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• • ATTACHh1EN'P 1 • <br />BUSH DRAW CULVERT <br />UNDER HAULROAD <br />Upstream Drainage Area = 430 acres <br />From Procedures for Determining Peak Flows in Colorado, Soil <br />Conservation Service, U.S. Department of Agriculture, March, 1977. <br />Channel Length = 5500' <br />Elevation = 55' Slope = 1~ <br />Page 22, Figure S-5 tc = 0.55 <br />Assume CN = 86, Page 21 range (poor) <br />Page 15 Type II storm for western Colorado 1B slope <br />CFS = 125 <br />Page 80 10 year 24 hour precipitation event = 1.6 inches <br />Page 65 0.56(125) = 70 CFS for 10 year 24 hour storm <br />36" yJ Culvert from Mann,,//ing <br />Q = 1.n86 x A x R`135~2 <br />n = 0.024 for steel culvert <br />__ 1.486 %D2 (D)'67 V ft/ 1(2 <br />Q 0.024 x 4 x (4) x (Slope H ft) <br />4 = 1.486 x T (3)2 x (.75).67x (0.04).5 <br />0.024 4 <br />Q = 61.92 x 7.07 x 0.83 x 0.20 <br />Q = 72.7 CFS > 70 CFS ;, OK <br />Use a 36" ~ culvert in Bush Draw <br /> <br />