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1 34 7. CONCLUSIONS AND RECOMMENDATIONS This report presents the results and findings of supplemental Site characterization field ' work, file reviews, and analyses conducted by ARCADIS Geraghty and Miller, Inc, on behalf of UNOCAL, between August, 1998 and March, 1999, regarding the former service station number 2859, located at 1665 Pacific Avenue, Stockton, California Additionally, the historical record of data and events regarding the Site has been examined, analyzed, and ' presented The results of a sitewide monitoring event conducted February 4, 1999 are also presented and evaluated Based on the results and discussion presented in the foregoing sections of the report, ' ARCADIS Geraghty&Miller, Inc concludes the following ' • The primary petroleum hydrocarbon sources, relating to the dispensing of gasoline products at the Site, have been removed • Approximately 2,745 pounds (450 gallons) of TPHg and 12 pounds (16 gallons) of benzene have been removed by an SVE pilot study at the Site • The amount of excavated impacted soil removed at the Site is in question ' However, previous consultants report having excavated impacted soil to a depth of approximately 30 feet in the area of the 1988 tank excavation ' • The Site release occurred during some previous time when groundwater levels were lower and groundwater has subsequently risen into the zone of impacted ' soils C Based on the NP-1 data, impacts from the removed surface source and residual ' concentrations in vadose zone soils are not the result of ongoing migration downward and impact to saturated zone soils ' • General water quality in the vicinity of the Site is poor and does not meet California State standards(MCLs)for acceptable drinking water ' • The water sampled in NP-1, 85 to 90 feet bgs, is of clearly different quality than s' that from water sampling points higher in the profile It appears that the water