Disturbance of a natural hydrogeochemical system caused by the construction of a high-level radioactive waste facility: The case study of the central storage facility at Villar de Canas, Spain

This paper analyzes the natural hydrogeochemical conditions of the future Central Storage Facility site at Villar de Canas and evaluates the evolution of the system associated with its construction. The characterization of the hydrogeochemical structure of the system is based on a comprehensive field and laboratory survey, which allowed us to define both the distribution of materials and their hydro-chemomechanical properties under isothermal conditions. The resulting observations were used to develop a numerical model in a multiphysics environment solver, which was calibrated from the monitoring of the hydraulic head distribution and from detailed geochemical analysis of water samples. The numerical model indicated that the behavior of the system is governed by a very slow underground flow regime and by equilibrium with gypsum and the dissolution of other sulfated phases; these results also suggest that the construction of facilities will not significantly disturb these processes, showing a very small effect of chemistry on the mechanical evolution (vertical displacements).