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' 2.0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS <br /> On December 30, 2004, to comply with quarterly groundwater monitoring requirements and to <br /> monitor the plume of impacted groundwater, Ramage Environmental monitored and sampled the <br /> six on-site monitoring wells In addition, Ramage Environmental continued monthly free product <br /> removal from MW-1 <br /> 2.1 Groundwater Monitoring <br /> Depth-to-groundwater was measured to within 0 01 foot in each of the wells using a water level <br /> indicator The depth to static groundwater across the site ranged from 48 65 feet bgs in MW-6 to <br /> 49 57 feet bgs in MW-5 The corresponding groundwater surface elevation ranged from a high of <br /> 29 53 feet below mean sea level (msl) at MW-2 to a low of 30 44 feet below msl at MW-4 The <br /> groundwater elevations at MW-1 and MW-2 do not appear to fit the regional trend, possibly due to <br /> the presence of free product Otherwise, the groundwater table surface appears as a plane <br /> dipping toward the east at a gradient of approximately 0 0016 foot/foot A groundwater surface <br /> contour map is included as Figure 4 The well construction details and groundwater monitoring <br /> data are summarized in Table 1 <br /> 2.2 Groundwater Sampling and Analysis <br /> Fallowing the groundwater level measurements, MW-2, MW-3, MW-4, MW-5 and MW-6 were <br /> purged and sampled Due to the presence of a free product sheen, MW-1 was not sampled The <br /> wells were purged using a pump and dedicated disposable tubing, until at least three well casing <br /> volumes were extracted, and/or after groundwater temperature, pH and electrical conductivity <br />' values had stabilized Following well purging and recharge, groundwater was sampled from the <br /> wells using dedicated disposable bailers and laboratory-supplied containers <br /> Each sample container was transported in an iced cooler with chain-of-custody documentation to <br /> Excelchem Environmental Labs (Excelchem), a state of California certified hazardous waste <br /> testing laboratory (Certification #2119) Excelchem analyzed each of the groundwater samples <br /> for TPH-as-gasoline and BTEX by EPA Method 8020/8015M, and for methyl tertiary butyl ether <br /> (MTBE), di-isopropyl ether (DIPS), ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether <br /> r (TAME), tertiary butanol (TBA), and 1,2-dichloroethane (1,2-DCA) by EPA Method 8260B <br /> 5 <br />