2011-03-14_REVISION - M1977493 ‎(54)‎

• Permit No: M1977493
• IBM Index Class Name: REVISION
• Doc Date: 3/14/2011
• Doc Name: Exhibit List, Ex. 67
• From: Climax
• To: MLRB
• Type & Sequence: AM6
• Media Type: m
• Archive: No

t. CMC001610
G.
— - - -
Environmental
January 30, 1996
Mr. Stuart Teuscher
Climax Mine
Highway 91
Climax, Colorado 80429
Recommended Modifications
Robinson Lake Cut-off Wall
Dear Stuart:
Titan Environmental Cowadon
7939 E. Arapahoe Rd., suite 230
Englewood, Coiorado 80112
Phone:[phone]
Fax: [phone]
5101 -004
This letter provides a recommended modification to the concrete cut-off wall designed for
the Robinson Lake Pump Back System. The original cut -off wall design called for a 24-
inch deep minimum cut -off wall key to be excavated into the bedrock as a means to
intercept any potential seepage within the bedrock. The cut -off wall would then be
constructed as a single wall starting within the keyway. In the original design, no
provisions were made to address conditions where the key could not be trenched.
If, during excavation of the cut -off wall key, the bedrock strength precludes advancement
of the keyway, a modification to the design is recommended to provide a watertight seal
against the bedrock. It is recommended that a 24 -inch concrete wall footing foundation
be constructed on the surface of the bedrock prior to forming the cut-off wall. The
purpose of the footing is to provide a large surface area seal onto the bedrock face, thus
minimizing any potential seepage between the cut-off wall and bedrock. The footing will
be constructed in the following steps:
• The bedrock will be visually inspected to ensure the rock face is competent
and free of any transmissive fractures or joints. The condition of the bedrock
prior to footing construction will be documented;
• The bedrock surface shall be cleaned to be free of soil, loose rock, or other
foreign materials or substances to promote adhesion of the footing to the
bedrock surface;
C
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A - V.tOD WC