## Llanfair Th Factsheet March 2016

Natural Resources Wales wants to work with partner organisations and the community to design and deliver flood risk management improvements for Llanfair Talhaiarn, which will reduce the risk of flooding from the Nant Barrog river. What has happened to date? 

We have completed an appraisal of the flood risk to Llanfair Talhaiarn from the Nant Barrog and have now come up with our preferred option for mitigating the flood risk to the village. We want to hear comments from residents and stakeholders. 

What works are planned? 

Our preferred option is to improve the top section of the culvert, improve the trash screen arrangements and undertake some localised wall raising work. We also hope to create some upstream storage areas to manage the peak flows of water. Why don't you replace the whole culvert? 

We considered replacing the whole culvert, but we can't go ahead with this for technical, environmental and economic reasons. The cost of replacing the whole culvert would far outweigh the financial benefits that could be generated. 

Would improving the top end of the culvert mean that the bottom end of the culvert wouldn't be able to cope?  
We have considered this in our assessment, and will be replacing all manhole covers along the length of the culvert with specially designed covers to allow for increased flows. 

Why aren't you making the culvert bigger at the downstream end - is this not a pinch point?  
Our analysis found that it is the upstream section of the culvert that causes flooding in Llanfair Talhaiarn.  Replacing the downstream section of the culvert would also be particularly challenging as it passes very close to buildings. 

What allowance is there for climate change?  
Our design will provide protection for a present day one in 100 year flood incident - in other words a flood incident that has a one per cent risk of happening in any given year. We cannot provide a higher standard to allow for future climate change at this time.  However, we will continue to investigate plans for Natural Flood Risk Management in the upper catchment to alleviate the effects of future climate change.   
 
 
If the upstream works are not completed, what will happen?   
If we are unable to deliver the upstream works, our proposed scheme would provide a one in 75 years standard of flood protection. 

If you are sealing the culvert is there a risk of water coming out elsewhere and causing flooding?  
We have considered this in our design and will be raising a short section of floodwall downstream of the culvert to ensure we don't cause flooding elsewhere. 

Will your proposal stop all flooding? 

No. We can't ever stop all flooding. The scale of protection will always be limited by the capacity of the culvert. The scheme will increase the capacity of the culvert and raise the standard of protection. But if a rainfall event happens, that exceeds the culvert design, flooding will still occur. 

Is the design finished? 

No, at this stage we have only competed the outline design. As part of the detailed design phase we will be consulting with landowners and stakeholders that are impacted by the proposed works to make sure that their concerns are addressed. We will also be working with Conwy County Borough Council to ensure they are happy with the works. 

When will the design be done? 

We are currently in the appraisal phase on the project. A business case is being prepared that will hopefully be submitted for approval by NRW in May 2016. Subject to this approval and available funding, we hope to progress detailed design later in 2016. 

When will the construction work be done? 

Funding for the construction phase of the work has not yet been approved. The works will have to take place in the summer, when hopefully river levels will be low, so that we can temporarily manage the flow in the culvert during the work. If all approvals are received and funding is available, we may be able to complete the work in the summer of 2017. 

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