Llanfair Talhaiarn flood risk management
Read the latest updates here
An update following Storm Ciara 2020
Our thoughts are with everyone affected by the recent devastating flooding that hit Llanfair Talhaiarn and other areas across Wales in February 2020.
We appreciate that this latest flooding is a matter of anxiety and deep disappointment to everyone living in the village.
Storm Ciara brought significant rainfall to the area – with the Elwy river reaching record flow levels.
Work is already underway, with Conwy County Borough Council, to understand the causes of the flooding and how we can work with the community to reduce flood risk in the future.
Initial findings are that the unprecedented flows in the Nant Barrog overwhelmed the culvert. There was also some overtopping of embankments by the River Elwy. We estimate the flows in the Barrog on 9th February to be greater than those experienced in 2012.
A Flood Investigation Report will be produced and published.
We intended to hold a drop-in session in Llanfair TH in March 2020 to gather information and discuss next steps with local people. However, the coronavirus pandemic means this has been postponed until a time when it is safe for us to meet face to face with people in the community.
In the meantime, we have collated answers to some frequently asked questions – which you can find here
We would welcome your thoughts on the flooding that occurred and we are happy to address any questions or concerns that you may have.
You can also discuss matters with Cllr Ifor Lloyd with whom we work very closely. Email: firstname.lastname@example.org
We will keep in close communication with the Community Council and provide regular updates.
As you may be aware further works to assist in the management of flooding was planned for the village for later this year. Following the flood event we have put our plans temporarily on hold as we review the issues. We would still hope to progress works this Summer following completion of this review if we feel that the planned works still offer the most effective way forward. However as you will understand any works in the coming months are also likely to be impacted by the COVID19 outbreak and the uncertainty that is associated with it.
Please forward your comments or any questions via email to Flood.Risk.Llanfairtalhaiarn@naturalresourceswales.gov.uk
Update on actions following the February 2020 flooding
Due to the coronavirus crisis, we have been unable to hold a drop-in session in Llanfair Talhaiarn to discuss flooding issues. We will do so, as soon as restrictions are lifted and it is safe to do so.
In the meantime, we held a skype meeting with the community council on Monday evening,15 June 2020, to discuss our proposed flood actions programme for the months and years ahead.
Our update for the community council is captured here, in summary.
We hope it helps keep you informed in these challenging times, before we can return to discuss matters with you face-to-face once again.
Please forward your comments or any questions via email to: Flood.Risk.Llanfairtalhaiarn@naturalresourceswales.gov.uk
We will continue to keep in close communication with the Community Council and provide regular updates.
You will also find answers to lots of questions on our website www.naturalresources.wales/Llanfairtalhaiarn
Llanfair Talhaiarn Post Floods Action Plan
Short-term actions (what we have done since February and will complete by October 2020)
- After the flooding, we removed 70 tonnes of river gravel that had been carried down the river and deposited in the area leading up to the tree catcher. Five tonnes of vegetation were also removed from the tree catcher and Capel Soar debris screen.
- We have replaced the telemetry system - essential for monitoring the river level and providing early warning alarms - at Nant Barrog. The existing telemetry was demolished during the flood event.
- Answers to your questions were posted out to all properties at risk following the floods – also found on the NRW website for the wider community – naturalresourceswales.gov.uk/LlanfairTalhaiarn
- We have reviewed the way we disseminate the early warning alarms to the community and can disseminate more widely.
- We are setting up messages, to be known as Early Warning Service Alarm 1 and Alarm 2. They will be issued via the Flood Warning System (FWS) and will be up and running by early August.
- A few weeks before the new Early Warning Service starts, we will send letters to all 53 properties at risk, providing information about how to register for the service.
- We are also improving the telemetry system, so that duty officers can better monitor river levels at Nant Barrog, also by early August.
- We are looking into the possibility of adding Nant Barrog river level data to NRW’s River Levels Online, found on the NRW website.
- We will be working with the volunteer Flood Warden Group to update Llanfair Talhaiarn’s Community Flood Plan, including information about the Early Warning Service.
- We are undertaking a CCTV survey of the culvert, to give us an understanding of its condition after Storm Ciara.
- We will be clearing the gravel trap, upstream of Capel Soar later this summer before investigating its effectiveness.
- We are carrying out a structural inspection of the Nant Barrog Weir and a review of the Elwy flood embankment.
- We are reviewing the requirements for the debris screen, to possibly make adjustments to reduce the risk of debris screen blockage, before October 2020.
- We are investigating the feasibility of providing suitable Property Level Protection (PLP) to home owners at risk of flooding.
- We are investigating the potential for Natural Flood Management works, if funding is available. This means using natural solutions, such as planting trees or leaky dams, to help reduce the flow of the water upstream
- We are providing input to the Storm Ciara Independent Flood Investigation, led by Conwy County Borough Council, which will report back later this summer.
- Phase two of the flood risk management scheme has been put on hold until we have the findings of the independent flood investigation report, so that we consider its recommendations before moving ahead.
Medium Term Actions (Autumn 2020 – Winter 2021)
- When Coronavirus social distancing restrictions have been lifted, we will organise a community drop-in session in the village, in partnership with Conwy County Borough Council.
- We will work with community representatives (including local councillors, volunteer flood warden group, other interested parties) and professional partners to develop a Flood Partnership Group.
- We will explore options for providing a Flood Warning Service for Llanfair Talhaiarn.
- We will review the Elwy Weir’s impact on flood risk.
- We will make improvements to the camera, which contributes to monitoring the river, upstream of the culvert.
- We will review the performance of the coarse debris screen (knows as the tree catcher) and move ahead with improvements if necessary.
- We will review the flood risk management scheme works - in light of the flood investigation report - and confirm what will be delivered in the Spring/Summer 2021.
- We will continue to manage the catchment upstream and work to deliver natural solutions to help alleviate the village’s flood risk.
Long Term actions (January 2022 – December 2025)
- We will continue to monitor and review the long-term performance of the gravel trap, upstream of Capel Soar.
- There will be on-going work to manage the river catchment upstream, and further options explored for natural flood risk management.
You can also discuss matters with Conwy County Borough Councillor Ifor Lloyd (email@example.com)
Background (where we were before Storm Ciara March 2020)
November 2012 saw flooding to the village of Llanfair Talhaiarn (TH) when the Nant Barrog, swollen by extreme rainfall, overwhelmed the Water Street culvert and flooded 19 homes and businesses.
This followed previous flooding in the village, during April 2012 along with numerous other reported incidents in the past 50 years.
Based on modelling, the November 2012 flood was estimated to have had a two percent chance of happening in any given year.
But, as evidenced by the frequency of flooding incidents in the village, in 2012 Llanfair TH was actually thought be at risk from floods on the Nant Barrog with a four percent chance of happening in any given year, due to overwhelming the Water Street culvert.
This risk of flooding is exacerbated by blockage of the trash screen, across the inlet of the Water Street culvert.
The River Elwy flows along the northern edge of the village. The November 2012 flood on the Elwy was reported as being between a one percent and two percent chance of happening in any given year. Existing flood defences protected Llanfair TH from further flooding from the Elwy during November 2012 - the village was solely affected by flows on the Nant Barrog.
Developing a flood risk management scheme
Since the 2012 flood events, we've been undertaking work in the village to improve resilience to flood risk and reduce the risk.
In 2016, we completed an appraisal of the flood risk, to assess the flood risk and came up with proposals to further reduce this risk.
The flood risk management scheme improves the capacity of the Water Street culvert.
Once completed, it will also improve the performance of the trash screen and we will investigate options to make improvements upstream to protect the village against flooding.
The flood scheme currently proposed will provide the village with protection of one percent chance of flooding from the Nant Barrog happening in any given year, once completed. It will also mean that the debris screen will be easier to manage and will not be as sensitive to blockage as the existing screen.
The construction of the flood risk management scheme is phased, with Phase 1 completed in January 2019, increasing the capacity of the culvert to being able to carry flows equivalent to 1.33 percent chance of flooding happening in any given year.
Phase 2 is planned for later this year, 2020 subject to obtaining planning and other permissions and review following the 9th Feb.2020 floods.
Phase 1 works involved improving a key upstream section of the Nant Barrog Water Street Culvert and The Black Lion Nant Barrog Culvert section. We have removed the old culvert sections at these locations and replaced them with larger sections. We also did work to seal the culvert throughout its length.
NRW is grateful to the residents for their support and understanding throughout Phase 1.
This work improved the capacity of the culvert and it is now able to accommodate increased flows, giving the village a 1.33 percent flood risk in any given year.
There is still a risk posed by the existing debris screen. NRW officers attend the site during high flow/heavy rainfall events but the current screen is difficult to maintain and keep clear of debris.
Phase 2 works, as currently designed (to be reviewed), will involve improving the existing debris screen arrangement at Capel Soar. A new, additional, wider debris screen is proposed. Walls will also be constructed to keep more water within the channel to drive it through the culvert to optimise its capacity. We have considered all options to ensure that we come up with the most suitable and sustainable solution. However we will review plans after the February 2020 floods.
The flood scheme will be supported by work upstream to manage the peak flow of water through the village by using natural flood management methods, by working with partner organisations.
NRW is hoping to work with Coed Cymru to look at natural solutions including planting hedges and creating natural barriers to the flow of the water upstream.
We will hold a further consultation event in the village before the next stage of works.