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2.2 Corrective Action Monitoring Groundwater samples were collected by Bryan A. Stirrat&Associates from the corrective action monitoring wells (AMW-1,AMW-4,AMW-10,AMW-11,AMWO-19)during the second quarter 2006 monitoring event. Bryan A. Stirrat reported that corrective action monitoring well MW-3 has been destroyed, and that corrective action monitoring well MW-5 could not be sampled during the third quarter 2006 due to a nonfunctional pump lodged in the well. The field and laboratory results provided by BC Laboratories, Inc. for the third quarter 2006 corrective action sampling are summarized on Table 2.3. VOCs have been consistently detected in samples from corrective action monitoring wells AMW- 1, AMW-4,AMW-10, and AMW-11. AMW-5 and AMW-19 have previously exhibited sporadic VOC detections. No VOCs have been detected in samples from AMW-3 since 1990. The historical groundwater data for the corrective action monitoring wells are presented in Appendix F. The data are graphed on time series concentration plots, included in Appendix G. For VOCs,only those VOCs that exhibited detections for the third quarter 2006 monitoring event were plotted. Historical data from the corrective action monitoring wells from March 1994 to the present were analyzed for temporal trend using Sen's Slope trend analysis. Graphs of the Sen's Slope analyses for corrective action monitoring wells are included in Appendix G. Table 2.4 summarizes the results of the corrective action monitoring well trend analysis. The following inorganic constituents exhibited an increasing trend according to the Sen's Slope analysis: barium at AMW- 1, bicarbonate at AMW-1, chloride at AMW-3 and AMW-5, nitrate at AMW-3 and AMW-5, field pH at AMW-5, field specific conductance at AMW-1, AMW-3, AMW-5, and AMW-10, strontium at AMW-19, sulfate at AMW-5 and AMW-10, and total dissolved solids (TDS) at AMW-5 and AMW-19. The third quarter 2006 concentration of barium at AMW-1 (0.31 mg/L) is comparable to concentrations observed at that well intermittently since May 2004, and is well below the National Primary Drinking Water Standards (2 mg/L). The third quarter 2006 concentration of bicarbonate at AMW-1 (820 mg/L) is comparable to concentrations observed at that well intermittently since February 2004. The second quarter 2006 concentration of chloride at AMW- 3 (92 mg/L) is comparable to concentrations observed at that well consistently since August 2003. The second quarter 2006 concentration of chloride at AMW-5 (99 mg/L) is comparable to concentrations observed at that well consistently since July 2001. The chloride concentration at both AMW-3 and AMW-5 is well below the National Secondary Drinking Water Standard (250 mg/L). The second quarter 2006 concentration of nitrate at AMW-3 (15 mg/L) is comparable to concentrations observed at that well consistently since August 2003. The second quarter 2006 concentration of nitrate at AMW-5 (13 mg/L) is comparable to concentrations observed at that well consistently since July 2001. The concentration of nitrate at both AMW-5 and AMW-10 during the second quarter 2006 is below the concentration observed in background well AMW-2 during the third quarter 2006(32 mg/L). The field pH value observed at AMW-5 during the second quarter 2006 (7.2) is comparable to values observed at that well since August 1991, and is within the National Secondary Drinking Water Standard range (6.5-8.5). The third quarter 2006 field specific conductance value at AMW-1 (1,300 umhos/cm) is comparable to values observed at that well consistently since March 2003. The second quarter 2006 field specific conductance value at AMW-3 (1,700 4