2000-09-13_REVISION - M1977493 (3)

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Petition for Partial Relei FFinancial Warranty Climax Molybdenum Company Permit #M-77 493 September 1, 1999 coarse-grained materials from a borrow site adjacent to the impoundment was the most effective and permanent remedy for the erosion problem. The Mayflower capping project began in 1988 and continued through the construction seasons of 1989 and 1990 when it was completed. Borrow material was extracted from the slope on the east side of the tailings impoundment, hauled to the coverage areas, and spread in a single 18" lift on the impoundment flats and to a 3' depth on the dam face. Approximately 300,000 cu. yds. of material was used to cap 124 acres (36 percent), of the 346-acre impoundment. Growth media was applied to an average depth of 18" over the rock cap. Growth media consisted of clean sandy loam material with an average 2.8 percent organics. Growth material was excavated from the adjacent borrow area. Biosolids were obtained from the Snake River Waste Water Treatment Plant (WWTP) in Summit County and were applied to the surface of the Mayflower cap as a growth media enhancement and substitute. Use of biosolids was permitted under the Biosolids Management Program of the Colorado Department of Public Health and Environment (CDPHE) (CDPHE BMP #0405). Biosolids incorporated into the Climax reclamation program meet Colorado's Grade I criteria with respect to metals and are applied at a rate of approximately 25 dry tons per acre. From 1990 into 1997, approximately 31 acres of the Mayflower tailings area were amended with biosolids with excellent results. Use of biosolids will continue into the future at various areas at Climax. Figure 1 delineates those areas on the Mayflower tailings impoundment which have been completed as well as the area of the remaining 218 acres. Figures 16 and 17 are photographs of the area prior to, during, and following reclamation work. Figures 18 through 20 show the area in 1992, 1996, and in July 1999. As discussed, the capping task is 36 percent complete and grading work on ancillary area C 19 is 100 percent complete. Therefore, Climax seeks a reduction in warranty for these elements of. $737,333• Geogrid installation, grading, and capping of the remain 218 acres of Mayflower remains to be done. Thus, that portion of the warranty remains unchanged. 3.5 Robinson Tailings Area The Robinson tailings impoundment encompasses 667 acres straddling the Continental Divide northwest of the mine and mill area. The Robinson impoundment was the first engineered tailings impoundment at Climax and was constructed in the mid-1930s. Prior to that, tailings were deposited, ad hoc, below the mill in the area now completely covered by the mine/mill yard and E-dump. The Robinson impoundment was active through the 1970s. Although this impoundment contained some additional storage area. Climax determined in the 1980s to decommission the area and designate the Ten Mile tailings impoundment as the primary tailings deposition site for the mine. As the water pool receded and the increasing beach areas and No. 1 Dam dried, wind-blown tailings became a regulatory issue causing Climax to initiate planning toward closure and reclamation of the area per the conditions of the amended (1989) permit. The permit requires that the Robinson impoundment flats be capped with rock material to a minimum 100419/Climax/Report.doc 8