2013-04-10_GENERAL DOCUMENTS - C1981019

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be fault - related have been observed from aerial photographs. These lineations trend approximately north 70 degrees west, north 45 degrees west and north 30 degrees east, with near vertical inclinations. No faults have been identified in the Collom pit area. Faults have been identified in Morgan Gulch, located west of the Little Collom X pit near the axis of the Collom syncline. Two nearly vertical joint sets with the primary having a strike ranging between N55 ❑ W and N60 ❑ W and the secondary having a strike of N19 ❑ E have been identified within the proposed Collom expansion area The coal- bearing strata of interest to the Colowyo operation are stratigraphically located in the Mesaverde Group within the Williams Fork Formation of upper Cretaceous age. The Williams Fork consists of alternating beds of sandstone, sandy shale, carbonaceous shale and coal. The coal to be mined lies within a 392 -foot interval in the Fairfield Member of the Williams Fork Formation. The quality of the coal seams is midway between bituminous and sub - bituminous. 9,000 feet of Mesozoic and 4,500 feet of Paleozoic sediments underlie these coal beds. The Williams Fork Formation is estimated to be 1,600 feet thick in the permit area and is underlain by the ridge- forming Trout Creek Sandstone member of the Iles Formation. Overburden material consists of a sequence of sedimentary claystones, siltstones, shales and carbonaceous -silty shales. These sediments are typical of the cyclothems deposited along the western interior of North America during Late Cretaceous time. The site - specific stratigraphy is described in Exhibit 6 and on Map 8 of the PAP. Results of test borings are included in Section 2.04.6 Geology Description, Volume 15, for the Collom expansion. Test borings resulted in information on the presence of subsurface water, characterization of the physical properties of the overburden, and testing and evaluation of the geochemical properties of the overburden. Additional discussion of the results of this testing can be found in Section B. III. E. of this document. Coal seams Y and X will be mined in the proposed Little Collom X pit. Coal seams Y through G will be mined in the proposed Collom Lite pit. Coal seam thicknesses in the Collom expansion area vary from 5 to 11 feet. The coal to be mined is midway between bituminous and sub - bituminous, low ash, low sulfur coal. 3.2.6 Climate Climatic information is found in Section 2.04.8 of Volume 1 of the PAP. The region is characterized by a semi -arid steppe climate regime. Precipitation averages 18 inches per year with a significant portion of this yearly precipitation occurring as snowfall. Prevailing winds over the permit area are from the southwest and average eight to nine miles per hour. High winds are not common, due to the protection afforded by local terrain. 3.2.7 Soils Colowyo Coal Mine C1981 -019 PR -03 23 April 10, 2013