REP13486

• Permit No: C1996083
• IBM Index Class Name: Report
• Doc Date: 12/22/1998
• Doc Name: BOWIE 2 MINE GOB PILE 2ND RESPONSE TO DIVISION ISSUES PN C-96-083
• From: DMG
• To: JOE DUDASH
• Permit Index Doc Type: STABILITY REPORT
• Media Type: D
• Archive: No

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STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Depanmenl of NaNral Resources
131 3 Sherman St., Room ? 15
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
DATE: December 22, 1998
TO: Joe Dudish
FROM: Jim Pendleton
RE: Bowie No.-2 Min Pile -Second Response to Division Issues
~~
DEPARTMENT OF
NATURAL
RESOURCES
Ruy Romer
Governor
lames S Lochhead
Executive Dneclor
hlichael8 Long
Division Dueclor
rmit No: C-96-083)
I have reviewed the second supplemental response to comments letter submitted by Jim Stover,
P.E., consultant to Bowie Resource Limited (BRL) for their Bowie No. 2 Mine. Mr. Stover
originally responded to our concerl3s in a letter dated September 28, 1998. In this second letter.
dated December 18, 1998, Mr. Stover responds to issues forwarded by the Division on
November 17, 1998.
Proctor Comparison (Item #2)
Jim Stover has attached a letter authored by Noma Johnston, P.E. of Lambert & Associates,
geotechnical consultant to BRL. In this letter Mr. Johnston provides additional information in
support of his earlier opinion that there was no reason to be concerned with relative compaction
results in excess of 1 15%. Mr. Johnston observes [hat the use of the Standard Proctor test
method, which applies the lighter specified rant load, makes it plausible to have field densities in
excess of 1 ] 5%. Further, he commented that only 5 of 53 density tests performed exceeded
115%. More importantly, Mr. Johnston presents Lambert & Associates methodlogy for the
performance of field density tests. In my opinion the methodlogy is acceptable and should result
in representative determinations if applied. Therefore, I consider my concern regarding the
magnitude of field density de[enninations to have been satisfied by this supplemental response.
Compaction Testing of Lowest 20' Lift (Item #4)
In response to our earlier request for verification of compaction achieved within the lowest 20
feet of the GOB pile, Mr. Stover now submits a proposed methodlogy prepared by Mr. Johnston
of Lambert Rr Associates. Norm Johnston recommends sampling the density of the in-place
lowerntost GOB material, which was previosuly untested, using thin-walled Shelby tubes. I am
prepared to accept Mr. Johnston's proposal, if BRL will agree to the two following conditions.
(1) I concur with Mr. Johnston's opinion that difficulty may be encountered if large
cobbles are encountered. Mr. Johnston states that the sampling tubes may be bent and