PERMFILE47451

• Permit No: C1980007A
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: Exhibit 51 Lower Refuse Pile
• Media Type: D
• Archive: Yes

Mountain Coal Com pany, L.L.C. Exhibit 51
West Elk Mine Lower Refuse Pile
investigators is summarized on Table 7. An effective stress friction angle of 30 degrees and effective stress
• cohesion of 288 psf were used. This is believed [o represent the performance of the waste material when
compactedto a minimum density of 90% of Standard Proctor Density.
Table 6 - Summarv of Strength Parameter Data
•
_~
Material Description Dry Uoit Weight (pcf) Cohesion (psQ Friction.4ngle Comments
(degrees)
Debris Flow Soils 113.7 0 34.0 I
105.0 0 33.7 I
Colluvial Soils 100.0 300 30.0 2
120.0 300 30.5 ~
125.0 2000 10.0 ~
110.0 447 19.0 3
109.0 1600 43.0 4
106.6 900 25.0 4
108.7 1400 10.0 4
102.8 0 35.0 4
112.4 0 50.0 4
117.3 700 40.0 4
111.2 2100 10.0 4
Coal Waste 93.0 706 II.0 5
80.0 89 32.0 5
115.0 0 33.0 5
80.0 118 10.0 5
121.0 346 24.0 5
66.0 288 30.0 5
45.0 72 41.0 6
68.0 72 41.0 6
Comments:
I . From Triaxial Shear Strength Testing by Rocky Mountain Geotechnica1,1985.
2. From Back Analysis by Michael Baker Associates, 1984.
3. From previous testing by Rocky Mountain Geotechnical in the North Fork Valley.
4. From Direct Shear Testing bylEC0.1976
~. Tests on samples from a temporary waste pile east of the mine portals.
6. Tests on samples from a waste pile adjacent to the warehouse area.
5.5.3 PiezometricPressure
Positions of [he water table and associated piezometric pressures were determined for stability models
utilizing the following information:
• Data collected from piezome[ers and monitoring wells installed during the field investigation
performed in June of 1985;
• Data based on anal}•ses referenced in Section ~.4; and
• • On other reasonableassumptions.
y
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