Environmental Remediation of the Wismut Legacy and Utilization of the Reclaimed Areas, Waste Rock Piles and Tailings Ponds

Abstract

Between 1945 and reunification (1989) of Germany more than 232 000 t of U3O8 has been produced in Saxony and Thuringia, East Germany. This affected an area of approximately 100 km2 and left behind an extensive legacy of contaminated operations areas, underground and open pit mines, waste rock piles and tailings ponds. Following reunification, DM 13 billion (€ 6.6 billion) were committed (and later revised to € 6.2 billion) to remediation of the liabilities and the government owned corporation, Wismut GmbH entrusted with the implementation of the Environmental Remediation (ER) of the liabilities. The prime goal of the ER Project follows from the legal requirements to abate health risks, mitigate existing and prevent future environmental damages. During the investigations and assessment of risks, development of remediation concepts, adoption of suitable technologies and work procedures as well as physical implementation of the remedial measures extensive use was made of international (mostly US and Canadian) ER experience. The extent of remedial measures was based on object-specific Environmental Assessments rather than on uniformly applied health/environmental standards. The ER workflow is more an iterative process than a linear succession of tasks, such as common for civil engineering projects. The internal (technical) parts of the problems were partly resolved by using Conceptual Site Models (CSM) for selection and prioritization of remedial measures. Reclamation of the waste rock piles is by covering in situ, relocation to a central pile or backfilling into an open pit. The backfilling of the open pit at Ronneburg with acid generating waste rock has been optimized from a geochemical point of view. For tailings ponds reclamation in form of dry landforms is being followed. To increase release (and reuse) of scrap metal from demolition, a fast and reliable method of discrimination of the non-contaminated metal has been developed. The flooding of underground mines is carried out in a controlled way. Both the reclamation works and the environmental base line are subject to thorough monitoring. An important part of emissions control is the monitoring of the seepage from waste rock dumps, discharges from the tailings ponds and of the discharge from mine flooding. The numerous decentralized on site data basis are accessed at the corporate level by means of an ORACLE based holding data base, which allows fast overviews, specific data quires and overlaying of different types of information and data to answer multifaceted questions. Utilization of the reclaimed areas and objects is becoming an important part of the considerations in the present phase of the project. This is due to the fact that the Wismut legacy is located in former mining districts, which are presently depressed and ER is an important factor in creation of an environment conducive to economic revival and infrastructure development. Concerning utilization, there are no legal restrictions placed on areas completely cleaned up of contamination. The utilization of partly reclaimed areas, waste rock piles and tailings ponds is regulated and restricted to settlement of industry and trades or to forestation. Exemptions, however, are possible if the owner takes on the responsibility for long term monitoring and maintenance. Successful examples of integration of reclamation plans and communal development are provided by rebirth of the health spa in Schlema and by the former mining town of Ronneburg expected to host the Federal Garden and Landscape Exhibition in 2007 (BUGA 2007).