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S E C ® R CHARACTERIZATION STATUS The lateral extent of the dissolved GRO and TBA plumes has been delineated, except north-northeast of Shell wells S-5 and S-6, and west of Shell well S-1 The dissolved benzene plume has been delineated except west of Shell well MW-1 The dissolved MtBE plume has laterally been delineated, except northeast of Shell wells S-5 and S-6 Dissolved GRO, benzene, MtBE, and TBA isoconcentration contour maps are included in Attachment 1 The vertical extent of dissolved MtBE and TBA beneath the site has g not been delineated, based on the presence of MtBE and TBA in CPT borings drilled during previous site assessments, and consistent concentrations of MtBE and TBA in deeper well MW-11 SECOR submitted the October 18, 2005 Work Plan for Additional Site Assessment, which included a proposal for further assessment of lateral (off-site) and vertical (on-site) impacts The work plan was approved by the SJCEHD in correspondence dated November 9, 2005 WASTE DISPOSAL The volume of purged groundwater generated during the fourth quarter 2005, and the method of disposal are documented in TRC's Quarterly Monitoring Report, October through December 2005 dated December 27, 2005 (Attachment 1) REMEDIAL PERFORMANCE SUMMARY An OS system has been operational at the site since December 20, 2002 A summary of the operation of the ozone injection system, and monthly groundwater sampling activities are presented in the following sections Ozone Infection Operation The OS system consists of a wall mounted KVA C-SpargeTM System, model 5020, that produces up to 4 grams per hour (0 009 pounds per hour) of ozone The OS system had been programmed to Inject ozone into 10 wells (SP-1 through SP-10) for 8 minutes for each well cycling 16 times per day, resulting in 89 percent programmed run time The configuration of the system is presented on Figure 1 The system operated continuously during the fourth quarter 2005 x During the current quarter (September 28, 2005 to December 27, 2005), the OS system was operational for 100 percent of the programmed run time, resulting in 1,951 hours of operation and 18 pounds of ozone injected Cumulatively, the OS system has operated for 12,666 hours, and has injected a total of approximately 114 pounds of ozone Table 1 presents the operating data for the OS system, and includes operating hours and pressure readings Remediation system field data sheets are included in Attachment 2 Monthly Groundwater Sampling Monthly groundwater samples were collected by SECOR from monitoring wells MW-3 and MW-4, and were submitted to STL for analysis for GRO, BTEX, MtBE, and TBA by EPA Method 82606 During the fourth quarter 2005, groundwater samples were collected from the wells on October 21, 2005, November 29, 2005, and December 27, • 2005 Results of the monthly groundwater sampling events are summarized in Table 2 t I1BP-ARCQ1111921ReportslQMR-QRPS1200514Q2005 QSSR and QRPS doc