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construction and operation has created cut and fill slopes even steeper. <br /> Steep slope angle affects plant growth potential in two main ways. First, the <br /> steep angle tends to allow incident moisture the opportunity to runoff before <br /> penetrating the soil and becoming available for uptake by plant roots. Second, <br /> as moisture runs off these steep angles, it has a very high capacity for <br /> carrying suspended sediment and, hence, as sediments are suspended and <br /> removed downslope, erosion can proceed at high rates. Beyond the potential <br /> impacts to aquatic and terrestrial ecosystems below, the loss of surface <br /> materials may expose ungerminated seeds or carry them away, or uproot <br /> seedlings with minimal root development. Lowered surface elevation will also <br /> leave surviving plants "pedestalled" and with reduced access to a wetted soil <br /> zone. The oversteepened slopes left by the former operators at Coal Basin <br /> make an already difficult revegetation task that much more difficult. <br /> Despite the difficulty, the abandonment of oversteepened slopes by the former <br /> operator demands that the consequent exaggeration of erosional danger be <br /> addressed through revegetation. <br /> ASSESSMENT OF EROSION HAZARD AT COAL BASIN <br /> Although the presence of slopes nearing and even exceeding 1:1 (h:v) intuitively <br /> suggests a high erosion hazard, the quantitative potential for sediment yield is <br /> not easily known. One approach to evaluating this potential is through use of a <br /> soil loss model such as the Universal Soil Loss Equation (USLE). Included in <br /> permit documentation for the Coal Basin Mine were calculations relating to <br /> sediment pond sizing. Included was one small area that had a 50 percent <br /> slope (2:1(h:v )). For this area, the consideration of soil erodibility, slope <br /> length, percent slope, ground cover and surface roughness along with rainfall <br /> 4 <br />