Water Supply Sourcing Options for Oil 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 50 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 via conventional bank intakes, which 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 Athabasca River water via infiltration galleries, groundwater, combined Athabasca River water and alluvial groundwater using wells (i.e. bank filtration systems), diversion of tributary rivers, utilization of large lakes in the region and pumping from other large rivers in the region. Investigations show that the size of river catchment needed to support raw water usage by a typical oil sands mines exceeds 5,000 km2 eliminating all tributary rivers that are located in the oil sands region except those rivers with large drainage areas like Firebag and MacKay Rivers. 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. A groundwater source alone would not likely meet the large water demands. River intakes on the Athabasca River will likely continue to be the most practical water supply option for oil sands mines north of Fort McMurray, although various types of Athabasca River intakes are possible. Existing intake systems include screened riverbank intakes, forebay intakes, and river bottom intakes. Infiltration galleries are not feasible for most sites, though some bank-filtration-type systems using high capacity wells may be an option if there is sufficient thickness of high-permeability alluvium at a suitable location in the Athabasca River valley.