ARCHIVED REPORTS_XR0004858 - Laserfiche WebLink

Home Browse Search

1 results from the monitoring and domestic well samples for the March 16, 1999 sampling • event. .Analytical results from previous sampling events are presented in Appendix C. 5.0 GROUNDWATER ANALYTICAL RESULTS 1 5.1 Laboratory Analysis of Ground Water Samples All ground water samples were submitted to GeoAnalytical 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. ' 6 Benzene Toluene Ethyl benzene Xylenes BTEX EPA Method 602 Detection limits 0.3 pg/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 ethyl benzene. Benzene, toluene, total xylenes and gasoline levels dropped between 28% and 71% as compared with the previous sampling event results. Ethyl benzene indicated a moderate increase from 36 µg/L in December 1998 to 46 µg/L this sampling event. Graph 1 shows the changes in BTEX levels over the past four sampling events. The sample collected from monitoring well MW-6 indicated no significant changes in the levels of toluene, which was below the detection limit, or gasoline. Benzene, ethyl benzene, and total xylenes levels increased slightly as compared with the results of the previous sampling event. Analytical laboratory data are summarized in Table 2 below. Laboratory data sheets, the chain of custody document, and QA/QC data sheets are included in Appendix A. American Geological services, Inc. CA95DE-029 7