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• Riprap Sizing -Drainage Ditch D-J8 <br />D50 =Size of Riprap <br />D50 = ((V X S^.17y7.58))^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 and Dilch J-11. <br />Because of the large flow, design as a trapezoidal channel. <br />Drainage Ditch DJ9-2 <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 DE CIMAL <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)^0.5j 4.44 FEET <br />R=AREAIWETTED 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 11.05 CFS <br />Riprap Sizing -Drainage Ditch D-J9 <br />D50 =Size of Riprap <br />D50 = ((V X S^.177.58))^2 <br />D50 = Diameter in feet <br />V =Velocity <br />S =Slope <br />D50 = 0.8 feet 10 inches <br />RUN-OFF VOLUME - - Pontl K <br /> Precip Direct Runoff <br />Area Acres Curve# Amount Runoff VoIA-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 />TR-045 Exh-8 - 167 - 12/06 <br />/iPPRotro <br />7/3~a~ <br />