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55--gallon drums near the vapor extraction unit for later disposal . <br /> After purging, the depth to groundwater was re-measured, and two <br /> 40-m1 sample vials were collected from each well . These were <br /> labelled and placed in a cooled ice chest for later delivery to <br /> Sequoia Analytical in Sacramento. The laboratory report and chain- <br /> of-custody form are .included in Appendix C. <br /> 5 .2 Depth to Groundwater <br /> The seasonal increase in rainfall has resulted in a rise in the <br /> water table of at least a few feet since Upgradient began <br /> monitoring the site (Table 1) . As of mid-February, the average <br /> depth to groundwater was 65 . 7 feet. <br /> 5 .3 Groundwater Gradient and Flow Direction <br /> Figures 6 and 7 show the groundwater gradient and flow direction in <br /> December and February. with only three monitoring points, the <br /> December gradient appears to be a typically uniform southwest- <br /> sloping planar surface, with an inclination of 0 . 001 ft/ft. The <br /> more complete data for February suggest a more complicated picture, <br /> with a central trough trending southwest through the site . This is <br /> a very unusual gradient, such as occurs where groundwater is being <br /> withdrawn from an extraction well . Future monitoring is needed to <br /> verify the February map. <br /> 5 .4 Groundwater Contamination <br /> Prior to February 1994, groundwater samples had not been collected <br /> at this site since the water table receded below the monitoring <br /> wells in late 1990 . As of June 1990, contaminated groundwater had <br /> been sampled in MW-3, MW-5, MW-6, and MW-7, and free-phase gasoline <br /> had been observed in MW-1 (this well was later destroyed) . <br /> Contaminants included TPH-g, all of the BTEX compounds, 1 ,2-DCA, <br /> and ethylene dibromide (in MW-1 only) . <br /> Of the wells sampled in February, MW-5 is the only one that is <br /> presently contaminated. Hydrocarbons in the C6-C12 range (gasoline) <br /> were detected at a concentration of 180 Ag/1, and benzene was <br /> detected at 1 . 6 gg/1 (Table 2 ) . <br /> 6.0 WASTE DISPOSAL <br /> Approximately 330 gallons of fluid were generated during the 1st <br /> quarter of 1995 as a resulr of the operation of the VES and purging <br /> of the groundwater monitoring wells The fluid was stored in 55- <br /> gallon drums near the extraction unit <br /> 6 <br />