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' The samples were transported under strict chain-of-custody protocol to GeoAnalytical • Laboratories in Modesto, California for analysis. All samples were delivered to the ' analytical laboratory within two hours from their time of collection. Appendix A contains analytical data, chain-of-custody and QA/QC data. Table 2 summarizes the ' analytical results from the monitoring and domestic well samples for the June 15 and 22, 1999 sampling event. Historical analytical results are presented in Appendix C. 1 5.0 GROUNDWATER ANALYTICAL RESULTS ' 5.1 Laboratory Analysis sis of Ground Water Samples p All ground water samples were submitted to GeoAnalyticai Laboratories of Modesto, California and were analyzed for the following constituents by the indicated methods: ' Total Petroleum Hydrocarbons (TPH) - Gasoline, Method 5030/LUFT Detection limit 0.05 mg/L. 1 • Benzene, Toluene, Ethyl benzene, Xylenes (BTEX), EPA Method 602 Detection limits 0.3 gg/L BTE, 0.6 µg/L X. The detection limits quoted above are the minimum reportable levels specified by the analytical laboratory. The presence of other hydrocarbons may raise the detection limits ' for specific constituents. Refer to the laboratory data sheets in Appendix A for sample specific detection limits. ' 5.2 Discussion of Analytical Results Analytical laboratory data indicate a significant decrease in detected constituent levels in monitoring well MW-lA, with the exception of toluene which remained essentially unchanged. Benzene, toluene, total xylenes and gasoline levels dropped between 15% j ' and 78% as compared with the previous sampling event results. These data indicate a continuation of a significant decrease in contaminant mass since the performance of the ' remedial soil excavation. The sample collected from monitoring well MW-6 indicated modest increases in gasoline I ' and BTEX levels. Benzene increased from 1.9 µg/L to 5.1 pg/L, and gasoline increased from 0.2 mg/L to 0.4 mg/L. These changes are believed to be related to the disturbance of the subsurface caused by the remedial soil excavation. ' No detectable levels of analyzed constituents were reported for monitoring wells MW-5, iMW-7, and MW-9, and the two domestic wells, North Well and South Well. These data tare consistent with results reported for prior sampling events. American Geological Service, Inc. ' CA95DE-029 8