The HRBT Expansion Project reached several milestones in August. On the South Island, construction crews completed the underground concrete walls, also known as slurry walls, for the launch pit, where the TBM start digging the new tunnels.
Excavation of the pit, which is scheduled to start this fall, will create a space for assembly and launching of the TBM. The machine will be received later this year via the TBM Quay – a dock that is currently being built adjacent to the South Island, as shown on the image above.
In preparation for the start of tunnelling next year, crews are busy installing cementitious ground improvement to strengthen the soft soils along the TBM’s path at the South Island. This process includes two separate operations called jet grouting and deep soil mixing.
In August, the first concrete pile cap – with special corrosion-resistant reinforcement – was installed on the foundation pilings for the new trestle bridges across the harbour.
Over on the North Island, crews have nearly completed the first layer of sand fill for the island expansion. Roadway and bridge construction continues throughout the 16 km (10-mile) corridor as crews prepare to start partial demolition on the Mallory Street Bridge over I-64.
The Slurry Treatment Plant (named “STP Katherine”) completed its Factory Acceptance Testing (FAT) at the MS factory in Clermont-Ferrand, France. Members of HRCP team, as well as from Dragados and Vinci, were present during the testing. The STP is comprised of a four-story structure with six towers, a building with nine filter presses, and nine large circular tanks. The STP is the facility where the bentonite slurry, which is fed to TBM Mary during her tunnel boring operation, will be produced. It is also where the “used” bentonite slurry containing spoils from the TBM excavation will be processed. Over the coming weeks, STP Katherine will be disassembled and shipped to the project site. Once received, she will be assembled in the northwest corner of the South Island and ready for use when TBM Mary begins boring the first of two new tunnels early next year. Click here and us/125 for information in the tunnelbuilder archive. Visit www.hrbtexpansion.org. 37/21.
