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2.0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS On September 12, 2003, to comply with quarterly groundwater monitoring requirements, Ramage Environmental monitored and sampled the four existing on-site groundwater monitoring 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 four groundwater morntonng wells, ranged from 24 42 feet bgs in MW-1 to 25 69 feet bgs in MW-3 The groundwater surface elevation in th four wells ranged from a high of 13 29 feet below mean sea level (msl) at MWA to a low of 13 4feet below ms] at MW-4 The resulting groundwater surface appears as an irregular plane dipping to the east-southeast at a gradient of approximately 0 0263 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 of the samples for TPH-as-motor oil, TPH-as-diesel, TPH-as-kerosene, TPH-as-gasoline and BTEX by EPA Method 802018015M, and for MTBE, di-isopropyl ether(DIPE), ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether(TAME), and tertiary butanol (TBA) by EPA Method 8260B The groundwater samples collected from MW-1, MW-2 and MW-3 contained detectable concentrations of petroleum hydrocarbons, including TPH-as-gasoline, TPH-as-kerosene, and BTEX compounds The groundwater sample collected from MWA did not contain detectable concentrations of petroleum hydrocarbons The oxygenate compounds, TPH-as-diesel and TPH- as-motor oil were not detected in any of the four groundwater samples The groundwater sample analytical results are summarized in Table 2, the distribution of gasoline and benzene in groundwater is shown on Figure 5, and the laboratory reports are included in Appendix A 6