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Workplan Addendum for Soil Excavation <br /> PG&E's Stockton Service Center <br /> Project No W4801 00 <br /> Page 2 <br /> SCOPE OF WORK <br /> The following scope of work is based upon the information outlined above <br /> ♦ Prior to further excavation, the former tank pit will be backfilled with self <br /> compacting fill which will be placed in the tank excavation in 12 to 14 inch lifts, <br /> and compacted between lifts (January 12, 1993 and January 27, 1993 sample <br /> analysis confirmed the removal of transformer oil impacted soils from the former <br /> tank area - Table 1) <br /> ♦ Subsequent to backfilling further excavation will be conducted in the former sump <br /> area which is located in the northwest corner of the former tank pit Sample <br /> analysis of soil samples collected after excavation activities on February 10, 1993 <br /> indicated that impacted soil was not completely removed (Attachment 1 contains <br /> the analytical data sheets and chain-of-custody documentation for the February 10, <br /> 1993 sampling) When all impacted soil is estimated to be removed a <br /> confirmation sample will be collected <br /> All field work will be performed under supervision of RESNA personnel in accordance with the <br /> Site Safety Plan (Attachment 2, Workplan for Soil Excavation, November 4, 1992) <br /> Soil Excavation and Sampling Methodology <br /> To prevent residual contaminants in the soil from acting as a source of groundwater degradation, <br /> the soil in the vicinity of the line sump area will be excavated A backhoe will be used to <br /> excavate the area A 40-hour health and safety trained PG&E crew will perform the excavation <br /> It is estimated that 5-10 cubic yards of material will be excavated Excavated soil will be <br /> underlain and covered with plastic sheeting A Photoionization Detector (PTD) will be used <br /> during excavation to assist in evaluating the lateral extent of soil impaction <br /> Following excavation, one or more verification samples will be collected from the excavation <br /> The samples will be collected from the sidewalls and floor of the excavation Exact number and <br /> locations of samples will be determined in the field under the direction of the San Joaquin <br /> County Public Health Services/Environmental Health Division <br /> All venfication soil samples will be collected from the backhoe bucket at least three inches <br /> below the surface of the soil The samples will be collected into prewashed brass liners Each <br /> liner will be sealed with Teflon sheet and plastic caps, sealed in air-tight bags, and preserved <br /> on ice pending shipment to a state-certified laboratory <br /> LETTERSIWPA 0393 FNL <br />