THU, 04 FEB, 2021 - 15:50
Cork City flood relief scheme is our best option
Despite opposition, the Lower Lee Flood Relief Scheme will serve Cork, its people and businesses well, says Dr John Martin, a chartered engineer with over 15 years’ experience in the field of flood risk management
PROTECTION: How the Lower Lee Flood Relief Scheme would look at Lapps Quay in Cork city.
DR JOHN MARTIN
KATHRIONA Devereux’s article on the Lower Lee Flood Relief Scheme (LLFRS), entitled ‘It’s time to think again about flood defences for Cork city’ (Feb 2) presents the (as yet unscrutinised) views of the Lee Engineering and Environment Forum (LEEF).
However, it lacks any response from the Office of Public Works (OPW) — the lead agency for flood risk management in Ireland, or their flood risk management consultants — renowned experts in the field, and in presenting the LEEF proposals, the column appears one-sided and omits or misrepresents important facts.
The article infers that, while the work of a small group of opponents to the scheme is “professional and forensic”, the work of the multi-disciplinary experts, who have worked on the project for more than 14 years, is not.
Critical facts need correction: Firstly, the current Save Cork City Judicial Review proceedings do not relate to LLFRS, but to a decision by An Bord Pleanala to grant permission for a Cork City Council Public Realm project at Morrison’s Island, which includes knee-high flood defences.
Opponents to the LLFRS present a tidal barrier as the silver bullet to solve all Cork’s flooding problems, tidal and fluvial. It is not. Contrary to LEEF assertions, the OPW formerly assessed the viability of tidal barriers at both Little Island and Great Island, undertaking detailed hydrodynamic modelling, consideration by international experts of navigational safety, assessment of statutory environmental issues, and active engagement with Port of Cork.
“Those advocating for a tidal barrier have never demonstrated this level of analysis.
In estimating the costs of the tidal barrier, the OPW has developed a cost model which pre-dated but closely aligns to a model independently developed by the U.S Army Corps of Engineers (USACE) when considering barriers for what is potentially the largest flood defence project in the world in New York.
Professor Jonkman from Delft University in the Netherlands (who was previously commissioned by Save Cork City to undertake some work) has latterly confirmed that this model is now international best practice.
The USACE cost methodology estimates that the Cork barrier would cost equal to or in excess of the OPW’s estimate, confirming that it could cost well over €1billion. When it comes to the accurate costing of tidal barriers, it appears LEEF purport to know more than the U.S Army Corps of Engineers, Professor Jonkman himself, and the OPW’s international flood risk management experts, who all agree that this is the best model.
“While LEEF points to multiple risks associated with the LLFRS, in reality, the risks surrounding a tidal barrier are far greater.
In Venice, the MOSE tidal barrier has recently been completed after 20 years of construction and costing almost €6bn, yet the city flooded on December 8 last, when the barrier did not raise because the forecast under-predicted the height of the tide.
The LLFRS has been developed as part of a long-term climate change strategy for Cork. The work demonstrates that quayside defences will provide the necessary level of protection on their own until at least the end of the century, even in the worst-case scenario being considered by the Intergovernmental Panel on Climate Change (IPCC).
If a tidal barrier were needed by, say 2100, it would still only be viable in conjunction with the raised quayside defences now needed and proposed as part of LLFRS, just like other barriers around the world, including the Thames Barrier and the MOSE barrier.
The LLFRS addresses the risk of water overtopping the quays, and also of water coming up through drainage systems and the ground. It has assessed these flood mechanisms in detail, undertaking extensive CCTV surveys of sewers, geotechnical assessment of the ground, permeability testing, and detailed analysis. The issues are well understood, and the Scheme incorporates extensive systems of drains, non-return valves, and small to medium size pumping stations to address the very issues that contribute to Cork flooding. Neither are these issues are unique or new — they have been successfully addressed in many completed flood relief schemes both in Ireland and throughout the world.
The OPW acknowledges its cost estimate for the LLFRS relates to the 2016 Public Exhibition design, and that the design of the Scheme has since evolved to take into account feedback from the public. This will in turn result in revisions to the costs; some additions and some deductions. Contrary to LEEF’s claims, the 2016 estimate did include for circa €20 million of quay wall repair, which remains an integral part of the project.
The article omits to mention that, when the Final Scheme is submitted to the Department of Public Expenditure and Reform for statutory consent, having taken account of public feedback, a detailed, updated cost benefit analysis will form part of the documentation.
“As with any project of this magnitude, under the Public Spending Code, the LLFRS will need Government approval to proceed to tender, and again to proceed to construction.
As part of this process, the project will be subject to a rigorous External Assurance Process, in the form of peer reviews to test and review the work undertaken.
Many other elements of LEEF’s narrative about tidal barriers, the cost of pumping stations, and much more besides, are misleading, and more space than is available here would be required to deal with them.
LEEF’s flawed analysis parrots the views of the Save Cork City Campaign. Indeed, most of the personnel in LEEF are associated closely with Save Cork City. It risks undermining both public confidence in, and indeed the implementation of, an urgently needed scheme.
The LLFRS has taken on board feedback from the public and is designed to best international standards, to protect the people, properties and future economy of Cork.
Dr John Martin was formally project manager for the Lee CFRAM (Catchment-based Flood Risk Assessment and Management) Study and programme manager for the National CFRAM Programme, he is currently Principal Officer in OPW Flood Project Management Services. He is a graduate of UCC.
Article published by Echo:
Dr John Martin: Cork City flood relief scheme is our best option. Available at: https://www.echolive.ie/corkviews/arid-40220576.html