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Mr Terry Tarditi October 2, 2002 Page 3 Discussion Based on the second and third quarter's data, the groundwater hydraulic gradient remains basically flat, as shown in Figures 2 and 3 Water level elevations are the lowest since records began as shown in Figure 4 i Analytical constituents for each well from the 2nd and 3rd quarters are shown on Figures 5 and 6,respectively BTEX BTEX concentrations remained consistent with the previous quarters in all four wells, except for a continued decrease in benzene concentrations in MW-3 (Figure 7) The reporting limits for all constituent concentrations in MW-1 were increased due to high concentrations of MTBE in the samples The dilutions were necessary because the MTBE concentrations were out of the calibration range for the target analyte Samples from MW-1 were analyzed multiple tines by the analytical laboratory to bring the correct dilution into the calibration range • Therefore, it is difficult to determine if BTEX and TPH-G concentrations in MW- 1 are consistent with previous results TPH-G. TPH-G concentrations remain below the method reporting limit of 50 }ig/L in MW-2, below the increased method reporting limit of 100 µg/L in well MW-4 As in the case of benzene concentrations described above for MW-1, the TPH-G reporting limit was increased to 10,000 µg for TPH-G,which makes it difficult to determine if TPH-G concentrations are present MTBE. In MW-1, MTBE concentrations decreased from 24,000 ptg/L in the 4th quarter 2001 to 14,000 µg/L the 1st quarter and increased to a historical high result of 50,000 µg/L in the 2nd quarter 2002 (Figure 8) MTBE was not detected in MW-2, and remained consistent with historical results in MW-3 and MW-4 (Figure 9) It is not clear why MTBE concentrations in MW-1 elevated so sharply without the elevated concentrations of other BTEX components Groundwater levels have not increased, and in fact have dropped approximately 6 feet in the last six months Figure 10 shows MTBE concentrations and water levels in MW-1 over time Thu report uais prepared in accordance weth the atandardr of the environmental consulting industry at the terve it ww prepared It should not be relied upon hypartees other than those,for whom it Awprepared and then only to the extent of the stops of work which ares anlhorezed They sport does noiguarantee that no additional environmental contamination beyond that descrrhed in they report exislr at the site \\BcsacO2\projects\21000\21417\Reports\2ndand3rd-02gtr doc