Evaluation and appraisal of the Wismut GmbH remediation project

Country / Region: Germany / Saxony & Thuringia

Begin of project: January 1, 2012

End of project: December 31, 2026

Status of project: August 1, 2022

Fig. 1: Tailings pond “Culmitzsch” (1991 and 2011) Source: Wismut GmbH

Since 1946 the Soviet company SAG Wismut exploited uranium deposits in Saxony and Thuringia. In 1954 the SAG became the Soviet-German company SDAG Wismut. When mining was abandoned in 1990, a total of 231.000 t of uranium had been produced. At that time, Wismut ranked number four in world-wide uranium production, following the USSR, the USA and Canada.

The mining legacy left behind by Wismut in 1990 included 32 km² operational areas, five underground mines with a total of 1,500 kilometres of open mine workings, an open pit with a residual volume of 84 million m³, 48 mine dumps with a volume of approx. 311 million m³ of weakly radioactive material and four tailings management facilities with a total of 160 million m³ of radioactive tailings (Figure 1).

In the context of German reunification in 1990, the Federal Republic of Germany has assumed the sole social and financial responsibility for the environmental remediation of these legacy sites. In December 1991 the company SDAG Wismut was converted into Wismut GmbH, a company under German corporate law. Remediation was defined as the company’s key mission and corporate purpose. The Federal Ministry for Economic Affairs and Climate Action (BMWK) represents the Federal Republic of Germany as its only shareholder. Up to now, the federal government has provided about 6.1 billion Euros to finance the remedial operations.

Fig. 2: Processing Unit Crossen (1991 and 2011) Source: Wismut GmbH

25 years have passed since the remediation operation started and the Wismut GmbH looks back at a period of successful remedial action in Saxony and Thuringia. This includes the substantial reduction of environmental impacts and the creation of conditions and prospects for economic revival, improving the quality of people’s lives in the former mining regions. A few years from now, it will be almost impossible to recognize that the remediated areas were former legacy sites (Figure 2).

However, there are still some tasks to tackle and remediation will continue until 2028. For example, flooding of two underground mines needs to be completed and several mine dumps and tailing facilities are not fully covered yet. Even after the remediation is finished, some objects will require post-remedial care, and long-term tasks will be carried out at most reclaimed sites. This includes in particular the interception and treatment of mine floodwater and seepage, maintenance of covered mine dumps and tailings management areas, the operation of a vast environmental monitoring system as well as mine inspection tasks.

In 2012 BGR has been assigned to advise the BMWK in its role of sole shareholder of the Wismut GmbH. This task involves the assessment and evaluation of the remediation operations of the Wismut GmbH. BGR provides the appropriate technical competence and expertise to successfully advise the BMWK in this framework.

Fig. 3: Back filling old drillings (Gessen valley) Source: BGR

Approaching the final phase of active remediation, most operations take place at the Ronneburg sites. Besides some long term issues such as the covering of tailings facilities and mine dumps as well as the decontamination of former operational areas, another focus in Ronneburg is to enhance Wismut’s water management and environmental monitoring facilities. This includes the extension of the water catchment system in the Gessen valley (Figure 3) as well as the construction of a new water treatment plant at the Helmsdorf site for which BGR is providing accompanying advice. A milestone was accomplished in 2018 when the final square meter of the Lichtenberg dump was safely covered, after 28 years of remediation effort. Here an area of 222 ha has turned into a valuable habitat for various plant and animal species which some of them are even protected. Cycling pathways invite local residents and visitors to appreciate this new landscape.

A major task at the Aue site is the completion of the drainage gallery at the "Markus-Semmler-Sohle". Since the cut-through to the medieval "Marx-Semmler-Stolln" was established end of 2014, subsequent gallery lining and ventilation measures dominate the underground activities. Further measures above and below the ground aim to mitigate the radon exhalation at the site.

At the Königstein site the ongoing licensing procedure for the final flooding of the closed mine is still a crucial factor for the future development of the site. Major activities above ground in Königstein focus on the sustainable rehabilitation of the site, including the completion of a new water treatment plant as well as a centralized office building.