ARCHIVED REPORTS_XR0006720 CASE 1

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2.0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS • On June 6, 2003, to comply with quarterly groundwater monitoring requirements, Ramage Environmental monitored and sampled the five of the six monitoring wells and sampled the one on-site domestic water supply well Monitoring well MW-2 was not sampled because the well was dry (i e , the groundwater level was below the bottom of the well) 2.1 Groundwater Monitoring Depth-to-groundwater was measured in the five monitoring wells using a water level indicator capable of measurements to within 0 01 foot The depth to the groundwater table ranged from I 21 70 feet bgs in MW-6 to 23 64 feet bgs in MW-4 The depth to groundwater at MW-2 was below the total depth of the well of 23 80 feet The corresponding groundwater surface elevations ranged from a high of 15 11 feet above mean sea level (msl) at MW-1 to a low of 14 07 feet above msl at MW-5 The resulting groundwater surface appears as an irregular plane dipping to the northeast at a gradient of approximately 0 0094 foot/foot A groundwater surface contour map is included as Figure 5 The well construction details and groundwater monitoring data are summarized in Table 1 2.2 Groundwater Sampling and Analysis Following groundwater level measurements, the five wells were purged and sampled The monitoring 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 monitoring wells using dedicated and disposable polyethylene bailers and laboratory-supplied containers Groundwater was sampled from the water supply well using a bailer, after the pump had activated and the water was allowed to run for approximately 15 minutes All sample containers were 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, benzene, toluene, ethylbenzene and xylenes (BTEX) by EPA Method 8020/8015M, and for MTBE, di-isopropyl ether (DIPE), ethyl tertiary butyl ether(ETBE), tertiary amyl methyl ether (TAME), tertiary butanol (TBA), and 1,2-dichloroethane (1,2-DCA) by EPA Method 8260B • 6