A containment chamber is constructed by excavating a pit at the site of oil-contaminated sand and lining the pit with an impermeable, heat-resistant, flexible plastic liner. An array of spaced apart heating assemblies is positioned to cover the bottom of the chamber. Each heating assembly may include an elongate linear electric resistance heater positioned within a tubular slotted sand screen. The containment chamber is filled with a charge of contaminated sand. Solvent, such as diesel fuel, is pumped into the elongate passageways defined between the heaters and screens. The heaters are actuated to vaporize the solvent, which moves through the screen slots and convectively permeates the charge. The vapor transfers heat to the oily sand and condenses. Condensed solvent and heated oil drain and are recovered from the chamber.