A method is provided to remove contaminants from contaminated soil. The method may include withdrawing vapors from a vapor extraction well, estimating the amount of water vapor removed from the contaminated soil in the vapors being withdrawn from the vapor extraction well, and applying heat to the contaminated soil from a plurality of heater wells at a rate not greater than that which would vaporize the estimated amount of water vapor. The permeability of the soil may thereby increase by the application of heat. Six or more heat injection wells may be provided for each vapor extraction well, and the heat injection wells may be placed and energized in a regular pattern around the vapor extraction well, which may include multiple rings of heaters around each vapor extraction well.