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.May 14, 2009 Cynthia C. Dougherty

Director

Office of Ground Water and Drinking Water U. S. Environmental Protection Agency 1200 Pennsylvania Ave., NW. Washington, DC 20460

Re: Proposed Rule for Geologic Se questration, Docket EPA–HQ–OW–2008–0390

Dear Director Dougherty:

The organizations identified by the signature s at the end of this letter have been participating in multi-stakeholder group (MSG ) discussions regarding the proposed rule for geologic sequestration (GS) of carbon di oxide under the Safe Drinking Water Act (SDWA), 73 Fed. Reg. 43491-541 (July 25, 2008). We have achieved consensus on specific rule language recommendations for all of the issues addressed in this letter.

As noted in previous letters , the consensus recommendations presented in this letter address only the objective of protecting unde rground sources of dr inking water (USDWs)

under the SDWA and do not address verifi cation requirements for carbon credits. 1 /

1. Basalts, Coal Seams, Salt Caverns, and Shales

We agree that EPA has ample basis for adopt ing rules to regulate GS in hydrocarbon reservoirs and in deep saline formations under the SDWA. For these types of geologic formations, there is a widespread technical consensus on how to assess and manage risks,

what data is needed to charac terize sites, how to select sites, how to conduct injection operations, how to model the behavior of CO 2 in the reservoir, and how to monitor project performance.

There is less technical suppor t on the ability to conduct GS in basalts, coal seams, salt caverns, and shales. As compared with deep saline formations and hydrocarbon reservoirs, the trapping/containment mechanisms of CO 2 and/or operational engineering involved in basalts, coal seams, salt caverns and shales may be signi ficantly different and using identical regulatory language might not be appropriate. In fact, it is not known at this time whether GS (or even injection in some cases) can be done at commercial scale in each of these types of formations – GS ef forts in these formations are still in the experimental stage. Wells in basalts, coal seams, salt caverns and shale formations

1 /

The recommendations presented in this letter reflect a consensus among the signatories on the specific issues addressed; however, some of the sign atories note that their participation should not be interpreted as an express or implied change in views on other issues that may be related to the issues addressed. In particular, CATF, EDF and NRDC re serve the respective views they have expressed regarding the appropriate legal author ity for the rule, the definition of ge ologic sequestration, and necessary requirements needed if injection is to be allowed above the lowermost underground source of drinking water ( see comments to EPA dated December 24, 2008 and letters dated March 17, 2009).Cynthia C. Dougherty May 14, 2009 Page 2 of 12

should be treated as experimental wells unde r Class V, recognizing that completing the process of research, development and demons tration likely will require initial full scale experimental projects in a ddition to pilot projects.

Keeping these wells under Class V would a llow EPA and the states to gain enough experience to develop suitable permitting requirements for such wells and to tailor those requirements at both the pilot and commercial scales until the agencies are ready to regulate such wells under an appropriate class.

To implement this approach, sections 144.6(f), 144.80(f), 146.5(f) a nd the definition of sequestration in 146.81 should be revised. The proposed 144.15 provision that the construction, operation or maintenance of any non-experimental Class V GS well is prohibited should be retained, but only with the understanding that this prohibition is not

intended to limit the size or scal e of any experimental GS operation.

“Class VI. Wells used for geologic sequestration but not including those wells used for geologic sequestrati on that are regulated under another Class. Wells used for geologic seques tration in basalts, coal seams, salt caverns or shales are regulated under Class V as experimental wells until such time as the Administrator establishes separate requirements by rule for the specific type of formation or determines, following public notice and opportunity for comment, that wells used for geologic sequestration of carbon dioxide streams into the speci fic type of formation should be regulated under another class. ”

2. Non-interference principle

EPA notes in the preamble (page 43506), “it is ... possible that multiple owners or operators will be injecting CO 2 into formations that are hydr aulically connected and thus the elevated pressure zones may intersect or interfere with each other.” We have agreed that this possibility should be addressed through a revi sion to the regulations. Until more comprehensive approaches to basin-scale management are developed and based on the proposed definition of “pressure front”, we recommend the adoption of the following addition to §146.94:

“ (e) If an owner or operator obtains evidence that a pressure front associated with one geol ogic sequestration project in tersects or will more likely than not intersect the pressure front or area of review associated with another project, the owner or operator obtaining such evidence must notify the Director. The Director sha ll notify the owner or operator of the other geologic sequestration project. If the Director determines that the pressure front associated with one project interferes or will more likely than not interfere with the ability of another project to comply with the terms of its permit(s), the Director ma y require the owners or operators ofCynthia C. Dougherty May 14, 2009 Page 3 of 12

the interfering or potentially interfer ing projects to m odify operations as necessary to mitigate or avoid such in terference. Such modifications may also include modifications mutually agreed upon by the respective owners and operators and approved by the Director .”

3. Transmissive faults or fractures

The proposed rule in §146.83(a)(2 ) requires a confining z one(s) that is free of transmissive faults or fractures, while §146.81 de fines this term as “A fault or fracture that has sufficient permeability and vertical extent to allow flui ds to move between formations”. We recommend the following m odification to the defi nition in §146.81(d) in order to avoid unduly restricting movement that is merely between formations:

“Transmissive fault or fracture means a fault or fracture that has sufficient permeability and vertical extent to allow fluids to move beyond a confining zone .”

4. Definition of confining zone

The proposed definition of confining zone in §146.81(d) requires that the formation act as “a barrier” to fluid movement, which may be unnecessarily strict. The definition also fails to recognize that it is movement through and beyond the confining zone that needs to be limited. We recommend retaining the current UIC program definition of confining zone as preferable to the proposed definition with one revision to address the possibility that a confining zone for a particular project may be beneath rather than above the injection

zone.

“ Confining zone means a geological formation, group of formations, or part of a formation that is capable of limiting fl uid movement from an injection zone .”

5. Area of review definition and basis

We also suggest that the second sentence of the proposed definition of GS project be

transferred to the definition of area of review as recommended below. This language also reflects a change from “brine” to “formation fluids.”

“

Area of review means the subsurface three-dime nsional extent of the carbon dioxide stream plume and the asso ciated pressure front, as well as the overlying formations, [any USDWs underlying an injection zone alongCynthia C. Dougherty May 14, 2009 Page 4 of 12

with any intervening formations,] 2 / and the surface area above that delineated region .”

In addition, we recommend that the second sentence includ ed both in EPA’s proposed

definition of area of review and in section 146.84(a) be dropped from the definition and retained in section 146.84(a) but modified to read as follows:

“(a) The area of review is based on computational m odeling, as well as monitoring and other operational data , that account for the physical and chemical properties of all phases of the injected carbon dioxide stream.”

The first sentence of section 146.84(a), which dup licates the definition of area of review, should be deleted from section 146.84(a) a nd retained in the definition with the modifications presented above.

6. Area of review and corrective action requirements

In proposed §144.55(a) the rule w ould require Class I, II (other than existing), III or VI permit applicants to identify the location “of all known wells within the injection well’s area of review which penetrate the injecti on zone” or, in the ca se of Class II wells operating over the fracture pressure of the injection formation, “all known wells within the area of review penetrating formations affected by the increase in pressure.”

Since injection in deep saline formations will result in an area of el evated pressure (above the original reservoir pressure) that will be larger than the CO 2 plume and could conceivably affect overlying or underlying formations, we have agreed that the requirement for Class II wells operating above th e fracture pressure should also apply to Class VI wells. This would help prevent the unwanted migrati on of reservoir fluids from the injection zone as a result of the pressu re increase. We ther efore recommend that §144.55(a) be revised to read as follows, with revisions shown in blue:

“(a) Coverage. Applicants for Class I, II, (other than existing), or III, injection well permits sha ll identify the location of all known wells within the injection well's area of review wh ich penetrate the injection zone. In the case of Class II wells that operate over the fracture pressure of the injection formation, applicants shall also identify the location of all known wells within the area of review penetrating formations affected by the increase in pressure

. For such wells which are improperly sealed, completed, or abandoned, the applicant shall also submit a plan consisting of such steps or modifications as ar e necessary to prevent movement of

2 /

The bracketed language should be included to the extent that the regulations authorize GS above USDWs, an issue on which the signatories have expressed differing views in our respective comments on the proposed rule. See footnote 1 above.Cynthia C. Dougherty May 14, 2009 Page 5 of 12

fluid into underground sources of dr inking water (‘‘corrective action’’). Where the plan is adequate, the Dir ector shall incorporate it into the permit as a condition. Where the Direct or’s review of an application indicates that the permittee’s plan is inadequate (based on the factors in §146.07), the Director shall require th e applicant to re vise the plan, prescribe a plan for corrective actio n as a condition of the permit under paragraph (b) of this section, or de ny the application. The Director may disregard the provisions of §146.06 (Area of Review) and §146.07 (Corrective Action) when reviewing an application to permit an existing

Class II well. Applicants for permits for Class VI wells [or for wells in other classes that are used for geolog ic sequestration and do not meet the criteria for §144.6(b)(4)] 3 / shall identify the location of all known wells within the area of review penetrat ing the injection zone and all known

wells within the area of review which penetrate formations affected by the pressure front and shall perform co rrective action as specified in §146.84. ”

7. Well construction

EPA’s proposed §146.86(b)(3) would require the long string casing to be cemented by circulating cement to surface in one or more stages. Yet that may be hard to accomplish in some cases, such as very deep wells. Ther e are also potential disadvantages of this approach with regard to the weight of the cem ent column and its relation to well integrity. Sealing this annulus also eliminates an approach for monitoring the integrity of the cement in that critical interval through the primary confining interval and above. We

recommend that EPA not make this a manda tory requirement. The requirement should also recognize that there may be other technol ogies that could be as effective as cement and centralizers, which may not be feasible in some applications; furthermore, current research and development efforts are likely to yield additional te chnologies the use of

which should not be foreclosed. Accordin gly, we recommend the following language for §146.86(b)(3):

“(3) At least one long string ca sing, using a sufficient number of centralizers, which at a minimum: must be s ealed from within the injection zone upward through the overlying c onfining zone, and must provide adequate isolation of the injection z one and other intervals as necessary for protection of USDWs using cement and/or other isolation techniques. The Director may approve the use of packers or alternative isolation techniques, provided these are demonstrated to be equivalent to cement or more effective to provide adequate isolation and to protect USDWs. ”

3 /

The undersigned, except NRDC which does not support the Group’s proposed bright line definition and language for §144.6(b)(4) ( see MSG letter of Dec. 23, 2008), believe that this clause in

brackets should be included.Cynthia C. Dougherty May 14, 2009 Page 6 of 12

8. Reevaluation of the Area of Review a nd Revision and Maintenance of Plans

Although the proposed §146.84(f) would require “reevaluation” of the AoR at a “minimum” fixed frequency of ten years or “when operational and m onitoring conditions warrant,” the specific language of §146.84 runs the risk that revisions will not be made on a timely basis. We recommend imposing a continual obligation on operators to assess whether the AoR itself, the AoR and corrective action plan and all ot her plans required by the regulations should be revise d, requiring an annua l certification stat ing that the owner or operator has reviewed the circumstances (including operating and monitoring data) during the preceding year to determine whethe r these circumstances warranted a revision of the AoR and any plans, and requiring th at revisions be done when required by the Director as well as when the operator determines that conditions warrant. To accomplish this, it is useful to break down the con cept of “reevaluation” into two ideas – “assessment” of the need to revise the AoR and all plans and the actual process of

“revision.” We believe that these suggestions will result in increased accuracy and reliability in the site performance data while avoiding work that is not warranted by the site data and site performance. Moreover, a continuous obligation to assess whether revisions are needed, when coupled with an annual certificati on requirement (see proposed §146.91(d) below) will create a clear accountability trail for both operator and Director in case of disputes. Given this a nnual certification proce ss, we believe it is unnecessary to require a reeval uation on a fixed basis ever y 10 years in every case.

An annual certification requirement can also be used to enhance the ability of both Director and operators to k eep track of which plans requi re updating and whether or not plans that ought to be update d have in fact been revised. Such a shared understanding is essential if there is to be the “ongoing di alogue” between regulator s and operators that EPA anticipates. We considered the inclusi on of an annual report as described in the preamble at 73 Fed. Reg. 43518, but concluded that the benefits of that particular report would be outweighed by the burden. The an nual certification we are recommending would be much simpler. We recommend:

That §146.84(f) be revised to read as follows:

“(f) (1) Notwithstanding the requirement in paragraph (2)(i) of this subsection to perform a reevaluation of the area of review at the frequency set forth in the area of review and corrective action plan, the owner or operator must also conduct the following whenever warranted by material change in the monitoring and operational data or in the evaluation of the monitoring and operational data by the owner or operator:

“(i) reevaluate the area of review by performing all of the actions specified in paragraphs (c)(1) through (3 ) of this section to delineate the area of review and identify all wells that require corrective action;Cynthia C. Dougherty May 14, 2009 Page 7 of 12

“(ii) perform corrective action on wells requiring corrective action in

the reevaluated area of review in the same manner specified in paragraph (d)

of this section; and

“(iii) submit an amended area of review and corrective action plan or demonstrate to the Director through m onitoring data and modeling results that no change to the area of review and corrective action plan is needed.

“(2) Except as provided in paragraph (3) of this subsection, the owner or operator shall also conduc t a reevaluation by perfor ming all of the actions specified in subparagraphs (1)(i) through (iii) of this subsection:

“(i) Within the time periods specified in the area of review and corrective action plan for conducting su ch a reevaluation of the area of review; or

“(ii) If an area of review eval uation or reevaluation has not been performed pursuant to § 146.84(c) and (d) for the ge ologic sequestration project during the preceding ten (10) y ears, then within six months after the passage of that 10-year period.

“(3) The Director shall waive the re quirement for a reevaluation pursuant to either §146.84(f)(2)(i) or (ii) if th e owner or operator demonstrates to the Director through monitoring and operational data and modeling results, such as those reviewed an nually pursuant to section 146.95, that

such a reevaluation is not wa rranted by material change.”

In addition, we recommend the following new §146.95 :

“146.95 Plan Maintenance and Update

“(a) Owners or operators must submit an annual statement, signed by an appropriate company official, confirming that the company has:

“(i) reviewed the monitoring and operational data that are relevant

to a decision on whether to reevalua te the area of review and the monitoring and operational da ta that are relevant to a decision on whether to update a plan identified in §146.82(p) or (u) through (x) or the quality assurance plan for all testing a nd monitoring requirements; and “(ii) determined whether any updates were warranted by material change in the monitoring and operationa l data or in the evaluation of the monitoring and operational data by the owner or operator.Cynthia C. Dougherty May 14, 2009 Page 8 of 12

“(b) Owners or operators must su bmit either the updated plan or a summary of the modifications for each plan for which an update was determined to be warranted pursuant to subsection (a) of this section. The Director may require submission of copies of any updated plans and/or additional information regarding whethe r or not updates of any particular plans are warranted.

“(c) The Director may require the re vision of any required plan whenever

the Director determines that such a revision is necessary to comply with the requirements of this subchapter.”

9. Emergency Response

With respect to the emergency and remedial response section, we propose two changes – change §146.94(b)(4) to read:

“Implement the emergency and reme dial response plan approved by the

Director , and keep the Director apprized of the implementation .”

and §146.94(d) to read:

“The owner or operator must notify the Director and obtain his approval prior to conducting any well workover or other remedia tion measures not listed in the emergency and remedial response plan .”

It should be noted that the language chosen here for §146.94(d) relates specifically to remediation measures and not to emergency responses, which should not be delayed to seek approval when immediate response actio n is necessary. Ever y effort should be taken to ensure that emergency responses are comprehensively a ddressed in the plan, including appropriate notification provisions and timeframes, but emergency responses should not be delayed when awaiting approvals could impair the effectiveness of the

response.Cynthia C. Dougherty May 14, 2009 Page 9 of 12

Conclusion

The undersigned submit these recommendations with the request that the

recommendations be considered for inclusion in a potential notice of data availability and as a basis for revising the respective provi sions in the final rule . In addition, we are committed to continuing our discussions with an objective of developing additional specific recommendations for improvement of a final rule that coul d be adopted by no later than your scheduled da te in late 2010 or early 2011.

Sincerely,

John McManus Vice President, Environmental Services

American Electric Power

Kyle Isakower Director, of Policy Analysis

American Petroleum Institute

Michael E. Moore Vice President External Affairs & CCS Business Development

Blue Source LLC

D. Brian Williams CO2 Storage Manager BP Alternative Energy North America Inc.Cynthia C. Dougherty May 14, 2009 Page 10 of 12

Karen St. John Director Regulatory Affairs

BP America Inc.

Robert F. Van Voorhees Counsel to the Carbon Sequestrati on Council (CCS Contact Group)

Kurt Waltzer Carbon Storage Development Coordinator

Clean Air Task Force

Jeff W. Sheets Sr. Vice President, Planning & Strategy ConocoPhillips

Ronald T. Evans Senior Vice President, Reservoir Engineering Denbury Resources Inc.

Darlene Radcliffe Director, Environmental Technology & Fuel Policy Duke EnergyCynthia C. Dougherty May 14, 2009 Page 11 of 12

William L. Fang Deputy General Counsel

Edison Electric Institute

Scott Anderson Senior Policy Advisor, Climate and Air Program

Environmental Defense Fund

Michael S. Beer Vice President, Federa l Regulation and Policy

E.ON U.S. LLC

Tiffany Rau Manager, Policy & Communications Hydrogen Energy International LLC

George Peridas

Scientist Climate Center

Natural Resources Defense CouncilCynthia C. Dougherty May 14, 2009 Page 12 of 12

Al Collins Senior Director, Regulatory Affairs Occidental Petroleum Corporation

Kevin Wanttaja Manager, Environmental Services Salt River Project

John A. King CO2 Manager - Americas Shell Exploration and Production

Karl R. Moor

Vice President and Asso ciate General Counsel Southern Company

L. Stephen Melzer

President Texas Carbon Capture & Storage Association

cc: Steve Heare Ann Codrington

Bruce Kobelski Suzanne Kelly

Lee WhitehurstLetter ID: 0294

Commenter: John McManus Organization: American Electric Power

Letter ID: 0294 Comment ID: 25305 Letter Lines: 37 to 46

Comment Code: 1000 1. General and Administrative Comments

Comment: [FN:1] The recommendations presented in this letter reflect a consensus among the signatories on the specific issues addressed; however, some of the signatories note that their participa tion should not be interpreted as an express or implied change in views on othe r issues that may be related to the issues addressed. In particular, CATF, ED F and NRDC reserve the respective views they have expressed regard ing the appropriate legal authority for the rule, the definition of geologic sequestration, and necessary requirements needed if injection is to be allowed above the lowermost underground source of drinking water (see comments to EPA dated Decem ber 24, 2008 and letters dated March 17, 2009).

Individual Response: EPA acknowledges the comment. Pleas e see the remainder of EPA's responses to this comment le tter and responses to comments from CATF, EDF, and NRDC for

further details. For additional information on EP A's final regulatory a pproach, please see the final rule and preamble as we ll as the rulemaking docket.

Letter ID: 0294 Comment ID: 25306 Letter Lines: 50 to 55

Comment Code: 2123 1.6.1.1 Comments in favor of in jection into deep saline

Comment: We agree that EPA has ample basis for adopting rules to regulate GS in hydrocarbon reservoirs and in deep salin e formations under the SDWA. For these types of geologic formations, there is a widespread technical consensus on how to assess and manage risks, what data is needed to characterize sites, how to select sites, how to conduct injection ope rations, how to model the behavior of CO2 in the reservoir, and how to monitor project performance.

Individual Response: EPA acknowledges the comment and ag rees that GS into hydrocarbon

reservoirs and saline formations is appropriate where a geolog ic system (e.g., injection and confining zones) is identified, characterized, and demonstrated to be suitable for receiving and confining injected CO2 without endangering USDWs under §146.82.

Letter ID: 0294 Comment ID: 25307 Letter Lines: 57 to 73

Comment Code: 2048 1.5.2.4 Oppose Class VI/ Support Class V experimental technology well

Comment Code: 2200 1.6.4 Other formation types

1Comment: There is less technical su pport on the ability to conduct GS in basalts, coal seams, salt caverns, and shales. As compar ed with deep saline formations and hydrocarbon reservoirs, the trapping/cont ainment mechanisms of CO2 and/or operational engineering involved in basalts, coal seams, salt caverns and shales may be significantly different and using identical regulatory language might not be appropriate. In fact, it is not known at this time whether GS (or even injection in some cases) can be done at co mmercial scale in ea ch of these types

of formations - GS efforts in these form ations are still in the experimental stage. Wells in basalts, coal seams, sa lt caverns and shale formations should be treated as experimental wells under Class V, recognizing that completing the process of research, development and dem onstration likely will require initial full scale experimental projects in addition to pilot projects.

Keeping these wells under Class V would a llow EPA and the states to gain enough experience to develop suitable permitting requirements for such wells and to tailor those requirements at both the pilot and commercial scales until the agencies are ready to regulate such wells under an appropriate class.

Individual Response: EPA clarifies that the final GS rule does not categorically preclude injection of CO2 into any formation types. Experimental research projects will continue to be regulated as Class V experimental technology wells as long as they remain of an experimental nature. EPA clarifies that existing experimental GS projects may be permitted as described in UIC Program Guidance #83: Using the Class V Experimental Technology Well Classification for Pilot Carbon Geologic Sequestration Projec ts, which provided information for permitting authorities to consider when permitting experiment al GS projects (i.e., those projects that are designed to test new, unproven technologies, per the definition of a Class V experimental technology well). EPA adds that, fo llowing finalization of the GS ru le, all GS projects that are not for experimental purposes must be re-permitted as Class VI wells and be subject to the final GS requirements. EPA expects th at, after promulgation of the fi nal rule, a limited number of experimental injection projects to test GS technology will continue, e.g., to inform the technology associated with GS into ba salts, coal seams, and salt domes.

EPA clarifies those Class V experimental projec ts subject to Guidance #83 will be those wells that test new technologies for purpos es of GS. The Agency also clar ifies that it does not consider it appropriate to permit CO2 injection wells that are testing the injectivit y or appropriateness of an individual formation (e.g., as a prelude to a commercial-scale ope ration) as Class V experimental technology wells. Such wells must be permitted as Class VI wells.

EPA is preparing an addendum to UICPG #83 that describes the use of th e Class V experimental technology well classification to clarify perm itting for Class V wells. This addendum will address shifting of Class V experi mental projects to full-scale GS projects and the future use of the Class V experimental technology well s ubclass for research a nd testing of new GS technologies. This guidance will be available on EPA’s website at http://water.epa.gov/type/groundwater /uic/wells_sequestration.cfm.

2Letter ID: 0294 Comment ID: 25308 Letter Lines: 75 to 89

Comment Code: 1240 1.1.1.3 Suggested changes/ed its to rule language

Comment Code: 2048 1.5.2.4 Oppose Class VI/ Support Class V experimental technology well

Comment Code: 2200 1.6.4 Other formation types

Comment: To implement this approach, sec tions 144.6(f), 144.80(f), 146.5(f) and the definition of sequestration in 146.81 s hould be revised. The proposed 144.15 provision that the construction, opera tion or maintenance of any nonexperimental Class V GS well is prohibited should be retaine d, but only with the understanding that this prohibition is not intended to limit the size or scale of any experimental GS operation.

"Class VI. Wells used for geologic seque stration but not in cluding those wells used for geologic sequestration that are regulated under another Class. Wells used for geologic sequestration in basalts, coal seams, salt caverns or shales are regulated under Class V as experime ntal wells until such time as the Administrator establishes separate requireme nts by rule for the specific type of formation or determines, following public notice and opportunity for comment, that wells used for geologic sequestrati on of carbon dioxide streams into the specific type of formation should be regulated under another class."

Individual Response: The text at 144.15 is retained in th e final regulation; the construction, operation or maintenance of any non-experimental Class V GS well is prohibited under the final rule. The final rule contains tailored requirements for Class VI wells to ensure that GS projects are permitted, sited, constructed, operated, and cl osed in a manner that protects USDWs from endangerment.

As described above, EPA clarifies that the final GS rule does not categorically preclude injection of CO2 into any formation types. EPA clarifies th at experimental research projects will continue to be regulated as Class V e xperimental technology wells as long as they remain of an experimental nature.

Letter ID: 0294 Comment ID: 25309 Letter Lines: 91 to 112

Comment Code: 1240 1.1.1.3 Suggested changes/ed its to rule language

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

Comment: 2. Non-interference principle

EPA notes in the preamble (page 43506), "it is...possible that multiple owners or operators will be injecting CO2 into formations that are hydraulically connected and thus the elevated pressure zones may intersect or interfere with each other." We have agreed that this possibility should be addressed through a revision to the regulations. Until more comprehensive approaches to basin-scale management are developed and based on th e proposed definition of "pressure

3front", we recommend the adoption of the following addition to §146.94:

"(e) If an owner or operator obtains evid ence that a pressure front associated with one geologic sequestration project intersects or will more likely than not intersect the pressure front or area of review associated with another project, the owner or operator obtai ning such evidence must notify the Director. The Director shall notify the ow ner or operator of the ot her geologic sequestration project. If the Director determines that the pressure front associated with one project interferes or will more likely than not interfere with the ability of another project to comply with the term s of its permit(s), the Director may require the owners or operators of the interfering or potentially interfering projects to modify operations as ne cessary to mitigate or avoid such interference. Such modifications may also include modifications mutually agreed upon by the respective owners and operator s and approved by the Director."

Individual Response: EPA agrees with the commenter that there are a variety of factors that may affect the need for emergency and remedial response at GS sites. The Agency believes that a site-specific emergency and remedial respon se plan that is info rmed by required site characterization data (per §146.82), modeling fo r AoR evaluations and reevaluations (per §146.84), and monitoring data (per §146.90) will appropriately address commenter concerns regarding the potential impacts of multiple GS projects. EPA has added a requirement at §146.94(d) that owners or operators must review their emergency and remedial response plan within one year of an AoR reevaluation requi red under 146.84 or following significant changes to the facility. Subsequently, the owners or operators must submit an amended plan or

demonstrate to the Director that no amendmen t to the plan is needed based on the AoR reevaluation or any significant changes made to the facility.

EPA also encourages owners or operators and permitting authorities to communicate planned GS activities during initial permitting activities to maximize coordination and minimize pressure interference. If a permit applicant (or the permitting authority) is aware of pending GS projects near a proposed well, the AoR delineation pe rformed pursuant to 146.84 should account for the impacts of multiple owners and operators injecting within a single basin. EPA expects that, where multiple operators are involved, the Director will not approve modeling that does not account for changes that may result from all injection operations.

EPA expects that changes within the AoR, such as the addition of new wells or projects that could potentially interfere with a GS projec t, would be identified as part of the AoR reevaluations required at §146.84(e) and would need to be addresse d in a revised emergency and remedial response plan. EPA is developing guidance on the development and implementation of project plans for GS sites, including emergency and remedial response plans.

Letter ID: 0294 Comment ID: 25310 Letter Lines: 115 to 126

Comment Code: 1220 1.1.1.1 Terminology and definitions

4Comment: 3. Transmissive fau lts or fractures

The proposed rule in §146.83(a )(2) requires a confining zone (s) that is free of transmissive faults or fractures, while §146.81 defines this term as "A fault or fracture that has sufficient permeability and vertical extent to allow fluids to

move between formations". We recomm end the following modification to the definition in §146.81(d) in or der to avoid unduly restric ting movement that is merely between formations:

"Transmissive fault or fracture means a fault or fracture that has sufficient permeability and vertical extent to allow fluids to move beyond a confining

zone."

Individual Response: EPA disagrees with the suggested edit. The final definition of transmissive fault or fracture at §146.81(d) is unchanged and reads as follows: “[A] fault or fracture that has sufficient permeability and vertic al extent to allow fl uids to move between

formations.”

The confining zone definition at §146.83(a)(2) also is unchanged and reads as follows: “Free of

transmissive faults or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide stream and displaced formation fl uids and allow injection at proposed maximum pressures and volumes without in itiating or propagating fracture s in the confining zone(s).”

Based on its evaluation of all public comments and input on the proposed rule and the NODA and Request for Comment, EPA has made many revisions to the Cla ss VI GS rule. Please see the final rule and preamble for additional information.

Letter ID: 0294 Comment ID: 25312 Letter Lines: 128 to 139

Comment Code: 1220 1.1.1.1 Terminology and definitions

Comment Code: 3100 2.1 Proposed Geologic Siting Requirements (40 CFR 146.83)

Comment: 4. Definition of confining zone

The proposed definition of confining z one in §146.81(d) requires that the

formation act as "a barrier" to flui d movement, which may be unnecessarily

strict. The definition also fails to rec ognize that it is movement through and beyond the confining zone that needs to be limited. We recommend retaining the current UIC program definition of confining zone as preferable to the proposed

definition with one revision to address th e possibility that a confining zone for a particular project may be beneath rather than above the injection zone.

"Confining zone means a geological formati on, group of formations, or part of a formation that is capable of limiting flui d movement from an injection zone."

Individual Response: EPA acknowledges the comment and di sagrees that the definition of

5confining zone is too strict. EPA clarifies that §146.83(a) requires that an y GS project must have at least one confining zone (i.e., impermeable layer) betwee n the injection zone and the lowermost USDW. EPA further believes that, in some situations, the presence of additional confining and containment zones above the pr imary (i.e., lowermost) confining zone can improve USDW protection. These layers could fu rther impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and

remediation.

Letter ID: 0294 Comment ID: 25313 Letter Lines: 141 to 168

Comment Code: 1220 1.1.1.1 Terminology and definitions

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

Comment: 5. Area of review definition and basis

We also suggest that the second senten ce of the proposed definition of GS project be transferred to th e definition of area of revi ew as recommended below. This language also reflects a change from "brine" to "formation fluids."

"Area of review means the subsurface three-dimensional ex tent of the carbon dioxide stream plume and the associated pr essure front, as well as the overlying formations, [any USDWs underlying an inje ction zone along with any intervening formations,] [FN2] and the surface ar ea above that delineated region."

[FN2] The bracketed language should be included to the extent that the regulations authorize GS above USDWs, an issue on which the signatories have expressed differing views in our respectiv e comments on the proposed rule. See

footnote 1 above.

In addition, we recommend that the s econd sentence included both in EPA’s proposed definition of area of review a nd in section 146.84(a) be dropped from

the definition and retained in sectio n 146.84(a) but modified to read as

follows:

"(a) The area of review is based on computational modeling, as well as monitoring and other operational data, that account for the physical and chemical properties of all phases of th e injected carbon dioxide stream."

The first sentence of section 146.84(a), wh ich duplicates the definition of area of review, should be deleted from s ection 146.84(a) and retained in the definition with the modifications presented above.

Individual Response: EPA disagrees that the AoR definition needs to specifically include the overlying formations and surface area above the delineated region. The intent of the AoR, a long-standing concept within the UIC Program, is to delineate the surface ar ea and all subsurface formations below it that may potentially be impacted by injecti on activity. Acceptable

6delineation models will provide predictions of CO 2 fate and transport, as well as changes in formation pressure, in three dime nsions as a function of time that can be used to delineate the subsurface storage site and the AoR.

Although EPA disagrees with the commenter's s uggested change, the Agency has carefully

considered all comments on the AoR definition at 146.84(a) and modified it to read as follows: The region surrounding the geologi c sequestration project where USDWs may be endangered by the injection activity. The area of review is delineated using computational modeling that accounts for the physical and chemical properties of all phases of the injected CO2 stream and is

based on available site characte rization, monitoring, and operational data. EPA believes that this definition is sufficiently broad and describes both the intent of the computational modeling and the relationship of the AoR to areas that are s ubject to the risks associ ated with injection.

Letter ID: 0294 Comment ID: 25314 Letter Lines: 171 to 215

Comment Code: 1240 1.1.1.3 Suggested changes/ed its to rule language

Comment Code: 3420 2.2.2.1 Scope of the inventory pr ocess (e.g., reliance on publicly available information, depth of wells)

Comment: 6. Area of review and corre ctive action requirements

In proposed §144.55(a) the rule would require Class I, II (other than existing), III or VI permit applicants to identify the location "of all known wells within the injection well’s area of review which penetrate the injection zone" or, in the case of Class II wells ope rating over the fracture pre ssure of the injection formation, "all known wells within the area of review penetrating formations affected by the increase in pressure."

Since injection in deep saline formations will result in an area of elevated pressure (above the original reservoir pr essure) that will be larger than the CO2 plume and could conceivably affect overlying or underlying formations, we have agreed that the requirement for Cl ass II wells operating above the fracture pressure should also apply to Class VI wells. This would help prevent the unwanted migration of reservoir fluids from the injection zone as a result of the pressure increase. We therefore reco mmend that §144.55(a) be revised to read as follows, with revisions shown in blue:

"(a) Coverage. Applicants for Class I, II, (other than existing), or III, injection well permits shall identify the location of a ll known wells within the injection well's area of review which pene trate the injection zone. In the case of Class II wells that operate over the fracture pressure of the injection formation, applicants shall also identify the location of all known wells within the area of review penetrating formations affected by the increase in pressure. For such wells which are improperly sealed, completed, or abandoned, the applicant shall also submit a plan consisti ng of such steps or modifications as

7are necessary to prevent movement of fl uid into underground sources of drinking water (‘‘corrective action’’). Where the pl an is adequate, the Director shall incorporate it into the permit as a conditi on. Where the Director’s review of an application indicates that the permittee’ s plan is inadequate (based on the factors in §146.07), the Director shall re quire the applicant to revise the plan, prescribe a plan for corrective ac tion as a condition of the permit under paragraph (b) of this section, or de ny the application. The Director may disregard the provisions of §146.06 (Area of Review) and §1 46.07 (Corrective Action) when reviewing an application to permit an existing Class II well. Applicants for permits for Class VI wells [or for wells in other classes that are used for geologic sequestration a nd do not meet the criteria for §144.6(b) (4)][FN3] shall identify the location of a ll known wells within th e area of review penetrating the injection zone and all known wells within the area of review which penetrate formations affected by the pressure front and shall perform corrective action as sp ecified in §146.84."

3/ The undersigned, except NRDC which does not support the Group’s proposed bright line definition and language for §144.6(b)(4) (see MSG letter of Dec. 23, 2008), believe that this clause in brackets should be included.

Individual Response: The final rule leaves §144.55 unchanged from the existing UIC requirements; i.e., Class VI wells are not addressed in this pr ovision. Based on its evaluation of all public comments and input on the proposed rule and NODA a nd Request for Comment, EPA has made many revisions to the GS Rule. See th e final rule and preamble for further discussion on EPA's final approach.

Letter ID: 0294 Comment ID: 25315 Letter Lines: 217 to 240

Comment Code: 1240 1.1.1.3 Suggested changes/ed its to rule language

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

Comment: 7. Well construction

EPA’s proposed §146.86(b)(3) would require th e long string casing to be cemented by circulating cement to surface in one or mo re stages. Yet that may be hard to accomplish in some cases, such as very deep wells. There are also potential disadvantages of this approach with rega rd to the weight of the cement column and its relation to well integrity. Sealing this annulus also eliminates an approach for monitoring the integrity of the cement in that critical interval through the primary confini ng interval and above. We recommend that EPA not make this a mandatory requirement. The requirement should also recognize that there may be other technologies that c ould be as effective as cement and centralizers, which may not be feasible in some app lications; furthermore, current research and development efforts are likely to yield additional technologies the use of which should not be foreclosed. Accordingly, we recommend the following language for §146.86(b)(3):

8"(3) At least one long stri ng casing, using a sufficient number of centralizers,

which at a minimum: must be sealed from within the injection z one upward through the overlying confining zone, and must provide adequate is olation of the injection zone and other in tervals as necessary for pr otection of USDWs using cement and/or other isolation techniques. The Director may approve the use of packers or alternative isolation technique s, provided these are demonstrated to be equivalent to cement or more effectiv e to provide adequate isolation and to protect USDWs."

Individual Response: EPA does not believe that the cem enting requirements at §146.86 would prevent monitoring, operation and remediation of Class VI wells. Cementing of deep wells has been performed successfully in the past by owners or operators of Class I hazardous and Class I municipal waste disposal wells. Some of these wells, which must meet the same cementing and casing requirements as Class VI wells, are up to 12,000 feet deep and have been successfully cemented in a manner that maintains integrity an d allows for all required well testing, operation, and remediation (EPA, 2001). See the discussion of Class VI well construction requirements in the preamble to the final GS rule for additi onal information. Additionally, EPA is developing guidance on the construction of Class VI wells . This guidance will be available on EPA’s website at http://water.epa.gov/type/gr oundwater/uic/wells_sequestration.cfm.

Section 146.86(b)(3) requires that the long-string casi ng extend to the inj ection zone and be cemented by circulating cement to the surface in one or more stages. It does not, however, specify how cementing should be accomplished, and gi ves flexibility to the owner or operator to propose alternate methods to provide a sufficient amount of cement to meet the standard that USDWs are protected from endangerment, subject to the approval of the Director. EPA notes that there are many potential ways to meet the requirement in d eep wells, such as the use of staged cementing.

EPA also received comments from stakeholders representing states, a water association, and industry supporting this provisi on, saying that it provides, at a reasonable cost, corrosion protection of the casing; prevents undesirable migration of fluids be hind the casing; provides support to the casing; and provides multiple barriers against endangerment of USDWs.

EPA stresses that protection of USDWs is the primary mission and mandate of the UIC program and the purpose of all requirements for inject ion wells. Any injection activity must be demonstrated to not endanger USDWs, regardle ss of their depth, and if such non-endangerment cannot be shown, then the activity will not be allowed under UIC requirements or the SDWA.

EPA recognizes concerns regardi ng construction of Class VI wells where the lowermost USDW is very deep. To further address comments on d eep injection wells, the final GS rule at §146.95 includes requirements for owners or operators that seek a waiver of the injection depth requirements. Owners or operators of wells opera ting under injection depth waivers must comply with additional construction require ments to ensure that wells used to inject above or between USDWs are protective. See the discussion of the wa iver approach in the preamble to the final GS

rule for additional information.

9Letter ID: 0294 Comment ID: 25316 Letter Lines: 242 to 313

Comment Code: 1240 1.1.1.3 Suggested changes/ed its to rule language

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

Comment: 8. Reevaluation of the Area of Review a nd Revision and Maintenance of Plans

Although the proposed §146.84(f) would requir e "reevaluation" of the aor at a "minimum" fixed frequency of ten year s or "when operational and monitoring conditions warrant," the specific language of §146.84 r uns the risk that revisions will not be made on a timely basis. We recommend imposing a continual obligation on operators to assess whether the aor itself, the aor and corrective action plan and all other plans required by the regulations should be revised, requiring an annual certification stating that the owner or operator has reviewed the circumstances (including ope rating and monitoring data) during the preceding year to determine whether these circumstances warrant ed a revision of the aor and any plans, and requiring that revisions be done wh en required by the director as well as when the operator de termines that conditions warrant. To accomplish this, it is useful to break down the concept of "reevaluation" into

two ideas - "assessment" of the need to revise the aor and all plans and the actual process of "revision." we believe that these suggestions will result in increased accuracy and reliability in th e site performance data while avoiding work that is not warranted by the site da ta and site performance. Moreover, a continuous obligation to assess whether revi sions are needed, wh en coupled with an annual certification requirement (see proposed §146.91(d) below) will create a clear accountability trail for both operator and director in case of disputes.

Given this annual certifica tion process, we believe it is unnecessary to require a reevaluation on a fixed basis every 10 years in every case.

An annual certification requirement can also be used to enhance the ability of both Director and operators to keep tr ack of which plans require updating and whether or not plans that ought to be update d have in fact been revised. Such a shared understanding is e ssential if there is to be the "ongoing dialogue" between regulators and operators that EPA anticipates. We considered the

inclusion of an annual re port as described in the preamble at 73 Fed. Reg. 43518, but concluded that the benefits of that particular report would be outweighed by the burden. The annual certif ication we are recommending would be uch simpler. We recommend:

That §146.84(f) be revised to read as follows:

"(f) (1) Notwithstanding the requirement in paragraph (2)(i) of this subsection to perform a reevaluation of the area of review at the frequency set forth in

the area of review and corre ctive action plan, the owner or operator must also conduct the following whenever warranted by material change in the monitoring

10and operational data or in the evalua tion of the monitoring and operational data by the owner or operator:

"(i) reevaluate the area of review by pe rforming all of the actions specified in paragraphs (c)(1) through (3) of this section to delinea te the area of review and identify all wells th at require corrective action;

"(ii) perform corrective action on wells requiring corrective action in the reevaluated area of review in the same manner specified in paragraph (d) of this section; and

"(iii) submit an amended area of revi ew and corrective action plan or demonstrate to the Director through mon itoring data and modeling results that no change to the area of review and corrective action plan is needed.

"(2) Except as provided in paragraph (3 ) of this subsecti on, the owner or operator shall also conduct a reevalua tion by performing all of the actions specified in subparagraphs (1)(i) through (iii) of this subsection:

"(i) Within the time periods specified in the area of revi ew and corrective action plan for conducting such a reev aluation of the area of review; or

"(ii) If an area of review evaluation or reevaluation has not been performed pursuant to §146.84(c) and (d) for the ge ologic sequestration project during the preceding ten (10) years, then within six months after the passage of that 10-year period.

"(3) The Director shall waive the requ irement for a reevaluation pursuant to either §146.84(f)(2)(i) or (i i) if the owner or operato r demonstrates to the Director through monitoring and operational data and modeling results, such as those reviewed annually pursuant to sec tion 146.95, that such a reevaluation is not warranted by mate rial change."

Individual Response: EPA disagrees with the proposed cha nges and believes that periodic AoR reevaluation at a set frequency of at least ever y 5 years is necessary to ensure protection of USDWs from endangerment and address the uncer tainties inherent 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.

EPA agrees that site-specific information will influence the need for AoR reevaluations, and

clarifies that if site mon itoring data agrees with the existing AoR delineation, a model recalibration may not be necessary, and the AoR reevaluation may consist of a demonstration

11that the current AoR delineation is ad equate based on site monitoring data.

Letter ID: 0294 Comment ID: 25317 Letter Lines: 315 to 340

Comment Code: 1240 1.1.1.3 Suggested changes/ed its to rule language

Comment Code: 3500 2.2.3 Area of Review Reevaluation (seeking comment)

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

Comment: In addition, we recommend the following new §146.95:

"146.95 Plan Maintenance and Update

"(a) Owners or operators must submit an annual statement, signed by an appropriate company official, conf irming that the company has:

"(i) reviewed the monitoring and operati onal data that are relevant to a

decision on whether to reevaluate the ar ea of review and the monitoring and operational data that are re levant to a decision on wh ether to update a plan identified in §146.82(p) or (u) through (x ) or the quality a ssurance plan for all testing and monitori ng requirements; and

"(ii) determined whether any updates were warranted by material change in the monitoring and operational data or in the evaluation of the monitoring and operational data by the owner or operator.

"(b) Owners or operators must submit eith er the updated plan or a summary of the modifications for each plan for which an update was determined to be warranted pursuant to subs ection (a) of this section. The Director may require submission of copies of any updated pl ans and/or additional information regarding whether or not updates of a ny particular plans are warranted.

"(c) The Director may require the revisi on of any required plan whenever the

Director determines that such a revisi on is necessary to comply with the requirements of this subchapter."

Individual Response: EPA agrees with the commenter that review of the GS project plans is appropriate. The final rule includ es provisions that owners or operators review and update the AoR and corrective action plan, th e testing and monitoring plan, a nd the emergency and remedial response plan throughout the life of the projec t (these provisions are added at §146.84(c), §146.90(j), and §146.94(d)). Owners or operators must review each plan and identify necessary amendments to the plan or demonstrate to the Director that no amendment is needed. These reviews must be performed within one year of an AoR reevaluation, following any significant changes to the facility (e.g., the addition of mon itoring or injection wells) , or when required by

the Director.

12Letter ID: 0294 Comment ID: 25318 Letter Lines: 344 to 349

Comment Code: 1240 1.1.1.3 Suggested changes/ed its to rule language

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

Comment: With respect to the emergency and remedial response section, we propose two changes - change §146.94(b)(4) to read:

"Implement the emergency and remedial re sponse plan approved by the Director, and keep the Director appri zed of the implementation."

Individual Response: The final rule retains the langua ge in §146.94(b)(4) as proposed. EPA agrees that the Director shoul d be kept apprised of progre ss on the implementation of the emergency and remedial response plan but expects that the plan itself will include provisions on

communications with the Direct or. The requirements for an emergency and remedial response plan at §146.94(a) are designed to ensure that owners or opera tors, as part of their permit application, comprehensively plan what actions w ould be necessary in the unlikely event of an emergency. The plan will ensure that operators know what entities a nd individuals must be notified and what actions must be taken to expeditiously mitigate any emergency situations. The rule sets forth triggers for notification to the Director that initiates consultation on appropriate responses. EPA expects that the owner or opera tor and Director would discuss the necessary response action and maintain a dialogue and communication throughout the conclusion of any needed actions. EPA is developing guidance on the development and implementation of emergency and remedial response plans for GS sites.

Letter ID: 0294 Comment ID: 25319 Letter Lines: 350 to 362

Comment Code: 1240 1.1.1.3 Suggested changes/ed its to rule language

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

Comment: and §146.94(d) to read:

"The owner or operator must notify the Di rector and obtain his approval prior to conducting any well workover or other remedi ation measures not listed in the emergency and remedial response plan."

It should be noted that the language chosen here for §146.94(d) relates specifically to remediation measures a nd not to emergency responses, which should not be delayed to seek approval when immediate response action is necessary. Every effort should be taken to ensure that emergency responses are comprehensively addressed in the pla n, including appropriate notification provisions and timeframes, but emergency responses should not be delayed when awaiting approvals could impair the effectiveness of the response.

1314 Individual Response: Since proposal, EPA has modified the final regulatory language at §146.94(d) to clarify what constitutes a workover to address a well failure (which invokes remedial actions) and what constitutes a mainte nance-type workover. For maintenance-type workovers (i.e., those that are scheduled in adva nce), the owner or operato r must notify and gain approval from the Director prior to beginning the workover. In th e final GS regulation, EPA has moved this requirement to the reporting requi rements at §146.91(d) to clarify its intent.

Regarding concerns that notifica tion could delay responses, EPA clarifies that the GS rule (at §146.94(b)) describes procedures owners or opera tors must take in emergency situations. Specifically, upon determining that there is a problem with the we ll that may endanger a USDW, the owner or operator must firs t cease injection, then take all steps reasonably necessary to identify and characterize any release, notif y the Director, and implement the approved emergency and remedial response plan, which ma y include a well workover. EPA believes that ceasing injection (which the ow ner or operator would do immediately and before notifying the Director) is the action necessary to prevent or mitigate endang erment of USDWs, as required

under the SDWA.