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Table 2.2 presents the VOC detections at background and detection monitoring wells during the third quarter 2006 monitoring event. Bromoform was detected in background monitoring well MW-6A at a concentration of 1.3 ug/L. Dibroochloromethane was detected in background monitoring well MW-6A and detection monitoring well MW-l0A at concentrations (0.44 ug/L and 0.23 ug/L, respectively) below the laboratory practical quantitation limit (PQL). Trichlorofluoromethane was detected in detection monitoring well MW-9A at a concentration of 2.9 ug/L. Neither bromoform, dibromochloromethane, or trichlorofluoromethane exhibits an increasing trend according to Sen's Slope analysis. Trichlorofluoromethane at MW-9A exhibits a decreasing trend according to Sen's Slope analysis. The bromoform detection at MW-6A during the third quarter 2006 is the first detection of this constituent at this well. The dibromochloromethane detections at MW-6A andMW-l0A during the third quarter 2006 are the first detections of this constituent at these wells. 2.3 Results for Evaluation Monitoring ells Groundwater samples were collected during the third quarter 2006 monitoring event from evaluation monitoring well MW-2. Bryan A. Stirrat and Associates reported that evaluation monitoring well MW-lA was dry during the third quarter 2006. The field and laboratory results from the third quarter 2006 sampling event are summarized on Table 2.3. The historical groundwater data for the evaluation monitoring wells are presented in Appendix F. The field and monitoring parameter data are presented on time series concentration plots in Appendix G. Historical data from the evaluation monitoring wells were evaluated for temporal trend using Sen's Slope trend analysis. Graphs of the Sen's Slope analyses are included in Appendix G. The only constituent to exhibit an increasing trend according to Sen's Slope analysis was sulfate at MW-2. Sen's Slope analysis identified decreasing trends in barium at MW-2, chloride at MW- IA and MW-2, magnesium at MW-2,and temperature at MW-IA. There were no VOC detections at evaluation monitoring well MW-2 during the third quarter 2006 monitoring event. 3