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Mr. J. Kelly Williamson <br /> Kayo Oil Company <br /> April 8, 1985 <br /> Page 2 <br /> were surveyed and monitored to determine .the ground water gradient. <br /> Approximately 1/8 inch of product had a cumulated on the water table in <br /> MW-1 since it was drilled in the ori incl investigation. A slight <br /> petroleum odor was noted in the groundw ter in MW-6 -and MW-7. <br /> The soil profiles were characterized by silty sand (SM) and sandy silt <br /> (ML), with interlayered sand (SP/SW) and sandy clay (CL). A strong <br /> petroleum odor, accompanied by an LEL reading of 55 percent, was <br /> detected in the soil at a depth of 35 feet in MW-7. The only other <br /> detections of hydrocarbons in the soils above the ground water occurred <br /> at a depth of 35 feet in MW-6 and MW-9, egistering 5 and 4 percent LEL, <br /> respectively. The soil sample collected in MW4 at a depth of 35 feet <br /> was analyzed by IT Stoner Analytical Laboratory using the EPA 602 <br /> method. Laboratory results are shown in Table 1. <br /> CONCLUSIONS AND RECOMMENDATIONS <br /> The ground' water gradient is relative' y flat, but does appear to be <br /> oriented in a southwesterly direct on, as shown in figure 2. <br /> Hydrocarbons have been detected at the water table in MW-1, MW-6, and <br /> MW-7. The highest accumulation of hyd ocarbons occurred in MW-1, with <br /> 1/8 inch of production the water table. We recommend collecting a water <br /> sample for the domestic well on the site and having it . analyzed for <br /> hydrocarbons to determine if the drinking water has been contaminated. <br /> All the wells should be monitored and purged on a weeky basis for six <br /> months to further evaluate the size of the problem. Samples have been <br /> collected and are being analyzed to determine if biological stimulation <br /> for complete removal of residual hydrocarbons by bio-oxidation is a <br /> viable option for cleanup at this site. <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 D. Shoff Robert M. Galbraith, R.G. 3881 <br /> Project Manager Manager, Geotechnical Services <br /> TDS;3c <br /> 0028 <br /> Attachments <br />