Sediment and chemical transport modeling of a hypothetical tailings dam breach spill in the lower Athabasca River

The lower Athabasca River is adjacent to one of the world’s largest sandy oil reserves. While tailings leaks in the event of a tailings dam failure can contaminate the downstream water column in the short term, there is a possibility of chemical adsorption by bed sediments and long-term contamination due to re-suspension of these deposits. This study tries to quantify these effects by numerically modeling the fate of sediments and related chemicals in the river from a hypothetical tailings spill. Numerical modeling is used to study the transport, deposition, and re-suspension of sediments and related chemicals downstream for different scenarios, taking into account historical and future flood events. The results show that a higher percentage of contaminated sediments leave the cloning domain in the first three days, while the rest remain in local sediments. Floods re-suspend some of these sediments and transport them miles downstream in the water column.