Unravelling Geological Structures Controlling the Groundwater Table in the Blötberget Mine Area

Natural resource consumption, one of the main drivers of carbon emissions, is steadily rising at a concerning pace. For raw materials and mineral resources, this means an annual increase, a trend expected to intensify with the global transition to green energy and sustainable industries. In particular, the demand for rare earth elements, often found in iron ore deposits, is projected to grow significantly. While reducing the global resource demand is crucial for achieving a sustainable future, developing environmentally responsible mining practices is equally essential. Re-opening of historical mines may be a more sustainable alternative to traditional exploitation, mainly due to its reduced environmental disturbance. Since transportation infrastructure are already in place and overburden has previously been removed, re-opening such sites can reduce additional ecosystem disruption. However, successful re-opening requires a comprehensive understanding of hydrogeological conditions in the area. This study investigates the Blötberget mine in Dalarna, Sweden as a previously closed mine to be reactivated. Following its closure, the mine rapidly flooded, and to evaluate its re-opening potential, this research analyses borehole data to map groundwater levels and examine the influence of geological structures on groundwater behaviour. The results indicate that the groundwater flow is significantly affected by several local geological features. Several of the faults in the area were found to function as hydraulic barriers, impeding groundwater flow and causing major variations in the water table. In contrast, other faults acted as conduits, forming aquifer zones in the host rock and likely promote groundwater flow locally. Notable, one significant drainage was identified, creating a local depression in the water table and thus marking the possible need for adapted dewatering upon re-opening of the mine. These findings highlight the significance of a detailed structural and hydrogeological analysis when considering reactivation of former mine sites. To further improve the understanding of groundwater dynamics in the area, future studies incorporating additional data such as topographic, subsurface, geological and temporal weather information would be highly valuable. Detailed analyses investigating such additional datasets could support reliable groundwater modelling, as well as high-frequency monitoring to capture seasonal fluctuations in the water table.