2011-08-08_REVISION - M1977493 (36)

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• • Water Quality Monitoring Plan Climax Molybdenum Company Version: R1 Permit No. M- 1977 -493 basic groundwater standards and are listed in Tables 1 or 2 of the CBGS. Only secondary drinking water standards (Table 2) apply to copper, iron, manganese and zinc. Based on this comparison of groundwater standards to discharge limit parameters, consideration was given to the addition of arsenic, mercury, and selenium to the groundwater monitoring program. None of these parameters have been previously identified as parameters of concern and are not expected to be observed at significant concentrations in waters at the site. Within the sampling record for the 4 Dam Seep (seepage through 4 Dam at the base of Eagle Park Reservoir, which is collected and returned to Robinson Lake) each of these parameters were analyzed in 17 samples collected between 1998 and 2001. Arsenic and selenium were not detected in any of the samples and mercury was observed at a concentration above the detection limit of 0.0002 mg /I only once, at a concentration of 0.0011 mg /I. Therefore, based on these data it does not appear to be necessary to add these parameters to the groundwater monitoring program. The parameter list for ongoing POC groundwater monitoring includes the following: pH Total Dissolved Solids (TDS) Sulfate (SO Hardness Cadmium (Cd), dissolved Copper (Cu), dissolved Arsenic (As), dissolved Silver (Ag), dissolved Aluminum (Al) Cyanide (CN), free EPP — Appendix C Iron (Fe), dissolved Lead (Pb), dissolved Manganese (Mn), dissolved Molybdenum (Mo), dissolved Zinc (Zn), dissolved For the purposes of establishing baseline conditions and to allow an evaluation of appropriate longer -term monitoring parameters for the new POC monitoring well EVMW -3, analyses will be performed for several additional parameters during the baseline monitoring period, discussed in Section 5.1.1. The selection of baseline monitoring parameters has been developed with consideration given to groundwater standards, water quality in the 4 Dam seep and additional metals and inorganic parameters that may be indicative of mining - related activity. On this basis, the following additional parameters are proposed for analyses during the baseline monitoring period: Mercury (Hg), dissolved Selenium (Se), dissolved Total Nitrate + Nitrate as N Chromium (CrIII + CrVI), dissolved 4.1.2 Internal Monitoring Sites For the internal monitoring sites identified in this Plan, the analytical list has been developed using appropriate indicator parameters to enable detection of changes in water quality at these locations that could be due to upgradient mine facilities. These parameters were chosen based on knowledge of the chemistry of mine drainage at Climax, as increases in these constituent concentrations are likely to be detected first should impacts from mining - related activities occur. Internal monitoring sites include both surface water (flowing streams and canals) and groundwater (wells, springs, and seeps) sampling locations. Based on currently available data, the following parameters are proposed as appropriate indicator parameters for internal monitoring, following the baseline data collection period. pH Iron (Fe), dissolved August, 2011 12