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Hydrologic Data <br /> Type II Storm Frequency Precipitation (SCS Fig S-7) <br /> 10 year/ 24 hour 1 . 88 inches <br /> 25 year/ 24 hour 2 . 20 inches <br /> Hydrologic Soil Complex - Group C <br /> Silty Gravelly Clays <br /> Weathered Shale and Sandstone <br /> Coal Fines - Dirt Roads <br /> Elevation Disturbed <br /> Drainage Max Min Slope Area <br /> Area Ft Ft Diff Ft Length Ft Slope Acres <br /> 1 8150 8040 110 990 11 . 1 11 . 63 <br /> lA 8105 7945 160 2000 8 . 0 7 . 23 <br /> 2 8075 8045 30 460 6 . 5 3 . 49 <br /> Runoff Course Numbers CN <br /> Area 1 - Washplant 93 <br /> Area lA - Old Refuse Pile 75 <br /> Area 2 - Shop Area 90 <br /> Runoff Volumes Runoff Flows <br /> Disturbed Runoff Unit Depth Depth X Area Peak Discharge <br /> Area (IN) Table 2 . 1 (SCS) (Acre Feet) Table S-IA(SCS) (cfs) <br /> 10yr 25yr 10yr 25yr 10yr 25yr <br /> 1 1 . 22 1 . 50 1 . 18 1 . 45 15 . 1 18 . 6 <br /> lA . 33 . 48 . 20 . 29 2 . 9 4 . 2 <br /> 2 1 . 01 1 . 27 . 29 . 37 5 . 9 7 . 4 <br /> 1 . 67 acre feet <br /> Sediment Loading <br /> Universal Soil Loss Equation A=RKLSCP <br /> Notes : <br /> 1 . From Fig . 5 . 5 (AHSDA) R=40 for all areas <br /> 2 . From Appendix II-B-7 of Mid-Continent ' s Permit Application <br /> a K value of . 70 has been established for areas where <br /> there is coal dust and black shale accumulations . <br /> 3 . Control practice value is assumed to be bare soil <br /> conditions . <br />