2009-11-05_REVISION - C1996083 ‎(2)‎

• Permit No: C1996083
• IBM Index Class Name: REVISION
• Doc Date: 11/5/2009
• Doc Name: 2nd Geotechnical Adequacy Review ‎(Memo)‎
• From: Marcia Talvitie
• To: Joe Dudash
• Type & Sequence: TR64
• Email Name: JJD
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]

MY 0 P 2009

INTEROFFICE MEMORANDUM
Date: 05 November 2009
To: J. J. Dudash, Lead Specialist
From: Marcia L. Talvitie, P.E. 10
Subject: Permit No. C-1996-083 - Bowie No. 2 Mine
Technical Revision No. 64 (TR-64) - Coal Refuse Pile No. 4
Second Geotechnical Adequacy Review
COLORADO
DIVISION OF
RECLAMATION
MINING
SAFETY
Bill Ritter, Jr.
Governor
Harris D. Sherman
Executive Director
Ronald W. Cattany
Division Director
Natural Resource Trustee
In accordance with your request of 06 October 2009, I have reviewed the 01 October TR-
64 adequacy response submitted by.J.E. Stover & Associates on behalf of Bowie
Resources, LLC.
With the exception of Item No. 8 in my original geotechnical adequacy review, all of the
issues I raised have been satisfactorily addressed.
8. MLT: CMWDA-4 has been designed with the intention of first excavating native
soils in order to create an available area for placement of the coal mine waste.
The Buckhorn Geotech report dated February 1, 2007 evaluated overall
excavation slopes of 2.5H:1V and 2H:1V. These slopes resulted in acceptable
upper waste fill slopes of 2.5H:1 V and 3H:1 V, respectively (page 3, 5th
paragraph). The May 2009 Buckhorn Geotech report steepens the acceptable
excavation slope (assuming a 3:1 upper waste fill slope of 31-1: IV) from 2H: IV to
1.3H:1 V. Presumably it is this steepening of the acceptable excavation slope that
accounts for much of the potential increase in the volume of CMWDA-4. Section
D-D' of Volume IX Figure 1 illustrates the relative locations of the original
ground surface and the proposed ground surface. Missing from this Section is a
line showing the proposed excavation surface. Please modify Section D-D' to
represent the approximate limits of excavation that have preceded or are expected
to precede. the placement of coal mine waste in CMWDA-4.
BRL; The location of the existing Section D-D' was outside of the excavation
limits approved by TR-43, therefore, the section line was moved to the east in
order to cut a section that would show the proposed Gob surface in relation to the
excavation surface. The new sections are shown on Section D-D' on Figure 1.
Office of Office of
Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines