2014-02-13_REVISION - M1977493

• Permit No: M1977493
• IBM Index Class Name: REVISION
• Doc Date: 2/13/2014
• Doc Name: Adequacy review of technical revision TR23
• From: DRMS
• To: Climax Mine
• Type & Sequence: TR23
• Email Name: ECS
• Media Type: D
• Archive: No

DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
February 13, 2014
Climax Mine
Attn: Mr. Ray Lazuk
Highway 91
Climax, CO 80429
STATE OF COLORADO
COLORADO
D IV IS I ON OF
RECLAMATION
MINING
SAFETY
John W Hickenlooper
Governor
Mike King
Executive Director
Loretta Pineda
Director
RE: File M 1977 -493; Climax Mine; Adequacy Review of Technical Revision 23 (TR23) — Mayflower TSF
Design, Stability and Operations and Monitoring Plan, and Modifications to the Tenmile TSF Operations
and Monitoring Manual
Mr. Lazuk:
The Division of Reclamation, Mining and Safety received Technical Revision 23 — Mayflower TSF Design,
Stability and Operations and Monitoring Plan, and Modifications to the Tenmile TSF Operations and Monitoring
Manual on October 15, 2013. Due to the scope and complexity of this proposed revision, Climax has waived the
DRMS 30 day review period for this revision in order to allow for appropriate review and comment. Also due to
scope of this revision, DRMS has worked cooperatively with the Colorado Division of Water Resources, Office
of the State Engineer - Dam Safety Branch (DSB) in order to provide a more thorough review of this submittal.
DRMS appreciates the DSB input provided for the review of this revision.
DRMS /DSB has completed the initial adequacy review of TR23. As with most revisions of this scope and
complexity, there are a several items that will require clarification of the existing information or submittal of
additional information. These items have been presented below and referenced to the documents submitted to
DRMS. DRMS /DSB would also be willing to meet with Climax to discuss these comments if further clarification
or discussion is needed.
DRMS anticipates that as mining continues at this site that development of TSFs will evolve based on the
implementation of additional items and best practices, the collection of additional data, field conditions, and
ongoing discussions between DRMS and Climax.
Monitoring /extension of existing sub -drain piping
Section 1, Page 1 -2 of the seepage and stability analysis (SSA) describes the existing dam drainage system,
including sub - drains of eight and twelve inch CMP in sand and gravel bedding. These drains are constantly
exposed to low pH drainage, and failure of these CMP drains due to corrosion and/or collapse could result in
significant issues that could jeopardize the stability of the dam. Therefore, DRMS would like Climax to commit
to annual video inspections of the CMP subdrains, if possible. What does Climax intend to do if any of the CMP
drains show signs of degradation or failure?
Section 3.1 of the Operations and Maintenance Manual for the Mayflower TSF (OMM) states that the sub -drain
system will be extended as the dam is raised, and that a design will be prepared when extension activities are
required. Due to the upstream raise deposition of the dam, it is unclear why this extension would be required.
Figure 6 -1 in the SSA does not depict a change in the toe of the dam or any extension of the drain system during
the "life of mine" raise. Please clarify why extension of the subdrain system is needed. If extension of the
subdrain is required, Climax will be required to provide an engineering design to DRMS for review and approval
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Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines