1997-11-13_REVISION - M1977493 (50)

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Woodward-Clyde 1W Engineering&sciences applied to the earth&its environment 0 October 14, 1997 Mr. Bryce Romig Climax Molybdenum Company Climax Mine Climax, CO 80429 Subject: Geologic Evaluation, Southeast Reservoir Rim Sideslope, Eagle Park Dam, Climax Mine, Climax, Colorado Project No. 24435-3936 Dear Bryce: We have completed our geologic evaluation of the reservoir rim sideslope for Eagle Park Dam as outlined in our Proposal No. 24435-3936, dated July 25, 1997. This letter presents a brief project background, a current summary of our observations during a recent site reconnaissance, and our recommendations for monitoring the slope. • Project Background Eagle Park Dam also known as Climax Dam No. 4 is located in the Eagle Park drainage and is part of the surface water storage facilities at the Climax Mine. Climax Dam No. 4 was constructed in the early 1960s, and originally used to store oxide tailing. In the early 1990s, the oxide tailing was removed and the reservoir converted to fresh water storage. The reservoir area and sideslopes consist of near surface bedrock on both abutments with a deep alluvial valley foundation. Shallow, near surface landsliding has recently occurred on -the south valley wall near the extreme east(upstream) end of the current reservoir. The Colorado Division of Minerals and Geology (DMG)has requested that Climax have a professional review the stability of the slope in this area of the reservoir. Summary of Our Site Reconnaissance A geologic reconnaissance of the reservoir slope area was conducted on August 25, 1997. The reconnaissance consisted of a review of our files and published geologic maps of the area, and a half day of geologic mapping of the subject reservoir rim sideslope. Figure 1 presents a section of a regional geologic map containing the project area. Mapping was conducted on a sketch map of the reservoir slope drawn from a vantage point north of the reservoir. Measurements of rock discontinuities consisting of joints, bedding joints, and a shear were made at several locations and are summarized in Table 1. The discontinuity reference numbers are shown with other geologic information on the sketch map-on Figure 2. oodward-Clyde International(Formerly Woodward-Clyde Consultants)A subsidiary of Woodward-Clyde Group,Inc. Stanford Place 3,Suite 1000.4582 South Ulster Street•Denver,Colorado 80237-2637 +1-303-694-2770•Fax:+1-303-694-3946 24435-3836/LE2.Doc 7r23/97(1:e0 PM)tRPT