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and MW-l0A) during the first quarter 2009 monitoring event. The analytical results from samples collected at these wells are used to determine potential landfill-related impacts. During the first quarter 2009 monitoring event, analysis for field parameters (pH, specific conductance, temperature, and turbidity) and monitoring parameters (bicarbonate, calcium, carbonate, chloride, magnesium, nitrate, potassium, sodium, sulfate, total dissolved solids [TDS], and volatile organic compounds [VOCs]) was performed for the background monitoring wells and detection monitoring wells. First quarter 2009 field and laboratory sampling results from background and detection monitoring wells are summarized on Table 2.2, along with the concentration limits determined from background monitoring well data. The historical groundwater data for the background and detection monitoring wells are presented in Appendix D. The data are graphed on time series concentration plots in Appendix E. The concentration limits were developed using data collected through the first quarter 2009. The statistical analysis calculations are presented in Appendix E. A copy of the statistical analysis methodology is presented in Appendix C. As presented on Table 2.2, the following constituents exceeded their respective concentration limits: calcium at MW-9A, MW-9B, and MW-10A, chloride at MW-9B and MW-10A, magnesium at MW-9B and MW-10A, field pH at MW-9A and MW-10A, potassium at MW-9A, MW-9B, and MW-10A, field temperature at MW-9A and MW-10A, and TDS at MW-10A. The chloride concentrations (with high specific conductance values) could indicate a saltwater intrusion to the groundwater. The French Camp Landfill is within the central Stockton area impacted by saltwater intrusion (Fourth Quarter/Annual 1999 Monitoring Report, French Camp Landfill, CH2MHILL,January 2000). Historical data from the background and detection monitoring wells were evaluated for temporal trend using Sen's Slope trend analysis. Graphs of the Sen's Slope analyses are included in Appendix E. Bicarbonate at MW-7A, chloride at MW-10A, and sulfate at MW-9B exhibited increasing trends, but did not exceed their respective concentration limits. Sen's Slope analysis identified decreasing trends in the following constituents: calcium at MW-8A, chloride at MW-7A, magnesium at MW-8A, nitrate at MW-8A and MW-10A, field pH at MW-6A and MW-9B, sodium at MW-8A, field specific conductance at MW-7A, sulfate at MW-7A, total dissolved solids at MW-7A, and field turbidity at MW-7A, MW-9A, and MW-10A. As noted above, MW- 6A and MW-7A are background monitoring wells, and trends in the groundwater quality at these wells are not indicative of an impact from the facility. Chloride at MW-10A was the only constituent that exceeded its concentration limit and exhibited a significant increasing statistical trend. The first quarter 2009 concentration of chloride at MW-l0A (600 mg/L) is comparable to concentrations observed at that well since April 2002. As presented in Table 2.2,there was one VOC detected at a detection monitoring wells during the first quarter 2009 monitoring event. Chloroform was detected at background well MW-6A at a concentration (1.0 ug/L) above the laboratory PQL. Chloroform has previously been detected at MW-6A at concentrations ranging from 0.10 ug/L to 0.81 ug/L.