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275 Grantline Rd. <br /> Page 2 of 7 <br /> underneath this strata lies 4 feet of light to medium Bark tannish- <br /> brown, damp, slightlyplastic clay; this layer is followed b <br /> least 4 feet of moist grayish-tan to tannish-brown, very fine- <br /> grained clayey sand that contains occasional pebbles. Groundwater <br /> was first encountered at a depth of appproximately 10.5 feet below <br /> grade and stabilized at a depth of 8.5 feet after 5 hours. Based <br /> on the surface topography, a very low groundwater gradient is <br /> assumed. It is estimated that the direction of groundwater flow is <br /> to the northeast. <br /> SITE BACKGROUND AND HISTORY <br /> The current business activity at the site is a video sales and <br /> rental shop. It was reported to TECO that the site was formerly <br /> used as a retail gasoline service station. Approximately 60 feet <br /> of underground product line were connected to the underground fuel <br /> P <br /> tanks with a roduct dispenser area <br /> southern portion of the Property. -pump island) located on the <br /> } <br /> present tenant, the (UST's were removed According me time einiews 1971wand hthe <br /> ad <br /> last been used to store gasoline. There were no known details of <br /> the tanks removal, contents or disposal, nor were any as-built <br /> Plans available. On July 18, 1989, TECO collected rXlr <br /> of ,the soil/water interface (vadose zone) along the !-Oil samples <br /> the area where the UST's were thought to hart been. perimeter <br /> rThe iof <br /> locations are shown as circles in the attached Figure 1. <br /> Analytical results did not indicate any concentrations of purgeable <br /> hal ocarbons above test method detection limits <br /> dated 3/15/90) . TPH as (see TFCC proposal <br /> samples analyzed but in gconcentrationswas eonly slitected p htl f the 4 soil <br /> method detection limits. A concentration of 370 slightly above test <br /> was detected in the soil sample from Boring <br /> Oil and Grease <br /> northeasterly .location and the farthest location away the most <br /> waste oil pit, y from the <br /> A 250-gallon UST that had last contained oil and <br /> grehabeen removed in 1971 and remained on site until December 6, 1989. <br /> On that date, TFCC removed and disposed of the waste oil tank in <br /> accordance with the Sart Joaquin County Health District tank removal <br /> I guidelines. Groundwater was encountered at a <br /> approximately 8.5 to 9.0 feet below surface grade. depth of <br /> SOIL EXCAVATION AND DISPOSAL <br /> On July 11, 12 and 13, 1990, TFCC excavated an estimated 220 cubic <br /> yards of oil and grease-contaminated soil from the area around and <br /> under the removed waste oil tank (see attached Figure 1) . The <br /> j soils were removed based on visual appearance of the soils. Soil <br /> contamination appeared as a dark <br /> from a dep�h of 6.5 <br /> feet to 10 feet below grade. Soil gsamplesiwere taken immediately <br /> above the groundwater interface, about 8. to 9 feet belo <br /> Groundwater was firnt encountered.at a depth of a w grade. <br /> prox mately 10.5 <br /> I <br />