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: 0203 

Commenter: Brad Castleberry 

Organization: Water Environment Association of Texas (WEAT) 

Letter ID: 0203 Comment ID: 22178 Letter Lines: 31 to 41 

Comment Code: 1600 1.3 Risk Associated with CO2 GS 

Comment: These comments are submitted on behalf of the Water Environment Association of 

Texas ("WEAT"). Specifically, these comments are submitted in response to the 

above-referenced rulemaking in an effort to urge caution and careful 

consideration before adoption of the proposed regulations. We urge this caution 

in the interest of protecting drinking water sources and groundwater quality. 

WEAT is a non-profit technical trade organization comprised of a number of 

utilities, industries, and individuals in the State of Texas. WEAT's members 

strive to promote sound science, education, and environmental stewardship. There 

are a number of activities in the proposed regulations that could impact 

groundwater quality as well as public drinking water sources. Careful 

Individual Response: EPA believes that injecting large volumes of CO2 for GS poses unique 

challenges that, if not properly managed, could endanger drinking water sources or have other 

adverse impacts. EPA believes that caution is warranted and has, as a result, developed a new 

well class with requirements tailored to address the unique challenges posed by GS and potential 

risks associated long-term injection of CO2. 

Letter ID: 0203 Comment ID: 22179 Letter Lines: 41 to 51 

Comment Code: 3100 2.1 Proposed Geologic Siting Requirements (40 CFR 146.83) 

Comment Code: 4600 2.6 Proposed Plume and Pressure Front Monitoring Requirements (40 

CFR 146.90) 

Comment: groundwater quality as well as public drinking water sources. Careful 

consideration should he given to ensure an adequate assessment is made of each 

proposed injection well site. This consideration should come in the form of 

detailed site studies. sophisticated computer modeling, and other tools used to 

predict hydrogeology. Careful consideration should also he given to ensure that 

adequate ongoing monitoring and reporting is provided for any site ultimately 

permitted pursuant to the proposed rules. Given the unique circumstances 

surrounding this type of pollutant, and the lack of a significant body of longterm evidence to support the proposed activity, we would encourage EPA to 

include significant monitoring and reporting provisions to ensure the long-term 

viability of any permitted site with respect to surrounding groundwater quality. 

Individual Response: EPA agrees with the commenter regarding the importance of site 

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characterization, and believes that the extensive requirements for geologic site characterization 

(at §146.82), AoR evaluation (§146.84), and testing of the well during drilling (§146.87) are 

appropriate to ensure that permitting authorities have the necessary information to evaluate 

whether a specific site will allow safe injection of CO2. EPA adds that submittal and review of 

monitoring data (as required at §146.90) and the AoR reevaluation process (§146.84(e)) will 

provide an opportunity for an ongoing review of the site and a dialogue between the Director and 

the owner or operator to ensure that the project is being operated in a manner that protects 

USDWs from endangerment. 

EPA believes that monitoring plans and methods need to be site-specific and that the monitoring 

requirements for GS sites at §146.90 provide an appropriate level of flexibility in structuring a 

testing and monitoring plan that protects USDWs from endangerment. 

The GS rule, at §146.90, requires injectate monitoring, mechanical integrity testing, corrosion 

monitoring, tracking the CO2 plume and area of elevated pressure, monitoring geochemical 

changes above the confining zone, and, at the discretion of the Director, surface air and soil gas 

monitoring for CO2 fluctuations, and any additional tests necessary to ensure USDW protection 

from endangerment. 

EPA is developing guidance on testing and monitoring to assist owners or operators and 

Directors in evaluating requirements under §146.90, including proposed monitoring plans. The 

guidance describes available technologies and recommended approaches for implementing a 

testing and monitoring plan, including pre-operational geophysical logging and testing of 

injection wells, MITs, injection well testing during operation, groundwater quality monitoring, 

tracking the CO2 plume and pressure front, and soil gas and surface air monitoring which may 

be required by the UIC Director for specific GS projects. The guidance can be found on EPA’s 

website at http://water.epa.gov/type/groundwater/uic/wells_sequestration.cfm.