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Suspended sediment in Quesnel Lake following the Mount Polley Mine tailings spill

University of British Columbia

In the four years that followed the 4 August 2014 tailings dam failure at Mount Polley Mine, British Columbia, Canada, water quality data indicated an ongoing sediment loading to Quesnel Lake and the Quesnel River. Within one day of the tailings dam failure, a flood of slurry entered the smaller, downstream basin of Quesnel Lake, called the West Basin. Previous studies had shown highly elevated turbidity in the West Basin through the first autumn and winter after the spill, and above background turbidity each autumn and spring from 2015 onwards. It remained unclear how long this seasonally elevated turbidity would last. In this thesis, we evalutate sediment transport in Quesnel Lake following the rapid inflow of a vast quantity of material. This thesis applies conservation of mass in two ways: first, using data collected between 10 September 2014 and 21 December 2018 to estimate suspended sediment mass and mass flows into and out of the West Basin; and second, using an analytical model. On 10 September, 37 days post-spill, an estimated 38000 $\pm$ 11000 Mg of solids remained suspended in the West Basin; this decreased to within background levels ($

Text

2020-07-02

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/74837

Civil Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/