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ifInlet-HERRfR <br /> ATTACHMENT A -PROPOSED WORK PLAN, PRELIMINARY SITE ASSESSMENT OF <br /> FCRMF!2XNDERs UUND ST ORAGE TANK SITE <br /> STOCKTON UNIFIED SCHOOL DISTRICT <br /> (HLI 0089003) <br /> In December 1989, a 500-gallon underground tank used for storing gasoline was removed <br /> from Franklin High School. One soil sampla was collected from the excavation by a <br /> representative from the San Joaquin County Public Health Services, Environmental <br /> Health Division(PHS-EHD), and laboratory analysis of the sample revealed the following <br /> results: <br /> i <br /> Total Lead 10 mg/Kg <br /> Benzene 0.063 mg/Kg <br /> i Toluene 3.2 mg/Kg <br /> Ethylbenzene 3.5 mg/Kg <br /> Xylene 12 mg/Kg <br /> Ethylene Dibromide 0.017 mg/Kg <br /> Total Petroleum Hydrocarbons 4,400 rrtg/Kg <br /> As a result of these findings, the PHS-EHD reportedly noted on their Underground <br /> Storage Tank Release (Leak)/Contamination Site Report dated 24 January 1990 that a <br /> further assessment of the extent of leakage will be required. This work plan describes <br /> the sampling procedures and the laboratory analyses that are proposed for a soil <br /> investigation to evaluate the vertical and lateral extent of leakage that may have <br /> i occurred. According to Mr.Leubner of the Stockton Unified School District,proir to the <br /> removal of the tank it was pressure tested and no leaks were detected. A Ieak was <br /> ' detected,however, in the tank's piping during this test. Thus, the source of the gasoline <br /> i <br /> discharge to the soil is suspected to be the tank's piping. <br /> Information supplied by the PHS-EHD indicates that the depth to groundwater at the site <br /> in the spring of 1986 (a high-water year) was approximately 55 feet and is currently <br /> approximately 85 feet. Due to the depth to groundwater at this site, only a soil <br /> investigation is proposed for this phase of the investigation. <br /> r <br /> PROPOSED INVESTIGATION <br /> Soil Barin s <br /> Four soil borings will be drilled in the immediate vicinity of the former underground tank <br /> excavation site. The first boring will be drilled through the former location of the 500- <br /> gallon tank to evaluate the vertical extent of contamination. The other three borings <br /> A - 1 <br />