Oakley Creek – Downer – Diaphragm Wall

In February 2020, an active slip in the Oakley Creek Esplanade Reserve started undermining the shared path on Great North Road, which started to damage the key arterial route of Great North Road. Auckland Transport engaged Beca & Downer to undertake this critical work to stabilise the slip and repair the road network.

March Construction were engaged by Downer on behalf of their client AT to construct 68nr 600mm wide low strength Dwall panels to form an inground lattice structure 22m deep to stabilize the slip located near the Entrance portal to the Waterview Tunnel.

This lattice structure was required to resist the lateral movement of the unstable block of soil. The project had originally been designed around Cutter Soil Mixed panels, however due to the high plasticity index of the soil, it was decided to proceed with a dig & replace option using Dwall techniques. This switch in methodology allowed the team to significantly reduce the temporary works requirements for the working platform. It ultimately proved to be a faster and cheaper means of construction for the client.