A tidal barrier like those protecting New Orleans could be built in Cork for €140m, an independent report suggests.
International engineering and hydraulics company, HR Wallingford, believes a tidal barrier would protect more of the city from flood risk than the OPW’s controversial Lower Lee flood relief scheme — the single largest investment in flood defences in the history of the State.
The news comes as the OPW finalises its analysis of the 1,250 public submissions made on its Cork City flood defence plan. Its reliance on raised quay walls has sparked controversy, with the Save Cork City campaign group a vocal opponent. It has called for its alternative plan to be considered — a downstream tidal barrier and upstream catchment management measures.
The OPW has consistently ruled out its proposals, saying a tidal barrier could cost up to €1bn, and that the upstream measures would not provide adequate protection against fluvial flooding.
John Hegarty of Save Cork City said: "The report confirms the suitability of a tidal barrier solution for Cork. It confirms the certainty of the cost of the tidal barrier at €140m.
"A tidal barrier gives extensive protection to the city of Cork from flooding, including protecting vital infrastructure. It would protect the historic centre of the city and boost the future viability of the local economy including tourism and local business.
"A tidal barrier provides faster flood relief and is environmentally the better choice for the City of Cork. It is fully adaptable to climate change, ensuring Cork is protected for generations to come. The tidal barrier represents better value for money for the taxpayer."
HR Wallingford, a civil engineering and environmental hydraulics firm based in England, said the tidal barrier plan proposed by the Save Cork City group, which has been ruled out by the OPW on mostly cost grounds, is viable and would work.
The campaign group’s alternative plan has the major benefit of not requiring the construction of raised walls along the city’s quays, it would help to maintain the historic landscape of the city, and would avoid the disruption caused by construction, the firm says.
Mr Hegarty also claimed that the costs of a tidal barrier are predictable and represents "a far safer" solution for people at risk of flooding.
He said: "We believe that a tidal barrier solution provides greater certainty for the city. It is a contained project and has very few unknowns. It can be constructed in two years, with no interference with trade or infrastructure.
"Cork will get flood relief faster and more economically with a tidal barrier."
Save Cork City is opposed to the scheme’s reliance on raised quay walls and has suggested an alternative plan — the construction of a downstream tidal barrier combined with upstream catchment management.
The OPW has consistently ruled out a barrier on cost grounds, suggesting that it could cost somewhere between €500m and €1bn, and warning that it would do nothing to protect the city from fluvial flood risk upstream.
Mr Hegarty gave his reasons as to why the council should not use walls to protect the city from flooding.
He said: "We have been assured by the minister that funding for flood relief in Cork has been approved for the city. In addition, we have been assured that the city won’t be forced into accepting the Walls as flood relief.
"The Walls scheme would set a new and dangerous precedent for Cork with water pumping systems and miles of walls ensuring the likelihood of a future dangerous breach in the defences leaving the city more likely to be flooded in the future. Walls as flood defences are not a progressive or sustainable solution to flood relief and would restrict the development of Cork.
"If Cork wants flood relief and to become a centre for international investment the only choice is a tidal barrier.
HR Wallingford’s technical director, David Ramsbottom, who was involved in the technical development of the Thames Estuary 2100 Plan, and civil engineer Peter Hunter, who was a project manager on the Cardiff Bay Barrage and who is the lender’s supervisor for a group of European banks for the $3bn St Petersburg Flood Defence Barrier, examined the campaigner’s proposal.
Their report says a tidal barrier could be built 10km downstream of Cork City, at a location proposed by Save Cork City between Little Island and Horse Head, for an estimated €140m based on 2017 figures.
The proposed structure would be about 950m-long and would consist of an embankment with a 60m wide navigation opening and a number of smaller gates.
“The main cost elements are the gates and the embankment, but the costs also include environmental mitigation measures and public amenity facilities,” they said.
Mr Hegarty stressed that his group and other groups concerned about the flood relief scheme "only want the absolute best for our city".
He said: "Vast additional areas of the city would be protected by the tidal barrier. Our economic future would be supported by the tidal barrier. Vital infrastructure which includes roads and rail routes would all be protected. In particular the routes of emergency services would remain open and protected by the barrier.
"A tidal barrier works as a part of an integrated flood defence system that can adjust to the needs of the future. It is the only solution for Cork that can reasonably adapt to sea level rise. It is the only solution for Cork if we are to have viable and extensive flood relief that would help to establish our position as a serious location for international investment.”
Additional reporting by Eoin English of the Irish Examiner