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' Beacon Station No.474 <br /> December 23, 1997 <br /> Stockton. Califbimia ' n ce Inve5tigation <br /> FIELD WORK <br /> ' Horizon obtained boring/well <br /> drilling permits is from the SJC PHS/EHD prior to beginning the <br /> ' work (Appendix B). Underground Services Alert (USA) was notified for locations of <br /> underground utilities, and a site-specific Health & Safety Plan was prepared prior to <br /> ' initiating the field work. <br /> All activities were completed in compliance with the State of California Water Resources <br /> Control Board's Leaking Underground Fuel Tanks (LUFT) Manual, the Regional Water <br /> ' Quality Control Board (RWQCB) Tri-Regional Board Staff Recommendations for <br /> Preliminary Investigation and Evaluation of Underground Tank Sites, and SJC PHS/EHD <br /> ' guidelines. All field work followed the Horizon Environmental Inc. Field Methods and <br /> Procedures (Appendix C). <br /> Drilling and Soil SamRling <br /> On September i I and 12, 1997, Horizon geologists observed the drilling of six soil borings <br /> at the site. The locations of the borings were selected to attempt to evaluate the presence of <br /> gasoline-range hydrocarbons in the soil and groundwater beneath the site. <br /> The borings were <br /> drilled and sampled using a truck-mounted drilling rig equipped with 8- and 10-inch <br /> diameter hollow-stem augers. All drilling, sampling and well completion activities were <br /> performed by V & W Drilling (V & W), a C-57 licensed contractor from Rio Vista, <br /> California. <br /> Three of the borings were located in close proximity to three existing onsite monitoring <br />' wells and were designed to provide a higher and slightly overlapping screened interval for <br /> groundwater sampling due to rising water levels. Boring MW-6 was drilled within three feet <br />' of monitoring_well MW-2, boring MW-8 was drilled within three feet of monitoring well <br /> MW-3, and boring MW-9 was drilled within three feet of monitoring well MW-1. An <br />' additional boring, MW-7, was drilled in the southeast corner of the site to provide lateral <br /> 1 1474-12.rpt 3 HORIZON ENVIRONMENTAL INC. <br />