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.COMMENTS OF THE UTAH DIVISI ON OF OIL, GAS AND MINING

JOHN R. BAZA, DIRECTOR

1594 W. NORTH TEMPLE, SUITE 1210

PO BOX 145801

SALT LAKE CITY, UT 84114

PH: 801-538-5340

ON THE

U.S. ENVIRONMENTAL PROTECTION AGENCY’S

PROPOSED FEDERAL REQUIREMENTS UNDER THE UNDERGROUND

INJECTION CONTROL PROGRAM FOR CARBON DIOXIDE GEOLOGIC

SEQUESTRATION WELLS

DOCKET ID NO. EPA-HQ-OW-2008-0390

December 23, 2008

The Utah Division of Oil, Gas and Mining (“ the Division”) appreciat es the opportunity to

comment on the referenced docket, related to the United States Environmental Protection Agency (“EPA”) proposal for Federal Requirements Under the Underground Injection Control (“UIC”) Pr ogram for Carbon Dioxide (“CO 2 ”) Geologic Sequestration

(“GS”)

Wells.

The Division has primacy over Class II injecti on wells in Utah, except for those on Indian Lands. The Division has been regulating injec tion wells since the 1950’s, and it obtained primacy for regulating injection wells under the UIC Program in 1982.

The Division offers the following comment s in regards to the proposed rules.

Funding

The Division has been administering a Cl ass II UIC Program for many years while receiving less than adequate funding from EPA. This deficit in funding has been compensated by the state’s Oil and Gas Conser vation Fee paid by operators based on oil and gas production volumes. It will be importa nt for EPA to address adequate funding for the new Class VI Well program because states will not be able to simply take on such a new responsibility without a mechanism to adequately fund it.

Protection of Underground Source s of Drinking Water (“USDW”)

As with all underground injec tion, protection of USDWs should be the major focus of the rules. Protection is accomplishe d through containment of the CO 2 stream through proper site selection and characterization of the ge ologic formation that is to be used forinjection, along with sound construction of th e injection wells and adequate monitoring practices.

Enhanced Oil Recovery (“EOR”) and EOR Crossover

Injection into reservoirs for EOR should remain unchanged and regulated under the Class II program. In the case where an operator of an EOR would also c hoose to use their wells for the purpose of GS the wells should sti ll be regulated under the Class II program. Additionally injection into non- producing oil and gas reservoi rs should also remain under the Class II program. Injection into non-oil a nd non-gas reservoirs should appropriately fall into the newly proposed Class VI well category for GS as proposed.

The proposed rule allows the director of th e program the discretion to “grandfather” the construction requirements of existing Class II wells to Class VI wells as long as a

determination is made that these wells w ould not endanger a USDW . The Division agrees with this proposal consider ing that an existing Class II well for EOR would not be allowed to endanger a USDW.

Injection Zones for Ga s Sequestration

EPA has proposed that all injection of CO 2 for sequestration should be below the lowermost USDW. This proposal is too rest rictive and could eliminate many areas of potential injection throughout th e State of Utah that might otherwise be considered for sequestration. There should be no prohibition against injection into any zone even if above the lowermost USDW as long as it can be determined that geologic conditions would prevent endangerment to a USDW.

Area of Review (“AOR”) Determination, Monitoring and Verification

The EPA seeks comment on the use of m odeling for AOR delineation, the use of proprietary models for GS site s, and the frequency of AOR reevaluation. By letter dated

December 23, 2008, the Interstate Oil a nd Gas Compact Commission (“IOGCC”) has

submitted several comments to the EPA on these issues with respect to the proposed rule. As a regulatory agency within a member stat e of IOGCC, the Divi sion concurs with the

IOGCC comments and recomme ndations related to AOR.

Proposed Well Construction Requirements

EPA proposed that construction of GS wells be tailored to the construction requirements of a Class IH well. The Division agrees that USDWs need to be protected; however, these construction requirements may be too stri ngent for existing Class II EOR wells. To require remedial work on existing wells to achieve the proposed standards may in fact compromise the established mechanical integrity of an existing Class II well. Additionally, the requirement to set surface casing and cement through the base of the lowermost aquifer would be too restrictive. The regulating agency should have thediscretion to evaluate wells on a site-specific basis to insure that USDWs will be protected.

Operating Requirements

EPA seeks comments on hydraulic fracturing, minimum depth requirements, and the potential impact of tracer use on human health and the environment. The Division

concurs with the IOGCC recommendati ons (included in their December 23, 2008 comments) that while hydraulic fracturi ng may be necessary for well completion, measures should be taken to prevent any fr acturing of the confining zone. No minimum depth for GS should be specified and once agai n should be done on a site-specific basis.

Use of tracers should be at the di scretion of the regulating agency.

Monitoring

EPA seeks comments on proposed pressure plume and pressure front monitoring including issues such as the amount a nd type of monitori ng, the usefulness of geophysical, air and soil mon itoring, post-injection site monitoring, and frequency of reporting requirements. The IOGCC comments of December 23, 2008 have addressed all of these issues in great detail, and the Division concurs with their recommendations.

Waste Characterization

Injected CO 2 is not and should not be considered a hazardous waste or regulated under

RCRA or CERCLA. It is assumed that RCRA or CERCLA wastes would be removed

from the CO 2 stream prior to injection.

Post Site Care Responsibility

EPAs proposed rule sets the pos t-injection care period at 50 y ears. This may be modified if it can be demonstrated that the plume has stabilized and the pressure has dissipated. Setting a 50-year period may be unnecessarily long. The Division’s recommendation is that a shorter period be prescribed and then the regulating agency ma y have the discretion to set a longer post-injection ca re period if the specifics of a project indicate such a need.Letter ID: 0193

Commenter: John R. Baza Organization: Utah Division of Oil, Gas, and Mining

Letter ID: 0193 Comment ID: 23907 Letter Lines: 46 to 52

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

Comment: The Division has been administering a Cl ass II UIC Program for many years while receiving less than adequate funding from EPA. This deficit in funding has been compensated by the state’s Oil and Gas C onservation Fee paid by operators based on oil and gas production volumes. It will be important for EPA to address adequate funding for the new Class VI Well program because states will not be able to simply take on such a new re sponsibility without a mechanism to adequately fund it.

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 acquiri ng 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 th at 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 ar e required to meet a minimum of 25 percent matching requirement.

Letter ID: 0193 Comment ID: 23908 Letter Lines: 54 to 60

Comment Code: 1610 1.3.1 Risks to USDWs

Comment: Protection of Underground Sources of Drinking Water ("USDW")

As with all underground inje ction, protection of USDWs s hould be the major focus of the rules. Protection is accomplished through containment of the CO2 stream through proper site selec tion and characteri zation of the geologic formation that is to be used for injection, along with sound construction of the injection wells and adequate monitoring practices.

Individual Response: The Agency agrees that drinking wa ter is an important resource that needs protection. The primary goal of the UIC Program under the SDWA is to protect USDWs from endangerment. Consistent with SDWA §1422 the UIC program provides that no underground injection shall be aut horized if it results in the m ovement of fluid containing any contaminant into USDWs, if the presence of th at contaminant may cause a violation of any

1primary drinking water regulation or may adversely affect the health of persons as specified in §144.12.

EPA recognizes that injecting large volumes of CO2 for GS poses unique challenges that, if not properly managed, could endanger drinking water sources and ha ve other adverse impacts. However, with proper site sele ction, the final, tailored, Class VI requirements address the large volumes of CO2 injected, its buoyancy, potential corrosivity in the presence of water, and potential impurities in the CO 2 stream. In addition, the tailo red permitting, siting, construction, operation, monitoring, and post-injection site care requirements in the GS rule are intended to prevent leakage from injection fo rmations and protect USDWs.

Letter ID: 0193 Comment ID: 23909 Letter Lines: 62 to 70

Comment Code: 2046 1.5.2.3 Continuing to classify CO2 in jection for EOR/EGR as Class II/ dividing line between Class II and Class VI (seeking comment)

Comment: Enhanced Oil Recovery (" EOR") and EOR Crossover

Injection into reservoirs for EOR shou ld remain unchanged and regulated under the Class II program. In the case where an operator of an EOR would also choose to use their wells for the purpose of GS the wells should st ill be regulated under the Class II program. Additionally injection into non-producing oil and gas reservoirs should also remain under the Class II program. Injection into non-oil and non-gas reservoirs should appropr iately fall into the newly proposed Class VI well category for GS as proposed.

Individual Response: EPA agrees that injection of CO2 for the primary purpose of enhancing oil and gas recovery should remain under the Class II Program. However, EPA believes that injection for the primary purpose of long-term stor age is sufficiently different from Class II ER operations and warrants tailored re quirements. For example, the volume of CO2 anticipated to be injected in Class VI wells is significantly great er than for Class II wells. Reservoir pressure conditions will also be different, with Class VI injection operations involving large volumes of CO2 and likely having higher pressure s within their storage formations than Class II ER projects. EPA believes that there are significant differences between how projects are operated, as well as the risks posed by these different injection activi ties. The new tailored approach of the GS rule was designed to address the gene ral risks deep injection may pos e to USDWs and was tailored specifically to address the risk s posed by long-term storage of CO2 (i.e., very large volumes, very long time-periods, and reservoir pressure conditions).

EPA is developing guidance on transitioning perm its from Class II to Class VI. The guidance will assist Directors in determining whether an injection project should be transitioned from Class II, where the primary purpos e is oil and gas production, to Class VI, where the primary purpose is long-term storage of large volumes of CO2. The gu idance describes the recommended methods the Director may use to evaluate change s in risk to USDWs from projects, and how the Director may determine whether a project should be regulated within th e Class II or Class VI UIC program. This guidance will be available on EPA’s website at

2http://water.epa.gov/type/groundwat er/uic/wells_sequest ration.cfm. For more information, please

see the discussion on transition of Class II well s in the preamble to the final GS rule.

Letter ID: 0193 Comment ID: 23910 Letter Lines: 72 to 76

Comment Code: 2064 1.5.3.2 Grandfathering construction of Class II wells (seeking comment)

Comment: The proposed rule allows the director of the program the discretion to "grandfather" the constructi on requirements of existing Cl ass II wells to Class VI wells as long as a determination is ma de that these wells would not endanger a USDW. The Division agrees with this proposal considering that an existing

Class II well for EOR would not be allowed to endanger a USDW.

Individual Response: EPA agrees that many Class II well s are designed and constructed to withstand exposure to CO2. The final GS rule provi des for the construction of these wells to be grandfathered per §146.81(c), provid ed the owner or operator can demonstrate to the Director that the wells were engineered and constructed to meet th e requirements at §146.86(a) and ensure protection of USDWs, in lieu of re quirements at §146.86(b) and §146.87(a). The final Class VI regulations require that any owner or operator injecting CO2 for the primary purpose of long term storage obtain a Class VI permit with some special consideration for the fact that they are transitioning from a well not originally designed to meet Class VI requirements. The Director has the authority to determine at what point a Cl ass VI permit is required for those projects that are transitioning from the primary purpose of EOR to long term storage of CO2. The final regulation provides a set of tec hnical factors for the Director to evaluate in making this determination, at §144.19. EPA believes that this approach provides su fficient protection of

USDWs when there is an increased risk to USDWs as compared to traditi onal Class II operations while allowing for site-specific flexibility. EPA adds that, following re-permitting as Class VI wells, these projects would be subject to the operational, MIT, monitoring, reporting, plugging, and post-injection site care and site clos ure requirements in the final GS rule.

Letter ID: 0193 Comment ID: 23911 Letter Lines: 78 to 85

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

USDW

Comment: Injection Zones for Gas Sequestration

EPA has proposed that all injection of CO 2 for sequestration should be below the lowermost USDW. This proposal is too rest rictive and could eliminate many areas of potential injection thro ughout the State of Utah that might otherwise be considered for sequestration. There shoul d be no prohibition against injection into any zone even if above the lowermos t USDW as long as it can be determined that geologic conditions would pr event endangerment to a USDW.

Individual Response: EPA acknowledges that there are lim ited circumstances where injection

3above 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.

EPA believes that these requirements will ensure USDW protection while providing flexibility to UIC program Directors and owne rs or operators who undertak e CO2 injection for GS. The Agency believes this approach: 1) responds to co ncerns about local and re gional geologic storage capacity limitations imposed by th e proposed injection depth require ments; 2) allows for a more site-specific assessment of injection depth for GS projects; 3) accommodates injection into different formation types; 4) a llows 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 aqui fer exemptions for GS. Finally, EPA’s approach to addressing injection depth va riability through a waiver process responds to concerns about future drinking wa ter resource availability and the need to ensure that highquality water remains available in sufficient qua ntities to supply drinking 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: 0193 Comment ID: 23912 Letter Lines: 87 to 94

Comment Code: 3300 2.2.1 Delineating the AoR/M odeling CO2 movement

Comment: Area of Review ("AOR") Determinat ion, Monitoring and Verification

The EPA seeks comment on the use of mode ling for AOR delineation, the use of proprietary models for GS sites, and the frequency of AOR reevaluation. By letter dated December 23, 2008, the Inters tate Oil and Gas Compact Commission ("IOGCC") has submitted several comments to the EPA on these issues with respect to the proposed rule. As a regulatory agency within a member state of IOGCC, the

Division concurs with the IOGCC comments and recommendations related to AOR.

Individual Response: Based on its evaluation of all public comments and input on the proposed rule and NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and preamble for furthe r discussion on EPA’s final approach.

Letter ID: 0193 Comment ID: 23913 Letter Lines: 96 to 106

Comment Code: 3820 2.3.1 Well construction procedures

Comment Code: 3824 2.3.1.2 Cementing of long-string casing (seeking comment)

Comment: Proposed Well Construction Requirements

EPA proposed that construction of GS we lls be tailored to the construction requirements of a Class IH well. The Division agrees that USDWs need to be

4protected; however, these construction requirements may be too stringent for existing Class II EOR wells. To require remedial work on existing wells to achieve the proposed standards may in fact compromise the established mechanical integrity of an existing Class II well. Additionally, the requirement to set surface casing and cement through the base of the lowermost aquifer would be too restrictive. The regulating agency should have the disc retion to evaluate wells on a site-specific basis to insure that USDWs will be protected.

Individual Response: EPA disagrees that the well construction standards for Class VI wells are too stringent. Rather, the constr uction requirements at §146.86 provi de an appropriate level of protection from endangerment to USDWs that is based upon the existi ng UIC framework for deep wells. The new tailored approach was design ed to address the genera l risks deep injection may pose to USDWs and was tailored specifically to address the unique na ture of CO2 GS (i.e., including large injection volumes, the relative buo yancy 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 adds that promoting GS or carbon management efforts is outside the scope of the GS rulemaking, which focuse s on protecting USDWs from endangerment.

Regarding the comment that remedial work will compromise the mechanical integrity of an existing Class II well, EPA clarifie s that if a Class II well cannot be converted for GS injection and operated in a way that prot ects USDWs, including maintaining mechanical integrity and safe operation, conversion to Class VI will not be al lowed. EPA believes that many Class II wells are

constructed in a manner that would allow conversion for use as Class VI wells, but acknowledges that this may not be the case for all such wells.

The final GS rule, at §146.81(c), allows the co nstruction of ER wells to be grandfathered, 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 protec tion of USDWs, in lieu of requirements at §146.86(b) and §146.87(a). Only the cemented-in-place construction requirements will be grandfathered under the fi nal GS rule; following conversion, these wells will be permitted as Class VI wells and be subj ect to the operational, MIT, monitoring, reporting, plugging, and post-injection site ca re and site closure requiremen ts in the final GS rule.

EPA is developing guidance on transitioning from Class II to Class VI. The guidance will assist Directors and owner/operators in evaluating where a project may fit within a Class II to Class VI transition. The guidance describes the methods ava ilable for the Director to determine the risk posed to USDWs from a GS/ER project, and how th e Director may determine if a project should be regulated by a Class II or Class VI UIC program. The guidance will be available on EPA's web site, at http://water.epa.gov/type/g roundwater/uic/wells_s equestration.cfm.

Letter ID: 0193 Comment ID: 23914 Letter Lines: 108 to 117

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

Comment Code: 4344 2.4.4.2.2 Comments opposed to setting a minimum injection depth

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

5Comment: Operating Requirements

EPA seeks comments on hydraulic fracturing, minimum depth requirements, and the potential impact of tracer use on human h ealth and the environment. The Division

concurs with the IOGCC recommendations (included in their December 23, 2008 comments) that while hydraulic fracturi ng may be necessary for well completion, measures should be taken to prevent any fracturing of the confining zone. No minimum depth for GS should be specified and once again should be done on a site-specific basis. Use of tracers sh ould be at the discretion of the regulating agency.

Individual Response: The final rule allows the use of hydrau lic fracturing at Class VI well 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 stimula tion, including hydraulic fracturing, must be approved by the Director. Owners or operators must submit a propos ed stimulation program as part of the permit application under §146.82(a)(9); the plan must demonstrate that a ny stimulation act ivities will not compromise the integrity of the confining zone. The Director will evaluate the owner or operator's proposed stimulation plan in the cont ext 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 neede d. EPA clarifies that UIC regulations prohibit fracturing of the confining zone at an y time during injection or stimulation.

In addition, to maintain the integrity of the c onfining zone, the final rule requires that, except during stimulation, the inj ection pressure not exceed 90 percen t of the fracture pressure of the injection zone.

EPA also agrees that it is not appropriate to set a minimum inj ection depth for GS projects and the Agency believes that a determination of si te-suitability for GS (i.e., that subsurface

formations will receive and confin e injected CO2) should be made on a site-specific basis. The GS rule at §146.82 requires the owner or operator to provide extensive si te- and project-specific

information to the Director to demonstrate that the site meets the minimum siting criteria at §146.83 and 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

6extensive, 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.

Finally, EPA agrees that the use of tracers should not be required at all GS sites, but should be available as an option. For this reason, EPA does not require the use of tr acers at all GS sites; however, the Director has discreti on to require their us e if he/she determin es 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.

Letter ID: 0193 Comment ID: 23915 Letter Lines: 119 to 126

Comment Code: 4600 2.6 Proposed Plume and Pressure Front Monitoring Requirements (40 CFR 146.90)

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

Comment: Monitoring

EPA seeks comments on proposed pressure plume and pressure front monitoring including issues such as the amount and type of monitoring, the usefulness of geophysical, air and soil monitoring, pos t-injection site monitoring, and frequency of reporting requirements. Th e IOGCC comments of December 23, 2008

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

with their recommendations.

Individual Response: Based on its evaluation of all public comments and input on the proposed rule and NODA and Request for Comment, EPA has made many revisions to the GS Rule. See the final rule and preamble for furthe r discussion on EPA's final approach.

EPA agrees with commenters that developing an d following testing and monitoring plans is an important part of assuring that a GS project is operating properly and is crucial for the early detection of potential endangerment to USDWs. EPA also agrees that periodic updates to the plan are appropriate. EPA clarifies that the fina l GS regulation includes a requirement that the

AoR be reevaluated at least ever y five years, and it specifies at §146.90(j) that the operator revise the testing and monitoring plan to incorporate the results of the most recent AoR reevaluation and recent operational and monitoring data.

EPA acknowledges the comment and the final rule retains the text as pr oposed. Please see the final rule and the discussion of testing and mon itoring in the preamble for additional information.

7Letter ID: 0193 Comment ID: 23916 Letter Lines: 128 to 132

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

Comment Code: 1640 1.3.4 CERCLA issues (seeking comment)

Comment: Waste Characterization

Injected CO2 is not and should not be c onsidered a hazardous waste or regulated

under RCRA or CERCLA. It is assumed that RCRA or CERCLA wastes would be removed from the CO2 stream prior to injection.

Individual Response: EPA received many comments regardi ng the applicability of the RCRA regulations and statute to CO2 st reams that are geologically seque stered under the final Class VI UIC well requirements. As a result, EPA has deci ded to initiate a sepa rate proposed rulemaking specifically to examine the issue of RCRA appl icability 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 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 ch anges to the RCRA regulations.

Letter ID: 0193 Comment ID: 23917 Letter Lines: 134 to 141

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

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

Comment: Post Site Care Responsibility

EPAs proposed rule sets the post-injecti on care period at 50 years. This may be

modified if it can be demonstrated th at the plume has stabilized and the pressure has dissipated. Setting a 50-year period may be unnecessarily long. The

Division’s recommendation is that a shorte r period be prescribed and then the regulating agency may have the discreti on to set a longer post-injection care period if the specifics of a pr oject indicate such a need.

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, titled "Computationa l Modeling of Underground Injection of Carbon

Dioxide for Determination of Area-of-Review a nd Potential Risk to Underground Sources of Drinking Water." EPA assessed various default timeframes based on additional review of

89 research studies and evaluation of public commen ts. While numerous commenters suggested that EPA shorten the monitoring timeframe, none of the commenters provided suffi cient data or other evidence to warrant a change in the proposed timeframe. While the 10- or 30-year timeframe suggested by some of these commenters may be within the timeframe suggested in some studies, EPA believes that the potential risks of endange ring USDWs will likely no t decline within these timeframes and available data, including da ta submitted by commenters, do not support a

different default timeframe. However, EPA acknowledges there will be circumst ances where it can be demonstrated in less than 50 years that the plume and pressure fr ont no longer pose a risk of endangerment to USDWs. For this reason, the GS ru le offers owners or operators flexibility regard ing the duration of the PISC timeframe by: (1) allowing the Direct or 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 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. 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.