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' l ti <br /> 08 June 2001 <br /> ' . AGE-NC Project No 95-0103 <br /> ' Page 3 of 4 <br /> ' Benzene was detected in four of the water samples (samples MWA, MW-3, MW-4 and VE-6) at <br /> concentrations ranging from 53 gg/l in well MW-3 to 2,600 µg11 zn well MW-4 The remaining <br /> BTEX compounds (toluene, ethylbenzene and xylenes) were detected in samples MW-1, MW-2, <br /> ' MW-3, MW-4, MW-5, MW-6 and VE-6, with the highest concentrations occurring in samples <br /> MW-4 and VE-6 <br /> ' MTBE was detected in the water samples from well MW-1 and MW-3 at concentrations of 23 gg/l <br /> and 12 gg/l,respectively DIPE was detected in samples MW-3,MW-5 and VW-6 at concentrations <br /> as high as 31 gg/l TBA was detected in samples MW-1 and VE-6 at 44 gg/l and 41 gg/l, <br /> ' respectively <br /> The analytical results of current and previous monitoring well samples are summarized in Tables 2 <br /> and 3 The laboratory report of the current ground water sampling data(MAT Lab IDs 66937 through <br /> 66943),quality assurance and quality control(QA/QC)data and chain-of-custody form are included <br /> in Appendix B <br /> t , <br /> 4.0. DISCUS SIONICONCLUSIONS <br /> Based on the analytical results from this investigation, AGE concludes the following <br /> ' The relative ground water elevation at the site increased 1 41'feet since the last monitoring <br /> event in November 2000 The map of ground water contours indicates a convergent ground <br /> ' water flow direction toward the southeast to east <br /> • Ground water levels in monitoring wells MW-1, MW-2, MW-3 and MW-4 were <br /> approximately three to five feet above the top of the screened interval,potentially reducing <br /> ' the effectiveness of these ground water monitoring wells to characterize the dissolved-phase <br /> 'hydrocarbon plume in the shallowest ground water <br /> ' • TPH-g was detected this quarter in MW-1,MW-3, MW-4,MW-5 and VE-6 In general,the <br /> TPH-g concentrations have remained fairly stable when compared to the results from the <br /> November 2000 sampling event, with concentrations decreasing slightly in MW-1, MW-3, <br /> and MW-5 A significant increase of TPH-g concentrations occurred in sample MW-4,with <br /> concentrations rising from 480 gg/l in November 2000 to 12,000 µg11 during this quarter <br /> TPH-g concentrations have significantly fluctuated in MW-4 since monitoring began in <br /> ' 1994 BTEX compounds show similar trends in these wells <br /> • Fuel oxygenates,including MTBE,DIPE or TBA,were detected in samples MW-1, MW-3, <br /> ' MW-5 and VE-6 The highest oxygenate concentration detected was 44 gg/l TBA in sample <br /> MW-1 <br /> 1 <br /> Advanced GeoEnvironmenta1,Inc <br /> , <br />