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1 <br /> The two on-site domestic wells were also sampled during this quarterly sampling event. <br /> Each well was sampled by activating the installed submersible pump to produce water. <br /> Samples were collected at the well head sampling ports by gently filling two VOA vials <br /> in accordance with the procedures previously described. <br /> The samples were transported under strict chain-of-custody protocol to GeoAnalytical <br /> Laboratories in Modesto, California for analysis. All samples were delivered to the <br /> analytical laboratory within three hours from their time of collection. Appendix A <br /> contains analytical data, chain-of-custody and QA/QC data. Table 2 summarizes the <br /> analytical results from the monitoring and domestic well samples for the December 18, <br /> 1998 sampling event. Analytical results from previous sampling events are presented in <br /> Appendix C. <br /> 5.0 GROUNDWATER ANALYTICAL RESULTS <br /> 5.1 Laboratory Analysis of Ground Water Samples <br /> All ground water samples were submitted to GeoAnalytical Laboratories of Modesto, <br /> California and were analyzed for the following constituents by the indicated methods: <br /> '• • Total Petroleum Hydrocarbons(TPH) - Gasoline, Method 5030/LUFT <br /> Detection limit 0.05 mg/L. <br /> • Benzene, Toluene, Ethyl benzene, Xylenes (BTEX), EPA Method 602 <br /> Detection limits 0.3 µg/L BTE, 0.6 µg/L X. <br /> The detection limits quoted above are the minimum reportable levels specified by the <br /> analytical laboratory. The presence of other hydrocarbons may raise the detection limits <br /> ' for particular constituents. Refer to the laboratory data sheets in Appendix A for sample <br /> specific detection limits. <br /> 5.2 Discussion of Analytical Results <br /> Analytical laboratory data indicate a significant decrease in detected constituent levels in <br /> monitoring well MW-lA. Benzene, toluene, ethyl benzene and total xylene levels <br /> dropped between 38% and 93% as compared with the previous sampling event results. <br /> Gasoline levels dropped approximately 50% from those obtained during the previous <br /> i <br /> sampling event. Graph 1 shows the reductions in BTEX levels over the past three <br /> sampling events. <br /> • American Geological Services, Inc. <br /> ' CA95DE-029 <br /> 7 <br />