ARCHIVED REPORTS_THIRD QUARTER 2011 SITE STATUS, REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT

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Stantec L & M OPERABLE UNIT-THIRD QUARTER 2011 SITE STATUS, REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT October 28, 2011 3.0 Status of Remediation Activities 3.1 DUAL PHASE EXTRACTION SYSTEM 3.1.1 Dual Phase Extraction Systems 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 Travaini TRO 400s 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 — 3Q11 During 3Q11 (June 16, 2011 through September 15, 2011) the DPE system was approximately 86% operational (78 out of 91 days). The system was shut down on July 15, 2011 to accommodate the third quarter monitoring and sampling event. The system was restarted on July 20, 2011 and operated without incident the remainder of the quarter. A critical device check was performed on the system on August 4, 2011. Sampling and analysis for TPHd via EPA Method TO-17 was initiated on August 11, 2011 for the SVE portion of the DPE system. Compliance vapor and groundwater samples were collected on July 13, August 11, and September 15, 2011. During 3Q11, the DPE system (GWE and SVE combined) removed approximately 11.9 lbs (2.0 gallons) of TPHg, 12.7 lbs (1.8 gallons) of TPHd, 3.9 lbs (0.5 gallons) of TPHo, 0.14 lbs (0.02 gallons) of MtBE, and 0.1 lbs (0.01 gallons) of benzene from water and soil vapor. No measurable amount of TBA was removed during 3Q11. Historically the DPE system (GWE and SVE combined) has removed approximately 18,016 lbs (2,954 gallons) of TPHg, 9,539 lbs (1,328 gallons) of TPHd, 5,135 lbs (674 gallons) of TPHo, 11.92 lbs (1.61 gallons) of benzene, 3.43 lbs (0.55 gallons) of MtBE, and 0.52 lbs (0.08 gallons) of TBA from water and soil vapor to date. Since system start-up groundwater extraction has removed and treated approximately 6,649,500 gallons of water. I:\Tidewater\TW Stockton(P2A)\QMRs\201 1\3Q1 1\3Q11 QSSR QRSR QMR Stockton_FINAL.doc 3.1