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pluuoly 4 <br /> .tip • <br /> w <br /> Department of Toxic Substances Control <br /> Man C.Lloyd•Ph.D. 8800 Cal Center RrNe Amold achwarzermgper <br /> AV <br /> A bry Sacramento.Ceiifomle 95826-3200 Governor <br /> TO: Jerry Lira <br /> Project Manager <br /> Northam California Site Mitigation Branch <br /> 8800 Cal Center Drive,2nd Floor• <br /> Satxamento, CA 95826.3200 /� <br /> FROM: Karen W, Dielaslo, Ph.D. av A .((_ , 109�a-e <br /> Staff Toxicologist . <br /> Science, Pollution Prevention and Technology Prograrn <br /> Human and Ecological Risk Division <br /> DATE: February 2, 2005 <br /> SUBJECT: DELTA GATEWAY APARTMENTS l L b M OPERABLE UNIT-HRA <br /> PCA Code: 11050 Site Code: 101350 WP:00 <br /> BACKGROUND <br /> The Hurnan and Ecological Risk Division (HERD)was requested to provide ongoing <br /> toxicology and risk assessment support for Deity Gateway Apartments(Site)by the Site <br /> Mitigation Program at the Region 1 Sacramento office. The Site Is located in the City of <br /> Stockton,California. The Site Is six acres in size and was farmady used for sborage and <br /> as a distribution point for petroleum hydrocarbons off-loaded from ships In the Port of <br /> Stockton. In the early 1980's,the Deft Gateway Apartments were constructed on the <br /> westem and southern portions of the L$M OU, There appears to be no evidenoe,that the <br /> Stockton Redevelopment Agency(ROA)conducted any environmental investigation of the <br /> Site prior to the construction of the delta Gateway Apartments. Previous sampling and <br /> analyses have IdentVW dissolved and separate-phase petroleum hydrocarbons in soil <br /> and groundwater as well as volatile organic compounds(VOCs)including fuel <br /> constituents such as benzene, ethylbenzene,toluene,and xytenes(13TEX),chlorinated <br /> golvents,semi-volatile organic compounds(SVQCs), Including polynuclear aromatic <br /> hydrocarbons(PAHs),and, metals(notably arsenic in groundwater and both arsenic <br /> and lead In soil). Methane has been detected In soil gas above the tower explosive limit <br /> (LEL)and also in groundwater. Soil gas analyses have confirmed the presence of <br /> VOCs such as petroleum hydrocarbon fuel•constituents including ST'SX,confirmed the <br /> presence of chlorinated solvents and Identified vinyl chloride contamination,and <br /> identified hydrogen sulfide contamination. Groundwater occurs at 8 to 17 ft below <br /> ground surface (bgs)and according to the CVRWQCB flow Is variable although <br /> generally to the southeast away from Mormon Slough.and the Stockton Channel. <br /> Prinlad on Recyded Paper <br />