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Wind waves and internal waves in Base Mine Lake

University of British Columbia

Syncrude's Base Mine Lake is the first commercial scale demonstration of end pit lake technology in the Canadian Oil Sands. Following its commissioning in 2012 significant efforts have been made to monitor and understand its evolution. Of particular interest is the impact of surface and internal waves on the resuspension of fluid fine tailings and the effect of hydrocarbons on surface wind wave formation and growth. In this study the first complete description of the wind and internal waves in Base Mine Lake is presented. Observations of surface wind waves were collected using two subsurface pressure gauges. Data revealed that wind waves in Base Mine Lake have short residence times and rarely generate bottom orbital velocities capable of resuspending fluid fine tailings. Additionally, numerical simulations of the wind waves in Base Mine Lake were performed with the SWAN model. Modeled wave heights were in good agreement with observations, and resuspension of fluid fine tailings was minimal even during the 10 year storm event. As the surface of Base Mine Lake contains a hydrocarbon film its impact on surface wind waves was investigated in the laboratory and field. It was found that the hydrocarbon film dampens high frequency wind waves and results in a slower growing wind wave field dominated by longer wavelengths. Additionally, the presence of hydrocarbons also increases the critical wind speed needed to initiate wave growth. From these findings it is postulated that the hydrocarbon film on Base Mine Lake acts to decrease the fluxes of momentum, gas, and heat. The internal waves in Base Mine Lake were simulated using Delft3D Flow. Simulated wave heights as large as 3 m were shown to oscillate for multiple days with little dampening, and despite the small surface area of Base Mine Lake (8 km²) the internal waves were significantly influenced by the Coriolis force. This influence was seen in the form of simulated Kelvin and Poincaré waves which resulted in complex circulation patterns within the lake. The findings presented here provide a first picture into the impacts of waves on the reclamation of Base Mine Lake.

Text

2017-08-08

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/62524

Civil Engineering

University of British Columbia

UBCV

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