Overview

The Australian Tunnelling Society, Australian Geomechanics Society and Institution of Civil Engineers
invite you to an evening of knowledge sharing, Q&A, and networking.

Event Synopsis

The Alkimos Seawater Alliance, comprising of Water Corporation, Acciona and Jacobs, has recently
completed the construction of two segmentally lined tunnels for the Alkimos Seawater Desalination Plant
in Perth’s north, marking a major milestone in the overall $2.8 billion project that will help secure Western
Australia’s drinking water supply amid declining rainfall.

Over 30,000 precast concrete segments were used to line the undersea tunnel, and with a combined total
length of 6.6km will house the marine intake and outfall risers. These works were undertaken in highly
variable ground conditions of Tamala Limestone and Ascot formations, coupled with challenging high
water pressures as the Intake and Outfall tunnels and extending 1.6km and 3.2km offshore under the
Indian Ocean respectively. TBM Tunnelling was completed in late August 2026, following 15 months of
continuous tunnelling operations.

Two 4.1m diameter Slurry Tunnel Boring Machines, named Mary and Karli, were selected to complete the
works. Crews operated the machines around the clock in rotating 12-hour shifts, working up to 20 metres
below the seabed including a number of times in hyperbaric conditions. The next phase currently
underway involves three vertical marine riser connections, to complete the intake and outfall structures
that will channel seawater to and from the plant.

Used to launch the TBMs was also the world’s largest secant piled peanut shaft that combines TBM
launch and the permanent Outfall Chamber and Intake Pumping Station.

Hear from the project team on the tunneling works on the project.

Event Timeline

• 5.30pm – 6.00pm: Networking and refreshments
• 6.00pm – 7.00pm: Presentation
• 7.00pm – 8.00pm Networking and refreshments

Speaker

Mr Simon Nguyen Acciona

Simon is a graduate of the University of Sydney and brings over 10 years’ construction experience
delivering critical infrastructure projects across the transport, energy and utility sectors.
His tunnelling expertise ranges from TBM, Roadheader Tunnel, and Cross Passage Excavation
developed from major underground projects across Australia including:

• Sydney Metro West Central Tunnelling Package
• Westconnex 3A M4-M5 Link Tunnels
• Melbourne Metro Tunnels and Stations

He is currently Senior Project Engineer – Tunnels for the Alkimos Seawater Desalination Plant, working
within the Alkimos Seawater Alliance (ASWA).