4300 Cherry Creek Drive South, EDO

- AQCC

- A5, Denver, CO 80246

- 1530 P 303

- 692

- 2000 www .colorado.gov/pacific/cdphe

John W. Hickenlooper, Governor | Larry Wolk, MD, MSPH, Executive Director and Chief Medical Officer

Dedicated to protecting and improving the health and environment of th e people of Colorad o

September 18 , 2015

Shaun McGrath Regional Administrator USEPA Region VIII 1595 Wynkoop St reet
Denver, CO 80202

- 1129

RE: 201 5 Colorado Designation Recommendations for 1

- hour Sulfur Dioxide NAAQS

Dear M r . McGrath :

Pursuant to the provisions of section 107(d)(1) of the Clean Air Act, the state of Colorado submits to the Environmental Protection Agency the attached area designation

recommendations for the 1

- Hour Sulfur Dioxide National Ambient Air Quality Standard (NAAQS), as revised on June 2 2, 2010

. The Consent Decree (CD) ordered on March 2, 2015 requires EPA to promulgate source specific designations on certain SO2 sources no later than July 2, 2016 (termed “Round 2” design ations). This CD affects two sources in

Colorado

– the Pawnee Power Plant and Martin Drake Power Plant. The Colorado Department of Public Health and Environment must submit source specific designation recommendations, to assist EPA in promulgating “Round 2” designations, by September
18, 2015.

The enclosed technical support document provides an overview of the designation process and supporting analyses for each recommendation

. The technical support document makes a strong case that these designation recommendations are accurate and supportable for EPA appr oval. The unclassifiable designation for the area surrounding the Pawnee Power Plant is based on the need to develop appropriate short

term emission rates so that air quality model results properly characterize ambient SO2 levels surrounding the facility

. The unclassifiable designation for the area surrounding the Drake Power Plant is based on disparate monitoring and modeling information

. Historical ambient monitoring in the Colorado Springs metropolitan area and current ambient SO2 monitoring near the Drake Power Plant shows that the 1

- hour SO2 NAAQS

has not been violated.4300 Cherry Creek Drive South, EDO

- AQCC

- A5, Denver, CO 80246

- 1530 P 303

- 692

- 2000 www .colorado.gov/pacific/cdphe

John W. Hickenlooper, Governor | Larry Wolk, MD, MSPH, Executive Director and Chief Medical Officer

Dedicated to protecting and improving the health and environment of th e people of Colorad o

Conversely, third

- party air quality modeling submitted to the Air Pollution Control Division (APCD) illustrates potential NAAQS violations. Th e s e disparit ies make it appropriate to designate the area as unclassifiable. An unclassifiable designation is further supported by APCD ’s determination that the available meteorological data is not sufficiently representative of conditions at the facility to conduct accurate modeling

. APCD is working with the facility operator, Colorado Springs Utilities, to gather representative meteorological data

.

The enclosed area classification recommendations for the area surrounding Pawnee Power Plant and the area surrounding Drake Power Plant were adopted by the Colorado Air Quality Control Commission following a public hearing held on August 20, 2015 . If you have any questions regarding this submittal, please contact Mike Silverstein

, Administrator for the Air Quality Control Commission, at (303) 692

- 3478 or Will Allison

, Director of the Air Pollution Control Division, at (303) 692

- 3114.

Sincerely,

Larry Wolk , MD , M S PH

Executive Director and Chief Medical Officer Colorado Department of Public Health and Environment

cc. Martha Rudolph, CDPHE
Mike Silverstein, CDPHE

- AQCC
Will Allison, CDPHE

- APCD Abby Fulton, EPA Region 8

Enclosure

State of Colorado , Technical Support Document f or 1

- Hour Sulfur Dioxide National Ambient Air Quality Standard Recommended Air Quality Designations for Specific

Sources