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Ditch 4 - 4.2% Chanel - Reclaimed Configuration <br />The following peak flow for Ditch 4 (4.2 %) was obtained from SedCad, page 14 -6 -121 <br />(Location of Ditch 4 can be found on Exhibit 8C. <br />Flow <br />(cfs) <br />Ditch D4 4.7 <br />Manning's Equation <br />Flow In a Trapezoidal Channel <br />DEPTH D <br />0.39 <br />FEET <br />WIDTH W <br />3 <br />FEET <br />Slope S <br />0.042 <br />EXPRESS AS DECIMAL <br />Mannings "N" N <br />0.04 <br />EXPRESS AS DECIMAL <br />SIDE SLOPE X <br />1.5 <br />SLOPE = X:1 <br />AREA= (W *D) +(X *D2)= <br />1.40 Feet2 <br />WETTED PERIMETER= (W) +2 *[((X *D)2 +D2)1/21 <br />4.41 Feet <br />R= AREA/WETTED PERIMETER <br />0.32 <br />V= (1.49 /N) *(R") *(S 112) _ <br />Q =AXV= <br />Q REQUIRED - Peak Discharge <br />Riprap Sizing <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 = 0.07 feet <br />3.55 Ft/Sec <br />4.97 CFS <br />4.73 CFS <br />0.9 inches Pit Run In -Place <br />PR -5 14 -6 -129 (Rev. 05112) <br />