Westpile [now Bachy Soletanche] was contracted by J Breheny Contractors to undertake the foundation work for a heavy lifting pad, as part of a wider scheme on the North terminal at Great Yarmouth Port. When complete, the development will see the port used for the storage and handling of wind turbine equipment at the Outer Harbour. The enhancement of the port infrastructure is part of multi-million pound investment for the Galloper Wind Farm and East Anglia ONE Wind Farm projects.
To ensure compliance with Westpile’s due diligence procedures, an internal review of the original design was carried out which resulted in a recommendation to Breheny to seek a further review to substantiate the suitability of the original design. Breheny’s review reached the same conclusion as Westpile’s and as a result the original pile design was amended to provide a more robust solution.
This collaborative approach to the design works ensured that the risk of pile failure was mitigated and an appropriate solution would be delivered.
Following the design review, it was agreed that the optimum solution would be to install 122 continuous flight auger (CFA) piles, with a diameter of 750mm and bored to a depth of 23m.
The ground conditions consisted of hydraulic fill to 13m, over very loose sands to 16.5m, over very dense sands to the pile toe at 23m below platform level. The ground water level was tidal and ranged from four to six metres below platform level.
The piles were installed using a Soilmec SF120, this particular rig was chosen for its ability to bore through sands subject to tidal groundwater levels, and therefore ensure the successful execution of the works.
Site production rates exceeded expectations and works were completed one week ahead of programme.