OPW rejects Cork’s alternative flood plans as ‘simply not feasible’

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The Office of Public Works has rejected as “simply unworkable” a retired professor’s theory that a new upstream reservoir combined with a downstream tidal barrier can protect Cork from flooding for half the cost of his relief plan. Lower Lee flood plan of 150 million euros (LLFRS).

As the city prepared for the second major flood in less than two months, the OPW mounted a strong critique of a detailed article presented by Philip O’Kane, retired professor of civil engineering at University College Cork, at the recent National Hydrology Conference. .

Professor O’Kane argued that a tidal barrier at any of the four locations, to be operated in conjunction with the ESB dams on the River Lee, is a “realistic and viable alternative” to what he described as the “14.5 km of embankments, walls, breached and demountable walls, and groundwater pump scheme ”as proposed in its LLFRS.

He suggested that his approach would be half the cost of the € 150 million LLFRS, protect more of the city from river, tidal and groundwater flooding, avoid converting the city center to a construction site by second time in a generation, and it would retain the character of the 800-year-old port city.

Making comparisons with Belfast and Singapore, he said that active control of water levels within the city could facilitate sailing, windsurfing, kayaking, and dragon sailing on a coastal freshwater supply and flood control reservoir. .

His theory has two parts.

First, he suggests increasing the capacity of the existing reservoir at Carrigadrohid and creating a new reservoir at Dromcarra, further west, to help reduce the risk of river / river flooding from the west.

The OPW said this was considered as part of the LLFRS and was scrapped for a number of reasons, including technical difficulties in increasing the Carrigadrohid Dam without compromising the dam’s safety, which had a negative impact on the internationally designated environmental site announced in Gearagh, displacing some 80 owners, and negatively impacting both the existing and proposed road infrastructure.

“Professor O’Kane’s proposal does not meet the project’s goals of being technically, socially, environmentally and economically viable,” said a spokesperson.

Second, Professor O’Kane suggests protecting the city from eastern tidal flooding by using a barrier or tidal barrier, working in conjunction with what the OPW said would be some of the largest pumps in the world. world, to effectively pump the River Lee into Tivoli.

Professor O’Kane makes comparisons to the tidal spillway in Belfast and the tidal barrage in Singapore, but the OPW said neither of the comparisons was appropriate. “The tidal dam in Belfast is to keep the water in at low tide, not to keep the water out at high tide,” the spokesman said.

“It does not and will not provide the required standard of protection against tidal flooding and consequently, like Cork, Belfast City Council has developed a tidal defense solution consisting of around 8 km of parapet defenses at the docks, the most of which are upstream of the dam. “

“The plan is currently out for tender for construction, so Belfast will soon have the necessary protection.

“This is an example of projects in other jurisdictions that are claimed completely out of context, creating unnecessary confusion.

“So is the comparison with the huge pumping and bombing station in Singapore, which cost hundreds of millions, and was built to turn the area into a freshwater lake, to provide drinking water for half a million people.

Brock Lewin of Badger & Dodo, South Mall, Cork, collecting his emergency flood protection sandbags from the Cork City Hall depot on Anglesea Terrace. Image: Dan Linehan
Brock Lewin of Badger & Dodo, South Mall, Cork, collecting his emergency flood protection sandbags from the Cork City Hall depot on Anglesea Terrace. Image: Dan Linehan

“Its upstream catchment is less than one-tenth that of Cork and is fully urbanized and densely populated.

“While it provides additional benefits such as tidal protection and recreation, the context and the business case are not relevant to the situation and needs of Cork.

Neither OPW nor the Cork City Council envisage any scenario in which turning the River Lee into a lake is appropriate or acceptable. ”

The spokesperson said Professor O’Kane acknowledged at the conference that his cost estimates were essentially his best guess.

The OPW said its costs did not include other capital project costs, or the huge operating and maintenance costs, while its cost reports did.

“Technically feasible options for a storm surge barrier far enough downstream to avoid the need for pumping have been studied in depth as part of the LLFRS, with estimated lifetime costs of around € 2 billion using robust estimation methodologies for costs similar to those used by New York City, “the spokesman said.

“A tidal barrier or a bombardment is not a viable option.

“Professor O’Kane’s work does not consider its adaptability to climate change or its resilience to design exceedance events, factors that were carefully considered in the development of LLFRS.

“In summary, Professor O’Kane’s proposal for the management of the Lee River floods is a combination of measures, all of which have already been evaluated as part of the LLFRS and have not been found feasible or appropriate for the specific problems of Cork.

“LLFRS represents the only viable solution.”



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