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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TR-37
Yoast Nline
Postrnine Channel Design
HYDROLOGIC INPUT PARAMETERS
SEDCAD 4
Channel YPM-6-2
OPTION 2
Watershed ID -Structure 9 - SWS1
West side subwatershed
Watershed Area: 5.5
Curve Number:
HYDROLOGIC CURVE AREA
WATERSHED TYPE VEGETATION COVER SOIL GROUP NUMBER (acres)
Reclaimed Fair (30% - 70%) B 71 5.54
Total 5.5
CURVE NUMBER 71
SEDCAD 4
Channel YPM-6-2
OPTION 2
Watershed ID -Structure 9 - SWS2
East side subwatershed
U'Jatershed Area: 20.3
Curve Number:
HYDROLOGIC CURVE AREA
WATERSHED TYPE VEGETATION COVER SOIL GROUP NUMBER (acres)
Reclaimed Fair (30% - 70%) B 71 17.33
Steep Mountain Brush Gocd (>70%) D 73 1.01
Sagebrush Good (>70°~) B 41 2.00
Total 20.3
CURVE NUMBER 68
SEDCAD 4
Channel YPM-6-2A
OPTION 2
Watershed ID -Structure 9 - SWS3
Watershed Area: 11.6
Curve Number:
HYDROLOGIC CURVE AREA
WATERSHED TYPE VEGETATION COVER SOIL GROUP NUMBER (acres)
Reclaimed Fair (30% - 70%) B 71 6.21
AspenJMountain Shrub Gaod (>70%) B 30 4.52
Aspen/Mountain Shrub Gocd (>70%) C 41 0'.88
Total 11.6
CURVE NUMBER 53
Watersheds, Technical Release No. 55, Soil Conservation Service, 1986.
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
13-12.3-24
Revised 02/08