We need many types of machinery and workers on site building the North East Link Tunnels. You may be familiar with piling rigs, cranes, excavators and trucks, but have you heard of a clay plant?

What are clay plants?

We're producing a safe, naturally occurring clay mix, known as bentonite, on site using specialised plants as shown in these images.

We’re using clay plants at our work sites in Yallambie and Bulleen.
The plants store and pump the clay needed to build the large concrete walls and interchanges for the North East Link Tunnels, often referred to in construction as D-walls or Diaphragm walls.

How does it work?

The clay plant mixes raw clay materials with water. Once combined, the mix is pumped into excavated holes to keep them stable, before concrete is poured in. The clay is then forced out by the concrete and the leftover mix is pumped back out and re-used for the next dig.

This is a safe and sustainable way of building the tunnel walls as the clay is continually re-used.

What is a D-wall?

A diaphragm wall, or D-wall, acts as a retaining wall for the tunnel. It is made from concrete and supports the underground structure of the tunnel.