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.Letter ID: 0222

Commenter: Jonathon Palm

Organization: Nevada Division of Environmental Protection, Bureau of Water Pollution Control

Letter ID: 0222 Comment ID: 21640 Letter Lines: 38 to 47

Comment Code: 1510 1.2.2.3 Need for additional study

Comment Code: 1800 1.4 Scientific Background/Informing the Proposal

Comment: 1. Before a project can be approved, there must be an accurate determination of

the integrity and cap acity of the underground reservoi r that is to receive the

injected fluids. At this time, it does not appear that the required expertise

and good science are available and will be used in the evaluation of the

underground reservoir to verify that th e formation is capab le of long term

storage. If the integrity is not realized , the Co2 and other gasses would escape

and possibly re-enter the at mosphere. No benefit to the reduction of greenhouse

gasses would be realized, or, worse, some unforeseen, negative consequence would

result. Recall the MTBE issue where the remedy to an air pollution problem

turned out to be a widespread and co stly contamination of groundwater.

Individual Response: EPA clarifies that the permitting requirements at §146.82 require an

extensive evaluation of the ge ologic conditions at a proposed GS site to demonstrate the

suitability of a potential project site for GS. If adequate maps a nd cross sections do not exist to

support a thorough evaluation of th e site, the owner or operator must produce the information

(e.g., through additional, new studies), and the Di rector has the authority to request additional

information under §146.82(a)(21).

While developing the GS regulation, EPA evaluate d relevant GS research , including projects

conducted by the seven regional carbon seque stration partnerships funded by the U.S.

Department of Energy (DOE) and coordina ted through the National Energy Technology

Laboratory (NETL), and several international pr ojects. Additionally, EP A's Office of Water

continues to fund research at the Lawrence Berk eley National Laboratory examining the effects

of CO2 interaction on ground water aquifers an d any potential mobilization of trace elements

that may occur. EPA is communicating with other research organizations and academic

institutions including, among others, Princet on University, Massachusetts Institute of

Technology, and Montana State University, wher e specific research on geologic sequestration,

injection well materials, and CO2 monitoring tech niques is in progress. EPA is also working

with DOE, USGS, and others to identify tools and training techniques th at will provide GS

permitting assistance and technical expertise as appropriate. Additionally, EPA's Office of

Research and Development (ORD) is undert aking multiple research efforts on GS.

EPA disagrees that GS is analogous to the MTBE experience. EPA believe s that large scale GS

can be done safely: the GS regulation builds upon the long-standing protec tive framework of the

UIC program, which has been regulati ng the injection of bill ions of gallons of fluids for decades.

The GS regulation enhances this framework with requirements for GS wells that are tailored to

1address the unique issues associ ated with large-scale GS incl uding large injection volumes, the

relative buoyancy of CO2, its corro sivity in the presence of water, the potential presence of

impurities in captured CO2, and its mobility with in subsurface geologic formations. These

additional protective requirements include more extensive geologi c testing, detailed

computational modeling of the AoR and period ic re-evaluations, de tailed requirements for

monitoring and tracking the CO2 plume and pressure front, and ex tended post-injection

monitoring and site care.

Letter ID: 0222 Comment ID: 21641 Letter Lines: 49 to 54

Comment Code: 1614 1.3.1.2 Impurities in captured CO 2; purity standards for CO2

Comment Code: 1616 1.3.1.3 Fluid movement

Comment: 2. The fluid to be injected into the gr ound may contain polluta nts carried with

the CO2 that potentially could enter a dr inking water source. This follows from

the first bullet above. Gases could be in jected into a confined space with

insufficient capacity for the volume of gas to be injected. Pressure would build

up as more gas is pumped in, forcing a breach in the reservoir. Pollutants could

escape and migrate into a s ource of drinking water.

Individual Response: EPA acknowledges that there are pote ntial risks associated with GS,

including the potential that CO2 injection for GS may result in leaching of subsurface materials

that could mobilize contaminants or compromi se pore space and endanger USDWs. The purpose

of the Class VI requirements is to minimize a nd mitigate potential/identified risks through proper

site characterization, well constr uction, operation, monitoring, post- injection site care, and site

closure. To ensure USDW protection and mitigate risks, the GS regulation requires the owner or

operator of a Class VI well to submit data abou t the site (during the site characterization

process), including information on the porosity, permeability, mineralogy, and geochemistry of

the injection and confining zones, along with info rmation on the compatibility of the CO2 stream

with fluids in the injection zone and minerals in both the injection and confining zones as

specified in §146.82. This data can help identify pot ential geochemical reactions that may occur

between the injected CO2 and the host geologic formation, as well as help determine the capacity

of the proposed injection formation. EPA adds that computational AoR modeling, required at

§146.84, must account for the physical properties of the receiving formation (based on the

collected data described above) a nd the properties of the CO2, e .g., injection volumes and rates.

Identification of potential reactions prior to inj ection would address concerns that formation of

carbonic acid could dissolve potential limestone creating karst features.

During injection operations, opera tors must extensivel y monitor ground water quality to provide

early detection of any unacceptable movement of fluids or impurities in the subsurface as

specified in §146.90. Operators must develop and follow an emergency and remedial response

plan to address any adverse effects associated with the GS operation, including contamination as

specified in §146.94, and provide financial responsib ility to address contamination as specified

in §146.85.

2Letter ID: 0222 Comment ID: 21642 Letter Lines: 56 to 60

Comment Code: 2064 1.5.3.2 Grandfathering construction of Class II wells (seeking comment)

Comment Code: 2066 1.5.3.3 Grandfathering construction of Class V wells (seeking comment)

Comment: 3. Existing Class II & V wells should not be grandfathered in on long-term CO2

injection projects. Injection into a Class II oil well may be appropriate for

short-term project in a producing oil/ga s field, but CO2 injection will outlast

a producing field and may not have been c onstructed to specs. All CO2 wells must

be specifically designed.

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

particularly given that the convert ed well will be used for a substa ntially different process, which

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

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

these wells to be grandfathered, per §146.81(c). EP A has included a requirement in the final GS

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

demonstrate to the Director that the grandfathe red wells were engineered and constructed meet

the requirements at §146.86(a) and ensure prot ection 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, mechnical

integrity testing, etc.) must be met fo llowing a determination under §146.81(c).

Letter ID: 0222 Comment ID: 21643 Letter Lines: 62 to 64

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

ownership

Comment: 4. An applicant for CO2 credits must provi de a clear demonstration of longterm

CO2 containment. If the CO2 cannot be contained in a geological formation

indefinitely, then the operator should not receive a credit.

Individual Response: EPA clarifies that setting a "containmen t standard" is outside the scope of

the Class VI GS rulemaking. However, the Class VI GS rule requires that CO2 injected for GS

remain confined in the injection zone. Leakage outside of the injection zone/to the surface would

be a permit violation. 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 endangerment of USDWs in anticipation of the eventual use of GS to

reduce CO2 emissions.

EPA clarifies that carbon crediting and greenhous e gas accounting are outside the scope of the

Class VI GS rulemaking. The Class VI GS rule is designed to ensure the protection of USDWs

from endangerment. However, the Agency acknowle dges that these issues are important and is

addressing them using other regulatory authoritie s. For example, in a separate rulemaking under

authority of the Clean Air Act, EPA is ame nding the Greenhouse Gas Reporting Program at 40

CFR Part 98 to add reporting requirements fo r CO2 injection and geologic sequestration. The

3greenhouse gas reporting requirements build on the requirements outlined in the Class VI GS

rule with the additional goals of verifying the amount of CO2 sequestered and collecting data on

any CO2 emissions to the surface from Class VI GS facilities.

Letter ID: 0222 Comment ID: 21644 Letter Lines: 66 to 71

Comment Code: 1200 1.1 General comments about the rulemaking

Comment Code: 5600 2.11 Comments related to UIC Program primacy for Class VI wells

Comment: 5. In implementing this rule, the state will be encumbered with increased

financial and resource burdens in asse ssing the geologic sequestration permit

submissions, evaluating the techni cal models, and making permitting

determinations. Financial resource cons iderations should accompany eventual

promulgation of the rule in order to en sure adequate funding for these various

tasks.

Individual Response: EPA acknowledges that there may be technical and administrative

challenges including resource concerns , and will work closely with the states to assist them in

resolving funding issues or acquiri ng the resources, personnel, and training needed to address the

unique technical challenges associated with GS.

EPA will also incorporate Class VI wells into the UIC Program's grant allocation process. The

States/Tribes/Territories must also demonstrate th at they have adequate resources to implement

the program through matching resources against those allocated by the UIC Program's grant

allocation formula. Currently, primacy programs ar e required to meet a minimum of 25 percent

matching requirement.

Letter ID: 0222 Comment ID: 21645 Letter Lines: 73 to 75

Comment Code: 1000 1. General and Administrative Comments

Comment: NDEP also supports the comments submitted by the Association of State Drinking

Water Administrators. Thank you for the oppor tunity to comment on this proposed

rule. If you need any additional information, please contact me.

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

responses to this comment and ASDWA’s comm ent for further details. For additional

information on EPA's final regulatory approach, pl ease see the final rule and preamble as well as

the rulemaking docket.

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