REP35990

• Permit No: C1996083
• IBM Index Class Name: Report
• Doc Date: 7/12/1999
• Doc Name: BOWIE 2 MINE LAMBERT & ASSOCIATES ASSUMPTIONS PN C-96-083
• From: DMG
• To: JOE DUDASH
• Permit Index Doc Type: STABILITY REPORT
• Media Type: D
• Archive: No

iii iiiiiiiiniii iii
STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources
1313 Sherman St ,Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: (303)83?-8106
DIVISION OF
MINERALS
GEOLOGY
RECLAMATION
MINING•SAFETY
DATE: July 12, 1999
TO: Joe Dudash -
FROM: Jim Pendleton
RE: Bowie N Mine - mbert & Associates Assumptions
mit No: C-96-083)
ern o~~en:
Governor
GregE Watcher
E~eculrve Director
Michael B. LOng
Drvismn DireUOr
)n response to your recent inquiry, I reexamined the Bowie No. 2 Gob Pile stability analysis
prepared by Norm W. Johnston, P.E., of Lambert & Associates. As I understand your query, you
desire to know specifically whether Lambert & Associates' stability analysis demonstrates that
the refuse pile at Bowie No. 2 has a safety factor of 1.5 in it's present configuration.
On page four of the report, the third paragraph states;
"Our stability analysis is based on the assumptions of an intimate and competent contact
between the GOB fill material and the natural support material which include the organic
topsoil removed and the exposed surface of the natural foundation support soil materials
benched prior [o placement of [he GOB material."
This statement appears unambiguous, as far as it goes. However, the report does not state
whether Lambert & Associates performed any examination or completed any inquiries which
determined whether the foundation had actually been benched prior to the placement of GOB
material.
The fourth paragraph on page four of the Lambert & Associates' report reads;
"The benching of the natural foundation support soil materials to expose competent
support material reduces the potential for developing a predetermined failure plane along
the GOB/natural material contact. We suggest that future plans include benching into the
natural material to receive the fill material prior to placing additional GOB material. The
benching should continue into competent foundation support material as the GOB
material is placed as the pile height is increased. The benching concept is shown on
Figure 7."
Figure 7 in the report is entitled "Toe Key, Bench Concept". The note included on figure 7