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Physiographic Setting <br />Trapper Mine extends across the northern slope of the Williams Fork Mountains between <br />elevations of 6,500 ft. and 7,800 ft. The crest of the Williams Fork Mountains forms a long <br />ridge extending east/west at elevations between 7,400 and 7,800 ft. The Yampa River flows <br />generally from east to west a short distance north of the permit area. The Williams Fork River <br />skirts the south side of the mine site and flows into the Yampa River one mile west of the <br />mine. <br />Geologic Setting <br />The bedrock at the ground surface in the Trapper permit area is an interbedded sequence of <br />sandstones, siltstones, shale, and coals comprised of the Cretaceous -age Williams Fork <br />Formation. The Williams Fork Formation forms part of the regionally extensive Mesa Verde <br />Group. Younger unconsolidated alluvial deposits of Quaternary age form a thin mantle over the <br />Williams Fork Formation in stream drainages. Structurally, the mine is situated on the south <br />limb of the northwest -plunging Big Bottom syncline. Major faults extend across the region, <br />but none have been found in the permit area. <br />Coal Seam Stratigraphy <br />The Williams Fork Formation is stratigraphically subdivided into three units or members. These, <br />in ascending order are: <br />1. the lower Williams Fork <br />2. the Twentymile sandstone <br />3. the upper Williams Fork <br />with individual thicknesses of 920 ft. 100 ft. and 680ft. respectively. The coal seams being <br />mined at Trapper Mine are all in the upper Williams Fork member and their nomenclature, in <br />descending order consists of: <br />o H <br />o I <br />o L <br />o Q <br />o Q rider <br />o R and R rider. <br />Surface Water Hydrology <br />Drainages within and adjacent to the permit area (on the north facing slope) drain south to north <br />in a dendritic pattern as illustrated in Map 1 above. Drainages flow primarily in response to <br />snowmelt and/or heavy rains, eventually discharging to the Yampa River. Drainages in the <br />southern portion of the permit area drain southward to the Williams Fork River. Natural surface <br />waters are of a calcium -magnesium -sulfate type, with total dissolved solids content commonly <br />greater than 1000 mg/1 in the smaller streams, and less than 1000 mg/l in the largest streams. <br />Total dissolved solids concentrations commonly peak during periods of low stream flows; during <br />high flows, waters are diluted, resulting in low concentrations. <br />Ground Water Hydrology <br />Within the general area of the Trapper Mine, ground water exists in both bedrock and alluvial <br />Page 8 <br />Trapper RN7 Prepared by: R. Reilley <br />Nov 2017 <br />