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concentrations of hydrocarbons were found in the samples collected from MW-7 (0 7 ppb xylenes), MW-8 <br /> (1 3 ppb benzene), and MW-9 (82 5 ppb hydrocarbons and 1 3 ppb benzene) Hydrocarbons were not <br /> detected in the sample collected from MW-10 Low concentrations of MTBE were detected in the <br /> groundwater samples collected from MW-4 (8 3 ppb), however, it was not detected in any of the other <br /> samples Table 2 in the attached report summarizes groundwater analytical data and laboratory reports are <br /> included as Appendix B <br /> The highest concentrations of hydrocarbons appear to remain onsite in the vicinity of the pump islands (MW- <br /> 1) <br /> MW1) and sidegradient of the former tank bed (MW-5) The groundwater plume does not appear to be migrating <br /> to any great extent When compared to the April 1998 sampling event, hydrocarbon concentrations <br /> decreased in MW 1, MW-2, MW-3, and MW-8, while they remained relatively unchanged in the remainder of <br /> the wells Changes in hydrocarbon concentrations are most likely a result of changes in groundwater <br /> elevation Additional monitoring data will be collected to further evaluate the extent of the dissolved <br /> hydrocarbon plume <br /> Additional Site Activities <br /> A copy of SECOR's "Corrective Action Plan" dated September 8, 1998, was forwarded to the County for <br /> review on September 14, 1998 The County approved the plan in faxed correspondence dated September <br /> 29, 1998 Accordingly, Time Oil intends to generate a Request for Proposal for the design, installation, and <br /> operation of a remediation system to address the hydrocarbon-impacted soils and groundwater at the subject <br /> site Upon selection of a consultant, Time will seek cost pre-approval from the Underground Storage Tank <br /> Cleanup Fund In the meantime, groundwater monitoring will be continued <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 /> �n�)r <br /> �Anastasia E Duarte-Wilkinson <br /> Environmental Toxicologist <br /> cc Ms Elizabeth Thayer <br /> California Regional Water Quality Control Board <br /> 0498%4049138 doe <br /> 2 <br />