| NEWS


Single team approach for Snowy AUSTRALIA – Client and contractors on Australia’s Snowy 2.0 hydropower project are now working as a single team following the recent reset of construction schedule and budget. The organisations – client Snowy Hydro


and the construction JV Future Generation – are now working to finish the new power plant before 2029. The Future Generation JV (FGJV)


comprises Webuild and its subsidiaries Lane and Clough. Under the new arrangement, the works have moved to an incentivised target cost contract model, with outstanding claims settled. Approaching half of the hydro project


has been completed, including excavations for the 2.85km-long main access tunnel and 2.9km-long emergency, cable and ventilation tunnel, the tailrace tunnel, cross passages and other tunnels, respectively. Cavern excavations are also underway for the underground powerhouse complex. For the headrace, TBM ‘Kirsten’ is being


modified to excavate the inclined pressure shaft. A second TBM, ‘Florence’, working on the tunnel was halted after a surface depression developed when the machine was moving from soft material into harder rock conditions.


London finishes in ’23… …Tunnelling at Power Tunnels UK – National Grid’s £1bn (US$1.2bn) London Power Tunnels (LPT) project, Phase 2, recently achieved a major milestone with its final tunnelling breakthrough at Eltham substation in Greenwich. The last of the project’s TBMs, named


‘Grace’ had tunnelled more than 11km eastwards from National Grid’s New Cross substation, in Southwark. With the full 32.5km underground route


complete, having involved tunnelling at depths of up to 60m under seven south London boroughs, the project will have shifted 900,000 tonnes of earth, with 99.98% of waste material diverted from landfill. National Grid’s delivery partner, Hochtief-Murphy Joint Venture (HMJV), started the Phase 2 tunnelling works in March 2020. Four TBMs – ‘Christine’, ‘Caroline’, ‘Edith’


and ‘Grace’ – bored the LPT Phase 2 tunnels, the works being executed in three sections between existing substations across south London: Wimbledon-New Cross (12km); New Cross-Hurst (18km); and Hurst- Crayford (2.5km).


Breakthroughs were at Eltham in June


2022 (TBM ‘Christine’ tunnelling from Hurst); Wimbledon in July 2022 (TBM ‘Caroline’ tunnelling from Kings Avenue); Crayford in January 2023 (‘Christine’ again tunnelling from Hurst); and, Kings Avenue in April 2023 (TBM ‘Edith’ tunnelling from New Cross). Vertical shafts of 9m-15m in diameter


and up to 55m depth were built for the tunnelling works and to provide future maintenance access to the high voltage (HV) power cables, approximately 200km of which are being installed between Wimbledon and Crayford. The power cables are to be fully operational by 2026 to reinforce and future-proof London’s electricity network as demand in the capital grows. Phase 1 of the National Grid project was


completed between 2011 and 2018, and carries power cables across the north side of the city.


…Secondary lining at Tideway UK – London’s new super sewer, Thames Tideway, achieved another milestone step closer to fully finishing with completion of the final section of secondary concrete lining to the bored tunnel. TBMs finished excavating the 25km-


long main tunnel in the first half of 2023. The end of excavation was followed with the secondary lining finish in the eastern section of the route, between Bermondsey and Stratford, at the close of the third quarter. This brings the Tideway project one


step closer to delivery, as it looks ahead to activating the tunnel in 2024. Tideway tunnel is designed to transfer sewage eastwards under gravity, intercepting the roughly 39 million tonnes of raw sewage overflows estimated to enter the River Thames every year. Primary lining for the 7.2m i.d. super


sewer was installed by four TBMs, running mostly under the river at depths of 30m-70m, while two smaller machines built Tideway’s two large connection tunnels in Greenwich and Wandsworth. A joint venture between Costain, Vinci


Construction Grands Projets and Bachy Soletanche is delivering the eastern section of the super sewer project. The western section is being built by a


joint venture of BAM Nuttall, Morgan Sindall and Balfour Beatty Group. The central section is built by Ferrovial Agroman UK and Laing O’Rourke.


…Silvertown piling UK – Bachy Soletanche has completed its piling programme for London’s new 1.4km- long Silvertown twin-tube road tunnel that will run under the River Thames. Working on behalf of the Riverlinx CJV,


Bachy Soletanche delivered geotechnical works on the Greenwich side of the project, which took just under two years to complete. For the tunnel’s South Portal, rotary


bored piles were used to form a secant wall, soldier piles and jet grouted columns. Further secant piles were used for the open cut and overbridge. Another major section of the contract


involved construction of a diaphragm wall shaft to form a reception and rotation chamber for the single TBM on the project following the machine’s first, southbound, drive from Silvertown to the Greenwich Peninsula. Unreinforced CFA piles were installed outside the shaft to strengthen and reduce the permeability of the river terrace deposits.


Second TBM arrival for Vancouver’s Oak-VGH CANADA – The second TBM recently achieved breakthrough at the future Oak- VGH Station on Vancouver’s Broadway Subway Project. Arrival of TBM ‘Elsie’, operated by


Broadway Subway Project Corporation, an Acciona Ghella JV, follows that of TBM ‘Phyllis’, in mid-October. The two Herrenknecht TBMs departed


from Great Northern Way-Emily Carr Station to bore 2km-long parallel tunnels. The Oak-VGH Station is the fourth of six underground stations along the future Broadway subway corridor. Following scheduled maintenance,


Phyllis and the Elsie are to bore next to South Granville. Construction of concrete walls, columns and floors is under way at all six stations on the project, which is a 5.7km-long extension of the Millennium Line.


Sydney university launches tunnelling major AUSTRALIA – The University of Technology Sydney (UTS) is launching what it says is the country’s first major course in tunnelling and underground engineering. Applications have been open over


recent months for the new course major – the Tunnelling and Underground Engineering programmedue to start in Feb 2024.


January 2024 | 7


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