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Septembn 1998 Serseca fIW South Expansion • Drainage and Sediment Control Plan ~ 4 <br />TABLE 2 <br />SOIL ERODIBILITY FACTOR <br />Soil Typs Soil Tsxture Soil Erodibility <br />Fsctor lNl <br />Winevada Loam 0.43 <br />Foidel Silt Loam 0.28 <br />Sk wa Silt Loam 0.28 <br />Roxal Variant 0,28 <br />3.3 Length-Slope Factor, LS <br />Input parameters to determine the LS factor were obtained from scaled maps of the watershed <br />areas. Values measured from the scaled maps are presented in the attached input parameter <br />summaries. It 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 for vegetative or mulch cover. The values utilized aze <br />shown on Table 3 (Renard ei al, 1996) (Schwab and Warner, 1987): <br />TABLE 3 <br />CONTROL FACTOR <br />Cover Cover T e Ve atetion Control Feetor <br />Undisturbed Aspen/Mountain <br />Shrub 25% canopy (2 m fall heightl, <br />80% round cover 0.042 <br /> Sagebrush 25% canopy 12 m fall heightl, <br />80% round cover 0.042 <br /> Herbaceous No cano , 80% round cover 0.043 <br /> Mesic Draina a No cano , 40% round cover 0.100 <br />Disturbed Bare Ground None 1.0 <br />3.5 Practice Factor, P <br />The practice factor is used to account for conservation practices for the watershed. The values <br />utilized aze shown in Table 4 (Renard et al, 1996)(Schwab and Wazner, 1987): <br />TABLE 4 <br />PRACTICE FACTOR <br />Surtece Surtece T e Preetics Practice Factor <br />Undisturbed Varies None 1.0 <br />Disturbed Topsoil Stripped Rough and Irregular 0.8 <br />3.6 Sediment Particle Distribution <br /> <br />• <br />A sediment particle size distribution was input into the SEDCAD+ computer model. The <br />distribution was obtained from previous analyses presented in the Seneca II mine permit and is <br />shown in the SEDCAD+ printouts. • <br />Montgomery Watson Mining Group " ]63 S. Unton Boulevard, Suite 460 'tskeruood, Colorado 80728 ' (970J 763 3140 <br />