UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION/X 

Ms. Brenda Bums, Commissioner 

Arizona Corporation Commission 

1200 West Washington Street 

Phoenix, Arizona 85007-2927 

Dear Ms. Bums: 

75 Hawthorne Street 

San Francisco, CA 94105-3901 

JUL 2 6 2012 

Thank you for your interest in Arizona's plan to address regional haze in protected national parks and 

wilderness areas as required under the Clean Air Act (CAA). I am responding to your recent letter 

requesting an extension of the public comment period and additional hearings. 

We agree to extend the deadline for public comment and increase the number of public hearings to 

provide ample opportunity for review and comment on the regional haze Federal Implementation Plan 

(FIP) regarding three power plants in Arizona (Apache Generating Station, Cholla Power Plant and 

Coronado Generating Station.) We plan to extend the public comment period by two weeks, for a total 

of60 days, ending on September 18,2012. We also plan to conduct two additional public hearings, one 

of which will be held in northern Arizona (Holbrook), and one in southern Arizona (Benson). These are 

scheduled for August 14 and 15, 2012, respectively. These two hearings are in addition to the public 

hearing in Phoenix on July 31 , 2012. We will carefully and thoroughly review comments, including any 

additional technical information, submitted during the public comment period prior to making our final 

determination. 

As background, under the Regional Haze Rule, Arizona was required to submit a Regional Haze State 

Implementation Plan (SIP) in December 2007. In January 2009, well after the CAA deadline for such 

action, we made a formal finding that Arizona had not submitted a complete Regional Haze SIP. That 

finding started a two-year clock that could be stopped only by our approval of a SIP or promulgation of 

a FIP. In January 2011, we received a notice of intent to sue followed by a lawsuit covering dozens of 

states, including Arizona, for which we had not approved a Regional Haze SIP or promulgated a 

Regional Haze FIP under the CAA. Shortly thereafter, in February 2011, Arizona submitted a new 

Regional Haze SIP. Submittal of this plan, however, had no effect on the EPA's legal obligation to 

promulgate a Regional Haze FIP, unless the EPA was able to approve fully Arizona's Regional Haze 

SIP. 

After lengthy and complex negotiations involving deadlines for numerous states, the most recent 

revision to the consent decree requires us to take actions on Arizona's SIP, or adopt a FIP, in two 

separate sets of notices. The final action date for the three power plants in our current proposal is 

November 15, 2012. The final action for the remainder of Arizona's SIP is July 15, 2013. These dates 

for us to act on Arizona's SIP are among the latest in the consent decree. 

Accordingly, on July 20, 2012, we proposed a partial approval and partial disapproval of Arizona's 

Regional Haze SIP with respect to its determination of Best Available Retrofit Technology (BART) to 

control emissions from eight units at three electric generating stations: Apache Generating Station, 

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Cholla Power Plant and Coronado Generating Station. We have proposed to approve the State's 

determination that these sources are subject to BART, and to approve the emissions limits for sulfur 

dioxide (S02) and particulate matter (PM1o) at all the units. We also have proposed to disapprove the 

BART emissions limits for nitrogen oxides (NOx) at most of the units. As a remedy we have proposed a 

FIP containing new emissions limits for NOx as well as associated compliance requirements. This 

proposal was published in the Federal Register on July 20, 2012 and is available at: 

http://www.epa.gov/region9/air/actions/az.html#all. 

We are committed to working with Arizona on its regional haze plan. Prior to our July 20, 2012 

proposal, EPA worked with Arizona, the affected utilities, the National Park Service, the environmental 

litigants, and others to gather information useful in preparing our proposal. EPA provided a prepublication version of the proposal that was published in the Federal Register to various parties, 

including the State, on July 2, 2012. States are entitled to deference to their reasoned decisions when 

consistent with the CAA and the Regional Haze Rule. However, we cannot give deference to state 

decisions if we find that the state's analysis does not comply with the regional haze requirements. In this 

case, where we have proposed a FlP, we are committed to continuing to work with the State of Arizona 

on approvable revisions to its SlP. When an approvable regional haze SlP revision is submitted to the 

EPA and approved, we will withdraw our FlP. 

Again, thank you for your letter. If you have further questions, please contact me or your staff may call 

Colleen McKaughan, Associate Director at 520-498-0118. 

Sincerely, 

Director, Air Division