The project involved installing unfilled tubular steel piles through the edge of the Cashin Quay reclamation and underlying soft sediments. The piles were designed as friction piles to resist the vertical loads, which were confirmed by dynamic pile testing.
The piles were designed to be adequate as temporary repair works but the layout was such that they could be extended to greater depths and incorporated into a replacement wharf, if/when this became necessary.
This project was designed and constructed during the seismic activity of the 2011 Canterbury earthquakes. Given the changing seismic design requirements, the analysis included use of finite element models utilising scaled numerical time history records developed by WSP. The work used similar sophisticated processes to the analysis performed in support of the insurance claim that was peer reviewed by world renowned experts.
One aspect that made the project so challenging was the need to keep the shiploader operational throughout the construction programme. By working closely with LPC, initially loading of bulk vessels from a single point was implemented, by moving vessels up and down the berth in a particular sequence to avoid causing structural damage to the vessel by unbalanced loading. After the 13 June 2011 earthquake, support to the shiploader was compromised. As a solution, an innovative steel truss design, spanning up to 36m, was designed and installed within an 18 day period to reinstate support to the shiploader.
The temporary repair works were minimised by careful consideration of the Level of Service that was actually required just for coal operations, yet locally retaining a heavy duty area for unloading of car ships.