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05 March 2001 <br /> AGE-NC Project No 99-0592 <br /> Page 3 of 4 4 <br /> 1 <br /> detected in the MW-1 sample at concentrations of 1 0 gg/l, 1 3 µg/l and 0 64 pg/l,respectively The <br />' fuel additives MTBE and 1,2-DCA were detected at concentrations of 9 7 µg/1 and 22 pgg/l, <br /> respectively, in sample MW-1 None of the target analytes were detected in samples_collected from <br /> monitoring wells MW-2, MW-3 and MW-4 and the active domestic well DW-1 <br />' Analytical results for the ground water samples for the February 2001 monitoring event are <br /> summarized on Tables 3 and 4 The laboratory report (MAT Lab IDs 90166 through 90170 and <br />' 90303), QA/QC and chain-of-custody are included in Appendix B <br />' 4.0. SUMMARY AND CONCLUSIONS <br />' Based on the findings from this investigation, AGE concludes <br /> • Ground water at the site was inferred to be flowing toward the east-northeast at an average <br />' gradient of 0 001 ft/ft, although at such a low gradient small measurement errors can <br /> significantly affect the inferred flow direction <br /> • Various petroleum hydrocarbon constituents were detected in the ground water sample <br /> collected from monitoring well MW-1, including TPH-g, TPH-d, benzene, toluene, total <br /> xylenes,MTBE and 1,2-DCA The detected concentrations of benzene and 1,2-DCA exceed <br /> the respective DHS Maximum Contaminant Levels (MCLs) The detected concentration of <br /> MTBE is below the primary MCL, but above the secondary MCL <br /> • Petroleum hydrocarbon-impacted ground water appears to be limited to the area near <br /> monitoring well MW-l None of the target analytes were detected in samples collected from <br /> MW-2, MW-3, MW-4 and DW-1 <br /> 5.0. RECOMMENDATIONS <br /> AGE recommends continued quarterly monitoring of ground water monitoring wells MW-1,MW-2, <br /> MW-3 and MW-4 and the on-site domestic well DW=l The next monitoring event is scheduled for <br /> June 2002 <br /> 6.0. LIMITATIONS <br /> Our professional services were performed using that degree of care and skill ordinarily exercised by <br /> environmental consultants practicing in this or similar localities The findings were based upon <br /> analytical results provided by an independent laboratory Evaluation ofthe hydrogeologic conditions <br /> at the site for the purpose of this investigation was made from a limited number of available data <br /> Advanced GeoEnviron mental,Inc <br />■ II <br />