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WORK PLAN FOR ADDITIONAL SOIL VAPOR SURVEY Brief Background May 30, 2014 2.0 Brief Background 2.1 SITE DESCRIPTION The Site is currently owned by the City of Stockton, which refers to the Site and surrounding area as "Parcel 2A". The Site currently consists of relatively flat, fallow land and is mostly undeveloped except for the Delta View Apartments located on the western and southern portion of the Site. A State Department of Motor Vehicles (DMV) building resides to the southeast of the Site. The Stockton Deep Water Channel (McLeod Lake), Tuleburg Levee, Weber Avenue, and an office building complex are located north of the Site. The Mormon Slough runs northwest to southeast of the site from the Stockton Deep Water Channel. The Work Net building is southeast of the Site across North Lincoln Street and there is a children's museum several 100 meters east of the Site across North Lincoln Street on the south side of West Weber Avenue. During a December 2, 2002 meeting with the RWQCB-CVR, environmental management of the Parcel 2A are was divided into three operable units (OUs): L&M OU; Unocal OU (UOU); and Morton OU (MOU). The L&M OU was established to direct investigations in the area south of West Weber Avenue, west of the midline of the former Harrison Street, east of North Edison, and north of former Main Street. Currently, oversight of environmental management responsibilities of the L&M OU is retained by Stantec on behalf of CEMC and P66, and oversight of the LOU and MOU is performed by Wallace Kuhl Associates (Wallace-Kuhl) on behalf of the City of Stockton. Environmental investigations began at the Site in 1989 and quarterly monitoring and sampling activities were initiated in 2002. SECOR International Inc.(now Stantec) was retained in late 2002 for environmental consulting services at the Site. A summary of previous investigations is included in Attachment 2. 2.2 REGIONAL GEOLOGY/HYDROGEOLOGY The shallow groundwater bearing zone (A-Zone) primarily extends from the ground surface to depths ranging from approximately 25 ft below ground surface (bgs) to 40 ft bgs. Subsurface material in the shallow zone predominantly consists of silt, silty sand, and silty gravel from four to 10 ft bgs, and then organic clay, clay, high permeability silt, and lenses of silty sand and poorly graded sand to depths ranging from 25 to 40 ft bgs. The shallow zone is generally underlain by low permeability silt and clay (with an occasional, thin, silty sand or poorly graded sand lens) of highly variable thickness. A deeper groundwater bearing zone (B-Zone) is encountered at a depth of approximately 42 ft bgs and extends to approximately 50 ft bgs. Subsurface material in 2.3