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No VOCs were reported at this well this quarter. VOCs were last detected in this well on April 23, 2004. Surface water Surface water samples were last taken on January 3, 2006. Surface water was not available for sampling this quarter. Samples will be taken if sufficient water is flowing at sampling points during this wet season. The dry climate at this site makes collection of a surface water difficult. Unsaturated Zone Soil Pore Gas The Monitoring and Reporting program for the landfill requires semi-annual VOC sampling. Soil gas samples were collected on February 26, 2007. Before sampling for TO-14 analysis, the concentration of major gasses (methane, Carbon Dioxide, and Oxygen) and pressure were measured using a CES-LANDTEC GEMTm2000 portable gas detector. The GEMTm2000 was operated until a steady-state gas composition indicated that the well was purged and ready for sampling. Soil gas samples were collected in 1-liter Summa canisters and sent to Air Toxics Ltd. for analysis by EPA method TO-14. The concentrations of major gasses were recorded at the first TO-14 sampling event, and a VOC sample was collected from the probe most likely to have the highest VOC concentration. Where no combustible gas was detected, the VOC sample was collected from the deepest probe. The probe selected in the first TO-14 sampling was used thereafter for this analysis. Since that time, sampling has continued at the probe selected for the first TO-14 sampling wvent. Results Methane concentrations were zero in all wells during the first and second quarters of 2007. VOCs were detected in all of the seven soil gas well locations during the first quarter 2007 sampling event. The highest VOC concentration was found in well SG-6 (Table 4 and Appendix Q. No "upwind"air sample was taken. Groundwater Direction and Flow Rate Calculations for the following statements are located in Appendix G. Shallow Aquifer Groundwater elevations at wells SB-1, MW-4, and MW-5 indicate that groundwater flow in the shallow water-bearing zone is outward from SB-1 towards MW-5 and MW-4 (Figure 2). The average calculated groundwater velocity is 2.39 ft/yr based on a gradient of 0.0086 foot per foot. The current water levels are similar to the conditions present in the late 1990s. Corral Hollow Landfill 9 Department of Public Works/Solid Waste 2nd Quarter 2007 Groundwater Monitoring County of San Joaquin—July 31,2007