REP14030

• Permit No: M1988112
• IBM Index Class Name: Report
• Doc Date: 10/24/1993
• Doc Name: CONSTRUCTION STATUS REPORT PHAE II EMBANKMENT RAISE & LINER INSTALLATION BATTLE MTN RESOURCES
• Media Type: D
• Archive: No

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STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources
131 3 Sherman St., Room 215
Denver, CO 80203
Phone: [phone]
FAX: [phone]
October 24, 1993
TO: Larry Oehler
FROM: Allen Sorenson
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Roy Romer
Governor
Michael B. Long
Drvwiun Dueaor
RE: Construction Status Report - Phase II Embankment Raise and
Liner Installation, Battle Mountain Resources, Inc. (BMRI),
San Luis Project, File No. M-88-112
I have reviewed the Construction Status Report prepared by BMRI's
design engineer, and offer the following comments.
Embankment Raise Fill
BMRI has proposed a change from the approved specification for
gradation limits for the Phase II, Raise 1 embankment materials.
The argument is made that due to the slower rate of rise within the
impoundment, that a free draining material within the raise is not
required to provide for desiccation of the beach tailings. Also,
the point is made that the potential for free water to impound
against the embankment fill no longer exists in that the free water
pond is remote from the embankment.
The Division can approve the specification change for embankment
fill only with the understanding that an in-depth characterization
of the Raise 2 lift foundation, more rigorous than that accepted
for Raise 1, will be required before Raise 2 construction could
proceed. Also, BMRI must quantify the freeboard provided by
tailing between the free water pond and the embankment in terms of
measured slope of the tailing surface, distance to the free water
pond, and the probable maximum precipitation event. BMRI should
commit to maintenance of a minimum distance between the main
embankment and the free water pond as an operating parameter.
The operator has indicated that Raise 1 has been constructed in
lifts of up to 4 feet in thickness. The operator must demonstrate
that the specified density and compaction is being achieved at the
base of these lifts. Density and compaction testing of embankment
materials should focus on the base of the lifts, and should be an
oversight item for the third party engineer.
The Division should be concerned with the way in which the
specification change is rationalized by the design engineer for the
following reasons: The statement is made in the Construction status
report that the tailing deposited adjacent to the Phase I