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2.0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS On March 15, 2006, to comply with quarterly groundwater monitoring requirements, and to monitor ' the plume of impacted groundwater, Ramage Environmental monitored and sampled the three wells 21 Groundwater Monitoring Depth-to-groundwater was monitored to within 0 01-foot using a water level indicator The static depth to the groundwater table, as measured in the three monitoring wells, ranged from 13 65 feet below grade in MW-1 to 26 00 feet below street grade in MW-3 The groundwater surface ' elevation in the three wells ranged from a high of 13 51 feet below mean sea level (msl) at MW-1 to a low of 14 44 feet below msl at MW-3 The resulting groundwater surface appears as a ' regular plane dipping to the northeast at a gradient of approximately 0 0113 foot/foot A groundwater surface contour map is included as Figure 4, the groundwater monitoring data are summarized in Table 3, and the sample information field sheets are included in Appendix A 1 2.2r Groundwater Sampling and Analysis �i Following groundwater level measurements, the wells were purged and sampled The wells were purged with a pump and dedicated disposable tubing until at least three well casing volumes had ' been removed and/or after groundwater temperature, pH and electrical conductivity values had stabilized Groundwater was sampled from the wells using disposable polyethylene bailers and laboratory-supplied containers Each sample container was transported in an iced cooler with chain-of-custody documentation to Excelchem Environmental Labs (Excelchem), a state of California certified hazardous waste testing laboratory (Certification #2119) Excelchem analyzed ' each groundwater sample for TPH-as-gasoline and benzene, toluene, ethylbenzene, xylenes (BTEX) by EPA Method 8021B/8015M, and for MTBE, di-isopropyl ether (DIPS), ethyl tertiary ' butyl ether(ETRE), tertiary amyl methyl ether (TAME), tertiary butanol (TBA), and 1,2- dichloroethane (1,2-DCA) by EPA Method 8260B -f tau ako 1jz-44 ED B. V1117 ' The highest concentrations of gasoline compounds were detected in the sample collected from MW-1 407 micrograms per liter (pg/1) of TPH-as-gasoline, 47 4 µg/l of benzene, 2 9 µg/l of ' toluene, 44 1 µg/l of ethylbenzene, 13 7 pg/l of xylenes, 2 2 µg11 of MTBE, and 16 µg/l of 1,2- DCA Only MTBE was detected in MW-2 at 3 8 fig/l and in MW-3 at 1 7 µg/I The groundwater sample analytical results are summarized in Table 2, the distribution of gasoline in groundwater is shown on Figure 5, and the laboratory reports are included in Appendix B 1'10 6 f