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

EAST MINE
• Principal Spillways
The principal spillway will carry the runoff amount within 6
hours.
Substation Pond
Laydown Pond
East Mine Pond
•
EAST MINE
Emergency Spillway Calcualtion
•
West Mine U.S.S. Pond
.07 acre feet X 43560
6 hours X 60 min./hr.X
60 sec./min.
.68 acre feet X 43,560
6 hrs. X 60 min./hr. X
60 sec./min
.41 acre feet X 43,560
6 hrs. X 60 min./hr. X
60 sec./min.
WEST MINE
.50 acre feet X 43,560
6 hrs. X 60min./hr. X
60 sec./min.
Norris Pond .28 acre feet X 43,560
6 hrs. X 60 min./hr. X
60 sec./min.
_ .14 second feet
_ .16 second feet
_ .83 second feet
= 1.01 second feet
_ .56 second feet
From National Engineering Handbook, Section 4 Hydrology Section 5
Hydraulics
Section 4
Page No.
9.2 Basis: 25 yr. 24 hr storm of 2.8" occuring in 6 hrs., poor pasture
10.21 or range CN 89.
Runoff = 1.7"
15.7 Lag Time L= H1'8 (S + 1)'7 L= Lag in hours
1900 Y'S H1= Hyd. length
S= 1000 - 10
CN