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April 19, 2013 <br />Mr. Eric Scott <br />Environmental Protection Specialist <br />Division of Reclamation, Mining and Safety <br />Department of Natural Resources <br />1313 Sherman St. Room 215 <br />Denver, Colorado 80203 <br />VISION OF <br />,IGIININGAND SAFES ON <br />Re: 17 Water Quality Trends at Climax Monitoring Well EVMW -1S, Eagle River Basin <br />Dear Mr. Scott; <br />Climax Molybdenum <br />A Freeport - McMoRan Company <br />This letter and attachments are to follow -up on our April 10, 2013 phone conversation when I notified you of <br />our recent observation of increasing trends of certain constituents in groundwater at monitoring well EVMW- <br />1S below the Robinson Lake Seep Pump Station. Following routine 1Q 2013 monitoring in accordance with <br />the Water Quality Monitoring Plan (WQMP), groundwater quality from monitoring well EVMW-1S shows <br />an apparent increase over time in several analytical parameters including dissolved iron, dissolved <br />manganese, sulfate, TDS, as well as dissolved calcium and dissolved magnesium. There were no apparent <br />increasing trends noted for any of the other WQMP parameters or in the adjacent deeper well (EVMW-1D). <br />The following information is attached to this letter: <br />Sent by Certified Mail <br />Climax Mine <br />Highway 91 - Fremont Pass <br />Climax, CO 80429 <br />Phone (719) 486 -7718 <br />e 1 '777- x19) 486 -2251 <br />RECEI vED <br />APR ?22013 <br />• Figure 3 from the WQMP showing relevant features and monitoring locations. <br />• Well logs for wells EVMW-1S, EVMW -1D and EVMW -4 located downgradient from the Robinson <br />Lake Seep Pump Station. <br />• A table of water quality data collected to date from wells EVMW-1S, EVMW -1D and EVMW -4 for <br />iron, manganese, sulfate, TDS, calcium, and magnesium. <br />• Graphs showing long -term monitoring data for the above constituents from EVMW (shallow well <br />replaced in 2011 by EVMW -1 S), and for EVMW -1 S and EVMW -1D for the period of record. <br />Upon discovery of the trends, Climax immediately increased the sampling frequency for wells EVMW-1S, <br />EVMW -1D and EVMW -4 to monthly. We intend to collect our first monthly sample the week of April 22, if <br />weather conditions allow. We also assembled a team of technical experts including a geochemist and <br />hydrogeologist from Tetra Tech to begin investigating groundwater conditions in the area to help identify the <br />potential cause of the trends. Tetra Tech has already begun this preliminary investigation, which includes the <br />following work to gain a better understanding of conditions that may be controlling the trends: <br />• Review all hydrogeological data associated with the area, including existing information on site <br />hydrogeology, drilling logs for EVMW-1S, EVMW -1D and EVMW -4, construction records of the <br />Robinson Lake Seep Pump Station and cut -off wall, and any other information from previous <br />subsurface investigations in the area. <br />• Review all chemical data associated with monitoring wells EVMW -1S, EVMW -1D, EVMW -4, <br />spring/surface water sampling locations above Eagle Park Reservoir, Robinson Lake, and Robinson <br />