PERMFILE60677

• Permit No: C1981012
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 30 STABILITY INVESTIGATION PART 2
• Media Type: D
• Archive: No

SCOPE
This report presents the results of our Supplemental Stability Investigation for
the existing and proposed configurations of the Refuse Disposal Area (RDA) located
west of the Basin Resources Golden Eagle Mine in Weston, Colorado. Construction
of the RDA began in 1983. Several previous investigations of the RDA stability
and/or density have been performed. The purpose of this investigation was to:
1. Review the previous stability analyses and strength testing performed.
Review and analyze previous moisture-density testing and water level
measurements;
2. Develop an understanding of the construction procedures used to build
the existing RDA; particularly the initial stripping, drain construction,
toe buttress construction, and fill placement and compaction
procedures;
• 3. Perform additional field and laboratory investigations to evaluate
current groundwater conditions within the RDA and to obtain addkional
information regarding the strength, gradation and in-place moisture
density of the coal refuse;
4. Analyze the stability of the existing and proposed RDA configurations
including a parametric analysis of varying refuse material properties,
slope face configurations and several water level and earthquake
conditions;
5. Develop alternatives for construction procedures related to staging of
the pile construction, the feasibility of installing roads across the pile
surface as it is being constructed, and the effects of constructing the
RDA from coarse refuse and rock. Investigate the feasibility of an
uncompacted zone at the back of the RDA; and
6. Develop recommendationsforcontinuedinspection,compactiontesting
and groundwater monitoring.
The current investigation included consideration of geotechnical aspects
• related to stability, internal drainage and construction procedures and testing.