ARCHIVED REPORTS_FOURTH QUARTER AND ANNUAL 2010 SITE STATUS, REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT

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Stantec L & M OPERABLE UNIT- FOURTH QUARTER AND ANNUAL 2010 SITE STATUS, REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT January 31, 2011 3.0 Status of Remediation Activities 3.1 DUAL PHASE EXTRACTION SYSTEM 3.1.1 Dual Phase Extraction Operations Summary The dual phase extraction (DPE) system consists of groundwater extraction (GWE) and soil vapor extraction (SVE) and utilizes of wells DPE-1 through DPE-13, and 2AMW-14, a 100-gallon liquid/vapor separator, and a Solleco 400- standard cubic feet per minute (scfm) thermal oxidizer with a Travani 25-hp liquid ring pump. From March 18, 2004 through April 4, 2004, the system was operated to conduct source tests for the San Joaquin Valley Air Pollution Control District (SJVAPCD) and the collection of effluent Polycyclic Aromatic Hydrocarbon (PAH) sampling under Authority to Construct (ATC) number N-4878-1-1. On July 7, 2004, the SJVAPCD issued a new ATC number (N-4878-1-2) for permanent operation of the system. The system was re-started on August 2 and 3, 2004 for collection of PAH samples. Following PAH sample collection; the system was shut down until Site excavation activities were completed. Continuous operation of the DPE system was re-commenced on December 14, 2004. On June 22, 2005, SJVAPCD issued a Permit to Operate (PTO) number (N-4878). On September 8, 2006, SJVAPCD issued a PTO number (N-4878-1-3) that excluded further sampling of PAH. 3.1.2 Dual Phase Extraction System Operational and Analytical Data —4Q10 The system shutdown on August 28, 2010 due to transfer pump failure and was restarted on October 4, 2010 after it was reconfigured without the first oil water separator. DPE wells were closed during pilot testing November 16, 2010 through 19, 2010. On December 6, 2010 the system hour meter was found to be functioning intermittently so it was removed and replaced. During 4Q10 (August 4, 2010 to December 14, 2010), the DPE system (GWE and SVE combined) removed approximately 115.1 pounds (18.9 gallons) of TPHg, 62.8 pounds (8.7 gallons) of TPHd, and 28.6 pounds (3.7 gallons) of TPHo. No measurable amount of benzene, TBA, or MtBE was removed during this time period. The DPE system has removed approximately 7,705 pounds (1,263 gallons) of TPHg, 9,548 pounds (1,330 gallons) of TPHd, 5,119 pounds (672 gallons) of TPHo, 5.09 pounds (0.69 gallons) of benzene, 0.01 pound (<1.0 gallon) of MtBE, and 1.07 pounds (0.16 gallon) of TBA from water and soil vapor to date. Since system start-up groundwater extraction has removed and treated approximately 5,725,230 gallons of water. In addition to the remediation system on-site, SPH removal activities are conducted to remove observed SPH from wells on and off-site. SPH removal activities are scheduled to be I:\Tidewater\TW Stockton(Parcel 2A-0415)\Reports\QMR\2010\4010-Annual\4Q10 and Annual OSSRQRSRQMR Stockton_FINAL.doc 3.1