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P _L j I r i blarding Lawson Associates "-'`• ground water. Suggested clean-up levels take into account cal characteristics of surface and subsurface feature physi- cal characteristics of the gasoline hydrocarbons. , and chem- ' 5oi1 - Important factors to consider when establishing # gasoline hydrocarbon clean-uplevels is in sc3.ls are the potential for hydrocarbons to leach from soil into ground water, and the current or potential uses of ground water that would be compro- mised. . _ The State of Califarn' F �� is s Leaking Underground Fuel Tank" (LUFT) field manual has a series of work sheets t� available to assist in determining the leachin aching 'potential of gasoline hydro- I carbons in soils. These work sheets take into account depth to i I ground water, average annual. precipitation, and physical chara - l, c , i. teri;stics of lithology (i.e fractures, coarse soil s, etc) . The work sheet for fiche Grant Line Road site (Plate 6 indicates a high ) g potential for gasoline hydrocarbons in shallow soils to leach into shallow ground water. The .nain z teason for this high potential is ,ver y shallow groukld water at the site. ., Our analyses indicate that all soils containing concentrations ! z r above 0.3 Parts-per-million (pP ) of BETXand/or 10 p Pm TPH would remric { " .... c { . The LUFT manual also points out that lower clean-up r f levels MAY be acceptable on a site-specific basis.+ At the Grant 3 ( �: iine Road site, the.ground water is confined to a rather thin �t y3 pcUr1Y" Yielding strata: In addition, most of the area of maximum } 4 f hydrocarbonconcentration in-'soil isf completely covered with asphalt or concrete. These materials will greatly reduce i infil- 17 A