Tailings dam embankment stability has re-emerged as a critical issue in the operation and management of tailings storage facilities (TSF). In particular, Samarco (Morgenstern et al., 2016), Mount Polley (Morgenstern et al., 2015) and Cadia Valley (Jefferies et al., 2019). Due to increased production rates and cost efficiency drives, TSF numbers have followed suit. As a consequence, incidence rates and fatalities increased, but normalised rates of failure per ton tailings are steady (Penman and Williamson, 2001; WMTF, 2019). Placement and operation of TSF remain a key concern as it is expected that global demand for resource production will only increase.
The mechanism of failure is complex, but a critical component is related to pore water in the embankments and footprint, causing foundation failure. Mobilisation of the foundation, shearing and lateral displacement, results in loss of containment. Groundwater, permeability, and composition of the substrate are important factors that influence short and long-term performance of a TSF.
In this paper, the influence of groundwater on the residual strength of the material properties is presented. It will include the assessment of the substrate, TSF footprint, geology, design criteria, and final landform. An important factor that is commonly overlooked by TSF design efforts is the impact of chemical and physical properties of seepage, rainfall, and groundwater on TSF containment structures. Long-term stability, closure, and liability are highly dependent on these factors. Under operational conditions, groundwater and seepage pathways can influence stability criteria which are connected to the rate of rise, loading of the footprint, consolidation and pore pressure dissipation.
Research outcomes include impacts of groundwater and seepage on footprint placement, design criteria, management and embankment stability in the operational and long-term setting.