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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 C lass 1 airsheds). These regulations specifically require examination of the contributio n to visibility impairment from BART (Best Available Retrofit Technology) eligible sourc es. 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 Augus t 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 Qu ality Division (AQD) of the Wyoming Department of Environmental Quality (WDEQ) as havin g two “BART Eligible” emission

units based on the criteria described above. The Gr anger facility is located approximately 7 miles north-northeast of Granger, W yoming, 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 faci lity.

The Division completed a screening analysis to dete rmine 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 subj ect to BART is whether the emissions from the facility’s BART eligible sources produce a modeled 98 th percentile level, 24-hour impact to visibility of greater than 0.5 deciviews (dv). The 98 th percentile level refers to

the 8 th highest predicted 24-hour visibility impact in any year of modeled meteorology. Visibility impacts were modeled using the CALPUFF m odeling system in combination with three-years of hourly windfields determined us ing the CALMET meteorological model. The pollutants included in the CALPUFF mode ling analyses were particulate matter (PM), sulfur dioxide (SO2), and nitrogen oxi des (NOx).

The Division’s screening analysis indicated that th e 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 a reas). Subsequent to this finding, the Division requested that FMC conduct an analysis to identify Best Available Retrofit2 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 analys is revealed discrepancies in the source location coordinates and source stack parame ters. 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”.