PERMFILE138126

• Permit No: C1991078A
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: Exhibit 09 Protection of the Hydrologic Balance
• Media Type: D
• Archive: Yes

• DEWATERING DEVICES
Sediment ponds A, C, D, & E will be equiped with 4" valved
dewatering pipes. Pond B will be equiped with a 6" valved
dewatering pipe. Using the equation (Q = C A (2GH)".5) as shown
below, the dewatering pipes are capable of dewatering the ponds
at the rate of 200 gpm for the 4" pipe and 500 gpm for the 6"
pipe with less that one foot of head. These flow rates are
considered conservative because dewatering must be performed
when the ponds are relatively full.
Of the five ponds to be equiped with a 4" dewatering device, Pond C
has the greatest design water capacity of 1.92 AF. Flowing at the
rate of 200 gpm it would take 2.2 days to dewater the pond. Pond B
has a design water capacity of 8.07 AF. The 6" dewatering device
flowing at 500 gpm will dewater this pond in 3.7 days.
The dewatering pipes will be plastic irrigation pipe or equal
with a C factor of 150. The pipes will be installed at a 2%
grade to oti'ercome the calculated friction loss shown beloca.
FLOW CALCULATIONS
Q = C A (2GH)".5
• DIAMETER OF PIPE 4.00 IN DIAMETER OF PIPE
AREA OF PIPE 0.0872 SF AREA OF PIPE
C = LOSS COEFFICIE 0.75 C = LOSS COEFFICIE
H = HEAD ON PIPE 1.00 FT H = HEAD ON PIPE
Q = 0.5250 CFS Q =
Q = 236 GPM Q =
FRICTION LOSSES IN PIPES
4 -INCH PIPE
6.00 IN
0.1963 SF
0.75
1.00 FT
1.1812 CFS
530 GPM
C = surface roughness constant = 150
q = flow in gpm 200
d = inside diameter of pipe, inches = 4
f = Friction Loss, feet per 100' in a Pipe at given flow
f = 0.2083((100/C)"1.85)(q"1.85)/(d"4.8655) 2.092 /100 ft
6 -INCH PIPE
C = surface roughness constant = 150
q = flow in gpm 500
d = inside diameter of pipe, inches = 6
f = Friction Loss, feet per 100' in a Pipe at given flow
• f = 0.2083(1100/C)"1.85)(q"1.85)/(d"4.8655) 1.585 /100 ft
DEWATER.WK1
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