Water management of the Finne Tunnel
Environmental monitoring has been carried out since the planning phase. The groundwater, flowing and standing water and the volumes of water obtained have been monitored.
Together with the relevant authorities, the volume of water available, its local distribution, chemical properties and any impact on the environment have all been continuously monitored. Dozens of measuring instruments provide the data for a hydrogeological model that permits the situation before, during and after construction to be observed and anticipated.
Large sections of the Finne Tunnel are under mountain water. The groundwater levels observed are around 40 metres and up to 60 metres above the floor of the tunnel. Hydrogeological analyses have shown that the groundwater does not take the form of a single body of water. Instead, it is found separately on a number of levels, from which little water permeates. The water level is lowered by means of bore wells when the tunnel boring machines cut through layers of water.