Surface mining
By 2009, the two extraction methods used were "in situ" extraction, when the bitumen occurs deeper within the ground, (which will account for 80 percent of oil sands development) and surface or open-pit mining, when the bitumen is closer to the surface. Only 20 percent of bitumen can be extracted using open pit mining methods, which involves large scale excavation of the land with huge hydraulic power shovels and 400-ton heavy hauler trucks. Surface mining leaves toxic tailings ponds. In contrast, "in situ" uses more specialized techniques such as steam-assisted gravity drainage (SAGD). "Eighty percent of the oil sands will be developed "in situ" which accounts for 97.5 percent of the total surface area of the oil sands region in Alberta." In 2006 the Athabasca deposit was the only large oil sands reservoir in the world which was suitable for large-scale surface mining, although most of this reservoir can only be produced using more recently developed in-situ technology.