GENERAL33946

• Permit No: M1988112
• IBM Index Class Name: General Documents
• Doc Date: 11/16/1992
• Doc Name: CROWN JEWEL PROJECT FN OK60-625
• From: DEPT OF ECOLOGY
• To: BATTLE MOUNTAIN GOLD CO
• Media Type: D
• Archive: No

~1~.'-
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Mr. A. Walter Wise
Page 3
November 6, 1992
Include periodic borings, instrumentation and the excavation of test
trenches. The trenches are particularly valuable in providing a large
scale check on the data generated by instrumentation and boring programs.
Finally, if at same future time, the slimes within the zone critical to the
integrity of the embankment are found to be at or near saturation the DSS
will not accept the continued use of the Knight Pidsold upstream construction
method. Analyses, purporting to show that in a saturated state, t:he response
of the slimes to dynamic loading will limit crest settlements to some
acceptable level, will not be accepted as justification for the continued use
of the upstream method. Furthermore, saturated materials within t:he zone
critical to the integrity of the impounding barrier will have to to treated to
permanently stabilize them.
FURTHER CONDITIONS ON APPROVAL FOR UPSTREAM CONSTRIICTION METHOD
It must be recognized that the Knight Pi€sold upstream scheme is still a
variant of the upstream construction method. The upstream method historically
emplaced slimes in a state that has shown a relatively high susceptibility to
static and dynamic slope failures. In fact, the DSS would not allow the
construction of an impoundment utilizing conventional upstream embankment
practices over saturated slimes. Knight Pidsold's upstream construction
schema appears to address many of the obvious shortcomings of the conventional
upstream method. However, given the relatively recent development of this
technique and the magnitude of the project, some form of peer review of the
embankment scheme should be provided, in addition to the regulatory oversight
from the DSS. This independent oversight would take the form of as expert or
board of experts that review the plans and periodically review key phases of
the construction and project operation. To function effectively, that review
must be independent of the project engineer. Thus, the owner, not the
engineer, would be responsible for hiring the reviewer(s).
If you wish to discuss this matter, please call us at [phone].
Sincerely,
-n~ c~ 5~,~(r
Melvin G. Schaefer, Ph.D, P.E.
Supervisor, Dam Safety Section
Water Resources Program
~_
Jerald LaVassar, P.E.
Dam Safety Section
Water Resources Program
MCS:JL:dkh
cc: Donald East, Knight Pi~sold
Anne Baldrige, Battle Mountain Gold Co.
Craig Stiles, Battle Mountain Gold Co.
Robert Raforth, Ecology
Patricia Crumley, Ecology
Alan Czarnowsky, ACZ Inc.