2011-08-12_REVISION - M1990057

• Permit No: M1990057
• IBM Index Class Name: REVISION
• Doc Date: 8/12/2011
• Doc Name: MEMO- Slope Stability Analyses Review.
• From: DRMS- Tim Cazier
• To: DRMS- Michael Cunningham
• Type & Sequence: TR3
• Email Name: MAC
• Email Name: TC1
• 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]
Mined Land Reclamation
MEMORANDUM
Ti20 3
To: Michael Cunningham, Environmental Protection Specialist
From: Tim Cazier, P.E., Environmental Protection Specialist
Date: August 12, 2011
STATE OF COLORADO
Re: Slope Stability Analyses Review for the Union Mill Tailings Pond, Permit No.
M- 1990 -057
COLORADO
D I V I S I O N O F
RECLAMATION
MINING
— &—
SAFETY
John W. Hickenlooper
Governor
Mike King
Executive Director
Loretta Pineda
Director
The Division of Reclamation, Mining and Safety engineering staff (DRMS) have reviewed the
Slope Stability analyses dated July 8, 2011 and prepared by CTL Thompson for the Union
Milling Company, Leadville, Colorado. DRMS was informed by the applicant after the
aforementioned submittal that they intend to pursue permitting only phase 1 of the project at this
time. Therefore, no comments related to phases 2 or 3 are included in this review.
The review consisted of comparing the application content with specific requirements of Rule
6.5 of the Minerals Rules and Regulations of the Colorado Mined Land Reclamation Board for
Hard Rock, Metal, and Designated Mining Operations. Any inadequacies are identified below
along with suggested actions to correct them.
1. Page 1, second paragraph: The fourth line states "A clay liner with specified permeability of
1 x10 gal /day /ft will be installed on the interior face and floor." This specification is
equivalent to nearly 1 x10 cm/s and will likely be very difficult, if not impossible to
achieve. Please confirm this is the intended specification and how the applicant intends to
achieve it.
2. Page 3, first paragraph: The second to last sentence states "... we sampled the stockpile
created during the excavation for the tailings pond." Please clarify whether the sample(s)
taken from this stockpile were intended to characterize the material intended for the
construction of the embankment or the in situ natural soil underlying the embankment.
3. Page 5, first paragraph: The last sentence indicates groundwater was encountered at 25 feet
in boring TH -2. In contrast, the last paragraph on the first page of the "TAILINGS
DISPOSAL / Operating History" dated June 6, 2011 submitted to DRMS by the applicant,
indicates the aquifer is 80 to 100 feet below the surface based on communication with the
Office of Office of
Denver • Grand Junction • Durango Active and Inactive Mines