Facing some of the tightest tolerances imaginable, Keller company Austral Construction has successfully finished a complex marine piling project ahead of schedule. It’s a vital infrastructure project that supports the development of a major new iron ore facility in Western Australia.
World-first autonomous road trains, industry-leading dust-free transport and resort-style employer accommodation are just some of the innovative features proposed for Onslow Iron – one of Australia’s largest iron ore developments.
Located in the remote Pilbara region of Western Australia, Onslow Iron will unlock billons of tonnes of stranded ore deposits, with an estimated 35 million tonnes intended to be shipped across the world annually.
In order for that to happen, the iron ore will travel150km from the Ken’s Bore mine to the Port of Ashburton in driverless road trains. At the wharf, it’ll be loaded via conveyor belts onto transhippers, which will take the cargo out to large vessels anchored40km off the coast.
Months of planning
The wharf is a critical link in this highly efficient process – and Keller company Austral Construction has played a vital role in its development.
Onslow Iron developer Mineral Resources Limited (MinRes) selected Austral due to its extensive expertise in marine projects, competitive price and unrivalled access to specialist equipment. Austral was contracted to carry out construction for almost the entire wharf structure, including the substructure piling and super structure.
“The project was extremely challenging and required a lot of detailed design and engineering works, with around four months of planning,” says Semir Basic, Project Manager. “The scope included 17 land-based piles and 51 marine piles, all of which came with a pre-applied protective coating. Given the site’s remote location, we had to meticulously plan and prepare for every possible need.”
For Project Superintendent Beau Bianchi, the biggest challenge came in the execution. “Around half of the marine piles were there to support these 270-tonne mooring dolphins fabricated overseas, each of which would cap six piles. Because these had to slip almost perfectly over the top of the piles, the verticality of the piles had to be incredibly accurate. In fact, these were some of the tightest tolerances –just 2mm per metre – I’ve worked with in my 20-plus-year career.”
To ensure those tolerances were met, the crew used guide frames and drove each pile just 500mm at a time before surveying its entire length. “You only get one shot to get it right,” he adds. “You can’t redo them, so we spent a lot of time surveying. We committed to a pile a day, but because of our planning, right plant and the hard work of the crew we were able to average 1.2.”
Speeding up the project
The project began with the crew installing the land-based piles from a working platform on reclaimed land, before moving onto the marine piles. These were installed using a rig mounted on a large, self-elevating barge, which reduced the need for time-consuming temporary works to be constructed.
The team had to carefully plan the installation sequence so the Jack Up barge could reach all the necessary areas. “There was also only a small area for the guide frame to operate along the side of the barge, so it was critical that it was set up in exactly the right position,” says Semir. “Once you jack up the barge you can’t move it easily – it takes half a day to do so.”
Starting on site in April, the Austral team successfully completed the works in early October. Towards the end, Austral demonstrated its breadth of resources by bringing in a second barge to expedite grouting for all the piles, allowing the crane barge to install the wharf’s smaller modules, catwalks and walkways. This approach enabled the team to finish ahead of schedule.
“The project ran very smoothly, which is testament to our planning, execution capabilities and strong partnership approach with the client,” adds Semir. “No one else really has the specialist equipment we do, nor the expertise to deliver such a project to this high quality – and finish early to save the client time. MinRes is very happy and, needless to say, so are we.”