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 

____________________________________________ 

) 

Notice of Proposed Rulemaking ) 

 Federal Requirements Under the ) 

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

 for Carbon Dioxide (CO2) ) FRL-8695-3 

Geologic Sequestration (GS) Wells ) 

 ) 

 ) 

73 Fed. Reg. 43492 (July 25, 2008) ) 

 ___________________________________________)

Comments of: 

Clean Air Task Force – 

 – Clean Water Action – 

– Environmental Defense Fund – 

– Natural Resources Defense Council – 

– Western Resource Advocates

A. Introduction 

The Clean Air Task Force, Clean Water Action, Environmental Defense Fund, Natural 

Resources Defense Council, and Western Resource Advocates (Environmental NGO Group) 

thank EPA for the opportunity to comment on the Proposed Rule on carbon dioxide sequestration 

wells under the Underground Injection Control (UIC) Program. 

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.

Founded in 1972, Clean Water Action (CWA) has 1.2 million members and offices in 20 states. 

Clean Water Action works to improve public health and environmental protection through 

grassroots organizing, policy research and 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. 
 2

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. 

Western Resource Advocates (WRA) is a regional non-profit organization using law, economics 

and policy analysis to protect the land, air and water of the Interior Western United States. 

The planet’s climate is changing fast. Greenhouse gas emissions from the use of fossil fuels, 

mainly carbon dioxide (CO2), are having a profound effect on our climate, presenting us with 

one of the most significant environmental and social challenges of the century. In its most recent 

Assessment Report last year, the Intergovernmental Panel on Climate Change, an independent 

scientific body, issued the loudest warning to date, calling the warming in the climate system 

“unequivocal” and calling for serious emission reductions if we are to avoid truly dangerous 

greenhouse gas concentrations. Failure to pursue significant reductions in greenhouse gas 

emissions very soon will make it much harder in the future both to stabilize atmospheric 

pollution concentrations and to avoid the worst impacts of climate change. Climate change is 

expected to and, indeed, already is having a profound effect on sources of drinking water. The 

American West, for example, is already becoming noticeable hotter and drier, as a recent 

compilation of studies by the Rocky Mountain Climate Organization (RMCO) and NRDC 

summarizes.1

A growing body of scientific research indicates that we face extreme dangers to human health, 

economic well-being, and the ecosystems on which we depend if global average temperatures are 

allowed to increase by more than 2 degrees Fahrenheit from today’s levels. We have good 

prospects of staying below this temperature increase if atmospheric concentrations of CO2 and 

other global warming gases are kept from exceeding 350 to 450 parts per million (ppm) CO2-

equivalent. Achieving this goal will require rapid reductions in existing emissions, including 

action to cut emissions by approximately 80% by mid-century. This goal is ambitious, but 

achievable. It can be done through an annual rate of emissions reductions that ramps up to about 

a 4% reduction per year. Fortunately, a wide variety of tools is available today to achieve those 

reductions. 

While it is not a “silver bullet”, one important tool is the geologic sequestration (GS) of CO2 at 

properly selected and properly regulated sites. Our Environmental NGO Group does not 

necessarily have a common view concerning the magnitude of the long-term role of GS in 

combating climate change, but we are united in recognizing that a transition away from fossil 

fuels will take time and that GS is likely to be an important part of the near- to medium-term 

solution. Fortunately, capturing CO2 and permanently sequestering it in certain types of wellselected and well-managed geologic formations is a technology that is ready to begin 

deployment today. While GS projects can be permitted today under the Safe Drinking Water 

Act’s (SDWA) UIC program (in fact a number of projects have already been permitted under 

existing well classes), the rules that currently apply to such projects were not designed with 

 

1

 “Hotter and Drier: The West’s Changes Climate”. Rocky Mountain Climate Organization (RMCO) and the Natural 

Resources Defense Council. Available at: http://www.nrdc.org/globalWarming/west/west.pdf 
 3

geologic sequestration in mind. Thus, the importance of this rulemaking is not that it is needed in 

order for GS projects to receive permits; rather, the rulemaking is important because it can assure 

that GS projects are regulated under rules that are specifically designed to require GS projects to 

be done safely and effectively without endangering underground sources of drinking water 

(USDWs) or, as discussed below, resulting in a risk of release to the atmosphere. For that reason, 

it is essential that EPA promulgate final rules for GS in a timely manner that are sufficient to 

protect USDWs. 

It is also essential that the U.S. Environmental Protection Agency (EPA) take supplemental 

action, based on other (non-SDWA) authority, to provide additional assurance that injected CO2

will not be released into the atmosphere in a way that adversely impacts the climate or otherwise 

endangers public health and welfare. Generally, the steps needed to protect USDWs are also 

needed in order to prevent emissions to the atmosphere. Supplemental steps citing additional 

authority should also guarantee that CO2 injected into geologic formations stays out of the 

atmosphere. This should be done according to a permanence (performance) standard, which will 

certify CO2 as ‘geologically sequestered’ for that purpose, in addition to protecting USDWs. 

These are needed, as none of the existing or proposed injection classes are adequate for the task 

of certifying CO2 as permanently sequestered for the purposes of preventing atmospheric 

releases. In order to be fully protective of the environment, Congress will also need to pass 

comprehensive cap and trade legislation to control the emission of greenhouse gases from all 

anthropogenic sources. But the need for such legislation is not a basis for deferring the adoption 

of EPA rules to protect USDWs or to assure that injected CO2 does not result in harmful releases 

to the atmosphere. 

The Supreme Court recognized in Massachusetts v. EPA2 that EPA has authority and, indeed an 

obligation, under the Clean Air Act to regulate emissions of greenhouse gases, including CO2, 

that “cause or contribute to air pollution that may reasonably be anticipated to endanger public 

health or welfare.”3

 Similarly, the D.C. Circuit’s remand of the power plant new source 

performance standards (“NSPS”) places EPA in the position to regulate CO2 emissions from new 

and also existing sources within that industrial sector.4 The Environmental Appeals Board EAB 

also recently has rejected the agency’s arguments that it is not authorized to issue best available 

control technology (BACT) emissions limits for CO2 in the context of a new source air permit 

decision for a large new coal-fired power plant, under the Clean Air Act’s Prevention of 

Significant Deterioration (PSD) new source review authority.5

 

In comments on the Agency’s recent advanced notice of proposed rulemaking on using the Clean 

Air Act to combat climate change, a coalition of environmental NGOs, including some members 

 

2

 127 S.Ct. 1438 (2007). 

3 Id. at 1460-61. 4

 Order, NY, et al. v. EPA, D.C. Cir. No. 06-1322 (Sept. 24, 2007). Once NSPS are set for an industry under section 

111(b), 42 U.S.C. §7411(b), the Act requires EPA to set standards for states to regulate emissions from existing 

sources in that industry. 42 U.S.C. § 7411(d). 

5 In re: Deseret Power Electric Coop., PSD App. No 07-03, Slip Op. (Nov. 13, 2008). The memorandum issued 

December 18, 2008 by Administrator Johnson entitled “EPA’ Interpretation of Regulations that determine Pollutants 

Covered by Federal Prevention of Significant Deterioration (PSD) Permit Program” (Johnson PSD memo) is 

procedurally deficient, and, in any event, states explicitly on its face that it is not intended to supersede the EAB’s 

decision in the Deseret case. Johnson memo at 2. Nor, indeed, can it lawfully do so. 
 4

of our Environmental NGO Group, pointed out that for the U.S. to achieve its necessary climate 

goals, controlling CO2 emissions from new and existing sources of CO2 is required. That 

necessitates reductions from all sectors, including radical shifts to zero-emitting technologies and 

corrective action on existing sources. These reductions will require targeted measures and 

policies, which include air regulations that would set CO2 emissions standards implicating the 

capture and sequestration of CO2. Setting an NSPS or a BACT standard based on CO2 capture 

technology necessarily creates a need for complementary requirements to assure that the 

captured CO2 is effectively isolated from the atmosphere. At this time, such an outcome requires 

injecting CO2 underground for permanent sequestration in either hydrocarbon reservoirs or deep 

saline formations. Such permanent sequestration clearly meets the definition of underground 

injection, regulated by the UIC program of the Safe Drinking Water Act (“SDWA”).6

We therefore are pleased to submit these comments on EPA’s proposed rules concerning 

“Federal Requirements Under the Underground Injection Control (UIC) Program for Carbon 

Dioxide (CO2) Geologic Sequestration (GS) Wells, 73 Fed. Reg.43492 (July 28, 2008). 

B. The Safe Drinking Water Act Authorizes EPA to Create a Preventive, 

Forward Looking, and Adaptive Program Specific to CO2 GS 

Permitting 

Under the SDWA, EPA’s authority to protect USDWs is clearly defined, broadly scoped, and 

forward looking.7 Section 1421 requires the Administrator to publish rules for state implemented 

underground injection programs that “prevent underground injection which endangers drinking 

water sources” as that phrase is further defined by the statute.8 Such programs, at a minimum, 

must “prohibit any underground injection ... which is not authorized by a permit,”9

 and such 

permit programs must require a showing to the satisfaction of the state that the underground 

injection will not endanger drinking water sources....”10 Underground injection “endangers 

drinking water sources if such injection may result in the presence in underground water which 

 

6

 42 U.S.C. §300h, et seq. Geologic sequestration of CO2 clearly meets the definition of underground injection found 

at 42 U.S.C. §300h(d)(1), “the subsurface emplacement of fluids by well injection.” Carbon dioxide, whether 

injected in a supercritical state, or as a gas, meets the definition of a fluid included in the existing regulations under 

the SDWA: those rules state that a “fluid” is “any material or substance which flows or moves whether in a 

semisolid, liquid, sludge, gas or other form or state.” 40 CFR § 144.3.

7 While our Environmental NGO Group agrees that EPA’s primary authority for the promulgation of this rule is 

found in the Safe Drinking Water Act, we also point out above that the Clean Air Act authorizes controls on CO2

emissions that necessarily implicate and necessitate this UIC approach, and so also can be said to provide authority 

for Class VI rules. EPA must exercise its Clean Air Act authority to regulate CO2 for the purposes of preventing its 

release to the atmosphere. Additionally, and more generally, EPA could also promulgate verification and accounting 

protocols for CO2 GS, as needed, under those Clean Air Act rules. Such Clean Air Act rules may or may not prove 

adequate for purposes of any future legislatively created trading system. Clearly, however, the UIC rules should not 

be regarded as sufficient to authorize or certify carbon credits as part of such a system, as they do not provide 

sufficient proof that CO2 will be permanently sequestered from the atmosphere, nor do they include additional 

details necessary for verifying and quantifying any atmospheric releases. 

8

 42 U.S.C. §§ 300h(a)(1), (b)(1). 

9 Id. § 300h(b)(1)(A). 10 Id. § 300h(b)(1)(B). 
 5

supplies or can reasonably be expected to supply any public water system of any contaminant, 

and if the presence of such contaminant may result in such system’s not complying with any 

national primary drinking water regulation or may otherwise adversely affect the health of 

persons.”11 And “contaminant” is defined as “any physical, chemical, biological, or radiological 

substance or matter in water.”12 Underground injection furthermore is prohibited without a 

permit, and to receive a permit the applicant must demonstrate that endangerment “will not” 

occur.13 This preventive, broadly scoped language demonstrates that Congress intended that all 

underground injection be regulated under the UIC program.14

The statute provides additional direction to EPA in developing its rules – the rules must “permit 

or provide for consideration of varying geologic, hydrological, or historical conditions, in 

different States and in different areas within a State,”15 and they are not to “interfere with or 

impede” underground injections for the purposes of “the secondary or tertiary recovery of oil or 

natural gas, unless such requirements are essential to assure that underground sources of drinking 

water will not be endangered by such injection.”16 While EPA is not free to exempt a particular 

class of injection entirely from rulemaking, the Agency is authorized to tailor the UIC rules to 

the specific geologic conditions and also to particular injection activities. The statute clearly 

authorizes EPA to create a new class or classes of UIC wells for the purpose of CO2

sequestration. 

This precautionary, forward looking statutory purpose and structure authorizes EPA also to take 

an adaptive approach, both in rulemaking and in defining permit terms, specifically to direct 

states to be adaptive in monitoring, tracking, and updating permits, in order to reflect lessons 

learned from experience and from monitoring reports. The statute also authorizes EPA to take an 

adaptive approach to the rules themselves. Section 1421(a)(1) states that “any regulation 

[governing underground injection activities] may be amended from time to time.”17 Whereas, as 

is the case with EPA’s proposed Class VI rules, regulations are established to govern a system on 

a scale of deployment that has not yet been demonstrated18, the preventive and precautionary 

nature of the UIC statute demands a periodic review, assessment, and update of the rule. EPA 

should, in its final rule, declare its intention to undertake such a process. Moreover, our 

Environmental NGO Group recommends that EPA commit itself to issuing a Notice of Proposed 

Rulemaking by no later than an identified date, perhaps in 2020, which would formally initiate 

this process. 

 

11 Id. § 300h(d)(2). 12 42 U.S.C. § 300f(6). 

13 42 U.S.C. § 300h(b)(1)(A), (B). 

14 See also NRDC v. EPA, 824 F.2d 1258, 1271 (1st Cir. 1987), holding that Congress intended the phrase 

‘underground injection which endangers drinking water sources" should have the broadest applicability, and citing 

and quoting H.R. Rep. No. 1185, 93d Cong., 2d Sess., reprinted in 1974 U.S. Code Cong. & Admin. News at 6484. 15 42 U.S.C. § 300h(b)(3)(A). 

16 Id. § 300h(b)(2)(B). 

17 42 U.S.C. § 300h(a)(1). 

18 Although the practice of injection/GS has been demonstrated at the individual project scale. 
 6

C. The Proposed Rule Has Many Positive Features 

Before offering comments on the proposal itself, we want to praise and lend our support to EPA 

for incorporating, or in some cases intending to incorporate, a number of features of the rule that 

we regard not solely as desirable, but essential. These include: 

• specific requirements for a comprehensive characterization before deeming a 

sequestration site as appropriate for injection; 

• monitoring requirements for tracking the behavior and location of CO2 in the subsurface, 

validating its confinement, or detecting unwanted behavior early to allow for corrective 

action; 

• the need to compile a monitoring plan, a site care and closure plan and a remedial 

response plan prior to obtaining a permit; 

• the requirement to update and report on these plans, including the area of review 

adjustment process, as monitoring and operational data become available; 

• a requirement for a continuous feedback loop between monitoring and modeling, 

whereby one updates the other in order to optimize operations and refine simulations; and 

• a criterion for site closure that is not based on the mere passage of a set number of years, 

but on the finding that drinking water is not endangered and that the project meets the 

necessary performance standards (we note, however, that articulation of the performance 

standards that need to be met in order to make such a finding is one of the areas where 

the rule needs work). 

These features are captured to differing extents by the proposed rule’s language, and our 

suggested changes below serve to reinforce these features. Some of these features appropriately 

go beyond what is currently required under existing well classes in the UIC program. We regard 

them as necessary for the effective regulation of GS in the Class VI context, and strongly support 

them. We would therefore label our proposed changes as technical modifications, and not radical 

changes in the rule. Even though these strengthening changes are needed, we urge EPA to 

maintain the basic structure of the rule as proposed and thank the drafting working group for 

producing the proposed rule in a short timeframe. 

D. General Comments 

Timing of promulgation

The proposed rule is based on a risk management approach and is written in a way that should 

avoid unintended consequences to USDWs. It is important to bear in mind that CO2 injection 

projects can already be permitted today. While this may be adequate to protect USDWs in certain 

cases, it is in the interests of the public (and the regulated industry) to have a new injection class, 

designed from the outset with the particular characteristics of GS in mind, as soon as possible. 

This is necessary in order provide certainty and adequately safeguard public health and the 

environment. If the final rule incorporates changes concerning the adaptive nature of the rule and 

permits, as our Environmental NGO Group suggests, the Agency, and its state counterparts, will 

be able to deal with such unintended consequences to USDWs through the rule’s performance-
 7

based provisions, review and a possible reissuance of permits if necessary, and by revising the 

rule text if appropriate. 

We consider the Phase III Deployment Phase of the Department of Energy’s (DOE) Regional 

Partnership Program to be very worthwhile, but we do not consider the completion of this 

program to be a prerequisite for either commercial implementation of CCS or for the 

promulgation of a sound and protective rule. The DOE’s program has limited funds available 

through appropriations, and its demonstration projects will be of limited scale and duration. In 

addition, it focuses as much or more on the optimum way to apply existing technologies as it 

does on fundamental research or even demonstrations that particular technologies “work.” Our 

scientific and practical understanding and experience in GS itself, as well as in related 

underground injection activities, is sufficient to construct and operate the first large-scale, 

commercial plants in the U.S., provided they are regulated adequately. In that respect, we do not 

consider the proposed rule premature, but a very timely and necessary development. 

The rule itself, rather than individual permits, should assure that Class VI permits do not 

allow responsible parties to avoid CERCLA liability on grounds that a release constitutes a 

“federally permitted release”

EPA notes in the preamble to the proposed rule (73 Fed. Reg. 43504) that CERCLA exempts 

from liability certain “federally permitted releases, including releases in compliance with a UIC 

permit under the Safe Drinking Water Act.” EPA further notes that “Class VI requirements and 

permits will need to be carefully structured to ensure that they do not ‘authorize’ inappropriate 

hazardous releases.” Our Environmental NGO Group strongly urges EPA to go further and 

effectively prohibit Class VI permit conditions that would make the “federally permitted release” 

defense available should injected fluids or displaced formation fluids enter or endanger USDWs. 

We suggest that such a prohibition be added to Subpart E – Permit Conditions, or to any other 

section of the rule that EPA finds appropriate. 

The rule should incorporate a “non-interference principle” to keep one sequestration project 

from interfering with the effectiveness of another

As EPA notes in the preamble (page 43506), “it is ... possible that multiple owners or operators 

will be injecting CO2 into formations that are hydraulically connected and thus the elevated 

pressure zones may intersect or interfere with each other.” Our Environmental NGO Group 

agrees that this is a genuine possibility at this stage in GS implementation. Until comprehensive 

approaches to basin-scale management are developed, we urge the adoption of the following 

addition to §146.94: 

“(e) If an owner or operator obtains evidence that a pressure front associated with 

one geologic sequestration project intersects or threatens to intersect a pressure 

front associated with any other project, the owner or operator obtaining such 

evidence must notify the Director and the other owner or operator. If the Director 

determines that the pressure front associated with one project interferes or 
 8

threatens to interfere with the ability of a project that began operations at an 

earlier date to sequester the earlier project’s total anticipated volume of the carbon 

dioxide stream as determined under §146.83(a), the Director may require the 

owner or operator of the project that began operations at a later date to modify 

operations as necessary to avoid such interference. “ 

Process for permit review by experts

We recommend that EPA consider establishing a process to collect input from experts to help 

inform EPA and states on evolving GS technology and appropriate policy and regulatory 

responses. Participants in the process should be independent, non-partisan, unbiased experts in 

the field, We recommend that the participants not be convened under the Federal Advisory 

Committee Act. Their opinions would be non-binding. Obtaining such input would help 

regulators improve their permitting decisions and would be complementary to the objectives of 

increased funding and resources for the UIC Program, outlined below. 

Funding and resources for the UIC Program

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 ensuring careful scientific review as well as an 

efficient processing time, they will require additional trained staff and other resources. 

Significant additional resources will need to be made available to hire new permitting staff and 

field inspectors. Those new staff, along with existing UIC staff, must be trained in subjects that 

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

states will need to be adequately prepared to review applications and make permitting decisions. 

Failure to provide sufficient resources will likely create permitting backlogs or result in suboptimal permits being issued. 

The Ground Water Protection Council (GWPC) estimated in 2004 that an annual funding 

increase to $56 million would be needed just to meet the needs of the existing UIC program at 

the state level even without the addition of GS project permitting.19 GWPC has further estimated 

that EPA will need to provide funding at a level of $100 million annually to meet the needs for 

the full UIC program, including the regulation of geologic sequestration.

 

19 GWPC, Class V Resource Needs Survey, Summary (September 2004). 

 
 9

Public Water Systems should receive notice of permit applications and have the opportunity to 

participate in the permitting process

EPA should adopt the existing requirements for public participation at 40 CFR Part 25 and 40 

CFR Part 124 as suggested in the proposal. UIC Program Directors should also incorporate 

modern communication technologies (cable television, various internet tools) to increase the 

likelihood of effective public understanding and involvement. Engaging the public as soon as 

candidate locations are identified will also increase the effectiveness of the effort. Given the 

focus of the rule on preventing harm to USDWs, UIC Program Directors should work with 

primacy agencies and departments with responsibility for implementing other aspects of SDWA 

to identify and notify Public Water Systems (PWSs) with a potential interest in the project. 

PWSs are an important stakeholder in the projects and should be the focus of targeted outreach at 

every stage of the permitting process. PWS representatives should be invited to serve on any 

Advisory Groups or other bodies set up during the lifetime of the project. We suggest that in 

Guidance to accompany this rulemaking, EPA urge owners and operators to establish on-going 

relationships with potentially impacted PWSs. 

Pressure limits

We believe that the pressure management provisions in §146.88(a) require modification. The 

members of our Environmental NGO Group have not reached agreement on the exact language 

for the suggested changes and are either submitting individual comments on this issue or are 

submitting comments jointly with other groups. We do agree, however, that injection pressure 

limits must be established after adequately considering the risks of both tensile failure and shear 

failure in the confining zone. We also agree that limits must be designed to avoid causing 

otherwise non-transmissive faults to become transmissive, in addition to addressing the more 

traditional concern of avoiding the initiation or propagation of fractures. 

Site closure standards and framework for long-term stewardship

Our Environmental NGO Group did not come to a common set of recommendations on site 

closure and are either submitting individual comments on this issue or are submitting comments 

jointly with other groups. We do agree, however, that EPA’s proposed closure standards in 

§146.93 need revision. In order to assure that site risks have diminished to the point that it is 

reasonable to discontinue or significantly reduce monitoring, it is essential that the rule require a 

demonstration of much more than merely ‘plume stabilization’ and that the nature of what must 

be demonstrated be precisely described. In addition, given the desired permanent nature of CO2

sequestration in the subsurface and the importance to the public of ensuring long-term oversight 

of project sites, EPA should use its existing regulatory authorities to establish a framework for 

long-term stewardship and seek whatever additional authorities may be required for this purpose 

from Congress. This framework should include an entity with responsibility for monitoring and 

managing sites after closure has been authorized. The proposed rule authorizes operators to stop 

monitoring, but does not provide for the stewardship of sites following closure.. EPA must 

rectify this omission. It is important that the post-closure framework include financing provisions 

that are adequate to ensure proper site stewardship in the long-term. 
 10

E. Specific Amendments to the Proposed Rule 

The rule should authorize Class VI permits for “up to” the operating life of a facility only if 

the rule is amended to require all aspects of project operations to be modified as appropriate 

over the course of the project

We support EPA’s proposal in §144.36 to issue Class VI well permits for a period “up to” the 

operating life of the facility. Still, it is not appropriate to issue these permits for the full operating 

life of the facility without consideration how project performance is evolving. Revisions of the 

Area of Review, and the various plans outlined in the proposed rule are to be expected from time 

to time, and it is possible that some of the needed revisions might be so material so as to 

constitute ground for modification, revocation or reissuance of the permit. 

Class VI is appropriately grouped with Class I Hazardous, Class II and Class III wells in the 

modification or revocation and reissuance provisions

We believe that EPA in §144.39 has appropriately listed Class VI alongside other injection 

classes for which a permit can be revoked and reissued for a specific cause (alterations to the 

facility, new information received and regulatory changes since the permit issued. This is 

necessary in order to ensure that Class VI regulations are adaptive, reflecting experience in GS as 

it is amassed. We do not support Class VI being listed alongside classes for which the permittee 

has control over whether reissue or modification would occur through requesting or agreeing to 

it. 

The definition of “carbon dioxide stream” should not be restricted to CO2 captured from 

industrial sources

The definition of “carbon dioxide stream” in §146.81(b) includes only carbon dioxide “that has 

been captured from an emission source (e.g., a power plant).” Over time, the vast majority of 

sequestered CO2 is likely to be captured from such sources, but rules are also needed to govern 

the sequestration of naturally occurring CO2 produced from geologic formations. We suggest 

that the definition be revised to read as follows: 

“Carbon dioxide stream means that has been captured from an emission source 

(e.g., a power plant), carbon dioxide plus incidental associated substances derived 

from the source materials 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.” 

Class VI applicants should be required to identify all known wells penetrating formations 

affected by increased pressure
 11

In proposed §144.55(a) the rule would require Class I, II (other than existing), III or VI permit 

applicants to identify the location “of all known wells within the injection well’s area of review 

which penetrate the injection zone” or, in the case of Class II wells operating over the fracture 

pressure of the injection formation, “all known wells within the area of review penetrating 

formations affected by the increase in pressure”. 

Since injection in deep saline formations will result in an area of elevated pressure (above the 

original reservoir pressure) that will be larger than the CO2 plume and could affect overlying or 

underlying formations, we believe that the latter requirement for Class II wells operating above 

the fracture pressure should also apply to Class VI wells. This would help prevent the unwanted 

migration of reservoir fluids from outside the injection zone through existing wells in the 

confining zone, as a result of the pressure increase. We therefore suggest that §144.55(a) be 

revised to read as follows: 

 “Coverage. Applicants for Class I, II, (other than existing), or III, or VI injection 

well permits shall identify the location of all known wells within the injection 

well's area of review which penetrate the injection zone. In the case of Class II 

wells operating over the fracture pressure of the injection formation, applicants 

shall identify the location of all known wells within the area of review penetrating 

formations affected by the increase in pressure. Applicants for Class VI shall 

identify the location of all known wells within the area of review penetrating the 

injection zone and all known wells which penetrate formations affected by the 

increase in pressure and shall perform corrective action as specified in Sec. 

146.84.” 

The rule should explicitly exclude from Class VI efforts to sequester CO2 in basalts, coal 

seams, salt caverns and shales, which instead should be regulated under Class V Experimental

We believe that EPA has ample basis for adopting rules to regulate geologic sequestration in 

hydrocarbon reservoirs and in deep brine formations. For these types of geologic formations, 

there is a widespread technical consensus on how to assess and manage risks, what data is 

needed to characterize sites, how to select sites, how to conduct injection operations, how to 

model the behavior of CO2 in the reservoir, and how to monitor project performance. There is no 

such consensus, however, regarding 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 to those in deep saline formations and hydrocarbon reservoirs, and using 

identical regulatory language would be ill advised. In fact, it is not known at this time whether 

sequestration (or even injection in some cases) can even be done at scale in such formations – 

efforts in these formations are very much still in the experimental stage. There is no basis at this 

time for determining whether rules that are appropriate for wells in hydrocarbon reservoirs and 

deep saline formations are also appropriate for wells in these other formations. 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 

wells under Class V. 
 12

Projects designed to evaluate injection in coal seams, salt caverns and shales should be permitted 

under the UIC Class V provisions and subject to the March 2007 Guidance on “Using the Class 

V Experimental Technology Well Classification for Pilot GS Projects.20 This Guidance clearly 

states that Class V is intended only for projects “...designed to evaluate the technical issues 

associated with CO2 injection”21. The Director should review all Class V GS permit applications 

to insure that they meet the definition of Pilot Project in CFR 146.3: “... a technology which has 

not proven feasible under the conditions in which it is being tested.” The purpose of such pilot 

projects should be to gather and share information which will lead to a clearer understanding of 

the feasibility of such projects on a commercial scale. 

In order to implement our suggestion regarding these formations, we recommend revising 

sections 144.6(f), 144.80(f), 146.5(f) and the definition of sequestration in §146.81 accordingly. 

We suggest retaining the provision in proposed §144.15 that the construction, operation or 

maintenance of any non-experimental Class V geologic sequestration well is prohibited. 

The rule should not prohibit in a blanket fashion GS sites located above the lowermost USDW, 

but should permit such sites only under certain conditions that are not applicable to sites 

below the lowermost USDW

We believe that GS sites located above lowermost USDWs may or may not present more types 

of risk than sites located below lowermost USDWs, but that in any event the consequences of 

leakage from sites above USDWs are likely to be more significant in the event that leakage 

occurs. At the same time, we recognize that there many potentially excellent sequestration sites 

above USDWs and that in some areas these may be the only sites available. We believe the rule 

should authorize GS sites above lowermost USDWs only if such sites meet requirements that go 

beyond what is mandatory for other sites. The following additional conditions would need to be 

satisfied: 

• confirmation that there is a confining zone underlying the entire base of the injection 

zone; 

• mandatory monitoring for changes in groundwater chemistry above the upper confining 

zone and below the lower confining zone; and 

• prior to permit issuance, and as a condition of 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. 

Emergency and remedial response, including response to potential problems relating to 

geologic features, is a necessary complement to corrective action and should remain in the 

rule

 

20 UICPG#83 

21 Id. at p. 1 
 13

While wells are the most likely conduits for fluid movement into USDWs, the definition of 

corrective action and the relevant provisions in §146.84 do not take into account the potential for 

geologic features, such as faults, spill points or fractures, to act as conduits for CO2 or other fluid 

migration, and hence breach of confinement. Actions to mitigate or remediate a potential breach 

of confinement, or a situation which might eventually lead to a breach of confinement, should 

not be limited to corrective action on wells. We therefore strongly support EPA’s inclusion of the 

Emergency and remedial response section. We propose two minor changes – change 

§146.94(b)(4) to read: 

“Implement the emergency and remedial response plan approved by the Director, 

and keep him apprized of the implementation.” 

and §146.94(d) to read: 

“The owner or operator must notify the Director and obtain his approval prior to 

conducting any well workover or other remediation measures not listed in the 

emergency and remedial response plan.” 

The definition of “confining zone” should not be limited to formations overlying the injection 

zone, and should focus on limiting movement through the confining zone rather than out the 

injection zone

The proposed definition of confining zone in §146.81(d) requires that the formation act as “a 

barrier” to fluid movement, which may be unnecessarily strict. The definition also fails to 

recognize that it is movement through and beyond the confining zone that needs to be limited. 

We suggest instead that the definition of “confining zone” read as follows: 

“Confining zone means a geologic formation, group of formations, or part of a 

formation stratigraphically overlying the injection zone that acts as a barrier to 

limit fluid movement beyond this formation, group of formations, or part of a 

formation.” 

The second sentence of the definition of ‘geologic sequestration project” should be amended 

to refer more generally to formation fluids and be transferred to the definition of “area of 

review”

We suggest the following amendment to §146.81(d) in order to be more inclusive on the types of 

fluid that could be displaced: 

“[...] It includes the subsurface three-dimensional extent of the carbon dioxide 

plume, associated pressure front, and displaced brine formation fluids, as well as 

the surface area above that delineated region.” 
 14

We also suggest that this second sentence of the definition of geologic sequestration project be 

transferred to the definition of area of review as recommended above. The language provided 

above reflects the change from “brine” to “formation fluids.” 

Moreover, we suggest that the present restriction of Class VI to formations below the lowermost 

USDW is more appropriately addressed elsewhere. Accordingly, we recommend that geologic 

sequestration project be defined as follows: 

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

a carbon dioxide stream beneath the lowermost formation containing a USDW

into an injection zone for geologic sequestration. It includes the subsurface threedimensional extent of the carbon dioxide plume, associated pressure front, and 

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

The term “pressure front” should be replaced with the more accurate term “area of elevated 

pressure” throughout the rule

The term “pressure front” in 146.81(d) is likely to be scientifically inaccurate as it implies a 

front, or discontinuity in pressure, whereas in reality there will be a continuous pressure gradient 

in the formation in most cases. We suggest globally replacing “pressure front” with “area of 

elevated pressure” throughout the rule. 

Additional well identification methods that do not rely on the public record should be required 

in certain provisions

§146.82(b) requires a map to be submitted with the permit that shows wells within the area of 

review – only information of public record is required to be included on this map. §146.82(e) 

requires a tabulation of all wells within the area of review which penetrate the injection or 

confining zone(s), including information on the well’s type, construction, date drilled, location, 

depth, record of plugging and/or completion and any additional information that the Director 

may require. 

While we are comfortable with relying on information of public record in subsection (b), we 

believe that additional diligence is needed when it comes to wells that penetrate the injection or 

confining zone in subsection (e). Information of public record is often incomplete and/or 

inaccurate. There are numerous orphaned or abandoned wells that are not listed on the public 

record that could potentially affect the integrity of the confining zone. While generally it is 

possible to intercept these problems during operations, there are methods available today to 

identify wells not listed on the public record22, which in many cases could identify potentially 

problematic wells in advance. A requirement to supplement public record information with field 

measurements should be included in the rule, and described with a term that is broader than 

“tabulation” in order to allow the Director to require other data formats as needed : 

 

22 NETL , for example, has developed an electromagnetic system that can be used for areal or ground-based 

identification of wells (casings). 
 15

§146.82(e): “A tabulation compilation of all wells within the area of review which 

penetrate the injection or confining zone(s). To supplement and/or verify 

information of public record, operators shall use reasonable methods to identify 

the presence wells within the area of review that penetrate the injection or 

confining zone(s). Such data must include a description [...]” 

Additionally, we believe that problematic wells may not be limited to the confining zone, as 

would be the case if confinement were to be breached, or if pressure effects caused by the 

injection caused fluid movement outside the defined confining zone. We recommend the 

following modification in §146.84(c)(2): 

“Using methods approved by the Director, identify all penetrations, including 

active and abandoned wells and underground mines, in the area of review that 

may penetrate the confining zone or otherwise act as conduits for fluid movement 

inside or outside the confining zone”. 

The term “transmissive fault or fracture” should be clarified

The proposed rule in §146.83(a)(2) requires a confining zone(s) that is free of transmissive faults 

or fractures, while §146.81 defines this term as “A fault or fracture that has sufficient 

permeability and vertical extent to allow fluids to move between formations”. We suggest the 

following modification to the definition in §146.81(d) in order to avoid unduly restricting 

movement that is merely between formations (compare our comments above on the definition of 

“confining zone”): 

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

permeability and vertical extent to allow fluids to move between formations

beyond a confining zone.” 

Secondary confining zone

§146.83 allows the Director to require additional confining zones, at his discretion. We do not 

believe that this will always be necessary – a good primary zone should be sufficient. Where 

additional hazards justify it, a secondary zone might be desirable. In all cases, we caution against 

relying on secondary confinement in place of establishing with a greater degree of certainty the 

suitability of the primary zone. Potential problems are best identified and anticipated early, and 

the focus should be on site characterization to show with confidence whether the confining zones 

are adequate. We suggest striking part (b) in §146.83 as it seems redundant. However, the 

Director must have the discretion to require a secondary confining zone if needed. We therefore 

recommend clarifying part (a)(2) to read explicitly: 

“A confining zone, or zones, that is are free of transmissive faults or fractures and 

of sufficient areal extent and integrity to contain the injected carbon dioxide 
 16

stream and displaced formation fluids and allow injection at proposed maximum 

pressures and volumes without initiating or propagating fractures in the confining 

zone(s)” 

The area of review provisions should be revised in several respects

Surprisingly, the definition of “area of review” (AOR) in §146.81(d) fails to mention that 

elevated pressure a critical aspect of what it means for an area to be “impacted” by injection 

activity. Our Environmental NGO Group recommends borrowing language from the proposed 

definition of “geologic sequestration project” and reworking the “area of review” definition. 

An additional concern is that both §146.81 and §146.84(a) state that the AOR is “based on 

computational modeling”. This could imply that the Area of Review could be based solely on 

computational modeling. Instead, the AOR should be based on computational modeling, 

monitoring and operational data (and kept updated until closure is approved). All references to 

computational modeling in relation to the Area of Review in this section, as well as in the 

definition of Area of Review in §146.81 should be amended as appropriate to read “based on 

computational modeling, as well as monitoring and other operational data.” We urge that the 

definition be revised as follows: 

“Area of review means the area that may be impacted by the injection activity. 

The area of review is based on computational modeling, as well as monitoring and 

other operational data, that account for the physical and chemical properties of all 

phases of the injected carbon dioxide stream. It includes the subsurface threedimensional extent, throughout the operating life of the facility, of the carbon 

dioxide stream plume, associated pressure front, and displaced formation fluids,

as well as the overlying formations and surface area above that delineated 

region.”

Even though proposed §146.84(f) requires “reevaluation” of the AOR at a “minimum” fixed 

frequency of ten years or “when operational and monitoring conditions warrant” (the “and” 

should be an “or”), §146.84 runs the risk that revisions will not be made on a timely basis. 

Default periods have a way of becoming the standard way of doing business. We recommend 

imposing a continual obligation on operators to assess whether the AOR should be revised, a 

requirement for an annual report stating whether circumstances during the preceding year 

warranted a revision, and a requirement that revisions be done when required by the Director as 

well as when the operator determines that conditions warrant. To accomplish this, it will be 

useful to break down the concept of “reevaluation” into two ideas – “assessment” of the need to 

revise the AOR and the actual process of “revision.” There are several portions of §146.84 that 

will need to be changed in order to incorporate these suggestions. We believe that these 

suggestions will incentivize honest and truthful reporting of data and site performance while 

avoiding the excessive burden of “re-evaluating” or revising the Area of Review if such work is 

not needed. Moreover, a continuous obligation to assess whether revisions are needed, when 

coupled with the annual reporting requirement just suggested, will create a clear accountability 

trail for both operator and Director in case of disputes. 
 17

The rule should require updating when warranted of all of the proposed “plans” and should 

require an annual report that summarizes whether not updates have been warranted, and 

whether or not updates have been undertaken

We applaud EPA for proposing to require the creation, use, and updating of various “plans” 

during the operating life of a facility. By creating such an iterative process, and basing it on 

monitoring and other operational data that become available through time, EPA can assure that 

facilities are managed in a way that adapts to changing circumstances. This approach also has the 

potential to enable what the Preamble calls an “ongoing dialogue” between operators and 

regulators, especially if the rule is enhanced by the annual reporting requirement suggested 

below for inclusion in §146.91. 

Perhaps inadvertently, the proposed rule does not explicitly require updating of several of the 

required plans. In most but not all cases, there is a rather ambiguous requirement to “maintain” a 

given plan. Explicit requirements to make updates as warranted appear to be missing from 

provisions relating to: 

• the testing and monitoring plan required by §146.90 (the ambiguous word “maintain” 

is used and there appears to be no requirement that estimated plugging costs be kept 

current); 

• the plugging plan required by §146.92 (again the ambiguous word “maintain” is 

used); 

• the post-injection site care and site closure plan required by §146.93 (not only is the 

word “maintain” used, but the ambiguity inherent in this term is revealed by the 

instruction in §146.93(a)(3) to consider amendments to this plan “upon cessation of 

injection” – §146.93 might be read to mean that operators could “maintain” this 

particular plan simply by considering the need for amendment on one occasion over 

the life of the facility); and 

• the emergency and remedial response plan required by §146.94 (there is no 

requirement here that the plan be updated as warranted – there is not even a 

requirement that the plan be “maintained.” 

An additional annual reporting requirement will enhance the ability of both Director and 

operators to keep track of which plans require updating and whether or not plans that ought to be 

updated have in fact been revised. Such a shared understanding is essential if there is to be the 

“ongoing dialogue” between regulators and operators that EPA anticipates. Our Environmental 

NGO Group considered supporting the inclusion of an annual report as described in the preamble 

at 73 Fed. Reg. 43518, but concluded that the benefits of that particular report would be 

outweighed by the burden. The annual report we are suggesting here, however, would be much 

simpler. We believe that EPA should require a report, signed by the appropriate company 

official, that: 

• lists all of the required plans; 
 18

• confirms for each plan that the company has reviewed all monitoring and operational 

data since the previous annual report that is relevant to a decision on whether to 

update the plan; 

• states with regard to each plan whether an update was determined to be warranted; 

and 

• for those plans where the operator did decide that an update was appropriate, a 

statement that the update has or has not been completed and a summary of the 

modifications that have been made. 

The rule should further provide that the Director has authority to require submission of copies of 

updated plans and/or further information regarding the reasons why updates of particular plans 

have or have not been done. 

Cementing requirements for casings

§146.86(b)(3) requires the long string casing to be cemented by circulating cement to surface in 

one or more stages. It has come to our attention that may be hard to accomplish in some cases, 

such as very deep wells. We have also been alerted to disadvantages of this approach with regard 

to the weight of the cement column and its relation to well integrity. We urge EPA to fully 

consider the advantages and disadvantages of this approach. At a minimum however, the long 

string casing should be cemented to at least above the confining layer (caprock). 

Cement bond logs and other outdated methods are not sufficient for establishing cement 

quality and integrity

Some of the techniques listed in §146.87(a)(2)(ii) and §146.87(a)(3)(ii), such as cement bond and 

variable density logs are no longer state-of-the-art, and do not reveal the nature or shape of any 

voids in the cement – instead they represents an average estimate of void space. To verify the 

integrity of cement behind casings, including the location of any channels, contamination or 

missing cement, the Director should require “a cement map that incorporates data from a cement 

bond log, a variable density display, and an ultrasonic image, unless an alternative evaluation 

based on equivalent or better technologies has been approved in writing”. 

Monitoring

In §146.90 the proposed rule outlines requirements for testing and monitoring. We strongly 

support the inclusion of such provisions. Monitoring is central to verifying and adapting the 

operational parameters of a GS project, while the concept of GS cannot be simply based on the 

premise of confinement without verification. We also support the provisions calling for a testing 

and monitoring plan, although we have suggested above that the requirements for updating this 

plan be strengthened. The collection of baseline data and information prior to the commencement 

of operations is also necessary for a number of monitoring techniques to produce useful results, 

and should be preserved. 
 19

The proposed rule outlines several different types of monitoring requirements: (a) analysis of the 

CO2 stream; (b) continuous monitoring of injection pressure, rate and volume as well as other 

quantities; (c) corrosion monitoring for the well materials; (d) groundwater and geochemistry 

monitoring above the confining zone; (e) mechanical integrity testing; (f) pressure fall-off tests; 

(g) CO2 plume and pressure front tracking; and (h) surface air monitoring. 

We do not wish to comment on (c). We consider subpart (i), enabling the Director to require 

additional forms of monitoring, as well as subpart (j), calling for a quality assurance and 

surveillance plan, entirely appropriate. We consider (a), (b), (d), (e), and (f) and (g) to be 

essential elements of a sound monitoring system. 

In particular, monitoring above the caprock, sometimes informally referred to as “above-zone 

monitoring, and covered in (d), is a tested monitoring method23, and one that can be key to 

verifying the integrity and lateral extent of the caprock (or confining zone). We support its 

inclusion, but also recognize that it might not be necessary to employ this method every time. 

We would only consider its omission acceptable only if another method capable of testing and 

verifying the integrity of the confining zone is being used. Subpart (d) would also cover 

groundwater monitoring near the surface, at a long distance from the caprock. It is our 

understanding that researchers from the Lawrence Livermore National Laboratory are already 

confident in the merits of this approach and its accuracy in detecting small amounts of CO2. We 

therefore recommend the following minor changes to §146.90(d): 

“Periodic monitoring of the ground water quality and geophysical, geochemical or 

other changes above the confining zone(s) that may be a result of carbon dioxide 

or other induced fluid movement through the confining zone or additional 

identified zones; provided however that the Director may instead require the 

inclusion of other methods that test and/or verify the integrity of the confining 

zone(s) with similar accuracy and to the same or larger areal extent.

(1) [...]” 

We also strongly support monitoring to track the CO2 plume. There is no unique method for 

doing this, and we do not believe that 4D-seismic techniques are appropriate or effective in all 

geologic settings, or that they should be made mandatory. However, tracking the extent of the 

CO2 plume is generally possible and must be part of a comprehensive and credible monitoring 

plan and a GS project. Appropriate limits of accuracy will be needed, as neither tracking 

individual CO2 molecules, nor to the nearest inch are feasible or desirable. However, the 

monitoring resolution must be such so as to enable confinement to be established, to give 

regulators confidence that the CO2 and displaced fluids are not near potential leakage pathways, 

and to warn in advance of any remedial action that might be needed. 

The “position of the pressure front” is not something that is as straightforward to establish as the 

extent of the CO2 plume. As we have commented above, there is no distinct “front”, or 

discontinuity, but rather a gradient in pressure that dissipates with distance away from the 

injection zone. Estimating the total injection footprint therefore will require appropriate 

 

23 Used successfully at the Frio pilot project, and already being considered for other projects. 
 20

thresholds to be defined in order to estimate the area of elevated pressure. Additionally, methods 

such as seismic surveys do not work in the same way for compressed brine as they do for CO2-

rich brine. Tracking the extent of the CO2 plume is generally possible and must be part of a 

comprehensive and credible monitoring plan and a GS project. The extent of the area of elevated 

pressure will likely be estimated with a combination of measurements, inferences and modeling, 

but it is presently essential to have monitoring wells penetrating the confining zone to do this. 

Where the CO2 plume itself is concerned, rather than the area of elevated pressure, the role of 

measurements (including indirect measurements such as seismic surveys) will and should be far 

greater than that of modeling. 

Finally, surface air monitoring techniques will not always be necessary for GS projects. As with 

other monitoring methods, they may work well in particular settings but not in others (for 

example where distinguishing from natural variability or from baseline data is hard). Current 

scientific thinking also dictates that the CO2 plume and confinement are best monitored near the 

injection zone or right above the caprock. This implies far greater depths, and a much larger 

distance between CO2 and displaced fluids from USDWs. The Director should have the 

discretion to require such techniques, but we do not believe that they should be made mandatory 

for all permits nor should the rule be limited to listing specific techniques (which might be 

superseded or have preferable alternatives). 

To capture the points made above and resolve current inaccuracies or limitations in the proposed 

language, we recommend the following additional changes in §146.90(g): 

“(1) Testing and monitoring to track establish the extent of the carbon dioxide 

plume and the position of the pressure front within defined thresholds, with the 

assistance of modeling tools where appropriate and through direct measurements

or indirect, geophysical or other techniques by either monitoring for pressure 

changes in the first formation overlying the confining zone or using indirect, 

geophysical techniques (e.g., seismic, electrical, gravity, or electromagnetic 

surveys and/or down-hole carbon dioxide detection tools); 

(2) Testing and monitoring to establish the extent of the area of elevated pressure 

through direct measurements and the assistance of modeling tools.” 

and in §146.90(h): 

“At the Director’s discretion, surface air monitoring methods and/or soil gas 

monitoring to detect movement of carbon dioxide that could signal endangerment 

of a USDW. 

(1) The testing and monitoring plan must be based on potential vulnerabilities 

within the area of review; 

(2) The monitoring frequency and spatial distribution of surface air monitoring 

and/or soil gas monitoring must reflect baseline data and the monitoring plan must 

include how the proposed monitoring will yield useful information on the area of 

review delineation and/or compliance with standards under 40 CFR 144.12” 
 21

Seismicity

Naturally occurring seismicity has been cited as an area of concern for geologic sequestration of 

CO2. We do believe that seismicity merits diligent treatment both in the regulations and in 

project operation, but we see no need for a blanket ban of sequestration in seismically active 

areas. Although some sites – especially ones near major active faults – would not be advisable 

for injection, there are plenty of other sites in seismically active areas that would make excellent 

candidates for safe and effective sequestration. Moreover, tools to measure, predict and design 

against the effects of seismic activity are available. 

Nature has proven its ability to retain fluids trapped in the subsurface in seismically active areas 

in many instances over hundreds of millions of years, even in highly tectonically active regions 

of the country such as California. The potential for slippage for faults to create leakage pathways 

to USDWs or the surface can be managed and effectively minimized through careful siting and 

operational design using well-established tools and methods. The regulations should ensure that 

suitable sites are selected, while high risk areas, such as those near major, non-sealing faults or 

those that demonstrate frequent activity, are rejected. The most likely potential CO2 leakage 

paths would be injection wells, and not faults. However, these can be designed to prevent 

leakage and to be resilient to earthquakes. 

We regard a ban on sequestration in seismically active areas unwarranted. We do however 

believe that additional diligence is required in site characterization and selection in such areas. 

The requirement in §146.82(c)(3) should be modified as follows: 

“Information on seismic history including the presence and depth of seismic 

sources and an assessment of that whether such seismicity would not interfere 

with containment;” 

In addition, language should be added to the minimum criteria for siting in §146.83, clarifying 

that if induced or natural seismicity poses unacceptable risks, a permit will not be granted. In 

order properly to assess the risk of significant induced seismicity in light of permitted operating 

conditions, the rule may need to require applicants to submit information beyond what is 

currently required in proposed §146.82. The effects of any seismic events during project 

operation should also be taken into account when updating, or considering whether to update, the 

Area of Review and Corrective Action Plan, the Testing and Monitoring Plans, and the 

Emergency and Remedial Response Plans, as well as any other plans as necessary. 

F. Conclusion 

Our Environmental NGO Group appreciates 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 
 22

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

term. 

Respectfully submitted, 

Kurt Waltzer, Clean Air Task Force

Lynn Thorp, Clean Water Action

Scott Anderson, Environmental Defense Fund

George Peridas, Natural Resources Defense Council

John Nielsen, Western Resource Advocates
Letter ID: 0250 

Commenter: Kurt Waltzer 

Organization: Clean Air Task Force 

Letter ID: 0250 Comment ID: 22269 Letter Lines: 68 to 99 

Comment Code: 1280 1.1.2.1 General comments on climate change/ global warming 

Comment: The planet’s climate is changing fast. Greenhouse gas emissions from the use of 

fossil fuels, mainly carbon dioxide (CO2), are having a profound effect on our 

climate, presenting us with one of the most significant environmental and social 

challenges of the century. In its most recent Assessment Report last year, the 

Intergovernmental Panel on Climate Change, an independent scientific body, 

issued the loudest warning to date, calling the warming in the climate system 

"unequivocal" and calling for serious emission reductions if we are to avoid 

truly dangerous greenhouse gas concentrations. Failure to pursue significant 

reductions in greenhouse gas emissions very soon will make it much harder in the 

future both to stabilize atmospheric pollution concentrations and to avoid the 

worst impacts of climate change. Climate change is expected to and, indeed, 

already is having a profound effect on sources of drinking water. The American 

West, for example, is already becoming noticeable hotter and drier, as a recent 

compilation of studies by the Rocky Mountain Climate Organization (RMCO) and 

NRDC summarizes.[FN1] 

[FN1: 1 "Hotter and Drier: The West’s Changes Climate". Rocky Mountain Climate 

Organization (RMCO) and the Natural Resources Defense Council. Available at: 

http://www.nrdc.org/globalWarming/west/west.pdf] 

A growing body of scientific research indicates that we face extreme dangers to 

human health, economic well-being, and the ecosystems on which we depend if 

global average temperatures are allowed to increase by more than 2 degrees 

Fahrenheit from today’s levels. We have good prospects of staying below this 

temperature increase if atmospheric concentrations of CO2 and other global 

warming gases are kept from exceeding 350 to 450 parts per million (ppm) 

CO2equivalent. Achieving this goal will require rapid reductions in existing 

emissions, including action to cut emissions by approximately 80% by midcentury. This goal is ambitious, but achievable. It can be done through an 

annual rate of emissions reductions that ramps up to about a 4% reduction per 

year. Fortunately, a wide variety of tools is available today to achieve those 

reductions. 

Individual Response: GS is one technology in a portfolio of options, including energy 

conservation, efficiency improvements, and the use of alternative fuels and renewable energy 

sources, that could be deployed to reduce CO2 emissions. However, the use and promotion of 

these technologies is outside the scope of the Class VI GS rulemaking. The Class VI GS 

1
requirements are designed to ensure that, where GS is deployed, projects are permitted, sited, 

constructed, operated, and closed in a manner that protects USDWs from endangerment. 

Letter ID: 0250 Comment ID: 22270 Letter Lines: 101 to 120 

Comment Code: 1330 1.1.3.1 Support use of GS in general 

Comment Code: 1350 1.1.3.3 Comments on the need for GS technology 

Comment: While it is not a "silver bullet", one important tool is the geologic 

sequestration (GS) of CO2 at properly selected and properly regulated sites. Our 

Environmental NGO Group does not necessarily have a common view concerning the 

magnitude of the long-term role of GS in combating climate change, but we are 

united in recognizing that a transition away from fossil fuels will take time 

and that GS is likely to be an important part of the near- to medium-term 

solution. Fortunately, capturing CO2 and permanently sequestering it in certain 

types of well-selected and well-managed geologic formations is a technology that 

is ready to begin deployment today. While GS projects can be permitted today 

under the Safe Drinking Water Act’s (SDWA) UIC program (in fact a number of 

projects have already been permitted under existing well classes), the rules 

that currently apply to such projects were not designed with geologic 

sequestration in mind. Thus, the importance of this rulemaking is not that it is 

needed in order for GS projects to receive permits; rather, the rulemaking is 

important because it can assure that GS projects are regulated under rules that 

are specifically designed to require GS projects to be done safely and 

effectively without endangering underground sources of drinking water (USDWs) 

or, as discussed below, resulting in a risk of release to the atmosphere. For 

that reason, it is essential that EPA promulgate final rules for GS in a timely 

manner that are sufficient to protect USDWs. 

Individual Response: EPA agrees that GS is one technology in a portfolio of options, including 

solar, wind, biomass, and geothermal, that could be deployed to reduce CO2 emissions; however 

these technologies are outside the scope of the UIC GS rulemaking. The Class VI GS 

requirements are designed to ensure that, where GS is deployed to address climate change, 

projects are permitted sited, constructed, operated, and closed in a manner that avoids releases of 

CO2 into USDWs. 

Please see the remainder of EPA’s responses to this 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: 0250 Comment ID: 22271 Letter Lines: 122 to 139 

Comment Code: 1310 1.1.2.4 Comments on other "out of scope" issues, e.g., pore space 

ownership 

Comment Code: 1420 1.2.1.1 Support the GS rulemaking 

2
Comment: It is also essential that the U.S. Environmental Protection Agency (EPA) take 

supplemental action, based on other (non-SDWA) authority, to provide additional 

assurance that injected CO2 will not be released into the atmosphere in a way 

that adversely impacts the climate or otherwise endangers public health and 

welfare. Generally, the steps needed to protect USDWs are also needed in order 

to prevent emissions to the atmosphere. Supplemental steps citing additional 

authority should also guarantee that CO2 injected into geologic formations stays 

out of the atmosphere. This should be done according to a permanence 

(performance) standard, which will certify CO2 as ‘geologically sequestered’ for 

that purpose, in addition to protecting USDWs. These are needed, as none of the 

existing or proposed injection classes are adequate for the task of certifying 

CO2 as permanently sequestered for the purposes of preventing atmospheric 

releases. In order to be fully protective of the environment, Congress will also 

need to pass comprehensive cap and trade legislation to control the emission of 

greenhouse gases from all anthropogenic sources. But the need for such 

legislation is not a basis for deferring the adoption of EPA rules to protect 

USDWs or to assure that injected CO2 does not result in harmful releases to the 

atmosphere. 

Individual Response: EPA acknowledges that the issue of GS falls within the broader context of 

CCS, but clarifies that the scope of the GS regulation is limited to injection of CO2, and that all 

requirements in the GS rule are designed for the purpose of protecting USDWs from 

endangerment. The SDWA does not provide the UIC Program with the authority to develop 

regulations for all areas related to GS, such as releases to the atmosphere. "Cap and trade" 

legislation is outside of the scope of this rulemaking. The UIC requirements are designed to 

ensure that, where GS is employed, it is done in a manner that protects USDWs from 

endangerment. 

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. 

In a separate rulemaking under authority of the Clean Air Act, EPA is amending the Greenhouse 

Gas (GHG) Reporting Program at 40 CFR Part 98 to add reporting requirements for facilities 

that conduct GS (subpart RR) and all other facilities that inject CO2 underground (subpart UU). 

3
For additional information, see the section of the final GS rule preamble entitled, "How Does 

Mandatory Reporting of Greenhouse Gases (GHGs) Relate to This Rulemaking?” and the GHG 

Reporting Program rulemaking and docket. 

Letter ID: 0250 Comment ID: 22272 Letter Lines: 141 to 167 

Comment Code: 1290 1.1.2.2 Comments that EPA should regulate CO2 as a pollutant 

Comment Code: 1310 1.1.2.4 Comments on other "out of scope" issues, e.g., pore space 

ownership 

Comment: The Supreme Court recognized in Massachusetts v. EPA [FN2] that EPA has 

authority and, indeed an obligation, under the Clean Air Act to regulate 

emissions of greenhouse gases, including CO2, that "cause or contribute to air 

pollution that may reasonably be anticipated to endanger public health or 

welfare." [FN3] Similarly, the D.C. Circuit’s remand of the power plant new 

source performance standards ("NSPS") places EPA in the position to regulate CO2 

emissions from new and also existing sources within that industrial sector. 

[FN4] The Environmental Appeals Board EAB also recently has rejected the 

agency’s arguments that it is not authorized to issue best available control 

technology (BACT) emissions limits for CO2 in the context of a new source air 

permit decision for a large new coal-fired power plant, under the Clean Air 

Act’s Prevention of Significant Deterioration (PSD) new source review authority. 

[FN5] 

[FN2: 127 S.Ct. 1438 (2007).] 

[FN3: Id. at 1460-61.] 

[FN4: Order, NY, et al. v. EPA, D.C. Cir. No. 06-1322 (Sept. 24, 2007). Once 

NSPS are set for an industry under section 111(b), 42 U.S.C. §7411(b), the Act 

requires EPA to set standards for states to regulate emissions from existing 

sources in that industry. 42 U.S.C. § 7411(d).] 

[FN5: In re: Deseret Power Electric Coop., PSD App. No 07-03, Slip Op. (Nov. 13, 

2008). The memorandum issued December 18, 2008 by Administrator Johnson entitled 

"EPA’ Interpretation of Regulations that determine Pollutants Covered by Federal 

Prevention of Significant Deterioration (PSD) Permit Program" (Johnson PSD memo) 

is procedurally deficient, and, in any event, states explicitly on its face that 

it is not intended to supersede the EAB’s decision in the Deseret case. Johnson 

memo at 2. Nor, indeed, can it lawfully do so.] 

Individual Response: The purpose of the Class VI GS regulation is to ensure consistency in 

permitting underground injection of CO2 at GS operations across the United States and provide 

requirements to prevent endangerment of USDWs in anticipation of the eventual use of GS to 

reduce CO2 emissions. The requirements apply only to GS injection technologies including well 

construction, operation, monitoring and testing technologies. The Supreme Court decision under 

Massachusetts v. EPA and Clean Air Act (CAA) provisions related to New Source Performance 

Standards (NSPS) and Best Available Control Technology (BACT) determinations are outside 

the scope of this Class VI GS rulemaking. 

4
The Class VI GS rulemaking is promulgated under Safe Drinking Water Act authority and does 

not relate to any endangerment and cause or contribute findings under the Clean Air Act. The 

Class VI GS requirements do not depend upon, and are unaffected by, Clean Air Act 

endangerment and cause or contribute findings. More information on EPA's Endangerment and 

Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act 

can be found at http://www.epa.gov/climatechange/endangerment.html. 

In a separate rulemaking under authority of the Clean Air Act, EPA is amending the Greenhouse 

Gas Reporting Program at 40 CFR Part 98 to add reporting requirements for CO2 injection and 

geologic sequestration. The greenhouse gas reporting requirements build on the requirements 

outlined in the Class VI GS rule with the additional goals of verifying the amount of CO2 

sequestered and collecting data on any CO2 emissions to the surface from GS facilities. 

Letter ID: 0250 Comment ID: 22274 Letter Lines: 169 to 192 

Comment Code: 1280 1.1.2.1 General comments on climate change/ global warming 

Comment: In comments on the Agency’s recent advanced notice of proposed rulemaking on 

using the Clean Air Act to combat climate change, a coalition of environmental 

NGOs, including some members of our Environmental NGO Group, pointed out that 

for the U.S. to achieve its necessary climate goals, controlling CO2 emissions 

from new and existing sources of CO2 is required. That necessitates reductions 

from all sectors, including radical shifts to zero-emitting technologies and 

corrective action on existing sources. These reductions will require targeted 

measures and policies, which include air regulations that would set CO2 

emissions standards implicating the capture and sequestration of CO2. Setting an 

NSPS or a BACT standard based on CO2 capture technology necessarily creates a 

need for complementary requirements to assure that the captured CO2 is 

effectively isolated from the atmosphere. At this time, such an outcome requires 

injecting CO2 underground for permanent sequestration in either hydrocarbon 

reservoirs or deep saline formations. Such permanent sequestration clearly meets 

the definition of underground injection, regulated by the UIC program of the 

Safe Drinking Water Act ("SDWA").[FN6] 

[FN6: 6 42 U.S.C. §300h, et seq. Geologic sequestration of CO2 clearly meets the 

definition of underground injection found at 42 U.S.C. §300h(d)(1), "the 

subsurface emplacement of fluids by well injection." Carbon dioxide, whether 

injected in a supercritical state, or as a gas, meets the definition of a fluid 

included in the existing regulations under the SDWA: those rules state that a 

"fluid" is "any material or substance which flows or moves whether in a 

semisolid, liquid, sludge, gas or other form or state." 40 CFR § 144.3.] 

Individual Response: EPA agrees that GS is one technology in a portfolio of options, including 

energy conservation, efficiency improvements, and the use of alternative fuels and renewable 

energy sources, that could be deployed to reduce CO2 emissions. However, the use of and 

5
investment in these technologies is outside the scope of the Class VI GS rulemaking. The Class 

VI GS requirements are designed to ensure that, where GS is deployed, projects are permitted, 

sited, constructed, operated, and closed in a manner that protects USDWs from endangerment. 

Letter ID: 0250 Comment ID: 22275 Letter Lines: 186 to 192 

Comment Code: 1430 1.2.1.2 Support EPA's authority to regulate CO2 injection 

Comment: [FN6: 6 42 U.S.C. §300h, et seq. Geologic sequestration of CO2 clearly meets the 

definition of underground injection found at 42 U.S.C. §300h(d)(1), "the 

subsurface emplacement of fluids by well injection." Carbon dioxide, whether 

injected in a supercritical state, or as a gas, meets the definition of a fluid 

included in the existing regulations under the SDWA: those rules state that a 

"fluid" is "any material or substance which flows or moves whether in a 

semisolid, liquid, sludge, gas or other form or state." 40 CFR § 144.3.] 

Individual Response: EPA agrees that the SDWA provides EPA with the authority to regulate 

underground injection of CO2 for GS (42 U.S.C. 300h et seq.). Injection wells are regulated 

under SDWA’s UIC Program. Under the SDWA, the injection of any "fluid" is subject to the 

requirements of the UIC program. "Fluid" is defined under 40 CFR 144.3 as any material or 

substance which flows or moves, whether in a semisolid, liquid, sludge, gas or other form or 

state, and includes liquids, gases, and semisolids (i.e., slurries) injected into the subsurface. 

Letter ID: 0250 Comment ID: 22276 Letter Lines: 194 to 197 

Comment Code: 1000 1. General and Administrative Comments 

Comment: We therefore are pleased to submit these comments on EPA’s proposed rules 

concerning "Federal Requirements Under the Underground Injection Control (UIC) 

Program for Carbon Dioxide (CO2) Geologic Sequestration (GS) Wells, 73 Fed. 

Reg.43492 (July 28, 2008). 

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

responses to this 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: 0250 Comment ID: 22277 Letter Lines: 199 to 248 

Comment Code: 1430 1.2.1.2 Support EPA's authority to regulate CO2 injection 

Comment: B. The Safe Drinking Water Act Authorizes EPA to Create a Preventive, Forward 

Looking, and Adaptive Program Specific to CO2 GS Permitting 

Under the SDWA, EPA’s authority to protect USDWs is clearly defined, broadly 

6
scoped, and forward looking. [FN7] Section 1421 requires the Administrator to 

publish rules for state implemented underground injection programs that "prevent 

underground injection which endangers drinking water sources" as that phrase is 

further defined by the statute. [FN8] Such programs, at a minimum, must 

"prohibit any underground injection ... which is not authorized by a permit," 

[FN9] and such permit programs must require a showing to the satisfaction of the 

state that the underground injection will not endanger drinking water sources. ..." 

[FN10] Underground injection "endangers drinking water sources if such injection 

may result in the presence in underground water which supplies or can reasonably 

be expected to supply any public water system of any contaminant, and if the 

presence of such contaminant may result in such system’s not complying with any 

national primary drinking water regulation or may otherwise adversely affect the 

health of persons. [FN11] And "contaminant" is defined as "any physical, 

chemical, biological, or radiological substance or matter in water." [FN12] 

Underground injection furthermore is prohibited without a permit, and to receive 

a permit the applicant must demonstrate that endangerment "will not" occur. 

[FN13] This preventive, broadly scoped language demonstrates that Congress 

intended that all underground injection be regulated under the UIC program. 

[FN14] 

[FN7: While our Environmental NGO Group agrees that EPA’s primary authority for 

the promulgation of this rule is found in the Safe Drinking Water Act, we also 

point out above that the Clean Air Act authorizes controls on CO2 emissions that 

necessarily implicate and necessitate this UIC approach, and so also can be said 

to provide authority for Class VI rules. EPA must exercise its Clean Air Act 

authority to regulate CO2 for the purposes of preventing its release to the 

atmosphere. Additionally, and more generally, EPA could also promulgate 

verification and accounting protocols for CO2 GS, as needed, under those Clean 

Air Act rules. Such Clean Air Act rules may or may not prove adequate for 

purposes of any future legislatively created trading system. Clearly, however, 

the UIC rules should not be regarded as sufficient to authorize or certify 

carbon credits as part of such a system, as they do not provide sufficient proof 

that CO2 will be permanently sequestered from the atmosphere, nor do they 

include additional details necessary for verifying and quantifying any 

atmospheric releases.] 

[FN8: 42 U.S.C. §§ 300h(a)(1),(b)(1).] 

[FN9: Id. § 300h(b)(1)(A).] 

[FN10: Id. § 300h(b)(1)(B).] 

[FN11: Id. § 300h(d)(2).] 

[FN12: 42 U.S.C. § 300f(6).] 

[FN13: 42 U.S.C. § 300h(b)(1)(A), (B).] 

[FN14: See also NRDC v. EPA, 824 F.2d 1258, 1271 (1st Cir. 1987), holding that 

Congress intended the phrase "underground injection which endangers drinking 

water sources" should have the broadest applicability, and citing and quoting 

H.R. Rep. No. 1185, 93d Cong., 2d Sess., reprinted in 1974 U.S. Code Cong. & 

Admin. News at 6484.] 

7
Individual Response: EPA agrees that the SDWA provides the EPA with the authority to 

regulate underground injection of CO2 for GS. (42 U.S.C. 300h et seq.). Injection wells are 

regulated under SDWA’s UIC Program. Under the SDWA, the injection of any "fluid" is subject 

to the requirements of the UIC program. "Fluid" is defined under 40 CFR 144.3 as any material 

or substance which flows or moves, whether in a semisolid, liquid, sludge, gas or other form or 

state, and includes liquids, gases, and semisolids (i.e., slurries) injected into the subsurface. 

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. 

EPA acknowledges that carbon crediting and greenhouse gas accounting are important issues. 

However, these issues are outside of the UIC Program's authority under the Safe Drinking Water 

Act and outside the scope of this rulemaking. The UIC requirements are designed to ensure that 

where GS is employed, it is done in a manner that protects USDWs from endangerment. All of 

the requirements of the GS rule are for the purpose of protecting USDWs from endangerment, 

consistent with the UIC Program's authority under SDWA. 

Letter ID: 0250 Comment ID: 22279 Letter Lines: 250 to 264 

Comment Code: 2020 1.5.1 Support Class VI designation 

Comment: The statute provides additional direction to EPA in developing its rules - the 

rules must "permit or provide for consideration of varying geologic, 

hydrological, or historical conditions, in different States and in different 

areas within a State," [FN15] and they are not to "interfere with or impede" 

underground injections for the purposes of "the secondary or tertiary recovery 

of oil or natural gas, unless such requirements are essential to assure that 

underground sources of drinking water will not be endangered by such injection." 

[FN16] While EPA is not free to exempt a particular class of injection entirely 

from rulemaking, the Agency is authorized to tailor the UIC rules to the 

specific geologic conditions and also to particular injection activities. The 

statute clearly authorizes EPA to create a new class or classes of UIC wells for 

the purpose of CO2 sequestration. 

8
[FN15: 42 U.S.C. § 300h(b)(3)(A).] 

[FN16: Id. § 300h(b)(2)(B).] 

Individual Response: EPA agrees that the final GS rulemaking, which creates a new class of 

well, is absolutely within the Agency’s authority provided under the SDWA. EPA agrees that 

tailored requirements for Class VI wells are necessary to address the unique nature of injecting 

large volumes of CO2 and to ensure that USDWs are protected from endangerment. The GS rule 

contains tailored requirements for the permitting, geologic site characterization, AoR and 

corrective action, well construction, operation, mechanical integrity testing, monitoring, well 

plugging, post-injection site care, and site closure of GS wells that directly address issues unique 

to the nature of large-scale CO2 injection for GS. 

Letter ID: 0250 Comment ID: 22280 Letter Lines: 266 to 284 

Comment Code: 2400 1.8 Comments on EPA's adaptive rulemaking process 

Comment: This precautionary, forward looking statutory purpose and structure authorizes 

EPA also to take an adaptive approach, both in rulemaking and in defining permit 

terms, specifically to direct states to be adaptive in monitoring, tracking, and 

updating permits, in order to reflect lessons learned from experience and from 

monitoring reports. The statute also authorizes EPA to take an adaptive approach 

to the rules themselves. Section 1421(a)(1) states that "any regulation 

[governing underground injection activities] may be amended from time to time." 

[FN17] Whereas, as is the case with EPA’s proposed Class VI rules, regulations 

are established to govern a system on a scale of deployment that has not yet 

been demonstrated [FN18], the preventive and precautionary nature of the UIC statute 

demands a periodic review, assessment, and update of the rule. EPA should, in 

its final rule, declare its intention to undertake such a process. Moreover, our 

Environmental NGO Group recommends that EPA commit itself to issuing a Notice of 

Proposed Rulemaking by no later than an identified date, perhaps in 2020, which 

would formally initiate this process. 

[FN17: 42 U.S.C. § 300h(a)(1).] 

[FN18: Although the practice of injection/GS has been demonstrated at the 

individual project scale.] 

Individual Response: EPA agrees that an adaptive approach to the UIC GS rulemaking is 

appropriate. However, the Agency does not feel that in order to use such as approach they need 

to commit to a date for a proposed rulemaking. The Agency plans to use an adaptive approach to 

ensure that USDWs are protected from endangerment and meet the potentially fast pace of GS 

deployment. EPA believes that an adaptive approach will allow regulatory development to 

proceed in time to meet the current and future demand for Class VI permits while recognizing 

the need to: continue to gather data from pilot projects and other research as it becomes 

available; and to enhance understanding of the technical and administrative aspects of GS 

deployment, operation, and technology developments. 

9
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: 0250 Comment ID: 22281 Letter Lines: 286 to 320 

Comment Code: 1420 1.2.1.1 Support the GS rulemaking 

Comment: C. The Proposed Rule Has Many Positive Features 

Before offering comments on the proposal itself, we want to praise and lend our 

support to EPA for incorporating, or in some cases intending to incorporate, a 

number of features of the rule that we regard not solely as desirable, but 

essential. These include: 

• specific requirements for a comprehensive characterization before deeming a 

sequestration site as appropriate for injection; 

• monitoring requirements for tracking the behavior and location of CO2 in the 

subsurface, validating its confinement, or detecting unwanted behavior early to 

allow for corrective action; 

• the need to compile a monitoring plan, a site care and closure plan and a 

remedial response plan prior to obtaining a permit; 

• the requirement to update and report on these plans, including the area of 

review adjustment process, as monitoring and operational data become available; 

• a requirement for a continuous feedback loop between monitoring and modeling, 

whereby one updates the other in order to optimize operations and refine 

simulations; and 

• a criterion for site closure that is not based on the mere passage of a set 

number of years, but on the finding that drinking water is not endangered and 

that the project meets the necessary performance standards (we note, however, 

that articulation of the performance standards that need to be met in order to 

make such a finding is one of the areas where the rule needs work). 

These features are captured to differing extents by the proposed rule’s 

language, and our suggested changes below serve to reinforce these features. 

Some of these features appropriately go beyond what is currently required under 

existing well classes in the UIC program. We regard them as necessary for the 

effective regulation of GS in the Class VI context, and strongly support them. 

We would therefore label our proposed changes as technical modifications, and 

not radical changes in the rule. Even though these strengthening changes are 

needed, we urge EPA to maintain the basic structure of the rule as proposed and 

thank the drafting working group for producing the proposed rule in a short 

timeframe. 

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 

10
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 

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. For additional 

information, please also see the discussion of EPA’s Final Regulatory Approach in the preamble 

to the final GS rule. 

Letter ID: 0250 Comment ID: 22282 Letter Lines: 322 to 338 

Comment Code: 1200 1.1 General comments about the rulemaking 

Comment Code: 2020 1.5.1 Support Class VI designation 

Comment: D. General Comments 

Timing of promulgation 

The proposed rule is based on a risk management approach and is written in a way 

that should avoid unintended consequences to USDWs. It is important to bear in 

mind that CO2 injection projects can already be permitted today. While this may 

be adequate to protect USDWs in certain cases, it is in the interests of the 

public (and the regulated industry) to have a new injection class, designed from 

the outset with the particular characteristics of GS in mind, as soon as 

possible. This is necessary in order provide certainty and adequately safeguard 

public health and the environment. If the final rule incorporates changes 

concerning the adaptive nature of the rule and permits, as our Environmental NGO 

Group suggests, the Agency, and its state counterparts, will be able to deal 

with such unintended consequences to USDWs through the rule’s performancebased 

provisions, review and a possible reissuance of permits if necessary, and by 

revising the rule text if appropriate. 

Individual Response: EPA agrees that the tailored requirements for Class VI wells, pursuant to 

the final GS rulemaking, are necessary to address the unique nature of injecting large volumes of 

CO2 and to ensure that USDWs are protected from endangerment, and that a new well Class 

specific to GS is appropriate. The GS rule contains tailored requirements for the permitting, 

geologic site characterization, AoR and corrective action, well construction, operation, 

mechanical integrity testing, monitoring, well plugging, post-injection site care, and site closure 

of GS wells that directly address issues unique to the nature of large-scale CO2 injection for GS. 

EPA adds that it continues to monitor research being conducted on GS and will use this to 

inform its adaptive rulemaking approach. 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. 

11
Letter ID: 0250 Comment ID: 22283 Letter Lines: 340 to 356 

Comment Code: 1200 1.1 General comments about the rulemaking 

Comment Code: 1640 1.3.4 CERCLA issues (seeking comment) 

Comment Code: 2020 1.5.1 Support Class VI designation 

Comment: We consider the Phase III Deployment Phase of the Department of Energy’s (DOE) 

Regional Partnership Program to be very worthwhile, but we do not consider the 

completion of this program to be a prerequisite for either commercial 

implementation of CCS or for the promulgation of a sound and protective rule. 

The DOE’s program has limited funds available through appropriations, and its 

demonstration projects will be of limited scale and duration. In addition, it 

focuses as much or more on the optimum way to apply existing technologies as it 

does on fundamental research or even demonstrations that particular technologies 

"work." Our scientific and practical understanding and experience in GS itself, 

as well as in related underground injection activities, is sufficient to 

construct and operate the first large-scale, commercial plants in the U.S., 

provided they are regulated adequately. In that respect, we do not consider the 

proposed rule premature, but a very timely and necessary development. 

The rule itself, rather than individual permits, should assure that Class VI 

permits do not allow responsible parties to avoid CERCLA liability on grounds 

that a release constitutes a "federally permitted release" 

Individual Response: EPA agrees that tailored requirements for Class VI wells are necessary to 

address the unique nature of injecting large volumes of CO2 and to ensure that USDWs are 

protected from endangerment. The GS rule contains tailored requirements for the permitting, 

geologic site characterization, AoR and corrective action, well construction, operation, 

mechanical integrity testing, monitoring, well plugging, post-injection site care, and site closure 

of GS wells that directly address issues unique to the nature of large-scale CO2 injection for GS. 

EPA believes, as supported by the rule's administrative record, that sufficient data and 

experience currently exist to develop UIC regulations for GS wells. The GS rulemaking builds 

upon decades of knowledge about safe injection practices. While developing the GS regulation, 

EPA has evaluated relevant GS research, including projects conducted by the seven regional 

carbon sequestration partnerships funded by the U.S. Department of Energy and coordinated 

through the National Energy Technology Laboratory (NETL), and several international projects. 

Additionally, EPA's Office of Water continues to fund research at the Lawrence Berkeley 

National Laboratory examining the effects of CO2 interaction with ground water aquifers and 

any potential mobilization of trace elements that may occur. 

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). Therefore, 

Class VI requirements and permits will need to be carefully structured to ensure that they do not 

'authorize' inappropriate releases, and would need to prevent potential releases from the well 

12
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. 

The UIC program Director has authority under SDWA §1423 to address potential compliance 

issues (e.g., potential releases that may endanger USDWs) resulting from injection violations in 

the unlikely event that a 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. 

Regarding long term liability, 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 operator will generally no longer be subject to 

enforcement for regulatory noncompliance. Furthermore, their financial instrument as required 

under §146.85 will be released if it was not 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 for regulatory noncompliance even after site closure was approved if the Director 

relied on erroneous information (e.g., erroneous modeling data) provided by the owner or 

operator when approving site closure. 

Separate from EPA's authority to enforce regulatory compliance, an owner or operator may be 

subject to a §1431 response order even after proper site closure is approved under §146.93. 

Under §1431 the Administrator may require an owner or operator to take necessary response 

measures if he or she receives information that a contaminant is present or is likely to enter a 

public water system or an USDW, which may present an imminent and substantial endangerment 

to the health of persons, and the appropriate State and local authorities have not acted to protect 

the health of such persons. The action may include issuing administrative orders or commencing 

a civil action for appropriate relief against the owner or operator of a Class VI well. If the owner 

or operator fails to comply with the order, they may be subject to a civil penalty for each day in 

which such violation occurs or failure to comply continues. 

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. 

EPA recognizes the significant amount of data generated by the DOE partnerships and agrees 

that sufficient data have been collected to inform the final GS rule. EPA has evaluated permits 

and reviewed operational data and information associated with the seven regional carbon 

sequestration partnerships funded by the U.S. Department of Energy and coordinated through the 

13
National Energy Technology Laboratory. EPA believes that these projects form a solid basis for 

finalizing the GS requirements, and agrees there is no reason to wait until all phases of the DOE 

demonstration tests are complete. 

Letter ID: 0250 Comment ID: 22284 Letter Lines: 358 to 368 

Comment Code: 1640 1.3.4 CERCLA issues (seeking comment) 

Comment: EPA notes in the preamble to the proposed rule (73 Fed. Reg. 43504) that CERCLA 

exempts from liability certain "federally permitted releases, including releases 

in compliance with a UIC permit under the Safe Drinking Water Act." EPA further 

notes that "Class VI requirements and permits will need to be carefully 

structured to ensure that they do not ‘authorize’ inappropriate hazardous 

releases." Our Environmental NGO Group strongly urges EPA to go further and 

effectively prohibit Class VI permit conditions that would make the "federally 

permitted release" defense available should injected fluids or displaced 

formation fluids enter or endanger USDWs. We suggest that such a prohibition be 

added to Subpart E - Permit Conditions, or to any other section of the rule that 

EPA finds appropriate. 

Individual Response: 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). 

Therefore, Class VI requirements and permits will need to be carefully structured to ensure that 

they do not "authorize" inappropriate releases, and would need to 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. 

The UIC program Director has authority under SDWA §1423 to address potential compliance 

issues (e.g., potential releases that may endanger USDWs) resulting from injection violations in 

the unlikely event that a 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. 

Regarding long term liability, 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 operator will generally no longer be subject to 

enforcement for regulatory noncompliance. Furthermore, their financial instrument as required 

under §146.85 will be released if it was not 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 for regulatory noncompliance even after site closure was approved if the Director 

relied on erroneous information (e.g., erroneous modeling data) provided by the owner or 

14
operator when approving site closure. 

Separate from EPA's authority to enforce regulatory compliance, an owner or operator may be 

subject to a §1431 response order even after proper site closure is approved under §146.93. 

Under §1431 the Administrator may require an owner or operator to take necessary response 

measures if he or she receives information that a contaminant is present or is likely to enter a 

public water system or an USDW, which may present an imminent and substantial endangerment 

to the health of persons, and the appropriate State and local authorities have not acted to protect 

the health of such persons. The action may include issuing administrative orders or commencing 

a civil action for appropriate relief against the owner or operator of a Class VI well. If the owner 

or operator fails to comply with the order, they may be subject to a civil penalty for each day in 

which such violation occurs or failure to comply continues. 

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. 

EPA recognizes the significant amount of data generated by the DOE partnerships and agrees 

that sufficient data have been collected to inform the final GS rule. EPA has evaluated permits 

and reviewed operational data and information associated with the seven regional carbon 

sequestration partnerships funded by the U.S. Department of Energy and coordinated through the 

National Energy Technology Laboratory. EPA believes that these projects form a solid basis for 

finalizing the GS requirements, and agrees there is no reason to wait until all phases of the DOE 

demonstration tests are complete. 

Letter ID: 0250 Comment ID: 22285 Letter Lines: 370 to 391 

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

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

Comment: The rule should incorporate a "non-interference principle" to keep one 

sequestration project from interfering with the effectiveness of another 

As EPA notes in the preamble (page 43506), "it is ... possible that multiple 

owners or operators will be injecting CO2 into formations that are hydraulically 

connected and thus the elevated pressure zones may intersect or interfere with 

each other." Our Environmental NGO Group agrees that this is a genuine 

possibility at this stage in GS implementation. Until comprehensive approaches 

to basin-scale management are developed, we urge the adoption of the following 

addition to §146.94: 

"(e) If an owner or operator obtains evidence that a pressure front associated 

with one geologic sequestration project intersects or threatens to intersect a 

15
pressure front associated with any other project, the owner or operator 

obtaining such evidence must notify the Director and the other owner or 

operator. If the Director determines that the pressure front associated with one 

project interferes or threatens to interfere with the ability of a project that 

began operations at an earlier date to sequester the earlier project’s total 

anticipated volume of the carbon dioxide stream as determined under §146.83(a), 

the Director may require the owner or operator of the project that began 

operations at a later date to modify operations as necessary to avoid such 

interference." 

Individual Response: EPA agrees with the commenter that there are a variety of factors that 

may affect the need for emergency and remedial response at GS sites. EPA believes that the GS 

Rule adequately protects USDWs from being endangered by multiple wells. EPA has decided 

not to adopt the commenter’s edit. However, the Agency believes that a site-specific emergency 

and remedial response plan that is informed by required site characterization data (per §146.82), 

modeling for AoR evaluations and reevaluations (per §146.84), and monitoring data (per 

§146.90) will appropriately address commenter concerns regarding the potential impacts of 

multiple GS projects. EPA has added a requirement at §146.94(d) that owners or operators must 

review their emergency and remedial response plan within one year of an AoR reevaluation 

required under §146.84 or following significant changes to the facility. Subsequently, the owners 

or operators must submit an amended plan or demonstrate to the Director that no amendment to 

the plan is needed based on the AoR reevaluation or any significant changes made to the facility. 

EPA also encourages owners or operators and permitting authorities to communicate planned GS 

activities during initial permitting activities to maximize coordination and minimize pressure 

interference. If a permit applicant (or the permitting authority) is aware of pending GS projects 

near a proposed well, the AoR delineation performed pursuant to §146.84 should account for the 

impacts of multiple owners and operators injecting within a single basin. EPA expects that, 

where multiple operators are involved, the Director will not approve modeling that does not 

account for changes that may result from all injection operations. 

EPA expects that changes within the AoR, such as the addition of new wells or projects that 

could potentially interfere with a GS project, will be identified as part of the AoR reevaluations 

required at §146.84(e) and would need to be addressed in a revised emergency and remedial 

response plan. EPA is developing guidance on the development and implementation of project 

plans for GS sites, including emergency and remedial response plans. 

Letter ID: 0250 Comment ID: 22286 Letter Lines: 393 to 402 

Comment Code: 1200 1.1 General comments about the rulemaking 

Comment: Process for permit review by experts 

We recommend that EPA consider establishing a process to collect input from 

experts to help inform EPA and states on evolving GS technology and appropriate 

policy and regulatory responses. Participants in the process should be 

16
independent, non-partisan, unbiased experts in the field, We recommend that the 

participants not be convened under the Federal Advisory Committee Act. Their 

opinions would be non-binding. Obtaining such input would help regulators 

improve their permitting decisions and would be complementary to the objectives 

of increased funding and resources for the UIC Program, outlined below. 

Individual Response: The final rule is based on the most recent GS-related data, information, 

and scientific research available. EPA believes that sufficient data have been collected to inform 

the final GS rule. Nevertheless, EPA anticipates that future experimental and full-scale projects 

will continue to inform the technology, and is therefore using an adaptive rulemaking approach. 

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. 

Please see the remainder of EPA's responses to this comment letter for further details. For 

additional information on EPA's final regulatory approach, including the discussion of the public 

participation requirements, please see the final rule and preamble as well as the rulemaking 

docket. 

Letter ID: 0250 Comment ID: 22287 Letter Lines: 404 to 433 

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

Comment: Funding and resources for the UIC Program 

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 

ensuring careful scientific review as well as an efficient processing time, they 

will require additional trained staff and other resources. 

Significant additional resources will need to be made available to hire new 

permitting staff and field inspectors. Those new staff, along with existing UIC 

staff, must be trained in subjects that will enable them to make prudent 

permitting, management, and oversight decisions. EPA and states will need to be 

adequately prepared to review applications and make permitting decisions. 

Failure to provide sufficient resources will likely create permitting backlogs 

or result in suboptimal permits being issued. 

The Ground Water Protection Council (GWPC) estimated in 2004 that an annual 

17
funding increase to $56 million would be needed just to meet the needs of the 

existing UIC program at the state level even without the addition of GS project 

permitting.[FN19] GWPC has further estimated that EPA will need to provide 

funding at a level of $100 million annually to meet the needs for the full UIC 

program, including the regulation of geologic sequestration. 

[FN19: GWPC, Class V Resource Needs Survey, Summary (September 2004).] 

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. 

Letter ID: 0250 Comment ID: 22288 Letter Lines: 435 to 453 

Comment Code: 5520 2.10.1 Appropriateness of existing public participation requirements 

(Part 25 and Part 124) for GS (seeking comment) 

Comment: Public Water Systems should receive notice of permit applications and have the 

opportunity to participate in the permitting process 

EPA should adopt the existing requirements for public participation at 40 CFR 

Part 25 and 40 CFR Part 124 as suggested in the proposal. UIC Program Directors 

should also incorporate modern communication technologies (cable television, 

various internet tools) to increase the likelihood of effective public 

understanding and involvement. Engaging the public as soon as candidate 

locations are identified will also increase the effectiveness of the effort. 

Given the focus of the rule on preventing harm to USDWs, UIC Program Directors 

should work with primacy agencies and departments with responsibility for 

implementing other aspects of SDWA to identify and notify Public Water Systems 

(PWSs) with a potential interest in the project. PWSs are an important 

stakeholder in the projects and should be the focus of targeted outreach at 

every stage of the permitting process. PWS representatives should be invited to 

serve on any Advisory Groups or other bodies set up during the lifetime of the 

project. We suggest that in Guidance to accompany this rulemaking, EPA urge 

owners and operators to establish on-going relationships with potentially 

impacted PWSs. 

Individual Response: EPA agrees and has adopted the existing public participation 

requirements at 40 CFR Part 25 and 40 CFR Part 124. EPA encourages but does not require 

18
operators and permitting agencies to begin involving the public by providing information as 

early in the GS project development process as possible. Furthermore, the Agency recognizes 

that the initial phases of site evaluation and site selection may begin in advance of permit 

application submission. The public may become aware of these activities and begin to have 

questions or concerns about the pending project. For this reason, outreach and education—which 

are outside of, but complementary to, the public notification process—can help clarify project 

details and avoid public misperceptions about the nature and safety of GS projects. This may also 

benefit the owner or operator by improving local acceptance of the site. The public will also have 

the opportunity to submit written comments and, in many cases, attend hearings if requested on 

proposed GS projects during formal public comment periods. Permitting authorities must follow 

the public participation requirements for UIC permits specified in 40 CFR Part 124.10 which 

generally requires that the public notice include information about where interested parties can 

obtain copies of the draft permit and application. In addition, the existing public participation 

requirements for UIC permits at 40 CFR 124.10(c)(1)(x)(A) require notification "to any unit of 

local government having jurisdiction over the area where the facility is proposed to be located." 

In addition, the final rule now requires notification of the director of the state public water supply 

supervision program (drinking water program) of the availability of the draft Class VI permit. 

See 40 CFR §124.10(c)(1)(xi). EPA anticipates that the Director of the drinking water program 

will inform public water systems located within the proposed area of review about the permit 

application. 

EPA agrees with commenters that the use of new forms of information technology can improve 

public participation and understanding of GS projects and the associated injection technologies 

involved. EPA does not require the use of any new information technologies to inform the 

public, but encourages GS project operators and permitting authorities to use the Internet as well 

as both new and established tools to explain and post information on the latest developments. 

This information may include schedules for hearings, briefings, and other opportunities for 

involvement. EPA plans to conduct outreach on the GS rule, and provides GS related 

information on its website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. 

EPA currently uses social networking applications for important information (e.g., Facebook and 

Twitter), and will encourage GS operators and permitting authorities to use similar technologies 

to keep the public informed of GS projects. 

Letter ID: 0250 Comment ID: 22289 Letter Lines: 455 to 466 

Comment Code: 4110 2.4.1.1 Injection pressure limitations 

Comment: Pressure limits 

We believe that the pressure management provisions in §146.88(a) require 

modification. The members of our Environmental NGO Group have not reached 

agreement on the exact language for the suggested changes and are either 

submitting individual comments on this issue or are submitting comments jointly 

with other groups. We do agree, however, that injection pressure limits must be 

established after adequately considering the risks of both tensile failure and 

19
shear failure in the confining zone. We also agree that limits must be designed 

to avoid causing otherwise non-transmissive faults to become transmissive, in 

addition to addressing the more traditional concern of avoiding the initiation 

or propagation of fractures. 

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: 0250 Comment ID: 22290 Letter Lines: 468 to 487 

Comment Code: 5220 2.8.2.1 Post-injection monitoring activities 

Comment: Site closure standards and framework for long-term stewardship 

Our Environmental NGO Group did not come to a common set of recommendations on 

site closure and are either submitting individual comments on this issue or are 

submitting comments jointly with other groups. We do agree, however, that EPA’s 

20
proposed closure standards in §146.93 need revision. In order to assure that 

site risks have diminished to the point that it is reasonable to discontinue or 

significantly reduce monitoring, it is essential that the rule require a 

demonstration of much more than merely ‘plume stabilization’ and that the nature 

of what must be demonstrated be precisely described. In addition, given the 

desired permanent nature of CO2 sequestration in the subsurface and the 

importance to the public of ensuring long-term oversight of project sites, EPA 

should use its existing regulatory authorities to establish a framework for 

long-term stewardship and seek whatever additional authorities may be required 

for this purpose from Congress. This framework should include an entity with 

responsibility for monitoring and managing sites after closure has been 

authorized. The proposed rule authorizes operators to stop monitoring, but does 

not provide for the stewardship of sites following closure.. EPA must rectify 

this omission. It is important that the post-closure framework include financing 

provisions that are adequate to ensure proper site stewardship in the long-term. 

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 individual UIC 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 required. 

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. 

Regarding establishing a framework for long-term stewardship, EPA clarifies that, once site 

closure is authorized, the UIC program has no authority over a site. EPA clarifies that long-term 

liability for GS sites is outside the scope of this rulemaking after a the CO2 plume has been 

demonstrated to no longer pose an endangerment to USDWs and the site has been properly 

closed pursuant to §146.93. 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 operator will generally no longer be subject to enforcement for 

regulatory noncompliance. 

Separate from EPA’s authority to enforce regulatory compliance, an owner or operator may be 

21
subject to a §1431 response order even after proper site closure is approved under §146.93. 

Under §1431 the Administrator may require an owner or operator to take necessary response 

measures if he or she receives information that a contaminant is present or is likely to enter a 

public water system or an USDW, which may present an imminent and substantial endangerment 

to the health of persons, and the appropriate State and local authorities have not acted to protect 

the health of such persons. The action may include issuing administrative orders or commencing 

a civil action for appropriate relief against the owner or operator of a Class VI well. If the owner 

or operator fails to comply with the order, they may be subject to a civil penalty for each day in 

which such violation occurs or failure to comply continues. 

Letter ID: 0250 Comment ID: 22291 Letter Lines: 489 to 502 

Comment Code: 5700 2.12 Comments on the proposed duration of Class VI permits (seeking 

comment) 

Comment: E. Specific Amendments to the Proposed Rule 

The rule should authorize Class VI permits for "up to" the operating life of a 

facility only if the rule is amended to require all aspects of project 

operations to be modified as appropriate over the course of the project 

We support EPA’s proposal in §144.36 to issue Class VI well permits for a period 

"up to" the operating life of the facility. Still, it is not appropriate to 

issue these permits for the full operating life of the facility without 

consideration how project performance is evolving. Revisions of the Area of 

Review, and the various plans outlined in the proposed rule are to be expected 

from time to time, and it is possible that some of the needed revisions might be 

so material so as to constitute ground for modification, revocation or 

reissuance of the permit. 

Individual Response: EPA appreciates the commenter’s concern and believes that the final rule 

addresses this concern about adaptability. The final rule maintains the lifetime permit provision 

and clarifies that the permit extends through the post-injection site care period (144.36(a)). It also 

adds a requirement that the Director review each Class VI permit at least once every 5 years to 

determine whether it should be modified, revoked and reissued, terminated or a minor 

modification made as provided in §§144.39, 144.40, or 144.41. The Director’s review will be 

informed by the owners’ or operators’ iterative reevaluation of the project. Specifically, the final 

rule includes a requirement that the AoR be reevaluated at least every five years, and also 

requires owners or operators to review and update the AoR and corrective action plan, the testing 

and monitoring plan, and the emergency and remedial response plan throughout the life of the 

project (146.84(e), 146.90(j), and 146.94(d)). Owners or operators must review each plan and 

identify necessary amendments or demonstrate to the Director that no amendment is needed. In 

no case can reviews occur less often than once every five years. The iterative process and 

subsequent plan reevaluations ensure that time and resources are committed to the most critical 

aspects of the permit in preventing endangerment to USDWs. 

22
EPA believes that the iterative process of developing and executing the various plans required of 

GS well operators in the final rule (e.g., for AoR and corrective action, testing and monitoring, 

injection well plugging, post-injection site care, and emergency and remedial response) is 

tailored to the unique aspects of—and is more appropriate for–GS than establishing a finite 

permit duration (e.g., ten years as suggested by some commenters). 

EPA emphasizes that the Director has the authority to revise the permit if project operations 

change or if the director believes based on monitoring or operational data that the project may 

endanger USDWs. EPA has also added text to 144.39(a)(5) that permit modifications would be 

required if the Director determines that a modification is necessary based on an AoR 

reevaluation, amendments to any of the project plans, or a review of the testing and monitoring 

results. The Director may also choose to require minor permit modifications under 40 CFR 

144.41, depending on the extent of the plan amendment. All permit modifications, except minor 

modifications under 40 CFR 144.41, require an opportunity for public comment on the portion of 

the permit that is being reopened pursuant to requirements under 40 CFR Part 124. 

The Agency plans to collect and review data on GS projects every six years 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: 0250 Comment ID: 22292 Letter Lines: 504 to 514 

Comment Code: 2000 1.5 Need for a New Class of Injection Well 

Comment: Class VI is appropriately grouped with Class I Hazardous, Class II and Class III 

wells in the modification or revocation and reissuance provisions 

We believe that EPA in §144.39 has appropriately listed Class VI alongside other 

injection classes for which a permit can be revoked and reissued for a specific 

cause (alterations to the facility, new information received and regulatory 

changes since the permit issued. This is necessary in order to ensure that Class 

VI regulations are adaptive, reflecting experience in GS as it is amassed. We do 

not support Class VI being listed alongside classes for which the permittee has 

control over whether reissue or modification would occur through requesting or 

agreeing to it. 

Individual Response: EPA agrees the Director should have the ability to revoke and reissue a 

permit for Class VI wells and has retained this provision in the final rule. 

Letter ID: 0250 Comment ID: 22293 Letter Lines: 516 to 535 

Comment Code: 1220 1.1.1.1 Terminology and definitions 

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

Comment: The definition of "carbon dioxide stream" should not be restricted to CO2 

23
captured from industrial sources 

The definition of "carbon dioxide stream" in §146.81(b) includes only carbon 

dioxide "that has been captured from an emission source (e.g., a power plant)." 

Over time, the vast majority of sequestered CO2 is likely to be captured from 

such sources, but rules are also needed to govern the sequestration of naturally 

occurring CO2 produced from geologic formations. We suggest that the definition 

be revised to read as follows: 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf, starting on p. 

10, to see the original formatting.] 

"Carbon dioxide stream means that has been captured from an emission source 

(e.g., a power plant), carbon dioxide plus incidental associated substances 

derived from the source materials 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." 

Individual Response: EPA disagrees with the suggested edit. The final definition of carbon 

dioxide stream at §146.81(d) remains unchanged and reads as follows: “[C]arbon dioxide that 

has been captured from an emission source (e.g., a power plant), plus incidental associated 

substances derived from the source materials and 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.” 

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

and Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the 

final rule and preamble for additional information. 

Letter ID: 0250 Comment ID: 22294 Letter Lines: 537 to 538 

Comment Code: 3200 2.2 Proposed Area of Review and Corrective Action Requirements (40 

CFR 146.84) 

Comment: Class VI applicants should be required to identify all known wells penetrating 

formations affected by increased pressure 

Individual Response: EPA clarifies that under 146.84(c)(2)operators must identify all 

penetrations of the confining zone in the AoR for the GS project. This area would encompass 

both the CO2 plume and areas of increased pressure associated with CO2 injection, regardless of 

which is larger. 

24
Letter ID: 0250 Comment ID: 22295 Letter Lines: 540 to 569 

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

Comment Code: 3440 2.2.2.2 Evaluation of wells in the AoR (e.g., types of data to be 

reviewed) 

Comment: In proposed §144.55(a) the rule would require Class I, II (other than existing), 

III or VI permit applicants to identify the location "of all known wells within 

the injection well’s area of review which penetrate the injection zone" or, in 

the case of Class II wells operating over the fracture pressure of the injection 

formation, "all known wells within the area of review penetrating formations 

affected by the increase in pressure". 

Since injection in deep saline formations will result in an area of elevated 

pressure (above the original reservoir pressure) that will be larger than the 

CO2 plume and could affect overlying or underlying formations, we believe that 

the latter requirement for Class II wells operating above the fracture pressure 

should also apply to Class VI wells. This would help prevent the unwanted 

migration of reservoir fluids from outside the injection zone through existing 

wells in the confining zone, as a result of the pressure increase. We therefore 

suggest that §144.55(a) be revised to read as follows: 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Coverage. Applicants for Class I, II, (other than existing), or III, or VI 

injection well permits shall identify the location of all known wells within the 

injection well's area of review which penetrate the injection zone. In the case 

of Class II wells operating over the fracture pressure of the injection 

formation, applicants shall identify the location of all known wells within the 

area of review penetrating formations affected by the increase in pressure. 

Applicants for Class VI SHALL IDENTIFY THE LOCATION OF ALL KNOWN WELLS 

WITHIN 

THE AREA OF REVIEW PENETRATING THE INJECTION ZONE AND ALL KNOWN 

WELLS WHICH 

PENETRATE FORMATIONS AFFECTED BY THE INCREASE IN PRESSURE AND shall 

perform 

corrective action as specified in Sec. 146.84." 

Individual Response: The final rule leaves §144.55 unchanged; i.e., Class VI wells are not 

addressed in this provision. 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 preamble for further discussion on EPA's final approach. 

25
Letter ID: 0250 Comment ID: 22296 Letter Lines: 571 to 614 

Comment Code: 2160 1.6.3 Unmineable coal seams 

Comment Code: 2200 1.6.4 Other formation types 

Comment: The rule should explicitly exclude from Class VI efforts to sequester CO2 in 

basalts, coal seams, salt caverns and shales, which instead should be regulated 

under Class V Experimental 

We believe that EPA has ample basis for adopting rules to regulate geologic 

sequestration in hydrocarbon reservoirs and in deep brine formations. For these 

types of geologic formations, there is a widespread technical consensus on how 

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

select sites, how to conduct injection operations, how to model the behavior of 

CO2 in the reservoir, and how to monitor project performance. There is no such 

consensus, however, regarding 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 to those in deep saline 

formations and hydrocarbon reservoirs, and using identical regulatory language 

would be ill advised. In fact, it is not known at this time whether 

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

such formations - efforts in these formations are very much still in the 

experimental stage. There is no basis at this time for determining whether rules 

that are appropriate for wells in hydrocarbon reservoirs and deep saline 

formations are also appropriate for wells in these other formations. 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 wells under Class V. 

Projects designed to evaluate injection in coal seams, salt caverns and shales 

should be permitted under the UIC Class V provisions and subject to the March 

2007 Guidance on "Using the Class V Experimental Technology Well Classification 

for Pilot GS Projects. [FN20] This Guidance clearly states that Class V is 

intended only for projects "...designed to evaluate the technical issues 

associated with CO2 injection" [FN21]. The Director should review all Class V GS 

permit applications to insure that they meet the definition of Pilot Project in 

CFR 146.3: "... a technology which has not proven feasible under the conditions 

in which it is being tested." The purpose of such pilot projects should be to 

gather and share information which will lead to a clearer understanding of the 

feasibility of such projects on a commercial scale. 

[FN20: UICPG#83] 

[FN21: Id. at p. 1] 

In order to implement our suggestion regarding these formations, we recommend 

revising sections 144.6(f), 144.80(f), 146.5(f) and the definition of 

26
sequestration in §146.81 accordingly. We suggest retaining the provision in 

proposed §144.15 that the construction, operation or maintenance of any nonexperimental Class V geologic sequestration well is prohibited. 

Individual Response: EPA acknowledges that site-suitability for GS is dependent on a number 

of factors and that many formation types may be suitable for GS. The final GS rule does not 

preclude injection into any formation type provided owners or operators can demonstrate that GS 

can be performed in a manner that protects USDWs from endangerment. The Agency 

acknowledges that GS into basalts, coal seams, salt domes, shales, limestone formations, and 

fractured karst will likely have limited application, or that owners or operators seeking Class VI 

permits for injection into these formations may not be able to meet the final GS requirements or 

demonstrate protection of USDWs. 

EPA acknowledges that there may be risks associated with GS, particularly regarding GS into 

basalts, which have been the subject of limited experimental projects in the past. EPA anticipates 

that in the short-term, GS into basalts, coal seams, salt domes, shales, limestone formations, and 

fractured karst will continue to be experimental in nature (i.e., if they are to test GS technologies 

and collect data), and will likely be permitted as Class V experimental technology wells and be 

subject to UIC Program Guidance #83. EPA will continue to review data on early GS projects, 

including those in such formations, to determine whether the appropriate amount and types of 

information and documentation are required and being collected. 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: 0250 Comment ID: 22297 Letter Lines: 616 to 618 

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

USDW 

Comment: The rule should not prohibit in a blanket fashion GS sites located above the 

lowermost USDW, but should permit such sites only under certain conditions that 

are not applicable to sites below the lowermost USDW 

Individual Response: EPA acknowledges that there are limited circumstances where injection 

above the lowermost USDW can be performed in a manner that protects USDWs from 

endangerment, as long as appropriate protections are in place. The final GS rule at §146.95 

establishes a process by which 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. 

Additionally, the final GS rule does not categorically preclude or prohibit injection into any type 

of formation. 

EPA believes that these requirements will ensure USDW protection while providing flexibility to 

UIC program Directors and owners or operators who undertake CO2 injection for GS. The 

Agency believes this 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 

27
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. 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: 0250 Comment ID: 22298 Letter Lines: 620 to 638 

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

USDWs in certain circumstances 

Comment: We believe that GS sites located above lowermost USDWs may or may not present 

more types of risk than sites located below lowermost USDWs, but that in any 

event the consequences of leakage from sites above USDWs are likely to be more 

significant in the event that leakage occurs. At the same time, we recognize 

that there many potentially excellent sequestration sites above USDWs and that 

in some areas these may be the only sites available. We believe the rule should 

authorize GS sites above lowermost USDWs only if such sites meet requirements 

that go beyond what is mandatory for other sites. The following additional 

conditions would need to be satisfied: 

• confirmation that there is a confining zone underlying the entire base of the 

injection zone; 

• mandatory monitoring for changes in groundwater chemistry above the upper 

confining zone and below the lower confining zone; and 

• prior to permit issuance, and as a condition of 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. 

Individual Response: EPA agrees that there are limited circumstances where injection above the 

lowermost USDW can be performed in a manner that protects USDWs from endangerment, as 

long as appropriate protections are in place. The final GS rule at §146.95 establishes a process by 

which 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. 

It establishes requirements specifying information that owners or operators must submit, and 

Directors must consider (including the presence of confining zones above and below the 

injection zone and detailed hydrologic evaluation of the proposed site), in consultation with 

PWSS Directors. Owners or operators of Class VI wells granted a waiver of the injection depth 

requirements are subject to additional requirements (e.g., ground water monitoring above and 

28
below the injection zone) to ensure USDW protection above and below the injection zone. 

EPA believes that these requirements will ensure USDW protection while providing flexibility to 

UIC program Directors and owners or operators who undertake CO2 injection for GS. The 

Agency believes this 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. 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: 0250 Comment ID: 22299 Letter Lines: 640 to 664 

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

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

Comment: Emergency and remedial response, including response to potential problems 

relating to geologic features, is a necessary complement to corrective action 

and should remain in the rule. While wells are the most likely conduits for fluid 

movement into USDWs, the definition of corrective action and the relevant 

provisions in §146.84 do not take into account the potential for geologic 

features, such as faults, spill points or fractures, to act as conduits for CO2 

or other fluid migration, and hence breach of confinement. Actions to mitigate 

or remediate a potential breach of confinement, or a situation which might 

eventually lead to a breach of confinement, should not be limited to corrective 

action on wells. We therefore strongly support EPA’s inclusion of the Emergency 

and remedial response section. We propose two minor changes - change §146.94(b) 

(4) to read: 

[In the paragraphs below the text in all CAPS denotes added text. See also EPA-HQ-OW-0390-

0250.pdf to see the 

original formatting.] 

"Implement the emergency and remedial response plan approved by the 

Director, AND KEEP HIM APPRIZED OF THE IMPLEMENTATION." 

and §146.94(d) to read: 

"The owner or operator must notify the Director and obtain his approval prior to 

conducting any well workover OR OTHER REMEDIATION MEASURES NOT LISTED IN 

THE 

29
EMERGENCY AND REMEDIAL RESPONSE PLAN." 

Individual Response: The final rule keeps the language in §146.94(b)(4) as proposed. EPA 

agrees that the Director should be kept apprised of progress on the implementation of the 

emergency and remedial response plan and expects that the plan itself will include provisions on 

communications with the Director. EPA agrees that an emergency and remedial response plan is 

an important part of assuring protection of USDWs from endangerment at GS sites. The 

requirements for an emergency and remedial response plan at §146.94(a) are designed to ensure 

that owners or operators, as part of their permit applications, comprehensively plan what actions 

would be necessary in the unlikely event of an emergency. The plan will ensure that operators 

know what entities and individuals must be notified and what actions must be taken to 

expeditiously mitigate any emergency situations. EPA is developing guidance on the 

development and implementation of emergency and remedial response plans for GS sites. 

Since proposal, EPA has modified the final regulatory language at §146.94(d) to clarify what 

constitutes a workover to address a well failure (which invokes remedial actions) and what 

constitutes a maintenance-type workover. For maintenance-type workovers (i.e., those that are 

scheduled in advance), the owner or operator must notify and gain approval from the Director 

prior to beginning the workover. In the final GS regulation, EPA has moved this requirement to 

the reporting requirements at §146.91(d) to clarify its intent. 

Regarding concerns that notification could delay responses, EPA clarifies that the GS rule, at 

§146.94(b), describes procedures owners or operators must take in emergency situations. 

Specifically, upon determining that there is a problem with the well that may endanger a USDW, 

the owner or operator must first cease injection, then take all steps reasonably necessary to 

identify and characterize any release, notify the Director, and implement the approved 

emergency and remedial response plan, which may include a well workover. EPA believes that 

ceasing injection (which the owner or operator would do immediately and before notifying the 

Director) is the immediate action necessary to prevent or mitigate endangerment of USDWs as 

required under the SDWA. 

Letter ID: 0250 Comment ID: 22300 Letter Lines: 666 to 683 

Comment Code: 1220 1.1.1.1 Terminology and definitions 

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

Comment: The definition of "confining zone" should not be limited to formations overlying 

the injection zone, and should focus on limiting movement through the confining 

zone rather than out the injection zone 

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

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

strict. The definition also fails to recognize that it is movement through and 

beyond the confining zone that needs to be limited. We suggest instead that the 

definition of "confining zone" read as follows: 

30
[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Confining zone means a geologic formation, group of formations, or part of a 

formation stratigraphically overlying the injection zone that acts as a 

barrier to limit fluid movement beyond THIS FORMATION, GROUP OF FORMATIONS, OR 

PART OF A FORMATION." 

Individual Response: EPA disagrees with the suggested edit. However, the Agency has 

modified the final definition of confining zone at §146.81(d) to read as follows: “[A] geologic 

formation, group of formations, or part of a formation stratigraphically overlying the injection 

zone that acts as barrier to fluid movement. For Class VI wells operating under an injection 

depth waiver, confining zone means a geologic formation, group of formations, or part of a 

formation stratigraphically overlying and underlying the injection zone.” 

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

and Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the 

final rule and preamble for additional information. 

Letter ID: 0250 Comment ID: 22301 Letter Lines: 685 to 726 

Comment Code: 1220 1.1.1.1 Terminology and definitions 

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

Comment: The second sentence of the definition of ‘geologic sequestration project" should 

be amended to refer more generally to formation fluids and be transferred to the 

definition of "area of review" 

We suggest the following amendment to §146.81(d) in order to be more inclusive 

on the types of fluid that could be displaced: 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"[...] It includes the subsurface three-dimensional extent of the carbon dioxide 

plume, associated pressure front, and displaced brine FORMATION FLUIDS, as 

well as the surface area above that delineated region. 

We also suggest that this second sentence of the definition of geologic 

sequestration project be transferred to the definition of area of review as 

recommended above. The language provided above reflects the change from "brine" 

to "formation fluids." 

Moreover, we suggest that the present restriction of Class VI to formations 

31
below the lowermost USDW is more appropriately addressed elsewhere. Accordingly, 

we recommend that geologic sequestration project be defined as follows: 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

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

a carbon dioxide stream beneath the lowermost formation containing a USDW INTO 

AN INJECTION ZONE FOR GEOLOGIC SEQUESTRATION. It includes the subsurface threedimensional extent of the carbon dioxide plume, associated pressure front, and 

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

The term "pressure front" should be replaced with the more accurate term "area 

of elevated pressure" throughout the rule 

The term "pressure front" in 146.81(d) is likely to be scientifically inaccurate 

as it implies a front, or discontinuity in pressure, whereas in reality there 

will be a continuous pressure gradient in the formation in most cases. We 

suggest globally replacing "pressure front" with "area of elevated pressure" 

throughout the rule. 

Individual Response: EPA disagrees with the suggested edit. However, the Agency has 

modified the definition of geologic sequestration project at §146.81(d) to read as follows: 

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

dioxide stream beneath the lowermost formation containing a USDW; or, wells used for geologic 

sequestration of carbon dioxide that have been granted a waiver of the injection depth 

requirements pursuant to requirements at §146.95; or, wells used for geologic sequestration of 

carbon dioxide that have received an aquifer exemption expansion. It includes the subsurface 

three-dimensional extent of the carbon dioxide plume, associated pressure front, and displaced 

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

The final definition of pressure front at §146.81(d) also is unchanged and reads as follows: 

“[T]he zone of elevated pressure that is created by the injection of carbon dioxide into the 

subsurface. For the purposes of this subpart, the pressure front of a carbon dioxide plume refers 

to a zone where there is a pressure differential sufficient to cause the movement of injected fluids 

or formation fluids into a USDW.” 

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

and Request for Comment, EPA has made many revisions to the Class VI GS rule. Please see the 

final rule and preamble for additional information. 

Letter ID: 0250 Comment ID: 22302 Letter Lines: 728 to 751 ; 763 to 765 

Comment Code: 3420 2.2.2.1 Scope of the inventory process (e.g., reliance on publicly 

available information, depth of wells) 

32
Comment: Additional well identification methods that do not rely on the public record 

should be required in certain provisions 

§146.82(b) requires a map to be submitted with the permit that shows wells 

within the area of review - only information of public record is required to be 

included on this map. §146.82(e) requires a tabulation of all wells within the 

area of review which penetrate the injection or confining zone(s), including 

information on the well’s type, construction, date drilled, location, depth, 

record of plugging and/or completion and any additional information that the 

Director may require. 

While we are comfortable with relying on information of public record in 

subsection (b), we believe that additional diligence is needed when it comes to 

wells that penetrate the injection or confining zone in subsection (e). 

Information of public record is often incomplete and/or inaccurate. There are 

numerous orphaned or abandoned wells that are not listed on the public record 

that could potentially affect the integrity of the confining zone. While 

generally it is possible to intercept these problems during operations, there 

are methods available today to identify wells not listed on the public record 

[FN22], which in many cases could identify potentially problematic wells in 

advance. A requirement to supplement public record information with field 

measurements should be included in the rule, and described with a term that is 

broader than "tabulation" in order to allow the Director to require other data 

formats as needed: 

[FN22: NETL , for example, has developed an electromagnetic 

system that can be used for areal or ground-based identification of wells 

(casings).] 

Individual Response: EPA acknowledges that public records may not contain data on every 

artificial penetration in the AoR (or all of the data on each well that is required for the 

tabulation), particularly in areas with many older wells. However, EPA notes that the inventory 

and review process for GS wells required at §146.84(c)(2) is similar to what is required of Class 

I and Class II injection well operators, that the AoR and corrective action process for these well 

types has been successful for many years. 

EPA adds that the Director has the discretion to require the owner or operator to supplement a 

data records search, including requiring ground or airborne surveys for wells, if there is reason to 

believe, based on knowledge of the site or of available data bases, that the incompleteness of 

available information could compromise USDW protection from endangerment. EPA adds that 

all corrective action must be performed pursuant to the approved AoR and corrective action plan, 

which affords the Director the discretion to require any additional information needed (including 

information that is not publically available) to ensure that all necessary corrective action is 

performed. 

33
Letter ID: 0250 Comment ID: 22304 Letter Lines: 782 to 798 

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

Comment Code: 1616 1.3.1.3 Fluid movement 

Comment: The term "transmissive fault or fracture" should be clarified 

The proposed rule in §146.83(a)(2) requires a confining zone(s) that is free of 

transmissive faults or fractures, while §146.81 defines this term as "A fault or 

fracture that has sufficient permeability and vertical extent to allow fluids to 

move between formations". We suggest the following modification to the 

definition in §146.81(d) in order to avoid unduly restricting movement that is 

merely between formations (compare our comments above on the definition of 

"confining zone"): 

[In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

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

permeability and vertical extent to allow fluids to move between formations 

BEYOND A CONFINING ZONE." 

Individual Response: EPA has retained the definition in the final rule. While there may be 

cases, as the commenter suggests, where a transmissive fault may exist but not pose a concern 

for confinement, i.e., in the context of all other information, EPA believes the definition is 

accurate. 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 the geologic site characterization discussion in the preamble for further discussion on 

EPA's final approach. 

Letter ID: 0250 Comment ID: 22305 Letter Lines: 800 to 823 

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

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

(seeking comment) 

Comment: Secondary confining zone 

§146.83 allows the Director to require additional confining zones, at his 

discretion. We do not believe that this will always be necessary - a good 

primary zone should be sufficient. Where additional hazards justify it, a 

secondary zone might be desirable. In all cases, we caution against relying on 

secondary confinement in place of establishing with a greater degree of 

certainty the suitability of the primary zone. Potential problems are best 

identified and anticipated early, and the focus should be on site 

34
characterization to show with confidence whether the confining zones are 

adequate. We suggest striking part (b) in §146.83 as it seems redundant. 

However, the Director must have the discretion to require a secondary confining 

zone if needed. We therefore recommend clarifying part (a)(2) to read 

explicitly: 

[In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"A confining zone, or zones, that is ARE free of transmissive faults or 

fractures and of sufficient areal extent and integrity to contain the injected 

carbon dioxide stream and displaced formation fluids and allow injection at 

proposed maximum pressures and volumes without initiating or propagating 

fractures in the confining zone(s)" 

Individual Response: EPA disagrees with the suggested edit, but agrees that providing the 

Director discretion will allow consideration of a range of sites for GS, based on site-specific 

conditions and ensure USDW protection. EPA believes that requiring appropriate site 

characterization by the owner or operator (under §146.82) and providing an appropriate degree 

of flexibility to the Director to evaluate site-specific geologic data will afford the greatest 

protection of USDWs from endangerment. The Agency believes that in some geologic settings, 

the presence and identification of additional confining and containment zones above the primary 

(i.e., lowermost) confining zone can improve USDW protection. These formations could further 

impede vertical fluid movement, allow for pressure dissipation, and provide additional sites for 

monitoring, mitigation, and remediation, while also affording the greatest protection of USDWs 

from endangerment. 

Letter ID: 0250 Comment ID: 22306 Letter Lines: 825 to 831 

Comment Code: 1220 1.1.1.1 Terminology and definitions 

Comment Code: 3300 2.2.1 Delineating the AoR/Modeling CO2 movement 

Comment: The area of review provisions should be revised in several respects 

Surprisingly, the definition of "area of review" (AOR) in §146.81(d) fails to 

mention that elevated pressure a critical aspect of what it means for an area to 

be "impacted" by injection activity. Our Environmental NGO Group recommends 

borrowing language from the proposed definition of "geologic sequestration 

project" and reworking the "area of review" definition. 

Individual Response: Although EPA disagrees with the commenter's suggested change, the 

Agency has carefully considered all comments on the AoR definition at 146.84(a) and modified 

it to read as follows: The region surrounding the geologic sequestration project where USDWs 

may be endangered by the injection activity. The area of review is delineated using 

computational modeling that accounts for the physical and chemical properties of all phases of 

35
the injected CO2 stream and is based on available site characterization, monitoring, and 

operational data. EPA believes that this definition is sufficiently broad and describes both the 

intent of the computational modeling and the relationship of the AoR to areas that are subject to 

the risks associated with injection. 

Letter ID: 0250 Comment ID: 22307 Letter Lines: 833 to 854 

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

Comment Code: 3300 2.2.1 Delineating the AoR/Modeling CO2 movement 

Comment: An additional concern is that both §146.81 and §146.84(a) state that the AOR is 

"based on computational modeling". This could imply that the Area of Review 

could be based solely on computational modeling. Instead, the AOR should be 

based on computational modeling, monitoring and operational data (and kept 

updated until closure is approved). All references to computational modeling in 

relation to the Area of Review in this section, as well as in the definition of 

Area of Review in §146.81 should be amended as appropriate to read "based on 

computational modeling, as well as monitoring and other operational data." We 

urge that the definition be revised as follows: 

[In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Area of review means the AREA that may be impacted by the injection activity. 

The area of review is based on computational modeling, as well as MONITORING AND 

OTHER OPERATIONAL DATA, that account for the physical and chemical properties of 

all phases of the injected carbon dioxide stream. IT INCLUDES THE SUBSURFACE 

THREE-DIMENSIONAL EXTENT, THROUGHOUT THE OPERATING LIFE OF THE 

FACILITY, OF THE 

CARBON DIOXIDE STREAM PLUME, ASSOCIATED PRESSURE FRONT, AND 

DISPLACED FORMATION 

FLUIDS, AS WELL AS THE OVERLYING FORMATIONS AND SURFACE AREA ABOVE 

THAT 

DELINEATED REGION." 

Individual Response: Based on review of all public comments on the AoR definition at 

146.84(a), the Agency has modified it to read as follows: "The region surrounding the geologic 

sequestration project where USDWs may be endangered by the injection activity. The area of 

review is delineated using computational modeling that accounts for the physical and chemical 

properties of all phases of the injected CO2 stream and is based on available site 

characterization, monitoring, and operational data." The definition in the proposed rule 

accounted for the varying physical and chemical properties of the CO2 including free-phase and 

water-dissolved CO2, as the commenter suggests. The definition in the final rule will continue to 

do so. 

36
EPA is developing guidance on AoR and corrective action at GS Class VI sites to assist owners 

or operators and Directors in evaluating requirements and proposed AoR and corrective action 

plans under 146.84. The guidance describes EPA's recommended approaches for the data to be 

considered in an initial AoR delineation, how to apply computational modeling to delineate the 

AoR, performing corrective action at GS sites, and, when appropriate, completing AoR 

reevaluations. The guidance will be available on EPA's web site, at 

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

EPA clarifies that the initial AoR delineation required under 146.84(c) is performed prior to 

injection, and therefore no monitoring or operational data would yet exist. The AoR delineation 

models will incorporate all available site data and anticipated operating procedures (e.g., 

injection rates and volumes). 

The AoR reevaluation process required at 146.84(e) requires owners or operators to incorporate 

monitoring or operational data and make any needed adjustments to corrective action or 

monitoring at the site. EPA believes that the iterative process of AoR reevaluation is appropriate 

to verify that the CO2 plume and pressure front are moving through the subsurface as predicted, 

verify the accuracy of the delineation model (or identify needed changes), and refine testing and 

monitoring activities to ensure that USDWs are protected from endangerment and that there 

would be adequate warning of potential problems at the site before any endangerment could 

occur. 

Letter ID: 0250 Comment ID: 22308 Letter Lines: 856 to 874 

Comment Code: 3530 2.2.3.1 AoR reevaluation frequency (seeking comment) 

Comment: Even though proposed §146.84(f) requires "reevaluation" of the AOR at a 

"minimum" fixed frequency of ten years or "when operational and monitoring 

conditions warrant" (the "and" should be an "or"), §146.84 runs the risk that 

revisions will not be made on a timely basis. Default periods have a way of 

becoming the standard way of doing business. We recommend imposing a continual 

obligation on operators to assess whether the AOR should be revised, a 

requirement for an annual report stating whether circumstances during the 

preceding year warranted a revision, and a requirement that revisions be done 

when required by the Director as well as when the operator determines that 

conditions warrant. To accomplish this, it will be useful to break down the 

concept of "reevaluation" into two ideas - "assessment" of the need to revise 

the AOR and the actual process of "revision." There are several portions of 

§146.84 that will need to be changed in order to incorporate these suggestions. 

We believe that these suggestions will incentivize honest and truthful reporting 

of data and site performance while avoiding the excessive burden of "reevaluating" or revising the Area of Review if such work is not needed. Moreover, 

a continuous obligation to assess whether revisions are needed, when coupled 

with the annual reporting requirement just suggested, will create a clear 

accountability trail for both operator and Director in case of disputes. 

37
Individual Response: EPA agrees with commenters that reevaluations of the AoR every ten 

years may not be sufficient, and has changed the minimum frequency for the AoR reevaluation 

from 10 years to at least every 5 years, as specified in §146.84(e). EPA believes that this revised 

frequency addresses commenters' concerns that more frequent reevaluations are necessary to 

address the inherent uncertainties in modeling CO2 movement, the emerging nature of GS 

technology, risk-based targeting of monitoring activities, and the unique nature of CO2 GS. To 

the comment that a "minimum frequency" tends to become a standard frequency, which may not 

be adequate for some sites, EPA clarifies that the Director has discretion to require more frequent 

AoR reevaluations based on site specific information to ensure that USDWs are protected from 

endangerment. 

EPA recognizes that there are many unknowns about how GS projects will unfold including: the 

practicalities of permitting, operating, monitoring, and closing a GS project. To address this, the 

Agency is using an adaptive approach to regulating GS. The Agency 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. 

EPA disagrees that an annual reevaluation of the AoR is appropriate, because this timeframe 

would not, in many cases, allow for the generation and collection of sufficient data on which 

evaluate modeled predictions. However, EPA adds that the Director has discretion to require 

more frequent reevaluations based on site specific information such as when monitoring data 

differ significantly from modeled predictions, or when there are appreciable operational changes 

(e.g., injection rates). 

EPA adds that the final GS rule includes provisions that owners or operators review and update 

the AoR and corrective action plan throughout the life of the project, as specified in §146.84(c). 

Owners or operators must review the plan and identify necessary amendments to the plan or 

demonstrate to the Director that no amendment is needed. The review must be performed within 

one year of an AoR reevaluation, following any significant changes to the facility (e.g., the 

addition of monitoring or injection wells), or when required by the Director. EPA believes that 

these new provisions could address the commenter’s suggestions. 

Letter ID: 0250 Comment ID: 22309 Letter Lines: 876 to 892 

Comment Code: 3700 2.2.5 Comments on the requirement for an AoR and corrective action 

plan 

Comment Code: 4750 2.7.5 Comments on the merit of annual reports (seeking comment) 

Comment: The rule should require updating when warranted of all of the proposed "plans" 

and should require an annual report that summarizes whether not updates have 

been warranted, and whether or not updates have been undertaken 

We applaud EPA for proposing to require the creation, use, and updating of 

various "plans" during the operating life of a facility. By creating such an 

iterative process, and basing it on monitoring and other operational data that 

38
become available through time, EPA can assure that facilities are managed in a 

way that adapts to changing circumstances. This approach also has the potential 

to enable what the Preamble calls an "ongoing dialogue" between operators and 

regulators, especially if the rule is enhanced by the annual reporting 

requirement suggested below for inclusion in §146.91. 

Perhaps inadvertently, the proposed rule does not explicitly require updating of 

several of the required plans. In most but not all cases, there is a rather 

ambiguous requirement to "maintain" a given plan. Explicit requirements to make 

updates as warranted appear to be missing from provisions relating to: 

Individual Response: EPA acknowledges the commenters' support of the AoR and corrective 

action plan, and retains the requirement in the final regulation §146.84(b). EPA believes that the 

iterative process by which monitoring and operational data are used to validate the original AoR 

calculation, along with the combined knowledge and ongoing dialogue between the owner or 

operator and the Director on the local geologic conditions will be critical in developing and 

implementing plans that protect USDWs from endangerment. 

EPA adds that the final rule includes provisions that owners or operators review and update the 

AoR and corrective action plan, the testing and monitoring plan, and the emergency and remedial 

response plan throughout the life of the project, as specified in §146.84(c), §146.90(j), and 

§146.94(d). Owners or operators must review each plan and identify necessary amendments to 

the plan or demonstrate to the Director that no amendment is needed. These reviews must be 

performed within one year of an AoR reevaluation, following any significant changes to the 

facility (e.g., the addition of monitoring or injection wells), or when required by the Director. 

EPA clarifies that the final rule does not require an annual report. 

Letter ID: 0250 Comment ID: 22310 Letter Lines: 889 to 896 

Comment Code: 4610 2.6.1 Testing and monitoring plan requirement (seeking comment) 

Comment: Perhaps inadvertently, the proposed rule does not explicitly require updating of 

several of the required plans. In most but not all cases, there is a rather 

ambiguous requirement to "maintain" a given plan. Explicit requirements to make 

updates as warranted appear to be missing from provisions relating to: 

• the testing and monitoring plan required by §146.90 (the ambiguous word 

"maintain" is used and there appears to be no requirement that estimated 

plugging costs be kept current); 

Individual Response: EPA agrees that developing and following testing and monitoring plans is 

an important part of assuring that a GS project is operating properly and is crucial for the early 

detection of potential endangerment to USDWs. EPA also agrees that periodic updates to the 

plan are appropriate. EPA clarifies that the final GS regulation includes a requirement that the 

AoR be reevaluated at least every 5 years, and it specifies at §146.90(j) that the operator revise 

39
the testing and monitoring plan to incorporate the results of the most recent AoR reevaluation 

and recent operational and monitoring data. 

Letter ID: 0250 Comment ID: 22311 Letter Lines: 889 to 892 ; 897 to 898 

Comment Code: 5100 2.8.1 Injection well plugging activities (seeking comment) (40 CFR 

146.92) 

Comment: Perhaps inadvertently, the proposed rule does not explicitly require updating of 

several of the required plans. In most but not all cases, there is a rather 

ambiguous requirement to "maintain" a given plan. Explicit requirements to make 

updates as warranted appear to be missing from provisions relating to: 

• the plugging plan required by §146.92 (again the ambiguous word "maintain" is 

used); 

Individual Response: EPA believes that developing and implementing an injection well 

plugging plan is important to assuring that GS wells are plugged in a manner that will ensure that 

the well will not serve as a conduit for CO2 leakage, preventing endangerment of USDWs. 

EPA disagrees that explicit requirements to make updates to the injection plugging plan is 

necessary. The final rule at §146.92(c) requires the owner or operator to notify the Director of 

any changes to the injection well plugging plan at least 60 days before plugging the well. This 

will allow the owner or operator (through communication with the Director) to address any 

issues associated with the initial well plugging plan submitted with the permit application and 

will require the owner or operator to maintain the plugging plan in order to communicate such 

changes. EPA is not requiring formal periodic review and updates to the injection well plugging 

plan throughout the injection phase. EPA does not expect that changes to this plan would be 

implemented until injection operations cease. 

Letter ID: 0250 Comment ID: 22312 Letter Lines: 889 to 892 ; 899 to 904 

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

Comment: Perhaps inadvertently, the proposed rule does not explicitly require updating of 

several of the required plans. In most but not all cases, there is a rather 

ambiguous requirement to "maintain" a given plan. Explicit requirements to make 

updates as warranted appear to be missing from provisions relating to: 

• the post- injection site care and site closure plan required by §146.93 (not 

only is the word "maintain" used, but the ambiguity inherent in this term is 

revealed by the instruction in §146.93(a)(3) to consider amendments to this plan 

"upon cessation of injection" - §146.93 might be read to mean that operators 

could "maintain" this particular plan simply by considering the need for 

amendment on one occasion over the life of the facility); and 

40
Individual Response: EPA believes that developing and implementing a post-injection site care 

and site closure plan is important to ensure protection of USDWs, and agrees that the plan should 

be revised as needed to account for the most recent information about the site. EPA anticipates 

that, in some cases, the appropriate post-injection monitoring strategy may end up being different 

than initially projected and there may be a need to amend the post-injection site care and site 

closure plan. EPA is requiring that upon the cessation of injection, the owner or operator submit 

an amended post-injection site care and site closure plan or demonstrate to the Director that no 

changes to the original post-injection site care and site closure plan are necessary, as specified in 

§146.93(a)(3). EPA is not requiring formal periodic review and updates to the PISC and site 

closure plan throughout the injection phase. EPA does not expect that changes to this plan would 

be implemented until injection operations cease. EPA envisions that owners or operators would 

take into account similar considerations that guide updates to other project plans, e.g., 

monitoring and operational data and results of AoR reevaluations. EPA adds that, if any 

monitoring or other site data indicate a need for amending the post-injection site care plan, the 

owner or operator is expected to amend the plan accordingly. 

Letter ID: 0250 Comment ID: 22313 Letter Lines: 889 to 892 ; 905 to 907 

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

Comment: Perhaps inadvertently, the proposed rule does not explicitly require updating of 

several of the required plans. In most but not all cases, there is a rather 

ambiguous requirement to "maintain" a given plan. Explicit requirements to make 

updates as warranted appear to be missing from provisions relating to: 

• the emergency and remedial response plan required by §146.94 (there is no 

requirement here that the plan be updated as warranted - there is not even a 

requirement that the plan be "maintained." 

Individual Response: In response to comments on the need for revision of the emergency and 

remedial response plan, EPA has added a requirement at §146.94(d) requiring owners or 

operators to review their emergency and remedial response plans within one year of an AoR 

reevaluation or following significant changes to the facility. Subsequently, the owners or 

operators must submit an amended plan or demonstrate to the Director that no amendment to the 

plan is needed. 

Letter ID: 0250 Comment ID: 22314 Letter Lines: 909 to 932 

Comment Code: 4750 2.7.5 Comments on the merit of annual reports (seeking comment) 

Comment: An additional annual reporting requirement will enhance the ability of both 

Director and operators to keep track of which plans require updating and whether 

or not plans that ought to be updated have in fact been revised. Such a shared 

understanding is essential if there is to be the "ongoing dialogue" between 

41
regulators and operators that EPA anticipates. Our Environmental NGO Group 

considered supporting the inclusion of an annual report as described in the 

preamble at 73 Fed. Reg. 43518, but concluded that the benefits of that 

particular report would be outweighed by the burden. The annual report we are 

suggesting here, however, would be much simpler. We believe that EPA should 

require a report, signed by the appropriate company official, that: 

• lists all of the required plans; 

• confirms for each plan that the company has reviewed all monitoring and 

operational data since the previous annual report that is relevant to a decision 

on whether to update the plan; 

• states with regard to each plan whether an update was determined to be 

warranted; and 

• for those plans where the operator did decide that an update was appropriate, 

a statement that the update has or has not been completed and a summary of the 

modifications that have been made. 

The rule should further provide that the Director has authority to require 

submission of copies of updated plans and/or further information regarding the 

reasons why updates of particular plans have or have not been done. 

Individual Response: The final GS regulation retains the reporting requirements as proposed 

and does not include a requirement for an annual report. Instead, EPA believes that periodic 

reevaluation of the AoR, as required at §146.84(e), along with any revisions to the required plans 

that may be required based on the AoR reevaluation, will promote an ongoing relationship 

between the permitting authority and the owner or operator. The final GS rule, at §§146.84(c), 

146.90(j), and 146.94(d), requires owners or operators to review and update the AoR and 

corrective action plan, the testing and monitoring plan, and the emergency and remedial response 

plan throughout the life of the project. 

Regarding the content of the reports on the updates, owners or operators must review each plan 

and identify necessary amendments to the plan or demonstrate to the Director that no amendment 

is needed. These reviews must be performed within one year of an AoR reevaluation, following 

any significant changes to the facility (e.g., the addition of monitoring or injection wells), or 

when required by the Director. In no case can reviews occur less often than once every five 

years. For additional information, please see the final rule and the preamble for a discussion of 

EPA's final approach to recordkeeping and reporting. 

While the Agency recognizes some concerns expressed by commenters about the burden 

associated with an annual report, the Agency's decision to retain the semi-annual reporting 

requirement at §146.91(a) is because the semi-annual report in conjunction with the continued 

dialogue associated with AoR reevaluations and periodic updates to the plans is a preferred 

approach to an annual report. 

Letter ID: 0250 Comment ID: 22315 Letter Lines: 934 to 943 

42
Comment Code: 3824 2.3.1.2 Cementing of long-string casing (seeking comment) 

Comment: Cementing requirements for casings 

§146.86(b)(3) requires the long string casing to be cemented by circulating 

cement to surface in one or more stages. It has come to our attention that may 

be hard to accomplish in some cases, such as very deep wells. We have also been 

alerted to disadvantages of this approach with regard to the weight of the 

cement column and its relation to well integrity. We urge EPA to fully consider 

the advantages and disadvantages of this approach. At a minimum however, the 

long string casing should be cemented to at least above the confining layer 

(caprock). 

Individual Response: Section 146.86(b)(3) requires that the long-string casing extend to the 

injection zone and be cemented by circulating cement to the surface in one or more stages. It 

does not, however, specify how cementing would be accomplished, and gives flexibility to the 

owner or operator to propose alternate methods to provide a sufficient amount of cement to meet 

the standard that USDWs are protected from endangerment, subject to the approval of the 

Director. EPA notes that there are many potential ways to meet the requirement in deep wells, 

such as the use of staged cementing. See the discussion of Class VI well construction 

requirements in the preamble to the final GS rule for additional information. Additionally, EPA 

is developing guidance on the construction of Class VI wells. This guidance will be available on 

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

EPA adds that cementing of deep wells has been performed successfully in the past, for example, 

by owners or operators of Class I hazardous and Class I municipal waste disposal wells. Some of 

these wells, which must meet the same cementing requirements for long-string casing as Class 

VI wells, are up to 12,000 feet deep (EPA, 2001). 

EPA also received comments from stakeholders representing states, a water association, and 

industry supporting this provision, saying that it provides, at a reasonable cost, corrosion 

protection of the casing; prevents undesirable migration of fluids behind the casing; provides 

support to the casing; and provides multiple barriers against endangerment of USDWs. 

EPA stresses that protection of USDWs is the primary mission and mandate of the UIC program 

and the purpose of all requirements for injection wells. Any injection activity must be 

demonstrated to not endanger USDWs, regardless of their depth, and if such non-endangerment 

cannot be shown, then the activity will not be allowed under UIC requirements or the SDWA. 

EPA recognizes concerns regarding construction of Class VI wells where the lowermost USDW 

is very deep. To further address comments on deep injection wells, the final GS rule at §146.95 

includes requirements for owners or operators that seek a waiver of the injection depth 

requirements. Owners or operators of wells operating under injection depth waivers must comply 

with additional construction requirements to ensure that wells used to inject above or between 

USDWs are protective. See the discussion of the waiver approach in the preamble to the final GS 

rule for additional information. 

43
Letter ID: 0250 Comment ID: 22316 Letter Lines: 945 to 956 

Comment Code: 3866 2.3.3.3 Logging and testing requirements (40 CFR 146.87) 

Comment: Cement bond logs and other outdated methods are not sufficient for establishing 

cement quality and integrity 

Some of the techniques listed in §146.87(a)(2)(ii) and §146.87(a)(3)(ii), such 

as cement bond and variable density logs are no longer state-of-the-art, and do 

not reveal the nature or shape of any voids in the cement - instead they 

represents an average estimate of void space. To verify the integrity of cement 

behind casings, including the location of any channels, contamination or missing 

cement, the Director should require "a cement map that incorporates data from a 

cement bond log, a variable density display, and an ultrasonic image, unless an 

alternative evaluation based on equivalent or better technologies has been 

approved in writing". 

Individual Response: EPA has conducted extensive research and has found that the tests and 

logs specified at §146.87(a)(2 and 3) have been proven through industry practice and research to 

identify cementing flaws. EPA also believes that the required logs are sufficient to show 

potential pathways for migration of fluid into and out of the wellbore. EPA adds that should 

alternative methods be shown to provide equivalent or better information, the Director may allow 

such alternatives under §146.87(a)(5). The Agency plans to, every six years, collect and review 

data on GS projects to determine whether the appropriate amount and types of information and 

appropriate documentation are being collected, and to determine if modifications to the 

requirements are appropriate or necessary. 

Letter ID: 0250 Comment ID: 22317 Letter Lines: 958 to 969 

Comment Code: 4610 2.6.1 Testing and monitoring plan requirement (seeking comment) 

Comment: Monitoring 

In §146.90 the proposed rule outlines requirements for testing and monitoring. 

We strongly support the inclusion of such provisions. Monitoring is central to 

verifying and adapting the operational parameters of a GS project, while the 

concept of GS cannot be simply based on the premise of confinement without 

verification. We also support the provisions calling for a testing and 

monitoring plan, although we have suggested above that the requirements for 

updating this plan be strengthened. The collection of baseline data and 

information prior to the commencement of operations is also necessary for a 

number of monitoring techniques to produce useful results, and should be 

preserved. 

Individual Response: EPA agrees with commenters that developing and following testing and 

44
monitoring plans is an important part of assuring that a GS project is operating properly and is 

crucial for the early detection of potential endangerment to USDWs. EPA also agrees that 

periodic updates to the plan are appropriate. EPA clarifies that the final GS regulation includes a 

requirement that the AoR be reevaluated at least every 5 years, and it specifies at §146.90(j) that 

the operator revise the testing and monitoring plan to incorporate the results of the most recent 

AoR reevaluation and recent operational and monitoring data. EPA adds that the final rule, at 

§146.82, retains the data collection requirements that are part of the permit application. 

Letter ID: 0250 Comment ID: 22318 Letter Lines: 971 to 982 

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

CFR 146.90) 

Comment: The proposed rule outlines several different types of monitoring requirements: 

(a) analysis of the CO2 stream; (b) continuous monitoring of injection pressure, 

rate and volume as well as other quantities; (c) corrosion monitoring for the 

well materials; (d) groundwater and geochemistry monitoring above the confining 

zone; (e) mechanical integrity testing; (f) pressure fall-off tests;(g) CO2 

plume and pressure front tracking; and (h) surface air monitoring. 

We do not wish to comment on (c). We consider subpart (i), enabling the Director 

to require additional forms of monitoring, as well as subpart (j), calling for a 

quality assurance and surveillance plan, entirely appropriate. We consider (a), 

(b), (d), (e), and (f) and (g) to be essential elements of a sound monitoring 

system. 

Individual Response: EPA acknowledges the commenter’s support. 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 preamble for further discussion on 

EPA's final approach. 

EPA agrees with commenters on the importance of monitoring at GS sites and emphasizes that 

monitoring of injection activities will be an important component of every GS project. 

Monitoring associated with injection wells and the movement of the CO2 plume is necessary to 

verify that the injectate is confined in the target formations and does not endanger USDWs. 

Letter ID: 0250 Comment ID: 22319 Letter Lines: 984 to 1010 

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

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

CFR 146.90) 

Comment: In particular, monitoring above the caprock, sometimes informally referred to as 

"above-zone monitoring, and covered in (d), is a tested monitoring method [FN23], and 

one that can be key to verifying the integrity and lateral extent of the caprock 

45
(or confining zone). We support its inclusion, but also recognize that it might 

not be necessary to employ this method every time. We would only consider its 

omission acceptable only if another method capable of testing and verifying the 

integrity of the confining zone is being used. Subpart (d) would also cover 

groundwater monitoring near the surface, at a long distance from the caprock. It 

is our understanding that researchers from the Lawrence Livermore National 

Laboratory are already confident in the merits of this approach and its accuracy 

in detecting small amounts of CO2. We therefore recommend the following minor 

changes to §146.90(d): 

[In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Periodic monitoring of the ground water quality and GEOPHYSICAL, geochemical OR 

OTHER changes above the confining zone(s) that may be a result of carbon dioxide 

OR OTHER INDUCED fluid movement through the confining zone or additional 

identified zones; provided however that the DIRECTOR MAY INSTEAD REQUIRE THE 

INCLUSION OF OTHER METHODS THAT TEST AND/OR VERIFY THE INTEGRITY OF 

THE 

CONFINING ZONE(S) WITH SIMILAR ACCURACY AND TO THE SAME OR LARGER 

AREAL 

EXTENT.(1) [...]" 

[FN23: Used successfully at the Frio pilot project, and already being 

considered for other projects.] 

Individual Response: EPA clarifies that direct monitoring of ground water quality above the 

confining zone is important, and the GS rule requires this at §146.90(d). EPA believes that the 

ground water geochemical monitoring outlined in §146.90(d) will maximize protection of 

USDWs from endangerment at GS sites. Additional monitoring above the confining zone, as 

well as monitoring in additional formations, e.g., the injection zone, may also be necessary, and 

if the Director believes such monitoring is warranted he/she has the authority under §146.90(i) to 

require that it be included in the testing and monitoring plan. 

EPA adds that the baseline geochemical data required with the permit application at 

§146.82(a)(6) will provide information on predicting potential interactions between rocks and 

CO2 as the commenter suggests, and also expects that this information will inform the 

development and approval of a site-specific testing and monitoring plan. EPA expects that the 

data will also help determine whether any changes are occurring above the confining zone and 

whether they might be associated with the CO2 plume or pressure front. 

EPA further clarifies that the final rule at §146.90(g) requires indirect monitoring not above the 

confining zone but in the injection zone, unless the Director determines, based on site-specific 

geology, that indirect methods are not appropriate. Indirect methods can include geophysical 

methods. 

46
Letter ID: 0250 Comment ID: 22320 Letter Lines: 1012 to 1022 

Comment Code: 4655 2.6.5.1 Plume tracking techniques/geophysical methods (seeking 

comment) 

Comment: We also strongly support monitoring to track the CO2 plume. There is no unique 

method for doing this, and we do not believe that 4D-seismic techniques are 

appropriate or effective in all geologic settings, or that they should be made 

mandatory. However, tracking the extent of the CO2 plume is generally possible 

and must be part of a comprehensive and credible monitoring plan and a GS 

project. Appropriate limits of accuracy will be needed, as neither tracking 

individual CO2 molecules, nor to the nearest inch are feasible or desirable. 

However, the monitoring resolution must be such so as to enable confinement to 

be established, to give regulators confidence that the CO2 and displaced fluids 

are not near potential leakage pathways, and to warn in advance of any remedial 

action that might be needed. 

Individual Response: EPA agrees that seismic monitoring may not be applicable or appropriate 

for all sites. The final rule (at §146.90(g)) requires owners or operators to perform monitoring to 

track the extent of the CO2 plume and pressure front. The owner or operator must use direct 

methods to monitor for pressure changes in the injection zone. Indirect methods (e.g., seismic, 

electrical, gravity, or electromagnetic surveys and/or down-hole CO2 detection tools) are also 

required unless the Director determines, based on site-specific geology, that such methods are 

not appropriate. 

EPA is affording Director's discretion regarding the use of geophysical techniques at some sites 

because the Agency recognizes that geophysical methods are not appropriate in all geologic 

settings. For example, geophysical methods are difficult to execute in areas that are structurally 

and topographically complex or where lithologies have limited contrast in density, porosity, 

permeability, and other physical properties. EPA clarifies that this determination will be made by 

the Director based on the site-specific geologic information submitted by the owner or operator 

with their permit application. 

There may also be interference from urban and residential infrastructure, and sites with loose 

materials such as glacial deposits may produce poor or inaccurate seismic images. But the 

laterally continuous, confined formations that that make many sites appropriate for GS will also 

render many of them suitable for seismic surveying. In fact, seismic and other geophysical and 

remote sensing methods have been used with success at GS pilot projects and are likely to be 

useful for plume tracking at many GS sites. StatOilHydro has used both time-lapse seismic and 

gravity methods to track the CO2 plume at the Sleipner site. Seismic surveys have also been used 

successfully at the Weyburn pilot project site in Saskatchewan. Although resolution on seismic 

surveys is generally accepted to be the best of the geophysical methods, gravity monitoring at 

Sleipner has also imaged the plume, and results have agreed with seismic surveys. At InSalah, 

PSInSAR satellite monitoring has been used in combination with tiltmeter data and was able to 

detect otherwise imperceptible ground displacement (i.e., at the millimeter scale) that indicates 

47
the presence of CO2. 

EPA acknowledges the commenters' concern about the cost of geophysical techniques. However, 

EPA believes that tracking of the plume is essential for protection of USDWs from 

endangerment at GS sites and that geophysical methods are necessary for such tracking. 

EPA is developing guidance on testing and monitoring to assist owners or operators and 

Directors in evaluating requirements under §146.90, including proposed monitoring plans. The 

guidance describes available technologies and recommended approaches for implementing a 

testing and monitoring plan, including pre-operational geophysical logging and testing of 

injection wells, MITs, injection well testing during operation, groundwater quality monitoring, 

tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which may 

be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s 

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

Letter ID: 0250 Comment ID: 22321 Letter Lines: 1024 to 1038 

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

Comment: The "position of the pressure front" is not something that is as straightforward 

to establish as the extent of the CO2 plume. As we have commented above, there 

is no distinct "front", or discontinuity, but rather a gradient in pressure that 

dissipates with distance away from the injection zone. Estimating the total 

injection footprint therefore will require appropriate thresholds to be defined 

in order to estimate the area of elevated pressure. Additionally, methods such 

as seismic surveys do not work in the same way for compressed brine as they do 

for CO2rich brine. Tracking the extent of the CO2 plume is generally possible 

and must be part of a comprehensive and credible monitoring plan and a GS 

project. The extent of the area of elevated pressure will likely be estimated 

with a combination of measurements, inferences and modeling, but it is presently 

essential to have monitoring wells penetrating the confining zone to do this. 

Where the CO2 plume itself is concerned, rather than the area of elevated 

pressure, the role of measurements (including indirect measurements such as 

seismic surveys) will and should be far greater than that of modeling. 

Individual Response: EPA agrees with commenter that plume tracking must be part of a 

comprehensive and credible monitoring plan for GS wells. For this reason, EPA believes that 

direct pressure measurements are appropriate and that direct pressure monitoring will be feasible 

at all GS sites. The final rule, at §146.90(g), requires owners or operators to perform monitoring 

to track the extent of the CO2 plume and pressure front. The owner or operator must use direct 

methods to monitor for pressure changes in the injection zone. Indirect methods (e.g., seismic, 

electrical, gravity, or electromagnetic surveys and/or down-hole CO2 detection tools) are also 

required unless the Director determines, based on site-specific geology, that such methods are 

not appropriate. 

EPA believes that pressure monitoring in the injection zone is necessary to track the 

48
development and movement of the pressure front and CO2 plume. Monitoring can also identify 

needed remedial actions, provide inputs for AoR reevaluation modeling, evaluate predictions of 

plume movement, and target additional geochemical and surface monitoring needs. Knowledge 

of the location of the CO2 plume and the associated pressure front will assure the public that GS 

projects are proceeding according to plan, provide sufficient information to the owner or operator 

and Director, or allow for appropriate actions to address any indication that USDWs may be 

endangered. 

EPA is developing guidance on testing and monitoring to assist owners or operators and 

Directors in evaluating requirements under §146.90, which will include discussion of identifying 

the extent of the CO2 plume and pressure front. The guidance describes available technologies 

and recommended approaches for implementing a testing and monitoring plan, including preoperational geophysical logging and testing of injection wells, MITs, injection well testing 

during operation, groundwater quality monitoring, tracking the CO2 plume and pressure front, 

and soil gas and surface air monitoring which may be required by the UIC Director for specific 

GS projects. The guidance can be found on EPA’s website at 

http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm. In addition, in January 2009, 

DOE published a best practices manual entitled "Monitoring, Verification, and Accounting of 

CO2 Stored in Deep Geologic Formations" (DOE/NETL-311/081508); this manual is included in 

the docket for the for the final GS rule. 

Letter ID: 0250 Comment ID: 22322 Letter Lines: 1040 to 1043 

Comment Code: 4670 2.6.7 Surface air monitoring and/or soil gas monitoring (seeking 

comment) 

Comment: Finally, surface air monitoring techniques will not always be necessary for GS 

projects. As with other monitoring methods, they may work well in particular 

settings but not in others (for example where distinguishing from natural 

variability or from baseline data is hard). Current scientific thinking also 

Individual Response: EPA acknowledges that air and soil gas monitoring are subject to sitespecific limitations and may not be suitable in all settings as a method to ensure USDW 

protection. However, EPA does not believe that this should entirely preclude their use. If surface 

monitoring were the only monitoring method employed to ensure USDW protection, direct 

correlation of CO2 at the surface with CO2 in the subsurface might be difficult; however, when 

combined with information gathered through other monitoring techniques required of GS well 

owners and operators (e.g., monitoring wells, geophysical techniques), air and soil gas 

monitoring may provide valuable data on the magnitude and location of a leak. 

The final rule at §146.90(h) retains the allowance for surface air and soil gas monitoring at the 

discretion of the Director as a means of identifying leaks that may pose a risk to USDWs and 

informing emergency notification of a Class VI owner or operator and UIC Director in the event 

of a USDW endangerment, pursuant to requirements at §146.91(c). EPA clarifies that the 

decision to use surface monitoring and the selection of monitoring methods will be site-specific 

49
(e.g., may be influenced by geology, injection depth, and operational conditions) and must be 

based on potential risks to USDWs within the AoR. 

Letter ID: 0250 Comment ID: 22324 Letter Lines: 1043 to 1050 

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

Comment: variability or from baseline data is hard). Current scientific thinking also 

dictates that the CO2 plume and confinement are best monitored near the 

injection zone or right above the caprock. This implies far greater depths, and 

a much larger distance between CO2 and displaced fluids from USDWs. The Director 

should have the discretion to require such techniques, but we do not believe 

that they should be made mandatory for all permits nor should the rule be 

limited to listing specific techniques (which might be superseded or have 

preferable alternatives). 

Individual Response: EPA has changed this requirement in the final rule. The final GS 

regulation, at §146.90(g)(1), requires all GS project owners or operators to monitor for pressure 

changes in the injection zone. EPA believes that pressure monitoring in the injection zone is 

necessary to track the development and movement of the pressure front and CO2 plume. 

Pressure monitoring within the injection zone is necessary because any such monitoring above 

the confining zone would not detect movement of the pressure front unless a breach of the 

confining zone occurs. EPA believes that monitoring using wells in the injection zone (i.e., that 

penetrate the confining zone) can be safely performed if the wells are constructed to prevent flow 

between the injection zone and USDWs or other layers above the confining zone. Such 

construction technologies exist and have been used in the oil and gas industry for years. EPA 

believes that the benefits of monitoring in the injection formation outweigh the manageable risk 

of those monitoring wells serving as conduits for fluid movement. EPA adds that owners or 

operators may consider performing additional pressure monitoring in wells that are above the 

confining zone (e.g., in the same wells used to perform ground water quality monitoring required 

at §146.90(d)) to provide additional verification that no pressure changes are occurring above the 

confining zone due to CO2 leakage. Monitoring also identifies needed remedial actions, provides 

inputs for AoR reevaluation modeling, and targets additional geochemical and surface 

monitoring needs. Knowledge of the location of the CO2 plume and the associated pressure front 

will assure the public that GS projects are proceeding according to plan, provide sufficient 

information to the owner or operator and Director, or allow for appropriate actions to address any 

indication that USDWs may be endangered. 

Flexibility is also provided regarding how to monitor for the specific data required by the final 

rule. The testing and monitoring plan is developed by the owner or operator in consultation with 

the Director and is designed to ensure that a detailed, Director-approved document describing 

how monitoring will be conducted during the lifetime of the project exists. EPA is developing 

guidance on testing and monitoring to assist owners or operators and Directors in evaluating 

requirements under §146.90, including proposed monitoring plans. The guidance describes 

available technologies and recommended approaches for implementing a testing and monitoring 

50
plan, including pre-operational geophysical logging and testing of injection wells, MITs, 

injection well testing during operation, groundwater quality monitoring, tracking the CO2 plume 

and pressure front, and soil gas and surface air monitoring which may be required by the UIC 

Director for specific GS projects. The guidance can be found on EPA’s website at 

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

Letter ID: 0250 Comment ID: 22325 Letter Lines: 1052 to 1086 

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

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

Comment: To capture the points made above and resolve current inaccuracies or limitations 

in the proposed language, we recommend the following additional changes in 

§146.90(g): 

[In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf, to see the 

original formatting.] 

"(1) Testing and monitoring to track ESTABLISH the extent of the carbon 

dioxide plume and the position of the pressure front WITHIN DEFINED 

THRESHOLDS, WITH THE ASSISTANCE OF MODELING TOOLS WHERE 

APPROPRIATE AND THROUGH 

DIRECT MEASUREMENTS OR INDIRECT, GEOPHYSICAL OR OTHER TECHNIQUES 

by either 

monitoring for pressure changes in the first formation overlying the confining 

zone or using indirect, geophysical techniques (e.g., seismic, electrical, 

gravity, or electromagnetic surveys and/or down-hole carbon dioxide detection 

tools); 

(2) TESTING AND MONITORING TO ESTABLISH THE EXTENT OF THE AREA OF 

ELEVATED 

PRESSURE THROUGH DIRECT MEASUREMENTS AND THE ASSISTANCE OF 

MODELING TOOLS." 

and in §146.90(h): 

[In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf, to see the 

original formatting.] 

"At the Director’s discretion, surface air monitoring METHODS and/or soil 

gas monitoring to detect movement of carbon dioxide that could SIGNAL 

endangerMENT OF a USDW. 

(1) The testing and monitoring plan must be based on potential vulnerabilities 

within the area of review; 

(2) The monitoring frequency and spatial distribution of surface air 

51
monitoring and/or soil gas monitoring must reflect baseline data and the 

monitoring plan must include how the proposed monitoring will yield useful 

information on the area of review delineation and/or compliance with standards 

under 40 CFR 144.12" 

Individual Response: As described above, EPA believes that direct pressure measurements are 

appropriate and that direct pressure monitoring will be feasible at all GS sites and retains this 

provision in the final GS rule, at §146.90(g). 

EPA acknowledges that air and soil gas monitoring to ensure USDW protection is not necessary 

at all GS sites and agrees that the decision to use surface monitoring and the selection of 

monitoring methods for the purpose of USDW protection will be site-specific. 

The Agency believes that surface air and soil gas monitoring, when coupled with subsurface 

monitoring, may be appropriate at some GS projects to ensure USDW protection. EPA also 

acknowledges that surface air and soil gas measurements are subject to variability and may not 

be suitable in all settings as a method to ensure USDW protection. However, EPA does not 

believe that this should entirely preclude their use. The decision to use surface monitoring and 

the selection of monitoring methods will be site-specific (e.g., may be influenced by geology, 

injection depth, and operational conditions) and must be based on potential risks to USDWs 

within the AoR. 

In the final rule, at §146.90(h), the decision to require such monitoring as an additional measure 

to ensure USDW protection rests with the Director as a means of identifying leaks that may pose 

a risk to USDWs and informing emergency notification of a Class VI owner or operator and UIC 

Director in the event of a USDW endangerment, pursuant to requirements at §146.91(c). 

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 

preamble for further discussion on EPA's final approach. 

Letter ID: 0250 Comment ID: 22326 Letter Lines: 1088 to 1115 

Comment Code: 1620 1.3.2 Induced seismicity 

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

Comment: Seismicity 

Naturally occurring seismicity has been cited as an area of concern for geologic 

sequestration of CO2. We do believe that seismicity merits diligent treatment 

both in the regulations and in project operation, but we see no need for a 

blanket ban of sequestration in seismically active areas. Although some sites - 

especially ones near major active faults - would not be advisable for injection, 

there are plenty of other sites in seismically active areas that would make 

excellent candidates for safe and effective sequestration. Moreover, tools to 

measure, predict and design against the effects of seismic activity are 

52
available. 

Nature has proven its ability to retain fluids trapped in the subsurface in 

seismically active areas in many instances over hundreds of millions of years, 

even in highly tectonically active regions of the country such as California. 

The potential for slippage for faults to create leakage pathways to USDWs or the 

surface can be managed and effectively minimized through careful siting and 

operational design using well-established tools and methods. The regulations 

should ensure that suitable sites are selected, while high risk areas, such as 

those near major, non-sealing faults or those that demonstrate frequent 

activity, are rejected. The most likely potential CO2 leakage paths would be 

injection wells, and not faults. However, these can be designed to prevent 

leakage and to be resilient to earthquakes. 

We regard a ban on sequestration in seismically active areas unwarranted. We do 

however believe that additional diligence is required in site characterization 

and selection in such areas. The requirement in §146.82(c)(3) should be modified 

as follows: 

Individual Response: EPA agrees that GS should not be banned in any type of environment or 

geologic setting and believes that decisions about seismic risk should be made on a site-specific 

basis. The Class VI requirements to properly characterize, permit, operate, and monitor a GS 

project are designed to ensure that, where GS is employed, it is done in a manner that protects 

USDWs from endangerment. These requirements include site characterization during which 

owners or operators must submit information about the seismic history of and seismic sources 

near a proposed GS site, as well as data on known or suspected faults in the AoR, geomechanical 

information on fractures, stress, ductility, rock strength, and in situ fluid pressures within the 

confining zone as specified in §146.82(a)(3). This information is evaluated by the Director in 

conjunction with information about well construction, operation, monitoring, post-injection site 

care, and other site-specific information. The Director determines suitability of a potential 

project site for GS. Sites with the potential for reopening or reactivation of faults or unacceptable 

seismic risk that could otherwise interfere with containment would not be suitable for GS sites –

as owners or operators seeking to inject CO2 for GS at such sites would not be able to 

demonstrate USDW protection from endangerment. 

EPA acknowledges that wells in the AoR are potential leakage pathways, and the GS rule 

contains rigorous provisions for both injection well construction at §146.86 and corrective action 

on active or abandoned wells located in the AoR at §146.84. 

Letter ID: 0250 Comment ID: 22327 Letter Lines: 1117 to 1134 

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

Comment Code: 1620 1.3.2 Induced seismicity 

Comment: [In the paragraph below the text 

in all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf, to see the 

53
original formatting.] 

"Information on seismic history including the presence and depth of seismic 

sources and aN ASSESSMENT OF that WHETHER SUCH seismicity would not 

interfere with containment;" 

In addition, language should be added to the minimum criteria for siting in 

§146.83, clarifying that if induced or natural seismicity poses unacceptable 

risks, a permit will not be granted. In order properly to assess the risk of 

significant induced seismicity in light of permitted operating conditions, the 

rule may need to require applicants to submit information beyond what is 

currently required in proposed §146.82. The effects of any seismic events during 

project operation should also be taken into account when updating, or 

considering whether to update, the Area of Review and Corrective Action Plan, 

the Testing and Monitoring Plans, and the Emergency and Remedial Response Plans, 

as well as any other plans as necessary. 

Individual Response: 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 preamble discussion of geologic site characterization for further discussion on 

EPA's final approach. 

EPA clarifies that under §146.82(a)(21), the Director has the authority to require additional 

information to be submitted with the permit application. EPA agrees that seismic events should 

be taken into account when updating the plans or other permit conditions and clarifies that 

existing language at §144.39(a)(2) allows the Director to modify the permit when he or she 

receives new information that was not available at the time of permit issuance. 

Letter ID: 0250 Comment ID: 22328 Letter Lines: 1136 to 1146 

Comment Code: 1000 1. General and Administrative Comments 

Comment: F. Conclusion 

Our Environmental NGO Group appreciates 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 acknowledges the comment. Please see the remainder of EPA's 

54
responses to this comment letter 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: 0250 Comment ID: 24726 Letter Lines: 30 to 66 

Comment Code: 1000 1. General and Administrative Comments 

Comment: Comments of: 

Clean Air Task Force 

Clean Water Action 

Environmental Defense Fund 

Natural Resources Defense Council 

Western Resource Advocates 

A. Introduction 

The Clean Air Task Force, Clean Water Action, Environmental Defense Fund, 

Natural Resources Defense Council, and Western Resource Advocates (Environmental 

NGO Group) thank EPA for the opportunity to comment on the Proposed Rule on 

carbon dioxide sequestration wells under the Underground Injection Control (UIC) 

Program. 

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. 

Founded in 1972, Clean Water Action (CWA) has 1.2 million members and offices in 

20 states. Clean Water Action works to improve public health and environmental 

protection through grassroots organizing, policy research and 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. 

Western Resource Advocates (WRA) is a regional non-profit organization using 

law, economics and policy analysis to protect the land, air and water of the 

Interior Western United States. 

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

55
responses to this comment letter as well as the comments of EDF, and NRDC 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: 0250 Comment ID: 25256 Letter Lines: 753 to 780 

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

Comment Code: 3420 2.2.2.1 Scope of the inventory process (e.g., reliance on publicly 

available information, depth of wells) 

Comment: [In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

§146.82(e): "A tabulation COMPILATION of all wells within the area of review 

which penetrate the injection or confining zone(s). TO SUPPLEMENT AND/OR VERIFY 

INFORMATION OF PUBLIC RECORD, OPERATORS SHALL USE REASONABLE 

METHODS TO IDENTIFY 

THE PRESENCE WELLS WITHIN THE AREA OF REVIEW THAT PENETRATE THE 

INJECTION OR 

CONFINING ZONE(S). Such data must include a description [...]" 

[FN22: NETL , for example, has developed an electromagnetic 

system that can be used for areal or ground-based identification of wells 

(casings).] 

Additionally, we believe that problematic wells may not be limited to the 

confining zone, as would be the case if confinement were to be breached, or if 

pressure effects caused by the injection caused fluid movement outside the 

defined confining zone. We recommend the following modification in §146.84(c) 

(2): 

[In the paragraph below the text in 

all CAPS denotes added text. See also EPA-HQ-OW-0390-0250.pdf to see the 

original formatting.] 

"Using methods approved by the Director, identify all penetrations, including 

active and abandoned wells and underground mines, in the area of review that may 

penetrate the confining zone OR OTHERWISE ACT AS CONDUITS FOR FLUID 

MOVEMENT 

INSIDE OR OUTSIDE THE CONFINING ZONE". 

Individual Response: EPA is retaining the requirement at §146.82(b), which is now found in 

§146.82(a)(4), as proposed. EPA adds that all corrective action must be performed pursuant to 

the approved AoR and corrective action plan, which affords the Director the discretion to require 

any additional information needed (including information that is not publically available) to 

56
ensure that all necessary corrective action is performed. EPA notes that the Director has the 

discretion at §146.84(c)(2) to require the owner or operator to supplement a data records 

search—including the use of ground, airborne, or geophysical (e.g., magnetic) surveys—if there 

is reason to believe that the incompleteness of available information could compromise USDW 

protection from endangerment. For these reasons, EPA is retaining the requirement at 

§146.84(c)(2) as proposed. 

Regarding the concern about identifying wells other than those that penetrate the confining zone, 

EPA adds that the Director the discretion to require any additional information needed to ensure 

that all necessary corrective action is performed, including information on wells that are above 

the confining zone, if site-specific information indicates such a need to ensure USDW protection. 

Letter ID: 0250 Comment ID: 25257 Letter Lines: 889 to 896 

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

Comment Code: 4610 2.6.1 Testing and monitoring plan requirement (seeking comment) 

Comment: Perhaps inadvertently, the proposed rule does not explicitly require updating of 

several of the required plans. In most but not all cases, there is a rather 

ambiguous requirement to "maintain" a given plan. Explicit requirements to make 

updates as warranted appear to be missing from provisions relating to: 

• the testing and monitoring plan required by §146.90 (the ambiguous word 

"maintain" is used and there appears to be no requirement that estimated 

plugging costs be kept current); 

Individual Response: The final rule includes provisions that owners or operators review and 

update the AoR and corrective action plan, the testing and monitoring plan, and the emergency 

and remedial response plan throughout the life of the project, as specified in §146.84(c), 

§146.90(j), and §146.94(d). Owners or operators must review each plan and identify necessary 

amendments to the plan or demonstrate to the Director that no amendment is needed. These 

reviews must be performed within one year of an AoR reevaluation, following any significant 

changes to the facility (e.g., the addition of monitoring or injection wells), or when required by 

the Director. 

57