The challenge
As one of the UK’s key infrastructure projects, the expansion of the Port of Tilbury has had responsible and considerate construction at its core throughout. To maintain this, we've worked closely with principal contractor GRAHAM to provide a flexible, smart and sustainable groundworks support and monitoring solution, enabling the safe delivery of the project’s required excavation work.
Forming part of the site’s drainage strategy, three new attenuation tanks were to be installed at the dock for the collection of surface water, prior to its discharge. To enable the installation of the attenuation tanks, three 70-metre long, 10-metre wide and 7-metre deep excavations were required. Appointed by GRAHAM, we were contracted to design and supply the groundworks equipment for the project.
Our solution
Working with GRAHAM, our team of engineers designed a bespoke and modular groundworks scheme for the project, featuring two levels of Supershaft Plus (the four-way hydraulic bracing system) and Super Bracing Struts, to ensure the steel sheet piled walls of the excavation remained stable during this process.
However, as work began on site, it became clear that the ground conditions were different to what initial ground investigations had indicated.
Joe Waller, Business Development Manager at Mabey Hire, explained further: “From the initial investigations, we were expecting the clays to be very soft – something that had been reflected in our initial engineered scheme design. However, as the work progressed, it became clear that the ground was in fact of a far better quality, meaning we could reduce the kit to one level of bracing and struts and provide a more environmentally friendly solution. Our engineering team revaluated the scheme design and amended it in line with the real-time conditions we were seeing on site, allowing the design to be changed frequently as our customer progressed with the excavating works.”
Demonstrating our ability to react and adapt to unexpected challenges, the groundworks scheme was changed from a two-frame solution to a one-frame solution, significantly reducing the amount of steel required. To give the customer complete peace of mind, our innovative wireless prop-load monitoring solution, LIVEpin, was fitted on the steel struts.
Joe continued: “Given the dramatic change in scheme design, with essentially half the amount of steel used, our monitoring solution provided our customer with additional confidence in the revised geotechnical design. It also enabled both GRAHAM and our engineers to monitor the groundworks equipment in real-time through our Insite portal to ensure it was performing as intended throughout the excavation works.”
While the groundworks design itself changed, one thing present in both the initial scheme and that delivered on site was the theme of sustainability, with our commitment to supplying modular equipment. The 200 tonnes of equipment supplied could be reused on each excavation. Not only did this heavily reduce the amount of steel used on the project, improving efficiency, it also meant that fewer vehicle movements were required to deliver the equipment to site, further minimising the project’s carbon footprint.
Joe concluded: “The Port of Tilbury project demonstrates how unpredictable construction can be. Conditions can change by the day and, as a temporary works specialist, it is vital that you have the experience and knowledge to enable you to react. As a result of our engineering team’s skill, the works were unaffected by the unexpected ground conditions and our groundworks equipment was supplied to site on time and in full, providing GRAHAM with the tools it needed to undertake this complex project.”
Our equipment remained on site until September 2020, with the Port’s expansion works completed later that year.
