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TAUNA M. SZYMANSKI 

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July 10, 2013 FILE NO: 31531.460005

Via Electronic Mail

Ms. Gina McCarthy

Assistant Administrator for Air and Radiation

U.S. Environmental Protection Agency

1200 Pennsylvania Avenue, NW

Mail Code 6101A

Washington, D.C. 20460

Email: mccarthy.gina@epa.gov

Re: Request for Extension of Comment Period on the Proposed Rule Regarding 

“Implementation of the 2008 National Ambient Air Quality Standards for 

Ozone: State Implementation Plan Requirements”

Dear Assistant Administrator McCarthy:

On June 6, 2013, the U.S. Environmental Protection Agency (“EPA”) published in the 

Federal Register its proposed “Implementation of the 2008 National Ambient Air 

Quality Standards for Ozone: State Implementation Plan Requirements” (“Proposed 

Rule”), and requested that comments on the Proposed Rule be filed by August 5, 2013. 

78 Fed. Reg. 34,178. We are writing on behalf of the Utility Air Regulatory Group 

(“UARG”) to request a 30-day extension of this comment period, to September 4, 

2013.1

The Proposed Rule is lengthy, detailed and complex, with multiple proposals and 

alternatives listed for consideration and comment. There are at least two dozen 

discrete topics relating to the Proposed Rule and the implementation of the 2008 ozone 

National Ambient Air Quality Standards on which EPA requests comment. Each of 

 1 UARG is a voluntary, ad hoc, not-for-profit association of electric generating 

companies and organizations and national trade associations. UARG’s purpose is to 

participate on behalf of its members collectively in EPA’s rulemakings and other Clean Air 

Act administrative proceedings that affect the interests of electric generators and in litigation 

arising from those proceedings. 
 

Assistant Administrator Gina McCarthy

July 10, 2013

Page 2

these topics requires careful consideration, analysis, and the development of 

substantive responses. The voluminous number of diverse topics on which EPA 

specifically requests comment merits additional time to prepare responses.

In addition to the many legal and policy aspects of the Proposed Rule requiring 

consideration and response, EPA requests comment on aspects of the Proposed Rule 

that necessitate technical and scientific analysis and input. For instance, several 

aspects of the Proposed Rule involve modeling and model performance issues. 

Furthermore, EPA’s complicated proposal to substitute NOx reductions for VOC 

reductions in certain circumstances has potential ramifications that merit analysis by 

technical experts. 

UARG is consulting with modelers and scientists with the goal of providing EPA with 

detailed, informed comments on this highly technical Proposed Rule. EPA 

specifically requests comment on these technical issues, and adequate collaboration 

with outside consultants and scientists takes more time than the time typically required 

to develop comments on legal and policy issues alone. For these reasons, UARG 

believes that extending the public comment period in this case would further the 

Agency’s goal of creating a robust and deliberative record in this rulemaking.

In consideration of these factors, UARG respectfully requests that EPA extend the 

comment period on the Proposed Rule to September 4, 2013. 

We appreciate your consideration of this request and look forward to your prompt 

response. Thank you for your attention to this matter.

Sincerely,

Tauna M. Szymanski 

Lucinda Minton Langworthy

cc: Dr. Karl Pepple, OAQPS, pepple.karl@epa.gov

Butch Stackhouse, OAQPS, stackhouse.butch@epa.gov

EPA Docket EPA-HQ-OAR-2010-0885 (via electronic submission)