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Spillway Pond B <br />Determine f{ow velocity down 3h:1v embankment <br />Pond B Emergency Spillway <br />Manning's Equation <br />Flow in a Trapezoidal Channel <br />DEPTH D 0.300 FEET <br />WIDTH W 10.000 FEET <br />Slope S 0.330 EXPRESS AS DECIMAL <br />Mannings "N" N 0.040 EXPRESS AS DECIMAL <br />SIDE SLOPE X 2.000 SLOPE = X:1 <br />AREA=(W*D)+(X*D^2p <br />WETTED PERIMETER=(W)+2"[((X*Dr2+D^2)^0.5] <br />R=AREA/WETTED PERIMETER <br />V=(1.49/N)*(R^.667)*(S^.5}= <br />Q=AXV= <br />Q REQUIRED -Peak Discharge <br />Sediment Pond B <br />Riprap Sizing -Down Face of Embankment -Pond B <br />D50 =Size of Riprap <br />D50 = ((V X S^.17}/7.58)}^2 <br />D50 = Diameter in feet <br />V =Velocity <br />S =Slope <br />D50 = <br />POND C <br />1.00 feet <br />12 inches <br />3.18 FEET^2 <br />11.34 FEET <br />0.28 <br />9.17 FT/SEC <br />29.15 CFS <br />22.63 CFS <br />Sediment pond C receives inflow from the mine. A sediment pond is to provide adequate capacity to contain <br />or treat the run-off or inflow entering the pond as a result of a 10-year, 24hour precipitation event and any <br />additional storage resulting from the inflow from any underground mine. The calculation below shows Pond C <br />has a required water capacity of 3.23 acre feet for the 10-year event, 24hour event. Pond C has an as-built <br />water capacity of 3.47 acre-feet which leaves 0.24 acre-feet of storage for mine water. If the mine discharges <br />water for B hours at a pumping rate of 150 gallons per minute, the resultant water discharged is about 0.22 <br />acre-feet. The mine may discharge water in this fashion three or more times per week The sediment pond <br />will be dewatered between each mine discharge event to assure the pond maintains the capacity to contain <br />the 10.year, 24hour precipitation event. <br />RPPRouED <br />PR-07 5/17 /03 EXH-8 -7 4/03 <br />