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Former Beacon Station No 419 February 17, 1999 ' Stockton California Additional Subsurface Investigation a station building, two gasoline product dispenser islands located east of the station building, and three underground gasoline storage tanks (USTs) located toward the eastern property boundary Locations of these and other pertinent site features are shown on the Site Plan ' (Figure 2) ' Previous environmental work at the site was performed by Acton, Mikelson, van Darn (AMvD) and others This previous work included drilling three onsite soil borings (SB-1, ' SB-2, and S13-3) in March 1991, the removal and replacement of the UST's in October 1993, and drilling three additional soil borings and installing three onsite 4-inch inside diameter ' (ID) groundwater monitoring wells (MW-1, MW-2, and MW-3) in July 1994 Gasoline hydrocarbons were found to be present in soil and groundwater during these previous ' investigations Locations of the soil borings, UST's, and groundwater monitoring wells are ' shown on Figure 2 Groundwater was found to be present at a depth of approximately 70 feet below surface grade (bsg) in July 1994 In May 1996, Horizon drilled soil borings SB-4, S13-5, MW-4, MW-5, and MW-6, and treported the results on August 2, 1996, in Report [ofl Additional Subsurface Investigation Borings S13-4 and S13-5 were advanced to a depth of approximately 561/2 feet bsg Borings ' MW-4, MW-5, and MW-6 were advanced to depths of approximately 70 feet to 71 feet bsg A 4-inch ID groundwater monitoring well was constructed in borings MW-4 and MW-5, and a 2-inch ID groundwater monitoring well was constructed in boring MW-6 Groundwater was encountered in the borings between the depths of 50 feet to 57 feet bsg ' Gasoline hydrocarbons were not present above the laboratory reporting limits in any of the samples analyzed from borings S13-4, MW-4, MW-5, and MW-6, except for a trace concentration of 0 0057 parts per million (ppm) total xylenes detected in the soil sample collected at 50 feet bsg in boring SB-4 Gasoline hydrocarbons were detected in soil samples from boring S13-5 with the highest concentrations being 4 1 ppm TPHg and 0 44 ppm benzene in the soil sample collected at 55 feet bsg MTBE was not present above the 1 laboratory reporting limits in any of the soil samples analyzed Gasoline hydrocarbons were detected in the water samples collected from wells MW-5 and MW-6 with reported 1419-12 rpt 2 HORIZON ENVIRONMENTAL INC.