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<br />Riprap Sizing -Drainage Ditch D-H1 1°/,Slope Reach <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 = 0.08 feet 0.9 inches <br />None Required <br />Concrete Ditch <br />Flow From Ditch I-1 10 Year Event <br />Manning's Equation <br />Flow In a Trapezoidal Channel <br /> <br />I~ <br />DEPTH D 0.720 FEET <br />WIDTH W 2.000 FEET <br />Slope S 0.001 EXPRESS AS DECIMAL <br />Mannings "N" N 0.015 EXPRESS AS DECIMAL <br />SIDE SLOPE X 1.000 SLOPE = X:1 <br />AREA=(W'D)+(X'D^2p 1.96 FEET^2 <br />WETTED PERIMETER=(W)+2*[((X*Dy` 2+D^2)^0.5] 4.04 FEET <br />R=AREANVETTED PERIMETER 0.49 <br />V=(1.49/N)'(R^.667)'(S^.5)= 1.94 FT/SEC <br />Q=AXV= 3.80 CFS <br />Q REQUIRED -Peak Discharge 2.80 CFS <br />PR-07 <br />Exh-8 - 169 - <br />2/03 <br />