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California Water Service Co an Y Final Closure Report for Underground Storage Tank Removal 1602 E. Lafayette St., Stockton, CA Closure activities described below were performed in December 2011 through January 2012, in accordance with the Closure Permits, Work Plans and the Site Health & Safety Plan. Summary tables and laboratory analytical reports for samples collected during this closure process are provided in Appendix B. The waste manifests for the project are provided in Appendix C. 2.1 Removal of Underground Storage Tanks In December 2011, Veolia Environmental Services (Veolia ES) removed the sand and oily water from the tanks and rinsed the tanks with water. All the material from the tanks were disposed of as hazardous waste by Veolia ES. The USTs were inerted and excavated on December 13, 2011 under County permit SR0063739 and the City of Stockton Fire Department permit 11/12-093. The tanks were transported and disposed of as hazardous waste at Ecology Control Industries (ECI) of Richmond, CA under manifest numbers 002135911 JJK and 002135912 JJK. Four (4) confirmation soil samples were collected from the bottom of the tank excavation on December 13, 2011 (samples TP 1, TP 2, TP 3, and TP 4). In addition, three (3) soil samples were collected from the bottom of the adjoining main pipeline trench (samples 001, 002, and 003). A total of five (5) soil samples were also collected from the two soil stockpiles onsite (see Figure 3). All samples were collected under chain of custody and delivered on the day they were sampled to McCampbell Analytical, a state certified laboratory, for analysis. Analytical results are presented in Section 3.0 of this Report (analytical reports are provided in Appendix B). 2.2 Backfilling of the Excavation Based on the results including non-detect for TPHg and TPHd levels significantly below 1,000 mg/kg, no further soil removal in the tank excavation was warranted. Debris greater than three inches in diameter was removed from the soil stockpiles and disposed of as debris (non-hazardous). The excavated soil was used to backfill the excavation in 12" lifts and clean fill was imported to bring the excavation to match ground level. Compaction testing results are attached in Appendix D. Cal Water has reported that the plan for this portion of the facility is to asphalt the area in the future for use as employee parking, which will provide a much more impervious cover to prevent stormwater infiltration in the future. Concrete and/or brick debris that were removed from the excavation were staged onsite separate from the excavated soil. This debris was removed as non-hazardous waste and disposed of offsite. 2.3 Removal and Disposition of Associated Piping Two sets of pipelines associated with the former USTs were identified at the site (see Figure 3). The first set in the northern of the two trenches consisted of two three-inch diameter pipelines, one 1%-inch pipeline, and a 3/4"-inch pipeline. Through a utility survey, placing a camera in the CHOW ENGINEERING INC. 2