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Riprap Sizing - Drainage Ditch D-J8 <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 = 0.8 feet 10 inches <br />Ditch J-9-2 <br />Ditch J-9-2 receives flow from its local drainage area, Ditch J-9-1 and Ditch J-11. <br />Because of the large flow, design as a trapezoidal channel. <br />Drainage Ditch D-19-2 <br />Manning's Equation <br />Flow In a Trapezoidal Channel <br />DEPTH D 0.400 FEET <br />WIDTH W 3.000 FEET <br />Slope S 0.125 EXPRESS AS DECIMAL <br />Mannings "N" N 0.025 EXPRESS AS DECIMAL <br />SIDE SLOPE X 1.500 SLOPE = X:1 <br />AREA=(W"D)+(X"D^2)= 1.44 FEET^2 <br />WETTED PERIMETER=(W)+2'[((X"D)^2+D^2)^0.5) 4.44 FEET <br />R=AREA/WETTED PERIMETER 0.32 <br />V=(1.49/N)"(R^.667)-(S^.5)= 9.94 FT/SEC <br />Q=AXV= 14.32 CFS <br />Q REQUIRED - Peak Discharge 11.61 CFS <br />Riprap Sizing - Drainage Ditch D-J9 <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 = 0.8 feet 10 inches <br />RUN-OFF VOLUME - - Pond K <br /> Precip Direct Run-off <br />Area Acres Curve # Amount Run-off Vol A-F <br />Disturbed 4.93 87 1.8 0.75 0.31 <br />Derelict 0.66 74 1.8 0.26 0.01 <br />Farmsteads 1.43 82 1.8 0.52 0.06 <br />Orchard 0.54 72 1.8 0.21 0.01 <br />TOTAL 7.56 0.39 <br />TOTAL REQUIRED WATER VOLUME - - A-F 0.39 <br />Exh-8 - 167 - <br />10/07 <br />TR-049 <br />PPRovED <br />6/y?a9