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�r � ��;•- �,.-„,�.''�� j �� ,� -�'� fi�� i�'$"� .�,� �' ew_ p���,,,y -s�S�'+;� �'mac+ ..._�'Fr �w <br /> i <br /> $ of 6 Pages <br /> E� <br /> CONTAMINATION <br /> Soil <br /> k The site geology indicated a relative uniform series of beds <br /> layered horizontally at the site. Therefore, we do not believe <br /> +” any bedding plane migration of the fuel took place therefore, <br /> most of its movement was vertical. Naturally th_-r::� would have <br /> been some lateral movement due to advection during rainfall <br /> �s infiltration and minor interflowing. For the most part the <br /> contamination is located in the general area of the old <br /> excavated tanks and the old dispensing islands. We project, <br /> using our Electromagnetic Induction and well data, the <br /> extent of the contamination is located inside of the 100 mmho <br /> line which is shown with hatch marks on the Horizontj <br /> Contamination Map. U 0 <br /> Boreholes BM-2 & 3 showed no soil contamination at all; borehole <br /> BM-1 had considerable contamination, and was contaminated down <br /> to the water table. However, no free product or scheen was <br /> noted on any of the samples. As expected higher concentrations <br /> of fuel were found in the finer--grained material owning to their <br /> greater porosity. <br /> Water <br /> The ground water shows hydrocarbons in all wells. The greatest <br /> amount is located in well BM-1. Although no free product was <br /> noted a nig',i amount of Total Petroleum Hydrocarbon was found at <br /> this paint, lesser amount were found in wells BM-2 & 3. The <br /> profile of the ground water plume is generally as would be <br /> expected from the measured hydraulic gradient. Since historiorl <br /> ground water data indicate a gradient different from the one <br /> measured at the site, it would be reasonable to expect the water <br /> flow direction to change from time to time. If this change is <br /> seasonal the migration distance from the site will not be great <br /> but more concentrated at the site. <br /> MITIGATION <br /> If, upon review by the San Joaquin Local Health District, the site <br /> +w• requires mitigation, we believe it will be far to costly to <br /> excavate the contaminated soil and treat it properly. Possible <br /> � < approaches to a realistic mitigation plan will probably require <br /> soil vapor extraction and possibly ground water treatment. <br /> Yours Truly, <br /> John Cussen <br /> rr, <br /> President <br /> s <br /> Richard Merriam <br /> Certified Engineering <br /> j ' Geologist #$BO <br />