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Spillway Pond B <br /> Determine flow velocity down 3h:1v embankment <br /> Pond B Emergency Spillway <br /> Manning's Equation <br /> Flow In a Trapezoidal Channel <br /> DEPTH D 0.300 FEET <br /> WIDTH W 10.000 FEET <br /> Slope S 0.330 EXPRESS AS DECIMAL <br /> Mannings"N" N 0.040 EXPRESS AS DECIMAL <br /> SIDE SLOPE X 2.000 SLOPE=X:1 <br /> AREA=(W*D)+(X*D^2)= 3.18 FEET^2 <br /> WETTED PERIMETER=(W)+2*[((X*D)^2+D^2)^0.5] 11.34 FEET <br /> R=AREANVETTED PERIMETER 0.28 <br /> V=(1.49/N)*(R^.667)*(S^.5)= 9.17 FT/SEC <br /> Q=AXV= 29.15 CFS <br /> Q REQUIRED-Peak Discharge 22.63 CFS <br /> Sediment Pond B <br /> Riprap Sizing-Down Face of Embankment-Pond B <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= 1.00 feet 12 inches <br /> POND C <br /> Sediment pond C receives inflow from the mine. A sediment pond is to provide adequate capacity to contain <br /> or treat the run-off or inflow entering the pond as a result of a 10-year,24-hour precipitation event and any <br /> additional storage resulting from the inflow from any underground mine. The calculation below shows Pond C <br /> has a required water capacity of 3.26 acre feet for the 10-year event,24-hour event. Pond C has an as-built <br /> water capacity of 3.47 acre-feet which leaves 0.24 acre-feet of storage for mine water. If the mine discharges <br /> water for 8 hours at a pumping rate of 150 gallons per minute,the resultant water discharged is about 0.22 <br /> acre-feet. The mine may discharge water in this fashion three or more times per week. The sediment pond <br /> will be dewatered between each mine discharge event to assure the pond maintains the capacity to contain <br /> the 10-year,24-hour precipitation event. <br /> TR-119 EXH-8-7 08/19 <br />