PERMFILE40093

• Permit No: C1981022A
• IBM Index Class Name: Permit File
• Doc Date: 5/14/2003
• Section_Exhibit Name: 2.05 Minimum Requirements for Operation and Reclamation Plans
• Media Type: D
• Archive: Yes

Sian - 2.05.3
Where: phi = Internal friction angle
• cohesion =Cohesion of material
gamma =Unit weight of material
The material characteristics from all three mines were used to calculate a safety factor for the East
Yard pile. The factor of safety against failure for final design conditions for the East pile was
determined utilizing acomputer-assisted limit equilibrium method of slices. The program used to
analyze the stability of the East Yard pile (GEOPRO) utilizes the Bishop's method of analysis. The
GEOPRO program was developed by Dr. N. F. Nash, under the company name DataSurge. The
most conservative factor of safety (lowest) was generated using the material characteristics from the
Blue Ribbon Mme site. These materials came from the nearby West Elk Mme and are physically
similar to those generated by the Sanborn Creek Mme having come from roof falls and mine
development in the Sanborn Creek and Beaz Mmes. The stability analyses indicated a minimum static
safety factor for the East Yard pile slopes of 1.6.
The East Yard pile area will be reclaimed by grading bench surfaces and ouulopes to a stable
configuration with rounded edges blending with the surrounding terrain. The regraded surfaces will
be capped with a minirrnim of 4 feet of suitable soil materiak from the Elk Creek soil stockpile
and/or other sources and revegetated.
West Valley Coal Refuse Pile -The West Valley coal refuse pile site, located in the fast ephemeral
drainage to the west of the existing Elk Geek surface facilities, was selected from several potential
sites evaluated because existing slopes are f7aner than several of the other prospective disposal areas,
upslope drainage can be readily diverted, the area provides sufficient disposal capacity for currently
anticipated future mining operations, and the area is readily accessible from the existing mice facilities.
• The West Valley refuse pile will provide additional disposal capacity for approximately 120,000 cubic
yards of refuse material. Based on projected mining rates, the additional available capacity should be
adequate to support current and anticipated future mining operations. The facility will be accessed
from the new West Valley haul road.
The refuse maceriak to be placed in the West Valley refuse pile will be essentially the same as those
now going to the East Yard pile since they will come from the same or similar sources. The stability
of the West Valley refuse pile was analyzed using essentially the same material characteristics as used
in analyzing the East Yard pile and the program PGSTABL (Version 6H, Purdue University, 1988)
which utilizes the Modified Bishop Method. The stability analyses indicated a min;m,,m static safety
factor for the West Valley coal mine refuse pile slopes of 2.1. The West Valley coal mine refuse pile
was designed and it's stability evaluated by Westec as documented by the design report included in
Exhibit 2.05-E4, Mine Development Rock/Coal Refuse Facility Design. Desigtu were reviewed and
modified as appropriate to address DMG concerns byBalaz &Associates.
Soil materials from the West Valley refuse pile has been stockpi]ed in the expanded Elk Creek soil
stockpile for future reclamation use. Surface drainage from the refuse pile, stripped areas, and
adjacent areas as well as any infiltration intercepted by the undertirain will be routed to Sedimentation
Pond Cto allow settlement of suspended solids prior to discharge to the North Fork of the Gunnison
River. At anypoint in time, the area stripped for subsequent refuse placement and related activities u
not anticipated to exceed approximately one-third of the overall refuse pile footprint. The progress
and timing of refuse pile construction will be wholly dependent on the amount of coal mine refuse
generated by ongoing mining operations. This amount can vary significantly dependent on mining
conditions but is projected to range from approximately 3,000 to 6,000 cubic yards annually The
West Valley coal mine refuse pile area will be reclaimed in a manner similar to that described for the
• East Yard pile.
PR04 2.05-47 Revised May 2001