is turning old mines into lakes

The energy transition has a hidden side that often remains in the background: it is not only saying goodbye to fossil fuels but also thinking about what to do with these degraded lands after years of extractive activity. The mines. Leaving these exploited lands to their fate is a waste in every sense. Germany knows this and has promoted the largest landscape intervention in Europe: the Lusatian Lake District.

You can see it better in the photo that illustrates this article: the before and after: what began as a network of huge open-pit coal mines is being transformed into a complex system of more than 20 interconnected artificial lakes, a true vacation paradise for sailing or taking a bike ride. In fact, You can now book a getaway over there.

The project. Between Berlin and Dresden, Germany is transforming one of the most degraded landscapes in Europe into the largest system of artificial lakes on the continent: Lausitzer Seenland. This is a conversion project of old open pit lignite mines in a network of 23 lakes that occupy 13,600 hectaresten of them connected by navigable canals forming a continuous area of ​​7,000 hectares.

The state-owned company LMBV Lausitzer und Mitteldeutsche Bergbau-Verwaltungsgesellschaft) oversees the technical execution, which includes the creation of tourism infrastructure, such as beaches, ports, cycling and camping areas, along with state-of-the-art facilities. The process is long and need a lot of money: Going from a mine to a long-term safe lake costs between 200 and 600 million euros and in Lusatia alone it has already cost 7 billion euros.

Why is it important. This project represents the largest environmental restoration effort of post-mining landscapes in Europe and constitutes a relevant case study for the rehabilitation of degraded areas. As collect this analysis from the German Federal Environment Agency, 19 of these lakes have already achieved good/high ecological potential. That is, recovery is possible.

Beyond ecological recovery, the lakes also fulfill water management functions: during 2018, more than 62 million cubic meters were released from the lakes to raise low levels of the Spree and Schwarze Elster rivers during drought, such as collect the local media Niederlausitz Aktuell. The project also has significant socioeconomic implications: the government has destined 40,000 million euros to promote this transition from mining in the eastern coal regions towards other vectors such as sustainable tourism.

Context. At the time of the German Democratic Republic were extracted more than 2,000 million tons of lignite from depths greater than 60 meters, leaving enormous craters in the landscape. Lusatia was the country’s gasoline: in 1989, lignite production there reached 195.1 million tons. In total, open pit mining of lignite has devastated 179,490 hectares in Germany.

German reunification in 1990 marked a before and after. The fall in energy demand and that the Federal Environment Agency will classify it Since lignite is the most polluting fossil fuel, it brought about a progressive dismantling of its mining. During the 1990s the LMBV was tasked with restoring 19 open pit mining areas in Lusatia. As explains Dr. Uwe Steinhuber of LMBV, it will take at least two generations to complete it.

How they do it. The rehabilitation of Lusatia is supported by geotechnical stabilization and active hydrological control, such as collects LMBV in this report. To transform mining craters into safe lakes, it applies deep vibration compaction techniques that prevent liquefaction of sandy soil, while accelerating filling through controlled diversion of flows from the Spree River. The process is monitored by the Copernicus satellite, which detects ground movements.

Water chemistry is the other great technical challenge in that the oxidation of pyrite causes extreme acidification such as documents the Canadian Journal of Soil Science. To neutralize it, they use treatment plants and ships, which allows them to reach the quality standards of the Federal Environment Agency.

Yes, but. We have already seen that the calendar is long and the budget astronomical, but LMBV warns that still remains: at the moment they have invested 7,000 million euros, but the total cost of the project (which includes other regions) amounts to 13,800 million. The entire process will end in this decade, but it will be necessary to apply surveillance in the coming generations, both for contaminants and the geological stability of the area.

Despite all efforts, rehabilitation is far from ideal: of the 36 lakes assessed by the Federal Environment Agency (which includes other lakes outside the tourist district), 12 they got “moderate” classification due to mercury or endocrine disrupting compounds such as tributyltin and one presented “poor” status due to excess nutrients. There is scientific evidence which support that mining soils present severe physical, chemical and biological limitations that make complete ecological restoration difficult.

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Cover | Tourismusverband Lausitzer Seenland (Steffen Rasche)