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SUPPLEMENTAL SITE INVESTIGATION WORK PLAN South Pointe Property Stockton, California Site Background Southpointe Properties, Stockton, California dated March 25, 2008 (WKA, 2008). The investigation was performed on behalf of the City of Stockton Redevelopment Department on a self-directed basis (i.e., not subject to formal regulatory oversight). Investigation activities performed by WKA between February and November 2007 were intended to characterize site soils and shallow groundwater for potential chemical impacts related to historical industrial uses. The majority of the work was performed on the South Pointe property (subject site of the current investigation) but also included the Promenade area, which was subsequently redeveloped as the pedestrian arcade which currently exists between the site and Stockton Channel to the north and Mormon Slough to the west. During three phases of investigation WKA advanced 60 test pits on the South Pointe site to a maximum depth of approximately 17 ft bgs. Investigative activities were focused along the central rail lines historically transecting the site east to west, and in the northeast corner of the site, where a significant area of petroleum hydrocarbon-impacted soil was identified. Multiple rounds of investigation allowed WKA to analyze initial samples and conduct follow-up, `step out' sampling to characterize areas with elevated constituents of concern. Test pit locations are illustrated on the WKA Figure 4 included in Appendix A. Encountered materials consisted of artificial fill and building rubble to depths of approximately 2 to 8 ft bgs in the locations of former onsite structures. Deeper native soils consisted primarily of fine-grained sand to depths of 10 to 15 ft bgs. Railroad track remnants (ties and ballast) were observed at the location of test pit TP-9, located in the western portion of the site. Soil and Groundwater Sampling WKA collected 259 soil samples across the site and the adjacent Promenade property. Shallow groundwater was encountered at depths ranging from 8 to 17 ft bgs in 12 of the exploratory test pits and at each of these pits a grab groundwater sample was collected.Soil and groundwater samples were analyzed for one or more of the following groups of analytes: • Total petroleum hydrocarbons (TPH) quantified as gasoline, diesel, motor oil, hydraulic oil, mineral oil, and kerosene by USEPA Method 8015M; • Volatile organic compounds (VOCs) by USEPA Method 826013; • Semi-volatile organic compounds (SVOCs) by USEPA Method 8270C; • Organochlorine pesticides (OCPs) by USEPA Method 8081 A; • Polychlorinated biphenyls (PCBs) by USEPA Method 8082A (soil only); and • Title 22/CAM 17 Metals by USEPA Methods 6000/7000. Data Analysis and Findings 2.3