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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-lA(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 Loadina <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 /> 60 <br />