USEPA Region VIII 

1595 Wynkoop Street 

Denver, CO 80202-1129 

RE: Addendum to 2015 Colorado Designation Recommendations for 1-hour Sulfur Dioxide NAAQS 

Dear Mr. 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 22, 2010. The Consent Decree (CD) entered on March 2, 

2015 requires EPA to promulgate source specific designations on certain S02 sources no 

later than July 2, 2016 (termed "Round 2" designations). On September 18, 2015, 

Colorado recommended "unclassifiable" designations for two "Round 2" sources in 

Colorado, the Pawnee Power Plant and Martin Drake Power Plant. EPA requested in a 

February 18, 2016 letter that Colorado submit additional information regarding these 

source specific designation recommendations by April 19, 2016. 

The unclassifiable area designation 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. The 

enclosed technical support document provides detailed information for specific 

designation boundary recommendations for these two facilities. The technical support 

document shows that these designation boundary recommendations are accurate and 

supportable for EPA approval. Colorado recommends a radius of 10 kilometers (6.2 

miles) around the Pawnee Power Plant as the boundary for the unclassifiable 

designation. This recommendation is based on guidelines in EPA's Modeling Technical 

Assistance Document (TAD) and an EPA memo issued March 1, 2011 as well as other 

factors. Regarding the boundaries for the Drake Power Plant, Colorado recommends a 

boundary around a portion of the city of Colorado Springs, including enclosed 

unincorporated county areas, bounded to the north by East Woodmen Road, North 

Academy Boulevard, and city limits, to the east by North/South Powers Boulevard, and 

to the south and west by city limits, with the addition of the census designated place 

termed "Stratmoor" bounded by South Academy Boulevard. This recommendation takes 

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 1 Larry Wolk, MD, MSPH, Executive Director and Chief Medical Officer • 
If you have any questions regarding this submittal, please contact me at (303) 692

3114 

or Lisa Devore of my staff at (303) 692-3117. 

Sincerely, 

William Allison, Director 

Air Pollution Control Division 

Colorado Department of Public Health and Environment 

cc: Monica Morales, EPA Region 8 

Adam Clark, EPA Region 8 

Enclosure 

State of Colorado, Technical Support Document for 1-Hour Sulfur Dioxide National 

Ambient Air Quality Standard Recommended Air Quality Designation Boundaries for 

Specific Sources 

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 1 Larry Wolk, MD, MSPH, Executive Director and Chief Medical Officer