ARCHIVED REPORTS XR0000033 - Laserfiche WebLink

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2.0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS On December 30, 2004, to comply with quarterly groundwater monitoring requirements, Ramage �l Environmental monitored and sampled the three wells 2.1 Groundwater Monitoring Depth-to-groundwater was measured in the wells to within 0 01-foot using a water level indicator The depth to the groundwater table ranged from 50 41 feet bgs in MW-2 to 50 90 feet bgs in MW- 3 The corresponding groundwater surface elevations ranged from a high of 29 32 feet below mean sea level (msl) at MW-2 to a low of 29 66 feet below msl at MW-3 The resulting groundwater surface appears as a regular plane dipping to the north at a gradient of approximately 0 0024 foot/foot A groundwater surface contour map is included as Figure 3 The well construction details, wellhead elevations and groundwater monitoring data are summarized in Table 5 22 Groundwater Sampling and Analysis Following groundwater level measurements, the wells were purged and sampled 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 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 (#2119) Excelchem analyzed each sample for TPH-as-het fuel, TPH-as-gasoline and benzene, toluene, ethylbenzene, xylenes (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 The sample information field sheets are included in Appendix A The groundwater samples collected from all three monitoring wells contained detectable concentrations of petroleum hydrocarbons Only TPH-as-gasoline was detected in the groundwater samples collected from MW-2 and MW-3 The oxygenate compounds were not detected in any of the groundwater samples The groundwater sample analytical results are summarized in Table 4, the concentrations of petroleum hydrocarbons in groundwater are posted on Figure 4 and the laboratory reports are included in Appendix B 5 r