Coal mine flooding in the Lorraine-Saar basin: experience from the French mines

Soazig Corbel (1) , Joël Kaiser (1) , Serge Vicentin (1)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)

Coal mining in the Lorraine-Saar basin started in the nineteenth century. The coal deposit was mined both in France and in Germany. On the French side, mining ceased in 2004 after 150 years of activity. Once mining stopped, the water that was infiltrating from groundwater to mine operations was no longer pumped out to the surface. As a consequence, the French coal mines got progressively flooded from 2006. Three mine water pumping stations associated to treatment plants have been built on the Lorraine coal basin, to keep mine flooding under control. Since 2008, the French Geological Survey (BRGM) is carrying out the operational management of the monitoring plan that was set in place to follow closely mine flooding in the French coal mines, on behalf of the French state. This study presents the results of the entire monitoring plan for the different mine water reservoirs of the Lorraine coal basin. The actual speed of mine flooding will be compared to prediction studies, mine water quality will be detailed and content evolution of iron, manganese and suspended solids will be discussed for the different mine reservoirs. As first results, mine flooding speed varies for the different mine water reservoirs in relationship with water inflows from the above groundwater. However, the actual mine water speeds fit reasonably well the predictions made 10 years ago. Regarding mine water quality, a great care was taken to quantify all dangerous substances potentially present in mine water and only traces of a few substances have been detected. At last, content evolutions of iron, manganese and suspended solids do not fit the predictions. The concentrations are lower than expected, but decrease in a much slower way. While the French coal mines are almost completely under water, the German mines of the Lorraine-Saar basin are still running. Coal mining ended up in 2012 in Saar, but water is still pumped out to the surface to keep the mine operations dry. As the mining corporation RAG is currently in the process of an environmental impact assessment to realize a partial flooding of their mines, data and experience gained by the BRGM from the French coal mine flooding could be useful.

Mots clés: water quality; mine flooding; Lorraine-Saar basin; hard coal

Domaines: Ingénierie de l'environnement

Soazig Corbel, Joël Kaiser, Serge Vicentin. Coal mine flooding in the Lorraine-Saar basin: experience from the French mines. IMWA 2017, Jun 2017, Lappeenranta, Finland. ⟨hal-01540156⟩