International audience The cessation of underground mining in the Lorraine iron ore basin and the stop of the dewatering pumping have induced a quick rise of the flooding level in the mine reservoir. In a particular sector, where the outcrops meet the Orne valley, this caused an appreciable rise in the water table in the underlying alluvial deposits related to the river. Then, infiltrations of water into the cellars of some 60 dwelling houses located in the lower part of a town have been observed. In order to control the hydraulic impact on surface buildings of the flooding of underground mine workings, with a view to designing an effective and permanent system, a number of field studies and investigations were carried out. These studies have shown the necessity to create a new overflowing point of the mine water reservoir. For this purpose, inverse modelling of the hydrological system consisting of the mine reservoir, the alluvial deposits aquifer and the Orne river, and a 3D geological modelling of the existing mine workings have been developped. Original and new tools, completed by the inspection of the flooded mine with a remote operated véhicule, in order to illustrate and optimise the installation of the permanent gravity system necessary for lowering the water level in the mine reservoir, have been achieved. They have provided a satisfactory solution either technically or financially, even under the most severe hydrological conditions.