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1 <br /> 1 <br /> points outside and within the Tesoro tank farm for assessing <br /> potential leakage from the gasoline and diesel storage tanks and <br /> ' associated pipelines. If the gasoline leakage was emanating from <br /> a leaking tank or pipeline within the tank farm, floating product <br /> would have been found in one of the test holes . Figure 3 illus- <br /> trates product thickness measurements conducted on March 23 , <br /> ' 1988 . <br /> ' A floating product was measured in TS-7 ; however, it was <br /> determined to be old material rather than new gasoline. The <br /> material appeared black and had a pungent odor rather than a <br /> sweet odor typical of new gasoline. The location of the test <br /> hole ( in Tesoro' s paved service yard) suggests that the material <br /> ' found in the test hole may have leached from the asphalt pad to <br /> the groundwater . <br /> No hydrocarbon layer has been observed in the two monitoring <br /> wells. The wells are sited at key locations for detecting conti- <br /> nued migration of the hydrocarbon plume onto the Tesoro site. <br /> ' The wells will be monitored for this purpose. <br /> Laboratory Analyses <br /> The analytical results on the water and product samples <br /> collected from the eleven exploratory test holes, the two moni- <br /> toring wells, and the test hole SP-3 along the Southern Pacific <br /> pipeline right-of-way are presented in Table 4 . The water <br /> samples were analyzed for total petroleum hydrocarbons and for <br /> benzene, toluene, ethyl benzene, and xylene. Product samples <br /> were analyzed for chemical composition. Laboratory reports and <br /> chromatographs are presented in Appendix D. <br /> - 14 - <br />