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S E C O R <br /> G:rr_ ranging from 20 to 21 feet bgs. Groundwater was encountered in the well borings during drilling <br /> at depths ranging from approximately 8 to 10 feet bgs. All soil samples analyzed were non-detect <br /> for all hydrocarbon constituents, except for soil sample MW-16-S9.5, which contained MtBE at a <br /> concentration of 0.040 ppm. MtBE was detected in all groundwater samples collected from the <br /> newly installed monitoring wells at concentrations ranging from 28 to 3,900 ppb. All other <br /> hydrocarbon constituents and fuel oxygenates were non-detect. <br /> An ozone sparge unit was placed into operation on December 20, 2002 and injects ozone in to <br /> sparge wells SPA through SP-15. <br /> SENSTIVE RECEPTORS <br /> A sensitive receptor survey and a'/-mile radius water well survey were performed by Alisto in 1999. <br /> No basements or subways were found within a 300-foot radius of the subject site. An offsite <br /> subsurface utility survey revealed the presence of a sanitary sewer trench adjacent to the subject <br /> site that may influence the transport of petroleum hydrocarbons in groundwater. A search of <br /> California Department of Water Resources (DWR) and Banks Information Solutions files indicated <br /> that seven water wells had been installed within a '/-mile radius of the subject site, however, the <br /> wells could not be located based upon the information provided by DWR. A visual reconnaissance <br /> of the area did not identify the presence of any additional water wells (Alisto, 1999). <br /> MONITORING AND SAMPLING <br /> The site has been monitored and sampled since 4th quarter, 1992. From 1992 to the present the <br /> Site has been monitored/sampled quarterly. Currently, 20 wells (MW-1 through MW-6 and MW-8 <br /> through MW-21) are monitored and sampled quarterly each year. Samples are analyzed for <br /> TPHg, TPHd, BTEX, and fuel oxygenates. <br /> REMEDATION STATUS <br /> The ozone injection system consists of a panel mounted KVA C-SpargeTM System that produces <br /> 4 grams per hour (0.009 pounds per hour) of ozone. The system injects ozone to fifteen ozone <br /> wells: SP-1 through SP-15. The system was placed into operation on December 20, 2002, The <br /> system was down for the first part of the first quarter due to electrical problems. It as restarted on <br /> February 17, 2004, however, it was shut down again on March 31, 2004 due to line leaks. System <br /> will be repaired and restarted during the second quarter 2004. <br /> CHARACTERIZATION STATUS <br /> Contamination in soil has been adequately delineated. Contamination in groundwater has not <br /> been delineated. <br /> RECENT SUBMITTALS/CORRESPONDENCE <br /> February 18, 2004 — Letter, County of San Joaquin County Environmental Health Department <br /> (SJCEHD): Notice of Responsibility, Site has been assigned to the SJCEHD local oversight <br /> program. <br /> May 4, 2004—First Quarter 2004 Remedial summary report <br /> THIS QUARTER ACTIVITIES (First Quarter 2004) <br /> 1. Performed quarterly groundwater monitoring and sampling (TRC). <br /> I:1ConocoPhi llipffosco Marketing1111951QSSR1200411Q2004 QSSR.doc <br />