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

Table 2
SEDIMENTATION POND E DESIGN CALCULATIONS
(Continued)
Modified Universal Scil Loss Equation:
Y = 95 (Q gp) 0.56 K LS CP
= 95 ((1.42) (15.4)) 0.56 (0.2)(2.80)(1.0)(1.0)
- 299 tons x 2000 (lbs/ton) / 60 (lbs/cu.ft.)/43,560(sq. ft/ac.)
= 0.23 ac -ft.
Required Sediment Volume: 0.23 ac -ft x (100/40) = 0.58 ac.ft.
Required Sediment Cleanout: When pond is 60% full of sediment.
RUNOFF VOLUME:
1.8 in. rainfall and Curve Number 81 = 0.48 in. runoff
35.5 ac watershed x 0.48 (in. runoff)/12(in./ft.) = 1.42 ac -ft of runoff
volume
OPERATIONS VOLUME:
300 gallons per day = 40 ft3 = .00092 ac -ft
300 gal X 1 ft3 / 7.48 gal = 40 ft3
40 ft3 / 43,560 (ft/acre) _ .00092 acre-feet
SPOIL SPRING FLOW:
.02 cfs = .0397 ac -ft
.02 cfs x 3600 sec/hr x 24 hr = 1728 ft3
1728 ft3 / 43,560 (ft/acre) = .0397 ac -ft
TOTAL VOLUME:
0.58 ac -ft of sediment volume + 1.42 ac -ft of runoff volume + .00092 ac -ft
operations volume + .0397 ac -ft spoil spring flow = 2.04 ac -ft
of total volume
EMERGENCY SPILLWAY:
- Design for 25 -yr, 24 -hr event = 2.2 in. rainfall
- 35.5 ac watershed
- AMC II Curve No. 81
- Average slope of runoff area is 6%
- Slope correction factor = 1.11
- 2.2 in. rainfall O curve No. 81 = 0.74 in. runoff
PEAK FLOW:
32 cfs/in. runoff x 0.74 in. runoff x 1.11 = 26.3 cfs
- 8-9 - Revised 10/19/88