PERMFILE54870

• Permit No: C1980005A
• IBM Index Class Name: Permit File
• Doc Date: 9/28/2007
• Doc Name: 10 Year, 24 Hour SEDCAD Modeling
• Section_Exhibit Name: Tab 07 Appendix 7-6f.3 Addendum 7-6f.3A
• Media Type: D
• Archive: Yes

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SENECA II MINE
Pond 008
HYDROLOGIC INPUT PARAMETERS
SEDCAD 4
WATERSHED ID
Structure 4 - SWS1
Subwatershed -Channel PM-8
Watershed Area:
52.3
Curve Number:
VEGETATION HYDROLOGIC CURVE AREA
WATERSHED TYPE COVER SOIL GROUP NUMBER (acres)
Aspen/Mountain Brush Good (>70%) C 63 20.9
Reclaimed Fair (30 - 70%) C 71 31.4
Total 52.3
CURVE NUMBER 68
Curve number (CN) values used are approved Seneca II CN values (see Appendix 7-12, Postiming
Drainage Control). Values were adapted from Urban Hydrology for Small Watersheds, Technical Release
No. 55 (TR-55), Soil Conservation Service, 1986.
SEDCAD 4
WATERSHED ID
Structure 4 - SWSt
Subwatershed -Channel PM-8
Watershed Area:
52.3
Sedimentology: k Factor and Control Factor
VEGETATION HYDROLOGIC k CONTROL AREA
WATERSHED TYPE COVER SOIL GROUP FACTOR FACTOR (acres)
Aspen/Mountain Brush Good (>70%) C 0.37 0.042 20.9
Reclaimed Fair (30 - 70%) C 0.16 0.043 31.4
Total 52.3
0.24 0.043
The soil erodibility factor, "k-Factor", values were determined based on Seneca II soil survey information (see Tab 9,
Exhibit 9-1, Soil Types and Sample Locations, and Attachment 9-6) as presented in Soils oI Colorado, Loss Factors and
Erodibility, Soil Conservation Service, 1983.
The Control Factor values were adapted from the Yoast and Seneca II-W permit application packages. These values are
presented in each permit in the Drainage and Sediment Control Plan attachment, which is located in Tab 13 of the
respective permit documents. The values are based on Renard, et al. (Renard, K.G., Foster, G.R., Weesies, G.A.,
McCool, D.K., and D.C. Yoder, coordinators, 1996. Predicting Soil Erosion by Water. A Guide to Converation Planning
with the Revised Universal Soil Loss Equation (RUBLE) .Agricultural Handbook 703. U.S. Department of Agriculture.
TR-42
7-6f.3A-21
Revised 09/07