By rosebell
TBM Hiwa-i-te-Rangi, which is digging the Central Interceptor wastewater tunnel in Auckland, New Zealand, has broken through into the bottom of the 30m deep shaft at the project’s Western Springs site on Tuesday 10 September.
While this machine was commissioned in July 202, it has excavated more than13km and installed over than 8,100 segment rings until now.
As a representive of Auckland-based water company Watercare, the Ghella Abergeldie joint venture (JV) is constructing the project.
Although in 2019 that the Central Interceptor project was consented, Western Springs was slated to be the last site on the original tunnel alignment, earlier this summer Watercare received funding to extend the wastewater tunnel northward by just over 1.5km, that means that tunneling is due to continue to build the extension from Grey Lynn to Point Erin, Herne Bay.
So, stretching 16.2km from the Māngere Wastewater Treatment Plant to Point Erin Park, New Zealand’s longest wastewater tunnel will be even longer.
Being endorsed by Auckland Council, the funding for the extension is part of the New Zealand government’s Local Water Done Well plan. As part of it, Watercare has been financially separated from the council, so it can access increased borrowing for investment in water services.
While delivery of the extension will be up to the Ghella Abergeldie JV, Arup will continue to support the JV in the delivery of the detailed design.
In order to arriving 30m beneath surface at Point Erin Park, Hiwa-i-te-Rangi will continue boring from Tawariki St, Grey Lynn, at depths of between 17-60m.
With the aim of decreasing wet-weather overflows in central Auckland, Central Interceptor has a combined stormwater and wastewater network.
With NZ$204M (£100M) more than its original budget, Watercare revised the project’s budget to NZ$1.5bn (£724M) earlier this year. It said that the project had become more expensive to deliver due to inflation, which had increased labour and material costs.
The scheduled date for inauguration of this scheme up to Grey Lynn is 2026, whereas the Point Erin extension will be started up in 2028, when it connects to an upgraded Herne Bay Trunk Sewer.
