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' 20 October 2003 <br /> • AGE-NC Project No 95-0185 <br />' Page 5 of 6 <br /> Jun�03 <br /> TPH-d was detected in ground water samples MWA and MW-4 at concentrations of 1,300,000 µg/1 <br /> and 1,200,000 µg/l, respectively TPH-g was detected in ground water samples MW-1 and MW-4 <br /> at concentrations of 1,400 µg/1 and 6,300 µg/l,respectively <br /> No other target analytes were detected in the analyzed samples Current and previous analytical <br /> results are summarized in Tables 3 and 4 The laboratory report (CTEL Laboratory I D Nos <br /> 0305071 and 0306127), quality control and quality assurance data(QA/QC) and chain-of-custody j <br /> form are Included in Appendix C <br /> 4.0. CONCLUSIONS <br /> I <br />' Based on the data collected during this monitoring period, AGE concludes <br /> • Ground water flow during the May and June 2003 ground water monitoring event was <br /> inferred to be northeast at a gradient of approximately 0 0005 to 0 02 ft/ft at the former UST <br /> area, and west-southwest at a gradient of 0 0004 to 0 008 ft/ft in the area encompassed by <br /> wells MW-2, MW-3 and MW-5 Due to the low ground water gradients at the site and the <br /> operation of the ozone-sparging system, small variations in ground water measurements <br /> could modify the inferred ground water flow direction <br /> • Ozone readily degrades to oxygen, the effectiveness of subsurface ozone infection was j <br />' correlated to elevated dissolved oxygen concentrations detected in monitoring wells add scent <br /> to ozone-sparging wells <br /> • The concentrations of TPH-d and TPH-g rapidly increased between May and June 2003 in <br /> wells MW-1 and MW-4,however,neither TPH-d nor TPH-g were detected in wells MW-2, <br /> MW-3 and MW-5 during this period The rapid increases in TPH-d and TPH-g are attributed <br /> to ozone sp arging-induced re-mobilization and migration of the adsorbed petroleum <br /> hydrocarbons in the sail <br /> • Low concentrations of the BTEX compounds benzene and toluene were detected only in well <br />' MW-1, at 5 2 µg/1 and 6 4 µg/l, respectively, during June 2003 <br /> • Free product has been present in wells MWA and MW-4 since the June 2002 ground water <br /> monitoring event <br /> 1 <br /> 1 � - <br />' Advanced GeoEnvironmental,Inc <br />