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MC <br /> The 150 cubic yards of hydrocarbon impacted soil remaining in the subsurface will remain <br /> in place The depth to groundwater during 1995 at the Hi Hopes property was reported <br /> to be approximately 75 feet or more below ground surface (Table 1) Groundwater is <br /> approximately 35 feet below the documented base of the remaining hydrocarbon impacted <br /> soil left in place (Exhibits 5, 6, and 7) <br /> The State of California Water Resources Control Board and Department of Health <br /> Services Leaking Underground Fuel Tank (LUFT) Field Manual Guidelines for Site <br /> Assessment, Cleanup, and Underground Storage Tank Closure, 1989 manual provides a <br /> soil leaching potential analysis methodology for gasoline and its fuel components (Exhibit <br /> 9) This methodology is used to establish concentrations of gasoline fuel and its <br /> components that could by left in place without threatening groundwater The leach <br /> potential analysis is applicable to the hydrocarbon impacted soil left in place within the <br /> subsurface at the HE Hopes property because of the relative small volume of impacted soil <br /> . and the relatively low hydrocarbon concentration levels <br /> As shown on Exhibit 9 the analysis for this site indicated a score for the Hi Hopes site of <br /> 43 points out of a possible 50 and suggests that maximum levels of benzene, toluene, <br /> ethyl benzene, and xylene that can be left in the subsurface are 0 3, 0 3, 1, and 1 mg/kg, <br /> respectively (Exhibit 9) Total petroleum hydrocarbon as gasoline fuel concentrations in <br /> soil that may be left in place is 100 mg/kg Concentrations of hydrocarbon impacted soil <br /> left in place on the Hi Hopes property are at concentrations at or below the LUFT score <br /> guidelines based on analysis of samples from borings and the excavation <br /> Based on historical data developed during interviews with people familiar with the Hi <br /> Hopes property, observations of the nature and character from soil samples collected from <br /> exploratory soil borings and excavation sidewall and floor samples and concentration <br /> ratios of benzene to xylene and benzene to total petroleum hydrocarbon as gasoline fuel <br /> the gasoline spill appears to be old <br /> • 08220010 011 35 <br />