Patent ID: 8864412

Claim:
A method for remediating a surface layer of permeable porous contaminated soil containing a contaminant, comprising: excavating contaminated soil from the layer to form a pit having bottom and side surfaces; lining the bottom and side surfaces of the pit with an impermeable, heat-resistant, flexible liner to form an open topped containment chamber; substantially covering the bottom of the containment chamber with an array of generally parallel, spaced apart, substantially horizontally extending, elongate heating assemblies, each assembly comprising an electric resistance heater positioned within a tubular perforated screen operative to exclude soil, the heater and screen combining to define an elongate horizontal passageway therebetween; installing means for supplying electric power to the heaters; installing means for supplying solvent, for the contaminant, to the elongate passageways; installing means for removing heated liquid from the containment chamber; filling the containment chamber with contaminated soil from an adjacent area to provide a charge for processing; pumping solvent for the contaminant into the elongate horizontal passageways; operating the heaters to vaporize solvent present in the elongate horizontal passageways, thereby producing hot solvent vapour that rises, through the screens, convectively heats the charge, condenses and combines with the contaminant to form a mobile heated liquid that drains downwardly; and recovering drained heated liquid from the containment chamber using the removal means.