Central Interceptor project’s TBM ordered

14 November 2019

New Zealand – The Central Interceptor wastewater project has ordered a 5.45m-diameter Herrenknecht EPB for its main 13km tunnel. The tunnel depth will vary from 15-110m, with a harbour crossing 15m below the seabed. The finished diameter of the tunnel will be 4.5m.

The Ghella Abergeldie joint venture (GAJV) was appointed in early 2019 as Main Contractor by Watercare, with Arup commissioned by GAJV to provide tender design support, detailed design services and construction phase support of shafts structural design and the tunnel lining design. The client’s consultant is Jacobs.

The tunnel will connect with the existing network and will encounter 16 shafts up to 80m deep, as well as numerous connecting sewers, chambers, control facilities and air treatment facilities.

The geology within the main tunnel alignment and link sewers primarily comprise moderately weathered to unweathered, extremely weak to weak, interbedded sandstones, siltstones and mudstones of the East Coast Bays Formation (ECBF), and to a lesser extent ECBF residual soils, and recent alluvium and Kaawa Formation soils belonging to the Tauranga Group.

The project also calls for 4.3km of pipe-jacked connections to be executed by a 3m and a 2.85m diameter machine. Some 1,500 segments will be required for this.