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5.0 MONITORING SCHEDULE, DATA ANALYSIS AND REPORTING <br />• 5.1 POC Groundwater Monitoring Sites <br />5.1.1 Monitoring Schedule <br />• <br />• <br />Water Quality Monitoring Plan Climax Molybdenum Company <br />Version: R1 Permit No. M -1977 -493 <br />The POC monitoring sites in the Arkansas and Tenmile Watersheds have been sampled for <br />years, and baseline sampling is not necessary. These two POC wells, ARwell and GWM -2, will <br />continue to be sampled quarterly, weather and access conditions permitting. To be consistent <br />with the sampling schedule employed over that last several years, sampling will typically be <br />performed in March, June, September, and December. In reviewing the existing analytical data <br />for these wells, where seasonal variation in analytical results is observed, the lowest <br />concentrations are typically observed in the spring and summer sampling periods. <br />The new POC site in the Eagle River basin will be established during the 2011 field season and <br />will be monitored quarterly, weather and access conditions permitting, to establish baseline <br />conditions for a period of 2 to 2 ' years, to provide a minimum of 5 samples for baseline <br />characterization, as discussed in Section 4.2.2. <br />5.1.2 Data Analysis <br />The data evaluation for the POC wells involves a comparison against NPLs, as provided in <br />Tables 4 -1 and 4 -3, for the Arkansas and Tenmile Creek Watersheds. For the Eagle River <br />Watershed well (EVMW -3), NPLs will be established after the baseline sampling is complete. <br />Climax will review the monitoring results from POC sites after analytical results are received. <br />The review will include a comparison to the NPLs and a trend analysis that compares the most <br />recent water quality data with data collected over the period of record. Statistical testing will be <br />performed to test whether the data are normally distributed. In the event the data for the <br />parameter being evaluated are not normally distributed, which is most likely at low <br />concentrations, Climax assumes the data are log- normally distributed. The method to be used <br />for comparison against the NPL will depend on whether or not the data are normally distributed. <br />Where the NPL is based on table values from the CBSG, data from the recent sampling events <br />for a well will be used to calculate the standard deviation for the parameter for each POC well. <br />This approach is appropriate to consider the statistical characteristics of recent data against the <br />table value NPL, which is not based on the current data population. This statistical test is <br />intended to determine whether an individual future result that may exceed the NPL represents a <br />statistically significant exceedance of the NPL, considering the mean and standard deviation of <br />the data population of which the recent data is a part of. Where the NPL is based on ambient <br />water quality the statistical test will utilize data from a fixed baseline data set (also used to <br />calculate the NPL), which will then also provide an appropriate statistical test of significance <br />against the evaluation criterion, which in this case would represent the 95 percentile upper <br />prediction limit. <br />If the data are normally distributed, the evaluation criterion will be calculated with the following <br />equation: <br />1 <br />Evaluation Criteron = NPL + On — 1,1 — a]s 1 + — <br />n <br />EPP — Appendix C August, 2011 17 <br />