2009-10-06_PERMIT FILE - C1980005 (12)

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• Seneca II Mine Pond 004 HYDROLOGIC INPUT PARAMETERS SEDCAD 4 WATERSHED ID Structure 6 - SWS-1 Subwatershed - Channel PM-12 Upper Watershed Area: 67.3 Curve Number: HYDROLOGIC CURVE AREA WATERSHED TYPE GROUND COVER SOIL GROUP NUMBER (acres) Reclaim >3 years Good (>70%) B 62 63 61 Sagebrush Fair D 70 3.73 Total 67.3 CURVE NUMBER 62 Approved Seneca II Mine curve number (CN) values are presented in Appendix 7-12, Postiming Drainage Control. Values were adapted from Urban Hydrology for Small Watersheds, Technical Release No. 55 (TR- 55), Soil Conservation Service, 1986. SEDCAD4 WATERSHED ID Structure 6 - SWS-1 Subwatershed - Channel PM-12 Upper Watershed Area: 67.3 Sedimentology: k Factor and Control Factor VEGETATION HYDROLOGIC k CONTROL AREA WATERSHED TYPE COVER SOIL GROUP FACTOR FACTOR (acres) Reclaimed Good (>70%) B 0 16 0.043 63 61 Sagebrush Fair D 0.37 0.042 3.73 Total, 1 67.3 0.17 0.043 The soil erodibility factor, "k-Factor", values were determined based on Seneca II soil survey information (see Tab 9, Exhibit 9- 1, Soil Type and Sampling Locations, and Attachment 9-6) as presented in Soils of Colorado, Loss Factors and Erodibility, Soil Conservation Service. 1983. The Control Factor values were adapted from the Yoast and Seneca II-W permit application packages. These values are presented in each permit in the Drainage and Sediment Control Plan attachment which is located in Tab 13 of the respective permit documents. The values are based on Renard, et al. (Renard, K.G., Foster, G.R., Weesies, G.A., McCool, D.K., and D.C. Yoder, coordinators, 1996. Predicting Soil Erosion by Water.- A Guide to Converation Planning with the Revised Universal Soil Loss Equation (RUSLE). Agricultural Handbook 703. U.S. Department of Agriculture. Revised 09/09 TR-51 7-6c.1 A-22