Background: Bandon, an area of Potential Significant Flood Risk (APSR) is one of the largest towns in West Cork with origins dating back to the early 17th Century. Much of the work undertaken on this flood relief scheme includes both Recorded Monuments and National Monuments. For many years the town and surrounding area have suffered significant flood events that caused damage to properties and losses to businesses. The flooding is primarily due to high flows in the Bandon River and its tributary, the Bridewell River, which exceed the channel capacities. In February 2011, the Office of Public Works, in partnership with Cork County Council, commenced initial feasibility and investigations. This was one of the first schemes to be designed using a pilot Catchment Flood Risk Assessment and Management Studies (CFRAM Study). The CFRAM Study policy was a shift to catchment-based, flood risk-management measures. In 2011, the OPW appointed Ayesa as the lead consultant to the scheme. Our scope included the hydrological studies and assessments, hydraulic modelling of flood flows in the Bandon River and its tributaries, examination of flood risk management options, and selection of preferred options based on environmental, social, technical, and economic criteria.
There were five distinct stages in the project, and Ayesa provided assistance and consulting support across all stages and acted as Employer's Representative:
- Stage I: Feasibility Study and Preparation of a Flood Risk-Management Plan;
- Stage II: Public Exhibition;
- Stage III: Detailed Design, Confirmation and Tender;
- Stage IV: Construction;
- Stage V: Handover of Works.
We prepared the final plan and the Flood Risk Management Plan and public exhibition documents to receive statutory approval and ministerial sign-off on the scheme. In addition, our team carried out the geotechnical and structural design for the flood defences. This included: the design and specification of reinforced concrete flood defence walls, the design of piled foundation, piers, and deck for a new pedestrian footbridge, design and specification of flood defence embankments. To increase the flow capacity of the river, it was necessary to dredge over 3.6km of the river floor and banks. This d
redging of the river bed was extensive - to 9.5 metres downstream of the Bandon weir (approximately 1.8m below the existing bed level) in the town and at a grade of 1/1000 until it reached the existing bed level 3.6 kilometres downstream from the town. Approximately 150,000m3 of material was dredged. The project team enforced the Construction Environmental Management Plan (CEMP) which included sediment management and solids monitoring plans. Inland Fisheries independently monitored the CEMP to ensure the environment was not adversely impacted throughout the extensive dredging process. Works were carried out throughout the town of Bandon, and extensive traffic management and Environmental Mitigation works were required throughout the scheme phases.
New flood defences were constructed to contain flood water within the Bandon and Bridewell River and the Mill Stream. The scheme also included
the construction of new defence walls and embankments along the Bandon River, the underpinning/mini pilling of Bandon Bridge which required extensive archaeological works and temporary protection and the construction of a rock ramp for fish passage. Additionally, rip-rap revetment details were designed for the dredged profiles of the river. The old steel footbridge was replaced with a new three-span steel footbridge to increase capacity and safety. Further works included the construction of new RC culverts, local drainage works in and about the town of Bandon together with extensive brick paving and landscaping.
Scheme elements:
- River dredging
- Flood defence walls
- Embankments
- Pumping stations
- A new pedestrian footbridge
- Fish pass construction
- An underpinning of Bandon Bridge.
Official opening of Bandon Flood Relief Scheme: On 9 December 2022, the completion of the new Bandon Flood Relief Scheme was officially marked by the Minister of State for the Office of Public Works, where Minister Patrick O’Donovan unveiled a plaque to mark the completion. Read more
Innovation/ Value Add
The client tasked Ayesa to deliver a passive scheme with as little human intervention as possible. Through intelligent design and detailed planning, the scheme was almost entirely passive, with no human intervention required for the scheme to perform, a significant win for the client.
.png)
