Before any works commenced, Brisbane’s new runway site was low lying with very poor strength soils. Some engineers likened the consistency to toothpaste. Between 2012 and 2017 Brisbane Airport Corporation (BAC) transformed the site by:
- Raising the ground level to be free from flood and climate change impacts
- Improved the strength of the ground to make it suitable for construction of the new runway.
BAC has gone about this challenging endeavour by:
- Placing 11 million cubic metres of sand at varying heights across the site
- Installing 330,000 vertical wick drains into the underlying soils to depths of up to 35 metres
- Leaving the site to settle for three years, to allow the weight of the sand coupled with the straw like action of the wicks to squeeze the water out of the soil
- Monitoring the progress of settlement performance to check when the site has reached a suitable level of settlement to commence building the runway and taxiways.
In 2017, as predicted, the site achieved the necessary ground improvements and moved into the final construction stage for the project.