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• Drainage Ditches C6, C9, C10 & C14 <br />~ Manning's Equation <br />Flow In a Trapezoidal Channel -Maximum Slope <br />DEPTH D 0.4 FEET <br />WIDTH W 6.0 FEET <br />Slope S 0.5 EXPRESS AS DECIMAL <br />Mannings'N" N 0.04 EXPRESS AS DECIMAL <br />SIDE SLOPE X 2.0 SLOPE = X:1 <br />AREA=(W"D)+(X"D^2)= 2.72 FEET^2 <br />WETTED PERIMETER=(VV)+2"[((X•D)^2+D^2)^0.5] 7.79 FEET <br />R=AREA/WETTED PERIMETER 0.35 <br />V=(1.49/N)"(R^.667)"(5^.5)= 13.06 FT/SEC <br />Q = A X V = 35.53 CFS <br />Q REQUIRED -Peak Dischazge - C 14 34 CFS <br />Trapezoidal Channel in C-Gulch <br />• Riprap Sizing -Trapezoidal Channel <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 = 2.0-feet 24-inches <br />Drainage channels C6, C9, C10 & C14 will be constructed at least 6-feet wide at the bottom <br />with 2H:1 V side slopes, 2-feet deep including freeboard with DSO riprap of 24-inches. <br />• <br />PR-03 EXH-8 -19 - 5/99 <br />