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STATE OF CALIFORNIA—ENVIRONMENTAL PROTEC*GENCY PETE WILSON,Governor <br /> E. <br /> DEPARTMENT OF TOXIC SUBSTANCES CONTROL <br /> +0151 CROYDON WAY,SUITE 3 <br /> SACRAMENTO,CA 95827-2106 <br /> (916) 855-7700 <br /> February 3, 1992 <br /> FEB 0 5 1992 <br /> Mr. Robert Chambers ENVIRONMENTAL HEALTH <br /> Beck Development Company PERMIT/SERVICES <br /> 2114 West Hammer Lane <br /> Stockton, California 95209 <br /> Dear Mr. Chambers: <br /> BECK DEVELOPMENT COMPANY, TRACY SITE <br /> This letter is to state the position of the Department of <br /> Toxic Substances Control (Department) with regard to residential <br /> development of the subject site. <br /> Our review of the December 20, 1991, Supplemental Health <br /> Risk Assessment (HRA) indicates that although concentrations of <br /> carcinogenic polycyclic aromatic hydrocarbons (PAHs) are present <br /> in the contaminated soils within the former storage reservoir at <br /> the site, the health risk posed by these concentrations to future <br /> residents is not significant. This conclusion is based on the <br /> results of the recent sampling of soils within the reservoir, the <br /> calculations presented in the Supplemental HRA, and the <br /> conservative risk assumptions contained in those calculations. <br /> However, the Department finds that the potential health risk <br /> represented by the waste sample encountered at the bottom of <br /> Trench T-1 during the September 13 , 1991, sampling is <br /> significant. We have reviewed the January 24, 1992 addendum to <br /> the Supplemental HRA, which was prepared by your consultant <br /> (Kleinfelder) to specifically address the health risk posed by <br /> this waste. We do not agree with the health risk as calculated <br /> in the addendum. We calculate the total life time cancer risk <br /> associated with residential exposure to this waste to be in <br /> excess of one in ten-thousand (1 x 10-4) . <br /> In view of the fact that the waste material in T-1 was not <br /> encountered in the other trenches nor identified as present in <br /> previous borings, it does not appear to be wide spread within the <br /> reservoir. Also, this material appeared only as a thin layer <br /> directly above the concrete at the bottom of T-1. Therefore, . the <br /> Department believes it feasible to delineate and remove this <br /> waste material from the former reservoir prior to residential <br /> development of the site. <br />