The Impact of the Mount Polley Tailings Pond Failure on the Sedimentary Record of Quesnel Lake, British Columbia
The Mount Polley tailings pond failure that occurred on August 4, 2014 provided an opportunity to understand the effects of point source sedimentation events in the sedimentary record. Six sediment cores that were taken at both distal and proximal locations in Quesnel Lake (B.C. were used to identify if turbidity currents or subaqueous debris flows were generated. Geotechnical (grain size and LOI) mineralogical and copper metal concentrations confirmed the presence of turbidite deposits in four cores. All of these turbidites contained a coarser grained base and an uppermost fine grained cap. Two out of the four turbidite deposits that were most proximal to the spill mouth contained mixed basal layers that may signify the energy of the current at that depth. Sediment is focused in the deepest part of the basin. The spill sediments will compress over time but will represent sedimentation rates at 4 5 orders of magnitude larger than Holocene natural rates.