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-2008-0390-0102.txt [11/18/2010 10:28:51 PM] Document ID: EPA-HQ-OW-2008-0390-102

Last Name:

First Name: Rebecca

Title:

Organization: Mendocino County Water Agency, State of California

City:

State: CA

Zip Code:

Phone Number:

Fax Number:

Country Code:

Email Address: mcwa@co.mendocino.ca.us

Current Category Code: 254

Comment: Hi, MaryRose. My name is Rebecca, and I teach school for the Mendocino

County Water Agency. I'm pretty confused about carbon sequestration, and

wondered if you could enlighten me. I have a difficult time picturing carbon,

and wonder how it is sequestered. Is it in a gas or liquid form? If it's a gas

and injected into the ground, wouldn't it be able to seep between rocks and get

into our water supply? Is it stored in tanks? Someone told me it's injected into

coal, then buried? Could we inject it into old coal mines and seal it up? Even

our most knowledgeable around here are stumped on this one. Thank you.

mcwa@co.mendocino.ca.usLetter ID: 0102

Organization: Mendocino County Wa ter Agency, State of California

Letter ID: 0102 Comment ID: 21938 Letter Lines: 15 to 22

Comment Code: 1320 1.1.3 General comments about GS

Comment: Hi, MaryRose. My name is Rebecca, and I teach school for the Mendocino

County Water Agency. I'm pretty conf used about carbon sequestration, and

wondered if you could enlighten me. I ha ve a difficult time picturing carbon,

and wonder how it is sequestered. Is it in a gas or liquid form? If it's a gas

and injected into the grou nd, wouldn't it be able to s eep between rocks and get

into our water supply? Is it stored in tanks? Someone told me it's injected into

coal, then buried? Could we inject it in to old coal mines and seal it up? Even

our most knowledgeable around here are stumped on this one. Thank you.

Individual Response: GS is the process of injecting CO2 captured from an emission source

(e.g., a power plant or industrial fa cility) into deep subsurface rock formations for long-term

storage. It is part of a proce ss known as “carbon capture and storag e” (CCS). When injected into

an appropriate receiving formation, CO2 is sequestered by a comb ination of trapping

mechanisms, including physical and geochemi cal processes. Please see the preamble and

materials in the docket for additional information.

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