Characterizing groundwater flow in a former uranium mine (Bertholène, France): Present status and future considerations

• Published in: Journal of hydrology. Regional studies 2022-12, Vol.44, p.101221, Article 101221
• Main Authors: L’Hermite, Pierre, Plagnes, Valérie, Jost, Anne, Kern, Guillaume, Reilé, Benoît, Chautard, Camille, Descostes, Michael
• Format: Article
• Language: English
• Subjects: Climate change; Data analysis; Earth Sciences; Former mining site; Groundwater flows; Groundwater modeling; Hydrology; Sciences of the Universe
• ISSN: 2214-5818; 2214-5818
• DOI: 10.1016/j.ejrh.2022.101221

Bertholène is a former uranium mine in Aveyron, where tailings and waste rocks are stored in a natural valley. This results in acid mine drainage (AMD) at the outlet of the tailings storage facility (TSF), where there is a dedicated water treatment plant. A detailed data analysis was conducted using data from 13 piezometers and from long-term monitoring of the local climate. A 3D model was developed using MODFLOW to understand groundwater flows at the catchment scale and identify flow paths from the contamination sources within the TSF. Previous geochemical modeling of TSFs had indicated that AMD was expected to occur for 50–100 years, therefore the site must be managed with a long-term view. As climate change may affect not only the recharge but also the frequency and intensity of extreme events, its impact on water balance and water levels at the site has to be studied for the next 100 years. Data analysis provides information about the unsaturated conditions within the tailings. Then water balance calculations at the TSF outlet validate the contribution of two different water zones. Modeling using the recharge estimation supports the current functioning of the catchment. The impact study of extreme events shows that the water table should not permanently reach the tailings over the next century. [Display omitted] •Combination of data analysis, hydrogeological model and climate change impact.•Tailings storage is in unsaturated conditions.•Modelling validates the current hydrogeological functioning using estimated recharge.•Climate change has little impact on the water balance but modifies the extreme events.