Geotechnical performance of a uranium tailings containment facility at Key Lake, Saskatchewan

Abstract

The main objective of this paper was to investigate the geotechnical performance of uranium tailings in the Deilmann Tailings Management Facility (DTMF) at Key Lake, Saskatchewan, Canada. Laboratory analyses of core samples indicated that the high water content (100–250%) at the tailings surface gradually decreases with depth and reaches around 60–80% at the DTMF bottom. The corresponding solids content values were found to be 30 ± 5% at the surface and 60 ± 5% at the bottom. The grain size data correlated well with both the water content and the solids content profiles, that is, an increase in fines content or an increase in coarse content was associated with an increase in water content (decrease in solids content) and vice versa. The investigated tailings generally exhibited segregation within a narrow range of +2 to −2%, when scaled with respect to the average solids content over a vertical profile. A fines water ratio of around 50 ± 5% was found to be associated with negligible segregation. The effective stress was found to be up to 600 kPa at the DTMF bottom. At low effective stress (around 5 kPa), void ratio ranged from 3.0 to 5.0, while at high effective stress (around 600 kPa) the range of void ratios was generally between 0.5 and 1.0.