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.
Due to the mobility and corrosive nature of CO2, sequestration should be below the lowest USDW. 

Not all geologic provinces in the U.S. are suitable for CO2 sequestration. 

‐Comment submitted by William E. Freeman, Navajo Nation USEPA Underground Injection Control 

(UIC) Program, Shiprock, New Mexico (NM) 
Letter ID: 0341  

Commenter: William E. Freeman  

Organization: Navajo Nation  

Letter ID: 0341 Comment ID: 28024 Letter Lines: 17 to 20  

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

Comment: Comment:  

Due to the mobility and corrosive nature of CO2, sequestration  

should be below the lowest USDW. Not all geologic provinces in the U.S. are  

suitable for CO2 sequestration.  

Individual Response: EPA agrees that not all regions are suitable for GS. However, based on an

evaluation of comments on the proposed injection depth requirements and the waiver process

discussed in the NODA, and concerns about USDW protection, EPA believes that there are situations

where injection into non‐USDW formations above the lowermost USDW can be performed in a manner

that protects USDWs. 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. The waiver approach establishes

requirements for extensive site‐specific information related to injecting above or between USDWs that

the owner or operator must submit and the Director must consider, in consultation with PWSS

Directors, to ensure that water supplies in the area and all USDWs are protected. Such decisions will be

made on a case by case basis after reviewing the required data, including proof of continuous confining

layers above and below the proposed injection zone and proof that the injection zone formation does

not outcrop.