Storm Dennis anniversary – flood alleviation and structures update

Written by on 16th February 2022

To coincide with the two-year anniversary of Storm Dennis, Rhondda Cynon Taf Council has provided a detailed update on ongoing infrastructure repairs as well as the significant investment in flood alleviation work in communities.

Storm Dennis brought unprecedented weather from February 15-16, 2020 – it flooded 1,498 properties and caused severe damage to town centres, rail and road networks, business parks and leisure facilities. The Council’s extensive response included supporting emergency services, setting up rest centres, providing emergency funding to families and coordinating a large food appeal.

Rhondda Cynon Taf Council also began assessing the widespread infrastructure damage. Acknowledging that the repair effort would be ongoing for years to come, the Council committed to a comprehensive investigation into what happened, to develop and deliver repairs, and to invest in targeted flood alleviation work.

In the past two years, we have experienced 28 storm events including the three major storms in February 2020 of Ciara, Dennis and Jorge. Since February 2020, our Flood Risk Management Team has:

  • Investigated 4,036 reports of flooding.
  • Inspected more than 50km of watercourse/drainage infrastructure, and 10km of ordinary watercourse and associated catchments.
  • Removed around 2,500 tonnes of debris from these assets.
  • Completed 28 Flood Investigation Reports.
  • Developed 19 reports in accordance with Section 19 of the Flood and Water Management Act 2010 (of which nine are published).

An accelerated capital programme targeting 108 flood alleviation schemes is also being delivered, investing £13m by March 2022. Progress ranges from developing business cases to design and construction. Key schemes include:

  • Pentre Road Inlet – major upgrades are complete, including a new culvert inlet, debris basin, overflow structures and monitoring equipment.
  • A4059 at Aberdare – significant work to provide resilience to flooding,between Asda and Tinneys roundabouts, has been completed.
  • Cwmbach Industrial Estate – a scheme to provide overflows and flood routing has been completed.
  • Bronallt Terrace Inlet, Abercwmboi – work to upgrade the ordinary watercourse culvert inlet and barrel has been completed.
  • Pentre Flood Alleviation Scheme (FAS) – work continues to progress a business case for proposals to mitigate flood risk in the community.
  • A4061 Rhigos Road – work continues on site to upgrade two ordinary watercourse culverts on the section of road near Tower Colliery.
  • Treorchy FAS – work continues to progress a business case for proposals to mitigate flood risk within the community. A first phase of advanced work will start in March, subject to grant approval.
  • Glenboi Pump Station FAS – advanced work and detailed design is complete, to facilitate an upgraded surface water pumping station.
  • Glenboi/Fernhill Highway Drainage Upgrades – a major upgrade of the highway drainage network is ongoing.
  • Rhydyfelin Drainage Upgrades – work continues on site to upgrade the drainage infrastructure in and around the community.
  • Bronallt Terrace FAS, Abercwmboi – business case and design work is complete, with construction to start in March, subject to grant approval.
  • Heath Terrace, Ynyshir – work is ongoing to upgrade a culvert inlet and channel, aimed at increasing resilience during heavy rainfall.
  • Allen Street, Mountain Ash – significant channel upgrades and repairs are underway, to reduce the risk of flooding in the community.
  • Monitoring Equipment – work to expand the Council’s monitoring stations has completed installation at 25 sites with a further five to come.
  • Enhancing resources – the Council has set up a new Pluvial Drainage Team and also secured approval from Cabinet to set up a dedicated Tip Safety Team, to improve upon the existing capabilities in these areas.

Various repair schemes to other infrastructure – including bridges, walls and landslips – are also being delivered right across the County Borough.

Among the completed schemes are M&S Bridge (Pontypridd), Canning Street, Bailey Street and Maindy Street Bridges (Ton Pentre), Castle Inn River Wall (Rhydyfelin), Merlin Bridge (Hopkinstown), Cross Street River Wall (Ynyshir), Sion Street River Wall (Pontypridd) Ynys Meurig Bridge and Nant Clydach Bridge (Abercynon). The below list includes key schemes which are ongoing:

  • Feeder Pipe Footbridge, Abercynon –the structure was demolished and feasibility studies are ongoing for its replacement in 2023/24.
  • Ty’n y Bryn Footbridge, Tonyrefail – emergency repairs were carried out, and site investigations and design are ongoing for its replacement.
  • Iron Tram Bridge, Robertstown – Scheduled Monument consent was granted to undertake repairs, which are currently taking place off site.
  • Blaencwm River Wall – a contractor is undertaking the final stages of repairs, which will allow Blaen-y-Cwm Road to be fully reopened.
  • Berw Road River Wall, Pontypridd – full repair work is programmed after initial emergency works were undertaken following an inspection.
  • Berw Road Bridge (White Bridge), Pontypridd – initial repairs allowed the bridge to reopen, with a full repair programme planned this summer.
  • Pontypridd Road River Wall, Porth – initial repairs have reduced the risk of the structure collapsing, with full repairs planned for 2022.
  • Maerdy Mountain Road – retaining wall improvements were undertaken last summer, and final design work is ongoing.
  • Ynyshir Community Route landslip – final reinstatement of the cycle route is progressing, with reopening of the route anticipated shortly.
  • Tylorstown Landslip – significant site activity has seen the removal of the majority of slip material and returning the river to its former alignment. Public consultation on Phase 4, making the hillside safe, is ongoing.
  • Castle Inn Footbridge, Treforest – a planning submission has been made for works to replace the existing bridge with a single span bridge, with works set to take place this summer.
  • Tonypandy River Wall – surveys and design work are ongoing, in order to repair the scour damage.
  • Gelligaled Park Footbridge, Ystrad – repairs are planned this summer.
  • Brook Street Retaining Wall, Porth – emergency work was completed after Storm Dennis, with surveys and design for additional work ongoing.


Councillor Andrew Morgan, Leader of Rhondda Cynon Taf Council and Cabinet Member with responsibility for Highways and Transportation, said:

“This update on the two-year anniversary of Storm Dennis shows the considerable work that the Council has completed, and continues to deliver, right across the County Borough following the unprecedented storm event. Significant time and resources continue to be spent investigating what happened, carrying out repairs and delivering targeted flood alleviation work.

“The work of our Flood Risk Management Team has included investigating more than 4,000 reports of flooding from 28 storms since February 2020, and investigating and removing debris from more than 60km of watercourse – the majority of which is underground. Investigating what happened in Storm Dennis remains a priority, to ensure we are better prepared for future events – and this has resulted in nine Section 19 flood reports being published so far.

“Out in our communities, more than 50 flood alleviation or drainage schemes have already been completed, with another 50 in development. By the end of the current financial year, our investment in this area will be more than £13m since Storm Dennis. Work is also ongoing to supply high-risk properties with equipment to alleviate the impacts of future storms, including expandable barriers. So far, around 400 homes have been provided with this support.

“Our funding for coal tips is also significant, with £7m spent since Storm Dennis to increase monitoring with partners, develop schemes and carry out works on site. The major slip at Tylorstown has resulted in a comprehensive Remediation Plan being followed – of which the next phase, removing the remaining slipped material from the hillside, is currently being consulted upon. We have also worked closely with Welsh Government and The Coal Authority to secure works to stabilise the privately owned Wattstown Standard Tip.

“For other structures such as walls and bridges, the Council faced a huge task to assess the damage following Storm Dennis and begin to develop repair works. Progress to date has seen a number of large projects completed – including M&S Bridge in Pontypridd and Ynys Meurig Bridge in Abercynon – and many others in development or being progressed on site. The update provided by the Council today outlines progress on some of the key schemes.

“Residents can be assured the Council will continue all aspects of its work relating to flood alleviation as a priority, to ensure we are as prepared as possible for the likelihood of future storm events due to climate change. We have also set up an Emergency Control Room to coordinate our multi-agency response during future storms and other emergencies, so we can get a more accurate picture of any developing situation and deploy resources to communities more efficiently.”

Natural Resources Wales has been working in partnership with the Council to carry out repairs and upgrades since the 2020 storms, and undertake regular checks at key locations across the County Borough all year round.

Michael Evans, Head of Operations South Wales Central at Natural Resources Wales, added:

“We do not underestimate the impact that the February 2020 storms had on communities in Rhondda Cynon Taf and our thoughts remain with those still recovering and rebuilding today. When considering how to defend areas across Wales most at risk from flooding, NRW will always work with local communities to identify the best combination of measures to tackle specific threats.

“As well as carrying out repairs and undertaking checks to flood defences across the Borough, NRW as has been carrying out detailed flood risk modelling in the Lower Taff catchment and the River Cynon and Rhondda rivers to support the next phase of work planned to develop a strategic flood risk management masterplan for the whole River Taff catchment. This work is being done in collaboration with all flood risk management authorities in this area, including Rhondda Cynon Taf County Borough Council.

“As climate change looks set to make extreme weather events more frequent in the future, we’ll continue to work constructively with them to keep under review what is practically possible to reduce flood risk in this area.”

Posted on 16/02/2022

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