Modelling the potential effects of Oil-Sands tailings pond breach on the water and sediment quality of the Lower Athabasca River

Yonas B Dibike; Ahmad Shakibaeinia; Ian G Droppo; Emma Caron

doi:10.1016/j.scitotenv.2018.06.163

Modelling the potential effects of Oil-Sands tailings pond breach on the water and sediment quality of the Lower Athabasca River

Sci Total Environ. 2018 Nov 15:642:1263-1281. doi: 10.1016/j.scitotenv.2018.06.163. Epub 2018 Jun 20.

Authors

Yonas B Dibike¹, Ahmad Shakibaeinia², Ian G Droppo³, Emma Caron⁴

Affiliations

¹ Environment and Climate Change Canada, Watershed Hydrology and Ecology Research Division (WHERD), Water & Climate Impact Research Centre (W-CIRC), Victoria, BC, Canada. Electronic address: Yonas.Dibike@canada.ca.
² Polytechnique Montreal, Department of Civil, Geological and Mining Eng., Montreal, QC, Canada.
³ Environment and Climate Change Canada, Watershed Hydrology and Ecology Research Division (WHERD), Canadian Centre for Inland Waters (CCIW), Burlington, ON, Canada.
⁴ Environment and Climate Change Canada, Watershed Hydrology and Ecology Research Division (WHERD), Water & Climate Impact Research Centre (W-CIRC), Victoria, BC, Canada.

PMID: 30045507
DOI: 10.1016/j.scitotenv.2018.06.163

Abstract

Within the Oil-Sands industry in Alberta, Canada, tailings ponds are used as water recycling and tailings storage facilities (TSF) for mining activities. However, there could be possible circumstances under which a sudden breach of an embankment confining one of the TSFs may occur. Such a tailings pond breach would result in a sudden release of a huge volume of Oil Sands process-affected water (OSPW) and sediment slurry containing substantial amount of chemical constituents that would follow the downstream drainage paths and subsequently enter into the Lower Athabasca River (LAR). This study investigates the implications of OS tailings release on the water and sediment quality of the LAR by simulating the fate of sediment and associated chemicals corresponding to a hypothetical breach and release scenarios from a select set of tailings ponds using a two-dimensional hydrodynamic and constituent transport model. After predicting the total volume, time evolution and concentration of sediment and associated chemicals (metals, polycyclic aromatic hydrocarbons (PAHs) and naphthenic acids (NAs)) reaching the LAR, the transport and deposition of these materials within the study reach is simulated. The results show that, depending on tailings release locations, between 40 and 70% of the sediment and associated chemicals get deposited onto the river bed of the 160 km study reach while the rest leaves the study domain during the first three days following the release event. These sediment/chemicals deposited during the initial spill may also have long-term effects on the water quality and aquatic ecosystem of the river and the downstream delta. However, care has to be taken in interpreting the results as further analysis has shown that the outcomes of such model simulations are very sensitive to the various underlying assumptions as well as the values assigned to some model parameters representing the physical properties of the tailings material.

Keywords: Chemical constituents; Lower Athabasca River; Oil Sands; Sediment transport; Tailings ponds; Transport modelling.