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Work Plan,Additional Excavation and Confirmation Sampling Bulk Transportation Facility, Stockton, California Hygienetics Environmental Services,Inc. 16 feet below grade. Brown, silty fine-grained sand was observed at the 16-foot depth in the western portion of the UST excavation. 1.4.2 Ground Water No ground water was observed in the UST excavation in October 2002. Depth to first ground water, therefore, is inferred to be greater than 16 feet below the ground surface. 2.0 PROPOSED WORK Hygienetics proposes overexcavation and confirmation soil sampling at the locations where elevated concentrations of diesel fuel hydrocarbons were detected during UST removal. The work elements are described in the following sections. 2.1 Health and Safety Work will be performed under the existing Health and Safety Plan prepared by Foss for the initial UST removal. This plan will be revised to reflect current site conditions before fieldwork begins. Foss personnel, Hygienetics personnel, and personnel working for subcontractors involved directly in the excavation and sampling work will be briefed on the contents of the plan and will be required to follow the provisions of the plan. A copy of the Health and Safety Plan will be available at the site during fieldwork. 2.2 Overexcavation Foss will further excavate in the area of the diesel fuel pipeline and at the junction of the fuel piping between the two satellite dispensers using a backhoe and hand tools,as appropriate. Excavation will proceed until visual and olfactory evidence indicates soil impacted with petroleum hydrocarbons has been removed. Hygienetics will also use a photoionization detector to check in-situ soil for evidence of petroleum vapor. The excavated soil will be stockpiled on and covered with plastic, pending characterization for proper disposal. 2.3 Soil Sampling When field evidence indicates impacted soil has been removed,Hygienetics will collect soil samples at the base,of the two excavated areas for laboratory analysis. Samples will be collected either directly from the base of the excavations or from soil brought to the surface by the backhoe bucket, depending on the depth of excavation. Any slough material in the excavation and approximately 3 inches of exposed native soil in the backhoe bucket will be removed before sampling. Soil samples will be collected using a slide-hammer sampling tool containing a clean, 2-inch-diameter by 6-inch- long brass sleeve. The sampling tool will be driven into the native soil to collect each sample. On withdrawal, the brass sleeves containing the soil samples will be capped with Teflon sheets and plastic end caps and each end of the sleeves will be wrapped with duct tape. The brass sleeves will be labeled with a unique identifying number, date, and project number and will be placed on ice in a cooler. Hygienetics personnel will prepare a Chain-of-Custody form for the samples and this form will accompany the samples to the laboratory. 3