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.
p. 1 

Janet Napolitano Stephen A. Owens 

Governor Director 

December 23, 2008 

JAN 12 ZOOS 

Water Docket 

Environmental Protection Agency 

Mailcode: 2822T 

1200 Pennsylvania Ave. NW 

Washington, DC 20460. 

Re: Arizona Department of Environmental Quality Comments on Proposed EPA Carbon 

Sequestration Rule, Docket ID No. EPA-HQ-OW-2008-0390 

Dear Sir or Madam: 

The Arizona Department of Environmental Quality (ADEQ has reviewed the referenced 

proposed EPA rule . ADEQ does not implement the Underground Injection Control (UIC) 

program in Arizona, rather, ADEQ implements a state authorized Aquifer Protection Permit 

(APP) program. ADEQ has worked closely and effectively with the EPA Region IX UIC 

program for many years to ensure consistency in approach to regulating discharges to Arizona's 

aquifers. ADEQ believes that the proposed rule contains appropriate provisions to regulate 

geologic sequestration of carbon dioxide via the national UIC program. In this comment, ADEQ 

wishes to emphasize the unique statutory and geologic issues related to carbon injection and 

sequestration in Arizona. 

While one of the EPA UIC program's criteria for exemption of aquifers is a concentration of 

10,000 mg/L or more of total dissolved solids, Arizona has no similar exemption in current law. 

Arizona law classifies all aquifers for drinking water use (Arizona Revised Statutes § 49-224). 

In the past, the use of high-TDS groundwater for drinking in Arizona has not been necessary due 

to sufficient supplies of high-quality water resources. However, as the state's population has 

grown and potable water resources have become scarce, many Arizona water providers must 

now treat brackish groundwater to provide drinking water to their customers. ADEQ believes 

that the use of high-TDS groundwater in Arizona will only increase, and that saline aquifers 

represent potentially valuable water resources. 

JAN 0 4 2000 

Northern Regional Office Southern Regional Office 

1801 W. Route 66 " Suite 117 " Flagstaff, AZ 86001 400 West Congress Street " Suite 433 " Tucson, AZ 85701 

(928) 779-0313 (520) 628-6733 

ARIZONA DEPARTMENT 

OF 

ENVIRONMENTAL QUALITY 

1110 West Washington Street " Phoenix, Arizona 85007 

(602) 771-2300 " www.azdeq .gov 

Printed on recycled paper 
p. 2 

EA UIC Comment 

December 23, 2008 

Page 2 of 2 

The Region IX UIC program and the ADEQ APP program have historically cooperated on 

various projects, including injection wells and dry wells. The approach has been that EPA 

Region 9 would not issue a UIC permit if ADEQ could not issue an APP. ADEQ expects that 

these cooperative efforts between the two programs will continue, particularly regarding 

potential commercial scale geologic sequestration of carbon dioxide in deep saline aquifers in 

Arizona. The two permitting programs are now actively cooperating to permit a U.S. 

Department of Energy funded pilot sequestration test in northeastern Arizona. ADEQ looks 

forward to continued cooperation with EPA's UIC program. 

Thank you for the opportunity to review and comment on the proposed rule. If you have 

questions, please contact ADEQ's Groundwater Section Manager, Michele Robertson, at (602) 

771-4827. 

cc: Herb Guenther, Director, Arizona Department of Water Resources 
Letter ID: 0286 

Commenter: Stephen Owens 

Organization: Arizona Department of Environmental Quality 

Letter ID: 0286 Comment ID: 25299 Letter Lines: 39 to 70 

Comment Code: 4450 2.4.4.4 Use of aquifer exemptions (seeking comment) 

Comment: The Arizona Department of Environmental Quality (ADEQ) has reviewed the 

referenced proposed EPA rule . ADEQ does not implement the Underground Injection 

Control (UIC) program in Arizona, rather, ADEQ implements a state authorized 

Aquifer Protection Permit (APP) program. ADEQ has worked closely and effectively 

with the EPA Region IX UIC program for many years to ensure consistency in 

approach to regulating discharges to Arizona's aquifers. ADEQ believes that the 

proposed rule contains appropriate provisions to regulate geologic sequestration 

of carbon dioxide via the national UIC program. In this comment, ADEQ wishes to 

emphasize the unique statutory and geologic issues related to carbon injection 

and sequestration in Arizona. 

While one of the EPA UIC program's criteria for exemption of aquifers is a 

concentration of 10,000 mg/L or more of total dissolved solids, Arizona has no 

similar exemption in current law. Arizona law classifies all aquifers for 

drinking water use (Arizona Revised Statutes § 49-224). In the past, the use of 

high-TDS groundwater for drinking in Arizona has not been necessary due to 

sufficient supplies of high-quality water resources. However, as the state's 

population has grown and potable water resources have become scarce, many 

Arizona water providers must now treat brackish groundwater to provide drinking 

water to their customers. ADEQ believes that the use of high-TDS groundwater in 

Arizona will only increase, and that saline aquifers represent potentially 

valuable water resources. 

The Region IX UIC program and the ADEQ APP program have historically cooperated 

on various projects, including injection wells and dry wells. The approach has 

been that EPA Region 9 would not issue a UIC permit if ADEQ could not issue an 

APP. ADEQ expects that these cooperative efforts between the two programs will 

continue, particularly regarding potential commercial scale geologic 

sequestration of carbon dioxide in deep saline aquifers in Arizona. The two 

permitting programs are now actively cooperating to permit a U.S. Department of 

Energy funded pilot sequestration test in northeastern Arizona. ADEQ looks 

forward to continued cooperation with EPA's UIC program. 

Individual Response: EPA acknowledges the commenter's support of the proposed approach. 

The UIC program's mission is the protection of all USDWs 

EPA believes that the creation of a new injection well class (VI) under the existing UIC Program 

1
2

is necessary to enable the use of GS as a climate change mitigation technology in a manner that 

protects USDWs from endangerment. The GS rule contains minimum technical criteria for the 

permitting, geologic site characterization, AoR and corrective action, well construction, 

operation, mechanical integrity testing, monitoring, financial responsibility, injection well 

plugging, post-injection site care, and site closure of GS wells, which will ensure that USDWs 

are protected from endangerment. 

EPA believes 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. 

The Agency clarifies that, in States with primary enforcement responsibility for underground 

injection wells, the decision to allow aquifer exemptions or the injection depth waivers at 

§146.95 is at the discretion of the State pursuant to State statutes. If a State/UIC Director 

believes that aquifer exemptions or injection depth waivers are not appropriate for their State, the 

Director has the authority to not include those provisions in the State regulations. 

For additional information on EPA's final approach to regulating GS, please see the final rule 

and preamble.