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2.0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS On June 29, 2005, to comply with quarterly groundwater monitoring requirements and to monitor ' the plume of impacted groundwater, Ramage Environmental monitored and sampled the seven on-site monitoring wells In addition, Ramage Environmental continued monthly free product ' removal from MW-1 21 Groundwater Monitoring Depth-to-groundwater was measured to within 0 01 foot in each of the wells using a water level ' indicator The depth to static groundwater across the site ranged from 44 95 feet bgs in MW-7 to 47 00 feet bgs in MW-2 The corresponding groundwater surface elevation ranged from a high of 26 90 feet below mean sea level (msl) at MW-7 to a low of 27 90 feet below msl at MW-4 The groundwater table surface appears as a plane dipping toward the east-southeast at a gradient of approximately 0 002 foot/foot A groundwater surface contour map is included as Figure 4 The ' well construction details and groundwater monitoring data are summarized in Table 1 22 Groundwater Sampling and Analysis M Following the groundwater level measurements, all wells except MW-1 were purged and sampled Due to the presence of a free product sheen, MW-1 was not sampled The wells were purged using a pump and dedicated disposable tubing, until at least three well casing volumes were extracted, and/or after groundwater temperature, pH and electrical conductivity values had ' stabilized Following well purging and recharge, groundwater was sampled from the wells using dedicated disposable 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 groundwater samples for TPH-as-gasoline and 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 8260B 5