Test thresholds for assessment of possible groundwater contamination at sites contaminated with radioactive materials

At several sites in Brandenburg the ground is contaminated with natural radionuclides, especially thorium from former industrial processes. Such type of contamination is regulated neither in the Federal Ordinance on Soil Protection and Contaminated Sites (BBodSchV) nor in the German Radiation Protection Ordinance (StrlSchV). However, the European Basic Safety Standards Directive specifies that areas of a former practice or work that are a source of permanent risk to people have to be demarcated and controlled. If necessary, intervention measures need to be carried out and access must be restricted. Therefore treatment of such cases requires technical regulations and supporting instructions to facilitate correct decisions by the relevant authorities. Such regulations must conform to the existing regulations, especially the BBodSchV and guidelines of urban land-use planning. When assessing existing situations, the groundwater exposure pathway is of particular significance for any decision-making. Suitable criteria and instructions were derived in order to identify for this special pathway those areas that can be considered uncontaminated and therefore exempt from further radiological investigations and from any restrictions concerning land-use planning. The methodical approach corresponds to the leachate forecast according to BBodSchV. The results obtained are presented in the paper. (author)