24 April 2019
sponsored by Unibail-Rodamco-Westfield
Ipswich Tidal Barrier - submitted by VBA (Volker Stevin, Boskalis, Atkins)
The Ipswich Flood Defence Management Scheme, approved by the Environment Agency in March 2006, now increases the standard of protection to 0.33% (greater than 1 in 200), including climate change predictions. The scheme improves protection to 1,608 households and 422 commercial properties.
The scheme involved building a tidal barrier across the New Cut River with associated works to tie it into the high ground. Works on site commenced over a decade ago, with the installation of a new flood gate in the Wet Dock and construction of the tie in walls and has now been completed with the construction of the tidal barrier.
It has been a partnership project between the Environment Agency, Ipswich Borough Council and Suffolk County Council. As well as the Haven Gateway Partnership, New Anglia Local Enterprise Partnership, Associated British Ports, and UK Power Networks.
After a thorough tender process, the tidal barrier works were let to VBA (Volker Stevin, Boskalis, Atkins), a joint venture framework contractor to the Environment Agency. It was a Design and Build Contract, managed by Arcadis and supervised by Jacobs.
Work commenced on site in October 2015 with the construction of the cofferdam in the New Cut. This cofferdam was completed in July 2016, giving the team a safe working environment to construct the barrier. In the meantime, the actual barrier gate was fabricated by Hollandia in Holland and the Control Building was also taking shape. It all came together on 6 November 2017, when the new 200 tonne tidal gate arrived from Holland and was slotted into place. Subsequent tests showed that the required 2mm tolerance had been met - an impressive piece of work by the team.
The reference design for the tidal barrier detailed the gate and hydraulic cylinders to have a range of motion from the bottom “open” position up to the top inspection position (0-110 degrees rotation). Further provision was to be provided to enable the cylinders to be disconnected and for the gate to be lifted into the maintenance position (180 degrees rotation) using a large 100 tonne mobile crane. During pre-construction and design, the team developed an operating system for the gate, which allows the main hydraulic drive cylinders to be utilised for the entire operation, eliminating the need for a crane for inspection, painting and other maintenance, leading to long term cost savings as well as safety enhancements.
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The SECBE 2019 Civils Project of the Year Award is sponsored by Unibail-Rodamco-Westfield.