Mamhead slipway to be temporarily closed from September to allow vital coastal protection works to be completed before the onset of winter
Works to replenish the rock revetment in front of Exmouth’s historic listed seawall were given the go ahead at a meeting of East Devon District Council on 25 July 2018.
The repairs to the revetment, which is adjacent to the recently completed Mamhead slipway, are required in response to a continual lowering of the estuary seabed in this location. The rock revetment, which was originally constructed in the 1970s, has become increasingly ineffective over the past ten years. The rock at the western end is moving away from the toe of the seawall, leaving it unprotected and vulnerable.
East Devon had originally planned for the works to be done at the same time as the Environment Agency tidal defence scheme. However, monitoring of the lower sections of the wall during the past winter has shown some movement of its base, so these works have been brought forward to ensure that the historic seawall, which is such an important defence as well as a valued asset for the town, remains in good condition.
Detailed surveys of the seabed and revetment by boats and drones have been used to design the project to replenish the rock and ensure the long term stability of the seawall. The works, which will be carried out by Keir for the council, will involve installation of a line of steel sheet piles around six metres out into the estuary, with rock armour then placed between the new piles, and the existing seawall. Steel sheet piles are sections of sheet materials with interlocking edges that are driven into the ground, and they will retain the new rock placed behind.
East Devon will minimise the impact on slipway users by waiting until September to start the works. It will be necessary to close Mamhead slipway from Monday 3 September while the work is done to protect the public and ensure our contractors can work safely. The works are unable to take place any later in the year, due to restrictions on activities, which may disturb overwintering birds around the Exe Estuary. It is anticipated that the works may take up to two months to complete.
Regular updates will be posted on the Council’s twitter feed @eastddevon and on the East Devon District Council Facebook page.
Councillor Tom Wright, East Devon District Council’s portfolio holder for the environment, said:
We do appreciate how important access to the water is for visitors and local residents and we will endeavour to limit disruption as much as we can. These works to the sea wall are essential to ensure it remains sound long into the future and it will complement the Environment Agency tidal defences, which are planned to start next year. The timing of the works does not fit well with end of summer potential use of the slipway, but we are restricted by the issues surrounding migrating birds and fish.