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1.0 INTRODUCTION/PREVIOUS WORK This report is being submitted in response to a request by the San Joaquin County Public Health Services, Environmental Health Division for a subsurface investigation of groundwater contamina- tion at the H. J, Heinz facility, 757 E. 11th Street in Tracy. The subject property is currently occupied by a food prc.cessing company (Figure 1 ) . N J On March 31, 1989, an underground diesel tank was removed from the site. Soil contamination was noted in the sidewalij of the excavation. Soil samples were collected from each wall of the pit. The Laboratory results for the samples are included in Appendix I. Due to elevated concentrations of diesel constitu- ents in the soils, combined with the presence of groundwater at approximately 10 feet observed in the pit, the San Joaquin Local Health District required further assessment of soi.L and groussd- water contamination at the site. On January 18, 1990, pursuant to a workplan dated May 8, 1989, four soil borings (MW1, SB2, SH3 and SB4) were advanced to depths ranging from 7 to 19.5 feet below grade for the purposes of site characterization and the installation of a groundwater monitoring well . The well and former soil boring locations are shown on Figure 2. Soil boring and well completion data are included on the boring/well logs contained in Appendix II. Soil samples were w collected from boreholes (SB-2, SB-3, and SB-4) near the top of the capillary fringe ([d 8 feet below grade) . �" ..a On January 30, 1990, MW1 was monitored and developed in accord- ance with WaterWork's Well Monitoring and Development Protocols , _ (Appendix III ) _ A water sample was collected the same day in accordance with WaterWork's Groundwater Sampling Protocol (Appen- dix III ). The sample was analyzed by H.C. Laboratories for BTXE and TPH as diesel by EPA 8020 and DOHS methods, respectively. Benzene, toluene, ethylbenzene and xylenes were not present above method detection Limits; however, 150 ppb TPHD was recorded in the sample. The results of the investigation were presented in a report dated February 26, 1990. On September 14, 17-21, and 24, 1990, the former tank pit area was excavated with a backhoe to remove as much contaminated soil as possible. The lateral extent of the excavation was 10 feet west and east, 8 feet south and 32 feet north of the former tank pit (Figure 2) . All observable contaminated soil was removed in the east, and west directions. High voltage utilities and light- ing structures prevented complete excavation of all contaminated soils above the water table along the northern and southern boundaries of the excavatio► , However, it is clear that the vast majority of the contaminated soil in the unsaturated zone has been removed. The water table was encountered at a depth of 9. 5 feet below grade. Approximately 800 cubic yards of soil were removed from the pit. Sixteen soil pile composites were collect- {1� N 1