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<br />CHANNEL DESIGN <br /> <br />• Channels below the impoundment have been designed to withstand the worst case <br />condition (i.e. passing 7.5 cfs) <br />1. Channels Below Spillways <br />Worst Case: Below spillway channel <br />O~5 = 7.5 cfs S = 0.07 <br />Minimum Channel Protection = 6 in. rip rap <br />n = 0.031 •, Z = 3:1, Vp = 7.9•fps <br />'n & Vo (Ref. U.S. Dept. Of Commerce, Bureau of Public Roads, Design of <br />Roadside channels, Hydraulic Series No. 4) <br />A Minimum = 7.5 cfs = 0.95 ftZ <br />7.9 fps <br />Try Triangular Swale: d = 1' <br />A=zd2=(3)(1)=3ft'OK <br />Check Velocity <br />• V = 1.49 R~"S"~ R = A/P A = 2ft <br />N <br />P=2d 1+3' <br />= 6.33 <br />R = 0.474 <br />V = 7.73 fps OK <br />..channels will use minimum 6" rip rap on gravel bed <br />d=1' <br /> <br />Revised May 1998 <br />