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oil I/UILIfMI Mr. Charles Leubner 20 January 1997 Page 4 Similar procedures were used for collecting soil samples from the stockpiles, except a backhoe was not needed to collect the samples. Excess soil from the core sampler was monitored for the presence of hydrocarbons using a portable organic vapor analyzer (OVA) equipped with a flame ionization detector (FID). This field monitoring was conducted by filling a Ziplock plastic bag approximately one-third capacity with soil. The container was then placed in the sun to promote volatilization of hydrocarbon constituents in the soil sample. The probe of the organic vapor analyzer probe was inserted into the headspace of the plastic bag and the highest concentration was recorded. The results of this monitoring are reported on Table 1. No samples were collected of the stockpiled soil for headspace analysis by the organic vapor analyzer. Pipeline Trench Sampling Seventeen soil samples were also collected from a depth approximately 2 feet below the bottom of the pipeline trench at 20 -foot intervals. This sampling was performed under the direction of Ms. Letitia Briggs of the San Joaquin County Environmental Health Division. The only deviation from the sampling procedures described above was that the liners were driven directly into soil in the backhoe bucket instead of being driven with a corer. Soil samples were also collected for headspace organic vapor monitoring. Results of the headspace monitoring are shown on Table 1. Analytical Results Table 1 summarizes the results of the laboratory analyses of samples collected from the excavation, pipeline trench, and soil stockpiles. All samples were analyzed for Total Petroleum Hydrocarbons as Diesel (TPH-D) by EPA Method 8015 modified, and benzene, toluene, ethylbenzene and xylenes (BTEX) by EPA Method 8020. Tank Excavation Samples When the diesel tanks were removed from the excavation, the excavation floor did not appear to be stained, although a slight sheen was noted in water that was present in the north end of the excavation. This sheen could have been due to hydrocarbons leaking into the excavation from a broken storm drain located near that end of tank. No holes were observed in the walls of the tanks when they were inspected after their removal from the ground. The only staining noted in the excavation was on the western sidewall of the pit dug to collect Sample 597 which was located at the northern end of Tank T7 (see Figure 3). Sample 598 was collected from this stained material and was found to contain diesel at a concentration of 200 mg/Kg.