Erkenntnisse aus der sanierung von stark sauren und sulfathaltigen tagebauseen am beispiel des tagebausees gräbendorf

Conclusions from the restoration of heavily acid and sulphate-containing mining lakes using the Gräbendorf mining lake as an example. With Lusatia's 16 open-cast mines till the year 1990, groundwater lowering to a depth of approx. 100 m below ground level has had considerable impacts on the situation in Lusatia as far as water management is concerned. After the closing of the open-cast mines they filled again with groundwater. The water qualities of the existing mining lakes and of those that are still to be created are often characterised by low pH values and high iron and sulphate concentrations, which, if not treated, may lead to a number of subsequent ecological and economic problems. Therefore different restoration technologies are applied to improve water quality sustainably. With 425 hectares the lake Gräbendorfer See is a mining like of medium size in which the restoration procedure applied is flooding by water imported from the river Spree. Doing this, potentials and limits of flooding with imported water have been illustrated. Therefore for sustainable restoration subsequent measures are required. The results achieved and the measures required in the future are documented and prepared / analysed / processed in a German-Polish INTERREG III A project: Presentation and assessment of the application of restoration procedures for the improvement of the water quality in mining lakes as well as of the groundwater in the euro-region and the lebusa land, which have been influenced by mining". This project will be implemented as a mirror project, i.e. each party has selected an appropriate mining lake for it. Thus we can exchange experience and technologies and, on the basis of this feasibility study (qualified task), can also tackle the joint restoration of further mining lakes.