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.
GENERAL COMMENT: 

Arizona Public Service Company (APS) owns or operates a number of fossil fuel-fired power 

plants, including two large coal-fired power plants. APS strongly supports aggressive research 

and development of viable methods for carbon capture and sequestration (CCS) projects and for 

reuse CO2 from fossil generation plants. APS has worked with Westcarb and other Arizona 

utilities on a DOE funded project to drill an experimental CO2 sequestration test well at our 

Cholla Power Plant near Holbrook, Arizona. APS has also recently received funding from DOE 

to study the feasibility of reusing CO2 from the plant to grow algae that later can be processed 

into liquid transportation fuels. 

APS supports EPA’s proposal to adopt a flexible waiver process to allow for CO2 sequestration 

above and between underground sources of drinking water (USDWs). 74 Fed. Reg. at 44810. In 

Arizona we are just beginning to investigate the potential for geologic storage sites. In the case 

of the project at our Cholla Power Plant, CO2 injection was planned below any USDW. 

However, to the north of our plant favorable geologic storage sites may be located between 

USDWs. The data on water quality is sparse in these deeper units. Allowing for a waiver gives 

us increased flexibility to pursue good storage sites that are not beneath all USDWs. 

Because of the importance of the waiver proposal APS asks that EPA consider requiring the 

inclusion of this waiver provision, rather than leaving the adoption of an injection depth waiver 

process to the discretion of the individual UIC Program Directors. 74 Fed. Reg. 44811. Inclusion 

of a waiver provision would still leave UIC Program Directors free to decline to grant any 

waivers where not necessary or appropriate.
A subsidianj of Pinnacle West Capital Corporation 

Scott L. Davis 

Director 

Environmental Health & Safety 

Department 

VIA ELECTRONIC DELIVERY 

October 15, 2009 

Water Docket 

U.S. Environmental Protection Agency 

Mail Code: 4101 T 

1200 Pennsylvania Avenue, N.W. 

Washington, DC 20460 

Attn: Docket ID No. EPA-HQ-OW-2008-0390 

Tel. 602-250-3225 Mail Station 8376 

Fax 602-250-3872 PO Box ~i3999 

e-mail Scott.Davis@aps.comPhoenix.Arizona 85072-3999 

Re: Comments on Notice of Data Availability for Federal Requirements 

Under the Underground Injection Control (UIC) Program for Carbon 

Dioxide (C02) Geologic Sequestration (GS) Wells (74 Fed. Reg. 44802 

dated Aug. 31, 2009) 

To Whom It May Concern: 

Arizona Public Service Company (APS) submits these comments in response to 

the Environmental Protection Agency (EPA) request for public input regarding the 

Notice of Data Availability and Request for Comment ("NOD A") relating to the 

proposed Federal Requirements Under the Underground Injection Control (UIC) Program 

for Carbon Dioxide (C02) Geologic Sequestration Wells. APS is the largest electric 

utility in Arizona serving over a million customers. APS owns or operates a number of 

fossil fuel-fired power plants, including two large coal-fired power plants. Over the last 

two years APS has worked with Westcarb and other Arizona utilities on a DOE funded 

project to drill an experimental CO2 sequestration test well on our Cholla Power Plant 

property near Holbrook, Arizona. APS also recently received funding from DOE to 

study the feasibility of a fully integrated energy system for beneficial CO2 use. The CO2 

produced by the power plant is fed directly to an algae farm, which consumes CO2. The 

algae will then be processed into liquid transportation fuels (e.g. biodiesel, ethanol, and 

military fuel), constituting a beneficial reuse of CO2. 

APS strongly supports aggressive research and development of viable methods for 

carbon capture and sequestration (CCS) projects and for reuse CO2 from fossil generation 

plants. EPA predicts that the electric power sector "will most likely be the largest 

potential market for [CCS] technologies," and predicts that CCS technology could lead to 

CO2 reductions of approximately 80-90% at a single plant. 73 Fed. Reg. 44354, 44492 

(July 30, 2008). As a result of our involvement in this research and because of the 

potential for impact to our industry APS believes we have the knowledge and perspective 
Arizona Public Service Company Comments 

Docket ID No. EPA-HQ-OW -2008-0390 

October 15,2009 

Page 2 of2 

to provide meaningful comments on the development of EPA's UIC regulations for CO2 

geologic sequestration. 

APS appreciates EPA's careful approach to the development of the C02 g(;:ologic 

sequestration regulations, including this most recent release of additional data. Because 

the technology is still being developed and may not be commercially deployed for many 

years, it is essential that the rule be flexible in order to accommodate later developments 

in information and technology. Performance based standards allow for requirements that 

can be tailored for the differences in geology and other site characteristics across the 

country. 

APS supports EPA's proposal to adopt a flexible waiver process to allow D)r CO2 

sequestration above and between underground sources of drinking water (USDWs). 74 

Fed. Reg. at 44810. In Arizona we are just beginning to investigate the potential fDr 

geologic storage sites. In the case of the project at our Cholla Power Plant, C02 injection 

was planned below any USDW. However, to the north of our plant favorable geologic 

storage sites may be located between USDWs. The data on water quality is sparse in 

these deeper units. Allowing for a waiver gives us increased flexibility to pursue good 

storage sites that are not beneath all USDWs. 

Because of the importance of the waiver proposal APS asks that EPA consi.der 

requiring the inclusion of this waiver provision, rather than leaving the adoption of an 

injection depth waiver process to the discretion of the individual UIC Program Directors. 

74 Fed. Reg. 44811. Inclusion of a waiver provision would still leave UIC Progrmn 

Directors free to decline to grant any waivers where not necessary or appropriate. 

We appreciate the opportunity to comment on this new data and EPA's proposal 

for an injection depth waiver process. If you have any questions regarding these 

comments, please contact me at (602) 250-3225 or by email atScott.Davis@aps.com. 

Scott L. Davis, 

Director Environmental Health and Safety, APS 
Letter ID: 0363  

Commenter: Scott L. Davis  

Organization: Arizona Public Service Company (APS), Environmental Health and Safety  

Letter ID: 0363 Comment ID: 28269 Letter Lines: 17 to 21  

Comment Code: 6000 6. Other Comments that are Out of Scope for the NODA  

Comment: Arizona Public Service Company (APS) owns or operates a number of fossil fuel‐  

fired power plants, including two large coal‐fired power plants. APS strongly  

supports aggressive research and development of viable methods for carbon  

capture and sequestration (CCS) projects and for reuse CO2 from fossil  

generation plants. APS has worked with Westcarb and other Arizona utilities on a  

Individual Response: This comment is outside the scope of the Notice of Data Availability and the UIC

Program’s authority under the GS rulemaking.  

Letter ID: 0363 Comment ID: 28270 Letter Lines: 21 to 25  

Comment Code: 2400 2.4. Other Research Offered by Commenters (seeking comment)  

Comment: generation plants. APS has worked with Westcarb and other Arizona utilities on a  

DOE funded project to drill an experimental CO2 sequestration test well at our  

Cholla Power Plant near Holbrook, Arizona. APS has also recently received  

funding from DOE to study the feasibility of reusing CO2 from the plant to grow  

algae that later can be processed into liquid transportation fuels.  

Individual Response: EPA acknowledges the submittal. EPA is aware of the Cholla GS project described

and will continue to review studies of this nature. EPA intends to continue to collect data on GS and to

incorporate such data and information as it implements its adaptive approach to the GS rulemaking to

incorporate new research, data, and information about GS. For more information on the adaptive

approach, see the responses to comments on the proposed rule in the rulemaking docket.  

Letter ID: 0363 Comment ID: 28273 Letter Lines: 65 to 72  

Comment Code: 2400 2.4. Other Research Offered by Commenters (seeking comment)  
Comment: coal‐fired power plants. Over the last two years APS has worked with Westcarb  

and other Arizona utilities on a DOE funded project to drill an experimental CO2  

sequestration test well on our Cholla Power Plant property near Holbrook,  

Arizona. APS also recently received funding from DOE to study the feasibility of  

a fully integrated energy system for beneficial CO2 use. The CO2 produced by the  

power plant is fed directly to an algae farm, which consumes CO2. The algae will  

then be processed into liquid transportation fuels (e.g. biodiesel, ethanol, and  

military fuel), constituting a beneficial reuse of CO2.  

Individual Response: EPA acknowledges the submittal. EPA is aware of the Cholla GS project described

and will continue to review studies of this nature. EPA intends to continue to collect data on GS and to

incorporate such data and information as it implements its adaptive approach to the GS rulemaking to

incorporate new research, data, and information about GS. For more information on the adaptive

approach, see the responses to comments on the proposed rule in the rulemaking docket.  

Letter ID: 0363 Comment ID: 28274 Letter Lines: 74 to 90  

Comment Code: 5000 5. Comments on the Proposed Rule (out of NODA Scope)  

Comment: APS strongly supports aggressive research and development of viable methods for  

carbon capture and sequestration (CCS) projects and for reuse CO2 from fossil  

generation plants. EPA predicts that the electric power sector "will most likely  

be the largest potential market for [CCS] technologies," and predicts that CCS  

technology could lead to CO2 reductions of approximately 80‐90% at a single  

plant. 73 Fed. Reg. 44354, 44492 (July 30, 2008). As a result of our involvement  

in this research and because of the potential for impact to our industry APS  

believes we have the knowledge and perspective to provide meaningful comments on  

the development of EPA's UIC regulations for CO2 geologic sequestration.  

APS appreciates EPA's careful approach to the development of the C02 geologic  

sequestration regulations, including this most recent release of additional  

data. Because the technology is still being developed and may not be  

commercially deployed for many years, it is essential that the rule be flexible  

in order to accommodate later developments in information and technology.  

Performance based standards allow for requirements that can be tailored for the  

differences in geology and other site characteristics across the country.  

Individual Response: The final rule is based on the most recent GS‐related data, information, and

scientific research available. EPA intends to continue to collect data on GS and to incorporate such data
as it implements its adaptive approach to GS rulemaking. EPA plans to, every six years, collect and

review data on GS projects to determine whether the appropriate amount and types of information and

appropriate documentation are being collected, and to determine if modifications to the requirements

are appropriate or necessary.

For additional information on the adaptive approach and site specific requirements, see the responses

to comments on the proposed rule in the rulemaking docket.

The other portion of this comment pertains to EPA’s proposed GS rule (73 FR 43492) and is outside the

scope of the Notice of Data Availability. Please see responses to comments on the proposed rule for

EPA’s response to similar comments.  

Letter ID: 0363 Comment ID: 28275 Letter Lines: 92 to 100  

Comment Code: 3210 3.2.1. Comments Generally in Support of the Approach  

Comment: APS supports EPA's proposal to adopt a flexible waiver process to allow for CO2  

sequestration above and between underground sources of drinking water (USDWs).  

74 Fed. Reg. at 44810. In Arizona we are just beginning to investigate the  

potential for geologic storage sites. In the case of the project at our Cholla  

Power Plant, C02 injection was planned below any USDW. However, to the north of  

our plant favorable geologic storage sites may be located between USDWs. The  

data on water quality is sparse in these deeper units. Allowing for a waiver  

gives us increased flexibility to pursue good storage sites that are not beneath  

all USDWs.  

Individual Response: EPA acknowledges the commenter's support of the waiver approach and site‐

specific flexibility in regulatory development and permitting as described in the NODA and Request for

Comment. The Agency acknowledges that there are some 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 and operators can seek a waiver of the Class

VI injection depth requirements. EPA agrees that a flexible, site‐specific approach to waiver

determinations (and all Class VI permitting decisions) is appropriate. Site‐specific demonstrations of

injection zone integrity along with proper well construction, operation, monitoring, and post closure site

care are the best way to ensure USDW safety while allowing flexibility for GS above or between USDWs.

EPA believes that the additional requirements that apply to owners or operators of Class VI wells

granted a waiver of the injection depth requirements will provide additional considerations for the

owner or operator and Director when permitting such wells to ensure protection of all USDWs.  

The Agency believes the waiver approach: 1) responds to concerns about local and regional geologic
storage capacity limitations imposed by the proposed injection depth requirements; 2) allows for a more

site‐specific assessment of injection depth for GS projects; 3) accommodates injection into different

formation types; 4) allows for injection of CO2 for GS into non‐USDWs above and/or between USDWs

when appropriate and where it can be demonstrated that USDWs will be protected; and 5) responds to

concerns about the use of aquifer exemptions for GS. Finally, EPA's approach to addressing injection

depth variability through a waiver process responds to concerns about future drinking water resource

availability and the need to ensure that high quality water remains available in sufficient quantities to

supply drinking water needs.  

Letter ID: 0363 Comment ID: 28276 Letter Lines: 102 to 107  

Comment Code: 3390 3.3.9. Comments Regarding State Discretion to Adopt the Waiver Approach  

Comment: Because of the importance of the waiver proposal APS asks that EPA consider  

requiring the inclusion of this waiver provision, rather than leaving the  

adoption of an injection depth waiver process to the discretion of the  

individual UIC Program Directors. 74 Fed. Reg. 44811. Inclusion of a waiver  

provision would still leave UIC Program Directors free to decline to grant any  

waivers where not necessary or appropriate.  

Individual Response: EPA clarifies that adoption of the waiver process remains at the discretion of

individual UIC programs. Therefore, States, Territories, and Tribes seeking primacy for Class VI wells are

not required to provide for injection depth waivers in their UIC regulations and may choose not to make

this process available to Class VI wells under their jurisdiction. Although some commenters asked EPA to

require that waivers be applied nationally, the Agency believes that the decision about whether a waiver

program is appropriate in a specific State, Tribe, or Territory should be made by each program. This

approach allows flexibility for individual program Directors to determine the appropriateness of allowing

for waivers based on regional or state‐specific conditions, such as the predominant geologic settings

anticipated to be used for GS or other land uses in the state while ensuring maximum protection of

USDWs. The final approach for injection depth waivers represents minimum Federal requirements. UIC

program Directors may adopt GS requirements that do not allow injection above or between USDWs if

they determine this to be appropriate (for conditions in their State, Territory, Tribe, or Region) and

protective.