1987-12-01_PERMIT FILE - C1981017 ‎(201)‎

• Permit No: C1981017
• IBM Index Class Name: PERMIT FILE
• Doc Date: 12/1/1987
• Doc Name: Geotechinical Investigations Mine portal Benches and Haul Roads- Table of Contents
• Section_Exhibit Name: Volume V V-E-11
• Media Type: D
• Archive: No

OBSERVATIONS
Geotechnical Report -
The above mentioned Geo-Hydro report addressed the
bedrock and surficial geology landslides and avalanches, and
methods of road construction and slope angles. The report
noted that:
- Development of the haul road system in Coal Basin
was a difficult task. With rugged mountainous topography,
steep slopes, severe erosion problems, potentially unstable
slopes and high avalanche danger comprise a set of
exceptionally unfavorable factors for road construction.
- Morphological features of the area have been very
much influenced by the harsh climate related to the
exceptionally high altitude. Erosional processes
significantly contributed to the rugged topography.
Frequent avalanches continuously modify the surface features
at numerous locations along the haul roads at several mine
benches.
Geo-Hydro found that high soil cuts have been excavated
in many road sections, with some grades exceeding 45
degrees, and that "the access to it (the slope of the cut)
is difficult or impossible". The report also states that
high rock cuts can also be found along some road segments
and are typically very steep, frequently up to vertical ;
although, again, ". . . access to the slopes is practically
impossible".
Geo-Hydros report goes on to provide very detailed
information on the geotechnical aspects of the haul roads.
Table 11 (Figure 2) in their report summarizes the
configurations and geotechnical conditions of the haul
roads. The overall stability of the cut and fill sections
of the haul roads is summarized as shown below:
Minor or No Moderate Important
Stability Problems Stability Problem Stability Problems
Cut - 60% 23% 17%
Fill - 63 13 4%
All of the important stability problems identified on
the haul roads have, for the most part, been attributed to
factors other than the existence of the haul roads. These
other factors include natural erosional process, avalanches
and natural slumping and creeping of steep slopes. A small
percentage of the important stability problem areas of the
road system may be due in part to the combined effects of
natural processes and the existence of the haul road.
However, this percentage is very small and for the most part
is insignificant.