Details

Overview

The Australian Tunnelling Society (ATS), Australian Geomechanics Society (AGS), Australian Society of Trenchless Technology (ASTT) and Institution of Civil Engineers (ICE) invite you to an evening of knowledge sharing, Q&A, and networking.

Event Synopsis

The first stage of the Alkimos Seawater Desalination Plant (ASDP) is currently under construction by an alliance between Water Corporation, Acciona, and Jacobs. The plant is designed to produce 50 Gigalitres per annum, with provision to extend to 100 gigalitres per annum in the future. Enabling earthworks to prepare the site for construction commenced in late 2023, and works on the plant and associated infrastructure began in mid-2024. First water production is planned for 2028.

The offshore works include possibly the world’s largest secant piled peanut shaft that combines TBM launch and the permanent outfall chamber and intake pumping station.  The intake and outfall tunnels are designed for significant internal pressures, and will be connected to intake and outfall structures on the sea bed via risers that are constructed in highly permeable soils.

This presentation will explain why the plant is needed to reduce dependence on rainfall and groundwater with a growing population. It gives an overview of the desalination process and the plant itself, and the resulting demands for the seawater intake and brine outfall, which are sized for the final 100 gigalitre per annum plant. The considerations that went into siting the intakes and outfalls in a highly environmentally sensitive location will be outlined, how the resulting design process drove the need for the 2.6 km intake and 4 km outfall tunnels, and the complex process of securing environmental approvals. It will also describe how the intake and outfall solutions on the sea bed minimise the impact to flora and fauna.

The presentation will then look at some of the challenges in designing and constructing the intake and outfall systems in a complex geotechnical setting that comprises highly variable Tamala Limestone and Ascot formations. This includes a description of the all the outfall structures and the tunnel boring machine selection for the highly variable ground conditions and high water pressures.

Event activities

Networking and refreshments

Presentation

Networking and refreshments

Speakers

Anthony Harding

Technical Director-Tunnels, Jacobs

Anthony Harding is Jacobs Global Principal for Tunnel Engineering. He gained a degree and PhD from Edinburgh University, and has worked on a wide range of tunnel projects, covering transportation, water, and power markets, usually within multidisciplinary design-build environments, frequently taking senior technical and design leadership roles. Anthony is Jacobs Global Principal for Tunnel Engineering, and is currently the offshore design manage for the Alkimos Seawater Desalination Plant, working within the Alkimos Seawater Alliance (ASWA).

Damon Howes

Senior Principal Engineer, Water Corporation