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Appendix G <br />Air Quality Analysis Modeling Report <br />For the Red Cliff Mine, CAM is proposing to construct new mine entries (portals) and associated <br />facilities to extract low-sulfur coal from existing federal coal leases, potential new federal coal <br />leases, and a small amount of private coal. The total future coal leasing area is estimated to be <br />about 23,000 acres. In addition to locating facilities on the existing and potential new coal <br />leases, CAM would locate surface facilities, including a waste rock disposal area, railroad loop, <br />the unit train load out, and a conveyor system, on BLM lands within the boundaries of the <br />proposed right of way and Land Use Application area (approximately 1,140 acres). Mitchell <br />Road (X Road) would be upgraded to serve as the mine access road from SH 139. <br />A railroad would be constructed from the mine site, connecting to the existing Union Pacific <br />Railroad near Mack, Colorado. The proposed railroad would traverse approximately 9.5 miles of <br />BLM land, crossing of SH 139 once and traversing approximately 5 miles of private land. The <br />proposed railroad would also cross M.8 Road and 10 Road. <br />Electric power would be provided to the mine through contract with the local power utility. A <br />new 14-mile, 69-kilovolt (kV) transmission line is proposed to supply electrical power from the <br />Unitah Substation to the mine site, with approximately 7 miles on federally managed lands and 7 <br />miles on private lands. <br />3.0 Near-Field Dispersion Modeling Analysis <br />Near-field impacts within 1 kilometer (lcm) of the proposed mine's surface facilities (mine site) <br />were assessed by modeling projected emission rates in the AMS/EPA Regulatory Model <br />(AERMOD). AERMOD is a modeling system consisting of three separate modules: AERMET, <br />AERMAP, and AERMOD. AERMET is a meteorological preprocessor and uses hourly surface <br />observations, cloud cover, and upper air parameters from twice-daily vertical sampling of the <br />atmosphere to create two output files consisting of surface and vertical profile data, respectively. <br />The terrain preprocessor AERMAP uses Digital Elevation model (DEM) maps as well as user- <br />generated receptor grids. AERMAP's output file consists of the x,y locations of each receptor, <br />mean sea level (MSL) elevation, and hill profile parameter. The hill profile parameter is used in <br />determining plume flow around elevated terrain. <br />AERMOD directly reads the three output files created by the pre-processing programs and, along <br />with user-entered source information, predicts ambient air concentrations for a variety of <br />pollutants and averaging periods ranging from 1-hour to annual. AERMOD has a regulatory <br />default option, as well as rural or urban dispersion coefficients, urban population settings, and <br />other features specific to the model. AERMOD also includes the Plume Rise Model <br />Enhancement (PRIME) building downwash algorithm, which calculates directional specific <br />building downwash widths and heights as well as downwash parameters for the cavity region of <br />the building (earlier downwash algorithms ignored the cavity region, and models did not <br />calculate concentrations for receptors located inside this area). <br />Modeled pollutant concentrations were compared to the applicable NAAQS and CAAQS to <br />determine if emissions from the proposed mine (construction phases and ongoing production) <br />would interfere with attainment and maintenance of those standards in the Class II areas <br />surrounding the Red Cliff Mine area. This section describes the air quality dispersion model <br />options, land use classification, receptor network, meteorological data, emission calculations, <br />and model results for the near-field analysis. <br />G-3 <br />DBMS 515 <br />