The SAFIRA project has been set up to examine and further develop in situ groundwater decontamination techniques. The Bitterfeld region was selected as the model location for investigations into developing in situ technologies for the remediation of complex contaminated groundwater. The principal site-specific investigations have been completed and the main contaminants characterized. The location was found to be suitable for a pilot plant and the fundamental mechanisms for removing the "pollutant cocktail" are now known; degradation experiments have been scaled up. The methods tested successfully in the laboratory and in the mobile decontamination unit to prove their chemical and hydrological long-term stability will be competitively optimised in a pilot plant under real-world conditions.