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.
December 23, 2008

Water Docket

U.S. Environmental Protection Agency

Office of Water Docket (Mailcode 2822T)

1200 Pennsylvania Ave., NW

Washington, DC 20460

RE: Comments On The Federal Requirements Under The Underground Injection 

Control (UIC) Program For Carbon Dioxide Geosequestration Wells, Proposed 

Rule EPA-HQ-OW-2008-0390

Dear Water Docket:

The Association of Metropolitan Water Agencies (AMWA) appreciates the opportunity to 

comment on the proposed rule for permitting the geological sequestration of carbon 

dioxide. AMWA recognizes the importance of reducing carbon dioxide emissions to 

mitigate climate change impacts. Our member utilities across the country are engaged in 

efforts to reduce their carbon footprint and greenhouse gas emissions in a myriad of ways 

— from increased efficiency to green power projects. However, protecting our nation’s 

water supply from potential negative impacts of the development of carbon sequestration 

projects is paramount. 

The attached document provides the association’s comments on the proposal. If EPA has 

any questions about our comments please contact me or Erica Brown, Director of 

Regulatory Affairs, at 202-331-2820.

Sincerely,

Diane VanDe Hei

Executive Director

 Cc: Cynthia Dougherty, OGWDW

 Steve Heare, OGWDW

BOARD OF DIRECTORS

President

Brian L. Ramaley

Newport News Waterworks

Vice President

James McDaniel

LA Dept. of Water and Power

Treasurer

Chips Barry

Denver Water Department

Secretary

Jerry N. Johnson

D.C. Water and Sewer Authority

Mark Premo

Anchorage Water and

Wastewater Utility

David Modeer

Tucson Water

Michael Wallis

East Bay Municipal Utility District

Robert Hunter

Atlanta Department of

Watershed Management

Irene Caminer

Chicago Department 

of Water Management

Don Broussard

Lafayette Utilities System

John P. Sullivan, Jr.

Boston Water and

Sewer Commission

Patricia Mulroy

Las Vegas Valley Water District

Emily Lloyd

New York City DEP

David Rager

Greater Cincinnati Water Works

Scott Potter

Nashville Water & Sewerage 

Services

Edmund Archuleta

El Paso Water Utilities

Jeff Taylor

Houston Public Utilities Division

Charles M. Murrray

Fairfax Water

Chuck Clarke

Seattle Public Utilities

Diane VanDe Hei

Executive Director
 AMWA Comments On Proposed Federal UIC Requirements For Carbon Dioxide Geosequestration Wells 1

Association of Metropolitan Water Agencies

Comments On The Federal Requirements Under The Underground Injection Control (UIC) Program For Carbon 

Dioxide Geosequestration Wells, Proposed Rule 

73 Federal Register 43492, July 25, 2008

Introduction

AMWA appreciates the opportunity to comment on the proposed rule for permitting the geological sequestration of 

carbon dioxide (CO2). Many of the most critical impacts of global climate change will manifest themselves through 

the hydrologic system, and there is already strong evidence that climate change is having an impact on the world’s 

water resources. AMWA recognizes the importance of reducing carbon dioxide emissions to mitigate climate 

change impacts. Our member utilities across the country are engaged in efforts to reduce their carbon footprint and 

greenhouse gas emissions in a myriad of ways — from increased efficiency to green power projects. However, 

protecting our nation’s water supply from potential negative impacts of the development of carbon sequestration 

projects is paramount. 

Many strategies must be used to reduce greenhouse gases (GHG) – from conservation to alternative energy sources. 

Carbon capture and sequestration (CCS) may be one tool in the toolbox, but it is not the silver bullet in that it does 

not reduce GHG but simply stores GHG underground. While it is important to perform the research to explore 

options for CCS, including the proper modeling of the subsurface dynamics and comprehensive monitoring of pilot 

and permitted sites, it is also important to consider the permanent nature of sequestration. Our ability to predict 

how subsurface dynamics may change over the life of the sequestration is currently very limited. Carbon 

sequestration is still largely untested and prudence is necessary to avoid any unintended consequences that could 

have long-term effects on underground sources of drinking water (USDWs). 

Therefore, AMWA recommends that the final regulation take a phased approach and prohibit the construction of 

CO2 sequestration wells in the following types of aquifers until more is known about the risks of CO2 sequestration 

to USDWs as a result of the effects and dynamics of the fluid in the subsurface: 

1. Aquifers currently used for potable water supply today, or

2. Aquifers where it can be demonstrated that the aquifer will be used for potable supply in the future. 

AMWA is not trying to block carbon sequestration but believes that unintended consequences to the nation's water 

supply can be avoided by initially prohibiting the construction of CO2 wells in any aquifer for potable supply, and 

by waiting to construct sequestration wells through any USDW until there is a better understanding of the effects of 

carbon sequestration on the dynamics of the subsurface geology and geochemistry. EPA should then revisit this 

exclusion once the potential risk factors and unintended consequences to USDWs are better understood. 

AMWA supports strong criteria for site selection, design and operation of carbon sequestration sites. EPA’s rule 

and any financial incentives put forth by other branches of government must avoid the manifestation of long-term 

risks from adverse site selection or design due to moral hazard. Moral hazard is the possibility that a party 

insulated from risk may behave differently from the way it would behave if it were fully exposed to the risk. A 

potential owner/operator of a CCS site that has liability immunity for example, may have a tendency to act less 

carefully than it otherwise would, leaving another party to bear some responsibility for the consequences of those 

actions.

There are many potential issues that affect water quality that are not directly related to EPA’s authority under the 

Safe Drinking Water Act (SDWA), yet AMWA would like to note that many of these issues need to be addressed 

before carbon sequestration is fully deployed on a national scale. Specifically, AMWA believes that the 

Department of Energy (DOE) should develop feasibility and cost-benefit analyses with respect to additional energy 

and water consumed under a CCS scenario versus traditional coal power plants and other engineering solutions for 
 AMWA Comments On Proposed Federal UIC Requirements For Carbon Dioxide Geosequestration Wells 2

GHG mitigation and reduction. Research regarding the water requirements for a CCS project and the study and 

consideration of future water quantity needs in the regions of potential geosequestration sites must be performed. 

Climate change, drought, and the depletion of traditional ground water supplies due to population growth and land 

development are causing drinking water utility managers to look at new sources of drinking water that have not 

traditionally been considered as sources of drinking water. Coupled with improvements in desalination and other 

treatment technologies, drinking water sources of high salinity are being used for water supply. AMWA 

recommends that EPA reexamine the current classification of a USDW (i.e., an aquifer with a total dissolved solids 

(TDS) concentration of less than 10,000 mg/L) when siting Class VI geosequestration wells. The potential need to 

use saline aquifers for potable supply, particularly in water-stressed areas, should take precedence over the 

sequestration of carbon dioxide there. 

AMWA supports EPA’s rulemaking to provide a framework for the permitting of carbon sequestration wells, 

recognizing that state agencies are looking to EPA to provide this leadership since carbon sequestration wells are 

already being piloted, yet there is no comprehensive federal standard currently in place. AMWA’s comments are 

comprised of general comments about the proposal as well as several responses to specific EPA requests for 

comment. 

General Comments

Protection of drinking water sources is our primary concern. AMWA is concerned about the potential for CCS 

projects to result in unintended, and possibly harmful, consequences to sources of drinking water. Much of the 

work in the CCS arena is still in pilot or pre-pilot phase. AMWA cautions against the permitting of large scale CCS 

projects until protection of potable or potentially potable aquifers can be established as a primary concern, and 

information about DOE pilot projects and the effects of carbon sequestration on the subsurface and USDW can be 

collected and analyzed.

AMWA is also concerned about using saline aquifers for carbon sequestration. In a climate-stressed and ultimately 

water-stressed world, it is quite possible that these aquifers will be used as drinking water supplies in the near 

future. For example, EPA states in the rule proposal that deep saline aquifers that have >10,000 TDS will account 

for 88% of geosequestration sites. Many of these aquifers may actually be targeted for water supply. 

The experience of drinking water systems in Florida and other areas has demonstrated that TDS measurements in 

USDWs are a moving target. The upper Floridan aquifer is currently about 8000 mg/L TDS. However, in pumping 

this already brackish aquifer, the upwelling of more saline waters from below is occurring. In addition, some 

utilities are considering pumping from deeper wells with a higher salinity for drinking water supply and using 

reverse osmosis to treat for TDS. 

As the protection of current and future drinking water supplies is paramount, AMWA suggests that when there are 

competing uses in an aquifer, the needs of the aquifer for drinking water supply should take precedence over other 

municipal or industrial uses and the risk of unintended impacts on potable water supplies is unacceptable. AMWA 

suggests that EPA require a more rigorous scientific evaluation in the final rule about how potential risk to potable 

aquifers will be avoided in the site characterization for a CO2 geosequestration project. 

Drinking water utilities must be consulted during the review of any CO2 sequestration permit application. AMWA 

recommends that as part of the process, all drinking water utilities that draw from an aquifer in the area of review 

(AoR) of a potential CO2 sequestration project should be informed and consulted. In addition, AMWA 

recommends that local drinking water utilities be included in the AoR review process, as drinking water or potential 

drinking water sources may become threatened due to a change in plume direction or behavior. Public involvement 

also needs to be a mandatory part of the AoR reevaluation process.
 AMWA Comments On Proposed Federal UIC Requirements For Carbon Dioxide Geosequestration Wells 3

Unintended consequences: There have been unintended consequences in the deployment of municipal disposal 

wells in Florida, and AMWA cautions EPA to be very cautious in allowing for carbon sequestration wells to be 

drilled in areas that are not protected by a confining layer of bedrock. For example, AMWA believes that EPA 

should exclude certain formations such as basalt, shale, fractured karst and coal bed seams from Class VI CO2

injection until more research about the appropriateness injection into these formations completed. 

Regulatory alternative: EPA’s proposed Alternative 3 for permitting CO2 geosequestration appears to be the best 

approach in that it would allow for projects to move forward. AMWA supports this approach because it provides 

the permitting authority with discretion to require additional information from owner/operators applying for a 

permit and to make case-by-case permitting decisions. This is important as water chemistry and subsurface 

geology differ widely across the country. 

Class VI wells: AMWA agrees with EPA’s proposal to have CO2 geosequestration wells permitted under a new 

UIC category – Class VI – as this is a new type of injection well. However, as there is limited modeling or 

monitoring data specific to UIC of CO2 available, this data gathering and modeling must occur. AMWA has 

additional comments about research needs below. 

Aspects of permitting process:

 Well construction

o EPA’s proposal requires that materials that meet or exceed industry standards must be compatible with 

injected CO2 and “are designed for the life of the well”. As the CO2 may be stored underground 

indefinitely, are concretes and other well materials designed to last forever under the chemical and 

geological conditions expected in a carbon sequestration well? AMWA requests that EPA and DOE 

perform additional research and data collection in this area.

 Mechanical integrity testing

o AMWA supports EPA’s proposal for mechanical integrity testing every year. This safeguard is 

necessary to protect drinking water supplies, as wells will be drilled through USDWs to reach confined 

bedrock for sequestration wells. 

Research must be comprehensive and must continue to increase our limited understanding of this technology. 

Class VI is a new unique type of well category that needs to have theoretical research (i.e., modeling) and 

monitoring performed, as well as other data gathered, to better understand how CO2 sequestration will affect 

groundwater and the subsurface geology. The research must include a combination of good theoretical work and 

sound observational work as we are entering uncharted territory. While CO2 has been used for gas extraction, 

under geosequestration, CO2 would be put in the ground permanently. As a result, AMWA has the following 

recommendations for research:

o Before any CO2 geosequestration projects are fully deployed, more research is needed to allow EPA 

and/or DOE to develop a risk assessment for the technology, taking into account risks to USDWs. 

o The effectiveness of available risk management methods must be demonstrated. This is also 

recommended by the IPCC in its Summary for Policymakers. 

o Groundwater modeling is improving and variable density flow models for deeper aquifers can be used 

with reasonable accuracy for understanding subsurface flow and quality. However these models must 

take variables such as heat transport into account to better translate to a CO2 geosequestration scenario.

o Data can and should be gathered immediately and more core analysis should be required in the 

permitting process – specifically for key formations and for water/rock/gas interaction. 

o Rock cores and thorough geochemical analysis of geosequestration should happen even before the AoR. 

Advances in research and subsurface modeling make it possible to analyze the interaction between rock 

formations and CO2. Performing these analyses early on could potentially prevent unintended 

consequences.

o Potential ancillary effects of CCS – such as pressure waves, which could move hundreds of miles and 

affect sequestration sites – must be evaluated.
 AMWA Comments On Proposed Federal UIC Requirements For Carbon Dioxide Geosequestration Wells 4

o Effects of CCS on saline aquifers are unknown. CO2 geosequestration modeling performed to-date has 

generally not considered this type of aquifer. This modeling must be conducted.

Specific Comments

EPA requests comments on several aspects of the proposed rule. AMWA’s response to several of these 

requests follows. 

 73 FR 43502 - EPA seeks comment on the approach to grandfather construction requirements at the Director’s 

discretion for existing Class I, Class II, and Class V wells seeking to convert to Class VI wells, and whether 

additional construction requirements would be necessary to prevent endangerment to USDWs from the GS of 

CO2. Additionally, EPA seeks comment on how the grandfathering approach for existing wells may affect 

compliance with the requirements in this proposal.

Response: AMWA recommends that any well being considered for injection of CO2 be required to meet the 

same standards as detailed in EPA’s rule for class VI wells. For example, the wells must be constructed 

with the same corrosion-resistant materials required under the rule. AMWA is new to the details of the UIC 

program and is concerned that wells constructed under Class I, II and V requirements may not have the 

same protective measures required in EPA’s proposed regulation, such as the down-hole shutoff valve. 

AMWA recommends that if EPA proceeds with allowing for wells already constructed to be grandfathered 

and converted to Class VI wells that the owner/operator of the well must conclusively demonstrate, through 

modeling, monitoring and other appropriate data, that the well can be operated in compliance with all 

requirements of the final rule. 

 73 FR 43503 – EPA requests comment on prohibiting injection into unmineable coal seam formations if they 

are above the lowermost USDW.

Response: AMWA opposes the injection of CO2 into coal seams in general and as stated earlier 

recommends that EPA and DOE conduct additional research to determine the impacts of CO2 storage on 

coal seams. Furthermore, AMWA opposes the injection into any formation above the lowermost existing or 

potential USDW and recommends that EPA only allow for the injection of CO2 into formations below the 

lowermost existing or potential USDW. Congress intended the UIC program to protect sources and 

potential sources of drinking water from contamination: 

“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.” SDWA § 1421(d)(2); 42 U.S.C. § 300h(d)(2).

AMWA believes that allowing the injection of CO2 above a USDW would endanger the USDW by 

providing a pathway for CO2 to contaminate a drinking water source, especially if a well was constructed 

through a CO2 plume. 

 73 FR 43507 - EPA seeks comment on requiring the reevaluation of the site AoR on a periodic basis, under 

what conditions the AoR should be reevaluated, and the appropriateness of a 10 year minimum fixed frequency 

for AoR reevaluation.

Response: As carbon sequestration is an emerging technology that has not yet been tested on a large scale 

in the U.S., AMWA believes at this time that a ten-year minimum frequency for AoR evaluation is not 

sufficient. AMWA recommends instead that the AoR be reevaluated annually for the first ten years of the 

project and then every five years for the remaining operating period of the project. 

AMWA also recommends that the final rule include criteria to trigger a shorter review period at earlier 

intervals should monitoring detect a sudden change in CO2 plume movement, size or pressure. In addition, 
 AMWA Comments On Proposed Federal UIC Requirements For Carbon Dioxide Geosequestration Wells 5

AMWA recommends that local drinking water utilities be included in the AoR review process, as existing 

or potential drinking water sources could become threatened due to a change in plume direction or behavior. 

Public involvement also needs to be a mandatory part of the AoR reevaluation process.

 73 FR 43510 - EPA seeks comment regarding requirements for degradation-resistant well construction 

materials, such as acid-resistant cements and corrosion resistant casing.

Response: AMWA agrees that cement and other materials used for carbon sequestration well construction 

must be resistant to corrosion and other potential chemical reactions in the subsurface. As stated earlier 

AMWA also recommends that additional materials research be performed.

 73 FR 435110 - EPA seeks comment on the merits of requiring down-hole shut-off valves in geosequestration 

wells. 

Response: AMWA supports requiring down-hole shut-off valves in all geosequestration wells as these 

valves could provide a line of defense against contamination of USDW in the event of a defective injection 

process.

 73 FR 43512 – EPA requests comment on whether CO2 injection should be allowed into an injection zone 

above the lowermost USDW, when the Director determines that geologic conditions exist that will prevent fluid 

movement into adjacent USDWs.

Response: AMWA opposes the injection into any formation above the lowermost existing or potential 

USDW and recommends that EPA take a phased approach and prohibit the construction of CO2

sequestration wells in aquifers currently used for drinking water supply or expected to be used in the future, 

until more is known about the risks of CO2 sequestration to USDWs as a result of the effects and dynamics 

of the fluid in the subsurface. Congress intended the UIC program to protect sources and potential sources 

of drinking water from contamination: 

“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.” SDWA § 1421(d)(2); 42 U.S.C. § 300h(d)(2).

AMWA believes that allowing the injection of CO2 above a USDW would endanger the USDW by 

providing a pathway for CO2 to contaminate a drinking water source, especially if a well was constructed 

through a CO2 plume. 

 73 FR 43512 – EPA is also requesting comment on whether aquifer exemptions should be allowed for the 

purpose of Class VI injection, and under what conditions should such aquifer exemptions be approved.

Response: AMWA does not believe it is prudent to allow for aquifer exemptions for the purpose of Class 

VI injection as saline aquifers not currently used for USDWs could be considered viable drinking water 

supply in a water-stressed environment. AMWA strongly believes that the use of an aquifer for drinking 

water supply should take precedence over all other municipal or industrial uses. 

 73 FR 43523 - EPA proposes that Class VI injection well permits would be issued for the operating life of the 

GS project including the post-injection site care period. EPA seeks comment on the merits of this approach.

Response: AMWA does not support issuing an operating permit for the life of the sequestration site. 

Instead, AMWA recommends issuing a lifetime operating permit for the coal plant, but with a separate and 

renewable permit for the operation of the geologic sequestration process. Drinking water treatment plants 

must notify state regulators of changes in ownership, management, or operations, and AMWA recommends 

that owner/operators of CCS sites be required to provide the same type of information to the Director in the 
 AMWA Comments On Proposed Federal UIC Requirements For Carbon Dioxide Geosequestration Wells 6

event of changes. In addition, AMWA recommends that owner/operators be required to periodically reevaluate their injectate stream for any emerging contaminants, and remove them if required.

As CCS is a developing technology, AMWA recommends that EPA have a plan to update the regulation as 

additional information is gathered through research and through data and observations collected from 

permitted sites. Having a permit renewal schedule built into the process will allow the Director to ensure 

that updates to the regulation are included in permit renewals. AMWA also suggests that the permit 

application process include a review of the site operations to see if any instances of unsafe operation or 

changes in regulation would require a change in the plant operation. 

 73 FR 43519 - EPA requests comment on the proposed use of a tentative 50-year fixed [post injection site 

care] timeframe that could be modified at the Director’s discretion based on monitoring and modeling data. 

Response: AMWA supports a minimum 50-year time frame for post-injection site care and recommends 

that the Director not be given any discretion to shorten this time period. EPA notes in the proposal that “the 

potential risks of endangering USDWs will not decline within that timeframe given that stabilization may 

continue for several decades.” AMWA also recommends that additional research be conducted to better 

understand the movement of CO2 plumes and that EPA provide guidance to owner/operators about the criteria 

for monitoring and modeling data that would be necessary to demonstrate that the plume has stabilized and 

justify site closure.

Conclusion

In conclusion, AMWA again stresses the need for more research using the improved groundwater modeling 

techniques and variable density flow models for deeper aquifers now available. In addition, EPA must gather 

data now and in the future to better understand the behavior of CO2 plumes and the interaction between water, 

CO2 and bedrock formations. 

Above all, drinking water needs should be considered paramount and EPA should consider the future drinking 

water needs of the country in light of climate change. EPA’s final rule should protect current and future 

USDWs from unintended consequences of CO2 geosequestration and moral hazard.

AMWA appreciates the opportunity to comment on EPA’s proposal. GHG reduction and mitigation measures 

including carbon sequestration are, understandably, very important issues to our members. As CCS technology 

has not been widely deployed in the U.S. to date, AMWA urges EPA and DOE to continue to perform the 

research suggested in these comments as well as follow-up assessments of the technology once deployed. 

AMWA also recommends that EPA commit to update the rule regularly as more becomes known about CCS 

technology and the behavior of CO2 injected into the subsurface. AMWA recommends that EPA work to 

update the rule every three to five years for the foreseeable future, as this technology will become more 

prevalent and injection methods and other sequestration techniques will likely improve. In developing this 

proposal, EPA has demonstrated its ability to quickly bring staff up to speed on this technology and AMWA 

believes the Agency must continue to take a strong interest in keeping up with technological advances. 
Letter ID: 0213 

Commenter: Diane VanDe Hei 

Organization: Association of Metropolitan Water Agencies (AMWA) 

Letter ID: 0213 Comment ID: 22914 Letter Lines: 28 to 36 ; 115 to 117 

Comment Code: 1610 1.3.1 Risks to USDWs 

Comment: The Association of Metropolitan Water Agencies (AMWA) appreciates the 

opportunity to comment on the proposed rule for permitting the geological 

sequestration of carbon dioxide. AMWA recognizes the importance of reducing 

carbon dioxide emissions to mitigate climate change impacts. Our member 

utilities across the country are engaged in efforts to reduce their carbon 

footprint and greenhouse gas emissions in a myriad of ways -- from increased 

efficiency to green power projects. However, protecting our nation’s water 

supply from potential negative impacts of the development of carbon 

sequestration projects is paramount. 

sequestration is currently very limited. Carbon sequestration is still largely 

untested and prudence is necessary to avoid any unintended consequences that 

could have long-term effects on underground sources of drinking water (USDWs). 

Individual Response: EPA believes that sufficient data and experience currently exist to 

develop regulations for Class VI wells. The GS rulemaking builds upon decades of knowledge 

about safe injection practices regulated by the UIC Program. While developing the GS 

regulation, EPA has evaluated relevant GS research, including projects conducted by the seven 

Regional Carbon Sequestration Partnerships (RCSPs) funded by DOE and coordinated through 

the National Energy Technology Laboratory (NETL), and several international projects. 

Letter ID: 0213 Comment ID: 22915 Letter Lines: 95 to 103 

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

Comment: AMWA appreciates the opportunity to comment on the proposed rule for permitting 

the geological sequestration of carbon dioxide (CO2). Many of the most critical 

impacts of global climate change will manifest themselves through the hydrologic 

system, and there is already strong evidence that climate change is having an 

impact on the world’s water resources. AMWA recognizes the importance of 

reducing carbon dioxide emissions to mitigate climate change impacts. Our member 

utilities across the country are engaged in efforts to reduce their carbon 

footprint and greenhouse gas emissions in a myriad of ways -- from increased 

efficiency to green power projects. However, protecting our nation’s water 

Individual Response: The use of and investment in climate change mitigation technologies is 

outside the scope of the Class VI GS rulemaking. The Class VI GS requirements are designed to 

1
ensure that, where GS is deployed, projects are permitted, sited, constructed, operated, and 

closed in a manner that protects USDWs from endangerment. 

Letter ID: 0213 Comment ID: 22916 Letter Lines: 103 to 105 

Comment Code: 1610 1.3.1 Risks to USDWs 

Comment: efficiency to green power projects. However, protecting our nation’s water 

supply from potential negative impacts of the development of carbon 

sequestration projects is paramount. 

Individual Response: EPA recognizes that injecting large volumes of CO2 for GS poses unique 

challenges that, if not properly managed, could endanger drinking water sources or have other 

adverse impacts. EPA agrees that caution is warranted and has, as a result, developed a new well 

class with requirements tailored to address the unique challenges posed by GS and potential risks 

associated long-term injection of CO2. These requirements include the tailored AoR delineation 

process per §146.84, monitoring that is appropriate to GS projects per §146.90, and extended 

post-injection site care per §146.93. 

Letter ID: 0213 Comment ID: 22917 Letter Lines: 107 to 115 

Comment Code: 1510 1.2.2.3 Need for additional study 

Comment: Many strategies must be used to reduce greenhouse gases (GHG) -- from 

conservation to alternative energy sources. Carbon capture and sequestration 

(CCS) may be one tool in the toolbox, but it is not the silver bullet in that it 

does not reduce GHG but simply stores GHG underground. While it is important to 

perform the research to explore options for CCS, including the proper modeling 

of the subsurface dynamics and comprehensive monitoring of pilot and permitted 

sites, it is also important to consider the permanent nature of sequestration. 

Our ability to predict how subsurface dynamics may change over the life of the 

sequestration is currently very limited. Carbon sequestration is still largely 

Individual Response: EPA agrees that GS is a key climate change mitigation technology, one 

that is part of a portfolio of options that could be deployed to reduce CO2 emissions. Other 

options could include efficiency improvements and the use of alternative fuels and renewable 

energy sources. The purpose of the GS regulation is to assure that where deployed, GS is 

conducted in a manner that protects USDWs from endangerment. EPA agrees that continued 

research in all GS associated fields will be integral to development of GS technology. EPA is 

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

collect and review data on GS projects to determine whether the appropriate amount and types of 

information and appropriate documentation are being collected, and to determine if 

modifications to the requirements are appropriate or necessary. 

2
Letter ID: 0213 Comment ID: 22918 Letter Lines: 119 to 134 

Comment Code: 1510 1.2.2.3 Need for additional study 

Comment Code: 1610 1.3.1 Risks to USDWs 

Comment: Therefore, AMWA recommends that the final regulation take a phased approach and 

prohibit the construction of CO2 sequestration wells in the following types of 

aquifers until more is known about the risks of CO2 sequestration to USDWs as a 

result of the effects and dynamics of the fluid in the subsurface: 

1. Aquifers currently used for potable water supply today, or 

2. Aquifers where it can be demonstrated that the aquifer will be used for 

potable supply in the future. AMWA is not trying to block carbon sequestration 

but believes that unintended consequences to the nation's water supply can be 

avoided by initially prohibiting the construction of CO2 wells in any aquifer 

for potable supply, and by waiting to construct sequestration wells through any 

USDW until there is a better understanding of the effects of carbon 

sequestration on the dynamics of the subsurface geology and geochemistry. EPA 

should then revisit this exclusion once the potential risk factors and 

unintended consequences to USDWs are better understood. 

Individual Response: EPA clarifies that the final regulation does not allow injection of carbon 

dioxide into USDWs. USDWs include both currently used sources and sources that may be used 

in the future. Under §144.3 a USDW is defined as an aquifer or portion of an aquifer that 

supplies any public water system or that contains a sufficient quantity of ground water to supply 

a public water system, and currently supplies drinking water for human consumption, or that 

contains fewer than 10,000 mg/L total dissolved solids and is not an exempted aquifer. The GS 

rule requires injection below the lowermost USDW, unless the owner or operator obtains a 

waiver from this requirement, in which case injection may occur into non-USDWs that lie above 

or between USDWs, provided the requirements at §146.95 are met. The final rule also allows for 

the expansion of the areal extent of existing aquifer exemptions for Class II EOR/EGR wells 

transitioning to Class VI injection for GS pursuant to requirements at §§146.4 and 144.7(d). 

Please see the discussion of "Class VI Injection Depth Waivers and Use of Aquifer Exemptions 

for GS" in the preamble to the final rule for additional information. 

The Agency acknowledges the commenter’s concerns about water resources and future water 

resource availability. The primary goal of the UIC Program under the SDWA is to protect 

USDWs from endangerment. Consistent with SDWA §1422, the UIC program provides that no 

injection shall be authorized if it results in the movement of fluid containing any contaminant 

into USDWs, if the presence of that contaminant may cause a violation of any primary drinking 

water regulation or may adversely affect the health of persons as specified in §144.12. 

The GS rule, as part of the UIC program regulations, continues the Program’s mandate under the 

SDWA of ensuring the protection of USDWs from endangerment. EPA expects that the tailored 

3
permitting, siting, construction, operation, monitoring, and post-injection site care requirements 

in the GS rule will prevent leakage from injection formations and protect USDWs. 

Letter ID: 0213 Comment ID: 22919 Letter Lines: 136 to 137 

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

Comment: AMWA supports strong criteria for site selection, design and operation of carbon 

sequestration sites. EPA’s rule and any financial incentives put forth by other 

Individual Response: EPA agrees with the commenter. The GS requirements are designed to 

ensure protection of USDWs from endangerment by requiring that injection wells are permitted, 

sited, constructed, operated, monitored, and plugged in a manner that does not endanger USDWs 

as informed by extensive, site-specific site characterization data. 

Letter ID: 0213 Comment ID: 22920 Letter Lines: 137 to 144 

Comment Code: 1600 1.3 Risk Associated with CO2 GS 

Comment: sequestration sites. EPA’s rule and any financial incentives put forth by other 

branches of government must avoid the manifestation of long-term risks from 

adverse site selection or design due to moral hazard. Moral hazard is the 

possibility that a party insulated from risk may behave differently from the way 

it would behave if it were fully exposed to the risk. A potential owner/operator 

of a CCS site that has liability immunity for example, may have a tendency to 

act less carefully than it otherwise would, leaving another party to bear some 

responsibility for the consequences of those actions. 

Individual Response: EPA clarifies that the GS rule does not insulate owners or operators from 

risk. The GS rule requires that owners or operators demonstrate and maintain financial 

responsibility for corrective action on wells in the AoR, injection well plugging, post-injection 

site care and site closure, and emergency and remedial response at GS sites, as specified in 

§146.85. In the event of contamination or other adverse event that endangers a USDW during the 

life of the project, the financial instrument(s), such as insurance, bonds, etc., rather than public 

monies, would cover necessary response actions to remediate the USDW. EPA clarifies that it is 

the owner or operator of the well who will be required to demonstrate financial responsibility, 

not the generator of the CO2, consistent with EPA’s authority under SDWA. Furthermore, EPA 

notes that tort and other remedies will continue to be available after site closure. Other Federal 

environmental statutes, e.g. Clean Air Act, 42 U.S.C. §§7401-7671; CERCLA, 42 U.S.C. §9601-

9675; and RCRA, 42 U.S.C. §6901-6992, potentially apply as well to the risks created by the 

long-term storage of CO2. 

EPA adds that Class VI well owners and operators must site, construct, operate, monitor, and 

close their wells in a manner that protects USDWs, and Class VI permits will set forth rigorous 

technical requirements to ensure careful planning, operation, and closure of GS projects. Failure 

4
to meet these requirements would be considered a violation of the permit and would be subject to 

applicable civil, criminal, or administrative penalties under SDWA §1423. The comment 

regarding financial incentives put forward by other federal agencies is outside the scope of this 

rulemaking. 

Letter ID: 0213 Comment ID: 22921 Letter Lines: 146 to 156 

Comment Code: 1510 1.2.2.3 Need for additional study 

Comment: There are many potential issues that affect water quality that are not directly 

related to EPA’s authority under the Safe Drinking Water Act (SDWA), yet AMWA 

would like to note that many of these issues need to be addressed before carbon 

sequestration is fully deployed on a national scale. Specifically, AMWA 

believes that the Department of Energy (DOE) should develop feasibility and 

cost-benefit analyses with respect to additional energy and water consumed under 

a CCS scenario versus traditional coal power plants and other engineering 

solutions for GHG mitigation and reduction. Research regarding the water 

requirements for a CCS project and the study and consideration of future water 

quantity needs in the regions of potential geosequestration sites must be 

performed. 

Individual Response: EPA clarifies that cost-benefit analysis of CCS and other greenhouse gas 

mitigation technologies and the water resource requirements for CCS are outside the scope of 

this rulemaking. 

Letter ID: 0213 Comment ID: 22922 Letter Lines: 158 to 168 

Comment Code: 1270 1.1.2 Comments on other rules/issues 

Comment: Climate change, drought, and the depletion of traditional ground water supplies 

due to population growth and land development are causing drinking water utility 

managers to look at new sources of drinking water that have not traditionally 

been considered as sources of drinking water. Coupled with improvements in 

desalination and other treatment technologies, drinking water sources of high 

salinity are being used for water supply. AMWA recommends that EPA reexamine 

the current classification of a USDW (i.e., an aquifer with a total dissolved 

solids (TDS) concentration of less than 10,000 mg/L) when siting Class VI 

geosequestration wells. The potential need to use saline aquifers for potable 

supply, particularly in water-stressed areas, should take precedence over the 

sequestration of carbon dioxide there. 

Individual Response: EPA clarifies that addressing climate change, drought, and the depletion 

of traditional ground water supplies are outside the scope of the Class VI GS rulemaking. Rather, 

the purpose of the Class VI GS rule is to ensure consistency in permitting underground injection 

of CO2 at GS operations across the United States and provide requirements to prevent 

5
endangerment of USDWs in anticipation of the eventual use of GS to reduce CO2 emissions. 

The Agency acknowledges commenter concerns about water resources and future water resource 

availability. However, modifying the definition of a USDW is outside the scope of the Class VI 

GS rulemaking. USDWs are defined as aquifers currently being used as sources of drinking 

water or those capable of supplying a public water system and have a total dissolved solids 

(TDS) content of 10,000 milligrams per liter or less (§144.3). 

The primary goal of the UIC program under the SDWA is to protect USDWs in order to ensure a 

reliable supply of drinking water for the American public. The Class VI GS rule, as part of the 

UIC program regulations, continues the program’s tradition of ensuring the protection of 

USDWs. The permitting, siting, construction, operation, monitoring, and post-injection site care 

requirements in the GS rule build on a long-standing protective regulatory framework, tailored to 

the unique characteristics of CO2 injected for the purpose of GS. 

Letter ID: 0213 Comment ID: 22923 Letter Lines: 170 to 175 

Comment Code: 1420 1.2.1.1 Support the GS rulemaking 

Comment: AMWA supports EPA’s rulemaking to provide a framework for the permitting of 

carbon sequestration wells, recognizing that state agencies are looking to EPA 

to provide this leadership since carbon sequestration wells are already being 

piloted, yet there is no comprehensive federal standard currently in place. 

AMWA’s comments are comprised of general comments about the proposal as well as 

several responses to specific EPA requests for comment. 

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: 0213 Comment ID: 22924 Letter Lines: 179 to 186 

Comment Code: 1510 1.2.2.3 Need for additional study 

Comment Code: 1610 1.3.1 Risks to USDWs 

Comment: Protection of drinking water sources is our primary concern. AMWA is concerned 

about the potential for CCS projects to result in unintended, and possibly 

harmful, consequences to sources of drinking water. Much of the work in the CCS 

arena is still in pilot or pre-pilot phase. AMWA cautions against the permitting 

of large scale CCS projects until protection of potable or potentially potable 

6
aquifers can be established as a primary concern, and information about DOE 

pilot projects and the effects of carbon sequestration on the subsurface and 

USDW can be collected and analyzed. 

Individual Response: As described above, EPA believes that sufficient data and experience 

currently exist to develop regulations for Class VI wells. While developing the GS regulation, 

EPA evaluated relevant GS research, including projects conducted by the seven Regional Carbon 

Sequestration Partnerships (RCSPs) funded by DOE and coordinated through the National 

Energy Technology Laboratory (NETL), and several international projects. 

EPA agrees that continued research will be integral to development of GS technology, but 

disagrees that the Agency should wait for all current field research to be complete before 

finalizing the GS rule. The Agency believes that establishing a regulatory framework for the 

future development and deployment of CCS technology provides a framework for injecting CO2 

so that the activity does not result in endangerment of USDWs. 

EPA believes 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: 0213 Comment ID: 22925 Letter Lines: 188 to 209 

Comment Code: 2126 1.6.1.2 Comments opposing injection into deep saline 

Comment: AMWA is also concerned about using saline aquifers for carbon sequestration. In 

a climate-stressed and ultimately water-stressed world, it is quite possible 

that these aquifers will be used as drinking water supplies in the near future. 

For example, EPA states in the rule proposal that deep saline aquifers that have 

>10,000 TDS will account for 88% of geosequestration sites. Many of these 

aquifers may actually be targeted for water supply. 

The experience of drinking water systems in Florida and other areas has 

demonstrated that TDS measurements in USDWs are a moving target. The upper 

Floridan aquifer is currently about 8000 mg/L TDS. However, in pumping this 

already brackish aquifer, the upwelling of more saline waters from below is 

occurring. In addition, some utilities are considering pumping from deeper wells 

with a higher salinity for drinking water supply and using reverse osmosis to 

treat for TDS. 

As the protection of current and future drinking water supplies is paramount, 

AMWA suggests that when there are competing uses in an aquifer, the needs of the 

aquifer for drinking water supply should take precedence over other municipal or 

industrial uses and the risk of unintended impacts on potable water supplies is 

7
unacceptable. AMWA suggests that EPA require a more rigorous scientific 

evaluation in the final rule about how potential risk to potable aquifers will 

be avoided in the site characterization for a CO2 geosequestration project. 

Individual Response: EPA clarifies that the final rule requires the Director to notify the director 

of the state public water system supervision program (PWSS) when a draft permit becomes 

available for public comment. EPA expects that the PWSS director will provide input to the 

Director regarding competing needs for water resources and whether to grant a permit. 

The Agency acknowledges commenter concerns about water resources and future water resource 

availability. However, modifying the definition of a USDW is outside the scope of the GS 

rulemaking. USDWs are defined as aquifers currently being used as sources of drinking water or 

those capable of supplying a public water system and they have a total dissolved solids (TDS) 

content of 10,000 milligrams per liter or less (§144.3). 

The primary goal of the UIC Program under the SDWA is to protect USDWs in order to ensure a 

reliable supply of drinking water for the American public. The GS rule, as part of the UIC 

program regulations, continues the program’s statutory mandate of ensuring the protection of 

USDWs. The permitting, siting, construction, operation, monitoring, and post-injection site care 

requirements in the GS rule built on a long-standing protective regulatory framework, tailored to 

the unique characteristics of CO2 GS. 

EPA clarifies that a state’s Class VI primacy program may be more stringent then the federal 

requirements. For example, a state has the discretion to ban GS projects from taking place in 

specific formations or other areas where there are water resource issues. EPA believes that state 

permitting authorities are in the best position to make determinations about the appropriateness 

of a particular site based on all available information, including drinking water supply needs. 

Letter ID: 0213 Comment ID: 22926 Letter Lines: 211 to 214 

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

Comment Code: 4710 2.7.1 Proposed submissions required for permit applications (seeking 

comment) 

Comment: Drinking water utilities must be consulted during the review of any CO2 

sequestration permit application. AMWA recommends that as part of the process, 

all drinking water utilities that draw from an aquifer in the area of review 

(AoR) of a potential CO2 sequestration project should be informed and consulted. 

Individual Response: As part of the UIC permit review process in 40 CFR 124, the UIC 

program Director must notify certain stakeholders of any public hearings and the availability of 

the draft permit. EPA has added a requirement at §124.10(c)(1)(xi) that state and local oil and 

gas regulatory agencies and state agencies regulating mineral exploration and recovery, the 

PWSS program director, and all agencies that oversee injection wells in the state must be notified 

as part of the public notice process for a Class VI permit. 

8
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." EPA believes these requirements address 

the commenter's concerns. 

Letter ID: 0213 Comment ID: 22927 Letter Lines: 215 to 218 

Comment Code: 3500 2.2.3 Area of Review Reevaluation (seeking comment) 

Comment Code: 5560 2.10.3 Enhancing the public participation process (seeking comment) 

Comment: In addition, AMWA recommends that local drinking water utilities be included in 

the AoR review process, as drinking water or potential drinking water sources 

may become threatened due to a change in plume direction or behavior. Public 

involvement also needs to be a mandatory part of the AoR reevaluation process. 

Individual Response: EPA agrees that coordination between GS project owners or operators, 

program Directors, drinking water utilities that may be affected by GS activities, and the public 

is important. EPA encourages GS project operators and permitting authorities to use the Internet 

and other available tools to explain potential GS projects, describe the technology, and post 

information on the latest developments, including schedules for hearings, briefings, and other 

opportunities for involvement. EPA has added a requirement at §124.10(c)(1)(xi) that state and 

local oil and gas regulatory agencies and state agencies regulating mineral exploration and 

recovery, the PWSS program director, and all agencies that oversee injection wells in the state 

must be notified as part of the public notice process for a Class VI permit. 

EPA encourages permitting authorities to notify and involve as many stakeholders as possible 

including drinking water organizations and local water utilities. §124.10(c)(1)(x)(A) requires 

notification "to any unit of local government having jurisdiction over the area where the facility 

is proposed to be located; and (B) to each State agency having any authority under State law with 

respect to the construction or operation of such facility." 

EPA anticipates that drinking water associations and local water utilities will express interest in 

and be notified of draft permits and public hearings as required under §124.10(c)(1)(ix) and 40 

CFR Part 25.5 (where EPA is providing public information) which requires the permitting 

authority to notify all interested parties. 

EPA notes that public notice is required if the Director determines that a major permit 

modification is necessary as a result of an AoR reevaluation or other indication that the plume is 

moving in a manner other than predicted. See §144.39(a)(5). 

Letter ID: 0213 Comment ID: 22928 Letter Lines: 220 to 226 

Comment Code: 2100 1.6 Target Geologic Formations for GS 

9
Comment: Unintended consequences: There have been unintended consequences in the 

deployment of municipal disposal wells in Florida, and AMWA cautions EPA to be 

very cautious in allowing for carbon sequestration wells to be drilled in areas 

that are not protected by a confining layer of bedrock. For example, AMWA 

believes that EPA should exclude certain formations such as basalt, shale, 

fractured karst and coal bed seams from Class VI CO2 injection until more 

research about the appropriateness injection into these formations completed. 

Individual Response: EPA clarifies that the final 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. Specifically, EPA clarifies that 

§146.83(a) requires the owner or operator to demonstrate the presence of a confining layer free 

of transmissive faults or fractures and of sufficient extent to contain the injected carbon dioxide 

and any displaced formation fluids; and that the injection zone is of sufficient areal extent, 

thickness, porosity, and permeability to receive the total anticipated volume of the carbon 

dioxide stream. 

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. 

Regarding unintended consequences related to municipal disposal wells in Florida, EPA clarifies 

that GS is quite different from the injection of wastewater in Florida. An owner or operator 

seeking to characterize a site for GS (pursuant to the requirements at §146.82) and identify both 

injection formations and suitable confining units per §146.83 may not be able to meet the 

requirements and ensure protection of USDWs due to the nature of karst formations/geology. In 

addition, the computational modeling required to delineate the AoR for a GS project would 

likely predict inappropriate buoyant flow and eliminate such formations as potential GS sites. 

Letter ID: 0213 Comment ID: 22929 Letter Lines: 228 to 234 

Comment Code: 2300 1.7 Comments on the Alternatives Considered 

Comment: Regulatory alternative: EPA’s proposed Alternative 3 for permitting CO2 

geosequestration appears to be the best approach in that it would allow for 

projects to move forward. AMWA supports this approach because it provides the 

permitting authority with discretion to require additional information from 

owner/operators applying for a permit and to make case-by-case permitting 

decisions. This is important as water chemistry and subsurface geology differ 

widely across the country. 

10
Individual Response: EPA agrees with the commenters that Regulatory Alternative 3 is 

appropriate. The technical requirements in Alternative 3 (and the final GS rule) build upon the 

long-standing UIC regulatory framework for deep wells and are appropriately tailored to address 

the unique nature of full-scale CO2 GS, including the volumes of CO2 to be injected, the 

buoyant and mobile nature of the injectate, and its corrosivity in the presence of water. 

Even though the Agency did not choose Alternatives 1 or 2, EPA agrees that flexibility is 

important to accommodate the varied conditions that may be encountered at GS sites while 

ensuring the protection of USDWs. The final GS regulation gives the Director discretion to set 

permit criteria that are appropriate to site-specific conditions and to require submission of 

additional information when necessary. The regulation provides flexibility for selection of 

appropriate sites and target formations (under §146.82), well construction specifics (under 

§146.86), and testing and monitoring regimes (under §146.90), provided the owner or operator 

can demonstrate that the injection and storage will not endanger USDWs and that minimum 

requirements for the site are met. 

Letter ID: 0213 Comment ID: 22930 Letter Lines: 236 to 240 

Comment Code: 2020 1.5.1 Support Class VI designation 

Comment: Class VI wells: AMWA agrees with EPA’s proposal to have CO2 geosequestration 

wells permitted under a new UIC category -- Class VI -- as this is a new type of 

injection well. However, as there is limited modeling or monitoring data 

specific to UIC of CO2 available, this data gathering and modeling must occur. 

AMWA has additional comments about research needs below. 

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 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. 

Letter ID: 0213 Comment ID: 22931 Letter Lines: 242 to 251 

Comment Code: 3820 2.3.1 Well construction procedures 

Comment: Aspects of permitting process: 

11
- Well construction 

o EPA’s proposal requires that materials that meet or 

exceed industry standards must be compatible with injected CO2 and "are 

designed for the life of the well". As the CO2 may be stored underground 

indefinitely, are concretes and other well materials designed to last 

forever under the chemical and geological conditions expected in a carbon 

sequestration well? AMWA requests that EPA and DOE perform additional 

research and data collection in this area. 

Individual Response: EPA clarifies that the rule requires that all well materials be compatible 

with fluids with which they may come in contact and be of sufficient structural strength to last 

the life of the sequestration project. GS projects are anticipated to have long life spans in 

comparison to other types of deep injection wells. Not only must Class VI wells be able to 

function safely and properly over the lifespan of the GS project, but they must be constructed 

such that USDWs remain protected after well plugging. The requirements at §146.86 will ensure 

that the well can maintain integrity throughout the proposed life span of the project, including 

after the injection well is plugged and through the post-injection site care period and beyond (73 

FR 43510). While the risk profile of a GS site will decrease following cessation of injection, 

EPA believes that Class VI wells must be designed to protect USDWs from endangerment for 

the life of the project. Furthermore, rigorous casing and cementing help ensure that the Class VI 

well will not serve as a conduit for the movement of fluids associated with future injection 

operations. 

Letter ID: 0213 Comment ID: 22932 Letter Lines: 253 to 254 

Comment Code: 4546 2.5.2.2 MIT frequency (seeking comment) 

Comment: - Mechanical integrity testing 

o AMWA supports EPA’s proposal for mechanical integrity testing every year. This safeguard is 

necessary to protect drinking water supplies, as wells will be drilled through USDWs to reach 

confined bedrock for sequestration wells. 

Individual Response: EPA agrees that annual external mechanical integrity testing is justifiable 

for the protection of USDWs from endangerment, given the unique nature of CO2 GS relative to 

other injection operations, including the potential for corrosion of the injection well components 

(e.g., steel casing and cement) and the buoyant nature of the injected CO2. EPA is finalizing 

regulations that require annual external MITs at §146.89(c). 

Letter ID: 0213 Comment ID: 22933 Letter Lines: 256 to 264 

Comment Code: 1510 1.2.2.3 Need for additional study 

Comment: Research must be comprehensive and must continue to increase our limited 

understanding of this technology. Class VI is a new unique type of well category 

that needs to have theoretical research (i.e., modeling) and monitoring 

12
performed, as well as other data gathered, to better understand how CO2 

sequestration will affect groundwater and the subsurface geology. The research 

must include a combination of good theoretical work and sound observational work 

as we are entering uncharted territory. While CO2 has been used for gas 

extraction, under geosequestration, CO2 would be put in the ground permanently. 

As a result, AMWA has the following recommendations for research: 

Individual Response: As described above, EPA agrees that continued research in all GS 

associated fields will be integral to development of GS technology. 

Letter ID: 0213 Comment ID: 22934 Letter Lines: 266 to 271 

Comment Code: 1510 1.2.2.3 Need for additional study 

Comment Code: 1600 1.3 Risk Associated with CO2 GS 

Comment: o Before any CO2 geosequestration projects are fully deployed, more research is 

needed to allow EPA and/or DOE to develop a risk assessment for the technology, 

taking into account risks to USDWs. 

o The effectiveness of available risk management methods must be demonstrated. 

This is also recommended by the IPCC in its Summary for Policymakers. 

Individual Response: As described above, EPA agrees that continued research in all GS 

associated fields will be integral to development of GS technology. EPA is using an adaptive 

approach to regulating GS under the UIC Program. Even after finalization of the GS regulation, 

the Agency plans to collect and review data every six years on GS projects to determine whether 

the appropriate amount and types of information and appropriate documentation are being 

collected, and to determine if modifications to the requirements are appropriate or necessary. 

EPA believes that the GS rule requirements are tailored to address the unique challenges posed 

by GS and the potential risks associated with the long-term injection of CO2. These requirements 

include the tailored AoR delineation process per §146.84, monitoring that is appropriate to GS 

projects per §146.90, and extended post-injection site care per §146.93. 

Letter ID: 0213 Comment ID: 22935 Letter Lines: 273 to 276 

Comment Code: 3300 2.2.1 Delineating the AoR/Modeling CO2 movement 

Comment: o Groundwater modeling is improving and variable density flow models for deeper 

aquifers can be used with reasonable accuracy for understanding subsurface flow 

and quality. However these models must take variables such as heat transport 

into account to better translate to a CO2 geosequestration scenario. 

Individual Response: EPA agrees that heat transport may be an important process in modeling 

of the AoR. The GS regulation stipulates, at 146.84(a), that the physical and chemical properties 

13
of all phases of the injected CO2 stream must be accounted for in the model. Heat transport is 

one of several processes that describe the geologic site, the injection scenario, and the fluids 

present, all of which are the foundation for the multiphase, AoR model development. 

Letter ID: 0213 Comment ID: 22936 Letter Lines: 278 to 280 

Comment Code: 3130 2.1.3 Comments that operators should submit more (or different) 

geologic data than proposed 

Comment: o Data can and should be gathered immediately and more core analysis should be 

required in the permitting process -- specifically for key formations and for 

water/rock/gas interaction. 

Individual Response: The Agency agrees and believes that the site characterization 

requirements at §146.82 are essential to proper siting of a GS well and are the foundation for a 

detailed understanding of the local and regional geology. Collecting and evaluating geochemical 

data in and around the CO2 injection zone, as required in §146.82(a)(6), serves several purposes. 

This baseline geochemical data can help predict geochemical reactions between the injectate, 

reservoir geology, and formation fluids. Such reactions can lead to dissolution and precipitation 

of minerals which affect formation porosity, which in turn can affect required injection pressure 

(Sminchak and Gupta, 2002) and transport of fluid within the formation. While the confining 

layer is the primary barrier to CO2 movement into a USDW, multiple barriers are important and 

changes in injection pressure and fluid movement may compromise those barriers. An increase in 

injection pressure due to reduced porosity, in particular, can lead to fracturing of the confining 

layer and potentially allow fluid movement outside of the injection zone. Losses in injectivity 

because of geochemical reactions may also require additional injection wells and further 

penetrations in the confining layer that can become pathways for fluid migration. 

Letter ID: 0213 Comment ID: 22937 Letter Lines: 282 to 285 

Comment Code: 4660 2.6.6 Geochemical monitoring 

Comment: o Rock cores and thorough geochemical analysis of geosequestration should happen 

even before the AoR. Advances in research and subsurface modeling make it 

possible to analyze the interaction between rock formations and CO2. Performing 

these analyses early on could potentially prevent unintended consequences. 

Individual Response: EPA agrees and believes that the baseline geochemical data required 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 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 

14
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. 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 final GS rule. 

Letter ID: 0213 Comment ID: 22938 Letter Lines: 287 to 288 

Comment Code: 1300 1.1.2.3 Comments on other aspects of CCS (capture, transport) 

Comment Code: 1510 1.2.2.3 Need for additional study 

Comment: o Potential ancillary effects of CCS -- such as pressure waves, which could move 

hundreds of miles and affect sequestration sites -- must be evaluated. 

Individual Response: EPA agrees that continued research in all GS associated fields will be 

integral to development of GS technology. EPA notes that a study conducted by Lawrence 

Berkeley National Laboratory evaluated basin-scale hydrology and pressure changes that could 

occur as a result of GS; this study is described in EPA’s Notice of Data Availability and Request 

for Comment (74 FR 44802, see references to Birkholzer et al. 2008b). 

Letter ID: 0213 Comment ID: 22939 Letter Lines: 290 to 292 

Comment Code: 1510 1.2.2.3 Need for additional study 

Comment Code: 2100 1.6 Target Geologic Formations for GS 

Comment: o Effects of CCS on saline aquifers are unknown. CO2 geosequestration modeling 

performed to-date has generally not considered this type of aquifer. This 

modeling must be conducted. 

Individual Response: EPA acknowledges the commenter's concern about water resources and 

the protection of USDWs from endangerment. The Agency clarifies that the statutory mandate of 

the UIC Program—and the purpose of the GS rule—is to protect current and future underground 

sources of drinking water. Under SDWA authority as implemented by the UIC Program 

regulations, the GS rule establishes comprehensive, rigorous requirements for permitting, siting, 

construction, operation, monitoring, and closure of GS projects. The GS rule's siting 

requirements found at §146.82, along with other requirements for construction, operation, testing 

and monitoring, and post-injection site care and site closure are designed to prevent the 

endangerment of USDWs in the vicinity of GS operations. 

EPA disagrees that insufficient modeling and risk evaluation have been conducted to support the 

GS rulemaking. To develop the GS rule, EPA considered laboratory, modeling, and field 

research, which included data from saline aquifers. In addition, the Agency is involved in 

15
collecting and analyzing GS project data and information from a variety of sources. Most 

notably, EPA has evaluated and written permits and reviewed operational data and information 

associated with the regional carbon sequestration partnership pilot projects funded by DOE and 

coordinated through the National Energy Technology Laboratory (NETL), and several 

international projects. 

EPA agrees that continued research in all GS associated fields will be integral to development of 

GS technology. EPA is aware of research by other federal agencies, industry, international 

parties, and academia related to GS, including projects that address many of the topics suggested 

by commenters. EPA published a Notice of Data Availability (NODA) and Request for 

Comment on August 31, 2009 (74 FR 44802), in which the Agency described the results of 

research at three DOE partnership sites (in Escatawpa, Mississippi; the Aneth Field in Paradox 

Basin, southeast Utah; and the Pump Canyon Site, New Mexico). In the NODA and Request for 

Comment, EPA also described two studies by the Lawrence Berkeley National Laboratory on the 

potential effects of CO2 injection on ground water and surrounding formations to determine the 

potential for impacts on USDWs and human health in the event that a GS project is not properly 

sited, operated, or managed. 

EPA acknowledges that there may be risks associated with GS in certain formation types. 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. 

Letter ID: 0213 Comment ID: 22940 Letter Lines: 299 to 318 

Comment Code: 2060 1.5.3 Comments on grandfathering of existing wells (seeking comment) 

Comment: - 73 FR 43502 -EPA seeks comment on the approach to grandfather construction 

requirements at the Director’s discretion for existing Class I, Class II, and 

Class V wells seeking to convert to Class VI wells, and whether additional 

construction requirements would be necessary to prevent endangerment to USDWs 

from the GS of CO2. Additionally, EPA seeks comment on how the grandfathering 

approach for existing wells may affect compliance with the requirements in this 

proposal. 

Response: AMWA recommends that any well being considered for injection of CO2 be 

required to meet the same standards as detailed in EPA’s rule for class VI 

wells. For example, the wells must be constructed with the same corrosionresistant materials required under the rule. AMWA is new to the details of the 

UIC program and is concerned that wells constructed under Class I, II and V 

16
requirements may not have the same protective measures required in EPA’s 

proposed regulation, such as the down-hole shutoff valve. AMWA recommends that 

if EPA proceeds with allowing for wells already constructed to be grandfathered 

and converted to Class VI wells that the owner/operator of the well must 

conclusively demonstrate, through modeling, monitoring and other appropriate 

data, that the well can be operated in compliance with all requirements of the 

final rule. 

Individual Response: EPA agrees that a cautious approach to grandfathering is appropriate, 

particularly given that the converted well will be used for a substantially different process, which 

involves increased reservoir pressures associated with large volumes of stored CO2 and the 

corrosivity of CO2 in the presence of water. The final GS rule provides for the construction of 

these wells to be grandfathered (per 146.81(c)). EPA has included a requirement in the final GS 

rule that owners or operators seeking to convert existing wells for long term storage must 

demonstrate to the Director that the grandfathered wells were engineered and constructed to meet 

the requirements at §146.86(a) and ensure protection of USDWs, in lieu of requirements at 

§146.86(b) and §146.87(a). EPA clarifies that only the construction requirements are 

grandfathered and that all other Class VI requirements (reporting, monitoring, mechanical 

integrity testing, etc.) must be met following a determination under §146.81(c). EPA expects that 

Directors review and consider many of the factors the commenter mentions, such as the materials 

used and the ability of the well to be tested for, and maintain, mechanical integrity during CO2 

injection when making their determination that §146.81(c) has been met. 

After evaluating the risks and benefits of down-hole shut-off systems and considering additional 

research, EPA will not require automatic down-hole shut-off devices for onshore Class VI wells 

since it is not necessary in all cases to ensure protection of USDWs from endangerment. Instead, 

the final rule, at §146.88(e)(2), requires that owners or operators of onshore Class VI wells 

install automatic surface shut-off devices. The rule affords Director's discretion to mandate 

automatic down-hole shut-off devices in onshore situations that may warrant their use. However, 

the Agency believes that offshore Class VI wells present unique construction and operational 

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

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

rule requires, at §146.88(e)(3), that owners or operators of offshore wells within State territorial 

waters install automatic down-hole shut-off systems. EPA believes that these requirements at 

§146.88(e) ensure that proper precautions are taken to prevent subsurface fluid movement and 

ensure protection of USDWs. 

Letter ID: 0213 Comment ID: 22941 Letter Lines: 320 to 325 

Comment Code: 1510 1.2.2.3 Need for additional study 

Comment Code: 2166 1.6.3.2 Comments opposing injection into unmineable coal seams 

Comment: - 73 FR 43503 - EPA requests comment on prohibiting injection into unmineable 

coal seam formations if they are above the lowermost USDW. 

Response: AMWA opposes the injection of CO2 into coal seams in general and as 

17
stated earlier recommends that EPA and DOE conduct additional research to 

determine the impacts of CO2 storage on coal seams. Furthermore, AMWA opposes 

Individual Response: As described above, the final GS rule does not preclude injection into 

unmineable coal seams (or any formation type) provided owners or operators can demonstrate 

that GS can be performed in a manner that protects USDWs from endangerment. 

EPA recognizes that GS in unmineable coal seams has been the subject of less research than 

saline formations or depleted oil and gas reservoirs. EPA continues to follow existing DOE 

projects and 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: 0213 Comment ID: 22942 Letter Lines: 325 to 339 

Comment Code: 4322 2.4.4.1.1 Comments in favor of requiring injection below the lowermost 

USDW 

Comment: determine the impacts of CO2 storage on coal seams. Furthermore, AMWA opposes 

the injection into any formation above the lowermost existing or potential USDW 

and recommends that EPA only allow for the injection of CO2 into formations 

below the lowermost existing or potential USDW. Congress intended the UIC 

program to protect sources and potential sources of drinking water from 

contamination: "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." SDWA § 1421(d)(2); 42 U.S.C. § 300h(d)(2). 

AMWA believes that allowing the injection of CO2 above a USDW would endanger the 

USDW by providing a pathway for CO2 to contaminate a drinking water source, 

especially if a well was constructed through a CO2 plume. 

Individual Response: EPA agrees that protecting USDWs from endangerment must be a top 

priority. The Agency believes that there are limited circumstances where injection above the 

lowermost USDW can be performed in a manner that protects USDWs, 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 nonUSDW formations above and/or between USDWs. The waiver approach requires the submission 

of extensive, site-specific information (in conjunction with the permit application submission) to 

demonstrate that injection of CO2 into a non-USDW that is above or between USDWs can be 

done in a manner that is protective of USDWs. It establishes: 1) requirements specifying 

information that owners or operators must submit, and Directors must consider, in consultation 

18
with PWSS Directors; 2) procedures for public notice of a waiver application and for DirectorRegional Administrator communication; 3) the waiver issuance process; and, 4) additional 

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

injection depth requirements to ensure USDW protection above and below the injection zone. 

EPA believes that the requirements at §146.95 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: 0213 Comment ID: 22943 Letter Lines: 341 to 357 

Comment Code: 3530 2.2.3.1 AoR reevaluation frequency (seeking comment) 

Comment Code: 3560 2.2.3.2 Conditions that merit reevaluation of the AoR (seeking comment) 

Comment: - 73 FR 43507 -EPA seeks comment on requiring the reevaluation of the site AoR 

on a periodic basis, under what conditions the AoR should be reevaluated, and 

the appropriateness of a 10 year minimum fixed frequency for AoR reevaluation. 

Response: As carbon sequestration is an emerging technology that has not yet 

been tested on a large scale in the U.S., AMWA believes at this time that a tenyear minimum frequency for AoR evaluation is not sufficient. AMWA recommends 

instead that the AoR be reevaluated annually for the first ten years of the 

project and then every five years for the remaining operating period of the 

project. 

AMWA also recommends that the final rule include criteria to trigger a shorter 

review period at earlier intervals should monitoring detect a sudden change in 

CO2 plume movement, size or pressure. In addition, AMWA recommends that local 

drinking water utilities be included in the AoR review process, as existing or 

potential drinking water sources could become threatened due to a change in 

plume direction or behavior. Public involvement also needs to be a mandatory 

Individual Response: EPA agrees with commenters that reevaluations of the AoR every ten 

years may not be sufficient to appropriately model plume and pressure front movement, establish 

conditions for corrective action, and ensure protection of USDWs from endangerment. For these 

reasons, the Agency changed the minimum frequency for the AoR reevaluation at §146.84(e) 

19
from 10 years to at least every 5 years in the final GS rule. EPA believes that this revised 

frequency addresses commenters' concerns about 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. 

EPA agrees that other aspects about a GS project may trigger the need for an AoR reevaluation, 

and adds that the AoR and corrective action plan must also specify the site-specific monitoring 

and operational conditions that warrant reevaluation, as specified in §146.84(b)(2)(ii). EPA 

agrees that site-specific information is an important factor in determining when AoR 

reevaluations are appropriate, and expects that the owner or operator's and Director's combined 

knowledge of the local geologic conditions will be a critical element in developing plans that 

protect USDWs from endangerment. In addition, the Director has discretion to require more 

frequent AoR reevaluation if he or she has reason to believe, based on site-specific information, 

that a five-year reevaluation schedule is not sufficiently protective of USDWs. 

Regarding the suggestion that local drinking water utilities be included in the AoR review 

process, EPA 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. EPA encourages 

permitting authorities to notify and involve as many stakeholders as possible about permit 

modifications, including drinking water organizations and local water utilities. 

Letter ID: 0213 Comment ID: 22944 Letter Lines: 357 to 358 

Comment Code: 3500 2.2.3 Area of Review Reevaluation (seeking comment) 

Comment Code: 5560 2.10.3 Enhancing the public participation process (seeking comment) 

Comment: plume direction or behavior. Public involvement also needs to be a mandatory 

part of the AoR reevaluation process. 

Individual Response: EPA notes that, public notice is required if the Director determines that a 

major permit modification is necessary as a result of an AoR reevaluation. See §144.39(a)(5). 

Letter ID: 0213 Comment ID: 22945 Letter Lines: 360 to 367 

Comment Code: 3862 2.3.3.1 Use of corrosion-resistant construction materials (seeking 

comment) 

Comment Code: 3864 2.3.3.2 Use of corrosion-resistant cements (seeking comment) 

Comment: - 73 FR 43510 -EPA seeks comment regarding requirements for degradationresistant well construction materials, such as acid-resistant cements and 

corrosion resistant casing. 

Response: AMWA agrees that cement and other 

20
materials used for carbon sequestration well construction must be resistant to 

corrosion and other potential chemical reactions in the subsurface. As stated 

earlier AMWA also recommends that additional materials research be performed. 

Individual Response: EPA agrees that the use of non-compatible materials can result in 

degradation and failure of the well and could ultimately endanger a USDW. Under 

§146.86(b)(1), casings and cement and other materials used must have sufficient strength and be 

designed for the life of the sequestration project. Further, materials must meet standards listed in 

the rule and be compatible with fluids with which the materials may be expected to come into 

contact. Therefore, some well materials may need to be acid-resistant and some may not if they 

do not come in contact with the CO2 stream or other corrosive fluids and if approved by the 

Director. 

EPA continues to actively monitor ongoing research on GS and related subtopics. The Agency 

actively tracks more than two dozen DOE pilot projects, which are providing practical 

knowledge and field experience in the early deployment of GS injection wells. The Agency 

discussed three specific projects in the Notice of Data Availability and Request for Comment: 

the Aneth field ER project; the Escatawpa, Mississippi saline basin project; and the Pump 

Canyon Unmineable coal seam project. EPA has also reviewed information from several 

international large-scale commercial GS operations. 

EPA plans to, every six years, collect and review project data on early GS projects, including site 

characterization, operational, monitoring, and modeling data, 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: 0213 Comment ID: 22946 Letter Lines: 369 to 374 

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

Comment: - 73 FR 435110 -EPA seeks comment on the merits of requiring down-hole shut-off 

valves in geosequestration wells. 

Response: AMWA supports requiring down-hole shut-off valves in all 

geosequestration wells as these valves could provide a line of defense against 

contamination of USDW in the event of a defective injection process. 

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

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

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

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

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

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

warrant their use. However, the Agency believes that offshore Class VI wells present unique 

construction and operational conditions, including isolation from shorelines and the need to 

construct wells through the water column and the subsurface, which may delay response time in 

21
the event of well difficulties. The rule requires, at §146.88(e)(3), that owners or operators of 

offshore wells within State territorial waters install automatic down-hole shut-off systems. EPA 

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

subsurface fluid movement and ensure protection of USDWs. 

Letter ID: 0213 Comment ID: 22947 Letter Lines: 376 to 397 

Comment Code: 4322 2.4.4.1.1 Comments in favor of requiring injection below the lowermost 

USDW 

Comment: - 73 FR 43512 - EPA requests comment on whether CO2 injection should be allowed 

into an injection zone above the lowermost USDW, when the Director determines 

that geologic conditions exist that will prevent fluid movement into adjacent 

USDWs. 

Response: AMWA opposes the injection into any formation above the lowermost 

existing or potential USDW and recommends that EPA take a phased approach and 

prohibit the construction of CO2 sequestration wells in aquifers currently used 

for drinking water supply or expected to be used in the future, until more is 

known about the risks of CO2 sequestration to USDWs as a result of the effects 

and dynamics of the fluid in the subsurface. Congress intended the UIC program 

to protect sources and potential sources of drinking water from contamination: 

"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." SDWA § 1421(d)(2); 42 U.S.C. § 300h(d)(2). 

AMWA believes that allowing the injection of CO2 above a USDW would endanger the 

USDW by providing a pathway for CO2 to contaminate a drinking water source, 

especially if a well was constructed through a CO2 plume. 

Individual Response: EPA agrees that protecting USDWs from endangerment must be a top 

priority. The Agency believes that there are limited circumstances where injection above the 

lowermost USDW can be performed in a manner that protects USDWs, 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 nonUSDW formations above and/or between USDWs. The waiver approach requires the submission 

of extensive, site-specific information (in conjunction with the permit application submission) to 

demonstrate that injection of CO2 into a non-USDW that is above or between USDWs can be 

done in a manner that is protective of USDWs. It establishes: 1) requirements specifying 

information that owners or operators must submit, and Directors must consider, in consultation 

with PWSS Directors; 2) procedures for public notice of a waiver application and for DirectorRegional Administrator communication; 3) the waiver issuance process; and, 4) additional 

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

22
injection depth requirements to ensure USDW protection above and below the injection zone. 

EPA believes that the requirements at §146.95 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: 0213 Comment ID: 22948 Letter Lines: 399 to 407 

Comment Code: 4470 2.4.4.4.2 Comments opposing aquifer exemptions in all cases 

Comment: - 73 FR 43512 - EPA is also requesting comment on whether aquifer exemptions 

should be allowed for the purpose of Class VI injection, and under what 

conditions should such aquifer exemptions be approved. 

Response: AMWA does not believe it is prudent to allow for aquifer exemptions 

for the purpose of Class VI injection as saline aquifers not currently used for 

USDWs could be considered viable drinking water supply in a water-stressed 

environment. AMWA strongly believes that the use of an aquifer for drinking 

water supply should take precedence over all other municipal or industrial uses. 

Individual Response: EPA believes that there are limited circumstances where aquifer 

exemptions for GS may be warranted, and the final GS rule allows for the expansion of the areal 

extent of existing aquifer exemptions for Class II EOR/EGR wells transitioning to Class VI 

injection for GS pursuant to requirements at §§146.4 and 144.7(d). Class VI owners or operators 

granted expansions of existing Class II EOR/EGR aquifer exemptions for GS projects must meet 

all of the tailored requirements for GS wells in the final GS rule. 

If an owner or operator applies for a Class VI permit to inject CO2 into a previously exempted 

aquifer (non-USDW) that is located above and/or between USDWs, the permit applicant must 

also apply for a waiver of the injection depth requirements pursuant to §146.95 to ensure that if a 

waiver is granted, USDWs above and below the injection zone are protected from endangerment. 

The Agency developed the waiver process to address comments and concerns about current and 

future drinking water resources and the use of climate mitigation technology at appropriate sites. 

The aquifer exemption requirements in the final rule provide flexibility and afford owners or 

operators an opportunity to assess and select a suitable GS site while also preserving USDWs 

23
(i.e., formations/aquifers afforded SDWA protection). Class VI owners or operators granted 

expansions of existing Class II EOR/EGR aquifer exemptions for GS projects must meet all of 

the tailored requirements for GS wells in the final GS rule. EPA agrees with the commenter's 

concerns about USDW preservation and protection and believes that, in most cases, the injection 

depth waiver is a more appropriate option than aquifer exemptions for Class VI injection, and 

that aquifer exemption expansions for GS should be granted in limited circumstances. 

EPA agrees that future water resources needs are an important consideration, and believes that 

the injection depth waiver process at §146.95 responds to concerns about future drinking water 

resource availability and the need to ensure high quality water remains available in sufficient 

quantities to supply drinking water supply needs. 

For additional information on the waiver approach and aquifer exemptions for Class VI wells, 

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: 0213 Comment ID: 22949 Letter Lines: 409 to 428 

Comment Code: 5700 2.12 Comments on the proposed duration of Class VI permits (seeking 

comment) 

Comment: - 73 FR 43523 -EPA proposes that Class VI injection well permits would be issued 

for the operating life of the GS project including the post-injection site care 

period. EPA seeks comment on the merits of this approach. 

Response: AMWA does not support issuing an operating permit for the life of the 

sequestration site. Instead, AMWA recommends issuing a lifetime operating 

permit for the coal plant, but with a separate and renewable permit for the 

operation of the geologic sequestration process. Drinking water treatment plants 

must notify state regulators of changes in ownership, management, or operations, 

and AMWA recommends that owner/operators of CCS sites be required to provide the 

same type of information to the Director in the event of changes. In addition, 

AMWA recommends that owner/operators be required to periodically reevaluate 

their injectate stream for any emerging contaminants, and remove them if 

required. 

As CCS is a developing technology, AMWA recommends that EPA have a plan to 

update the regulation as additional information is gathered through research and 

through data and observations collected from permitted sites. Having a permit 

renewal schedule built into the process will allow the Director to ensure that 

updates to the regulation are included in permit renewals. AMWA also suggests 

Individual Response: The final rule maintains the lifetime permit provision and clarifies that the 

permit extends through the post-injection site care period (144.36(a)). However, 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 

24
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. 

EPA adds that, as part of existing requirements at 40 CFR 144.39, 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 are 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. 

EPA notes that monitoring of the injectate stream is required under the monitoring and testing 

plan developed under 40 CFR 146.90; operators or owners must include injectate data in their 

semi-annual reports to the Director. 

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. 

EPA believes that these changes will address many comments in support of permit renewal. 

Additionally, the reevaluation process could be aligned with issuance of other environmental 

permits associated with the facility, provided the minimum reevaluation frequency requirements 

are met. EPA clarifies that it does not have the authority under the SDWA (and associated UIC 

requirements) to alter permitting requirements issued under other environmental statutes for coal 

plants or any CO2 sources. The UIC program's authority is limited to the injection operation and 

ensuring that USDWs are protected from endangerment. 

Letter ID: 0213 Comment ID: 22950 Letter Lines: 428 to 431 

Comment Code: 4710 2.7.1 Proposed submissions required for permit applications (seeking 

comment) 

Comment: updates to the regulation are included in permit renewals. AMWA also suggests 

that the permit application process include a review of the site operations to 

see if any instances of unsafe operation or changes in regulation would require 

25
a change in the plant operation. 

Individual Response: EPA agrees that review of site operations is important and expects that 

the reevaluations of the site plans will provide such review. For example, the AoR reevaluations 

offer a good opportunity to promote a dialogue between the owner or operator and the permitting 

authority. 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. 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. Please see the final rule and the discussion of AoR 

reevaluations in the preamble for additional information. 

Letter ID: 0213 Comment ID: 22951 Letter Lines: 433 to 441 

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

Comment Code: 5260 2.8.2.3 Adjusting the post-injection timeframe (seeking comment) 

Comment: - 73 FR 43519 -EPA requests comment on the proposed use of a tentative 50-year 

fixed [post injection site care] timeframe that could be modified at the 

Director’s discretion based on monitoring and modeling data. 

Response: AMWA supports a minimum 50-year time frame for post-injection site 

care and recommends that the Director not be given any discretion to shorten 

this time period. EPA notes in the proposal that "the potential risks of 

endangering USDWs will not decline within that timeframe given that 

stabilization may continue for several decades." AMWA also recommends that 

Individual Response: EPA disagrees that the Director should not have discretion to shorten or 

lengthen the post-injection site care monitoring period. EPA believes that 50 years is an 

appropriate default post-injection site care timeframe. However, EPA recognizes that there may 

be sites where the 50 year post injection site care timeframe may be either not appropriate or 

more burdensome than necessary based on site-specific conditions. For this reason, the GS rule 

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

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

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

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

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

§146.93(c). 

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

for post-injection site care will be necessary in most cases. The default 50 year post-injection site 

care timeframe represents a reasonable and protective monitoring period based on a review of 

26
research studies, industry reports, and existing environmental programs, and evaluation of public 

comments. 

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

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

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

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

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

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

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

impacts. 

Letter ID: 0213 Comment ID: 22952 Letter Lines: 441 to 445 

Comment Code: 1510 1.2.2.3 Need for additional study 

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

Comment: stabilization may continue for several decades." AMWA also recommends that 

additional research be conducted to better understand the movement of CO2 plumes 

and that EPA provide guidance to owner/operators about the criteria for 

monitoring and modeling data that would be necessary to demonstrate that the 

plume has stabilized and justify site closure. 

Individual Response: EPA is developing guidance to assist owners or operators in evaluating 

well plugging, post-injection site care, and site closure requirements of §146.92 and §146.93. 

Additionally, the guidance will assist Directors in evaluating proposed well plugging plans and 

post-injection site care and site closure plans under §146.92 and §146.93. The guidance describes 

recommended approaches for how an owner or operator could plug injection and monitoring 

wells; perform post-injection monitoring; demonstrate non-endangerment; and perform site 

closure activities. The guidance will be available at 

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

EPA agrees that continued research in all GS associated fields will be integral to development of 

GS technology. EPA plans to, every six years, collect and review project data on early GS 

projects, including site characterization, operational, monitoring, and modeling data, 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. 

For additional information on these requirements, please also see the discussion of testing and 

monitoring under EPA’s Final Regulatory Approach in the preamble to the final GS rule. 

Letter ID: 0213 Comment ID: 22953 Letter Lines: 449 to 453 ; 459 to 464 

Comment Code: 1510 1.2.2.3 Need for additional study 

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Comment: In conclusion, AMWA again stresses the need for more research using the improved 

groundwater modeling techniques and variable density flow models for deeper 

aquifers now available. In addition, EPA must gather data now and in the future 

to better understand the behavior of CO2 plumes and the interaction between 

water, CO2 and bedrock formations. Above all, drinking water needs should be 

AMWA appreciates the opportunity to comment on EPA’s proposal. GHG reduction 

and mitigation measures including carbon sequestration are, understandably, very 

important issues to our members. As CCS technology has not been widely deployed 

in the U.S. to date, AMWA urges EPA and DOE to continue to perform the research 

suggested in these comments as well as follow-up assessments of the technology 

once deployed. 

Individual Response: EPA agrees that continued research in all GS associated fields will be 

integral to development of GS technology. EPA published a Notice of Data Availability (NODA) 

and Request for Comment on August 31, 2009 (74 FR 44802), in which EPA described a study 

by the Lawrence Berkeley National Laboratory on the potential effects of CO2 injection, 

including far-field pressure effects, on ground water and surrounding formations to determine the 

potential for impacts on USDWs and human health in the event that a GS project is not properly 

sited, operated, or managed. 

Letter ID: 0213 Comment ID: 22954 Letter Lines: 453 to 457 

Comment Code: 1610 1.3.1 Risks to USDWs 

Comment: water, CO2 and bedrock formations. Above all, drinking water needs should be 

considered paramount and EPA should consider the future drinking water needs of 

the country in light of climate change. EPA’s final rule should protect current 

and future USDWs from unintended consequences of CO2 geosequestration and moral 

hazard. 

Individual Response: As described above, The Agency agrees that drinking water is an 

important resource to protect. The primary goal of the UIC Program under the SDWA is to 

protect USDWs from endangerment. Consistent with SDWA §1422, the UIC program provides 

that no injection shall be authorized if it results in the movement of fluid containing any 

contaminant into USDWs, if the presence of that contaminant may cause a violation of any 

primary drinking water regulation or may adversely affect the health of persons as specified in 

§144.12. 

The GS rule, as part of the UIC program regulations, continues the Program’s mandate under the 

SDWA of ensuring the protection of USDWs from endangerment. EPA expects that the tailored 

permitting, siting, construction, operation, monitoring, and post-injection site care requirements 

in the GS rule will prevent leakage from injection formations and protect USDWs. 

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29

Letter ID: 0213 Comment ID: 22955 Letter Lines: 466 to 473 

Comment Code: 1210 1.1.1 Comments about the proposed rule 

Comment: AMWA also recommends that EPA commit to update the rule regularly as more 

becomes known about CCS technology and the behavior of CO2 injected into the 

subsurface. AMWA recommends that EPA work to update the rule every three to five 

years for the foreseeable future, as this technology will become more prevalent 

and injection methods and other sequestration techniques will likely improve. 

In developing this proposal, EPA has demonstrated its ability to quickly bring 

staff up to speed on this technology and AMWA believes the Agency must continue 

chnological advances. 

Individual Response: EPA agrees that an adaptive approach to the UIC GS rulemaking is 

appropriate. The Agency will use such an 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. 

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.