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I-./ GROUND ZERO ANALYSIS, INC. 1714 Main Street Escaion, California 95320 Telephone: (209)838-9888 Facsimile: (209) 838-9883 April 15, 2003 OR 16 2003 ENV�R �MS�RVICES H Ms. Margaret Lagorio P San Joaquin County Environmental Health Department 304 East Weber Avenue, Third Floor Stockton, CA 95202 Subject: Results of Subsurface Investigation The Record, 530 E. Market Street, Stockton, CA Dear Ms. Lagorio: This letter report is submitted to present the results of the subsurface investigation at the subject site. Figure 1 shows the location of the site. The investigation was conducted to further assess the extent of gasoline constituents detected in soil samples collected beneath the former underground storage tank (UST). BACKGROUND The site previously utilized one 10,000-gallon UST for storage of unleaded gasoline. Figure 2 presents a site plan showing the location of the former UST. The UST was removed under permit from San Joaquin County Environmental Health Department (EHD) on January 14, 2003. A soil sample collected beneath the south end of the UST contained low levels of total xylenes, methyl- tert-butyl-ether (MTBE), and tert-butanol (TBA). Table 1 presents a summary of analytical results. Groundwater beneath the site was expected at approximately 25-30 feet below ground surface (bgs). FIELD METHODS Ground Zero supervised the drilling and sampling of a single soil boring (SBI) immediately adjacent to the end of the former UST, near where residual gasoline constituents were detected. Figure 2 presents the location of the soil boring. The boring was advanced to a depth of approximately 36 feet bgs. Fisch Environmental (C57- 683865) advanced the boring using a truck mounted Geoprobe 5400 direct push drilling rig. Soil samples were collected for logging and identification purposes at 5-foot depth intervals. Samples daWgmundzekuffboy/wp 1199.doc