Retaining wall finds a new role

Construction of water-sensitive urban design

The increasing popularity of bio-retention basins in water-sensitive urban design has created a new role for the MassBloc earth retention system.

A MassBloc retaining wall was recently deployed in the construction of a bio-retention basin on the edge of a new residential development, Fernbrooke, at Redbank Plains south-east of Brisbane.

After an original plan to use gabion walls was rejected by the council, civil contractor company Pensar turned to the MassBloc system, which provides an attractive and economical earth retention structure that is also easy to transport and quick to install.

Pensar project manager Steve Carter said the installation went fine “once we worked out the detailed design”.

“Because of the sloping site we had to create stepped foundations,” Steve said. “Plus there was an outlet pipe running through the wall requiring an in situ surround that had to fit the shape of the Rocla blocks.”

A mix of full and half blocks was used to create the wall, which varies in height from 1.5 to 4 metres, with some of the full-size blocks half-buried.

The MassBloc system is suitable as a retaining structure for bio-retention basins. The massive blocks (weighing around 1.8 tonnes) are permeable and are simply stacked in place, interlocked by a nib precast into the base.