ARCHIVED REPORTS XR0003742 - Laserfiche WebLink

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a The subject site is located adjacent to and east of Interstate Highway 5 in a residential area of Stockton West of the of Interstate 5 is a small commercial area with two gas stations and a shopping center An irrigation well owned and operated by the California Department of Transportation (Caltrans) is located approximately 120 feet south of the subject site Five domestic water wells are located southeast of the subject site at distances ranging from 780 to I,120 feet away The nearest open body of water is the Smith Canal located approximately 1,200 feet south of the subject site SITE HISTORY On December 7, 1994 Shell notified SJCPHS of a suspected product loss from the regular-unleaded underground fuel storage tank (UST) at this site The loss was due to corrosion of the southern most UST The total estimated release was approximately 8,500 gallons Fugro West, Inc (Fugro) conducted site reconnaissance and performed a 2,000 foot-radius well survey to determine if there were any nearby receptors or water-supply wells The results of the well survey are presented in Appendix A (Fugro's Figure I and Fugro's Table 1) An estimated 822 gallons of product were recovered utilizing a vacuum truck to remove free product from the tank backfill material during the period of December 10 to December 13, 1994 On December 10 and 13, 1994 Fugro West, Inc (Fugro) drilled and installed wells MW-1 and RW-I Wells MW-1 and RW-1 contained 2 5 and 1 5 feet of floating product after installation The boring logs for these wells are contained in Appendix B Soil samples collected from MW-1 at the depths of 6 5 and 11 feet below grade (fbg) did not contain detectable levels of Total Petroleum Hydrocarbons as gasoline (TPH) The sample from 11 fbg contained 0 020 parts per million (ppm) of benzene and the sample from 6 5 fbg was non-detectable (ND) for benzene The soil sample collected at 15 5 fbg in MW-1 contained 3,200 ppm TPH and 73 ppm benzene These results are summarized on Fugro's Table 2, contained in Appendix A of this report On December 13, 1994 a soil vapor extraction (SVE) system consisting of an internal combustion engine was put into operation extracting vapors from Wells MW-I and RW-1 This system was run for 2,631 hours and on May 1, 1995 the system was shut down During the operation of the SVE system it is estimated that 1,449 gallons of petroleum hydrocarbons were removed from the subsurface On December 28 and 29, 1994 a CPT rig was used to advance 14 probes into the ground for collection of soil and ground water samples A total of 14 ground water samples and five soil samples were collected during this work The locations of the CPT borings are shown on Fugro's Figure 2 contained in Appendix A Soil samples from Borings CPT-1, CPT-2, and CPT-6 contained non- 240-0783 2