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TABLE 5 RELATIVE GROUNDWATER ELEVATIONS Caldron's General Store 12750 West Byron Road, Tracy, California Relative Depth to Relative Groundwater Well No. Casing Elevation Groundwater Elevation 10-24-94 12-5-94 10-24-94 12-5-94 MW-1 96.36 6.02 5.94 90.34 90.42 MW-2 96.30 5.99 5.92 90.31 90.38 MW-3 97.13 6.59 6.51 90.54 90.62 Measurements in feet 5.0 CONCLUSIONS & RECOMMENDATIONS Petroleum hydrocarbons were detected in soil samples collected at the time of the tank removals. Excavation procedures were performed to remove impacted soil from the area of the former USTs and samples were collected. No petroleum hydrocarbons were detected in these samples, confirming the successful removal of impacted soil. TPH as diesel and motor oil were detected in the soil sample collected from MW-1 at a depth of 5 feet. The laboratory report noted that the TPH as gasoline detected in this sample represented strongly aged gasoline or diesel range compounds. No diesel or motor oil was stored on-site. However,both diesel and motor oil-range hydrocarbons were detected in this sample. The presence of these longer-chained hydrocarbons is most likely due to pipelines that run near the property, and are therefore not related to this investigation or activities conducted on-site. It is our understanding that an investigation relating to these pipelines is currently being conducted east of the site. TPH as gasoline was detected in the sample collected from a depth of 5 feet in MW-3 at '-' a concentration of 3.2 ppm. No petroleum hydrocarbons were detected at a depth of 10 feet in this boring or in groundwater samples collected from this monitoring well. No BTE&X were detected in any of these samples. The presence of these low concentrations of hydrocarbons may be due to a minor surface spill, and do not represent a threat to groundwater. The soil removed from the excavation and stockpiled on-site was treated with a bacteria inoculant. Samples collected from the stockpiles confirm the successful remediation of the stockpiled soil. Omb�.i Audi)s.rvi..1— 16 CALDRONS....~.95