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1 <br /> Former Beacon Station No 419 February 17, 1999 <br />' Stockton California Additional Subsurface Investigation <br /> W Drilling (V&W), a C-57 licensed contractor from Rio Vista, California The well <br /> completion activities were approved and witnessed by a SJC PHS/EHD inspector <br />' During drilling, soil samples were collected where possible from all borings at five-foot <br /> intervals or less from the ground surface to the total depth of the boring In addition, as <br />' requested by the SJC PHS/EHD in their letter dated May 5, 1998, "continuous core" soil <br /> samples were collected between the depths of 75 to 88 feet in boring SB-6 Soil --riples <br />' and drill cuttings were evaluated for the presence of petroleum hydrocarbon vapors with a <br /> portable organic vapor meter (OVM) Any evidence of petroleum hydrocarbons was <br />' recorded on the soil boring logs, which contain soil descriptions and well completion data <br />' (Appendix C) Soil samples were contained in chilled storage for transport to the laboratory <br /> for the requested analyses <br />' As requested by the SJC PHS/EHD in their letter dated October 13, 1997, soil borings SB-6, <br /> SB-7, and SB-9 were drilled to investigate soil at the historical low groundwater level of <br /> approximately 85 feet bsg beneath the site Soil boring SB-6 was drilled to approximately <br />' 91 i/2 feet bsg Continuous soil samples were collected between 75 and 88 feet bz,� and a <br /> discrete groundwater sample was collected between 88 to 91%2 feet bsg utilizing a <br />' HydroPuncht tool The groundwater sample and selected soil samples were submitted on <br /> expedited overnight analysis in order to evaluate hydrocarbon impact at depth Soil boring <br />' SB-7 was drilled and sampled to 86 feet bsg and backfilled with a 5% bentonite/neat cement <br /> slurry (grout) and a six-inch thick concrete cap was placed to surface grade Upon <br />' completion of drilling, a groundwater monitoring well was installed in borings MW-7, MW- <br /> 8, MW-9, and SB-9 (MW-10) Also after completion of drilling, vapor wells VW-1 and <br />' VW-2, as well as air-sparging well AS-I, were installed in boring SB-6 <br />' The sediments encountered during drilling consisted primarily of interbedded, firi,-grained <br /> sandy silts, silty sands, and sands The sediments were classified using the Unified Soil <br />' Classification System (USCS) A copy of the USCS is shown on the Boring g Y Lo Symbol <br />' 1419-12 rpt 4 HORIZON ENVIRONMENTAL INC. <br />