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<br />"1 <br />•/ <br />•1 <br />2.0 SITE CONDITIONS <br />Site condtions in the bcation of the proposed waste bank were obtained from various sources <br />including: geologic maps of the area (USGS, 1978): topographic quadrangles (USGS, 1978a1; <br />geologic hazard maps (USGS, 1978b1; field reconnaissance conducted in tare September and <br />early October 1995 by WESTEC; and borehob investigations condtxxed in early October, 1995 <br />by yJESTEC. A plan view of the proposed waste bank is shown on Drawing 95255-Ot. <br />2.1 SURFACE COfYO1T10f8S <br />Surface cronditions were primarily irnestigated by foot in the area of the waste bank. The area <br />is covered 90 to 95 percent by bw grasses, and 5 to 10 percent with scrub oak, low bushes, <br />and small pine trees. Terrain is very steep, with grades of up to 85 percent and vertical rodt <br />outcrops,l0 to 20 feet high. The Sanbom Creek Mine and the area of tha proposed waste <br />bank are located on the south-facing side of the North Fork of the Gunnison River valley. The <br />south-facing side of the river valley is characterized by dryer surTicial conditions due to longs <br />daily sunlight exposure, and thereforo more stable hillside conditions. <br />The soil at the surface is colluvial in nature from uphip sandstone outcrops of the Bowie <br />Member of the Mesa Verde Formation. This soil is a silty sand wkh some gravel-sized <br />material. Existing road cuts in the West Yard yield larger, well rounded boulders indicative of <br />alluvial terrace deposits probaby tram the North Fork of the Gunnison River. Also present are <br />very large boulders up to 3 feet in diameter. <br />In surveying the bottom of the draw in late September and early October, it was noted that <br />no water was fbwing. ACt:ordrg to Sanbom Creek Mins personnel, water is rarely observed <br />to be ibwing in the draw IArtderson, 19951, with the highest probability of any flow oecurfng <br />during high•intensity rainfall events, and during spring runoff eonditiona. No springs were <br />noted within the draw during the WESTEC field investigations, and according to the mine <br />personnel, springs have not been observed in the recent past (Anderson, 19951. <br />Rock outcrops near the toe of the proposed coal mine waste bank were mapped at the rims <br />of the borehole investigation in early October, 1995. The outcrops were probably exposed <br />during cuts made for the Denver and Rio Grande Western Railroad right-of-way at the toe of <br />96266r1424.RPT Coll Mim W~~t~ Bank Dugn la tM a~n0orn Crwk MM <br />Octobu 1996 WESTEC. Inc. 2 <br />