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. MW-8 (1 2 ppb benzene and 0 5 ppb xylenes), and MW-9 (61 ppb gasoline and 16 ppb toluene) <br /> Hydrocarbons were not detected in the samples collected from MW-7 or MW-10 Low concentrations of <br /> MTBE were detected in the groundwater samples collected from MW-2 (5 4 ppb), MW-3 (9 3 ppb), MW-4 <br /> (12 6 ppb), however, it was not detected in any of the other samples Table 2 in the attached report <br /> summarizes groundwater analytical data and laboratory reports are included as Appendix B <br /> The highest concentrations of hydrocarbons appear to remain onsite in the vicinity of the pump islands (MW- <br /> 1 and MW-3) The groundwater plume does not appear to be migrating to any great extent When compared <br /> to the October 1997 sampling event, groundwater concentrations decreased in MW-1, MW-3, MW-5, MW-6, <br /> and MW-9, while they remained relatively unchanged in the remainder of the wells Changes in hydrocarbon <br /> concentrations may be a result of changes in groundwater elevation Additional monitoring data will be <br /> collected to further evaluate the extent of the dissolved hydrocarbon plume <br /> Additional i Activities <br /> A 2-day pilot test was completed at the subject site on March 19 and 20, 1998, to determine the feasibility of <br /> utilizing vapor extraction to remediate hydrocarbon-impacted soils and groundwater at the subject site <br /> SECOR is currently compiling the results of the pilot test <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"*�� CnJ1QV"441'/__ <br /> • Anastasia E Duarte-Wilkinson <br /> Environmental Toxicologist <br /> cc Ms Elizabeth Thayer <br /> California Regional Water Quality Control Board <br /> . ap M4049134 dot <br /> 2 <br />