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.
14785 Preston Road, Suite 1100 • Dallas, Texas 75254-7891 • 972-239-2625 • Fax 972-387-1328 • www.nacoal.com 

DENNIS JAMES Direct Dial: (972) 448-5473

Manager of Technology e-mail:dennis.james@nacoal.com

November 26, 2008 

Water Docket, EPA Docket Center (EPA/DC) 

U. S. EPA West 

Room 3334 

1301 Constitution Ave., NW. 

Washington, DC 20460 

Attn: Docket ID No. EPA–HQ–OW–2008–0390 

Re: 40 CFR Parts 144 and 146 

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

Carbon Dioxide (CO2) Geologic Sequestration (GS) Wells; Proposed Rule 

Friday, July 25, 2008 

Federal Register / Vol. 73, No. 144 

Via Electronic Delivery 

Ladies & Gentlemen: 

The North American Coal Corporation (NAC), a subsidiary of NACCO Industries, Inc. 

(NYSE:NC), mines and markets lignite coal primarily as fuel for power generation and provides 

selected value-added mining services for other natural resources companies. Corporate 

headquarters are located in Dallas, Texas. NAC operates six surface lignite mines in North 

Dakota, Louisiana, Mississippi, and Texas, and also provides dragline mining services for 

independently owned lime rock quarries in Florida. NAC also supplies all the coal to the Dakota 

Gasification Company in Beulah, North Dakota; the only synfuels plant in the U.S. and the 

carbon dioxide producer for the Wayburn Project. The proposed rulemaking will have direct 

impact on our customers and will vitally affect NAC as a coal and lime rock producer. 

Our comments are organized into two sections: 

I. A general statement of NAC’s interest and involvement in this proceeding; 

II. NAC’s comments regarding the above referenced proposed rule. 
Page 2 of 6 

November 20, 2008 

14785 Preston Road, Suite 1100 • Dallas, Texas 75254-78911100 • 972-239-2625 • Fax 972-387-1328 • www.nacoal.com 

I. General Statement:

The North American Coal Corporation believes that a diverse fuel supply is imperative to the 

economic health of our country. Affordable and reliable electricity, which is created in an 

environmentally friendly manner, forms the cornerstone for our country’s economy and creates a 

healthy society. Lignite coal is a vital part of this diverse fuel supply. 

Coal and the low-cost electricity it provides are vital to the reliability of the U.S. electric 

supply system, and to the economic vitality of the U.S. economy. Coal production and related 

electrical generation account for some hundreds of billions of dollars of U.S. gross domestic 

output, over a hundred billion dollars of annual household income, and millions of jobs. 

Lime rock in Florida is used as aggregates in the construction of buildings and roads and as a 

feedstock for cement production. As such, lime rock is a critical component for the growth of 

the region: It is literally the foundation for any building project. 

Coal-fired power plants and cement kilns all produce carbon dioxide (CO2). If legislation or 

regulations are promulgated that restrict the emission of carbon dioxide, then many of these 

facilities will need to capture and sequester CO2. Thus, NAC’s customers will be impacted by 

the proposed regulations. Furthermore, as a natural resource producer, NAC will be directly 

impacted by any rule that affects the subsurface of the Earth. Lignite-fired power plants and 

cement kilns are all “mine mouth” facilities. That is to say, the mine is literally next door to the 

facility. If the facility (and/or others in the area) sequester CO2 in subsurface formations, then 

lands and resources controlled by NAC could be adversely affected. 

II. Comments Submitted by The North American Coal Corporation: 

NAC respectfully submits the following comments regarding the proposed rule to regulate the 

sequestration of CO2 to protect underground sources of drinking water, officially referenced as: 

40 CFR Parts 144 and 146, Federal Requirements Under the Underground Injection Control 

(UIC) Program for Carbon Dioxide (CO2) Geologic Sequestration (GS) Wells; Proposed Rule, 

Friday, July 25, 2008, Federal Register / Vol. 73, No. 144. 

A. NAC supports the Administration in its efforts to develop regulations that will protect our 

valuable groundwater resources. If laws or regulations are promulgated that restrict the 

emissions of CO2, then sequestration will be the only viable way to dispose of CO2 until 

beneficial uses can be developed. Sequestration activities will need to be regulated to 

insure our environment and ALL of our natural resources are protected. 

As a mining company, NAC is very aware that geology varies throughout the country and 

within regions and locales. This heterogeneous mix of subsurface conditions makes it 

challenging to develop a regulatory program that can adequately address all situations 

and conditions that will be encountered. 

B. Comments on Page 43502 subsections: 

F. Why is EPA Proposing To Develop a New Class of Injection Well for GS of CO2? 

G. How Would This Proposal Affect Existing Injection Wells Under the UIC Program? 
Page 3 of 6 

November 20, 2008 

14785 Preston Road, Suite 1100 • Dallas, Texas 75254-78911100 • 972-239-2625 • Fax 972-387-1328 • www.nacoal.com 

The proposed rule states, “the Agency defined five classes of injection wells at 40 CFR 

144.6, based on similarities in the fluids injected, construction, injection depth, design, 

and operating techniques”. However, the Agency is proposing a new class of well based 

more so on use than the afore stated criteria. A Class II well injecting CO2 into a deep oil 

reservoir may have the same physical requirements as a proposed Class VI well injecting 

CO2 into a similar stratum. 

EPA is making the assumption that all Class II wells (EOR) will inject CO2 at relatively 

low pressure and all Class VI wells (GS) will inject CO2 at very high pressure; therefore, 

the use determines the operating condition and requires the separate well classification. 

EOR is far from being a mature and widely deployed technology. GS is still very 

experimental with very limited testing at scale. Therefore, it is possible and probably 

likely that as EOR and GS technologies develop, the range of operating techniques and 

depths will have significant overlaps. 

As such, it would be more appropriate to distinguish CO2 injection wells based on the 

planned operating techniques and conditions than on ultimate use. This would improve 

the protection provided by the intent of the rule. 

Wells permitted for EOR and EGR injection of CO2 do sequester CO2. If these wells 

were permitted for a given range of operating conditions and parameters, then there 

would be no question about a well being used for GS. 

Furthermore, classifying wells as EOR/EGR or GS is problematic. EOR/AGR activities 

do sequester CO2 while they recover oil and gas. If use is the classification criteria, at 

what point would a Class II EOR/EGR well need to be reclassified as a Class VI GS 

well? The recovery of hydrocarbons from an EOR/EGR project will diminish as the 

reserve is depleted. This means that the volume of CO2 injected will result in less oil and 

gas production: Leading to the question of when does a Class II well need to be 

reclassified as a Class VI? If the requirement is only that some amount of hydrocarbon 

be produced, then many GS projects could opt for Class II permits. 

If the intent of the rule is to protect USDWs from the effects of CO2, then any well 

injecting CO2 should be subject to the same permitting requirements for the given 

operating environment. To do otherwise for the sake of bureaucratic simplicity merely 

increases the regulatory burden on operators without adding meaningful protection of the 

environment. 

C. Comments on Page 43502, subsection: 

H. What Are the Target Geologic Formations for GS of CO2? 

This section is a misrepresentation, and in some cases a gross misrepresentation, of the 

types of geologic formations that are suitable for geologic sequestration of CO2. The 

geologic studies of various formations that may be viable reservoirs for the storage of 

CO2 are relatively new. The scientists are just beginning to collect the data and make 

interpretations of the potential storage capacities and related issues. Therefore, it is 
Page 4 of 6 

November 20, 2008 

14785 Preston Road, Suite 1100 • Dallas, Texas 75254-78911100 • 972-239-2625 • Fax 972-387-1328 • www.nacoal.com 

premature for this rule to intimate that one type of geologic formation is better than 

another. The rule should instead promote thorough site characterization as a way to 

determine the adequacy of any formation to act as a sequestration reservoir. 

The rule does state that there is a vast amount of information already available for many 

depleted oil and gas reservoirs. However, it goes on to discuss the many problems that 

could preclude such a reservoir from being used for sequestration. At the same time, the 

rule states, “All these characteristics make deep saline formations the leading candidates 

for GS”. This is a predetermination that deep saline formations are preferred over 

depleted oil and gas reservoirs. At any given site, local conditions may make one option 

better or worse than another. 

Research is active and ongoing in this area. Many potential geologic formations have not 

even been tested for CO2 storage capacity, let alone identification of problems and issues 

inherent to the geologic environment. Unmineable coal seams, basalts, and other 

geologic formations may all have CO2 storage potential. Ruling out any geologic 

formations by administrative fiat is premature and irresponsible. The results of ongoing 

research need to be considered prior to such proposed actions and site specific 

characterization should be the ultimate determinant of a formation’s suitability. 

One additional criterion should be considered in the process of evaluating a specific 

geologic formation for suitability of sequestering CO2: The potential conflict of other 

resources. Other natural resources above, below, or within geologic sequestration 

formations should be considered in any evaluation for long term suitability and security. 

Drilling and mining operations that may occur in the future could have a significant 

impact on a CO2 reservoir. If oil or gas wells are drilled through or even near a reservoir, 

could they affect its integrity? Are there coal reserves, that mining of which (surface or 

underground) could damage the reservoir’s seal? If the presence of sequestered CO2

complicates or precludes the recovery of other resources, who is responsible for the lost 

resource value or additional costs? 

D. Comments on Page 43503 subsections: 

I. Is Injected CO2 Considered a Hazardous Waste Under RCRA? 

J. Is Injected CO2 Considered a Hazardous Substance Under CERCLA? 

Both RCRA and CERCLA are written to deal with hazardous wastes and pollutants at or 

near the surface where they can interact with our biosphere. Geologic sequestration of 

CO2 is, by definition, not impacting the biosphere. Therefore, these rules should not 

apply to the injection of CO2 and associated compounds. 

The chemical environment of deep saline aquifers or deleted oil and gas reservoirs will be 

very different from that at the surface. For example, hydrogen sulfide (H2S) is a very 

toxic and hazardous substance in the biosphere. However, it commonly occurs in 

formations at depth as a normal, naturally occurring constituent that causes no harm. 

Thus, the presence of H2S in a CO2 stream may not only be non-hazardous upon injection 

but beneficial; it could make the injected gas chemically more compatible with the target 

formation’s natural environment. It is more important to consider the impacts of 
Page 5 of 6 

November 20, 2008 

14785 Preston Road, Suite 1100 • Dallas, Texas 75254-78911100 • 972-239-2625 • Fax 972-387-1328 • www.nacoal.com 

injected CO2 and associated substances on the target formation’s environment. 

Therefore, injected CO2 should not be considered a hazardous waste under RCRA or a 

hazardous substance under CERCLA. 

E. Comments on Page 43505 subsection: 

1. Proposed Geologic Siting Requirements 

The proposed rule would require maps, cross sections, and geochemical data on all 

USDWs near an injection well. This requirement could be extremely burdensome to the 

operator, requiring significant work without any additional benefit. In many areas, near 

surface USDWs are very complex systems without much existing data. Obtaining the 

required data on these shallow USDWs would take significant time, money, and 

resources, and the interpreted data would have no impact on the injection well’s 

construction or operation. Defining the lowermost USDW sets a boundary condition for 

an injection well, everything above which would be protected. 

Many statements in this section of the proposed rule specify exactly what types of data 

will be collected and how they will be presented in a permit application. Across the 

United States, there are widely varying geologies, available regional data sets, and how 

well various technologies perform. The permitting authority for a state or region should 

have the flexibility to determine what types of information an operator should present to 

adequately characterize a specific injection well site. 

For example, the following statement is made: “Today’s proposal would require owners 

or operators to submit geochemical data on (a) the injection zone, (b) the confining zones, 

(c) containment zones above the confining zones in which any potentially migrating CO2 

could be trapped, (d) all USDWs, and (e) any other geologic zone or formation that is 

important to the proposed monitoring program.” This essentially requires an operator to 

collect geochemical data on the entire geologic column: From the surface down to the 

target formation. It is important to geochemically define the target formation and its 

overlying seal. It is also prudent to obtain data from adjacent formations that may be 

involved if leakage occurs. However, does this data all the way to the surface in any way 

add additional USDW protection? The permitting authority should have some discretion 

to limit the required data, based on the geology of the area. 

One additional criterion should be considered in the process of evaluating a specific 

geologic formation for suitability of sequestering CO2: The potential conflict of other 

resources. Other natural resources above, below, or within geologic sequestration 

formations should be considered in any evaluation for long-term suitability and security. 

Drilling and mining operations that may occur in the future could have a significant 

impact on a CO2 reservoir. If oil or gas wells are drill through or even near a reservoir, 

could they affect its integrity? Are there coal reserves, that mining of which (surface or 

underground) could damage the reservoir’s seal? If the presence of sequestered CO2

complicates or precludes the recovery of other resources, who is responsible for the lost 

resource value or additional costs? The existing language does require seismic data for 

the area, acknowledging that the geology is not static. Potential human activities could 

also act to disrupt subsurface conditions. 
Page 6 of 6 

November 20, 2008 

NAC appreciates the opportunity to provide comments in this proceeding of vital interest to 

our company, and trusts that these comments will be of assistance to EPA’s subsequent 

regulatory decisions. 

Regards, 

THE NORTH AMERICAN COAL CORPORATION

Dennis R. James 

Manager of Technology 

14785 Preston Road, Suite 1100 • Dallas, Texas 75254-78911100 • 972-239-2625 • Fax 972-387-1328 • www.nacoal.com 
Letter ID: 0214 

Commenter: Dennis R. James 

Organization: North American Coal Corporation (NAC) 

Letter ID: 0214 Comment ID: 22956 Letter Lines: 57 to 86 

Comment Code: 1320 1.1.3 General comments about GS 

Comment: I. General Statement: 

The North American Coal Corporation believes that a diverse fuel supply is 

imperative to the economic health of our country. Affordable and reliable 

electricity, which is created in an environmentally friendly manner, forms the 

cornerstone for our country’s economy and creates a healthy society. Lignite 

coal is a vital part of this diverse fuel supply. 

Coal and the low-cost electricity it provides are vital to the reliability of 

the U.S. electric supply system, and to the economic vitality of the U.S. 

economy. Coal production and related electrical generation account for some 

hundreds of billions of dollars of U.S. gross domestic output, over a hundred 

billion dollars of annual household income, and millions of jobs. 

Lime rock in Florida is used as aggregates in the construction of buildings and 

roads and as a feedstock for cement production. As such, lime rock is a 

critical component for the growth of the region: It is literally the foundation 

for any building project. 

Coal-fired power plants and cement kilns all produce carbon dioxide (CO2). If 

legislation or regulations are promulgated that restrict the emission of carbon 

dioxide, then many of these facilities will need to capture and sequester CO2. 

Thus, NAC’s customers will be impacted by the proposed regulations. 

Furthermore, as a natural resource producer, NAC will be directly impacted by 

any rule that affects the subsurface of the Earth. Lignite-fired power plants 

and cement kilns are all "mine mouth" facilities. That is to say, the mine is 

literally next door to the facility. If the facility (and/or others in the 

area) sequester CO2 in subsurface formations, then lands and resources 

controlled by NAC could be adversely affected. 

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: 0214 Comment ID: 22957 Letter Lines: 97 to 102 

1
Comment Code: 1420 1.2.1.1 Support the GS rulemaking 

Comment: A. NAC supports the Administration in its efforts to develop regulations that 

will protect our valuable groundwater resources. If laws or regulations are 

promulgated that restrict the emissions of CO2, then sequestration will be the 

only viable way to dispose of CO2 until beneficial uses can be developed. 

Sequestration activities will need to be regulated to insure our environment and 

ALL of our natural resources are protected. 

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

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

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

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

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. 

Letter ID: 0214 Comment ID: 22958 Letter Lines: 104 to 107 

Comment Code: 1200 1.1 General comments about the rulemaking 

Comment: As a mining company, NAC is very aware that geology varies throughout the 

country and within regions and locales. This heterogeneous mix of subsurface 

conditions makes it challenging to develop a regulatory program that can 

adequately address all situations and conditions that will be encountered. 

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, including the discussions of site 

characterization and target formations for GS, as well as the rulemaking docket. 

Letter ID: 0214 Comment ID: 22959 Letter Lines: 115 to 154 

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

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

Comment: The proposed rule states, "the Agency defined five classes of injection wells at 

40 CFR 144.6, based on similarities in the fluids injected, construction, 

injection depth, design, and operating techniques". However, the Agency is 

proposing a new class of well based more so on use than the afore stated 

criteria. A Class II well injecting CO2 into a deep oil reservoir may have the 

same physical requirements as a proposed Class VI well injecting CO2 into a 

similar stratum. 

2
EPA is making the assumption that all Class II wells (EOR) will inject CO2 at 

relatively low pressure and all Class VI wells (GS) will inject CO2 at very high 

pressure; therefore, the use determines the operating condition and requires the 

separate well classification. EOR is far from being a mature and widely 

deployed technology. GS is still very experimental with very limited testing at 

scale. Therefore, it is possible and probably likely that as EOR and GS 

technologies develop, the range of operating techniques and depths will have 

significant overlaps. 

As such, it would be more appropriate to distinguish CO2 injection wells based 

on the planned operating techniques and conditions than on ultimate use. This 

would improve the protection provided by the intent of the rule. 

Wells permitted for EOR and EGR injection of CO2 do sequester CO2. If these 

wells were permitted for a given range of operating conditions and parameters, 

then there would be no question about a well being used for GS. 

Furthermore, classifying wells as EOR/EGR or GS is problematic. EOR/AGR 

activities do sequester CO2 while they recover oil and gas. If use is the 

classification criteria, at what point would a Class II EOR/EGR well need to be 

reclassified as a Class VI GS well? The recovery of hydrocarbons from an 

EOR/EGR project will diminish as the reserve is depleted. This means that the 

volume of CO2 injected will result in less oil and gas production: Leading to 

the question of when does a Class II well need to be reclassified as a Class VI? 

If the requirement is only that some amount of hydrocarbon be produced, then 

many GS projects could opt for Class II permits. 

If the intent of the rule is to protect USDWs from the effects of CO2, then any 

well injecting CO2 should be subject to the same permitting requirements for the 

given operating environment. To do otherwise for the sake of bureaucratic 

simplicity merely increases the regulatory burden on operators without adding 

meaningful protection of the environment. 

Individual Response: EPA disagrees that the risks posed by long term storage of CO2 for GS 

can be addressed under existing UIC requirements, such as those for Class II wells. EPA believes 

that there are significant differences between how EOR and GS projects are operated, as well as 

different risks posed by these different injection activities. The new tailored approach of the GS 

rule was designed to address the general risks deep injection may pose to USDWs and was 

tailored specifically to address the risks posed by long term storage of CO2 (i.e., very large 

volumes, very long time-periods, and reservoir pressure conditions). EPA acknowledges that 

some CO2 is sequestered during EOR operations; however, the pressure increases associated 

with injecting high volumes of CO2 changes the risk profiles for these wells increases when 

transitioning from Class II to Class VI. 

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

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

3
Class II where the primary purpose is oil and gas production to Class VI where the primary 

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

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

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

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

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

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

Letter ID: 0214 Comment ID: 22960 Letter Lines: 158 to 199 

Comment Code: 2100 1.6 Target Geologic Formations for GS 

Comment: H. What Are the Target Geologic Formations for GS of CO2? 

This section is a misrepresentation, and in some cases a gross 

misrepresentation, of the types of geologic formations that are suitable for 

geologic sequestration of CO2. The geologic studies of various formations that 

may be viable reservoirs for the storage of CO2 are relatively new. The 

scientists are just beginning to collect the data and make interpretations of 

the potential storage capacities and related issues. Therefore, it is premature 

for this rule to intimate that one type of geologic formation is better than 

another. The rule should instead promote thorough site characterization as a 

way to determine the adequacy of any formation to act as a sequestration 

reservoir. 

The rule does state that there is a vast amount of information already available 

for many depleted oil and gas reservoirs. However, it goes on to discuss the 

many problems that could preclude such a reservoir from being used for 

sequestration. At the same time, the rule states, "All these characteristics 

make deep saline formations the leading candidates for GS". This is a 

predetermination that deep saline formations are preferred over depleted oil and 

gas reservoirs. At any given site, local conditions may make one option better 

or worse than another. 

Research is active and ongoing in this area. Many potential geologic formations 

have not even been tested for CO2 storage capacity, let alone identification of 

problems and issues inherent to the geologic environment. Unmineable coal 

seams, basalts, and other geologic formations may all have CO2 storage 

potential. Ruling out any geologic formations by administrative fiat is 

premature and irresponsible. The results of ongoing research need to be 

considered prior to such proposed actions and site specific characterization 

should be the ultimate determinant of a formation’s suitability. 

One additional criterion should be considered in the process of evaluating a 

specific geologic formation for suitability of sequestering CO2: The potential 

conflict of other resources. Other natural resources above, below, or within 

4
geologic sequestration formations should be considered in any evaluation for 

long term suitability and security. Drilling and mining operations that may 

occur in the future could have a significant impact on a CO2 reservoir. If oil 

or gas wells are drilled through or even near a reservoir, could they affect its 

integrity? Are there coal reserves, that mining of which (surface or 

underground) could damage the reservoir’s seal? If the presence of sequestered 

CO2 complicates or precludes the recovery of other resources, who is responsible 

for the lost resource value or additional costs? 

Individual Response: EPA clarifies that the GS rule does not categorically preclude injection of 

CO2 into any non-USDW formation types. The purpose of the GS rule is to ensure protection of 

USDWs from endangerment, and the rule requires that owners or operators demonstrate that 

wells are sited in suitable systems with geologic formations to receive and confine injected CO2, 

required at §146.83 of the GS rule. The Class VI siting, well construction and operation, 

monitoring and testing, and post-injection site care and site closure requirements are designed to 

ensure that injected CO2 remains within the target formation. If an owner or operator can 

demonstrate to the Director's satisfaction that GS in coal seams, basalts, salt domes, or shales can 

be accomplished in a manner that protects USDWs and meets all of the requirements of the GS 

rule, the project may be permitted as a Class VI well. 

EPA acknowledges that there may be risks associated with GS, particularly regarding GS into 

formations such as coal seams, basalts, salt domes, or shales, which have been the subject of 

limited experimental projects in the past. For this reason, the Agency is using an adaptive 

approach to regulate GS injection. EPA will collect and review project data on early GS projects, 

including those that inject into various formation types, to determine whether the appropriate 

amount and types of information and documentation are 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. 

EPA acknowledges that site-suitability for GS is dependent on a number of factors and that many 

formation types may be suitable for GS. EPA clarifies that the owner or operator of a Class VI 

well must demonstrate site-suitability for GS under §146.83. It is the responsibility of the 

Director to evaluate the information submitted by the owner or operator with the permit 

application and to determine whether GS at a specific site is appropriate. 

EPA agrees that GS into unmineable coal seams has the potential to allow sequestration while 

ensuring USDW protection from endangerment, as described by commenters citing the process 

of enhanced methane recovery. The final GS rule does not preclude injection into unmineable 

coal seams provided owners or operators can demonstrate that GS can be performed in a manner 

that protects USDWs from endangerment. The Agency clarifies that owners or operators of Class 

VI wells used for injecting CO2 into unmineable coal seams are subject to the same site 

characterization, well construction, operation, monitoring, post-injection site care and site 

closure requirements that are required of projects injecting into other formation types. 

Regarding overlap of GS sites, oil and gas sites, or sites containing other resources, EPA notes 

5
that the final rule requires Class VI permit applicants to submit maps and tabulations of wells, 

including injection wells (which could be used for ER or natural gas storage), in the AoR for 

review by the UIC program Director under §146.84. In addition, the rule requires the Director to 

notify the state oil and gas agency and state mineral exploration and recovery agency as part of 

the public notification required for a draft permit, as required at §124.10(c)(1)(xi). EPA expects 

that these agencies will inform the Director of any existing natural gas storage facilities or other 

drilling or mining operations around the proposed GS site and that the Director will take this 

information and the data on wells in the AoR into consideration when deciding whether to grant 

a permit for GS. EPA clarifies that compensation associated with lost resources or additional 

costs resulting from interference with oil and gas or other operations is outside the scope of this 

rulemaking. 

Letter ID: 0214 Comment ID: 22961 Letter Lines: 203 to 222 

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

Comment Code: 1640 1.3.4 CERCLA issues (seeking comment) 

Comment: I. Is Injected CO2 Considered a Hazardous Waste Under RCRA? 

J. Is Injected CO2 Considered a Hazardous Substance Under CERCLA? 

Both RCRA and CERCLA are written to deal with hazardous wastes and pollutants at 

or near the surface where they can interact with our biosphere. Geologic 

sequestration of CO2 is, by definition, not impacting the biosphere. Therefore, 

these rules should not apply to the injection of CO2 and associated compounds. 

The chemical environment of deep saline aquifers or deleted oil and gas 

reservoirs will be very different from that at the surface. For example, 

hydrogen sulfide (H2S) is a very toxic and hazardous substance in the biosphere. 

However, it commonly occurs in formations at depth as a normal, naturally 

occurring constituent that causes no harm. Thus, the presence of H2S in a CO2 

stream may not only be non-hazardous upon injection but beneficial; it could 

make the injected gas chemically more compatible with the target formation’s 

natural environment. It is more important to consider the impacts of injected 

CO2 and associated substances on the target formation’s environment. Therefore, 

injected CO2 should not be considered a hazardous waste under RCRA or a 

hazardous substance under CERCLA. 

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

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

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

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

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

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

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

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

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

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

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

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

EPA clarifies that CO2 itself is not listed as a hazardous substance under CERCLA; however, the 

CO2 stream may contain a listed hazardous substance (such as mercury) or may mobilize 

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

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

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

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

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

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

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

the scope of the Class VI permit. 

Letter ID: 0214 Comment ID: 22962 Letter Lines: 226 to 236 

Comment Code: 3140 2.1.4 Comments that the proposed geologic data requirements are too 

stringent 

Comment: 1. Proposed Geologic Siting Requirements 

The proposed rule would require maps, cross sections, and geochemical data on 

all USDWs near an injection well. This requirement could be extremely 

burdensome to the operator, requiring significant work without any additional 

benefit. In many areas, near surface USDWs are very complex systems without 

much existing data. Obtaining the required data on these shallow USDWs would 

take significant time, money, and resources, and the interpreted data would have 

no impact on the injection well’s construction or operation. Defining the 

lowermost USDW sets a boundary condition for an injection well, everything above 

which would be protected. 

Individual Response: EPA believes that identifying and mapping all surrounding USDWs near 

an injection well, as specified at §146.82(a)(5), is necessary to ensure protection of all USDWs 

from endangerment. The purpose of the UIC requirements (including those for Class VI wells) is 

to ensure the protection of USDWs from endangerment, which are defined based on total 

dissolved solids (TDS) content, not their location or depth (§144.3). 

EPA adds that knowing the number, location and depth of USDWs near an injection well will 

generate baseline regional information, support development of an effective testing and 

monitoring plan, and enhance owner or operator and Director understanding of the site. This 

requirement is common to all injection well classes. 

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Letter ID: 0214 Comment ID: 22963 Letter Lines: 238 to 257 

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

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

Comment: Many statements in this section of the proposed rule specify exactly what types 

of data will be collected and how they will be presented in a permit 

application. Across the United States, there are widely varying geologies, 

available regional data sets, and how well various technologies perform. The 

permitting authority for a state or region should have the flexibility to 

determine what types of information an operator should present to adequately 

characterize a specific injection well site. 

For example, the following statement is made: "Today’s proposal would require 

owners or operators to submit geochemical data on (a) the injection zone, (b) 

the confining zones, (c) containment zones above the confining zones in which 

any potentially migrating CO2 could be trapped, (d) all USDWs, and (e) any other 

geologic zone or formation that is important to the proposed monitoring 

program." This essentially requires an operator to collect geochemical data on 

the entire geologic column: From the surface down to the target formation. It 

is important to geochemically define the target formation and its overlying 

seal. It is also prudent to obtain data from adjacent formations that may be 

involved if leakage occurs. However, does this data all the way to the surface 

in any way add additional USDW protection? The permitting authority should have 

some discretion to limit the required data, based on the geology of the area. 

Individual Response: The Agency believes that the requirement at §146.82(a)(6) to submit 

baseline geochemical data on subsurface geologic formations, including all USDWs in the AoR 

is appropriate and protective of USDWs. EPA believes that this data will support monitoring 

plan development, inform injectate fate and transport model development (e.g., by providing 

appropriate input parameters), and provide information needed to respond to any unexpected and 

unpermitted leaks outside of the injection zone. The baseline geochemical information will allow 

the owner or operator and permitting authority to evaluate monitoring data and identify any 

changes in subsurface geochemistry that may indicate fluid movement. 

The rule requires geochemical analysis of, at a minimum, the injection zone, confining zone, and 

all USDWs (§146.82(a)(6)). These geochemical tests are necessary to ensure the adequacy of the 

confining system and to serve as a baseline for future monitoring. The Director has the discretion 

to require geochemical analysis of additional subsurface zones if in the Director's opinion they 

are necessary for the protection of USDWs from endangerment. 

EPA agrees that site characterization should be site-specific, particularly in light of the variety of 

geologic settings in which GS may be employed. EPA believes that, while there is a large 

amount of required information, the owner or operator is given flexibility in determining what 

methods are used to demonstrate the suitability of a potential site. EPA envisions an ongoing 

dialogue between the Director and the owner or operator during the permitting process (as well 

8
as throughout the operation of the site). 

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

and Directors in evaluating permit requirements and applications under §146.82. The guidance 

provides recommendations regarding characterizing the regional geology and hydrogeology of a 

proposed GS site as well as performing the necessary geochemical, geomechanical, and 

geophysical analyses of the injection and confining zone. The guidance can be found on EPA’s 

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

Letter ID: 0214 Comment ID: 22964 Letter Lines: 259 to 271 

Comment Code: 2100 1.6 Target Geologic Formations for GS 

Comment: One additional criterion should be considered in the process of evaluating a 

specific geologic formation for suitability of sequestering CO2: The potential 

conflict of other resources. Other natural resources above, below, or within 

geologic sequestration formations should be considered in any evaluation for 

long-term suitability and security. Drilling and mining operations that may 

occur in the future could have a significant impact on a CO2 reservoir. If oil 

or gas wells are drill through or even near a reservoir, could they affect its 

integrity? Are there coal reserves, that mining of which (surface or 

underground) could damage the reservoir’s seal? If the presence of sequestered 

CO2 complicates or precludes the recovery of other resources, who is responsible 

for the lost resource value or additional costs? The existing language does 

require seismic data for the area, acknowledging that the geology is not static. 

Potential human activities could also act to disrupt subsurface conditions. 

Individual Response: Under §146.82(a)(2) owners or operators must identify all injection and 

production wells, which will most likely include evidence of and information about the location 

of natural gas storage sites or enhanced recovery sites. The Director must evaluate this 

information when determining whether to issue a permit. The Director may also require 

additional site-characterization or data collection at his or her discretion. For example, the 

Director may require additional monitoring under §146.90(i) to ensure that GS does not interfere 

with existing natural gas storage projects. 

EPA adds that the final rule includes a requirement that state and local oil and gas regulatory 

agencies and state agencies regulating mineral exploration and recovery must be notified when a 

draft Class VI permit is available for public comment, at §124.10(c)(1)(xi). EPA expects that 

staff from the different agencies will provide input on whether a proposed site could interfere 

with other resource uses. 

Regarding the commenter's concern about future drilling and mining operations, EPA clarifies 

that if an injection well is drilled in the future, the applicable UIC requirements (i.e., based on 

the well class) for AoR and corrective action will apply. The UIC program has no authority to 

address drilling for other purposes. However, EPA anticipates that any applicable permitting 

process would consider prior uses of subsurface formations. 

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EPA notes that pore space and mineral rights issues and associated economic losses are outside 

the scope of this rulemaking.