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contaminants were found at 20 feet None of the other samples contained <br /> detectable concentrations of gasoline or BTEX Table 2 in Canonie's report <br /> summarizes analytical results and Appendix E contains laboratory reports <br /> On November 5, the groundwater wells were developed and sampled Prior to <br /> purging, an east-southeasterly gradient was determined by measuring the depth to <br /> groundwater in each well Analyses indicated the presence of 0 55 ppb xylenes <br /> in the sample collected from W3, however, no contaminants were detected in the <br /> remaining wells Table 2 in Canonie's report summarizes analytical results and <br /> Appendix E contains laboratory reports <br /> After the installation of the wells, a vapor extraction pilot test was performed <br /> on W1, W2, and W4 to evaluate the feasibility of in-situ remediation by vapor <br /> extraction The results of the study indicate that soil vapors can be easily <br /> extracted from the existing wells and that this technology appears appropriate <br /> for site remediation <br /> Conclusions <br /> Based on the results of the soil and groundwater investigation, it appears that <br /> further action is warranted at this site Although trace concentrations of <br /> xylenes were present in a groundwater sample collected from W4, the levels <br /> indicated fall far below California's primary drinking water quality standards <br /> (1750 ppb for xylenes) Accordingly, it does not appear that the implementation <br /> of a cleanup system is warranted at this time Several quarters of groundwater <br /> monitoring may be appropriate to evaluate changes in groundwater quality <br /> Based on the results of soil samples collected during the tank removal, the <br /> findings of the soil vapor survey, and analyses performed during the site <br /> assessment, it appears that the extent of soil contamination is well defined and <br /> remains limited to the area of the pump islands The installation of a vapor <br /> extraction system should be adequate to address the small amount of impacted <br /> soil <br /> Upon securing a consultant for the above-mentioned activities , a workplan will <br /> be generated and forwarded for your review If you have any questions regarding <br /> this matter, please do not hesitate to contact me at (206) 286-4495 If I am <br /> unavailable, Kevin Murphy may be able to answer any questions that you may have <br /> Sincerely, <br /> Anastasia E Duarte <br /> Environmental Toxicologist <br /> cc Ms Beth Thayer <br /> Regional Water Quality Control Board, Central Valley Region <br /> i <br /> aed/mar93/4167 L11 <br />