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standards (California DHS). The historical record of the monitoring data are in Appendices E and F. Monitoring results for the second semester(Table 2) indicates that the concentrations of field and monitoring parameters are below established concentration limits for all remaining wells. VOCs One VOC (Trichloroethene, trace concentration) was reported in well MW-3 this semester. VOCs were not detected in wells MW-1, MW-2, and LW-I this semester. No analytes were detected in any of the laboratory control blanks this semester. Surface Water Surface water was not available for sampling this semester. The next samples will be taken this wet season if sufficient water is flowing at sampling points. Leachate Waste Discharge Requirements require monitoring leachate flow rate, pH, and Electrical Conductivity on a monthly basis (Table 3). Vadose Zone Soil Gas Soil gasses were sampled in November 2006. Samples were collected by first measuring the methane content using a CES-LANDTEC GEMTM 500 portable gas analyzer. The GEMTM 500 was operated until a steady-state gas composition indicated that the well was purged. After purging, gas samples were collected in 6-liter Summa canisters and sent to Atmospheric Analysis &Consulting, Inc. for analysis by EPA method TO-14A. Second Semester Results VOCs were detected in all soil gas samples (Table 4). The highest concentration of any VOC was found in SG-T. Ethanol and Freon 12 were most often reported with the highest concentration in a sample. The most VOCs (thirty-four) were reported were in SG-T. The results are consistent with the historical record. Methane concentrations were 0 percent in all the wells except for 2.6 percent in SG-11 and 23.1 percent in SG-T. i 1 Foothill Sanitary Landfill 7 Department of Public Works/Solid Waste 2nd Semester Groundwater Monitoring County of San Joaquin—January 31,2007