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1117 Lone Palm Avenue,Suite 201 <br /> s•� Modesto,California 95351 <br /> ATC209-579-2221 <br /> f Shaping the Future Fax:209-579-2225 <br /> 8.0 CONCLUSIONS <br /> Based on laboratory analytical results,.plume stability statistics, historical contaminant plume <br /> distribution and field observations, the lateral and vertical extent of petroleum hydrocarbon- <br /> impacted soil and groundwater are adequately defined. <br /> • The dissolved contaminants at the site are localized and exhibit a decreasing trend over the last 10 <br /> years. <br /> • Some of the soil analytical data collected over the course of subsurface investigations exceeds <br /> current ESL and RSL values. <br /> • Risks associated with soil vapor exposure, although the Johnson and Ettinger model show the risk <br /> from soil vapor exceeds the threshold of L.OE-6 and the hazard quotient exceeds the threshold of <br /> 1,the highest soil concentrations which were used in the model were from samples collected from <br /> SB7 in April 2000: Concentrations may have:decreased over time. <br /> 9.0 RECOMMENDATIONS <br /> Cardno ATC recommends collecting soil vapor samples to evaluate current risks associated with soil <br /> vapor intrusion and if the results indicate the incremental risk and hazard quotient are below acceptable <br /> levels,Cardno ATC will recommend NFA status for the site. <br /> S:Enviromental\22493\Reports\Eggiman Closure Report.doc 12 <br />