Numerical methods applied to field tests for the determination of the saturated permeability

Abstract

As part of a seepage study for a new tailings facility in the north of Chile, which is to be built upon deep unsaturated consolidated alluvial deposits, an exhaustive hydrogeological characterization was carried out based on field work. Constant and falling head permeability testing in boreholes; laboratory testwork to characterize the materials; and desktop studies aimed at developing numerical models were included. A series of numerical models, which together with the soil material properties determined from the boreholes, allowed the saturated permeability of the soil to be estimated. The results were then subsequently applied in the hydrogeological modeling of the tailings facility. Infiltration models were carried out to simulate each test interval in the boreholes. An iteration process was applied, based on a soil water characteristic curve for the material, obtaining from each model flow values equal to or similar to that measured in the field for the constant and falling head permeability tests. The use of these models also allowed the field testwork to be optimized, both relating to the type of test to undertake and also the duration of each test.