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I <br /> (or comparable). DRAFT <br />' 4.2.1 Sparging System Location <br /> The blower unit will be assimilated with the VES; hence the blower will draw power from <br />' the operating VES. <br /> A one-inch diameter PVC pipe will carry the air from the blower to the sparging wells. The <br /> ' piping will be installed beneath the ground surface. <br /> ' 4.2.2 'Sparging Wells <br /> None of the present wells at the site are suitable for air sparging. Therefore, two sparging <br /> wells will be installed at the site. We estimate that these wells could create a cone of <br /> influence 40 to 60 feet in diameter at the air-water interface (55 feet). <br /> One well will be installed northeast of RW-1, between MW-1 and MW-4; the second <br /> sparging well will be installed west of RW-1 near the back wall of the Art &Artists building. <br /> The approximate locations for the sparging well are illustrated in Figure 6. A work plan for <br /> ' the installation of the sparging wells is included in Appendix D. The well design is included <br /> with the work plan. Permission will be obtained from the City of Lodi to construct a shallow <br /> ditch for the installation of the blower piping. <br /> 4.2.3 Monitoring <br /> A regular quarterly monitoring program will be continued throughout the remediation <br /> period, including sampling of all monitoring wells. However, for the first quarter after <br /> initiation of remediation, we recommend monthly monitoring of the wells for groundwater <br /> ' depth and organic vapors to determine if groundwater mounding or lateral spread of <br /> hydrocarbons is occurring. <br /> ' Since four monitoring wells (MW-5 through MW-8) are located on the edge or completely <br /> outside the impacted area, we do not believe it will be necessary to collect weekly or <br /> monthly groundwater samples for laboratory analysis. Quarterly samples of these wells <br /> ' should provide sufficient information on any possible migration of the hydrocarbon plume. <br /> No other monitoring is scheduled for the site at this time. <br /> ' 43 Estimated Clean-up Time <br /> Air sparging in highly permeable aquifers generally results in rapid reduction of hydrocarbon <br /> ' concentrations in the saturated zone.The length of time for groundwater clean-up if difficult <br /> to estimate. However, data in the PAR suggests that groundwater remediation could be <br /> accomplished within 6 to 12 months. <br /> ' asn MP/7-M-47 10 <br /> 1 <br />