Due to extreme precipitation fluctuations, Sydney‘s drinking water demand could no longer be met by relying on rainwater alone. A seawater desalination plant was therefore set up on the Kurnell Peninsula south of Sydney. The plant was planned to supply the metropolis with four million inhabitants with up to 15 percent of the drinking water volume required per day.
To connect the desalination plant with the water intake and outfall systems in the Tasmian Sea, two identical Herrenknecht micromachines type TBM3400XH were used. With a diameter of 4.16 meters, they excavated two 2.5-kilometer-long sections in hard sandstone, including four curves with a radius of 500 meters.
The machines achieved best monthly performance rates of up to 650 meters. In the two tunnels a total of 1,904 segment rings were installed precisely. The brekthough of the two machines - right on schedule on December 7 and December 8, 2008 - was an important cornerstone for putting the plant into operation at the end of 2009 as planned.