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V RS Ms. Michelle Le San Joaquin County Environmental Health Department February 7,2006 Page 4 and January 3, 2006). Analytical results of the composite samples from the over-excavated soil (SP-13- 14, SP-15-18 and SP-19-22) indicated that GRO was present at a maximum concentration of 620 mg/kg, toluene at 1.5 mg/kg, ethylbenzene at 3.7 mg/kg, and xylenes at 29 mg/kg. Due to the presence of petroleum hydrocarbons, the over-excavated material was hauled off site by Dillard Environmental and disposed of at Forward Landfill in Manteca, California. The soil disposal manifests are presented as Attachment E. Summary of Activities and Findings • Three 12,000-gallon, double-walled fiberglass USTs were removed on December 29, 2005. The tanks were in good condition with no apparent holes or cracks. • Soil in the southwest corner of the UST pit and beneath two of the dispensers was stained and had a strong petroleum odor. • Significant concentrations of petroleum hydrocarbons were identified in UST pit sample PB-3 and dispenser samples DI-1 and DI-4. Benzene was not identified at or above the reporting limit in any of the soil samples collected. Oxygenates/additives were not identified in any of the soil samples, with the exception of one detection of TBA in sample DI-3 (0.039 mg/kg). • Approximately 57 cubic yards of soil from beneath the southwest corner of the former UST complex and two of the dispensers were over-excavated to approximate depths of 21 and 13 feet bgs,respectively. • Over-excavation was discontinued prior to removal of all impacted soil because of equipment limitations and interference from an overhead service canopy. • At the total depth of the tank and dispenser over-excavations, evidence of petroleum hydrocarbons persists. In the tank pit, stained soil with a petroleum odor was still present prior to backfilling. Analytical results of confirmation soil samples collected at the dispenser over-excavation identified concentrations of petroleum hydrocarbons. • Clean stockpiled materials were used as backfill at the site. Stockpiled materials containing petroleum hydrocarbons were hauled off site for proper disposal. CONCLUSIONS Based on the analytical data collected during the above-described fieldwork, detectable concentrations of petroleum hydrocarbons remain in soil near the southwest corner of the UST complex and beneath two of the dispenser areas. Quarterly groundwater monitoring will continue at the site. K:\WprocessU5 BP ARCO\00595\05 UST Removal\UST Removal Rpt.doc