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~llar lJ7? C)Pn/J Turi~¢mi/r " PoaG D EraG,ation 1 4 3.1 Rainfall Factor, R • A rainfall factor of 30 was used for the TCC Mine site. This factor is consistent with other recent erosion analyses performed for the TCC Mine. 3.2 Soil Erodibility Factor, K The soil erodibiliry factors for the subject site were determined based Sediment Yield Demonstrations Blocks B & C, (TerraMatrix, 1995). From these reports an average K factor of 025 was used for reclaimed and disturbed areas. Other Kfactors- used are summarized in Table 1.2, Soil Erodibility Factot (Soil Conservation Service, 1983). TABLE 1.2 SOIL ERODIBILITY FACTOR Soil Type Soil Texture Soil Erodibility Factor 1\~tixrure on Redatmed Surfaces Mix of soils 0 35 Disturbed Areas Mix of soils 0.2~ Pre-Law Spoil Mix of soils 035 Refuse Rough 0.15 3.3 Length-Slope Factor, LS Input parameters to determine the LS factor were obtained from scaled maps of the watershed areas. Values treasured from the scaled maps are shown on the attached SEDCAD i results. 3.4 Control Factor, C The control factor is used to account for vegetative or mulch cover. Reclaimed area corer percentage obtained from Colorado Yampa Coal, 1999. The values utilized are shown on Table 1.3, Control Factoc (Schwab and \C%arne[, 198 i): TABLE 1.3 CONTROL FACTOR Cover Cover Tv a Ve elation Control Factor Reclaimed Reclaimed Seed Good (>70'/0) Cover OAl 1`1ix Dismrbed Refuse None None 1.0 Pre-Law Reclaimed Seed Fair (>>0°ro) Cower 03G Reclaimed Dlix • 3.5 Practice Factor, P The practice factor is used to account for conservation practices for the watershed. These may include, but arc not limited to, terrace construction, roughening of surface, and/or contour furrows. The values utilized are shown in Table l.i, Practice Factor (Renard e! a/, 199G)(Schwab and \~'arner, 1987): !`lomgomen' ~~'auon ~,\lining Group ' 1G5 J. Onion 6oulecud, Suite -I10 'Lakewood, Colorado 80??8 ' (303) 7GS-SId0 U-8