Release of Contaminants from Uranium Mine Waste – Laboratory and Field Experiments

Abstract.

The Königstein Uranium Mine was closed in 1990, ending uranium production in the former GDR. As a result of the mining operation, a dump of about 4 × 10⁶ m³ was left at Schüsselgrund valley near Königstein. As part of the reclamation of the mine and the dump, abandoned equipment, radioactive soil, and building wastes will have to be disposed of. The aim of this investigation was to define the characteristics of the abandoned materials and mine wastes in order to identify a suitable remediation approach for these materials. It was important to evaluate their long-term behaviour in order to determine if it would be safe to dispose of the abandoned materials in the Schüsselgrund mine dump before closing and covering it. After in-situ remediation of the dump, groundwater will become the most important pathway for the migration of radioactive and toxic contaminants into the environment. If the disposal of the abandoned materials significantly increases the risk of contaminant potential or release, safer disposal strategies will have to be found. The investigation focused on the potential geochemical interactions, the mineralogical characteristics, and the time scales of fixation/release of contaminants from the wastes. To evaluate chemical interactions of contaminants and dump material, a total of 19 columns and 5 field tests were installed. Experiences from three years of experiments are reported.