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hydrocarbons, hexavalent chromium, magnesium, nitrate, oil and grease, potassium, sodium, strontium, sulfate,TDS,and VOCs). 2.1 Detection Monitoring During the third quarter 2009 monitoring event, ATC Associates, Inc. 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 ATC Associates, Inc. and laboratory results provided by BC Laboratories, Inc. for the third quarter 2009 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 third quarter 2009 monitoring event were plotted. The concentration limits presented on Table 2.2 were calculated by Herst&Associates,Inc. from data collected through the third quarter 2009 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 third quarter 2009 monitoring event, barium at AMW-13 and AMW-14, hexavalent chromium at AMW-6 and AMW-7, and field temperature at AMW-7 exceeded their respective concentration limits. The third quarter 2009 barium concentration at AMW-13 (0.26 mg/L) is comparable to concentrations observed at that well consistently since May 1995, and is well below the National Primary Drinking Water Standard (2 mg/L). The third quarter 2009 barium concentration at AMW-14 (0.24 mg/L) is comparable to concentrations observed at that well consistently since August 2006, and is well below the National Primary Drinking Water Standard (2 mg/L). The third quarter 2009 hexavalent chromium concentration at AMW-6 (0.0054 mg/L) is comparable to concentrations observed at that well intermittently since February 1997, and is well below the National Primary Drinking Water Standard for chromium (0.1 mg/L). The third quarter 2009 hexavalent chromium concentration at AMW-7 (0.0063 mg/L) is comparable to concentrations observed at that well intermittently since July 1995, and is well below the National Primary Drinking Water Standard for chromium (0.1 mg/L). The third quarter 2009 field temperature value at AMW-7 (21.4 °C) is comparable to values observed at that well intermittently since June 1994. During the third quarter 2009 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. Dichlorofluoromethane, tetrachloroethene, and trichloroethene were detected above the PQL at AMW-14. The third quarter 2009 concentration of dichlorofluoromethane at AMW-14 (0.61 ug/L) is comparable to concentrations observed at that well intermittently since May 1996. The third quarter 2009 concentration of tetrachloroethene at AMW-6 (0.94 ug/L) is comparable to concentrations observed at that well intermittently since September 1996, and is below the National Primary Drinking Water Standard (5 ug/L). The third quarter 2009 concentration of tetrachloroethene at AMW-13 (2.4 ug/L) is comparable to concentrations observed at that well intermittently since March 1994, and is below the National Primary Drinking Water Standard (5 2