Laserfiche WebLink
1 <br />1 ~. <br />A <br />Table 5 <br />FISH CREEK TIPPLE <br />DIVERSION [iITCH DESIGN CALCULATIONS (Continued) <br />REVISED <br />7/30/85 <br />' Ditch F-2 <br /> Tributary area = 235 ac. undisturbed and reclai med <br />' Weighted CN = 70 <br /> Total runoff @ CN(70) = 0.17 (in) / 12 (in/ft) x 235 (ac.) = 3.33 ac-ft <br />' Peak flow (steep slope) 150 (cfs/in. <br />d <br />25 <br />5 <br />f runoff) x 0.17 (in. runoff) <br /> = <br />. <br />s uncorrecte <br />c <br /> Basin slope factor (actual slope 10% ) = 0.859 <br />' Basin shape factor (hydraulic length 4,200 ft., equivalent area 150 ac.) <br /> = 235/150 = 1.567 <br /> Corrected peak flaw = 25.5 cfs x 0.8 59 x 1,567 = 34.3 cfs <br /> Design: trapezoidal ditch, 3.0 ft. deep, bottom width = 2.0 ft., <br />' side slope = 2:1, gradient = 0.03 ft/ft, n = 0.03 <br /> Flow conditions: depth = 1.51 ft., velocity = 4.51 fps, area <br /> <br />~ = 7.60 sq. ft. <br />' <br />' Check calculation: Q = VA = 4.51 x 7.60 = 34.3 cfs <br />' Ditch P-1 <br /> Tributary area = 46 ac. disturbed <br />' Weighted CN = 87 <br /> Total runoff @ CN(87) = 0.75 (in) / 12 (in/ft) x 46 (ac.) = 2.88 ac-ft <br />' Peak flow (steep slope) 58 (cfs/in. runoff) x 0.75 (in runoff) <br />d <br />4 <br /> = <br />3.5 cfs uncorrecte <br /> Basin slope factor {actual slope 10%) = 0.890 <br />' Basin shape factor (hydraulic length 1,500 ft., equivalent area <br /> 27.5 ac.) = 46/27.5 = 1.673 <br /> Corrected peak flaw = 43.5 cfs x 0.890 x 1.673 = 64.8 cfs <br /> Design: trapezoidal ditch, 3.5 ft. deep, bottom width = 2.0 ft., <br />' side slope = 2:1, gradient = 0.005 ft/ft, n = 0.03 <br /> Flow conditions: depth = 2.36 ft., velocity = 4.10 fps, area <br /> = 15.80 sq. ft. <br /> Check calculations: Q = VA = 4.10 x 15.80 = 64.8 cfs <br />~.- <br /> <br /> <br /> <br />