SITE INFORMATION AND CORRESPONDENCE

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Ms.Lori Duncan November 15,2011 RE:2911 E.Fremont St,Stockton,CA Page 3 of 14 the inactive clarifier in October 2010 to further investigate the extent of soil contamination beneath the clarifier and to determine if groundwater beneath the site had also been impacted. Figure 3 presents site detail showing the locations of the soil borings. Tables 1 and 2 summarize the results of soil and groundwater samples collected near the inactive clarifier. Based upon the analytical results of soil samples collected at the site, soil beneath the clarifier was impacted by low to moderate concentrations of petroleum hydrocarbons and chlorinated solvents. The area of impacted soil appears to extend laterally approximately 12-15 feet from the source(clarifier),and occurs to a depth of approximately 32 feet below ground surface. Naphthalene was previously detected at a concentration as high as 29 mg/kg(Krazan,April 2010),which exceeds its Preliminary Remedial Goal (PRG) of 4.2 mg/kg for soil in an industrial setting, as established by the US EPA, Region 9. Only low levels of PCE were detected in groundwater,at levels below the Maximum Contaminant Level (MCL) of 5.0 µg/L. Based upon the lack of contaminants in boring LPB-4, located east of the clarifier and near the former waste oil UST,it does not appear that the documented contamination is related to the former USTs that were removed from the site in the early 1990s. SOIL EXCAVATION Excavation activities included concrete sawing and removal,removing the unused clarifier, excavating contaminated soil around and beneath the removed clarifier to the extent possible, stockpiling the excavated soil for characterization, sampling the stockpiled soil for potential landfilling, collecting soil samples from the excavation to confirm source removal and residual contaminants remaining, transporting and disposing of contaminated soil to a Class II landfill,and backfilling and compacting the excavated area. EHD was notified a minimum of 72 hours prior to the start of field work. The area to be excavated was marked and cleared by Underground Services Alert on June 10, 2010 (Locate Request#184601). An experienced geologist under the supervision of a licensed Professional Geologist supervised the excavation activities pursuant to the April 13, 2011 workplan. Del-Tech Geotechnical Support (Del- Tech, California Engineering Contractor A, HAZ #657366) of Oakdale, California conducted the excavation. Soil was excavated on June 20 and June 21,2011. The excavation was backfilled between June 22 and June 28,2011, and contaminated soil was transported to a State licensed landfill on July 1, 2011. The approximate limits of the excavation are shown on Figure 4. An area of approximately 290 square feet was opened and excavated. The excavation work zone was located inside the building within Warehouse Bay#2. The limits of the excavation were dictated by site conditions,such as the configuration of the building and the need to provide sufficient space on the north and west sides to allow access for the backhoe. From previous investigations and due to the known space limitations,Lee&Pierce,EHD,and the property owner were aware prior to commencing work that the excavation would not result in removal of all residual contamination. The objective of the excavation was to remove as much impacted soil as was practical and collecting confirming soil samples in order to 10759-EXC SUMMARY LTR