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Collection ditch CD-1 discharges into Sanborn Creek. A triangular <br />channel will be constructed to handle this flow. The ditch grade will <br />15 percent which results in a flow velocity of 7 fps. <br />• <br />Riprap for CD-1 where it enters Sanborn Creek. <br />D50 = ((V X S^.17)/7.58))^2 <br />D50 = Diameter in feet <br />V = Velocity = 7 <br />S = Slope = 15~ <br />D50 = 0.447 feet 5.369 inches <br />Use 6 to 12 inch riprap in this ditch section. <br />SANBORN CREEK CULVERT <br />This culvert receives flow from area #1, $6 and D. <br />The total design flow is therefore 13.359 CFS <br />A 36" diameter CMP will easily handle this flow. A rock headwall <br />will be constructed at the inlet of the culvert. The culvert <br />discharges into a highway department culvert which discharges <br />into the river so outlet protection for the Sanborn Creek <br />culvert is not an issue. <br />COLLECTION DITCH CD-2 <br />0.5$ SLOPE AREA <br />FLOW FROM DRAINAGE AREA N0. 2 & B <br />FLOW IN A TRIANGULAR CHANNEL <br />DEPTH D 2.000 <br />SLOPE S 0.005 <br />MANNINGS "N" N 0.030 <br />DITCH SIDE SLOPE X 1.500 <br />AREA=(W*D)+(X*D)= <br />WETTED PERIMETER=(W)+2((XD^2+D^2))^.5 <br />R=AREA/WETTED PERMITER <br />V=(1.49/N)*(R^.667)*(S^.5)= <br />Q = A X V = <br />Q REQUIRED - <br />FEET <br />EXPRESS AS DECIMAL <br />EXPRESS AS DECIMAL <br />SLOPE = X:1 <br />6.00 FEET^2 <br />7.21 FEET <br />0.83 <br />3.11 FEET/SEC <br />18.64 CFS <br />17.81 <br />• B-93 <br />