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The following calculations present the design for a series of <br />ditches that will be installed to control run-off from the Sanborn <br /> Creek Mine area. The location of the ditches is shown on Drawing <br />• 5-019. <br /> COLLECTION DITCH CD-1 <br /> 0.5$ SLOPE AREA <br /> FLOW FROM DRAINAGE AREA N0. 1 & D <br /> FLOW IN A TRIANGULAR CHANNEL <br /> DEPTH D 1.000 FEET <br /> S LOPE S 0.005 EXPRESS AS DECIMAL <br /> MANNINGS "N" N 0.030 EXPRESS AS DECIMAL <br /> DITCH SIDE SLOPE X 1.500 SLOPE = X: 1 <br /> AREA=(W*D)+(X*D)= 1.50 FEET^2 <br /> WETTED PERIMETER=(W)+2( (XD^2+D^2))^.5 3.61 FEET <br /> R=AREA/WETTED PERMITER 0.42 <br /> V=(1.49/N)*(R^.667)*(S^ .5)= 1.96 FEET/SEC <br /> Q = A X V = 2.94 CFS <br /> Q REQUIRED 2.95 <br /> COLLECTION DITCH CD-1 <br /> 5% SLOPE AREA <br /> FLOW FROM DRAINAGE AREA NO. 1 & D <br /> F LOW IN A TRIANGULAR CH ANNEL <br /> DEPTH D 0.650 FEET <br />~" SLOPE S 0.050 EXPRESS AS DECIMAL <br /> MANNINGS "N" N 0.030 EXPRESS AS DECIMAL <br /> DITCH SIDE SLOPE X 1.500 SLOPE = X: 1 <br /> AREA=(W*D)+(X*D)= 0.63 FEET^2 <br /> WETTED PERIMETER=(W)+2( (XD^2+D^2))^.5 2.34 FEET <br /> R=AREA/WETTED PERMITER 0.27 <br /> V=(1.49/N)*(R^.667)*(S^ . 5)= 4.64 FEET/SEC <br /> Q = A X V = 2.94 CFS <br /> Q REQUIRED 2.95 <br />Collection ditch CD-1-will be a V ditch 1.000 feet deep. <br />1.5h:1v side slopes. With a freeboard of 0.3' the total depth <br />of CD-1 is 1.300 feet. The flow velocity is slow enough <br />in the 0.5% area that erosion should not be a problem. In the <br />5% slope area the ditch needs to be watched for erosion. This <br />area does not handle the total flow from the area so the actual <br />velocity in the ditch may be slower which will reduce the chance <br />for erosional problems. <br />• B-92 <br />