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� 1 In order to address the soil vapor issue Wright has prepared this Soil Vapor Workplan for collecting soil vapor samples at the Delta site. The following text and attached figures show our proposed sampling locations and a summary of the field sampling protocol. 1.0 Soil Vapor Sampling Workplan T''ie work tasks Wright currently plans for the subject soil vapor sampling program are as follows: 1.1 Proposed Sampling Locations Three-planned sampling locations will be marked (see Figures 1 and 2)after scanning the spots for live underground utilities with a private locator as warranted. We will also mark the street curb and/or sidewalk for Underground Service Alert and call them as required for all subsurface activities. Note that two sampling points will adjacent to the existing groundwater monitoring (MW-2 and MW-3) in the sidewalk. Since Wright has not been allowed access onto the Delta property, the soil vapor sampling points will be installed in the sidewalk at the Delta property line in protected surface vault boxes. 1.2 Temporary Soil Vapor Well Installation The three proposed borings will be completed to approximately 5 feet below ground surface (bgs) utilizing a hand auger and a 3-inch diameter auger bit (see Figure 1). Permits will be obtained from the San Joaquin County EHD as required for the installation and removal of the temporary soil vapor wells. The cored hole and upper boring will be completed sufficient in size as to accommodate a protective vault box of between 4- and 6-inch diameter if necessary. Soil recovered from the driven rods or the hand augured boring will be logged, placed in sealed waste containers, labeled and properly disposed. A Professional Geologist will log the soil borings for each soil vapor sampling point. Representative soil will be retained from two of the holes in order to conduct physical property testing. Tre temporary soil vapor wells will then be installed as follows: A stainless steel vapor point will be installed by placing approximately 2- to 6-inches of sand via tremie pipe then; utilizing a tremie, place the expendable vapor tip affixed to Teflon"' tubing on the sand. Additional sand will then be placed via tremie (if nezessary) to create approximately a 1-foot sand pack interval around the vapor tip as the tremie hosting the TeflonTM tubing is withdrawn. The surface seal will consist of approximately 1-foot of dry granular bentonite overlain by a 50/50 mixture of hydrated granular bentonite to the surface or the bottom of the vault box if installed. A vapor tight Swagelok valve in the off position will be affixed to the top of the Teflon tubing(see well completion details are presented on Figure 2). The wells will then be protected from tampering during equilibration by the installation of surface-mount 4-inch or 6-inch diameter vault boxes placed into concrete into the sidewalk. Upon completion of soil Page 2 of 8