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COLORADO OPERATIONS <br />Climax Molybdenum Henderson Mine and Mill <br />P.O. Box 68 <br />A Freeport- McMoRan Company Empire, CO 80438 <br />Phone (303) 569 -3221 <br />Fax (303) 569 -2830 <br />April 29, 2015 <br />Sent Via Email and Certified Mail #: 7006 2150 0001 8832 9413 <br />MAY 05 20 <br />Mr. Peter Hays <br />Division of Reclamation Mining and Safety DIVISION OF RECLAMATION <br />1313 Sherman St., Rm. 215 ''l � MINING AND SAFETY <br />Denver, CO 80203 ! 4 <br />RE: Climax Molybdenum Company, Henderson Mill, Permit No. M- 1977 -342, Proposed <br />Technical Revision No. 26, Tailing Storage Facility Liner System <br />Dear Mr. Hays: <br />Climax Molybdenum Company (CIVIC) is submitting this request for a Technical Revision (TR -26) to the <br />Henderson Reclamation Permit for the installation of a liner system overlaying higher permeability strata <br />on the northern side of the tailing storage facility (TSF). <br />CMC has identified isolated higher permeability sandstone and siltstone layers north of 1 -Dam within the <br />Troublesome formation (Figure 1), which primarily consists of low permeability claystone. Geologic <br />investigations indicate these formations extend into the TSF area above the current tailing level, but <br />below the ultimate anticipated height of tailing deposition. This formation provides a possible conduit for <br />tailing and process impacted water to escape the impoundment if not mitigated prior to tailing levels <br />reaching its elevation. <br />The Henderson Mill stores tailing and process water within the TSF, located north -west of the main Mill <br />complex. This facility is an unlined containment area bounded by natural topography and two earthen <br />dams (1 -Dam and 3 -Dam). The remainder of the TSF is confined by impermeable claystone of the <br />Troublesome Formation, except for an isolated sand seam on the northern side of the TSF. <br />Figure 1 - Site Overview <br />✓ 4f'r -� <br />V N0 Vfr la- `on S <br />