2012-11-19_PERMIT FILE - M1977493

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November 16, 2012 Climax Molybdenum A Freeport - McMoRan Company Mr. Eric Jacobs Colorado Department of Public Health and Environment Hazardous Materials and Waste Management Division HMWMD -HS -B2 4300 Cherry Creek Drive South Denver, Colorado 80246 -1530 RE: Climax Mine Crusher Adit Vent Raise Asbestos Disposal Shaft Closure Plan Climax Mine Highway 91 - Fremont Pass Climax, CO 80429 Phone (719) 486 -7718 Fax (719) 486 -2251 R ECEIVED NOV 19 2012 Division of Recian on Mining & $ , afety Dear Mr. Jacobs, As I had previously indicated in my letter to the Hazardous Materials and Waste Management Division (HMWMD) dated April 5, 2011, Climax Molybdenum Company — Climax Mine intends to permanently close the Crusher Adit Vent Raise (CAVR) shaft. The CAVR Shaft is a former ventilation shaft that had been converted for use as an asbestos disposal shaft. The shaft was constructed and configured per the design plan submitted to the CDPHE -HMWMD on July 7, 1988. As we have discussed, this shaft is no longer needed for asbestos disposal and will be permanently closed. The proposed closure plan varies in some aspects from the original closure concept included as part of the 1988 design plan submittal. The original plan envisioned backfilling the shaft with fill material and placing a clay cap at the surface. Because much of the shaft remains open and there is a possibility that overburden fill (from open pit mining activities) may be placed in the vicinity of the shaft, Climax is proposing an alternate closure plan for the shaft. The enclosed Technical Memorandum, prepared by Tetra Tech, Inc., presents the plan for the physical closure of the shaft and includes several construction drawings detailing the concrete shaft cap. As described in the enclosed documents, we propose to seal the shaft with a concrete plug that will be anchored into the existing collar of the shaft to minimize the potential for surface water to enter the shaft and create an air flow barrier. Compliance with applicable Division of Mining, Reclamation, and Safety guidelines are also addressed in the plan. As part of the closure we propose to decontaminate and demolish the HEPA - filtered exhaust system, the bag disposal chute, and the inner wood containment structure that provided the particulate control over the shaft. The enclosed Asbestos Decontamination Work Plan, prepared by Koch Environmental Health, Inc., presents the details of decontamination activities to prepare the area for building demolition and shaft cap construction. Climax will provide notification to the CDPHE Air Pollution Control Division as part of the asbestos abatement permitting process.