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2.0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS (1Q07) On March 1, 2007, to comply with quarterly groundwater monitoring requirements, and to monitor the plume of impacted groundwater, Ramage Environmental monitored and sampled the three wells. 2.1 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 11.90 feet below grade in MW-1 to 24.11 feet below street grade in MW-3. The groundwater surface ti.. elevation in the three wells ranged from a high of 11.76 feet below mean sea level (msl) at MW-1 to a low of 12.55 feet below msl at MW-3. The resulting groundwater surface appears as a regular plane dipping to the northeast at a gradient of approximately 0.0094 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. Between December 13, 2006 and March 1, 2007, the groundwater surface rose an average of 0.12 feet, the groundwater gradient decreased from 0.0098 to 0.0094 foot/foot, and the `P4 groundwater flow direction remained toward the northeast. These groundwater surface characteristics are consistent with historical and seasonal trends. 2.2 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 8021 B/8015M, and for MTBE, di-isopropyl ether `F (DIPE), ethyl tertiary butyl ether(ETRE), tertiary amyl methyl ether(TAME), tertiary butanol (TBA), 1,2-dichloroethane (1,2-DCA), and 1,2-dibromoethane (EDB) by EPA Method 82606. 7