Questions and Answers - Llanfair Talhaiarn 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 the situation returns to normal.

In the meantime, we have prepared answers to questions raised with us by people in the community. We hope they cover the main issues but other queries can be raised via Flood.Risk.Llanfairtalhaiarn@naturalresourceswales.gov.uk Answers are based on information available to date as investigations continue.

Conwy County Borough Council is also undertaking an independent Flood Investigation.

The flood event due to storm Ciara - February 2020

How much rain was there?

Storm Ciara brought significant rainfall to the area – with the Elwy river reaching record flow levels.

The River Elwy at Pont y Gwyddel reached its highest peak on record - 3.65metres at 11:30 on 9 February 2020. This is 0.17metres higher than it was in the November 2012 flood event.

NRW’s Gwytherin rain gauge (situated 12km south-west of Llanfair Talhaiarn) recorded 77mm of rainfall over a 16-hour period. This is 66 percent of the monthly average.

The Plas Pigot rain gauge (situated 7km south of Llanfair Talhaiarn) recorded 58mm of rainfall over a 16-hour period, or 76 percent of the monthly average.

It has been noted that significant amounts of rainfall fell in specific one-hour periods within the time periods referenced above, 25% of the rain fell in one hour at Gwytherin and 28% in one particular hour at Plas Pigot.

Why didn't people receive an alarm/warning service?

Alarms were issued. The current way of sending alarms uses the Wales Telemetry System. The system sends a direct SMS text message to registered mobile phones. Registered landline numbers receive a recorded text to speech message, generated by BT.

Due to restrictions in the amount of numbers we were able to register, NRW decided to only offer the alarm to the nine Flood Wardens in Llanfair Talhaiarn.

These alarms were set up to provide a threshold for NRW’s operational response; it is not an official warning of possible or expected flooding.

Why wasn't there enough time for Wardens to implement the flood plan?

At approximately 5:30am on Sunday 9 February 2020, an alarm activated a direct warning message to the Flood Wardens to implement the flood plan. However, high intensity rainfall and gale force winds caused an exceptional amount of flood water and debris to cascade down the river that overwhelmed the culvert and trash screen. This unprecedented combination dramatically reduced the notice time that is usually afforded to instigate the flood plan.

Flood Wardens are volunteers and should not be placing themselves or others at risk during a flood.

Should NRW have issued earlier warnings?

The warnings were issued as the current system allows. The current threshold levels have been reviewed on several occasions, following past events to ensure the operational response can be carried out in an efficient and timely way. Earlier warnings would require lowering the trigger thresholds, drastically increasing the rate of false alarms.

Was the debris screen blocked?

No. We believe the flooding was caused by the amount of water which exceeded the capacity of the culvert. The debris screen was clear just before the surge of water came through and overwhelmed the culvert.

Should an NRW machine have been on site in readiness for the screen blocking?

Our wheeled backhoe digger is based at the NRW depot in Rhuddlan so that it can respond to any incident in this catchment. The machine is only required if the screen cannot be cleared manually. Until the surge of water NRW officers were actively monitoring to ensure the screen was clear.

Did the tree catcher screen cause the surge in water?

Our investigations to date indicate that the surge was caused by a sudden and extreme increase in rainfall intensity. The investigation will look at the role of the tree catcher and whether any debris collected there impacted on flows in the Barrog.
See also answer to Question 1.

Why didn’t the NRW flood scheme stop the flooding?

The 2018 works significantly increased the capacity of the culvert (pipe) that runs down Water Street. The narrowest, steepest section of the culvert was removed. Blockage risks and pipe crossings were also removed.

The works to the culvert were the most that could be done to protect a village of this size, given the Government’s funding rules, under which NRW operates.

We estimate that the flows on 9 February significantly exceeded the capacity of the culvert.

Did the NRW scheme make matters worse?

There is no evidence to support this. The scheme has increased the capacity of the culvert, but it was still overwhelmed by flows from this significant rainfall event.

Why didn’t the downstream flap valves work?

The flap valves did work. They open and close independently with fluctuating water levels on the landward and river side. They don’t depend on being operated manually by NRW.
As the Elwy was so high on 9 February, the flap valves couldn’t open.

What is the 75 tonnes of material removed since 10th February and where is it from?

Most of the material came from the channel leading up to the tree catcher and the area some 10 metres upstream of the tree catcher.

Vegetation from the tree catcher made up around two tonnes; gravel and other material from the channel running into the tree catcher and surrounding area made up 70 tonnes and vegetation from the trash screen was three tonnes.

Did the material removed by NRW cause the flooding?

No - We believe the flooding was caused by the water exceeding the culvert's flow capacity. The material was removed to help maintain the river in its channel, upstream of the village.

How was NRW allowed to work in the channel at this time of year?

Usually we cannot work in rivers during this time of year due to legislation that protects fish. However, this work was carried out as an emergency to try and ensure that the river stayed within its banks upstream of the tree catcher screen.

Looking ahead

What has happened since the flooding?

Our teams worked to re-establish the telemetry that provides the early warning alarms.

We worked in partnership with Conwy County Borough Council (CCBC) to investigate the causes of the flooding.
CCBC was responsible for producing the flood investigation report, which has been made available to the public.

What’s the latest in terms of completing the flood risk management scheme?

As you are aware, NRW has improved the top section of the Nant Barrog Water Street culvert and the Nant Barrog Black Lion culvert. This was called the Phase 1 works.

It was anticipated that, in the Summer of 2020, NRW would install a new and improved trash screen behind Capel Soar.
There would also be work to improve the walls under this second phase of the scheme. Our scheme, as currently designed, would provide protection to the level of one percent chance of flooding in any given year, once all works, including Phase 2, are completed.

Phase 2 has now been postponed until the Spring 2022.

In parallel NRW, working with partner organisations, hopes to bring about natural flood risk management in the catchment to manage the peak flows of water.

Why can’t you replace the whole culvert?

We considered replacing the whole culvert, but could not go ahead for technical, environmental and economic reasons. Flood schemes must meet cost/benefit criteria.

The cost of replacing the whole culvert far outweighed the financial benefit. It would also be very difficult to undertake, given the narrowness of Water Street and the proximity of properties.

Would improving the top end of the culvert mean that the bottom end of the culvert wouldn’t be able to cope?

We considered this in our assessment and replaced all manhole covers along the length of the culvert with specially designed covers to allow for increased flows. We also installed non-return valves in gulleys that discharge into the culvert.

Why didn’t you make the culvert bigger at the downstream end – is this not a pinch point?

Our analysis found that it was the upstream section of the culvert that constrained flows through the culvert and reduced its capacity, increasing flood risk.

Replacing the downstream section of the culvert would also have been particularly challenging as it passes very close to and under buildings.

We did increase the size of the Black Lion culvert. This allows more flow through the culvert. It also reduced the amount of wall that had to be built at the downstream end of the culvert.

How would a new trash screen help?

NRW staff have great difficulty in maintaining the current screen because of its limited capacity and location. The new screen would be larger and easier to access. This would allow us to respond better and more efficiently and ensure that risk of blockage would be significantly reduced.

What allowance is there for climate change?

Climate change is a reality and is impacting on us in many ways - drier summers, wetter winters, and more frequent storms.

NRW is already considering what impact this will have on flood alleviation and how, as an organisation, we can help communities respond to these events.

If upstream works were progressed, they would provide further resilience against climate change.

We will continue to liaise with other bodies to investigate plans for natural flood risk management in the upper catchment to alleviate the effects of future climate change.

So, the scheme will not stop all flooding?

Unfortunately, no. We can’t ever stop all flooding. Unfortunately also, in the case of Llanfair Talhaiarn, the scale of protection will always be limited by the capacity of the culvert.

The scheme has increased the capacity of the culvert and will raise the standard of protection.

But if a rainfall event happens, that exceeds the culvert’s capacity, flooding will still occur.

Why can’t volunteering Flood Wardens have more of a responsibility?

Volunteer Flood Wardens define their role as they wish, based on the needs of their community and NRW recommends that they should not put themselves or others at risk.

NRW will arrange to meet volunteer Flood Wardens soon to help review and update the Community Flood Plan, ensuring the actions they wish to perform are suitable and won't compromise their health and safety or place them at risk of legal action.

Why don’t all properties in the village have Property Level Protection (PLP)?

PLP was offered to all properties impacted by the 2012 floods in 2012/13, as part of an initiative to help impacted properties.

Will NRW supply PLP to anyone who needs it?

Property owners are generally responsible for implementing specific flood protection measures to their own properties.
NRW will consider property level resilience measures and the use of PLP if we consider this to be a valid option of reducing flood risk to a community.

Properties were flooded from the River Elwy as well – could an Elwy flood warning service be developed?

This might be possible and requires further study.

Could Natural Flood Management (NFM) - using natural processes to reduce risk of flooding - have stopped the flood?

It is unlikely the NFM measures, such as tree planting or leaky dams, would have been enough to mitigate the volume of water that came down the Barrog on 9 February.

NFM measures are very useful in reducing flows and having an impact on low volume events, but do not have such an impact on very heavy rainfall events.

However, we do plan to work with partners to deliver NFM to the Barrog as it will have some positive impact.

Could water storage upstream be considered?

To cope with the flows of 9 February, a significant amount of water storage would have been required. There are limited areas for storage upstream. We have considered two sites, but the storage volumes were small in comparison with this flood event and therefore we do not anticipate that they would have had a significant impact on the flows.

There are also issues in relation to the management and maintenance of any storage sites.

Would Phase 2 works have stopped the flood?

Phase 2 works, as currently designed, would have improved the situation as the proposed walls would be higher than existing so this would have kept some water in the channel initially. However, the flows were such that we believe that these walls are likely to have been overwhelmed also, given that there is limited capacity in the culvert. We believe that the scale of the event resulted in flows that were of a greater volume than the capacity of the culvert.

Why is Phase 2 still under consideration?

The new screen, proposed under Phase 2, will be safer and more sustainable to manage. It would therefore have a reduced risk of blockage. It is also wider and would also therefore be less likely block than the current screen.

There will also be an area for machinery to operate away from the public highway, making the maintenance operation safer.

The screen is too steep – wouldn’t a flatter screen allow water through and stop debris collecting?

The existing screen has been designed in line with guidance as far as is possible, given the constraints of the site. It is the best design for the location.

The area where the screen is positioned is very narrow, which limits its width. Guidance states that a wider screen is required, which will be easier to manage but will also be able to accommodate some debris build-up.

For screens that are hand cleared, there is a maximum length to allow clearance with a rake. As such, a flatter longer screen is not acceptable as it would not be possible to pull back the rake across the whole face of the screen.

The screen has been located approximately three metres from the culvert inlet, which does allow water to spill over the face and go back into the channel before entering the culvert. However, this is not possible when the capacity of the culvert is exceeded.

Why is there a need for a screen at all?

Construction Industry Research and Information Association (CIRIA) guidance for the culvert was followed during design, which advised that a screen was required.

We also assess the site in terms of public safety and assess the risk associated with the culvert inlet by undertaking a Public Safety Risk Assessment.

However, CIRIA guidance has been updated recently, so we are reviewing to confirm our position.

As part of the Phase 2 works, as currently designed, the screen would be relocated upstream to the rear of the Chapel. Fencing would be installed between the new screen and the culvert inlet. There are currently no plans for a second screen at the inlet.

Why can’t the community manage the screen instead of NRW?

NRW built the current screen and is legally responsible for its maintenance. As employers, NRW owes a duty of care to its maintenance staff and employees.

Therefore, staff are trained, competent and provided with appropriate Personal Protective Equipment (PPE) to manage the risks associated with the maintenance.

NRW also owes a duty of care to members of the public who may be at risk from its assets.

NRW would not have the management control to ensure that community members are trained, competent and using appropriate PPE.

As part of our on-going review following the 9 February event, we will investigate whether there is greater scope for community involvement.

Does the Elwy weir cause a problem – it is damaged, what will happen to it?

A study to determine the way forward for the weir is planned for later this year.

Does gravel build-up at the Elwy bridges cause a problem?

We do not have any evidence to suggest that gravel build-up is a problem.

Will NRW clear gravel from the Elwy bridges….Pont y Llan and Pont Ffordd Llansannan?

Gravel clearance by NRW would only be undertaken after a review of the flood risk impact. If it was found that the gravel was having a significant impact, NRW would consider clearing it.

Any planned gravel removal is a permitted activity under environmental regulations - we would need to review the implications and justify removal before undertaking any work.

The River Elwy flooded School Lane…will there be a scheme?

This will be considered after the review process has been completed. There is an existing flood bank, but this is being investigated to understand its role in the February 9 event.

Who pays for the damage caused by flooding?

The Welsh Government has stated that if your home was flooded during February 2020 you can claim financial help. You may be eligible for an Emergency Assistance Payment grant from Welsh Government.

Turn2us is a national charity providing practical help to people who are struggling financially. Farmers and farm workers may be eligible for an emergencyfund from the Royal Agricultural Benevolent Institution (RABI).

To find out more, call their freephone helpline 0808 281 9490. Conwy County Borough Council can also advise on: Community Flood Recovery Grants and Emergency/alternative accommodation via Conwy Housing Solutions https://www.conwy.gov.uk/en/Resident/Housing/Homelessness/Am-I-homeless.aspx; Phone: 0300 124 0050; Email: housingsolutions@conwy.gov.uk
Opening hours: Face to face service has closed. Any person homeless or threatened with homelessness can now contact us between 9.30a.m and 5.15pm on 0300 123 3079
Conwy CBC can also advise on:

• Council Tax exemptions;
• Waste collections;
• What to do with sandbags after a flood (a contaminated sandbag is one that has been touched by flood water, sewage, oil or fuel). This now needs to be treated as contaminated waste.

If you believe you have a claim, write to Natural Resources Wales on our general enquiries email (enquiries@naturalresourceswales.gov.uk)

Will a better alarm/flood warning service be instigated?

Yes, to an extent. The current method of sharing the alarm to wardens only will now be offered to everyone at risk. This means that those registered can receive the alarm via a choice of service, which includes voice calls to mobiles and/or landlines, SMS text and the option of receiving emails.

This also gives us the ability to re-try unanswered calls up to three times.

NRW staff will confirm when this service is available.

A specific flood warning service for Llanfair Talhaiarn will need further study

Is there going to be a bigger/different scheme following the 9 February flood event and the Minister’s visit?

To date there has been no indication of increased funding or a change in Government rules that would result in a change to the protocols that NRW must follow when justifying and/or developing flood schemes.

We are reviewing our plans and assessing whether the designed Phase 2 works are appropriate given the events of 9 February.

Will there be a catchment-wide project that the community can be involved in?

As part of the on-going review we will consider catchment-wide issues. We can help set-up of a flood partnership group for the catchment and adjoining areas. This would be community-led, allowing local people to come together with statutory bodies and other stakeholders to share concerns/ideas regarding flood risk issues. Part of the scope for the group would be to look at catchment-wide issues and improvements to flood risk management that could be delivered through joint ventures or various funding streams. It could also potentially look at the options for more community involvement in managing flood risk.

When and where will the drop-in session be held?

We intended to hold a drop-in session in the village in March 2020 but this has been postponed due to the coronavirus crisis.
Once we can do so, we will come and discuss next steps.

What next?

We would welcome your feedback and if you have any further question or want more information, please contact us on 03000 65 3000 or email Flood.Risk.Llanfairtalhaiarn@naturalresourceswales.gov.uk