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i• <br />Drainage Area D <br />There is a minor ephemeral channel that must be diverted around Sediment Pond C. <br />The 10 year peak flow for drainage area D is 8.36 cfs. The refuse pile upper diversion <br />ditch drains into this minor ephemeral channel. The maximum peak flow from this <br />channel is 6.26 cfs presented in Appendix C of Volume 4. The total design Flow for this <br />channel is 14.62 cfs (8.36 + 6.26). <br />The flow value for the upper diversion ditch is the flow based on the 10 year event. See <br />Volume IV, Appendix B, ditch reach 4b. <br />Drainage Ditch D-D1 <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 0.100 EXPRESS AS DECIMAL <br />Mannings "N" N 0.040 EXPRESS AS DECIMAL <br />SIDE SLOPE X 3.000 SLOPE = X:1 <br />• <br />AREA=(W*D)+(X*D^2)= <br />WETTED PERIMETER=(W)+2*[((X*D)^2+D^2)^0.5] <br />R=AREA/WETTED PERIMETER <br />V=(1.49/N)*(R^.667)*(S^.5)= <br />Q=AXV= <br />Q REQUIRED -Peak Discharge <br />Riprap Sizing -Drainage Ditch D-D1 <br />D50 =Size of Riprap <br />050 = ((v x s^.n)n.56p^z <br />D50 = Diameter in feet <br />V =Velocity <br />S =Slope <br />D50 = 0.197 feet <br />Nane Required <br />2.367 inches <br />Construct ditch D-D1 a minimum of 2 feel deep to provide for <br />freeboard and lessor ditch slopes. <br />PR-07 EXH-8 -11 <br />3.27 FEET^2 <br />11.90 FEET <br />0.27 <br />4.98 FT/SEC <br />16.28 CFS <br />14.62 CFS <br />2/03 <br />