The Ipswich Flood Barrier

The Environment Agency is the main organisation driving this project, in partnership with Ipswich Borough Council and The Haven Gateway Partnership. The initial task was to produce the Ipswich Flood Defence Management Strategy. This was approved by DEFRA (Department of Food and Rural Affairs) in March 2006 with an estimated price tag of 45 million pounds. The objective was to ensure that the centre of Ipswich would have only a 1 in 300 chance of tidal and fluvial (river-flow) flooding each year in a 100 year period that is, until 2106.

The works connected to the project go much further than just a river barrier which can be raised and lowered. They involved strengthening the defences all around the upper part of the river estuary to the east and west of the lock gates, which were built in the 1970s. To quote the Agency's :-

“Similar to the Thames Barrier, although quite a bit smaller, the 20 metre wide gate will rise during periods of extreme high tides to hold back the North Sea and, with the help of the sheet piling, keep Ipswich dry.

When finished, the works will reduce the risk of flooding to 1,608 homes and 422 businesses and support key infrastructure such as the fire station and council buildings. Everything upstream of the barrier will be protected against a tidal surge like the one experienced in 1953 and, more recently, in 2013. That will be hugely reassuring to the home and business owners on the waterfront, many of whom suffered thousands of pounds worth of damage and disruption after the tidal surge in 2013.”

Andrew Usborne, Project Manager for the Environment Agency

The other works required were to replace and relocate two huge power cables in sizeable vertical and horizontal shafts taking them well beneath the Wet Dock lock entrance in a chalk layer. One of the main consumers of this electricity is the Port of Felixstowe, so breaking the power supply was not an option. Also there was flood gate replacement at the Wet Dock entrance and refurbishment of the Handford and Horseshoe Weir sluices. The tripartite project involved Associated British Ports (ABP), UK Power Networks and the Environment Agency.

Ipswich Society members view the Ipswich Flood Barrier in the evening sunshine; composite picture taken on Tuesday July 19, 2016 from offices near the end of Bath Street.

The tender for the movable tidal barrier was awarded to the main contractor, VBA in Holland,in November 2014. Anyone aware of the history of the silting up of the Orwell will not be surprised that dredging works were important to ensure that the barrier would fit. Dredging, unsurprisingly, will play its role in the future, too. A cofferdam, a temporary watertight enclosure pumped dry to enable the barrier's construction at the southern entrance to New Cut, was completed in 2016.

The tidal gate itself will be delivered in April 2017 and will become operational in the spring of 2018. This is a major engineering project happening at the end of Bath Street with a shifting cast of medium cranes, huge cranes, pile-drivers, concrete-pourers, metal structures and changing staff specialists, labourers, engineers and managers. It required an Act of Parliament to build it with a range of licences, conservation consents and legal agreements. When complete there will be an unmanned control room on the southern end of the Island site (see illustration). Sophisticated monitoring and modelling systems will give ample warning of potentially extreme weather and tidal conditions - then staff will operate the barrier appropriately. However, most of the time the 20 metre high radial gate will remain underwater in its recess in the river bed.

The projected final cost is 58 million pounds. Once completed the scheme will unblock various developments in the town, so the effect of the barrier goes far further than managing water. We should all be grateful for this investment in our town and the wider benefits upriver. The original prediciton was that the Ipswich barrier would be raised once every four years; the computer projections for global warming suggest that this might rise to six times per year in 100 years time.

R.G.