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i <br /> Mr. J. Kelly Williamson <br /> Kayo Oil Company <br /> April 8, 1985 <br /> Page 2 <br /> A petroleum odor and an LEL reading up to 50 percent aas detected in - <br /> MW-1 at a depth of 20 feet. A slight petroleum odor at a depth of 15 <br /> feet in MW-2 was noted, accompanied by a 2 percent LEL reading. No <br /> hydrocarbons were detected in MW-3 and MW-4. The soil sample collected <br /> in MW.-1 at a depth of 19.5 feet was analyzed by IT Stoner Analytical <br /> Laboratory using the EPA 602 method. Laboratory results are shown in <br /> Table 1. <br /> The soil profiles were characterized by sandy silt (ML) with inter- <br /> layered silty sand. A silty clay (CL) was encountered in MW-4 at a <br /> depth of 18 feet. <br /> CONCLUSIONS AND RECOMMENDATIONS <br /> Hydrocarbons were detected in the soil samples from DH-1 and MW-1, <br /> located in or within 10 feet of the tank backfill. Borings along the <br /> perimeter of the tanks were clean. The hydrocarbons were found to <br /> extend to a total depth of approximately 20 to 25 feet. The size of the <br /> contamination plume is small, and no "free product" was encountered in <br /> the Soils. Ground water is at a depth of approximately 50 feet (spring <br /> 1984) in the general area of the site, based on information provided by <br /> the San Joaquin County Flood Control District. <br /> We recommend quarterly monitoring for vapors and for possible accumu- <br /> lation of liquids. <br /> We trust the information contained herein meets your needs at this <br /> time. If you have any questions concerning this work, please feel free <br /> to contact me at our Martinez, California, office (415) 228-8400. <br /> Very truly yours, <br /> Thomas 0. Shoff <br /> Pr 'ect Manager <br /> Robert M. Galbraith, R.G. 3881 <br /> Manager, Geotechnical Services <br /> TDS:jc <br /> -- 0026 _ --- --- <br /> Attachments <br />