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Status Report; Robinson Seep Investigation <br />1.2 Monitoring Program <br />Climax Molybdenum Company <br />In response to the observed increasing constituent trends at EVMW -1S, Climax immediately <br />notified the DRMS and ERWSD and increased the sampling frequency for wells EVMW -1 S, <br />EVMW -1 D, and EVMW -004 to monthly. Climax also began collecting monthly samples from <br />Robinson Lake and the Robinson Lake Seep in April 2013. Tabular summaries of monitoring <br />data from established locations in the Eagle River watershed are included as Appendix A. This <br />enhanced monitoring data along with a review of historical data, available site hydrogeology <br />information, construction records, Robinson Lake operational data, and the results of additional <br />field investigations were evaluated to develop a conceptual hydrogeochemical model of site <br />conditions. <br />Field investigations, consisting of the following phases, were undertaken to evaluate the spatial <br />extent of impacted groundwater and potential groundwater flow paths between Robinson Lake <br />and the Robinson Lake Seep collection system: <br />• Site reconnaissance to identify potential geological controls for impacted water transport <br />and to collect samples of surface water downgradient of Robinson Lake; and <br />• Drilling investigations in August and September, 2013 to delineate impacted <br />groundwater by means of field screening and water sampling. <br />Section 2.0 presents a summary of the data collected from enhanced monitoring activities in the <br />vicinity of Robinson Lake and Section 3.0 discusses the results of additional field investigations. <br />Conclusions and recommendations are presented in Section 4.0. <br />Tetra Tech, Inc November 2013 <br />