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

Section 2 - High thick fill in a road and mine bench
These types of areas were constructed using prudent
state-of-the-art construction techniques practiced at the
time of excavation. The road fill was constructed in areas
where excessive material was side cast down the bank.
Vegetation was not removed, nor was the fill compacted or
keyed into the hillside. The mine bench fills were
constructed by pushing material over the crest of the bench
in a similar manner. Slopes in these areas often exceed
1: 1. Local erosion had occured due to water running over
the crest and down the slope.
The reclamation concept employed here was to flatten
the overall slope to 1.5: 1. by dozing the material down-
slope. (Photograph 2) . In areas where it was impossible to
ted in
ure 8, it
achieve a slope of this. 11 as materialdupathe slope and a
necessary to pulll
and dispose of
it in an approved location. The final configuration was
subsequently seeded and mulched. A berm and diversion ditch
were placed at the crest of the fill . A final procedure was
the placement of a small bench and catchment basin at the
toe of the slope, where possible.
Conclusions '
• As previously discussed, the factor of safety achieved
by reducing the slope to 1.5: 1 is 1.3. A close inspection
of this test section indicated no evidence of incipient
tension cracks near the crest of the slope nor any seeps on
the face of the slope. In addition, there was no evidence
of erosional problems anywhere on the test section. Very
small rills and gullies were noted that could be eliminated
by traversing the slope after final grading by the doze .
The small bench and basin at the. toe of the slope appeared
to function very well , both in the sense of stabilizing. the
slope and impounding surface runoff from the slope due to
erosion before the vegetation had established itself.
However, this procedure should only be applied to the mine
benches and not to the haul roads, as construction of
benches and catchment basins in similar areas of the haul
road would cause more harm to the environment as compared
to the small stability benefits.
It appears that this test section wasas compete
succ-
ess and should continue to be a p Post
ng
reclamation plan.
Section 3 - Thin sliver fill
This test section was placed in an area where a minor
amount of material had been casted The fill itself idswveryethinPe of a usuallyi
ne
bench or road cut. not
h