_GENERAL DOCUMENTS - C1981017 (263)

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Project Area Overview The Huntsman and Bear Creek Abandoned Mine Land Reclamation Project area is located within Coal Basin, a high mountain drainage basin located in western Pitkin County, a mountainous and rugged portion of the state. The project area is situated at an elevation of about 8,100 feet. The mountain basin where the coal refuse disposal facility is located is narrow and steep, with nearly vertical cliffs and high velocity streams being very common. Annual precipitation is approximately twenty-eight inches, and annual average snowfall is approximately 170 inches,roughly equivalent to that received at many ski resorts in western Colorado. Due in large part to the highly erosive soils and relatively steep slopes found in this area, the annual rate of erosion is great. Coal Creek,the major drainage in the area, is confluent with the Crystal River approximately four miles downstream from the project area. Vegetation at this elevation is predominantly an aspen/spruce/ fir transition, with grasses and shrubs dominating open areas. The area has historically been used principally for open range grazing and by hunters in the Fall. More recently, an increase in day users, generally hikers and mountain bikers, have been accessing the area. The Huntsman and Bear Creek Abandoned Mine Land Reclamation Projects were conducted on a portion of a larger coal refuse disposal facility. The majority of the facility operated under a mining and reclamation permit issued by the Colorado Title V regulatory program. However, the lower margins of the facility were operated prior to implementation of the Surface Mining Control and Reclamation Act, and were exempt from the reclamation obligations imposed on the remainder of the facility. Huntsman Project Overview The purpose of the Huntsman Project was to alleviate potential refuse pile instability. Prior to the project this portion of the larger refuse pile was severely over-steepened and had little, if any plant growth medium on it. Portions of the slope approached vertical, while other areas were closer to 1 H:IV. As a result, vegetative cover was negligible, and surface erosion of the refuse material was significant. More importantly, however, the lower portion of the area presented evidence of potential mass instability. Surficial bulging, drainage from the base of the pile and mid-slope tension fractures had been observed. These features indicated that a deep-seated failure of the refuse facility could occur. This portion of the larger refuse facility is located immediately adjacent to Coal Creek, a significant tributary to the Crystal River. Coal Creek is incised, in a narrow valley. Failure of the refuse facility could cause temporary blockage of Coal Creek. A breach of the temporary blockage could lead to downstream flooding and large-scale erosion. To alleviate these concerns, stabilization of the Huntsman area slopes was required. Stabilization of the Huntsman slopes required removal of the steep upper portion of the area. Due to the proximity of the refuse toe to Coal Creek, the slope length could not be extended toward the creek. Therefore, the upper portion of the project area had to be excavated to achieve the project goals of unloading surcharge, and creating a moderated slope. A limiting factor at the upper portion of the project area was a boundary between the pre-Title V portion of the facility, and the portion of the facility permitted under the Title V program. The design slopes for the project were 2H:1 V. Although a gentler slope angle would have been desirable, the proximity of the creek to the toe of the slope, and the boundary of the permitted area at the upper margin of the area limited the area available for cut and fill 5