitoring period

based on a review of research studies, industr y reports, and existing environmental programs, and evaluation of public comments.

To the commenters who expressed concern about the cost of post-injection site care, EPA does not agree that post-injection si te care timeframes longer than 30 years will be prohibitively expensive. In fact, EPA believes that post-in jection site care mon itoring will represent a relatively minor component of total project cost, and will provide an essential level of protection from endangerment for USDWs. A discussion of th e costs attributed to monitoring technologies (used during injection and the post- injection site care timeframes ) is available in the Technology

and Cost Document for the GS rule, which is in the federal docket for this rulemaking. EPA believes that it is logical to make use of existing monitoring infrastruc ture at a GS site in order to ensure USDWs are not endangered.

Letter ID: 0131 Comment ID: 21538 Letter Lines: 145 to 147

Comment Code: 5260 2.8.2.3 Adjusting the post-injecti on timeframe (seeking comment)

Comment: financing. As it currently r eads, the proposed rule has provisions for extending this period in the event that performance standards are not met, so the standard would be adequately protective with a 30-year requirement.

Individual Response: EPA disagrees that a post-injection si te care timeframe of 50 years is

9excessive for most Class VI wells. While numerous commenters suggested that EPA shorten the monitoring timeframe, none of the commenters provided sufficie nt data or other evidence to warrant a change in the proposed timeframe. Wh ile the 10- or 30-year timeframe suggested by some of these commenters may be within the timeframe suggested in some studies, there are circumstances (e.g., little development of mine ral trapping of CO2) under which the potential risks of endangering USDWs will likely not decline within these timeframes and available data, including data submitted by commenters, do not support a different default timeframe.

EPA acknowledges there will be circumstances wh ere it can be demonstrated in less than 50 years that the plume and pressure front no longe r pose a risk of endangerment to USDWs. For

this reason, the GS rule offers ow ners or operators flexibility re garding the duration of the PISC timeframe by: (1) allowing the Director discretio n to shorten or lengthen the PISC timeframe during the post-injection period based on site-s pecific data, pursuant to requirements at §146.93(b); or (2) affording the Dire ctor discretion to allow a Cla ss 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 ensu res non-endangerment of USDWs pursuant to requirements at §146.93(c).

EPA believes that a default post-injection site car e 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 ac commodate site-specific circumstances and various geologic conditions, and addre sses commenters’ concerns, wh ile ensuring USDW protection. Both approaches will utilize si te-specific data, and be based on pressure monitoring and USDW impacts.

Letter ID: 0131 Comment ID: 21539 Letter Lines: 149 to 153

Comment Code: 5430 2.9.1 Comments on proposed financia l responsibility requirements (40 CFR 146.85)

Comment: Financial Responsibility and L ong-term Care Requirements Generally, SEGNA supports efforts to minimize post-closure monitoring requirements and costs, and to increase options for demonstrating financial assurance, so as to not unnecessarily discourage entities from pursuing or financing carbon seque stration projects.

Individual Response: EPA agrees that flexibility is impor tant. Owners or operators have the flexibility to choose from a variet y of financial instruments to m eet their financial responsibility obligations. Owners or operators may use one or mu ltiple financial responsibility instruments for well plugging and PISC (§146.85(a)(6)). However EP A will not allow for a separate financial responsibility demonstration for well plugging and PI SC (i.e., a demonstration submitted prior to well plugging and the beginning of the post-injection site care peri od rather than with the permit application). A demonstration of fi nancial responsibility for all phases of the GS project will be required prior to the issuance of a Class VI permit (§146.85(a)(5)(i)).

10EPA is developing guidance on financial responsibili ty for Class VI wells to assist owners or operators in evaluating the fi nancial responsibility requireme nts for Class VI wells. This guidance will be available on EPA's website at http://water.epa.gov/type/groundwater /uic/wells_sequestration.cfm.

Letter ID: 0131 Comment ID: 21540 Letter Lines: 155 to 159

Comment Code: 5700 2.12 Comments on the proposed durati on of Class VI permits (seeking comment)

Comment: Proposed Injection Permit Duration SEGNA agrees that with EPA's proposal that permits be issued for the operating life and post-closure care period of the injection well. The ongoing monitoring, reporting and regulatory review required by other provisions of this proposed rule are adequate to ensure that human hea lth and the environment are protected.

Individual Response: EPA agrees with commenters that Cl ass VI permits should be issued for the operating life of the GS proj ect. EPA believes that the iterat ive process of developing and executing the various plans required of GS well ope rators under the final rule (e.g., for AoR and

corrective action, te sting and monitoring, injection well pl ugging, post-injection site care, and emergency and remedial response) is tailored to the unique aspect s of—and is more appropriate for–GS than establishing a finite permit dur ation (e.g., five years as suggested by some commenters). EPA adds that the required revi ews of the AoR and corrective action plan, the testing and monitoring plan, and th e emergency and remedial respon se plan at least every five years throughout the life of the project are preferable to a periodic permit r eapplication. The iterative process and subsequent plan reevaluati ons ensure that time and resources are committed to the most critical aspects of the pe rmit in preventing endangerment to USDWs.

EPA clarifies that the final GS rule specifies that Class VI permits will be issued for the operating life of the facility and the post-inj ection site care period (144.36(a)). The rule also requires the Director to review Cl ass VI permits at least every 5 years to determine whether they

should be modified, revoked and reissued, termin ated or a minor modification made as provided in §§144.39, 144.40, or 144.41.

Letter ID: 0131 Comment ID: 21541 Letter Lines: 161 to 168

Comment Code: 1420 1.2.1.1 Support the GS rulemaking

Comment: Conclusion In summary, SEGNA is supportive of EPA's e fforts to provide regul atory clarity for geologic sequestration of CO2. We enc ourage EPA to consider the above recommendations to ensure that geologi c sequestration of CO2 is conducted in an environmentally safe and techni cally sound manner, while avoiding unnecessary technical and regulatory complexity. An appropriate balance

1112 between these considerations will maximi ze the potential for this technology to play a significant role in addressing the challenges of climate change.

Individual Response: EPA acknowledges the comment and belie ves that the creation of a new injection well class (VI) under the existing UIC Program is necessary to enable deployment of GS as a climate change mitigation technol ogy in a manner that protects USDWs from endangerment. EPA agrees that the UIC Program , under the authority of the SDWA, provides a strong framework for regulating inje ction of CO2 for GS and adds that the GS regulation tailors the UIC requirements to address the unique issues associated with large- scale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic

formations.

EPA agrees that the implementation of the GS rule in a manner that ensures protection of USDWs from endangerment is impo rtant to establishing a foundation for further advances in the field of CO2 GS. EPA acknowledges the need for regulatory certaint y: the final GS requirements provide a level of certainty by setting forth unique requirement s for GS. These requirements

include: the tailored AoR delin eation process at §146.84, the types of monitoring appropriate to GS projects at §146.90 and the post-injection site care process at §146.93. For additional information on these requirements, please also see the discussion of EPA’s Final Regulatory Approach in the preamble to the final GS rule.