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11"W V <br /> EVALUATION OF REMEDIAL ALTERNATIVES <br /> As directed by the SJCPHS in a letter received in December 2000, an evaluation of "other remedial <br /> alternatives for groundwater cleanup"was conducted to address current site conditions. <br /> This review included the following technologies: air sparging, slurry wall, interception trench, in situ <br /> oxidation, and groundwater extraction. Based on a review of the hydrogeology at the site, monitoring and <br /> natural attenuation is considered as the only viable option,given current site conditions. <br /> Current hydrogeologic conditions limit dissolution and transport of hydrocarbons in the saturated zone. <br /> This has allowed natural attenuation processes to effectively limit the migration of hydrocarbons. The <br /> primary process limiting hydrocarbon transport downgradient is biodegradation. It has been shown that <br /> this process can limit migration of hydrocarbons from the source area. Natural attenuation is the proposed <br /> remedial alternative for the site. <br /> The submerged residual hydrocarbons entrapped in the saturated soil matrix achieve equilibrium by <br /> conserving surface area and adhering to the soil. The transfer of submerged residual hydrocarbons into <br /> groundwater is a very slow diffusion limited process that does not generally produce significant <br /> concentrations of hydrocarbons in groundwater beyond the immediate source area. <br /> G:N je \73962TUBLIC gmmingVeXUAW 3 <br />