f.!!!2 

Protection Agency 

NOV 17 2015 

Mr. John Mooney 

John R. Kasich, Governor 

Mary Taylor, Lt. Governor 

Craig W. Butler, Director 

Chief, Air Programs Branch 

U.S. EPA, Region 5 

77 West Jackson Blvd. 

Chicago, Illinois 60604 

Re: Ohio EPA Response to Sierra Club Designation Recommendation for the 

William H. Zimmer Power Plant and General James M. Gavin Source Areas for the 

2010 Sulfur Dioxide National Ambient Air Quality Standard 

Dear Mr. Mooney: 

On March 20, 2015, U.S. EPA notified states regarding a settled consent decree with 

Sierra Club that affects sources in certain areas yet to be designated under the 2010 1-

hour sulfur dioxide (S02) national ambient air quality standard (NAAQS). This affects 

sources with 2012 emissions greater than 16,000 tons, or sources with emissions 

greater than 2,600 tons and an emission rate of at least 0.45 lbs S02/mmbtu; unless a 

retirement from burning coal was announced by March 2, 2015. The letter identified the 

General James M. Gavin Power Plant and the William H. Zimmer Power Plant as 

subject to the consent decree requirements. 

U.S. EPA allowed states an opportunity to submit recommendations on the designations 

of the areas around the subject facilities by September 18, 2015. Ohio EPA submitted 

recommendations on September 16, 2015 based upon a 5-factor analysis outlined in 

U.S. EPA's March 20, 2015 memorandum Updated Guidance for Area Designations for 

the 2010 Primary Sulfur Dioxide National Ambient Air Quality Standard. Based upon 

that analysis, Ohio EPA recommended Gallia County and a portion of Meigs County be 

designated as attainment for the 2010 1-hour S02 standard for the General James M. 

Gavin source area, which included Kyger Creek Power Plant emissions. A separate 

submittal recommended the portion of Clermont County, excluding Pierce Township, be 

designated as attainment for the 2010 1-hour S02 standard for the William H. Zimmer 

source area. 

~· . · Concurrently, Sierra Club submitted a modeling analysis for both the General James M. 

· Ga~in and William H. Zimmer source areas. Sierra Club recommended a designation of > 

50 West Town Street • Suite 700 • P.O. Box 1049 • Columbus, OH 43216-1049 

www.epa.ohio.gov • (614) 644-3020 • (614) 644-3184 (fax) 
nonattainment for both source areas. On October 20, 2015, U.S. EPA provided Ohio 

EPA the opportunity to review the Sierra Club's analyses since the two analyses 

differed in final results. Ohio EPA analyzed Sierra Club's submittal and identified 

multiple shortcomings, incidents of consistent over-prediction, and the inclusion of 

mischaracterized sources that do not warrant further consideration under the Data 

Requirements Rule. Ohio EPA contends that this systemic over-prediction leads to 

severe inaccuracies of modeled ground-level impacts. Additionally, Ohio EPA notes 

that Sierra Club neglected to include receptors at the location of ambient air quality 

monitors and made no attempt to conduct an analysis of model accuracy based on 

modeled versus monitored concentrations. Omission of this critical check on model 

performance indicates that the Sierra Club did not place a high value on assessing 

model accuracy or the quality of model inputs. Ohio EPA performed this analysis on the 

Sierra Club modeling and demonstrated serious over-predictions of modeled values 

with respect to monitored concentrations. Attached is Ohio EPA's analysis of Sierra 

Club's modeling for both source areas. Additionally, the Sierra Club failed to follow U.S. 

EPA guidance in completion of the modeling submittal. The attached documentation 

clearly identifies the serious technical errors and flaws in the Sierra Club modeling, and 

we urge U.S. EPA to not give any weight to the Sierra Club submittal. Ohio EPA 

reiterates the recommendation of attainment for both source areas as described in 

Ohio's original September 16, 2015 submittals. 

If you have questions, please contact Jennifer Van Vlerah in our Division of Air Pollution 

Control at (614) 644-3696. 

Sincerely, 

Robert Hodanbosi, P.E. 

Chief, Division of Air Pollution Control 

Enclosure