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f COLORADO OPERATIONS <br />® Climax Molybdenum Henderson Mine and Mill <br />A Freeport- McMoRan Company P.O. Box 68 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 9291 <br />Mr. Peter Hays <br />MAY 0 5 2015 <br />Division of Reclamation Mining and Safety / Q D114SION OF RECLAMATION <br />1313 Sherman St., Rm. 215 /I I ►� MINING ANDWEfY <br />Denver, CO 80203 <br />RE: Climax Molybdenum Company, Henderson Mill, Permit No. M-197 -3 <br />Z A2,_ Proposed <br />Technical Revision No. 25, Ute Park Extraction Wellfield - Phase II <br />Dear Mr. Hays: <br />Climax Molybdenum Company (CMC) is submitting this request for a Technical Revision (TR -25) to the <br />Henderson Reclamation Permit for the Phase II 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 eventually be replaced by this new wellfield as it is <br />fully built -out over the next several years. The need for a new wellfield was identified during ongoing <br />hydrogeologic investigations and modeling which indicate that seepage impacted groundwater is <br />bypassing the existing extraction system and could migrate further downgradient toward point of <br />compliance wells MLGW -7 and MLGW -15. A site map depicting the area below 1 Dam and the existing <br />extraction and monitoring well network is included in Attachment 1, Figure 2. <br />As part of Phase II 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 2, Figure 1 & <br />2 /Attachment 3 — Pitless unit detail). Additionally, another nested pair of monitoring /observations wells <br />(MLGW -23 & 24) will be installed downgradient of 1 -Dam to continue Henderson's commitment to <br />groundwater monitoring and protection. Again, these monitoring wells will not be classified as an <br />environmental protection facilities, but will be used to monitor the effectiveness of the new extraction <br />wellfield. <br />The installation of the well in Phase I allowed for further characterization of the aquifer by providing <br />composition data, soil strata thickness, hydraulic conductivity and pumping capacity of the deposits. The <br />information gained during Phase 1 was, in general, anticipated by Henderson's hydrogeologists. This <br />information will be utilized to optimize the design and installation of the Phase II and Phase III extraction <br />wells, including well depth, casing diameter, pump settings and other design parameters. <br />Phase III will follow Phase II and will likely consist of the installation of two to three more extraction wells, <br />which will be designed taking into consideration information on aquifer characteristics from the Phase I <br />and II wells. <br />The Phase II wells will be drilled through the entire thickness of the aquifer system, which is estimated to <br />be approximately 60 -88 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 />✓loo vw:i rl.s <br />