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Geological TechAta Inc Page 4 Groundwater Monitonng Report Pioject No 723 2 Apri] t 8,2003 E Oxygenated Fuel Compounds (MTBE, DIPE, ETBE, TAME & TBA) by method 8260 ' The detection lit-nits for the above analyses are listed in Table 2 of Appendix A, while the lab analytical results are presented in Appendix B ' As required under AB2886, groundwater elevation and laboratory data were submitted electronically to GeoTracker on March 25 & April 16, 2003 - confirmation numbers ' 9218912303 & 6045791447 ' 2.0 FINDINGS AND DISCUSSION The results of the groundwater sample analysis show the following • Review of the historic groundwater elevations show that groundwater levels raised each season from the mid 1990s to spring 2000 and have been decreasing steadily with each seasonal cycle since spring 2000 ' • The concentrations of BTEX and TPH-G continue to fluctuate in individual monitoring wells from one sampling event to the next • Intermediate well MW-101 continues to contain stable TPH-G concentrations, but benzene and toluene concentrations continue to fluctuate at levels dust above the laboratory reporting limits ' • Deep well MW-201 contained xylene at a concentration (0 5 ug/l) dust above the laboratory reporting limit The previously noted contamination is probably a drilling artifact created by the use of mud rotary drilling It is noted that the contaminant ' concentrations in MW-201 have declined by an order of magnitude since the first monitoring event in December 2001, which supports the conclusion that the high concentrations were from a drilling artifact ' • Figure 4 illustrates TPH-G and Benzene concentrations versus elevation in well MW-3, which lies near the core of the plume There appears to be a direct relationship between ' the water table and the TPH-G concentrations Benzene concentrations have stabilized in the well • Figure 5 illustrates TPH-G and Benzene concentrations versus elevation in well MW-4, ' which lies up gradient of the core of the plume The contaminant concentrations have stabilized in this well • Figure 6 illustrates TPH-G and Benzene concentrations versus elevation in deep well MW-101, which lies near the core of the plume The concentrations are approaching stability The steep decline in the initial concentrations suggests that the contaminants detected in the well were initially a drilling artifact The continued presence of the TPH-G suggests that this well is within the plume 1