Diaphragm walls are installed when excavation will be below the groundwater table, and a near-watertight wall is a requirement.

The trench wall is constructed using slurry excavation techniques, with temporary guide walls to maintain correct trench alignment.

Wall thicknesses can vary from 500 mm to 1500 mm, with depths to 50 metres.

Walls are constructed in panels, using end stops to retain the concrete and to form control joints. Concreting is carried out utilising tremie methods, with long panel sections requiring use of multiple tremies to ensure uniform placement of concrete along the wall panel.

Walls are generally load-bearing, depending on design requirements and founding material. Normally, temporary soil anchors are necessary for stability prior to completion of the permanent structure, which will provide the permanent support.