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WORK PLAN ADDENDUM FOR SITE INVESTIGATION Countryside Market 10848 Copperopolis Road Stockton, CA 1 .0 REVISED ASSESSMENT PLAN Stokely Construction of Tracy, California will utilize a rubber- tired backhoe to perform the excavation. We propose to excavate an additional 3 to 5 feet beyond the tank excavation in all directions, which would increase the size of the excavation to as much as 20 feet (north-south) by 21 feet ;(east-west) by 12 .5 feet deep. This would remove approximately 200 cubic yards of soil . At present, we believe that the upper few feet of soil are either uncontaminated native soil or clean backfill, this material will be stockpiled separately from the contaminated soil that lies below the original depth of the excavation (5 feet) . Visquine will be placed beneath the stockpiles to prevent further contamination. During excavation, Upgradient will utilize a portable photo- ionization detector (PID) to screen the soil for organic vapors and then direct the backhoe operator. The soil will be screened frequently to avoid excavating clean soil, if possible. When it appears that the lateral and vertical limits of contamination have been reached, or when site conditions prevent further excavation without the use of additional equipment, excavation will be terminated and at the direction of EHD, soil samples will be collected. Based on the proposed excavation limits, and in accordance with the LUFT Field Manual, we estimate that one sample will be collected from each sidewall and one or two samples will be collected from the floor. The estimated depth to groundwater ,is in excess of 50 feet, and we do not anticipate that water will enter the excavation. Samples will be collected from the backhoe bucket, using a percussion slide hammer loaded with brass samples sleeves . The bottom sleeve will be immediately covered with teflon sheets, capped, labelled, and placed in a cooled ice chest for transmittal to the analytical laboratory. The analytical procedures to, be used are unchanged from the previous workplan. Due to the proximity of the excavation to Copperopolis Road, the excavation will be backfilled with clean fill and/or native soil when excavation is complete. This will reduce the danger to passing vehicular traffic. The contaminated stockpile will be transported under non-hazardous manifest to Remco, Inc. of Richmond, California for disposal.