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W,r yards of visibly contaminated soil were removed from the excavation, which extended to a c'.epth of 18 feet. The objective was to remove soils with petroleum hydrocarbons in concentrations greater than 100 ppm. The extent of volatile organic compounds (VOCs) in soils was estimated, in the field, using on-site field headspace measurements made by McLaren Engineering personnel with an HNu, photoionization detector (PID). Soil samples were ` collected for headspace measurements from the backhoe bucket during the excavation work. Results of the field headspace measurements are presented in Table 1. The excavation was terminated at a depth of approximately 18 feet, where groundwater was encountered. Feur end point soil samples and one water sample were collected from the excavation. Soil samples were taken from all four quadrants of the excavation by lowering the backhoe bucket to approximately 17 feet and removing material from the sidewall of the excavation just above groundwater saturation. The water sample was collected from groundwater which accumulated in the excavation over a period of approximately 45 minutes. It should be noted both sidewall and groundwater samples from the pit were taken from the area below the former tank location and therefore, represent and area of highest fuel hydrocarbon concentration. The soil samples were taken from the capillary fringe, a semi-saturated unit directly above the groundwater table. Relatively high concentrations of petroleum hydrocarbons.detected in soils from .the zone appear to reflect migration through the vadose soils. Groundwater samples taken from the capillary fringe/groundwater table interface in the open excavation are, at best, sem.t-quantitative. Some factors in their semi-qualitative nature may include: volatilization of contaminants from the groundwater surface; adsorbed contaminants on suspended solids from other locations within the excavation; and globules of petroleum hydrocarbon product floating on the groundwater surface. In addition to the excavation sidewall soil samples, two composite soil samples from the excavated soil piles were collected. On-site analysis for TPH by Modified EPA Method 8015 and for aromatic volatile organics by EPA Methods 8020 and 602 were conducted by Enseco Mobile Laboratories. Soil and water samples were analyzed for organic lead content by the Department of Health Services approved method and for total lead concentration by EPA Method 239.1 at the Enseco laboratories South Coast — facility in Garden Grove, California. Enseco Mobile Laboratories and Enseco South Coast Laboratory are both certified by the State of California, Department of Health Services for hazardous waste testing. Results of the April 6, 1989, sampling are presented in Table 2. Laboratory data sheets and chain-of-custody forms for these analyses are included in Appendix I. _- The excavation has not been backfilled pending evaluation of the site assessment wor --as set-forth-herein-.--- SCOPE ere n.SCOPE OF SERVICES The purpose of the Sebastiani Vineyards site assessment investigation was to define, to the extent possible, the lateral and vertical extent of soil and groundwater contamination associated with leakage from the former �. 5