Trehafod Flood Alleviation Scheme

This page provides details about the proposed works and their significance to the community of Trehafod.

Scheme Background

Since 2020, the village of Trehafod has been impacted by internal flooding to properties on four separate occasions.

The most significant rainfall event, designated by the Met Office as ‘Storm Dennis’, occurred between the 15and 16^th of February 2020. The storm resulted in internal flooding to 1,498 homes and businesses across RCT, of which 65 residential properties and 3 businesses were situated in Trehafod.

More recently, between the 23^rd and 24^th November 2024, a rainfall event designated as ‘Storm Bert’ by the Met Office resulted in internal flooding to a further 9 residential properties in Trehafod.

Trehafod is noted as an area of high surface water and ordinary watercourse flood risk based on Natural Resources Wales’s Flood Risk Assessment Wales (FRAW) maps. According to the Welsh Government’s Communities at Risk Register (CaRR) 2024, the community of Trehafod is identified as the 99^th most at-risk community in Wales for surface water and ordinary watercourse flood risk with 132 properties modelled to be at risk. This risk is broadly associated to blocked culvert inlets and potential bank breaches/ overtopping related to the network of ordinary watercourses draining the northern hillsides.

The council has already delivered several interventions in Trehafod to reduce the risk of flooding whilst the wider FAS program is delivered.

• In 2023, 2.49 kilometres of highway drainage and culverted watercourse within Trehafod was surveyed and mapped to assess structural and operational condition.
• In 2024, the Council completed a scheme at A4058 Gyfeillon Road to improve the  capacity of the highway drainage infrastructure to convey surface water to the River Rhondda.
• Following Storm Bert, a further 41.15 metres of culverted watercourse was surveyed at Gyfeillon Road.

Proposed Scheme Objectives

• Reduce the risk to life by reducing the number of people exposed to risk of flooding of significant depth and velocity
• Reduce community disruption by reducing the amount of residential and commercial property exposed to flood risk.
• No detriment to downstream receiving River/Watercourse.
• Improve Community Resilience to Flood Events and Climate Change – promoting sustainability and wellbeing.
• Deliver a preferred option that works with natural processes and promotes green infrastructure.
• Enhance local biodiversity and support the resilience of ecosystem services.
• Improve the resilience of flood risk assets against climate change – promoting accessibility and low maintenance requirements.
• Reduce the impact of climate change – mitigating the extent of the projects carbon footprint.
• Improve community wellbeing through the enhancement of local amenity.

Proposed Scheme Description

This project is intended to manage the risk of surface water and ordinary watercourse flooding to the community of Trehafod by upgrading the Dŵr Cymru Welsh Water surface water pumping station on Trehafod Road, along with associated infrastructure.

The scheme intends to deliver:

• A 1 in 100-year standard of protection, including allowances for climate change, to the local community.
• An increase in capacity for the pumping station , allowing for a greater flow rate and volume to be managed, reducing the risk to properties in the area.
  

Wider benefits include maintaining the community’s significant transport route, specifically Gyfeillon Road (A4058), which is the only primary road that connects the Rhondda Valleys with the Taf Valley, and Trehafod Road which is the principal through-route for the village, serving rows of terrace properties that would otherwise be isolated during severe flooding.

RCT Council, working with Waterco, has already completed a Business Justification Case (BJC), in line with the Welsh Government FCERM Business Case Guidance. This stage involved extensive screening and analysis of various options to address the local flood risk in Trehafod, resulting in the identification of a preferred option for further development.

Public engagement with the relevant stakeholders will be undertaken as part of the next stage of the project, followed by preparation of the Full Business Case to Welsh Government and progression into detailed design phase.

Flood Risk Management 

Highways, Transportation and Strategic Projects,
Rhondda Cynon Taff County Borough Council
Floor 2
Llys Cadwyn
Pontypridd

CF37 4TH

Email: FRM@rctcbc.gov.uk