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2.1 Detection Monitoring During the second quarter 2010 monitoring event, Del-Tech collected groundwater samples from the background well (AMW-2) and detection monitoring wells (AMW-6, AMW-7, AMW-12, AMW-13, and AMW-14). The field results provided by Del-Tech and laboratory results provided by BC Labs for the second quarter 2010 groundwater detection monitoring event are summarized on Table 2.2. The historical groundwater data for the detection monitoring wells are presented in Appendix D. Times series concentration plots of historical groundwater data for the detection monitoring wells are presented in Appendix E. For VOCs, only those compounds that exhibited detections at detection monitoring wells during the second quarter 2010 monitoring event were plotted. The concentration limits presented on Table 2.2 were calculated by Herst & Associates, Inc. from data collected through the second quarter 2010 monitoring event. The statistical analysis calculations for detection monitoring wells are presented in Appendix E. Information on the development of the concentration limits can be found in the Fourth Quarter/Annual 1999 Monitoring Report, Austin Road Landfill, prepared by CH2M Hill in January 2000. A copy of the statistical analysis methodology is presented in Appendix C. During the second quarter 2010 monitoring event,barium at AMW-13 and AMW-14 exceeded its concentration limit. The second quarter 2010 barium concentration at AMW-13 (0.27 mg/L) is comparable to concentrations observed at that well since May 1995, and is well below the National Primary Drinking Water Standard (2 mg/L). The second quarter 2010 barium concentration at AMW-14 (0.25 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). During the second quarter 2010 monitoring event, no VOCs were detected above the laboratory practical quantitation limit (PQL) in samples collected from detection monitoring wells AMW-2, AMW-7, or AMW-12. Tetrachloroethene was detected above the PQL at AMW-6. Tetrachloroethene and trichloroethene were detected above the PQL at AMW-13. Tetrachloroethene was detected above the PQL at AMW-14. The second quarter 2010 concentration of tetrachloroethene at AMW-6 (0.76 ug/L) is comparable to historical concentrations observed at that well, and is below the National Primary Drinking Water Standard (5 ug/L). The second quarter 2010 concentration of tetrachloroethene 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). The second quarter 2010 concentration of tetrachloroethene at AMW-14 (3.2 ug/L) is comparable to historical concentrations observed at that well, and is below the National Primary Drinking Water Standard (5 ug/L). The second quarter 2010 concentration of trichloroethene at AMW-13 (1.0 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 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, 2