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i <br /> 1 . 0 INTRODUCTION <br /> This submittal presents Aqua Science -Engineers, Inc. (ASE)'s workplan to <br /> conduct . an ozone sparging pilot test for interim remediation at the <br /> Unocal Service Station located at 574 West Grant Line Road in Tracy, <br /> California (Figures 1 and 2). This workplan was prepared on behalf of Mr. <br /> Satnam Singh, owner of the .property, as required by the San Joaquin <br /> County Public Health Services, Environmental Health Division (PHS-EHD) <br /> 1 in their undated directive letter (Appendix A). <br /> 2 . 0 BRIEF SITE HISTORY AND BACKGROUND INFORMATION <br /> This workplan was prepared as a supplement to ASE's corrective action <br /> plan (CAP) dated January 16, 2002. ASE's rational for the=selection of <br /> k ozone sparging as the preferred remediation strategy is detailed in the <br /> CAP. <br />$ 3 . 0 PURPOSE OF PILOT STUDY <br /> The purpose of this pilot study is to determine the effectiveness of ozone <br /> sparging as a remediation alternative at the site. The most significant <br /> groundwater contamination at the site is in the western portion of the site <br /> in the vicinity of monitoring well MW-1 and the former., underground <br /> storage tanks (USTs). Groundwater contamination is also 'present in the <br /> northern portion of the site in, the vicinity of monitoring well MW-5. <br /> ` Groundwater contamination in this area, however, has been decreasing <br /> and this area will not receive treatment during this pilot:. study. If the <br /> ozone sparging is proven effective during this study and hydrocarbon <br /> contamination in the northern portion of the site - needs active <br /> remediation at the conclusion of this pilot study, then ozone sparging <br /> could be expanded to this area as needed. <br /> 4 . 0 OZONE SPARGING DESCRIPTION <br /> Ozone sparging is the process of adding an ozone/air mixture into a <br /> water-bearing zone contaminated with organic compounds. The ozone <br /> acts as an oxidant, which will destroy organic hydrocarbons. Ozone can <br /> oxidize contaminants either directly. or through the formation of hydroxyl <br /> radicals. In situ decomposition of ozone can also leadl to beneficial <br /> oxygenation and biostimulation. In- addition, since a gas is injected, it may <br /> be possible for some remediation .to also take place in the vadose. zone as <br /> well. <br /> Singh's Unocal 'Remedial Action flan — March 2002 <br />