^,,£Dsr^^^ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION 8 

^^KKi>y g 1595 Wynkoop Street 

^.'iwlWfc'/ DENVER, CO 80202-1129 

'^^i PR0^^^ ^^°^ ^ 800-227-8917 

http://www.epa.gov/region08 

JUM10 2011 

Ref: 8P-AR 

Brian Gustafson, Administrator 

Air Quality Program 

South Dakota Department of Envirormient and Natural Resources 

523 East Capitol Avenue 

Pierre, South Dakota 57501-3182 

RE: EPA Response to Jime 1, 2011 Letter on 

Regional Haze State Implementation Plan 

Dear Mr, Gustafson: 

We are providing this correspondence in response to your letter dated June 1, 2011. We 

appreciate your ongoing efforts to work with us to enhance your Regional Haze State 

Implementation Plan (SIP). At this stage in the SIP process, we recognize the need to reach 

resolution on a SIP revision and will address only critical points from your June letter. 

Emission limits for Big Stone I: We appreciate C>tter Tail Power Company's willingness to 

accept the emission limits we have recommended. We understand that the emission limits for 

NOx and SO2 presented in your draft revision for the Administrative Rules of South Dakota, 

chapter 74:36:21 will apply at all times, including startup and shutdown, and be included in your 

next SIP submittal. 

Compliance test method for particulate matter: We continue to prefer a narrower list of test 

method options as detailed in our May 16, 2011 email, however, we are satisfied that your 

suggested approach to include the reference to the South Dakota performance testing methods 

rule will ensure adequate enforceability of the particulate matter emissions limits. To eliminate 

possible confusion and enforcement challenges with the inclusion of separate irrelevant subsections of chapter 74:36:11, we suggest you revise the reference to 74:36.11.01 which we 

suspect was your original intent. 

Continuous emission monitoring system (CEMS) requirements: We appreciate your agreement 

to change the reference in 74:36:21:09 to 40 CFR Part 75, Our recommendation in this regard 

results in certain reporting dilemmas that were not fiilly detailed in our May email. 40 CFR 75,64 

requires submittal of quarterly Electronic Data Reports directly to the EPA Administrator with 
no copy to the state. The general approach other states have used and which we find acceptable 

involves providing clarification in the states' Regional Haze rules. For South Dakota, this would 

involve fiirther revising the reference in 74:36:21:09 as we offer below: 

"Monitoring of sulfijr dioxide and nitrogen oxide emissions from the main stack of a 

BART-eligible source shall be conducted using a continuous emission monitoring system 

which complies with the followine specific continuous emission monitoring requirements 

in 40 CFR Part 75 (July 1, 2009) and 40 CFR Part 60 (July 1. 2009^: 

• BART CEMSs shall be certified, maintained, calibrated and operated 

in accordance with 40 CFR Part 75. Continuous monitoring of SO? 

emissions shall meet the requirements of 40 CFR 75.11. Continuous 

monitoring of NOv emissions shall meet the requirements of 40 CFR 

75.12. 

• BART CEMSs recordkeeping and reporting shall be in accordance 

with the requirements of 40 CFR 60.7. Valid CEMS data shall meet 

the requirements of 40 CFR 60,13. 

Emissions in Ib/MMBtu for BART compliance shall be calculated as specified in the 

definition of 30-dav rolling average at 74:36:21:02(10)." 

Reasonable Progress four-factor analysis: We would like to acknowledge the additional effort 

required to perform a revised four-factor analysis for GCC Dacotah and are pleased with your 

willingness to proceed with this. We offer our assistance to review a draft of this analysis when it 

is available before you move forward with processing a revised SIP. 

Your general approach on all other items discussed in your June letter appears satisfactory; 

however, we will only reach a final conclusion, and perform our complete review, regarding the 

adequacy of South Dakota's Regional Haze SIP when we act on the South Dakota Regional 

Haze SIP revision through our owoi public notice and comment rulemaking. 

We are available to discuss any remaining concems you may have with the Regional Haze SIP. 

If you have any questions on EPA's comments, please contact me at (303) 312-6416, or your 

staff may contact Gail Fallon at (303) 312-6281, 

Sincerely, 

OJ 

6 

Carl Daly, Director 

Air Program