Rapid erosion to the SSSI foreshore needed to be fixed fast
When the re-commissioned sluice on the Sharpness Canal was first activated during the summer floods of 2007 to release excess water into the adjacent Severn Estuary, the force of the discharge eroded the adjacent SSSI foreshore, exposing the original Victorian spillway.
In addition to deteriorating stonework from the original structure, saturation of the cliffing face resulted in bank collapse and lateral erosion of the foreshore during each tidal passage. The rapid rate of bank retreat meant that the works had to be designed and implemented within a very tight time frame.
We were initially appointed as designer to produce a solution to repair and protect the Victorian spillway and surrounding foreshore environment.
A sub-contract was then issued by British Waterways/May Gurney to install the bio-engineering elements of the repair including a Coirnet terraced revetment and brushwood sediment trap.
A rock ramp attenuator was installed at the Apron ‘toe’ to prevent further loss of material from the spillway.
The Severn estuary has the second highest tidal range in the world and this placed tight restrictions on the working day. Our operatives rose to the challenge and worked seven days a week for five weeks to complete the project on schedule.
The completed project is designed to naturally accrete with water-borne sediment and was left unplanted to allow the new sloping terraces to colonise naturally with water-borne local species.