How is the oil shale mined?
Shale is hard, abrasive and resilient. Explosives are typically employed to break the rock. The underground mine will extract a rich oil shale horizon, typically 40 to 60 feet in thickness. If this rich oil shale zone outcrops at the surface, horizontal mine adits or openings will allow entry to mine the shale. If the shale does not outcrop, then vertical shafts or declines will be used to reach the shale horizon below the surface. At the White River Mine the shale horizon is about 1,000 feet below the surface. A 30-foot diameter vertical shaft is the main mine entry, and a separate 4,574-foot long, three-segment, doglegged decline was installed to convey the shale to the surface. The top leg of the decline is 28.5 feet wide by 12.75 feet high and slopes at 23.75% over a length of 2,074 feet. The lower leg is 18.5 feet wide by 12.75 feet high and 2,500 feet long with a slope of 26.8%. Two other mine openings that intersect the decline are a 16-foot diameter ventilation raise and a 5-fo
