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SUPPLEMENTAL SITE INVESTIGATION WORK PLAN South Pointe Property Stockton, California Conceptual Site Model had been excavated during redevelopment of the Promenade and stockpiled on the South Pointe property. The work plan stated that the material contained elevated concentrations of chromium and lead and qualified for Class II disposal at Republic Services' Forward Landfill in Manteca, California. The document references the soil as being 'burrito wrapped', suggesting it had been placed on and beneath plastic or a similar barrier material. No additional documentation is provided regarding the completion of this soil removal action. 3.5 CURRENT CONDITIONS AND EXTENT OF ORGANOCHLORINE PESTICIDES AND LEAD IN SOIL Historical activities at the site have resulted in significant disturbance and displacement of shallow soils at the site. Previous investigations have documented the presence of fill materials to approximately 5 ft bgs along the central portion of the site, materials which are believed to represent debris generated from the demolition of buildings, rail lines, loading docks, and similar historical site features. Based on environmental sampling, these fill materials generally contain concentrations of organochlorine pesticides (OCPs) and/or lead exceeding risk-based screening levels. Soils removed from the perimeter of the property to facilitate development of the surrounding Promenade property were stockpiled in the central portion of the site, resulting in an approximately 3,000-yard soil stockpile overlying native and previously disturbed soils at the site. The presence of this soil pile, and the relationship between the soil pile and underlying materials, is illustrated conceptually on cross sections presented as Figure 4. Several rounds of investigation at the site have identified OCPs and lead to be the primary constituents of concern. Concentrations of lead and OCPs (primarily dieldrin and aldrin) in soil exceeding DTSC Screening Levels (SLs) for residential use extend generally to depths of 2 to 5 ft bgs in areas of the site containing fill materials. Concentrations of lead exceeding residential screening criteria extend locally to depths of up to 10 ft bgs.The extent of lead in soil at concentrations exceeding residential SLs is depicted on Figure 5, and the extend of OCPs in soil at concentrations exceeding residential SLs is depicted on Figure 6. Expanded figures, presenting location-specific concentrations of lead and OCPs in soil, are included as Appendix C. 3.4