Biaxial Geogrids

The construction of a 480 m long quay structure and deep-water berth at the Port of Belfast posed major geotechnical and engineering challenges due to extremely poor ground conditions across a 50-acre brownfield site. The land, located within Belfast Harbour near George Best Belfast City Airport and the Titanic Quarter, required extensive stabilisation before it could support a £50 million trans-shipment and storage facility for the offshore wind sector. This large-scale infrastructure project, developed as part of a joint venture between Dong Energy and Scottish Power Renewables, was critical to supporting the West of Duddon offshore wind farm. The facility was designed to handle, store, and assemble oversized wind turbine components, requiring the use of heavy tracked cranes and high-capacity handling equipment. These operations imposed extreme load conditions on the ground, making soil stabilisation and load distribution essential. The quay structure itself added further complexity. It consisted of a combi-wall system using 1600 mm diameter tubular piles up to 32 m long, combined with 22 mm sheet piles. The structure was tied back to an anchor system supported by 376 raking piles, each 30 m in length. Additionally, a 17,000 m² quay slab was supported by 780 CFA piles of 750 mm diameter. Without significant ground improvement, the underlying soils would not have been capable of supporting these structural and operational demands.

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The development of a £100 million Carbonaceous Biomass Facility for MWH Treatment Ltd presented significant geotechnical challenges. Located at Ince near Helsby, Cheshire, the site sits within the Ince Marshes floodplain of the River Mersey, an area well known for poor ground conditions. The project aimed to replace a previously approved bioethanol plant with a modern biomass energy facility capable of processing up to 175,000 tonnes of fuel annually and generating renewable electricity for approximately 37,000 homes, alongside potential heat and steam supply for local industry. However, the underlying soil profile posed a major obstacle. The site is characterised by deep deposits of soft alluvial clay and peat extending to depths of around 10 metres. These materials exhibit extremely low strength, with a minimum undrained shear strength of just 7. 5 kPa. Such weak subgrade conditions significantly increase the risk of excessive settlement, bearing failure, and instability under heavy construction loads, particularly from cranes and piling rigs. Given the scale of the infrastructure and the intensity of construction activities, a conventional foundation or working platform solution would have been inefficient, costly, and potentially unsafe. A robust ground improvement and load distribution strategy was therefore essential to ensure both construction viability and long-term performance.

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Barnet Council, working alongside main contractor Willmott Dixon, embarked on the development of the Oakleigh Road South Vehicle Depot, a key infrastructure project designed to support the borough’s waste collection and recycling operations. The facility includes refuse vehicle parking, maintenance buildings, cleaning bays, refuelling stations, and a covered bulking area for efficient waste handling and transfer. A critical aspect of the project involved upgrading the pavement structure at the site entrance and junction off Oakleigh Road South to accommodate frequent Heavy Goods Vehicle (HGV) traffic. These vehicles impose substantial loads, making pavement durability and long-term performance essential. However, challenging ground conditions posed a significant risk. The site exhibited a general California Bearing Ratio (CBR) of 3%, with weaker zones dropping to as low as 1%. Such low CBR values indicate poor load-bearing capacity, increasing the likelihood of rutting, deformation, and premature pavement failure. As a result, an effective ground stabilisation and pavement reinforcement solution was required to ensure structural integrity under heavy traffic conditions.

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