2001-12-11_PERMIT FILE - C1981028A ‎(2)‎

• Permit No: C1981028A
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: APPENDIX K SURFACE WATER/SEDIMENT CONTROL
• Media Type: D
• Archive: Yes

4
DISCUSSION ~+
The numerous "blowouts" and other small depressions and the lack of
vrell defined drainage channels are characteristics that are not common
on the agricultural watersheds for which the SCS method was derived. It
is likely that these characteristics cause the actual curve number to be
even less than the value of 39 used above. Therefore, it is likely that
the estimate of zero runoff from the 24 hr, 10 yr precipitation event
is substantially more safe than the above computations would suggest.
It is o-,orth noting that, should a storm produce overland flow, the
runoff will exit the proposed mine area in a distributed manner, and not
as concentrated flow in drainage channels. It would be difficult to
appropriately set site detention ponds unless channels were purposely
• constructed to collect and direct runoff to the ponds.
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