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

The part north of the gully is partly in colluvial soils behind
the lamphouse, the remaining part is in rocks of the Mesaverde.
The cut portion in colluvium shows moderate sloughing and rock-
fall. Moderate to severe sloughing can also be observed in the
cut part in rock. The height of the cut is relatively low, not
exceeding some 35 feet above the portals and 20 to 35 feet in
the south cut portion. The cut slopes are on the order of 50 to
600.
The storage yard cut is very high cut reaching a height of
100 to 200 feet. It has different slopes ; lower cut portions
are covered by rockfall debris that have slopes around 450.
Higher cut portions are steeper , up to vertical . The overall
cut slope, not including rockfall debris parts, is on the order
of 70 to 800. The overall stability of the cut appears to be
satisfactory, but the slope is subject to severe rockfall. Some
undercutting of the crest can be observed. No ground water
seeps have been observed on the cut face .
A low angle cut is present along the east side of the
storage yard. This cut has been made approximately along the
bedding plane of the bedrock, which dips about 100 to the west
at this location.
Several fills can be identified in the No. 1 mine area.
• They include , from north to south, the fan fill , the bench
fill , the "bin" fill and the storage yard fill .
The fan fill is a minor fill between the mine portals and
the north fan ; it extends down to the haul road and farther
below it (some 70 feet) . The fill surface shows moderate
rilling , erosion and sloughing .
The bench fill is located in the main gully below the
portal area. It appears to extend some 250 feet below the bench
crest , although it is likely that the fill is a very shallow
sliver or outwash over much of its height. This fill may be of
appreciable thickness below the mine bench. Severe rilling and
erosion is present on the fill surface.
The bin fill provides a narrow passage across a large
avalanche gully from the portal bench to the storage yard. It
is very probably a thin, sliver-type fill , with an approximate
maximum height of 50 feet. Outwash from the fill extends
several hundred feet down the gully, to the confluence with the
bench fill gully. Severe erosion and sloughing of this fill is
causing the failure of a small timber crib wall at the
narrowest portion of the fill . The extent of the fill west of
the road in the avalanche gully is uncertain, since it was
covered by snow at the time of mapping .
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GEO-HYDRO CONSULTING,INC.