20 june 2022
Since site mobilisation in January 2022, a substantial cut and fill exercise has been undertaken on the WERF site to construct a level platform at a flood safe height to enable the main Westfield ERF building to be constructed. To ensure that the ground is capable of safely supporting the Westfield ERF for the duration of its operational life, ground improvement was implemented. HZI intended to employ controlled modulus columns (CMC) piling, drilling numerous holes into the soil in a grid pattern. Instead of removing the drilled material from the holes as spoil, the soil is displaced laterally around the diameter of the bore holes, increasing the density of the local soil- improving the bearing capacity of the ground. The holes are then filled with concrete, creating columns for supporting the building loads.
Following extensive ground investigations, HZI decided that a different ground improvement method was more appropriate for the Westfield ERF site and dynamic compaction was employed instead. During dynamic compaction, the ground density is increased by repeatedly dropping a heavy weight from a prescribed height in a mesh pattern. The craters left in the ground are then filled with granular material and compacted, resulting in a reduction of the void ratio and an increased relative density (improving the mechanical characteristics of the soil, both strength and deformability)
The program of dynamic compaction has now been completed, enabling the recently awarded main civils work package to commence with the construction of the main Westfield ERF building. Neil Young, Project Director, said “Now that the ground improvement has been completed the Westfield ERF will begin to quickly take shape, as the main civils works begin”.