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. TRAPPER MINE <br />SEDIMENT LOAD DEMONSTRATION <br />BLOCK A,D&H PITS RSC 03-04 POST-MINING <br />Area 89.7 acres <br />f 1 <br />Curve Number <br />Hydrologic Soil Group: B (Permit C-81-010, Appendix Q, Section XII) <br />Cover Type: Pasture, Grassland, or Range <br />Hydrologic Condition: Good <br />CN (AMC II): 61 (SEDCAD 4 CN table - Other Agricultural Lands) <br />CN (AMC III): 78.8 (Barfield, Warner, Haan p. 84) <br />Erodibility Factor <br />K: 0.25 (Permit No. C-81-010, Appendix Q, Section XIII, Table E-4) <br />Control Factor <br />Type and Height of Canopy: None <br />Canopy Cover: None <br />Percent Ground Cover: 78.2 (Trapper Mine Phase II Bond Release App., Table 1.2-1) <br />CP: 0.016 (SEDCAD 4 table for Permanent Pasture, Rangeland) <br />Roughness Modifier: 0.65 (Contour farming operations, effective herbaceous cover, <br />contour ditches, livestock water tanks) <br />Modified CP: 0.010 <br />Average Slope and Slope Length <br /> Elevation <br />Length Change Sloe <br />A-Pit RSC 250 10 4.0 <br />200 10 5.0 <br />Average 225 10 5 <br />D-Pit RSC 650 110 16.9 <br />650 95 14.6 <br />350 40 11.4 <br />Average <br />H-Pit RSC <br />Average <br />E <br />09/18/2008 <br />Overall average <br />Time of Concentration <br />Land Use Category <br />Slope <br />Length (ft) <br />Tc (hrs) <br />SCADINPS2.xls, A,D&H RSC <br />550 82 14 <br />400 40 10.0 <br />525 30 5.7 <br />900 92 10.2 <br />250 40 16.0 <br />519 51 10 <br />431 47 10 <br />1 Forest with heavy ground litter (overland flow) <br />10.0% <br />431 <br />0.149