2011-08-08_REVISION - M1977493 (36)

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• • • Water Quality Monitoring Plan Climax Molybdenum Company Version: R1 Permit No, M -1977 -493 Total Dissolved Solids (TDS) Manganese (Mn), dissolved Sulfate (SO Molybdenum (Mo), dissolved For the purposes of establishing baseline conditions and to confirm the selection of the indicator monitoring parameters for the new internal monitoring locations, analyses will be performed for several additional parameters during the baseline monitoring period, discussed in Section 5.2.2. The selection of baseline monitoring parameters has been developed with consideration given to surface water and groundwater standards, 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 of groundwater samples during the baseline monitoring period: Arsenic (As), dissolved Silver (Ag), dissolved Aluminum (Al) Cadmium (Cd), dissolved Chromium (CrIII + CrVI), dissolved Lead (Pb), dissolved Surface water samples collected during the analyzed for the following: Hardness Mercury (Hg), total (in lieu of dissolved) EPP — Appendix C Mercury (Hg), dissolved Selenium (Se), dissolved Total Nitrate + Nitrate as N Cyanide (CN), free Copper (Cu), dissolved Zinc (Zn), dissolved initial baseline monitoring period will also be Ammonia (NH as N At the end of the baseline monitoring period, Climax will review the baseline data to verify the adequacy of the indicator parameter list for early detection of potential impacts of mining - related activity. If appropriate, additional indicator parameters will be added to the indicator parameter monitoring list. 4.2 Numeric Protection Levels Consistent with DRMS rules, Numeric Protection Levels (NPLs) will be established for POC groundwater wells using the CBSG as a guide with consideration given to baseline data, where available. In instances where the existing groundwater quality exceeds a CBSG table value, an alternate NPL is selected to protect against the further lowering of groundwater quality. Where ambient data are to be used to establish protection limits, the mean concentration from a minimum of the first five quarterly sampling results generated subsequent to January 31, 1994 will be used to establish baseline conditions, consistent with HRMMR 6.4.21(9)(b) and CBSG 41.5(C)(6)(b)(i). The NPLs are discussed below for each of the watersheds. Due to variability in analytical results caused by sampling and analytical variations, and by unquantified natural variability, normal practice is to quantify the combined variability in sampling results, and use that variability to determine when a statistically significant exceedance between a sampling result and an established criterion occurs. The data analysis approach to be used in evaluating data against the NPLs is described in Section 5. 4.2.1 Arkansas River Watershed The POC for the Arkansas River Watershed is ARwell, a monitoring well that is located downgradient from the surface water intake well for the raw and domestic water supply for the Site. August, 2011 13