Laserfiche WebLink
Working To Restore Nature <br /> May 4, 1993 <br /> Unocal Station No 6981, Stockton, California <br /> sediments underlying the existing fuel UST's and dispensers appears feasible <br /> Implementation of this alternative will require the installation of two additional shallow <br /> vapor-extraction wells, subgrade piping, and installation and operation of vacuum extraction <br /> and abatement system Removal of the existing UST's will not be required, and the method <br /> is less disruptive to operations at the site than excavation This method is also not <br /> contingent on weather conditions and can be performed at any time during the year <br /> 53 Ground-Water Remediation Options <br /> I <br /> Based on the size of the site, the size of the plume, dissolved hydrocarbon concentrations, <br /> and the type of sediments present at the site, in-situ bioremediation, chemical oxidation, and <br /> slurry wall containment are not viable or economically feasible options The following <br /> Ile feasible options are presented <br /> 5.3.1 No Action/Monitor <br /> 1 <br /> At this time, dissolved gasoline and BTEX concentrations exceed Primary and Secondary <br /> MCUs However, the concentrations have shown marked decreases, probably due to the <br /> adsorption of the dissolved compounds associated with the drop in ground water Therefore, <br /> I it may be feasible to monitor the ground-water gradient and quality periodically through <br /> source removal and site closure without active ground-water remediation Data obtained <br /> during the monitoring will be used to verify 1) the ground-water gradient, 2) that dissolved <br /> gasoline and BTEX do not migrate farther offsite, and 3) that the dissolved gasoline and <br /> r <br /> BTEX concentrations in ground water decrease with the remediation of the overlying soil <br /> If dissolved hydrocarbon concentrations do not decrease after source removal, active <br /> remediation may be required <br /> r � 3W32-13 11 <br /> A <br />