NEWS |
Halfway mark for TBM tunnelling on Auckland’s Central Interceptor sewer
Singapore DTSS Phase 2 tunnelling done SINGAPORE - Tunnelling works for the second phase of the Deep Tunnel Sewerage System (DTSS) has been completed by the National Water Agency, PUB. DTSS Phase 2 involves the construction
of a 98km-long network of deep tunnels and link sewers, as well as the future Tuas Water Reclamation Plant. It extends the DTSS network to serve the western half of Singapore, including the downtown area and new developments such as Tengah Town and Jurong Lake District. Tunnelling works on Phase 2 began in
Above: Halfway mark for CI sewer in Auckland PHOTO CREDIT: WATERCARE
NEW ZEALAND - Tunnelling on Watercare’s Central Interceptor project in New Zealand has reached the halfway mark. The project is the largest
wastewater infrastructure undertaking in New Zealand history. The Central Interceptor will store of wastewater, control
226,000m3
the flows into treatment plants and reduce the number of wastewater overflows into Auckland’s waterways and the Waitematā Harbour. The 14.7km-long tunnel will
run from Māngere Wastewater Treatment Plant to Grey Lynn and will be intersected by two link sewers. Construction of the Central
Interceptor involved excavating a 1500m-long tunnel under Manukau Harbour in 11 weeks – the first time tunnelling has been carried out under a major New Zealand harbour. The contractor, Ghella Abergeldie
JV, is delivering the NZ$1.2bn (US$710m) project, using a 5.4m-diameter Herrenknecht TBM named ‘Hiwa-i-te-Rangi’. Watercare’s Central Interceptor
Executive Programme Director, Shayne Cunis, said the halfway mark on tunnel excavation had
8 | December 2023
been achieved despite significant challenges. “We all deserve to savour this moment. We’re on track to deliver this project in 2026 as planned, despite everything that has been thrown at us – Covid-19 lockdowns, closed borders, global shipping delays, and major weather events. But most importantly, the project is being delivered safely,” he said. “I want to pay tribute to our
Ghella Abergeldie JV construction partners, as well staff from Jacobs, Aecom, Delve Underground, Watercare and our sub-contractors, who are all working so hard to deliver this project in the best way we can. This is our busiest year, with around 600 staff working on 16 sites.” Ghella Abergeldie JV’s Project
Director, Francesco Saibene, said the Central Interceptor would be the longest bored tunnel in New Zealand and reaching the halfway mark was a moment to celebrate. The first link sewer was
completed in March, and construction has started on a second link sewer, which will be completed in two drives. Section One of the main tunnel
and both link sewers are due to be commissioned by mid-2024.
2019 and incorporated new features to ensure the integrity of the deep tunnels and ease of maintenance. These include the use of concrete resistant to microbiological- influenced corrosion, isolation gates to allow for flow diversion, fibre optic cables for remote monitoring of a tunnel’s structural integrity, and the use of air jumpers to control air flow within the tunnels. Conceived in the 1990s to transform
the country’s used water management system, the gravity-fed DTSS is a 206km- long network designed to meet long-term needs for used water collection, treatment, reclamation, and discharge. PUB chief executive Goh Si Hou said:
“The Deep Tunnel Sewerage System is not only an engineering feat, but a key pillar in strengthening Singapore’s water resilience to meet the long-term challenges of climate change and growing water needs.
West Gate Tunnel decks nearly complete AUSTRALIA – More than 4.5km of road deck has been installed across the West Gate Tunnel project’s twin tunnels with a specialist machine is lifting more than 2,000 x 24-tonne concrete segments. CPB Contractors and John Holland
JV completed tunnelling with two Herrenknecht EPBMs in May this year. TBMs ‘Bella’ and ‘Vida’ were the largest TBMs in the Southern Hemisphere – each at 15.6m diameter, 90m long and weighing 4,000 tonnes. Work is also under way to construct the
tunnel entries and exits and prepare for the installation of the timber net structures. The project is due to open in late 2025. West Gate is the first Australian tunnel
to be constructed with an elevated road surface, providing another space below for maintenance of critical services, ventilation and emergency access.
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