PERMFILE134266

• Permit No: C1980007
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 70 REFUSE PILE EXPANSION
• Media Type: D
• Archive: No

REFUSE PILE EXPANSION
Sylvester Gulch Facilities Area (PR#07). Subsoil
from Phase 2 may also be used for mine
development projects. Subsoil removed during
Phases 3 and 4 will be sufficient for the reclamation
of the RPE, and will be placed in a stockpile to be
determined by MCC prior to beginning Phase 3.
Sediment control ditches, clear water diversion
ditches, and a sediment settling pond were
constructed to control surface runoff prior to Phase
I stripping operations. The sedimentation pond was
constructed along the north toe of the RPE as shown
in Figures L-2 and L-3. Sediment control ditches
and berms were placed on the north and west sides
of the RPE. Clear water diversion berms were
placed [o the south and west sides of the RPE.
Figure L-3 illustrates the ditch and berm layout.
Clear water on the west side will be directed into
Svlvester Gulch. Clear water on the south side will
be directed into the unnamed gulch between Box
Canyon and Sylvester Gulch where it eventually
passes through an existing culvert under Highway
133. Ditch locations are also shown on Map 54.
The RPE area designated as Phase I and 2 were
lined with HDPE. Clay was also considered for the
;lining of the RPE. Refer to the slope stability
.~ analysis (Appendix K) for geotechnical analytical
data on the insitu clay, and stability calculations
using either clay or HDPE liners. Both clay and
HDPE provided sufficient and similar slope stability
results.
An underdrain, designated within this report as a
rock drain, will be used to collect any refuse fill
drainage. The rock drain will be constructed as
shown in Figure L-l; the subsoil will be excavated
to the elevation shown in Figure B-13. Drainage
captured by the rock drain and all disturbed drainage
runoff will be directed into the sedimentation pond.
The portion of [he underdrain underlying Phase 1
and 2 were constructed during 1997. Construction
of the underdrains was certified. complete with
photographs in the third quarter site inspection
report, dated November 1997.
Table 2 presents actual coal refuse production for
1997 and 1998, and projects the amount of refuse to
be generated through ?006. Construction of the
RPE was not completed until the end of 1997, so no
.,refuse was placed during this time. Table 3 gives
the resulting life-span for each sub-phase, assuming
placement of refuse in the RPE begins April 1,
1997. Phase 1 was completed in December 1997.
2.1.2 Phase Two -Initial Refuse Placement
Phase 2 began immediately following completion of
Phase I. Refuse is currently being placed in the
depression generated during Phase 1. All cut areas
from which subsoil was removed during Phase 1
will be backfilled with refuse to bring the location
back to approximate original grade. Additional
topsoil and subsoil will be removed along the south
and eastern edges of the RPE and stockpiled north
of Highway 133. The rock rock drain will be
extended to the east along the north toe of the RPE.
The quantity of cut, fill and disturbed area for Phase
2 is shown in Table 1.0. Currently MCC is
generating very little refuse from the mine. The
majority of the waste being placed in the RPE is
from shaft construction, which is expected to be
completed by late summer 1999. Given the very
small amount of refuse that is projected to be
generated, Phase 2 is expected to last for sometime.
See Figures B-IS through B-17 for Phase 2
construction details.
2.1.3 Phase Three -Main Buildout
Phase 3 will be the main buildout of the RPE as
depicted in Figures B-18 through B-20. Additional
topsoil and subsoil will be stripped from the south
hillside as the pile is built up the slope at a 2.5-
horizontal to 1-vertical slope. Removed soil will be
stockpiled north of Highway 133. Sediment control
ditches will be extended on the west, south and east
sides. Reclamation will be accomplished by placing
an average of 9 to 12 inches of subsoil and topsoil
respectively on the finished slopes, resulting in an
average soil cover thickness of I8 [0 24 inches. (See
the Reclamation discussion in regards to a variance
to the four feet of cover requirement.)
The quantity of cut, fill and disturbed area for this
phase is shown in Table I.0
2.1.4 Phase Four -Completion
Phase 4 +vill complete the RPE as depicted in
Figures B-?I through B-23. The refuse will be
Harding Lawson Associates 2