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Llansannan Flood Alleviation Scheme

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About the scheme

What will the scheme do?

  • Reduce the risk of flooding to the village
  • Increase the capacity of the system by over 70%.

This will be achieved by:

  • Increasing the size of existing culverts
  • Widening river channels
  • Removing obstacles in channels

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

Phase 1 - Construction: September to October 2021

  • A544 culvert upgrade
  • Dalar Bach river restoration
  • Llain Hiraethog channel improvement work:

    • New floodwall along the left bank within the carpark 
    • New vehicle bridge
    • Upgrades to the existing left bank channel wall
    • New pedestrian bridge and communal area
    • New communal area at Ffordd Gogor culvert inlet

Phase 2 - Utility diversions: Winter 2021/2022

Phase 3 – Construction: starting Spring 2022

  • Ffordd Gogor Culvert replacement including a new inlet at Llain Hiraethog and outlet at the Uwch Yr Aled Channel
  • Highway drainage system improvements
  • Welsh Water foul sewer diversion

Traffic management during construction:

  • A544 single lane road closure during autumn 2021
  • Ffordd Gogor full road closure during summer 2022

Proposed scheme (PDF)

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