Remedial measures following accidental release of dioxin

Abstract

The remedial measures required to clean up buildings and land following the accidental release of a chlorinated dioxin or similar compound are in principle similar to those required for any site which has been contaminated by past industrial use. In this paper we attempt to combine the considerable experience of the Hazardous Materials Service of the Harwell Laboratory in tackling these more general problems, with our specific experience of applying our expertise to the situation at Seveso, to make some general comments and recommendations.A localised but very difficult problem following an accident such as that at Seveso is how to decontaminate, dismantle and dispose of the chemical plant itself. Broadly, the alternatives are to entomb the entire plant in a monolith; to comprehensively decontaminate the plant, so that the equipment may be disposed of as ‘clean’; or to dismantle the plant in such a way that the highly contaminated materials are contained within the vessels and pipes, which are then disposed of directly. In general we would recommend this third option of direct disposal as it minimises handling of the most toxic materials whilst still offering long term security provided that a safe disposal option is available.As regards cleaning up land contaminated following an accident, the essence of effective response must be preplanning and speed. Thus we stress the importance of contingency planning, which should specify, inter alia, the methods to be used for investigating the extent of contamination; and the methods to be used for immediate decontamination while the dioxin is still attached to vegetation and thus open to degradation by the sunlight. Once the contamination has been washed into the soil, then there is little alternative to surface stripping in the more contaminated areas. In areas of lesser contamination a technique such as deep ploughing may be useful.