Flat Holm Island Jetty Demolition and Reconstruction

Kaymac delivered the demolition and replacement of Flat Holm Island’s deteriorating jetty, overcoming remote access, tidal restrictions and challenging marine logistics to improve access for visitors and island volunteers.

Situated in the Bristol Channel, approximately 6 km from Lavernock Point, Flat Holm is managed by Cardiff Council’s Flat Holm Project Team. The island is a Local Nature Reserve, Site of Special Scientific Interest and Special Protection Area.

The existing jetty on the island’s northern shore had fallen into disrepair, raising safety concerns and restricting access at certain high tides. Previous repair attempts had been hampered by the logistical challenges of working on an isolated island, where plant, materials and personnel could only be transported by sea.

Developing a buildable solution

Kaymac worked alongside the design consultancy to help develop a replacement structure that could be built within the island’s access and tidal constraints. Following a competitive tender, Kaymac was appointed Principal Contractor to demolish the existing concrete and timber jetty and construct a new steel and concrete structure.

The works took place during autumn 2019, requiring careful coordination around weather, sea swell and tidal working windows.

Demolition and reconstruction within tidal working windows

Kaymac demolished the existing concrete and timber jetty within a restricted marine worksite on the island’s northern shore. The demolition required careful coordination of tidal conditions, beach access and the availability of plant transported to the island by landing craft. With the only suitable landing point located to the south, equipment first had to be moved across the island to the worksite.

Low-tide working windows governed access for compact plant and the subsequent construction of the replacement jetty’s reinforced concrete piers. Fresh water was delivered to the island to enable concrete to be batched on site, overcoming the limitations of supplying concrete to a remote offshore location.

The replacement steel structure was designed in manageable sections to suit the restricted access and lifting capacity available. Sections were lowered down the cliffs, assembled and lifted into position using small plant able to reach the beach at low tide. GRP and recycled plastic decking were then installed to complete the new access structure.

Coordinated delivery in a remote location

All site works were carried out by Kaymac’s directly employed workforce, supported by specialist supply chain partners. The site team stayed on the island for fortnightly periods, with Kaymac and client management visits coordinated throughout construction to inspect progress and verify quality.

The completed jetty improved access to Flat Holm and demonstrated Kaymac’s ability to combine marine demolition, civil engineering and complex logistics to deliver infrastructure in a challenging island environment.