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Collection ditch CD-4 will be a V ditch 0.510 feet deep. <br /> 1.Sh:ly side slopes. With a freeboard of 0.3` the total depth <br />. of CD-4 is 0.810 feet. The flow <br />erosion should not be a problem. velocity is slow enough <br /> COLLECTION DITCH CD-5 <br /> FLOW FROM DRAINAGE ARE A NO. 4 & 5 <br /> FLOW IN A TRIANGULAR CHANNEL <br /> DEPTH D 3.000 FEET <br /> S LOPE S 0.010 EXPRESS AS DECIMAL <br /> MANNINGS "N" N O.OJO EXPRESS AS DECIMAL <br /> DITCH SIDE SLOPE X 1.500 SLOPE = X:1 <br /> AREA=(W*D)+(X*D)= 13.50 FEET^2 <br /> WETTED PERIMETER=(W)+2((XD^2+D^2))^.5 10.82 FEET <br /> R=AREA/WETTED PERMITER 1.25 <br /> V=(1.49/N)*(R^.667)*(S^.5)= 5.76 FEET/SEC <br /> Q = A X V = 77.72 CFS <br /> Q REQUIRED 29.30 <br /> Collection ditch CD-5 will be a V ditch 3.000 feet deep. <br /> 1.5h:1v side slopes. With a freeboard of 0.3' the total depth <br /> of CD-5 is 3.300 feet. The flow velocity is marginally <br /> erosive. If erosion becomes a problem some some riprap or other <br /> method may be employed to control erosion. The depth of the ditch is <br /> greater than necessary to provide for the 36" CMP designed below. <br /> Ditch CD-5 will be constructed and maintained 3.3 feet deep. <br />r <br />Riprap sizing foz CD-5 if required <br /> D50 = ((V X S^.17)/7.58))^2 <br /> D50 = Diameter in feet <br /> V = Velocity <br /> S = Slope <br /> D50 = 0.121 feet 1.446 inches none required <br />Since access along the road that CD-S crosses is required, a culvert <br />will be installed across the road. A 36-Inch diameter CMP will <br />handle about 32.5 cfs with no head. Construct a rock headwall at <br />the inlet and outlet ends of the cmp for erosion protection. <br />MINE WATER SETTLING POND <br />The mine water settling pond is designed to allow the mine <br />dewatering water time to settle prior to being discharged into <br />Sanborn Creek. It will be required only during the initial <br />development of the mine. After mining is established in the B-Sean <br />a mine sump will be constructed which will provide the necessary <br />settling time. The maximum flow expected from the mine is 237 gpm. <br />The following mine water settling calculations are based on <br />the maximum expected flow of 237 and a smaller flow of 8o gpm <br />which is expected during the initial development of the mine. <br />• B-97 5/18/93 <br />