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About AECOM

At AECOM, we believe infrastructure creates opportunity for everyone.

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Innovation & Digital

Our technical experts and visionaries harness the power of technology to deliver transformative outcomes.

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About AECOM

At AECOM, we believe infrastructure creates opportunity for everyone.

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Innovation & Digital

Our technical experts and visionaries harness the power of technology to deliver transformative outcomes.

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Llanfair Talhaiarn Flood Risk Management Scheme

Abergele, Conwy, North Wales, UK

Using extensive fluvial hydraulic modelling, we’ve designed a flood risk management scheme which will protect the Welsh village of Llanfair Talhaiarn during extreme weather conditions.

With a history of flooding, the village of Llanfair Talhaiarn in Abergele, Conwy, Wales, experienced extensive disruption following major flood events in September 2008, June 2009 and two extreme weather events 2012.

We undertook the detailed design of a flood risk management scheme to help protect the village and reduce the risk of flooding from the Nant Barrog, a small, steep watercourse which flows northwards through the centre of the village. The scheme, which was designed following extensive engagement with the local community and CCBC planning department, is located within the Llanfair Talhaiarn conservation area and passes through the grounds of aGrade II listed Soar Methodist Chapel.

Fluvial hydraulic modelling, which informed the design, was undertaken to determine flood water levels, flows and flood extents. The design entailed the removal and replacement of the dilapidated existing brick arch culvert that was restricting the capacity of the original system to a 5% (1 in 20-year) Annual Exceedance Probability (AEP) flow event, the installation of an in-situ reinforced concrete vehicle culvert and flood walls and the development of a highway drainage system with non-return valves to prevent surcharge during peak events.

In addition to providing flood protection during a 1% (1 in 100-year) AEP event, the final scheme will provide considerable environmental interventions. To mitigate for the loss of natural bed we are to remove existing weirs and place natural stone along the riverbed to improve conditions for migrating fish. Options currently being considered for Phase 2 include environmental enhancements such as landscaping and mitigating the impact that the scheme has on the river habitat with the implementation of baffles and resting pools.

Phase 1 was completed January 2019 and phase 2 design is still ongoing.