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S E C O R OS System Effectiveness Although the system was not as efficient due to the decreased run time, the existing OS well network appears to be successfully remediating hydrocarbons dissolved in the groundwater beneath and downgradient of the USTs in the area of well MW-10. The results of quarterly groundwater monitoring since the startup of the OS system, and the results of monthly groundwater sampling of well MW-3 indicate the presence of declining GRO and MtBE concentration trends in wells MW-1 through MW-5; these wells are located in the vicinity of the OS wells. Since the system was brought on-line, concentrations of GRO and MtBE have gradually declined in well MW-10 over the quarterly sampling events performed by TRC and the monthly sampling events performed by SECOR, with occasional fluctuations of MtBE concentrations reported over the last year of monthly sampling. Graphs illustrating dissolved GRO, benzene, and MtBE versus time in wells MW-3 and MW-10 are provided as Figures 2 and 3, respectively. SECOR will continue to operate and evaluate the effectiveness of the OS system during the first quarter 2006. 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 November 15, 2005 (Attachment 1). RECENT SUBMITTALS 1 CORRESPONDENCE In accordance with the September 13, 2004 Work Plan for Additional Site Assessment, SECOR completed the installation of two of the three off-site wells on May 17, 2005 (MW-23 and MW-24). Well MW-22 was not installed at this time due to the presence of utilities in the immediate vicinity of the proposed location (private property access road). SECOR submitted an Addendum to Work Plan for the Installation of Well MW-22 on June 17, 2005, which included a proposal for installing well MW-22 at the same location using Geoprobe direct push drilling equipment. Following the receipt of the addendum work plan, the SJCEHD contacted SECOR and indicated that the proposed well construction details were not in compliance with the California DWR Water Well Standards, which require a minimum of two inches of annular space between the well casing and the borehole. SECOR submitted a Second Addendum for the Installation of Well MW-22 on July 15, 2005, which proposed the installation of well MW-22 using the hollow stem auger drilling method, as originally proposed in the initial work plan, at an alternative location located on private property (Holiday Inn property). The second addendum work plan was approved by SJCEHD in correspondence dated July 20, 2005, and SECOR oversaw the completion of well MW-22 on August 26, 2005. SECOR will submit the results of off-site assessment in a Site Conceptual Model (SCM) as requested by the SJCEHD in correspondence dated September 28, 2004 during the first quarter 2006. SECOR submitted a Work Plan for the Reinstallation of Off-Site Well MW-14 on December 22, 2005. The work plan was approved by the SJCEHD in correspondence dated January 10, 2006. I:1BP-ARC01111951Reports\QSR&QRPS 2005111195 QSR& QRPS 4Q05.doc