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l <br /> • 1, MW-2, MW-6, MW-7, MW-8, and MW-10 Table 2,Table 3, and Figure 3 in the attached report summarize <br /> groundwater analytical data and laboratory reports are included as Attachment 2 <br /> The highest concentrations of hydrocarbons appear to remain onsite in the vicinity of the pump islands (MW- <br /> 1) and somewhat downgradient of the tank system When compared to the November 2000 sampling event, <br /> hydrocarbon concentrations decreased in MW-1 and MW-4 (slightly), while they increased slightly in MW-5 <br /> Hydrocarbon concentrations remained relatively unchanged in the remainder of the wells Changes in <br /> hydrocarbon concentrations are most likely a result of groundwater elevation fluctuations and remediation <br /> efforts Since the initiation of remediation efforts, hydrocarbon concentrations across the site have generally <br /> decreased <br /> Remediation Activities—First Quarter 2001 <br /> In August and September 1999, SECOR installed a vapor extraction/air sparging system at the subject site to <br /> remediate hydrocarbon-impacted soils and groundwater System operation began December 13, 1999 <br /> The vapor extraction system consists of ten wells (W-1 through W-8, MW-1 and MW-3) manifolded within the <br /> remediation compound Vapors are extracted with a blower and destroyed with a catalytic oxidizer with a <br /> destruction efficiency of at least 95% The air sparging system consists of 4 wells (AS-1 through AS-1) An <br /> air compressor is used to introduce air into the sparging wells, and recovered vapors are destroyed with the <br /> SVE system <br /> Based on the analysis of influent samples, SECOR estimates that 1,858 pounds (304 7 gallons) of gasoline <br /> were removed and treated during the reporting period at an average extraction rate of 189 scfm SECOR <br /> estimates that 31,539 pounds (5,1704 gallons) of hydrocarbons have been removed since system startup <br /> Approximately 44 gallons of free product have been bailed from MW-1 since its detection if February 2000 <br /> Attachment 3 in SECOR's report Includes soil vapor analytical results and system efficiency results <br /> If you have any questions regarding these matters, please do not hesitate to contact me at(206) 286-4495 <br /> Sincerely, <br /> Time Oil Co <br /> A," <br /> Anastasia E Duarte-Wilkinson <br /> Environmental Toxicologist <br /> cc Ms Elizabeth Thayer <br /> California Regional Water Quality Control Board <br /> letlersfcalrY404914049M doc <br /> 2 <br />