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remediated 527 67 gallons of gasoline at the site A graph showing the <br /> influent air concentration of TPH-G over time is presented in the Graphs <br />. section of this report Only a trace of total xylenes was detected in the <br /> September influent air sample <br /> 7.0 CONCLUSIONS <br /> lsoconcentration contour maps for TPH-G, benzene, and MTBE in the <br /> shallow water-bearing zone are presented as Figures S through 7, <br /> respectively <br /> When compared to the previous quarter, hydrocarbon concentrations have <br /> decreased, or remained near or below laboratory method reporting limits <br /> in all groundwater monitoring wells, with the exception of MTBE in <br /> monitoring well MW-19 which increased slightly Samples collected from <br /> monitoring wells MW-17 and MW-18 contained 590 ppb and 2,300 p p b <br /> TPH-D respectively, neither of which had contained reportable <br /> concentrations when they were last sampled in June 2001 However, the <br /> laboratory noted that the compounds identified as TPH-D did not exhibit a <br /> typical diesel pattern Recovery wells RW-1 though RW-5 were sampled <br /> for the first time since September 2000, and hydrocarbon concentrations <br /> in the groundwater samples collected from them have decreased <br /> significantly, with the exception of TPH-D which increased in RW-2 and j <br /> RW-3 Concentrations in the drinking water well remained below reporting <br /> limits <br /> The TPH-D concentrations in monitoring wells MW-5, MW-13 though <br /> MW-20, and recovery wells RW-1 though RW-4 exceeded the Water <br /> Quality Objectives (WQOs) as listed in RWQCB Cleanup and Abatement <br /> Order #R5-2003-0713 The TPH-G concentrations in MW-13, MW-14, <br /> MW-19 and RW-1 through RW-3 exceeded WQOs MTBE concentrations in <br /> monitoring wells MW-13, MW-14, MW-19 and MW-20, and TBA <br /> concentrations in MW-13, MW-14 and MW-19 and recovery wells RW-1 <br /> and RW-3 exceeded WQOs Additionally, benzene and ethylbenzene <br /> concentrations in MW-19 and the total xylenes concentrations in RWA <br /> exceeded WQOs <br /> It is notable that all BTEX and oxygenate concentrations detected in t h e <br /> onsite wells this quarter were below WQOs, with the exception of TBA in <br /> RWA and RW-3 <br /> Frank's One Stop Quarterly Report — September 2003 Sampling <br /> -5- <br />