Keller was employed by fuel supplier IOR to provide foundations for new diesel storage tanks on the client’s Lytton Terminal at the Port of Brisbane.
The tanks, with a combined capacity of 60 million litres, form part of a A$50m expansion project, due for completion in June 2023.
“We were initially approached by IOR’s mechanical engineers because of the tricky ground conditions,” said Tony Eid, Keller’s new business manager. “The site was once swampland, so there’s a high amount of organic material and soft clays, as well as a high water-table.
Initially the client had considered removing the compressible soils and replacing them with structural fill, which is how the foundations for the terminal’s existing tank had been installed.
But the high water-table and the proximity of the new structures to the existing tank made this impractical. Keller’s solution was a combination of piling and cement stabilisation, also known as mass soil-mixing.
Although the client was unfamiliar with the soil-mixing technique, Keller promised that this option would save time and money compared with conventional piling.
As well as being used for foundations, Keller used the technique to support excavation work and create platforms for the large cranes required on-site.
Mass soil mixing involves adding a cement binder to soils to stiffen and stabilise them, so a lot of time was spent creating different mixes and running laboratory tests to determine the right one.
Over a period of four months the Keller team carried out 12,198.4m³ of mass mixing, completing the work two months ahead of schedule with a cost saving of nearly A$1m.
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