Strategies for follow-up care and utilisation of closing and flooding in European hard coal mining areas

Abstract : The already implemented or near end of mining in the European hard coal mining areas will cause the rise of the water table which had been kept down for mining activities, and will finally re-establish the contact with the groundwater layers near the surface. This flood water causes contaminations of groundwater used for drinking water and therefore calls for immediate action, because of the in part high salinity and concentration of mobilisation products from the oxidised rocks. On the other hand the long-term process offers new options for discharge optimisation and utilisation. The FLOMINET project carried out within the frame of the European RFCS program develops numerical models to forecast the impact of regional mine water rebound on mine, ground and surface water in interconnected underground hard coal mines. The research is also dedicated to the industrial utilisation of the rising mine water for renewable energy in form of electricity and geothermal heat. For this purpose numerical models have been enhanced in terms of density and temperature to become a practical planning tool for these activities. One additional application is the appraisal of gas reservoirs for methane gas extraction, the influence of the flooding process on such extraction, and the forecast of risks originating from mine gases dissolved in water after mine flooding.