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ATC Associates Inc. 1117 Lone Palm Avenue,Suite B ATC Modesto,California 95351 (:VY209-579-222-2221 Fax:209-579-2225 A S S O C I A T E S I N C . a vacuum was applied to VEW2 for approximately 4 hours. During the second short term VET using VEW3 as the extraction well,the vacuum was applied for 4 hours. The May 2008 subsurface investigation activities and July 2008 pilot testing were completed in general accordance with ATC's Subsurface Investigation and Pilot Test Workplan for Jamar Service Station, 4075 East Main Street, Stockton, California, dated January 15, 2008. This work was approved by the SJEHD in a letter dated January 18,2008. A sensitive receptor survey was conducted for the site and surrounding area during August 2008 as reported in ATC's Sensitive Receptor Survey Report for Jamar Service Station, 4075 East Main Street, Stockton, California. Between May 14 and 21, 2008, ATC supervised the advancement of six borings using CPT technology to collect discrete groundwater samples to depths of approximately 119 to 125 feet bgs. Dissolved phase hydrocarbons and fuel oxygenates were discovered on site at a depth defined as the "C" water bearing zone (WBZ) near MW3. Methyl tertiary butyl ether(MTBE) was discovered at elevated levels off-site in the"C" WBZ down gradient from well clusters MW6 and MW7. The data indicated that low concentrations of MTBE south of the site at a depth of 75 feet were possibly from the former Blue Star Gas Station; however, this has not been confirmed. Site analytical data also indicated that dissolved phase hydrocarbons did not attenuate with depth possibly suggesting that the identified "A", "B", and "C"WBZs are either interconnected or lack laterally continuous confining zones above and below. This information was reported in ATC's Additional Subsurface Investigation Report for Jamar Service Station, 4075 East Main Street, Stockton, California, dated October 2,2008. Between November 22 and December 6, 2010, ATC supervised the installation of monitoring wells MWlc, MW3c, MWl lc, and MW12a; and injection wells IW6 and IW7. Petroleum hydrocarbons were detected in soil samples collected from the boreholes of MWlc, MW3c, MW 12a, IW6 and IW7. Refer to ATC's Summary Report of Subsurface Investigation, dated February 15, 2011, for additional information. From January to April, 2011, ATC supervised modification and expansion of the existing remediation compound and installation of a soil vapor extraction (SVE) system that included a Mako 250 thermal- catalytic oxidizer(TCAT)unit. REMEDIATION SYSTEM OPERATIONS AND MAINTENENCE ACTIVITIES Remediation techniques utilized at the site include ozone injection into groundwater and soil vapor extraction in vadose zone soil. Groundwater Remediation The groundwater remediation technology currently in place at the site is an in-situ air stripping process using microencapsulated ozone (03). This technology combines the operations of air stripping and oxidative decomposition in a single process. The process employs nano- to micro-sized bubbles of air- Jamar Status Rpt IQ 2012 3