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Spillway Pond J <br />Determine flow velocity down 3h:1v embankment <br />Pond J Emergency Spillway <br />Manning's Equation <br />Flow In a Trapezoidal Channel <br />DEPTH D 0.500 <br />WIDTH W 5.000 <br />Slope S 0.330 <br />Mannings "N" N 0.040 <br />SIDE SLOPE X 2.000 <br />AREA= (W *D) +(X *D ^2)= <br />WETTED PERIMETER= (W) +2 *[((X *D) "2 +D ^2) ^0.5] <br />R= AREANVETTED PERIMETER <br />V= (1.49/N) *(R ^.667) *(S ".5) = <br />Q =AXV= <br />Q REQUIRED - Peak Discharge <br />Sediment Pond J <br />Riprap Sizing - Down Face of Embankment - Pond J <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 />FEET <br />FEET <br />EXPRESS AS DECIMAL <br />EXPRESS AS DECIMAL <br />SLOPE = X:1 <br />D50 = 1.7 feet 20 inches <br />Pond Dewatering <br />POND J DEWATERING <br />USE A PUMP WITH A CAPACITY TO DEWATER IN 48 -HOURS <br />POND J <br />RUNOFF FROM 10 -YEAR, 24 -HOUR EVENT 2.38 <br />VOLUME 774930 <br />PUMP CAPACITY 269 <br />PUMP SIZE 4" <br />Dewatering Time 2880.00 Minutes <br />48.00 Hours <br />2.00 Days <br />Acre -Feet <br />Gallons <br />GPM <br />3.00 FEET ^2 <br />7.24 FEET <br />0.41 <br />11.90 FT /SEC <br />35.69 CFS <br />33.56 CFS <br />TR -91 Volume XI, App. B -7 12/14 <br />