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. 3.0 RESULTS 3.1 Depth to Groundwater and Groundwater Flow Direction The depth to groundwater on November 18 was between 28 and 29 feet below grade, which is about 2 feet shallower than in September(Table 1) Using the three-point method to contour these values yields a groundwater•elevation (piezometric surface) map with a uniform gradient of 0 0043 ft/ft (Figure 3), which is slightly steeper than the calculated gradient of 0 0033 ft/ft in September In both quarters, as in six of the past seven quarters, the flow direction has been to the southeast In the fourth event (first quarter of this year), the gradient was to the northeast 3.2 Laboratory Results The MTBE concentration in JLM-4 increased from below the detection limit in September to 13 parts per billion in November(Table 2) Although the concentration is still low, this is a fairly sharp increase that seems rather questionable, especially since MTBE has not previously been detected in this well and other hydrocarbons (1,2-DCA, xylene, and TPH-g) all decreased below detection limits The MTBE concentration might be due to some laboratory error, such as interpretation of the chromatogram Concentrations in JLM-3 were mostly unchanged from September, although the 1 2-DCA concentration doubled from 11 parts per billion to 21 In JLM-5, the TPH-g concentration . doubled and even larger increases were reported in benzene, ethylbenzene, and xylene, but the 1,2-DCA concentration declined by half This lack of consistency in the concentrations of various analytes is rather difficult to explain, particularly when overall concentrations are so low The changes appear to be rather random, and the evidence collected to date suggests that the dissolved-phase plume is fairly stable and is not migrating in any particular direction This is discussed further in the following section 4.0 DISCUSSION AND CONCLUSIONS Figure 4 shows the trend in hydrocarbon concentrations in two of the monitoring wells over the past seven quarters The Total Petroleum Hydrocarbon and Total BTEX curves are strikingly similar for both wells Excluding a 6-month period during the middle of this year, there has been a general decline in concentrations since monitoring began The TPH-g concentration has declined by 94% in JLM-3, and 75% in JL-M-5 The Total BTEX concentration has declined by 87% in JLM-3 and by 82% in JLM-5 In JLM-3, much of that decline took place soon after the well was installed, in JLM-5, the decline has been more steady and gradual These results are encouraging, and if they continue into 2004, it is likely that natural attenuation will result in site cleanup'without the necessity for any active remediation efforts 3