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2 0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS I On November 12, 1999, Ramage Environmental monitored and sampled groundwater at the site 21 Groundwater Monitoring Depth-to-groundwater measurements were taken in fourroundwater monitoring wells to 9 g evaluate groundwater flow and gradient characteristics Depth-to-groundwater measurements were not taken from MW-1 and the two deep soil vapor extraction wells (VW-1 and VW-2), because their wellhead elevations were moved during the installation of the soil vapor extraction and air sparging system During this quarter, groundwater measurements were also not taken from MW-4 and MW-5 because their wellheads were blocked by the remediation system monitoring equipment The depth-to-groundwater beneath the site ranged from 38 54 feet below ground surface (bgs) in MW-2 to 41 57 feet bgs in MW-7 MW-7 is completed above-grade and protected with a monument casing The groundwater elevation beneath the site ranged from a high of 23 28 feet below mean sea level (MSL) in MW-6 to a low of 23 44 feet below MSL in MW-2 Groundwater levels have dropped an average of 1 40 feet, since groundwater levels were last measured on August 26, 1999 In the past year, groundwater levels have risen an average of 0 51 feet Since May 1992, the groundwater levels have risen an average of 25 81 feet The current and historical groundwater monitoring data are summarized in Table 1 The groundwater flow direction and gradient are illustrated on the groundwater surface map (Figure 3) The groundwater gradient was calculated at 0 002 foot/foot in a southerly direction 22 Groundwater Sampling and Analysis Groundwater from MW-6, MW-7 and the two deep soil vapor extraction wells VW-1 and VW-2 was sampled to evaluate the concentration of gasoline hydrocarbons at the groundwater table The groundwater monitoring wells (MW-1, MW-2, MW-3, MW-4 and MW-5) were not sampled, because of groundwater levels significantly above the screened interval of these wells Each of the four wells (MW-6, MW-7, VW-1 and VW-2) was purged of at least three well volumes using a decontaminated bailer Following purging and recharge, groundwater samples were collected from the four wells using dedicated and disposable sampling bailers The groundwater samples were contained in laboratory-supplied containers, labeled, and packed in an iced cooler for transport with chain-of-custody documentation to Kiff Analytical, LLC (Kiff), a state of California certified analytical laboratory (#2236) 4 f