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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 />~/ <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 11%) = 0.925 <br />Basin shape factor (hydraulic length 2,350 ft., equivalent area 57 ac.) c_ <br />= 34.7/57 = 0.609 G <br />' Corrected peak flow = 6.5 cfs x 0.925 x 0.609 = 3.7 cfs -- <br />Design: trapezoidal ditch, 2.0 ft. deep, bottom width = 1.0 ft., ~' <br />side slope = 2:1, gradient = 0.01 ft/ft, n = 0.03 c= <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 f <br /> Tributary area = 16.5 ac. reclaimed <br />' Weighted CN = 70 ~~ <br /> Total runoff @ CN(70) = 0.17 (in)/12 (in/ft) x 16.5 (ac.) = 0.23 ac-ft '~ <br />' Peak flow (flat slope) 9.4 (cfs/in. 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 flaw = 1.6 cfs x 1.12 0 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 ftlft, n = 0.03 f <br /> Flow conditions: de th = 0.22 ft., <br />p <br />y = 1.52 fps, area = 0.32 sq. <br />velocit ~~ <br />' ft. <br />Check calculation: Q = VA = 1 <br />52 x <br />32 = 0 <br />48 cfs ~~ <br />0 <br /> . . <br />. <br /> <br /> -1 4- <br />1 <br />