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Work Plan Stewart's Beacon Project No.01-17.1.2 —. Marcia 12,1990 Page: 2 moved south of the tank, but bias moved at least S0 feet to the north. Soil contaminati4a has two modes o:dispersal: that migrating out directly from the tares, and that which is dispersed by ground water moverriert. The cross section given in fig=3 shows the contamination distribution. Soil and ground water.analytical data . generated during the preliminay investigation hrs leen su-nunarized in Table.. 2.2 ,summary of Tank Removal Subsequent to this assessment,all three undei7wi d fuel storage tanks were removed by Western Meter Service of Stockton,California on 20 December 1988. Seal and ground water samples were-collected by California Water Labs, Inc. a-3 the detection of Cynthia Wagner of SanJoaquin Local Heaith Department. That data has been summarized in Table 2. Soil excavated during tank closure•was stockpiled on site. 2.3 ]Hlrtory of Site Monitoring The soil excavated during tank closure in Der-ember of W388 was tested for petroleum hydrocarbons. Three samples were collected in January 1990 for each composite sample a=id were collected from the center of the pile by digging dawn with a backhoe. An „ estimated 250 yds-3 was in the stockpileand _eQmpsite samples were analyzed. The analytical data from these samples indicate that no petroleum hydrocarbons occur in ; this material. Copies of the lab reports are given'In Appendix A,samples GT soil 1A,B,C to Gt-18 soil 5A,B,C. During early ranuary 1990,the three monitoring wets were redeveloped,purged,and sampled. These samples were tested for petroleum hydrocarbons and the data is presented in Appendix A, sample number GTI$-MWl to GT18-MW3. Only MWl contained hydrocarbons which are at levels higher then they were in May 1988. However,since we do not have data points between May 1988 and January 1990,it is difficult to put these two data sets in a larger perspective. - A water sample was also collected from the sump that was used to dewater the excavation before the reexcavatlon occurred. That sample was collected after the _ — water in the excavation recharged and had reached equilibrium. its sample number is GTIS sump and is presented in Appendix A. This data shows that the water which recharged the excavation contained very little hydrocarbons. 2A Summary of interim Sall Remediation On 3 January 1990,SE6MO initiated thu soil remedlation work plan by widening and deepening the tank excavation, 'rhe excavation contained ground water to a level of - _ ___�abaut 1D or]i fact belawi�-surfarw:-A dpwawring-process-was-inidated.to-facilitate- -- - -. --- - - :� t the deepening of the excavation In order to access.the contaminated soil. .✓ ,iae�