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CAMBRIA <br /> shut down October 14, 2003 due to a change in the discharge permit conditions The GWE <br /> system was restarted on June 8, 2004 and is currently in operation <br /> Quarterly groundwater monitoring and sampling has been performed at this site since January <br /> 1995 Depth to water in monitoring wells at this site has ranged from approximately 6 to 13 feet <br /> below grade (fbg) and groundwater flow direction has vaned at the site but has predominantly <br /> been either toward the northeast or southwest <br /> June 2004 Site Investigation Recent field activities conducted at the site include dnIling 14 <br /> soil borings and installing one groundwater monitoring well The purpose of the soil borings was <br /> to assess shallow soil impact in the southern portion of the site The monitoring well was <br /> installed to provide further delineation along the western edge of the site The findings of this <br /> investigation will be formally reported in a forthcoming site investigation report/site conceptual <br /> model However the findings of this investigation are used in this overexcavation work plan to <br /> determine the extent of digging for this corrective action measure <br /> WORK PLAN <br /> Technical Rationale for Proposed Scope of Work <br /> • The highest concentrations of gasoline constituents in groundwater beneath this site are <br /> found in the former UST area, near wells MW-5 and RW-lA <br /> • Available soil analytical data (shown on Figure 2) and historical groundwater monitoring <br /> data suggest the southern portion of the site is where the highest levels of petroleum <br /> hydrocarbons have been detected <br /> • After the former USTs were removed and overexcavation was performed (1995), soil <br /> samples collected from the finished excavation contained residual levels of petroleum <br /> hydrocarbons A map and table displaying these data are included in Appendix A <br /> • We have been evaluating groundwater influent data collected from the GWE system and <br /> finding that petroleum hydrocarbon concentrations are declining at a slow rate We <br /> suspect the slow concentration decline may be due to residual petroleum hydrocarbons in <br /> soil in the vicinity of the former UST complex <br /> i <br /> 0783 2 <br />