NEWS |


Auckland trenchless dig TBM completes outfall drive


São Paulo revised


procurement plan for immersed tube bids BRAZIL - São Paulo’s state government has revised its concession plan and republished its bids call for the Santos–Guarujá immersed tube, the country’s first such tunnel. The revised procurement notice includes


technical and operational adjustments to the 30-year concession model, aiming to increase the appeal to the private sector, give greater legal certainty, and to enhance efficiency of the contract execution. The 1.5km-long tunnel for light rail,


Above: The small diameter TBM arrives at Onehunga Wharf in Auckland after completing its bore for a treated effluent outfall off Clarks Beach, as a key step in the project to improve water quality in the Manukau Harbour PHOTO CREDIT: WATERCARE


NEW ZEALAND - The 1.2m-diameter, 19.5-tonne TBM boring for a new wastewater pipeline in Auckland has completed its drive off Clarks Beach and recovered to docked at Onehunga Wharf The outfall for treated effluent


is a key part of Watercare’s investment to improve water quality in the Manukau Harbour. The 240m-long drive took seven


weeks. It holed through to receiving pit 10m under the sea and then two weeks were spent preparing for its recovery to the surface. The TBM had installed a steel


pipeline with a high-density polyethylene (HDPE) carrier pipeline pulled through inside. Divers unbolted the small diameter shield from both the steel and HDPE pipelines, respectively. Lift bags were used to float up


the small diameter TBM to the surface where it was secured to a pontoon barge and taken back to land where it would undergo servicing. The HDPE carrier has been


plugged to prevent leaks or ground and seawater intrusion prior being brought into service. Installation of the full outfall is


expected to the best part of two months. A 66m-long diffuser be installed


at the end of the outfall. The diffuser is designed to have almost


8 | September 2025


two dozen rubber nozzles, called ‘duck bills’. The nozzles will allow periodic release of treated effluent without permitting ingress of sea water into the outfall system. The pontoon is part of a larger


fleet of vessels working on the harbour from Clarks Beach. Piling work has been underway to establish the piled foundations for the large diffuser structure, before it is connected to the bored tunnel outfall. Treated effluent will come from


the Clarks Beach Wastewater Treatment Plant, currently being upgraded. The works are expected to be completed by mid-2026. The outfall is a key component


of a broader infrastructure programme designed to support the projected population growth in Auckland’s south-west, which is expected to reach approximately 30,000 people by 2050. Watercare programme delivery


manager Dave Kennerley said the outfall has been designed and sized to support future population growth. It will store and discharge treated wastewater approximately 100m into the Waiuku Channel – a highly dynamic part of the harbour where it will quickly disperse. Discharges for treated effluent


dispersion will happen on outgoing tides.


pedestrians and cyclists is to run beneath the estuary between the cities of Santos and Guarujá, travel between which is currently served by ferries and small passenger boats. The tunnel will is to have three lanes in


each direction and the concession contract is to cover construction, operation, and maintenance. São Paulo state government took the


project on a procurement roadshow to Europe and changed its plans following the discussions on the infrastructure market’s appetite for the concession deal. Adjustments changed the contractual


base date, revised some major cost items, and re-evaluated the average transportation distance, and traffic projections were updated. There were also more safeguards for the concessionaire, on predictability and contractual protection. The project is a partnership between


the state government, its transport agency (ARTESP), the Ministry of Ports and Airports, the National Waterway Transport Agency (ANTAQ), and the Santos Port Authority. Bid deadline is early September.


TBMs relaunched on Melbourne’s North East Link AUSTRALIA - The two 15.6m-diameter TBMs on the North East Link road tunnel project, in Melbourne, were recently relaunched following servicing and pull throughs in a 30m-deep box at Lower Plenty Road, where they reached earlier this year. TBMs ‘Gillian’ and ‘Zelda’ are driving


the remaining stretch of the 6.5km-long tunnels to Bulleen. The Herrenknecht TBMs are operated


by Spark consortium, comprising Webuild, GS Engineering and Construction, CPB Contractors, China Construction Oceania, Ventia, Capella Capital, John Laing Investments, DIF, and Pacific Partnerships.


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