Ron Curry, Administrator 

US EPA Region 6, (6-RA) 

1445 Ross Avenue, Suite 1200 

Dallas, TX 75202-2733 

RE: Recommendations for 2010 Sulfur Dioxide Nation Ambient Air Quality Standards 

(NAAQS) for Louisiana 

Dear Mr. Curry: 

On March 20,2015, the United States Environmental Protection Agency (US EPA) issued 

"Updated Guidance for Area Designations for the 2010 Primary Sulfur Dioxide National 

Ambient Air Quality Standard." This guidance was based upon a consent decree entered into on 

March 2, 2015, in the US District Court of the Northern District of California by the US EPA 

and plaintiffs Sierra Club and Natural Resources Defense Council (Case No. 13-cv-03953). 

States with indicated areas were given until September 18, 2015, to submit a recommendation to 

US EPA. 

Two areas (3 facilities) in Louisiana were identified as fitting these categories: 

1.) Nelson Industrial Steam Company- Calcasieu Parish; 

2.) R SNelson Generation Plant- Calcasieu Parish; and 

3.) Do let Hills Power Station - De So to Parish. 

The state recommended, on September 18, 2015, that these areas be designated attainment based 

on the most current information at that time. By letter dated February 11, 2016, EPA disagreed 

with this designation recommendation and provided a detailed technical support document as 

evidence as to why the recommendations should be changed to something other than attainment. 

EPA indicated that Calcasieu Parish would be designated as unclassifiable and that DeSoto 

Parish (or a portion thereof) would be designated as nonattainment. Furthermore, the letter 

indicated that the state had until April 19, 2016 to provide your office with any additional 

information that the EPA should consider prior to finalizing these designations. The state 

appreciates this opportunity to present additional data and modeling outcomes which will show 

that the EPA's intended designations should be adjusted such that both areas are designated 

attainment. 

The state offers the following information for consideration and believes that the final 

designation should be changed accordingly: 

Post Office Box 4301 • Baton Rouge, Louisiana 70821-4301 • Phone 225-219-3953 • Fax 225-219-3971 

www.deq.louisiana.gov 
attainment with the standard. EPA asserts that the area of analysis or grid was not sufficient 

according to its draft Technical Assistance Document (TAD); however, no receptors in the 

modeling presented were greater than 170.0~-tg/m which is less than the standard (196.5~-tg/m\ 

near the edge of the grid. It is widely accepted that AerMod over predicts concentrations when 

used to determine a one-hour standard and provides conservative results. Furthermore, it is 

apparent from EPA's own TSD that S02 emissions from the facilities in the area of analysis 

have been reduced by some 20% over the three-year period of2012-2014. 1 

These factors are indicative of an area that is in attainment with the standard for the sulfur 

dioxide NAAQS. . EPA should hold the same for Calcasieu Parish and designate the area as 

attainment. 

Intended Nonattainment Area: Desoto Parish 

The state initially recommended DeSoto Parish (a partial portion of the parishi as unclassifiable 

due to lack of sufficient monitoring data and/or modeling results. After completing model runs 

using the EPA proposed Beta option ofLowWind3 within the most current version ofthe EPA 

approved Aermod model, the state revised its initial recommendation from unclassifiable to 

attainment. EPA has stated that it intends to designate the area as nonattainment. 

The state would like to provide further information that will reinstate the designation of 

attainment for the DeSoto Parish area. Dolet Hills Power Station owners have conducted 

additional air modeling for the DeSoto Parish area that included more accurate emission data and 

stack parameters for the coal-fired electric utility and also included the International Paper 

Mansfield Mill, which is located approximately 14 kilometers north ofthe utility. This modeling 

run did not use the Beta option that EPA discounted in the state's revised designation 

recommendation. This model was performed in accordance with EPA's draft TAD, dated 

February 2016 as well as the EPA Technical Support Document attached to the 120 day letter. 

Specifically, more accurate information was included for three categories: stack parameters, 

emissions data, and effects of downwash. The data was processed on a parameter basis in which 

flowrate was adjusted back to actual hourly stack conditions using the temperature data for 

concurrent hour for which the exit velocity was being calculated. The final refined modeling 

1 See Table 1: Actual S02 Emissions between 2012-2014 from Facilities in the Calcasieu Parish Area of Analysis, 

Technical Support Document, Louisiana 

2 The area bounded by the following UTM Coordinates (excluding portions of Red River Parish, Louisiana that falls 

within this UTM-based boundary) at NAD 83 Datum, UTM Zone 15: X ,Y coordinates respectively: 

441287,35410 19;441287;35620 19;450500,35620 19;450500,3541 019. 
Based upon the additional information presented, the state recommends a designation of 

attainment for both the Calcasieu and DeSoto Parish areas. Documentation to support the 

LDEQ's recommendation for each parish can be found in the attached enclosures. If you have 

any questions, please contact Donald Trahan, Administrator of the Air Permits Division, 

at (225) 219-3408. 

Sincerely, 

:} ;1 _) c_-) 0 I ) fJ ~ - u ~~ ~{. - /!: e:;;>--fo.-

Chuck Carr Brown, Ph.D. 

Secretary 

C: Mark Hansen, Acting Associate Director of Air Programs 

Guy Donaldson, Chief Air Planning Section 

CCBNHANH 

Enclosures: 

Calcasieu Parish Supporting Document 

De Soto Parish Supporting Document