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'� Nfl1NIGX�lf�lYfR <br /> Mr. Charles Leubner <br /> 10 October 1991 <br /> Page 2 <br /> Health Division, and laboratory analysis of the sample revealed the following results: <br /> Total Lead 10 mg/Kg <br /> Benzene 0.063 mg/Kg <br /> 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 41,400 mg/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. According to Mr. Leubner <br /> of the Stockton Unified School District, the tank was pressure tested prior to its removal <br /> and no leaks were detected. A leak was detected, however, in the tank's piping during <br /> the pressure test of the tank. Thus, the source of the gasoline discharged to the soil is <br /> 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 was proposed for this phase of the investigation. <br /> FIELD INVESTIGATION AND METHODS <br /> Soil Boring Locations <br /> Three soil borings were drilled at Franklin High School on 19 August 1991 through and <br /> around the excavation resulting from the removal of the 500-gallon a (see Figure 2). <br /> The first boring (B-1) was drilled to a depth of 50 feet below the ground surface through <br /> the area where the leakage was believed to have occurred in the tank's piping. It was <br /> possible to drill directly over the site of the excavation because the hole had been filled <br /> in so that a boring could be drilled directly over the area of concern. <br /> Borings B-2 and B-3 were drilled approximately 16 feet to the west and 8 feet to the east <br /> of the former excavation, respectively. Both B-2 and B-3 were drilled to a depth of 20 <br /> feet below the ground surface since hydrocarbon vapors were not detected during drilling. <br /> All borings were terminated before encountering groundwater. A fourth boring scheduled <br /> to be drilled approximately 15-feet to the south of the former excavation area was not <br /> drilled due to the presence of several inches of stagnant standing water where the <br /> drilling was to occur, which made the area inaccessible to the drill rig at the time of the <br />