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

important instability includes large sloughs, slump zones, and
major landslides, with associated mudflows.. The landslides cut
back deeply into the natural slopes in areas of relatively
small cuts and appear not to be directly related to road con—
struction. Most fills have only minor instability. Moderate
instability includes erosion rills and sloughs. Important in—
stability problems consist of severe erosion gullies .and oc—
casional slumping of the fills.
4. 0 MINE BENCHES
4. 1 DOCUMENTATION OF MINE BENCHES
Documentation of the mine benches included the location of
cuts, fills and benches associated with the mine portal areas.
Features of the mine bench areas were plotted onto maps of 1" =
200' scale (Plates 4 through 7) . Areas described on the maps
include those of fill , cut in rock or colluvium, horizontal
bench areas , undisturbed areas , and areas covered by a thin
outwash from fill slopes. Portions of the mine bench areas,
subject to disturbance by avalanches , are also delineated on
the maps. The locations of special features such. as ditches,
sediment ponds, and evidence of slope instability are provided
when applicable. The documentation provided on the maps is
supplemented by individual descriptions of each mine bench ,
presented in section 4. 3. Details of the parameters described
for the cuts and fills are similar to those for the haul roads.
In addition, the written descriptions allow a more detailed
account of the character of the cuts and fills. Special
features and stability problems are presented in detail in
these descriptions .
Plates 4 through 7 include location maps of the mine bench
areas , and drainage plans for each mine bench. Drainage
features such as ditches and sediment ponds are documented as
they were observed at the time of mapping. Some of the features
shown on the drainage plans were not apparent at the time of
mapping , often due to snow or rockfall cover .
4. 2 DESCRIPTION OF MINE BENCHES
Mine No. 1 Bench (see Plate 4) was developed as two yards;
one is used as a mine bench with the mine portals located in
it. The second yard , located south of the mine bench, has been
used as a storage yard .
There are two significant cuts above the mine bench and
above the storage yard. The mine bench cut (port 1 cut) has
been excavated in various geologic units. A distinct gully,
just south of the lamphouse , divides this cut into two parts.
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GE044YDRO CONSWING,1NC.