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' 06 September 2001 <br /> AGE-NC Project No 98-0534 <br />' -Page 3 of 4 <br /> 0 007 feet/feet One well MW-4 ground water elevation out of range with the surrounding wells, <br /> therefore, the data from well MW-4 was not used to the ground water elevation contouring <br /> 3 2 ANALYTICAL RESULT F R <br /> S O GROUND WATER SAMPLES <br /> LES <br /> TPH-g was detected in the ground water samples collected from wells MW-4 and MW-6, at <br /> concentrations of 98 micrograms per liter (µg/1) 53 ug/l, respectively TPH-d was detected in the <br /> samples from wells MW-4 and MW-6 at 120,ug/l and 59 ,tg/l, respectively <br /> Toluene was the only BTEX compound detected in the ground water samples (MW-4 at 0 98 Azgll) <br /> MTBE was detected in the ground water samples from wells MW-3, MW-4, MW-6 and MW-8 at <br /> concentrations of 3 0 E,tg/l, 18 ,ug/l, 190 ,ug/1 and 4 0,ug/l, respectively ETBE was detected at 5 8 <br /> /.tg/l in sample MW-6 TBA was detected at 23 µg/1 in sample MW-6 No other fuel oxygenates were <br /> detected in any of the samples <br /> Laboratory results of water samples analyzed for petroleum hydrocarbons are summarized in Table <br /> Ile 2 The laboratory reports for the quarterly monitoring event (MAI Laboratory ID No 68591 to <br /> 68597) quality assurance and quality control (QA/QC) reports and chain-of-custody form are <br /> included in Appendix B Figure 4 depicts the distribution of the dissolved hydrocarbon benzene and <br /> MTBE <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> Based on the findings from this investigation, AGE concludes <br /> • Ground water on the site was flowing toward the south-southwdst from the former UST area <br /> at a low hydraulic gradient of approximately 0 007 feet/feet <br /> • Dissolved benzene and MTBE in shallow ground water are delineated by the well network <br /> • MTBE was detected in four ground water samples collected, with the highest dissolved <br /> concentration occumng within the former UST area at 200,ug/l The CVRWQCB document <br /> titled A Compilation of Water Quality Goals, August 2000, lists the State of California <br /> Maximum Contaminant Level (MCL) for MTBE in drinking water at 13 µg/1 <br /> Advanced GeoEnvzronmental,Inc <br />