Water Supply Sourcing Options for Oils Sands Mines
Each potential oil sands developer deals with the question of optional sources of raw water to supply large water demands that range from 40 to 80 million cubic metres per year for each of six existing and planned developments. The Athabasca River currently supplies nearly all of the water to the existing mines and has resulted in some concern over the effects of reduced river flows. This paper describes the various water supply options, and the likely scenario for future oil sands water supply projects. Various water supply options have been suggested including groundwater, directional drill or horizontal wells into an alluvial sand aquifer beneath the river, infiltration galleries, diversion of small tributary streams, utilization of large lakes in the region and pumping from other large rivers in the region. Investigations show that the size of river needed to support the high raw water usage by oil sands mines exceeds 3000 km2 eliminating all rivers except those like the Firebag, Steepbank and MacKay Rivers that are located in the oils sands region. Lakes cannot be used as a source of supply due to large water deficits for smaller lakes and the large cost of sourcing water from a lake as large as Lake Athabasca. Groundwater is not economical even if ground water quality was acceptable. Riverbank intakes on the Athabasca River will likely continue to be the only practical water supply option for oil sands mines north of Fort McMurray, although various types of Athabasca River intakes are possible. Intake systems at existing intakes include screened river bank intakes, forebay intakes, and river bottom intakes. Infiltration galleries and directional drill or horizontal wells are not feasible for most sites, though some well configurations might be feasible if a suitable near-surface sand deposit occurred beneath the river at a suitable location.