Construction of the Trans-Alaska Pipeline System for a fifth, should it become necessary. Holding tanks were planned that had a capacity equal to that of the pipeline, allowing the whole pipeline to be emptied if required. As required by the Pipeline Authorization Act, a ballast-water filtration system had to be designed as well. This system removes oil from tankers' ballast water so it is not released into Prince William Sound—something fishermen feared when the pipeline was proposed. Shortly after the permit was signed, convoys of equipment on snow tractors began heading north, using hardened snow roads and an ice bridge over the Yukon River to reach
Construction of the Trans-Alaska Pipeline System cost $1.4 billion. The percentage of the pipeline owned by various companies has changed over time, but as of 2009, the primary owner was BP, which controls 46.93 percent of the pipeline. Second is ConocoPhillips Transportation Alaska Inc. with 28.29 percent, followed in order by ExxonMobil (20.34 percent), Koch Alaska Pipeline Company (3.08 percent), and Unocal Pipeline Company (1.36 percent). The pipeline also has had a human toll. Thirty-two Alyeska or contract workers were killed during the construction project. That figure does not include common carrier fatalities. Since the pipeline began operating in 1977, 10 people have been killed while