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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 = <br />0.8 feet <br />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 <br />WIDTH W <br />Slope S <br />Mannings "N" N <br />SIDE SLOPE X <br />AREA=(W'D)+(X'D^2)= <br />WETTED PERIMETER=(W)+2'[((X'D)^2+D^2)^0.5j <br />R=AREAIWETTED PERIMETER <br />V=(1.49/N)"(R^.667)'(S^.5)= <br />Q=AXV= <br />Q REQUIRED -Peak Discharge <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 <br />RUN-OFF VOLUME - - Pontl K <br />Area <br />Disturbed <br />Derelict <br />Farmsteads <br />Orchard <br />TOTAL <br />TOTAL REQUIRED WATER VOLUME --A-F <br />0.400 <br />3.000 <br />0.125 <br />0.025 <br />1.500 <br />Acres <br />4.93 <br />0.66 <br />1.43 <br />0.54 <br />7.56 <br />FEET <br />FEET <br />EXPRESS AS DECIMAL <br />EXPRESS AS DECIMAL <br />SLOPE = X:1 <br />10 inches <br />Curve # <br />87 <br />74 <br />82 <br />72 <br />Precip <br />Amount <br />1.8 <br />1.8 <br />1.8 <br />1.8 <br />1.44 FEET^2 <br />4.44 FEET <br />0.32 <br />9.94 FT/SEC <br />14.32 CFS <br />11.05 CFS <br />Direct <br />Runoff <br />0.75 <br />0.26 <br />0.52 <br />0.21 <br />Runoff <br />Vol A-F <br />0.31 <br />0.01 <br />0.06 <br />0.01 <br />0.39 <br />0.39 <br />TR-045 Exh-8 - 167 - 12/06 <br />/iPPRotro <br />7/3~a~ <br />