Essential Website Maintenance – Thursday 9th January 2020

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Llansannan flood alleviation scheme

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The scheme has reduced the risk of flooding to the village by increasing the capacity of the drainage system by 70%, with new culverts, improved river channels and new floodwalls.

The work involved:

  • increasing the size of the culvert crossing the A544 at the north end of the village
  • improving the river channel in Dalar Bach
  • building new floodwalls in Dalar Bach at the carpark through to Llain Hiraethog inlet
  • improving the channel in front of Llain Hiraethog
  • replacing the culvert from the Llain Hiraethog channel down Ffordd Gogor and connecting back into the Afon Bach at Uwch yr Aled
  • diverting BT cables, the Welsh Water foul sewer and water mains
  • creating a seating  area at Llain Hiraethog

Environmental benefits

  • Removing weir structures at three locations to help fish migration
  • Installing baffles along the channel bed to give resting points for migrating fish
  • Installing vegetated retaining wall to improve biodiversity

Social benefits

  • Creating two new communal areas along the A544

Project funding

  • 85% funded by Welsh Government
  • 15% funded by Conwy County Borough Council


  • Design phase completed:  31 May 2021
  • Construction tender phase:  June 2021
  • Work started:  February 2022
  • Scheme completed:  November 2022



The Llansannan flood alleviation scheme won an award from the Institute of Civil Engineers Wales Cymru.

The scheme was nominated by contractors MWT Civil Engineering Ltd and won the category for best project under £5m.

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