Before the footings are embedded, large volumes of water have been pumped from metres beneath the surface to dewater 
ready for excavation.
This water is typically acidic, and minerals such as iron, which when brought to the surface, can affect local vegetation and wildlife. The underground water is tested and treated to bring the quality to a safe level.
Once the water is pumped from the excavation, it flows to a dosing unit, which treats the acidity, and through to an aeration unit in a settlement basin. A big silt curtain surrounds the works to contain silt.
In the past month, Macmahon has installed a temporary crane pad on the river foreshore so that the crane can access the river bridge pier area during construction.
The works have been managed in partnership with the Swan River Trust.