This comment letter response contains two parts:   

(1) The original submittal from the commenter.

(2) A data base printout of EPA’s response to each point raised by the commenter.

Notes about the response letters:

• The response letters were generated by a data base used to track the content of all public

comment submittals and ensure that the Agency responds to each. Each comment letter

was assigned a Letter ID that corresponds to the last four digits of the docket number of the

original comment (as posted on www.regulations.gov).

• Each response letter includes: comment text; an EPA‐assigned comment code; and an

individual response. These are described and explained below.  

• The data base contains Comment text from the letters submitted by commenters.  

Many hard copy letters were scanned into electronic format for inclusion in the data

base. As a result, there may be some typographical errors attributable to optical

character recognition issues.  However, all original submittals were reviewed in the

process of drafting responses to ensure that the comment content was understood and

appropriately addressed.

• The content of each comment letter was divided into topic areas and assigned a unique

Comment ID.  Additionally, one or more Comment Codes (i.e., unique topic area ID) was

assigned to each discrete point raised by a commenter. This information was added to

the data base. To inform final rulemaking decisions, all comments and information

received on a given topic were reviewed by technical experts in each rule area (e.g., on

construction requirements).  

• Following decisions on the final rule requirements, Individual responses were drafted

by topic area to ensure completeness and consistency of the responses with the final

rule and other responses to similar comments.  Each discrete point made by a

commenter was given a unique response.

• Upon completion of comment responses, all information was entered into the data base.

Each letter response is a compilation of each comment and its individual response,

compiled in the order of the original comment letter.  As a result of this process, there is

repetition in the response text.  The Agency believes this approach ensures completeness

and attention to each comment letter that was submitted.   

• All comments in a topic area were reviewed, evaluated, and responded to concurrently.  

Responses on each topic area are compiled and are also available in the rulemaking docket.








Letter ID: 0192 

Commenter: Jeff W. Sheets 

Organization: ConocoPhillips 

Letter ID: 0192 Comment ID: 23886 Letter Lines: 60 to 64 

Comment Code: 1000 1. General and Administrative Comments 

Comment: In addition to the Multi-Stakeholder Discussion Group mentioned above, 

ConocoPhillips has formulated our specific perspective on EPA rulemaking working 

with organizations including the American Petroleum Institute, the CO2 Capture 

and Storage (CCS) Contact Group (VanVoorhees/Bryan Cave). We support the 

consensus of these groups, taken in their entirety. Our company's comments 

Individual Response: EPA acknowledges the comment. Please see the remainder of EPA's 

responses to this comment, American Petroleum Institute’s comment, and CCS’s comment for 

further details. For additional information on EPA's final regulatory approach, please see the 

final rule and preamble as well as the rulemaking docket. 

Letter ID: 0192 Comment ID: 23887 Letter Lines: 72 to 86 

Comment Code: 1210 1.1.1 Comments about the proposed rule 

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

Comment Code: 1420 1.2.1.1 Support the GS rulemaking 

Comment: Protection of U.S. Drinking Water (USDW) sources is paramount and a central 

requirement of the Safe Drinking Water Act and ConocoPhillips wholeheartedly 

supports high standards for protection of current and potential future USDWs. We 

believe that maintaining focus on several key principles can ensure rulemaking 

that is protective and flexible to allow site specific considerations while 

maintaining cost-effective operations. We applaud EPA's work to that end. We 

support most concepts, elements and details in the proposed requirements, and 

provide our comments to reinforce and amplify a few issues which we believe flow 

from the following important key principles: 

o All UIC well classes have requirements fully designed to protect USDW's. 

o The oil and gas industry's experience with CO2 injection for enhanced oil 

recovery (EOR) provides a track record of USDW protection that can enhance EPA's 

rulemaking. 

Individual Response: EPA believes that the creation of a new injection well class (VI) under the 

existing UIC Program is necessary to enable the use of GS as a climate change mitigation 

technology in a manner that protects USDWs from endangerment. EPA agrees that the UIC 

Program, under the authority of the SDWA, provides a strong framework for regulating injection 

1
of CO2 for GS and adds that the GS regulation tailors the UIC requirements to address the 

unique issues associated with large-scale GS including large injection volumes, the relative 

buoyancy of CO2, its corrosivity in the presence of water, the potential presence of impurities in 

captured CO2, and its mobility within subsurface geologic formations. 

EPA recognizes that the oil and gas industry has decades of experience injecting CO2 for the 

purpose of ER, and that sites used for ER may be suitable for GS and may be among the first GS 

sites. Some of the research that informs the final GS rule was conducted at ER sites. EPA also 

recognizes that a by-product of ER activities is that a certain percentage of the CO2 is trapped in 

the receiving formation. 

Letter ID: 0192 Comment ID: 23888 Letter Lines: 88 to 91 

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

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. 

Individual 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 longterm 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. 

Letter ID: 0192 Comment ID: 23889 Letter Lines: 93 to 96 

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

Comment: o Performance standards should focus on containment while allowing for 

flexibility as more is learned about CCS. An approach which is overly 

prescriptive reduces learning, risks delaying the use of newer/better 

alternatives in the future, and can add unnecessary costs. 

Individual Response: The Agency believes that the Class VI requirements balance site-specific 

flexibility with USDW protection. Rather than setting performance or technology-based 

standards for GS projects, EPA is adopting a flexible approach, where operators of GS projects 

would develop and implement site-specific plans for delineating the AoR, testing and monitoring 

the site, performing corrective action, and post-injection site care. EPA believes that the plans—

2
which would be reviewed and approved by the Director and periodically updated throughout the 

life of the project—promote an ongoing dialogue between the operator and the Director that will 

encourage use of the most appropriate technologies for a particular project. 

Letter ID: 0192 Comment ID: 23890 Letter Lines: 98 to 101 

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

Comment: o Area/field Permitting- Many CCS sites will be multi-well sites, with the 

possibility, 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. 

Individual 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. 

3
Letter ID: 0192 Comment ID: 23891 Letter Lines: 103 to 180 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 2046 1.5.2.3 Continuing to classify CO2 injection for EOR/EGR as Class II/ 

dividing line between Class II and Class VI (seeking comment) 

Comment: Enhanced recovery of oil or natural gas and geologic sequestration of CO2 

EPA's Proposal would continue to regulate and permit injection of CO2 for 

EOR/EGR (enhanced gas recovery) purposes as Class II injection "as long as any 

production is occurring." EPA has asked for comment on the merits of this 

approach "since owners or operators of some Class II EOR/EGR wells may wish to 

use wells for the purposes of production and GS prior to the field being 

completely depleted." 73 Fed. Reg. at 43502. We support the Multi-Stakeholder 

consensus recommendation that the rules be clarified to provide more certainty 

about the applicability of Class II requirements where GS of C02 occurs in 

connection with EOR/EGR activities. Specifically, the UIC rules should provide a 

"bright line" definition as to the applicable class of wells where C02 

injections for EOR/EGR production and for GS occur in tandem. We strongly 

support the recommendation for the following language to accomplish that 

objective: 

§ 144.6, 144.80 and 146.5, and Classification of injection wells. 

Injection wells are classified as follows: 

*** 

(b) Class II. Wells which inject fluids: 

(1) Which are brought to the surface in connection with conventional oil 

or natural gas production and may be commingled with waste waters from 

gas plants which are an integral part of production operations, unless 

those waters are classified as a hazardous waste at the time of 

injection. 

(2) For enhanced recovery of oil or natural gas; 

(3) For storage of hydrocarbons which are liquid at standard temperature 

and pressure; 

(4) For enhanced recovery of oil or natural gas where geologic 

sequestration is occurring during or in connection with enhanced 

recovery of oil or natural gas provided (i) there is reasonable 

expectation of more than insignificant future production volumes or 

rates as a result of carbon dioxide injection and (ii) operating 

4
pressures are no higher than reasonably necessary to produce such 

volumes or rates; 

* * * 

(f) Class VI. Wells injecting a carbon dioxide stream for geologic 

sequestration except those wells described in subsection (b)(4) of this 

section or otherwise excluded from this Class. 

The Multi-Stakeholder group has agreed that wells in classification (b)(4) 

should remain in Class II and be subject to the current requirements of Class 

II. We have also agreed that the wells used for GS in oil and gas reservoirs 

that do not meet the criteria of (b)(4) should be subject to additional 

requirements. We have tentatively defined such wells as wells used "for geologic 

sequestration in oil and gas formations and where the criteria of paragraph (b) 

(4) are not met" But we have not yet reached consensus on defining what specific 

requirements should apply to these wells. We are committed to working toward 

agreement on those requirements (probably within a Class II context) and 

submitting the results of that effort to EPA by February 28, 2009 for your 

consideration. 

ConocoPhillips further recommends that Class VI be used for wells designed 

"exclusively for geologic sequestration of carbon dioxide." This clarifies and 

broadens Class II to include former producing oil and gas wells, EOR wells, EOR 

with simultaneous storage, and EOR fields transitioning to/from storage, such 

that all oil and gas fields storing CO2 are Class II, whether producing or not. 

This approach removes uncertainty for fields which may have become storage 

fields, but return to production as economic conditions change, or cease 

production for some time as part of enhancing recovery, and possibly other 

scenarios. This approach acknowledges the track record of CO2 injection for EOR 

and the significant knowledge base in oil and gas fields. Thus, Class VI 

requirements would acknowledge the greater uncertainties inherent in often 

deeper saline storage, newer field developments, and possibly less defined 

closure structures. This approach also may safely accelerate CCS projects 

utilizing well known oil and gas formations, public acceptance may be more 

likely and regulatory authorities/ oil and gas agencies are in place to begin 

CCS projects. We support API's recommendation to add a Class II (b)(S), "For 

geologic sequestration in oil and gas formations and where the criteria of 

paragraph (b)(4) are not met". 

Individual Response: EPA did not make the suggested change. The Agency disagrees that wells 

injecting CO2 for the primary purpose of long term storage should be regulated under Class II 

requirements. 

Based on its evaluation of all public comments and input on the proposed rule and NODA and 

Request for Comment EPA has made many revisions to the GS Rule. See the final rule and 

5
preamble for further discussion on EPA's final approach to transitioning from Class II to Class 

VI. 

EPA is developing guidance on transitioning permits from Class II to Class VI. The guidance 

will assist Directors in determining whether an injection project should be transitioned from 

Class II where the primary purpose is oil and gas production to Class VI where the primary 

purpose is long-term storage of large volumes of CO2. The guidance describes the recommended 

methods the Director may use to evaluate changes in risk to USDWs from projects, and how the 

Director may determine whether a project should be regulated within the Class II or Class VI 

UIC program. This guidance will be available on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. For more information, please 

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

Letter ID: 0192 Comment ID: 23892 Letter Lines: 182 to 214 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 4110 2.4.1.1 Injection pressure limitations 

Comment: Injection Pressure Limitations 

We are concerned about three aspects of proposed 146.88(a), governing injection 

pressure limitations. First, it "restricts" fractures in the injection zone 

"except during stimulation" rather than focusing on maintaining the integrity of 

the confining zone, which is the suggested focus for protecting USDWs. Second, 

it misses an opportunity to refer specifically to the full range of potential 

geomechanical failure modes potentially posed by operations at a particular 

site. Third, the type of geomechanical risk that is addressed (initiation or 

propagation of fractures), is dealt with in a potentially arbitrary fashion (the 

90% of fracture pressure limit), which may not be appropriate in all cases. 

The MSDG's recommended language addresses these concerns by focusing on 

maintaining the integrity of the confining zone and including tensile failure 

and shear failure as appropriate to evaluate for potential transmissivity 

concerns. It calls for additional geomechanical studies of tensile failure and 

shear failure only "where appropriate" because there will be locations where 

experience or existing information will provide sufficient evidence to avoid the 

need for additional studies. The need for conducting additional tests and for 

determining which tests would be acceptable is left to the Director's 

discretion. Recommended language: 

The owner or operator must comply with a maximum injection pressure 

limit approved by the Director and specified in the permit. In approving 

a maximum injection pressure limit, the Director shall consider the 

results of well tests and, where appropriate, geomechanical or other 

studies that assess the risks of tensile failure and shear failure. The 

Director shall approve limits that, with a reasonable degree of 

6
certainty, will avoid initiation or propagation of fractures in the 

confining zone or cause otherwise non-transmissive faults transecting 

the confiding zone to become transmissive. In no case may injection 

pressure cause movement of injection or formation fluids in a manner 

prohibited by 40 CFR Part 144.12(a). 

Individual Response: EPA notes that because determination of the injection pressure limit is 

based on the fracture pressure of the injection zone, the limit is site-specific and not arbitrary. 

EPA emphasizes that injection pressure limits are important to protect against fracturing of the 

confining zone, and that the requirement at §146.88(a) that the pressure in the injection zone not 

exceed 90 percent of the fracture pressure provides a margin of safety in the well operation and 

protects USDWs from endangerment. If the Director determines, based on a review of the 

information collected as part of site characterization, that a lower injection pressure limitation is 

appropriate, the Director has the authority to set a lower limit in the operating permit than the 

limit established in the rule. 

EPA notes that during the site characterization process, owners or operators must submit data 

about the geology of the site, as specified at §146.82(a), including data on known or suspected 

faults and fractures and geomechanical information on fractures, stress, ductility, rock strength, 

and in situ fluid pressures within the confining zone. The Director will use these data to 

determine appropriate limits on injection. 

In response to the concern about reopening of faults at lower pressures than 90 percent of 

fracture pressure, EPA believes that the requirement for the owner or operator to submit data on 

known or suspected faults and fractures and information on the seismic history of the site will 

inform the determination of an appropriate pressure limitation in the permit. Any sites with the 

potential for reopening or reactivation of faults or unacceptable seismic risk that could otherwise 

interfere with containment will not be permitted as GS sites. 

EPA is developing guidance on site characterization for GS projects to assist owners or operators 

in meeting the requirements of §146.82 and to assist directors in evaluating permit applications. 

The guidance will describe recommended approaches for characterizing the regional geology and 

hydrogeology of a proposed site and performing the necessary geochemical, geomechanical, and 

geophysical analyses of the injection and confining zone. EPA is also developing guidance for 

primacy agencies that will include recommended approaches for evaluating owner or operatorsubmitted data in setting permit conditions. The guidance will be available on EPA's web site, at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Letter ID: 0192 Comment ID: 23893 Letter Lines: 216 to 229 

Comment Code: 3120 2.1.2 Need to identify additional confining and containment zones 

(seeking comment) 

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

USDW 

Comment: Lowermost USDW: 

7
EPA's proposal restricts injection to formations beneath the lowermost USDW and 

gives 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." 

Individual 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, sitespecific 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. 

Letter ID: 0192 Comment ID: 23894 Letter Lines: 231 to 241 

Comment Code: 3800 2.3 Proposed Injection Well Construction Requirements (40 CFR 

8
146.86) 

Comment: Well Standards: 

Some well standards, as written in the proposed rule, seem to build from Class I 

Hazardous requirements, which is a level of rigor not necessary for protection 

of USDWs in all C02 injection sites. Given oil and gas industry experience with 

Class II wells, the non-hazardous nature of CO2, and benefits of considering 

many types of sites, geological formations, and confining configurations, we 

recommend increased consideration for Class II influence in Class VI well 

standards. Given that all UIC injection well classes are designed to protect 

USDWs, ConocoPhillips supports API recommendations, and believe the following 

are particularly important: 

Individual Response: EPA disagrees that the well standards provided in the GS rule are too 

rigorous for all Class VI wells. Although the requirements are based on the existing regulatory 

framework for deep wells, including Class I wells, EPA believes that GS is sufficiently different 

from other injection operations to warrant the tailored requirements for Class VI wells at 

§146.86. The well construction requirements are necessary to protect USDWs from 

endangerment. 

Furthermore, EPA clarifies that the requirements for Class VI wells are not necessarily more 

stringent than those for Class I hazardous waste injection wells, rather they are different. For 

example, Class I hazardous well owner or operators are subject to requirements that are not 

applicable to Class VI wells, such as no migration petitions. 

Letter ID: 0192 Comment ID: 23895 Letter Lines: 243 to 255 

Comment Code: 4500 2.5 Proposed Mechanical Integrity Testing (MIT) Requirements (40 CFR 

146.89) 

Comment: - The Mechanical Integrity Testing (MIT) requirements: In addition to daily 

monitoring of pressure, API recommends that: 

At least once per year, the owner or operator must confirm the absence 

of significant fluid movement under paragraph (a)(2) of this section 

using a method acceptable to the Director (e.g. including diagnostic 

surveys such as oxygen-activation logging or temperature or noise 

logs). 

Revised text supports a performance-based approach and allows the 

development and use of new technologies as they become available. 

Subsection (3) was deleted because it requires the tubing to be pulled 

at significant cost and risk of uncontrolled releases. 

Individual Response: EPA believes that the MITs described in §146.89(c) of the rule (an 

9
approved tracer log or temperature or noise logs) are effective methods to demonstrate external 

MI, provide an important early warning of potential problems in the injection well system, and 

represent standard techniques that have been used successfully by the drilling industry and for 

the UIC Program for decades. The Agency notes that the regulations do provide flexibility at 

§146.89(e) to allow the Director to approve the use of alternative MIT methods, which can allow 

the use of any new technologies that become available. 

In addition, EPA is using an adaptive approach to regulating 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 appropriate documentation are being collected, and to determine if 

modifications to the requirements are appropriate or necessary. 

EPA agrees that the casing inspection log is not an appropriate test to detect fluid movement 

behind the casing, but clarifies that it can be used to determine the presence or absence of 

corrosion of the long-string casing, and is required if the Director determines that it is necessary 

based on site-specific information. EPA has revised the final GS rule to require that the 

frequency of the casing inspection log must be specified in the approved testing and monitoring 

plan. See §146.89(d). 

Letter ID: 0192 Comment ID: 23896 Letter Lines: 257 to 261 

Comment Code: 4200 2.4.2 Down-hole shut-off valves in GS wells (seeking comment) 

Comment: - Automatic shut-in is appropriate, but we recommend not pursuing the proposed 

requirement for downhole shut off devices. Down hole shut off valves are 

designed for offshore or other site-specific risks and should be added on a 

site-specific basis when warranted. In many cases, surface shut-in is adequate 

and sufficiently protective. 

Individual Response: After evaluating the risks and benefits of down-hole shut-off systems and 

considering additional research, EPA will not require automatic down-hole shut-off devices for 

onshore Class VI wells since it is not necessary in all cases to ensure protection of USDWs from 

endangerment. Instead, the final rule, at §146.88(e)(2), requires that owners or operators of 

onshore Class VI wells install automatic surface shut-off devices. The rule affords Director's 

discretion to mandate automatic down-hole shut-off devices in onshore situations that may 

warrant their use. The rule requires, at §146.88(e)(3), that owners or operators of offshore wells 

within State territorial waters install automatic down-hole shut-off systems. EPA believes that 

these requirements at §146.88(e) ensure that proper precautions are taken to prevent subsurface 

fluid movement and ensure protection of USDWs. 

The GS rule, at §146.88(e)(3), requires the installation of down-hole shut-off devices for Class 

VI wells located in the offshore submerged lands within the jurisdiction of a State UIC program. 

The Agency believes that the unique construction and operational conditions for offshore Class 

VI wells, including isolation from shorelines and the need to construct wells through the water 

column and the subsurface, may delay response time in the event of well difficulties. These 

10
conditions merit requiring automatic down-hole shut-off devices for offshore wells in the 

submerged lands of a State. 

While EPA acknowledges that the likelihood of damage to onshore facilities is lower than that 

for off-shore facilities, down-hole shut-off valves are still commonly used in onshore facilities 

such as acid gas injection wells and high pressure, high-temperature wells. While valve failure is 

a concern, EPA believes that technology has advanced sufficiently to make valve failure a rare 

occurrence and to appropriately handle such failure if it occurs. For example, wireline retrievable 

devices can allow repair or replacement of damaged devices without necessitating pulling the 

tubing. 

EPA believes that requiring the installation of automatic surface shut-off devices for onshore 

wells (and affording Director's discretion to require down-hole devices where necessary) and 

automatic down-hole shut-off devices for offshore wells in submerged lands within the 

jurisdiction of a State ensures that proper precautions are taken to prevent subsurface fluid 

movement and ensure protection of USDWs. 

Letter ID: 0192 Comment ID: 23897 Letter Lines: 263 to 279 

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

CFR 146.90) 

Comment: Monitoring 

ConocoPhillips supports EPA's proposed rules to prepare, maintain, and comply 

with a testing and monitoring plan, including chemical analysis of CO2 streams 

and allowing for fit-for-purpose monitoring. We recommend some changes as 

described in detail in API's submittal. API's recommendations emphasize careful 

site selection and characterization, which create the strongest protection for 

USDWs while still handling well construction and monitoring with the most cost 

effective protective measures. Specific monitoring requirements detailed in 

API's recommendation maintain appropriate rigor to protect USDWs while allowing 

for site specific details. EPA's flexibility around operator developed plans is 

appropriate, and API acknowledges the directors discretion and ability to add 

prescriptive requirements as appropriate for specific sites. The recommendations 

provide balance, since too many prescriptive elements in the requirements 

themselves, would run the risk of becoming too broadly applied and add 

unnecessary cost. Preserving the environmental benefits of CCS relies on 

managing cost-effective protective solutions. 

Individual Response: EPA agrees and believes that flexibility is important in developing and 

implementing a monitoring plan that is appropriately tailored for a specific GS site. The purpose 

of the requirement at §146.90 to develop site-specific testing and monitoring plans is to ensure 

that the monitoring performed at a site is appropriate for site operational conditions and the 

geologic setting. EPA believes that this is the best approach for addressing potential risks at GS 

sites. These flexible provisions in the monitoring requirements for Class VI wells enable the 

11
owner or operator to tailor monitoring programs to the specific needs of each project in 

consultation with the Director. Please also see EPA's response to API's comment. 

Letter ID: 0192 Comment ID: 23898 Letter Lines: 281 to 290 

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

CFR 146.85) 

Comment: Financial Assurance 

This requirement intends to project and cover the cost of closure and postclosure site care plans. There is acknowledgment of three important elements 1) 

flexible methods and instruments, 2) preserving the availability of selfinsurance mechanisms, and 3) release of financial assurance at closure. Exposure 

after closure would be a concern to investors and would not provide mechanisms / 

financial instruments to recognize that risks diminish after monitoring, postinjection site care, and closure. Again, it seems inappropriate that this 

requirement exceeds requirements for Class I hazardous wells. 

Individual Response: EPA agrees that it is appropriate to allow a flexible approach for financial 

responsibility as long as USDWs are being protected. Owners or operators have the flexibility to 

choose from a variety of financial instruments to meet their financial responsibility obligations 

and may use one or multiple financial responsibility instruments for well plugging and PISC 

(§146.85(a)(6)). However EPA will not allow for a separate financial responsibility 

demonstration for well plugging and PISC (i.e., a demonstration submitted prior to well plugging 

and the beginning of the post-injection site care period rather than with the permit application). A 

demonstration of financial responsibility for all phases of the GS project will be required prior to 

the issuance of a Class VI permit (§146.85(a)(5)(i)). 

EPA will retain the use of self-insurance as an instrument for financial responsibility for Class 

VI wells. EPA is developing guidance that describes the types of financial instruments owners or 

operators can use to meet financial responsibility requirements for Class VI wells. The financial 

responsibility guidance will include considerations for Directors regarding how to evaluate the 

appropriateness of a specific financial responsibility instrument for a specific project. This 

guidance is available on EPA's website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

The goal of financial responsibility is to ensure that financial resources are available to prevent 

the endangerment of USDWs from improper plugging, remediation, and management of wells in 

the event that the owner or operator experiences financial difficulties. EPA disagrees that the 

requirements equate GS wells with Class I hazardous waste wells; rather, the financial 

responsibility requirements for Class VI wells are tailored to the unique nature of the long term 

GS of CO2. 

Once an owner or operator has met all regulatory requirements under Part 146 for Class VI wells 

and the Director has approved site closure pursuant to requirements at §146.93, the owner or 

12
operator will generally no longer be subject to enforcement for regulatory noncompliance. 

Furthermore, the financial instrument required under §146.85 will be released if it has not been 

used. However, even if a site closure is approved under §146.93, an owner or operator may be 

held liable for regulatory noncompliance (including violation of 40 CFR 144.12) in certain 

circumstances. For example, an owner or operator may be held liable even after site closure if the 

Director relied on erroneous information provided by the owner or operator when approving site 

closure. 

Additionally, an owner or operator may always be subject to any action the Administrator deems 

necessary to protect the health of persons under §1431 of the SDWA after site closure if there is 

unanticipated migration towards or into a USDW that causes or threatens imminent and 

substantial endangerment to public health. The action may include issuing administrative orders 

or commencing a civil action for appropriate relief. 

The Agency clarifies that Class VI well permits may be transferred to another owner or operator 

pursuant to §144.38, whereby generally all other regulatory responsibilities are transferred to that 

new owner and operator, including all potential liabilities associated with meeting the 

requirements of that permit. 

Furthermore, after site closure an owner or operator may remain liable under tort and other 

remedies, or under other federal statutes including, but not limited to, Clean Air Act, 42 U.S.C. 

§§ 7401-7671; CERCLA, 42 U.S.C. § 9601-9675; and RCRA, 42 U.S.C. § 6901-6992. EPA 

does not have authority to transfer SDWA or other legal liability for Class VI wells to the State 

or federal government or a third-party fund. See the final rule preamble for further discussion of 

EPA's final approach. 

Letter ID: 0192 Comment ID: 23899 Letter Lines: 292 to 293 

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

Comment: RCRA- CO2 should only be considered to be RCRA hazardous if combined with a 

RCRA 

listed hazardous stream. 

Individual Response: EPA received many comments regarding the applicability of the RCRA 

regulations and statute to CO2 streams that are geologically sequestered under the final Class VI 

UIC well requirements. As a result, EPA has decided to initiate a separate proposed rulemaking 

specifically to examine the issue of RCRA applicability to CO2 streams being geologically 

sequestered, including the possible option of a conditional exemption from the RCRA 

requirements for CO2 GS in Class VI wells. EPA will consider these comments as part of its 

development of that proposal. The Agency will consider issues particular to RCRA in the context 

of that separate rulemaking, and recommends that the commenter read that proposed rule when it 

is published. The Agency notes that commenters who wish to submit comments on the RCRA 

proposal will need to do so during the comment period for that rule. Finally, EPA also notes that 

13
the final GS rule, which adds new regulations for Class VI wells under the Safe Drinking Water 

Act (SDWA), is not making any changes to the RCRA regulations. 

Letter ID: 0192 Comment ID: 23900 Letter Lines: 295 to 299 

Comment Code: 1640 1.3.4 CERCLA issues (seeking comment) 

Comment: CERCLA- CO2 injection under UIC permits will meet EPA's requirements and area 

of 

review along with all permitting requirements; which will ensure appropriate 

injection and handling. We are very concerned that by raising this issue, EPA 

opens broad concern and uncertainty which could seriously jeopardize progress on 

CCS. 

Individual Response: CO2 itself is not listed as a hazardous substance under CERCLA; 

however, the CO2 stream may contain a listed hazardous substance (such as mercury) or may 

mobilize substances in the subsurface that could react with ground water to produce listed 

hazardous substances (such as sulfuric acid). Whether such substances may result in CERCLA 

liability from a sequestration facility depends entirely on the composition of the specific CO2 

stream and the environmental media in which it is stored (e.g., soil or ground water). CERCLA 

exempts from liability, under CERCLA section 107, 42 U.S.C. 9607, certain “federally permitted 

releases” (FPR) as defined in CERCLA, 42 U.S.C. 9601(10). Class VI permits will need to be 

carefully structured to ensure that they prevent potential releases from the well which are outside 

the scope of the Class VI permit. 

Furthermore, EPA is promulgating the GS rule under the authority of the SDWA. To the extent 

the commenter is seeking interpretations of CERCLA and its related provisions, such as the 

definition of a federally permitted release, such interpretations are beyond the scope of this 

rulemaking. 

EPA agrees that proper site characterization and operation of a GS project is important for 

protecting USDWs from endangerment. The UIC program Director also has authority under the 

SDWA to address potential compliance issues (e.g., potential releases that may endanger 

USDWs) resulting from injection violations in the unlikely event that a remedial response is 

necessary. Although EPA anticipates that the need for emergency or remedial actions at GS sites 

will be rare, the GS rule requires, at §146.94, that emergency and remedial response plans be 

developed and updated to address such events and that owners or operators demonstrate that 

financial resources are set aside to implement the plans if necessary, per §146.85. 

EPA adds that promoting the use of GS is outside the scope of the GS rule. Rather, the purpose 

of the GS regulation is to ensure that, where deployed, GS is conducted in a manner that protects 

USDWs from endangerment. 

Letter ID: 0192 Comment ID: 23901 Letter Lines: 301 to 309 

14
Comment Code: 5240 2.8.2.2 Post injection timeframe (seeking comment) 

Comment: Closure Standard 

ConocoPhillips believes there are three problems with the closure standard in 

proposed section 146.93(b). First, the presumption that monitoring should 

continue for 50 years is unnecessary and potentially counterproductive. A 

straight performance standard is preferable to this or any other fixed time 

period because it provides a clearer standard and an incentive to maximize the 

understanding of site and project performance and as such is more protective of 

USDWs. Second, the proposal requires demonstration that the CO2 plume has 

Individual Response: The post-injection site care requirements in the final GS rule, §146.93(b), 

incorporate a combination of a 50-year default post-injection site care timeframe, in conjunction 

with a performance standard, for Class VI wells. The GS rule offers owners or operators 

flexibility regarding the duration of the PISC timeframe by: (1) allowing the Director discretion 

to shorten or lengthen the PISC timeframe during the post-injection period based on site-specific 

data, pursuant to requirements at §146.93(b); or (2) affording the Director discretion to allow a 

Class VI well owner or operator to demonstrate, during the permitting process based on 

substantial data, that an alternative PISC timeframe may be appropriate if it ensures nonendangerment of USDWs pursuant to requirements at §146.93(c). 

EPA believes however, that to ensure USDW protection from endangerment, a default timeframe 

for post-injection site care will be necessary in all but a limited number of cases. This default 50 

year post-injection site care timeframe represents a reasonable and protective monitoring period 

based on a review of research studies, industry reports, and existing environmental programs, 

and evaluation of public comments. 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to 

adjust the timeframe for a limited number of GS projects during the permitting process where 

substantial data exists to demonstrate that an alternative timeframe would be protective of 

USDWs, or based on data collected during the PISC period, is appropriate to address the range of 

sites where GS is anticipated to occur, to accommodate site-specific circumstances and various 

geologic conditions, and addresses commenters’ concerns, while ensuring USDW protection. 

Both approaches will utilize site-specific data, and be based on pressure monitoring and USDW 

impacts. EPA expects that the Director will consider the types of information the commenter 

describes in determining whether the plume and pressure front no longer pose a risk of 

endangerment to USDWs and post-injection site care monitoring may be discontinued. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, postinjection site care, and site closure requirements of §146.92 and §146.93. Additionally, the 

guidance will assist Directors in evaluating proposed well plugging plans and post-injection site 

care and site closure plans under §146.92 and §146.93. The guidance describes recommended 

approaches for how an owner or operator could plug injection and monitoring wells; perform 

post-injection monitoring; demonstrate the appropriateness of an alternative post-injection site 

care time frame; demonstrate non endangerment; and perform site closure activities. This 

15
guidance will be available at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA adds that the purpose of the GS rule is not to incentivize the use of GS; rather, the purpose 

of the GS rule is to ensure that, where GS is deployed, it is conducted in a manner that protects 

USDWs from endangerment. 

Letter ID: 0192 Comment ID: 23902 Letter Lines: 309 to 315 

Comment Code: 5220 2.8.2.1 Post-injection monitoring activities 

Comment: USDWs. Second, the proposal requires demonstration that the CO2 plume has 

"stabilized", which is undefined. Cessation of plume movement is not necessarily 

essential, and may not be applicable, to show that a project poses no threat of 

endangerment to USDWs-plumes that are still moving may, nonetheless, be in 

geological settings which ensure that they remain contained. Instead, it is more 

protective to show that the plume is not expected to encounter a leakage 

pathway. Third, the required demonstration that "no additional monitoring is 

Individual Response: EPA acknowledges that many site-specific factors will influence the 

determination of when the CO2 plume and pressure front no longer pose a risk of endangerment 

to USDWs. It is for this reason that EPA believes that Directors, in consultation with operators, 

will be in the best position to determine whether additional post-injection site care is needed. 

EPA expects this decision to be made based on relevant site data and in consultation with all 

potentially impacted parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long 

time periods due to density differences, natural formation flow gradients and diffusion. EPA 

clarifies that under the final rule, a complete cessation of plume movement is not required, only a 

demonstration that the plume and pressure front no longer pose a risk of endangerment to 

USDWs is. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, postinjection site care, and site closure requirements of §146.92 and §146.93. Additionally, the 

guidance will assist Directors in evaluating proposed well plugging plans and post-injection site 

care and site closure plans under §146.92 and §146.93. The guidance describes recommended 

approaches for how an owner or operator could plug injection and monitoring wells; perform 

post-injection monitoring; demonstrate non endangerment; and perform site closure activities. 

The guidance will be available at http://www.epa.gov/safewater/wells_sequestration.html. 

Letter ID: 0192 Comment ID: 23903 Letter Lines: 315 to 318 

Comment Code: 5220 2.8.2.1 Post-injection monitoring activities 

Comment: pathway. Third, the required demonstration that "no additional monitoring is 

16
needed" does not provide guidance regarding how an operator is to show that no 

additional monitoring is needed. The proposal below provides specific guidance 

on what the operator must show. 

Individual Response: As described above, EPA acknowledges that many site-specific factors 

will influence the determination of when the CO2 plume and pressure front no longer pose a risk 

of endangerment to USDWs. It is for this reason that EPA believes that Directors, in consultation 

with operators, will be in the best position to determine whether additional post-injection site 

care is needed. EPA expects this decision to be made based on relevant site data and in 

consultation with all potentially impacted parties. 

EPA agrees that a complete cessation of plume movement may not occur at some sites for long 

time periods due to density differences, natural formation flow gradients and diffusion. EPA 

clarifies that under the final rule, a complete cessation of plume movement is not required, only a 

demonstration that the plume and pressure front no longer pose a risk of endangerment to 

USDWs is. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, postinjection site care, and site closure requirements of §146.92 and §146.93. Additionally, the 

guidance will assist Directors in evaluating proposed well plugging plans and post-injection site 

care and site closure plans under §146.92 and §146.93. The guidance describes recommended 

approaches for how an owner or operator could plug injection and monitoring wells; perform 

post-injection monitoring; demonstrate non endangerment; and perform site closure activities. 

The guidance will be available at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Letter ID: 0192 Comment ID: 23904 Letter Lines: 320 to 344 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 5200 2.8.2 Post injection site care (seeking comment) (40 CFR 146.93) 

Comment: We recommend the standard in the proposed alternative language for section 

146.93(b) below because it sets forth detailed criteria, all of which must be 

satisfied, to demonstrate that the site does not pose an endangerment to USDWs. 

The specific criteria listed in our proposal will serve to provide the Director 

with the requisite information to make the appropriate determination. The 

advantage of this approach is that it establishes clear criteria that an 

operator must demonstrate before obtaining site closure based upon particular 

site characteristics and is, therefore, reasonably applicable to any storage 

site as opposed to a standard based upon a fixed duration. Furthermore, it is 

more stringent than a purely discretionary approach because it establishes 

specific criteria that must be presented before site closure may be granted. We 

believe this language, which is an extension of work done by the World Resources 

Institute and the Ground Water Protection Council, avoids the noted shortcomings 

and provides stronger protection for USDWs. 

17
146.93 (b) The owner or operator shall monitor the site following the 

cessation of injection. 

(1) The owner or operator shall continue to conduct monitoring as 

specified in the Director-approved post-injection site care and site 

closure plan, until closure is authorized pursuant to 146.93(b)(3). 

(2) The owner or operator can request and demonstrate to the 

satisfaction of the Director that the post-injection site care and site 

closure plan should be revised to reduce the frequency of monitoring. 

Individual Response: EPA disagrees with the suggested edits, but believes that the provisions of 

the final GS rule at §146.93(b) address the commenter’s suggestions. Specifically, the owner or 

operator must monitor the site until it can be demonstrated that the CO2 plume and pressure front 

no longer pose a risk of endangerment to USDWs and that monitoring must continue until the 

owner or operator demonstrates, based on monitoring and other site-specific data, that no 

additional monitoring is needed to ensure that the GS project does not pose a risk of 

endangerment to USDWs, as required at §146.93(b)(3). See the final rule and preamble for 

further discussion on EPA's final approach. 

Letter ID: 0192 Comment ID: 23905 Letter Lines: 346 to 364 

Comment Code: 1240 1.1.1.3 Suggested changes/edits to rule language 

Comment Code: 5280 2.8.2.4 USDW non-endangerment demonstrations 

Comment: (3) Prior to authorization for site closure, the owner or operator must 

demonstrate to the Director, based on monitoring, other site-specific 

data, and modeling that is reasonably consistent with site performance, 

that no additional monitoring is needed to assure that the geologic 

sequestration project does not and is not expected to pose an 

endangerment to USDWs. The Director shall approve closure if the owner 

or operator demonstrates, based on the current understanding of the 

site, including monitoring data and/or modeling, all of the following: 

(i) the estimated magnitude and extent of the project footprint (CO2 

plume and the area of elevated pressure) ; (ii) the estimated location 

of the detectable CO2 plume; (iii) that there is no significant leakage 

of either CO2 or displaced formation fluids that is endangering USDWs; 

(iv) that the injected or displaced fluids are not expected to migrate 

in the future in a manner that encounters a potential leakage pathway 

into a USDW; (v) that the injection wells at the site completed into or 

through the injection zone or confining zone are plugged and abandoned 

in accordance with these requirements; and (vi) any remaining project 

monitoring wells at the site are being managed by a person and in a 

manner acceptable to the Director. 

18
Individual Response: EPA disagrees that the rule should specify the criteria for setting the 

monitoring timeframe. Instead, EPA believes that such determinations are site-specific and 

should be described in a project specific post-injection site care and site closure plan. EPA also 

believes that periodic reviews and updates, where necessary, to the plan are important to 

ensuring that the site continues to be managed effectively and to determine whether shortening 

the monitoring timeframe is appropriate. The post-injection site care requirements in the final GS 

rule offer owners or operators flexibility regarding the duration of the PISC timeframe by: (1) 

allowing the Director discretion to shorten or lengthen the PISC timeframe during the postinjection period based on site-specific data, pursuant to requirements at §146.93(b); or (2) 

affording the Director discretion to allow a Class VI well owner or operator to demonstrate, 

during the permitting process based on substantial data, that an alternative PISC timeframe may 

be appropriate if it ensures non-endangerment of USDWs pursuant to requirements at 

§146.93(c). 

EPA believes that a default post-injection site care timeframe of 50 years, with flexibility to 

adjust the timeframe for a limited number of GS projects during the permitting process where 

substantial data exists to demonstrate that an alternative timeframe would be protective of 

USDWs, or based on data collected during the PISC period, is appropriate to address the range of 

sites where GS is anticipated to occur, to accommodate site-specific circumstances and various 

geologic conditions, and addresses commenters’ concerns, while ensuring USDW protection. 

Both approaches will utilize site-specific data, and be based on pressure monitoring and USDW 

impacts. 

EPA is developing guidance to assist owners or operators in evaluating well plugging, postinjection site care, and site closure requirements of §146.92 and §146.93. Additionally, the 

guidance will assist Directors in evaluating proposed well plugging plans and post-injection site 

care and site closure plans under §146.92 and §146.93. The guidance describes recommended 

approaches for how an owner or operator could plug injection and monitoring wells; perform 

post-injection monitoring; demonstrate the appropriateness of an alternative post-injection site 

care time frame; demonstrate non endangerment; and perform site closure activities. The 

guidance will be available at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

Letter ID: 0192 Comment ID: 23906 Letter Lines: 366 to 389 

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

Comment: Need for adequate implementation resources 

Although not directly addressed in the EPA proposal, the need for adequate 

resources to implement the regulatory program for geologic sequestration at both 

the federal and state levels is a major consideration and one that EPA should be 

addressing both internally and in its discussions with Congress. The annual 

national budget for the UIC program (approximately $11 million) has remained 

static for many years, while UIC agencies have been asked to take on additional 

responsibilities. Furthermore, inflation of salaries and other expenses has 

eroded the buying power of the unchanging UIC budget. If state and regional 

agencies are asked to take on the additional workload of CO2 injection, while 

19
20

ensuring careful scientific review as well as an expeditious processing time, 

they will require additional trained staff and other resources. 

If the nation is serious about reducing atmospheric CO2 through underground 

injection, significant additional resources will need to be made available to 

hire new permitting staff and field inspectors. Those new staff, along with the 

existing cadre of UIC staff and managers, must be trained in subjects that will 

enable them to make prudent permitting, management, and oversight decisions. As 

momentum grows to begin sequestering CO2 underground, EPA and states will need 

to develop additional regulatory requirements and prepare to review applications 

and make permitting decisions. Failure to provide sufficient resources will 

likely create permitting backlogs, resulting in a bottleneck in the overall 

geologic sequestration effort. 

Individual Response: EPA acknowledges that there may be technical and administrative 

challenges including resource concerns, and will work closely with the states to assist them in 

resolving funding issues or acquiring the resources, personnel, and training needed to address the 

unique technical challenges associated with GS. 

EPA will also incorporate Class VI wells into the UIC Program's grant allocation process. The 

States/Tribes/Territories must also demonstrate that they have adequate resources to implement 

the program through matching resources against those allocated by the UIC Program's grant 

allocation formula. Currently, primacy programs are required to meet a minimum of 25 percent 

matching requirement.