Decontamination of drill cuttings and other waste material

Drill cuttings (2) are delivered from a hopper (3) onto a conveyor belt (4) which moves in the direction of the arrow (A). Steam is passed under pressure from a steam nozzle (8) through the conveyor (4) and the drill cuttings carried thereon. The steam is generated in an oil fired boiler (9). Thereafter the drill cuttings are subjected to a bioremediation step. A C:N:P ratio of the drill cuttings is monitored at least one during the method and the ratio optionally altered to provide an optimum C:N:P ratio for microorganism activity. Steam treatment drives off mobile oil fractions in the drill cuttings and additionally conditions the waste material for the performance of either indigenous microorganisms or subsequently added innoculum.