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.
Electronic Filing 

Docket ID No. EPA–HQ–OW–2008–0390 

December 24, 2008 

Water Docket 

U.S. Environmental Protection Agency 

Mailcode 2822T 

1200 Pennsylvania Avenue, NW 

Washington, DC 20460 

RE: AGA Comments on Proposed Federal Requirements Under the Underground 

Injection Control (UIC) Program for Carbon Dioxide (CO2) Geologic Sequestration 

(GS) Wells, 40 C.F.R. Parts 144 and 146, 73 Fed. Reg. 43492 (July 25, 2008) 

 

Dear Sir or Madam: 

The American Gas Association (AGA) appreciates the opportunity to comment on the 

Environmental Protection Agency's (EPA) proposal to establish the regulatory framework for 

geologic sequestration (GS) of carbon dioxide (CO2) under the Underground Injection Control 

(UIC) Program pursuant to the Safe Drinking Water Act (SDWA). 73 Fed. Reg. 43492 (July 25, 

2008). 

The American Gas Association, founded in 1918, represents 202 local energy companies that 

deliver natural gas throughout the United States. There are nearly 70 million residential, 

commercial and industrial natural gas customers in the U.S., of which 92 percent — more than 64 

million customers — receive their gas from AGA members. Today, natural gas meets almost onefourth of the United States' energy needs. For more information, please visit www.aga.org. 

AGA member companies have particular expertise regarding underground storage in geological 

formations. AGA’s Underground Storage Committee (USC) includes engineering representatives 

of more than 30 companies that operate underground natural gas storage facilities in the United 

States and Canada. 

AGA is a member of the Utility Solid Waste Activities Group (USWAG). We support and have joined in comments 

filed by USWAG on EPA’s CO2 geologic sequestration proposed rule. We submit this separate comment letter to 

highlight our specific technical concerns relating to potential impacts on the operation of natural gas underground 

storage facilities. The storage of hydrocarbon natural gases is exempt from current UIC regulations of injection 

activities. However, geologic sequestration of CO2 could have direct and indirect impacts on many current or 

future underground natural gas storage fields in the U.S., depending on how the new GS facilities are located and 

designed. 
AGA Comments on EPA CO2 Sequestration Proposed Rule 

December 24, 2008 

Page 2 

2

Gas storage fields in the United States can be divided into two major types: porous rock reservoirs 

and salt caverns. Gas storage has been developed in many of the major sedimentary basins 

throughout the U.S. Because many of the areas and geologic formations considered for GS will 

be in the same basins and will occur in the geologic section either above, below, or in some cases, 

within the same formation as natural gas storage fields, there is a potential for natural gas storage 

fields to be directly or indirectly impacted by GS. Gas storage is a very important part of natural 

gas supply in the U.S., because it provides up to 50% of the winter heating season peak 

consumption of 50 Bcf per day to residential and commercial customers when there is typically not 

enough flowing capacity in pipelines to meet the winter surge in demand. 

We ask EPA to address the potential impacts on gas storage operations in crafting the final rule 

with respect to the following issues. 

• Minimum criteria for siting: We request that EPA revise proposed section 146.83(a) to 

say that “Owners or operators of Class VI wells must demonstrate to the satisfaction of the 

Director that the wells will be sited in areas with a suitable geologic system, and in a 

manner that will not adversely impact the safe operation of nearby natural gas 

underground storage facilities, in compliance with applicable safety regulations and 

guidelines of the Department of Transportation.” (Requested amended language in 

italics.) Further, the required geologic assessment should include analysis of potential leak 

paths through faulting, fracturing, or other migration paths from injected CO2 in formations 

in close proximity above or below a natural gas storage formation. 

• Require Analysis before Hydraulic Fracturing for GS Wells Near Gas Storage: Before 

hydraulic fracturing of a GS injection well, the GS operator should perform an analysis to 

consider the proximity, both laterally and vertically, of the GS zone to existing natural gas 

storage reservoirs, and should analyze the fracturing design to examine the potential for 

communication with a natural gas storage reservoir. This could be added to the injection 

well construction requirements in section 146.86. 

• Ensure Collaborative Process for GS Construction in Gas Storage Fields: Gas 

storage operators have particular expertise regarding their natural gas storage fields, and 

can help prevent problems if EPA helps to ensure their participation in the process of the 

site evaluation and construction of GS wells in natural gas storage fields. We ask you to 

revise sections 146.86 and 146.87 so as to authorize the Director to ensure the 

coordination between gas storage operators and GS well owners/operators in 

circumstances where the GS construction will occur in natural gas storage fields. Such 

coordination can involve, for example, obtaining input from the gas storage operators on 

the unique circumstances associated with the gas storage field where the GS well will be 

constructed. To assist in this process, gas storage field operators should have ready 

access to GS well records, well logs and cementing records for any GS construction 

activity that occurs in a gas storage field. 

As noted in our joint comments with USWAG, many complex technical and legal issues will have 

to be resolved before geologic sequestration of CO2 can become a reality, and this will require a 

cooperative effort among several federal agencies, including EPA, the Department of 

Transportation, and the Federal Energy Regulatory Commission. The General Accounting Office 

(“GAO”) recently issued a report entitled "Climate Change – Federal Actions Will Greatly Affect the 

Viability of Carbon Capture and Storage As a Key Mitigation Option" (GAO-08-1080, September 
AGA Comments on EPA CO2 Sequestration Proposed Rule 

December 24, 2008 

Page 3 

3

2008) (“GAO Report”), which emphasizes that significant technological barriers involving CO2

capture technologies, as well as regulatory and legal uncertainties involving CO2 storage, leakage, 

and ownership issues, must be resolved before a successful CO2 CCS program of the scale 

envisioned by policymakers can be achieved. GAO Report at 3-5. A National Academy of 

Sciences ("NAS") report emphasized that a large-scale CO2 UIC program cannot be successful "if 

a significant fraction of the public views it as dangerous or unacceptable" and, therefore, CO2

storage technologies must not only be safe and effective, they must be presented "to the public 

and the regulatory community in such a way as to instill confidence that they are in fact safe and 

effective.” Id. at 49 (citing NAS, Prospective Evaluation). We offer the foregoing comments in an 

effort to help ensure the safety and effectiveness of geologic carbon sequestration when it is 

located in or near natural gas storage fields, and to ensure that the interaction of the GS well and 

the natural gas storage field does not pose a threat to underground sources of drinking water. 

AGA appreciates the opportunity to comment. 

Respectfully submitted, 

AMERICAN GAS ASSOCIATION 

By: Pamela A. Lacey 

Senior Managing Counsel 

American Gas Association 

400 North Capitol St. N.W. Suite 450 

Washington, D.C. 20003 

(202) 824-7340 

December 24, 2008 
Letter ID: 0228 

Commenter: Pamela A. Lacey 

Organization: American Gas Association 

Letter ID: 0228 Comment ID: 21802 Letter Lines: 62 to 75 

Comment Code: 1000 1. General and Administrative Comments 

Comment: Gas storage fields in the United States can be divided into two major types: 

porous rock reservoirs and salt caverns. Gas storage has been developed in many 

of the major sedimentary basins throughout the U.S. Because many of the areas 

and geologic formations considered for GS will be in the same basins and will 

occur in the geologic section either above, below, or in some cases, within the 

same formation as natural gas storage fields, there is a potential for natural 

gas storage fields to be directly or indirectly impacted by GS. Gas storage is 

a very important part of natural gas supply in the U.S., because it provides up 

to 50% of the winter heating season peak consumption of 50 Bcf per day to 

residential and commercial customers when there is typically not enough flowing 

capacity in pipelines to meet the winter surge in demand. 

We ask EPA to address the potential impacts on gas storage operations in 

crafting the final rule with respect to the following issues. 

Individual Response: EPA clarifies that the Class VI requirements apply only to wells that are 

injecting CO2 into the subsurface for the purpose of GS, and not to natural gas storage 

operations, and that natural gas storage operations are out of the scope of the UIC program's 

authority. 

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: 0228 Comment ID: 21803 Letter Lines: 77 to 86 

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

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

Comment: - Minimum criteria for siting: We request that EPA revise proposed section 

146.83(a) to say that "Owners or operators of Class VI wells must demonstrate to 

the satisfaction of the Director that the wells will be sited in areas with a 

suitable geologic system, and in a manner that will not adversely impact the 

safe operation of nearby natural gas underground storage facilities, in 

compliance with applicable safety regulations and guidelines of the Department 

of Transportation." (Requested amended language in italics.) Further, the 

required geologic assessment should include analysis of potential leak paths 

1
through faulting, fracturing, or other migration paths from injected CO2 in 

formations in close proximity above or below a natural gas storage formation. 

Individual Response: EPA believes that the extensive requirements for geologic site 

characterization (at §146.82), AoR evaluation (§146.84), and testing of the well during drilling 

(§146.87) are appropriate to ensure that permitting authorities have the necessary information to 

evaluate whether a specific site will allow safe injection of CO2. EPA adds that submittal and 

review of monitoring data (as required at §146.90) and the AoR reevaluation process 

(§146.84(e)) will provide an opportunity for an ongoing review of the site and a dialogue 

between the Director and the owner or operator to ensure that the project is being operated in a 

manner that protects USDWs from endangerment. EPA believes that any natural gas storage 

operations would be found in site characterization as would any faults or fractures. 

Letter ID: 0228 Comment ID: 21804 Letter Lines: 88 to 94 

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

146.86) 

Comment Code: 4140 2.4.1.4 Use of fracturing for GS in specific geologic settings (seeking 

comment) 

Comment: - Require Analysis before Hydraulic Fracturing for GS Wells Near Gas Storage: 

Before hydraulic fracturing of a GS injection well, the GS operator should 

perform an analysis to consider the proximity, both laterally and vertically, of 

the GS zone to existing natural gas storage reservoirs, and should analyze the 

fracturing design to examine the potential for communication with a natural gas 

storage reservoir. This could be added to the injection well construction 

requirements in section 146.86. 

Individual Response: EPA clarifies that all stimulation, including hydraulic fracturing, must be 

approved by the Director. Owners or operators must submit a proposed stimulation program as 

part of the permit application (§146.82(a)(9)); the plan must demonstrate that any stimulation 

activities will not compromise the integrity of the confining zone. The Director will evaluate the 

owner or operator's proposed stimulation plan in the context of all information about the site, and 

the owner or operator must perform stimulation only as approved. 

The final rule also requires that the owner or operator notify the Director 30 days before 

performing stimulation during injection operations (§146.91(d)(2)); this will provide an 

additional opportunity for the Director to review the owner or operator's plans for stimulation 

and add other requirements as needed. EPA clarifies that UIC regulations prohibit fracturing of 

the confining zone at any time during injection or stimulation. 

EPA believes that the extensive requirements for geologic site characterization (at §146.82), 

AoR evaluation (§146.84), and testing of the well during drilling (§146.87) are appropriate to 

ensure that permitting authorities have the necessary information to evaluate whether a specific 

site will allow safe injection of CO2. EPA believes that any natural gas storage operations will 

be identified during site characterization pursuant to requirements at §146.82 and §146.83 as will 

2
any faults or fractures. 

Letter ID: 0228 Comment ID: 21805 Letter Lines: 96 to 108 

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

146.86) 

Comment Code: 3866 2.3.3.3 Logging and testing requirements (40 CFR 146.87) 

Comment: - Ensure Collaborative Process for GS Construction in Gas Storage Fields: Gas 

storage operators have particular expertise regarding their natural gas storage 

fields, and can help prevent problems if EPA helps to ensure their participation 

in the process of the site evaluation and construction of GS wells in natural 

gas storage fields. We ask you to revise sections 146.86 and 146.87 so as to 

authorize the Director to ensure the coordination between gas storage operators 

and GS well owners/operators in circumstances where the GS construction will 

occur in natural gas storage fields. Such coordination can involve, for example, 

obtaining input from the gas storage operators on the unique circumstances 

associated with the gas storage field where the GS well will be constructed. To 

assist in this process, gas storage field operators should have ready access to 

GS well records, well logs and cementing records for any GS construction 

activity that occurs in a gas storage field. 

Individual Response: EPA agrees that GS owners and operators and gas storage operators 

should coordinate when deciding where to locate their facilities. EPA expects that the permitting 

authority will be involved in this decision during the permit application process and when 

approving the permit. The permit application requires at §146.82(a)(2) that owners or operators 

submit a map showing all injection wells, which would include wells used for gas storage. The 

permitting process also requires at 124.10(c)(1)(xi) the notification of the state oil and gas 

agency and state mineral recovery agency, among others, when the draft permit is available for 

comment. The draft permit will also include the permit application. EPA believes that those 

agencies that should be involved in the decision will be properly informed under the final rule 

application and notification procedures. 

Letter ID: 0228 Comment ID: 21806 Letter Lines: 110 to 121 

Comment Code: 1200 1.1 General comments about the rulemaking 

Comment Code: 1500 1.2.2.2.4 Some other agency should regulate GS 

Comment: As noted in our joint comments with USWAG, many complex technical and legal 

issues will have to be resolved before geologic sequestration of CO2 can become 

a reality, and this will require a cooperative effort among several federal 

agencies, including EPA, the Department of Transportation, and the Federal 

Energy Regulatory Commission. The General Accounting Office ("GAO") recently 

3
issued a report entitled "Climate Change - Federal Actions Will Greatly Affect 

the Viability of Carbon Capture and Storage As a Key Mitigation Option" 

(GAO-08-1080, September 2008) ("GAO Report"), which emphasizes that significant 

technological barriers involving CO2 capture technologies, as well as regulatory 

and legal uncertainties involving CO2 storage, leakage, and ownership issues, 

must be resolved before a successful CO2 CCS program of the scale envisioned by 

policymakers can be achieved. GAO Report at 3-5. A National Academy of Sciences 

Individual Response: Regarding the need for a CCS agency to coordinate across agencies, EPA 

is coordinating with and will continue to facilitate communication among federal and state 

agencies during the implementation phase of the GS regulation. 

Letter ID: 0228 Comment ID: 21807 Letter Lines: 121 to 127 

Comment Code: 1680 1.3.8 Don't overstate risk, don't stigmatize CO2 

Comment: policymakers can be achieved. GAO Report at 3-5. A National Academy of Sciences 

("NAS") report emphasized that a large-scale CO2 UIC program cannot be 

successful "if a significant fraction of the public views it as dangerous or 

unacceptable" and, therefore, CO2 storage technologies must not only be safe and 

effective, they must be presented "to the public and the regulatory community in 

such a way as to instill confidence that they are in fact safe and effective." 

Id. at 49 (citing NAS, Prospective Evaluation). We offer the foregoing comments 

Individual Response: EPA disagrees that the GS regulation overstates the risk of CO2 injection. 

EPA recognizes that injecting large volumes of CO2 for GS poses unique challenges that, if not 

properly managed, could endanger drinking water sources and have other adverse impacts. 

However, with proper site selection, the final, tailored, Class VI requirements address the large 

volumes of CO2 injected, its buoyancy, potential corrosivity in the presence of water, and 

potential impurities in the CO2 stream. In addition, EPA expects the tailored permitting, siting, 

construction, operation, monitoring, and post-injection site care requirements in the GS rule to 

prevent leakage from injection formations and protect USDWs. 

EPA does not agree that the tailored requirements will create a negative public perception of GS. 

The Agency believes that a demonstration to the public that GS projects are meeting the GS 

rule's tailored requirements would likely improve confidence in the project and help address 

public questions and concerns. 

Letter ID: 0228 Comment ID: 21808 Letter Lines: 127 to 131 

Comment Code: 1000 1. General and Administrative Comments 

Comment: Id. at 49 (citing NAS, Prospective Evaluation). We offer the foregoing comments 

in an effort to help ensure the safety and effectiveness of geologic carbon 

sequestration when it is located in or near natural gas storage fields, and to 

4
5

ensure that the interaction of the GS well and the natural gas storage field 

does not pose a threat to underground sources of drinking water. 

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

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.