The removal of organics and volatile metals from soils using thermal desorption comprises moving contaminated materials, positioned on a belt conveyor, through a chamber (32) under oxygen conditions, temperature conditions, and residence time effective to substantially avoid incineration of the contaminants, while volatilizing the contaminants and producing a processed material that is substantially decontaminated, where the volatilized contaminants are carried from the chamber (32) by a transport gas which is passed through a packed tower (70) where quench/scrubbing liquid flows countercurrent to gas flow, for producing a substantially cleaned gas and a contaminated liquid concentrate. The gas may be passed through a further gas cleaning system (86) prior to discharge into the atmosphere, while the liquid concentrate is passed through a water treatment system (90) for producing substantially cleaned water which may be passed through an air cooler (92) and recycled back to cool the processed material. Steam from moist contaminated material can be used as a cocurrent transfer gas.