2010-03-25_REVISION - C1981010 ‎(3)‎

• Permit No: C1981010
• IBM Index Class Name: REVISION
• Doc Date: 3/25/2010
• Doc Name: Adequacy Review ‎(Memo)‎
• From: MarciaTalvitie
• To: Jason Musick
• Type & Sequence: TR106
• Email Name: JDM
• Email Name: MLT
• 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]
INTEROFFICE MEMORANDUM
Date: 25 March 2010
To: Jason Musick, Lead Specialist
From: Marcia L. Talvitie, P.E.°
Subject: Trapper Mine - Permit No. C-1981-010
TR-106 - Revision to Mining Sequence in K -Pit
Adequacy Review - Geotechnical
COLORADO
D I V1 S I ON OF
RECLAMATION
MINING
SAFETY
Bill Ritter, Jr.
Governor
Harris D. Sherman
Executive Director
Ronald W. Cattany
Division Director
Natural Resource Trustee
As requested, I have reviewed the TR-106 application, submitted by TMI, for adequacy with
respect to geotechnical. issues. The application consists of several revised pages to the permit
and a new report prepared by Agapito Associates, Inc. (AAI), "Revised K-Pit Buttress Fill
Stability Analysis and Recommendations" dated February 2010.
AAI has continued to re-evaluate the stability of and the need for the proposed K-Pit buttress as
additional information about the K-Pit has become available. AAI and TMI are to be
commended for the on-going attention to this topic. With the current analysis, AAI concludes
that the height of the K-Pit buttress should be no greater than 50 feet. The change is due to the
discovery of potential weak zones in the I-Seam strata and the realization that the buttress will
not be required to maintain long-term stability of the reclaimed K-Pit. New recommendations
have been presented addressing the revised buttress design and the mining plan for K-Pit.
I have only one comment regarding TR-106:
1) The current AAI analysis makes several specific recommendations regarding K-Pit Mining
and the K-Pit Buttress, summarized beginning on Page 7 with Section 4.0. The revised
permit pages submitted with TR-106 do address the proposed change in height of the
buttress, but do not make mention of the other recommendations made by AAI.
Please clarify, in the revised pages of the permit, whether it is indeed TMI's intent to
comply with the recommendations made in the current AAI report. Specifically:
a) For K-Pit Mining, does TMI plan to reduce the gradients of slopes (by excavating
material) in K-Pit which are currently steeper than 1819 Will haul roads be designed with
maximum cut and fill slopes of 3H:1 V when located in or above the I-Seam??
b) AAI seems to indicate (Page 8) that in lieu of placing spoils in the K-Pit Buttress, they
may be used in reclamation of the AE Pit. Revised permit pages submitted with TR-106 do
..not mention this possibility. Please clarify the list of proposed locations for placement of
excess spoil from the K-Pit.
This concludes my adequacy review for TR-106. Please don't hesitate to call if you have any
questions.
Office of
office of
Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines