Remediation and restoration of a thorium and radium contaminated site

This paper describes the remediation and restoration of approximately 130,000 square metres of derelict land in East London, contaminated with radioactive and chemical substances. The land had been the location of a chemical plant operated under different owners for about ninety years. The plant was demolished in the 1970's and lay derelict for approximately 10 years. This site was bought by developers in the late 1980's with the intention of constructing a residential complex, and therefore had to be cleared of contamination such that it could be released for unrestricted use. This paper provides an overview of the initial radiological status of the site, the methodology and safety measures adopted for the decontamination operations with emphasis placed on the various radiological monitoring and sampling regimes and techniques employed for: a) providing on-going evaluation of the decontamination progress, b) the radiological characterisation of the waste arisings in order to identify various available disposal routes, c) ensuring safety for both operators and members of the public during decontamination operations, d) ensuring compliance with the radiological end-point agreed with the authorising department (HMIP) as the final stage of the restoration. (author) 5 figs