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3.0 RESULTS <br /> • 3.1 Depth to Groundwater and Groundwater Flow Direction <br /> The depth to groundwater on June 4 was approximately 27 feet below grade, which is <br /> about 2 feet deeper than in March (Table 1) Using the three-point method to contour <br /> these values yields a groundwater elevation (piezometric surface) map with a uniform <br /> gradient of 0 0062 ft/ft sloping to the southeast (Figure 3) This has been the flow <br /> direction in four of the five monitoring events that have taken place since the wells were <br /> installed In the fifth event(first quarter of this year),the gradient was to the northeast <br /> 3.2 Laboratory Results <br /> Hydrocarbon concentrations in JLM-4 have not changed since March, all analytes except <br /> 1,2-DCA were below the detection limit (Table 2) Concentrations of most analytes <br /> increased slightly in JLM-3 and decreased slightly in JLM-5 Hence, overall, most <br /> hydrocarbon concentrations in the dissolved-phase plume are stable The laboratory also <br /> noted that the gasoline is relatively fresh and unmodified, as is the diesel A significant <br /> portion of the TPH-d compounds fall within the transition from gasoline to diesel, <br /> indicating that the lighter hydrocarbons within the gasoline-diesel transition have not <br /> been degraded and the diesel is relatively fresh <br /> 4 0 DISCUSSION AND CONCLUSIONS <br /> i <br /> In the First Quarter 2003 Report, we observed that no petroleum hydrocarbons were <br /> detected in JLM-4, despite the fact that this well was downgradient from the contaminant <br /> plume for the first time since the wells were installed in 2002 Based on this observation, <br /> we speculated that hydrocarbons might be detected in this well during the second quarter <br /> if hydrocarbon migration lags slightly behind changes in groundwater flow direction The <br /> data from the second quarter suggest that this is not the case, no hydrocarbons were <br /> detected in the well, wluch indicates that dissolved hydrocarbons are migrating slowly, if <br /> at all <br /> So far, no obvious concentration trends have emerged in either JLM-3 or JLM-5 (Figure <br /> 4) This is not surprising, because the monitoring period is too short to reveal the long- <br /> term pattern, the contaminant source has been removed, and the hydraulic gradient is <br /> relatively flat Under these conditions, concentrations change slowly and patterns are not <br /> evident during the first year of monitoring <br /> 3 <br />