Groundforce Shorco has implemented a groundbreaking solution at Westbere wastewater treatment works.
- Main contractor Clancy installs a storm tank to prevent sewage discharge into River Stour.
- An octagonal excavation supports an efficient installation process for the circular storm tank.
- Groundforce Shorco’s Mega Brace system ensures stability in challenging conditions.
- The project minimises environmental impact through reduced material use and carbon footprint.
At the Westbere wastewater treatment works near Canterbury, a new storm tank is being constructed by the main contractor, Clancy, for Southern Water. This infrastructure aims to manage surface water surcharges during intense rainfall, thereby preventing the discharge of untreated sewage into the nearby River Stour.
The storm tank features six precast concrete rings, each 15 metres in diameter, stacked to a depth of 6.5 metres. These rings are composed of 16 interlocking segments, produced by FP McCann and distributed by Keyline. To facilitate this construction, Clancy has undertaken an octagonal excavation reaching seven metres deep.
Groundforce Shorco has equipped the project with 120 interlocking six-metre GFI steel sheet piles, installed using an excavator-mounted Mueller MS4 vibrating hammer from Groundforce’s Piletec division. Initially, Clancy excavated to about a metre, bracing the top of the cofferdam with Groundforce Shorco’s modular hydraulic Mega Brace system before proceeding to the formation layer and base slab casting.
As Clancy project manager Oliver Smart explained, ‘The excavation is octagonal because it makes no sense to dig a rectangular hole for a circular tank.’ This approach minimises the excavation footprint, reducing material and equipment requirements. ‘The octagonal shape has reduced muck away by 20%, amounting to 200 cubic metres,’ added Groundforce Shorco’s area sales manager Arpad Nagy.
The adaptability of the Mega Brace system was crucial in addressing the excavation’s challenges, allowing for easy installation regardless of shape. The innovative design also contributed to a 10 linear metre reduction in sheet piling and 30 linear metre in bracing. This efficiency not only optimises resource use but also significantly decreases the project’s carbon footprint.
This project highlights a forward-thinking approach in civil engineering, employing innovative design to enhance efficiency and sustainability.
