The 5.4m diameter TBM Hiwa-i-te-Rangi arrived at the 25m deep Pump Station 23 shaft in Hillsborough (Auckland) on 6th December. The TBM had left the southern shore of the Manukau in September and tunnelled the 1500m stretch under the harbour in just 11 weeks for the Central Interceptor project.

The TBM cutterhead will now be inspected, repaired and adjusted. In 2023 the TBM Hiwa-i-te-Rangi will then begin tunnelling the 2 km towards central Auckland to Keith Hay Park site in Mount Roskill.

Hiwa-i-te-Rangi began her journey in August last year and has now travelled more than 4 km from the site next to Māngere Wastewater Treatment Plant on Greenwood Rd to Onehunga, crossing through different geological formations. The 4.5m diameter tunnel is made up of concrete rings, formed by six concrete segments that are fixed together underground, 10-12 completed tunnel rings are laid each day. Spoil travels through the cutterhead, along the length of the nearly 200m TBM via a series of conveyor belts, before tipping into “muck skips” which travel to the tunnel entrance via electric locomotives. A gantry crane lifts the muck skips out of the shaft and the spoil is deposited at nearby Puketutu Island. 

Meanwhile the micro-TBM Domenica achieved her third breakthrough on the Link Sewer C, the first link sewer (running from May Rd, Mt Roskill to Avondale). In November it completed an epic 1100m drive and broke through at Miranda Reserve site in Avondale. 

Domenica will travel another 300m to the pump station located further west in the Reserve, completing the Link Sewer C. It will then be refurbished ahead of work on the second link sewer next year. 

The Ghella Abergeldie JV is delivering the Central Interceptor project. Tunnelling takes place at 15-20m below the seabed, with a maximum of 15 crew working 24/7 underground at a time. 

Earlier this year, Auckland Council announced that the Central Interceptor tunnel would be extended from Tawariki St, Grey Lynn to Pt Erin to capture combined wastewater and stormwater flows in Herne Bay. Consent applications for the tunnel extension will take place early next year.  For further information click here and nz/18 for tunnelbuilder archive. Visit  https://www.watercare.co.nz/.  49/22