2.1 Responses to Public Comments on Geologic Siting Requirements

This file contains responses to public comments on geologic siting for Class VI wells
(comment codes 3100 to 3150). This section includes comments on the need for

injection and confining zones and required permit information.

The table below presents all of the EPA

‐ assigned comment codes that are included in

this section of the comment and response summary. Use the bookmarks in the PDF to

move among the comment codes.

Topics included in this summary and associated comment codes

Topic Code

2.1 Proposed Geologic Siting Requirements (40 CFR 146.83) 3100

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

2.1.2 Need to identify additional confining and containment zones 3120

2.1.3 Comments that operators should submit more (or different) geologic data than
proposed 3130

2.1.4 Comments that the proposed geologic data requirements are too stringent 3140

2.1.5 Comments on required permit information (40 CFR 146.82) 3150

Every comment on these topic areas and the associated response is included in this

summary; there is some repetition where multiple commenters made the same

comment.

Responses to letters from individual commenters or organizations are also available in

the rulemaking docket.Comment Code: 3100 2.1 Proposed Geologic Siting Requirements (40 CFR 146.83)



### Individual Comments

Commenter Name: Leslie Savage Letter ID: 0122 Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24764 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: (f) Maps and stratigraphic cross sections indicating the general vertical and lateral limits of all USDWs, water wells and springs within the area of review, their positions relative to the injection zone(s) and the direction of water movement, where known;

{Consistency with definition and use of term in other areas of the rules.}

Response: EPA believes that the plural for injection zone(s) should be retained in the Final Rule in recognition of the fact that characterizing more than one injection zone may be necessary at some GS sites. EPA believes that in some geologic settings, the presence and identification of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These formations could further impede vertical fluid movement, allow for pressure dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection of USDWs from endangerment. EPA believes that providing the Director this additional discretion is an important element of assuring that GS activities will not endanger USDWs.

Please see the final rule and the discussion of geologic site characterization in the preamble for

additional information.

Commenter Name: Leslie Savage Letter ID: 0122 Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24767 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: (1) An injection zone of sufficient areal extent, thickness, porosity, and permeability to receive the total anticipated volume of the carbon dioxide

stream;

{Redundant - simply repeats the definition of "injection zone." Either take this language out of the definition or take it out of here.}

Response: EPA acknowledges the comment. For consistency, §146.83(a)(1) includes the definition of injection zone. EPA clarifies that §146.83 identifies the specific criteria that owners or operators

must meet to demonstrate that a GS site is suitable for GS.

Commenter Name: Dwight Lockwood, PE, QEP Letter ID: 0141 Commenter Organization: Global Energy, Inc. Comment ID: 23090

Comment: 1. The siting criteria, including defining of the appropriate Area of Review, seismic evaluation, extensive modeling and characterization are sufficientlyrigorous that it is reasonable to anticipate minimal risks of leakage will exist long term. This minimal risk therefore argues in favor of a simple and pragmatic program.

Response: EPA acknowledges the comment and believes that a detailed geological site characterization (required under §146.82) is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for the unique nature of injecting large volumes of CO2 into a variety of geological formations for long-term storage.

Commenter Name: Brianne Metzger Letter ID: 0151 Commenter Organization: Spectra Energy Corp Comment ID: 21844 Other EPA Comment Codes and Descriptions: 2100 1.6 Target Geologic Formations for GS

Comment: I. Large-Scale GS Operations Must Not Impact The Storage Of Hydrocarbon Natural

Gases.

One concern with GS is the potential implications for and impact on large-scale natural gas storage operations. Under SDWA, hydrocarbon natural gas storage is exempt from current UIC regulations governing injection activities. Spectra is concerned about the potential implications and impacts on underground gas storage from the Proposed Rule. Natural gas storage is regulated by State and interstate entities, such as Interstate Oil and Gas Compact Commission (IOGCC), that oversee the siting, permitting, design, construction, and operations of wells. Within the U.S., natural gas storage is generally located in two major geologic formations, porous rock reservoirs and salt caverns. Generally, the types of storage fields that will potentially be impacted by the Proposed Rule are porous rock reservoirs. Because many of the areas and geologic formations considered for GS will be in the same basins and may occur within or in close proximity to the same geologic strata, there is the potential for gas storage fields to be adversely impacted by GS. In order to avoid any unintended impacts to natural gas storage operations, there are several issues that need

to be considered.

First, gas storage wells are regulated by State oil and gas regulatory agencies. Individual States have a critical role in protecting and regulating the competing economic interests involved in utilizing the subsurface, not only for natural gas storage but also oil and gas production or other subsurface activities. Many State oil and gas regulations specify well siting or construction requirements for any wells that are drilled within a gas storage area or penetrate the storage horizon. Spectra suggests that appropriate regulatory agencies in individual States be active participants with the EPA in the GS permitting process, to ensure appropriate State knowledge of local geology is considered in a technical evaluation of the suitability of potential GS zones, and for the balanced protection of gas storage and other economic interests. We believe the EPA should affirm the authority of the States to require the GS operator to comply with all well construction and monitoring requirements to protect the integrity of gas storage reservoirs.Second, as part of the site selection and GS permit application process, all natural gas storage projects within the AoR should be identified on the AoR map and assessments performed to determine the potential impact from CO2 or fluid migration to the gas reservoir. Such an assessment should also include analysis of potential leak paths through faulting, fracturing, or other migration paths from injected CO2 in formations in close proximity to gas storage reservoirs.

Third, we would recommend that where GS and gas storage reservoirs are in close proximity that additional monitoring be required. We are also concerned about the potential impact of hydraulic fracturing of GS wells on natural gas storage. We believe that an analysis should be conducted based on the proximity (laterally and vertically) of the GS zone to existing gas storage reservoirs and the potential for communication with a gas storage reservoir. For this reason, we believe it is important that all records relating to well logs, cementing records, and casing strings and cementing operations of any GS wells drilled within the reservoir or protective perimeter boundaries of a gas storage field must be available and accessible to the public. Conversely, and for the same reasons, we believe information regarding the proximity of gas storage reservoirs to GS wells is equally important and should be readily available to the public to ensure the integrity of the CO2 injection operation.

Response: EPA believes that the extensive requirements for geologic site characterization (at §146.82), AoR evaluation (§146.84), and testing of the well during drilling (§146.87) are appropriate to ensure that permitting authorities have the necessary information to evaluate whether a specific site will allow safe injection of CO2. EPA adds that submittal and review of monitoring data (as required at §146.90) and the AoR reevaluation process (§146.84(e)) will provide an opportunity for an ongoing review of the site and a dialogue between the Director and the owner or operator to ensure that the project is being operated in a manner that protects USDWs from endangerment.

Under §146.82(a)(2) owners or operators must identify all injection and production wells, which will most likely include evidence of and information about the location of natural gas storage sites. The Director must evaluate this information when determining whether to issue a permit. While the GS rule does not explicitly require the owner or operator to identify natural gas storage sites within the AoR, the Director may require additional site-characterization or data collection at his or her discretion. For example, the Director may require additional monitoring under §146.90(i) to ensure that GS does not interfere with existing natural gas storage projects. The site characterization requirements at §146.82 will also help determine the existence and locations of any faults and

fractures.

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations to owners or operators regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. Additionally, EPA expects that this guidance will support permitting authorities as they evaluate initial permits for Class VI injection wells with technical assistance as needed. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.EPA expects permitting authorities to retain an administrative record for the project, which at the discretion of the permitting authority might be available online and at the authority's office. EPA encourages (but does not require) operators and permitting agencies to begin involving the public by providing information as early in the GS project development process as possible.

In response to the comment that state gas agencies should be involved in permitting decisions, EPA clarifies that the decision to issue a permit rests with the agency implementing the Class VI Program, as identified in the state's approved primacy application. If a state or tribe chooses not to seek primacy for Class VI program implementation, EPA will directly implement the program for the state or tribe. However, the final rule includes a requirement that state and local oil and gas regulatory agencies and state agencies regulating mineral exploration and recovery must be notified when a draft Class VI permit is available for public comment, at §124.10(c)(1)(xi).

Commenter Name: Bonnie Lovelace Letter ID: 0152 Commenter Organization: Montana Department of Environmental Quality (MDEQ) Comment ID:

22126 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: 146.83 (a) (1): MDEQ suggests adding the same language to (1) as is found in (2): "without initiating or propagating fractures in the injection zone.

Response: EPA did not make the suggested edit to the injection zone requirement but retained similar language in the restriction on injection pressure at §146.88(a).

Commenter Name: Sandi Tabor Letter ID: 0162 Commenter Organization: Lignite Energy Council (LEC) Comment ID: 21296 Other EPA Comment Codes and Descriptions: 5400 2.9 Proposed Financial Responsibility and Long-Term Care Requirements

Comment: Third, EPA must develop financial assurance and risk management regulations that clarify the long-term obligations and risk associated with a GS project. One way to meet the EPA's dual goal of protecting the environment while facilitating the development of CCS is to focus regulations on proper site characterization. Proper site selection and characterization will help minimize potential future risks and lessen the need for default provisions that apply to all sites.

Response: EPA agrees that proper site characterization is important to minimizing risks associated with GS, but also believes that assuring financial responsibility for corrective action on Class VI wells in the AoR, injection well plugging, PISC and site closure, and emergency and remedial response at GS sites is an important component of ensuring that USDWs are protected. The goal of the financial responsibility requirements at §146.85 are to ensure that financial resources are available to prevent endangerment of USDWs from improper plugging, remediation, and management of wells in the event that the owner or operator experiences financial difficulties. See the final rule and preamble for further discussion of EPA's final approach to financial responsibility.

EPA expects that the cost of financial responsibility will depend heavily on the estimated cost of covered activities as well as certain site-specific factors and their project phases. Under the final rule, the cost estimate must be performed for each phase of the GS project separately and must be based on the costs to the owner or operator of hiring a third party to perform the required activities.Additionally, during the active life of the GS project, the owner or operator must adjust the cost estimate for inflation within 60 days prior to the anniversary date of the establishment of the financial instrument(s) to demonstrate financial responsibility. In order to assist owners or operators and financial institutions in achieving accurate cost estimates, EPA plans to include a guidance that includes discussion of how best to estimate costs, including how to adjust cost estimates for inflation, in its guidance on meeting financial responsibility requirements for GS wells.

Commenter Name: James Devine Letter ID: 0166 Commenter Organization: United States Geological Survey (USGS) Comment ID: 21350 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Section 146.87 (e), Logging, Sampling, and Testing Prior to Injection Well Operation, FR page 43538

It is stated that, "Upon completion, but prior to operation, the owner or operator must conduct the following tests to verify hydrogeologic characteristics of the injection zone:

(1) A pump test; or

(2) Injectivity tests."

A`pump' test can be either injecting or withdrawing fluid. The following suggested rewrite reduces redundancy: "Upon completion, but prior to operation, the owner or operator must conduct pumping tests to verify the hydraulic properties of the injection zone. These tests can take the form of :

(1) withdrawal tests; or

(2) injectivity tests."

Response: EPA retained the requirements in the final rule as proposed because existing UIC program requirements use similar language and the tests and their purposes are understood by the regulated community. Additionally, the Agency believes that verification of hydrogeologic characterization will generate the same information as the suggested alternative language.

Commenter Name: Michael Mudd Letter ID: 0167 Commenter Organization: FutureGen Alliance (FGIA) Comment ID: 22467

Comment: A-1. Proposed Geologic Siting Requirements III-A-1. This section mentions several types of geologic/geochemical/geomechanical information needed to assess a site’s viability. EPA should specify the information required to support this analysis.

Response: EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations to owners or operators regarding information to characterize the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA isalso developing a number of technical guidances and implementation materials to assist owners or operators and Directors in the permitting process. These guidances will provide recommendations to perform many of the activities necessary for applying for a permit, including developing all required plans and conducting site characterizations that meet the requirements of §146.82. The draft guidance material can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Kyle Isakower Letter ID: 0170 Commenter Organization: American Petroleum Institute Comment ID: 24150 Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions

Comment: Rule Provision: 146.81(d) [Definition - Transmissive fault or fracture]

API Comments: Transmissive fault or fracture means a fault or fracture that has sufficient permeability and vertical extent to allow fluids to move between

formations BEYOND THE CONFINING ZONE.

Rationale: The term "between formations" is inaccurate since there can be multiple formations within a injection zone. The critical factor for transmissivity is movement of injected or displaced fluids beyond the confining

zone.

Response: EPA acknowledges the comment but is retaining the requirement in the final rule as originally proposed under §146.81(d). EPA has retained the definition in the final rule, which is the same as the existing definition at §148.2, to address transmissive faults and fractures that extend beyond the confining zone.

Commenter Name: Kyle Isakower Letter ID: 0170 Commenter Organization: American Petroleum Institute Comment ID: 24152 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(c)

API Comments: (c) A MAP DELINEATING the area of review based on UPON modeling, using ALL AVAILABLE data INCLUDING DATA obtained during logging and testing of the well and the formation as required by paragraphs (l), (r), and (s) of this section ANY WELLS IN THE AREA OF REVIEW

Rationale: This appears to be related to a condition where a well is already drilled. This does not align with requesting information to receive a permit.

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).The requirement to provide the final area of review based on modeling and data obtained during logging and testing is in the final GS rule at §146.82(c)(1). Please see the final rule and the discussion of geologic site characterization in the preamble for additional information.

Commenter Name: Kyle Isakower Letter ID: 0170 Commenter Organization: American Petroleum Institute Comment ID: 24154 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(e)

API Comments: (e) A tabulation RECORD of all wells ARTIFICIAL PENETRATIONS within the area of review which penetrate THAT REACH the injection or confining zone(s). Such data AS AVAILABLE IN THE PUBLIC RECORD must include a description of each well’s PENETRATION’S type, construction, date drilled, location, depth, record of plugging and/ or completion, and any additional information the Director may require;

Rationale: Artificial penetrations is a more inclusive term.

Rule Provision: 146.82(f)

API Comments: (f) Maps and stratigraphic cross sections indicating the general vertical and lateral limits of all USDWs, water wells and springs within the area of review, their positions relative to the injection zone(s) and the direction of water movement, where known; POTENTIOMETRIC (WATER LEVEL) SURFACE MAP(S) OF EXISTING AQUIFERS BEING UTILIZED AS PRIVATE OR PUBLIC WATER

SUPPLIES AND THE DIRECTION OF GROUNDWATER FLOW IN THESE AQUIFERS WITHIN THE

AREA OF

REVIEW. AT LEAST TWO GEOLOGIC CROSS SECTIONS SHOWING THE THICKNESS

AND GENERAL

VERTICAL AND LATERAL LIMITS OF ALL USDWS WITHIN THE AREA OF REVIEW.

No rationale provided

Rule Provision: 146.82(g)

API Comments: (g) Baseline geochemical data on subsurface formations, including all USDWs in the area of review COMPILATION OF AVAILABLE GEOCHEMICAL

DATA ON THE PROPOSED INJECTION ZONE AND NEAREST POROUS AND PERMEABLE

FORMATION

ABOVE THE CONFINING ZONE.

Rationale: Limits the data to be submitted to available information and to the injection zone and the zone immediately above the confining zone which are the zones most likely to be monitored for potential CO2 leakage.

Response: As described above, EPA disagrees that the information that is submitted to support a Class VI permit application should be limited to known/available data.EPA believes that a thorough understanding of the hydrogeologic conditions of all USDWs in the AoR is necessary, and disagrees with the suggested edits because the GS rule, as written, affords flexibility to owners or operators and Directors to tailor the site characterization process to the unique features of the site. EPA encourages owners or operators and Directors to collaborate and consult during site characterization to discuss information needs and ensure that all appropriate data to assess the suitability of the site are collected. The Director has the authority to request additional hydrogeologic data or other data on USDWs as well.

The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR, is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate and transport model development (e.g., by providing appropriate input parameters), and provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. The baseline geochemical information will allow the owner or operator and permitting authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may

indicate fluid movement.

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion to require geochemical analysis of additional subsurface zones if, in the Director's opinion, they are necessary for the protection of USDWs from endangerment.

Commenter Name: James Taft Letter ID: 0172 Commenter Organization: Association of State Drinking Water Administrators (ASDWA) Comment ID:

23450 Other EPA Comment Codes and Descriptions: 1510 1.2.2.3 Need for additional study

Comment: Specific Comments

Geologic Siting Requirements and Area of Review (AOR)

Additional Research and Data Needed:

More research and data are needed, than are typically available now, to make scientific determinations as well as implement proven methods to ensure the integrity of the proposed geologic sites, without displacement of existing USDW. Such research and data will be particularly important with regard to characterizing the thickness of the confining zone and permeability.

Response: EPA agrees that continued research will be integral to development of GS technology, but disagrees that the Agency is unable to ensure the integrity of the proposed geologic sites.

EPA agrees that continued research in all GS associated fields will be integral to development of GS technology. EPA is aware of research by other federal agencies, industry, international parties, and academia related to GS, including projects that address many of the topics suggested by commenters. EPA published a Notice of Data Availability (NODA) and Request for Comment on August 31, 2009 (74 FR 44802), in which the Agency described the results of research at three DOE partnership sites (in Escatawpa, Mississippi; the Aneth Field in Paradox Basin, southeast Utah; and the PumpCanyon Site, New Mexico). In the NODA and Request for Comment, EPA also described two studies by the Lawrence Berkeley National Laboratory on the potential effects of CO2 injection on ground water and surrounding formations to determine the potential for impacts on USDWs and human health in the event that a GS project is not properly sited, operated, or managed.

To protect USDWs from endangerment and meet the potentially fast pace of GS deployment, EPA is using an adaptive approach to regulating CO2 injection for GS. The Agency plans to collect and review data every six years on GS projects to determine whether the appropriate amount and types of information and documentation are being collected, and to determine if modifications to the requirements are necessary. An adaptive approach will allow regulatory development to proceed in time to meet the current and future demands for Class VI permits, while EPA continues to gather data from pilot projects and other research as it becomes available.

Commenter Name: James Rower Letter ID: 0173 Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23479

Comment: 5. Siting of CO2 GS Wells

As a general matter, USWAG believes that EPA must consider the potential impact of CO2 GS projects on other pre-existing subsurface activities (e.g., natural gas storage operations). In particular, the Final Rule should ensure that final Class VI permits not inappropriately interfere with these other pre-existing subsurface interests and operations.

With respect to the types of formations into which CO2 may be injected for GS under the UIC Program, it is counterproductive at this stage in the development of the CO2 GS regulatory regime to categorically preclude any potentially feasible injection formations as possible long-term storage sites. EPA recognizes that the commercial deployment of CO2 GS activities will result in the new production of large volumes of CO2 for which Owners or Operators will have to locate new and environmentally protective injection zones. In fact, the GAO Report anticipates a need to permit thousands, if not tens of thousands, of additional UIC wells to accommodate the increased volumes of CO2 expected to be captured in a large-scale CCS program. GAO Report at 40. Therefore, it makes sound policy sense for EPA to encourage the identification and utilization of as many injection zones as possible, with the prerequisite that injection at any site be protective of USDWs.

Response: EPA believes that the extensive requirements for geologic site characterization (at §146.82), AoR evaluation (§146.84), and testing of the well during drilling (§146.87) are appropriate to ensure that permitting authorities have the necessary information to evaluate whether a specific site will allow safe injection of CO2. EPA adds that submittal and review of monitoring data (as required at §146.90) and the AoR reevaluation process (§146.84(e)) will provide an opportunity for an ongoing review of the site and a dialogue between the Director and the owner or operator to ensure that the project is being operated in a manner that protects USDWs from endangerment. EPA believes that any natural gas storage operations would be found in site characterization as would any

faults or fractures.

The final rule does not preclude injection into any formations or types of injection sites provided that the wells meet the final GS rule requirements. The purpose of the GS regulation is to ensure thatinjection of CO2 for GS is conducted in a manner that is protective of USDWs. This includes appropriate site characterization and identification of geologic formations that are amenable to injection of potentially large volumes of CO2 for long-term storage. The regulation provides flexibility to owners or operators to select appropriate sites and target formations (under §146.82), well construction specifics (under §146.86), and injection procedures provided the owner or operator can demonstrate that the injection and storage will not endanger USDWs and that minimum requirements for the site are met.

Commenter Name: Pamela Faggert Letter ID: 0175 Commenter Organization: Dominion Comment ID: 23518

Comment: 2. Siting

Dominion agrees that proper site selection is critical to a successful GS project. Appropriate siting can minimize or eliminate risk of potential threats to USDW that GS may pose. However, several of the contemplated requirements and restrictions in the Dominion Comments on Proposed Regulation of CO2 Injection Wells proposal are unnecessary for the protection of USDW and could discourage the development of CCS.

Response: EPA believes that a detailed geological site characterization (required under §146.82) is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for theunique nature of injecting large volumes of CO2 into a variety of geological formations for longterm storage.

EPA disagrees that any of these protective requirements are unnecessary, and clarifies that waiving any of the requirements would not be acceptable. The GS regulation allows flexibility where appropriate. Certain requirements (e.g., the need to characterize additional confining layers) are at the Director's discretion (§146.83(b)).

Commenter Name: Quinlan J. Shea Letter ID: 0177 Commenter Organization: Edison Electric Institute Comment ID: 23551 Other EPA Comment Codes and Descriptions: 1310 1.1.2.4 Comments on other "out of scope" issues, e.g., pore space ownership; 2100 1.6 Target Geologic Formations for GS; 3120 2.1.2 Need to identify additional confining and containment zones (seeking comment)

Comment: EEI agrees that proper site selection is critical to a successful GS project and notes that it serves to minimize, if not eliminate, any potential threats to drinking water sources that CO2 injection and storage may pose. However, several of the proposed requirements are unnecessary from the perspective of protecting drinking water sources and would only serve to hamper GS projects from going forward, including limitations on receiving formations, potential alteration to the current definition of an underground source of drinking water (USDW), and the proposed grant of discretion to the UIC program director to require permit applicants to identify secondary containment/confining zones.Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

EPA believes that the Class VI requirements, including the level of site characterization required under §§146.82 and 146.83, appropriately address the unique challenges posed by large-scale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic formations.

EPA disagrees with the commenter that the GS rule requirements are unnecessary to protect USDWs. The GS final rule builds upon longstanding programmatic requirements for underground injection that have been in place since the 1980s and that are used to manage over 800,000 injection wells nationwide. These programmatic requirements are designed to prevent fluid movement into USDWs by addressing the potential pathways through which injected fluids can migrate into

USDWs. EPA coordinated with Federal and non- Federal entities on GS and CCS to determine how best to tailor existing injection requirements to CO2 for GS.

Additionally, EPA clarifies that the GS rule does not categorically preclude injection of CO2 into any non-USDW formation types. The purpose of the GS rule is to ensure protection of USDWs from endangerment, and the rule requires that owners or operators demonstrate that wells are sited in suitable systems with geologic formations to receive and confine injected CO2, required at §146.83 of the GS rule. The Class VI siting, well construction and operation, monitoring and testing, and post-injection site care and site closure requirements are designed to ensure that injected CO2 remains within the target formation. If an owner or operator can demonstrate to the Director's satisfaction that GS in coal seams, basalts, salt domes, or shales can be accomplished in a manner that protects USDWs and meets all of the requirements of the GS rule, the project may be permitted

as a Class VI well.

Commenter Name: Quinlan J. Shea Letter ID: 0177 Commenter Organization: Edison Electric Institute Comment ID: 23567

Comment: It is also important to keep in mind the enormous extent to which proper site characterization will minimize any potential risks posed by CO2 storage. Proper site characterization is the most effective risk management tool for CCS. Regulations tailored to ensure proper site selection will in turn minimize the need for regulations crafted to respond to risks that, in such a context, would be extremely unlikely to occur.

Response: The Agency agrees with the commenter about the importance of proper site selection and believes that the site characterization requirements in the GS rule are essential to ensuring that a GSproject will not endanger USDWs. The GS injection requirements, under SDWA authority, ensure protection of USDWs from endangerment through assessment of the suitability of an injection zone (146.83), appropriate site characterization (§146.82), and area of review evaluation (§146.84) among other requirements. The GS requirements are designed to ensure protection of USDWs from endangerment by requiring that injection wells are not only sited properly, but permitted, constructed, operated, monitored, and plugged in a manner that does not endanger USDWs.

Commenter Name: Quinlan J. Shea Letter ID: 0177 Commenter Organization: Edison Electric Institute Comment ID: 23577

Comment: B. Siting and Secondary Containment

Our first area of concern relates to proposed provisions for the siting of GS projects, including requirements related to project site geology and permissible receiving formations. EEI agrees that proper site selection is critical to a successful GS project and notes that it serves to minimize, if not eliminate, any potential threats to drinking water sources that CO2 injection and storage may pose. However, several of the proposed requirements are unnecessary from the perspective of protecting drinking water sources and would only serve to hamper GS projects from going forward.

Response: EPA disagrees that any of these protective requirements are unnecessary, and clarifies believes that a detailed geological site characterization (required under §146.82) is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for the unique nature of injecting large volumes of CO2 into a variety of geological formations for long-term

storage.

The mission of the UIC program and the goal of the GS regulation is to protect USDWs from endangerment, and every aspect of the GS rule is designed toward that end. Therefore, EPA disagrees that any of these protective requirements are unnecessary, and clarifies that waiving any of the requirements would not be acceptable. The GS regulation allows flexibility where appropriate. Certain requirements (e.g., the need to characterize additional confining layers) are at the Director's discretion (§146.83(b)), based on his or her understanding of a particular site.

Commenter Name: Frederick R. Eames Letter ID: 0178 Commenter Organization: CCS Alliance Comment ID: 23853 Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards)

Comment: Siting requirements should reflect that conditions affecting risk differ by site. They need to be tailored to the actual risks presented by specific sites. EOR is a well developed technique and there is now a history through which its risks can be assessed. This differs from injection for long-term storage in deep

saline formations or unmineable coal seams. with which there is little experience, particularly on the massive scale (e.g., a million or more tons per year per plant) envisioned for the future. For CCS to be a viable long-term strategy, policy must encourage development of data about these sites, newtechnology. and new practices.

Response: EPA agrees with the commenter that every site (and the risk posed) is unique. EPA agrees that site characterization should be site-specific, particularly in light of the variety of geologic settings in which GS may be employed. EPA believes that, while there is a large amount of required information, the owner or operator is given flexibility in determining what methods are used to demonstrate the suitability of a potential site. EPA envisions an ongoing dialogue between the Director and the owner or operator during the permitting process (as well as throughout the operation of the site).

Commenter Name: Robert J. Finley Letter ID: 0180 Commenter Organization: Illinois State Geological Survey Comment ID: 23624 Other EPA Comment Codes and Descriptions: 3110 2.1.1 Proposed siting requirements (i.e., injection/confining zones, trapping mechanism)

Comment: 146.83

(a)(2)

Modify this section to indicate that the confining zone is "reasonably expected" to be free of faults and fractures that are transmissive. Again, the behavior of a given fault or fracture in an area cannot be conclusively proven with respect to its impact on fluid flow except by analogy to oil field or gas storage field performance. There is no mechanism to carry out a subsurface test of a fault except possibly in the case of multiple wells opportunely place on opposite sides of a defined fault to access a transmissive unit which can be pressure pulse tested and can be isolated by packers or other equipment. Such tests (obviously) are unlikely to work in a confining zone due to its low permeability.

Response: The Agency believes that the requirement at §146.83(a)(2) that the confining zone be free of transmissive faults or fractures is appropriate for Class VI wells and is necessary to ensure containment of the injectate and that requiring the confining zone to be free of transmissive faults maximizes protection of USDWs from endangerment. Class I hazardous waste injection well operators must also meet a similar requirement that the site is free of transmissive faults or fractures; they have successfully made such demonstrations in the past. While core samples obtained through drilling and hydraulic testing are direct methods to obtain such information, geophysical techniques such as seismic or electromagnetic surveys can also be used in many geologic settings to demonstrate the absence of or identify and characterize the presence of faults or fractures. At sites where deep faults (even with little or no surface expression) are present, processing and interpreting data from multiple geophysical sensing methods has been shown to detect faults better than analysis of data from individual methods (Goussev et al, 2004). Drilling through faults or fractures with appropriate well design, materials, and operation, would not result in an increase in their permeability or a decrease in CO2 containment properties of the related CO2 storage reservoir. In some cases, the use of complementary drilling and geophysical methods might provide the most dependable characterization of potential transmissive faults and fractures. EPA adds that the Director will evaluate all geologic data on the site to ensure protection of USDWs from endangerment before approving a site for a GS project.

EPA acknowledges that some smaller fractures may not be detectable during the site characterizationprocess, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells and sites can mitigate the potential impacts of unidentified fractures. These include limitations on injection pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible CO2 movement through high-permeability regions (i.e., faults and/or fractures) not

detected in the initial site characterization.

Commenter Name: Robert J. Finley Letter ID: 0180 Commenter Organization: Illinois State Geological Survey Comment ID: 23625

Comment: (b)

The words "allow for pressure dissipation" are unclear in meaning with respect to additional zones. If there are no formations in the stratigraphic column at a sequestration site which have been depleted below original reservoir pressure due to hydrocarbon production, all zones are likely to be at hydrostatic pressure (or overpressured, as in parts of the Gulf Coast Basin). Only in a few

instances are formations encountered that have never been drilled and are at less than the basinal hydrostatic pressure gradient. This is the only case where leakage into such a unit may "allow for pressure dissipation". Is that what is meant here? I suggest this phrase be carefully reviewed and considered for

deletion.

Response: EPA clarifies that the primary purpose of the requirement for identification of additional confining zones where needed is to improve USDW protection in cases where a primary confining zone may not be sufficient to meet the UIC programmatic requirement to protect USDWs fromendangerment. The Agency acknowledges that the additional confining formations may also, in sitespecific circumstances, further impede vertical fluid movement, provide additional sites for monitoring, mitigation, and remediation, and allow for pressure dissipation.

Commenter Name: Thomas Curtis Letter ID: 0181 Commenter Organization: American Water Works Association (AWWA) Comment ID: 23728 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Part 146.83(a)(1) AWWA recommends revising this part to read:

An injection zone of sufficient areal extent, thickness, porosity, and permeability to receive the total anticipated volume of the carbon dioxide stream, and at a depth with sufficient overburden pressure to keep the carbon dioxide stream as a supercritical fluid.

Response: EPA disagrees that the GS rule should require that the CO2 remain in a supercritical state. EPA believes that, in many cases CO2 will be injected at depths where it will remain supercritical. However, the final rule does not require that it remain in a supercritical state once it is injected; nor does the rule preclude the injection of gaseous CO2 into shallower non-USDWs provided that the owner or operator meets the Class VI requirements and ensures protection of USDWs from endangerment.Commenter Name: Thomas Curtis Letter ID: 0181 Commenter Organization: American Water Works Association (AWWA) Comment ID: 24377 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Part 146.83(a)(2) AWWA recommends revising this part to read:

A confining zone(s) that is free of transmissible faults or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide stream and displaced formation fluids and allow injection at proposed maximum pressures and volumes without initiating or propagating fractures in the injection and confining zone(s).

Response: EPA acknowledges the importance of selecting GS sites with confining zones that are free of transmissive faults and fractures but disagrees that the rule should prohibit fracturing within the injection zone. EPA believes that, in some circumstances, fracturing is necessary (i.e., in association with an approved for stimulation program to improve wellbore and formation injectivity). EPA clarifies that all stimulation for GS must be approved by the Director pursuant to requirements at §146.91.

Commenter Name: Adam P. Haynes Letter ID: 0184 Commenter Organization: Texas Independent Producers and Royalty Owners Association (TIPRO) Comment ID:

22787 Other EPA Comment Codes and Descriptions: 2143 1.6.2.1 Comments in favor of injection into depleted reservoirs

Comment: An additional point of concern in the rules is the limited view of applicable storage sites. While brine aquifers may indeed be good candidates for geologicstorage, the same is true of oil and gas reservoirs, both productive and nonproductive. The EPA should develop a site rating system that allows for the geologic storage of CO2 in stable subsurface formations. This type of rating system will ensure that sites which are best suited to handle large CO2 storage projects are utilized and any CCS regulatory system will have early successes. Of course, the most likely sites to score well in any ranking system would be formations containing or having contained hydrocarbon reserves and properly permitted Class II wells existing in these formations should be acceptable

conduits for CCS.

Response: EPA disagrees that a rating system is appropriate. Instead, the GS rule focuses on evaluating the suitability of a site based on site-specific geological and operational data. EPA believes that a detailed geological site characterization (required under §146.82) is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for the unique nature of injecting large volumes of CO2 into a variety of geological formations for long-term

storage.

EPA agrees that depleted oil and gas fields are promising formations for GS, provided the Class VI siting, well construction and operation, monitoring and testing, and post-injection site care and site closure requirements are met. EPA adds that injection of carbon dioxide for the purposes ofenhanced oil recovery is classified as Class II injection, not Class VI, and will require a Class II permit. Wells for which the primary purpose is long term sequestration are considered Class VI

wells.

EPA adds that the GS rule does not include criteria for rating particular sites for GS. EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations to owners or operators regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Daniel Plath Letter ID: 0188 Commenter Organization: NiSource, Inc. Comment ID: 25238

Comment: 5. Data and MMV Requirements (146.82 and 146.90)

The Proposed Rule has potentially very extensive data and monitoring, measuring and verification (MMV) requirements, particularly once this is an established and proven technology. The required data to prudently develop a GS site and to monitor the gas plume is extremely site specific and industry knowledge base dependent. A pilot project will inherently require more frequent and diverse data collection and modeling than the nth project in the same formation. The Final Rule needs to recognize the clear differences in data requirements for first of its kind projects, where the primary driver is risk mitigation due to the multitude of unknowns, versus the application of a well developed technology for which cost effectiveness is the primary consideration because the experience and knowledge exists to effectively identify and manage the risks. NiSource does not see any recognition of this significant difference in the Proposed Rule and respectfully submit that EPA incorporate language accordingly.

Response: EPA acknowledges that early pilot projects may focus on gathering data to inform GS technology. However, EPA believes that a detailed geological site characterization of every GS site (as required under §146.82) is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for the unique nature of injecting large volumes of CO2 into a variety of geological formations for long-term storage. EPA adds that, if data on a formation or site collected in connection with an earlier project can support a geologic characterization, the Director has discretion to accept this data, provided it is sufficient to demonstrate site suitability.

The mission of the UIC program and the goal of the GS regulation is to protect USDWs from endangerment, and every aspect of the GS rule is designed toward that end. Therefore, EPA disagrees that any of these protective requirements are unnecessary, and clarifies that waiving any of the requirements would not be acceptable. The GS regulation allows flexibility where appropriate.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24329Comment: III. Comments Regarding Proposed Class VI Requirements

A. Geologic Siting Requirements

In view of the need to promote appropriate use of GS to reduce CO2 emissions, the regulations should be designed to allow GS in any geologic setting in which the Director concludes that GS can be conducted without endangering USDWs. It follows that the regulations should give the Director discretion to apply the "non-endangerment" performance standard on a site-specific basis as particular geologic site conditions warrant, without the need to apply prescriptive criteria that - while perhaps necessary to endure protection of USDWs in some cases - would arbitrarily disqualify some sites that would in fact be appropriate for GS. This does not mean that regulation need be lax; it simply means that regulation must be flexible, and that rigid criteria should not substitute for performance-based standards and site-specific consideration of

the merits.

The preamble to the proposed rule outlines normal site selection criteria for injection well projects, including the need to identify an injection zone withsufficient permeability, porosity, thickness and lateral extent and a lowpermeability confining zone with sufficient thickness and lateral extent to protect overlying USDWs. 73 Fed. Reg. at 43505. These are familiar and appropriate geologic siting requirements for injection well operations, and the regulatory text proposed for codification at 40 C.F.R. 146.83(a) - with relatively minor technical changes - would embody them appropriately. Unfortunately, the preamble goes on to suggest the need for overly-elaborate analysis of extraneous issues, and the rule text proposed for codification at 40 C.F.R. 146.83(b) would allow the Director apparently unlimited discretion to impose siting conditions that go beyond those necessary to ensure protection of USDWs. EPA should clarify that site evaluation should go no farther than necessary to prevent endangerment, and should eliminate any apparent discretion to impose siting requirements that are not necessary to protect USDWs.

Response: The final rule does not preclude injection into any formations or types of injection sites provided that the wells meet the final GS rule requirements. The purpose of the GS regulation is to ensure that injection of CO2 for GS is conducted in a manner that is protective of USDWs. This includes appropriate site characterization and identification of geologic formations that are amenable to injection of potentially large volumes of CO2 for long-term storage. The regulation provides flexibility to owners or operators to select appropriate sites and target formations (under §146.82), well construction specifics (under §146.86), and injection procedures provided the owner or operator can demonstrate that the injection and storage will not endanger USDWs and that minimum requirements for the site are met.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24402 Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions

Comment: Rule Provision: 146.81(d) [Definition - Confining zone]

Proposed CCS Group Recommendations: Confining zone means a geological formation,group of formations, or part of a formation THAT IS CAPABLE OF LIMITING FLUID

MOVEMENT FROM AN INJECTION ZONE.

Basis for CCS Group Comments: The current UIC program definition of confining zone is preferable to the proposed definition. There are no special circumstances for CO2 streams that warrant a change. In addition, the word "above" should be changed to "from" to accommodate situations where USDWs may be beneath as well as above the injection zone.

Response: EPA did not change the requirement that injection occur below the lowermost USDW. However, the final GS rule contains a provision (at §146.95) for owners or operators to apply for waivers from the requirement that injection be below the lowermost USDW. EPA believes this waiver provision will reduce potential limitations on the re-permitting of Class II wells as Class VI wells, provided they meet the requirements at §146.95, while still protecting USDWs from endangerment.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24410 Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions

Comment: Rule Provision: 146.81(d) [Definition - transmissible fault or fracture]

Proposed CCS Group Recommendations: transmissible fault or fracture means a fault or fracture that has sufficient permeability and vertical extent to allow fluids

to move between formations BEYOND THE CONFINING ZONE.

Basis for CCS Group Comments: The term "between formations" is inaccurate since there can be multiple formations within an injection zone. The critical factor for transmissivity is movement of injected or displaced fluids beyond the confining zone.

Response: EPA has retained the proposed definition, which is the same as the existing definition at §148.2, to address transmissive faults and fractures that extend beyond the confining zone.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24414 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(c)

Proposed CCS Group Recommendations: (c) A MAP DELINEATING the area of review

based on UPON modeling, using ALL AVAILABLE data INCLUDING DATA obtained during logging and testing of the well and the formation as required by paragraphs (l), (r), and (s) of this section ANY WELLS IN THE AREA OF REVIEW

Basis for CCS Group Comments: This appears to be related to a condition where a well is already drilled. This does not align with requesting information to receive a permit.Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of information to be submitted. In addition, section §146.82 in the final rule is similar to the permit application requirements for other injection well classes, which could help avoid confusion about how to meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to be submitted before operation of the well is authorized are very similar to those for Class I wells, with modifications and additions that address the unique challenges and types of data

collected for GS wells.

The requirement to provide the final area of review based on modeling and data obtained during logging and testing is in the final GS rule at §146.82(c)(1). Please see the final rule and the discussion of geologic site characterization in the preamble for additional information.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24419 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(e)

Proposed CCS Group Recommendations: (e) A tabulation RECORD of all wells ARTIFICIAL PENETRATIONS within the area of review which penetrate THAT REACH the injection or confining zone(s). Such data AS AVAILABLE IN THE PUBLIC RECORD must include a description of each well’s PENETRATION’S type, construction, date drilled, location, depth, record of plugging and/ or completion, and any additional information the Director may require;

Basis for CCS Group Comments: "Artificial penetrations" is a more inclusive

term.

Rule Provision: 146.82(f)

Proposed CCS Group Recommendations: (f) Maps and stratigraphic cross sections indicating the general vertical and lateral limits of all USDWs, water wells and springs within the area of review, their positions relative to the injection zone(s) and the direction of water movement, where known; POTENTIOMETRIC (WATER LEVEL) SURFACE MAP(S) OF EXISTING AQUIFERS BEING UTILIZED AS

PRIVATE OR

PUBLIC WATER SUPPLIES AND THE DIRECTION OF GROUNDWATER FLOW IN THESE AQUIFERS

WITHIN THE AREA OF REVIEW. AT LEAST TWO GEOLOGIC CROSS SECTIONS

SHOWING THE

THICKNESS AND GENERAL VERTICAL AND LATERAL LIMITS OF ALL USDWS WITHINTHE AREA

OF REVIEW.

Basis for CCS Group Comments: This revision more accurately identifies the information that is needed and should be considered for permitting.

Rule Provision: 146.82(g)

Proposed CCS Group Recommendations: (g) Baseline geochemical data on subsurface formations, including all USDWs in the area of review COMPILATION

OF AVAILABLE GEOCHEMICAL DATA ON THE PROPOSED INJECTION ZONE AND

NEAREST POROUS

AND PERMEABLE FORMATION ABOVE THE CONFINING ZONE.

Basis for CCS Group Comments: Limits the data to be submitted to available information and to the injection zone and the zone immediately above the confining zone which are the zones most likely to be monitored for potential CO2 leakage.

Response: EPA believes that a determination of what information may be necessary for a specific Class VI well and what information is available in the public record will be site-specific and based on data availability and data quality. For instance, in meeting the requirement to tabulate information on wells in the AoR, the Director has the discretion to require the owner or operator to supplement a data records search if there is reason to believe that the incompleteness of available information could compromise USDW protection from endangerment. Please see the final rule and the discussion of permitting and geologic site characterization in the preamble for additional information.

EPA believes that a thorough understanding of the hydrogeologic conditions of all USDWs in the AoR is necessary, and disagrees with the suggested edits because the GS rule, as written, affords flexibility to owners or operators and Directors to tailor the site characterization process to the unique features of the site. EPA encourages owners or operators and Directors to collaborate and consult during site characterization to discuss information needs and ensure that all appropriate data to assess the suitability of the site are collected. The Director also has the authority to request additional hydrogeologic data or other data on USDWs.

The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR, is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate and transport model development (e.g., by providing appropriate input parameters), and provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. The baseline geochemical information will allow the owner or operator and permitting authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may

indicate fluid movement.

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion to require geochemical analysis of additional subsurface zones if, in the Director's opinion, they are necessary for the protection of USDWs from endangerment.Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24421 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Rule Provision: 146.83(a) & (a)(1)

Proposed CCS Group Recommendations: Support the proposed language.

Basis for CCS Group Comments: Agree with EPA’s rationale.

Response: EPA acknowledges the comment.

Commenter Name: Jeff W. Sheets Letter ID: 0192 Commenter Organization: ConocoPhillips Comment ID: 23888

Comment: o Appropriate site selection supported by rigorous characterization provides the strongest foundation for protection of USDWs. It is important that a diversity of geologic containment systems be used for sequestration, and that site selection requirements do not unnecessarily exclude potential storage sites.

Response: EPA agrees that site characterization is an important aspect of ensuring USDW protection, and clarifies that the final rule does not preclude injection into any formations or types of injection sites provided that the wells meet the final GS rule requirements. The purpose of the GS regulation is to ensure that injection of CO2 for GS is conducted in a manner that is protective of USDWs. This includes appropriate site characterization and identification of geologic formations that are amenable to injection of potentially large volumes of CO2 for long-term storage. The regulation provides flexibility to owners or operators to select appropriate sites and target formations (under §146.82), well construction specifics (under §146.86), and injection procedures provided the owner or operator can demonstrate that the injection and storage will not endanger USDWs and that minimum requirements for the site are met.

Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24640 Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions

Comment: Rule Provision: 146.81(d) [Definition - Transmissive fault or fracture]

Anadarko Petroleum Corporation (APC) Comments: Transmissive fault or fracture means a fault or fracture that has sufficient permeability and vertical extent

to allow fluids to move between formations BEYOND THE CONFINING ZONE.

Rationale: The term "between formations" is inaccurate since there can be multiple formations within a injection zone. The critical factor for transmissivity is movement of injected or displaced fluids beyond the confining

zone.

Response: EPA has retained the proposed definition, which is the same as the existing definition at §148.2, to address transmissive faults and fractures that extend beyond the confining zone.Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24642 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(c)

Anadarko Petroleum Corporation (APC) Comments: (c) A MAP DELINEATING the area of

review based on UPON modeling, using ALL AVAILABLE data INCLUDING DATA obtained during logging and testing of the well and the formation as required by paragraphs (l), (r), and (s) of this section ANY WELLS IN THE AREA OF

REVIEW

Rationale: This appears to be related to a condition where a well is already drilled. This does not align with requesting information to receive a permit.

Response: EPA recognizes that this information may not be available until after a well has been drilled. EPA revised §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

Final information on injection zone pressures would be required. EPA recognizes that this information may not be available until after a well has been drilled. EPA revised §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)). Final information on injection zone pressures would be required following drilling of the well, at §146.82(c)(4).

In the final rule, the requirement for the final AoR based on modeling, including data obtained during logging and testing, can be found at §146.82(c)(1). Please see the final rule and the discussion of geologic site characterization in the preamble for additional information.

Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24646 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(e)

Anadarko Petroleum Corporation (APC) Comments: (e) A tabulation of all wells ARTIFICIAL PENETRATIONS within the area of review which penetrate the injection or confining zone(s). Such data must include a description of each well’s type, construction, date drilled, location, depth, record of plugging and/ or completion, and any additional information the Director may require;

Rationale: Artificial penetrations is a more inclusive term.

Response: EPA agrees that all artificial penetrations must be identified and evaluated during site characterization. However the final rule retains the proposed text to be consistent with similar requirements for other well classes and to support the corrective action requirements. EPA isdeveloping guidance on AoR and corrective action at GS Class VI sites to assist owners or operators and Directors in evaluating requirements and proposed AoR and corrective action plans under §146.84. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24647 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(f)

Anadarko Petroleum Corporation (APC) Comments: (f) Maps and stratigraphic cross sections indicating the general vertical and lateral limits of all USDWs, water wells and springs within the area of review, their positions relative to the injection zone(s) and the direction of water movement, where known; POTENTIOMETRIC (WATER LEVEL) SURFACE MAP(S) OF EXISTING AQUIFERS BEING

UTILIZED

AS PRIVATE OR PUBLIC WATER SUPPLIES AND THE DIRECTION OF GROUNDWATER

FLOW IN THESE AQUIFERS WITHIN THE AREA OF REVIEW. AT LEAST TWO GEOLOGIC CROSS

SECTIONS

SHOWING THE THICKNESS AND GENERAL VERTICAL AND LATERAL LIMITS OF ALL

USDWS

WITHIN THE AREA OF REVIEW.

No rationale provided

Response: The Agency acknowledges the suggested edits but has retained the language as proposed. EPA believes that a thorough understanding of the hydrogeologic conditions of all USDWs in the AoR is necessary to protect USDWs from endangerment, and disagrees with the suggested edits because the GS rule, as written, affords flexibility to owners or operators and Directors to tailor the site characterization process to the unique geologic features of the site. The final requirements will allow for submittal of information similar to or the same as that which was suggested by the commenter. EPA encourages owners or operators and Directors to consult during site characterization to discuss information needs and ensure that all appropriate data necessary to assess the suitability of the site are collected. The Director may request additional hydrogeologic data or other data on USDWs as well, as provided in §146.82(a)(21).

Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24648 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(g)

Anadarko Petroleum Corporation (APC) Comments: (g) Baseline geochemical data on subsurface formations, including all USDWs in the area of review

COMPILATION OF AVAILABLE GEOCHEMICAL DATA ON THE PROPOSED INJECTION

ZONE ANDNEAREST POROUS AND PERMEABLE FORMATION ABOVE THE CONFINING ZONE.

Rationale: Limits the data submitted to available information and to the injection zone and the zone immediately above the confining zone which is the zones most likely to be monitored for potential CO2 leakage.

Response: The Agency acknowledges the suggested edits but has retained the language as proposed. EPA believes that a thorough understanding of the hydrogeologic conditions of all USDWs in the AoR is necessary, and disagrees with the suggested edits because the GS rule, as written, affords flexibility to owners or operators and Directors to tailor the site characterization process to the unique features of the site. EPA encourages owners or operators and Directors to consult during site characterization to discuss information needs and ensure that all appropriate data necessary to assess the suitability of the site are collected. The Director has the authority to request additional hydrogeologic data or other data on USDWs as well.

The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR, is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate and transport model development (e.g., by providing appropriate input parameters), and provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. The baseline geochemical information will allow the owner or operator and permitting authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may

indicate fluid movement.

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion to require geochemical analysis of additional subsurface zones if, in the Director's opinion, they are necessary for the protection of USDWs from endangerment.

Commenter Name: Brad Castleberry Letter ID: 0203 Commenter Organization: Water Environment Association of Texas (WEAT) Comment ID: 22179 Other EPA Comment Codes and Descriptions: 4600 2.6 Proposed Plume and Pressure Front Monitoring Requirements (40 CFR 146.90)

Comment: groundwater quality as well as public drinking water sources. Careful consideration should he given to ensure an adequate assessment is made of each proposed injection well site. This consideration should come in the form of detailed site studies. sophisticated computer modeling, and other tools used to predict hydrogeology. Careful consideration should also he given to ensure that adequate ongoing monitoring and reporting is provided for any site ultimately permitted pursuant to the proposed rules. Given the unique circumstancessurrounding this type of pollutant, and the lack of a significant body of longterm evidence to support the proposed activity, we would encourage EPA to include significant monitoring and reporting provisions to ensure the long-term viability of any permitted site with respect to surrounding groundwater quality.

Response: EPA agrees with the commenter regarding the importance of site characterization, and believes that the extensive requirements for geologic site characterization (at §146.82), AoR evaluation (§146.84), and testing of the well during drilling (§146.87) are appropriate to ensure thatpermitting authorities have the necessary information to evaluate whether a specific site will allow safe injection of CO2. EPA adds that submittal and review of monitoring data (as required at §146.90) and the AoR reevaluation process (§146.84(e)) will provide an opportunity for an ongoing review of the site and a dialogue between the Director and the owner or operator to ensure that the project is being operated in a manner that protects USDWs from endangerment.

EPA believes that monitoring plans and methods need to be site-specific and that the monitoring requirements for GS sites at §146.90 provide an appropriate level of flexibility in structuring a testing and monitoring plan that protects USDWs from endangerment.

The GS rule, at §146.90, requires injectate monitoring, mechanical integrity testing, corrosion monitoring, tracking the CO2 plume and area of elevated pressure, monitoring geochemical changes above the confining zone, and, at the discretion of the Director, surface air and soil gas monitoring for CO2 fluctuations, and any additional tests necessary to ensure USDW protection from endangerment.

EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in evaluating requirements under §146.90, including proposed monitoring plans. The guidance describes available technologies and recommended approaches for implementing a testing and monitoring plan, including pre-operational geophysical logging and testing of injection wells, MITs, injection well testing during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which may be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Thomas Curtis Letter ID: 0204 Commenter Organization: American Water Works Association (AWWA) Comment ID: 22182

Comment: - Geosequestration activities should be prohibited in the immediate vicinity of sole source aquifers.

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

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

Commenter Name: Diane VanDe Hei Letter ID: 0206 Commenter Organization: Association of Metropolitan Water Agencies (AMWA) Comment ID:

22208

Comment: - Protection of drinking water sources and potential future underground sources of drinking water (USDW) is paramount. As a result AMWA and AWWA recommend that:

o The final CO2 geologic sequestration regulation should at a minimum, prohibitthe construction of CO2 sequestration wells in any sole source aquifers and restrict any project in the vicinity of any sole source aquifer.

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

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

Commenter Name: Diane VanDe Hei Letter ID: 0206 Commenter Organization: Association of Metropolitan Water Agencies (AMWA) Comment ID:

22209 Other EPA Comment Codes and Descriptions: 1310 1.1.2.4 Comments on other "out of scope" issues, e.g., pore space ownership; 1610 1.3.1 Risks to USDWs

Comment: - The USDW classification must be reconsidered when siting Class VI wells. The best sources of drinking water are already being used by utilities. Coupled with challenges resulting from climactic changes, population growth and land development, many utilities are turning to more challenging groundwater sources such as those that are very deep or have high salinity concentrations, also because the pumping costs for these deep wells are no longer prohibitive given

the lack of sufficient water elsewhere. Some of these new sources could fall outside of the current definition of a USDW, in that the aquifer has a TDS concentration higher than 10,000 ppm. EPA’s proposed rule promises protection of USDWs from endangerment yet there are no anti-degradation provisions in the proposed regulation to protect other groundwater supplies, such as those aquifers that are not classified as a USDW but have been, or may be, identified as a future drinking water source. The TDS criterion was written at a time when many advanced water treatment technologies were generally cost prohibitive. In light of the changes in the hydrological and technological landscape, we

recommend that EPA reexamine the classification of USDWs based on TDS when considering the siting of Class VI geosequestration wells. The potential need to use saline aquifers for potable supply, particularly in water-stressed areas, should take precedence over the sequestration of carbon dioxide there.

Response: The Agency acknowledges commenter concerns about water resources and future water resource availability. However, modifying the definition of a USDW is outside the scope of the GS rulemaking. USDWs are defined as aquifers currently being used as sources of drinking water or those capable of supplying a public water system and they have a total dissolved solids (TDS) content of 10,000 milligrams per liter or less (§144.3).

The primary goal of the UIC Program under the SDWA is to protect USDWs in order to ensure a reliable supply of drinking water for the American public. The GS rule, as part of the UIC program regulations, continues the program’s tradition of ensuring the protection of USDWs. The permitting, siting, construction, operation, monitoring, and post-injection site care requirements in the GS rulebuilt on a long-standing protective regulatory framework, tailored to the unique characteristics of

CO2 GS.

Commenter Name: John King Letter ID: 0211 Commenter Organization: Shell Exploration and Production Company (SEPCo) Comment ID:

22751

Comment: - Site Characterization/Evaluation: EPA should seek to develop clear performance standards as detailed in the American Petroleum Institute’s submission regarding site characterization. The need for adequate site characterization and evaluation cannot be understated, however it is critical that EPA works to clarify the site evaluation needs and ensure that they are no more elaborate than necessary to ensure protection of USDWs.

Response: EPA agrees with the commenter on the importance of proper site characterization, and clarifies that the purpose of the GS regulation is to ensure that injection of CO2 for GS is conducted in a manner that is protective of USDWs based on an evaluation of site-specific information. This includes appropriate site characterization and identification of geologic formations that are amenable to injection of potentially large volumes of CO2 for long-term storage. The regulation provides flexibility to owners or operators to select appropriate sites and target formations (under §146.82), well construction specifics (under 146.86), and injection procedures provided the owner or operator can demonstrate that the injection and storage will not endanger USDWs and that minimum requirements for the site are met.

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

Commenter Name: Diane VanDe Hei Letter ID: 0213 Commenter Organization: Association of Metropolitan Water Agencies (AMWA) Comment ID:

22919

Comment: AMWA supports strong criteria for site selection, design and operation of carbon sequestration sites. EPA’s rule and any financial incentives put forth by other

Response: EPA agrees with the commenter. The GS requirements are designed to ensure protection of USDWs from endangerment by requiring that injection wells are permitted, sited, constructed, operated, monitored, and plugged in a manner that does not endanger USDWs as informed by extensive, site-specific site characterization data.

Commenter Name: Edward Steadman Letter ID: 0220 Commenter Organization: The Energy and Environmental Research Center at the University of North Dakota Comment ID:

21611 Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards)Comment: There is also text in this section that can be interpreted as requiring the owner/operator to submit core, outcrop, seismic survey, cross sections, well logs, and other unspecified data. Some later passages on this subject suggest that they are not all necessarily required, but rather are examples of types of data that could be used to demonstrate and quantify various key characteristics of a formation. With respect to the need for various types of geological data, the document is at times vague, inconsistent and, occasionally, even contradictory. It is critical that geologic heterogeneity and regional differences in data availability be acknowledged and state or regional directors be given the flexibility to make decisions based on data sets that reflect the geologic and regional differences. For instance, seismic survey data are limited in coverage, are expensive to acquire, can be inconclusive with respect to interpretation, and should not be universally required as a precondition for site consideration. The regulations must be performance-based and reinforce the need to technically and efficiently achieve specific goals, such as proving that an adequate and competent seal exists or that a target formation has sufficient injectivity. The regulations should not prescribe precisely how such proof is obtained, but should only dictate that sufficient proof be presented to the director. The regulations should give the director a significant degree of flexibility to determine whether the body of evidence presented by the owner/operator constitutes sufficient proof that USDWs will be protected. The regulations may include a list of useful data types, but EPA should clearly

state that the list is one of available tools from which to choose the most applicable to a specific site, not a list of required applications and data that must be acquired and presented.

Response: EPA disagrees that any of these protective requirements are unnecessary. EPA believes that requiring appropriate site characterization by the owner or operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific geologic data will afford the greatest protection of USDWs from endangerment. EPA believes that it is important for the Director to have as much site-specific information as possible in order to make an informed decision to permit injection for GS at a specific site. The GS regulation allows flexibility where appropriate. Certain requirements (e.g., the need to characterize additional confining layers) are at the Director's discretion (§146.83(b)), based on his or her understanding of a particular site.

Additionally, EPA disagrees that consideration of local and regional seismicity is not important. The site characterization provisions in the GS rule, including a review of the local and regional geology, and detailed review of any known or potential seismically active terrain in the vicinity of a proposed GS site are necessary to minimize the potential for induced seismic events or the reactivation of faults, which are a known potential risk associated with injection and are addressed in all aspects of the UIC regulations.

Commenter Name: Edward Steadman Letter ID: 0220 Commenter Organization: The Energy and Environmental Research Center at the University of North Dakota Comment ID:

21633

Comment: Page 43536. § 146.83 Minimum criteria for siting. Requiring the injection zone to have the ability to receive the "total anticipated volume of the carbon dioxide stream" seems unreasonable. Linking CO2 source potential with CO2 injection potential is not recommended, and flexibility is required. Forexample, if the stream is coming from a power generating facility, it can be difficult to estimate the longevity of the plant given changes in technology that may allow for increased energy output. Multiple storage sites may be required for one source, or conversely, multiple sources may utilize a single storage site.

Response: The Agency disagrees with the commenter that there should not be an absolute requirement that the injection zone be capable of receiving the total anticipated volume of CO2. The GS rule is designed to ensure that the total volume of CO2 anticipated to be injected can be safely stored within the target injection zone. This evaluation is based on site-specific characteristics including the local geology (e.g., data on formation thickness, porosity, and permeability and the presence of confining zones). The GS injection requirements, under SDWA authority, ensure protection of USDWs from endangerment through assessment of the suitability of an injection zone (§146.83), appropriate site characterization (§146.82), and area of review evaluation (§146.84) among other requirements.

The Agency believes that this comment may be based on an assumption that Class VI injection wells will be co-located with CO2 producing facilities. While this may, in some cases, be an accurate assumption, the specifications, design, and purpose of the CO2 source/facility are not addressed by the Class VI GS requirements.

The productivity of the CO2 source (e.g., power plant, industrial facility, etc.) is not the driver of site suitability. Rather, the acceptability of a candidate site is determined, in part, by the amount of CO2 it can receive without allowing pressures in the injection formation to build up to levels that may fracture the confining zone or cause unacceptable fluid movement. If a CO2 source produces more than a formation can hold, then once the capacity of the receiving formation is reached, any additional CO2 produced would have to be injected elsewhere.

Commenter Name: Tiffany Rau Letter ID: 0224 Commenter Organization: Hydrogen Energy International Comment ID: 21671

Comment: (B) WELLS, MONITORING & OPERATIONS

In general, regulations for geologic sequestration should provide for effective storage management by requiring the following activities:

- Site characterization that validates the geological model of the storage site and confirms potential leakage pathways have been identified and evaluated;

- Risk assessment that builds upon the predicted behavior and movement of the co2 in the reservoir over time and confirms that the potential for leakage has been evaluated through site characterization; and

Response: EPA agrees with the commenter. The requirements for geologic site characterization are based on a long standing UIC regulatory framework tailored to address specific risks to USDWs posed by injection. These requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.Commenter Name: Brian Williams Letter ID: 0225 Commenter Organization: BP Alternative Energy North America, Inc. (BP) Comment ID: 21716

Comment: (B) WELLS, MONITORING & OPERATIONS

In general, regulations for geologic sequestration should provide for effective storage management by requiring the following activities:

- Site characterization that validates the geological model of the storage site and confirms potential leakage pathways have been identified and evaluated;

- Risk assessment that builds upon the predicted behavior and movement of the CO2 in the reservoir over time and confirms that the potential for leakage has been evaluated through site characterization; and

Response: EPA agrees with the commenter. The requirements for geologic site characterization are based on a long standing UIC regulatory framework tailored to address specific risks to USDWs posed by injection. These requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: Andrew Duguid Letter ID: 0226 Commenter Organization: Schlumberger Carbon Services Comment ID: 24018 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: §146.83 Minimum criteria for siting.

Proposed Rule: (2) A confining zone(s) that is free of transmissive faults or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide stream and displaced formation fluids and allow injection at proposed maximum pressures and volumes without initiating or propagating fractures in the confining zone(s); and

Schlumberger Suggested Revision: -

Schlumberger Rationale: We support this language as it is written.

Response: EPA acknowledges the comment and the final rule retains the text at §146.83 as proposed.

Commenter Name: Ben Yamagata Letter ID: 0227 Commenter Organization: Coal Utilization Research Council Comment ID: 21783

Comment: -The potential requirement for "buffer zones" in addition to a confining zone (§146.83(b)).

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in somesituations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: Pamela A. Lacey Letter ID: 0228 Commenter Organization: American Gas Association Comment ID: 21803 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: - Minimum criteria for siting: We request that EPA revise proposed section 146.83(a) to say that "Owners or operators of Class VI wells must demonstrate to

the satisfaction of the Director that the wells will be sited in areas with a suitable geologic system, and in a manner that will not adversely impact the safe operation of nearby natural gas underground storage facilities, in compliance with applicable safety regulations and guidelines of the Department of Transportation." (Requested amended language in italics.) Further, the required geologic assessment should include analysis of potential leak paths through faulting, fracturing, or other migration paths from injected CO2 in formations in close proximity above or below a natural gas storage formation.

Response: EPA believes that the extensive requirements for geologic site characterization (at §146.82), AoR evaluation (§146.84), and testing of the well during drilling (§146.87) are appropriate to ensure that permitting authorities have the necessary information to evaluate whether a specific site will allow safe injection of CO2. EPA adds that submittal and review of monitoring data (as required at §146.90) and the AoR reevaluation process (§146.84(e)) will provide an opportunity for an ongoing review of the site and a dialogue between the Director and the owner or operator to ensure that the project is being operated in a manner that protects USDWs from endangerment. EPA believes that any natural gas storage operations would be found in site characterization as would any

faults or fractures.

Commenter Name: A. James Mayer Letter ID: 0230 Commenter Organization: A. J. Mayer International on behalf of the American Energy Security Initiative Comment ID:

21887 Other EPA Comment Codes and Descriptions: 2100 1.6 Target Geologic Formations for GS

Comment: 4. EPA should provide flexibility in the siting requirements including promoting utilization of EOR, Enhanced Gas Recovery (EGR) and Enhanced Coalbed Methane Recovery (ECBM) formations for storage.

Response: EPA clarifies that the GS rule does not categorically preclude injection of CO2 into any non-USDW formation types. The purpose of the GS rule is to ensure protection of USDWs from endangerment, and the rule requires that owners or operators demonstrate that wells are sited in suitable systems with geologic formations to receive and confine injected CO2, required at §146.83 of the GS rule. The Class VI siting, well construction and operation, monitoring and testing, and post-injection site care and site closure requirements are designed to ensure that injected CO2remains within the target formation. If an owner or operator can demonstrate to the Director's satisfaction that GS in coal seams, basalts, salt domes, or shales can be accomplished in a manner that protects USDWs and meets all of the requirements of the GS rule, the project may be permitted

as a Class VI well.

EPA acknowledges that site-suitability for GS is dependent on a number of factors and that many formation types may be suitable for GS. EPA agrees that GS into unmineable coal seams has the potential to allow sequestration while ensuring USDW protection from endangerment, as described by commenters citing the process of enhanced methane recovery. The final GS rule does not preclude injection into unmineable coal seams provided owners or operators can demonstrate that GS can be performed in a manner that protects USDWs from endangerment. The Agency clarifies that owners or operators of Class VI wells used for injecting CO2 into unmineable coal seams are subject to the same site characterization, well construction, operation, monitoring, post-injection site care and site closure requirements that are required of projects injecting into other formation types.

Commenter Name: Abbie Krebsbach Letter ID: 0235 Commenter Organization: Montana-Dakota Utilities Co. Comment ID: 23181 Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards)

Comment: Careful Characterization of Site Risks

It is, of course, crucial that the final rule meet EPA's objective of protecting drinking water supplies. We are concerned, however, that some of the more stringent requirements being proposed for Class VI wells are not supported by findings of unique risks actually posed by CCS wells. EPA's regulations should be based upon an accurate characterization of the potential risks posed by the geologic sequestration of CO2 and be specifically tailored accordingly to address those identified risks. This will ensure that EPA meets its obligation to provide appropriate protection of underground sources of drinking water, while avoiding unnecessary regulations that may hamper CCS or EOR projects from going forward or call into question the general safety of CO2 storage.

Regulations tailored to ensure proper site selection will in turn minimize the need for regulations crafted to respond to risks that, in such a context, would be extremely unlikely to occur. For example, simply limiting CO2 injection to

Response: EPA believes that a detailed, site-specific, geologic site characterization (required under §146.82) is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for the unique nature of injecting large volumes of CO2 into a variety of geological formations for long-term storage.

Commenter Name: Philip Papadeas Letter ID: 0238 Commenter Organization: Sandia Technologies, LLC Comment ID: 23348

Comment: Geologic CharacterizationEPA should allow an applicant to drill a site stratigraphic test well, convertible later to a Class VI injection well. All information should be provided, and utilized for modeling the reservoir, with conservative model inputs and predictions for determining future operations.

Response: EPA anticipates that test wells will be drilled to support geologic site characterization of the proposed GS sites and can be used to collect subsurface samples, e.g. for laboratory determination of capillary pressure, and take other necessary measurements.

EPA believes that the requirements for geologic site characterization (at §146.82), AoR evaluation (§146.84), and testing of the well during drilling (§146.87) are appropriate to ensure that permitting authorities have the necessary information to evaluate whether a specific site will allow safe injection of CO2.

Commenter Name: Philip Papadeas Letter ID: 0238 Commenter Organization: Sandia Technologies, LLC Comment ID: 23350

Comment: §146.82 (d) (2)

Re: Faults transmissive or sealing? Whether faults are transmissive or sealing in the injection interval, or zone is immaterial, if the reservoir and injection interval can pass modeling scenarios using conservative assumptions successfully preventing fluid migration to the USDW, then these operational considerations should be used as the key threshold and benchmark for EPA’s geological evaluation. Class I operators are required to model both scenarios if data is not known or exists and this similar approach

should be followed.

Response: The Agency believes that the requirement at §146.83(a)(2) that the confining zone to be free of transmissive faults or fractures is appropriate for Class VI wells and is necessary to ensure containment of the injectate and that requiring the confining zone to be free of transmissive faults maximizes protection of USDWs from endangerment. EPA clarifies that geological data collected during site characterization, including information on faults, will be used as inputs for AoR modeling. Modeling results, in concert with other site characterization information, will be used to determine if a site is appropriate for GS and will ensure protection of USDWs from endangerment.

Commenter Name: Philip Papadeas Letter ID: 0238 Commenter Organization: Sandia Technologies, LLC Comment ID: 23351 Other EPA Comment Codes and Descriptions: 3860 2.3.3 Well component degradation

Comment: §146.82 (h) (i, j) Re: Compatibility testing should be performed from cores and either native or synthesized formation fluid and injectate to determine and demonstrate potential reactivity of the injectate with formations, tubular materials, and other waste or injectate mixtures. This is presently performed for all Class I hazardous wastes, and should be employed as a one-time initial testing program for new well operations and injection constituents, composition and properties.

Response: EPA has revised subpart §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before wellconstruction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

Commenter Name: Kevin Wanttaja Letter ID: 0248 Commenter Organization: Western Energy Supply and Transmission

Associates Comment ID:

22245

Comment: – WEST urges EPA to take appropriate care in characterizing the risks of CO2 geologic storage under the UIC program. As we commented above, a successful national CO2 emissions abatement program will necessarily need to rely heavily upon development of and public support for CCS. By overly burdening the detail of site characterization and UIC of CO2 risks related to given sites under consideration, EPA could inadvertently and inappropriately stigmatize CCS, particularly if it heads off into an unwarranted categorization of CO2 as a pollutant or a hazardous waste. Such excessive focus on risk or inappropriate characterization would imply liability risk that would chill further development of critically needed CCS under a climate change program. WEST Associates believes EPA can develop site characterization regulations that minimize potential burdensome regulations based on known potential site characteristics as discussed in these comments immediately below.

Response: EPA believes that a demonstration to the public that extensive data have been collected and evaluated would likely improve confidence in the project and help address public questions and

concerns.

EPA recognizes that many CO2 streams may be relatively pure, and research indicates that the estimated amounts of impurities in a CO2 stream are likely to be low. However, EPA believes that owners or operators of GS wells must characterize their CO2 stream as part of their permit application, as required at §146.82(a)(7). This information can help the Director determine the potential for geochemical reactions between the injectate (CO2) and the host geologic formations, which could result in the plugging of pore spaces or the dissolution of formation minerals.

Since the GS rule, at §146.81(d), excludes CO2 streams that meet the definition of a hazardous waste under 40 CFR part 261, if the injectate is determined to meet the definition of a hazardous waste under RCRA, injection may only occur in a Class I hazardous waste injection well.

Commenter Name: Kevin Wanttaja Letter ID: 0248 Commenter Organization: Western Energy Supply and Transmission

Associates Comment ID:

22246 Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards)

Comment: – EPA should apply a tiered set of site characterization requirements based on demonstrable and known site characteristics. For example, potential sites that are deep saline formations located more than one kilometer below the surface are generally recognized as among the most favorable and secure site options for assuring public safety.[FN1] If such sites do not have a USDW aquifer located between it and the ground surface above, a more streamlined regulatory site characterization and risk review may be appropriate. On the other hand, an example of a potential site that may require a more rigorous sitecharacterization and risk assessment are "sole source aquifers" which are aquifers that are a sole supply of water for a region and are critically important to protect. Some stakeholders may assert that there should be no CO2 storage above or below a sole source, aquifer. However, such a restriction would essentially prohibit storage in many western areas. Rather, a better approach would allow EPA to permit UIC Class VI wells in areas where it can be shown that there are sufficient caps and protections to prevent the migration of CO2 in overlying aquifers, even in proximity of aquifers designated as sole source. An early detection-monitoring program could be established to provide sufficient opportunity to mitigate any unlikely release of CO2 from the geologic storage unit. Approaches like this illustrate how EPA can streamline UIC regulations for site characterization and permit UIC Class VI wells that first and foremost protect public safety, yet reflect a workable balance in adapting site characterization and risk assessments based on criteria adaptable to unique

candidate sites.

Response: EPA believes that requiring appropriate, site-specific, site characterization by the owner or operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific geologic data will afford the greatest protection of USDWs from endangerment. EPA believes that it is important for the Director to have as much site-specific information as possible in order to make an informed decision to permit injection for GS at a specific site. This approach allows the permit writer to establish requirements considering varying site conditions eliminating the need for tiered requirements. GS in areas that may pose risks to USDWs, as assessed and identified by the owner or operator and the Director during the site selection process, would not be permitted. EPA disagrees that a tiering system for GS sites or formations isappropriate. Instead, the GS rule focuses on evaluating the suitability of each site based on sitespecific geological and operational data.

EPA adds that the final GS rule contains a provision (at §146.95) for owners or operators to apply for waivers from the requirement that injection be below the lowermost USDW. EPA believes this waiver provision will reduce potential limitations on the re-permitting of Class II wells as Class VI wells, provided they meet the requirements at §146.95 while still protecting USDWs from endangerment.

Commenter Name: James T. Sims Letter ID: 0249 Commenter Organization: Western Business Roundtable Comment ID: 22263 Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards)

Comment: EPA should consider applying a tiered set of site characterization requirements based on demonstrable and known site characteristics. For example, potential sites that are deep saline formations located one or more kilometers below the ground surface are generally recognized as among the most favorable and secure site options for assuring public safety. If such sites do not have a Underground Source of Drinking Water (USDW) aquifer located between it and the ground surface above, a more streamlined regulatory site characterization and risk review may be appropriate.

On the other hand, an example of a potential site that may require a more rigorous site characterization and risk assessment are "sole source aquifers"which are aquifers that are the sole supply of water for a region and are critically important to protect. Some stakeholders may assert that there should be no CO2 storage above or below a sole source aquifer. However, such a restriction could essentially prohibit storage in many Western areas. Rather, a better approach would allow EPA to permit UIC Class VI wells in areas where it can be shown that there are sufficient caps and protections to prevent the migration of CO2 in overlying aquifers, even in proximity to aquifers designated as sole source. An early detection monitoring program could be established to provide sufficient opportunity to mitigate any unlikely release of CO2 from geologic storage unit.

Approaches like this illustrate how EPA can streamline UIC regulations for site characterizations and permit UIC Class VI wells that first and foremost protect public safety, yet reflect a workable balance in adapting site characterization and risk assessments based on criteria adaptable to unique candidate sites.

Response: EPA believes that requiring appropriate, site-specific, site characterization by the owner or operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific geologic data will afford the greatest protection of USDWs from endangerment. EPA believes that it is important for the Director to have as much site-specific information as possible in order to make an informed decision to permit injection for GS at a specific site. This approach allows the permit writer to establish requirements considering varying site conditions eliminating the need for tiered requirements. GS in areas that may pose risks to USDWs, as assessed and identified by the owner or operator and the Director during the site selection process, would not be permitted. EPA disagrees that a tiering system for GS sites or formations is appropriate. Instead, the GS rule focuses on evaluating the suitability of a site based on site-specific geological and operational data.

EPA adds that the final GS rule contains a provision (at 146.95) for owners or operators to apply for waivers from the requirement that injection be below the lowermost USDW. EPA believes this waiver provision will reduce potential limitations on the re-permitting of Class II wells as Class VI wells, provided they meet the requirements at 146.95 while still protecting USDWs from endangerment.

Commenter Name: Kurt Waltzer Letter ID: 0250 Commenter Organization: Clean Air Task Force Comment ID: 22326 Other EPA Comment Codes and Descriptions: 1620 1.3.2 Induced seismicity

Comment: Seismicity

Naturally occurring seismicity has been cited as an area of concern for geologic sequestration of CO2. We do believe that seismicity merits diligent treatment both in the regulations and in project operation, but we see no need for a blanket ban of sequestration in seismically active areas. Although some sites - especially ones near major active faults - would not be advisable for injection, there are plenty of other sites in seismically active areas that would make excellent candidates for safe and effective sequestration. Moreover, tools to measure, predict and design against the effects of seismic activity are

available.Nature has proven its ability to retain fluids trapped in the subsurface in seismically active areas in many instances over hundreds of millions of years, even in highly tectonically active regions of the country such as California. The potential for slippage for faults to create leakage pathways to USDWs or the surface can be managed and effectively minimized through careful siting and operational design using well-established tools and methods. The regulations should ensure that suitable sites are selected, while high risk areas, such as those near major, non-sealing faults or those that demonstrate frequent activity, are rejected. The most likely potential CO2 leakage paths would be injection wells, and not faults. However, these can be designed to prevent leakage and to be resilient to earthquakes.

We regard a ban on sequestration in seismically active areas unwarranted. We do however believe that additional diligence is required in site characterization and selection in such areas. The requirement in §146.82(c)(3) should be modified

as follows:

Response: EPA agrees that GS should not be banned in any type of environment or geologic setting and believes that decisions about seismic risk should be made on a site-specific basis. The Class VI requirements to properly characterize, permit, operate, and monitor a GS project are designed to ensure that, where GS is employed, it is done in a manner that protects USDWs from endangerment. These requirements include site characterization during which owners or operators must submit information about the seismic history of and seismic sources near a proposed GS site, as well as data on known or suspected faults in the AoR, geomechanical information on fractures, stress, ductility, rock strength, and in situ fluid pressures within the confining zone as specified in §146.82(a)(3). This information is evaluated by the Director in conjunction with information about well construction, operation, monitoring, post-injection site care, and other site-specific information. The Director determines suitability of a potential project site for GS. Sites with the potential for reopening or reactivation of faults or unacceptable seismic risk that could otherwise interfere with containment would not be suitable for GS sites –as owners or operators seeking to inject CO2 for GS at such sites would not be able to demonstrate USDW protection from endangerment.

EPA acknowledges that wells in the AoR are potential leakage pathways, and the GS rule contains rigorous provisions for both injection well construction at §146.86 and corrective action on active or abandoned wells located in the AoR at §146.84.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24857 Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions

Comment: EPA Proposal: Confining zone means a geologic formation, group of formations, or part of a formation stratigraphically overlying the injection zone that acts as

a barrier to fluid movement.

GWPC Recommendations: Confining zone means a geological formation, group of formations, or part of a formation that is capable of limiting fluid movement from an injection zone.

Rationale: The current UIC program definition of confining zone is preferable to the proposed definition. There are no special circumstances for CO2 streamsthat warrant a change

Response: EPA acknowledges the comment and the final rule retains this text as proposed. EPA believes that the definitions used for injection zone and confining zone for Class VI GS are appropriately tailored to address the unique risks and challenges posed by GS of CO2 streams.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24859 Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions

Comment: GWPC Recommendations: "Fault means a surface or zone of rock fracture along which there has [or has not] been displacement."

Rationale: Add definition of fault to clarify use in other provisions. This is

the current definition with the insertion of the words "or has not" before displacement to recognize that faults can exist where there has been no displacement.

Response: Based on its evaluation of all public comments and input on the proposed rule and NODA and Response to Comments EPA has made many revisions to the GS Rule. See the final rule and the discussion of site characterization in the preamble for further discussion on EPA's final approach. EPA does not define "fault" but defines "transmissive fault or fracture." EPA has retained the proposed definition, which is the same as the existing definition at §148.2, to address transmissive faults and fractures that extend beyond the confining zone.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24867 Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions

Comment: EPA Proposal: Transmissive fault or fracture means a fault or fracture that has sufficient permeability and vertical extent to allow fluids to move between

formations.

GWPC Recommendations: Transmissive fault or fracture means a fault or fracture that has sufficient permeability and vertical extent to allow fluids to move beyond the confining zone.

Rationale: Recommends changing "between formations" to "beyond the confining

zone." The term between formations is insufficient as it could also include multiple zones within a injection zone.

Response: EPA has retained the proposed definition, which is the same as the existing definition at §148.2, to address transmissive faults and fractures that extend beyond the confining zone.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24870 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: EPA Proposal: (c) The area of review based on modeling, using data obtained during logging and testing of the well and the formation as required byparagraphs (l), (r), and (s) of this section;

GWPC Recommendations: (c) A map delineating the area of review based upon modeling, using all available data including data available from any logging and testing of wells within the area of review.

Rationale: Is this supposed to be a map, a tabular display, a cross section or series of cross sections etc... This appears to be related to a condition where a well is already drilled. This does not align with requesting information to receive a permit.

Response: EPA recognizes that information necessary for an area of review may not be available until after a well has been drilled and formation testing can occur. EPA revised §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)) including The final area of review based on modeling, using data obtained during logging and testing of the well and the formation §146.82(c)(1).

Based on its evaluation of all public comments and input on the proposed rule and NODA and Response to Comments EPA has made many revisions to the GS Rule. See the final rule and the site characterization discussion in the preamble for further discussion on EPA's final approach.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24873 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: EPA Proposal: (6) Geologic and topographic maps and cross sections illustrating regional geology, hydrogeology, and the geologic structure of the local area.

GWPC Recommendations: Support the EPA language.

Response: EPA acknowledges the comment and the final rule retains the text as proposed.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24874 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(e)

EPA Proposal: (e) A tabulation of all wells within the area of review which penetrate the injection or confining zone(s). Such data must include a description of each well’s type, construction, date drilled, location, depth, record of plugging and/ or completion, and any additional information the Director may require;

GWPC Recommendations: (e) A compilation of all artificial penetrations within the area of review which penetrate the injection or confining zone(s). Such datamust include a description of each well’s type, construction, date drilled, location, depth, record of plugging and/ or completion, and any additional information the Director may require;

Rationale: The GWPC felt that the term compilation was more appropriate than tabulation because tabulation as tabulation implies a spreadsheet while compilation can take numerous forms.

Response: EPA used the term tabulation in the final rule because it is the same term used in the same requirement for other well classes; and, the regulated community and permitting officials are familiar with existing terminology.

Based on its evaluation of all public comments and input on the proposed rule and NODA and Response to Comments EPA has made many revisions to the GS Rule. See the final rule and preamble for further discussion on EPA's final approach.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24875 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: EPA Proposal: (f) Maps and stratigraphic cross sections indicating the general vertical and lateral limits of all USDWs, water wells and springs within the area of review, their positions relative to the injection zone(s) and the direction of water movement, where known;

GWPC Recommendations: (f) Maps and stratigraphic cross sections indicating the general vertical and lateral limits of all USDWs, the location of water wells and perennial springs within the area of review, their positions relative to the injection zone(s) and the direction of water movement, where known;

Rationale: Clarification: Use of the term perennial before springs will prevent a requirement to list very minor, intermittent springs which are not hydrologically significant.

Response: EPA acknowledges the comment; however, the final rule does not reflect the suggested edit. The Agency uses the term “springs” in the site characterization requirements for other classes of wells (see §146.70 (a)(2)) and the term is familiar to the regulated community and permitting officials. EPA adds that characterization will be site-specific, and owners or operators are encouraged to discuss the site with the Director as data are collected to identify thresholds for certain types of data.

Based on its evaluation of all public comments and input on the proposed rule and NODA and Response to Comments EPA has made many revisions to the GS Rule. See the final rule and preamble for further discussion on EPA's final approach.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24876 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rulelanguage; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: EPA Proposal: (g) Baseline geochemical data on subsurface formations, including all USDWs in the area of review;

GWPC Recommendations: (g) Compilation of available baseline geochemical data on the proposed injection zone and nearest adjacent porous and permeable formation to the confining zone, existing utilized water supply aquifers and any other USDWs designated by the Director.

Rationale: It will be unduly burdensome to address "all USDWs" in some contexts. This revision allows for more appropriate focusing on those USDWs designated by

the Director.

Response: EPA believes that identifying and mapping all surrounding USDWs near an injection well, as specified at §146.82(a)(5), is necessary to ensure protection of all USDWs from endangerment. The purpose of the UIC requirements (including those for Class VI wells) is to ensure the protection of USDWs from endangerment, which are defined based on total dissolved solids (TDS) content, not their location or depth (40 CFR §144.3).

EPA adds that knowing the number, location and depth of USDWs near an injection well will generate baseline regional information, support development of an effective testing and monitoring plan, and enhance owner or operator and Director understanding of the site. This requirement is common to all injection well classes.

Based on its evaluation of all public comments and input on the proposed rule and NODA and Response to Comments EPA has made many revisions to the GS Rule. See the final rule and preamble for further discussion on EPA's final approach.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24878 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Rule Provision: 146.83

EPA Proposal: Minimum criteria for siting

(a) Owners or operators of Class VI wells must demonstrate to the satisfaction of the Director that the wells will be sited in areas with a suitable geologic system. The geologic system must be comprised of:

(1) An injection zone of sufficient areal extent, thickness, porosity, and permeability to receive the total anticipated volume of the carbon dioxide

stream;

GWPC Recommendations: Support the proposed EPA language.

Rationale: Agree with EPA’s rationale.

Response: EPA acknowledges the comment and the final rule retains the text at §146.83(a) asproposed.

Commenter Name: Lori Mathieu Letter ID: 0283 Commenter Organization: Connecticut Department of Health Comment ID: 25297

Comment: 2: The proposed rules should be limited in the scope of its geographic coverage to areas that provide the greatest potential for sequestration of Carbon Dioxide, in terms of both the amount of sequestered and storage suitability.

Response: EPA believes that a detailed geological site characterization (required under §146.82) is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for theunique nature of injecting large volumes of CO2 into a variety of geological formations for longterm storage. However, regardless of the history of the site, the owner or operator must provide to the Director extensive information demonstrating the adequacy of the site to contain the CO2 (§146.82) and ensure protection of USDWs from endangerment.

Commenter Name: Anonymous7 Letter ID: 0288

Comment ID: 25136

Comment: COMMENT ON CARBON SEQUESTRATION

Geology, like hydrology is a science of averaged parameter values. Whendetermining lithologic properties (e.g.. transmissivity, thickness, threedimensional position, etc.) of a geologic stratum, scientists estimate these properties based on collection of data at a small number points selected from an infinite number of possible points. The more deeply buried the stratum, the greater the cost of data collection and, so, the number of data points tends to diminish with depth. There is no way to know how representative the collected data are of a geologic stratum.

As an example, imagine driving down a road at 60 mph and hitting a hole in the highway. In 20 million years from now, that highway likely will be buried under

hundreds of feet of sediment. If a dozen test holes are drilled from the land surface, though the highway roadbed, the chance that that hole would be intersected is minuscule, yet that hole in the roadbed may be the most important feature of the highway.

Not all data are collected from drilling cores, there also are temperature data, geophysical data, etc. An uncertainty analysis is performed to provide a sense of how reliable the modeling results are, but the bottom line" is that the "weak links" in the protectiveness of a confining unit are still likely to be unknown.While this lack of knowledge is not a lethal blow to modeling for, say, watersupply, these weak links can lead to serious consequences where the purpose is modeling the injection of supercritical CO2 fluids.

When we think of very deep strata that are, say, thousands of feet below land surface, we take some "comfort" in their depth. We take this comfort, becauseit's difficult to imagine that, absent a deep mappable fault, a fluid rupturing a very deep confining layer is likely to reach the land surface. However, where injection strata and confining units are shallower, our level of comfort decreases, and rightly so. It is because of the lack of sufficient data to accurately define the nature of the subsurface, that EPA needs to take a protective approach to options for: 1) injecting into formations in or above the lowermost USDW, 2) injecting below the lowermost USDW when that USDW is "relatively" shallow, and 3) injecting into a formation overlain by a brittle confining layer, unless that confining layer is very deep.

Response: EPA agrees that permitting decisions regarding GS sites must account for a large amount of site-specific information. For this reason, the GS regulation requires the owner or operator to submit data about the site, including information on the porosity, permeability, mineralogy, and geochemistry of the targeted injection and confining zones. Operators must also present information on the compatibility of the CO2 stream with fluids in the injection zone and minerals in both the injection and the confining zone(s), as determined through the formation testing program and on the compatibility of the CO2 with the materials used to construct the well, as required at §146.82(c)(3).

Commenter Name: John McManus Letter ID: 0294 Commenter Organization: American Electric Power Comment ID: 25312 Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions

Comment: 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 fluid movement from an injection zone."

Response: EPA acknowledges the comment and disagrees that the definition of confining zone is too strict. EPA clarifies that §146.83(a) requires that any GS project must have at least one confining zone (i.e., impermeable layer) between the injection zone and the lowermost USDW. EPA further believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation.

Commenter Name: Scott Anderson Letter ID: 0510 Commenter Organization: Environmental Defense Fund Comment ID: 21219

Comment: I want to especially note some strengths of the rule that relate to brine displacement. Protecting USDWs from displaced formation fluids, is just as important as protecting USDWs from injected CO2. And EPA clearly realizes this, and we're pleased.I want to read these sections into the record or not, make a, maybe if I can do it quickly enough. We are pleased with Section 146.83, requires a confining zone that confines both CO2 and displaced formation fluids.

Response: EPA acknowledges the comment. EPA's goal is developing standards for GS wells in order to ensure the protection of USDWs from endangerment. The final rule requires that any GS project must have at least one confining zone (i.e., impermeable layer) between the injection zone and the lowermost USDW (§146.83(a)).

Commenter Name: Scott Anderson Letter ID: 0510 Commenter Organization: Environmental Defense Fund Comment ID: 21227

Comment: We believe that, that there should be a provision that prohibits interference among projects. Eventually, if sequestration becomes a big enough industry we would foresee a need for basic scale of regional management.

Between now and then we think it's important to nip problems in the bud, and we suggest that a new project not be allowed to interfere with an existing project in terms of the pressure fronts overlapping or other types of interference unless a finding is made that such a overlap doesn't degrade the effectiveness of either project. So then a rule like that would force people to space projects in a way that is proper.

Response: EPA believes that the extensive requirements for geologic site characterization (at §146.82), AoR evaluation (§146.84), and testing of the well during drilling (§146.87) are appropriate to ensure that permitting authorities have the necessary information to evaluate whether a specific site will allow safe injection of CO2. EPA adds that submittal and review of monitoring data (as required at §146.90) and the AoR reevaluation process (§146.84(e)) will provide an opportunity for an ongoing review of the site and a dialogue between the Director and the owner or operator to ensure that the project is being operated in a manner that protects USDWs from endangerment. EPA believes that any natural gas storage operations would be found in site characterization as would any

faults or fractures.

Commenter Name: Olon Plunk Letter ID: 0536 Commenter Organization: Xcel Energy Comment ID: 21377 Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: In the meantime, I would like to offer some general observations. Having been through this effort to locate and prove up the acceptability of a CO2 sequestration site for a large commercial scale project, Excel believes the topics EPA would require permit applicant to address in its proposed rules are appropriate and important. For example, we believe the best technical expertise should be brought to bear in the first studying and then submitting documentation concerning site and formation geology, hydro-geology, faults, fractures, injectivity, existing wells and so on.

Response: EPA acknowledges the comment and agrees on the importance of the required permit information set in §146.82. EPA believes that the extensive requirements for geologic sitecharacterization at §146.82 are appropriate to ensure that permitting authorities have the necessary information to evaluate whether a specific site will allow safe injection of CO2.

Commenter Name: Olon Plunk Letter ID: 0536 Commenter Organization: Xcel Energy Comment ID: 21378 Other EPA Comment Codes and Descriptions: 3800 2.3 Proposed Injection Well Construction Requirements (40 CFR 146.86); 4000 2.4 Proposed Injection Well Operating Requirements (40 CFR 146.88); 5000 2.8 Proposed Well Plugging and Post-Injection Site Care Requirements

Comment: We believe there must be suitable CO2 injection plans backed by seismic surveys, multi dimensional modeling simulations and formation testing.

We recognize the overriding importance of well design and construction that assures well integrity. We believe there must be a sound operations management program including appropriate monitoring and corrective actions that are prepared and implemented by experts in the field.

We recognize both the local and national interest in providing effective post injection site care and closure and demonstrating adequate financial responsibility for these activities. While agreeing with supporting all of these important program elements, I would like to add a few words of caution.

Response: EPA acknowledges the comment. The GS requirements are designed to ensure protection of USDWs from endangerment by requiring that injection wells are permitted, sited, constructed, operated, monitored, and plugged in a manner that does not endanger USDWs. Appropriately designed and constructed wells are necessary to prevent endangerment to USDWs and maintain integrity of the well throughout the lifetime of a GS project. This is the foundation of the requirements for construction and pre-operational testing of Class VI wells at §§146.86 and 146.87.

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in evaluating this information. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in evaluating this information. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

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

### Individual Comments

Commenter Name: Michael H. Cochran Letter ID:

0108 Commenter Organization: Bureau of Water, Division of Environment, Kansas Department of Health & Environment (KDHE) Comment

ID: 21964

Comment: 146.83 (a): Need to include without initiating or propagating fractures in the injection in addition to the confining zone.

Response: EPA acknowledges the importance of selecting GS sites with confining zones that are free of transmissive faults and fractures but disagrees that the rule should prohibit fracturing within the injection zone. EPA believes that, in some circumstances, fracturing is necessary (i.e., in association with an approved stimulation program) to improve wellbore and formation injectivity. EPA clarifies that all stimulation for GS must be reported to the Director for approval 30 days in advance of such activities, pursuant to requirements at §146.91(d)(2).

Commenter Name: Leslie Savage Letter ID: 0122 Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24768 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: (2) A confining zone(s) that is free of transmissive faults or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide stream and displaced formation fluids and allow injection at proposed maximum pressures and volumes without initiating or propagating fractures in the confining zone(s) ; and

{Redundant. Repeats definition of "confining zone." Also, implies that the confining zone cannot have a single fracture, no matter how small. Much more stringent than for Class I hazardous wells.}

Response: EPA believes that the plural for injection zone(s) should be retained in the Final Rule in recognition of the fact that characterizing more than one injection zone may be necessary at some GS sites. EPA believes that in some geologic settings, the presence and identification of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These formations could further impede vertical fluid movement, allow for pressure dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection of USDWs from endangerment. While other countries may not require such additional protection, EPA believes that providing the Director this additional discretion is an important element of assuring that GS activities will not endanger USDWs.

Commenter Name: John Hanger Letter ID: 0130 Commenter Organization: Pennsylvania Dept. of Env. Protection Comment ID: 21502

Comment: Proposed Geologic Siting Requirements -The proposed regulations should better express the need for characterizing the number, location, and depth of "underground sources of drinking water." Specifically, Pennsylvania recommends the addition of a subsection under "Geologic Siting Requirements" that calls for a hydrogeologic characterization of USDWs in the area of review. Although a number of technical requirements for such a characterization are presented in the Technical Support Document,"Geologic CO2 Sequestration Technology and Cost Analysis," such visibility is not present in the proposed rule itself. The depth and capacity of the regional groundwater system should be established in this characterization, along with other required details described in the Technical Support Documents. Groundwater flow directions and approximate water budgets to estimate deep components of flow will help to assess any injection well impacts to USDWs. Fracturing and faulting in context with the regional groundwater system should be a part of the hydrogeologic characterization. This would include an uncertainty analysis of current knowledge for the area.

Also, consideration should be given for a recommendation of scales for maps and cross sections. Scales should be sufficient to provide enough detail for the "detailed geologic assessment."

-The definition and criteria to ‘show or demonstrate secondary containment of the reservoir’ does not make sense for PA geology. EPA should allow for demonstration approaches that are flexible to regional geology.

Response: EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in evaluating this information. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Richard Driggans Letter ID: 0145 Commenter Organization: Tennessee Valley Authority Comment ID: 23150

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

As a related matter, at least for the near future, siting a fossil-fueled plant that utilizes GS near a sole-source aquifer should only be considered where the infrastructure is in place for transporting supercritical CO2 to a distant injection well location. Because a large portion of the Nation’s fleet of fossil-fueled generating facilities were sited and built without consideration of CCS, there are considerable space, water supply, geologic, seismic, and financial constraints for retrofitting many existing facilities with this technology. Although the proposed rule does not require facilities to capture and/or sequester CO2, promulgation of this rule should acknowledge that GS of CO2 will not be suitable at a large number of existing facilities and may be most applicable for new-generation facilities that are properly sited a priori

for CCS.

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

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

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

Commenter Name: Kenneth Alexander Letter ID: 0146 Commenter Organization: Old Dominion Electric Cooperative (ODEC) Comment ID: 21710 Other EPA Comment Codes and Descriptions: 2100 1.6 Target Geologic Formations for GS

Comment: 3.EPA should not automatically exclude placement of wells in pmiicular geologic tructures. The Final Rule should leave the door open for a range of injection sites and methods provided the owner or operator can show that the injection and storage will be protective of Underground Sources of Drinking Water (USDWs).

Response: The final rule does not preclude injection into any formations or types of injection sites provided that the wells meet the final GS rule requirements. The purpose of the GS regulation is to ensure that injection of CO2 for GS is conducted in a manner that is protective of USDWs. This includes appropriate site characterization and identification of geologic formations that are amenable to injection of potentially large volumes of CO2 for long-term storage. The regulation provides flexibility to owners or operators to select appropriate sites and target formations (under §146.82), well construction specifics (under §146.86), and injection procedures provided the owner or operator can demonstrate that the injection and storage will not endanger USDWs and that minimum requirements for the site are met.

EPA is using an adaptive approach to regulating GS under the UIC Program. Even after finalization of the GS regulation, the Agency plans to collect and review data every six years on GS projects to determine whether the appropriate amount and types of information and appropriate documentation are being collected, and to determine if modifications to the requirements are appropriate or

necessary.

Commenter Name: James Dooley Letter ID: 0156 Commenter Organization: Joint Global Change Research Institute, Pacific Northwest National Laboratory Comment ID:

22630

Comment: Demonstrating Sufficient CO2 Storage Capacity

Page 43536. The draft Class VI rule states that the applicant is required to identify "An injection zone of sufficient areal extent, thickness, porosity, andpermeability to receive the total anticipated volume of the carbon dioxide stream." This is a good requirement but it is incomplete. There needs to be some time element here. That is the proposed rule needs to address "total anticipated volume" over what period of time. There is no need to establish an arbitrary quantitative figure here (e.g., "over 40 years"). Rather the calculation could be predicated on the expected lifetime of the facility, the duration of the injection permit, etc. It would be prudent to modify this sentence to explicitly communicate that the USEPA was not considering "the total anticipated volume of the carbon dioxide stream" for any given year of operations.

Response: The Agency agrees with the commenter, in the final regulation, the owner or operator must demonstrate that the receiving formation (injection zone) is "sufficient... to receive the total anticipated volume of the CO2 stream" (§146.83 (a)(2)). In addition, the Director will also consider the owner or operator's proposed AoR and corrective action plan, in which the owner or operator must delineate, through modeling, the predicted extent of the CO2 plume over the duration of the project.

Commenter Name: Michael J. Miller Letter ID: 0168 Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22495

Comment: EPRI COMMENT #4B: The minimum siting criterion specified in §146.83(a)(2) that states the confining zone must be "free of transmissive faults or fractures" is too vague and open to interpretation by permit writers, potentially leading to inconsistent application throughout the United States. Faults and fractures are ubiquitous and quite common in deep sedimentary basins where the natural accumulation of thick sediments causes differential compaction and settling, resulting in fracturing and faulting. However, some faults and fractures are sealed or have very low transmissivity, allowing them to be present in the caprock without jeopardizing containment. Therefore, if taken literally, the language in the proposed rule could limit permitting to those sites that are totally "free" of faults and fractures, potentially eliminating numerous sedimentary basins with excellent CO2 storage potential. EPRI recommends that the EPA remove the language "free of transmissive faults or fractures" from this section of the rule and, instead, base its decision on a site-by-site demonstration of capacity and containment using data and model results provided by the applicant.

Response: EPA disagrees that the language is vague. The Agency believes that the requirement at §146.83(a)(2) that the confining zone be free of transmissive faults or fractures is appropriate for Class VI wells and is necessary to ensure containment of the injectate and that requiring the confining zone to be free of transmissive faults maximizes protection of USDWs from endangerment. Class I hazardous waste injection well operators must also meet a similar requirement that the site is free of transmissive faults or fractures; they have successfully made such demonstrations in the past. EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.Commenter Name: Michael J. Miller Letter ID: 0168 Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22497

Comment: EPRI COMMENT #4D: If EPA retains the language in the rule requiring that confining zones be free of transmissive faults and fractures, EPRI wants to point out that reliable techniques for characterizing deep faults/fractures are rudimentary. Drilling through the fault or fracture plane and hydraulically testing it to determine its local transmissivity is the most direct and reliable characterization method. EPRI is concerned about any requirement to characterize the hydraulic properties of faults cutting across confining zones because this can only be achieved by drilling through and hydraulically testing the fault, creating potential fast-flow pathways in the caprock, potentially jeopardizing

containment.

Response: While core samples obtained through drilling and hydraulic testing are direct methods to obtain such information, geophysical techniques such as seismic or electromagnetic surveys can also be used in many geologic settings to demonstrate the absence of or identify and characterize the presence of faults or fractures. At sites where deep faults (even with little or no surface expression) are present, processing and interpreting data from multiple geophysical sensing methods has been shown to detect faults better than analysis of data from individual methods (Goussev et al, 2004). Drilling through faults or fractures with appropriate well design, materials, and operation, would not result in an increase in their permeability or a decrease in CO2 containment properties of the related CO2 storage reservoir. In some cases, the use of complementary drilling and geophysical methods might provide the most dependable characterization of potential transmissive faults and fractures. EPA adds that the Director must evaluate all geologic data on the site to ensure protection of USDWs from endangerment before approving a site for a GS project.

Commenter Name: Kyle Isakower Letter ID: 0170 Commenter Organization: American Petroleum Institute Comment ID: 24156 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Rule Provision: 146.83(a)(2)

API Comments: (2) A confining zone(s) that is LATERALLY CONTINUOUS AND free of KNOWN TRANSECTING, transmissive faults or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide stream and displaced formation fluids and allow injection at proposed maximum pressures and volumes without initiating or propagating fractures in the confining zone(s); and OVER

AN AREA SUFFICIENT TO PREVENT THE MOVEMENT OF INJECTED OR DISPLACED

FLUIDS INTO A USDW;

Rationale: The proposed clarification keeps the emphasis on the non-endangerment of USDWs and limits the requirements to that which is known or can be readily

determined.

Response: The Agency believes that the requirement at §146.83(a)(2) that the confining zone be free of transmissive faults or fractures as written is appropriate for Class VI wells and is necessary to ensure containment of the injectate, and that requiring the confining zone to be free of transmissivefaults maximizes protection of USDWs from endangerment. Class I hazardous waste injection well operators must also meet a similar requirement that the site is free of transmissive faults or fractures; they have successfully made such demonstrations in the past. EPA adds that the Director must evaluate all geologic data on the site to ensure protection of USDWs from endangerment before approving a site for a GS project.

Commenter Name: Frederick R. Eames Letter ID: 0178 Commenter Organization: CCS Alliance Comment ID: 23851

Comment: 2. Geologic Siting Requirements

EPA's Proposed Rule includes significant technical information requirements for the geological siting of Class VI wells, including: maps and cross-sections of nearby USDWs; demonstrations of the porosity and permeability of the injection zone and subsurface formations; information on faults and fractures, including results of geomechanical studies; seismic history studies; determinations of maximum sustainable injection pressures; and geochemical data.

The geological siting requirements for Class VI wells should be reasonably balanced to ensure that EPA's goals are met. but not be so burdensome so as to deter the development of CCS projects. To this end, EPA should ensure that the information it seeks is essential to its evaluation efforts, and not unnecessarily overbroad. Proper geological siting requirements will help EPA, state actors, and owners and operators identify the risks involved so that proper additional evaluations may be made to protect human health and the snvironment and to evaluate financial and strategic risks associated with CCS projects.

Moreover, the siting requirements authorize the Director to use his discretion to require owners and operators to identify and provide additional information with respect to additional zones near the GS. Such discretion should not be unlimited. We recommend that EPA establish clearer guidelines with respect to how such discretion may be exercised to prevent unnecessary requirements.

Response: EPA believes that requiring appropriate, site-specific, site characterization by the owner or operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific geologic data will afford the greatest protection of USDWs from endangerment. EPA disagrees the requirements are too burdensome, and believes that it is important for the Director to have as much site-specific information as possible in order to make an informed decision to permit injection for GS at a specific site. EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in evaluating this information and exercising discretion. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Robert J. Finley Letter ID: 0180Commenter Organization: Illinois State Geological Survey Comment ID: 23624 Other EPA Comment Codes and Descriptions: 3100 2.1 Proposed Geologic Siting Requirements (40 CFR 146.83)

Comment: 146.83

(a)(2)

Modify this section to indicate that the confining zone is "reasonably expected" to be free of faults and fractures that are transmissive. Again, the behavior of a given fault or fracture in an area cannot be conclusively proven with respect to its impact on fluid flow except by analogy to oil field or gas storage field performance. There is no mechanism to carry out a subsurface test of a fault except possibly in the case of multiple wells opportunely place on opposite sides of a defined fault to access a transmissive unit which can be pressure pulse tested and can be isolated by packers or other equipment. Such tests (obviously) are unlikely to work in a confining zone due to its low permeability.

Response: The Agency believes that the requirement at §146.83(a)(2) that the confining zone be free of transmissive faults or fractures is appropriate for Class VI wells and is necessary to ensure containment of the injectate and that requiring the confining zone to be free of transmissive faults maximizes protection of USDWs from endangerment. Class I hazardous waste injection well operators must also meet a similar requirement that the site is free of transmissive faults or fractures; they have successfully made such demonstrations in the past. While core samples obtained through drilling and hydraulic testing are direct methods to obtain such information, geophysical techniques such as seismic or electromagnetic surveys can also be used in many geologic settings to demonstrate the absence of or identify and characterize the presence of faults or fractures. At sites where deep faults (even with little or no surface expression) are present, processing and interpreting data from multiple geophysical sensing methods has been shown to detect faults better than analysis of data from individual methods (Goussev et al, 2004). Drilling through faults or fractures with appropriate well design, materials, and operation, would not result in an increase in their permeability or a decrease in CO2 containment properties of the related CO2 storage reservoir. In some cases, the use of complementary drilling and geophysical methods might provide the most dependable characterization of potential transmissive faults and fractures. EPA adds that the Director will evaluate all geologic data on the site to ensure protection of USDWs from endangerment before approving a site for a GS project.

EPA acknowledges that some smaller fractures may not be detectable during the site characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells and sites can mitigate the potential impacts of unidentified fractures. These include limitations on injection pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible CO2 movement through high-permeability regions (i.e., faults and/or fractures) not

detected in the initial site characterization.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24330 Other EPA Comment Codes and Descriptions: 3140 2.1.4 Comments that the proposed geologicdata requirements are too stringent

Comment: 1. Site Evaluation

The preamble appears to suggest the need for an elaborate evaluation of site conditions to address concerns related to seismicity and potential geochemical interactions. In fact, however, seismicity and geochemical impacts are issues that are easily addressed in the GS context, and requirements for unnecessarily elaborate analysis would serve only to burden and impede the development of GS projects.

Concerns with respect to seismicity are frequently raised in the injection well context, but there is ample experience demonstrating that such risks are modest and easily addressed through appropriate injection pressure limitations. Similarly, geologic compatibility - while it can present issues in some contexts - is unlikely to present any serious problems in the GS context. These conclusions are confirmed by decades of experience with literally thousands Class II CO2 injection wells injecting hundreds of millions of tons of CO2.

The apparent extent of concern about geochemical compatibility is particularly hard to understand. Although it is true that injection of CO2 can be expected to lead to the formation of carbonic acid, the resulting carbonic acid is only weakly corrosive and - as experience with the injection of extremely corrosive hazardous wastes demonstrates - cannot reasonably be expected to cause any breach of containment that would endanger a USDW. The proposed rule expresses specific concern about geochemical reactions that could alter the composition of the injected CO2 stream - particularly through the mobilization of contaminants that occur naturally in the injection zone - but such concerns are essentially immaterial because the specific composition of the CO2 stream matters little as long as the CO2 stream remains confined.

Response: The Agency believes that the site characterization requirements at §146.82 are essential to proper siting of a GS well and are the foundation for a detailed understanding of the local and regional geology. Collecting and evaluating geochemical data in and around the CO2 injection zone, as required in §146.82(a)(6), serves several purposes. This baseline geochemical data can help predict geochemical reactions between the injectate, reservoir geology, and formation fluids. Such reactions can lead to dissolution and precipitation of minerals which affect formation porosity, which in turn can affect required injection pressure (Sminchak and Gupta, 2002) and transport of fluid within the formation. While the confining layer is the primary barrier to CO2 movement into a USDW, multiple barriers are important and changes in injection pressure and fluid movement may compromise those barriers. An increase in injection pressure due to reduced porosity, in particular, can lead to fracturing of the confining layer and potentially allow fluid movement outside of the injection zone. Losses in injectivity because of geochemical reactions may also require additional injection wells and further penetrations in the confining layer that can become pathways for fluid migration.

EPA disagrees with the comment that the composition of the CO2 stream is not important. Information about the composition of the CO2 stream informs decisions about the appropriate design and construction of the well, the potential for adverse mineral reactions in the subsurface geologic formations, and appropriate testing and monitoring parameters.EPA disagrees that injectivity is not an important consideration. While increasing storage capacity is not the intent of the UIC requirements, EPA believes that maximizing the amount of CO2 that can be injected through a single well may reduce the need for additional injection wells, which reduce the potential for unacceptable fluid movement and improve USDW protection from endangerment.

Finally, EPA disagrees that consideration of local and regional seismicity is not important. The site characterization provisions in the GS rule, including a review of the local and regional geology, and detailed review of any known or potential seismically active terrain in the vicinity of a proposed GS site are necessary to minimize the potential for induced seismic events or the reactivation of faults, which are a known potential risk associated with injection and are addressed in all aspects of the UIC regulations.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24422 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Rule Provision: 146.83(a)(2)

Proposed CCS Group Recommendations: (2) A confining zone(s) that is LATERALLY CONTINUOUS AND free of KNOWN TRANSECTING, transmissible faults or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide stream and displaced formation fluids and allow injection at proposed maximum pressures and volumes without initiating or propagating fractures in the confining zone(s); and OVER AN AREA SUFFICIENT TO PREVENT THE MOVEMENT OF INJECTED OR DISPLACED FLUIDS INTO A USDW;

Basis for CCS Group Comments: The proposed clarification keeps the emphasis on the non-endangerment of USDWs and limits the requirements to that which is known or can be readily determined.

Response: The Agency believes that the requirement at §146.83(a)(2) that the confining zone be free of transmissive faults or fractures is appropriate for Class VI wells and is necessary to ensure containment of the injectate and that requiring the confining zone to be free of transmissive faults maximizes protection of USDWs from endangerment. EPA believes that the text regarding propagation of faults and fractures is important to avoid the potential for fluid movement and to ensure that injection is at appropriate pressures. Class I hazardous waste injection well operators must also meet a similar requirement that the site is free of transmissive faults or fractures; they have successfully made such demonstrations in the past. While core samples obtained through drilling and hydraulic testing are direct methods to obtain such information, geophysical techniques such as seismic or electromagnetic surveys can also be used in many geologic settings to demonstrate the absence of or identify and characterize the presence of faults or fractures. EPA adds that the Director will evaluate all geologic data on the site to ensure protection of USDWs from endangerment before approving a site for a GS project.

Commenter Name: Andy Horn Letter ID: 0196 Commenter Organization: Colorado Ground Water Association (CGWA) Comment ID: 23925

Comment: Issue 5. The regulations should specifically address the potential for migration of injected CO2 in different types of groundwater reservoirs.The proposed rule lacks specificity with respect to the manner in which a proposed operation will demonstrate that there is a suitable geologic trap for the injected CO2 and that the integrity of that trap will be perpetual. Demonstrating a pre-existing geologic structure capable of trapping CO2 and demonstrating that the complex geochemical reactions in and adjacent to the GS reservoir will not compromise the reservoir’s integrity are critical. However, the rule simply presumes such a demonstration can be made and provides no methods or criteria to be met in developing the demonstration.

Supercritical CO2 is essentially a light non-aqueous phase liquid (LNAPL) capable of dissolving into water and also into which water can dissolve. A porous medium, such as the strata comprising a GS reservoir, is about eight times as permeable to supercritical CO2 as to water due to the low viscosity of the supercritical CO2. The supercritical CO2 will rise through a water-bearing reservoir as a buoyant fluid, independent of injection pressure gradients. When the supercritical CO2 reaches an impermeable stratum, that buoyancy will cause it to continue to move updip along that stratum until it encounters a stratigraphic or structural trap or permeability change sufficient to preclude further migration, i.e., a trap. The CO2 will continue to migrate into that trap, displacing the native water. If the injected volume is greater than the trap’s available volume the excess CO2 will "spill" from the trap and continue to migrate laterally and vertically along the upper confining stratum until it either finds another trapping configuration or reaches temperature and pressure where it reverts from supercritical to gaseous CO2.

Finding trapping structures in the subsurface is a non-trivial exercise. Every dry oil or gas exploration hole was drilled because a geologic investigation appeared to establish presence of a trap for buoyant hydrocarbons. While some dry holes may result from a missing source of petroleum, overwhelmingly the cause is that the postulated trap did not exist, either because the trapping structure was absent or due to natural leaks through the confining units through which the oil or gas escaped. These technical problems associated with finding petroleum LNAPL traps are directly analogous to finding traps capable of holding CO2 in perpetuity. There are, however, major issues for CO2 sequestration not borne by hydrocarbon exploration.

One issue is geologic trap integrity. Drilling can verify the postulated trapping geometry for either activity. If the confirmed configuration does not contain petroleum, the configuration is likely to be leaky. There is no corresponding way to establish the integrity of the seals in the case of exploration for CO2 traps.

Another issue relating to GS reservoir siting evaluation is economics inherentin the process. There is significant financial incentive to find the petroleumbearing trap, and that incentive can bear the burden of multiple failures. For the operator of a large point-source of CO2, sequestration of CO2 is a cost to be minimized as it does not result in a profit opportunity. Without detailed, explicit rules establishing how to prove a trap before attempting GS, the existence of functional traps will be simply presumed until lack of theirexistence or integrity is proven by failure.

The problem of finding and proving a sequestration trap for CO2 can be minimized by requiring sequestration in depleted petroleum traps, however there may not be enough depleted oilfields to contain a significant amount of CO2 and the presence of unsuitably constructed or abandoned wells can compromise integrity

of a GS reservoir.

Response: EPA developed the GS regulations to address the potential for migration of injected CO2 into different types of groundwater reservoirs to prevent endangerment of USDWs. The rule requires the owner or operator to provide extensive information to demonstrate to the Director (§146.82) that the CO2 will be contained within the injection formation. Because of the site-specific nature of GS and the variety of geologic settings in which GS may be employed, the regulation does not provide a specific list of information to be provided.

Owners or operators seeking a permit for GS wells must provide the appropriate information, regardless of whether there is a cost incentive for proper site characterization. If the information submitted is not adequate to support a determination that sufficient traps exist to contain the CO2 and ensure USDW protection, the Director may request additional information (under §146.82(a)(21)), or ultimately decline to issue a permit.

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24652 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Rule Provision: 146.83(a)(2)

Anadarko Petroleum Corporation (APC) Comments: (2) A confining zone(s) that is LATERALLY CONTINUOUS AND free of KNOWN TRANSECTING, transmissive faults or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide stream and displaced formation fluids and allow injection at proposed maximum pressures and volumes without initiating or propagating fractures in the confining zone(s); and OVER AN AREA SUFFICIENT TO PREVENT THE MOVEMENT OF INJECTED OR DISPLACED FLUIDS INTO A USDW;

Rationale: The proposed clarification keeps the emphasis on the non-endangerment of USDWs and limits the requirements to that which is known or can be readily

determined.

Response: The Agency believes that the requirement at §146.83(a)(2) that the confining zone be free of transmissive faults or fractures is appropriate for Class VI wells and is necessary to ensure containment of the injectate and that requiring the confining zone to be free of transmissive faultsmaximizes protection of USDWs from endangerment. EPA believes that the text regarding propagation of faults and fractures is important to avoid the potential for fluid movement and to ensure that injection is at appropriate pressures. Class I hazardous waste injection well operators must also meet a similar requirement that the site is free of transmissive faults or fractures; they have successfully made such demonstrations in the past. While core samples obtained through drilling and hydraulic testing are direct methods to obtain such information, geophysical techniques such as seismic or electromagnetic surveys can also be used in many geologic settings to demonstrate the absence of or identify and characterize the presence of faults or fractures. EPA adds that the Director must evaluate all geologic data on the site to ensure protection of USDWs from endangerment before approving a site for a GS project.

Commenter Name: Darrick Eugene Letter ID: 0223 Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23957

Comment: Point #2: The absence of a systemfor qualifying geologic storage sites. Fundamentally, the TxCCSA believes that hydrocarbon related geologic storage is one of the important avenues by which the next generation of energy production will move forward. CO2 occurs naturally in the subsurface and is no stranger to geologists who attempt to understand fluid migration and subsurface accumulations. The fact that CO2 can be trapped in subsurface formations for geologic times is known and accepted; and more of these locations will undoubtedly be found. This brings us to another concern with the Proposed Rule involving the absence of a system to qualify sites for CO2 injection (i.e. a site permitting framework). We feel this it is necessary to rate sites for injection security. There is an evolving [FN3] framework which could form the basis for qualifying or rating sites. We believe that such a framework is necessary for the insurance industry that will oversee injection in non-hydrocarbon related geologic storage applications.

3 See the work of Dr. Steven Bryant, director of the Geologic CO2 Storage Joint Industry Project in the Center of Petroleum and Geosystems Engineering at the University of Texas.

Response: EPA disagrees that a single process or framework for evaluating all GS sites or formations is appropriate. Instead, the GS rule focuses on evaluating the suitability of each site basedon site-specific geological and operational data. EPA believes that requiring appropriate, sitespecific, site characterization by the owner or operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific geologic data will afford the greatest protection of USDWs from endangerment. EPA believes that it is important for the Director to have as much site-specific information as possible in order to make an informed decision to permit injection for GS at a specific site. This approach allows the permit writer to establish requirements considering varying site conditions eliminating the need for tiered requirements. GS in areas that may pose risks to USDWs, as assessed and identified by the owner or operator and the Director during the site selection process, would not be permitted.

Commenter Name: Andrew Duguid Letter ID: 0226 Commenter Organization: Schlumberger Carbon Services Comment ID: 24025 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Proposed Rule: (i) Be based on detailed geologic data collected to characterizethe injection zone, confining zone and any additional zones; and anticipated operating data, including injection pressures, rates and total volumes over the proposed life of the geological sequestration project;

Schlumberger Suggested Revision: (i) Be based on detailed geologic data collected to characterize the injection zone, confining zone(s), monitoring zones and any additional zones; and anticipated operating data, including injection pressures, rates and total volumes over the proposed life of the geological sequestration project;

Schlumberger Rationale: We feel that if there are secondary confining units that they should be included in the site model along with any transmissive zones between the primary and secondary confining units.

Response: EPA agrees that all geologic data about the site, including confining zone(s) and transmissive zones, should be addressed in the model but disagrees that the suggested revision is necessary. EPA clarifies that the AoR delineation model must be based on detailed geologic data collected to characterize the injection zone, confining zone and any additional zones (§146.84(c)(1)(i)).

Commenter Name: A. James Mayer Letter ID: 0230 Commenter Organization: A. J. Mayer International on behalf of the American Energy Security Initiative Comment ID:

21890

Comment: 7. EPA should provide for a system for qualifying sequestration sites, including qualifying geographically and geologically diverse sites for CO2 injection in non-trapping (oil/gas) applications.

Response: EPA disagrees that a system for qualifying GS sites is appropriate. Instead, the GS rule focuses on evaluating the suitability of each site based on site-specific geological and operational data. EPA believes that requiring appropriate, site-specific, site characterization by the owner or operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific geologic data will afford the greatest protection of USDWs from endangerment. EPA believes that it is important for the Director to have as much site-specific information as possible in order to make an informed decision to permit injection for GS at a specific site. This approach allows the permit writer to establish requirements considering varying site conditions, eliminating the need for tiered requirements. GS in areas that may pose risks to USDWs, as assessed and identified by the owner or operator and the Director during the site selection process, would not be permitted.

Commenter Name: Randy Joseph Letter ID: 0240 Commenter Organization: Western Organization of Resource Councils Comment ID: 23220

Comment: 2) Siting: Geologic sequestration will require a lot of wells, roads, support facilities and other development. We expect that there will be many proposals for geologic sequestration in areas that are already subject to heavy energy development. It may seem appropriate to concentrate development in areas, but we submit that the opposite may be true. Areas already impacted by oil, gas and coal development will have underground fractures and fissures that could make safe implementation of geologic sequestration a challenge.Response: EPA clarifies that it is not the intent of the GS rule to identify or set requirements for which areas may be or should be used for GS. Rather, the purpose of the rule is to ensure that where deployed, GS is conducted in a manner that protects USDWs from endangerment.

Commenter Name: Mark Bohrer Letter ID: 0241 Commenter Organization: North Dakota Industrial Commission Comment ID: 23279 Other EPA Comment Codes and Descriptions: 1220 1.1.1.1 Terminology and definitions

Comment: 146.82(a) Overlying formations needs to be defined. Geologic information should be limited to the injection and confining zones.

Response: EPA believes that a detailed geological site characterization (required under §146.82) is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for theunique nature of injecting large volumes of CO2 into a variety of geological formations for longterm storage.

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Mark Bohrer Letter ID: 0241 Commenter Organization: North Dakota Industrial Commission Comment ID: 23283

Comment: 146.83(a)1 An injection zone capable of receiving the total anticipated volume of carbon dioxide should not be an absolute requirement. The volume to be injected may be difficult to ascertain since the life of a power plant or other source may change with advances in technology or under certain economic conditions. A candidate injection zone should not be excluded if it can only serve as a sequestration zone for a portion of a project.

Response: The Agency disagrees with the commenter for asserting that there should not be an absolute requirement that the injection zone be capable of receiving the total anticipated volume of CO2. The GS rule is designed to ensure that the total volume of CO2 anticipated to be injected can be safely stored within the target injection zone. This evaluation is based on site-specific characteristics including the local geology (e.g., data on formation thickness, porosity, and permeability and the presence of confining zones). The GS injection requirements, under SDWA authority, ensure protection of USDWs from endangerment through assessment of the suitability of an injection zone (§146.83), appropriate site characterization (§146.82), and area of review evaluation (§146.84) among other requirements.

The Agency believes that this comment may be based on an assumption that Class VI injection wells will be co-located with CO2 producing facilities. While this may, in some cases, be an accurate assumption, the specifications, design, and purpose of the CO2 source/facility are not addressed bythe Class VI GS requirements.

The productivity of the CO2 source (e.g., power plant, industrial facility, etc.) is not the driver of site suitability. Rather, the acceptability of a candidate site is determined, in part, by the amount of CO2 it can receive without allowing pressures in the injection formation to build up to levels that may fracture the confining zone or cause unacceptable fluid movement. If a CO2 source produces more than a formation can hold, then once the capacity of the receiving formation is reached, any additional CO2 produced would have to be injected elsewhere.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24879 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: EPA Proposal: (2) A confining zone(s) that is free of transmissive faults or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide stream and displaced formation fluids and allow injection at proposed maximum pressures and volumes without initiating or propagating fractures in the confining zone(s); and

GWPC Recommendations: (2) A confining zone(s) that is laterally continuous and free of known transecting, transmissive faults or fractures over an area sufficient to prevent the movement of fluids into a USDW;

Rationale: Suggest using the Class I regulation for this paragraph (2) in 146.62(c) with the addition of reactivation of existing faults or fractures and

before the terms faults or fractures the word known should be added.

Response: The Agency believes that the requirement at §146.83(a)(2) that the confining zone to be free of transmissive faults or fractures is appropriate for Class VI wells and is necessary to ensure containment of the injectate and that requiring the confining zone to be free of transmissive faults maximizes protection of USDWs from endangerment. EPA believes that the text regarding propagation of faults and fractures is important to avoid the potential for fluid movement and to ensure that injection is at appropriate pressures. Class I hazardous waste injection well operators must also meet a similar requirement that the site is free of transmissive faults or fractures; they have successfully made such demonstrations in the past. While core samples obtained through drilling and hydraulic testing are direct methods to obtain such information, geophysical techniques such as seismic or electromagnetic surveys can also be used in many geologic settings to demonstrate the absence of or identify and characterize the presence of faults or fractures. EPA adds that the Director will evaluate all geologic data on the site to ensure protection of USDWs from endangerment before approving a site for a GS project.

Commenter Name: Mark Singer Letter ID: 0504 Commenter Organization: Green America Project, LLC Comment ID: 21249

Comment: Geologic sequestration operations must have capstone formations separating the injection site not just from the surface but also from soluble rock such as

limestone.

Now, there's a couple places in the, in the Federal Register where they, wherethey discussed this. But none of them discussed the effect of CO2 on the rock, they just talk about, for example, plugging pore spaces.

Response: EPA clarifies that §146.83(a) requires that any GS project must have at least one confining zone (i.e., impermeable layer) between the injection zone and the lowermost USDW. The owner or operator and the permit writer must take into account the possibility of permeable and/or soluble geology in the subsurface. The requirement focuses on isolation from the USDW in order to meet the UIC programmatic requirement to protect USDWs from endangerment.

EPA believes that plugging of pore spaces is one aspect of the interactions between CO2 and the rock that need to be addressed. Additionally, the GS regulation requires the owner or operator to submit data about the site, including information on the porosity, permeability, mineralogy, and geochemistry of the targeted injection and confining zones. Operators must also present information on the compatibility of the CO2 stream with fluids in the injection zone and minerals in both the injection and the confining zone(s), as determined through the formation testing program and on the compatibility of the CO2 with the materials used to construct the well (§146.82(c)(3)). The data can help the Director determine the potential for geochemical reactions between the injectate (CO2) and the host geologic formations, which could result in the plugging of pore spaces or the dissolution of

formation minerals.

Commenter Name: Cynthia Lane Letter ID: 0528 Commenter Organization: American Water Works Association (AWWA) Comment ID: 21387 Other EPA Comment Codes and Descriptions: 3130 2.1.3 Comments that operators should submit more (or different) geologic data than proposed

Comment: provide for a consistent application of the monitoring requirements. Another area of concern is often the lack of good records of abandoned wells that tap the very same strata used for carbon dioxide sequestration. There is a presumption that even states with oil and gas or mining operation have excellent, up to date reports and have maps indicating abandoned wells and mines. This is not always the case. Many states with extractive industries do have maps and surveys, but they are not sufficiently precise for geologic sequestration. Studies have shown that injected carbon dioxide will be able to

find the abandoned wells. These wells allow for the transmission of the carbon dioxide out of the confined aquifer into potential USDW's and then eventually to

the surface.

Response: EPA acknowledges that areas previously used for drilling for oil, gas, or minerals pose potential challenges for GS. However, regardless of the history of the site, the owner or operator must provide to the Director extensive information demonstrating the adequacy of the site to contain the CO2 (§146.82). This information includes the location of all existing or abandoned wells within the modeled AoR (§§146.82(a)(2) and 146.84(c)(2)) and the location, orientation, and properties of all known or existing faults (§146.82(a)(3)(ii)). The Director may require ground or airborne surveys to identify active or abandoned wells if there is reason to believe, based on knowledge of the site or of available data bases, that the available information is not adequate for assessing a proposed GS site (§146.84(c)(2)). The Director may also require additional surveys and tests to identify and characterize fractures. After reviewing the permit information submitted, the Director may deny the application if there is reason to believe that USDWs may be endangered.Comment Code: 3120 2.1.2 Need to identify additional confining and containment zones (seeking comment)



### Individual Comments

Commenter Name: Michael H. Cochran Letter ID:

0108 Commenter Organization: Bureau of Water, Division of Environment, Kansas Department of Health & Environment (KDHE) Comment

ID: 21969

Comment: 146.83 (b): This should not be an option, but should be required of the owner/operator. This is important in evaluating and demonstrating containment.

Response: EPA agrees with commenters that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection from endangerment. The final regulation retains the requirement at §146.83(b) which affords the Director discretion to require owners or operators to identify and characterize

additional zones.

Commenter Name: Karl R. Moor Letter ID: 0109 Commenter Organization: Southern Company, on behalf of Edison Electric Institute (EEI) Comment ID:

21995

Comment: For example, requiring a secondary containment field would create the wrong impression about the safety of carbon capture and storage, and should not be part of the final rule. Such a requirement is unprecedented in the UIC program, even for storage of hazardous wastes in Class I wells. Secondary containment fields are also unprecedented internationally: Countries where carbon capture and storage projects are currently underway - including Norway, Canada, Australia and Algeria - do not require additional containment zones, and in fact, those countries regulate CCS using existing petroleum laws. Singling out carbon capture and storage for this heightened and substantially more rigorous requirement would suggest to the public that EPA thinks geologic storage of carbon dioxide is more dangerous than the underground injection of other substances. Since EPA is the agency charged with protecting the environment, the public could be easily swayed by EPA’s apparent apprehension of carbon capture and storage as currently embodied in the proposed regulations. In order to create a regulatory scheme that fosters carbon capture and storage development and deployment, EPA should reconsider how it has characterized carbon dioxide injection - both explicitly and implicitly - in its final regulations.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commentersrepresenting states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site. While other countries may not require such additional protection, EPA believes that providing the Director this additional discretion is an important element of assuring that GS activities will not endanger USDWs.

To the comment that the geologic siting requirements could create a negative public perception, EPA believes that a demonstration to the public that extensive data have been collected and evaluated would likely improve confidence in the project and help address public questions and concerns.

Commenter Name: Doug Louis Letter ID: 0121 Commenter Organization: Kansas Corporation Commission Comment ID: 22077

Comment: KCC staff finds the concept of additional containment zones above the confining zones to be confusing and unnecessary. If the injection zone and confining zone are competent, well understood and monitored, there is no need to have a costly and unneeded system of redundant containment zones above the two. Futhermore, the term "containment zone" is not found in the definitions section nor fully explained.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

EPA clarifies that the GS rule defines confining zone as "a geologic formation, group of formations, or part of a formation stratigraphically overlying the injection zone that acts as barrier to fluid movement." (§146.81(d)).

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in making an objective decision about requiring additional confining layers. The guidance

can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Leslie Savage Letter ID: 0122 Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24735Comment: - The implied recommendation that a geologic sequestration project have more than one confining zone is much more stringent than the requirements for Class I hazardous waste injection wells.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: Leslie Savage Letter ID: 0122 Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24769 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: (b) At the Director's discretion, owners or operators of Class VI wells must identify and characterize additional zones that will impede vertical fluid movement, are free of faults and fractures that may interfere with containment, allow for pressure dissipation, and provide additional opportunities for monitoring, mitigation and remediation.

{Redundant and unnecessary. Language in definition of "confining zone."}

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: John Stormon Letter ID: 0123 Commenter Organization: Washington State Dept. of Ecology Comment ID: 23001

Comment: Containment or a caprock are critical to prevent the migration of CO2 upward into shallower USDWs. Allowing the director to require additional confining zones will allow regulators to include additional protective standards where needed and could allow use of an otherwise marginal formation for geologicsequestration.

Response: EPA agrees with the commenter that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection from endangerment. The final regulation retains the requirement at §146.83(b) which affords the Director discretion to require owners or operators to identify and characterize

additional zones.

Commenter Name: Dawn A. Thorne Letter ID:

0134 Commenter Organization: University of Utah Energy and Geoscience Institute on behalf of the Southwest Regional Partnership Comment

ID: 21654

Comment: - Section 146.83(b) "At the Director's discretion, owners or operators of Class VI wells must identify and characterize additional zones that will impede vertical fluid movement, are free of faults and fractures that may interfere with containment, allow for pressure dissipation, and provide additional opportunities for monitoring mitigation and remediation."

Response/Discussion: These zones would imply that "secondary containment" is necessary for GS. Such zones are not required for Class I hazardous waste wells, thereby giving the impression that GS is more risky than the underground storage of hazardous waste. While a "stacked system" of reservoirs and seals certainly provides additional safeguards to underground sources of drinking water (USDWs), in general, these containment zones will not be necessary in every case, especially when it can be demonstrated that seal integrity will be maintained over the life of a GS project. As stated in the proposed rule, "...their absence does not necessarily indicate inappropriateness of a GS site".

The SWP agrees with the testimony of Edison Electric Institute at the Public Hearing on September 30, 2008 (Chicago, IL), that such an additional requirement would create the perception of fear among the public. Through international and national GS pilot studies of various scales, it has been demonstrated that it is very unlikely that GS would harm human health and the environment when sited properly. The SWP would recommend that the EPA remove this section from the final rule, since detailed siting evaluation is explicitly covered in Sections 146.83(a)(1,2).

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.Commenter Name: Christine Reimer Letter ID: 0142 Commenter Organization: National Ground Water Association Comment ID: 22579

Comment: Preamble Questions: EPA’s proposal would provide the Director the discretion to require the owner or operator to identify and characterize additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure dissipation. EPA says that these layers could provide additional sites for monitoring, mitigation, and remediation. EPA’s proposal would not require that these

additional zones be identified for all GS sites because their absence does not necessarily indicate inappropriateness of a GS site. However, if such zones are present, information about their characteristics can provide inputs for predictive models, identify appropriate monitoring locations, and improve public confidence in and acceptance of a proposed GS site. EPA specifically seeks comment on the merits of requiring the identification of these additional zones.

EPA Notice 64.

NGWA Response: While NGWA believes that a site with a single confining can provide storage integrity, NGWA recommends that if there are additional confining layers at the site they should be characterized to get a better estimate of leakage risk to USDWs and possibly identify additional monitoring

zones.

Response: EPA agrees with the commenter that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection from endangerment. The final regulation retains the requirement at §146.83(b) which affords the Director discretion to require owners or operators to identify and characterize additional zones. Any additional confining zones would need to be included in the geologic site characterization process, which the owner or operator would submit and the Director would review in determining whether to grant a permit. EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in making an objective decision about requiring additional confining layers. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Christine Reimer Letter ID: 0142 Commenter Organization: National Ground Water Association Comment ID: 22592 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Proposed Rule: 146.83(b)

Proposed revision: (b) Owners or operators of Class VI wells must identify and characterize additional zones, if they exist, that will impede vertical fluid movement, allow for pressure dissipation, and provide additional opportunities for monitoring, mitigation and remediation. Vertical faults and fractures that

transect these zones must be identified.Rationale: While NGWA believes that a site with a single confining can provide storage integrity we feel that if there are additional confining layers at the site they should be characterized to get a better estimate of leakage risk to USDWs and possibly identify additional monitoring zones.

Response: EPA agrees with the commenter that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection from endangerment. The final regulation retains the requirement at §146.83(b) which affords the Director discretion to require owners or operators to identify and characterize additional zones. Any additional confining zones would need to be included in the geologic site characterization process, which the owner or operator would submit and the Director would review in determining whether to grant a permit. EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in making an objective decision about requiring additional confining layers. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Patrick Nugent Letter ID: 0143 Commenter Organization: Texas Pipeline Association (TPA) Comment ID: 23140

Comment: 7. Characterization of a secondary containment zone should not be left to the discretion of the Director. The proposed regulations provide that at the Director's discretion, he or she shall require owners or operators of Class VI wells to identify and characterize secondary containment or confinement zones. Rather than stating this provision as a requirement to be imposed upon an applicant at the discretion of the Director, TPA suggests that EPA establish this provision as an additional demonstration to be made by an applicant, in the event that a secondary confinement zone is present at the site. The existence of a secondary confining zone would make the site more attractive for permitting and should be treated as an incentive to make the permitting process progress more smoothly and swiftly. A secondary containment zone is certainly not needed to ensure safe geologic sequestration. A single containment zone is all that is needed. Accordingly, if a secondary containment zone does exist at the site, then the applicant should be provided the opportunity to demonstrate that it does exist and to receive preferential treatment in the permitting process as a

result.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements (at §146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects.

EPA disagrees that such sites warrant "preferential treatment." Rather, the Agency expects that the

extensive site characterization data collected at each site will be evaluated in the context of that site (and USDW protection) to support a determination regarding where a permit should be issued. TheAgency believes that providing the Director discretion will allow consideration of a range of sites for GS, based on site-specific conditions and ensure USDW protection. EPA believes that requiring appropriate site characterization by the owner or operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific geologic data will afford the greatest protection of USDWs from endangerment.

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in making an objective decision about requiring additional confining layers. The guidance

can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Richard Driggans Letter ID: 0145 Commenter Organization: Tennessee Valley Authority Comment ID: 23149

Comment: 2. Siting - The proposed rule provides the Director the discretion to require the owner or operator to identify and characterize additional (secondary) confining and containment zones above the primary (i.e., lowermost) confining zone to further impede vertical fluid movement and allow for pressure dissipation. There are situations that must require secondary containment, e.g., CO2 GS well fields located in the vicinity of a designated sole-source aquifer or other aquifer widely used for water supply. Assurance of CO2 containment must be near-absolute in such cases, and regulators must have discretion to require cap rock redundancy. As a further precaution, potential

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements (at §146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects.

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

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in making an objective decision about requiring additional confining layers. The guidance

can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.Commenter Name: Bonnie Lovelace Letter ID: 0152 Commenter Organization: Montana Department of Environmental Quality (MDEQ) Comment ID:

22110

Comment: 10. EPA seeks comment on the concept of identifying and characterizing additional confining and containment zones above the primary confining zone. MDEQ agrees with this approach and EPA's reasoning that such information would add to predictive models, identify monitoring locations and improve public confidence and acceptance of a proposed geologic sequestration site. Additionally, in the environmental assessment process required under NEPA and some state environmental policy acts, such information would allow for more thorough consideration of project alternatives.

Response: EPA agrees with the commenter that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection from endangerment. The final regulation retains the requirement at §146.83(b) which affords the Director discretion to require owners or operators to identify and characterize

additional zones.

Commenter Name: Bonnie Lovelace Letter ID: 0152 Commenter Organization: Montana Department of Environmental Quality (MDEQ) Comment ID:

22127

Comment: 146.83 (b): MDEQ suggests that this content be a requirement, not at the discretion of the Director. All possible demonstration of containment needs to be a requirement.

Response: EPA agrees with the commenter that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection from endangerment. EPA disagrees with the commenter that the requirement should be mandatory. The final regulation retains the requirement at §146.83(b) which affords the Director discretion to require owners or operators to identify and characterize additional zones.

Commenter Name: James Dooley Letter ID: 0156 Commenter Organization: Joint Global Change Research Institute, Pacific Northwest National Laboratory Comment ID:

22642

Comment: Allowing the Director the Discretion to Ask for Additional Fact Finding on Supplemental Confining Layers Page 43505-43506. EPA specifically asks for comments on allowing the Director to require that additional confining zones be identified for certain projects. Assuming that the Director uses this authority to require more fact finding for cause (i.e., it is not a capricious request), then it seems as if USEPA has struck an appropriate balance here and should retain this flexibility in the final rule. Given the capital cost of something like an IGCC+CCS, it does not seem unreasonable to ask that cores be taken from a second or third overlying caprock if there is some reason to want to ensure that there are additional containment systems beyond the caprock immediately above the target injection zone. While the USEPA might receive comments saying that this is potentially a significant unknown cost that could delay CCS deployment, the cost of this additional fact finding is likely denominated in the millions of dollars or less while the rest of the complete end-to-end CCSfacility could be worth tens of billions of dollars. Again assuming that this flexibility is only used when needed and for cause, it seems to be an appropriate and cost effective tool for ensuring the overall goals of the Class VI program are fulfilled.

Response: EPA acknowledges the commenter's support and agrees that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection from endangerment. The final regulation retains the requirement at §146.83(b) which affords the Director discretion to require owners or operators to identify and characterize additional zones.

Commenter Name: James Childress Letter ID: 0158 Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23759

Comment: Concern #4: Requirement for secondary confinement/containment. (Ref. page 43505, 1Proposed Geologic Siting Requirements)

The proposal would provide the Director the discretion to require the owner or operator to identify and characterize additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure and dissipation. Secondary containment (multiple confining structures) should not be required to prevent leakage of CO2. If required, this will prevent geologic storage in certain but important geographic regions. It also raises doubt concerning procedures and protocols to characterize and validate safe geologic storage formations and containment where there is not secondary containment. Under the proposed rule, there are measures that provide adequate assurance of formation integrity and require operators to demonstrate that their project will not endanger underground sources of drinking water (USDWs). If a secondary containment is present, it will be detected during site characterization and risk assessment. Such a special case could be analyzed to evaluate the potential risks to USDWs and to develop additional evaluation criteria to be applied to permit geological storage without going through the aquifer exemption process.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: James Stine Letter ID: 0163 Commenter Organization: National Rural Electric Cooperative Association Comment ID:(NRECA) 21325

Comment: 4. On a related subject, EPA requests comment on whether the Final Rule should require, or allow the Director to require at his discretion, the identification and characterization of additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure dissipation -- in effect, a "secondary containment" requirement. Id. at 43505-06. As a general matter, NRECA opposes the inclusion of this secondary containment requirement, and believes that it will only be in the most unusual situations where the circumstances warrant the Director exercising his discretion and requiring this additional protection in a Class VI permit. While it is of course true that additional containment zones above the confining zone could impede vertical fluid movement, there is no basis for requiring these additional zones if it has already been demonstrated that the original confining is protective of USDWs.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: Michael Mudd Letter ID: 0167 Commenter Organization: FutureGen Alliance (FGIA) Comment ID: 22457

Comment: Multiple Confining Layers Could be Required at the Direction of the

Director

p. 53536, c. 3 The Proposed Rules for Class VI wells identified by EPA include a requirement for a confining zone with suitable properties to contain the injected CO2 (§ 146.83(a). In addition, under subsection (b) of the proposed regulation, owners or operators may be required to identify and characterize multiple confining layers, at the discretion of the Director (§ 146.83(b)).

Comment:

- Subsection (b) of § 146.83 of the proposed regulations, which grants the Director discretion to require the presence of multiple confining layers, does not promote sound policy and should be removed from the proposed regulation.

- If EPA chooses to retain the option described in subsection (b), then the discretion of the Director should be limited, and there should be specification of the types of conditions under which multiple confining layers might be required.This optional requirement may eliminate suitable GS sites without reducing risk. It also adds a potential risk to a proposed project because the likelihood and cost of this additional requirement will not be known during the project initiation phase.

The rationale for inclusion of an optional requirement for multiple confining layers is not provided. There does not appear to be any clear need for that additional requirement, which goes beyond what is currently required for Class I UIC wells that inject hazardous wastes. The proposed regulation could lead to significant problems in the future, but more importantly, this requirement is not needed. If subsection (b) of § 146.83 were removed, and if the Director or his staff find that the confining system identified by an operator does not appear to be reliable, they can reject the application and/or require that the operator provide information on additional confining layers. The description of the requirements for a confining system given in part (2) of subsection (a) would cover this situation, and would allow protection of USDW’s and the public without creating the potential for confusion that would arise with the option outlined in subsection (b).

Previous experience and research have demonstrated that a single wellcharacterized confining system can provide more than adequate protection by preventing the upward migration of CO2. For example, time-lapse seismic imaging at the Sleipner Project demonstrates "the caprock is an effective seal that prevents CO2 migration out of the storage formation" (IPCC 2005). Examination of recent surveys of the safety of underground CO2 sequestration found no suggestion that multiple confining systems are needed or should be required (e.g., IPCC 2005; Benson and Surles 2006). In addition, the technical support document provided by EPA for the proposed rule changes (Vulnerability Evaluation Framework for Geologic Sequestration of Carbon Dioxide, EPA430-R-08-009) does not provide any support for requirement of multiple confining layers.

The proposed regulations do not specify or in any way limit the conditions under which multiple confining layers might be required. Thus, there is no guidance for imposition of the rule, and no limitations on the discretion of the Director. Including this additional discretionary requirement as an option in the regulations is troublesome because there then is a good possibility that it could become the default requirement. If that were the case, the requirement of multiple confining layers would lead to potential disqualification of excellent storage sites, and additional costs for characterization.

An additional problem with the optional requirement of multiple confining layers is one of perception. We know of no precedent within current UIC regulations, other applicable U.S. environmental law, or internationally, for the requirement of multiple confining layers to contain injected fluids. Given the lack of precedent, the inclusion of the requirement for multiple confining layers for CO2 in the proposed regulations for Class VI wells could lead to the incorrect perception by the public that injection and storage of CO2 is more dangerous to the public than subsurface injection of hazardous wastes. This perception of high risk, which does not appear to be justified by previousstudies of the risks of subsurface CO2 sequestration (e.g., IPCC 2005; Benson and Surles 2006) could lead to decreased use of carbon sequestration as an option to limit global climate change, and therefore to decreased potential for full use of U.S. energy resources.

References:

Benson SM and T Surles. 2006. Carbon Dioxide Capture and Storage: An Overview with Emphasis on Capture and Storage in Deep Geological Formations, The Proceedings Special Issue, Institute of Electrical and Electronics Engineers (IEEE), Vol. 94, No 10, October 2006, DOI 10.1109/PROC.2006.883716.

IPCC. 2005. IPCC Special Report: Carbon Dioxide Capture and Storage. Summary for Policy Makers and Technical Summary, B. Metz, O. Davidson, H. de Coninck, M. Loos, and L. Meyer (eds.). Cambridge University Press, New York.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in making an objective decision about requiring additional confining layers. The guidance

can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Michael J. Miller Letter ID: 0168 Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22494

Comment: Preamble, page 43505-43506 and §146.83(b): "Today’s proposal would provide the Director the discretion to require the owner or operator to identify and characterize additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure dissipation ... EPA specifically seeks comment on the merits of identifying these additional zones."

EPRI COMMENT #4A: From a technical perspective, the key criterion for requiring additional characterization should be that the applicant cannot demonstratecompliance with the minimum criteria for siting a GS project specified in §146.83(a)(1) and (a)(2) -- specifically if the applicant must rely on [a] multiple injection zones to receive the anticipated total volume (§146.83(a)(1)) without fracturing the formation or displacing fluids or [b] multiple confining units to impede vertical movement (§146.83(a)(2)). Section §146.83(b) requires characterization of additional zones that will impede fluid movement, which seems redundant to §146.83 (a)(2). EPA should remove Section §146.83(b) and characterization of additional zones should be limited to those needed by the applicant to demonstrate capacity and containment (i.e., §146.83(a)(1) and (a) (2)).

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: Michael J. Miller Letter ID: 0168 Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22496

Comment: EPRI COMMENT #4C: Section §146.83(b) of the rule states that the Director may require an applicant to characterize additional zones that will impede vertical

fluid movement that are "free of faults and fractures." Because fracture-free confining units are rare and many confining units that contain fractures can provide effective confinement (see EPRI Comment #4B), and because §146.83(a)(2) provides for additional characterization of multiple confining zones if needed,

EPRI recommends that this section be eliminated.

Response: The Agency believes that the requirement at §146.83(a)(2) that the confining zone(s) be free of transmissive faults or fractures is appropriate for Class VI wells and is necessary to ensure containment of the injectate and that requiring the confining zone to be free of transmissive faults maximizes protection of USDWs from endangerment.

EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation.

Commenter Name: Theresa Pugh Letter ID: 0169Commenter Organization: American Public Power Association Comment ID: 23398

Comment: APPA is not expert on drilling practices and many of the site characterization techniques discussed in the proposed rule. As discussed below, the Final Rule should leave the door open for a range of injection sites (except for sole source aquifers which we believe should be excluded from consideration) and methods (some of which are unrecognized, or even unknowable, at this point in time), provided that the Owner or Operator can show that the injection and storage will be protective of USDWs. APPA does join its "sister" organization, AWWA, representing the water utilities, in calling for proposed GS projects to at least identify all the confining zones in applications. APPA does not believe that multiple confining zones should be arbitrarily required. We defer to state directors to make these judgments based upon their knowledge of local geology.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency believes that providing the Director discretion will allow consideration of a range of sites for GS, based on site-specific conditions and ensure USDW protection. EPA believes that requiring appropriate site characterization by the owner or operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific geologic data will afford the greatest protection of USDWs from endangerment.

Commenter Name: Kyle Isakower Letter ID: 0170 Commenter Organization: American Petroleum Institute Comment ID: 24157 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Rule Provision: 146.83(b)

API Comments: (b) At the Director‘s discretion, owners or operators of Class VI wells must identify and characterize additional zones that will impede vertical fluid movement, are free of faults and fractures that may interfere with containment, allow for pressure dissipation, and provide additional opportunities for monitoring, mitigation and remediation.

Rationale: This paragraph creates a presumption that additional confining zones WILL be required. It is also redundant given the previous sections.

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, secondary confining zones are required when the Director determines that these zones are needed to maximize the protection of USDWs from endangerment. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provideadditional sites for monitoring, mitigation, and remediation. The Agency believes that providing the Director discretion will allow consideration of a range of sites for GS, based on site-specific conditions, and ensure USDW protection. EPA believes that requiring appropriate site characterization by the owner or operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific geologic data will afford the greatest protection of USDWs from endangerment.

Commenter Name: Kyle Isakower Letter ID: 0170 Commenter Organization: American Petroleum Institute Comment ID: 24222

Comment: Rule Provisions: 73 FR 43506 EPA Preamble Question: 10. EPA’s proposal would provide the Director the discretion to require the owner or operator to identify and characterize additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure dissipation. EPA says that these layers could provide additional sites for monitoring, mitigation, and remediation. EPA’s proposal would not require

that these additional zones be identified for all GS sites because their absence does not necessarily indicate inappropriateness of a GS site. However, if such zones are present, information about their characteristics can provide inputs for predictive models, identify appropriate monitoring locations, and improve public confidence in and acceptance of a proposed GS site. EPA specifically seeks comment on the merits of requiring the identification of these additional

zones. EPA Notice 43506.

API Response: API holds that secondary containment is not mandatory. There are many areas where a single confining zone can be shown to be highly protective of USDWs. Adequacy of containment must be done on a site-specific basis. This requirement would reduce the number of CCS storage site opportunities while increasing costs and not enhancing protection.

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, secondary confining zones are required when the Director determines that these zones are needed to maximize the protection of USDWs from endangerment. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. EPA disagrees that the requirement would reduce the number of sites available for GS. The intent of this requirement is to ensure that a proposed site provides adequate protection of USDWs from endangerment; if this protection cannot be demonstrated, the Director would not issue a permit for GS at the site.

Commenter Name: James Rower Letter ID: 0173 Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23482

Comment: On a related subject, EPA requests comment on whether the Final Rule should require, or allow the Director to require at his discretion, the identification and characterization of additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede verticalfluid movement and allow for pressure dissipation - in effect, a "secondary containment" requirement. Id. at 43505-06. As a general matter, USWAG opposes the inclusion of a secondary containment requirement, even at the Director's discretion, and believes that it will only be in the most unusual situations where circumstances warrant the requirement of this additional layer of protection.

In developing this regulatory program, EPA must ensure that CO2 GS is protective of USDWs while simultaneously taking care not to unduly burden the permitting process or discourage the development of environmentally protective Class VI

wells. While it is of course true that additional containment zones above the confining zone could impede vertical fluid movement, there is no basis for requiring these additional zones if it has already been demonstrated that the original confining zone is protective of USDWs. A redundant requirement that is frequently unnecessary will eliminate otherwise valid injection zones from the universe of potential Class VI injection sites.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: Pamela Faggert Letter ID: 0175 Commenter Organization: Dominion Comment ID: 23520

Comment: b. Requirements for Secondary Containment

The Agency is considering granting discretion to the Director to require "additional zones that will impede vertical fluid movement..." Such broad discretionary authority is unnecessary for the same reasons that limitations of injection to formation below the lowermost USDW are unnecessary. This discretionary authority is likely to have a negative affect on GS into unmineable coal seams and for storage through existing EOR wells. In the event the Agency elects to retain this authority, we urge EPA to modify the proposal to include clear guidelines in order to provide some amount of certainty for CCS operators and investors. Additionally, clear guidelines for exercising requirements for secondary containment would safeguard against what is discretionary authority on paper from becoming default requirements in practice.

Secondary confinement should not be a requirement. Such a requirement would eliminate good and sound storage sites and reduce ultimate capacity of the country to store CO2.Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements (at §146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects.

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

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in making an objective decision about requiring additional confining layers. The guidance

can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Kenneth Nemeth Letter ID: 0176 Commenter Organization: Southern States Energy Board Comment ID: 23540

Comment: being sited in what would otherwise be very safe geology. SSEB also does not support the requirement of secondary seals for the same reason as stated above. The only requirement would be viable provisions for safe and secure containment to protect USDWs.

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, secondary confining zones are required when the Director determines that these zones are needed to maximize the protection of USDWs from endangerment. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. EPA disagrees that the requirement would reduce the number of sites available for GS. The intent of this requirement is to ensure that a proposed site provides adequate protection of USDWs from endangerment; if this protection cannot be demonstrated, the Director would not issue a permit for GS at the site.

Commenter Name: Quinlan J. Shea Letter ID: 0177 Commenter Organization: Edison Electric Institute Comment ID: 23551 Other EPA Comment Codes and Descriptions: 1310 1.1.2.4 Comments on other "out of scope" issues, e.g., pore space ownership; 2100 1.6 Target Geologic Formations for GS; 3100 2.1 Proposed Geologic Siting Requirements (40 CFR 146.83)

Comment: EEI agrees that proper site selection is critical to a successful GS project andnotes that it serves to minimize, if not eliminate, any potential threats to drinking water sources that CO2 injection and storage may pose. However, several of the proposed requirements are unnecessary from the perspective of protecting drinking water sources and would only serve to hamper GS projects from going forward, including limitations on receiving formations, potential alteration to the current definition of an underground source of drinking water (USDW), and the proposed grant of discretion to the UIC program director to require permit applicants to identify secondary containment/confining zones.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

EPA believes that the Class VI requirements, including the level of site characterization required under §§146.82 and 146.83, appropriately address the unique challenges posed by large-scale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic formations.

EPA disagrees with the commenter that the GS rule requirements are unnecessary to protect USDWs. The GS final rule builds upon longstanding programmatic requirements for underground injection that have been in place since the 1980s and that are used to manage over 800,000 injection wells nationwide. These programmatic requirements are designed to prevent fluid movement into USDWs by addressing the potential pathways through which injected fluids can migrate into

USDWs. EPA coordinated with Federal and non- Federal entities on GS and CCS to determine how best to tailor existing injection requirements to CO2 for GS.

Additionally, EPA clarifies that the GS rule does not categorically preclude injection of CO2 into any non-USDW formation types. The purpose of the GS rule is to ensure protection of USDWs from endangerment, and the rule requires that owners or operators demonstrate that wells are sited in suitable systems with geologic formations to receive and confine injected CO2, required at §146.83 of the GS rule. The Class VI siting, well construction and operation, monitoring and testing, and post-injection site care and site closure requirements are designed to ensure that injected CO2 remains within the target formation. If an owner or operator can demonstrate to the Director's satisfaction that GS in coal seams, basalts, salt domes, or shales can be accomplished in a manner that protects USDWs and meets all of the requirements of the GS rule, the project may be permitted

as a Class VI well.

Commenter Name: Quinlan J. Shea Letter ID: 0177 Commenter Organization: Edison Electric Institute Comment ID: 23583Comment: A third area of concern related to siting involves the Agency’s proposed grant of discretion to the UIC program director to require permit applicants to identify "additional zones that will impede vertical fluid movement, are free of faults and fractures that may interfere with containment, allow for pressure dissipation, and provide additional opportunities for monitoring, mitigation and remediation"-i.e., secondary containment/confining zones. A proposal to require secondary containment, even in discretionary form, is unnecessary and unwarranted for many of the same reasons that a blanket limitation on receiving formations is unnecessary and unwarranted. Specific concerns include the following:

- Better alternatives exist to protect USDW: The presumed purpose of secondary containment is better addressed through proper site selection and well-designed plans to detect and contain leakage from the primary containment system. EEI also notes, as we did in our May 15, 2008, pre-rulemaking comments, a discussion led by panelist Susan Hovorka of the University of Texas at EPA‘s December 2007 public workshop, as characterized in the Agency‘s meeting summary (p. 8):

CO2 is very responsive to pressure as a mitigation technique in the event of movement to an undesired location. Injecting fluids in an adjacent well at a regulated pressure can guide CO2 back to the containment area. Another mitigation option is changing injection patterns once a problem is detected. Site-specific contingencies could be built into plans to provide guidance in the event of an unexpected

event.

Given the proposed rules‘ emergency and remedial response requirements, a secondary containment requirement is especially unwarranted.

- Unprecedented under the UIC program: Secondary containment/confining systems are currently not required for any other types of injection wells under the UIC program. The physical and chemical properties of CO2 are not sufficiently unique--nor do they pose a sufficiently unique potential threat to USDW--to warrant such unprecedented treatment under the UIC program.

- Unprecedented in U.S. environmental law generally: We are unaware of any comparable requirement to ascertain secondary containment features in geologic formations in any other environmental regulatory regime. Those regimes that impose secondary containment requirements--for example, secondary containment requirements for oil spill prevention control and countermeasure plans under the Oil Pollution Act, and for land disposal and underground storage tanks under the Resource Conservation and Recovery Act (RCRA)--relate to man-made containment structures, as opposed to geologic containment structures.

- Unprecedented internationally: To our knowledge, none of the CO2 storage projects currently operating outside the U.S. has been required to have or demonstrate existence of a secondary containment zone/confining system. Further, Norway, Canada, Australia and Algeria, countries where CCS projects are currently underway, do not require secondary containment.Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

EPA believes that the Class VI requirements, including the level of site characterization required under §§146.82 and 146.83, appropriately address the unique challenges posed by large-scale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic formations. The Agency believes that in some geologic settings, the presence and identification of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These formations could further impede vertical fluid movement, allow for pressure dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection of USDWs from endangerment. While other countries may not require such additional protection, EPA believes that providing the Director this additional discretion is an important element of assuring that GS activities will not endanger

USDWs.

Commenter Name: Quinlan J. Shea Letter ID: 0177 Commenter Organization: Edison Electric Institute Comment ID: 23584

Comment: - Concerns for inaccurate public perception: As noted above, no secondary containment requirement, whether blanket or discretionary, currently exists even for the injection of hazardous wastes under the Class I permitting scheme. Imposition of a substantially more rigorous requirement on injection and storage of CO2 strongly implies that such a project would be more dangerous than underground injection of a host of other materials, including hazardous wastes. The final rules should be crafted to avoid creating this public stigma for one of the most promising GHG-management strategies, and for a technology that can be employed safely and effectively in the absence of secondary containment requirements of any sort.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GSprojects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

EPA adds that a demonstration to the public that extensive data have been collected and evaluated would likely improve confidence in the project and help address public questions and concerns.

Commenter Name: Quinlan J. Shea Letter ID: 0177 Commenter Organization: Edison Electric Institute Comment ID: 23585

Comment: While EEI is opposed to any secondary containment requirement, including one that would be subject to exercise of the UIC program director‘s discretion, EPA‘s proposal to establish secondary containment as a discretionary requirement presumably would allow for consideration of the nature of the particular primary confining system at issue and reduce unnecessary elimination of potential storage sites as compared to a default requirement to demonstrate secondary containment. At the same time, discretion, even where warranted, must be bounded by sufficiently clear guidelines for application in determining whether imposition of a discretionary requirement is warranted in a given case. However, the proposed rules contain no discussion of any factors for the UIC program director to consider in making this determination. Should the Agency choose to impose a discretionary requirement, the current proposal should be modified to include such clear guidelines in order to provide some amount of certainty for operators and investors as well as to avoid the metamorphosis of what is a discretionary requirement on paper into a default requirement in practice.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements (at §146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects.

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

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in making an objective decision about requiring additional confining layers. The guidance

can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Frederick R. Eames Letter ID: 0178 Commenter Organization: CCS Alliance Comment ID: 23818Comment: E. SECONDARY CONTAINMENT SHOULD NOT BE REQUIRED

Secondary containment (i.e., a second formation of "caprock" above the initial formation) should not be required because it could limit the eligibility of potential storage sites, raise costs due to extra transportation, and add to the considerable regulatory burden of regulating site characterization. The standards of the Safe Drinking Water Act require that any injection that does occur will not result in endangerment of USDWs. This should be sufficient, without imposing in addition an arbitrary additional standard.

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, secondary confining zones are required when the Director determines that these zones are needed to maximize the protection of USDWs from endangerment. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. EPA disagrees that the requirement would reduce the number of sites available for GS. The intent of this requirement is to ensure that a proposed site provides adequate protection of USDWs from endangerment; if this protection cannot be demonstrated, the Director would not issue a permit for GS at the site.

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

Commenter Name: Thomas Curtis Letter ID: 0181 Commenter Organization: American Water Works Association (AWWA) Comment ID: 23680

Comment: EPA Request for Comment: EPA specifically seeks comment on the merits of requiring the identification of additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure dissipation. EPA Notice 43506.

AWWA Response: AWWA recommends that EPA require owner/operators to identify these additional confining and containment zones as part of the site characterization process. This identification is important to understand the project as a whole, and failing to identify these additional zones results in a very large knowledge gap in the identification of potential mitigation options in the event that a leak occurs from the primary confining layer. Having this information available to regulators and stakeholders would allow for a better understanding of the project as a whole, and would provide for a more informed and comprehensive review process. If certain stakeholders, such as drinking water utilities, were provided with this information, utilities would have a better understanding of a geologic sequestration project with the knowledge that multiple confining layers separated the carbon dioxide injection zone from their

USDWs.Response: EPA agrees with the commenter that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection from endangerment. EPA disagrees that secondary confining zones are required at all sites, e.g., where a primary confining zone that free of transmissive faults or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide stream and displaced formation fluids and allow injection at proposed maximum pressures and volumes without initiating or propagating fractures in the confining zone(s) (per §146.83(a)) is demonstrated to be present. The final regulation retains the requirement at §146.83(b) which affords the Director discretion to require owners or operators to identify and characterize additional zones.

Commenter Name: Thomas Curtis Letter ID: 0181 Commenter Organization: American Water Works Association (AWWA) Comment ID: 23729 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Part 146.83(b) This part of the rule should a requirement, not an option that can be requested at the discretion of the Director. While it is possible that a site with a single confining can provide storage integrity, AWWA recommends that additional confining layers at the site be characterized to get a better estimate of leakage risk to USDWs and possibly identify additional monitoring zones. It is important to know if these zones exist, and to have adequately documented their characteristics, to evaluate and demonstrate the possibility of secondary containment. AWWA recommends revising this part to read:

Owners or operators of Class VI wells must identify and characterize additional zones that will impede vertical fluid movement, are free of faults, fractures or other discontinuities that may interfere with containment, allow for pressure dissipation, and provide additional opportunities for monitoring, mitigation and

remediation.

Response: EPA agrees with the commenter that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection from endangerment. EPA disagrees that secondary confining zones are required at all sites, e.g., where a primary confining zone that free of transmissive faults or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide stream and displaced formation fluids and allow injection at proposed maximum pressures and volumes without initiating or propagating fractures in the confining zone(s) (per §146.83(a)) is demonstrated to be present. The final regulation retains the requirement at §146.83(b) which affords the Director discretion to require owners or operators to identify and characterize additional zones.

Commenter Name: Bradley J. Field Letter ID: 0186 Commenter Organization: New York State Dept. of Environmental Conservation

Div. of Mineral Resources Comment ID:

25179

Comment: I. EPA specifically seeks comment on the merits of identifying these additional

zones.

NYSDEC-DMN Response: It is NYSDEC-DMN’s opinion that identification and characterization of secondary confinement should not be a requirement unless the unit identified as the primary confining zone is questionable. Thisdetermination should be made on a project and site-specific basis.

Response: EPA agrees with the commenter that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection from endangerment. The final regulation retains the requirement at §146.83(b) which affords the Director discretion to require owners or operators to identify and characterize

additional zones.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24331

Comment: 2. Redundant Confining/Containment Zone Requirement

EPA requests comment on whether the Final Rule should require, or allow the Director discretion to require, additional confining and containment zones above the primary confining zone. 73 Fed. Reg. at 43505-06. We oppose any such requirement.

If there are substantial doubts as to the adequacy of a single confining formation, it would of course be necessary to specify one or more additional formations as part of the a confining system that would be adequate to protect USDWs; this is one of the reasons the term "confining zone" is defined in the way it is (i.e., to include a "geologic formation [or] group of formations" acting as a barrier to fluid movement). Considerations as to the adequacy of the confining zone are a central focus of the permitting process, with permit applicants being required to demonstrate that USDWs will not be endangered by the proposed injection activity. By definition, a requirement for additional confining zones would therefore be a requirement for redundant geologic containment: it would never be necessary for the protection of USDWs. By allowing the Director discretion to impose such a requirement, the proposed rule would expressly authorize the imposition of requirements that are not necessary for the protection of USDWs. Worse, the proposed rule provides no apparent limit on the Director’s discretion in this regard. Indeed, the preamble suggests that the Director could require detailed evaluation of additional geologic formations just because they are there, perhaps in the hope that additional study and documentation - though not necessary to show that USDWs will be protected - might "improve public confidence in and acceptance of" GS. 73 Fed. Reg. at

43506.

Again, the ultimate standard for geologic citing should be protection of USDWs. By authorizing extraneous siting (or site assessment) requirements that are not necessary for protection of USDWs, the proposed rule would invite a "belt and suspenders" approach that would unnecessarily burden permit applicants and signal unwarranted concern about the risks and uncertainties associated with CO2 injection. Under the UIC program, protection of USDWs is and should be enough.

The Director should have no discretion - let alone unlimited discretion - to "tack on" additional siting requirements.

It should be noted that a requirement for redundant confining and containment zones would be unprecedented. No such requirement exists in the UIC program,even in the context of hazardous waste injection. Nor does such a requirement apply in any of the countries where GS projects are currently underway (including Norway, Canada, Australia and Algeria). EPA should not single out GS for heightened and substantially more rigorous requirements than would apply in other contexts. To do so would signal a disproportionate concern about the injection of CO2 that simply is not warranted on the merits.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site. While other countries may not require such additional protection, EPA believes that providing the Director this additional discretion is an important element of assuring that GS activities will not endanger USDWs.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24423 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Rule Provision: 146.83(b)

Proposed CCS Group Recommendations: (b) At the Director’s discretion, owners or operators of Class VI wells must identify and characterize additional zones that will impede vertical fluid movement, are free of faults and fractures that may interfere with containment, allow for pressure dissipation, and provide additional opportunities for monitoring, mitigation and remediation.

Basis for CCS Group Comments: This paragraph creates a presumption that additional confining zones WILL be required. It is also redundant given the previous sections. Providing for a confining zone that meets the requirements should be sufficient. Any further identification of confining zones would potentially eliminate zones useful for future geologic sequestration.

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, secondary confining zones are required when the Director determines that these zones are needed to maximize the protection of USDWs from endangerment. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that theserequirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24514

Comment: Rule Provisions or Federal Register Cite: 73 FR 43506 EPA Preamble Question: 10. EPA’s proposal would provide the Director the discretion to require the owner or operator to identify and characterize additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure dissipation. EPA says that these layers could provide additional sites for monitoring, mitigation, and remediation. EPA’s proposal would not require

that these additional zones be identified for all GS sites because their absence does not necessarily indicate inappropriateness of a GS site. However, if such zones are present, information about their characteristics can provide inputs for predictive models, identify appropriate monitoring locations, and improve public confidence in and acceptance of a proposed GS site. EPA specifically seeks comment on the merits of requiring the identification of these additional

zones. EPA Notice 43506.

CSC Response: Secondary containment should not be mandatory. There are many areas where a single confining zone can be shown to be highly protective of USDWs. Adequacy of containment must be demonstrated on a site-specific basis. By definition, an additional confining or containment zone beyond is not necessary to prevent endangerment of USDWs, and would serve only to prevent the use of otherwise-appropriate GS reservoirs.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA clarifies that secondary confining zones are not required for all GS sites. EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: Jeff W. Sheets Letter ID: 0192 Commenter Organization: ConocoPhillips Comment ID: 23893 Other EPA Comment Codes and Descriptions: 4324 2.4.4.1.2 Comments opposed to requiring injection below the lowermost USDW

Comment: Lowermost USDW:

EPA's proposal restricts injection to formations beneath the lowermost USDW andgives the Director the discretion to require identification of additional confining zones. ConocoPhillips recommends focus on performance standards rather than depth or confining zone redundancy - injection should be allowed into any injection zone which has geologic and mechanical isolation sufficient to prevent fluid movement which could endanger any USDW. In some site situations injection zones can be safely above USDW's with adherence to well construction standards and other requirements. There may be high potential geologic sites above USDWs which need not be excluded for storage. Identification of redundant confining zones may be confusing and unduly reduce the number of sites deemed appropriate for CCS. This is particularly true since the definition of confining zone

includes "formation or set of formations."

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, secondary confining zones are required when the Director determines that these zones are needed to maximize the protection of USDWs from endangerment. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. EPA also believes that a site-specific demonstration regarding the need for additional confining zones affords the flexibility the

commenter seeks.

EPA adds that the final GS rule contains a provision (at 146.95) for owners or operators to apply for waivers from the requirement that injection be below the lowermost USDW. EPA believes this waiver provision will reduce potential limitations on the re-permitting of Class II wells as Class VI wells, provided they meet the requirements at 146.95 while still protecting USDWs from endangerment.

The final GS rule at §146.95 establishes a process by which owners or operators can seek a waiver of the Class VI injection depth requirements for injection into non-USDW formations above and/or between USDWs. The waiver approach requires the submission of extensive, site-specific information (in conjunction with the permit application submission) to demonstrate that injection of CO2 into a non-USDW that is above or between USDWs can be done in a manner that is protective of USDWs. The requirements are designed to ensure that the owner or operator, the Director, and the Regional Administrator consider, on a site specific basis, the implications, benefits, and challenges associated with GS and ensuring water availability and USDW protection. For additional information on the waiver approach, please see the final rule and preamble, as well as EPA's responses to comments on the Notice of Data Availability and Request for Comment.

Commenter Name: Paul Pike Letter ID: 0198 Commenter Organization: Ameren Corporation Comment ID: 23944

Comment: A related subject is the requirement to identify and characterize additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure dissipation - in effect, a "secondary containment" requirement. 73 Fed. Reg. at 43505-06. We believe that only in the most unusual situations would circumstances warrant the requirement of an additional protective layer and oppose the inclusion of a "secondary containment" requirement.Response: EPA believes that the Class VI requirements, including the level of site characterizationrequired under §§146.82 and 146.83, appropriately address the unique challenges posed by largescale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic formations. EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. The Agency believes that in some geologic settings, the presence and identification of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These formations could further impede vertical fluid movement, allow for pressure dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection of USDWs from endangerment.

Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24577

Comment: Rule Provisions: 73 FR 43506 EPA Rule Issue: 10. EPA’s proposal would provide the Director the discretion to require the owner or operator to identify and characterize additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure dissipation. EPA says that these layers could provide additional sites for monitoring, mitigation, and remediation. EPA’s proposal would not require that these

additional zones be identified for all GS sites because their absence does not necessarily indicate inappropriateness of a GS site. However, if such zones are present, information about their characteristics can provide inputs for predictive models, identify appropriate monitoring locations, and improve public confidence in and acceptance of a proposed GS site. EPA specifically seeks comment on the merits of requiring the identification of these additional zones.

EPA Notice 43506.

Anadarko Petroleum Corporation (APC) Response: By utilizing the definition of confining zone (a geologic formation, group of formations, or part of a formation stratigraphically overlying the injection zone that acts as a barrier to fluid movement) the EPA has provided necessary guidance to prevent movement of fluids from the injection zone which may potentially endanger a USDW. The director discretion does not provide for any additional protection level of USDWs but does create issues and uncertainty by allowing the director to require

dditional zones without scientific basis.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirementspromote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24653 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Rule Provision: 146.83(b)

Anadarko Petroleum Corporation (APC) Comments: (b) At the Director’s discretion, owners or operators of Class VI wells must identify and characterize additional zones that will impede vertical fluid movement, are free of faults and fractures that may interfere with containment, allow for pressure dissipation, and provide additional opportunities for monitoring, mitigation and

remediation.

Rationale: This paragraph creates a presumption that additional confining zones WILL be required. It is also redundant given the previous sections.

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, secondary confining zones are required when the Director determines that these zones are needed to maximize the protection of USDWs from endangerment. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation.

Commenter Name: Chris M. Hobson Letter ID: 0201 Commenter Organization: Southern Company Comment ID: 22166

Comment: EPA also seeks comment on whether the Final Rule should require, or allow the Director to require at his discretion, the identification and characterization of additional confining and containment zones above the primary confining zone that could further impede vertical fluid movement and allow for pressure dissipation. Id. at 43505-06. As a general matter, Southern Company opposes the inclusion of any sort of "secondary containment" requirement - even at the Director's discretion - as it would unnecessarily burden Owners or Operators of Class VI wells while providing little or no benefit in terms of USDW protection. An emphasis on proper site selection and characterization combined with performance-based standards will ensure that Class VI permits are only issued for CO2 GS projects where the primary containment zone will protect against endangerment of USDWs in the first instance. Identification of redundant confining and containment zones would only serve to confuse the permit application and approval process and unduly restrict siting of CO2 GS projects.

Response: EPA believes that the Class VI requirements, including the level of site characterizationrequired under §§146.82 and 146.83, appropriately address the unique challenges posed by largescale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic formations.

EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). The Agency believes that in some geologic settings, the presence and identification of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These formations could further impede vertical fluid movement, allow for pressure dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection of USDWs from endangerment.

Commenter Name: John Corra Letter ID: 0205 Commenter Organization: Wyoming Department of Environmental Quality (DEQ) Comment ID:

22201

Comment: 6. Various issues where we agree with US EPA that the Director should have the discretion to determine, or require:

b.Identifying and characterizing additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure dissipation.

Response: EPA agrees with the commenter that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection from endangerment. The final regulation retains the requirement at §146.83(b) which affords the Director discretion to require owners or operators to identify and characterize

additional zones.

Commenter Name: Christopher Murray Letter ID: 0207 Commenter Organization: Pacific Northwest National Laboratory Comment ID: 22431

Comment: Multiple Confining Layers Could be Required at the Discretion of the Director.....Page 3 Subsection (b) of § 146.83 of the proposed regulations, which grants the Director discretion to require the presence of multiple confining layers, does not promote sound policy and should be removed from the proposed regulation.

Response: EPA believes that the Class VI requirements, including the level of site characterizationrequired under §§146.82 and 146.83, appropriately address the unique challenges posed by largescale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic formations.

EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and anelectric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: Christopher Murray Letter ID: 0207 Commenter Organization: Pacific Northwest National Laboratory Comment ID: 22439

Comment: PROPOSED REGULATION

p. 43536, c. 3 The proposed rules for Class VI wells identified by EPA include a requirement for a confining zone with suitable properties to contain the injected CO2 (§ 146.83(a)). In addition, under subsection (b) of the proposed regulation, owners or operators may be required to identify and characterize multiple confining layers, at the discretion of the Director (§ 146.83(b)).

DISCUSSION

The rationale for inclusion of an optional requirement for multiple confining layers is not provided. There does not appear to be any clear need for that additional requirement, which go beyond what is currently required for Class I UIC wells that inject hazardous wastes. The proposed regulation could lead to significant problems in the future, but more importantly, this requirement is not needed. If subsection (b) of § 146.83 were removed, and if the Director or his staff find that the confining system identified by an operator does not appear to be reliable, they can reject the application and/or require that the operator provide information on additional confining layers. The description of the requirements for a confining system given in part (2) of subsection (a) would cover this situation, and would allow protection of USDW's and the public without creating the potential for confusion that would arise with the option outlined in subsection (b).

Previous experience and research have demonstrated that a single wellcharacterized confining system can provide more than adequate protection by preventing the upward migration of CO2. For example, time-lapse seismic imaging at the Sleipner Project demonstrates "the caprock is an effective seal that prevents CO2 migration out of the storage formation" (IPCC 2005). Examination of recent surveys of the safety of underground CO2 sequestration found no suggestion that multiple confining systems are needed or should be required (e.g., IPCC 2005; Benson and Surles 2006). In addition, the technical support document provided by EPA for the proposed rule changes (Vulnerability Evaluation Framework for Geologic Sequestration of Carbon Dioxide, EPA 430-R-08-009) does not provide any support for requirement of multiple confining layers.

The proposed regulations do not specify or in any way limit the conditions under which multiple confining layers might be required. Thus, there is no guidance for imposition of the rule, and no limitations on the discretion of the Director. We believe including this additional discretionary requirement as an option in the regulations is troublesome because there then is a good possibility that it could become the default requirement. If that were the case, the requirement of multiple confining layers would lead to potentialdisqualification of excellent storage sites, and additional costs for

characterization.

An additional problem with the optional requirement of multiple confining layers is one of perception. We know of no precedent within current UIC regulations, other applicable U.S. environmental law, or internationally, for the requirement of multiple confining layers to contain injected fluids. Given the lack of precedent, the inclusion of the requirement for multiple confining layers for CO2 in the proposed regulations for Class VI wells could lead to the incorrect perception by the public that injection and storage of CO2 is more dangerous to the public than subsurface injection of hazardous wastes. This perception of high risk, which does not appear to be justified by previous studies of the risks of subsurface CO2 sequestration (e.g., IPCC 2005; Benson and Surles 2006) could lead to decreased use of carbon sequestration as an option to limit global climate change, and therefore to decreased potential for full use of U.S. energy

resources.

PNNL RECOMMENDATION

For the reasons outlined above, we believe that subsection (b) of § 146.83 of the proposed regulations, which grants the Director discretion to require the presence of multiple confining layers, does not promote sound policy and should be removed from the proposed regulation. If EPA chooses to retain the option described in subsection (b), then we feel that the discretion of the Director should be limited, and there should be specification of the types of conditions under which multiple confining layers might be required.

REFERENCES

Benson SM and T Surles. 2006. Carbon Dioxide Capture and Storage: An Overview with Emphasis on Capture and Storage in Deep Geological Formations, The Proceedings Special Issue, Institute of Electrical and Electronics Engineers (IEEE), Vol. 94, No 10, October 2006, DOI 10.1109/PROC.2006.883716.

IPCC. 2005. IPCC Special Report: Carbon Dioxide Capture and Storage. Summary for Policy Makers and Technical Summary, B. Metz, O. Davidson, H. de Coninck, M. Loos, and L. Meyer (eds.). Cambridge University Press, NewYork.

Response: EPA believes that the Class VI requirements, including the level of site characterizationrequired under §§146.82 and 146.83, appropriately address the unique challenges posed by largescale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic formations. The Agency believes that in some geologic settings, the presence and identification of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These formations could further impede vertical fluid movement, allow for pressure dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection of USDWs from endangerment. While other countries may not require such additional protection, EPA believes that providing the Director this additional discretion is an important element of assuring that GS activities will not endanger

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

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in making an objective decision about requiring additional confining layers. The guidance

can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

To the comment that the geologic siting requirements could create a negative public perception, EPA believes that a demonstration to the public that extensive data have been collected and evaluated would likely improve confidence in the project and help address public questions and concerns.

Commenter Name: Richard Guinn Letter ID: 0210 Commenter Organization: Eastman Chemical Company Comment ID: 22695

Comment: 4. Secondary confinement/containment should not be required.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements (at §146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects.

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

Commenter Name: Richard Guinn Letter ID: 0210 Commenter Organization: Eastman Chemical Company Comment ID: 22710

Comment: Concern #4: Requirement for secondary confinement/containment. (Ref: page 43505, 1- Proposed Geologic Siting Requirements)

The proposal would provide the Director the discretion to require the owner or operator to identify and characterize additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure and dissipation. Secondary containment (multiple confining structures) should not be required to prevent leakage of CO2. If required, this will prevent geologic storage in certain but important geographic regions. It also raises doubt concerning procedures andprotocols to characterize and validate safe geologic storage formations and containment where there is not secondary containment. Under the proposed rule, there are measures that provide adequate assurance of formation integrity and require operators to demonstrate that their project will not endanger underground sources of drinking water (USDWs). If a secondary containment is present, it will be detected during site characterization and risk assessment. Such a special case could be analyzed to evaluate the potential risks to USDWs and to develop additional evaluation criteria to be applied to permit geological storage without going through the aquifer exemption process.

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, secondary confining zones are required when the Director determines that these zones are needed to maximize the protection of USDWs from endangerment. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. EPA disagrees that the requirement would reduce the number of sites available for GS. The intent of this requirement is to ensure that a proposed site provides adequate protection of USDWs from endangerment; if this protection cannot be demonstrated, the Director would not issue a permit for GS at the site.

Commenter Name: John King Letter ID: 0211 Commenter Organization: Shell Exploration and Production Company (SEPCo) Comment ID:

22765

Comment: 2. Redundant Confining/Containment Zone Requirement

EPA requests comment on whether the Final Rule should require, or allow the Administrator discretion to require, additional confining and containment zones above the primary confining zone. 73 Fed. Reg. at 43505-06. SEPCo strongly opposes any such requirement.

Rather than being necessary for the protection of USDWs, a requirement for additional confining and containment zones above the injection zone would apply in addition to the requirement for an adequate demonstration that USDWs will be protected. By definition, such a requirement is unnecessary. Having demonstrated the adequacy of their belts, there is no need to require permit applicants to furnish suspenders as well.

It should also be noted that a requirement for additional confining and containment zones above the injection zone would be unprecedented. No such requirement exists in the UIC program, even in the context of hazardous waste injection. Nor does such a requirement apply in any of the countries where GS projects are currently underway (including Norway, Canada, Australia and Algeria). EPA should not single out GS for heightened and substantially more rigorous requirements than would be warranted on the merits of the actual risk.

Recommendation:Require potential operators to demonstrate that USDWs will not be endangered by the proposed injection activity in the primary containment zone through the Class VI permitting process, without adding a requirement of any secondary confining or containment zones.

Response: EPA believes that the Class VI requirements, including the level of site characterizationrequired under §§146.82 and 146.83, appropriately address the unique challenges posed by largescale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic formations. The Agency believes that in some geologic settings, the presence and identification of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These formations could further impede vertical fluid movement, allow for pressure dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection of USDWs from endangerment. While other countries may not require such additional protection, EPA believes that providing the Director this additional discretion is an important element of assuring that GS activities will not endanger

USDWs.

Commenter Name: Barbara Walz Letter ID: 0216 Commenter Organization: Tri-State Generation and Transmission Association,

Inc. Comment ID:

22969 Other EPA Comment Codes and Descriptions: 2100 1.6 Target Geologic Formations for GS

Comment: D. It is counterproductive at this stage in the development of a CO2 geologic sequestration regulatory regime to categorically preclude any potentially feasible injection formations as possible long-term storage sites. EPA recognizes that the commercial deployment of CO2 geologic sequestration activities will result in the production of large volumes of CO2 for which owners or operators will have to locate new and environmentally protective injection zones. Therefore, it makes sound policy sense for EPA to encourage the identification and utilization of as many protective zones as possible, with the prerequisite that any injection site be protective of underground sources of drinking water (USDW). Tri-State supports alternative approaches that would allow

Response: EPA clarifies that the GS rule does not categorically preclude injection of CO2 into any non-USDW formation types. The purpose of the GS rule is to ensure protection of USDWs from endangerment, and the rule requires that owners or operators demonstrate that wells are sited in suitable systems with geologic formations to receive and confine injected CO2, required at §146.83 of the GS rule. The Class VI siting, well construction and operation, monitoring and testing, and post-injection site care and site closure requirements are designed to ensure that injected CO2 remains within the target formation. If an owner or operator can demonstrate to the Director's satisfaction that GS in coal seams, basalts, salt domes, or shales can be accomplished in a manner that protects USDWs and meets all of the requirements of the GS rule, the project may be permitted

as a Class VI well.

Commenter Name: Barbara Walz Letter ID: 0216 Commenter Organization: Tri-State Generation and Transmission Association,

Inc. Comment ID:

22972

Comment: EPA requests comment on whether the Final Rule should require, or allow theDirector to require at his/her discretion, the identification and characterization of additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure dissipation in effect, a "secondary containment" requirement. Tri-State opposes the inclusion of this secondary containment requirement, and believes that it will only be in the most unusual situations where the circumstances warrant the Director exercising discretion to require this additional protection in a Class VI permit. While additional containment zones above the confining zone could impede vertical fluid movement, there is no basis for requiring these additional zones if it was already demonstrated that the original confining zone is protective of USDWs.

Response: EPA believes that the Class VI requirements, including the level of site characterizationrequired under §§146.82 and 146.83, appropriately address the unique challenges posed by largescale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic formations.

EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: Olon Plunk Letter ID: 0217 Commenter Organization: Xcel Energy, Inc. Comment ID: 21557

Comment: Secondary Containment

Requiring secondary containment as a matter of standard practice is unnecessary and will likely significantly decrease the number of geologic storage sites available. Such a requirement exceeds the standard for Class I hazardous waste injection wells, creating the logical, yet erroneous inference that CO2 injection in a Class VI well poses a greater risk than Class I injection of a hazardous waste. Given the proposed rule's basic premise that the design of a Class VI well and the designated receiving formation must be protective of USDWs in order to be permitted in the first instance, the need for secondary containment is redundant and unnecessary. Secondary containment should remain only as an option to be proposed by the project applicant in instances where legitimate concerns over the primary containment capabilities of the receiving formation preclude permitting in the normal manner.

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, secondary confining zones are required when the Director determines that these zones are needed tomaximize the protection of USDWs from endangerment. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. The Agency acknowledges that the additional confining formations may also, in site-specific circumstances, further impede vertical fluid movement, provide additional sites for monitoring, mitigation, and remediation, and allow for pressure dissipation. EPA disagrees that the requirement would reduce the number of sites available for GS or that the requirement implies that CO2 poses a greater threat than Class I hazardous wells. The intent of this requirement is to ensure that a proposed site provides adequate protection of USDWs from endangerment; if this protection cannot be demonstrated, the Director would not issue a permit for

GS at the site.

Commenter Name: Andrew Duguid Letter ID: 0226 Commenter Organization: Schlumberger Carbon Services Comment ID: 24019 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Proposed Rule: (b) At the Director’s discretion, owners or operators of Class VI wells must identify and characterize additional zones that will impede vertical fluid movement, are free of faults and fractures that may interfere with containment, allow for pressure dissipation, and provide additional opportunities for monitoring, mitigation and remediation.

Schlumberger Suggested Revision: (b) Owners or operators of Class VI wells must identify and characterize some additional zones, if they exist, that will impede vertical fluid movement, allow for pressure dissipation, and provide additional opportunities for monitoring, mitigation and remediation. Vertical faults and

fractures that transect these zones must be identified.

Schlumberger Rationale: We believe that a site with a single confining can provide storage integrity, however, we feel that if there are additional confining layers at the site they should be characterized to get a better estimate of leakage risk to USDWs and possibly identify additional monitoring

zones.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.Commenter Name: Neeraj Gupta Letter ID: 0229 Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21828

Comment: Page 61, Injection Zone and Confining Layer - Conditions under which "director" may require a secondary containment/buffer zone should be more clearly defined to provide regulatory certainty. In addition, in definition of what constitutes a secondary containment or buffer zone is highly subjective and a matter of individual opinions. Therefore, more clarity on how these zones should be selected is requested.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements (at §146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects.

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

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in making an objective decision about requiring additional confining layers. The guidance

can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Abbie Krebsbach Letter ID: 0235 Commenter Organization: Montana-Dakota Utilities Co. Comment ID: 23183

Comment: Secondary Containment Requirement Concerns

A proposal to require secondary containment, even in discretionary form, is unnecessary and unwarranted for many of the same reasons that a blanket limitation on receiving formations is unnecessary and unwarranted. The presumed purpose of secondary containment is better addressed through proper site selection and well-designed plans to detect and contain leakage from the primary containment system. Montana-Dakota believes that the physical and chemical propel1ies of CO2 are not sufficiently unique, nor do they pose a sufficiently unique potential threat to USDW, to warrant such unprecedented treatment under the UIC program.

Imposition of a substantially more rigorous requirement on injection and storage of CO2 strongly implies that such a project would be more dangerous than underground injection of a host of other materials, including hazardous wastes. The final rules should be crafted to avoid creating this public stigma for one of the most promising GHG-management strategies, and for a technology that canbe employed safely and effectively in the absence of secondary containment requirements of any sort.

However, should the EPA choose to impose a discretionary requirement for program directors to determine secondary containment requirements, the current proposal should be modified to include such clear guidelines in order to provide some amount of certainty for operators and investors, as well as to avoid the metamorphosis of what is a discretionary requirement on paper into a default requirement in practice.

Response: EPA believes that the Class VI requirements, including the level of site characterizationrequired under §§146.82 and 146.83, appropriately address the unique challenges posed by largescale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic formations. The Agency believes that in some geologic settings, the presence and identification of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These formations could further impede vertical fluid movement, allow for pressure dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection of USDWs from endangerment.

EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements (at §146.83(b)) promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects.

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

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in making an objective decision about requiring additional confining layers. The guidance

can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Philip Papadeas Letter ID: 0238 Commenter Organization: Sandia Technologies, LLC Comment ID: 23352

Comment: §146.83 (a)(2) Re: Confining Zone free of transmissive faults This remains very difficult to prove or demonstrate in the subsurface unless detailed seismic and geologic data exists in the area to define such. One suggested approach may involve including a secondary buffer confining zone, as a redundancy to the first confining zone. The key may also be if there isconnection from the Injection Zone to the Confining Zone, then additional modeling or reduction in injection rate/pressure and more of a margin of safety built in unless more detailed geological modeling demonstrates the lack of transmissive faulting.

Response: EPA acknowledges that some smaller fractures may not be detectable during the site characterization process. Other requirements for GS injection wells and sites can mitigate the potential impacts of unidentified fractures. These include limitations on injection pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible CO2 movement through high-permeability regions (i.e., faults and/or fractures) not detected in the initial

site characterization.

Commenter Name: Mark Bohrer Letter ID: 0241 Commenter Organization: North Dakota Industrial Commission Comment ID: 23230

Comment: 10. EPA’s proposal would provide the Director the discretion to require the owner or operator to identify and characterize additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure dissipation. EPA says that these layers could provide additional sites for monitoring, mitigation, and remediation. EPA’s proposal would not require that these

additional zones be identified for all GS sites because their absence does not necessarily indicate inappropriateness of a GS site. However, if such zones are present, information about their characteristics can provide inputs for predictive models, identify appropriate monitoring locations, and improve public confidence in and acceptance of a proposed GS site. EPA specifically seeks comment on the merits of requiring the identification of these additional zones.

EPA Notice 43506.

Redundant confining zones should not be required. If the primary confining zone is adequate, by definition it is sufficient. If one sequestration site identifies one confining zone and another identifies multiples, it may lead to public confusion and lack of confidence in a site that only has one confining zone even though it is just as protective.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.Commenter Name: Mark Bohrer Letter ID: 0241 Commenter Organization: North Dakota Industrial Commission Comment ID: 23284

Comment: 146.83(b) Delete reference to identification of additional confining zones. This implies this will be required. Redundant confining zones are not required

in other UIC well classes.

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, secondary confining zones are required when the Director determines that these zones are needed to maximize the protection of USDWs from endangerment. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation.

Commenter Name: Kurt Waltzer Letter ID: 0250 Commenter Organization: Clean Air Task Force Comment ID: 22305 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Secondary confining zone

§146.83 allows the Director to require additional confining zones, at his discretion. We do not believe that this will always be necessary - a good primary zone should be sufficient. Where additional hazards justify it, a secondary zone might be desirable. In all cases, we caution against relying on secondary confinement in place of establishing with a greater degree of certainty the suitability of the primary zone. Potential problems are best identified and anticipated early, and the focus should be on site characterization to show with confidence whether the confining zones are adequate. We suggest striking part (b) in §146.83 as it seems redundant. However, the Director must have the discretion to require a secondary confining zone if needed. We therefore recommend clarifying part (a)(2) to read explicitly:

[In the paragraph below the text in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the original formatting.]

"A confining zone, or zones , that is ARE free of transmissive faults or fractures and of sufficient areal extent and integrity to contain the injected carbon dioxide stream and displaced formation fluids and allow injection at proposed maximum pressures and volumes without initiating or propagating fractures in the confining zone(s)"

Response: EPA disagrees with the suggested edit, but agrees that providing the Director discretion will allow consideration of a range of sites for GS, based on site-specific conditions and ensure USDW protection. EPA believes that requiring appropriate site characterization by the owner or operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific geologic data will afford the greatest protection of USDWs fromendangerment. The Agency believes that in some geologic settings, the presence and identification of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These formations could further impede vertical fluid movement, allow for pressure dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection of USDWs from endangerment.

Commenter Name: Walter L. Baker Letter ID: 0253 Commenter Organization: Utah Division of Water Quality Comment ID: 22346

Comment: ALLOWING FOR DIRECTOR DISCRETION IN REQUIRING ADDITIONAL

CONTAINMENT ZONES

We support EPA's intention to provide Director's discretion in requiring additional confining and containment zones that could further impede vertical fluid movement and allow for pressure dissipation. This acknowledges the importance and merit of implementing a risk-based, site-specific approach in characterizing a site for CCGS projects. This allows for flexibility in setting permit requirements for the protection of USDWs and other natural resources thereby increasing the number of sites that could potentially be used for CCGS.

Response: EPA agrees with the commenter that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection from endangerment. The final regulation retains the requirement at §146.83(b) which affords the Director discretion to require owners or operators to identify and characterize additional zones. EPA believes that providing the Director discretion will allow consideration of a range of sites for GS, based on site-specific conditions and ensure USDW protection. EPA believes that requiring appropriate site characterization by the owner or operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific geologic data will afford the greatest protection of USDWs from endangerment.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24814

Comment: EPA Rule Issue: 10. EPA’s proposal would provide the Director the discretion to require the owner or operator to identify and characterize additional confining and containment zones above the primary (i.e., lowermost) confining zone that could further impede vertical fluid movement and allow for pressure dissipation. EPA says that these layers could provide additional sites for monitoring, mitigation, and remediation. EPA’s proposal would not require that these

additional zones be identified for all GS sites because their absence does not necessarily indicate inappropriateness of a GS site. However, if such zones are present, information about their characteristics can provide inputs for predictive models, identify appropriate monitoring locations, and improve public confidence in and acceptance of a proposed GS site. EPA specifically seeks comment on the merits of requiring the identification of these additional zones.

EPA Notice 43506.

GWPC CO2 Committee Response: Any showing of secondary containment is unnecessary once the requirement for containment has been satisfied by providing for an adequate confining zone. References to additional confining and containmentzones is more likely to lead to confusion than support.

Rationale: Any emphasis on the availability of additional confining zones is likely to cause confusion over the adequacy of projects that satisfy the actual requirements but do not also provide what is by definition redundant and unnecessary layers of protection. Moreover, discussions of additional confining zones could undercut the ability to use beneficially any additional formations in the area of interest covered by a proposed project.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24880 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: EPA Proposal: (b) At the Director’s discretion, owners or operators of Class VI wells must identify and characterize additional zones that will impede vertical fluid movement, are free of faults and fractures that may interfere with containment, allow for pressure dissipation, and provide additional opportunities for monitoring, mitigation and remediation.

GWPC Recommendations: Delete paragraph

Rationale: This paragraph creates a presumption that additional zones WILL be required. It is also redundant from previous sections.

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, secondary confining zones are required when the Director determines that these zones are needed to maximize the protection of USDWs from endangerment. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation.

Commenter Name: Claire Olson Letter ID: 0260 Commenter Organization: Basin Electric Power Cooperative Comment ID: 22396Comment: "1. Proposed Geologic Siting Requirements"

EPA requests comments on whether the final rule should require the identification and characterization of additional confining and containment zones with the primary (lowermost) confining zone that could further impede vertical fluid movement and allow for pressure dissipation and act as a "secondary containment" requirement.

Basin Electric opposes the inclusion of this secondary containment or characterization requirement as a default provision. In the rare situation where specific site circumstances would warrant, the State Director could exercise discretion and require this additional protection in a Class VI Permit.

This requirement for additional containment zones is not needed if it has already been demonstrated and characterized that the original confinement zone is protective of USDW. The requirement to identify and characterize additional zones that will impede vertical fluid movement is too broad.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

Letter ID: 0263 Commenter Organization: Interstate Oil & Gas Compact Commission Comment ID: 22795

Comment: III A. 1 Proposed Geologic Siting Requirements

K. EPA specifically seeks comment on the merits of identifying these additional zones.

IOGCC Response: Secondary confinement should not be a requirement. Such a requirement would eliminate good and sound storage sites and reduce ultimate capacity of the country to store anthropogenic CO2. The determination as to whether secondary confinement should be required should be made on a project by project basis and be site specific. It is possible to hypothesize a circumstance where secondary confinement is not necessary with the addition of stronger monitoring requirements.

Response: EPA clarifies that secondary confining zones are not required for all GS sites. Rather, secondary confining zones are required when the Director determines that these zones are needed to maximize the protection of USDWs from endangerment. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)).EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. EPA disagrees that the requirement would reduce the number of sites available for GS. The intent of this requirement is to ensure that a proposed site provides adequate protection of USDWs from endangerment; if this protection cannot be demonstrated, the Director would not issue a permit for GS at the site.

Commenter Name: Michael Moore Letter ID: 0265 Commenter Organization: North American Carbon Capture & Storage Association (NACCSA) Comment ID:

22863

Comment: 2. Secondary Containment

Another area of concern related to siting involves the Agency's proposed grant of discretion to the UIC program director to require permit applicants to identify secondary containment/confining zones. While NACCSA agrees with the Agency's current approach not to include a blanket secondary containment requirement (although, if secondary confining units exist with regard to a given project, they should be included in site modeling, along with identification of any transmissible zones between the primary and secondary confining units), and, while a discretionary requirement for secondary containment is preferable to a blanket, universal requirement, any discretionary requirement that is imposed should be bounded by clear parameters for its use. The proposed rule, however, contains no such parameters. NACCSA urges the Agency to consider what parameters may be put in place to ensure protection ofUSDWs while providing some level of clarity for project operators and investors regarding under what circumstances such a requirement should be expected, as well as some degree of assurance that the "on paper" discretionary requirement will not lead to an "in practice" blanket requirement due to the lack of appropriately enumerated.

Several points should be considered in determining whether any sort of requirement for secondary containment, including a discretionary requirement, should be imposed, as well as what parameters maybe appropriately included in the final rule should the Agency choose to implement a discretionary requirement. They include the following:

- Do better alternatives exist to protect USDWs? In any given case, the additional protection to USDWs that the Agency appears to believe secondary containment could provide likely may be better addressed through proper site selection and well-designed plans and procedures to detect and contain leakage from the primary containment system, rather than through imposing de facto limitations on the types of sites that maybe used. If such requirements have already been satisfied, there is likely no need for secondary containment.

- What public misconceptions maybe created? Secondary containment is unprecedented under the UIC program, even for the injection of hazardous wastes under the Class I permitting scheme. Imposition of such a requirement on injection and storage of CO2suggests that such a project would be more dangerous than underground injection of a host of other materials, including hazardouswastes, or even than injection of CO2 for purposes of EOR. The Agency should carefully consider the risk of creating unwarranted negative public perception posed by proposed requirements. In any given case, CCS technology can be safely employed absent any secondary containment requirements.

Response: EPA believes that the Class VI requirements, including the level of site characterizationrequired under §§146.82 and 146.83, appropriately address the unique challenges posed by largescale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic formations. The Agency believes that in some geologic settings, the presence and identification of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These formations could further impede vertical fluid movement, allow for pressure dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection of USDWs from endangerment.

To the comment that the geologic siting requirements could create a negative public perception, EPA believes that a demonstration to the public that extensive data have been collected and evaluated would likely improve confidence in the project and help address public questions and concerns.

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

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA expects that this guidance will assist permit writers in making an objective decision about requiring additional confining layers. The guidance

can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Karl R. Moor Letter ID: 0501 Commenter Organization: Southern Company Comment ID: 21159

Comment: For example, requiring a secondary containment field for this is, would create the wrong impression about the safety of carbon capture and storage, and it should not be a part of the final rule. Such a requirement is unprecedented in the UIC program.

Even for the storage of Class I sources secondary containment fields are also unprecedented internationally. Countries where carbon capture and storage projects are currently underway, besides the United States, including Norway, Canada, Australia, and Algeria did not require secondary containment zones. And in those, in most of these instances the countries are in fact using the existing petroleum walls without the benefit of an additional regulatory

program.Singling out, as the regulations do, carbon capture and storage would just heighten the substantial level of scrutiny. It sends a message that carbon dioxide is more dangerous than the underground injection of other substances. And since EPA is the agency in charge with protecting the environment, the public could easily be swayed by EPA's apparent apprehension of carbon capture that's currently, that is currently embodied in the regulations.

In order to create a regulatory scheme that fosters carbon capture and storage the development and employment, the EPA should also consider how it has characterized carbon capture injection, both explicitly and implicitly in the regulation.

Moreover, EPA should consider the effect of these regulations on securing critical financial support for CCS projects. Misperceptions about the risks can skew opportunities for financing. No one needs to be reminded today that the recent turmoil in the financial markets makes very challenging the financing of new technologies.

In a credit constrained world the heightened risk and overplaying risk and the conflicts that this regulation can impede the development of a critically important technology for reducing CO2 emissions.

Response: EPA believes that the Class VI requirements, including the level of site characterizationrequired under §§146.82 and 146.83, appropriately address the unique challenges posed by largescale GS including large injection volumes, the relative buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in captured CO2, and its mobility within subsurface geologic formations. EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (e.g., §146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. The Agency believes that in some geologic settings, the presence and identification of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These formations could further impede vertical fluid movement, allow for pressure dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection of USDWs from endangerment. While other countries may not require such additional protection, EPA believes that providing the Director this additional discretion is an important element of assuring that GS activities will not endanger USDWs. To the comment that the geologic siting requirements could create a negative public perception, EPA believes that a demonstration to the public that extensive data have been collected and evaluated would likely improve confidence in the project and help address public questions and concerns.

Commenter Name: Kevin Frederick Letter ID: 0525 Commenter Organization: Wyoming Department of Environmental Quality Comment ID: 21399

Comment: Discretion for identifying and characterizing additional confining and containment zones of the primary confining zone that could further impede vertical fluid movement and allow for pressure dissipation.

Response: EPA agrees with the commenter that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improveUSDW protection from endangerment. The final regulation retains the requirement at §146.83(b) which affords the Director discretion to require owners or operators to identify and characterize

additional zones.

Commenter Name: Doug Louis Letter ID: 0530 Commenter Organization: Kansas Corporation Commission Comment ID: 21340

Comment: KCC staff finds the cost of additional containment zones above the confining zones to be confusing and unnecessary. If the injection zone and the confining zone are competent, well understood and monitored, there is no need to have a costly and unneeded system of redundant containment zones above the two.

Furthermore, the term containment zone has was not in the definitions section or fully explained.

Response: EPA retains the requirement to identify additional containment/confining zones, if required by the Director, as proposed (§146.83(b)). EPA acknowledges that such additional zones may not be needed in all circumstances, and clarifies that this requirement is at the Director's discretion, based on his or her understanding of a particular site. EPA believes that, in some situations, the presence of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These layers could further impede vertical fluid movement and allow for pressure dissipation, and also provide additional sites for monitoring, mitigation, and remediation. The Agency's decision is supported by commenters representing states, water associations, and an electric utility who assert that these requirements promote a flexible, risk-based, site-specific approach to characterizing and permitting a site for GS projects, and are intended to improve understanding of the project as a whole and promote better modeling of the site.

EPA clarifies that the GS rule defines confining zone as "a geologic formation, group of formations, or part of a formation stratigraphically overlying the injection zone that acts as barrier to fluid movement." (§146.81(d)).

Comment Code: 3130 2.1.3 Comments that operators should submit more (or different) geologic data than proposed



### Individual Comments

Commenter Name: Michael H. Cochran Letter ID:

0108 Commenter Organization: Bureau of Water, Division of Environment, Kansas Department of Health & Environment (KDHE) Comment

ID: 21963

Comment: 146.82 (g): Needs to list the formations for which baseline geochemical data should be obtained. In addition to the USDWs, this at minimum should include the injection formation and the confining zone immediately above the injection zone.

Response: The GS regulation, at §146.82(a)(6), requires the owner or operator to submit baseline geochemical data on subsurface geologic formations. EPA is not specifying for which formationsthis information should be submitted to allow flexibility, but examples may include the following formations: a) the injection zone, b) the confining zones, c) containment zones above the confining zones in which any potentially migrating CO2 could be trapped, d) all USDWs, and e) any other geologic zone or formation that is important to the proposed monitoring program. The Director has the authority to request additional geochemical data as well.

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Leslie Savage Letter ID: 0122 Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24762 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: (2) Location, orientation, and properties of known or suspected faults and fractures that may transect the confining zone(s) in the area of review and a determination that they would not interfere with containment;

(4) Data on the depth, areal extent, thickness, mineralogy, porosity, permeability and capillary pressure of the injection and confining zone(s) ; including geology/facies changes based on field data which may include geologic cores, outcrop data, seismic surveys, well logs, and names and lithologic descriptions;

Response: EPA believes that the plural for injection zone(s) should be retained in the Final Rule in recognition of the fact that more than one injection zone may be used at some GS sites. EPA believes that in some geologic settings, the presence and identification of additional confining and containment zones above the primary (i.e., lowermost) confining zone can improve USDW protection. These formations could further impede vertical fluid movement, allow for pressure dissipation, and provide additional sites for monitoring, mitigation, and remediation, while also affording the greatest protection of USDWs from endangerment. While other countries may not require such additional protection, EPA believes that providing the Director this additional discretion is an important element of assuring that GS activities will not endanger USDWs.

Please see the final rule and the discussion of geologic site characterization in the preamble for

additional information.

Commenter Name: Christine Reimer Letter ID: 0142 Commenter Organization: National Ground Water Association Comment ID: 22545 Other EPA Comment Codes and Descriptions: 2064 1.5.3.2 Grandfathering construction of Class II wells (seeking comment); 2066 1.5.3.3 Grandfathering construction of Class V wells (seeking comment); 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: The NGWA Carbon Sequestration Task Force recommends that the experimental phaseextend beyond the regional partnerships to each site proposed for productionscale injection of carbon dioxide. It is recommended that at least one well at each site be constructed under the Class V experimental category, and thattesting of the adequacy of the geologic environment for geologic sequestration of carbon dioxide be conducted prior to permitting any well in the Class VI category at the site.

The transition of carbon dioxide injection wells from Class II (Enhanced Oil Recovery wells) to Class VI (carbon sequestration wells) will presumably be requested when production of the petroleum has ceased. Liquid carbon dioxide from a distant source, such as a power plant, can be stored in the depleted petroleum reservoir even after production has ceased, necessitating a change in classification of the injection well. The new use of the wells involves much longer storage time, and raises concerns about mechanical integrity and long term effects, including geochemical changes, on underground source of drinking water (USDWs). The reclassification should depend on a positive outcome from a Class V experimental program conducted in the depleted reservoir, as described

below.

The "grandfathering" of Class V carbon sequestration wells would mean allowing experimental wells to be permitted for operation after the testing period is over. The NGWA Carbon Sequestration Task Force recommends that each carbon sequestration system or wellfield have an experimental phase, and not rely on results from distant experimental locations. Thus, nearly every operational well would start as a Class V experimental well, or would go through a Class VI testing phase, before being permitted for long-term operation. The transition to Class VI operational status would require demonstrating that the minimum requirements are met at that location. Most wells would go through the following permitting phases:

- Class V experimental well construction permit: This permit would allow geologic and geophysical testing, aquifer testing, laboratory work, etc, but would not include injection of CO2 (only potable water injection testing would be allowed).

- Class VI experimental well operational testing permit: At this stage, the full monitoring facilities would need to be constructed. This permit would allow test injection of liquid CO2 at rates high enough to demonstrate that the location meets the minimum requirements for operation, for a period of up to two

years.

- Class VI operation permit: After demonstrating that the location and the well meet all the minimum requirements for injection of CO2, the operation permit can be issued.

The goals of the experimental well Class V construction permit would be to make the following demonstrations:

- A receiving zone of sufficient depth, area extent, thickness, porosity, and permeability is present;

- Lithologic description, geological name, thickness and depth of each confining unit above the storage aquifer, and of each USDW.- A trapping mechanism that is free of pathways for migration of injected fluids into a USDW. These pathways may include major non-sealing faults, porous beds within the confining unit, changes of facies trending toward more porous units and man-made structures such as wells or mine shafts. A trapping mechanism is defined as a geologic environment that prevents vertical and horizontal movement of fluids into a USDW; The volume of the trap shall exceed the proposed total volume of injected carbon dioxide for the life of the proposed facility

- Identification of all confining units between the primary injection/storage zone and the lowermost USDW, and their adequacy to contain the injected fluid. Unless the only feasible injection zone has only one confining unit separating it from the lowermost USDW, this demonstration includes adequacy of confinement for both the primary confining unit and a secondary containment system that extends to the base of the lowermost USDW and is completely redundant of the primary confining system and could confine the injected CO2 should the primary system fail. In locations where the secondary containment system is not possible, the applicant shall propose an alternative system of early warning of failure of the primary confining unit in order to avoid impacting any USDW should that confinement fail. This demonstration applies in the horizontal sense as well, demonstrating one or more mechanisms containing the fluid from horizontal movement into a USDW in the storage aquifer at a distant location.

- The construction of an operational monitoring system meeting all the requirements described in this document’s MMV section, and demonstration of the adequacy of this system to meet those requirements.

- Demonstration of mechanical integrity

Having made the foregoing demonstrations, a Class VI operational testing permit can be issued for a period of up to two years. The goals of the experimental well Class VI operational testing permit would be to make the following

demonstrations:

- A hydraulic demonstration of the adequacy (depth, area extent, thickness, porosity, and permeability) of the storage zone, using monitoring data and 4-D seismic monitoring of the extent of the CO2 plume. - Demonstration of the adequacy of the trap for 5/10 years of injection at the proposed rate. The volume of the trap shall exceed the proposed total volume of injected carbon dioxide for the 5/10 years of the first operation permit. - Demonstration of the adequacy of confinement under operational conditions using monitoring data and a method of detecting the extent of the CO2 plume in the storage aquifer, such as 4-D seismic monitoring or direct sampling. - Re- evaluation of the Area of Review and extent of the zone of endangering

influence. - Re-evaluation of mechanical integrity, using the buoyancy of the injected CO2 to better measure external mechanical integrity. The re-evaluation shall include the testing required during the initial MIT, as well as evaluation of the cement for carbonation, or chemical weathering by CO2Under this permitting scenario, the vast majority of Class V experimental wells would be constructed after the Class VI standards had been published. The "grandfathering" of Class V wells that do not meet the Class VI construction standards would only be needed for DOE test sites established before rulemaking was complete. If these wells include the ongoing mechanical integrity monitoring of annular fluid pressure and composition, and they pass periodic mechanical integrity testing, they should be able to follow the same permitting procedures to become operational Class VI wells.

Response: EPA believes that submittal and review of monitoring data (as required at §146.90) and the AoR reevaluation process (§146.84(e)) will provide an opportunity for an ongoing review of the site and a dialogue between the Director and the owner or operator to ensure that the project is being operated in a manner that protects USDWs from endangerment. EPA notes that changes to these plans require a permit modification under §144.39, the public must be notified according to the public comment procedures under 40 CFR 124.

Please see the final rule and the discussion of geologic site characterization in the preamble for

additional information.

EPA disagrees that every GS well should initially be permitted as a Class V well. The Agency believes that the tailored Class VI requirements including extensive requirements for geologic site characterization at §146.82, AoR evaluation at §146.84, and testing of the well during drilling at §146.87 are appropriate to ensure that permitting authorities have the necessary information to evaluate whether a specific site will allow safe injection of CO2. EPA adds that submittal and review of monitoring data (as required at §146.90) and the AoR reevaluation process (§146.84(e)) will provide an opportunity for an ongoing review of the site and a dialogue between the Director and the owner or operator to ensure that the project is being operated in a manner that protects USDWs from endangerment. Given this approach to permitting Class VI projects, EPA believes that the requirements for grandfathering of construction at §146.81(c) are necessary and appropriate.

Commenter Name: Christine Reimer Letter ID: 0142 Commenter Organization: National Ground Water Association Comment ID: 22546 Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Geologic Characterization

The UIC program is required under the Safe Drinking Water Act to protect USDWs from contamination from fluids injected into the subsurface. Part of this requirement is the demonstration that the injected fluids will not migrate, through buoyancy, ground-water flow or injection pressure, into USDWs. This demonstration is based on the characteristics of the geological environment where injection is to take place. The current UIC regulations require investigation of waste disposal sites through an application-phase data summary (Area of Review study) and geologic testing while drilling the pilot hole of the injection well. In general, the critical attributes of the injection and confining units are measured during pilot hole drilling, and the integrity and

extent of those units are addressed in the literature review and Area of Review study at the application phase. Because of the large volumes of carbon dioxide that are expected to be injected, and the vast extent of the storage zones, itis expected that more detailed information will be needed over a larger area for carbon sequestration than has been historically needed for injection of other

wastes.

The NGWA recommends that the adequacy and safety of injection of liquid carbon dioxide at each site be evaluated by multi-phase, variable density ground-water modeling, supported by extensive field investigations (see section General Comments on the Use of Modeling for Ground-Water Protection Related to CO2 Sequestration, below) These models should be included at the experimental well permit application phase as conceptual models, and progressively refined as data are collected during well construction and testing, and monitoring of operations.

The test injection well/operational testing permit application for a carbon sequestration injection well must address the geological characteristics of the site. The data presented at this stage should be adequate to make and calibrate an appropriate ground-water model. The necessary elements of the geologic system for carbon sequestration include:

- A receiving zone of sufficient depth that the injected carbon dioxide can be maintained in a supercritical state - Of sufficient areal extent that it includes the entire zone of endangering

influence - Of sufficient thickness and porosity to contain the volume of carbon dioxide injected over the life of the proposed system - Of sufficient permeability to accept the peak daily flow of injected carbon dioxide from the facility - A trapping mechanism (consisting of either impermeable barriers or geochemical/mixing barriers) that is free of vertical or horizontal pathways for migration of injected fluids into a USDW. The volume of the trap shall exceed the proposed total volume of injected carbon dioxide for the life of the proposed facility - A primary confining system of sufficient areal extent, thickness and competency to contain the injected fluid at proposed rates and volumes without initiating or propagating fractures in the confining zone - Unless the only feasible injection zone has only one confining unit separating it from the lowermost USDW, a secondary containment system that is completely redundant of the primary confining system and could confine the injected CO2 should the primary system fail. - The identification of a monitoring zone between the primary and secondary confining units. In locations where the secondary containment system is not possible, the applicant shall propose a monitoring formation to provide early warning of failure of the primary confining unit in order to avoid impacting any

USDW should that confinement fail. - Provide depth and completion information of all USDWs that may be affected by the injection if fluid movement does occur. - Provide geochemical information on subsurface aquifers, including all USDWs: Baseline geochemical data on water-rock- CO2 geochemistry and mineral reactions, maps and cross sections.These elements should be identified in existing well records, in geologic literature, and by using the results of the exploratory program. The critical storage and confining units should be shown to exist over the entire area of review, or zone of endangering influence

The operation permit application should also include a preliminary multi-phase numerical transport model for CO2 and formation fluid, including all of the

elements listed above. This model should include at least one calibration scenario and will be used to provide a preliminary evaluation of the adequacy and safety of injection of carbon dioxide at the site, as well as a preliminary calculation of the potential storage volume of the geologic structure.

Each permit application for a carbon sequestration injection well must include an Area of Review study, which addresses the entire zone of endangering influence of the carbon sequestration operation, including the area impacted after cessation of injection due to buoyancy transport. The zone of endangering influence shall be determined by the ground-water model described above and illustrated with maps and cross sections.

Provide information on the geologic structure of the proposed site, including:

- Maps and cross sections of local geologic structure. Each cross section should include the location and depth of relevant data sources, including geophysical logs, that were used in developing the cross section - Geological name and lithologic description of each injection zone, primary and/or secondary confining unit, and USDW - Data on the receiving formation and the confining systems : 1. Size of the storage reservoir, and extent of the confining units in comparison to the area of endangering influence 2. Presence or absence of a secondary confining unit 3. Porosity, and permeability of the storage zone and confining units, including any geology/facies changes, based on field data which may include geologic cores, outcrop data, 3-dimensional seismic surveys, and well logs 4. Capacity of the storage zone in comparison to the proposed total volume of carbon dioxide to be stored, 5. Evaluation of the long-term effectiveness of the storage structure, including expected pathways of migration of injected carbon dioxide, and

the horizontal barriers to fluid movement - Geomechanical information on fractures, stress, rock strength, and in situ fluid pressures within the primary and secondary containment units and confining

systems - Identification of potential pathways for migration of injected fluids and determination that they would not conduct a volume of fluid that would cause a violation of the prohibition of fluid movement as it applies to the class of

well that is to be constructed - Identification of potential risks within the zone of endangering influence, including degradation of water quality in USDWs, gas buildup in USDWs, reduction of porosity through geochemical changes in USDWs, and population that could be affected by gas releases.- List of penetrations into the injection zone and secondary containment system. - Information on seismic history and the presence/depth of seismic sources

Response: EPA agrees that extensive geological data collection and computational modeling, similar to what the commenter suggests, are important components of characterizing a potential GS site. For this reason, the GS regulation requires owners or operators to collect and submit extensive geological data (specified at §146.82) on the proposed GS site, including the injection and confining zones. Operators must also delineate the AoR using computational modeling that accounts for the multiphase flow of CO2 and native fluids (§146.84(c)), based on the geological data collected and proposed injection operations.

EPA disagrees with the comment that all sites should be evaluated by multi-phase, variable density groundwater modeling; instead, EPA believes that owners or operators should have the flexibility to select models that are most appropriate to site conditions and available data types and amounts. EPA is also requiring that the AoR be reevaluated at a frequency of every 5 years using monitoring and operating data to verify that the CO2 plume and pressure front are behaving as predicted in AoR calculation models (§146.84(e)).

Commenter Name: Brianne Metzger Letter ID: 0151 Commenter Organization: Spectra Energy Corp Comment ID: 21824

Comment: EPA is proposing that an applicant include "baseline geochemical data on subsurface formations, including all USDWs in the area of review." 40 C.F.R. § 146.82(g). It is not clear how much baseline data EPA is expecting the permit applicant to generate and collect from additional drilling or testing of the injection zone and all other zones. Given the likely depth of many of the GS wells through multiple strata, this could involve tens (and possibly hundreds) of different formations above the injection zone. Therefore, we would recommend that EPA limit the baseline geochemical data "where feasible, to the next porous formation above the injection zone." EPA should also clarify that the permit applicant may rely upon secondary sources (such as other drilling or geologic records) that relate to and support the data requirement. EPA should also clarify whether the Agency expects applicants to test private wells, where permission is granted, within the AoR for purposes of establishing baseline data. As a general matter, Spectra believes that EPA should not require testing of private wells because sampling results could be affected by flawed well construction or poor integrity, wholly unrelated to the injection project.

Response: The GS regulation, at 146.82(a)(6), requires the owner or operator to submit baseline geochemical data on subsurface geologic formations. EPA is not specifying for which formations this information should be submitted in the rule to allow flexibility, but examples may include the following formations: a) the injection zone, b) the confining zones, c) containment zones above the confining zones in which any potentially migrating CO2 could be trapped, d) all USDWs, and e) any other geologic zone or formation that is important to the proposed monitoring program. The Director has the authority to request additional geochemical data as well. EPA does not expect that testing of private wells will be required in most cases, but clarifies that the Director has authority to require such sampling if it is believed to be necessary to ensure USDW protection.

While each monitoring plan will be site-specific based on data collected during the initial site characterization and baseline geochemical monitoring, it is likely that geochemical sampling mightinclude basic water quality parameters such as pH, specific conductivity, temperature, CO2, alkalinity, major ions, and select heavy metals. Additional parameters may be monitored based on the potential for leaching of minerals or the geochemistry of native fluids.

Commenter Name: Kyle Isakower Letter ID: 0170 Commenter Organization: American Petroleum Institute Comment ID: 24151 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(b)

API Comments: (b) A surface map showing the PROPOSED LOCATIONS FOR the injection well(s) for which a permit is sought and the applicable area of review. Within the area of review, the map must show the number, or name and location of all KNOWN injection wells, producing wells, abandoned wells, plugged wells or dry holes, deep STRATAGRAPHIC boreholes, State or EPA approved subsurface cleanup sites, surface bodies of water, springs, mines (surface and subsurface), quarries, water wells and other pertinent surface features including structures intended for human occupancy and roads. The map should also show faults, if known or suspected. Only information of public record is required to be included on this map;

Rationale: Faults are not shown on maps unless there is a surface expression of the fault. Also, faults are detailed in (d) below and this language appears

redundant.

The word "known" needs to be added to remove any implication that an applicant has to conduct studies to determine the location of wells that are not currently

documented in some fashion.

Response: EPA did not delete “faults” from §146.82(b) because faults may have surface expressions that should be presented on submitted maps to complement the required cross section data. EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Please see the final rule and the discussion of geologic site characterization in the preamble for

additional information.

EPA acknowledges that some smaller fractures may not be detectable during the site characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells and sites can mitigate the potential impacts of unidentified fractures. These include limitations on injection pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible CO2 movement through high-permeability regions (i.e., faults and/or fractures) not

detected in the initial site characterization.EPA believes that a determination about whether or what information may be necessary (for a specific GS project) is outside of the public record and will be site-specific and based on knowledge of the site, data availability, and data quality. For instance, in meeting the requirement to tabulate information on wells in the AoR, the Director has the discretion to require the owner or operator to supplement a data records search if there is reason to believe that the incompleteness of available information could compromise USDW protection from endangerment.

Commenter Name: Kyle Isakower Letter ID: 0170 Commenter Organization: American Petroleum Institute Comment ID: 24153 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(d)(1) and (2)

API Comments: (d) KNOWN information on the geologic structure and hydrogeologic RESERVOIR properties of the proposed storage site and overlying formations, including:

(1) ISOPACH maps and OF THE PROPOSED INJECTION AND CONFINING ZONE(S), A STRUCTURAL CONTOUR MAP HUNG ON THE TOP OF THE PROPOSED

INJECTION ZONE, AND AT LEAST TWO GEOLOGIC cross sections of the area of review SHOWING THE

GEOLOGIC FORMATIONS FROM THE SURFACE TO TOTAL DEPTH.

(2) Location, orientation, and properties of known or suspected

SUBSURFACE faults and fractures that may transect the confining zone(s) in the area of review and a determination that they would not interfere with containment;

Rationale: If the information is not known, it cannot be reported. "Reservoir" and changes to (1) and (2) are technical corrections.

Fractures generally can’t be identified until a well is drilled and evaluated. Even then, only fractures in the immediate vicinity of the wellbore

can be identified.

This responsibility is best left with EPA.

Rule Provision: 146.82(d)(3)

API Comments: (3) Information on seismic history THAT HAVE AFFECTED THE PROPOSED AREA OF REVIEW, INCLUDING KNOWLEDGE OF PREVIOUS SEISMIC EVENTS, including

the presence and depth of seismic sources and a determination that the seismicity would not interfere with containment;

Rationale: Information on seismic history should have some degree of relevance to the project. This responsibility is best left with EPA.Rule Provision: 146.82(d)(4)

API Comments: (4) Data on the depth, areal extent, thickness, mineralogy, porosity, permeability and capillary RESERVOIR pressure of the injection and confining zone(s) WITHIN THE AREA OF REVIEW; including geologic/facies changes based on field data which may include geologic cores, outcrop data, seismic surveys, well logs, and names and lithologic descriptions;

Rationale: Deleted capillary pressure because it is too hard to measure outside of the lab. Using sidewall cores, it may be difficult to determine capillary pressure. Additionally, full cores are not available until after the well being permitted is drilled.

Rule Provision: 146.82(d)(5)

API Comments: (5) KNOWN geomechanical information on fractures, stress, ductility, rock strength, and in situ fluid pressures within the confining zone(s) WITHIN THE AREA OF REVIEW; and

Rationale not provided

Response: EPA acknowledges that some smaller fractures may not be detectable during the site characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells and sites can mitigate the potential impacts of unidentified fractures. These include limitations on injection pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible CO2 movement through high-permeability regions (i.e., faults and/or fractures) not detected in the initial site characterization. Regarding the requirement to determine capillary pressure, EPA recognizes that this information may not be available until after a well has been drilled. EPA revised §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)). Final information on injection zone pressures would be required following drilling of the well, at §146.82(c)(4).

EPA disagrees that information submitted with Class VI permit applications should be limited to known (i.e., previously available) data. Site-specific conditions may affect the suitability of a proposed site. Therefore the owner or operator must provide to the Director the necessary preliminary information to support a permit decision.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24413 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(b)

Proposed CCS Group Recommendations: (b) A SURFACE map showing the PROPOSED LOCATIONS FOR the injection well(s) for which a permit is sought and theapplicable area of review. Within the area of review, the map must show the number, or name and location of all KNOWN injection wells, producing wells, abandoned wells, plugged wells or dry holes, deep stratigraphic boreholes, State or EPA approved subsurface cleanup sites, surface bodies of water, springs, mines (surface and subsurface), quarries, water wells and other pertinent surface features including structures intended for human occupancy and roads. The map should also show faults, if known or suspected. Only information of public record is required to be included on this map;

Basis for CCS Group Comments: Faults are not shown on maps unless there is a surface expression of the fault. Also, faults are detailed in (d) below and this language appears redundant.

The word "known" needs to be added to remove any implication that an applicant has to conduct studies to determine the location of wells that are not currently

documented in some fashion.

Response: EPA disagrees that information submitted with Class VI permit applications should be limited to known (i.e., previously available) data. Site-specific conditions may affect the suitability of a proposed site. Therefore the owner or operator must provide to the Director the necessary preliminary information to support a permit decision.

EPA did not delete “faults” from §146.82(b) because faults may have surface expressions, which should be presented on submitted maps in order to complement the required cross-section data. EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. Please see the final rule and the discussion of geologic site characterization in the preamble for additional information.

EPA believes that a determination about whether or what information may be necessary (for a specific GS project) is outside of the public record will be site-specific and based on knowledge of the site, data availability, and data quality. For instance, in meeting the requirement to tabulate information on wells in the AoR, the Director has the discretion to require the owner or operator to supplement a data records search if there is reason to believe that the incompleteness of available information could compromise USDW protection from endangerment. EPA acknowledges that some smaller fractures may not be detectable during the site characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or suspected faults and fractures (i.e., not all fractures).

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24415 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(d)Proposed CCS Group Recommendations: (d) KNOWN information on the geologic structure and hydrogeologic RESERVOIR properties of the proposed storage site and overlying formations, including:

(1) ISOPACH maps and OF THE PROPOSED INJECTION AND CONFINING ZONE(S), A

STRUCTURAL CONTOUR MAP HUNG ON THE TOP OF THE PROPOSED INJECTION ZONE, AND AT

LEAST TWO GEOLOGIC cross sections of the area of review SHOWING THE GEOLOGIC

FORMATIONS FROM THE SURFACE TO TOTAL DEPTH.

(2) Location, orientation, and properties of known or suspected SUBSURFACE

faults and fractures that may transect the confining zone(s) in the area of review and a determination that they would not interfere with containment;

Basis for CCS Group Comments: If the information is not known, it cannot be reported.

"Reservoir" and changes to (1) and (2) are technical corrections.

Fractures generally can't be identified until a well is drilled and evaluated. Even then, only fractures in the immediate vicinity of the well bore can be

identified.

Response: EPA acknowledges that some smaller fractures may not be detectable during the site characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells and sites can mitigate the potential impacts of unidentified fractures. These include limitations on injection pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible CO2 movement through high-permeability regions (i.e., faults and/or fractures) not detected in the initial site characterization.

As described above, EPA disagrees that information submitted with Class VI permit applications should be limited to known (i.e., previously available) data. Site-specific conditions may affect the suitability of a proposed site. Therefore the owner or operator must provide to the Director the necessary preliminary information to support a permit decision. Please see the final rule and the discussion of geologic site characterization in the preamble for additional information.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24416 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(d)(3)

Proposed CCS Group Recommendations: (3) Information on seismic history THAT HAVE AFFECTED THE PROPOSED AREA OF REVIEW, INCLUDING KNOWLEDGE OF PREVIOUS

SEISMIC EVENTS, including the presence and depth of seismic sources and a determination that the seismicity would not interfere with containment;Basis for CCS Group Comments: Information on seismic history should have some degree of relevance to the project.

Response: EPA believes that consideration of local and regional seismicity is important and this type of review is relevant to every project. The site characterization provisions in the GS rule, including a review of the local and regional geology, and detailed review of any known or potential seismically active terrain in the vicinity of a proposed GS site, are necessary to minimize the potential for induced seismic events or the reactivation of faults, which are a known potential risk associated with underground injection and are addressed in all aspects of the UIC regulations.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24417 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(d)(4)

Proposed CCS Group Recommendations: (4) Data SUFFICIENT TO DEMONSTRATE THE EFFECTIVENESS OF THE INJECTION AND CONFINING ZONE(S), INCLUDING DATA ON

THE DEPTH, AREAL EXTENT, THICKNESS, MINERALOGY, POROSITY, VERTICAL

PERMEABILITY RESERVOIR PRESSURE AND OF THE INJECTION AND CONFINING ZONE(S) WITHIN THE

AREA OF REVIEW; INCLUDING GEOLOGIC CHANGES BASED ON FIELD DATA WHICH MAY

INCLUDE GEOLOGIC CORES, OUTCROP DATA, SEISMIC SURVEYS, WELL LOGS, CAPILLARY

PRESSURE TESTS AND NAMES and lithologic descriptions;

Basis for CCS Group Comments: Capillary pressure is too hard to measure outside the lab; how comparable are lab results to what goes into the ground. Sidewall core may not be sufficient to do this, and it is difficult to core the whole of the confining and injection zones. Rewording keeps the usefulness of capillary pressure in the provision without making it a mandatory use.

Response: EPA acknowledges that laboratory methods are standard for determining capillary pressures regardless of formation permeability and that in situ measurements would require drilling of a well. However, EPA also anticipates that test wells will be drilled to support geologic site characterization of the proposed GS sites and can be used to collect subsurface samples (for laboratory determination of capillary pressure) and take other necessary measurements.

EPA recognizes that this information may not be available until after a well has been drilled. EPA revised §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)). Final information on injection zone pressures would be required following drilling of the well, at §146.82(c)(4).EPA believes that information on capillary entry pressure is necessary and appropriate. Capillary entry pressure measurements on core samples can quantify the amount of buoyant force the confining zone can maintain before failure (World Resources Institute, 2008).

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24418 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(d)(5)

Proposed CCS Group Recommendations: (5) KNOWN geomechanical information on fractures, stress, ductility, rock strength, and in situ fluid pressures within the confining zone(s) WITHIN THE AREA OF REVIEW; and

Basis for CCS Group Comments: Clarification.

Rule Provision: 146.82(d)(6)

Proposed CCS Group Recommendations: Delete item 6 because this issue is covered under other sections such as (b).

Response: EPA acknowledges the comment but did not make the suggested edits. The Agency believes that the site characterization requirements at §146.82, including geomechanical information and geologic and topographic maps and cross sections, are essential to proper siting of a GS well and are the foundation for a detailed understanding of the local and regional geology, and that the owner or operator should collect this information, regardless of whether it is known in advance of the siting process. Collecting and evaluating this data supports important evaluations regarding the suitability of the site to receive and contain injected CO2.

EPA recognizes that this information may not be available until after a well has been drilled. EPA revised §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)). Final information on injection zone pressures would be required following drilling of the well, at §146.82(c)(4).

Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24641 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(b)

Anadarko Petroleum Corporation (APC) Comments: (b) A surface map showing the PROPOSED LOCATIONS FOR the injection well(s) for which a permit is sought and the applicable area of review. Within the area of review, the map must show the number, or name and location of all KNOWN injection wells, producing wells, abandoned wells, plugged wells or dry holes, deep STRATAGRAPHIC boreholes, State or EPA approved subsurface cleanup sites, surface bodies of water, springs,mines (surface and subsurface), quarries, water wells and other pertinent surface features including structures intended for human occupancy and roads. The map should also show faults, if known or suspected. Only information of public record is required to be included on this map;

Rationale: Faults are not shown on maps unless there is a surface expression of the fault. Also, faults are detailed in (d) below and this language appears

redundant.

Known needs to be added to remove any implication that an applicant has to conduct stuides to determine wells that are not currently documented in some

fashion.

Response: Regarding the comment that EPA delete mention of faults on surface maps, EPA believes that if faults have surface expressions, they should be presented on maps submitted; this information would complement the required cross section data. EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

EPA disagrees that the information that is submitted to support a Class VI permit application should be limited to known/available data. The Agency believes that the site characterization requirements at §146.82, including geomechanical information and geologic and topographic maps and cross sections, are essential to proper siting of a GS well and are the foundation for a detailed understanding of the local and regional geology, and that the owner or operator should collect this information, regardless of whether it is known in advance of the siting process. Collecting and evaluating this data supports important evaluations regarding the suitability of the site to receive and contain injected CO2. Please see the final rule and the discussion of geologic site characterization in the preamble for additional information.

EPA acknowledges that some smaller fractures may not be detectable during the site characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells and sites can mitigate the potential impacts of unidentified fractures. These include limitations on injection pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible CO2 movement through high-permeability regions (i.e., faults and/or fractures) not

detected in the initial site characterization.

EPA also believes that a determination about whether or what information may be necessary (for a specific GS project) is outside of the public record will be site-specific and based on knowledge of the site, data availability, and data quality. For instance, in meeting the requirement to tabulate information on wells in the AoR, the Director has the discretion to require the owner or operator to supplement a data records search if there is reason to believe that the incompleteness of available information could compromise USDW protection from endangerment.Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24643 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(d)

Anadarko Petroleum Corporation (APC) Comments: (d) KNOWN information on the geologic structure and hydrogeologic RESERVOIR properties of the proposed storage site and overlying formations, including:

(1) ISOPACH maps and OF THE PROPOSED INJECTION AND CONFINING ZONE(S), A

STRUCTURAL CONTOUR MAP HUNG ON THE TOP OF THE PROPOSED INJECTION ZONE, AND AT

LEAST TWO GEOLOGIC cross sections of the area of review SHOWING THE GEOLOGIC

FORMATIONS FROM THE SURFACE TO TOTAL DEPTH.

(2) Location, orientation, and properties of known or suspected SUBSURFACE

faults and fractures that may transect the confining zone(s) in the area of review and a determination that they would not interfere with containment;

Rationale: If the information is not known, it cannot be reported.

"Reservoir" and changes to (1) and (2) are technical corrections.

Fractures generally can’t be identified until a well is drilled and evaluated. Even then, only fractures in the immediate vicinity of the wellbore can be

identified.

Response: EPA believes that all of the site characterization requirements at 146.82, including information on faults and fractures, are essential to proper siting of a GS well and are the foundation for a detailed understanding of the local and regional geology, and that the owner or operator should collect this information, regardless of whether it is known in advance of the siting process. Collecting and evaluating this data supports important evaluations regarding the suitability of the site to receive and contain injected CO2.

EPA recognizes that this information may not be available until after a well has been drilled. EPA revised §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)). Final information on injection zone pressures would be required following drilling of the well, at §146.82(c)(4).

EPA acknowledges that some smaller fractures may not be detectable during the site characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells and sites can mitigate the potential impacts of unidentified fractures. These include limitations on injection pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible CO2 movement through high-permeability regions (i.e., faults and/or fractures) not

detected in the initial site characterization.Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24644 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision:146.82(d)(3)

Anadarko Petroleum Corporation (APC) Comments: (3) Information on seismic history THAT HAVE AFFECTED THE PROPOSED AREA OF REVIEW INCLUDING

KNOWLEDGE OF PREVIOUS SEISMIC EVENTS AND HISTORY OF THESE EVENTS, including the presence and depth of seismic sources and a determination that the seismicity would not interfere with containment;

Rationale: Information on seismic history should have some degree of relevance to the project.

Response: EPA believes that consideration of local and regional seismicity is important and this type of review is relevant to every project. The site characterization provisions in the GS rule, including a review of the local and regional geology, and detailed review of any known or potential seismically active terrain in the vicinity of a proposed GS site are necessary to minimize the potential for induced seismic events or the reactivation of faults, which are a known potential risk associated with injection and are addressed in all aspects of the UIC regulations.

Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24645 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(d)(4) & (5)

Anadarko Petroleum Corporation (APC) Comments: (4) Data on the depth, areal extent, thickness, mineralogy, porosity, permeability and capillary RESERVOIR pressure of the injection and confining zone(s) WITHIN THE AREA OF REVIEW; including geologic/facies changes based on field data which may include geologic cores, outcrop data, seismic surveys, well logs, and names and lithologic descriptions;

(5) KNOWN geomechanical information on fractures, stress, ductility, rock strength, and in situ fluid pressures within the confining zone(s) WITHIN THE AREA OF REVIEW; and

Rationale: Deleted capillary pressure because it is too hard to measure outside of the lab. Using sidewall cores, it may be difficult to determine capillary pressure. Additionally, full cores are not available until after the well being permitted is drilled.

Response: EPA acknowledges the comment but did not make the suggested edits. The Agency believes that the site characterization requirements at §146.82, including geomechanical information and geologic and topographic maps and cross sections, are essential to proper siting of a GS welland are the foundation for a detailed understanding of the local and regional geology, and that the owner or operator should collect this information, regardless of whether it is known in advance of the siting process. Collecting and evaluating this data supports important evaluations regarding the suitability of the site to receive and contain injected CO2.

EPA acknowledges that laboratory methods are standard for determining capillary pressures regardless of formation permeability and that in situ measurements would require drilling of a well. However, EPA also anticipates that test wells will be drilled to support geologic site characterization of the proposed GS sites and can be used to collect subsurface samples (for laboratory determination of capillary pressure) and take other necessary measurements.

EPA recognizes that this information may not be available until after a well has been drilled. EPA revised §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)). Final information on injection zone pressures would be required following drilling of the well, at §146.82(c)(4).

EPA believes that information on capillary entry pressure is necessary and appropriate. Capillary entry pressure measurements on core samples can quantify the amount of buoyant force the confining zone can maintain before failure (World Resources Institute, 2008).

Commenter Name: Diane VanDe Hei Letter ID: 0213 Commenter Organization: Association of Metropolitan Water Agencies (AMWA) Comment ID:

22936

Comment: o Data can and should be gathered immediately and more core analysis should be required in the permitting process -- specifically for key formations and for water/rock/gas interaction.

Response: The Agency agrees and believes that the site characterization requirements at §146.82 are essential to proper siting of a GS well and are the foundation for a detailed understanding of the local and regional geology. Collecting and evaluating geochemical data in and around the CO2 injection zone, as required in §146.82(a)(6), serves several purposes. This baseline geochemical data can help predict geochemical reactions between the injectate, reservoir geology, and formation fluids. Such reactions can lead to dissolution and precipitation of minerals which affect formation porosity, which in turn can affect required injection pressure (Sminchak and Gupta, 2002) and transport of fluid within the formation. While the confining layer is the primary barrier to CO2 movement into a USDW, multiple barriers are important and changes in injection pressure and fluid movement may compromise those barriers. An increase in injection pressure due to reduced porosity, in particular, can lead to fracturing of the confining layer and potentially allow fluid movement outside of the injection zone. Losses in injectivity because of geochemical reactions may also require additional injection wells and further penetrations in the confining layer that can become pathways for fluid migration.

Commenter Name: Philip Papadeas Letter ID: 0238 Commenter Organization: Sandia Technologies, LLC Comment ID: 23349

Comment: §146.82Re: Collection of detailed geologic data. The collection of this data is the operator’s burden, and should be built on accumulation of all known geologic material in the area. Sandia believes this information is valuable for modeling, site characterization and geologic profile of the injection- confinement system. If none is present, then the operator must demonstrate via stratigraphic test or an information well all pertinent formation cores, not only of proposed permeable injection intervals, but overlying buffer intervals, confining zone cores, and formations that will act as hydraulic seals.

One proposed approach is for the Agency to make the first Permitted injection well conditional, collecting the required data and providing this to the EPA under an adjusted permit to demonstrate that the data matches conservative assumptions used in reservoir and geologic modeling. The follow-up wells should collect in-fill well data on geomechanics and confirm data obtained from the first well. Reduced data collection should be employed for all subsequent wells on the site, since adequate will exit from these early wells for the storage operator and EPA to make a detailed assessment of the capability of the site.

This idea is similar to many approaches on ‘greenfield’ sites followed via Class I well Permitting by EPA. A secondary approach is for the operator to include this data acquisition into their project costs for stratigraphic test data, cores, logs, pressures, reservoir testing to demonstrate the suitability of the injection and confining horizons. The burden

Response: EPA agrees and believes that the extensive requirements for geologic site characterization (at §146.82), AoR evaluation (§146.84), and testing of the well during drilling (§146.87) are appropriate to ensure that permitting authorities have the necessary information to evaluate whether a specific site will allow safe injection of CO2. EPA adds that submittal and review of monitoring data (as required at §146.90) and the AoR reevaluation process (§146.84(e)) will provide an opportunity for an ongoing review of the site and a dialogue between the Director and the owner or operator to ensure that the project is being operated in a manner that protects USDWs from endangerment.

EPA acknowledges that early pilot projects may focus on gathering data to inform GS technology. However, EPA believes that a detailed geological site characterization of every GS site (as required under §146.82) is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for the unique nature of injecting large volumes of CO2 into a variety of geological formations for long-term storage. EPA adds that, if data on a formation or site collected in connection with an earlier project can support a geologic characterization, the Director has discretion to accept this data, provided it is sufficient to demonstrate site suitability.

Commenter Name: Mark Bohrer Letter ID: 0241 Commenter Organization: North Dakota Industrial Commission Comment ID: 23280

Comment: Capillary pressure is difficult to measure outside a lab and would not be available if no wells have been drilled in a project. Do not see necessity forthis information.

Response: EPA acknowledges that laboratory methods are standard for determining capillary pressures regardless of formation permeability and that in situ measurements would require drilling of a well. However, EPA also anticipates that test wells will be drilled to support geologic site characterization of the proposed GS sites and can be used to collect subsurface samples (for laboratory determination of capillary pressure) and take other necessary measurements. EPA believes that information on capillary entry pressure is necessary and appropriate. Capillary entry pressure measurements on core samples can quantify the amount of buoyant force the confining zone can maintain before failure (World Resources Institute, 2008).

EPA recognizes that this information may not be available until after a well has been drilled. EPA revised §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)). Final information on injection zone pressures would be required following drilling of the well, at §146.82(c)(4).

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24869 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: EPA Proposal: (b) A map showing the injection well(s) for which a permit is sought and the applicable area of review. Within the area of review, the map must show the number, or name and location of all injection wells, producing wells, abandoned wells, plugged wells or dry holes, deep stratigraphic boreholes, State or EPA approved subsurface cleanup sites, surface bodies of water, springs, mines (surface and subsurface), quarries, water wells and other pertinent surface features including structures intended for human occupancy and roads. [Highlighted text: The map should also show faults, if known or suspected.] Only information of public record is required to be included on this

map;

GWPC Recommendations: (b) A surface map showing the proposed locations for the injection well(s) for which a permit is sought and the applicable area of review. Within the area of review, the map must show the number, or name and location of all known injection wells, producing wells, abandoned wells, plugged wells or dry holes, deep stratigraphic boreholes, State or EPA approved subsurface cleanup sites, surface bodies of water, springs, mines (surface and subsurface), quarries, water wells and other pertinent surface features including structures intended for human occupancy and roads. Only information of public record is required to be included on this map;

Rationale: Insert "known" before "injection"

Suggests removing highlighted text as faults are not shown on maps unless there is a surface expression of the fault. Also, faults are detailed in (d) below and this language appears redundant.Response: Regarding the comment that EPA delete mention of faults on surface maps, EPA believes that if faults have surface expressions, they should be presented on maps submitted; this information would complement the required cross section data. EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. Please see the final rule and the discussion of geologic site characterization in the preamble for additional information.

EPA acknowledges but did not make the suggested edits. EPA believes that all of the site characterization requirements at §146.82, including geomechanical information and geologic and topographic maps and cross sections, are essential to proper siting of a GS well and are the foundation for a detailed understanding of the local and regional geology, and that the owner or operator should collect this information, regardless of whether it is known in advance of the siting process. Collecting and evaluating this data supports important evaluations regarding the suitability of the site to receive and contain injected CO2.

EPA acknowledges that some smaller fractures may not be detectable during the site characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells and sites can mitigate the potential impacts of unidentified fractures. These include limitations on injection pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible CO2 movement through high-permeability regions (i.e., faults and/or fractures) not

detected in the initial site characterization.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24871 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: EPA Proposal: (d) Information on the geologic structure and hydrogeologic properties of the proposed storage site and overlying formations, including:

(1) Maps and cross sections of the area of review;

(2) Location, orientation, and properties of known or suspected faults and fractures that may transect the confining zone(s) in the area of review and a determination that they would not interfere with containment;

GWPC Recommendations: (d) Sufficient information on the geologic structure and reservoir properties of the proposed storage site and overlying formations, including:

(1) Isopach maps of the proposed injection and confining zone(s), a structural contour map aligned with the top of the proposed injection zone, and at least two geologic cross sections of the area of review reasonably perpendicular to each other showing the geologic formations from the surface to total depth.(2) Location, orientation, and properties of known or suspected subsurface faults that may transect the confining zone(s) in the area of review and a determination that they would not interfere with containment;

Rationale: Fractures can be incredibly small and it is virtually impossible to

find all subsurface fractures. The GWPC also recommends addition of the term "Sufficient" before the information sought in (d) as this is more precise.

Response: EPA acknowledges that some smaller fractures may not be detectable during the site characterization process, and clarifies that §146.82(a)(3)(ii) requires the owner or operator to submit data on known or suspected faults and fractures (i.e., not all fractures). Other requirements for GS injection wells and sites can mitigate the potential impacts of unidentified fractures. These include limitations on injection pressures to avoid propagation of existing fractures in the confining zone (§146.88(a)), collection and assessments of CO2 monitoring data at the site, and AoR reevaluations (§146.84(e)) to assess possible CO2 movement through high-permeability regions (i.e., faults and/or fractures) not detected in the initial site characterization.

EPA disagrees with the other suggested edits because the GS rule, as written, affords flexibility to owners or operators and Directors to tailor the site characterization process to the unique features of the site. Please see the final rule and the discussion of geologic site characterization in the preamble

for additional information.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24872 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: EPA Proposal: (3) Information on seismic history including the presence and depth of seismic sources and a determination that the seismicity would not interfere with containment;

(4) Data on the depth, areal extent, thickness, mineralogy, porosity, permeability and capillary pressure of the injection and confining zone(s); including geology/facies changes based on field data which may include geologic cores, outcrop data, seismic surveys, well logs, and names and lithologic descriptions;

(5) Geomechanical information on fractures, stress, ductility, rock strength, and in situ fluid pressures within the confining zone; and

GWPC Recommendations: (3) Information on seismic history that have affected the proposed area of review including knowledge of previous seismic events and history of these events, including the presence and depth of seismic sources and a determination that the seismicity would not compromise containment;

(4) Data sufficient to demonstrate the effectiveness of the injection and confining zone(s), including data on the depth, areal extent, thickness, mineralogy, porosity, vertical permeability reservoir pressure and of the injection and confining zone(s) within the area of review; including geologicchanges based on field data which may include geologic cores, outcrop data, seismic surveys, well logs, capillary pressure tests and names and lithologic descriptions;

(5) Geomechanical information on the confining zone(s) within the area of review; and

Rationale: Capillary pressure is too hard to measure outside the lab; how comparable are lab results to what goes into the ground. Sidewall core may not be sufficient to do this, and it is difficult to core the whole of the confining and injection zones. Rewording keeps the usefulness of capillary pressure in the provision without making it a mandatory use.

Response: EPA acknowledges that laboratory methods are standard for determining capillary pressures regardless of formation permeability and that in situ measurements would require drilling of a well. However, EPA also anticipates that test wells will be drilled to support geologic site characterization of the proposed GS sites and can be used to collect subsurface samples (for laboratory determination of capillary pressure) and take other necessary measurements. EPA believes that information on capillary entry pressure is necessary and appropriate. Capillary entry pressure measurements on core samples can quantify the amount of buoyant force the confining zone can maintain before failure (World Resources Institute, 2008).

EPA recognizes that this information may not be available until after a well has been drilled. EPA revised §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)). Final information on injection zone pressures would be required following drilling of the well, at §146.82(c)(4).

Commenter Name: Cynthia Lane Letter ID: 0528 Commenter Organization: American Water Works Association (AWWA) Comment ID: 21387 Other EPA Comment Codes and Descriptions: 3110 2.1.1 Proposed siting requirements (i.e., injection/confining zones, trapping mechanism)

Comment: provide for a consistent application of the monitoring requirements. Another area of concern is often the lack of good records of abandoned wells that tap the very same strata used for carbon dioxide sequestration. There is a presumption that even states with oil and gas or mining operation have excellent, up to date reports and have maps indicating abandoned wells and mines. This is not always the case. Many states with extractive industries do have maps and surveys, but they are not sufficiently precise for geologic sequestration. Studies have shown that injected carbon dioxide will be able to

find the abandoned wells. These wells allow for the transmission of the carbon dioxide out of the confined aquifer into potential USDW's and then eventually to

the surface.

Response: EPA acknowledges that areas previously used for drilling for oil, gas, or minerals pose potential challenges for GS. However, regardless of the history of the site, the owner or operator must provide to the Director extensive information demonstrating the adequacy of the site to contain the CO2 (§146.82). This information includes the location of all existing or abandoned wells withinthe modeled AoR (§§146.82(a)(2) and 146.84(c)(2)) and the location, orientation, and properties of all known or existing faults (§146.82(a)(3)(ii)). The Director may require ground or airborne surveys to identify active or abandoned wells if there is reason to believe, based on knowledge of the site or of available data bases, that the available information is not adequate for assessing a proposed GS site (§146.84(c)(2)). The Director may also require additional surveys and tests to identify and characterize fractures. After reviewing the permit information submitted, the Director may deny the application if there is reason to believe that USDWs may be endangered.

Comment Code: 3140 2.1.4 Comments that the proposed geologic data requirements are too stringent



### Individual Comments

Commenter Name: James Rower Letter ID: 0173 Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23460 Other EPA Comment Codes and Descriptions: 1210 1.1.1 Comments about the proposed rule

Comment: • In many instances the proposed requirements for Class VI CO2 GS wells are unnecessarily more stringent than existing requirements for other well classes under the UIC Program. While it is essential that the Final Rule be protective of underground sources of drinking water ("USDWs"), many of the more rigorous requirements proposed for Class VI wells are not warranted by findings of unique risks posed by CO2 GS wells. The Final Rule should craft requirements that protect USDWs while avoiding the imposition of unnecessary costs or the creation of an unfounded negative public perception of CO2 GS projects.

Response: EPA disagrees that the requirements at §146.82 are too stringent and believes that a detailed geological site characterization is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for the unique nature of injecting large volumes of CO2 into a variety of geological formations for long-term storage.

The mission of the UIC program and the goal of the GS regulation is to protect USDWs from endangerment, and every aspect of the GS rule is designed toward that end. Therefore, EPA disagrees that any of these protective requirements are unnecessary, and clarifies that waiving any of the requirements would not be acceptable. The GS regulation allows flexibility where appropriate. Certain requirements (e.g., the need to characterize additional confining layers) are at the Director's discretion (§146.83(b)), based on his or her understanding of a particular site.

EPA disagrees that the requirements would negatively affect public perception of CO2 GS projects. Rather, EPA believes that a demonstration to the public that extensive data have been collected and evaluated would likely improve confidence in the project and help address public questions and

concerns.

Commenter Name: James Rower Letter ID: 0173 Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23465Other EPA Comment Codes and Descriptions: 3300 2.2.1 Delineating the AoR/Modeling CO2

movement
Comment: • The Final Rule must not make the application process overly burdensome or unrealistic by requiring detailed information that may not be available at the time of the initial application; instead, the Final Rule should allow for submission of updated information regarding a CO2 GS well and its AoR as that

information becomes available.

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of information to be submitted. In addition, §146.82 in the final rule is similar to the permit application requirements for other injection well classes, which could help avoid confusion about how to meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to be submitted before operation of the well is authorized are very similar to those for Class I wells, with modifications and additions that address the unique challenges and types of data collected for GS

wells.

Commenter Name: James Rower Letter ID: 0173 Commenter Organization: Utility Solid Waste Activities Group (USWAG) Comment ID: 23501

Comment: For example, some requirements for information related to geologic structure and hydrogeologic properties of the proposed storage site and overlying formations may be unavailable until drilling commences, including "data on the depth, areal extent, thickness, mineralogy, porosity, permeability and capillary pressure ... geologic cores, outcrop data, seismic surveys, ... and lithologic descriptions" of the injection and confining zones (proposed § 146.82(d)(4)) and "geomechanical information on fractures, stress, ductility, rock strength, and in situ fluid pressures within the confining zone" (proposed § 146.82(d)(5)). 73 Fed. Reg. at 43536. While some of this information may be available during the permit application process, other details will be unavailable prior to drilling.

To require detailed information that may either be unreliable, because it is based on unrealistic or unfounded predictions, or may simply be unavailable could delay the permitting process and have an overall chilling effect on CO2 GS projects. EPA should craft these requirements with flexibility and require in the initial permit application only that information which is necessary to determine whether issuance of a Class VI permit is appropriate. Submission of additional information as it becomes available - whether through well drilling, construction, operation, reevaluation, or corrective action - will allow for more reliable data that will in turn ensure greater protection of USDWs.

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. Inresponse to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of information to be submitted. In addition, section §146.82 in the final rule is similar to the permit application requirements for other injection well classes, which could help avoid confusion about how to meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to be submitted before operation of the well is authorized are very similar to those for Class I wells, with modifications and additions that address the unique challenges and types of data

collected for GS wells.

Commenter Name: Robert J. Finley Letter ID: 0180 Commenter Organization: Illinois State Geological Survey Comment ID: 23621 Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information (40 CFR 146.82)

Comment: (d) (4) (5)

This section calls for data that is almost certainly incompletely available and cannot be acquired except from a permitted well. Geomechanical information on the confining zone almost certainly will not exist until storage projects have been completed in a basin. There is no economic motive to develop such data. Acquiring a representative and accurate in situ fluid pressure in a confining zone may be impossible given that a confining zone should not be permeable and therefore its testing with wireline or drillstem tools is highly questionable.

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of information to be submitted. In addition, section §146.82 in the final rule is similar to the permit application requirements for other injection well classes, which could help avoid confusion about how to meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to be submitted before operation of the well is authorized are very similar to those for Class I wells, with modifications and additions that address the unique challenges and types of data

collected for GS wells.

EPA adds that the presence or absence of an economic motive for generating the data is outside the scope of the rulemaking. The owner or operator must submit all of the data required at §146.82 in order to support a determination about the suitability of the site, regardless of an economic incentive for gathering that data.Commenter Name: Robert J. Finley Letter ID: 0180 Commenter Organization: Illinois State Geological Survey Comment ID: 23622 Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information (40 CFR 146.82)

Comment: (g)

Reference is made to geochemical data on subsurface formations with no indication of which formation or how many. This could be interpreted to mean all formations within the sedimentary column both above and below an injection zone at a given site. Much of such data may be both irrelevant and unavailable and it will be extremely costly to core and sample every formation in the area of a proposed site.

Response: The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate and transport model development (e.g., by providing appropriate input parameters), and provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. The baseline geochemical information will allow the owner or operator and permitting authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid movement.

EPA clarifies that the rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion to require geochemical analysis of additional subsurface zones if in the Director's opinion they are necessary for the protection of USDWs from endangerment.

EPA clarifies that operators would not necessarily need to core and sample each formation in the area of a proposed GS site. If relevant, comprehensive information about the site exists (e.g., from earlier geologic studies of the area), the Director may, at his/her discretion, allow its use in the site characterization for the GS project. In addition, §146.87(b) allows cores from nearby wells to be submitted if the owner or operator can demonstrate that core retrieval is not possible and that cores from nearby wells are representative of conditions at the GS well. EPA clarifies that, at a minimum, cores of injection zones and confining zones, and samples of formation fluids must be submitted. §146.87(b) gives the Director authority to require the owner or operator to core other formations in the borehole if necessary to provide sufficient geologic information to verify that the site is suitable for GS. EPA adds that §146.87(b) allows the owner or operator to submit whole cores or sidewall cores of the injection zone and confining system.

Additionally, EPA acknowledges comments regarding the costs associated with thoroughly evaluating a potential GS site. The Agency believes the requirements for a thorough geologic site characterization for a GS project are necessary to protect USDWs from endangerment.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24330 Other EPA Comment Codes and Descriptions: 3110 2.1.1 Proposed siting requirements (i.e., injection/confining zones, trapping mechanism)

Comment: 1. Site EvaluationThe preamble appears to suggest the need for an elaborate evaluation of site conditions to address concerns related to seismicity and potential geochemical interactions. In fact, however, seismicity and geochemical impacts are issues that are easily addressed in the GS context, and requirements for unnecessarily elaborate analysis would serve only to burden and impede the development of GS projects.

Concerns with respect to seismicity are frequently raised in the injection well context, but there is ample experience demonstrating that such risks are modest and easily addressed through appropriate injection pressure limitations. Similarly, geologic compatibility - while it can present issues in some contexts - is unlikely to present any serious problems in the GS context. These conclusions are confirmed by decades of experience with literally thousands Class II CO2 injection wells injecting hundreds of millions of tons of CO2.

The apparent extent of concern about geochemical compatibility is particularly hard to understand. Although it is true that injection of CO2 can be expected to lead to the formation of carbonic acid, the resulting carbonic acid is only weakly corrosive and - as experience with the injection of extremely corrosive hazardous wastes demonstrates - cannot reasonably be expected to cause any breach of containment that would endanger a USDW. The proposed rule expresses specific concern about geochemical reactions that could alter the composition of the injected CO2 stream - particularly through the mobilization of contaminants that occur naturally in the injection zone - but such concerns are essentially immaterial because the specific composition of the CO2 stream matters little as long as the CO2 stream remains confined.

Response: The Agency believes that the site characterization requirements at §146.82 are essential to proper siting of a GS well and are the foundation for a detailed understanding of the local and regional geology. Collecting and evaluating geochemical data in and around the CO2 injection zone, as required in §146.82(a)(6), serves several purposes. This baseline geochemical data can help predict geochemical reactions between the injectate, reservoir geology, and formation fluids. Such reactions can lead to dissolution and precipitation of minerals which affect formation porosity, which in turn can affect required injection pressure (Sminchak and Gupta, 2002) and transport of fluid within the formation. While the confining layer is the primary barrier to CO2 movement into a USDW, multiple barriers are important and changes in injection pressure and fluid movement may compromise those barriers. An increase in injection pressure due to reduced porosity, in particular, can lead to fracturing of the confining layer and potentially allow fluid movement outside of the injection zone. Losses in injectivity because of geochemical reactions may also require additional injection wells and further penetrations in the confining layer that can become pathways for fluid migration.

EPA disagrees with the comment that the composition of the CO2 stream is not important. Information about the composition of the CO2 stream informs decisions about the appropriate design and construction of the well, the potential for adverse mineral reactions in the subsurface geologic formations, and appropriate testing and monitoring parameters.

EPA disagrees that injectivity is not an important consideration. While increasing storage capacity is not the intent of the UIC requirements, EPA believes that maximizing the amount of CO2 that canbe injected through a single well may reduce the need for additional injection wells, which reduce the potential for unacceptable fluid movement and improve USDW protection from endangerment.

Finally, EPA disagrees that consideration of local and regional seismicity is not important. The site characterization provisions in the GS rule, including a review of the local and regional geology, and detailed review of any known or potential seismically active terrain in the vicinity of a proposed GS site are necessary to minimize the potential for induced seismic events or the reactivation of faults, which are a known potential risk associated with injection and are addressed in all aspects of the UIC regulations.

Commenter Name: John King Letter ID: 0211 Commenter Organization: Shell Exploration and Production Company (SEPCo) Comment ID:

22764

Comment: A. Geologic Siting Requirements

The preamble to the proposed rule outlines normal site selection criteria for injection well projects, including the need to identify an injection zone withsufficient permeability, porosity, thickness and lateral extent and a lowpermeability confining zone with sufficient thickness and lateral extent to protect overlying USDWs. 73 Fed. Reg. at 43505. These are familiar and appropriate requirements, and they appear to be appropriately embodied in the regulatory text proposed for codification at 40 C.F.R. 146.83(a). Unfortunately, the preamble goes on to suggest the need for extraneous detail in the evaluation of site conditions. In addition, the rule text proposed for codification at 40 C.F.R. 146.83(b) would allow the Administrator apparently unlimited discretion to impose additional siting requirements that go beyond those necessary to ensure protection of USDWs.

Recommendation:

EPA should omit the latter requirement of extraneous details, and instead seek to develop clear performance standards as detailed in the American Petroleum Institute’s submission regarding site characterization. The need for adequate site characterization cannot be understated, however it’s is critical that EPA works to clarify the site evaluation needs and ensure that they are no more elaborate than necessary to ensure protection of USDWs.

1. Site Evaluation

The preamble appears to suggest that there may be a need for an elaborate evaluation of site conditions to address concerns related to seismicity and potential geochemical interactions. In fact, however, seismicity and geochemical compatibility are issues that are easily addressed in the GS context, and requirements for unnecessarily elaborate analysis would serve only to burden and impede the development of GS projects.

Concerns with respect to seismicity are frequently raised in the injection well context, but there is ample experience demonstrating that such risks are modest and easily addressed through appropriate injection pressure limitations.Similarly, geologic compatibility -- while it can present issues in some contexts -- is unlikely to present any serious problems in the GS context. These conclusions are confirmed by decades of experience with thousands of Class II CO2 injection wells injecting hundreds of millions of tons of CO2.

While it is true that injection of CO2 can be expected to lead to the formation of carbonic acid, the resulting carbonic acid is only weakly corrosive and -- as experience with the injection of extremely corrosive hazardous wastes demonstrates -- cannot reasonably be expected to cause any breach of containment that would endanger a USDW. The proposed rule expresses specific concern about geochemical reactions that could alter the composition of the injected CO2 stream -- particularly through the mobilization of contaminants that occur naturally in the injection zone -- but such concerns are immaterial because the specific composition of the CO2 stream matters little as long as the CO2 remains confined. Another theoretical concern relates to the potential for geochemical changes to contribute to the plugging of pore spaces in the injection zone. However, experience with Class II CO2 injection confirms pore plugging should not pose any practical problems in the CO2 injection context because of the relative weakness of carbonic acid and the time and transport distance required for carbonic acid to form and for any subsequent geochemical changes to occur. Even if pore plugging were to manifest it, it would occur deep in the injection zone where its effect would be minimal. In any event, the impact of pore plugging would only be to decrease permeability in the injection zone, thereby reducing the efficiency (but not the safety) of the injection operation.

In short, geochemical changes related to CO2 injection cannot be expected to be material to the protection of USDWs. Accordingly, there is no credible basis for the suggestion (73 Fed. Reg. at 43505) that "[s]tudies of rock samples and review of geochemical data from monitoring wells are needed to evaluate the impact" of potential geochemical changes related to CO2 injection.

Recommendation:

Remove requirements for detailed analysis of potential chemical or mineralogical reactions that are unnecessary to ensure protection of USDWs.

Response: The Agency believes that the site characterization requirements at §146.82 are essential to proper siting of a GS well and are the foundation for a detailed understanding of the local and regional geology. Collecting and evaluating geochemical data in and around the CO2 injection zone, as required in §146.82(a)(6), serves several purposes. This baseline geochemical data can help predict geochemical reactions between the injectate, reservoir geology, and formation fluids. Such reactions can lead to dissolution and precipitation of minerals which affect formation porosity, which in turn can affect required injection pressure (Sminchak and Gupta, 2002) and transport of fluid within the formation. While the confining layer is the primary barrier to CO2 movement into a USDW, multiple barriers are important and changes in injection pressure and fluid movement may compromise those barriers. An increase in injection pressure due to reduced porosity, in particular, can lead to fracturing of the confining layer and potentially allow fluid movement outside of the injection zone. Losses in injectivity because of geochemical reactions may also require additional injection wells and further penetrations in the confining layer that can become pathways for fluid migration.EPA disagrees with the comment that the composition of the CO2 stream is not important. Information about the composition of the CO2 stream informs decisions about the appropriate design and construction of the well, the potential for adverse mineral reactions in the subsurface geologic formations, and appropriate testing and monitoring parameters.

EPA disagrees that injectivity is not an important consideration. While increasing storage capacity is not the intent of the UIC requirements, EPA believes that maximizing the amount of CO2 that can be injected through a single well may reduce the need for additional injection wells which reduce the potential for unacceptable fluid movement and improve USDW protection from endangerment.

Finally, EPA disagrees that any of the requirements for detailed analysis of potential chemical or mineralogical reactions are unnecessary to ensure protection of USDWs from endangerment. EPA believes that information on the mineralogy of the injection and confining zones (required at §146.82(3)(iii)), can help predict geochemical reactions between the injectate, reservoir geology, and formation fluids. Such reactions can lead to dissolution and precipitation of minerals which can affect formation porosity and injectivity, and in turn can affect required injection pressure (Sminchak and Gupta, 2002) and transport of fluid within the formation.

Additionally, EPA disagrees that consideration of local and regional seismicity is not important. The site characterization provisions in the GS rule, including a review of the local and regional geology, and detailed review of any known or potential seismically active terrain in the vicinity of a proposed GS site are necessary to minimize the potential for induced seismic events or the reactivation of faults, which are a known potential risk associated with injection and are addressed in all aspects of the UIC regulations.

Commenter Name: Dennis R. James Letter ID: 0214 Commenter Organization: North American Coal Corporation (NAC) Comment ID: 22962

Comment: 1. Proposed Geologic Siting Requirements

The proposed rule would require maps, cross sections, and geochemical data on all USDWs near an injection well. This requirement could be extremely burdensome to the operator, requiring significant work without any additional benefit. In many areas, near surface USDWs are very complex systems without much existing data. Obtaining the required data on these shallow USDWs would take significant time, money, and resources, and the interpreted data would have no impact on the injection well’s construction or operation. Defining the lowermost USDW sets a boundary condition for an injection well, everything above which would be protected.

Response: EPA believes that identifying and mapping all surrounding USDWs near an injection well, as specified at §146.82(a)(5), is necessary to ensure protection of all USDWs from endangerment. The purpose of the UIC requirements (including those for Class VI wells) is to ensure the protection of USDWs from endangerment, which are defined based on total dissolved solids (TDS) content, not their location or depth (§144.3).

EPA adds that knowing the number, location and depth of USDWs near an injection well will generate baseline regional information, support development of an effective testing and monitoring plan, and enhance owner or operator and Director understanding of the site. This requirement iscommon to all injection well classes.

Commenter Name: Edward Steadman Letter ID: 0220 Commenter Organization: The Energy and Environmental Research Center at the University of North Dakota Comment ID:

21610

Comment: Page 43505. 1. Proposed Geologic Siting Requirements

With regard to the need for data on all USDWs at a site:

Wording here suggests that maps and cross sections must be generated of all USDWs near the proposed injection well. Submitting maps and cross sections of all of the USDWs, not just the lowermost USDW, seems unnecessarily burdensome to the owner/operator. Such maps will require significant additional work, and it is not clear how doing so will result in improved protection of USDWs since protective casing is already required from the surface all the way to the bottom of the lowermost USDW. Identifying and mapping the lowermost USDW should be sufficient to protect all overlying USDW zones.

Response: EPA believes that identifying and mapping all surrounding USDWs near an injection well, as specified at §146.82(a)(5), is necessary to ensure protection of all USDWs from endangerment. The purpose of the UIC requirements (including those for Class VI wells) is to ensure the protection of USDWs from endangerment, which are defined based on total dissolved solids (TDS) content, not their location or depth (§144.3).

EPA adds that knowing the number, location and depth of USDWs near an injection well will generate baseline regional information, support development of an effective testing and monitoring plan, and enhance owner or operator and Director understanding of the site. This requirement is common to all injection well classes.

Commenter Name: Edward Steadman Letter ID: 0220 Commenter Organization: The Energy and Environmental Research Center at the University of North Dakota Comment ID:

21612 Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards)

Comment: Following is a series of comments with regard to the quote on page 43505: "...require owners or operators to submit geochemical data on (a) the injection zone, (b) the confining zones, (c) containment zones above the confining zones in which any potentially migrating CO2 could be trapped, (d) all USDWs, and (e) any other geologic zone or formation that is important to the proposed monitoring program."

The EPA should recognize that it is essentially saying that the entire rock column from the injection zone to the surface must be geochemically characterized. Such characterization goes far above and beyond that which is necessary to protect the USDWs. It is essentially forcing owners/operators to pay for potentially unnecessary research activities. For instance, in the Williston Basin, a vast majority of the hydrocarbon production is historically

from Paleozoic formations. One result of this is that there is a wealth ofreadily available data on the nature of Paleozoic formations in the Williston Basin. Likewise, the Cenozoic formations are fairly well characterized because of the presence of coal and potable aquifers. However, the Mesozoic formations that lie between those two groups are relatively poorly understood. This is

because there is little economic incentive to characterize most of the Mesozoic rocks beyond the fact that they are dominated by low permeability shales and evaporites. There are 15 named rock units in the Mesozoic section of the Williston Basin. The regulations as proposed indicate that they must all be geochemically characterized. To geochemically characterize all of these Mesozoic units as part of a GS project in which the primary sinks and seals are in the deeper Paleozoic would be very expensive and of dubious value to anyone. Once again, there must be flexibility and discretionary powers given to directors with respect to what formations must be geochemically characterized. Indeed, this concept of flexibility must apply for all types of characterization that are considered necessary to prove that a GS well application can be approved.

Response: The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate and transport model development (e.g., by providing appropriate input parameters), and provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. The baseline geochemical information will allow the owner or operator and permitting authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid movement.

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion to require geochemical analysis of additional subsurface zones if in the Director's opinion they are necessary for the protection of USDWs from endangerment.

EPA agrees that site characterization should be site-specific, particularly in light of the variety of geologic settings in which GS may be employed. EPA believes that, while there is a large amount of required information, the owner or operator is given flexibility in determining what methods are used to demonstrate the suitability of a potential site. EPA envisions an ongoing dialogue between the Director and the owner or operator during the permitting process (as well as throughout the operation of the site).

Commenter Name: Edward Steadman Letter ID: 0220 Commenter Organization: The Energy and Environmental Research Center at the University of North Dakota Comment ID:

21631 Other EPA Comment Codes and Descriptions: 3150 2.1.5 Comments on required permit information (40 CFR 146.82)

Comment: Page 43536. § 146.82 Required Class VI permit information. There are numerous requirements for information on formations overlying the proposed storage site. Requirements should be flexible and site-specific. The required information should be limited to relevant primary and/or secondary seals and be used to document the vulnerability or lack thereof of any USDWs in the area.Response: EPA agrees that site characterization should be site-specific, particularly in light of the variety of geologic settings in which GS may be employed. EPA believes that, while there is a large amount of required information, the owner or operator is given flexibility in determining what methods are used to demonstrate the suitability of a potential site. EPA envisions an ongoing dialogue between the Director and the owner or operator during the permitting process (as well as throughout the operation of the site).

Commenter Name: Neeraj Gupta Letter ID: 0229 Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21829

Comment: Page 63, Geochemical Data- The proposed requirements ask for geochemical data on injection zone, confining zone, any underground source of drinking water, and any other important zone. This may be a burdensome amount of information for GS sites. While some indication of geochemical parameters may be obtained from wireline methods, it can be a challenge to collect representative brine samples, especially from low permeability caprocks and deep saline formations. It is very unlikely we would even be able to collect samples from many low permeability confining layers. In addition, no guidance on the list of analytes (i.e. cations, anions, metals, physical parameters) is provided. We would suggest that data from regional studies and other deep wells also be allowed as an alternative for defining the geochemical setting.

Response: The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate and transport model development (e.g., by providing appropriate input parameters), and provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. The baseline geochemical information will allow the owner or operator and permitting authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid movement.

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion to require geochemical analysis of additional subsurface zones if in the Director's opinion they are necessary for the protection of USDWs from endangerment.

EPA agrees that site characterization should be site-specific, particularly in light of the variety of geologic settings in which GS may be employed. EPA believes that, while there is a large amount of required information, the owner or operator is given flexibility in determining what methods are used to demonstrate the suitability of a potential site. EPA envisions an ongoing dialogue between the Director and the owner or operator during the permitting process (as well as throughout the operation of the site). EPA clarifies that if recent information about the site exists (e.g., from other geologic studies of the area), the Director may, at his/her discretion, allow its use in the site characterization for the GS project.

Commenter Name: Mark Bohrer Letter ID: 0241 Commenter Organization: North Dakota Industrial Commission Comment ID: 23281

Comment: 146.82(g) Baseline geochemical data on subsurface formations is too broad.Should be limited to the injection zone, confining zones, and possibly the next porous and permeable zone above the upper confining zone.

Response: The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate and transport model development (e.g., by providing appropriate input parameters), and provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. The baseline geochemical information will allow the owner or operator and permitting authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid movement.

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion to require geochemical analysis of additional subsurface zones if in the Director's opinion they are necessary for the protection of USDWs from endangerment.

EPA agrees that site characterization should be site-specific, particularly in light of the variety of geologic settings in which GS may be employed. EPA believes that, while there is a large amount of required information, the owner or operator is given flexibility in determining what methods are used to demonstrate the suitability of a potential site. EPA envisions an ongoing dialogue between the Director and the owner or operator during the permitting process (as well as throughout the operation of the site).

Commenter Name: Kevin Wanttaja Letter ID: 0248 Commenter Organization: Western Energy Supply and Transmission

Associates Comment ID:

22242

Comment: – EPA needs to build a practical realism into the site characterization UIC regulatory requirements under the SWDA. The current rule proposal is so "demanding" it may preclude many otherwise eligible geological storage sites. The site characterization and related requirements for permitting a UIC well present a very large list of extremely detailed potential impact issues that by themselves may be frightening to members of the public. This evaluative process needs to be pared down to those most critical few factors that assure the greatest degree of safety for each unique UIC for CO2 GS site. WEST members do not want to see development of a regulatory program that gets so bogged down that it goes no further than the nuclear waste storage siting fiasco in the US (e.g., the Nevada nuclear storage site is still not approved by the state and is caught up in unrealistic public fear and political concerns). If this happens to UIC for CO2 GS siting, it could stop the coal fired power plant industry if CCS becomes one of a very few limited options for CO2 emissions abatement required under a GHG legislative or regulatory program.

Response: EPA believes that a detailed geological site characterization (required under §146.82) is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for theunique nature of injecting large volumes of CO2 into a variety of geological formations for longterm storage.

EPA adds that the GS rule does not address the use of coal-fired power plants; instead the mission of the UIC program and the goal of the GS regulation is to protect USDWs from endangerment, and every aspect of the GS rule is designed toward that end. Therefore, EPA disagrees that any of these protective requirements are unnecessary, and clarifies that waiving any of the requirements would not be acceptable. The GS regulation allows flexibility where appropriate. Certain requirements (e.g., the need to characterize additional confining layers) are at the Director's discretion (§146.83(b)), based on his or her understanding of a particular site.

To the comment comparing the GS siting requirements to nuclear waste storage siting requirements, EPA clarifies that the two activities are very different, and while it is out of the scope of the GS rulemaking to comment on the stringency of nuclear waste siting requirements, EPA stresses that the site characterization requirements for GS wells are tailored so that they are appropriate for the unique nature of injecting large volumes of CO2 into a variety of geological formations for long-term

storage.

Commenter Name: Dianna Tickner Letter ID: 0262 Commenter Organization: Peabody Energy Comment ID: 22993

Comment: Class II EOR wells to permanent CO2 storage wells. As proposed, the site geology requirements seem to be unduly burdensome without any real additional safety benefit to underground sources of drinking water. Site geology should be considered on a case by case basis to prevent the categorical elimination of sites which may be technically acceptable.

Response: EPA disagrees that the requirements at §146.82 are unnecessary and unduly burdensome and believes that a detailed geological site characterization is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for the unique nature of injecting large volumes of CO2 into a variety of geological formations for long-term storage.

EPA agrees that site characterization should be site-specific, particularly in light of the variety of geologic settings in which GS may be employed. EPA believes that, while there is a large amount of required information, the owner or operator is given flexibility in determining what methods are used to demonstrate the suitability of a potential site. EPA envisions an ongoing dialogue between the Director and the owner or operator during the permitting process (as well as throughout the operation of the site).

Commenter Name: Mark Vickery Letter ID: 0280 Commenter Organization: Texas Commission on Environmental Quality Comment ID: 24099

Comment: (a) The proposed requirement that an application for Class VI well permit include baseline geochemical data on subsurface formations including all underground sources of drinking water (USDWs) in the area of review is unnecessarily burdensome, considering that this could entail sampling of numerous individual sands throughout thousands of feet of geologic section.USDWs in Texas may extend to depths of 4,000 feet or more, and in some regions of the U. S., even deeper. Baseline determinations for local aquifers in a CO2- GS project should focus on those immediately overlying CO2 confining zones, lowest USDWs, and any other USDWs of significance.

Response: The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate and transport model development (e.g., by providing appropriate input parameters), and provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. The baseline geochemical information will allow the owner or operator and permitting authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid movement.

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion to require geochemical analysis of additional subsurface zones if in the Director's opinion they are necessary for the protection of USDWs from endangerment.

EPA agrees that site characterization should be site-specific, particularly in light of the variety of geologic settings in which GS may be employed. EPA believes that, while there is a large amount of required information, the owner or operator is given flexibility in determining what methods are used to demonstrate the suitability of a potential site. EPA envisions an ongoing dialogue between the Director and the owner or operator during the permitting process (as well as throughout the operation of the site).

Regarding concerns about deep USDWs, EPA adds that the final GS rule contains a provision (at §146.95) for owners or operators to apply for waivers from the requirement that injection be below the lowermost USDW. EPA believes this waiver provision will reduce potential limitations on the re-permitting of Class II wells as Class VI wells, provided they meet the requirements at §146.95.

Comment Code: 3150 2.1.5 Comments on required permit information (40 CFR 146.82)



### Individual Comments

Commenter Name: Leslie Savage Letter ID: 0122 Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24765 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: (i) The compatibility of the CO2 stream with fluids in the injection zone and minerals in both the injection and the confining zone(s) , based on the results of the formation testing program, and with the materials used to construct the well;

{See comment above.}Response: The final rule will allow the Director to require more than one confining zone; therefore, EPA did not make the suggested change.

Please see the final rule and the discussion of geologic site characterization in the preamble for

additional information.

Commenter Name: Leslie Savage Letter ID: 0122 Commenter Organization: Railroad Commission of Texas (RRC) Comment ID: 24766 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: (m) Proposed procedure to outline steps necessary to conduct injection operation;

{"Proposed procedure to outline steps" does not make sense. Recommend "Outline of steps ...."}

Response: EPA disagrees that the suggested edit provides more clarity to the requirements and has retained the language as proposed. Additionally, similar language is used for other UIC well classes and the regulated community and permitting officials are familiar with the terms.

Please see the final rule and the discussion of geologic site characterization in the preamble for

additional information.

Commenter Name: John Hanger Letter ID: 0130 Commenter Organization: Pennsylvania Dept. of Env. Protection Comment ID: 21501

Comment: Proposed Class VI Permit Requirements

-The permit applicant (owner/operator) for a proposed UIC Class VI well must demonstrate in the permit application that he owns the right to inject the CO2 into the property and that his ownership extends to the entire area to which the CO2 may migrate.

-Section 146.82 sets forth the information which the owner or operator must

submit

"(b) A map showing the injection well(s) for which a permit is sought and the applicable area of review. Within the area of review, the map must show... Only information of public record is required (emphasis added) to be included on this map;...."

While it may be prudent to show only public information, it is also easy to avoid the aggravation of a diligent search by requiring that only public information is shown. This should not relieve the permittee from sharing any confidential information about the area, the subsurface conditions, the potential adjoining landuse, etc. Regulations should require full and complete disclosure of all information known, even if a confidential submittal is required.

-It is possible that the owner/operator would be required to obtain informationfrom neighboring non-owners in order to meet the requirements identified in the permit requirement and or area of review sections. EPA should identify the means by which Class VI owners/operators can obtain this information. This point is especially relevant to the inclusion of ‘buffer zones’ (see comments on the Area of Review) and the need to obtain site-specific information about these buffers.

Response: EPA clarifies that land and pore space ownership issues are outside the scope of the GS regulation and disagrees that it is necessary that the owner or operator of a GS site own the entire area to which the CO2 may migrate. EPA does believe, however, that it is important that the owner or operator have surface access to wells that require corrective action and for all necessary testing and monitoring during the life of the project. For this reason, the GS rule requires owners or operators to demonstrate that they will have access for these activities in the AoR and corrective action plan at §146.84(b) and testing and monitoring plan (§146.90).

EPA acknowledges that information beyond publically available data may be needed to accurately assess the suitability of a site for GS. EPA believes that a determination about whether or whatinformation may be necessary (for a specific GS project) is outside of the public record will be sitespecific and based on knowledge of the site, data availability, and data quality. The Director has the discretion to require the owner or operator to supplement publically available data if there is reason to believe that the incompleteness of available information could compromise USDW protection from endangerment.

In response to the comment suggesting that some of the required information may be available from neighboring land owners, EPA replies that if relevant information about the site exists (e.g., from earlier geologic studies of the area) and is available and the owner of that information is willing to share it, the Director may, at his/her discretion, allow its use in the site characterization for the GS project.

Commenter Name: Brianne Metzger Letter ID: 0151 Commenter Organization: Spectra Energy Corp Comment ID: 21823 Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: E. EPA Should Not Make The Permitting Process Overly Burdensome By Requiring Unnecessary Or Unavailable Data.

Under the proposal, EPA is requiring the collection and submission of a significant amount of information and data. Although we understand and support the need for certain baseline data to support the determination that a particular project location is suitable, in certain cases, some of the data that EPA is requiring is irrelevant, excessive, or may even be unavailable. Therefore, we would recommend that the Agency include a provision in the Final GS Rule that would provide a waiver process and criteria, whereby the Director could waive certain data requirements, where such requirements are unnecessary.

Response: EPA disagrees that any of these protective requirements are unnecessary, and believes that waiving any of the requirements would not be acceptable. The GS regulation allows flexibility where appropriate. Certain requirements (e.g., the need to characterize additional confining layers) are at the Director's discretion (§146.83(b)), based on his or her understanding of a particular site.EPA believes that a detailed geologic site characterization (required under §146.82) is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long-standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for the unique nature of injecting large volumes of CO2 into a variety of geologic formations for long-term storage.

EPA believes that a determination about whether or what information may be necessary (for a specific GS project) is outside of the public record will be site-specific and based on knowledge of the site, data availability, and data quality. For instance, in meeting the requirement to tabulate information on wells in the AoR, the Director has the discretion to require the owner or operator to supplement a data records search if there is reason to believe that the incompleteness of available information could compromise USDW protection from endangerment.

Commenter Name: Brianne Metzger Letter ID: 0151 Commenter Organization: Spectra Energy Corp Comment ID: 21825

Comment: EPA has also included a requirement that the permit applicant include a "proposed formation testing program to obtain an analysis of the chemical and physical characteristics" of the injection and confining zone. 40 C.F.R. § 146.82(j). A permit applicant is already required to submit the underlying data as part of the permit application process, and it appears that this requirement is unnecessary and duplicative. Therefore, we request further clarification regarding the intent and scope of this formation testing program.

Spectra generally supports the requirement for the "proposed stimulation program" to ensure that stimulation activities will not interfere with containment. 40 C.F.R. § 146.82(k). We believe it is important that EPA monitor stimulation activities of third parties to ensure that such activities not interfere with or damage the containment integrity of other GS operations or natural gas storage reservoirs.

Response: The formation testing plan must be approved before the owner or operator can generate necessary data on the compatibility of the CO2 stream with fluids in the injection zone and minerals in both the injection and the confining zone. In response to comments and based on an evaluation of the proposed requirements, EPA revised subpart §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at 146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

Additionally, EPA agrees that it is important that the Agency, as manager of the national UIC Program, understand how various aspects of GS projects, including stimulation activities, are proceeding, and that operators performing well stimulation activities are not endangering USDWs. EPA plans to, every six years, collect and review project data on early GS projects, including site characterization, operational, monitoring, and modeling data, to determine whether the appropriate amount and types of information and appropriate documentation are being collected, and to determine if modifications to the requirements are appropriate or necessary.Commenter Name: Bonnie Lovelace Letter ID: 0152 Commenter Organization: Montana Department of Environmental Quality (MDEQ) Comment ID:

22123

Comment: 146.82 (b): MDEQ suggests that the information requirements not be limited to public records only. The area ofreview should be surveyed completely and all information shown on a map.

Response: EPA believes that a determination about whether or what information may be necessary (for a specific GS project) is outside of the public record will be site-specific and based on knowledge of the site, data availability, and data quality. For instance, in meeting the requirement to tabulate information on wells in the AoR, the Director has the discretion to require the owner or operator to supplement a data records search if there is reason to believe that the incompleteness of available information could compromise USDW protection from endangerment. EPA acknowledges that maps are probably the most appropriate method for presenting the required information. EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Bonnie Lovelace Letter ID: 0152 Commenter Organization: Montana Department of Environmental Quality (MDEQ) Comment ID:

22124

Comment: 146.82 (e): MDEQ suggests that the tabulation of wells within the area of review not be limited to only those that penetrate the injection or confining zone(s). Identifying all perforations will allow for complete public involvement and identification of areas of risk should the plume move upward.

Response: EPA believes that a determination about whether or what information may be necessary (for a specific GS project) is outside of the public record will be site-specific and based on knowledge of the site, data availability, and data quality. For instance, in meeting the requirement to tabulate information on wells in the AoR, the Director has the discretion to require the owner or operator to supplement a data records search if there is reason to believe that the incompleteness of available information could compromise USDW protection from endangerment.

EPA believes that limiting this inventory effort to those wells that penetrate the confining zone is appropriate, because the confining zone, by definition, acts as a barrier to the fluid movement that could endanger a USDW.

Commenter Name: Bonnie Lovelace Letter ID: 0152 Commenter Organization: Montana Department of Environmental Quality (MDEQ) Comment ID:

22125

Comment: 146.82 (g) : MDEQ suggests that this rule be more specific to include geochemical data collection for the injection formation and the confining zone directly above the injection zone.

Response: The Agency believes that the requirement at §146.82(a)(6) to submit baselinegeochemical data on subsurface geologic formations, including all USDWs in the AoR is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate and transport model development (e.g., by providing appropriate input parameters), and provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. The baseline geochemical information will allow the owner or operator and permitting authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid movement.

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion to require geochemical analysis of additional subsurface zones if in the Director's opinion they are necessary for the protection of USDWs from endangerment.

Commenter Name: Steven Pirner Letter ID: 0153 Commenter Organization: South Dakota Department of Environment and

Natural Resources Comment ID:

22141

Comment: 144.18 Requirements of Class VI wells - owners must get a permit versus ruleauthorization - much more detailed application, and has/allows for public input. We are in agreement with this.

Response: EPA acknowledges the comment and the final rule retains the requirement as proposed.

Commenter Name: Steven Pirner Letter ID: 0153 Commenter Organization: South Dakota Department of Environment and

Natural Resources Comment ID:

22144

Comment: 146.82 Required Class VI permit information - (e) ".... and any additional information the Director may require:" - this is good part, as we as a state have had numerous occasions when operators do not submit all of the information needed to determine the viability of an application for a well because it is not specifically listed in the state regulations

Response: The Agency believes that providing the Director discretion to request additional information will allow consideration of a range of sites for GS, based on site-specific conditions, and ensure USDW protection. EPA believes that requiring appropriate site characterization by the owner or operator (under §146.82) and providing an appropriate degree of flexibility to the Director to evaluate site-specific geologic data will afford the greatest protection of USDWs from endangerment.

Commenter Name: James Childress Letter ID: 0158 Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23769 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: 146.82 Required Class VI permit information. (b) "A map showing the injection well(s) for which a permit is sought and the applicable area of review. Within the area of review, the map must show the number, or name and location of all injection wells, producing wells, abandoned wells, plugged wells or dry holes, deep stratigraphic boreholes, State or EPA approved subsurface cleanup sites,surface bodies of water, springs, mines (surface and subsurface), quarries, water wells and other pertinent surface features including structures intended for human occupancy and roads. The map should also show faults, if known or suspected. Only information of public record is required to be included on this map; "

The note that "only information of public record is required to be included on this map" may leave out deep oil and gas wells, particularly older wells. The presence of such non-public but "known" information may be eligible for inclusion as "known" under 144.55(a).

Response: EPA believes that a determination about whether or what information may be necessary (for a specific GS project) is outside of the public record will be site-specific and based on knowledge of the site, data availability, and data quality. For instance, in meeting the requirement to tabulate information on wells in the AoR, the Director has the discretion to require the owner or operator to supplement a data records search if there is reason to believe that the incompleteness of available information could compromise USDW protection from endangerment.

Commenter Name: James Childress Letter ID: 0158 Commenter Organization: Gasification Technologies Council (GTC) Comment ID: 23770 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: §146.82 Required Class VI permit information (e) "A tabulation of all wells within the area of review which penetrate the injection or confining zone(s). Such data must include a description of each well's type, construction, date drilled, location, depth, record of plugging and/or completion, and any additional information the Director may require; -

We recommend striking out "all wells" and replacing with "all known wells".

Requiring that all wells or other artificial penetrations into injection or confining zones within the AoR be identified and information on depth and closure be provided can be costly and sometimes accurate information is

difficult to obtain for older wells within the AoR. EPA's assistance in obtaining and storing this information would be helpful to CCS operators.

Response: The Agency believes that the requirement to provide a tabulation of wells and geologic information (at §146.82(a)), along with a description of each well's type, construction, date drilled, location, depth, record of plugging and/or completion will appropriately inform a determination of the risk associated with wells in the AoR. EPA believes that it is important to have information on all

wells in the AoR.

Commenter Name: Michael J. Miller Letter ID: 0168 Commenter Organization: Electric Power Research Institute (EPRI) Comment ID: 22493 Other EPA Comment Codes and Descriptions: 4660 2.6.6 Geochemical monitoring

Comment: Preamble, page 43505, §146.82(g), and § 146.90(d): "Today’s proposal would require owners or operators to submit geochemical data on a) the injection zone, b) the confining zones, c) containment zones above the confining zones in whichany potentially migrating CO2 could be trapped, d) all USDWs, and e) any other geologic zone or formation that is important to the proposed monitoring program."

EPRI COMMENT #3A: EPA does not provide the technical justification for collecting geochemical data from all zones, geologic formations and USDWs. We

believe the collection of data should be limited to zones needed to demonstrate system performance defined by the minimum siting criteria specified in §146.83(a)(1) and (a)(2). EPRI believes that system performance with the end goal of protecting USDW can be achieved by collecting geochemical data from a maximum of four zones for the reasons provided below:

1) Injection zone -- during site characterization, check for conditions that could lead to CO2-induced rock dissolution, potentially resulting in formation and injection well collapse (well integrity);

2) Primary confining zone -- during site characterization, check for conditions that could lead to caprock dissolution and degradation, potentially resulting in loss of CO2 containment with subsequent CO2 movement through the primary barrier (caprock integrity);

3) Monitoring zone -- a zone proposed by the applicant and approved by the EPA where performance monitoring is required to take place in accordance with §146.90(d). The monitoring zone would lie between the primary confining zone and the USDW. It would be the only zone sampled on a routine schedule during CO2 injection operations and closure to detect the leakage of CO2 through the primary confining zone (performance monitoring) as noted ; and

4) USDW zone -- during site characterization, collect optional samples at or near the closest USDW boundary to the injection zone to establish baseline water quality.

EPRI COMMENT #3B: Before promulgating the rule, a comprehensive study of deep well fluid sampling techniques needs to be performed to ensure that the techniques cited by EPA consistently produce samples that are representative of deep reservoir conditions. Otherwise, interpretation of geochemical data derived from methods producing inconsistent or non-representative sample data could result in erroneous conclusions, including unnecessary or inappropriate corrective action. Collecting representative deep well samples from confining zones is especially challenging (see EPRI comment #14).

Response: The GS regulation, at §146.82(a)(6), requires the owner or operator to submit baseline geochemical data on subsurface geologic formations. EPA is not specifying for which formations this information should be submitted to allow flexibility, but examples may include the following formations: a) the injection zone, b) the confining zones, c) containment zones above the confining zones in which any potentially migrating CO2 could be trapped, d) all USDWs, and e) any other geologic zone or formation that is important to the proposed monitoring program. The Director has the authority to request additional geochemical data as well.

EPA believes that the necessary sampling techniques are available, and is developing guidance onsite characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

On the topic of sampling, EPA recognizes that the collection of representative ground water samples from depth poses challenges and that special methods, such as U-tubes, will be needed to preserve the integrity of such samples. EPA is developing guidance on testing and monitoring to assist owners or operators and Directors in evaluating requirements under §146.90, including proposed monitoring plans. The guidance describes available technologies and recommended approaches for implementing a testing and monitoring plan, including pre-operational geophysical logging and testing of injection wells, MITs, injection well testing during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which may be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Regarding the comment about the technical justifications and difficulty of sampling within the confining zone, EPA clarifies that §146.90(d) requires owners and operators to monitor ground water quality and geochemical changes above the confining zone(s), rather than within the confining zone.

Commenter Name: Theresa Pugh Letter ID: 0169 Commenter Organization: American Public Power Association Comment ID: 23407 Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: · The Final Rule must not make the application process overly burdensome or unrealistic by requiring detailed information that may not be available at the time of the initial application; instead, the Final Rule should allow for submission of updated information regarding a CO2 GS well and its AoR as that information becomes available through phased corrective action.

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of information to be submitted. In addition, section §146.82 in the final rule is similar to the permit application requirements for other injection well classes, which could help avoid confusion about how to meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to be submitted before operation of the well is authorized are very similar to those for Class I wells, with modifications and additions that address the unique challenges and types of data

collected for GS wells.

The final rule requires for the submission of updated information on the well and its AoR. The finalGS rule, at §§146.84(c) and §146.90(j) requires owners or operators to review and update the AoR and corrective action plan and the testing and monitoring plan, at least once every 5 years, throughout the life of the project. Owners or operators must review each plan and identify necessary modifications 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 monitoring or injection wells), or when required by the Director. While the rule does not specify that changes in phased corrective action warrant an update, the Director may determine that these types of modifications need to be incorporated into a plan update. EPA is developing guidance on developing and updating the GS project plans, which includes recommended considerations for developing and updating the plans. This guidance will be available on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Kyle Isakower Letter ID: 0170 Commenter Organization: American Petroleum Institute Comment ID: 24120 Other EPA Comment Codes and Descriptions: 1210 1.1.1 Comments about the proposed rule

Comment: EPA should be aware that some provisions seem to be based on data and information that would actually be generated by the permitted activity and therefore would not be available at the time of submittal of the permit application. For example §146.82(c) requests data from wells that cannot be drilled until the permit is received. EPA proposed rules appear to contemplate delineation and evaluation activities prior to submittal of an application for GS wells/projects. It is not clear to API under what authority and regulatory framework these activities would be conducted since most Class VI projects will not be oil and gas related and so would not fall under oil and gas rules.

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of information to be submitted. In addition, section §146.82 in the final rule is similar to the permit application requirements for other injection well classes, which could help avoid confusion about how to meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to be submitted before operation of the well is authorized are very similar to those for Class I wells, with modifications and additions that address the unique challenges and types of data

collected for GS wells.

Commenter Name: Kyle Isakower Letter ID: 0170 Commenter Organization: American Petroleum Institute Comment ID: 24155 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(h)

API Comments: (h) Proposed operating data: (1) Average and maximum dailyINJECTION rate and volume of the carbon dioxide stream; (2) Average and maximum SURFACE injection pressure;

Rationale: Technical clarifications.

Rule Provision: 146.82(k)

API Comments: (k) Proposed stimulation program and a determination that stimulation will not interfere with containment;

Rationale: This responsibility is best left with EPA.

Rule Provision: 146.82(n)

API Comments: (n) A WELLBORE schematic or other appropriate drawings of the

surface and of the subsurface construction details of the well AND SURFACE

WELLHEAD CONSTRUCTION.

Rationale: Technical clarification.

Rule Provision: 146.82(q)

API Comments: q) The ANY status of corrective action on wells in the area of review;

Rationale: Clarifies that wells not needing corrective action will not have a

corrective action status.

Response: EPA acknowledges the commenter’s support for parts of the requirements under 146.82. EPA disagrees with suggested technical clarifications regarding proposed operating data, needs for the stimulation program, and the status of corrective action. EPA adds that it is developing guidance for owners or operators on the geologic site characterization, AoR, and corrective action processes. These guidances will provide recommendations and clarify the intent of all required elements of a permit application. The guidances can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Frederick R. Eames Letter ID: 0178 Commenter Organization: CCS Alliance Comment ID: 23845

Comment: B. PERMIT APPLICATION REQUIREMENTS

EPA proposes to require owners and operators to submit relevant site information to the permitting authority for consideration of permit applications, including: maps of the injection wells, the AoR as determined through computational modeling, all artificial penetrations within the AoR, maps of the general vertical and lateral limits of USDWs, maps of the geologic cross sections of the local area, the proposed operating data and injection procedures, proposed formation testing program, and stimulation program, well schematics and construction procedures, and contingency plans for shut-ins or well failures.Some of the data that EPA proposes to require is irrelevant, excessive, or in some cases unavailable. Therefore, the CCS Alliance recommends that EPA ensure that any required data is necessary to the ultimate goals of the Proposed Rule. For example, artificial penetrations several formations above the injection zone may have little relevance to the GS operation. Similarly, the CCS Alliance recommends including a provision in the final rule providing the Director discretion to waive certain data requirements, where such requirements are unnecessary, or require that the data be updated as it is collected or becomes

available.

EPA is proposing that an applicant include "baseline geochemical data on subsurface formations, including all USDWs in the area of review."" The Proposed Rule is not clear as to how much baseline data EPA is expecting the permit applicant to generate and collect from additional drilling or testing of the injection zone and all other zones. Given the likely depth of many of the GS wells through many strata, this could involve a large number of different formations above the injection zone. EPA should limit the baseline geochemical data to information regarding the next porous formation above the injection zone. Similarly, EPA should clarify that the permit applicant may rely upon secondary sources (such as other drilling or geologic records) that relate to and support the data requirement. EPA also should clarify whether its expects applicants to test private wells, where permission is granted, within the AoR for purposes of establishing baseline data.

[FN44] 40 C.F.R. $ 146.82(g).

EPA also has included a requirement that the permit applicant include a "proposed formation testing program to obtain an analysis of the chemical and physical characteristics" of the injection and confining zone." A permit applicant is already required to submit the underlying data as part of the permit application process, and it appears that this requirement is unnecessary and duplicative. Therefore, the Alliance requests further clarification regarding the intent and scope of this formation testing program.

[FN45] 40 C.F.R. $ 146.82(j).

EPA should monitor stimulation activities of third parties to ensure that such activities not interfere with or damage the containment integrity of other GS operations or natural gas storage reservoirs. The CCS Alliance, therefore, generally supports the requirement for the "proposed stimulation program" to ensure that stimulation activities will not interfere with containment. [FN46]

[FN46] 40 C.F.R. 9 146.82(k).

EPA has proposed requiring the applicant to submit "the status of corrective action on wells in the area of review."[FN47] The CCS Alliance does not believe it is necessary to require the inclusion of all wells within the AoR regardless of whether or not they penetrate the injection zone. There could be many shallow

wells within the AoR located hundreds or thousands of feet above the CO2 injection zone. Therefore, EPA should limit this requirement to the injectionzone, injection pool, and only those wells that either intersect or penetrate the proposed reservoir, the cap rock, and possibly the porous strata directly above the injection zone.

[FN47] 40 C.F.R. $ 146.82(q).

On a related matter, EPA has stated that only information of public record pertaining to all types of wells (injection. producing, abandoned) be included on the AoR. Data availability and use raises a question regarding the possible existence of other data which might be private, proprietary, and/or not publicly available. Such non-publicly available data may or may not be relevant to the application process. The CCS Alliance requests EPA to clarify to what extent an applicant would be expected to develop or use information not contained in the public record.

EPA also proposes that permit applications for GS sites include several plans not currently required under existing UIC regulations, including (1) a monitoring and testing plan; (2) an AoR and corrective action plan; (3) a well plugging plan: and (4) a post-injection site care and site closure plan. The CCS Alliance questions whether it is necessary for each plan to be submitted contemporaneously with the permit application. The up-front gathering and submission of such detailed information would be costly and time-consuming. We recommend requiring the submission of such plans only upon approval of an initial permit application, with further approvals contingent upon the successful completion, submission, and approval of the required plans. The initial permit application could provide general information regarding the specific plans to be submitted later. Such a process will provide sufficient information for EPA to make an initial permitting decision.

As part of the permitting process, EPA should require that owners and operators establish a plan to ensure that resource development may occur in other geologic strata within or near the AoR. CCS will be a critical technology, but also critical to the nation are energy resources and mineral reserves. Companies may have made considerable investment in purchasing, identifying and characterizing these resources. This value should be protected as GS sites are selected and developed. EPA's proposed rule at present does not address this issue.

Response: EPA believes that a detailed geological site characterization (required under 146.82) is essential to evaluating the presence and adequacy of the various geologic features necessary to receive and confine injected CO2 for GS. The requirements for geologic site characterization are based on a long standing UIC regulatory framework developed to address specific risks to USDWs posed by injection. The Class VI GS requirements are tailored so that they are appropriate for theunique nature of injecting large volumes of CO2 into a variety of geological formations for longterm storage.

EPA recognizes that some of this information may not be available until after a well has been drilled. EPA revised §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).EPA disagrees that any of these protective requirements are unnecessary, and clarifies that waiving any of the requirements would not be acceptable. The GS regulation allows flexibility where appropriate. Certain requirements (e.g., the need to characterize additional confining layers) are at the Director's discretion (§146.83(b)), based on his or her understanding of a particular site.

The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate and transport model development (e.g., by providing appropriate input parameters), and provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. The baseline geochemical information will allow the owner or operator and permitting authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may

indicate fluid movement.

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion to require geochemical analysis of additional subsurface zones if in the Director's opinion they are necessary for the protection of USDWs from endangerment.

EPA believes that a determination about whether or what information may be necessary (for a specific GS project) is outside of the public record will be site-specific and based on knowledge of the site, data availability, and data quality. For instance, in meeting the requirement to tabulate information on wells in the AoR, the Director has the discretion to require the owner or operator to supplement a data records search if there is reason to believe that the incompleteness of available information could compromise USDW protection from endangerment.

In response to the comment that EPA should require that owners or operators establish a plan to ensure that resource development may occur in other geologic strata within or near the AoR, the Agency clarifies ensuring protection of resource rights including mineral, water, and energy resource development rights is outside the scope of this rulemaking.

In conducting GS site characterization, the Agency anticipates that the owner or operator would consider the proximity of and implications that a GS project may have on other activities in the AoR. However, the purpose of the requirements is to ensure that Class VI GS well is constructed, operated, monitored, and closed in a manner that is protective of USDWs.

Commenter Name: Robert J. Finley Letter ID: 0180 Commenter Organization: Illinois State Geological Survey Comment ID: 23619

Comment: 146.82

Much of this section assumes that data are available from an injection well, such as the data referred to in (c) from logging and testing of "the well." The reality is that such a well will not be drilled until the permit is received, so specific data, especially for a saline reservoir that has not been a hydrocarbon producer or gas storage unit elsewhere in its depositional basin, likely will

not exist.Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of information to be submitted. In addition, section §146.82 in the final rule is similar to the permit application requirements for other injection well classes, which could help avoid confusion about how to meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to be submitted before operation of the well is authorized are very similar to those for Class I wells, with modifications and additions that address the unique challenges and types of data

collected for GS wells.

EPA clarifies that operators would not necessarily need to core and sample each formation in the area of a proposed GS site. If relevant, comprehensive information about the site exists (e.g., from earlier geologic studies of the area), the Director may, at his/her discretion, allow its use in the site characterization for the GS project. In addition, §146.87(b) allows cores from nearby wells to be submitted if the owner or operator can demonstrate that core retrieval is not possible and that cores from nearby wells are representative of conditions at the GS well. EPA clarifies that, at a minimum, cores of injection zones and confining zones, and samples of formation fluids must be submitted. §146.87(b) gives the Director authority to require the owner or operator to core other formations in the borehole if necessary to provide sufficient geologic information to verify that the site is suitable for GS. EPA adds that §146.87(b) allows the owner or operator to submit whole cores or sidewall cores of the injection zone and confining system.

Commenter Name: Robert J. Finley Letter ID: 0180 Commenter Organization: Illinois State Geological Survey Comment ID: 23620

Comment: (d) (2)

The entire discussion of faults is problematic here and elsewhere. Faults may be sealing, as in the case of many hydrocarbon traps, or they may be transmissive, especially in tensional stress regimes. In compressive regimes, and if similar faults form hydrocarbon trap boundaries, faults are more likely to be sealing, but cannot be conclusively stated as such from inferential data.

Response: EPA believes that the requirement at §146.83(a)(2) that the confining zone to be free of transmissive faults or fractures is appropriate for Class VI wells and is necessary to ensure containment of the injectate and that requiring the confining zone to be free of transmissive faults maximizes protection of USDWs from endangerment. Class I hazardous waste injection well operators must also meet a similar requirement that the site is free of transmissive faults or fractures; they have successfully made such demonstrations in the past. While core samples obtained through drilling and hydraulic testing are direct methods to obtain such information, geophysical techniques such as seismic or electromagnetic surveys can also be used in many geologic settings to demonstrate the absence of or identify and characterize the presence of faults or fractures. At sites where deep faults (even with little or no surface expression) are present, processing and interpreting data from multiple geophysical sensing methods has been shown to detect faults better than analysisof data from individual methods (Goussev et al, 2004). EPA adds that the Director must evaluate all geologic data on the site to ensure protection of USDWs from endangerment before approving a site for a GS project.

Commenter Name: Robert J. Finley Letter ID: 0180 Commenter Organization: Illinois State Geological Survey Comment ID: 23621 Other EPA Comment Codes and Descriptions: 3140 2.1.4 Comments that the proposed geologic data requirements are too stringent

Comment: (d) (4) (5)

This section calls for data that is almost certainly incompletely available and cannot be acquired except from a permitted well. Geomechanical information on the confining zone almost certainly will not exist until storage projects have been completed in a basin. There is no economic motive to develop such data. Acquiring a representative and accurate in situ fluid pressure in a confining zone may be impossible given that a confining zone should not be permeable and therefore its testing with wireline or drillstem tools is highly questionable.

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of information to be submitted. In addition, section §146.82 in the final rule is similar to the permit application requirements for other injection well classes, which could help avoid confusion about how to meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to be submitted before operation of the well is authorized are very similar to those for Class I wells, with modifications and additions that address the unique challenges and types of data

collected for GS wells.

EPA adds that the presence or absence of an economic motive for generating the data is outside the scope of the rulemaking. The owner or operator must submit all of the data required at §146.82 in order to support a determination about the suitability of the site, regardless of an economic incentive for gathering that data.

Commenter Name: Robert J. Finley Letter ID: 0180 Commenter Organization: Illinois State Geological Survey Comment ID: 23622 Other EPA Comment Codes and Descriptions: 3140 2.1.4 Comments that the proposed geologic data requirements are too stringent

Comment: (g)

Reference is made to geochemical data on subsurface formations with no indication of which formation or how many. This could be interpreted to mean all formations within the sedimentary column both above and below an injection zoneat a given site. Much of such data may be both irrelevant and unavailable and it will be extremely costly to core and sample every formation in the area of a proposed site.

Response: The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate and transport model development (e.g., by providing appropriate input parameters), and provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. The baseline geochemical information will allow the owner or operator and permitting authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid movement.

EPA clarifies that the rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion to require geochemical analysis of additional subsurface zones if in the Director's opinion they are necessary for the protection of USDWs from endangerment.

EPA clarifies that operators would not necessarily need to core and sample each formation in the area of a proposed GS site. If relevant, comprehensive information about the site exists (e.g., from earlier geologic studies of the area), the Director may, at his/her discretion, allow its use in the site characterization for the GS project. In addition, §146.87(b) allows cores from nearby wells to be submitted if the owner or operator can demonstrate that core retrieval is not possible and that cores from nearby wells are representative of conditions at the GS well. EPA clarifies that, at a minimum, cores of injection zones and confining zones, and samples of formation fluids must be submitted. §146.87(b) gives the Director authority to require the owner or operator to core other formations in the borehole if necessary to provide sufficient geologic information to verify that the site is suitable for GS. EPA adds that §146.87(b) allows the owner or operator to submit whole cores or sidewall cores of the injection zone and confining system.

Additionally, EPA acknowledges comments regarding the costs associated with thoroughly evaluating a potential GS site. The Agency believes the requirements for a thorough geologic site characterization for a GS project are necessary to protect USDWs from endangerment.

Commenter Name: Robert J. Finley Letter ID: 0180 Commenter Organization: Illinois State Geological Survey Comment ID: 23623

Comment: (i)(j)

These two sections appear to conflict in that (j) asks for the proposed formation testing program, which certainly can be defined in advance of drilling the injection well, but preceding section (i) asks for the results of compatibility testing based on the results of the proposed program. Also, what does compatibility mean? Modeling to date suggests that there may be both dissolution and precipitation of mineral phases as brine containing dissolved CO2 reacts with reservoir and confining layer rock. What is the standard for compatibility? If the apertures of microfractures are first enlarged but then carbonate or other minerals are expected to be reprecipitated, is that compatible? Much more appropriate would be to ask for the expected pathway ofgeochemical and geochemical reactions with the standard being that the expected pathways present no substantive risk of compromise to the sealing systems.

Response: EPA agrees that the formation testing plan must be approved before the owner or operator can generate necessary data on the compatibility of the CO2 stream with fluids in the injection zone and minerals in both the injection and the confining zone. In response to comments and based on an evaluation of the proposed requirements, EPA revised subpart §146.82 so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

Regarding compatibility, EPA clarifies that owners or operators must also present information on the compatibility of the CO2 stream with fluids in the injection zone and minerals in both the injection and the confining zone(s), as determined through the formation testing program and on the compatibility of the CO2 with the materials used to construct the well (§146.82(c)(3)). Based on this, the Director will determine the potential for geochemical reactions between the injectate (CO2) and the host geologic formations, which could result in the plugging of pore spaces or the

dissolution of formation minerals.

Commenter Name: Thomas Curtis Letter ID: 0181 Commenter Organization: American Water Works Association (AWWA) Comment ID: 23654 Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: In its comments, AWWA makes several recommendations for the following specific items to be included in the final regulation:

- A permit process for geologic sequestration (separate from the coal plant), with required monthly reporting similar to the NPDES permit/reporting process;

Response: EPA believes that permitting under the UIC Program is an essential element for ensuring that GS projects are operated in a manner that protects USDWs from endangerment. The UIC Program establishes minimum federal requirements for owners or operators of GS wells; and, States may choose to develop requirements that are as stringent as or more stringent than the minimum federal requirements. This affords states the flexibility to implement the program while ensuring that USDWs are protected from endangerment. If a State does not develop UIC Program requirements for Class VI wells, EPA implements the program in those states. The Agency clarifies that all owners or operators of Class VI wells must comply with the requirements under Subpart H of 146 in order to inject CO2 for GS through a Class VI well. A UIC injection well permit application is separate from other permitting activities (i.e., coal plant permitting).

EPA believes that the extensive requirements for geologic site characterization (at §146.82), AoR evaluation (§146.84), and testing of the well during drilling (§146.87) are appropriate to ensure that permitting authorities have the necessary information to evaluate whether a specific site will allow safe injection of CO2. EPA adds that submittal and review of monitoring data (as required at §146.90) and the AoR reevaluation process (§146.84(e)) will provide an opportunity for an ongoing review of the site and a dialogue between the Director and the owner or operator to ensure that the project is being operated in a manner that protects USDWs from endangerment.

EPA is developing a number of technical guidances and implementation materials to assist owners oroperators and Directors in the permitting process. These guidances will provide recommendations regarding performing many of the activities necessary for applying for a permit, including developing all required plans and conducting site characterizations that meet the requirements of §146.82. These guidances can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

EPA clarifies that owners or operators of Class VI GS wells must comply with UIC semi-annual reporting requirements at 146.91(a). EPA believes that semi-annual reporting is appropriate to ensure that permitting authorities can maintain proper oversight of GS projects, particularly in the early stages of rule implementation and deployment of GS technologies. The Agency also clarifies that permitting authorities may choose to require more frequent reporting, at the discretion of the

Director.

EPA clarifies that it does not have the authority under the SDWA (and associated UIC requirements) to alter permitting requirements issued under other environmental statutes for coal plants or any CO2 sources. The UIC program's authority is limited to the injection operation and ensuring that USDWs are protected from endangerment.

Commenter Name: Thomas Curtis Letter ID: 0181 Commenter Organization: American Water Works Association (AWWA) Comment ID: 23656 Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: In its comments, AWWA makes several recommendations for the following specific items to be included in the final regulation:

- Requirement for formal technical, managerial, and financial plans for GS owners/operators; and

Response: EPA agrees that requiring project plans for GS wells is appropriate. The final GS rulerequires owners and operators to develop, gain approval for, and implement a series of projectspecific plans, including: an area of review (AoR) and corrective action plan, a testing and monitoring plan, an injection well plugging plan, a post-injection site care and site closure plan, and an emergency and remedial response plan. All of these plans must be submitted at the time of permit application (§146.82(a)), along with a demonstration that appropriate financial resources are available, pursuant to requirements at §146.85, to fund all required activities. EPA believes that the requirement for the plans associated with GS projects will promote an ongoing dialogue between the owner or operator and the Director to ensure that USDWs are protected from endangerment. EPA is developing guidances to assist owners or operators in describing how to prepare the project plans and how to meet the financial responsibility requirements for GS wells. The guidances can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Thomas Curtis Letter ID: 0181 Commenter Organization: American Water Works Association (AWWA) Comment ID: 23724 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Part 146.82(b) AWWA recommends revising the second to the last sentence to read:

The map should also show faults and other major geologic discontinuities, ifknown or suspected.

Response: 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 GS rule. Please see the final rule and preamble for additional information.

Commenter Name: Thomas Curtis Letter ID: 0181 Commenter Organization: American Water Works Association (AWWA) Comment ID: 23725 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Part 146.82(b) AWWA recommends that the last sentence be deleted from this part. Owner/operators should be required to go beyond the data available in the public record to identify some of the features listed in this requirement. For example, the owner/operator should be required to do its due diligence to identify all abandoned wells, plugged wells or old boreholes in the area of review. While public records may be a good starting point for the identification of these features, given the fact that some of the existing wells could be decades old, it is hard to believe that records would exist for every one of them. EPA should mandate that owner/operators use well identification technology to locate any existing wells that are not listed in the public record.

AWWA recommends revising this part to read:

A surface map showing the injection well(s) for which a permit is sought and the applicable area of review. Within the area of review, the map must show the number, or name and location of all injection wells, producing wells, abandoned wells, plugged wells or dry holes, deep stratigraphic boreholes, State or EPA approved subsurface cleanup sites, surface bodies of water, springs, mines (surface and subsurface), quarries, water wells and other pertinent surface features including structures intended for human occupancy and roads. The map should also show faults, if known or suspected. The owner or operator must include all information available in the public record, as well as conducting independent site investigations to locate any of the above features that may not be identified in the public record.

Response: EPA believes that a determination about whether data/information is outside or within the public record will be site-specific, and based on knowledge of the site, data availability, and data quality. For instance, in meeting the requirement to tabulate information on wells in the AoR, the Director has the discretion to require the owner or operator to supplement a data records search, including requiring ground or airborne surveys for wells, if there is reason to believe, based on knowledge of the site or of available data bases, that the incompleteness of available information could compromise USDW protection from endangerment.

Commenter Name: Thomas Curtis Letter ID: 0181 Commenter Organization: American Water Works Association (AWWA) Comment ID: 23726 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Part 146.82 (c) AWWA recommends revising this part to read:A map delineating the area of review based upon modeling, using all available data including data obtained during geophysical logging and testing of the well and the formation as required by paragraphs (l), (r), and (s) of this section.

Response: EPA clarifies that the map of the AoR must reflect the model inputs, including the extensive geologic information, data collected during the site characterization process (e.g., information about artificial penetrations), and anticipated operating parameters (e.g., injection rates) submitted with the permit application under 146.82. EPA adds that the final rule, at §146.82(c)(1), requires that the final area of review be “based on modeling, using data obtained during logging and testing of the well and the formation...”

Commenter Name: Thomas Curtis Letter ID: 0181 Commenter Organization: American Water Works Association (AWWA) Comment ID: 23727 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Part 146.82(d)(1) AWWA recommends revising this part to read:

Isopach maps of the area of review, including the proposed injection and confining zone(s), a structural contour map hung on the top of the proposed injection zone, and at least two geologic cross sections of the area of review showing the geologic formations from the surface to total depth.

Part 146.82(d)(2) AWWA recommends revising this part to read:

Location, orientation, and properties of known or suspected subsurface faults, fractures, and other discontinuities that may transect the confining zone(s) in the area of review and a determination that they would not interfere with

containment.

Part 146.82(d)(3) AWWA recommends revising this part to read:

Information on the seismic history within the proposed area of review including presence and depth of seismic sources, knowledge of previous seismic events and history of these events, and a determination that the seismicity would not

interfere with containment.

Part 146.82(d)(4) AWWA recommends revising this part to read:

A spreadsheet with data on the depth, areal extent, thickness, mineralogy, porosity, permeability, capillary and reservoir pressure of the injection and confining zone(s) within the area of review; including any geologic/facies changes based upon field data which may include geologic cores, outcrop data, seismic surveys, well logs, and names and lithologic descriptions.

Part 146.82(d)(5) AWWA recommends revising this part to read:

Geomechanical information on fractures, stress, ductility, rock strength, and in situ fluid pressures on the injection and confining zones within the area ofreview.

Part 146.82(e) AWWA recommends revising the first sentence to read:

A spreadsheet of all wells and other artificial penetrations within the area of review which penetrate the injection or confining zone(s).

Part 146.82(f) AWWA recommends revising this part to read:

Potentiometric (water level) surface maps and stratigraphic cross sections indicating the general vertical and lateral limits of all USDWs including existing aquifers not meeting the definition of a USDW that are either currently being utilized as private or public water supplies or are identified as a future water supply, water wells and springs within the area of review, their positions relative to the injection zone(s) and the direction and velocity of water movement. At least two geologic cross sections showing the thickness and general

vertical and lateral limits of all USDWs within the area of review.

Part 146.82(g) This part should provide a list of the formations for which baseline geochemical data should be obtained. AWWA recommends revising this part

to read:

Collection of baseline geochemical data on the subsurface formations, including all USDWs in the area of review. At a minimum, geochemical data should be provided for the injection formation, the confining zone immediately above the injection zone, the nearest adjacent porous and permeable formation to the confining zone, all USDWs in the area of review including existing aquifers not meeting the definition of a USDW that are either currently being utilized as private or public water supplies or are identified as a future water supply, as well as for any additional formations as required by the Director.

Part 146.82(h)(1) AWWA recommends revising this part to read:

Average and maximum daily injection rate and volume of the carbon dioxide

stream.

Part 146.82(h)(2) AWWA recommends revising this part to read:

Average and maximum surface injection pressure;

Part 146.82(k) AWWA recommends revising this part to read:

Proposed stimulation program and a determination that stimulation will not interfere with or breach the confining layer.

Part 146.82(n) AWWA recommends revising this part to read:

Engineering drawings of the surface and subsurface construction details of the system, including design features for surge control and water hammer protection, including the following:(i) Record drawings, based upon inspections by the engineer of record or persons under his direct supervision, with al deviations noted; (ii) Copies of the mill certificates of all casings used in the construction of the well; (iii) Certification of completion submitted by the engineer of record; (iv) An operation manual including emergency procedures; (v) Proposed monitoring program and data to be submitted; (vi) Proof that the existence of the well and any associated monitoring wells have been recorded with the permanent warranty deed or other instrument of conveyance as a two page proviso or addendum that contains certification of the locations of the wells (by metes and bounds) and a detailed sketch of the parcel that shows the location of the well. The location shall be measured by a certified land surveyor, and shall contain the surveyor's signature, registration number, official seal, and the following statement: "I hereby certify that this survey was made under my responsible direction and supervision, and is a correct representation of the land surveyed."

Part 146.82(q) As the Director should approve the corrective action plan prior to any activities taking place within the area of review, AWWA recommends revising this part to read:

The plan for corrective action on artificial penetrations within the area of review and the status of any correction actions, if previously approved by the

Director.

Part 146.82(s) As the well should not yet be constructed when the owner/operator applies for the permit, the demonstration of mechanical integrity should not have occurred yet. Therefore, AWWA recommends revising this part to read:

The proposed demonstration method for mechanical integrity pursuant to §146.89.

Part 146.82(v) As monitoring wells may also have to be plugged, AWWA recommends revising this part to read:

Proposed injection and monitoring well(s) plugging plan required by §146.92(b).

Response: EPA disagrees that the suggested revisions are necessary. While EPA acknowledges and agrees with the importance of many of the specific items the commenter suggests adding to the text,the Agency believes that it is important to allow some flexibility to address the varied and sitespecific conditions at GS sites. EPA anticipates that the iterative process by which owners or operators submit and Directors review geologic and other information to support the permit application will promote the most effective approach to addressing USDW endangerment. EPA adds that if the Director believes that additional information is needed to support a determination about the suitability of a proposed site, it is within his/her authority to request it.

EPA notes that the final rule does include reference to capillary pressure in §146.82(a)(3)(iii), “Data on the depth, areal extent, thickness, mineralogy, porosity, permeability, and capillary pressure of the injection and confining zone(s); including geology/facies changes based on field data which may include geologic cores, outcrop data, seismic surveys, well logs, and names and lithologicdescriptions.”

EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Thomas Curtis Letter ID: 0181 Commenter Organization: American Water Works Association (AWWA) Comment ID: 24374 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: Part 146.82(d)(3) AWWA recommends revising this part to read:

Information on the seismic history within the proposed area of review including presence and depth of seismic sources, knowledge of previous seismic events and history of these events, and a determination that the seismicity would not

interfere with containment.

Response: EPA agrees that consideration of local and regional seismicity is important. This information is required for GS projects at §146.82(a)(3)(v). The site characterization provisions in the GS rule also require the owner or operator to submit data on known or suspected faults in the AoR (§146.82(a)(3)(ii)). Beyond the AoR (the specific project area) EPA notes that the site characterization requires a review of the local and regional geology, and detailed review of any known or potential seismically active terrain in the vicinity of a proposed GS site would certainly be required in a GS site characterization.

Commenter Name: Robert F. Van Voorhees Letter ID: 0190 Commenter Organization: Carbon Sequestration Council Comment ID: 24420 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(h)

Proposed CCS Group Recommendations: (h) Proposed operating data: (1) Average and maximum daily INJECTION rate and volume of the carbon dioxide

stream; (2) Average and maximum SURFACE injection pressure;

ClarificationsBasis for CCS Group Comments: Technical clarifications.

Rule Provision: 146.82(i)

Proposed CCS Group Recommendations: Support the proposed language.

Basis for CCS Group Comments: Agree with EPA’s rationale.

Rule Provision: 146.82(j)

Proposed CCS Group Recommendations: Support the proposed language.

Basis for CCS Group Comments: Agree with EPA’s rationale.

Rule Provision: 146.82(k)

Proposed CCS Group Recommendations: (k) Proposed stimulation program and a determination that stimulation will not compromise containment;

Basis for CCS Group Comments: "Interfere" is too ambiguous and should be replaced by "compromise" which limits concerns to situations where containment may be lost.

Rule Provision: 146.82(n)

Proposed CCS Group Recommendations: (n) A WELLBORE schematic or other appropriate drawings of the surface and of the subsurface construction details

of the well AND SURFACE WELLHEAD CONSTRUCTION.

Basis for CCS Group Comments: (n) Technical clarification.

Rule Provision: 146.82(q)

Proposed CCS Group Recommendations: (q) The ANY status of corrective action on wells in the area of review;

Basis for CCS Group Comments: Clarifies that wells not needing corrective action

will not have a corrective action status.

Response: EPA acknowledges the commenter’s support for portions of the subject requirements. EPA disagrees that the suggested technical clarifications are necessary. EPA adds that it is developing guidance for owners or operators on the geologic site characterization and AoR and corrective action processes. These guidances will provide recommendations and clarify the intent of all required elements of a permit application. The guidances can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Jeff W. Sheets Letter ID: 0192 Commenter Organization: ConocoPhillips Comment ID: 23890

Comment: o Area/field Permitting- Many CCS sites will be multi-well sites, with thepossibility, as in EOR applications, for hundreds of wells. It is recommended that an area/field permitting approval be implemented to simplify the process and allow for well-by-well flexibility in requirements where that makes sense.

Response: EPA disagrees that area permits are appropriate for GS wells. The Agency believes that individual injection well permits are essential to ensure that every GS well is constructed, operated, monitored, plugged, and closed in a manner that is protective of USDWs.

EPA believes that the efficiencies and administrative benefits offered by area permits can be achieved through well executed plans required for GS wells. EPA envisions that planned additional GS wells should be discussed as part of the ongoing dialog between the owner or operator and the Director. For example, EPA expects the AoR plan to consider anticipated future wells so that the Director is able to consider all anticipated injection and resultant pressure changes in evaluating the plan and setting permit conditions. Similarly testing and monitoring plans should account for future injection wells to ensure that ground water monitoring or CO2 plume and pressure front tracking are planned appropriately.

Through this iterative planning process, the owner or operator and Director can identify ways to streamline future submittals, including permit applications for future wells in the same field. For example, the parties could identify common, static components of the project that could be incorporated into future permit applications and facilitate submittal of data by the owner or operator and review and approval by the Director.

EPA also believes that requiring separate permit applications for each well will ensure that the public has an opportunity to provide input on each well in the field as it is constructed or brought online. In addition, where wells are re-permitted as GS wells (e.g., in ER projects, which may typically operate under Class II area permits), EPA believes that the unique nature of GS necessitates individual review of each well to ensure the re-permitted wells were engineered and constructed to achieve the goals of §§146.86(b) and 147.87(a) and ensure protection of USDWs from endangerment.

EPA disagrees that many GS sites would have the hundreds of wells that are typical of some Class II ER projects. EPA believes that newer technologies, such as horizontal well injection will likely reduce the number of wells in GS projects.

Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24649 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(h)

Anadarko Petroleum Corporation (APC) Comments: (h) Proposed operating data: (1) Average and maximum daily INJECTION rate and volume of the carbon dioxide

stream; (2) Average and maximum SURFACE injection pressure;

Rationale: Technical clarifications.

Response: EPA disagrees that the suggested technical clarifications are necessary. EPA adds that it is developing guidance for owners or operators on the geologic site characterization process. Theguidance will provide recommendations for owners and operators to consider when completing a permit application. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24650 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(n)

Anadarko Petroleum Corporation (APC) Comments: (n) A WELLBORE schematic or other appropriate drawings of the surface and of the subsurface construction

details of the well AND SURFACE WELLHEAD CONSTRUCTION.

Rationale: Technical clarification.

Response: EPA disagrees that the suggested technical clarifications are necessary. EPA adds that it is developing guidance for owners or operators on the geologic site characterization process. The guidance will provide recommendations for owners and operators to consider when completing a permit application. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Craig R. Walters Letter ID: 0200 Commenter Organization: Anadarko Petroleum Corporation Comment ID: 24651 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Rule Provision: 146.82(q)

Anadarko Petroleum Corporation (APC) Comments: q) The ANY status of corrective action on wells in the area of review;

Rationale: Clarifies that wells not needing corrective action will not have a

corrective action status.

Response: EPA disagrees that the suggested technical clarifications are necessary. EPA adds that it is developing guidance for owners or operators on the geologic site characterization and AoR and corrective action process. The guidance documents will provide recommendations for owners and operators to consider when completing a permit application. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Richard Guinn Letter ID: 0210 Commenter Organization: Eastman Chemical Company Comment ID: 22720

Comment: §146.82 Required Class VI permit information. (b) "A map showing the injection well(s) for which a permit is sought and the applicable area of review. Within the area of review, the map must show the number, or name and location of all injection wells, producing wells, abandoned wells, plugged wells or dry holes, deep stratigraphic boreholes, State or EPA approved subsurface cleanup sites, surface bodies of water, springs, mines (surface and subsurface), quarries,water wells and other pertinent surface features including structures intended for human occupancy and roads. The map should also show faults, if known or suspected. Only information of public record is required to be included on this map;"

The note that "only information of public record is required to be included on this map" may leave out deep oil and gas wells, particularly older wells. The presence of such non-public but "known" information may be eligible for inclusion as "known" under 144.55(a).

§146.82 Required Class VI permit information (e) "A tabulation of all wells within the area of review which penetrate the injection or confining zone(s). Such data must include a description of each well's type, construction, date drilled, location, depth, record of plugging and/or completion, and any additional information the Director may require;"

We recommend striking out "all wells" and replacing with "all known wells". Requiring that all wells or other artificial penetrations into injection or confining zones within the AoR be identified and information on depth and closure be provided can be costly and sometimes accurate information is

difficult to obtain for older wells within the AoR. EPA's assistance in obtaining and storing this information would be helpful to CCS operators.

Response: EPA believes that a determination about whether information necessary (for a specific GS project) is outside or within the public record will be site-specific and based on knowledge of the site, data availability, and data quality. For instance, in meeting the requirement to tabulate information on wells in the AoR, the Director has the discretion to require the owner or operator to supplement a data records search if there is reason to believe that the incompleteness of available information could compromise USDW protection from endangerment.

Commenter Name: Paul L. Carpinone Letter ID: 0212 Commenter Organization: Tampa Electric Company Comment ID: 22909 Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: - The Final Rule must not make the application process overly burdensome or unrealistic by requiring detailed information that may not be available at the time of the initial application; instead, the Final Rule should allow for submission of updated information regarding a CO2 GS well and its AoR as that

information becomes available.

Response: EPA disagrees that any of the protective requirements are unnecessary, and believes that the Class VI GS requirements for obtaining a permit are tailored so that they are appropriate for theunique nature of injecting large volumes of CO2 into a variety of geological formations for longterm storage.

EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to besubmitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of information to be submitted. In addition, section §146.82 in the final rule is similar to the permit application requirements for other injection well classes, which could help avoid confusion about how to meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to be submitted before operation of the well is authorized are very similar to those for Class I wells, with modifications and additions that address the unique challenges and types of data

collected for GS wells.

Commenter Name: Diane VanDe Hei Letter ID: 0213 Commenter Organization: Association of Metropolitan Water Agencies (AMWA) Comment ID:

22926 Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Drinking water utilities must be consulted during the review of any CO2 sequestration permit application. AMWA recommends that as part of the process, all drinking water utilities that draw from an aquifer in the area of review (AoR) of a potential CO2 sequestration project should be informed and consulted.

Response: As part of the UIC permit review process in 40 CFR 124, the UIC program Director must notify certain stakeholders of any public hearings and the availability of the draft permit. EPA has added a requirement at §124.10(c)(1)(xi) that state and local oil and gas regulatory agencies and state agencies regulating mineral exploration and recovery, the PWSS program director, and all agencies that oversee injection wells in the state must be notified as part of the public notice process for a Class VI permit.

In addition, the existing public participation requirements for UIC permits at 40 CFR 124.10(c)(1)(x)(A) require notification "to any unit of local government having jurisdiction over the area where the facility is proposed to be located." EPA believes these requirements address the

commenter's concerns.

Commenter Name: Dennis R. James Letter ID: 0214 Commenter Organization: North American Coal Corporation (NAC) Comment ID: 22963 Other EPA Comment Codes and Descriptions: 1250 1.1.1.4 Flexibility is needed (performancebased standards)

Comment: Many statements in this section of the proposed rule specify exactly what types of data will be collected and how they will be presented in a permit application. Across the United States, there are widely varying geologies, available regional data sets, and how well various technologies perform. The permitting authority for a state or region should have the flexibility to determine what types of information an operator should present to adequately characterize a specific injection well site.

For example, the following statement is made: "Today’s proposal would require owners or operators to submit geochemical data on (a) the injection zone, (b) the confining zones, (c) containment zones above the confining zones in whichany potentially migrating CO2 could be trapped, (d) all USDWs, and (e) any other geologic zone or formation that is important to the proposed monitoring program." This essentially requires an operator to collect geochemical data on the entire geologic column: From the surface down to the target formation. It is important to geochemically define the target formation and its overlying seal. It is also prudent to obtain data from adjacent formations that may be involved if leakage occurs. However, does this data all the way to the surface in any way add additional USDW protection? The permitting authority should have some discretion to limit the required data, based on the geology of the area.

Response: The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate and transport model development (e.g., by providing appropriate input parameters), and provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. The baseline geochemical information will allow the owner or operator and permitting authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid movement.

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion to require geochemical analysis of additional subsurface zones if in the Director's opinion they are necessary for the protection of USDWs from endangerment.

EPA agrees that site characterization should be site-specific, particularly in light of the variety of geologic settings in which GS may be employed. EPA believes that, while there is a large amount of required information, the owner or operator is given flexibility in determining what methods are used to demonstrate the suitability of a potential site. EPA envisions an ongoing dialogue between the Director and the owner or operator during the permitting process (as well as throughout the operation of the site).

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Ronald Evans Letter ID: 0215 Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24288

Comment: IV. SUGGESTED CHANGES TO LANGUAGE OF PROPOSED RULE

[In the sections below, the text in CAPS denotes added text.]

A. § 146.82 Required Class VI permit information

This section of the proposed rule sets forth the information which the owner or operator must submit to the Director in order to obtain a Class VI well permit.All of the information specified must be part of the permit application. But some data are not necessary in light of other provisions of the current proposal, and some are not attainable prior to well drilling (applicants will not drill the well until it has been approved, otherwise they risk drilling an unusable well). Still other data can only be obtained after injection activities have been initiated. Post-drilling and post-injection data should not be required as part of the application process but instead should be considered confirmatory data that may be submitted after they are obtained. In general, the proposed rule should be modified to require submission of only those data which are needed for consideration of the initial permit application, and only those data that may be reasonably obtained prior to commencement of installation and operation of the injection well.

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of information to be submitted. In addition, section §146.82 in the final rule is similar to the permit application requirements for other injection well classes, which could help avoid confusion about how to meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to be submitted before operation of the well is authorized are very similar to those for Class I wells, with modifications and additions that address the unique challenges and types of data

collected for GS wells.

Commenter Name: Ronald Evans Letter ID: 0215 Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24289 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: 1. EPA Proposed: §146.82 (f) Maps and stratigraphic cross sections indicating the general vertical and lateral limits of all USDWs, water wells and springs within the area of review, their positions relative to the injection zone(s) and the direction of water movement, where known;

So long as the Applicant proposes to inject CO2 below the lowermost USDW, as proposed under the rule, there is no justification to require maps and stratigraphic cross sections for the entire extent of those USDWs above the lowermost USDW, although mapping and stratigraphic cross sections in the immediate vicinity of the proposed injection locations (e.g. where the injection wells will be drilled) should still be required. Data regarding all USDWs in the AoR will likely be costly and/or difficult to collect and, except as noted above, the usefulness of those data seems questionable.

Accordingly, Denbury suggests that subparagraph (f) should be modified as

follows:(f) Maps and stratigraphic cross sections indicating the general

vertical and lateral limits of all THE LOWERMOST USDWs

, ALL USDWS IN THE IMMEDIATE VICINITY OF THE PROPOSED INJECTION WELL(S), water wells and springs within the area of review, their positions relative to the injection zone(s) and the direction of water movement, where known;

Response: EPA disagrees with the commenter that there is no justification to require maps and stratigraphic cross sections for the entire extent of those USDWs above the lowermost USDW. EPA believes that a thorough understanding of the hydrogeologic conditions of all USDWs in the AoR is necessary. EPA clarifies that §146.82(a)(5) requires, as part of the site characterization and permit application process, that operators submit maps and cross sections indicating the general vertical and

lateral limits of all USDWs within the area of review. This information will result in information on and a characterization of the number, location, and depth of USDWs. The Director has the authority to request additional hydrogeologic data or other data on USDWs as well.

Commenter Name: Ronald Evans Letter ID: 0215 Commenter Organization: Denbury Resources, Inc. (DRI) Comment ID: 24290 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: 2. EPA Proposed : §146.82(l) The results of the formation testing program as required in paragraph (j) of this section; (r) All available logging and testing program data on the well required by§ 146.87; (s) A demonstration of mechanical integrity pursuant to § 146.89;

The requirements of subparts (l), (r) and (s) of § 146.82 cannot be met until after the well is drilled. For example, subparagraph (l) references (j), formation testing. Clearly formation testing is a drilling or post completion operation. Similarly, logging and mechanical integrity testing also are drilling or post well completion operations. Because this information will be collected post application approval, it should not be required prior to the granting of the Class VI permit.

Denbury suggests that EPA modify § 146.82 to eliminate subparts (l), (r) and (s) because those data do not belong in and in fact may not be available as part of a permit application.

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of information to be submitted. In addition, section §146.82 in the final rule is similar to the permit application requirements for other injection well classes, which could help avoid confusion abouthow to meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to be submitted before operation of the well is authorized are very similar to those for Class I wells, with modifications and additions that address the unique challenges and types of data

collected for GS wells.

Commenter Name: Edward Steadman Letter ID: 0220 Commenter Organization: The Energy and Environmental Research Center at the University of North Dakota Comment ID:

21631 Other EPA Comment Codes and Descriptions: 3140 2.1.4 Comments that the proposed geologic data requirements are too stringent

Comment: Page 43536. § 146.82 Required Class VI permit information. There are numerous requirements for information on formations overlying the proposed storage site. Requirements should be flexible and site-specific. The required information should be limited to relevant primary and/or secondary seals and be used to document the vulnerability or lack thereof of any USDWs in the area.

Response: EPA agrees that site characterization should be site-specific, particularly in light of the variety of geologic settings in which GS may be employed. EPA believes that, while there is a large amount of required information, the owner or operator is given flexibility in determining what methods are used to demonstrate the suitability of a potential site. EPA envisions an ongoing dialogue between the Director and the owner or operator during the permitting process (as well as throughout the operation of the site).

Commenter Name: Edward Steadman Letter ID: 0220 Commenter Organization: The Energy and Environmental Research Center at the University of North Dakota Comment ID:

21632

Comment: Page 43536. § 146.82 Required Class VI permit information. The requirement ofbaseline geochemical data on subsurface formations should be flexible and sitespecific. The required information should be limited to relevant primary and/or secondary seals and be used to document the vulnerability or lack thereof of any

USDWs in the area.

Page 43536. § 146.82 Required Class VI permit information. Well-plugging requirements can change throughout the life of a well. Therefore, requiring a well-plugging plan with the permit application is excessive and unnecessary.

Response: The Agency believes that the requirement at §146.82(a)(6) to submit baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR is appropriate and protective of USDWs. EPA believes that this data will support monitoring plan development, inform injectate fate and transport model development (e.g., by providing appropriate input parameters), and provide information needed to respond to any unexpected and unpermitted leaks outside of the injection zone. The baseline geochemical information will allow the owner or operator and permitting authority to evaluate monitoring data and identify any changes in subsurface geochemistry that may indicate fluid movement.

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the confining system and to serve as a baseline for future monitoring. The Director has the discretion torequire geochemical analysis of additional subsurface zones if in the Director's opinion they are necessary for the protection of USDWs from endangerment.

Commenter Name: Darrick Eugene Letter ID: 0223 Commenter Organization: Texas Carbon Capture and Storage Association Comment ID: 23969 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: 2. § 146.82 Required Class VI permit information

This section of the proposed rule sets forth the information which the owner or operator must submit to the Director in order to obtain a Class VI well permit. All of the information specified must be part of the permit application. But some data are not necessary in light of other provisions of the current proposal, and some are not attainable prior to well drilling (applicants will not drill the well until it has been approved, otherwise they risk drilling an unusable well). Still other data can only be obtained after injection activities have been initiated. Post drilling and post injection data should not be required as part of the application process but instead should be considered confirmatory data that may be submitted after they are obtained. In general, the proposed rule should be modified to require submission of only those data which are needed for consideration of the initial permit application, and only those data that may be reasonably obtained prior to commencement of installation and operation of the injection well.

EPA Proposed: §146.82 (f) Maps and stratigraphic cross sections indicating the general vertical and lateral limits of all USDWs, water wells and springs within the area of review, their positions relative to the injection zone(s) and the direction of water movement, where known;

So long as the Applicant proposes to inject CO2 below the lowermost USDW, as required by the proposed rule, there is no justification to require maps and stratigraphic cross sections for the entire extent of those USDWs above the lowermost USDW, although mapping and stratigraphic cross sections in the immediate vicinity of the proposed injection locations (e.g. where the injection wells will be drilled) should still be required. Data regarding all USDWs in the AoR will likely be costly and/or difficult to collect and, except as noted above, the usefulness of those data seems questionable.

Accordingly, TxCCSA suggests that subparagraph (f) should be modified as

follows:

(f) Maps and stratigraphic cross sections indicating the general

vertical and lateral limits of all THE LOWERMOST USDWs, ALL USDWS IN THE IMMEDIATE VICINITY OF THE PROPOSED INJECTION WELL(S), water wells and springs within the area of review, their positions relative to the injection zone(s) and the direction of water movement, where known;

EPA Proposed : §146.82(l) The results of the formation testing program as required in paragraph (j) of this section;(r) All available logging and testing program data on the well required by § 146.87; (s) A demonstration of mechanical integrity pursuant to § 146.89;

The requirements of subparts (l), (r) and (s) of § 146.82 cannot be met until after the well is drilled. For example, subparagraph (l) references (j), formation testing. Clearly formation testing is a drilling or post completion operation. Similarly, logging and mechanical integrity testing also are drilling or post well completion operations. Because this information will be collected post application approval, it should not be required prior to the granting of the Class VI permit.

TxCCSA suggests that EPA modify § 146.82 to eliminate subparts (l), (r) and (s) because those data do not belong in and in fact may not be available as part of a permit application.

Response: EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA believes that this revision of §146.82 addresses commenters' concerns regarding the timing of information to be submitted. In addition, section §146.82 in the final rule is similar to the permit application requirements for other injection well classes, which could help avoid confusion about how to meet the permitting requirements for Class VI wells. The requirements at §146.82(c) for information to be submitted before operation of the well is authorized are very similar to those for Class I wells, with modifications and additions that address the unique challenges and types of data

collected for GS wells.

Additionally, EPA disagrees with the commenter that there is no justification to require maps and stratigraphic cross sections for the entire extent of those USDWs above the lowermost USDW. EPA believes a thorough understanding of the hydrogeologic conditions of all USDWs in the AoR is necessary. EPA clarifies that §146.82(a)(5) requires, as part of the site characterization and permit application process, that operators submit maps and cross sections indicating the general vertical and

lateral limits of all USDWs within the area of review. This information will result in information on and a characterization of the number, location and depth of USDWs. The Director has the authority to request additional hydrogeologic data or other data on USDWs as well.

Commenter Name: Andrew Duguid Letter ID: 0226 Commenter Organization: Schlumberger Carbon Services Comment ID: 24017 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language

Comment: §146.82 Required Class VI permit information.

Proposed Rule: (b) A map showing the injection well(s) for which a permit is sought and the applicable area of review. Within the area of review, the mapmust show the number, or name and location of all injection wells, producing wells, abandoned wells, plugged wells or dry holes, deep stratigraphic boreholes, State or EPA approved subsurface cleanup sites, surface bodies of water, springs, mines (surface and subsurface), quarries, water wells and other pertinent surface features including structures intended for human occupancy and roads. The map should also show faults, if known or suspected. Only information of public record is required to be included on this map;

Schlumberger Suggested Revision: (b) A map or electronic file (e.g. GIS file) showing the injection well(s) for which a permit is sought and the applicable area of review. Within the area of review, the map must show the number, or name and location of all injection wells, producing wells, abandoned wells, plugged wells or dry holes, deep stratigraphic boreholes, State or EPA approved subsurface cleanup sites, surface bodies of water, springs, mines (surface and subsurface), quarries, water wells and other pertinent surface features including structures intended for human occupancy and roads. The map should also show faults, if known or suspected with surface expressions. Only information of public record is required to be included on this map;

Schlumberger Rationale: This may mean more clarification. It seems strange to have deep faults on a surface map. Is the map to be of the surface or of the confining unit? Also, any map will be very busy so it may be useful to be able

to submit an electronic file like a GIS file.

Proposed Rule: (c) The area of review based on modeling, using data obtained during logging and testing of the well and the formation as required by paragraphs (l), (r), and (s) of this section;

Schlumberger Suggested Revision: -

Schlumberger Rationale: We support this but it may need to be better clarified that the well must e drilled prior to the permit application

Proposed Rule: (3) Information on seismic history including the presence and depth of seismic sources and a determination that the seismicity would not interfere with containment;

Schlumberger Suggested Revision: (3) Information on seismic history of the area including the presence and depth of seismic sources and a determination that the seismicity would not interfere with containment;

Schlumberger Rationale: It seems like this requirement is at a larger scale than the AOR (maybe a regional scale) than the other requirements. This should be specified.

Proposed Rule: (4) Data on the depth, areal extent, thickness, mineralogy, porosity, permeability and capillary pressure of the injection and confining zone(s); including geology/facies changes based on field data which may include geologic cores, outcrop data, seismic surveys, well logs, and names and lithologic descriptions;Schlumberger Suggested Revision: (4) Data on the depth, areal extent, thickness, mineralogy, porosity, permeability and capillary entry pressure of the injection and confining zone(s); including geology/facies changes based on field data which may include geologic cores, outcrop data, seismic surveys, well logs, and names and lithologic descriptions;

Schlumberger Rationale: Should this include capillary pressure or capillary entry pressure?

Proposed Rule: (e) A tabulation of all wells within the area of review which penetrate the injection or confining zone(s). Such data must include a description of each well's type, construction, date drilled, location, depth, record of plugging and/or completion, and any additional information the Director may require;

Schlumberger Suggested Revision: -

Schlumberger Rationale: How will this be handled if all of this data is not

available for each well?

Proposed Rule: (f) Maps and stratigraphic cross sections indicating the general vertical and lateral limits of all USDWs, water wells and springs within the area of review, their positions relative to the injection zone(s) and the direction of water movement, where known;

Schlumberger Suggested Revision: In

Schlumberger Rationale: -

Proposed Rule: (g) Baseline geochemical data on subsurface formations, including all USDWs in the area of review;

Schlumberger Suggested Revision: (g) Baseline geochemical data on subsurface formations, including all USDWs and geochemically monitored in the area of review;

Schlumberger Rationale: All formations that are or may need to be geochemically

monitored should be included

Response: EPA agrees that deep faults would not be expressed on a surface map, but information on such faults should be provided in cross sections, which are also required as part of the materials that support a permit application.

EPA agrees that submittal of support information electronically is beneficial. The final GS rule requires owners or operators to submit permit applications, including supporting information, to EPA in an electronic format (§146.91(e)).

Regarding seismic information, EPA acknowledges that, due to the nature of seismic events and records, available information would likely address an area that is larger than the delineated AoR.EPA clarifies that the intent of this requirements is to ensure that the Director has sufficient information on which to base a determination of the suitability of a potential project site for GS.

EPA clarifies that information on capillary entry pressure must be submitted. EPA believes that capillary entry pressure measurements on core samples are necessary to quantify the amount of buoyant force the confining zone can maintain before failure (World Resources Institute, 2008).

Regarding the requirement to submit tabulations of all wells within the AoR, EPA acknowledges that public records may not contain data on every artificial penetration in the AoR (or all of the data on each well that is required for the tabulation), particularly in areas with many older wells. However, EPA notes that the inventory and review process for GS wells required at §146.84(c)(2) is similar to what is required of Class I and Class II injection well operators, that the AoR and corrective action process for these well types has been successful for many years. EPA adds that the Director has the discretion to require the owner or operator to supplement a data records search, including requiring ground or airborne surveys for wells, if there is reason to believe, based on knowledge of the site or of available data bases, that the incompleteness of available information could compromise USDW protection from endangerment.

Regarding baseline geochemical data, EPA is not specifying for which formations this information should be submitted to allow flexibility, but examples may include the following formations: a) the injection zone, b) the confining zones, c) containment zones above the confining zones in which any potentially migrating CO2 could be trapped, d) all USDWs, and e) any other geologic zone or formation that is important to the proposed monitoring program. The Director has the authority to request additional geochemical data as well.

EPA agrees that not all of the information listed at §146.82 of the proposed regulation will be available at the time the owner or operator develops their initial permit application. In response to comments and based on an evaluation of the proposed requirements at §146.82, the Agency revised this subpart so that the final regulation specifies separate requirements for information to be submitted with the permit application and before well construction is approved (at §146.82(a)) and information to be submitted before operation of the well is authorized (at §146.82(c)).

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Neeraj Gupta Letter ID: 0229 Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21811 Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Permit Organization - The proposed regulation presents a large amount of material spread throughout the document. In general, it has been easier to complete the permit process with the basic UIC form with the simplified list of attachments (this procedure was used for Region 4 and Region 5). Thus, the MRCSP would encourage EPA to prepare suggested formats and a systematically organized list of information and documents required for the permit.Response: EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. EPA is also developing a number of technical guidances and implementation materials to assist owners or operators and Directors in the permitting process. EPA expects that these guidances will assist permit writers in performing many of the activities necessary for applying for a permit, including developing all required plans and conducting site characterizations that meet the requirements of §146.82. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Neeraj Gupta Letter ID: 0229 Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21863 Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: Page 112, Reporting - The policy suggests monitoring and testing plan, AOR/corrective action plan, and Post-Injection plan. We’d recommend these documents be included as supporting attachments the permit application. This level of reporting may result in delays to the permitting process.

Response: EPA believes that the requirement that owners and operators develop an area of review (AoR) and corrective action plan, a testing and monitoring plan, an injection well plugging plan, a post-injection site care and site closure plan, and an emergency and remedial response plan are necessary to protecting USDWs from endangerment and does not believe they will result in delays to the permitting process. EPA anticipates that these plans will be attachments to the permit application and also acknowledges that not all information necessary to develop full plans will be available at the time of the initial permit application. For this reason, EPA envisions an iterative process where the owner or operator and the Director will discuss the site data being collected and how it will inform all aspects of the project, including the plans under §146.82. EPA is developing guidances to assist the owner or operator in preparing the project plans and meeting the financial responsibility requirements for GS wells. The guidances can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Neeraj Gupta Letter ID: 0229 Commenter Organization: Battelle Energy Technology (BET) Comment ID: 21868

Comment: Page 193, AOR Map- It will be difficult to provide the numerous site features on a single map as required in the regulation. Multiple maps should be allowed. Otherwise, the map must show the number, or name and location of all injection wells, producing wells, abandoned wells, plugged wells or dry holes, deep stratigraphic boreholes, State or EPA approved subsurface cleanup sites, surface bodies of water, springs, mines (surface and subsurface), quarries, water wells and other pertinent surface features including structures intended for human occupancy and roads, and faults.

Response: EPA acknowledges the comments and agrees that multiple maps may be necessary to present all of the data needed to support a determination of the suitability of a site for GS. Nothing in the GS rule prohibits this.Commenter Name: Mark Bohrer Letter ID: 0241 Commenter Organization: North Dakota Industrial Commission Comment ID: 23257 Other EPA Comment Codes and Descriptions: 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: wells. The timing of plan submittal should be linked to the activity being addressed. Site closure plans, post-closure plans, well plugging plans, etc., should not be required many years in advance since conditions, understanding of the sequestration zones, and technology change over time.

Response: EPA disagrees with the commenter's assertion that that the timing of plan submittals should be linked to the specific activity being addressed, and believes that submittal and review of each of the owner or operator's plans required at §146.82 at the time of the permit application is necessary for the Director to make a permit approval determination. While injection well plugging, post-injection site care and site closure will likely not occur for years after injection commences, the Director needs to have assurance that the owner or operator has planned for these events.

Commenter Name: Mark Bohrer Letter ID: 0241 Commenter Organization: North Dakota Industrial Commission Comment ID: 23282

Comment: 146.82(u) Site closure plans, post-closure plans, well plugging plans, etc., should not be required many years in advance since conditions, understanding of the sequestration zones, and technology change over time.

Response: EPA disagrees with the commenter's assertion that that the timing of plan submittals should be linked to the specific activity being addressed, and believes that submittal and review of each of the owner or operator's plans required at §146.82 at the time of the permit application is necessary. While injection well plugging, post-injection site care and site closure will likely not occur for years after injection commences, the Director needs to have assurance that the owner or operator has planned for these events.

Commenter Name: Kristin Henry Letter ID: 0242 Commenter Organization: Sierra Environmental Law Program, Sierra Club Comment ID: 23312

Comment: CCS Permitting Requires Specialized Technical Expertise

Permitting a Class VI well involves many complicated technical issues across a range of disciplines. Site selection alone involves characterization of geology, hydrogeology, geochemistry and geomechamics. [FN13] Well construction, interpreting monitoring data, and proper site closure are a few other highly technical areas. EPA’s proposed rule recognizes these complexities by requiring submission of numerous types of data with a permit application and continuous monitoring and reporting. But the rule does not provide for technical analysis of this

information. It entrusts evaluation of this data to the state administrator or to the EPA in non-delegated states.

[FN13: IPCC CCS 5.4.1.1, Table 5.3.]

Response: EPA clarifies that permit information is subject to technical review. Permitting authority staff will evaluate the extensive data that owners or operators submit under §146.82 to determine thesuitability of a potential project site for GS. EPA adds that the staff in state primacy agencies and EPA regional offices (who will review permit applications in states that do not have primacy) have years of experience with the current UIC injection well classes, have permitted deep injection wells in the past, and have relevant specialties in geology, engineering, and related disciplines.

EPA is developing guidance on site characterization for GS projects to assist owners or operators and Directors in evaluating permit requirements and applications under §146.82. The guidance provides recommendations regarding characterizing the regional geology and hydrogeology of a proposed GS site as well as performing the necessary geochemical, geomechanical, and geophysical analyses of the injection and confining zone. Additionally, EPA expects that this guidance will assist permitting authorities in evaluating initial permits for Class VI injection wells with technical assistance as needed. The guidance can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.

Commenter Name: Kristin Henry Letter ID: 0242 Commenter Organization: Sierra Environmental Law Program, Sierra Club Comment ID: 23314 Other EPA Comment Codes and Descriptions: 5600 2.11 Comments related to UIC Program primacy for Class VI wells; 5700 2.12 Comments on the proposed duration of Class VI permits (seeking comment)

Comment: • EPA - advised by experts and regional stakeholders - and not individual states, should make permitting decisions on CCS projects, at least for the first few years. • Permits should be issued in stages, to be adaptive to advances in knowledge, science and regulation, not for the operating life of the well.

Response: EPA agrees that an adaptive approach to address the availability of new information and technology is appropriate. EPA plans to, every six years, collect and review project data on early GS projects, including site characterization, operational, monitoring, and modeling data, to determine whether the appropriate amount and types of information and appropriate documentation are being collected, and to determine if modifications to the requirements are appropriate or necessary.

EPA disagrees that it should be the only entity to issue permits during the first few years after promulgation. EPA acknowledges the expertise of existing State, Tribal, and Territorial programs that implement the UIC requirements under Section 1422 of the SDWA (Class I, III, IV, and V wells) and state oil and gas agencies that have been regulating Class II UIC wells for decades under section 1425 of SDWA. These agencies already understand the technical and administrative issues involved in construction, operation, injection and permitting as well as, in the case of Class II operators issues related to CO2 injection, subsurface operations, and pipeline transport. EPA believes that existing programs can adapt this expertise to the new requirements for Class VI wells and will be able to develop a primacy application for Class VI wells under section 1422 of SDWA.

Additionally, States can use multiple authorities beyond those afforded under the SDWA including surface access and land rights, unitization of fields, pore space ownership, mineral rights, site safety and emergency preparedness, and maximization of State oil and gas resource exploitation.

EPA expects that both Headquarters and the Regions will work closely with the states during the early permitting process to ensure that flexibility is applied in a manner that ensures a consistent level of USDW protection from endangerment. EPA designed flexibility into the regulations to ensure that site-specific factors can be accounted for and expects that permit writers will usediscretion where site-specific factors are important. As part of its adaptive approach, EPA also plans to review initial permits (after they are granted) to ensure that USDW protection goals have been consistently met across differing geologic situations. If necessary, EPA will reevaluate the flexibility granted to states in the rule. As part of its adaptive approach, if EPA finds that there is not sufficient consistency in the permits so that USDWs are not being sufficiently protected from endangerment, it will consider changes to the permit requirements in the future.

Regarding the commenter's request that permits be issued in stages, EPA clarifies that the final rule maintains the lifetime permit provision and that the permit extends through the post-injection site care period (144.36(a)). However, it also adds a requirement that the Director review each Class VI permit at least once every 5 years to determine whether it should be modified, revoked and reissued, terminated or a minor modification made as provided in §§144.39, 144.40, or 144.41. The Director’s review will be informed by the owners’ or operators’ iterative reevaluation of the project. Specifically, the final rule includes a requirement that the AoR be reevaluated at least every five years, and also requires owners or operators to review and update the AoR and corrective action plan, the testing and monitoring plan, and the emergency and remedial response plan throughout the life of the project (146.84(e), 146.90(j), and 146.94(d)). Owners or operators must review each plan and identify necessary amendments or demonstrate to the Director that no amendment is needed. In no case can reviews occur less often than once every five years. The iterative process and subsequent plan reevaluations ensure that time and resources are committed to the most critical aspects of the permit in preventing endangerment to USDWs.

Commenter Name: Michel Paque Letter ID: 0259 Commenter Organization: Ground Water Protection Council Comment ID: 24877 Other EPA Comment Codes and Descriptions: 1240 1.1.1.3 Suggested changes/edits to rule language; 4710 2.7.1 Proposed submissions required for permit applications (seeking comment)

Comment: EPA Proposal: (h) Proposed operating data:

(1) Average and maximum daily rate and volume of the carbon dioxide stream; (2) Average and maximum injection pressure; (3) The source of the carbon dioxide stream; and (4) An analysis of the chemical and physical characteristics of the carbon dioxide stream;

GWPC Recommendations: (h) Proposed operating data:

(1) Average and maximum daily injection rate and volume of the carbon dioxide

stream; (2) Average and maximum surface injection pressure; (3) The source of the carbon dioxide stream; and (4) An analysis of the chemical and physical characteristics of the carbon dioxide stream;

Rationale: Clarification: Addition of the term surface in (h)(d) will make it clear as to where the injection pressure is to measured.

Rule Provision: 146.82(i)

EPA Proposal: (i) The compatibility of the carbon dioxide stream with fluids inthe injection zone and minerals in both the injection and the confining zone(s), based on the results of the formation testing program, and with the materials used to construct the well;

(j) Proposed formation testing program to obtain an analysis of the chemical and physical characteristics of the injection zone and confining zone;

GWPC Recommendations: Support the proposed EPA language.

Rationale: Agree with EPA’s rationale.

EPA Proposal: (k) Proposed stimulation program and a determination that stimulation will not interfere with containment;

(l) The results of the formation testing program as required in paragraph (j) of this section;

(m) Proposed procedure to outline steps necessary to conduct injection operation;

(n) Schematic or other appropriate drawings of the surface and subsurface construction details of the well;

(o) Injection well construction procedures that meet the requirements of § 146.86;

GWPC Recommendations: (k) Proposed stimulation program and a determination that stimulation will not compromise containment;

(l) The results of the formation testing program as required in paragraph (j) of this section;

(m) Proposed procedure to outline steps necessary to conduct injection operation;

(n) A wellbore schematic of the subsurface construction details and surface

wellhead construction.

(o) Injection well construction procedures that meet the requirements of § 146.86;

Rationale: "Interfere" is too ambiguous and should be replaced by "compromise" which limits concerns to situations where containment may be lost.

EPA Proposal: (p) Proposed area of review and corrective action plan that meets the requirements under § 146.84;

(q) The status of corrective action on wells in the area of review;

(r) All available logging and testing program data on the well required by § 146.87;(s) A demonstration of mechanical integrity pursuant to § 146.89;

(t) A demonstration, satisfactory to the Director, that the applicant has met the financial responsibility requirements under § 146.85;

GWPC Recommendations: (p) Proposed corrective action plan for artificial penetrations within the area of review, if necessary

(q) All available logging and testing program data on the well required by § 146.87;

(r) The proposed demonstration method for mechanical integrity pursuant to

(s) A demonstration, satisfactory to the Director, that the applicant has met the financial responsibility requirements under § 146.85;

Rationale: (q) Should be deleted because it is not part of an applicationprocess but, rather a post permitting activity. This would result in a renumbering of the subsections after the new (q).

Rule Provision: 146.82(u)

EPA Proposal: (u) Proposed testing and monitoring plan required by § 146.90;

(v) Proposed injection well plugging plan required by § 146.92(b);

(w) Proposed post-injection site care and site closure plan required by § 146.93(a);

(x) Proposed emergency and remedial response plan required by § 146.94; and

(y) Any other information requested by the Director.

GWPC Recommendations: (t) Proposed testing and monitoring plan required by § 146.90;

(u) Proposed injection and monitoring well(s) plugging plan required by § 146.92(b);

(v) Proposed post-injection site care and site closure plan required by § 146.93(a);

(w) Proposed emergency and remedial response plan required by § 146.94; and

(x) Any other information requested by the Director.

Rationale: Need to address the plugging of monitoring well(s), if any, included in the project.Response: EPA acknowledges the commenter’s support for portions of the subject requirements. EPA disagrees that the technical clarifications suggested are necessary. EPA adds that it is developing guidance for owners or operators on the geologic site characterization and AoR and corrective action processes. These guidances will provide recommendations and clarify the intent of all required elements of a permit application. The guidances can be found on EPA’s website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.