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After purging, water samples were collected with a disposable plastic bailer and placed in 40-m1 Vials. The vials were labeled and logged and placed in a cooled ice chest for later transport to Sequoia Analytical Laboratory. The laboratory report and chain of custody form are in Appendix B. 4.0 RESULTS 4.1 Depth to Groundwater and Hydraulic Gradient The static water level fell by almost 3 feet during the third quarter, and the depth to groundwater now averages more than 10.5 feet. This rapid drop is almost as great as the drop that occurred during the third quarter of 1998 (Table 1). The data in Table 1 were used to contour the piezometric surface and interpret the groundwater flow direction, which are illustrated in Figure 3. The piezometric surface slopes southwestward except along the eastern margin of the site, where the gradient appears to be more westward. The gradient is relatively flat (0.00045 ft/ft) in the central portion of the site, but appears to be steeper to the east (0.0015 ft/ft). This is probably due to the rapid drop in the static water level during the quarter. The static water level in KF-6 and KF-7 is probably slightly above the piezometric surface because these wells are small-diameter piezometers that bottom within the upper silt layer that underlies the site and do not reach the underlying aquifer sand. As a result, they are slower to equilibrate with the piezometric surface after changes in the water depth. Given more time, the water level will probably recede in both wells, which will reduce the hydraulic gradient in the eastern part of the map area. 4.2 Analyticai Rcsu!ts The water samples were analyzed for Total Petroleum Hydrocarbons as gasoline and for volatile aromatic hydrocarbons (benzene, toluene, ethylbenzene, and xylene). The results are shown in Table 2. Samples from most of the wells continue to be below detection limits for all analytes. Several of the wells have now been free of hydrocarbons for more than a year. More importantly, contaminant concentrations in both KF-3 and KF-5 declined appreciably during the quarter. Gasoline (TPH-g) was below the 50 parts-per-billion (ppb) detection limit.in KF-3 for the first time since the third quarter of last year, and benzene was also at its lowest concentration (51 ppb) since that time. In KF-5, TPH-g and benzene declined by nearly 90%, although toluene and xylene rose above the detection limit to 0.93 and 2.1 ppb, respectively. The results confirm that groundwater quality beneath the site is continuing to improve. 3