2013-01-14_PERMIT FILE - C1996083

• Permit No: C1996083
• IBM Index Class Name: Permit File
• Doc Date: 1/14/2013
• Doc Name: 11/9/2012 Gob Pile #2 Expansion Buckhorn Stability Analysis TR76
• Section_Exhibit Name: Volume IX Coal Mine Waste Disposal Area No. 2
• Media Type: D
• Archive: No

Table 1.0 Analyses Methods and Results from SLIDE modeling
Analysis Method
Section ID
Minimum
Factor of
Safety
Comments
Janbu Simplified
A -A'
1.687
Janbu Simplified
D -D'
1.717
Janbu Simplified
E -E'
2.028
Janbu Simplified
F -F'
1.640
Global Minimum
Since the global minimum static F.S. of 1.640 for section F -F" is greater than the long -term
static F.S. of 1.5 required in Section 4.09.1 of the Regulations of the Colorado Mined Land
Reclamation Board for Coal Mining, the proposed expansion of CWDA Pile #2 appears to
meet all of the requirements for reclamation. All of the computed static factors of safety for
the cross - sections analyzed were in excess of the required long -term static F.S. of 1.5 as the
analysis results in Table 1. indicate.
CONCLUSIONS
If constructed as recommended, the proposed expansion of CWDA Pile #2 at Bowie Mine
#2 appears to provide adequate factors of safety with regard to slope stability of areas to
be reclaimed upon completion of the pile expansion. Field and laboratory testing of the gob
materials should be continued in order to provide current material properties for use in
future modeling of the coal waste piles at the Bowie #2 mine.
Thank you for the opportunity to work with you on this long -term project at the Bowie Mine
#2. If you have any questions about this analysis, please contact me at (970) 497 -8852 or
[e-mail].
Respectfully submitted,
� -� C. 2
Daniel C. Quigley, PE, PG
Buckhorn Geotech, Inc.
Appendices
A — Site Plan
B— Cross - section A -A', D -D', E -E' and F -F'
C— SLIDE® Model results- Sections A -A', D -D', E -E' and F -F'
Bowie Mine #2 — CWDA Pile # 2 Expansion PN 05- 126-GEO
REVISED Stability Analysis