2.1.4 Trench Excavation and Spoil Handling

Figure 3 Staged construction of road deck – sections of the deck will be constructed in 4 stages (sequentially)

2.1.4 Trench Excavation and Spoil Handling

Trench excavation will be carried out in layers (starting at the southern end) as shown in Figure 4 with installation of temporary struts and ground anchors as the depth increases. As excavation progresses, steel waler beams and struts will be installed in combination with ground anchors to support the piled trench walls. In addition, shotcrete and/or rockfall mesh with pins will be applied to the sides of the trench to stabilise the excavation face. Shotcrete will be spray applied, rockfall mesh is installed by driving short pins into the soil and attaching the mesh to the pins. As the trench becomes deeper, excavators and loaders will be located inside the trench to break material from the natural face of the trench and transport material to stockpiles. On the construction deck above, cranes and excavators will reach down to remove material from the trench to load onto trucks for offsite disposal.

Figure 4 Excavation - Layers