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7h3adwe11&Ro110 <br /> Group, respectively, published by Lawrence Berkeley National Laboratory in 1995. For the <br /> purposes of this study, we have assumed a background arsenic concentration of 8 mg/kg. <br /> The non-cancer end-points for arsenic for industrial and residential scenarios are 440 mg/kg and <br /> 22 mg/kg. Considering these values and the calculated background value of 8.76 mg/kg, we <br /> have conservatively assumed that soil with arsenic concentrations exceeding 20 mg/kg will be <br /> excavated and disposed of off-site, unless a site cap is implemented, as discussed below. <br /> Excavating soil with arsenic concentrations exceeding 20 mg/kg reduces the 95%UCL to <br /> 6.57 mg/kg. <br /> 2.0 DESCRIPTION OF CURRENT AND HISTORIC SITE CONDITIONS <br /> 2.1 Operable Unit 1 <br /> • The following sections briefly describe current and historic physical conditions at each site. <br /> Thorough descriptions are provided in the RI (Treadwell &Rollo, 2000). <br /> 2.1.1 Area 10 <br /> This site is referred to as the Banner Island Site and is owned by the SDHR. The site is located <br /> north of the Stockton Deep Water Channel, south of West Lindsay Street, and between <br /> Van Buren and North Madison Streets. Currently, the surface of the site is predominantly soil <br /> with some areas of asphaltic pavement and concrete (Figure 2). <br /> Banner Island was formally a delta island,reclaimed during the 1920s. The site was leased by <br /> the City of Stockton to the Guntert and Zimmerman Construction Division, Inc., and used for <br /> shipbuilding and repair and storage of steel until the 1970s. Figure 2 shows the approximate <br /> locations of former buildings. All structures have been demolished and removed, and all <br /> underground utilities and storage tanks were reportedly removed. <br /> • <br /> 14 <br /> 25970318.PGS 15 November 2000 <br />