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1.0 Introduction 

Federal Regional Haze regulations require states to address visibility impairment in 

certain parks and wilderness areas (designated as Class 1 airsheds). These regulations 

specifically require examination of the contribution to visibility impairment from BART 

(Best Available Retrofit Technology) eligible sources. BART eligible sources are those 

sources that: 1) belong to one of 26 listed sources categories, 2) are “in existence” on 

August 7, 1977, but not “in operation” before August 7, 1962, and 3) have the potential 

to emit greater than 250 tons per year of a single visibility impairing pollutant. 

FMC’s Granger facility was identified by the Air Quality Division (AQD) of the Wyoming 

Department of Environmental Quality (WDEQ) as having two “BART Eligible” emission 

units based on the criteria described above. The Granger facility is located 

approximately 7 miles north-northeast of Granger, Wyoming, in Section 36, 

T20N/R111W. Figure 1.1 shows the regional setting of the Granger plant. The facility 

has two coal-fired boilers (identification numbers UIN-14 and UIN-15). Figure 1.2 shows 

the location of these units within the Granger facility. 

The Division completed a screening analysis to determine whether the facility was 

“Subject to BART” per the regulations contained in 40 CFR 51, Appendix Y, Section III. 

The criteria for judging whether a facility is subject to BART is whether the emissions 

from the facility’s BART eligible sources produce a modeled 98th percentile level, 24-hour 

impact to visibility of greater than 0.5 deciviews (dv). The 98th percentile level refers to 

the 8th highest predicted 24-hour visibility impact in any year of modeled meteorology. 

Visibility impacts were modeled using the CALPUFF modeling system in combination 

with three-years of hourly windfields determined using the CALMET meteorological 

model. The pollutants included in the CALPUFF modeling analyses were particulate 

matter (PM), sulfur dioxide (SO2), and nitrogen oxides (NOx). 

The Division’s screening analysis indicated that the Granger facility was “Subject to 

BART” since it contributed to visibility impairment in two regional Class 1 areas - the 

Bridger Wilderness and the Fitzpatrick Wilderness (Figure 1-3 shows the location of the 

FMC Granger facility relative to these wilderness areas). Subsequent to this finding, the 

Division requested that FMC conduct an analysis to identify Best Available Retrofit 
 

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Technology applicable to the source and to quantify the improvement in Class 1 visibility 

associated with application of BART controls. The analysis of BART control options was 

to be done according to the guidelines in 40 CFR 51, Appendix Y, Section IV. 

 

Examination of the Division’s BART screening analysis revealed discrepancies in the 

source location coordinates and source stack parameters. These problems were 

corrected and a new baseline analysis was completed by TRC using refined 

meteorological data provided by the Division. The revised baseline analysis indicates 

that the FMC Granger boilers impact the designated Class 1 areas at a level below the 

BART visibility impact threshold and therefore are not “Subject to BART”.