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<br />Exhibit E -Reclamation Plan (continued) <br />i 10.5 cfs at a flow depth of 0.55 feet and a velocity of 4.67 ftlsecond. This velocity is low enough to <br />avoid erosion when using coarse gravel of a D50 of 10 inches. Since the ditch will actually be 3.0 <br />feet deep with freeboard, the safety factor for the design flow is very large. <br />West b9rne Area Ou[!er Dtreh <br />The ditch is designed for the 100 year - 24 hour event peal: flow using the STORM program <br />developed by the technical branch of the Office of Surface Mining. The design is given below: <br />100 year - 24 hour precipitation: 2.4 inches <br />Curve Number of Site: (assuming worst case acreage disturbed at any one time) - 12.5 acres <br />disturbed porous gravel: CN = 79 <br />time of concentration path: 890' long, 30' drop, short grass pasture <br />Using these inputs, the STORM program produced the following results: <br /> <br />Project Title = Carol <br />WATERSHED HYDROGRAPH <br />Inflow into structure is <br />Structure type: <br />Ann Permit West Mine Area Outlet <br />1 <br />Null <br />-- Watershed data for watershed ~ 1 <br />Curve number = 79.0 <br />Area = 12.5 acres <br />Hydraulic length = 850.00 Feet <br />Elevation change = 30.0 feet. <br />Concentration time = 0.18 hours <br />Concentration time type = SCS Upland Curves <br />Unit hydrograph type = Disturbed <br />-- Total Area <br />= 12.5 acres <br />-- Storm data <br />Total precipitation = 2.4 inches <br />Storm type = SCS Type 2 storm, 24 hour storm <br />Peak Discharge = 8.30 cfs <br />Discharge volume = 0.80 acre ft <br />• <br />Cazol Ann Permtt CDMG Application 2 7 <br />