The Schlema-Alberoda site is located in the southwest of Saxony, to the northwest of Aue. During the production phase from 1946 to 1991, this site produced approx. 80,000 tonnes of uranium. Rehabilitation of the mines around Aue is a huge challenge as the underground workings total 60 levels reaching down to –1800 m.
The situation at the vein deposit around Aue is characterised by a multitude of near-surface cavities created during the early years of mining and which had to be reopened and backfilled as part of the remediation effort. Contaminants had to be removed, adits and day shafts were filled and sealed. As underground cleanup advanced, demolition and disassembly of surface structures and buildings could be addressed.
When the pumps were switched off in 1991, this meant the finale of underground mining: flooding of the mine workings. The existing technical facilities for mine water pumping and treatment are a prerequisite for controlled flooding of the mine. By 2008, the major part of cavities is flooded in the Schlema-Alberoda mine field. The level of the flood water has risen to less than 25 m below the Markus-Semmler- Stolln gallery. This drainage gallery was developed in the Middle Ages and allowed drainage of the copper, silver and cobalt mines of the Schneeberg and Schlema districts for several centuries. It is still used today as a drainage system and serves to minimise radon levels in the Schlema valley. Within a couple of years, the flood level will gradually approach the spillover level into the Zwickauer Mulde River which is at 323 m a.s.l.
The Aue Operations Office also oversees remedial action at the Pöhla mine field. It includes the Pöhla-Globenstein, Hämmerlein, and Tellerhäuser subsites in the upper range of the Western Ore Mountains near the frontier with the Czech Republic. Mine cavities totalled some 1.2 million m³. Following completion of clean-up, mine flooding at this site was initiated in 1992. Flooding of the mine was complete in 1995 when the flood water level had reached the adit level.
