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A- <br />Climax Molybdenum <br />A Freeport-McMoRan Company <br />COLORADO OPERATIONS <br />Henderson Mill <br />P.O. Box 68 <br />Empire, CO 80438 <br />Phone (303) 569-3221 <br />Fax (303) 569-2830 <br />September 7, 2010 <br />UPS Tracking #: 1Z8048470266704289 <br />!'?°? <br />Mr. Allen C. Sorenson <br />Division of Reclamation, Mining and Safety z/ <br />1313 Sherman St., Rm. 215 <br />Denver, CO 80203 <br />Re: Permit M-1977-342, Addition to Tailing Dam No. 3 Seep Collection System, <br />Addition to Environmental Protection Facilities, Technical Revision TR-09, Henderson <br />Mill <br />Dear Mr. Sorenson: <br />L__- <br />Climax Molybdenum Company intends to install an addition to the existing Tailing Dam No. 3 <br />Seep Collection System at the Henderson Mill. The addition would not change the existing <br />system but would complement it and capture several small seeps not currently being addressed. <br />Tailing Dam No. 3 is the smaller, south impoundment at the Henderson tailing facilities. When <br />it was commissioned in 1976 seepage from the dam was intercepted and pumped into the main <br />tailing water pool. The original pump system was replaced in 2000 by a series of earthen <br />diversion structures and the gravity-flow No. 3 Dam Seep Water Pipeline (A.K.A. Dam No. 3 <br />Seep Collection System). This Environmental Protection Facility increased the effectiveness and <br />reliability of collection, (see TR-09). <br />One subsurface seepage pathway at the extreme south end of the dam was not identified nor <br />dully intercepted by the diversion structures. The seepage emanating from that pathway flows at <br />only about 5 gallons per minute, but contains concentrations of iron and manganese and is acidic <br />with a pH of less than 4.0 s.u. <br />The attached, No. 3 Dam Seepage Mitigation Design Report, characterizes the seep area and <br />provides a design for capturing the seep water. The seep water will be routed to the existing No. <br />3 Dam Seep Water Pipeline.