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F lu-UI-9U u4. IUnvi rRulvl u130Vi Wu 1 3R1.1V. 1V y30UlulJ • rUUL/UU4 <br /> ell.( <br /> S47E OF eA FORMA—E"ROMMENTAL PNOT CnON AGENCY Pt7EWLSON.G&� <br /> 7EPARTMENT OF TOXIC SUBSTANCES CONTROL <br /> 3151 CROYDON WAY,SWE 3 <br /> SACRAMENTO.CA 96927-2106 <br /> (510)' 540-3827 <br /> June 20, 1996 <br /> Mr. Robert Chambers <br /> Beck Development Company <br /> 2114 west Hammer Lanc <br /> Stockton, California 95209 <br /> BECK DEVELOPMENT COMPANY, TRACY SITE, HAZARDOUS WASTE PROPERTY <br /> DETERMINATION <br /> Dear Mr. Chambers : <br /> In response to the April 24 , 1996 decision filed by the <br /> California Court of Appeal, Third Appellate District, the <br /> Department of Toxic Substances Control (DISC) has made a <br /> hazardous caste property determination regarding the subject <br /> property (Site) . DTSC concerns at the Site stem from the <br /> construction and use of a 16-acre reservoir by Southern Pacific <br /> Transportation Company to store "Bunker C" oil between 1926 and <br /> 1945 . In 1953 after a fire, the reservoir was collapsed and <br /> covered with native soil . Investigations into soil contamination <br /> revealed subsurface contamination with polynuclear aromatic <br /> hydrocarbons (pAHs) , a layer of asphalt-like material, and oil . <br /> In the past, DTSC required the performance of a Health Risk <br /> Assessment to determine the potential threat posed by PAH <br /> contamination in soil and in the asphalt-like 1paterial _ DTSC <br /> also rcoommended additional groundwater monitoring to assess the <br /> migration of the oil . Further discussion is provided below. <br /> The PAH contamination associated with residues in the <br /> collapsed reservoir was identified at depths between five and <br /> eight feet . In 1991, DTSC calculated the lifecime cancer risk <br /> from carcinogenic PAHs to be 1 x 10'5 to 3 x `10-5 . DTSC staff <br /> have re-calculated the potential risk from the carcinogenic_ PAHs <br /> using revised health risk criteria. DTSC has concluded that PAH <br /> levels detected in soil (assuming the same exposure assumptions <br /> used in past reports) do not represent a significant risk for <br /> unrestricted or residential land use . <br /> w <br />