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4 0 RESULTS 4.1 Depth to Groundwater and Hydraulic Gradient The depth to groundwater on January 12 was botween 35 and 36 feet, which is about mid-way between the depths measured in June and November of 2005 (Table 1) The calculated elevation of the water table is approximately 20 feet below sea level in VM-7, deepening to 20 4 feet in VM-6 Figure 3 illustrates the shape of the water table and general direction of groundwater flow The contour pattern is very similar to Figure 3 in the Fourth Quarter 2005 Report, indicating little or no change in the piezometric surface or hydraulic gradient The eastward groundwater flow direction at this site has been amazingly consistent over the long term 4.2 Analytical Results P Petroleum hydrocarbons in the diesel range were detected in VM-I and VM-2 (Table 2), but in both cases the laboratory noted that the chromatogram did not match the diesel standard and the result was dine to overlap from the gasoline range (Appendix B) It now appears clear that diesel fuel is not a contaminant of concern at this site The same is true for fuel oxygenates, ethylene dibromide (EDB), and 1,2-dichloroethane (1.2-DCA) none were detected-in any of the wells (Table 3) In the Fourth Quarter 2005 Report, we reported that hydrocarbon concentrations in the gasoline range declined by at least 35% in most wells-during 2005, and in some wells the decline was much larger In January, the concentration increased in VM-3 and VM-6, but declined in VNI-1, VM-4, and VM-7 In VM-2. the TPH-g concentration of 29,400 ppb was still lower than in most previous quarters but higher than the 184 ppb that had been reported in Novembei That result is undoubtedly erroneous, but the source of the error is unknown Figure 4 contours the TPH-g values to illustrate the extent,of the contamination Whether the contaminant plume extends to the southwest across Grant Street is unknown, because there are no wells on the west side of that street As in the fourth quarter of 2005, the laboratory reported that in some wells the TPH-g concentration was due to a single analyte Because none of the gasoline oxygenates was detected by EPA method 8260 and the BTEX concentrations were low, it is unlikely that the single compound detected by EPA method 8015 was a normal constituent of gasoline One of the halogenated hydrocarbons, such as trichloroethylene or vinyl chloride is a more likely candidate Both were detected several years ago by EPA method 8010 In the fourth quarter of 2005, the laboratory ieported that the total lead concentration m as below the detection limit(10 ppb) in all well-, This quarter, the lead concentration was surpris;ugly elevated in several wells, ranging from 43 2 ppb in VM-7 to 81 3 ppb in VM-3 (Appendix B) Figure 5 1s an isocontour map of dissolved lead, and it appears that the highest concentrations are located in the central portion of the site southeast of the former dispenser island However, the