Please see below the proposals for the Climate Adaptation Scilly Phase 2 proposals on St Agnes:
Periglis Embankment
What’s the problem?
The crest along Periglis has seen significant erosion since 2013-14. The crest has lowered at the north and centre of the bay, and the dune has retreated at the southern end. All of this creates a risk for overtopping and flood water running into Big Pool. Bulk bags have been positioned in parts of dune which has helped to strengthen the bank and supported the natural increase in sand found on the beach.
What’s the suggested solution?
Taking inspiration from the works that were carried out previously, the proposals suggest using an enhanced core, covered with recovered materials. This would work by excavating part of the existing bank and placing geobags at the core. The bags would be covered by a mix of sand and cobbles, topped up by locally excavated materials where available. The crest height would be increased with site won topsoil and widened to a minimum of 4 m. The bank would be planted with local vegetation to provide additional strength and to blend in with the local habitat.
Periglis Demountable Sea Defences
In order to prevent flooding from water surging up from the slipways at Periglis, it is proposed that a new demountable, or removable, sea defence is installed at the top of the slipway that can be installed at times where there is a high risk of flooding.
The exact layout and design of the defence is yet to be finalised, however, it would likely be similar to other demountable sea defences on St Mary's.