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• Figure 7 - "C" Factors for Permanent Pasture and Rangeland <br />The following table presents an interpolation of the "C" factor <br />for the reclaimed and natural areas. This is a two way <br />interpolation which factors in both canopy and ground cover. <br />A type W was chosen because there are more forbs and shrubs <br />than grasses in both the reclaimed and natural areas. <br />CANOPY PERCENT PERENNIAL GROUND COVER <br />------ -------------------------------- <br />------ -------------------------------- <br />20.0 23.0 34.9 40.0 <br />-------------------------------- <br />0.0 $ W 0.24 0.23 0.17 0.15 <br />17.5 $ Reclaimed - - - - - - - 0.16 <br />19.5 $ Natural - - - - 0.20 <br />25.0 $ W 0.20 0.19 0.15 0.13 <br />SYMBOL DESIGNATION: <br />Reclaimed Mine Site = R <br />Natural Conditions = N <br />A= R K L S C P <br />A is the soil loss in Tons/Acre/Year <br />R N <br />R = rainfall factor 35.00 35.00 <br />K = soil erodibility factor 0.32 0.32 <br />• LS = combined length slope factor <br />Assume 400' Slope 10$ Grade 2.80 2.80 <br />C = cropping management factor: <br />"C" - Crop Management - R <br />Canopy 17.5$ <br />Cover - Grass 21.7$ <br />Ground Cover 34.9$ 0.16 <br />"C" - Crop Management - N <br />Canopy 19.5$ <br />Cover - Grass 6.9$ <br />Ground Cover 23.0$ 0.20 <br />P = erosion control practice factor 1.00 1.00 <br />SEDIMENT VOLUME <br />AREA R K LS C P A <br />R 35 0.32 2.8 0.16 1.0 5.0 <br />N 35 0.32 2.8 0.20 1.0 6.3 <br />It can be seen from the above calculation that the reclaimed <br />mine site may loose about 5.0 tons per acre per year to <br />erosion. The natural conditions may loose about 6.3 tons <br />per acre per year to erosion. <br />The above calculation demonstrates that untreated drainage from <br />the reclaimed area will contribute 26$ less suspended solids <br />• than untreated drainage from the natural surrounding area. <br />RUNOFF.WK1 <br />-96d- New 11-25-92 <br />T {~- <br /> <br />