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hn KLEINFELDER 1 EXECUTIVE SUMMARY This is a report of Kleinfelder's soil and ground water assessment conducted at the Nor-Cal facility in Stockton, California. In January and March of 1991, Nor-Cal retained a tank removal contractor to remove three underground fuel storage tanks, remove petroleum hydrocarbon impacted soil, and backfill the open tank excavation. In May 1991, an environmental engineering firm installed a single ground water monitoring well through the center of the backfilled excavation. Kleinfelder was retained by Nor-Cal Beverage Company of Sacramento to drill and sample two soil borings through the backfilled excavation and resample the existing monitoring well. Kleinfelder prepared a work plan and obtained boring permits from San Joaquin County to drill and sample the two borings. ' On January 27, 1992, Kleinfelder drilled two soil borings through the backfilled excavation to assess the vertical migration of petroleum hydrocarbon concentrations. The borings were drilled near two areas with previously detected elevated petroleum hydrocarbon concentrations. Three soil samples were analyzed from each boring. Petroleum ' hydrocarbons were not detected in one of the borings and low concentrations were detected in the second boring. Kleinfelder resampled the existing monitoring well in which low concentrations of total petroleum hydrocarbons (TPH) as gasoline and benzene had been previously detected. rThe water sample collected by Kleinfelder did not contain detectable TPH as gasoline, or benzene, toluene, ethylbenzene, and xylenes (BTEX) concentrations. ' Based on the results of the sampling completed by Kleinfelder and review of previous data p g collected at the site, hydrocarbons do not appear to be present at elevated concentrations beneath the bottom of the excavation. The lateral extent of hydrocarbons, if any, beyond the excavation is unknown. However, boring B-1 was drilled at an angle 200 from vertical. The 20, 25 and 40 auger foot samples were collected approximately b, 8 and 13 feet west of - the property fence. Based on the results of these three samples from boring B-1, there does not appear to have been a significant lateral migration of petroleum hydrocarbons at a depth of 20 to 40 feet. Additionally, Kleinfelder does not recommend additional ground water assessment or remediation at this time. FR1-92-15 Page 1 of 21 Copyright 1992 Kleinf0der,Inc.