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o� <br /> 1� Harding Lawson Associates <br /> i <br /> i December 20, 1994 <br /> 256661 <br /> San Joaquin County <br /> Mr Harlin Knoll! Page 2 <br /> LEADED TANK (Site B) f <br /> TPH 836 ppb 372 ppb <br /> Benzene 460 ppb ¢100 ppb <br /> Toluene 7430 ppb c150 ppb <br /> Xylene 46500 ppb 4030 ppb <br /> Tetraethyl Lead 300 parts per million (ppm) 1368 mg/kg <br /> The SJCEHS, acting as lead agency, requested HSC to over-excavate the tank sites to determine the <br /> condition of the soil and groundwater at each site Currently, Site A has been over-excavated to the <br /> groundwater table (approximately 11 feet below the ground surface (bgs) Contarrvnated sods were <br /> present to the groundwater table and a sample collected at 11 feet bgs contained up to 1,200 <br /> milligrams per kilogram (mg/kg) of TPH-G, and benzene, toluene, ethylbenzene, and xylenes (BTEX) at <br /> 26 mg/kg, 110 mg/kg, 34 mg/kg, and 160 mg/kg, respectively A sample of the groundwater collected <br /> from the Site A tank pit contained concentrations of TPH-G at 56 milligram per liter (mg/1) and BTEX <br /> at 24,000 micrograms per liter (ug/1), 19,000 ug/l, 2,400 ug/l, and 10,200 ug/1, respectively Soils from <br /> the excavation at Site A were stockpiled and aerated onsite <br /> Currently, no over-excavation work has been conducted at Site B The excavation has been backfilled <br /> and the former tank location is now occupied by a concrete pad used to store oil <br /> The concrete fuel oil bunker is located near the west side of the molasses tank and is bounded by <br /> railroad tracks to the west and the molasses storage tanks to the east (Plate 4) The 10,000 gallon <br /> concrete bunker was used to store No. 6 fuel oil The top of the bunker has been removed and the <br /> inside has been steam cleaned The SJCEHS has requested that HSC prepare a closure plan for the <br /> 7 concrete bunker <br /> Groundwater at the HSC facility typically occurs at depths of 8 to 12 feet below ground surface and <br /> flows towards the northeast <br /> FIELD INVESTIGATION <br /> HLA's field investigation included an evaluation of groundwater conditions and groundwater quality <br /> associated with Site A and Site B USTs and an evaluation of soils below the concrete bunker All field <br /> work, was performed in accordance with HLA's site-specific Health and Safety Plan and HLA's work <br /> plan approved by SJCEHS <br /> J <br /> R <br /> I � <br />