How are the oil sands mined and what is done after mining is complete?
To understand how mining works it is necessary to know the geology of the Fort McMurray area. Portions of the oil sands are found on the surface, especially in the valley of the Athabasca River where the river has worn away surface rock and gravel. Most of the oil sands, however, are buried under sand, gravel, and rock, called overburden, and in some places up to 16 metres of muskeg or swamp. The amount of overburden varies, but generally it increases the further you get away from the Athabasca and Clearwater River valleys. The oil sands themselves lie in a band, often 50 metres deep, below the overburden and above a layer of limestone bedrock. Companies have to remove the muskeg and overburden to expose the layer of oil sands. Then draglines, trucks, shovels and other heavy equipment remove the oil sands and take it away to the extraction and upgrading plants for processing. This is called open pit mining. Eventually, as mining operations move into new areas, earlier parts of the old
