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 capacity of the underground reservoir 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 the formation is capable of long term 

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

and possibly re-enter the atmosphere. 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 costly contamination of groundwater. 

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

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

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

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

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

information under §146.82(a)(21). 

While developing the GS regulation, EPA evaluated relevant GS research, including projects 

conducted by the seven regional carbon sequestration partnerships funded by the U.S. 

Department of Energy (DOE) and coordinated through the National Energy Technology 

Laboratory (NETL), and several international projects. Additionally, EPA's Office of Water 

continues to fund research at the Lawrence Berkeley National Laboratory examining the effects 

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

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

institutions including, among others, Princeton University, Massachusetts Institute of 

Technology, and Montana State University, where specific research on geologic sequestration, 

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

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

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

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

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

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

UIC program, which has been regulating the injection of billions of gallons of fluids for decades. 

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

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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. These 

additional protective requirements include more extensive geologic testing, detailed 

computational modeling of the AoR and periodic re-evaluations, detailed requirements for 

monitoring and tracking the CO2 plume and pressure front, and extended 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 CO2; purity standards for CO2 

Comment Code: 1616 1.3.1.3 Fluid movement 

Comment: 2. The fluid to be injected into the ground may contain pollutants carried with 

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

the first bullet above. Gases could be injected 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 source of drinking water. 

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

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

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

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

site characterization, well construction, 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 about the site (during the site characterization 

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

the injection and confining zones, along with information 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 potential 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) and the properties of the CO2, e.g., injection volumes and rates. 

Identification of potential reactions prior to injection would address concerns that formation of 

carbonic acid could dissolve potential limestone creating karst features. 

During injection operations, operators must extensively 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 responsibility to address contamination as specified 

in §146.85. 

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Letter 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/gas field, but CO2 injection will outlast 

a producing field and may not have been constructed 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 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 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, mechnical 

integrity testing, etc.) must be met following 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 provide 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 "containment 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 greenhouse 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 acknowledges that these issues are important and is 

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

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

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

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greenhouse 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 assessing the geologic sequestration permit 

submissions, evaluating the technical models, and making permitting 

determinations. Financial resource considerations should accompany eventual 

promulgation of the rule in order to ensure 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 acquiring 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 that 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 are 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 opportunity to comment on this proposed 

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

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

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

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

the rulemaking docket. 

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