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5� <br /> • <br /> TPHG and BTEX concentrations on the site and historically observed fluctuations have been interpreted as local <br /> contammant drainage and desorption from aquifer sediment Monitoring was not possible in the "core" area of the <br /> historically observed highest concentration dissolved plume this quarter A small dissolved plume is present roughly <br /> centered on Wells MW-2 and MW-5 (see Figures 2 and 3) Well MW-2 has historically shown a dissolved presence <br /> Weil MW-5 has not shown contaminant presence The currently observed contaminant presence in Well MW-5 is <br /> interpreted arising from the disturbance due to the nearby soil and groundwater removal that caused localized <br /> contammant desorbtion and movement <br /> Conclusions and Recommendations <br /> Wright sampled seven monitoring wells this quarter Groundwater flow direction was northerly under a low <br /> calculated gradient and water levels in monitoring wells had declined about 0 2-0 3 feet since the previous quarter <br /> Wells MW-3 and MW-9 were not available for monitoring and the site quarterly monitoring occurred after <br /> contaminated soil removal TPHG contaminants observed in MW-6 anse upgradlent from an off-site source <br /> The historically observed "core" dissolved plume had been centered on MW-3 and MW-9 Soil excavation has <br /> removed contaminated soil in this area A small dissolved plume is observed around MW-2 (that has historically <br /> displayed dissolved contaminants) and MW-5 this quarter Well MW-5 has historically not displayed dissolved <br /> contaminants, and this current presence at MW-5 is attributed to the localized effects of soil excavation causing <br /> desorbtion and migration into groundwater <br /> Wright has completed the soil excavation work to remove contaminated soil in the vicinity of MW-3 and MW-9 and <br /> downgradient of the former underground tank pit (and some groundwater dewatering removal and treatment as <br /> needed for the excavation required) Wright had abandoned Wells MW-3 and MW-9 for the work under approved <br /> SJC/EHD permits These two monitoring wells will be re-installed at approximately their original locations pending <br /> SJC/EHD approval to monitor the "core" plume area A report of the soil excavation and disposal work will be <br /> prepared under a separate cover and submitted to SJC/EHD <br /> The site is scheduled for continued quarterly monitoring at this time <br /> i <br /> Page 3 of 4 <br />