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.
BEFORE THE UNITED STATES 

ENVIRONMENTAL PROTECTION AGENCY 

________________________________________ 

) 

Federal Requirements Under the ) 

 Underground Injection Control (UIC) Program ) EPA-HQ-OW-2008-0390 

 for Carbon Dioxide (CO2) ) FRL-8951-3 

 Geologic Sequestration (GS) Wells; ) RIN 2040–AE98 

 Notice of Data Availability and ) 

Request for Comment ) 

 ) 

 ) 

74 Fed. Reg. 44802 (August 31, 2009) ) 

 ___________________________________________)

Comments of: 

Clean Air Task Force 

Environmental Defense Fund 

Natural Resources Defense Council

A. Introduction 

The Clean Air Task Force, Environmental Defense Fund and the Natural Resources Defense 

Council thank the United States Environmental Protection Agency (EPA) for the opportunity to 

comment on the Notice of Data Availability under the Underground Injection Control (UIC) 

Program for Carbon Dioxide (CO2) Geologic Sequestration Wells. 

Founded in 1996, the Clean Air Task Force (CATF) is a nonprofit organization dedicated to 

restoring clean air and healthy environments through scientific research, public education, and 

legal advocacy.

Environmental Defense Fund (EDF), founded in 1967, is a non-profit organization that 

represents more than 500,000 members. EDF links science, economics and law to create 

innovative, equitable and cost-effective solutions to society’s most urgent environmental 

problems. 

The Natural Resources Defense Council (NRDC) is a national, nonprofit organization of 

scientists, lawyers and environmental specialists dedicated to protecting public health and the 

environment. Founded in 1970, NRDC has more than 1.2 million members and online activists 

nationwide, served from offices in New York, Washington D.C., San Francisco, Los Angeles, 

Chicago and Beijing. 
Our organizations continue to believe strongly that geologic sequestration of CO2 (GS), correctly 

implemented, must be a component of the U.S. climate mitigation portfolio. For that reason, we 

continue to stress the importance of the current rulemaking and the timely promulgation of a 

sound rule, as we stated in our joint comments of December 2008 and June 26, 2009. We 

reiterate the need for EPA to (1) address the question of atmospheric emissions of CO2 as well as 

protection of underground sources of drinking water related to underground CO2 injection 

without delaying promulgation of the pending rule, (2) create a regulatory framework for 

geologic sequestration, governing not only geologic sequestration in saline reservoirs, but also in 

oil & gas reservoirs, and (3) expeditiously develop airside accounting, monitoring and reporting 

provisions for injected CO2.

1

 We are somewhat encouraged by EPA’s statements in this NODA 

that it is “evaluating the need for a more comprehensive regulatory framework to provide legal 

guidance,” and that it will take comment on and “endeavor to issue a more comprehensive rule in 

the same time frame” as the final rule in this docket.2 Our organizations anticipate the 

opportunity to provide input to the Agency when such a rule is proposed. However, EPA’s good 

intentions do not obviate the need for the Agency to add a clear statement of Clean Air Act 

authority when it finalizes this rule, as we have noted in our earlier comments is necessary. 

B. Definitions in the NODA 

1. Definition of Class VI well as proposed does not “preclude” or prohibit injection into 

basalts, coal seams, salt caverns and shales, and GS in such formations should be 

excluded from Class VI at this time

EPA mistakenly asserts that the definition of a Class VI well “[a]s proposed, ... would ... 

preclude the injection of CO2 into shallow formations such as coal seams and basalts.”3 In fact, 

the definition of a Class VI well as proposed only states that a Class VI well is one “used for 

geologic sequestration of carbon dioxide beneath the lowermost formation containing an 

underground source of drinking water (USDW).”4 As basalts and coal seams can be found in 

areas beneath the lowermost USDW, or in areas where there is no USDW, this definition 

actually does not preclude or prohibit injection into basalts or coal seams, shallow or otherwise. 

A more important point, however, and one raised in both our earlier comments and today’s 

comments, is that an affirmative prohibition on the inclusion of basalts, coal seams, salt caverns 

and shales in Class VI is warranted based on the state of the science at present. EPA should 

adopt regulatory language containing such a prohibition.5

 Such language need not be added to 

the definition of a Class VI well, but it is not sufficient simply to assert in a preamble that the 

current language preclude such injection. Experimentation with GS in basalts, coal seams, salt 

caverns and shales should continue under Class V for the foreseeable future. 

 

1

 For further details, refer to our letter of Jun26, 2009 to Administrator Jackson. 2

 74 Fed. Reg, at 44805; see also Final Rule, Mandatory Reporting of Greenhouse Gases, 

 EPA-HQ-OAR-2008-0508, RIN 2060-A079, as signed, at 480-481 (Sept. 23, 2009). 3

 74 Fed. Reg. 44808. 

4

 73 Fed. Reg. at 43535. 

5

 Also refer to Multi-Stakeholder Group letter of May14. 2009, which supported the exclusion of GS in basalts, coal 

seams, salt caverns, and shales from Class VI. 

2
2. Other “Definitions” in the NODA

EPA has not proposed changes, in the NODA, to any of the regulatory language included in the 

Notice of Proposed Rulemaking. Therefore, we assume that the “definitions” included in the 

NODA are meant for clarity only, and do not indicate any intention by the Agency to change 

those definitions. Unfortunately clarity is not always achieved: we note particularly the new 

definition of “carbon capture and storage”6 which is not found in the proposed regulatory text 

and confusingly includes the word “storage” rather than “sequestration” making it inconsistent 

with the regulatory text as proposed, as well as other definitions set out in the NODA. 

In addition, we refer EPA to our previous joint comments of December 2008 and the MultiStakeholder Group letter of May 14, 2009 for specific recommendations on regulatory language 

changes to the proposed definitions. 

“Carbon dioxide stream means carbon dioxide plus incidental associated 

substances derived from the source of the CO2 and/or the capture process, and any 

substances added to the stream to enable or improve the injection process. This 

subpart does not apply to any carbon dioxide stream that meets the definition of a 

hazardous waste under 40 CFR part 261.” 

“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.” 

“Sequestration project [...] It includes the subsurface three-dimensional extent of 

the carbon dioxide plume, associated pressure front, and displaced formation 

fluids, as well as the surface area above that delineated region.” 

“Geologic sequestration project means an injection well or wells used to emplace 

a carbon dioxide stream into an injection zone for geologic sequestration. 

“Transmissive fault or fracture means a fault or fracture that has sufficient 

permeability and vertical extent to allow fluids to move beyond a confining 

zone.” 

“Area of review means the subsurface three-dimensional extent of the carbon 

dioxide stream plume and the associated pressure front, as well as the overlying 

formations, any USDWs underlying an injection zone along with any intervening 

formations, and the surface area above that delineated region.” 

C. Research, Data Analysis and Findings 

We agree with EPA that the Agency should continue to make available the results of studies and 

data coming out of the Department of Energy (DOE) Regional Carbon Sequestration 

 

6

 74 Fed. Reg. 44803. 

3
Partnerships, and other research efforts, and that this data can inform the Agency’s rulemaking 

effort now, and going forward. The Safe Drinking Water Act as it applies to the proposed Class 

VI expressly mandates the incorporation of any amendments to the federal regulations into state 

programs. This process will allow the results of future study (including this research) to be 

incorporated into state Class VI programs over time.7 Such an adaptive approach to regulating 

means the results of this research can be incorporated in a revised regulatory framework. This 

consideration, combined with the abundant scientific evidence already considered by EPA in the 

development of this proposal, means that EPA need not wait for the completion of the DOE 

program before finalizing this rule. 

We provide below specific thoughts about research results and progress described by the Agency 

in the NODA. 

1. Regional Partnerships Data

EPA notes that the DOE Southwestern Regional Partnership site at Pump Canyon, near 

Archuleta, New Mexico, “will inform a determination on whether CO2 can be effectively and 

safely sequestered in coal seams.”8

 The results of this project are pending and given the 

quantities injected it is unclear to us that this particular project will determine the techniques, if 

any, that might establish commercial-scale coal seam GS as a safe and effective option. We 

reiterate our concern expressed in our original comments, that at this time coal seams and basalt 

formations, wherever located, should not be considered appropriate formations for GS under 

Class VI. 

2. LBNL Study of Ground Water Quality Changes Related to the Mobilization of Trace 

Elements, If CO2 Leakage is Assumed to Occur

 We agree with EPA that it is important to recognize that these studies describe what happens if 

one assumes that CO2 leaks. The studies do not describe or model the risks of actual CO2

leakage, nor should their results be taken as supporting the idea that there is high risk of such 

leakage. The LBNL study described in the NODA investigated trace element geochemical 

changes in “representative” potable aquifers under the assumption of leaked CO2, which does 

not represent the expected result of CO2 injection at large scale. We agree with EPA that the goal 

of the UIC program and these regulations is to ensure that the risk of such leakage into USDWs 

is low. 

The results of the LBNL study to date suggest that UIC Class VI permits must be based on 

submitted information that is sufficient to establish whether the AOR contains a high or low 

hazard trace element leaching environment. Specifically, the LBNL study of the fate and 

transport of trace elements highlights the need for geochemical screening of reservoir rock in 

potential GS sites. In the case of formations characterized by hazardous trace element 

mineralogy where brine leaching could result in pore water that contains trace elements 

exceeding the maximum contaminant levels (MCLs) and Action Levels (ALs), EPA must ensure 

that the rule language results in the issuance of permits that take into account the potentially 

 

7

 42 U.S.C. §300h(b)(1)(B). 8

 74 Fed. Reg. 44806. 

4
higher risks involved. In particular, the rule should ensure that permits issued in this context will 

require both baseline geochemical studies and monitoring of any geochemical changes above and 

below the confining zone. 

3. LBNL Study of Basin-Scale Hydrologic Impacts of CO2 Sequestration

The results of the 2008 LBNL study of basin-scale hydrologic impacts of CO2 sequestration9

highlighted in the NODA,10 demonstrate the potential for interference of far-field pressures in 

large-scale GS deployment. Although we do not interpret the interference and pressure effects 

described in the study as “significant” compared to injection or formation pressures, these results 

underscore the importance of sound basin-scale management practices, and the need for a noninterference principle to be adhered to during the early years of GS activity, until greater 

proficiency in basin-scale management is gained.11

D. CO2 Injection Above the Lowermost Formation Containing a USDW 

and Other Issues 

1. Injection into coal seams and basalts 

As noted above, the currently proposed definition of a Class VI well confines GS to geologic 

formations located below the lowermost USDW.12 While EPA asserts that “as proposed, the 

definition would also preclude injection of CO2 into shallow formations such as coal seams and 

basalts,” in fact that is not the case. First, USDWs do not exist everywhere, and there may be 

shallow coal seams and basalts in areas where there is not USDW. Second, shallow basalts and 

coal seams may be located below the lowermost USDW. We continue to assert that the Agency 

should prohibit Class VI wells in basalts, coal seams, salt caverns and shales regardless of 

injection depth. 

As we noted in our December comments:13 there is no significant prior experience or consensus 

on how to assess and manage risks, what data is needed to characterize sites, how to select sites, 

how to conduct and manage injection operations, how to model the behavior of CO2, and how to 

monitor project performance of CO2 sequestration in basalts, coal seams, salt caverns and shales. 

The trapping mechanisms of CO2 and/or the operational engineering involved in such operations 

is significantly different from those in deep saline formations and hydrocarbon reservoirs. We 

simply do not know at this time whether sequestration (or even injection in some cases) can even 

be done at scale in such formations. 

Due to this fundamentally different nature of GS in these formations, if EPA decides not to 

explicitly prohibit Class VI wells in such formations, it must provide substantial evidence of the 

scientific basis on which it bases its belief that the physical processes, operational engineering, 

 

9

 Not “storage” – LBNL did not assume that the CO2 could or will be released in the future. 10 74 Fed. Reg. 44808. 

11 Also refer to Multi-Stakeholder Group letter of May14. 2009, which supported the inclusion of a non-interference 

principle. 

12 See proposed 40 C.F.R. §§ 144.6(f), 144.80(f) 146.5(f). at 73 Fed. Reg. 43534-43535. 13 Joint Environmental Group Comments at 11 (Dec. 24, 2008). 

5
and risks involved are similar to and/or equally mature as those in saline formations or oil/gas 

reservoirs. We believe that such a demonstration is important both as a policy matter and a legal 

matter. 

We reassert that until there is better understanding of whether and how sequestration can be 

safely accomplished in basalts, coal seams, salt caverns and shales, wells in these formations 

should be treated as experimental and regulated under UIC Class V. 

2. CO2 Sequestration Should be Allowed Above the Lowermost USDW, But Only Where 

the Geology is Sufficiently Protective, and the Permit Contains Adequate Requirements 

EPA seeks comment on the alternative idea of a “waiver” process, wherein the Director might 

grant site-specific exemptions from the general prohibition on injection above the lowermost 

USDW. We support this idea generally. As we described in our comments on the NOPR,14 GS 

reservoirs located above lowermost USDWs may or may not present additional risks than sites 

located below the lowermost USDWs, and establishing safe and effective siting and operations 

should be based on additional considerations. At the same time, we recognize that there are many 

potentially excellent sequestration sites above USDWs, and that in some areas of the country, 

these may be the only sites available. 

For that reason, we continue to assert that if CO2 injection is permitted above the lowermost 

USDW, the regulations allowing such injection must require (in addition to the information EPA 

asserts the Director would consider in evaluating a waiver application):15 

• confirmation that there are laterally continuous, impermeable confining units above and

below the injection zone adequate to prevent fluid movement and pressure buildup 

• identification of other wells in the area; and 

• monitoring for changes in groundwater chemistry above the upper confining zone and

below the lower confining zone. 

EPA should also require, in appropriate circumstances, prior to permit issuance, completion of 

regional hydrogeologic studies that are conducted with sufficient accuracy to simulate regional 

hydrologic flows and demonstrate that USDWs would not be endangered if injected or formation 

fluids were to move beyond either the higher or the lower confining zone. 

Before finalizing regulatory language on a waiver process to allow injection above the 

lowermost USDW, EPA should investigate and address the potential need for protection against 

water wells, or wells of any other type that may bisect pressurized GS reservoirs. 

3. Distinction between Class VI and other wells

We commend EPA for recognizing that in the NODA that “it is necessary to address the specific, 

unique characteristics of Class VI injection (e.g., large injection volumes, viscosity, and 

buoyancy) and the Agency does not have information or data indicating that Class II operations 

 

14 Id. at 12. 15 74 Fed. Reg. at 44811. 

6
7

are entirely analogous to Class VI, large-scale injection, this alternative allows Class VI injection 

depth considerations to be tailored for GS. A number of dominant differences between Class II 

and Class VI operations indicate that these well classes warrant different treatment. These 

differences include: the risk profiles for these operations; the greater total injection volumes (of 

CO2) for Class VI GS; and, differences in formation pressures (potentially higher for GS), 

greater opportunities for mobilization of constituents, and injection rates and operating 

conditions.”16 This is of significance as the Agency considers how to regulate GS in oil/gas 

reservoirs. 

In addition, however, given the relative similarity between GS in saline formations and oil/gas 

reservoirs in comparison to GS in coal seams, basalts, salt caverns and shales, we are puzzled by 

the Agency’s omission in including a similar comparison of risk profiles between saline and 

basalts, coal seams, salt caverns and shales. We therefore reiterate our points above regarding GS 

in such formations. 

E. Conclusion 

Our organizations appreciate the opportunity to provide comments to EPA on this most 

important rulemaking effort. A final rule will represent a significant step forward in combating 

global climate change, and the time is more than ripe for the U.S. to take such steps. When EPA 

issues its final rule, we feel it must be both technically sound and adaptive to reflect learning 

from experience with GS projects in as seamless a manner as is possible. We very much look 

forward to continuing to work with the Agency on this rule, as well as other efforts under the 

Agency’s existing authority to address the significant problem of climate change in the near 

term. 

Respectfully submitted on Oct15, 2009, 

Scott Anderson, Environmental Defense Fund 

44 East Ave, Suite 304, Austin, TX 78701, 512-691-3410, sanderson@edf.org 

Ann Brewster Weeks, Clean Air Task Force 

18 Tremont St, Suite 530, Boston, MA 02108, 617-624-0234, aweeks@catf.us 

George Peridas, Natural Resources Defense Council 

111 Sutter St, 20th Floor, San Francisco, CA 94104, 415-875-6181, gperidas@nrdc.org

 

16 74 Fed.Reg. 44810. 
Letter ID: 0376  

Commenter: Scott Anderson  

Organization: Environmental Defense Fund (EDF)  

Letter ID: 0376 Comment ID: 28164 Letter Lines: 46 to 57  

Comment Code: 6000 6. Other Comments that are Out of Scope for the NODA  

Comment: Our organizations continue to believe strongly that geologic sequestration of  

CO2 (GS), correctly implemented, must be a component of the U.S. climate  

mitigation portfolio. For that reason, we continue to stress the importance of  

the current rulemaking and the timely promulgation of a sound rule, as we stated  

in our joint comments of December 2008 and June 26, 2009. We reiterate the need  

for EPA to (1) address the question of atmospheric emissions of CO2 as well as  

protection of underground sources of drinking water related to underground CO2  

injection without delaying promulgation of the pending rule, (2) create a  

regulatory framework for geologic sequestration, governing not only geologic  

sequestration in saline reservoirs, but also in oil & gas reservoirs, and (3)  

expeditiously develop airside accounting, monitoring and reporting provisions  

for injected CO2 [FOOTNOTE 1]. We are somewhat encouraged by EPA’s statements  

Individual Response: This comment pertains to EPA’s proposed GS rule (73 FR 43492) and is outside the

scope of the Notice of Data Availability. Please see responses to comments on the proposed rule for

EPA’s response to similar comments.

In addition, portions of this comment are outside the scope of the Notice of Data Availability and the UIC

Program’s authority under the GS rulemaking.  

Letter ID: 0376 Comment ID: 28165 Letter Lines: 57 to 72  

Comment Code: 1100 1.1 Comments on the Comprehensive Approach  

Comment: for injected CO2 [FOOTNOTE 1]. We are somewhat encouraged by EPA’s statements  

in this NODA that it is "evaluating the need for a more comprehensive regulatory  

framework to provide legal guidance," and that it will take comment on and  

"endeavor to issue a more comprehensive rule in the same time frame" as the  

final rule in this docket. [FOOTNOTE 2] Our organizations anticipate the  

opportunity to provide input to the Agency when such a rule is proposed.  
However, EPA’s good intentions do not obviate the need for the Agency to add a  

clear statement of Clean Air Act authority when it finalizes this rule, as we  

have noted in our earlier comments is necessary.  

FOOTNOTE 1‐ For further details, refer to our letter of Jun 26, 2009 to  

Administrator Jackson.  

FOOTNOTE 2‐ 74 Fed. Reg, at 44805; see also Final Rule, Mandatory Reporting of  

Greenhouse Gases, EPA‐HQ‐OAR‐2008‐0508, RIN 2060‐A079, as signed, at 480‐481  

(Sept. 23, 2009).  

Individual Response: EPA acknowledges that GS falls within the broader context of CCS and the need for

regulatory clarity to ensure that USDWs are protected from endangerment. In developing the final GS

rule, the Office of Water coordinated with other Agency program offices and across federal agencies

(e.g., with the Department of Energy; United States Geological Survey; Bureau of Ocean Energy

Management, Regulation, and Enforcement, formerly the Minerals Management Service; Bureau of

Land Management). The Agency continues to evaluate areas of potential applicability of other Federal

environmental statutes including, but not limited to: the Clean Air Act; the Resource Conservation and

Recovery Act; the Comprehensive Environmental Response, Compensation, and Liability Act; and the

Marine Protection, Research and Sanctuaries Act to various aspects of GS and CCS. The Agency will

continue to coordinate on GS and CCS related issues to minimize redundancy and maximize efficiencies

for owners or operators. For additional information, please see the discussion entitled "How Does This

Rulemaking Relate to Other Federal Authorities and GS and CCS Activities?" in the preamble to the final

GS rule.  

The Agency further clarifies that comments on the Greenhouse Gas Reporting Rule for CO2 Injection and

Geologic Sequestration (40 CFR 98), issued under the authority of the CAA in a separate rulemaking

action are out of the scope of the GS NODA. For additional information, see the responses to comments

on the proposed GHG rule in the rulemaking docket for that rule.  

Letter ID: 0376 Comment ID: 28166 Letter Lines: 74 to 92  

Comment Code: 3410 3.4.1. Applicability of Waiver Process to Deep Saline and Other Types of

Formations (seeking comment)  

Comment: B. Definitions in the NODA  

1. Definition of Class VI well as proposed does not "preclude" or prohibit  

injection into basalts, coal seams, salt caverns and shales, and GS in such  

formations should be excluded from Class VI at this time  
EPA mistakenly asserts that the definition of a Class VI well }[a]s proposed,  

... would ... preclude the injection of CO2 into shallow formations such as coal  

seams and basalts." [FOOTNOTE 3] In fact, the definition of a Class VI well as  

proposed only states that a Class VI well is one “used for geologic  

sequestration of carbon dioxide beneath the lowermost formation containing an  

underground source of drinking water (USDW). [FOOTNOTE 4] As basalts and coal  

seams can be found in areas beneath the lowermost USDW, or in areas where there  

is no USDW, this definition actually does not preclude or prohibit injection  

into basalts or coal seams, shallow or otherwise.  

FOOTNOTE 3‐ 74 Fed. Reg. 44808.  

FOOTNOTE 4‐ 73 Fed. Reg. at 43535.  

Individual Response: EPA agrees and clarifies that the rule does not preclude injection into coal seams

or basalts. EPA believes that the requirements that allow owners or operators to seek waivers from the

injection depth requirements at §146.95, along with proper siting, well construction, operation,

monitoring, and post‐injection site care pursuant to the GS rule requirements will ensure USDW

protection.  

Letter ID: 0376 Comment ID: 28167 Letter Lines: 94 to 106  

Comment Code: 3410 3.4.1. Applicability of Waiver Process to Deep Saline and Other Types of

Formations (seeking comment)  

Comment: A more important point, however, and one raised in both our earlier comments and  

today’s comments, is that an affirmative prohibition on the inclusion of  

basalts, coal seams, salt caverns and shales in Class VI is warranted based on  

the state of the science at present. EPA should adopt regulatory language  

containing such a prohibition. [FOOTNOTE 5] Such language need not be added to the  

definition of a Class VI well, but it is not sufficient simply to assert in a  

preamble that the current language preclude such injection. Experimentation  

with GS in basalts, coal seams, salt caverns and shales should continue under  

Class V for the foreseeable future.  

FOOTNOTE 5 ‐ Also refer to Multi‐Stakeholder Group letter of May 14. 2009, which  

supported the exclusion of GS in basalts, coal seams, salt caverns, and shales  

from Class VI.  
Individual Response: EPA disagrees that categorically precluding or prohibiting injection into any type of

formation is appropriate. Instead, construction and operation of a Class VI well for injection into

shallower formations can be permitted if an owner or operator can demonstrate, pursuant to the

requirements at §146.95, that injection can be performed in a manner that protects USDWs and if the

owner or operator meets the other protective requirements at §146.82 through §146.94. EPA believes

that the injection depth waiver requirements at §146.95, along with proper siting, well construction,

operation, monitoring, and post‐injection site care pursuant to the GS rule requirements will ensure

USDW protection.

EPA recognizes that some types of formations, such as coal seams and basalts, are typically shallow and

above the lowermost USDW. The Agency expects that injection for GS into these shallow formations can

be issued waivers and permitted as Class VI wells, provided their owners or operators can meet all of the

requirements at §146.95 and demonstrate that such injection can be performed in a manner that

protects USDWs.  

EPA recognizes that it may be appropriate to conduct injection into certain formation types (e.g., in

basalts, coal seams, salt caverns, and shales) on a small scale as experimental projects; such wells could

be permitted as Class V experimental technology wells. To facilitate experimental injection for GS and to

increase global understanding of injection into these formation types, the Agency is preparing an

addendum to the Class V experimental technology guidance on wells that meet the criteria. The decision

about whether a well should be permitted as a Class V experimental technology well or a Class VI well

will be site‐specific and depend on the nature of the project.  

Letter ID: 0376 Comment ID: 28168 Letter Lines: 110 to 149  

Comment Code: 1000 1. General Comments on the Notice of Data Availability  

Comment: EPA has not proposed changes, in the NODA, to any of the regulatory language  

included in the Notice of Proposed Rulemaking. Therefore, we assume that the  

"definitions' included in the NODA are meant for clarity only, and do not  

indicate any intention by the Agency to change those definitions. Unfortunately  

clarity is not always achieved: we note particularly the new definition of  

"carbon capture and storage" [FOOTNOTE 6] which is not found in the proposed  

regulatory text and confusingly includes the word "storage" rather than  

"sequestration" making it inconsistent with the regulatory text as proposed, as  

well as other definitions set out in the NODA.  

FOOTNOTE 6 ‐ 74 Fed. Reg. 44803.  

In addition, we refer EPA to our previous joint comments of December 2008 and  
the Multi‐ Stakeholder Group letter of May 14, 2009 for specific recommendations  

on regulatory language changes to the proposed definitions.  

"Carbon dioxide stream means carbon dioxide plus incidental associated  

substances derived from the source of the CO2 and/or the capture process, and  

any substances added to the stream to enable or improve the injection process.  

This subpart does not apply to any carbon dioxide stream that meets the  

definition of a hazardous waste under 40 CFR part 261."  

"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."  

"Sequestration project [...] It includes the subsurface three‐dimensional extent of  

the carbon dioxide plume, associated pressure front, and displaced formation  

fluids, as well as the surface area above that delineated region."  

"Geologic sequestration project means an injection well or wells used to emplace  

a carbon dioxide stream into an injection zone for geologic sequestration."  

"Transmissive fault or fracture means a fault or fracture that has sufficient  

permeability and vertical extent to allow fluids to move beyond a confining  

zone."  

"Area of review means the subsurface three‐dimensional extent of the carbon  

dioxide stream plume and the associated pressure front, as well as the overlying  

formations, any USDWs underlying an injection zone along with any intervening  

formations, and the surface area above that delineated region."  

Individual Response: EPA did not include a definition for carbon capture and storage in the proposed or

final GS rule, although, the final GS rule includes some revised definitions in response to public

comments. The definitions, including the definition of a GS project, can be found at 40 CFR 146.81(d).

For details on specific definitions, see the responses to comments on the proposed rule in the

rulemaking docket.  

Letter ID: 0376 Comment ID: 28169 Letter Lines: 151 to 170  

Comment Code: 2100 2.1 DOE Regional Carbon Sequestration Partnership Projects  

Comment: C. Research, Data Analysis and Findings  
We agree with EPA that the Agency should continue to make available the results  

of studies and data coming out of the Department of Energy (DOE) Regional Carbon  

Sequestration Partnerships, and other research efforts, and that this data can  

inform the Agency’s rulemaking effort now, and going forward. The Safe Drinking  

Water Act as it applies to the proposed Class VI expressly mandates the  

incorporation of any amendments to the federal regulations into state programs.  

This process will allow the results of future study (including this research) to  

be incorporated into state Class VI programs over time. [FOOTNOTE 7] Such an  

adaptive approach to regulating means the results of this research can be  

incorporated in a revised regulatory framework. This consideration, combined  

with the abundant scientific evidence already considered by EPA in the  

development of this proposal, means that EPA need not wait for the completion of  

the DOE program before finalizing this rule.  

FOOTNOTE 7 ‐ 42 U.S.C. §300h(b)(1)(B).  

We provide below specific thoughts about research results and progress described  

by the Agency in the NODA.  

Individual Response: EPA agrees that the monitoring and publication of results of the RCSP projects in

combination with an adaptive approach to the rule is the best way to ensure protection of USDWs while

keeping up with ongoing research developments. EPA believes that the projects have provided new and

beneficial information. The state of knowledge regarding site characterization, plume monitoring, leak

detection, and plume modeling have all been advanced because of these studies; as such they have

informed the GS rule development.  

EPA is using an adaptive approach to regulating CO2 injection for GS. EPA plans, every six years, to

collect and review data 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.  

Letter ID: 0376 Comment ID: 28170 Letter Lines: 172 to 184  

Comment Code: 2130 2.1.3. SWP (Pump Canyon, NM)  

Comment: 1. Regional Partnerships Data  

EPA notes that the DOE Southwestern Regional Partnership site at Pump Canyon,  

near Archuleta, New Mexico, "will inform a determination on whether CO2 can be  

effectively and safely sequestered in coal seams." [FOOTNOTE 8] The results of  
this project are pending and given the quantities injected it is unclear to us  

that this particular project will determine the techniques, if any, that might  

establish commercial‐scale coal seam GS as a safe and effective option. We  

reiterate our concern expressed in our original comments, that at this time coal  

seams and basalt formations, wherever located, should not be considered  

appropriate formations for GS under Class VI.  

FOOTNOTE 8 ‐ 74 Fed. Reg. 44806.  

Individual Response: EPA acknowledges concerns with ECBM and basalt projects but believes that it

may be possible to safely utilize these types of formations for GS. The RCSP projects have contributed to

the state of knowledge about injection into coal seams and basalts for GS, e.g., to determine under what

conditions such projects can be achieved safely. While the Archuleta project is a small volume

demonstration, other projects will use larger volumes if this project succeeds.  

EPA does not intend to ban ECBM projects. In the final GS rule, GS into unmineable coal seams will be

allowed, provided the owner or operator can demonstrate that GS at the site can be performed without

endangering USDWs. Owners or operators of unmineable coal seam projects will be subject to the same

site characterization requirements (at §146.82) as those required of other projects.  

Letter ID: 0376 Comment ID: 28171 Letter Lines: 186 to 210  

Comment Code: 2210 2.2.1. Groundwater Quality and Mobilization of Trace Elements (seeking

comment)  

Comment: 2. LBNL Study of Ground Water Quality Changes Related to the Mobilization of  

Trace Elements, If CO2 Leakage is Assumed to Occur  

We agree with EPA that it is important to recognize that these studies describe  

what happens if one assumes that CO2 leaks. The studies do not describe or  

model the risks of actual CO2 leakage, nor should their results be taken as  

supporting the idea that there is high risk of such leakage. The LBNL study  

described in the NODA investigated trace element geochemical changes in  

"representative" potable aquifers under the assumption of leaked CO2, which does  

not represent the expected result of CO2 injection at large scale. We agree with  

EPA that the goal of the UIC program and these regulations is to ensure that the  

risk of such leakage into USDWs is low.  

The results of the LBNL study to date suggest that UIC Class VI permits must be  

based on submitted information that is sufficient to establish whether the AOR  
contains a high or low hazard trace element leaching environment. Specifically,  

the LBNL study of the fate and transport of trace elements highlights the need  

for geochemical screening of reservoir rock in potential GS sites. In the case  

of formations characterized by hazardous trace element mineralogy where brine  

leaching could result in pore water that contains trace elements exceeding the  

maximum contaminant levels (MCLs) and Action Levels (ALs), EPA must ensure that  

the rule language results in the issuance of permits that take into account the  

potentially higher risks involved. In particular, the rule should ensure that  

permits issued in this context will require both baseline geochemical studies  

and monitoring of any geochemical changes above and below the confining zone.  

Individual Response: EPA agrees that LBNL’s study should not be taken as supporting the idea that there

is high risk of leakage and contamination of USDWs from GS activities. It is mentioned in the NODA that

the risk of fluids leaking from deep storage is low for properly managed GS projects, but it may not be

completely ruled out. Site specific risk analyses should be undertaken in order to determine the

probability of CO2 (and associated formation fluids) leaking from the storage reservoir.  

EPA agrees that geochemical screening of reservoir rock in potential GS sites, as well as screening of

overlying USDW geochemistry, should be part of GS site characterization. For this reason, all GS project

owner or operators must submit detailed, site‐specific information about a proposed GS site, including

information on the porosity, permeability, mineralogy, and geochemistry of the targeted injection and

confining zones as well as all USDWs within the AoR. Operators must also present information on the

compatibility of the CO2 stream with fluids in the injection zone and minerals in the injection and

confining zones (§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. For additional information on

EPA’s approach to site characterization for GS wells, see the responses to comments on the proposed

rule in the rulemaking docket.  

Letter ID: 0376 Comment ID: 28172 Letter Lines: 212 to 230  

Comment Code: 2220 2.2.2. Basin‐Scale Hydrologic Impacts of CO2 Storage (seeking comment)  

Comment: 3. LBNL Study of Basin‐Scale Hydrologic Impacts of CO2 Sequestration  

The results of the 2008 LBNL study of basin‐scale hydrologic impacts of CO2  

sequestration [FOOTNOTE 9] highlighted in the NODA, [FOOTNOTE 10] demonstrate  

the potential for interference of far‐field pressures in large‐scale GS  

deployment. Although we do not interpret the interference and pressure effects  

described in the study as "significant" compared to injection or formation  

pressures, these results underscore the importance of sound basin‐scale  
management practices, and the need for a non‐ interference principle to be  

adhered to during the early years of GS activity, until greater proficiency in  

basin‐scale management is gained. [FOOTNOTE 11]  

FOOTNOTE 9 ‐ Not "storage" ‐ LBNL did not assume that the CO2 could or will be  

released in the future.  

FOOTNOTE 10 ‐ 74 Fed. Reg. 44808.  

FOOTNOTE 11 ‐ Also refer to Multi‐Stakeholder Group letter of May14. 2009, which  

supported the inclusion of a non‐interference principle.  

Individual Response: The final GS rule focuses on permitting of individual GS wells and therefore does

not include requirements for basin‐scale evaluations. However, EPA agrees that proactive management

of basin scale concerns to maintain pressures within acceptable ranges is important, and encourages

owners or operators and permitting authorities to communicate planned GS activities to maximize

coordination and minimize pressure interference. If a permit applicant (or the permitting authority) is

aware of pending GS projects near a proposed well, the AoR delineation performed pursuant to §146.84

should account for the impacts of multiple owners and operators injecting within a single basin. EPA

anticipates that, where multiple operators are involved, the Director would not approve modeling that

does not account for changes that may result from all injection operations. The proximity of injection

sites to each other and the relative timing of each injection operation might indicate a possible increase

in risk for the containment of the total CO2 and/or the effects of hydraulic perturbations and brine

displacement.  

EPA adds that if any new GS projects are permitted within the AoR of a GS project between AoR

evaluations, the AoR reevaluation would need to address such projects. EPA also expects that the

permitting of the newer GS project would have considered the presence of an project. For additional

information regarding EPA’s requirements for AoR delineation for GS projects, see the responses to

comments on the proposed rule in the rulemaking docket.  

Letter ID: 0376 Comment ID: 28173 Letter Lines: 232 to 273  

Comment Code: 3410 3.4.1. Applicability of Waiver Process to Deep Saline and Other Types of

Formations (seeking comment)  

Comment: D. CO2 Injection Above the Lowermost Formation Containing a USDW and Other Issues  

1. Injection into coal seams and basalts  
As noted above, the currently proposed definition of a Class VI well confines GS  

to geologic formations located below the lowermost USDW. [FOOTNOTE 12] While  

EPA asserts that "as proposed, the definition would also preclude injection of  

CO2 into shallow formations such as coal seams and basalts," in fact that is  

not the case. First, USDWs do not exist everywhere, and there may be shallow  

coal seams and basalts in areas where there is not USDW. Second, shallow basalts  

and coal seams may be located below the lowermost USDW. We continue to assert  

that the Agency should prohibit Class VI wells in basalts, coal seams, salt  

caverns and shales regardless of injection depth.  

FOOTNOTE 12 ‐ See proposed 40 C.F.R. §§ 144.6(f), 144.80(f) 146.5(f). at 73 Fed.  

Reg. 43534‐43535.  

As we noted in our December comments: [FOOTNOTE 13] there is no significant  

prior experience or consensus on how to assess and manage risks, what data is  

needed to characterize sites, how to select sites, how to conduct and manage  

injection operations, how to model the behavior of CO2, and how to monitor  

project performance of CO2 sequestration in basalts, coal seams, salt caverns  

and shales. The trapping mechanisms of CO2 and/or the operational engineering  

involved in such operations is significantly different from those in deep saline  

formations and hydrocarbon reservoirs. We simply do not know at this time  

whether sequestration (or even injection in some cases) can even be done at  

scale in such formations.  

FOOTNOTE 13 ‐ Joint Environmental Group Comments at 11 (Dec. 24, 2008).  

Due to this fundamentally different nature of GS in these formations, if EPA  

decides not to explicitly prohibit Class VI wells in such formations, it must  

provide substantial evidence of the scientific basis on which it bases its  

belief that the physical processes, operational engineering, and risks involved  

are similar to and/or equally mature as those in saline formations or oil/gas  

reservoirs. We believe that such a demonstration is important both as a policy  

matter and a legal matter.  

We reassert that until there is better understanding of whether and how  

sequestration can be safely accomplished in basalts, coal seams, salt caverns  

and shales, wells in these formations should be treated as experimental and  

regulated under UIC Class V.  

Individual Response: As described above, EPA disagrees that categorically prohibiting injection into any

type of formation is appropriate. EPA recognizes that injection into basalts, coal seams, salt caverns, and

shales have been the subject of limited experimental projects in the past. However, EPA believes that
the GS rule provides safeguards to allow, on a site‐specific basis, GS in other formation types, provided

the owner or operator demonstrates to the Director's satisfaction that the formations are suitable for

receiving and confining injected CO2 as specified at §146.83. The siting, well construction, operational,

and other requirements in the GS rule are designed to ensure that injected CO2 remains within the

target formation.  

As described above, small‐scale, experimental injection into shallow basalts, coal seams, salt caverns

and shales; such wells would be permitted as Class V experimental technology wells. See the preamble

to the final rule and the responses to comments on the proposed GS rule for additional information on

EPA's approach to injection into various formation types.  

Letter ID: 0376 Comment ID: 28174 Letter Lines: 275 to 289  

Comment Code: 3210 3.2.1. Comments Generally in Support of the Approach  

Comment: 2. CO2 Sequestration Should be Allowed Above the Lowermost USDW, But Only Where  

the Geology is Sufficiently Protective, and the Permit Contains Adequate  

Requirements  

EPA seeks comment on the alternative idea of a "waiver" process, wherein the  

Director might grant site‐specific exemptions from the general prohibition on  

injection above the lowermost USDW. We support this idea generally. As we  

described in our comments on the NOPR, [FOOTNOTE 14] GS reservoirs located above  

lowermost USDWs may or may not present additional risks than sites located below  

the lowermost USDWs, and establishing safe and effective siting and operations  

should be based on additional considerations. At the same time, we recognize  

that there are many potentially excellent sequestration sites above USDWs, and  

that in some areas of the country, these may be the only sites available.  

FOOTNOTE 14 ‐ Id. at 12.  

Individual Response: EPA acknowledges the commenter's support of the waiver approach and site‐

specific flexibility in regulatory development and permitting as described in the NODA and Request for

Comment. The Agency acknowledges that there are some situations where injection into non‐USDW

formations above the lowermost USDW can be performed in a manner that protects USDWs. The final

GS rule at §146.95 establishes a process by which owners and operators can seek a waiver of the Class

VI injection depth requirements. The Agency believes the waiver approach: 1) responds to concerns

about local and regional geologic storage capacity limitations imposed by the proposed injection depth

requirements; 2) allows for a more site‐specific assessment of injection depth for GS projects; 3)

accommodates injection into different formation types; 4) allows for injection of CO2 for GS into non‐
USDWs above and/or between USDWs when appropriate and where it can be demonstrated that

USDWs will be protected; and 5) responds to concerns about the use of aquifer exemptions for GS.

Finally, EPA's approach to addressing injection depth variability through a waiver process responds to

concerns about future drinking water resource availability and the need to ensure that high quality

water remains available in sufficient quantities to supply drinking water needs.

EPA believes that that injection for the purpose of GS into non‐USDW formations above the lowermost

USDW warrants tailored requirements to address the unique challenges and risks relative to injection

below the lowermost USDW. For example, there is a risk of downward migration of fluids if there is no

lower confining layer or inadequate confinement. In addition, there is potential that wells will be drilled

through the injection zone in the future to reach USDWs. EPA believes that the additional requirements

that apply to owners or operators of Class VI wells granted a waiver of the injection depth requirements

at §146.95 will provide additional considerations for the owner or operator and Director when

permitting such wells to ensure protection of all USDWs.  

Letter ID: 0376 Comment ID: 28175 Letter Lines: 291 to 314  

Comment Code: 3230 3.2.3. Comments that Additional Submissions are Needed (seeking comment)  

Comment: For that reason, we continue to assert that if CO2 injection is permitted above  

the lowermost USDW, the regulations allowing such injection must require (in  

addition to the information EPA asserts the Director would consider in  

evaluating a waiver application): [FOOTNOTE 15]  

‐ confirmation that there are laterally continuous, impermeable confining units  

above and below the injection zone adequate to prevent fluid movement and  

pressure buildup  

‐ identification of other wells in the area; and  

‐ monitoring for changes in groundwater chemistry above the upper confining zone  

and below the lower confining zone.  

FOOTNOTE 15 ‐ 74 Fed. Reg. at 44811.  

EPA should also require, in appropriate circumstances, prior to permit issuance,  

completion of regional hydrogeologic studies that are conducted with sufficient  

accuracy to simulate regional hydrologic flows and demonstrate that USDWs would  

not be endangered if injected or formation fluids were to move beyond either the  

higher or the lower confining zone.  

Before finalizing regulatory language on a waiver process to allow injection  
above the lowermost USDW, EPA should investigate and address the potential need  

for protection against water wells, or wells of any other type that may bisect  

pressurized GS reservoirs.  

Individual Response: EPA agrees that protecting drinking water resources is vital and is the purpose of

the UIC requirements. The waiver approach establishes extensive site‐specific information related to

injecting above or between USDWs that the owner or operator must submit and the Director must

consider, in consultation with PWSS Directors, to ensure that water supplies in the area and all USDWs

are protected. This includes site‐specific geologic and hydrologic data as the commenter suggests,

including a demonstration that the injection zone is bounded by laterally continuous, impermeable

confining units above and below it that are adequate to prevent fluid movement and pressure buildup

outside of the injection zone; and, that the confining units are free of transmissive faults and fractures

per §146.95(a)(2). The owner or operator must also describe how the monitoring and testing and any

additional plans will be tailored to the GS project to ensure protection of USDWs above and below the

injection zone as specified in §146.95(a)(5).  

In making a determination regarding whether to grant a waiver, the Director must also consider the

suitability of the injection zone, including current or planned artificial penetrations into the injection

zone or formations below it as specified in §146.95(b)(ii).

Many of these additional requirements specifically address water resources, as the commenter

suggests. The requirement at §146.95(b) establishes considerations that the UIC Director must assess

when evaluating a waiver application to ensure that USDW protection, site‐specific drinking water

resource issues, and the use and impact of GS technologies are considered and documented.

Considerations associated with water resources include: community needs, demands, and supply from

drinking water resources; planned needs, potential, and/or future use of USDWs and non‐USDWs in the

area; planned or permitted water, hydrocarbon, or mineral resource exploitation potential of the

proposed injection formation and other formations both above and below the injection zone to

determine if there are any plans to drill through the formation to access resources in or beneath the

proposed injection zone/formation; and a proposed plan for securing alternative resources or treating

USDW formation waters in the event of contamination related to the Class VI injection activity.

EPA adds that owners or operators granted injection depth waivers are subject to additional

requirements at §146.95(f) ensuring protection of USDWs above and below an injection zone.  

Letter ID: 0376 Comment ID: 28176 Letter Lines: 316 to 332  

Comment Code: 3130 3.1.3. Addressing the Differences Between Class II and Class VI Wells  

Comment: 3. Distinction between Class VI and other wells  
We commend EPA for recognizing that in the NODA that "it is necessary to address  

the specific, unique characteristics of Class VI injection (e.g., large  

injection volumes, viscosity, and buoyancy) and the Agency does not have  

information or data indicating that Class II operations are entirely analogous  

to Class VI, large‐scale injection, this alternative allows Class VI injection  

depth considerations to be tailored for GS. A number of dominant differences  

between Class II and Class VI operations indicate that these well classes  

warrant different treatment. These differences include: the risk profiles for  

these operations; the greater total injection volumes (of CO2) for Class VI GS;  

and, differences in formation pressures (potentially higher for GS), greater  

opportunities for mobilization of constituents, and injection rates and  

operating conditions." [FOOTNOTE 16] This is of significance as the Agency  

considers how to regulate GS in oil/gas reservoirs.  

FOOTNOTE 16 ‐ 74 Fed.Reg. 44810  

Individual Response: EPA agrees that ER is different than GS, and clarifies that the final GS rule

requirements are designed to address these unique attributes of GS.  

Letter ID: 0376 Comment ID: 28177 Letter Lines: 334 to 339  

Comment Code: 3120 3.1.2. Allowing GS in All Formation Types  

Comment: In addition, however, given the relative similarity between GS in saline  

formations and oil/gas reservoirs in comparison to GS in coal seams, basalts,  

salt caverns and shales, we are puzzled by the Agency’s omission in including a  

similar comparison of risk profiles between saline and basalts, coal seams, salt  

caverns and shales. We therefore reiterate our points above regarding GS in such  

formations.  

Individual Response: EPA recognizes that some types of formations, such as coal seams and basalts, are

typically shallow and above the lowermost USDW. The Agency expects that injection for GS into these

shallow formations can be issued waivers and permitted as Class VI wells, provided their owners or

operators can meet all of the requirements at §146.95 and demonstrate that such injection can be

performed in a manner that protects USDWs.  

EPA believes that if site characterization is properly conducted, confinement is demonstrated, and wells

are properly constructed, operated, monitored, and closed then formations such as coal seams and

basalts can be safely used for GS. The final GS rule does not categorically preclude or prohibit injection
into any type of formation. EPA believes that the requirements that allow owners or operators to seek

waivers from the injection depth requirements at §146.95, along with proper siting, well construction,

operation, monitoring, and post‐injection site care pursuant to the GS rule requirements will ensure

USDW protection.  

Letter ID: 0376 Comment ID: 28178 Letter Lines: 341 to 351  

Comment Code: 1000 1. General Comments on the Notice of Data Availability  

Comment: E. Conclusion  

Our organizations appreciate the opportunity to provide comments to EPA on this  

most important rulemaking effort. A final rule will represent a significant step  

forward in combating global climate change, and the time is more than ripe for  

the U.S. to take such steps. When EPA issues its final rule, we feel it must be  

both technically sound and adaptive to reflect learning from experience with GS  

projects in as seamless a manner as is possible. We very much look forward to  

continuing to work with the Agency on this rule, as well as other efforts under  

the Agency’s existing authority to address the significant problem of climate  

change in the near term.  

Individual Response: EPA believes that the final GS rule is technically sound and that the adaptive

approach to the GS rulemaking will allow for the incorporation of new research, data, and information

about GS as it becomes available in the future. For more information on the adaptive approach, see the

responses to comments on the proposed rule in the rulemaking docket.