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• 2 0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS On June 6, 2003, to comply with quarterly groundwater monitoring requirements, Ramage ' Environmental monitored and sampled the three wells 21 Groundwater Monitoring Depth-to-groundwater was measured using a water level indicator capable of measurements to ' within 0 01 foot The depth to the groundwater table, as measured in the three monitoring wells, ranged from 45 65 feet bgs in MW-2 to 46 08 feet bgs in MW-3 The corresponding groundwater surface elevations in the three wells ranged from a high of 24 56 feet below mean sea level (msl) at MW-2 to a low of 24 84 feet below msl at MW-3 The resulting groundwater surface appears as a regular plane dipping to the north-northeast at a gradient of approximately 0 00151 foot/foot A groundwater surface contour map is included as Figure 3 The well construction details, wellhead elevations and groundwater monitoring data are summarized in Table 5 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 (#2119) Excelchem analyzed each sample ' for TPH-as-tet fuel, TPH-as-gasoline and benzene, toluene, ethylbenzene, xylenes (BTEX) by EPA Method 8020/8015M, and for methyl tertiary butyl ether (MTBE), di-isopropyl ether (DIPE), ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether (TAME), and tertiary butanol (TBA) by EPA Method 82606 The groundwater samples collected from all three monitoring wells contained detectable concentrations of petroleum hydrocarbons The highest concentrations were detected at MW-1 This sample contained 3,900 µg/I of TPH-as-gasoline, 700 µg/l of benzene, 11 µg/I of toluene, 110 µg/I of ethylbenzene, and 58 pg/l of xylenes TPH-as-het fuel and MTBE were not detected in any of the groundwater samples The groundwater sample analytical results are summarized in Table 4, the concentrations of petroleum hydrocarbons in groundwater are posted on Figure 4, and the laboratory reports are included in Appendix A 5