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• Collection Ditch <br />Ditch D-4 <br />Collection Ditch for Pond P-9 <br />MANNING'S EQUATION <br />FLOW IN A TRAPIZODIAL CHANNEL <br />DEPTH D 0.550 FEET <br />WIDTH W 5.000 FEET <br />SLOPE S 0.020 EXPRESS AS DECIMAL <br />Mannings "N" N 0.040 EXPRESS AS DECIMAL <br />SIDE SLOPE X 1.500 SLOPE = X:1 <br />AREA=(W*D)+(X*D^2)= 3.20 FEET^2 <br />WETTED PERIMETER=(W)+2((XD^2+D^2))^.5 6.98 FEET <br />R=AREA/WETTED PERMITER 0.46 <br />V=(1.49/N)*(R^.667)*(S^.5)= 3.13 FT/SEC <br />Q = A X V = 10.04 CFS <br />Q REQUIRED 9.31 CFS <br />Q required is based of the design flow for the emergency <br />spillway for pond P-9. See page P-9-2 in this appendix. <br />• The ditch will be a trapezoidal with an 5-foot bottom width <br />and a flow dept of 0.6 feet. The side slopes will be <br />1.5h:1v. With a freeboard of 0.3' the total required depth of <br />the ditch is 0.9 feet. This ditch is formed by the berm <br />located on the south edge of the reclaimed site. Therefore <br />the berm must be at least 0.9 feet high. The flow velocity <br />is slow enough that erosion will not be a problem. <br />• <br />4-B:10 October 1994 <br />