2010-10-07_PERMIT FILE - C1994082

• Permit No: C1994082
• IBM Index Class Name: Permit File
• Doc Date: 10/7/2010
• Doc Name: Post Mining Channels SEDCAD Results/Channel YPM-1 to YPM-8
• Section_Exhibit Name: Tab 13 Attachment 13-12 Appendix 13-12.3
• Media Type: D
• Archive: No

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Yoast Mine
Postmine Channel Design
HYDROLOGIC INPUT PARAMETERS
SEDCAD 4
Channel YPM-5-1
OPTION 2
Watershed ID -Structure 10 - SWS1
wJatershed Area: 45.7
Curve Number:
HYDROLOGIC CURVE AREA
WATERSHED TYPE VEGETATION COVER SOIL GROUP NUMBER (acres)
Reclaimed Fair (30% - 70%) B 71 40.68
Aspen/Mountain Shrub Gcod (>70%) 8 30 1.21
Aspen/Mountain Shrub Good (>70%) D 48 0.99
Sagebrush Good (>70%) D 55 2.77
Total 45.7
CURVE NUMBER 68
SEDCAD 4
Channel YPM-5-1A
OPT10N 2
Watershed ID -Structure 10 - SWS2
~Natershed Area: 7.2
Curve Number:
HYDROLOGIC CURVE AREA
WATERSHED TYPE VEGETATION COVER SOIL GROUP NUMBER (acres)
Reclaimed Fair (30% - 70%) B 71 7.24
Total 7.2
CURVE NUMBER 71
Vegetation cover conditions presented in Tab 10, Vegetation, Attachment 10-1, 1990/1992 Vegetation
Baseline Report, Yoast Study Area (ESCO Associates, 1993). Approved Yoast Mine curve numbers are
presented in Attachment 13-12, Postmining Drainage and Sediment Control ,Table 13-12.1. Values were
adapted from Urban Hydrology for Small Watersheds, Technics! Re/ease No. 55, Sail Conservation Service,
1986.
TR-37 13-12.3-25 Revised 02/08