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. Mr Terry Tardiri January 23, 2003 Page 3 hydrocarbon constituents Laboratory reports for the groundwater samples collected for these sampling events are included as Attachment B Discussion Based on the fourth quarter's data, the groundwater hydraulic gradient remains basically flat, as shown in Figure 2 Analytical constituents for each well from the 4th quarter are shown on Figure 3, and a MTBE isoconcentration map is shown on Figure 4 BTEX BTEX concentrations remained consistent with the previous quarters in all four wells, except for a continued decrease in benzene concentrations in MW-3 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 tunes 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 are below the method reporting limit of 50 µg/L in MW-2 and MW-4 As m 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 TPH-G concentrations in MW-3 remain similar to 3rd quarter 2002 concentrations MTBE In MW-1, MTBE concentrations increased from 50,000 µg/L to 52,000 µg/L MTBE was not detected in MW-2, remained consistent with historical results in MW-3, and increased from 200 µg/L to 380 µg/L in MW-4 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 G feet in the last six months • \\Bcszc0l\Protects\21000\21417\Reports\Final 4th 02gtr doc