PERMFILE65956

• Permit No: C1981010
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: STOCK POND CERTIFICATIONS
• Section_Exhibit Name: APPENDIX Q SECTION XXIX
• Media Type: D
• Archive: No

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Mr. Forrest Luke
February 2, 1995
Page Three
DralnaEe Basin Area
The drainage azeas were determined by digitizing directly from a 1"=400' scale map supplied by
the Trapper Mining Company.
Time of Concentration. T
The time of concentration was calculated using the SCS upland method (a utility of SEDCAD+).
All hydraulic lengths, drainage heights and slopes were measured directly from a l"=400' scale
map supplied by Trapper Mining Company. The values calculated for each structure are shown
on a subwatershed basis in the SEDCAD+ printouts.
Muskineum Routing Parameters. K. X
The Muskingum Routing Pazameters were also calculated using the SCS upland method. All
hydraulic lengths, drainage heights and slopes were measured directly from a 1 "=400' scale map
supplied by Trapper Mining Company. The values calculated between each structure and/or
subwatershed aze shown in the SEDCAD+ printouts.
Curve Number. CN
The runoff curve number (CN) is a factor relating the amount of rainfall to the amount of runoff
for a given azea. The following curve numbers were supplied by the Trapper Mining Company:
Area CN
Undisturbed 47
Disturbed 87
1 Year Growth 80
2 Yeaz Growth 67
Channel Model
Depth of flow and velocity for each spillway were determined using Manning's Equation for open
channel flow. Channel slopes bottom width and side slopes for the channel were determined from
information supplied by the Trapper Mining Company.
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