_GENERAL DOCUMENTS - C1981017 (310)

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is located immediately south of, and adjacent to, Dutch Creek. The terrace cliff consists of about twenty to twenty-five feet of weathered Mancos Shale underlying ten to fifteen feet of unconsolidated alluvial materials. The Mancos Shale portion of the cliff forms a 650 or steeper slope. The overlying alluvial material forms a much steeper cliff face, approaching vertical in most areas, with overhanging soil horizons occurring in places. Due to the significant over-steepening of the upper portion of the cliff, retreat of the cliff toward the refuse pile occurs every year. The continued retreat of the cliff threatens the stability of the western portion of the Old Refuse Pile. It is believed that the retreat of the upper, alluvial portion of the cliff is a function of the cliff attempting to achieve equilibrium via head cutting processes. It does not appear that Dutch Creek at the toe of the cliff impacts the overall stability of the cliff and overlying coal refuse. Currently, the head cutting process continues, with the spalled material falling onto the underlying Mancos Shale slope. In recent years, the cliff has cut back about one to two feet per year. However, in 1997, the rate of retreat markedly increased. Approximately seven feet of retreat was measured between April and November 1997. As this process continues, the cliff retreats toward the Old Refuse Pile. The toe of the coal refuse is located approximately twenty feet south of the cliff edge. However, as the upper portion of the cliff continues to fail, the distance between the top of the cliff and the toe of the refuse decreases. Eventually, when the top of the cliff intersects the toe of the refuse, a portion of the Old Refuse Pile in this area will slide into Dutch Creek. It is probable that the size of the slope failures will vary from small slumps to larger block failures. Dependant upon stream flow at the time of failure, the refuse material will either by washed downstream into the Crystal River, or a blockage of Dutch Creek will occur. Dependent upon the characteristics of a blockage in Dutch Creek, a catastrophic failure of the blockage could occur, resulting in a threat to human health and safety, as well as environmental degradation. In either case, it is probable that a significant amount of coal refuse will be carried down Coal and Dutch Creeks to the Crystal River. This process could continue for years as the cliff face continues its retreat until the head of the cliff reaches a stable configuration. In its present condition, the cliff face poses a threat to human health and safety, and to the general welfare of the surrounding community. The general public increasingly is using Coal Basin, including the Old Refuse Pile. Mountain bikers, hunters, hikers and cattle ranchers on horseback have all been observed to traverse the Old Refuse Pile this past year. It is anticipated that as reclamation is completed, public use will increase. The upper portion of the cliff is so over- steepened that overhangs of relatively unconsolidated soil material have developed. People traveling along the edge of the cliff are in danger of causing a surficial cliff failure, possibly resulting in serious injury or death. Failure of a portion of the Old Refuse Pile into Dutch Creek will result in a significant increase in total suspended solids loading to the Crystal River. The introduction of large volumes of sediment to the Crystal River ecosystem would likely be detrimental to its trout fishery. This impact will occur regardless of whether the failure is of catastrophic proportions, or of smaller, intermittent slumps. Degradation of the Crystal River could have direct negative impacts upon the community of Redstone. These negative impacts would be environmental as well as economic in nature. 3