Case Study
Carrick on Shannon Flood Relief Scheme
OVERVIEW
Ryan Hanley has been engaged by Leitrim County Council as engineering and environmental consultants to develop a Flood Relief Scheme for Carrick on Shannon and Cortober.
The options assessment stage is currently nearing completion and the scheme is due to proceed to planning in Q4 2024. The current construction estimate exceeds €26.M.
Background
Carrick on Shannon and Cortober have a history of flooding from the River Shannon and its tributaries. Major flood events in November 2009, the Winter of 2015 and, to a lesser extent, Spring 2020 have presented the most severe flooding in the area in living memory. Ryan Hanley was appointed to the scheme by Leitrim County Council in Q4 2019. Leitrim County Council are joined on the Steering Group by Roscommon County Council and OPW, the funding authority.
To date, the scheme has progressed through data collection, constraints study, execution of investigation contracts, environmental surveys, hydrological analysis, hydraulic modelling, technical assessments, and is currently undergoing options assessment and development.
The Shannon is the largest river in Ireland. Our hydraulic model extents from Lough Allen at the top of the Shannon catchment downstream past Athlone Town, covering a catchment area of 4,600 km3 and a total model length of >150km. This reach of the Shannon also contains numerous manmade controls, such as ESB operated sluices at Lough Allen, and Waterways Ireland operated weirs at Jamestown, Tarmonbarry, Athlone, Roosky, among others. Ryan Hanley has modelled this hydrologically complex system in Flood Modeller Pro (1D), with urban floodplains modelled using TUFLOW (2D).
Ground conditions in the vicinity of Cortober are particularly poor, creating challenges in the development of engineering solutions. Together with our geotechnical specialists GDG, Ryan Hanley has developed solutions to the technical, environmental and economic constraints involved.
Public participation and stakeholder consultation events took place in 2020 and 2023, with a third event focused on the Emerging Preferred Scheme due to be scheduled in 2024.
