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1117 Lone Palm Avenue, Suite 201B Ca/'dno Modesto, California 95351 ATO 209-579-2221 Fax: 209-579-2222 Shaping the Future In August 2000, JPCA advanced three soil borings (B1, MW4, and MW5); MW4 and MW5 were completed as groundwater monitoring wells. B 1 was advanced to a depth of approximately 115 feet bgs and MW4 and MW5 were installed to a depth of approximately 75 feet bgs. Soil and groundwater samples were collected and analyzed. Site activities were summarized in JPCA's 2nd Phase 77 Environmental Assessment Report, dated October 25,2000. In January 2003, GHH Engineering, Inc. (GHH) supervised the advancement of three cone penetrometer test (CPT) borings and three soil borings to depths ranging from 104 feet bgs to 122 feet bgs. In May 2003, GHH advanced MW6A, MW6B, MW7A, and MW713 to the east of the site. These borings were completed as well clusters with MW6A and MW7A advanced to a depth of approximately 75 feet bgs, and MW613 and MW7B advanced to a depth of approximately 94 feet bgs. GHH also installed EWl in the southeast portion of the site. Site activities were summarized in GHH's Second Quarter 2003 Groundwater Monitoring Report and Additional Assessment Report, dated June 2003. In January 2004, ATC Associates (ATC) supervised the installation of five injection wells (IWI through IW5) on-site. Each injection well was completed with a shallow and deep sparge point. The shallow spargepoints were installed to a depth of approximately 74 feet bgs and the deep spargepoints were installed to a depth of approximately 108 feet bgs. These wells were installed to facilitate remediation activities. From February 17 to April 20, 2004, ATC supervised the installation of groundwater monitoring wells MW6C, MW7C, MW8, MW9A, MW913, MW9C, MW10A, MW10B, and MW10C. These wells were installed to evaluate the groundwater quality both laterally and vertically downgradient from the site. In June 2004, operation of the ozone injection system at the site was initiated. Figure 2 shows the remediation system compound location as well as the injection and groundwater monitoring well network for the site. The ozone remediation system consists of a KVA C-SpargeTM System Series 5030 model that has a maximum 03 delivery rate of 4 grams per hour and injection rates of between 2.0 and 3.0 standard cubic feet per minute(SCFM). Between May 28 and 30, 2008, ATC supervised the installation of vapor extraction wells VEWI, VEW2, and VEW3 to depths of approximately 50 feet bgs. These wells were installed to facilitate remediation pilot testing activities and evaluate soil vapor extraction as an alternative remedial approach. During July 2008, one long term and two short term vapor extraction tests (VETS)were conducted at the site in an effort to evaluate the feasibility of soil vapor extraction (SVE) as a remedial option at the site. During the long term VET a vacuum was applied to VEW I for approximately eight hours. During the first short term VET a vacuum was applied to VEW2 for approximately four hours. A vacuum was applied to VEW3 for approximately four hours during the second short term VET. 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, 5126623kapMsUemer-2015SVISWR. c 2 Cardno ATC