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I I I ' i 2.0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS On August 28, 2008, to comply with quarterly groundwater monitoring requirements, Ramage r ' Environmental monitored and sampled the three wells for the final time. ,i i 2.1 Groundwater Monitoring To calculate the groundwater gradient and flow direction, Ramage Environmental measured the depth to groundwater to within 0.01-foot using a water level indicator:` The static depth to the II 3 groundwater table, as measured in the three monitoring wells, ranged from 12.40 feet below grade in MW-1 to 24.32 feet below street grade in MW-3. The.groun;dwater surface elevation in the three wells ranged from a high of 12.23 feet below mean sea level (msl) at MW-2 to a low of 12.76 feet below msl at MW-3. The resulting groundwater surface appears as a regular plane dipping to the northeast at a gradient of approximately 0.0059 foot/foot. A groundwater surface contour map is included as Figure 4, the groundwater monitoring data are summarized in Table I 3, and the sample information field sheets are included in Appendix B. i� Between June 30, and August 28, 2008, the groundwater surface in the three monitoring wells dropped an average of 0.38 feet, the groundwater gradient dechreased from 0.0066 to 0.0059 foot/foot, and the groundwater flow direction remained toward the northeast. These groundwater surface characteristics are consistent with historical and seasonal trends. 2.2 Groundwater Sampling and Analysis L� Following groundwater level measurements, Ramage Environmentai purged and sampled the three monitoring wells. 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. Ramage Environmental transported the groundwater sample co ntain6rs in an iced cooler with chain-of-custody documentation to Excelchem Environmental Labs (Excelchem), a state of f California certified hazardous waste testing laboratory (Certification #2119). Excelchem analyzed each groundwater sample for TPH-as-gasoline and b�enzen:e, toluene, ethylbenzene, xylenes (BTEX) by EPA Method 8021B/8015M, and for MTBE,Idi-isopropyl ether (DIPE), ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether (TAME), tertiary butanol (TBA), 1,2- dichloroethane (1,2-DCA), and 1,2-dibromoethane (EDB) by EPA Method 8260B. ,I .I - i 8 I I