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REVISED <br />7/30/85 <br />Table 5 <br />FISH CREEK TIPPLE <br />DIVERSION DITCH DESIGN CALCULATIONS (Continued) <br />Ditch E-2 <br />Tributary area = 34.7 ac. reclaimed <br />Weighted CN = 70 <br />Total runoff @ CN(70) = 0.17 (in)/12 (in/ft) x 34.7 (ac.) = 0.49 ac -ft <br />Peak flow (steep slope) 38 (cfs/in. runoff) x 0.17 (in. runoff) = 6.5 <br />cfs uncorrected <br />Basin slope factor (actual slope 11K) = 0.925 <br />Basin shape factor (hydraulic length 2,350 ft., equivalent area 57 ac.) <br />= 34.7/57 = 0.609 <br />Corrected peak flow = 6.5 cfs x 0.925 x 0.609 = 3.7 cfs <br />Design: trapezoidal ditch, 2.0 ft. deep, bottorr width = 1.0 ft., <br />side slope = 2:1, gradient = 0.01 ft/ft, n = 0.03 <br />Flow conditions: depth = 0.63 ft., velocity = 2.57 fps, area <br />= 1.44 sq. ft. <br />Check calculation: Q = VA = 2.57 x 1.44 = 3.7 cfs <br />Ditch E-3 <br />Tributary area = 16.5 ac, reclaimed <br />Weighted CN = 70 <br />Total runoff C CN(70) = 0.17 (in)/12 (in/ft) x 16.5 (ac.) = 0.23 ac -ft <br />Peak flow (flat slope) 9.4 (cfs/ir. runoff) x 0.17 (in. runoff) <br />= 1.6 cfs uncorrected <br />Basin slope factor (actual slope 1.2�') = 1.120 <br />Basin shape factor (hydraulic length 2,450 ft., equivalent area 62 ac.) <br />= 16.5/62 = 0.226 <br />Corrected peak flow = 1.6 cfs x 1.120 x 0.266 = 0.48 cfs <br />Design: trapezoidal ditch, 1.5 ft. deep, bottom width = 1.0 ft., <br />side slope = 2:1, gradient = 0.01 ft/ft, n = 0.03 <br />Flow conditions: depth = 0.22 ft., velocity = 1.52 fps, area = 0.32 sq. <br />ft. <br />Check calculation: Q = VA = 1.52 x 0.32 = 0.48 cfs <br />-14- <br />