Emergency repair works have begun to repair a 40m section of failed sea wall. The wall is located on Memorial Beach, Southsea, Portsmouth UK (50.782565, -1.096222). The wall has failed as a result of severe beach draw down, caused by a series of storms with long period swells. Although wave height was not large, the high frequency of long duration small storms resulted in a significant reduction in beach level.
The draw down in beach material has exposed and undermined the toe of the sea wall. As such the promenade and remaining wall were left un-supported and collapsed. Over 25m of the wall and promenade have collapsed as a result.
The promanade will be closed to allow repairs to be undertaken, the footpath will be diverted through the suspended parking bays to ensure foot traffic can continue to operate as normal.
The repair works were to bring in a volume of beach material to provide a safe working platform and protect the collapsed section from further cutback. The broken concrete was removed and a 35m length of sheet piles were installed along the damaged length of promenade. Rock armour was installed along the toe of the sheet pile wall to prevent scour and aid beach stabilisation, then covered over with beach material. Finally the promenade has been reinstated back to original condition.
Works have continued to progress well down on site. The sheet piles have now been driven to required depth and the tops cut down to the correct level. Structural fill has been placed and compacted behind the sheet pile wall, ready for concreting and resurfacing.
200 tonnes of rock armour have been placed in front of the sheet piles and covered over with beach material. The rock is designed to reduce wave energy, protecting the area in front of the piles and will stabilise the existing beach. The rock is Purbeck stone from Dorset and each one has minimum weight of 1 tonne!
We have also begun bringing in material to help replenish the beach, and nearly 150 tonnes has been placed so far. The shingle is of a similar size to what is currently on the beach and is locally sourced from the Solent.
Next week we are planning to continue to bring and place beach material, with 800 tonnes ordered in total. The concrete slab will be poured on by the end of this week, and the capping beam the following week.
For more updates about the Southsea Coastal Scheme, visit the website at southseacoastalscheme.org.uk