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Primary Drinking Water Standard (5 ug/L). The first quarter 2010 concentration of trichloroethene at AMW-13 (4.6 ug/L) is comparable to historical concentrations observed at that well,and is below the National Primary Drinking Water Standard(5 ug/L). Historical data from the detection monitoring wells were analyzed for temporal trends using Mann-Kendall / Sen's Slope trend analysis. Graphs and summary tables of the Mann-Kendall / Sen's Slope analyses for detection monitoring wells are presented in Appendix E. The following inorganic constituents exhibited an increasing trend according to the Mann-Kendall/ Sen's Slope analysis: barium at AMW-6 and AMW-14, bicarbonate alkalinity at AMW-2, AMW-6, AMW-7, and AMW-13, calcium at AMW-7 and AMW-14, chloride at AMW-6 and AMW-7, hexavalent chromium at AMW-14, magnesium at AMW-6, AMW-7, and AMW-14, nitrate at AMW-2, AMW-6, AMW-7, and AMW-14, potassium at AMW-14, sodium at AMW-14, field specific conductance at AMW-2 and AMW-7, strontium at AMW-6 and AMW-14, sulfate at AMW-7, and TDS at AMW-6 and AMW-7. Carbonate at AMW-2 exhibited an apparent increasing trend according to the Mann-Kendall/Sen's Slope analysis, but this trend is due to a historical increase in the laboratory RL. There was only one constituent that exhibited a statistically significant increasing trend during the first quarter 2010 and also exceeded a concentration limit: barium at AMW-14. As described above, the first quarter 2010 barium concentration at AMW-14 (0.26 mg/L) is comparable to concentrations observed at that well since August 2006, and is well below the National Primary Drinking Water Standard(2 mg/L). Mann-Kendall / Sen's Slope analysis identified decreasing trends in the following inorganic parameters: barium at AMW-12, calcium at AMW-12, chloride at AMW-12, magnesium at AMW-12, nitrate at AMW-13, field pH at AMW-2, potassium at AMW-12, strontium at AMW- 12, and field turbidity at AMW-2 and AMW-14. None of the VOCs that were detected in detection monitoring wells during the first quarter 2010 monitoring event exhibited a significant increasing trend according to the Mann-Kendall / Sen's Slope analysis. One VOC that was detected in a detection monitoring well during the first quarter 2010 exhibited a significant decreasing trend: trichloroethene at AMW-14. 1,2-Dichloropropane and dichlorodifluoromethane at AMW-14 exhibited apparent decreasing trends according to the Mann-Kendall/Sen's Slope analysis, but this trend is due to historical decreases in the laboratory RLs. 2.2 Corrective Action Monitoring During the first quarter 2010 monitoring event, Del-Tech collected groundwater samples from corrective action monitoring wells (AMW-1, AMW-5R, AMW-10, AMW-11, AMW-18, AMW- 19, and AMW-19BR). Corrective action monitoring well AMW-5R is a replacement for corrective action monitoring well AMW-5. Corrective action monitoring well AMW-19BR is a replacement for corrective action monitoring well AMW-19B. The field results provided by Del- Tech and laboratory results provided by BC Laboratories, Inc. for the first quarter 2010 corrective action monitoring event are summarized on Table 2.3. The historical groundwater data for the corrective action monitoring wells are presented in Appendix F. Times series concentration plots of historical groundwater data for the detection monitoring wells are presented in Appendix G. For VOCs, only those compounds that exhibited detections at corrective action monitoring wells during the first quarter 2010 monitoring event were plotted. 3