SITE INFORMATION AND CORRESPONDENCE

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r r ' Ms.Lori Duncan November 15,2011 RE:2911 E.Fremont St,Stockton,CA Page 4 of 14 estimate the mass of contaminants remaining in place at the close of excavation activities. Approximately 170 cubic yards of soil was excavated from the source area. Del-Tech utilized a Case 580 Extendahoe backhoe to remove the soil. Del-Tech was able to remove soil within allowable boundaries from a depth of approximately 18 feet. The excavated soil was stockpiled on concrete just outside of the warehouse pending characterization and disposal. Field Observations Soil beneath the site consisted primarily of silts and clays from the ground surface to the maximum depth excavated,which was approximately 18.5 feet bgs. Moderate to strong petroleum odors were first observed at a depth of approximately 4 to 5 feet bgs in the immediate vicinity of the clarifier upon its removal. Moderate to strong petroleum odors were generally observed throughout the entire depth of the excavation immediately surrounding and beneath the former clarifier. Petroleum odors appeared to lessen in all directions as excavation progressed away from the source(the former clarifier). Very low to no petroleum odors were noted in the excavation side walls on the north, west, and east sides, but moderate odors were still observed along the south wall and in the excavation floor. Confirmation Soil Sampling Lee&Pierce directed Del-Tech to excavate selected soil sample locations along the sidewalls and floor of the excavation with a drive sampler. To collect each sample, Lee & Pierce personnel placed a pre- washed, 2-inch diameter brass tube into the drive sampler and Del-Tech personnel utilized the backhoe bucket to support and guide the drive sampler to the selected location. The sample was then collected by driving the sampler into the side wall or floor of the excavation using a manual slide hammer. Lee & Pierce personnel retrieved the sample tube from the sampler, sealed the brass sample tube with Teflon® tape and plastic end caps, labeled the sample, and placed the sample in an ice chest cooled to a temperature of approximately 4° C. A total of eight soil samples were collected on June 21, 2011. Figure 4 shows the locations of the confirmation soil samples collected from the excavation. The soil samples were transported to Argon Laboratories (CLAP #2359) of Ceres, California and analyzed for Total Petroleum Hydrocarbons as Gasoline(TPHg)and volatile organic compounds(VOCs) by EPA Method 8260B. The analysis was expanded to include oxygenated gasoline compound,including MTBE. Summary of Analytical Results Soil samples collected from the north wall at 12 feet bgs (NEW-12.0) and 12.5 feet bgs (NWW-12.5), from the west wall at 16 feet bgs (WW-16.0), and from the southeast wall at 15 feet bgs (ESW-15.0) 10759-EXC SUMMARY LTR