The "Tugun Project Gold Coast" included the construction of a desalting plant and installation of two water pipelines in Queensland (Australia). The 2.2-kilometer and two-kilometer-long water pipelines, running between the sea and the plant, underpass the beach, hotels and a highway. At depths ranging between 30 and 70 meters, the machines had to cross hard rock at extremely high groundwater pressures of five to seven bar. During excavation, three curves had to be driven. The smallest curve radius was 400 meters.
To meet the specific project requirements, Herrenknecht custom-manufactured two AVN2800AHs. Uncommonly, the cutting wheels of both TBMs were monodirectional. This allowed for an optimal arrangement of the cutting tools. Due to the space-saving configuration, 24 disc cutters could be mounted. Special hydraulic thrust cylinders counteracted machine roll due to the radial thrust force. A hatch above the center drive allowed for direct cutter access and quick cutter changes in the extremely abrasive geological formation of the project. In November 2008 the successfull breakthrough was celebrated.
