100-year-old structure has no foundations
A barrier of vertical steel sheet piles costing more than a million pounds could be the solution to save a section of Exmouth’s sea wall.
Cracks in the wall, which is believed to be around 100 years old, appeared in August in front of the Sideshore development.
A storm at the end of October significantly dropped beach levels and caused the wall to “crack and slump,” putting it “at serious risk of collapse.”
Concrete blocks were then put at its base ahead of Storm Ciaran, which helped keep it intact.
The wall has failed because it has no foundations at this location and has been undermined, according to a report to East Devon District Council (EDDC)’s cabinet, which estimates the repair cost at £1.1 million.
When waves wash out sand from underneath, the structure cracks. A further storm may remove the stone, which would eventually lead to all of the sea wall “unzipping” and land behind being lost to the sea.
To fix the problem, a vertical steel sheet piled wall in front of the current wall has been suggested. This could be in place indefinitely or at least until next autumn.
The sloping seaward revetments would be removed, or alternatively repaired or replaced for aesthetic purposes.
Other options such as beach recharges and rock defences were considered, but thrown out because of high costs.
Currently only 90 metres of the 255-metre section between Coastwatch House and Sideshore has failed.
But the remaining 165 metres of wall is “of the same construction and at risk of failure”, the report warns, and would be more expensive to repair later.
The Environment Agency could help cover between £250,000 and £400,000 of the cost, but this is not guaranteed.
Works are “unlikely to start until January and there will probably be further costs as temporary repairs are made until then. But there is a chance they could start next month. Installing the piles will take eight and a half weeks.
“The main risk is that the wall falls completely before we start with the end solution”, the report warns.
East Devon District Council’s cabinet will decide what to do when it meets next Wednesday.