2014-01-09_REVISION - C1996083

• Permit No: C1996083
• IBM Index Class Name: Revision
• Doc Date: 1/9/2014
• Doc Name: Adequacy Review - Geotechnical
• From: Marcia Talvitie
• To: Susan Burgmaier
• Type & Sequence: TR85
• 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 80243
Phone: [phone]
FAX: [phone] INTEROFFICE MEMORANDUM
Date: qR January 2014
To: Susan L. Burgmaier, Lead Specialist
From: Marcia L. Talvitie, P.E. `'�j1`4P
Subject: Bowie No. 2 Mine — Permit No. C -1996 -083
TR -85 — CMWDA #2 Drying Area
Preliminary Adequacy Review — Geotechnical
COLORADO
D IV IS ION OF
RECLAMATION
MINING
SAFETY
John W. Hickenlooper
Governor
Mike King
Executive Director
Loretta E. Piftda
Director
As requested in your Email of 30- Dec -2013, I have conducted a review of the TR -85 application
package. The application was submitted by J. E. Stover and Associates (Stover) on behalf of the
operator, Bowie Resources, LLC (BRL). TR -85 proposes to designate an area for seasonal
storage of end - dumped coal mine waste (CMW) atop Coal Mine Waste Disposal Area No. 2
(CMWDA #2). The purpose for this seasonal storage (limited to 2013/2014) is to allow the
CMW, which has a high moisture content once it leaves the coal preparation plant, to dry (drain)
somewhat, prior to its being permanently placed and compacted according to the approved plan.
The Volume IX materials submitted by Stover for the Division's review included revised pages
12 through 19 of the text and a new Stability Analysis prepared by Buckhorn Geotech
(Buckhorn), dated December 5, 2013. For my review, in addition to the requirements of 4.09
and 4.10, 1 considered information found in the Q3 -2013 Waste Pile Report and in previous
Buckhorn stability analyses developed for CMWDA #2.
The configuration of the proposed Drying Area generally reflect the points covered in a
preliminary discussion held between Tamme Stover - Bishop (Stover), Dan Quigley (Buckhorn),
and me on 22- Nov -2013.
Adequacy Comments
The second bullet of Buckhom's Assumptions section reads, "No phreatic surface was
modeled in either the gob or native material which is consistent with our analyses of pile
#2 to date." The Division's review of Buckhorn's earlier CMWDA #2 analyses found
that the 22- Sep -2008 study did consider a phreatic surface based on pore pressure
measurements and also conducted a sensitivity analysis using an increased phreatic
surface. In that study, block failure as well as circular failure was considered.
Buckhorn's Summary of Instrumentation Monitoring for the 3rd Quarter 2013 includes
data for a series of Vibrating Wire Piezometers (VWPs) that have been installed in
Office of Office of
Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines