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lilll�; (a <br /> Department of Toxic Substances Control <br /> Alan C.Lloyd,Ph.D. 8800 CBI Center Drive Amotd Sghmma msoger <br /> Agency sevatary Sacramento.Calltomis 858263200 Governor <br /> CaVEPA <br /> TO: .ferry Lile <br /> Project Manager <br /> Northern California Site Mitigation Branch <br /> 8800 Cal Center Drive,2nd Floor <br /> Sacramento, CA 95828-3200 <br /> FROM: Karen W. DiBiasio, Ph.D., <br /> Staff Toxicologist <br /> Science, Pollution Prevention and Technology Program - <br /> Human and Ecological Risk Division <br /> DATE: March 3, 2005 <br /> SUBJECT: DELTA GATEWAY APARTMENTS/L 8 M OPERABLE UNIT <br /> WORK PLAN FOR SOIL VAPOR ASSESSMENT <br /> PCA Code: 11050 Site Code: 101350 WP: 00 <br /> BACKGROUND <br /> The Human and Ecological Risk Division (HERD)was requested to provide ongoing' <br /> toxicology and risk assessment support for Delta View Apartments(fonnerty Delta <br /> Gateway Apartments) (Site)by the Site Mitigation Program at the Region 1 Sacramento <br /> Office. The Site is located h the City of Stockton, California. The Site is six acres In size <br /> and was formerly used for storage and as a distribution point for petroleum hydrocarbons <br /> off-loaded from ships In the Port of Stockton. In the early 1980's,the Delta Gateway <br /> Apartments were constructed on the western and southem portions of the L&M OU. <br /> There appears to be no evidence that the Stockton Redevelopment Agency(RDA) <br /> conducted any environmental investigation of the Site priorto the construction of the Delta <br /> Gateway Apartments. Previous sampling and analyses have Identified dissolved and <br /> separate-phase petroleum hydrocarbons in soil and groundwater as well as volattie <br /> organic compounds(VOCs)Including fuel constituents such as benzene, ethyibenzene, <br /> toluene, and xylenes (BTEX), chlorinated solvents, seml-volatile organic compounds <br /> (SVOCs), including polynuclear aromatic hydrocarbons(PAHs); and, metals (notably <br /> arsenic In groundwater and both arsenic and lead in soil). Methane has been detected <br /> in soil gas above the lower explosive limit(LEL) and also in groundwater. Soil gas <br /> analyses have confirmed the presence of VOCs such as petroleum hydrocarbon fuel <br /> constituents Including STEX, confirmed the presence of chlorinated solvents and <br /> Identified vinyl chloride conteminatfon,and identified hydrogen sulfide contamination" <br /> Groundwater occurs at 8 to 17 ft below ground surface (bgs)and according to the <br /> CVRWQCB flow is variable although generally to the southeast away from Mormon <br /> ® Printed on Requied Pape( <br />