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I <br /> I <br />' 9 November 1992 <br /> (GeoAudit CV 42E1-1 .8) <br /> Page 2 of 6 <br /> Ms. Diane Hinson of EHD, requesting permission to remove the tanks <br />' prior to initiating the site assessment activities outlined in the <br /> August workplan. This request was granted on 21 November 1991. <br /> However, no work was undertaken at that time. <br />' In August 1992 , at the request of Mr. Wyatt, GeoAudit submitted a <br /> workplan addendum to San Joaquin EHD. At Mr. Wyatt ' s request, the <br /> original workplan was revised so as to investigate the entire site <br /> for evidence of soil and/or groundwater contamination. This <br /> workplan was submitted on 10 August 1992 and approved in late <br /> August. <br />' GeoAudit proposed to drill six soil borings to a depth of 30 feet <br /> and collect soil samples at 5-foot intervals. Up to three of these <br /> borings would be continued to groundwater (estimated to be between <br />' 40 and 60 feet) and completed as monitoring wells if soil <br /> contamination were detected at 30 feet. A mobile laboratory would <br /> be used to analyze the samples on-site and provide immediate <br /> results to direct the drilling effort. <br /> 2 . 0 SOIL INVESTIGATION <br /> 2 . 1 Drill�.nq and Sampling <br />' Field work was performed on 19 and 20 October 1992 . Soil borings <br /> were advanced with a CME-75 drill rig equipped with 8-inch-diameter <br /> hollow-stem augers. Soils Exploration Service of Vacaville, <br /> California provided the 2-man drilling crew. Soil samples were <br /> collected at 5-foot intervals, usually starting at a depth of 10 <br /> feet, using a split-tube sampler loaded with three brass sleeves <br /> and a 140-pound hammer. The number of blows required to advance the <br /> sampler 18 inches was recorded on the boring log (see Appendix B) . <br /> After removal from the sampler, the bottom tube was screened for <br />' volatile organic vapors using a portable photo-ionization detector <br /> (Thermo Environmental Instruments model 580A) and the reading was <br /> recorded on the boring log. The ends of the tube were rhen covered <br /> with sheets of aluminum foil, capped, and sealed with aluminum duct <br />' tape. The sample was then labelled, logged on the boring log, and <br /> delivered to the mobile laboratory for immediate analysis. The <br /> middle and upper tubes were then extruded and described on the <br /> boring log. The tubes and sampler were then triple-rinsed to avoid <br /> contamination of subsequent samples. <br /> Augers were steam-cleaned between borings to avoid cross- <br /> contamination. <br /> I <br />