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' '12 March 1999 AGE-NC Project No 95-0121 Page 6 of'7 n 3 3 LABORATORY RESULTS OF GROUND WATER SAMPLES ` A total,of nine ground water samples were submitted to a DHS-certified laboratory in December ' 1998 TPH-g was detected in water samples colledtdd from wells MW-1 through MW-4 and MW-7 7 during the December 1998 sampling event at concentrations ranging to 56,000 micrograms per liter (ug/l) TPH-d was detected in water samples collected from MW-1 through MW-4 and MW-7 at concentrations ranging to 6,400 jcg/l,however,the laboratory reported that the diesel chromatograms for the samples did not have typical diesel characteristics ' BTEX compounds were detected in ground water samples collected from wells MW-1 through MW- 4 and MW-7 at concentrations ranging as high as 13,000,ug/1 (benzene, MW-3) ' MTBE was confirmed in water samples collected from MW-1, MW-2 and MW-5 at concentrations ranging as high as 120 pg/1, no other fuel oxygenates were detected above laboratory reporting limits Analytical results of the ground water samples are summarized in Table 2 The laboratory reports (Castle Analytical Laboratory Reference No 1897 and McCampbell Analytical Inc I D No 99876 through 99883) and chain-of-custody forms are presented in Appendix E 4.0. DISCUSSION AND CONCLUSIONS ' Based upon data collected dunng the December 1998 monitoring, AGE concludes Ground water monitoring data in the area of wells MW-1,MW-2,MW-3, MW-6,MW-71 and ' MW-9 indicated that the ground water flow direction was northeast at a gradient of 0 003 ft/ft,`data collected in the area of wells MW-4, MW-5 and MW-8 indicated that ground water ' flow direction was generally toward the northwest at a gradient of 0 002 ft/#1 Due to the low gradient at the site, slight variations in ground water measurements or changes of recharge/discharge of the local ground water could greatly modify ground water flow ' direction Between the August 1998 and the December 1998 ground water monitoring events, ground " water elevation decreased an average 0 60 feet at the site ' - Ground water was approximately pp tely 14 to 17 feet above the screened intervals in monitoring wells MW-1,MW-2, MW-3 and MW-5, ground water was approximately 7 to 10 feet above the-screen intervals at MW-4, MW-6, MW-7, MW-8 and MW-9 Therefore, samples collected from these wells may not be representative of dissolved petroleum hydrocarbon concentrations in shallow ground water Advanced GeoEnvironmental,Inc f