2017-08-15_PERMIT FILE - C1980007A ‎(3)‎

• Permit No: C1980007A
• IBM Index Class Name: Permit File
• Doc Date: 8/15/2017
• Section_Exhibit Name: Exhibit 66 Mine Water Control Plan
• Media Type: D
• Archive: Yes

West Elk Mine - Mine Water Control Plan
Mountain Coal Company
3.0 SEDCAD+ INPUT PARAMETERS FOR SUBWATERSHEDS
3.1 Subwatershed Boundary
Subwatershed boundaries were digitized in AutoCAD using the site contour maps. Map 54
depicts the main mine site, and Map 54B depicts facilities in Sylvester Gulch.
3.2 Soil Type & Land Cover
The soil type -land cover complex determines a number of SEDCAD+ input parameters relating
to both hydrology and erosion. Custom soil maps and reports were obtained for the main mine
site and Sylvester Gulch from hftp://websoilsurvey.nres.usda.gov/, USDA's online GIS -based
soils data source. Soil boundaries were digitized in AutoCAD from the map images. The
following soil types were mapped within the site boundaries:
Soil I.D. Soil Name
2
Absarokee-Work loams
13
Beenom-Absarokee association
17
Breece loam
39
Fughes loam
74
Torriorthents-Haplargids
75
Torriorthents-Rock outcrop
85
Water / Marsh
124
Coberly-Falcon, dry complex
130
Cryoc h repts-Cryobo rolls- Rubble land complex
153
Haploborolls- Ustochrepts- Rock outcrop complex
157
Herm-Fughes complex
158
Herm-Fughes-Kolob family complex
188
Taterheap-Papaspila complex, 5 to 40 percent slopes
189
Taterheap-Papaspila complex, 40 to 65 percent slopes
192
Torriorthents, cool -rock outcrop
Land cover was determined from field inspections and viewing the aerial photos over which the
custom soils maps are drawn. Areas erroneously shown as Water / Marsh were revised to
reflect the adjacent soil map unit. The following land cover types were present on the site:
• Coal product was developed to represent areas covered by coal stockpiles.
• Disturbed represented bare or gravel -covered materials storage benches, unreclaimed
refuse piles, and bare earth.
• Impermeable land cover includes open water and HDPE pond liner.
• Paved includes areas covered in asphalt, concrete, or building rooftops.
• Pasture includes undisturbed grassy areas and reclaimed soil stockpiles
• Revegetated areas include reclaimed refuse piles. They are differentiated from pasture
to reflect soil compaction by heavy equipment.
• Oakland cover reflects undisturbed wooded areas, chiefly containing scrub oak, aspen,
and mountain brush species.
Coal product, disturbed, impermeable, paved, and revegetated areas were assigned soil
parameters selected to reflect their disturbed condition. Oak and pasture areas were assigned
soil parameters based on the actual soil type.
Tetra Tech October 2010 3