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before sampling (Appendix A) . <br /> Water samples were collected in disposable plastic bailers and <br /> placed in sterilized 40-m1 vials and 1-liter amber bottles . The <br /> samples were placed in a plastic cooler and iced. They were <br /> delivered on July 10 to Alpha Laboratories in Ukiah, California for <br /> analysis . The samples were analyzed for TPH--gasoline, TPH-diesel, <br /> and BTEX. <br /> 4 .0 RESULTS <br /> 4 . 1 Groundwater Gradient and Flow Direction <br /> Depth-to-groundwater measurements and calculated groundwater <br /> elevations are presented in Table 1 . Results from previous <br /> monitoring events are included for comparison. <br /> The piezometric surface has continued to rise since September, when <br /> the average elevation was more than 50 feet below mean sea level. <br /> At the present time, the elevation is less than 40 feet below sea <br /> level, and the depth to groundwater is between 66 and 68 feet. This <br /> rise is due to the unusually abundant precipitation earlier this <br /> year, and water is now approximately 8 feet above the top of the <br /> screened casing in all wells . <br />. As in previous quarters, the elevation of the water table is <br /> essentially the same in all wells . Therefore, neither the gradient <br /> nor flow direction can be ascertained with certainty, although it <br /> appears that the present flow direction is slightly east of south <br /> (Figure 3 ) . <br /> 4 .2 Groundwater Contamination <br /> No hydrocarbons were detected in any of the groundwater samples <br /> that were obtained in July (Table 2 and Appendix B) . This is not <br /> surprising, and in the previous quarterly report we predicted that <br /> "a further rise in water level could result in an apparent decrease <br /> in groundwater contamination, as contaminants are carried above the <br /> screened interval" . The July samples were collected at a depth of <br /> 8 feet below the soil/water interface, below the contaminated zone. <br /> Only when the water table drops below the top of the screened <br /> interval will it be possible to obtain valid water samples . Several <br /> months will probably pass before the water table drops the required <br /> 8 feet. <br /> 5 .0 CONCLUSIONS AND RECOMMENDATIONS <br /> Groundwater samples will yield invalid results until the water <br /> table drops to a depth of 75 feet or greater. This is not likely to <br /> happen until the fourth quarter of 1995 . Therefore, Upgradient <br /> 3 <br />