Application of solidification/stabilization as a treatment technology for hazardous wastes has been hindered by the lack of a regulatory approval mechanism for solidified wastes. The Wastewater Technology Centre (WTC) has developed a protocol for evaluation of solidified wastes, which uses the performance of a solidified product in twelve laboratory test methods to recommend one of four categories of utilization and disposal. In order to facilitate acceptance of the protocol, a validation study of the test methods has been initiated by the WTC. A 63 m3 field test cell has been constructed using electric arc furnace dust solidified with an activated blast furnace slag binder system. The behaviour of the solidified waste in the field will be investigated by monitoring of leachate and testing of core samples, and compared with properties measured in the laboratory.