2014-01-07_REVISION - C1996083

• Permit No: C1996083
• IBM Index Class Name: Revision
• Doc Date: 1/7/2014
• Doc Name: Preliminary Adequacy Review - Geotechnical
• From: Marcia Talvitie
• To: Susan Burgmaier
• Type & Sequence: TR84
• Email Name: SLB
• Email Name: MLT
• Email Name: SB1
• 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 COL ®EL A D
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Phone. [phone] RECLAMATION
FAX: [phone] INTEROFFICE MEMORANDUM MINING
SAFETY
Date: 07 January 2014 John W. Hickenlooper
Governor
To: Susan L. Burgmaier, Lead Specialist Mike King
Executive Director
From: Marcia L. Talvitie, P.E. Loretta E. Pineda
Director
Subject: Bowie No. 2 Mine — Permit No. C -1996 -083
TR -84 — Reconfigure Coal Mine Waste Disposal Area No. 3 (Gob Pile #3)
Preliminary Adequacy Review -- Engineering and Geotechnical
As requested in your Email of 19- Dec -2013, I have conducted a review of the TR -84 application
package. The application was submitted by I. E. Stover and Associates (Stover) on behalf of the
operator, Bowie Resources, LLC (BRL). TR -84 proposes to increase the capacity of Coal Mine
Waste Disposal Area No. 3 ( CMWDA 43) by steepening the slopes of the pile to 2.5h:1v (the
permit approves currently slopes of 3h:Iv).
History of Coal Mine Waste Disposal Area No. 3
To accomplish my adequacy review of TR -84, I first revisited the permitting history of CMWDA
#3 and the sequence of design decisions that have been made. Volume XI of the Bowie No. 2
Mine permit is dedicated to this facility. A summary of the relevant history is provided below,
for reference.
TR -45 (Jul - 21107): Development of CMWDA 43 was first permitted under TR -45, for which the
Division conducted a thorough review of the application for adequacy with respect to the rules
governing disposal of coal mine waste. Both general and detailed design plans were provided, as
required by Rule 2.05.3(8). Relevant sections of 4.09.1, 4.09.2 and 4.10 were also addressed to
the Division's satisfaction.
Analysis of the geotechnical aspects of the facility was addressed in a 29- Mar -2007 report
prepared by Buckhorn Geotech. This Stability Evaluation of the proposed refuse pile was
incorporated into Volume XI as Appendix A. Buckhorn determined, based on subsurface
drilling results and material test properties for coal mine waste (CMW) stored at CMWDA #2,
that various pile geometries would result in a factor of safety (FOS) of at least 1.50. The
approved design had 3h :lv slopes on the north and south, with one 15' -wide terrace. The
maximum proposed height of the pile was 65 feet, resulting in an available volume of
approximately 650,000 cubic yards. CMWDA #3, coverfill, and topsoil storage locations were
depicted on Figure 1 of Volume XI. As shown in Section D -D' of the approved map, the
designed pile was to measure 570' from North to South. The top surface of the pile, 270' in
width, southward with a gradient of 1.5 %.
office of Office of
Mined Land Reclamation Denver • Grand )unction • Durango Active and Inactive Mines