A technique used by the Army to build barricades in Afghanistan was successfully employed at Duck Broad to rebuild an eroded reedbed.
Reinforced steel baskets, filled with rocks and sediment, were joined together to make the perimeter of a one hectare spit of land. This was filled with 10,000 cubic metres of sediment dredged from Heigham Sound and planted with common reed and reedmace. It restores the reedbed to how it would have looked in 1946, based on aerial photography.
The project has helped separate Duck Broad from the main channel and improve water quality within the broad. Wildfowl have been seen making their homes there again.
The dredging of Heigham Sound to create the reedbed has also improved channel depth for navigation.
Anglers were concerned that prymnesium, a naturally occurring algae that lives in the water in the Upper Thurne, might bloom as a result of the dredging work in Heigham Sound. Prymnesium can be harmful to fish.
To alleviate the possibility of a Prymnesium outbreak, we deployed an impermeable silt curtain to stop sediment entering the main water body. We have also been carrying out rigorous water quality sampling which has seen weekly and daily monitoring of conditions within the work area. A robust action plan is in place should water quality deteriorate.