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08 July 2002 <br /> AGE-NC Project No 95-0167 <br /> ' Page 3 of 4 <br /> 3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES <br /> TPH-g was detected in the water samples collected from monitoring wells MW-1 and MW-2 at <br /> ' concentrations of 18,000 micrograms per liter (µg/1) and 880 µg/1, respectively <br /> BTEX compounds were detected in the water samples collected from monitoring wells MW-1 and <br /> MW-2, the highest concentrations were detected in the sample from MW-1 at 2,300 µg/1 benzene, <br /> 2,200 µg/1 toluene, 420 µg/1 ethylbenzene and 2,100 µg/1 xylenes MTBE was detected by EPA <br /> Method 8260B in sample MW-1 at a concentration of 50 µg/l No other oxygenates were detected <br /> ' in the ground water samples <br /> Analytical results of water samples collected in May 2002 are summarized on Tables 2 and 3 The <br /> laboratory report(CTEL LaboratorylDs 0206-005-1 through 0206-005-6),QA/QC report and chain- <br /> of-custody form are included in Appendix B Figure 4 depicts the estimated areal distributions of <br /> ' impacted ground water containing TPH-g and benzene for 31 May 2002 <br /> ' 4.0. SUMMARY AND CONCLUSIONS <br /> Data collected at the site indicates that <br /> ' • The ground water flow direction during this monitoring event was toward the north- <br /> northwest at an average gradient of 0 02 ft/ft Ground water flow at the site has historically <br /> been towards the northwest Ground water flow direction is not well defined south of the <br /> former UST pit <br /> • Relatively high concentrations of TPH-g and BTEX occur in ground water in the area of <br /> ' monitoring wells MW-1 and MW-2 <br /> • MTBE was present in monitoring well MW-1 at a concentration of 50 µg/1 <br /> • The contaminant plume appeared to be confined to the general area of the former UST <br /> location and MW-1 and MW-2 Petroleum hydrocarbons were not detected in perimeter <br />' wells MW-3, MW-4, MW-5 and MW-6 In addition, petroleum hydrocarbons were not <br /> detected in a grab ground water sample collected and analyzed in April 1997 from soil boring <br /> P4, south of the former UST location <br /> 1 <br /> • <br />' Advanced Geo Environmental,Inc <br />