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<br />• <br />There is a minor ephemeral channel that must be diverted around Sediment Pond C. The 10 year peak <br />(low for drainage area D is 8.3G cfs. The refuse pile upper diversion ditch drains into this minor <br />ephemeral channel. The maximum peak flow from Ihis channel is G.2G cfs presented in Appendix C of <br />Volume 4. The total design (low Cor this channel is 14.62 cfs (8.3G + G.2G). The flow value for the <br />upper diversion ditch is the flow based on the 10 year event. See Volume IV, Appendix B, ditch reach <br />4b. <br />Drainage Area D <br />Drainage Ditch D-DI <br />Manning's Equation <br />Flow In a Trapezoidal Channel <br />DEPTH D 0.300 FEET <br />WIDTH W 10.1100 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:l <br />AREA=(W'D)+(X'D^2)= 3.27 FEET^2 <br />WETTED PERIMETER=(W)+2*[( (X•D)^2+D^2)^0.5 ] 11.90 FEET <br />R=AREA/WETTED PERIMETER 0.27 <br />V=(1.49/N)"(R^. G67)'(S^.5)= <br />Q=AXV= <br />Q REQUIRED -Peak Discharge <br />Riprap Sizing -Drainage Ditch D-Dl <br />D50 = Size of Riprap <br />D50 =Diameter in feel <br />V =Velocity <br />S =Slope <br />D50 = 0.2-feet <br />2.4-inches None Required <br />4.98 FT/SEC <br />16.28 CFS <br />14.62 CFS <br />Construct ditch D-DI a minimum oft feel deep to provide for freeboard and lessor ditch <br />slopes. <br /> <br />TR-Ot EXH-8 -14 - <br />I/98 <br />