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24 December 2001 AGE-NC Project No. 97-0327 ' Page 3 of 4 ' 3.2. LABORATORY RESULTS OF GROUND WATER SAMPLES A total of three ground water samples were submitted to a DHS-certified laboratory for analysis for ' TPH-g, TPH-d, BTEX and fuel oxygenated compounds. TPH-g was not detected in water samples collected from MW-1, MW-2 or MW-3; however, TPH-d was detected in water samples collected from wells MW-1 and MW-3 at concentrations of 75 4g/l and 90 ug/l, respectively. 1 Benzene was detected in a water sample collected from well MW-2 at a concentration of 0.66 ug/l. No other BTEX compounds were not detected in ground water samples collected from MW-1, ' MW-2 or MW-3. MTBE was detected(EPA Method 8260) in ground water samples collected from wells MW-1 and MW-2 at concentrations of 1.8 ,ug/l and 4.9 µg11 respectively; TBA was detected in samples collected from wells MW-2 and MW-3 at concentrations of 27 gg/l and 7.9 ug/l, respectively; 1,2-DCA was detected in a sample collected from well MW-1 at a concentration of 6.8 yg/l. No ' other fuel oxygenated compounds were detected by laboratory analysis. Analytical results of the ground water samples are summarized in Tables 2 and 3. The laboratory reports (McCampbell Analytical Laboratory I.D. No. 79168-70) and chain-of-custody forms are presented in Appendix B. ' 4.0. DISCUSSION AND CONCLUSIONS The implications of the findings from the September 2001 ground water monitoring event are as ' follows: • Ground water flow direction at the site was inferred to be toward the south-southeast at a gradient of 0.001 ft/ft or less. • 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. • Ground water elevation decreased approximately 3.24 feet between June 2001 and ' September 2001; decreasing ground water elevations have been observed at the site since May 2000. • Dissolved TPH-d was detected in samples collected from wells MW-1 and MW-3; previously,-the"greatest-TPH-d concentrations have been detected from wells MW-2 and MW-3 while low concentrations have been detected from well MW-1. • Low concentrations of dissolved MTBE were detected in samples collected from MW-1 and MW-2 and 1,2-DCA was detected in a sample collected from.well MW-1 indicating a minor impact to ground water-in the area assessed. ' Minor concentrations of dissolved TBA were detected in samples collected from wells ' Advanced GeoEnvironmental,Inc.