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Wm. J. Hunter & Associates 2220 Loma Vista Dr <br /> � <br /> gistered Geologists Sacramento, CA 95825 <br /> troleum& Mineral Appraisers (916) 972-7941 <br /> FAX (916) 972-1683 <br /> ADDENDUM TO WORKPLAN FOR SOIL CONTAMINATION INVESTIGATION AT 1500 <br /> SHAW ROAD, STOCKTON, CA -- DATED JANUARY 12, 1993 <br /> Prepared by <br /> Mo. J. Hunter & Associates <br /> April 15, 1993 <br /> PURPOSE OF ADDENDUM: <br /> To place four (4) sail borings on above site , and complete as <br /> groundwater monitoring wells. Recent investigative work <br /> performed under the above workplan revealed the presence of <br /> hydrocarbons below 45 , which was the approximate depth of the <br /> water table during the Spring of 1986,. <br /> BRIEF REVIEW OF RECENTLY COMPLETED WORK: <br /> On February 1 %, 2, 1993, five (5) soil borings were pi aceu at the <br /> locations shown on the attached Exhibit A - they are identified <br /> as SB-1 , SB-i, etc. Total depths are ind-sated nett to the auger <br /> hale symbol . Each soil boring was contincizsly cored using wire- <br /> line operated eq,aipment; selected samples ware screened with a <br /> PID meter , S, cores were retained at 5 intervals fu-om 11 bgl to <br /> total depth, they were briefly described, prope,-lv preserved and <br /> preserved pending transport to the laboratory for analvsis. <br /> Refer to Exhibits BrGrDrE,& F for details of that work. <br /> Upon completion of augerxng operations, the soil samples were <br /> transferred under proper chain of custody to FGL laboratory,, with <br /> instructions to test for BTEX & TPH-G. The results of that <br /> analysis is summarized an Table V. <br /> A review of that analysis revealed that measureable amounts of <br /> petroleum hydrocarbon components were detected in all 5 soil <br /> borings, and below 45 'bgl , (Spring 1986 water table, ) in Soil <br /> borings #2, 3, °r 4. The levels of contamination were generally <br /> highest in the sandier sediments. No water was encountered in <br /> any of the soil borings. <br /> As a result of the above work, it is apparent that contamination <br /> has migrated downward from the site of the removed UST, and is <br /> present at depths below recent high water levels. It is possible <br /> that the groundwater may have been degraded , although: invest- <br /> igative work to date has not determined is that is the case. <br /> Because contaminarion was measured in all 5 of the sail borings , <br /> work to date has not defined either tha gertical or horizontal <br /> limits of the plume, and additional wnt-K is -equirea. <br /> Therefore, it is proposed to place four (4) additional soil <br /> 1 <br />