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.file:///C|/Users/Kristy/Desktop/KristyMaterials/CommentsToPDF/EPA-HQ-OW-2008-0390-0234.txt [11/18/2010 10:30:50 PM] Document ID: EPA-HQ-OW-2008-0390-0234

Last Name: Corneli

First Name: Steven B. Title: Vice President, Market and Climate Policy Organization: NRG Energy, Inc. City: Princeton

State: NJ Zip Code: 8540

Phone Number: 609.524.4500

Fax Number: 609.524.4501 Country Code:

Email Address: Current Category Code: 255

Comment:

Water Docket Environmental Protection Agency

Mailcode: 2822T 1200 Pennsylvania Ave., NW Washington, DC 20460

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

RE: COMMENTS ON THE PROPOSED FEDERAL REQUIREMENTS UNDER THE UNDERGROUND INJECTION CONTROL (UIC) PROGRAM FOR CARBON DIOXIDE (CO2) GEOLOGIC SEQUESTRATION (GS) WELLS.

Dear Sir or Madam:

Attached please find the comments of NRG Energy, Inc. in the above referenced

matter.

Sincerely,

Steven B. Corneli

Vice President Market and Climate Policy

Comments of NRG Energy, Inc. Proposed UIC Program for Carbon Sequestration (Docket ID No. EPA-HQ-OW-2008-0390)

NRG Energy Inc. (NRG) submits the following comments concerning the Environmental Protection Agency ’s (EPA’s) proposed "Federal Requirements under the Underground Injection Control (UIC) Program for Carbon Dioxide (CO2) Geologic Sequestration (GS) Wells," as published in the Federal Register on July 25, 2008 at pages 43491-43541. NRG Energy, Inc., a Fortune 500 company, owns and operates one of the country’s largest and most diverse power generation portfolios. NRG’s 48 plants provide approximately 24,000 megawatts of generation capacity--enough to power nearly 20 million homes. NRG believes that emissions of GHGs from power generation and other sectors must be reduced, both domestically and internationally, to successfully address climate change, andfile:///C|/Users/Kristy/Desktop/KristyMaterials/CommentsToPDF/EPA-HQ-OW-2008-0390-0234.txt [11/18/2010 10:30:50 PM] that commercially attractive, safe and environmentally secure carbon capture and sequestration will be critical for that success. Headquartered in Princeton, NJ, NRG is a member of the U.S. Climate Action Partnership (USCAP), a group of business and environmental organizations calling for mandatory legislation to reduce greenhouse gas emissions.

NRG appreciates the substantial efforts which have been part of this proposal development governing CO2 injection for the purpose of GS. As a company, NRG is committed to effectively addressing climate change, and believes that GS is a critical component for the reduction of CO2 emissions. In general, NRG supports and commends the efforts of the EPA to develop a rational approach that would (1) create a new category of injection wells (i.e., Class VI) under the Underground Injection Control (UIC) Program and (2) establishes Federal regulations that are specifically tailored to CO2 injection for GS. However, we are concerned about several technical requirements of the proposed rules that would substantially increase the cost of GS without environmental benefits. It is essential that EPA develop a regulatory framework that encourages the commercial deployment of GS, otherwise efforts and investments to develop carbon capture technology will be discouraged.

NRG is a member of the Carbon Sequest ration Council (CCS Contact Group), and we support the more extensive comments filed by this organization. NRG offers the following comments on the proposed rule:

Injection Zones for Geologic Sequestration (GS)

The proposed rule limits GS to only those geologic formations that are below the lowermost underground source of drinking water (USDW). Prohibiting injection between and/or above the lowermost USDW would exclude GS in many potential storage reservoirs throughout the US that could be utilized for injection while still ensuring protection of USDWs. The petroleum industry has demonstrated that they can operate CO2 injection wells for EOR/EGR while preventing USDW endangerment. We believe protection of valuable drinking water sources could be accomplished through proper site selection and characterization. NRG recommends using science based techniques to demonstrate that geologic conditions exist that will prevent CO2 migration to USDWs. Under these circumstances, the lowermost USDW restriction would be unnecessary.

Area of Review and Corrective Action Requirements

1. Use of Computational Models for Area of Review

The EPA requested comment on the proposed rule regarding the use of modeling for area of review (AoR). NRG supports the use of computational models for determination of the AoR for geologic sequestration projects. The use of such models is already being used in the UIC program for "no-migration" petitions for Class I injection wells. We believe the use of modeling for determining the pressure effects associated with the underground injection process is an appropriate confirming process for safe site selection and corrective action to address potential risk presented by GS.

2. AoR Reevaluation

The proposed rule requires a re-evaluation of the AoR determination on afile:///C|/Users/Kristy/Desktop/KristyMaterials/CommentsToPDF/EPA-HQ-OW-2008-0390-0234.txt [11/18/2010 10:30:50 PM] frequency not to exceed once every ten years. NRG agrees with the Carbon Sequestration Council’s recommended alternative approach to re-evaluate the AoR only when site specific operation and monito ring data suggest that there is a

need for a new evaluation of the AoR. Periodic AoR re-evaluation will most likely be necessary given the enormous volumes of CO2 that would be injected into the subsurface, the lengthy timeframes likely for GS operations, and the potential uncertainty of the original model prediction. We believe that it is impractical and cost prohibitive to require re-evaluation of the AoR on a fixed schedule. Re-evaluation of the AoR should only be conducted when monitoring and testing data are determined to be inconsistent with the modeling results.

3. Corrective Action

EPA proposes to allow a phased approach to corrective action for GS wells. NRG agrees that this approach is prudent and practical given the enormous volumes of CO2 that would be injected for a geologic sequestration project. Implementation of a phased corrective action to address risk associated with artificial penetrations such as plugged well borings would reduce project costs and also reduce the regulatory burdens of the permitting process.

Proposed Class VI Well Standards

The proposed Class VI well construction requirements are as stringent as those for hazardous waste injection (Class I). NRG believes that this is not a logical or appropriate regulatory approach to ensure protection of USDWs. The injection of CO2 does not warrant the same level of regulations as hazardous waste injection.

The primary issues associated with CO2 injection for GS are related to the enormous volumes and the mobility of CO2 in the subsurface. However, the Class VI requirements do not address these issues. These stringent well construction requirements will only increase the costs of operation resulting in no additional protection of USDWs. NRG agrees with the Carbon Sequestration Council’s recommendation to use the Class II regulations as a starting point for the development of the Class VI regulations. The oil and gas industry has several decades of CO2 injection experience with the Class II UIC program an d has demonstrated that the construction requirements for Class II injections wells are sufficient to protect human health and the environment.

Injection Well Operating Requirements

1. Injection Pressure Limitations

The proposed rule does not allow injection pressures that exceed 90% of the fracture pressure of the receiving formation. NRG believes that this rule of thumb would be an over protective requirement and would not be necessary for ensuring containment of CO2 in the receiving formation. The existing requirement under the UIC regulations for Class II wells allows injection pressure limits that are based on site-specific conditions (i.e., well tests and geomechanical studies) that have been proven to be effective in protecting the confining zone. We believe a standard similar to Class II injection wells would be appropriate

for GS.

2. Continuous Monitoringfile:///C|/Users/Kristy/Desktop/KristyMaterials/CommentsToPDF/EPA-HQ-OW-2008-0390-0234.txt [11/18/2010 10:30:50 PM] NRG supports continuous monitoring of the annular and injection pressure for well integrity purposes. However, the proposed requirement for continuous monitoring of the annular fluid volume is impractical and unnecessary. We recommend continuous measurement of the annular pressure as a means of leak

detection instead of the annual fluid volume.

3. Tracers

NRG opposes any requirement to use tracers for leak detection because leaks from properly permitted injection wells are not likely to occur. The use of tracers

will not be effective in the detection of CO2 releases in the subsurface and will not ensure the protection of USDWs. Tracers are more likely to cause "false positives" by accidental leaks from the equipment on the surface. The Class VI regulations are designed to prevent the kind of leakage that the tracers are

intended to detect.

Monitoring Requirements

The preamble of the proposed rule states that the "monitoring of subsurface geochemistry and the position of the CO2 plume and pressure front are necessary to verify predictions of plume movement, provide inputs for modeling, identify

needed cor rective actions, and target geochemical and surface monitoring activities." 73 Fed. Reg. at 43514. NRG believes that the proposed monitoring requirements are excessive and unjustified. The use of monitor wells or seismic data would be needed to verify the model predictions. In particular, it is impractical and cost prohibitive to measure the exact location of the CO2 plume and pressure front using monitor wells. The monitor wells would be very expensive to install and may create a potential pathway for migration of CO2. In addition, plume or pressure front monitoring have never been necessary or required under the Class I hazardous waste injection well program because experience has shown that it is not necessary to verify the model predictions.

Financial Assurance

NRG commends the EPA for allowing flexibility on financial assurance for GS wells. Allowing flexibility will enable operators to use a combination of approaches and instruments to meet the financial requirements over the life of the injection well operation. We believe that it would be a mistake to impose any restrictions on the types of financial assurance or instruments that can be used for GS wells. We recommend that this approach be retained in the final

rule.

RCRA Applicability

The preamble of the proposed rule suggests that CO2 injected for GS projects may be considered hazardous waste for RCRA purposes. 73 Fed. Reg. at 43503. EPA’s brief discussion of the potential for injected CO2 streams to be characterized as hazardous waste are causing concern among the electric power industry and could have an effect on the future development of carbon capture and sequestration projects. The premise that CO2 could be characterized as a hazardous waste would likely prove detrimental to project development. The RCRA definition of "solid waste" is limited to "solid, liquid, semi-solid, or contained gaseous material." RCRA 1004(27). Because the gas and liquidfile:///C|/Users/Kristy/Desktop/KristyMaterials/CommentsToPDF/EPA-HQ-OW-2008-0390-0234.txt [11/18/2010 10:30:50 PM] (supercritical) phases involved in GS do not meet this definition, reading of federal law would suggests that the CO2 stream for GS should not be considered a "solid waste". EPA should clarify that the gas and liquid phases of the CO2 stream is not a solid or hazardous waste for RCRA purposes and therefore not subject to RCRA waste determination requirements.

CERCLA Applicability

The preamble of the proposed rule suggests that CERCLA liability may arise out of CO2 GS projects due to "potential USDW impacts", presence of impurities in the stream, and the potential for reaction products to migrate from the injection zone. 73 Fed. Reg. 43492, 43497 (July 25, 2008). EPA also states that (CERCLA exempts from liability certain "federally permitted releases" including releases in compliance with a UIC permit under SDWA. Therefore, Class VI requirements and permits will need to be carefully structured to ensure that they do not "authorize" inappropriate hazardous releases. This would include clarifying if there are potential releases from the well which are outside the scope of the Class VI permit.) 73 Fed. Reg. at 43504.

EPA’s suggestion that CERCLA liability may apply to CO2 GS projects raises concern among the electric power industry. Because EPA raised this as a potential issue, businesses and investors may be reluctant to support GS projects faced with a potential for CERCLA liability hanging over their heads. In order to prevent any discouragement of development in CO2 GS projects, EPA should provide confirmation in the final regulations that injection of CO2 into a permitted injection zone does not constitute a "release" for purposes of RCRA or CERCLA. EPA should also take the opportunity to dispel the CERCLA liability concerns by developing appropriate language to provide the clarity and assurance needed to promote continued research, development and deployment of CO2 GS projects.Letter ID: 0234

Commenter: Steven B. Corneli Organization: NRG Energy, Inc.

Letter ID: 0234 Comment ID: 23158 Letter Lines: 51 to 58

Comment Code: 1330 1.1.3.1 Support use of GS in general

Comment: capacity--enough to power nearly 20 million homes. NRG believes that emissions of GHGs from power generation and ot her sectors must be reduced, both domestically and internationally, to su ccessfully address climate change, and that commercially attractive, safe and environmentally secure carbon capture and sequestration will be critical for that su ccess. Headquartered in Princeton, NJ,

NRG is a member of the U.S. Climate Action Partnership (USCAP), a group of business and environmental organizations calling for mandatory legislation to reduce greenhouse gas emissions.

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: 0234 Comment ID: 23159 Letter Lines: 60 to 67

Comment Code: 1420 1.2.1.1 Support the GS rulemaking

Comment Code: 2020 1.5.1 Support Class VI designation

Comment: NRG appreciates the substantial efforts wh ich have been part of this proposal development governing CO2 injection for th e purpose of GS. As a company, NRG is committed to effectively addressing climate change, and believes that GS is a critical component for the reduction of CO 2 emissions. In general, NRG supports

and commends the efforts of the EPA to develop a rational appr oach that would (1) create a new category of injection wells (i.e., Class VI) under the Underground Injection Cont rol (UIC) Program and (2) establishes Federal regulations that are specifi cally tailored to CO2 inject ion for GS. However, we

Individual Response: EPA agrees that tailored requirements for Class VI wells are necessary to address the unique nature of in jecting large volumes of CO2 a nd to ensure that USDWs are protected from endangerment. The GS rule c ontains tailored requirements for the permitting, geologic site characterization, AoR and corre ctive action, well construction, operation, mechanical integrity testing, monitoring, well plu gging, post-injection site care, and site closure of GS wells that directly addre ss issues unique to the nature of large-scale CO2 injection for GS.

The EPA believes the final rulemaking falls within EPA’s authority under the SDWA. EPA clarifies that the SDWA provides EPA with the authority to develop federal minimum requirements for underground injection, such as GS , that are directly related to protecting

1USDWs from endangerment. Thus, EPA does not have authority under the SDWA to address

other issues related to CCS, such as capture and transportation.

Letter ID: 0234 Comment ID: 23160 Letter Lines: 67 to 72

Comment Code: 6000 3. Cost of the Proposed Rule

Comment: regulations that are specifi cally tailored to CO2 inject ion for GS. However, we are concerned about several technical requirements of th e proposed rules that would substantially increase the cost of GS without e nvironmental benefits. It is essential that EPA develop a regulat ory framework that encourages the commercial deployment of GS, otherwise effo rts and investments to develop carbon capture technology will be discouraged.

Individual Response: EPA believes that the GS rule requir ements are necessary and appropriate to address the unique challenges posed by large- scale GS including large injection volumes, the relative 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 geologic formations. EPA acknowledges that the Class VI requirements ha ve associated costs beyond baseline (Class I industrial wells) costs, and belie ves these costs are necessary a nd appropriate to address the unique challenges posed by large-scale GS incl uding 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.

The Agency clarifies that sequestration costs are expected to be a small component of total CCS project costs. EPA estimates that the GS rule requirements amount to approximately 2 percent of the total CCS project costs, according to the cost analysis for the final GS rule, which is in the rulemaking docket.

EPA also disagrees that the GS rule does not provide benefits of protecting USDWs. The GS rule contains tailored requirements to ensure that wells are appropriately pe rmitted, sited, constructed, operated, monitored, and closed in a manner th at protects USDWs from endangerment.

Letter ID: 0234 Comment ID: 23161 Letter Lines: 78 to 90

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

USDWs in certain circumstances

Comment: Injection Zones for Geol ogic Sequestration (GS)

The proposed rule limits GS to only those ge ologic formations that are below the lowermost underground source of drinking water (USDW). Prohibiting injection

between and/or above the lowermost USDW would exclude GS in many potential storage reservoirs throughout the US that could be utilized for injection while still ensuring protection of USDWs. The petroleum industr y has demonstrated that

2they can operate CO2 injection wells for EOR/EGR while preventing USDW endangerment. We believe protection of va luable drinking water sources could be accomplished through proper site selection and characterization. NRG recommends using science based techniques to demons trate that geologic conditions exist that will prevent CO2 migration to US DWs. Under these circumstances, the lowermost USDW restriction would be unnecessary.

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 inject ion into non-USDW formations above and/or between USDWs. Determinations about the appropriateness of a wa iver would be made by the Director, based on evaluation of site-specific conditions.

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 high quality 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: 0234 Comment ID: 23162 Letter Lines: 94 to 103

Comment Code: 3310 2.2.1.1 Comments in favor of requiring computational models to delineate the AoR (seeking comment)

Comment: 1. Use of Computational Mode ls for Area of Review

The EPA requested comment on the proposed ru le regarding the use of modeling for area of review (AoR). NRG supports th e use of computational models for determination of the AoR for geologic se questration projects. The use of such models is already being used in the UIC program for "no-migration" petitions for Class I injection wells. We believe th e use of modeling fo r determining the pressure effects associated with the underground injection process is an appropriate confirming process for safe s ite selection and corrective action to address potential risk presented by GS.

Individual Response: EPA acknowledges the commenter’s s upport and agrees that predicting

3the complex multiphase, buoyant flow of the CO 2, co-injectates, and compounds that may be mobilized due to injection requires the sophistica tion of computational models, as required at §146.84(c)(1). Models can predict CO2 fate and tr ansport, as well as changes in formation pressure, in three dimensions, as a function of ti me in order to delineate the subsurface storage site and the AoR. Models can account for site-specific and predicted operating conditions as well as geologic heterogeneities a nd potential migration through fau lts, fractures, and artificial penetrations.

Letter ID: 0234 Comment ID: 23163 Letter Lines: 105 to 117

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

Comment: 2. AoR Reevaluation

The proposed rule requires a re-evalua tion of the AoR determination on a frequency not to exceed once every ten years. NRG agrees with the Carbon Sequestration Council’s recommended alterna tive approach to re-evaluate the AoR only when site specific operation and m onitoring data suggest that there is a

need for a new evaluation of the AoR. Periodic AoR re-evaluation will most likely be necessary given the enormous vol umes of CO2 that would be injected into the subsurface, the lengthy timeframes likely for GS operations, and the potential uncertainty of the original m odel prediction. We believe that it is impractical and cost prohibitive to requi re re-evaluation of the AoR on a fixed

schedule. Re-evaluation of the AoR shoul d only be conducted when monitoring and testing data are determined to be inc onsistent with the modeling results.

Individual Response: EPA agrees that site-specific fact ors should be considered in the

reevaluation schedule, and notes that the AoR and corrective acti on plan must specify the sitespecific monitoring and operationa l conditions that warrant r eevaluation, as specified in §146.84(b)(2)(ii). In addition, the Director has discretion to require more frequent AoR

reevaluation if he or she has r eason to believe, based on site-speci fic information, that a five-year

reevaluation schedule is not su fficiently protective of USDWs. However, EPA believes that setting a minimum reevaluation frequency is appr opriate. In the final rule, the Agency changed the minimum frequency for the AoR reevaluation at §146.84(e) from 10 years to at least every 5 years in the final GS rule. EPA believes that this revised frequency addresses commenters'

concerns about the inherent unc ertainties in modeling CO2 move ment, the emerging nature of GS technology, risk-based targeti ng of monitoring activ ities, and the unique nature of CO2 GS.

EPA believes that periodic AoR reevaluation at a set frequency is necessary to ensure protection of USDWs from endangerment a nd address the uncertainties i nherent in predictive modeling. Periodic AoR reevaluations at §146.84( e) ensure that a deliberate effo rt is made to verify, based on monitoring and operational data, that the CO2 plume is moving within the subsurface as predicted. EPA believes that less frequent reevaluations may not be sufficient to appropriately model plume and pressure front movement, estab lish conditions for corre ctive action, and ensure protection of USDWs from endangerment.

4EPA clarifies that if site m onitoring data agrees with the existing AoR delin eation, 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: 0234 Comment ID: 23164 Letter Lines: 119 to 126

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

Comment: 3. Corrective Action

EPA proposes to allow a phased approach to corrective action for GS wells. NRG agrees that this approach is prudent and practical give n the enormous volumes of CO2 that would be injected for a geologi c sequestration project. Implementation of a phased corrective acti on to address risk associ ated with artificial penetrations such as plugged well borings would reduce project costs and also reduce the regulatory burdens of the permitting process.

Individual Response: EPA acknowledges the commenter’s s upport of phased corrective action and agrees that phased corrective action may provide many benefits to a project including, but not limited to, spreading the burden of cost, avoi ding delays in project start-up, allowing for use of future, improved corrective act ion techniques and addressing unanticipated changes in the movement of the CO2 plume or pressure front . EPA believes that the phased corrective action approach is appropriate for GS projects, and retained it at §146.84(b)(2)(iv) in the final GS regulation.

Letter ID: 0234 Comment ID: 23165 Letter Lines: 128 to 145

Comment Code: 3820 2.3.1 Well construction procedures

Comment: Proposed Class VI Well Standards

The proposed Class VI well construction re quirements are as st ringent as those for hazardous waste injection (Class I). NRG believes that this is not a logical or appropriate regula tory approach to en sure protection of USDWs. The injection

of CO2 does not warrant the same level of regulations as hazardous waste injection.

The primary issues associated with CO2 injection for GS are related to the enormous volumes and the mobility of CO2 in the subsurface. However, the Class VI requirements do not addr ess these issues. These st ringent well construction requirements will only increase the co sts of operation resulting in no additional protection of USDWs. NRG ag rees with the Carbon Sequestration

Council’s recommendation to use the Class II regulations as a starting point for the development of the Class VI regu lations. The oil and gas industry has several decades of CO2 injection experi ence with the Class II UIC program and

5has demonstrated that the construction requirements for Class II injections wells are sufficient to protect human health and the environment.

Individual Response: EPA recognizes that the oil and gas industry has decades of experience injecting CO2 for the purpose of enhanced recovery and that many of the wells used for ER may

be suitable for GS. However, EPA believes that GS is sufficiently different from Class II ER operations to warrant the tail ored requirements for Class VI wells. EPA believes that the construction requirements for Class VI wells , along with other requirements, e.g., site

characterization, are tailored to address the unique issues associat ed with large-scale GS and are necessary to protect USDWs fr om endangerment and that less er standards could potentially endanger USDWs. EPA believes that the constr uction requirements most directly address corrosivity concerns, while the large volumes a nd the mobility of CO2 in the subsurface are addressed by the siting requirements at §146.83.

For example, the volume of CO2 anticipated to be injected in Class VI wells is significantly greater than for Class II wells, and reservoir pre ssure conditions will be different, with Class VI injection operations involving large volumes of CO2 and likely having hi gher pressures within their storage formations than Class II ER project s. Therefore, Class VI GS reservoir pressures will increase more in comparison to Class II ER during the injection phase of the GS project.

EPA acknowledges that the Class VI requirement s have associated costs beyond baseline costs assumed in the cost analysis for this rule (based on an assumption that Cla ss I industrial wells are the baseline). EPA believes that the requirements for Class VI wells provide multiple layers of USDW protection from endangerment that justif y the cost of meeting the requirements. The Agency clarifies that the purpose of the GS regulation, promulgated under authority of the SDWA, is to ensure that, where GS is deployed, it is conducted in a manner that protects USDWs from endangerment.

Letter ID: 0234 Comment ID: 23166 Letter Lines: 149 to 159

Comment Code: 4110 2.4.1.1 Injection pressure limitations

Comment: 1. Injection Pressure Limitations

The proposed rule does not allow injecti on pressures that exceed 90% of the fracture pressure of the receiving forma tion. NRG believes that this rule of thumb would be an over protective require ment and would not be necessary for ensuring containment of CO2 in the receiving formation. The existing requirement under the UIC regulations for Class II we lls allows injecti on pressure limits that are based on site-specific conditions (i.e., well tests and geomechanical studies) that have been prove n to be effective in prot ecting the confining zone.

We believe a standard similar to Class II injection wells woul d be appropriate

for GS.

Individual Response: EPA believes the operating requirement s for Class VI wells, including the pressure limitation, are necessary to protect USDWs from endangerment by providing multiple

6safeguards to ensure that well in tegrity, containment of fluids w ithin the injection zone, and the integrity of the confining zone.

EPA emphasizes that injection pressure limits ar e important to protect against fracturing of the confining zone, and that the requ irement at §146.88(a) that the pressure in th e injection zone not exceed 90 percent of the fracture pressure provides a margin of safety in the well operation and protects USDWs from endangerment. If the Dire ctor determines, based on a review of the information collected as part of site characterization, th at a lower injection pr essure limitation is appropriate, the Director has the authority to set a lower limit in the operating permit than the

limit established in the rule.

EPA notes that the pressure limitation at §146.88 (a) accounts for site-specific conditions. During the site characterization process, owners or ope rators must submit data about the geology of the site, as specified at §146.82(a), including data on known or suspect ed faults and fractures and geomechanical information on fractures, stress, ductility, rock strengt h, and in situ fluid pressures within the confining zone. The Director will use these data to determine appropriate limits on injection.

EPA is developing guidance on site characterization for GS projects to assist owners or operators in meeting the requirements of §146.82 and to assist directors in evaluating permit applications. The guidance will describe recommended approach es for characterizing the regional geology and hydrogeology of a proposed site and performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confin ing zone. EPA is also developing guidance for primacy agencies that will include recommended a pproaches for evaluating owner or operatorsubmitted data in setting permit conditions. The gu idance will be available on EPA's web site, at http://water.epa.gov/type/groundwater /uic/wells_sequestration.cfm.

Letter ID: 0234 Comment ID: 23167 Letter Lines: 161 to 167

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

Comment: 2. Continuous Monitoring

NRG supports continuous monitoring of the annular and injection pressure for well integrity purposes. However, the proposed requirement for continuous monitoring of the annular fluid volume is impractical and unnecessary. We

recommend continuous measurement of the a nnular pressure as a means of leak

detection instead of th e annual fluid volume.

Individual Response: EPA believes that monitoring of annulus fluid volume is an important method for verifying that the well system is in tact, and knowing the annulus fluid volume is necessary for monitoring annulus pressure. While this requirement has until now been limited to Class I hazardous waste injection wells, the hi gh volumes and supercritical nature of the injectate, the potential geomechanical stresses in the wellbore, and the pot ential for movement of the buoyant CO2 in the event of a MI loss make it an important safety consideration for GS

7projects. Continuous pressure m onitoring allows immediate iden tification of corrosion-related well integrity loss. EPA agrees with the commen ter that recording annul us fluid volume may not be appropriate. However, EPA believes that knowing annulus fluid vol ume as required at §146.88(e) is a necessary component of monitoring well mechanical integrity, but believes that knowing the annulus fluid volume added is sufficient to meet the intent of the requirement. The final GS rule requires that ow ners or operators use continuou s recording devices to monitor injection pressure, rate and volume; as well as the pressure on the annulus between the tubing and the long string casing. It also modifies the requirement in th e proposed rule to continuously monitor annulus fluid volume; it now requires re cording of annulus fluid volume added. See §§146.88(e); 146.89(b); and 146.90(b).

Fluid level can be detected using acoustic t echniques (Schubert, 1998). The Texas Class I well regulations for industrial wells currently require continuous monitoring of annulus pressure and volume, and the majority of injection wells in Ohio conduct continuous monitoring (GWPC, 2006). At least one commenter indicated that the technology required fo r continuous monitoring is currently available and should not presen t an undue cost burd en. Continuous annulus monitoring is also conducted at the commercial-scaled carbon capture and geologic sequestration operation at the In Salah, Algeria natural gas plan t where more than 3 million tons of CO2 have been sequestered since 2004. The technology for con tinuous monitoring is available, is currently in fairly wide use, and the costs are not burdens ome, especially given the operational and safety

considerations addressed.

Letter ID: 0234 Comment ID: 23168 Letter Lines: 169 to 177

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

Comment: 3. Tracers

NRG opposes any requirement to use tracers for leak detection b ecause leaks from properly permitted injection wells are not likely to occur. The use of tracers

will not be effective in the detection of CO2 releases in the subsurface and will not ensure the protection of USDWs. Tr acers are more likely to cause "false positives" by accidental leaks from the equipment on the surface. The Class VI regulations are designed to prevent the kind of leakage that the tracers are

intended to detect.

Individual Response: EPA believes that, in some circumst ances, tracers can be an important component of a multifaceted approach to mon itoring GS projects. However, the Agency recognizes that tracers may not be appropriate in all GS project s. For this reason, EPA does not require the use of tracers at all GS sites; however, the Director ha s discretion to require their use

if he/she determines that the use of tracers could improve mon itoring of the site and enhance USDW protection from endangerment.

While the intent of the GS regulations is to prevent leaks of CO2 to USDWs, EPA clarifies that all of the protective components of the regulation, includin g a comprehensive monitoring

8program per §146.90 (which includes testing of th e well, ground water quality monitoring, and tracking of the CO2 plume and pressure front) support a multi-barrier approach to protecting USDWs. Additionally, some studies (e.g., Phel ps and Cole, 2008; Hovorka et al., 2004; McCallum et al., 2005) found that tracers can pr ovide useful CO2 monitoring information at injection wells both at depth and at near-surface locations. At Fr io, tracers enabled quantification of CO2 plume behavior and provided a techniqu e for model validity tes ting (McCallum et al., 2005). EPA will continue to track research related to tracer use. The Agency plans to, every six years, collect and review data on GS projects to determine whether the appropriate amount and types of information and appropriate documenta tion are being collected, and to determine if modifications to the requirements are appropriate or necessary.

Letter ID: 0234 Comment ID: 23169 Letter Lines: 179 to 187

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

Comment Code: 4660 2.6.6 Geochemical monitoring

Comment: Monitoring Requirements

The preamble of the proposed rule stat es that the "monitoring of subsurface geochemistry and the position of the CO2 plume and pressure front are necessary to verify predictions of plume moveme nt, provide inputs for modeling, identify needed corrective actions, and target geochemical and surface monitoring activities." 73 Fed. Reg. at 43514. NRG belie ves that the proposed monitoring requirements are excessive and unjustified. The use of monitor wells or seismic data would be needed to verify the m odel predictions. In particular, it is

Individual Response: EPA disagrees that the monitoring requirements in the GS rule are excessive or unjustified. In addition to monitoring to track the movement of the CO2 plume and pressure front, EPA believes that monitoring above the confining layer is an important part of a rigorous monitoring program. Such monitoring can provide an early warning that the plume may be approaching a USDW. The final rule, at §14 6.90(d), requires periodic monitoring of the ground water quality and geochemical changes above the confining zone(s). EPA also believes that geophysical (e.g., seismic) methods are useful for plume tracking at GS sites. For this reason, the final rule at §146.90(g) requires the use of indirect me thods (e.g., seismic, electrical, gravity, or electromagnetic surveys and/or down- hole CO2 detection tools) unless the Director determines, based on site-specific geology that such methods are not appropriate

EPA is developing guidance on testing and mon itoring to assist owne rs or operators and Directors in evaluating requi rements under §146.90, including pr oposed monitoring plans. The guidance describes available technologies a nd recommended approaches for implementing a testing and monitoring plan, including pre-ope rational geophysical l ogging and testing of injection wells, MITs, injecti on well testing during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, a nd soil gas and surface air monitoring which may be required by the UIC Director for specific GS projects. Th e guidance can be found on EPA’s website at http://water.epa.gov/type/gr oundwater/uic/wells_sequestration.cfm.

9EPA also acknowledges that complete coverage of the potential plume area or leakage in the subsurface is not possible through the use of monitoring wells. However, data from an appropriate number of monitori ng wells sited based on site-speci fic information will provide

direct information that is not otherwise obtai nable and, along with othe r monitoring data, will support a broader understanding of fl uid behavior at the site.

EPA adds that the iterative process of monitoring, mode ling, and AoR reevaluation is appropriate to verify that the CO2 plume and pressure front are moving through the subsurface as predicted, verify the accuracy of the de lineation model (or identif y needed changes), and refine testing and monitoring activities to ensu re that USDWs are protected from endangerment and that there would be adequate warning of potential problems at the site before any endangerment could occur.

Letter ID: 0234 Comment ID: 23170 Letter Lines: 187 to 193

Comment Code: 4650 2.6.5 CO2 plume and pressure fr ont tracking (seeking comment)

Comment: data would be needed to verify the m odel predictions. In particular, it is impractical and cost prohibitive to meas ure the exact location of the CO2 plume and pressure front using monitor wells. The monitor wells would be very expensive to install and may create a poten tial pathway for migration of CO2. In addition, plume or pressure front monito ring have never been necessary or required under the Class I hazardous wa ste injection well program because experience has shown that it is not necessary to veri fy the model predictions.

Individual Response: EPA believes that pressure monitoring in the injection zone is necessary to track the development and movement of the pressure front and CO2 plume. Monitoring can also identify needed remedial actions, provide inputs for AoR reevaluation modeling, evaluate predictions of plume movement, and target additional geochemical and surface monitoring needs. Knowledge of the location of the CO2 plume and the associated pressure front will also assure the public that GS projects are pr oceeding according to plan, provide sufficient information to the owner or operator and Director, or allow for appropriate actions to address any indication that USDWs may be endangered.

EPA believes that monitoring using wells in the injection zone, e.g., for pressure monitoring as required at §146.90(g)(1), can be safely performed if the wells are constructed to prevent flow between the injection zone a nd USDWs or other layers above the confining zone. Such construction technologies exist and have been us ed in the oil and gas industry for years. EPA believes that properly constructed monitoring wells will be a safe way to obtain the data that is essential to ensure that the inje cted CO2 remains confined in the injection zone and that pressure changes are not causing movement of formation or other fluids. EPA is developing guidance on

well construction that will in clude recommendations for mon itoring well construction. The guidance will be available on EPA’s website at http://water.epa.gov/type/groundwat er/uic/wells_se questration.cfm.

10To mitigate the risk of fluid movement, EPA re quires owners and operators to submit a testing and monitoring plan that describes how the ow ner or operator plans to site and construct monitoring wells.

EPA is developing guidance on testing and mon itoring to assist owne rs or operators and Directors in evaluating requi rements under §146.90, including pr oposed monitoring plans. The guidance describes available technologies a nd recommended approaches for implementing a testing and monitoring plan, including pre-ope rational geophysical l ogging and testing of injection wells, MITs, injecti on well testing during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, a nd soil gas and surface air monitoring which may be required by the UIC Director for specific GS projects. Th e guidance can be found on EPA’s website at http://water.epa.gov/type/gr oundwater/uic/wells_se questration.cfm.

EPA acknowledges the commenters' concern abou t the cost of monitoring. However, EPA believes that monitoring is essential for protecti on of USDWs at GS sites. Although a significant

cost in absolute terms, monito ring costs are expected to be a small fraction of site operating costs, according to EPA's cost analysis for the GS rulemaking (which is av ailable in the docket).

Letter ID: 0234 Comment ID: 23171 Letter Lines: 181 to 193

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

Comment: The preamble of the proposed rule stat es that the "monitoring of subsurface geochemistry and the position of the CO2 plume and pressure front are necessary to verify predictions of plume moveme nt, provide inputs for modeling, identify needed corrective actions, and target geochemical and surface monitoring activities." 73 Fed. Reg. at 43514. NRG belie ves that the proposed monitoring requirements are excessive and unjustified. The use of monitor wells or seismic data would be needed to verify the m odel predictions. In particular, it is impractical and cost prohibitive to meas ure the exact location of the CO2 plume and pressure front using monitor wells. The monitor wells would be very expensive to install and may create a poten tial pathway for migration of CO2. In addition, plume or pressure front monito ring have never been necessary or required under the Class I hazardous wa ste injection well program because experience has shown that it is not necessary to veri fy the model predictions.

Individual Response: EPA disagrees that plume and pressure front monitoring are not justified for Class VI wells. The Agency recognizes that wh ile there are similarities between injection of wastes for disposal (Class I) and GS, there are significant differences as well. Important unique considerations for GS include the buoyancy of CO2, its corrosivity when in contact with water, its low viscosity (i.e., high mobility), and the very large injection volumes that are anticipated. There is also a degree of uncertainty regarding the behavior of large volumes of CO2 in the

subsurface. Given these characteri stics of anticipated GS projects, EPA believes that plume and pressure front monitoring at §146.90(g) are justif ied to provide early warning of any unforeseen fluid movement that might endanger USDWs.

11The final rule at §146.90(g) requir es owners or operators to pe rform monitoring to track the extent of the CO2 plume and pressure front. The owner or operator must use direct methods to monitor for pressure changes in the injection zone. Indirect met hods (e.g., seismic, electrical, gravity, or electromagnetic surveys and/or down- hole CO2 detection tools) are required unless

the Director determines, based on site-specific geology that such methods are not appropriate.

EPA believes that pressure monitoring in th e injection zone is n ecessary to track the development and movement of the pressure front and CO2 plume. Knowledge of the location of the CO2 plume and the associated pressure front w ill also assure the public that GS projects are proceeding according to plan, provide sufficien t information to the owner or operator and Director, or allow for appropr iate actions to address any indication that USDWs may be endangered.

EPA believes that monitoring using wells in the injection zone, e.g., for pressure monitoring as required at §146.90(g)(1), can be safely performed if the wells are constructed to prevent flow between the injection zone a nd USDWs or other layers above the confining zone. Such construction technologies exist and have been us ed in the oil and gas industry for years. EPA believes that properly constructed monitoring wells will be a safe way to obtain the data that is essential to ensure that the inje cted CO2 remains confined in the injection zone and that pressure changes are not causing movement of formation or other fluids.

§146.90(g)(2) requires owners or oper ators to track the position of the CO2 plume using indirect methods (e.g., seismic, electrical, gravity, or electromagnetic surveys and/or down-hole CO2 detection tools), unless the Direct or determines based on site-spe cific geology, that such methods are not appropriate. For example, geophysical met hods are difficult to execute in areas that are structurally and topographically co mplex or where lithologies have limited contrast in density, porosity, permeability, and other physical properties. EPA clarifies that this determination will be made by the Director based on the site-specific geologic information submitted by the owner or operator with the permit application.

EPA believes that this approach provides flexibility to develop a site-specific monitoring plan, ensures that direct monitoring is available to track the movement of the CO2 and validate models, and recognizes that indirect techniques are not appropriate in all situations. The owner or operator's approved testing and monitoring pl an will include the site-specific details, technologies, testing and monitoring freque ncies, and other pertinent information.

EPA also acknowledges that complete coverage of the potential plume area or leakage in the subsurface is not possible through the use of monitoring wells. However, data from an appropriate number of monitori ng wells sited based on site-speci fic information will provide

direct information that is not otherwise obtai nable and, along with othe r monitoring data, will support a broader understanding of fl uid behavior at the site.

Letter ID: 0234 Comment ID: 23172 Letter Lines: 195 to 203

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

12CFR 146.85)

Comment: Financial Assurance

NRG commends the EPA for allowing flexib ility on financial assurance for GS wells. Allowing flexibility will enable operators to use a combination of approaches and instruments to meet the financial requirements over the life of the injection well operation. We believe th at it would be a mistake to impose any restrictions on the types of financial assurance or instruments that can be

used for GS wells. We recommend that this approach be retained in the final

rule.

Individual Response: EPA agrees that it is appropriate to al low a flexible approach for financial responsibility, which is why ow ners or operators may choose from a variety of financial instruments to meet their financial responsibilit y obligations, provided th e Director determines that the operator's proposed financ ial responsibility demonstration is adequate to prevent USDW endangerment by paying for each activity for which financial responsibility must be demonstrated, including correctiv e action on wells in the AoR, in jection well plugging, PISC and site closure, and emergency and remedial response. The allowabl e instruments are identified at §146.85(a).

Owners or operators may select and use multiple instruments for specific project activities. See the final rule and preamble for further discus sion of EPA's final a pproach to financial responsibility. EPA also anticipates that the availability of thir d-party GS financial instruments will grow in response to demand for such instruments by Class VI well owners or operators.

Letter ID: 0234 Comment ID: 23173 Letter Lines: 205 to 220

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

Comment: RCRA Applicability

The preamble of the proposed rule suggests that CO2 injected for GS projects may

be considered hazardous waste for RCRA purposes. 73 Fed. Reg. at 43503. EPA’s brief discussion of the potential for inj ected CO2 streams to be characterized as hazardous waste are causing concern among the electric power industry and

could have an effect on the future development of carbon capture and sequestration projects. The premise that CO2 could be characterized as a hazardous waste would likely prove detrimen tal to project development. The RCRA

definition of "solid waste" is limited to "solid, liquid, semi-solid, or contained gaseous material." RCRA 1 004(27). Because the gas and liquid (supercritical) phases involved in GS do not meet this definition, reading of federal law would suggests that the CO2 st ream for GS should not be considered a "solid waste". EPA should clarify that the gas and liquid phases of the CO2

stream is not a solid or hazardous wast e for RCRA purposes and therefore not subject to RCRA waste determination requirements.

13Individual 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 period for that rule.

Furthermore, EPA disagrees that the Class VI requirements themselves, necessarily have any implications for whether a particular material is a RCRA “solid wast e” or implicates CERCLA liability, as EPA understands the comment to s uggest. EPA notes that the GS rule is not promulgated under either of those statues, and furt her, the applicability of those statutes will not be determined under the SDW or the terms of the GS rule, but rather according to those statues themselves and any implementing regulations may apply.

EPA adds that promoting the use of GS is outsi de the scope of the GS rule. Rather, the purpose of the GS regulation is to ensu re that, where deployed, GS is c onducted in a manner that protects USDWs from endangerment.

Letter ID: 0234 Comment ID: 23174 Letter Lines: 222 to 245

Comment Code: 1640 1.3.4 CERCLA issues (seeking comment)

Comment: CERCLA Applicability

The preamble of the proposed rule suggest s that CERCLA liability may arise out of CO2 GS projects due to "potential USDW impacts", presence of impurities in the stream, and the potential for reac tion products to migrate from the injection zone. 73 Fed. Reg. 43492, 43497 (Jul y 25, 2008). EPA also states that (CERCLA exempts from liability certain "federally permitted releases" including releases in compliance with a UIC pe rmit under SDWA. Therefore, Class VI requirements and permits will need to be carefully structured to ensure that they do not "authorize" inappropriate h azardous releases. This would include clarifying if there are pote ntial releases from the well which are outside the scope of the Class VI permit.) 73 Fed. Reg. at 43504.

EPA’s suggestion that CERCLA liability ma y apply to CO2 GS projects raises concern among the electric power industr y. Because EPA raised this as a potential issue, businesses and invest ors may be reluctant to support GS projects faced with a poten tial for CERCLA liability hanging over their heads. In order to prevent any discouragement of development in CO2 GS projects, EPA

1415 should provide confirmation in the final re gulations that injection of CO2 into a permitted injection zone does not constitu te a "release" for purposes of RCRA or CERCLA. EPA should also take the oppor tunity to dispel the CERCLA liability concerns by developing appropriate language to provide the clarity and assurance needed to promote continued research, de velopment and deployment of CO2 GS projects.

Individual Response: EPA notes that the GS rule is no t promulgated under the RCRA or

CERCLA statutes, and further, th e applicability of t hose statutes will not be determined under

the SDWA or the terms of the GS rule, but rather according to those statutes themselves and any implementing regulations that may apply EPA received many comments regarding the applicability of the RCRA regulations and st atute to CO2 streams that are geologically sequestered under the final Class VI UIC well requirements. As a result, EPA has decided to initiate a separate proposed rulemaking specificall y to examine the issue of RCRA applicability to CO2 streams being geologically sequestere d, 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 propos al. The Agency will consider issues particular to RCRA in the context of that separate rulemaking, and recommends that the commenter read that proposed rule when it is published. The Ag ency notes that commenters who wish to submit comments on the RCRA proposal will need to do so during the comment period for that rule.

CO2 itself is not listed as a hazardous substan ce under CERCLA; however, the CO2 stream may contain a listed hazardous substance (such as mercury) or may mobilize substances in the subsurface that could react with ground water to produce listed hazardous substances (such as sulfuric acid). Whether such substances may result in CERCLA liability from a sequestration facility depends entirely on th e composition of the specific CO2 stream and the environmental media in which it is stored (e.g., soil or gr ound water). CERCLA exempts from liability, under CERCLA section 107, 42 U.S.C. 9607, certain “feder ally permitted releases” (FPR) as defined in CERCLA, 42 U.S.C. 9601(10). Class VI permits will need to be carefully structured to ensure that they prevent potential releases from the we ll which are outside the scope of the Class VI permit.

The UIC program Director has authority under SDWA §1423 to address potential compliance issues (e.g., potential releases that may endanger USDWs) resulting from injection violations in the unlikely event that a remedi al response is necessary. Although EPA anticipates that the need for emergency or remedial actions at GS sites wi ll be rare, the GS rule requires, at §146.94, that emergency and remedial response plans be deve loped and updated to address such events and that owners or operators demonstr ate that financial resources are set aside to implement the plans if necessary, per §146.85.

EPA adds that promoting the use of GS is outsi de the scope of the GS rule. Rather, the purpose of the GS regulation is to ensu re that, where deployed, GS is c onducted in a manner that protects USDWs from endangerment.