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® Climax Molybdenum <br />A Freeport- McMoRan Company <br />November 18, 2014 <br />Mr. Eric Scott, Environmental Protection Specialist <br />Division of Reclamation, Mining and Safety <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 <br />Climax Mine <br />Highway 91 - Fremont Pass <br />Climax, CO 80429 <br />Phone (719) 486 -7718 <br />Fax (719) 486 -2251 <br />/0 - I � -7-7- Lle7f <br />Re: Climax Mine, Robinson Seep Investigations — 2014 Results <br />Dear Mr. Scott; <br />The attached report provides the results of the work conducted in 2014 to further characterize groundwater <br />between Robinson Lake and Eagle Park Reservoir. The main objectives of the 2014 work were to evaluate <br />temporal changes in water quality downgradient of Robinson Lake since 2013, and to further delineate <br />seepage concentrations in shallow groundwater downgradient of the Robinson Lake seep collection system. <br />Additionally, the report provides an update to the current hydrogeochemical monitoring in the vicinity of <br />monitoring well EVMW -1 S based on the most recent data and interpretations from the increased monitoring <br />that began in April 2013. <br />A review of the last two years of data indicate that the previously observed increasing trends for primary <br />indicators sulfate and TDS have reversed, and overall decreasing trends has been observed since the summer <br />of 2013. Iron concentrations in EVMW -1 S also appear to have returned to within the upper limits of long- <br />term trends. These data suggest that the cause of the increasing trends observed in 2013 were likely from a <br />slug of poor quality water that was mobilized due to the filling of Robinson Lake when Climax resumed <br />operations in 2012. The plume of poor quality water has steadily been attenuating over time. An evaluation <br />of monthly data also indicates that no differences in trends or additional information were observed when <br />comparing monthly against quarterly sampling intervals. <br />Based on these findings we request that routine monitoring of the previously identified monthly sampling <br />locations be reduced in frequency back to routine quarterly sampling. We believe that, given the trends in <br />concentrations over time, quarterly monitoring can be conducted without risk to Eagle Park Reservoir. <br />Please feel free to contact me at 719- 486 -7584 if you have questions on the report. We will continue to <br />provide you and Eagle River Water & Sanitation District with monitoring data and will notify you in <br />accordance with the Water Quality Monitoring Plan if any increasing trends are observed again. <br />Sincerely, <br />Raymond Lazuk <br />Environmental Manager <br />attachment <br />Linn Brooks, ERWSD <br />