1987-12-01_PERMIT FILE - C1981017 ‎(289)‎

• Permit No: C1981017
• IBM Index Class Name: PERMIT FILE
• Doc Date: 12/1/1987
• Doc Name: Geotechnical Investigations Mine Portal Benches and Haul Roads
• Section_Exhibit Name: Chapter V Appendix V-E-II
• Media Type: D
• Archive: No

From the stability point of view, the majority of road
cuts was classified as featuring minor to moderate stability
problems. Only one important stability problem was classified;
a zone of severe erosion and undercutting of the crest of the
cut.
Practically all fills have been found to have either no or
. minor stability problems.
Road B (see Table 4) is a short road section, 3, 700 feet
long, with an average grade of 10%, between the junctions of A-
and E-roads, and C- and D-roads. The major part of the road is
again in the cut and fill configuration. Nearly all road cuts
have been excavated in soils; the height of the cuts is limited
to no more than 40 feet. All cut slopes are steep (up to 600) ;
no steeper slopes have been identified. The majority of the
fills are low (below 20 feet) ; the remaining fills are no more
than 40 feet high. All fill slopes appear to coincide with the
angle of repose (30 - 450) .
Stability of the road cuts ranges from minor to important
stability problems. Minor to moderate sloughing and erosion of
the cuts is common, with occasional severe sloughing, erosion
and undercutting of the cut crest. A zone of common active
slumping was identified for approximately 800 feet of cut;
almost the entire length of the B-road cuts is in a zone where
the natural ground exhibits evidence of downslope movement by
soil creep. This phenomenon does not seem to necessarily result
in significant instability of the cuts, but may contribute to
the active slumping described above.
Road C (see Table 5) from the junction of B- and D-roads
to No. 4 mine bench is 15, 800 feet in length , with an average
grade of 8. 0%. More than half of the road is in a cut and fill
configuration , and nearly 20% of the road length has no sig-
nificant earthwork. The majority of cuts are in rock , and are
under 40 feet in height. A few cut slopes stand over 60 feet
high. The slope of cuts tends to be relatively steep, usually
up to greater than 600. The majority of fills are less than 20
feet high and have been cosntructed at the angle of repose (30
to 450) . Fills occasionally range up to greater than 40 feet in
height, at the angle of repose.
Stability problems along road cuts range from minor to
important ; but most of the road has only minor sloughing and
erosion problems. Important stability problems are primarily
related to erosion, where severe gullying and sloughing has
occurred. Major problems of this type are frequent through
avalanche zones. An important area of mudflow and slumping was
identified at approximate station 63+50 at a stream crossing
• where slumping of natural slopes into the stream has occurred.
This instability is not a result of road construction, but may
24
GE04MRO CONSULTING,INC.
l�