Abstract: A method for ex situ cleaning of contaminated soil using a closed system of heat-conductive solid-walled pipes embedded in the contaminated soil, the pipes being in communication with the heat source that heats and circulates air throughout the system of pipes, the method having the following steps of placing the contaminated soil in a heap on the pipes, substantially enclosing the soil heap with a vapor barrier, circulating heated air throughout the pipes to elevate the temperature of the surrounding soil to a temperature sufficient to cause vaporization of soil contaminants, extracting the vapor containing soil contaminants from the enclosed soil heap, and treating the vapor to remove contaminants and recycling the vapor.