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,.. 1. INTRODUCTION At the request of ExxonMobil Oil Corporation (ExxonMobil), ETIC Engineering, Inc. (ETIC) has prepared this Air Sparging Pilot Test Work Plan for former Exxon Retail Site (RS) 7-3942, located at 4444 North Pershing Avenue, Stockton, California (Figure 1). This work plan was written in response to a letter from the San Joaquin County Environmental Health Department (SJCEHD) to ExxonMobil dated 3 September 2003 (Appendix A), in which SJCEHD recommended conducting a pilot study to evaluate low flow rate ozone sparging. As discussed on 11 June 2004 with the SJCEHD, this air sparging pilot test will provide preliminary information needed to assess the feasibility of using ozone as a remedial technology at the site. Former Exxon RS 7-3942 is currently a vacant lot located on the southeast comer of the intersection of North Pershing Avenue and Rosemarie Lane (Figure 2). Used oil and three grades of gasoline were stored in four underground storage tanks (USTs), which were removed from the site in July 1986. Land use in the vicinity of the site is primarily commercial and residential. A Shell service station and a 7-Eleven food and gasoline service store are located on the southwest and northwest corners, respectively, of the intersection of North Pershing Avenue and Rosemarie Lane. The Chateau Hospital convalescent home is located approximately 200 feet northwest of the site across Rosemarie Lane. There is an apartment complex to the east of the site and a commercial building to the south. Stagg High School is located approximately 1,500 feet southwest of the site. 2. PURPOSE AND OBJECTIVES OF THE AIR SPARGING PILOT TEST As part of an assessment of ozone sparging as a remedial technology for the site, an air sparging pilot test is proposed. The objective is to provide preliminary information concerning the extent to which a gas can be sparged through the subsurface. The data collected during the air sparging test will be used to assess the sphere of influence of sparging, and the effect sparging may have on groundwater elevations. 3. TEST DURATION AND SCOPE OF WORK Air sparging pilot tests are proposed to be conducted on wells SWl, SW2, RWl, and UVB- MWL During each test, air will be injected into the sparge well for approximately 2 to 3 hours at various rates and pressures. The exact length of these tests will vary depending on field results. The sparging and observation wells anticipated to be used for the air sparging pilot tests are presented in the table below: Air Sparging Wells Observation Wells_ SW1 Vl, V2,V4, and SW2 SW2 Vl, V2, UVB-MWI, and SWI RW1 MW3, V2 UVB-MWI UVB, UVB-MW2, SW2, and MW6 (air) ✓7 P G:Wmjec\s\]3942V.FASTER\tVPWPo]06\WPiex\.tloc 1