The scheme comprised of a 720m long, 1.8m diameter overflow culvert running from the Afon Bach to the Afon Conwy partly constructed in open cut and part in tunnel, an inlet structure, with trash screen across the Afon Bach, adjacent to the Cae'r Felin playground and a smaller (600mm diameter) inlet from the watercourse adjacent to the Perthi estate.



At the Conwy outfall, a flap value covers the opening in the river wall and prevents water flowing back up the culvert should water levels in the Afon Conwy be higher than those in the storm culvert, forcing the outlet flap valve closed.  Due to the size of the pipe there is significant storage space within the pipe for flood water.  The culvert is a sealed system, so as the water fills the culvert, it will be kept within the system and not allowed to escape.  As the inlet to the culvert is around 8m above the outlet, once a sufficient volume of water has been stored the weight of the water will force the flap valve open and the culvert will discharge into the Afon Conwy.

The scheme was worth £3.2m.  85% grant funding was obtained from the Welsh Assembly Governments Protection Fund with the remaining 15% funded from Conwy County Borough Council's Capital Programme.

















Welsh Environment Minister, Jane Davidson, visiting the Afon Bach Flood Defence Scheme.