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i i 2.0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS On July 23, 1999, Ramage Environmental monitored and sampled groundwater at the site 2.1 Groundwater Monitoring ' Depth-to-groundwater measurements were taken in all three groundwater monitoring wells to evaluate groundwater flow and gradient characteristics The depth to groundwater beneath the site ranged from 38 15 feet bgs in MW-2 to 39 20 feet bgs in MWA The corresponding groundwater surface elevation ranged from a high of 19 86 feet below mean sea level (msl) at MW-3 to a low of 20 33 feet below msl at MW-2 Groundwater levels have dropped an average of 0 93 feet, since the wells were last monitored on Apn! 22, 1999 Cumulative groundwater monitoring data are summarized in Table 1 ' The groundwater flow direction and gradient are shown on the groundwater surface map (Figure 3) In general, the resulting groundwater surface appears as a plane dipping to the south-southeast at a gradient of approximately 0 06 foottfoot 22 Groundwater Sampling and Analysis Groundwater from all three wells was sampled to evaluate the concentration of gasoline hydrocarbons in groundwater beneath the site Each of the wells was purged of at least three well volumes using a decontaminated bailer Temperature, pH and electrical conductivity measurements were taken during purging Following purging, groundwater samples were collected from all three wells using dedicated and disposable sampling bailers The groundwater samples were contained in laboratory-supplied glassware, labeled and packed in an iced cooler for transport under chain-of-custody documentation to Kiff Analytical, LLC (Kiff), a state of California certified analytical laboratory (#2236) Kiff analyzed the groundwater samples for TPH-as-gasoline, BTEX, methyl-t-butyl ether (MTBE), ditsopropyl ether (DIPE), ethyl-t-butyl ether (ETBE), tert-amyl methyl ether (TAME), and tert-butanol (TBA) by EPA Method 82608 The laboratory report and chain of custody are included in Appendix A Analytical results from the groundwater samples indicate that groundwater beneath and to the west of the former UST excavation is impacted by significant concentrations of gasoline hydrocarbons The highest concentrations of gasoline hydrocarbons were 5