Southsea Coastal Scheme

Purpose

Southsea is a busy tourist and coastal community adjacent to Portsmouth on the south coast. Its existing sea defences, some dating as far back as World War II, are reaching the end of their life, and the local authority recognised the need to adapt the coastline, to reduce flood risk for more than 8,000 properties. The defences failed on two recent occasions and the predicted effects of climate change only heightened this need. They also recognised the opportunity to completely transform the seafront and enable regeneration, enhance the public realm, and improve the setting of the many historic and cultural features that make Southsea so unique.

A VolkerStevin and Boskalis Westminster joint venture (VSBW) secured the contract as construction partner in Summer 2019. We were tasked with helping the client and its designer to overcome the challenges of planning, costing, gaining approval and funding, and finally constructing six frontages of work, across a seven-year programme.

What we are doing

We co-located from the outset of the early contractor involvement period, working as an integrated client, design, and construction team. As coronavirus sent the country into lockdown, we used digital tools to stay in touch and maintain the integrated approach. The frontage 1 design was already well developed, but we provided support in the form of site investigation work and buildability input.

We began constructing Frontage 1 in September 2020 between Long Curtain Moat and Clarence Pier. We are demolishing the existing seawall, installing a replacement sheet piled and clad defence wall, placing rock armour and raising the promenade.

Our management team continue to work alongside the client and designer, to plan and gain approval for each frontage in turn, before beginning construction. The second phase in the programme, Frontage 4 around Southsea Castle, has also recently passed through the necessary approval gateways. Construction has begun and is expected to be complete by spring 2024.

The Frontage 4 design now includes the value-engineered solution we developed, meaning less rock being used for the revetment sea defences, which is far better for the castle and tunnels and will require less piling. It also includes a new promenade design with enhanced features for local people and tourists, featuring wider pedestrian walkways. The Planning Committee agreed that this is a better approach both socially and aesthetically, and that the changes will contribute greatly towards making this area a ‘theatre of the sea’.

Project successes

With environmentally designated special protection areas either side of the coastline, developing and delivering the works in a sustainable manner continues to be a key consideration.

We’ve provided a temporary habitat for internationally protected Brent geese. They normally migrate to the field where our compound is sited. After consultation with Natural England and the Solent Waders and the Brent Goose Society, we closed off an adjacent area and created a temporary refuge. We used fake plastic geese and audio devices to encourage them to use the area.

We are committed to zero waste across all six frontages. We’ve set up a materials processing site to crush, grade and store material for use on future frontages e.g., raising the promenade and road on frontage 3. The processing site will save the project £4m in waste disposal costs and nearly 4,000t of carbon and 25,000 wagon movements through Portsmouth.

For information on the Southsea Coastal Scheme visit the project web site - Southsea Coastal Scheme.