A TIDAL barrier could cost as little as existing plans for flood protection walls in Cork city and would have the added benefits of avoiding years of construction disruption in the city centre.
Those were the findings of a new report by an independent civil engineering and environmental hydraulics organisation, which has put forward a tidal barrier option as a real alternative to raising quay walls in the city centre.
The group, Save Cork City, commissioned UK-based HR Wallingford to estimate the cost of a tidal barrier — located 10km downstream of the city between Horse Head and Little Island - with the price coming in at €140 million, based on 2017 values.
The proposed structure would be 950 metres long and would consist of an embankment with a 60-metre wide navigation opening and a number of smaller gates. It has been proposed as an alternative to the existing flood relief scheme designed by the Office of Public Works (OPW), which is estimated to cost over €140m and could take seven years to complete.
The OPW scheme has met with criticism from some architects, businesses and residents about the efficacy of the plans, height of the walls and the extent of construction which would cause major disruption to the city. However, the OPW has previously ruled out the option of a tidal barrier to safeguard Cork city from flooding, estimating that it could cost anywhere between €450m to €1bn to build.
The report by HR Wallingford states that a tidal barrier will “avoid the disruption that construction of the walls would cause and also avoid the impacts that walls would have on the city landscape”.
In addition, the report says a tidal barrier will protect more of the city of Cork as it will include areas to the east of the proposed flood defences and the flood relief scheme.
The tidal barrier cost estimate report was penned by David Ramsbottom, who has 40 years of experience in water engineering and was involved in the technical development of the Thames Estuary 2100 plan in London and Peter Hunter, a civil engineer who was project manager for the Cardiff Bay Barrage and is the Lender’s Supervisor for the $3bn St Petersburg flood defence barrier.
Save Cork City (SCC) — a group of architects, engineers and academics - have campaigned since the beginning of 2017 for an alternative plan to OPW flood defences, which they believe will damage the aesthetic beauty of the city’s quay walls and laden the city with flood barriers which will cut public access to and engagement with the River Lee.
SCC recently outlined its own three-point plan for flood relief, which it believes will provide a “viable and sustainable” solution to the city’s flooding issues. The plan focuses on building a tidal barrier, repairing the quayside landscape and slowing the flow of the river.
SCC decided to commission an independent report on the cost of a tidal barrier following the dismissal of its own costing of €135m by the OPW.
A spokesperson for SCC said: “We can’t keep building walls for flood relief. With climate change resulting in sea level rise and unpredictable weather patterns, we need a more holistic approach.
“The three-point plan of Save Cork City proposes a tidal barrier, sensitive repair of our urban quaysides and upstream river management in conjunction with dam management. The dam, the tidal barrier and the upstream landscape may all react and adapt as new circumstances unfold. Walls are not climate change adaptable and would, in fact, leave us vulnerable to catastrophic flooding.”
A statement from the OPW said: “As part of the public consultation process on the Lower Lee Flood Relief Scheme, the OPW committed to producing a report on the costs surrounding the potential for a tidal barrier in Cork and this report is currently being finalised by our consultants. Its preliminary findings confirm the previously advised position of the OPW that a tidal barrier is not currently viable. OPW cannot comment directly on the HR Wallinford report referred to as it has not been provided to us.”