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2.0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS On May 9, 2003, to comply with quarterly groundwater monitoring requirements, Ramage Environmental monitored and sampled the three wells 21 Groundwater Monitoring Depth-to-groundwater was monitored using a water level indicator capable of measurements to within 0 01 foot The static depth to the groundwater table, as measured in the three monitoring wells, ranged from 14 55 feet below grade in MW-1 to 26 67 feet below street grade in MW-3 The groundwater surface elevation in the three wells ranged from a high of 14 41 feet below mean sea level (msl) at MW-1 to a low of 15 11 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 0082 foot/foot A groundwater surface contour map is included as Figure 4, and the groundwater monitoring data are summarized in Table 3 22 Groundwater Sampling and Analysis 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 8020/8015M, and for MTBE, di-isopropyl ether (DIPS), ethyl tertiary butyl ' ether (ETBE), tertiary amyl methyl ether(TAME), tertiary butanol (TBA), and 1,2-dichloroethane (1,2-DCA) by EPA Method 82606 Only the groundwater sample collected from MW-1 contained detectable concentrations of gasoline hydrocarbons This sample contained 11,000 micrograms per liter (µg11) of TPH-as- gasoline, 880 pg/I of benzene, 430 µg11 of toluene, 980 µg/l of ethylbenzene, and 2,600 µg/l of xylenes 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 A 6