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
Central Asia–Center gas pipeline system Balkanabat. It continues via Uzen in Kazakhstan to the Beyneu compressor station, where it meets the eastern branch of the CAC. South of Hazar, the western system consists of diameter pipeline, and between Hazar and Beyneau diameter pipeline. On 20 December 2007, Russia, Turkmenistan and Kazakhstan agreed to construct a new Caspian pipeline parallel to the existing CAC-3 pipeline. The pipeline is planned be built between Belek compressor station in Turkmenistan and Alexandrov Gay compressor station. Capacity of the new pipeline will be 20–30 bcm per year and it would be supplied from the planned East–West pipeline. Construction of the