Historical mining, uranium tailings and waste disposal at one site: Can it be managed? A hydrogeological analysis

Hydrogeological investigations of a uranium tailings impoundment in Johanngeorgenstadt, Saxony, Germany are being conducted. The objective of the hydrogeochemical and isotopic investigations is to distinguish between different groundwater types. The area is characterized by near-surface historical mining. Since 1982 municipal waste has been dumped onto the tailings material. Three aquifers can be distinguished at the study site: the interface between the waste and the tailings the interface between the tailings and the weathered surface layer zone of mine backfilling A comparison of this site to another tailings site which is only covered by vegetation shows the effect of the waste cover on the concentration of heavy metals, especially uranium, in the seepage water. The waste produces reducing conditions under which uranium is relatively immobile. Higher concentrations of uranium are found in the seepage waters of the tailings site without a waste cover.