REP16163

• Permit No: M1988112
• IBM Index Class Name: Report
• Doc Date: 7/14/1993
• Doc Name: SAN LUIS MINE PHASE II RAISE 1 DESIGN REPORT
• Media Type: D
• Archive: No

i

San Luis Mine -Phan II, Raise 1 Desi~ Report
1.0 INTRODUCTION
1.1 General
Battle Mountain Resources, Inc. (BMRI) San Luis Project has initiated work on the fast
' embankment raise of the tailings disposal area. The conceptual design and stability analysis for the
tailings facility were presented in the San Luis 112 operating permit amendment. As discussed in
Section D.6 of the permit amendment, prior to construction of the raise, geotechnical testing of the
' insitu tailings material will be performed to verify the conceptual design. Steffen Robertson and
Kirsten (U.S.), Inc. (SRK) designed the tailings facility, and was retained to confirm the
' embankment raise design and the suitability of the insitu tailings. This report presents the results
of the tailings investigations and the stability analyses used to confirm the raise design and refers
to information presented in the original permit (Permit No. M-88-112, "Perrhit") and the permit
' amendment (Amendment).
1.2 Background
The embankment raise discussed herein corresponds to the first of two raises required for Phase II
operations as presented in the Amendment. The existing initial Phase I embankment consists of a
zoned earthfill structure with a crest to tce height of approximately 120 ft, 3EI:1V downgradient
slopes and 2.SH:1V upgradient slopes, with a crest width of 30 ft. Tha embankment was
' constructed to an elevation of 8590 ft.
' As presented in the Amendment, the fvst raise would be constructed by upstream methods when the
,~? tailings elevation reached 8582 ft. The raise was designed to be constructed to a crest elevation of
8605 ft with 3H:1V and 2.SH:1V downgradient and upgradient slopes respectively. The
' r downgradient slope of the raise was designed to be founded on the Phase I embankment while the
upgradient slope would be founded on previously deposited tailings.
Due to concerns that the tailings would reach elevation 8582 during the winter off 1993-1994 when
it would be difficult to wnstruct the raise, BMRI plans to construct the raise irlread of schedule.
Currently, raise construction is anticipated to occur with tailings in the impoundment at an elevation
of 8570 ft. Thus, the raise will require more earthftll and be founded to a greater extent on the
existing embankment with shallower tailings deposits beneath the raise than was originally
conceived. This will have the beneficial effect of increasing stability of the raise.
..
. ,'i)
is
' I July 13, 1993 1 SRK Project No. 14719