2017-12-14_GENERAL DOCUMENTS - C1981010

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Physiographic Setting Trapper Mine extends across the northern slope of the Williams Fork Mountains between elevations of 6,500 ft. and 7,800 ft. The crest of the Williams Fork Mountains forms a long ridge extending east/west at elevations between 7,400 and 7,800 ft. The Yampa River flows generally from east to west a short distance north of the permit area. The Williams Fork River skirts the south side of the mine site and flows into the Yampa River one mile west of the mine. Geologic Setting The bedrock at the ground surface in the Trapper permit area is an interbedded sequence of sandstones, siltstones, shale, and coals comprised of the Cretaceous -age Williams Fork Formation. The Williams Fork Formation forms part of the regionally extensive Mesa Verde Group. Younger unconsolidated alluvial deposits of Quaternary age form a thin mantle over the Williams Fork Formation in stream drainages. Structurally, the mine is situated on the south limb of the northwest -plunging Big Bottom syncline. Major faults extend across the region, but none have been found in the permit area. Coal Seam Stratigraphy The Williams Fork Formation is stratigraphically subdivided into three units or members. These, in ascending order are: 1. the lower Williams Fork 2. the Twentymile sandstone 3. the upper Williams Fork with individual thicknesses of 920 ft. 100 ft. and 680ft. respectively. The coal seams being mined at Trapper Mine are all in the upper Williams Fork member and their nomenclature, in descending order, consists of: o H o I o L o Q o Q rider o R and R rider. Surface Water Hydrology Drainages within and adjacent to the permit area (on the north facing slope) drain south to north in a dendritic pattern as illustrated in Map 1 above. Drainages flow primarily in response to snowmelt and/or heavy rains, eventually discharging to the Yampa River. Drainages in the southern portion of the permit area drain southward to the Williams Fork River. Natural surface waters are of a calcium -magnesium -sulfate type, with total dissolved solids content commonly greater than 1000 mg/1 in the smaller streams, and less than 1000 mg/l in the largest streams. Total dissolved solids concentrations commonly peak during periods of low stream flows; during high flows, waters are diluted, resulting in low concentrations. Ground Water Hydrology Within the general area of the Trapper Mine, ground water exists in both bedrock and alluvial aquifers. Significant bedrock aquifers are the Trout Creek, Middle, Twentymile, and White sandstones. The Middle, Twentymile and White sandstones lie within the Williams Fork Formation; the Trout Creek sandstone is the uppermost member of the underlying Iles Formation.