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collected from MW-4, MW-7, MW-8, MW-9 or MW-10 No sample was submitted from MW-1 due to the presence of free product Table 2 and Table 3 in the attached report summarize groundwater analytical data and laboratory reports are included as Attachment 2 The highest concentrations of hydrocarbons appear to remain onsite in the vicinity of the pump islands (MW- 1) MW1) and somewhat downgradient of the tank system When compared to the August 2000 sampling event, hydrocarbon concentrations increased slightly in MW-4 and MW-5, while they decreased slightly in MW-3 Hydrocarbon concentrations remained relatively unchanged in the remainder of the wells Changes in hydrocarbon concentrations are most likely a result of groundwater elevation fluctuations and remediation efforts Since the initiation of remediation efforts, hydrocarbon concentrations across the site have generally decreased The appearance of free product in MW-1 appears to be the result of condensed sod vapor due to vapor extraction efforts Site inventory records and leak detection systems were checked to assure that a new release had not occurred, no indications of a release were identified At this time product is being removed from MW-1 by hand bailing and the use of a passive skimmer in addition to continued vapor extraction efforts Remediation Activities—Fourth Quarter 2000 In August and September 1999, SECOR installed a vapor extraction/air sparging system at the subject site to remediate hydrocarbon-impacted soils and groundwater System operation began December 13, 1999 The vapor extraction system consists of ten wells (W-1 through W-8, MW-1 and MW-3) manifolded within the remediation compound Vapors are extracted with a blower and destroyed with a catalytic oxidizer with a destruction efficiency of at least 95% The air sparging system consists of 4 wells (AS-1 through AS-1) An air compressor is used to introduce air into the sparging wells, and recovered vapors are destroyed with the SVE system Based on the analysis of influent samples, SECOR estimates that 2,979 pounds (488 4 gallons) of gasoline were removed and treated during the reporting period at an average extraction rate of 187 scfm SECOR estimates that 29,680 9 pounds (4,865 7 gallons) of hydrocarbons have been removed since system startup Approximately 40 gallons of free product have been bailed from MWA since its detection if February 2000 Attachment 3 in SECOR's report includes soil vapor analytical results and system efficiency results If you have any questions regarding these matters, please do not hesitate to contact me at(206) 286-4495 Sincerely, Time Oil Co Anastasia E Duarte-Wilkinson Environmental Toxicologist cc Ms Elizabeth Thayer California Regional Water Quality Control Board i 2