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On December 2, 1993, the existing groundwater wells were developed and sampled <br /> Prior to purging, an easterly gradient was determined by measuring the depth to <br /> groundwater in each well (approximately 16 feet below ground surface) Analyses <br /> indicated 0 06 ppb toluene in the sample collected from W6, however, no <br /> contaminants were detected in the remaining wells Table 4 in SEACOR's report <br /> summarizes analytical results and Appendix E contains laboratory reports <br /> Conclusions <br /> Based on the results of soil samples collected during past and recent site <br /> assessment activities, it appears that the extent of hydrocarbon-impacted soil <br /> is well defined and remains limited to the area of the pump islands SEACOR's <br /> report recommends the installation of a vapor extraction system to address the <br /> small amount of impacted soil Time Oil concurs with this recommendation <br /> Based on the results of samples collected to date, it does not appear as though <br /> groundwater beneath the site has been significantly impacted by hydrocarbons <br /> Although trace concentrations of toluene were present in a sample collected from <br /> W6, the level indicated falls far below California's primary drinking water <br /> quality standards (1,000 ppb for toluene) Accordingly, SEACOR's report does not <br /> recommend the implementation of a groundwater cleanup system Time Oil concurs <br /> with this recommendation <br /> In their letter dated May 24, 1994, the PHS/EHD requested that quarterly <br /> groundwater monitoring be implemented until the investigation and cleanup of the <br /> site are deemed adequate In accordance with this request, Time has requested <br />. a cost estimate from SEACOR for the implementation of a quarterly monitoring <br /> program Sampling will be initiated during the Third Quarter of 1994 <br /> Time requests, however, that only one year of monitoring be required because it <br /> does not appear as though significant impacts to groundwater have occurred If <br /> there are no significant changes in hydrocarbon concentrations after one year of <br /> monitoring, Time will request that the PHS/EHD consider allowing the wells to be <br /> decommissioned or adjust the sampling interval to bi-annually <br /> SEACOR is currently generating a Corrective Action Plan which will contain a <br /> scope of work for the installation of an appropriate remediation system Upon <br /> completion of the report, it will be forwarded for your review if you have any <br /> questions regarding this matter, please do not hesitate to contact me at (206) <br /> 286-4495 If I am unavailable, Kevin Murphy may be able to answer any questions <br /> that you may have <br /> Sincerely, <br /> Am A sin 66�16-'4 <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/may94/4167 H4 <br /> 2 <br />