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Mr. Charles Leubner 10 October 1991 T Page 2 Health Division, and laboratory analysis of the sample revealed the follr;::ing results; Total Lead 10 mg/Kg Benzene 0.063 mg/Kg Toluene 3.2 mg/Kg Ethylbenzene 3.5 mg/Kg Xylene 12 mg/Kg Ethylene Dibromide 0.017 mg/Kg Total Petroleum Hydrocarbons 4,400 m K g/ g _ As a result of these findings, the PHS-EHD reportedly noted on their Underground Storage Tank Release (Leak)/Contamination Site Report dated 24 January 1990 that a further assessment of the extent of leakage will be required. According to Mr. Leubner of the Stockton Unified School District, the tank was pressure tested prior to its removal and no leaks were detected. A leak was detected, however, In the tank's p1phig during the pressure test of the tank. Thus, the source of the gasoline discharged to the soil is suspected to be the tank's piping. ti Information supplied by the PHS-EHD indicates that the depth to groundwater at the site In the spring of 1986 (a high-water year) was approximately 55 feet and is currently �~ approximately 85 feet. Due to the depth to groundwater at this site, only a soil Investigation was proposed for this phase of the investigation. ,t FIELD INVESTIGATION AND METHODS Soil Boring Locations Three soil borings were drilled pt Franklin High School on 19 August 19 1 through and around the excavation resulting from the removal of the 500-gallon dI see Figure 2). ` The first boring(B-1)was drilled to a depth of 50 feet below the ground surface through tlie.area where the leakage was believed to have occurred in the tank's piping. It was possIble to drill directly over the site of the excavation because the hole had been filled in so that a boring could be drilied directly over the area of concern. Borings B-2 and B-3 were drilled approximately 16 feet to the west and 8 feet to the east of the former excavation, respectively. Both B-2 and B-3 were drilled to a depth of 20 feet below the ground surface since hydrocarbon vapors were not detected during drilling. All borings were terminated before encomicering groundwater. A fourth boring scheduled to be drilled approximately 15-feet to the south of the former excavation area was not drilled due to the presence of several inches of stagnant standing water where the drilling was to occur,which mad:the area inaccessible to the drill rig at the:time of the