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former tanks and appears to exist at a depth of 30 feet to 35 feet The highest <br /> concentrations of contaminants were indicated in 30-foot samples collected from <br /> Wl (SB2) , W2, and SB3 Samples collected from a depth of 15 feet in SB1 and W3 <br /> contained 200 - 300 ppm gasoline, however, samples collected at 30 feet contained <br /> less than 10 ppm gasoline Samples collected from SB4, W4, W5, and W6 contained <br /> trace to "non-detect" concentrations of contaminants None of the samples <br /> collected from depths of 40 feet to 45 feet contained detectable concentrations <br /> of gasoline or its constituents Table 2 in Canonie's report summarizes <br /> analytical results and Appendix E contains laboratory reports <br /> After the installatio of he wells, a vapor extraction pilot test was performed_ <br /> on d`�fo evaluate t eas ;cayte�at <br /> itn-situ remediation vapor <br /> extract n u n soil va ors can be easel <br /> t -axis li g we 7.s an t a o extraction appears to be <br /> app opr a e or e a <br /> Conclusions <br /> Based on the results of the site investigation, it appears that further action <br /> is warranted at this site In general, soil contamination appears to be limited <br /> to the former tank excavation and the more dense soils encountered at a depth of <br /> 30 feet Although SB4, W4, W5, and W6 generally define the extent of soil <br /> contamination and data can be extrapolated to show that contamination is limited <br /> to the area of the former tank bed, it appears that an additional boring is <br /> needed to verify that contamination has not migrated to the northeast beneath the <br /> pump islands <br /> Once the extent of soil contamination has been completely defined, a corrective <br /> action plan can be developed for the installation and operation of an appropriate <br /> remedial action plan <br /> Upon securing a consultant for these activities, a workplan will be generated and <br /> forwarded for your review If you have any questions regarding this matter, <br /> please do not hesitate to contact me at (206) 2$6-4495 If I am unavailable, <br /> Kevin Murphy may be able to answer any questions that you may have <br /> � <br /> / Sincerely, <br /> 1 <br /> l ��'/` �d/1e�V j 4 <br /> 66666 Anastasia E Duarte <br /> Environmental Toxicologist <br /> 1 ��s►'js Y1✓�/11�c4 <br /> tj, <br /> cc Ms Beth Thayer <br /> Regional Water Quality Control Board, Central Valley Region <br /> aed/may93/4049 Lt8 <br />