ENFORCE26208

• Permit No: C1996083
• IBM Index Class Name: Enforcement
• Doc Date: 3/29/1999
• Doc Name: BOWIE 2 MINE GOB PILE GEOTECHNICAL FIELD & LAB STUDY PN C-96-083
• From: DMG
• To: JOE DUDASH
• Violation No.: CV1999004
• Media Type: D
• Archive: No

Ill IIIIIIIIIIIII III
999
DIVISION OF MINERALS AND GEOLOGY
Ueyartment of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80?03
Phone: [phone]
FAY: 1303) 83?-8106
DATE: March 29, 1999
TO: Joe Dudash
FROM: Jim Pendleton
STATE OF COLORADO
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r;/L'~I'
DIVISION OF
MINERALS
GEOLOGY
RECLAMATION
MINING•SAFETY
0111 Owens
Governor
Greg E. Walther
E.vecuuve Dveclor
Michael B. Long
Division Di.ector
RE: Bowie No. 2 line G Pile - Geotechnical Field & Lab Study
rmit No: C-96-083)
I have reviewed the study report submitted by Jim Stover, P.E., consultant to Bowie Resource
Limited (BR.L.) for their Bowie No. 2 Mine. This study was prepared by Norm Johnston, P.E. of
Lambert & Associates, Inc., subcontractor to Mr. Stover for BRL. In response to your earlier
request for verification of compaction achieved within the lowest 20 feet of the GOB pile, Mr.
Stover submitted a proposed methodology prepared by Mr. Johnston of Lambert & Associates
last December. Norm Johnston recommended sampline the density of the in-place lowermost
twenty feet of GOB material, which was previously untested, using thin-walled Shelby tubes and
California split spoon samplers. This study was performed incompliance with the proposed
methodology submitted by Mr. Johnson.
Lambert & Associates supervised the collection of samples in three bores wittti^ the Buwie #2
G(~B pile. Samples were collected using thin-walled Shelby tubes when possible, in order to
minimize disturbance of the samples. When resistance proved too great for the relatively weak
Shelby tubes, sample collection was completed using a thicker walled split barrel California
sampler. The thickness of the California barrel causes the sample to be more disturbed, which
can invalidate the density of the specimen. Lambert & Associates then completed laboratory
analysis of the collected specimens, including additional comparative Proctor analyses, and
finally prepared the report of the field and laboratory results.
Lambert & Associates report is brief but straight forward. The report includes a brief text, a
typical cross section of the pile, boring logs, Proctor analyses reports, and a tabular summary of
the calculated density determinations (Figure 9). Borings #1 and #2, which are towards the back
of the pile penetrate a large upper thickness of properly certified GOB, and a portion of the
suspect lowermost 20 feet of GOB. Boring #3, located near the toe on the out slope of the GOB
pile, penetrates the lowermost 20.4 feet of GOB, the portion of the pile in question. As Figure 9
summarizes, the 7 tests completed in Boring #I and the 6 tests completed in Boring #2 each
determined the density of the GOB to exceed the 90% relative compaction standard specification.
However, of the ten determinations completed within Boring #3, three were less than the
specified 90% relative compaction (80%, 84% and 87%).