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L & M OPERABLE UNIT- THIRD QUARTER 2014 SITE STATUS, REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT Status of Remediation Activities October 31, 2014 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 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. In a letter dated December 19, 2011 the RWQCB-CVR approved shutdown of the DPE system for rebound testing. On May 3, 2012 the system was rebound tested. Based on the results of the test, it was determined that the DPE system would only be operated periodically to capture product that seeps into the DPE wells. On October 16, 2013 the DPE system's LEL sensor would not calibrate. The LEL sensor was replaced; however the system remained off for additional rebound testing as agreed upon during a March 7, 2014 meeting between Stantec and the RWQCB-CVR. In a letter dated April 7, 2014 the RWQCB-CVR requested submittal of a proposal to remove the existing DPE remedial equipment while leaving system piping, manifolds, and other infrastructure in place to allow for optimization to occur using a mobile treatment unit if necessary. Stantec submitted a Remediation Equipment Removal Proposal dated May 30, 2014 and additionally proposed to retain the GWE portion of the DPE system for processing of M&S purge water and/or any additional groundwater generated by future remedial efforts. 5 Stantec 3.1