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Section 4 <br />St. Jude Mine <br />Table 4-1 100-vear Peak Discharges for the St. Jude Mine Basins <br /> 100- ear peak discharge <br /> Area Calculated Increased b SE <br />Basin ac s -mi cfs cfs <br />1 4.53 0.00708 3.44 6.12 <br />2 2.38 0.00371 2.17 3.85 <br />3 3.17 0.00495 2.66 4.74 <br />4 1.77 0.00277 1.76 3.13 <br />5 0.86 0.00134 1.05 1.86 <br />4.4 Surface Water Control Structure Design <br />CDM designed two diversion channels to route offsite surface water runoff from <br />Basin 1 and Basin 2 around the surface mine facilities to the ephemeral drainages. <br />Storm water runoff from Basin 3 will be captured and detained by an existing earthen <br />berm along the crest of the WRA. Storm water runoff from Basins 4 and 5, for storm <br />events less than the 100-year storm event, will be captured in a berm and routed to a <br />catchment basin. <br />4.4.1 Channel Design <br />Channels 1 and 2 were designed to convey the 100-year peak discharge from Basin 1 <br />and Basin 2, respectively to the ephemeral drainages. CDM used Manning's equation <br />to calculate the flow velocity and depth in Channels 1 and 2. Flow depth and velocity <br />were calculated using the following equations for the 100-year peak discharges, cross <br />section geometry (triangular), and Manning's n values listed in Table 4-2: <br />Q=VA <br />A = (b + zh)h <br />2/3 <br />V _ 1.49 (b + zh)h S1/2 <br />n b+2h 1+z2 <br />where: <br />Q = discharge in cfs <br />V = velocity in ft/ sec <br />z: 1 = side slope <br />A = flow area in ft2 <br />b = bottom width of the cross section in ft <br />h = flow depth in ft <br />S = channel slope in ft/ ft <br />n = Manning's roughness coefficient <br />F? <br />4-2 <br />0: 84988 - Denison\Task Order 1 - Sunday Mines Drainage Study\Reporffinal ReportlFinal Sunday Mines Drainage Repon_052208.d=