2009-09-21_PERMIT FILE - C1980007 ‎(2)‎

• Permit No: C1980007
• IBM Index Class Name: Permit File
• Doc Date: 9/21/2009
• Section_Exhibit Name: Exhibit 51 Lower Refuse Pile
• Media Type: D
• Archive: No

Mountain Coal Company, L.L.C. Exhibit 5l
West Elk Mine ~ Lower Refuse Pile
2.0 DESCRIPTION OF PILE CONFIGURATIONANDPHASlNG
•.
2.1 Lower Refuse Pile Configuration (January, 1996)
The pile layout as of January. 1996. is shown in Figure 2.OB and 2.OC in Appendix B. The original
desien phased the refuse pile into five specific design layouts (Phases 1 through V). The pile was
constructed according to this original phased design until the Phase IV configuration. The construction of a
new main access haul road in October of 1991 along the south and east edges of the current pile and the
change in both mining methods and coal seam reducing the quantity of refuse altered the layout of the
refuse pile. The March, 1993, revision eliminated Phase V and revised Phase IV as the final stage with
slopes averaging 2.SH to 1 V and a maximum pile height of 6310 feet. In January, 1996, the pile was
approaching the end of the Phase IV construction. The Marchl996 revision (see Section 2.2, below)
presents a redesigned Phase V for the LRP final configuration.
Rock material too large for utilization in the Lower Refuse Pile (LRP) underdrain has been placed as a
buttress no more than ten feet in height on the base of the east side of the Lower Refuse Pile. The buttress is
not necessary to increase the stability of the LRP in this area. It was constructed as a "stockpile" for large
rock that could also serve as armoring along the east slope base. The rock will remain upon final
reclamation. Prior to placement of rock. the pile slopes were properly compacted and sloped. An average
of one foot of subsoil was placed over the gob prior to the construction of the buttress, in compliance with
the requirementto place 9-12" of subsoil over the waste material.
• 2.2 Final Lawer Refuse Pile Configuration(Revised March, 1996)
- Figure 2.OD in Appendix B shows the final LRP configuration. The design maximizes storage and
meets required stability criteria. The pile was also extended upward along the north slope from the
bench at the 6230-ft contour at a 2H:1 V grade. The pile was also extended upward on the east slope at a
2H:1 V grade, beginning at a 10-ft offset from the existing shotcrete sediment ditch. The southern and
western slopes remained at the same grade. Access will continue [o be from the southeast as in Phase
IV, up to the final build-out elevation of 6330-ft (MSL).
When the pile was approaching the end of Phase IV, the volume of refuse in the LRP was approximately
900,000cubicyardsandtheremaining capacity for additional materials was estimated to be 360,000 cubic
yards. Refuse density was sampled a[ 59 pounds per cubic foot. A[ this deniin•, the remaining capacity
is 286.700-tons. In addition, the design included an average 18 inches of soil cover, or approximately
11,'_50-cy of subsoil and 11.250-cy of topsoil to cover the refuse placed for the new Phase V
construction. Topsoil and subsoil that were located on the north and east benches of the LRP were
moved to the west side of the LRP top, and later used for reclamation and/or moved to [he North Soil
Storage Area (for topsoil) and the Sylvester Gulch subsoil pile.
All ditches to handle sediment and clear water runoff were previouslyconstructed, per the original designs.
and were unmodified by the March 1996 design reconfiguration. Sediment laden runoff is directed into
constructed ditches which drain into the existing sedimentation pond. These ditches have been sized for a
100-year storm, 21-hour SCS Type II precipitation event (see Section 6.: ). Refer to Appendix L and
Exhibit 66 for surface hydrology computations for Phase V.

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