2018-08-08_PERMIT FILE - C1982056 ‎(17)‎

• Permit No: C1982056
• IBM Index Class Name: Permit File
• Doc Date: 8/8/2018
• Section_Exhibit Name: EXHIBIT 08 TAB 1 SEDIMENT CONTROL PLAN
• Media Type: D
• Archive: No

REVISED
7/30/85
Table 5
FISH CREEK TIPPLE
DIVERSION DITCH DESIGN CALCULATIONS (Continued)
Ditch F-2
Tributary area = 235 ac, undisturbed and reclaimed
Weighted CN = 70
Total runoff @ CN(70) = 0.17 (in) / 12 (in/ft) x 235 (ac.) = 3.33 ac -ft
Peak flow (steep slope) 150 (cfs/in. runoff) x 0.17 (in. runoff)
= 25.5 cfs uncorrected
Basin slope factor (actual slope 101k) = 0.859
Basin shape factor (hydraulic length 4,200 ft., equivalent area 150 ac.)
= 235/150 = 1.567
Corrected peak flow = 25.5 cfs x 0.859 x 1,567 = 34.3 cfs
Design: trapezoidal ditch, 3.0 ft. deep, bottom width = 2.0 ft.,
side slope = 2:1, gradient = 0.03 ft/ft, n = 0.03
Flow conditions: depth = 1.51 ft., velocity = 4.51 fps, area
= 7.60 sq. ft.
L Check calculation: Q = VA = 4.51 x 7.60 = 34.3 cfs
M
Ditch P-1
Tributary area = 46 ac. disturbed
Weiqhted Ch = 87
Total runoff @ CN(87) = 0.75 (in) / 12 (in/ft) x 46 (ac.) = 2.88 ac -ft
Peak: flow (steep slope) 58 (cfs/in. runoff) x 0.75 (in runoff)
= 43.5 cfs uncorrected
Basin slope factor (actual slope 10.) = 0.890
Basin shape factor (hydraulic length 1,500 ft., equivalent area
27.5 ac.) = 46/27.5 = 1.673
Corrected peak flow = 43.5 cfs x 0.890 x 1.673 = 64.8 cfs
Design: trapezoidal ditch, 3.5 ft. deep, bottom width = 2.0 ft.,
side slope = 2:1, gradient = 0.005 ft/ft, n = 0.03
Flow conditions: depth = 2.36 ft., velocity = 4.10 fps, area
= 15.80 sq. ft.
Check calculations: Q = VA = 4.10 x 15.80 = 64.8 cfs
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