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2 0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS <br /> On October 14, 1999, Ramage Environmental monitored and sampled groundwater at <br /> the site <br /> 21 Groundwater Monitoring <br /> Depth-to-groundwater measurements were taken in all three groundwater monitoring <br /> wells to evaluate groundwater flow and gradient characteristics The depth to <br /> groundwater beneath the site ranged from 39 59 feet bgs in MW-2 to 40 64 feet bgs in <br /> MW-1 The corresponding groundwater surface elevation ranged from a high of 21 29 <br /> feet below mean sea level (msl) at MW-3 to a low of 21 77 feet below ms] at MW-2 <br /> Groundwater levels have dropped an average of 1 43 feet, since the wells were last <br /> monitored on July 23, 1999 Cumulative groundwater monitoring data are summarized in <br /> Table 1 <br /> The groundwater flow direction and gradient are shown on the groundwater surface map <br /> (Figure 3) In general, the resulting groundwater surface appears as a plane dipping to <br /> the south-southeast at a gradient of approximately 0 04 foot/foot <br /> 22 Groundwater Sampling and Analysis <br /> Groundwater from all three wells was sampled to evaluate the concentration of gasoline <br /> hydrocarbons in groundwater beneath the site Each of the wells was purged of at least <br /> three well volumes using a decontaminated bailer Temperature, pH and electrical <br /> conductivity measurements were taken during purging Following purging, groundwater <br /> samples were collected from all three wells using dedicated and disposable sampling <br /> bailers The groundwater samples were contained in laboratory-supplied glassware, <br /> labeled and packed in an iced cooler for transport with chain-of-custody documentation <br /> to Kiff Analytical, LLC (Kiff), a state of California certified analytical laboratory (#2236) <br /> Kiff analyzed the groundwater samples for TPH-as-gasoline, BTEX, methyl-t-butyl ether <br /> (MTBE), diisopropyl ether (DIPE), ethyl-t-butyl ether (ETBE), tert-amyl methyl ether <br /> (TAME), and tert-butanol (TBA) by EPA Method 8260B The laboratory report and chain <br /> of custody are included in Appendix A <br /> Analytical results from the groundwater samples indicate that groundwater beneath and <br /> to the west of the former UST excavation is impacted by significant concentrations of <br /> gasoline hydrocarbons The highest concentrations of gasoline hydrocarbons were <br /> 5 <br />