2013-10-07_PERMIT FILE - C1981025A ‎(6)‎

• Permit No: C1981025A
• IBM Index Class Name: Permit File
• Doc Date: 10/7/2013
• Doc Name: Final Engineering Calculations
• Section_Exhibit Name: 4.0 Appendix 4-B
• Media Type: D
• Archive: Yes

• LONG POND 2/6
RUN-OFF VOLUME - - LONG POND
PRECIP DIRECT RUN-OFF
ACREAGE CURVE AMOUNT RUN-OFF VOLUME AF
0.92 78 2.2 0.60 0.05
1.16 70 2.2 0.32 0.03
TOTAL REQUIRED WATER VOLUME FROM RUN-OFF 0.077
SEDIMENT VOLUME
Not applicable to this sizing calculation. The pond is
designed to accumulate sediment from the water treatment
process.
25-YEAR STORM RUN-OFF CONTAINMENT
Design the long pond embankment to contain the run-off from
the 25 year event. The surface area of the long pond is
calculated as follows: The station measurement is taken
beginning on the east (inlet) end of the pond.
Station Width Surface Area
0 27 0.029
50 23 0.026
100 22 0.026
• 150
200 23
22 0.026
0.023
250 18 0.022
300 20 0.025
350 24 0.018
385 20
TOTAL 0.194 Acres
The run-off from the 25 year event would increase the water
level in the long pond 0.40 feet, .077 A-F/ 0.194 Acres.
Design the long pond embankment so it has 0.50 feet
of additional freeboard to contain this run-off. Therefore
the long pond will have 1.5 feet of freeboard above the
emergency spillway.
LONG POND SPILLWAYS
The maximum expected flow from the No. 1 & No. 3 Mine seepage
is 70 gpm. Since the long pond embankment will be designed
to contain the run-off from the 25-year event, the emergency
spillway must only pass the 70 gpm flow.
• P-9-6
08-14-95