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2. I AND ANALYSIS 0 GROUNDWATER MONITORING, SAMPLING ' On May 20, 1999, Ramage Environmental monitored and sampled groundwater at the site 2.1 Groundwater Monitoring ' Depth-to-groundwater measurements were taken in six groundwater monitoring wells to evaluate groundwater flow and gradient characteristics Depth-to-groundwater measurements were not taken from MW-1 and the two deep sod vapor extraction wells (VW-1 and VW-2), because their wellhead elevations were moved during the installation of the sod vapor extraction and air sparging system The depth-to-groundwater beneath the site ranged from 33 89 feet below ground surface (bgs) in MW-4 to 37 58 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 19 28 feet below mean sea level (MSL) in MW-3 to a low of 19 38 feet below MSL in MW-5 Groundwater levels have risen an average of 1 77 feet, since groundwater levels were last measured on February 18, 1999 In the past year, groundwater levels have risen an average of 4 52 feet Since May 1992, the groundwater levels have nsen an average of 29 91 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 0 001 foottfoot 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 sod 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 r Each of the four wells (MW-6, MW-7, VW-1 and VW-2) was purged of at least three well �i 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 ran iced cooler for transport under chain-of-custody documentation to Kiff Analytical, LLC (Kiff) a state of California certified analytical laboratory(#2236) 4