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gallons of water from each well, to stabilize temperature, pH and <br /> conductivity (Table 1) . The purge water was placed in DOT-approved <br /> drums and stored on-site. <br />' 3.2 Sample Collection and Analysis <br /> Water samples were collected from each well using new disposable <br /> plastic bailers. Three 40 ml EPA vials of water were collected from <br /> each well and transported in a chilled container to WEST <br /> Laboratories in Davis. Each sample was analyzed for total petroleum <br /> hydrocarbons (TPH as gasoline) and volatile aromatics (BTE&X) in <br /> accordance with EPA methods 8015m and 602 . <br /> 4 . 0 FINDINGS <br /> 4 . 1 Groundwater Elevation <br />' The relative groundwater elevations for the monitoring wells were <br /> calculated by subtracting the water depth from the casing elevation <br /> (Table 2) . Comparison of the March and June measurements indicates <br /> that water levels have risen approximately 2 to 2 1/2 feet in all <br /> wells. This rise in water levels is probably due to groundwater <br /> recharge since the onset of the rainy season. <br /> 4.2 Groundwater Flow Direction and Gradient <br /> Based on depth to groundwater measurements, the hydraulic gradient <br /> was calculated to be 0. 0025 ft/ft directed S 700E. (Figure 3) . <br /> This is a shallower than the previous gradient of 0. 0073 ft/ft and <br /> directed 770 farther towards the east. <br /> I4 .3 Laboratory Results <br /> No petroleum hydrocarbons were detected in any of the samples. The <br /> water sample analyses are summarized in Table 3 . The laboratory <br /> results and chain of custody are attached in Appendix A. <br /> 5. 0 CONCLUSIONS & RECOMMENDATIONS <br /> Low levels of benzene and xylene were detected in the March 1993 <br /> sampling event, but no contamination was detected in the June <br /> sampling event. It appears that natural processes have resulted in <br /> mitigation of the groundwater contamination that was detected in <br /> June and September Therefore, we do not recommend the installation <br /> of an additional monitoring well . We recommend that the wells be <br /> resampled in September to confirm the results obtained in the June <br /> quarterly monitoring. <br /> I 3 <br />