In response to recurring flooding events in Llanfair Talhaiarn, dating back to the 1970s and five since 2008, Natural Resources Wales (NRW) engaged AECOM to develop a flood risk scheme.
The village, vulnerable to flooding from the Nant Barrog watercourse, required 1% Annual Exceedance Probability (AEP) event standard of protection. AECOM adopted a multidisciplinary approach to safeguard the community.
Tailored flood risk management
Our diverse range of services included hydrological and hydraulic modelling, environmental assessments, and construction support, which underpinned the Flood Risk Management Scheme (FRMS). Employing advanced hydraulic modelling techniques, our expert team determined flood levels, flows, and extents, informing bespoke flood resilience solutions.
The civil design endeavoured to protect the village against future flood events. Noteworthy interventions include the replacement of a 40m long deteriorated brick arch culvert, a new reinforced concrete vehicle bridge and flood walls. Additionally, a robust highway drainage system with non-return valves was installed to prevent surcharge during peak events. Safety enhancements, such as a steel trash screen and improved landscaping and garden access agreed with the Chapel elders/trustees, further highlight NRWs and AECOMs comprehensive approach. The upstream coarse screen helped to prevent 150 tonnes of material reaching the village culvert during Storm Babet (October 2023).
Preservation and community engagement
Aligned with NRW's ecological priorities, our team committed to habitat restoration for migrating fish, eels and otters. Weirs were removed to improve fish migration, while an eel pass was installed along with features to support the local otter population and a vegetated retaining wall was installed to increase biodiversity. Additionally, rock armour was strategically placed to enhance riverbed conditions.
Community engagement was central to the project's ethos, with AECOM actively involving local stakeholders to ensure cultural and aesthetic alignment with the surrounding environment. The scheme's integration with a Grade II listed Chapel and conservation area was complimented, reflecting our commitment to heritage preservation. Our landscape architects specified indigenous flora and Victorian-style ornamental railings to harmonise with the chapel surroundings, enhancing the village's aesthetic appeal.
Safety-first culture and sustainability
As Principal Designer, AECOM instilled a safety-first culture, prioritising the well-being of both workers and residents. Through collaborative efforts, we delivered a scheme that not only mitigated flood risks but also championed environmental sustainability and community resilience.
AECOM's comprehensive approach to flood risk management in Llanfair Talhaiarn is a testament to collaboration and long-term vision. By combining engineering excellence with community engagement and ecological protection, the scheme embodies AECOM's commitment to safeguarding communities and preserving the environment for generations to come.