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.
file:///C|/Users/Kristy/Desktop/KristyMaterials/CommentsToPDF/EPA-HQ-OW-2008-0390-0107.txt[11/18/2010 10:30:21 PM]

Document ID: EPA-HQ-OW-2008-0390-107

Last Name: Blount

First Name: Gerald C.

Title: 

Organization: 

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Current Category Code: 261

Comment: As a concerned practicing geoscientist I believe it is reasonable to

regulate the geologic storage of CO2 by creating a new well class (Class VI)

within the Underground Injection Control (UIC) program and it is necessary to

protect underground drinking water sources. However, it may not be appropriate

to categorically limit storage to formations with water salinity greater than

10,000 parts per million.

Another option should be available in the rule that considers other factors that

may preclude the use of the aquifer as a source of drinking water or nullify

threats to aquifers containing potable water. The USEPA has typically afforded

this type of flexibility with technical documentation and deliberation. Prior to

finalization of this rule it would be very simple and prudent to provide for

another technical path within the process that would not limit technical

strategies for carbon dioxide storage.

If geologic storage of carbon dioxide is limited to formations with water

salinities greater than 10,000 parts per million it is likely that there will be

insufficient storage that is economically viable. Greenhouse gases are an

immediate threat, EPA should regulate but not limit solutions that are

technically viable, or increase costs when it is not necessary. Inflated storage

costs will only cause delay. Global warming is far too great a threat to the

human health and the environment to categorically limit potential CO2 storage

sites.
Letter ID: 0107 

Commenter: Gerald C. Blount 

 

Letter ID: 0107 Comment ID: 21940 Letter Lines: 15 to 20 

Comment Code: 1420 1.2.1.1 Support the GS rulemaking 

Comment Code: 2020 1.5.1 Support Class VI designation 

Comment: As a concerned practicing geoscientist I believe it is reasonable to 

regulate the geologic storage of CO2 by creating a new well class (Class VI) 

within the Underground Injection Control (UIC) program and it is necessary to 

protect underground drinking water sources. However, it may not be appropriate 

to categorically limit storage to formations with water salinity greater than 

10,000 parts per million. 

Individual Response: EPA agrees 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. 

Comments related to redefining or modifying the definition of USDWs under 40 CFR 144.3 are 

outside the scope of the rulemaking. The GS rule, as part of the UIC program regulations, 

continues the program’s tradition of ensuring the protection of USDWs by prohibiting injection 

of carbon dioxide into USDWs. EPA clarifies that all Class VI injection must be into nonUSDWs, which are formations with water salinity greater than 10,000 parts per million. The 

mandate as required by the SDWA of any Federally approved UIC Program (whether 

administered by a State, Territory, Tribe or EPA) is the protection of USDWs. This includes not 

only those formations that are presently being used for drinking water, but also those that can 

reasonably be expected to be used in the future. EPA has established through its UIC regulations 

that USDWs are underground aquifers with less than 10,000 milligrams per liter (mg/L) total 

dissolved solids (TDS) and which contain a sufficient quantity of ground water to supply a 

public water system (40 CFR 144.3). EPA defines saline formations as deep and geographically 

extensive sedimentary rock layers saturated with waters or brines that have a high total dissolved 

solids (TDS) content (i.e., over 10,000 mg/L TDS). 

EPA notes that owners or operators of Class II wells have the option to expand aquifer 

exemptions that have already been granted for purposes of Class VI injection under §144.7(d). 

The owner or operator must meet the requirements found in 146.4(d). 

1
2

Letter ID: 0107 Comment ID: 21941 Letter Lines: 15 to 37 

Comment Code: 4410 2.4.4.3.1 Comments in favor of allowing injection above/between 

USDWs in certain circumstances 

Comment: As a concerned practicing geoscientist I believe it is reasonable to 

regulate the geologic storage of CO2 by creating a new well class (Class VI) 

within the Underground Injection Control (UIC) program and it is necessary to 

protect underground drinking water sources. However, it may not be appropriate 

to categorically limit storage to formations with water salinity greater than 

10,000 parts per million. 

Another option should be available in the rule that considers other factors that 

may preclude the use of the aquifer as a source of drinking water or nullify 

threats to aquifers containing potable water. The USEPA has typically afforded 

this type of flexibility with technical documentation and deliberation. Prior to 

finalization of this rule it would be very simple and prudent to provide for 

another technical path within the process that would not limit technical 

strategies for carbon dioxide storage. 

If geologic storage of carbon dioxide is limited to formations with water 

salinities greater than 10,000 parts per million it is likely that there will be 

insufficient storage that is economically viable. Greenhouse gases are an 

immediate threat, EPA should regulate but not limit solutions that are 

technically viable, or increase costs when it is not necessary. Inflated storage 

costs will only cause delay. Global warming is far too great a threat to the 

human health and the environment to categorically limit potential CO2 storage 

sites. 

Individual Response: EPA recognizes that there is increasing demand for water resources and 

that technology improvements may make high TDS aquifers viable drinking water sources. EPA 

believes these potential resources should be considered when injection depth waivers are sought. 

Therefore, the final GS rule at §146.95(b) requires the Director to consider these issues in 

determining whether an injection depth waiver is appropriate. Specifically, the Director must 

consider whether alternative injection sites are available; community needs, demands, and supply 

from drinking water resources; planned needs, potential and/or future use of USDWs and nonUSDWs in the area; and a plan for securing alternative resources or treating USDW formation 

waters in the event of contamination related to the Class VI injection activity. 

EPA is not changing the USDW definition; changing the definition of a USDW is outside the 

scope of the GS rulemaking. The GS rule focuses on ensuring protection of USDWs, as required 

under the SDWA, by establishing regulations to ensure the safe injection of CO2 for long-term 

storage. 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.