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i.. 2.0 GROUNDWATER MONITORING, SAMPLING AND ANALYSIS A,. On August 26, 1999, Ramage Environmental monitored and sampled groundwater at the site. 2.1 Groundwater Monitoring Depth-to-groundwater measurements were taken in four groundwater monitoring wells to 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, due to the presence of down-hole remediation system monitoring # ' equipment. The depth-to-groundwater beneath the site ranged from 37.03 feet below ground } surface (bgs) in MW-2 to 40.21 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 21.93 feet below mean sea level (MSL) in MW-2 to a low of 21.97 feet below MSL in MW-7. Groundwater levels have dropped an average of 2.64 feet, since groundwater levels were last measured on May 20, 1999. In the past year, groundwater levels have risen an average of 1.08 feet. Since May 1992, the groundwater levels have risen an average of 27.27 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 0.0004 foot/foot in a northeasterly direction. This result is consistent with historical groundwater flow and gradient data. 2.2 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 in these wells. i6- 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 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). '' 4