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2002 .fenera IIW South FxDaxtian * Draixaee and Sediment Control Plan <br />3.0 SEDIMENTATION CALCULATIONS <br />The sedimen[ calculations used to model the Seneca IIW (South Expansion) mine site were performed <br />utilizing the SEDCAD Computer Modeling Program developed by Civil Software Design. The <br />SEDCAD Computer model calculates annual sediment yield using the Revised Universal Soi] Loss <br />Equation (RUBLE). The input parameters used in the sedimentation analyses axe presented in the <br />following sections. <br />3.1 RAINFALL FACTOR, R <br />A rainfall factor of 30 was used for the Seneca IIW (South Expansion) mine site. This factor is <br />consistent with other recent erosion analyses performed fox the Seneca Mine. <br />3.2 SOIL ERODIBILITY FACTOR, K <br />The soil exodibility factors for the subject site were determined based on soil survey information <br />(Nyenhuis, 1997). The values are shown on Table 2 (Soil Conservation Service, 1983). <br />TABLE 2 <br />SOIL ERODIBILITY FACTOR <br />Soil Type Soil Texture Soil Erodibitity <br />FactorlKl <br />Routt Clay Loam 0.28 <br />Winevada-Splitro Com lex Loam 0.37 <br />Binco Clay Loam 0.28 <br />Coutis Silt Loam 0.37 <br />Aaber Clay 0.28 <br />Splitro Loam 0.20 <br />Winevada Loam 0.43 <br />Foidel Silt Loam 0.28 <br />Sk way Silt Loam 0.28 <br />Roxal Variant 0.28 <br />Disturbed 0.76 <br />3.3 LENGTH-SLOPE FACTOR, LS <br />Input parameters to determine the LS factor were obtained from scaled maps of the watershed areas. <br />Values measured from the scaled maps are presented in [he attached input parameter summaries. It <br />was assumed that the maximum overland flow length was 400 feet. <br />3.4 CONTROL FACTOR, C <br />The control factor is used to account foe vegetative or mulch cover. The values utilized are shown on <br />Table 3 (Renard et al, 1996) (Schwab and Warner, 1987): <br />MWH * 165 S. Union Boulevard, Suite 410 * Inkewaod, Colorado 80228 * (970f 763-5140 <br />uinm/s«.+/rmv.nwrrm/vxm/nr..ewa ~xsx.~dy,e. <br />P "aN/la?m' <br />