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A Remediation Feasibility Study (RFS) was prepared and submitted to PHSEHD during April, 2011. The RFS described the remedial alternatives proposed and evaluated them in terms of applicability,technical performance, implementability and cost. The RFS recommended soil vapor extraction and in-situ air sparging as the preferred alternative (Muir, 2011 c). A Corrective Action Plan (CAP)was prepared under the direction by San Joaquin County Public Health Services Environmental Health Department(PHSEHD) in 2011. The CAP was reviewed and approved by PHSEHD during September, 2011. PHSEHD directed that the CAP utilize soil vapor extraction (SVE) and in-situ air-sparging (IAS) as the preferred remedial alternative. An application for Authority To Construct(ATC)the soilvapor extraction system was submitted to the San Joaquin Valley Air Pollution Control District(SJVAPCD) in October, 2012. A Permit To Operate (PTO)was issued in January, 2013. The Soil Vapor Extraction (SVE) and In-Situ-Air Sparge (IAS) systems were installed during December 2012 to January 2013. Advanced Geo Environmental Inc. (AGE)has conducted remediation operations in the capacity of a contractor at the site under direction of this office from 1st quarter 2013 to 3Td Quarter 2015. The original SVE remediation system initially consisted of a Mako CAT 250 catalytic oxidizer soil vapor extraction system mounted on a trailer. The SVE system utilized a manifold network of two-inch diameter, Schedule 40 PVC piping installed aboveground from SVE wells PT-SVEI and PT-SVE2 to an SVE moisture knockout vessel and 10-horsepower,maximum 250 standard cubic feet per minute (SCFM)blower. Initial SVE operations conducted during first quarter 2013 period extracted a calculated mass of hydrocarbons of approximately 24.2 pounds/day, or equivalent to a volume of approximately 3.8 gallons/day of gasoline. This system was operated continuously until the first quarter of 2014 when the SVE system was changed over to a smaller blower unit and used granular activated charcoal (GAC) in four drums in order to be more cost effective. To date,the SVE system has removed approximately 7,828 pounds of VOCs from the site subsurface. The SVE system has been operating in compliance with the SJVAPCD permit to operate specifications since January, 2013. IAS operations were initiated during March, 2014 using PT-SVEI lower zone to inject air into the water column. SVE well PT-SVE2 has been used as an observation well. The SVE system was discontinued on September 1, 2015 after three months of continuous influent gas indicating<1 ppmv on the field PID and<50 ug/1 from air sample analytical laboratory results. The SVE and IAS system were temporarily shut down to allow for a site subsurface stabilization for approximately 90 days prior to a series of rebound tests being conducted. i Parmar\Site Assessment Workplan\02152018.wpd 8