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San Joaquin County EHD September 5, 2008 Page 4 of 10 In-Situ Air Spargin¢Well Installation and Soil Sampling Ground Zero will supervise the installation of one (1) air sparging well at the Site. The boring (ASW 1) will be advanced to a total depth of 75 feet bgs. A depth of 75 feet bgs will insure that the screen interval of the well remains below the water table. The ASW will be spaced approximately five feet southeast of VEW 1 as shown on Figure 3. V&W will advance the boring using a drilling rig equipped with eight-inch diameter hollow stem augers. Soil samples will be collected from ASW1 at 5-foot intervals beginning at 55 feet bgs for deeper soils classification, subjective analysis for contamination with a PID, and possible laboratory analysis. The completed borehole will be converted into in-situ air sparging well (ASW 1). The ASW will be completed using 2-inch diameter schedule 40 PVC blank casing from surface to the screened interval consisting of 5 feet of 0.020-inch slotted screen set from 70 to 75 feet bgs. A filter pack consisting of No. 3 sand will be emplaced from total depth to two feet above the top of the screen interval. The remaining annulus will be completed with two feet of hydrated bentonite pellets overlain by neat cement grout to the ground surface. The well top will be fitted with a locking cap and covered with a traffic rated well box. No sooner than 48 hours after completion the well will be developed by mechanical surging and bailing methods. An air sparging well diagram is included as Figure 5. Up to two soil samples from ASW1 will be submitted for laboratory analysis. Soil samples will be collected in brass tubes, sealed with Teflon® sheets and plastic caps, uniquely labeled, temporarily stored on ice in an ice chest cooled to approximately 4°C, and will be delivered under chain of custody protocol to Argon Laboratories. Soil samples will be analyzed for TPHg using EPA method 8015M, BTEX via EPA method 8021B, and gasoline oxygenate additives, including 1,2- DCA and EDB by EPA method 8260B. Observation Well Installation Ground Zero will supervise the installation of three (3) observation wells at the Site. Two of the borings (OWI and OW2) will be advanced to a total depth of 25 feet bgs and the remaining boring (OW3) will be advanced to a total depth of 60 feet bgs. OWI and OW2 will be spaced 10 feet and 25 feet southwest of VEW2 and OW3 will be placed approximately 25 feet southwest of VEW1 as shown on Figure 3. These locations complete a set of observation points necessary to determine the radius of influence of both vapor extraction and air sparging activities. Tables 1 and 2 are field logs showing the configuration of observation wells that will be used during the vapor extraction portion of the pilot test and Table 3 shows the configuration of observation wells that will be used during GAGROUNDMHARRYS AUTO\Reports\Workplans\wp sve pilot test.doc