Restoration of the areas environmentally contaminated by the Olen radium facility

Ore with a uranium oxide content of about 50% was discovered in 1915 in the former Belgian Congo. The first ore arrived in Belgium in 1921 and in 1922 radium production began in Olen. Production continued there until the mid-1960s. In 1989 and 1990 media coverage of very high contamination in the village of Sint-Jozef-Olen resulted in a detailed radiological characterization of the contaminated areas and an evaluation of their impact on the population exposure. A follow-up committee was established with all the parties concerned. The committee requested several additional studies resulting in a growing consensus of opinion in favour of a global restoration plan. The major contaminated sites in the vicinity of the former radium facility were: the brook receiving the liquid effluents (Bankloop), a dump (the D1 dump) with mixed radium and chemical waste, nine or ten stretches of road with contaminated paving and a dwelling with contaminated material under the veranda. The principal argument in favour of restoring the sites was not the current population exposure, but the fact that most scenarios concerning the use of the contaminated areas envisage enhanced exposures to future generations. The worst scenario was the integration of the D1 dump into a residential area resulting in radon doses of a few tens of mSv/a. The radiological assessment of five options to restore the D1 dump used as selection criteria: the cost of the restoration, the surface area of the new storage facility, the collective dose of the intervention workers, and the individual dose for people who will be living above the storage facility after the period of institutional control. The best solution retained consisted in displacing the waste to a nearby place (with the radioactive waste under the chemical one) and applying a multilayer cover. The cost for the global restoration plan was estimated at 9 M Euros, 75% of which would be earmarked for restoring the D1 dump and constructing the storage facility, 17% for cleaning up the Bankloop, and 8% for radiation protection measures. Only the contaminated farmland at the mouth of the Bankloop would not be cleaned up. It would be subjected to institutional control to prevent specific exposure pathways such as the production of crops for direct human consumption or the incorporation of the contaminated zone into a residential area.