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COLORADO OPERATIONS <br /> ® Climax Molybdenum Henderson Mine and Mill <br /> Freeport-McMoRan Company P.O. sox 68 <br /> A Free <br /> P A Y Empire, CO 80438 <br /> Phone(303)569-3221 <br /> TR28 Fax(303)569-2830 <br /> ✓ Complied <br /> June 8, 2017 ✓O Violations: RECEIVED <br /> PSH-WHE <br /> JUN 12 2017 <br /> Sent Via Email and Certified Mail#7016 2070 0000 4713 5256 <br /> DIVISION OF RECLAMATION <br /> MINING&SAFETY <br /> Mr. Peter Hays <br /> Division of Reclamation Mining and Safety <br /> 1313 Sherman St., Rm. 215 <br /> Denver, CO 80203 <br /> RE: Climax Molybdenum Company, Henderson Mill, Permit No. M-1977-342, Proposed <br /> Technical Revision No. 28, Ute Park Extraction Wellfield - Phase III <br /> Dear Mr. Hays: <br /> Climax Molybdenum Company (CMC) is submitting this request for a Technical Revision (TR-28) to the <br /> Henderson Reclamation Permit for the Phase III continued construction of the upgrade to the Ute Park <br /> Extraction Wellfield, downgradient of the Henderson Mill Tailing Storage Facility (TSF) 1 Dam. The <br /> existing extraction wellfield permitted under TR-10 will be replaced by this new wellfield as it is completed. <br /> The need for a new wellfield was identified during ongoing hydrogeologic investigations and modeling <br /> which indicate that seepage impacted groundwater is bypassing the existing extraction system and could <br /> migrate further downgradient toward point of compliance wells MLGW-7 and MLGW-15. A site map <br /> depicting the area below 1 Dam and the existing extraction and monitoring well network is included in <br /> Attachment 1, Figure 1. <br /> As part of Phase III of this project, Henderson plans to install two additional extraction wells and their <br /> appurtenant infrastructure (electrical, piping and instrumentation). These wells will be drilled and installed <br /> along the original transect delineated in the Phase I (TR-23) submittal (See Attachment 1, Figure 2 & <br /> Attachment 3— Pitless unit detail). Additionally, a monitoring/observation well (MLGW-26) will be installed <br /> downgradient of 1-Dam to continue Henderson's commitment to groundwater monitoring and protection. <br /> This monitoring well will not be classified as an environmental protection facility, but will be used to <br /> monitor the effectiveness of the extraction wellfield. <br /> The installation of the wells in Phase I and II allowed for further characterization of the aquifer by <br /> providing composition data, soil strata thickness, hydraulic conductivity and pumping capacity of the <br /> deposits. In addition, a geophysical study was completed in 2016 to further characterize the aquifer. The <br /> information gained during Phase I and Il, in general, was anticipated by Henderson's hydrogeologists. <br /> This information will be utilized to optimize the design and installation of the Phase III extraction wells, <br /> including well depth, casing diameter, pump settings and other design parameters. <br /> The Phase III wells will be drilled through the entire thickness of the aquifer system, which is estimated to <br /> be approximately 90 feet deep. The extraction well is designed to optimize flow from the aquifer and <br /> includes an 8-inch stainless steel blank casing and wire-wrap well screen. A 4-inch downhole pump will <br /> convey water via a 2-inch drop pipe and pitless adapter to a manhole where the pump line will connect to <br /> a 6-inch high-density polyethylene (HDPE) header pipeline that leads to the seepage collection system. <br /> As with the first well installation, instrumentation for the system includes a down-well transducer and float <br /> switches to monitor and maintain water levels, a flow meter located in the manhole, a data logger and a <br />