PERMFILE127218

• 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 7-6c.1 Addendum 7.6-1A
• Media Type: D
• Archive: Yes

Seneca II Mine
Pond 004
HYDROLOGIC INPUT PARAMETERS
SEDCAD 4
WATERSHEDfD
Structure 8 - SWS1
Subwatershed -Channel PM-11
Watershed Area:
141.4
Curve Number:
HYDROLOGIC CURVE AREA
WATERSHED TYPE GROUND COVER SOIL GROUP NUMBER (acres)
Reclaim >3 years Good (>70%) B 62 133.7
Sagebrush Fair D 70 7.73
Total 141.4
CURVE NUMBER 62
Approved Seneca II Mine curve number (CN) values are presented in Appendix 7-12, Postiming Drainage
Control. Values were adapted from Urban HydroMgy for Sma!! Watersheds, Technical Release No. 55 (TR-
55), Soil Conservation Service, 1986.
SEDCAD 4
WATERSHED ID
Structure 8 - SWS1
Subwatershed -Channel PM-11
Watershed Area:
i 41.4
Sedimentology: k Factor and Control Factor
VEGETATION HYDROLOGIC k CONTROL AREA
WATERSHED TYPE COVER SOIL GROUP FACTOR FACTOR (acres)
Reclaimed Good (>70%) B 0.16 0.043 133.7
Sagebrush Fair D 0.37 0.042 7.73
Total 141.4
0.17 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 Type and Sampling Locations, and Attachment 9-6) as presented in Soils o1 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 Ptan attachment, which is located in Tab t3 of the
respective permit documents. The values are based on Renard, et al. (Renard, K.G., Foster, G.R., Weenies, G.A.,
McCool, D.K., and D.C. Yoder, coordinators, 1996. Predicting Soil Erosion by Water: A Guide to Convention Planning
with the Revised Universal Sail Loss Equation (RUBLE). Agricultural Handbook 703. U. S. Department of Agriculture.

TR-42 7-6c.1A-26 Revised 09/07