City Rail Link – Major Wastewater Diversion to Basque Park

A complex diversion

PROJECT: City Rail Link – Major Wastewater Diversion to Basque Park CONTRACTOR: Universal Underground CLIENT: Link Alliance – City Rail Link VALUE: $728,482

The City Rail Link Project is New Zealand’s largest civil infrastructure project to date. Design and construction of this project is being carried out by Link Alliance.

A major diversion was required for the wastewater conveyance at Mt Eden, where the new City Rail Link tunnels connect with the existing rail system. The design for this diversion comprises a DN560 SDR7.4 PE horizontal directional drilled installation, 330 metres long, at depths up to 26m below ground level with open excavation sections at each end.

The design of this diversion includes many innovative aspects to meet the unique challenges of a medium diameter horizontal directional drilled installation in the congested urban environment at Mt Eden and Auckland’s unique volcanic geology. Design parameters and installation methodologies were selected and included two trenchless construction methodologies in series to achieve this unique pipeline installation with difficult site conditions and installation requirements.