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2 0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS <br /> • <br /> On March 11, 2004, to comply with quarterly groundwater monitoring requirements, Ramage <br /> Environmental monitored and sampled the six monitoring wells and sampled the one on-site <br /> domestic water supply well <br /> 21 Groundwater Monitoring <br /> Depth-to-groundwater was measured in the six monitoring wells using a water level indicator <br /> capable of measurements to within 0 01 foot The depth to the groundwater table ranged from <br /> 21 00 feet bgs in MW-6 to 22 97 feet bgs in MW-4 The corresponding groundwater surface <br /> elevations ranged from a high of 15 53 feet above mean sea level (msl) at MW-1 to a low of 14 77 <br /> feet above msl at MW-5 The resulting groundwater surface appears as an irregular plane <br /> dipping to the north-northeast at a gradient of approximately 0 0058 foottfoot A groundwater <br /> surface contour map is included as Figure 5 The well construction details and groundwater <br /> monitoring data are summarized in Table 1 <br /> 22 Groundwater Sampling and Analysis <br /> Following groundwater level measurements, the six wells were purged and sampled The <br /> monitoring wells were purged with a pump and dedicated disposable tubing until at least three <br /> well casing volumes had been removed and/or after groundwater temperature, pH and electrical <br /> conductivity values had stabilized Groundwater was sampled from the monitoring wells using <br /> dedicated and disposable polyethylene bailers and laboratory-supplied containers Groundwater <br /> was sampled from the water supply well using a bailer, after the pump had activated and the water <br /> was allowed to run for approximately 15 minutes All sample containers were transported in an <br /> iced cooler with chain-of-custody documentation to Excelchem Environmental Labs (Excelchem), <br /> a state of California certified hazardous waste testing laboratory (Certification #2119) <br /> Excelchem analyzed each of the groundwater samples for TPH-as-gasoline, benzene, toluene, <br /> ethylbenzene and xylenes (BTEX) by EPA Method 8020/8015M, and for MTBE, di-isopropyl ether <br /> (DIPE), ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether (TAME), tertiary butanol (TBA), <br /> and 1,2-dichloroethane (1,2-DCA) by EPA Method 8260B <br /> . 6 <br />