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.
Proposed Waiver Process

We applaud the EPA for listening to criticisms from knowledgeable scientists and engineers regarding

the unwarranted and technically indefensible position prohibiting CO2 injection above and between

USDWs, which the EPA issued in its original July 25, 2008, proposed rule, ‘‘Federal Requirements Under

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

Wells’’.  Furthermore, we strongly concur with the core principle articulated in this NODA that all

geologic formations receive equal treatment and the rule should allow specific regions of the country

the regulatory flexibility to determine if any injection at a particular site and depth is the appropriate

approach.  Unfortunately, the proposed waiver process and specifically the extraordinary set of

additional technical and financial requirements imposed through the waiver process clearly violate these

principles by establishing a set of virtually insurmountable barriers for any owner/operator seeking a UIC

permit for a GS project through the waiver process.  The EPA has cited no technical evidence to suggest

elevated risk factors from properly sited GS projects conducted above or between USDWs that would

justify imposition of the additional site characterization, emergency response planning, financial liability,

alternative water resource planning, and the many other additional requirements outlined in this draft

NODA.  We strongly urge the EPA to draft a single and consistent set of requirements that all GS

sequestration projects must meet to ensure site suitability.

There is precedent supporting a single set of requirements approach.  The European Union issued a

directive in April 2009 that established the legal framework for the geological storage of CO2 (Directive

2009/31/EC).  This directive delineates the objectives for GS projects that must be reached by member

states in a reasonable time. However, each State is allowed to adapt its domestic law to the objectives

of the directive. Several EU States, including the UK, have already endorsed most all of these objectives.  

The EU Directive concerning the selection of storage sites provides a list of criteria that must be fulfilled

to determine if a geological formation is suitable or not.  There are no constraining criteria in terms of

depth relationships with any USDW.  The potential storage complex and surrounding area must be

characterized and article 4.4 says “A geological formation shall only be selected as a storage site if under

the proper conditions of use there is no significant risk of leakage and if no environmental or health risk

exists”. There is no other constraint.  Similarly, Australia was the first country in 2005 to endorse new

regulatory guidelines for CCS, and these guidelines do not impose depth criteria for the selection of

suitable CO2 storage sites and further emphasize establishment of a consistent regulatory framework for

CCS projects.1

  Finally, new reservoir engineering approaches are being considered2 that eliminate a free

CO2 phase in the target reservoir and thus could obviate virtually any risk to USDWs.  Consequently, we

emphasize again the importance of drafting a single set of consistent regulations that treat all potential

                                                           

1 Carbon Dioxide Capture and Geological Storage, Australian Regulatory Guiding Principles, Ministerial Council on

Mineral and Petroleum Resources, 2005.

2 Burton, M. and S. L. Bryant.  2009.  "Surface Dissolution: Minimizing Groundwater Impact and Leakage Risk

Simultaneously."  Energy Procedia 1(1):3707‐3714.
geologic formations equally and without imposition of additional unwarranted and arbitrary

requirements based on position in the subsurface with respect to USDWs.

Mischaracterization of Basalts and Coal Seams

The EPA NODA on pg. 44808 and 44809 refers to basalts and coal seams as examples of “shallow”

formations impacted by the proposed depth requirement in the draft regulations.  While shallow basalts

and coal seams certainly exist, so do shallow saline aquifers as well (i.e. the Coconino aquifer in Arizona).  

None of these shallow formations would be suitable sequestration targets.  In contrast, deep basalt (and

coal seams) exist that appear to offer suitable if not significantly lower long‐term risk (due to rapid

mineralization and other permanent sequestration mechanisms) than exist in other reservoirs.  

Moreover, a cursory look at the literature would quickly show that in the Pacific Northwest for example,

flood basalt formations extend in the deepest parts of the region up to 16,000 ft bgs.  Hence,

characterization of these formations as “shallow” is demonstrably false, and misleading to the public.

Also on pg. 44811 under Site Characterization, the following statement is made: “..and appropriate soil‐

rock chemistry (so as to ensure that the injection matrix is not dissolved as a result of injection);”.  EPA

provides no context, limits, or constraints on this requirement, which again would only apply to those

seeking a waiver under these draft rules.  First, the perturbation in groundwater chemistry induced from

CO2 injection virtually guarantees that some amount of matrix dissolution will occur in any foreseeable

type of geologic reservoir.  A strict legal interpretation of this statement would potentially exclude all

reservoirs in the U.S. for GS.  In reality, matrix dissolution reactions are inherently limited due to slow

dissolution kinetics in most reservoirs and the high SiO2 content of most siliclastic and volcanic rocks of

interest for GS.  In basalts, some matrix dissolution is desired as it is a precursor step towards eventual

precipitation of carbonate minerals that permanently sequester the CO2 in these reservoirs.  EPA

statement regarding a matrix dissolution requirement should at least be heavily caveated but

preferentially removed in any future drafts of these regulations.

B. Peter McGrail, Laboratory Fellow

Pacific Northwest National Laboratory

Alain Bonneville, Senior Staff Scientist

Pacific Northwest National Laboratory

(Formerly VP of Institut de Physique du Globe, France)
Letter ID: 0375  

Commenter: B. Peter McGrail  

Organization: Pacific Northwest National Laboratory  

Letter ID: 0375 Comment ID: 28160 Letter Lines: 19 to 39  

Comment Code: 3220 3.2.2. Comments in Opposition to the Approach  

Comment: We applaud the EPA for listening to criticisms from knowledgeable scientists and  

engineers regarding the unwarranted and technically indefensible position  

prohibiting CO2 injection above and between USDWs, which the EPA issued in its  

original July 25, 2008, proposed rule, "Federal Requirements Under the  

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

Sequestration (GS) Wells". Furthermore, we strongly concur with the core  

principle articulated in this NODA that all geologic formations receive equal  

treatment and the rule should allow specific regions of the country the  

regulatory flexibility to determine if any injection at a particular site and  

depth is the appropriate approach. Unfortunately, the proposed waiver process  

and specifically the extraordinary set of additional technical and financial  

requirements imposed through the waiver process clearly violate these principles  

by establishing a set of virtually insurmountable barriers for any  

owner/operator seeking a UIC permit for a GS project through the waiver process.  

The EPA has cited no technical evidence to suggest elevated risk factors from  

properly sited GS projects conducted above or between USDWs that would justify  

imposition of the additional site characterization, emergency response planning,  

financial liability, alternative water resource planning, and the many other  

additional requirements outlined in this draft NODA. We strongly urge the EPA to  

draft a single and consistent set of requirements that all GS sequestration  

projects must meet to ensure site suitability.  

Individual Response: EPA believes there is potential risk associated with injection into non‐USDW

formations above the lowermost USDW and additional requirements are warranted. For example, there

is a risk of downward migration of fluids if there is no lower confining layer or inadequate confinement.

In addition, there is the potential that wells will be drilled through the injection zone in the future to

reach the USDW. EPA believes that the additional requirements that apply to owners or operators of

Class VI wells granted a waiver of the injection depth requirements at §146.95 will provide additional

information when permitting such wells to ensure protection of all USDWs.  
Letter ID: 0375 Comment ID: 28161 Letter Lines: 37 to 74  

Comment Code: 3200 3.2. Comments on Alternative Injection Depth Waiver Approach  

Comment: additional requirements outlined in this draft NODA. We strongly urge the EPA to  

draft a single and consistent set of requirements that all GS sequestration  

projects must meet to ensure site suitability.  

There is precedent supporting a single set of requirements approach. The  

European Union issued a directive in April 2009 that established the legal  

framework for the geological storage of CO2 (Directive 2009/31/EC). This  

directive delineates the objectives for GS projects that must be reached by  

member states in a reasonable time. However, each State is allowed to adapt its  

domestic law to the objectives of the directive. Several EU States, including  

the UK, have already endorsed most all of these objectives.  

The EU Directive concerning the selection of storage sites provides a list of  

criteria that must be fulfilled to determine if a geological formation is  

suitable or not. There are no constraining criteria in terms of depth  

relationships with any USDW. The potential storage complex and surrounding area  

must be characterized and article 4.4 says "A geological formation shall only be  

selected as a storage site if under the proper conditions of use there is no  

significant risk of leakage and if no environmental or health risk exists".  

There is no other constraint. Similarly, Australia was the first country in 2005  

to endorse new regulatory guidelines for CCS, and these guidelines do not impose  

depth criteria for the selection of suitable CO2 storage sites and further  

emphasize establishment of a consistent regulatory framework for CCS projects.[FOOTNOTE 1]  

Finally, new reservoir engineering approaches are being considered [FOOTNOTE 2] that  

eliminate a free CO2 phase in the target reservoir and thus could obviate  

virtually any risk to USDWs. Consequently, we emphasize again the importance of  

drafting a single set of consistent regulations that treat all potential  

geologic formations equally and without imposition of additional unwarranted and  

arbitrary requirements based on position in the subsurface with respect to  

USDWs.  

FOOTNOTE 1 ‐ Carbon Dioxide Capture and Geological Storage, Australian  

Regulatory Guiding Principles, Ministerial Council on Mineral and Petroleum  

Resources, 2005.  

FOOTNOTE 2 ‐ Burton, M. and S. L. Bryant. 2009. "Surface Dissolution: Minimizing  

Groundwater Impact and Leakage Risk Simultaneously." Energy Procedia  

1(1):3707‐3714.  
Individual Response: EPA clarifies that GS projects that operate under injection depth waivers must

meet the same requirements as other Class VI wells; the purpose of the waiver requirements at §146.95

is to provide additional considerations for wells injecting above or between USDWs to ensure protection

of all USDWs. The waiver process allows for flexibility and does not preclude any formations, instead

relying on site characterization, well construction, maintenance, monitoring, and post site closure care.  

EPA adds that it is monitoring the progress of international research and legislative developments; a

paper summarizing EPA's research on international GS projects and legislation is in the rulemaking

docket.  

Letter ID: 0375 Comment ID: 28162 Letter Lines: 76 to 89  

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

Comment: Mischaracterization of Basalts and Coal Seams  

The EPA NODA on pg. 44808 and 44809 refers to basalts and coal seams as examples  

of "shallow" formations impacted by the proposed depth requirement in the draft  

regulations. While shallow basalts and coal seams certainly exist, so do shallow  

saline aquifers as well (i.e. the Coconino aquifer in Arizona). None of these  

shallow formations would be suitable sequestration targets. In contrast, deep  

basalt (and coal seams) exist that appear to offer suitable if not significantly  

lower long‐term risk (due to rapid mineralization and other permanent  

sequestration mechanisms) than exist in other reservoirs. Moreover, a cursory  

look at the literature would quickly show that in the Pacific Northwest for  

example, flood basalt formations extend in the deepest parts of the region up to  

16,000 ft bgs. Hence, characterization of these formations as "shallow" is  

demonstrably false, and misleading to the public.  

Individual Response: EPA recognizes that aquifers, coal seams, and basalts can be found both at shallow

and deep depths. EPA believes that, in some cases these formations can be used for GS, and the waiver

process in the final GS rule at §146.95 provides additional capacity where these types of formations are

shallow and protection of USDWs can be demonstrated.  

Letter ID: 0375 Comment ID: 28163 Letter Lines: 92 to 107  

Comment Code: 3310 3.3.1. Site Characterization  
Comment: Also on pg. 44811 under Site Characterization, the following statement is made:  

"..and appropriate soilrock chemistry (so as to ensure that the injection matrix  

is not dissolved as a result of injection);". EPA provides no context, limits,  

or constraints on this requirement, which again would only apply to those  

seeking a waiver under these draft rules. First, the perturbation in groundwater  

chemistry induced from CO2 injection virtually guarantees that some amount of  

matrix dissolution will occur in any foreseeable type of geologic reservoir. A  

strict legal interpretation of this statement would potentially exclude all  

reservoirs in the U.S. for GS. In reality, matrix dissolution reactions are  

inherently limited due to slow dissolution kinetics in most reservoirs and the  

high SiO2 content of most siliclastic and volcanic rocks of interest for GS. In  

basalts, some matrix dissolution is desired as it is a precursor step towards  

eventual precipitation of carbonate minerals that permanently sequester the CO2  

in these reservoirs. EPA statement regarding a matrix dissolution requirement  

should at least be heavily caveated but preferentially removed in any future  

drafts of these regulations.  

Individual Response: EPA clarifies that the GS regulation requires all owners or operators to submit

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

confining zones and on the compatibility of the CO2 stream with fluids in the injection zone and

minerals in both the injection and confining zones at §146.82(c)(3). The data can help the Director

determine the potential for geochemical reactions between the injectate (CO2) and the host geologic

formations, which could result in the plugging of pore spaces or the dissolution of formation minerals.

For additional information on site characterization for GS projects, see the preamble to the final rule and

the responses to comments on the proposed GS rule.

EPA is developing guidance on site characterization of GS sites to assist owners or operators and

Directors in evaluating the requirements under §146.82. The guidance will be available on EPA’s website

at water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.