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. Quik Stop No 121 Closure Report CCI Project No 12118 Page 4 of 33 to 43 feet, as detected in the water sample collected at MW-4 Low concentrations (Iess than I0 ug/L)of MTBE were detected at the two perimeter wells, MW-5 and MW-7, located on the south and southeast sides of the site In February 2001, Quik Stop began conducting a series of 8-hour, dual-phase treatment events at the site The Mobile Treatment System (MTS) events were conducted on a monthly basis, using the MTS operated by TRC of Concord, California The vapor extraction events were conducted mainly on wells MW-3 and RW-1 from February 2001 to December 2001 A total of 9 MTS events were conducted at the site During that time, a total of 47 29 gallons of equivalent product were removed from the site A summary of the MTS events are included in Tab 2, Table 5 and Appendix E At the request of the County, CCI performed additional investigation and groundwater monitoring activities at the site in July and August 2001 The work included drilling and installing two additional deep groundwater monitoring wells to 75 feet One well was placed on the northwest corner of the site (MW-10)and the other deep well (MW-9) was installed on the southwest side of the site CCI also installed two additional off-site shallow groundwater monitoring wells One well (MW-11)was placed on the northeast corner of the property located at 1190 West Louise Avenue The other shallow well (MW-12)was placed in the sidewalk on the northwest corner of the intersection of West Louise Avenue and Union Avenue The site then had a total of thirteen wells, including one recovery well and 9 A-aquifer monitoring wells There were also three deep wells (MW-6, MW-9 & MW-10), which monitor the B-aquifer at a depth of 75 feet On July 26, 2001, CCT conducted an aquifer pump test in well RW-I to evaluate the hydraulic characteristics of the shallow aquifer underlying the site The average value of K for the pumping and recovery test was 0 0033 centimeter per second (cm/s) or 0 0064 feet per minute (ft/min) In January 2002, CCI prepared a Feasibility Study and Corrective Action Work Plan for the site Several remediation methods were reviewed, including pumping and treating the groundwater with granulated activated carbon (GAC), then discharging the treated water to the sanitary sewer, dual-phase vapor extraction, with the extracted groundwater being treated with granulated active carbon(GAC)and then being discharged to the sanitary sewer, and treating the groundwater contamination in-situ using an ozone micro-sparging technology After consultation with Quik Stop, CCI proposed to install the KVA C-Sparger® System (System) ozone generator to remediate the groundwater at the site Due to the site lithology, which is a relatively flat gradient and localized area of the groundwater compounds at the Quik Stop site, this remediation technique appeared to be appropriate for the subject site The system