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• McClane Canyon Access Road <br />Culvert Sizing <br />10 Year Flow <br />Drainage Calculations <br />Ref. - Technical Manual No. 1 (Manual for Estimating Flood Characteristics <br />of Natural-Flow in Colorado) (by J. F. McClain and R. D. Jarrett, U. S. <br />Geological Survey) <br />Southern Plateau Region (of Colorado) Area (mi') <br />1. Watershed G Culvert at 8+46 <br />Drainage area = 46.31 ac <br />z <br />(46.31 ac)(640~ac) = 0.0724 mil <br />Q10 = 59.7 (0.0724)(0.709) = 9.28 cfs <br />Culvert sizing (C.M.P. with inlet control) <br />Ref. - (Handbook of Steel Drainage & Highway Construction Products) <br />Fig. 4-18 (Pg. 161); Scale 1 (headwall or end section) <br />. Q = 9.28 cfs <br />Check with D = 24" ~; Q = 10 cfs <br />pW = 0.84 <br />2. Watershed H Culvert at 20+50 <br />Drainage area = 30.23 ac = 0.0472 mil <br />Q10 = 59.7 (0.0472)(0'709) = 6.85 cfs <br />Culvert sizing - Q = 6.85 cfs <br />Check with D = 24"; Q = 7.0 cfs <br />pW = 0.68 <br />3. Watershed I Culvert at 31+00 <br />Drainage area = 47.64 ac = 0.0744 min <br />Q10 = 59.7 (0.0744)(0.709) = g,46 cfs <br />Culvert sizing <br />• Check with D = 24"; Q = 10 cfs <br />OW = 0.84 <br />1/17/83 <br />