PERMFILE61158

• Permit No: C1981016
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: Hydrology calculations
• Section_Exhibit Name: APPENDIX XXI Section XXI.9
• Media Type: D
• Archive: No

•
\J
•
WEST MINE
Section 5 Diversion Ditch Cross Slope
5.4-4 n= earth bottom, rubble sides n= .032
Diversion Ditch Calculation
Section 4
Page No.
Basis (as before)
10 yr. 24 hr. storm occuring in 6 hours = 1.6"
CN poor posture, range = 89
runoff = .75"
(see blow up of U.S.G.S. quad s heet)
15.7 Lag Time L= HL'8 (S + 1)'7 L= lag in hours
1900Y 'S
HL = Hyd length
L= (2200).8( 1
0 ' 10~ +1).7
89
1900 (59)'5 s= 1000 - 10
CN
L= 472 1.76 CN= 89
1900 7.68) y= slope
L= .057 hours = 3.4 minutes
16.7 Peak Runoff
qp= 484 AQ qp= peak runoff
,L1 D +L
2 Q= rainfall in inches
= 484 .053 A= area in sq. miles
6 + .057
~
pD= duration of rain
= 8.4 second feet L= lag time
A= 4 sq. ft. = z d2
Area Area A= bh = 8x1 = 4 sq. ft.
2 ~-
Wetted Perimeter
$ i' h
b
p= b+h = 8+1=9