Protecting Southsea against the tide and the unexpected
Project overview
While most sea defence projects battle against mud and rain, the Southsea Coastal Scheme, stretching for 4.5km from Old Portsmouth to Eastney, served us a 1,000kg surprise.
Our team made the national news headlines after unearthing an unexploded bomb. But at OEC, we are used to working under pressure. Once the Explosive Ordnance Disposal team cleared the blast zone, we got right back to work.
Because when you’re delivering the UK’s largest local authority-led coastal defence project, even an unexploded bomb won’t throw us off schedule.
Project overview
Spanning 4.5km from Old Portsmouth to Eastney, the Southsea Coastal Scheme has lowered flood risk for more than 10,000 homes and 700 businesses. We drove the major sea defence and earthworks across Frontages 1, 3, 4 and 5, with additional works on Frontage 6, between 2021 and 2026. Working alongside VolkerStevin and Boskalis Westminster, we brought specialist capability to a complex, multi-year coastal engineering programme to protect local communities while preserving heritage and wildlife along the coastline.
The full works
Armed with our modern screening and crushing fleet, we were trusted to carry out large-scale sea defence and earthworks. The process began by dismantling existing sea walls and associated ground structures, leveraging our specialist machinery to crush and screen materials on-site.
This is how we transformed demolition waste into high-grade recycled aggregates and soils that we then used to build new sea defences and raise land, giving them a second life. As one of the few earthmoving contractors capable of on-site recycling at this scale, we dramatically reduced the project’s carbon footprint.
To complete the sea defences, we used long-reach machinery to install dense Norwegian rock armour and rock revetments, guaranteeing safe placement within strict tidal working windows.
The Southsea Coastal Scheme in numbers:
- Installed 525 linear metres of sheet piles
- Imported and placed over 145,000 tonnes of rock at Southsea Castle
- Placed 75,000 tonnes of rock at Southsea Common
- Constructed a 96m rock groyne to reduce beach erosion
- Delivered 61,000m³ of beach recharge through carefully managed dredging
- Raised promenades and reprofiled land to achieve critical defence levels
For 5 years, we delivered the specialist sea defence services and large-scale earthworks to protect Portsmouth for generations. We are proud to have played our part, delivering complex sea defence works safely, sustainably and with reliable delivery at every stage.
of beach recharge
Reshaping coastal environments requires more than just heavy lifting; it demands a strong commitment to sustainability. We adopted a strict ‘nothing out of the gates’ mindset, ensuring all demolition materials remained within the scheme’s footprint. Beyond recycling every tonne of concrete, we also managed and optimised beach recycling and dredging operations. By creating a seeding beach to naturally maintain shingle levels in high-erosion areas, we significantly increased long-term coastal resilience. Our environmental stewardship even extended to the local wildlife, as we adapted our operations to protect fox habitats along the shoreline.
in cost savings
To us, innovation is measured by the tangible value we provide to our partners. For the Southsea Coastal Scheme, we developed an alternative methodology for constructing the rock revetment from land rather than offshore. This optioneering solution reduced programme risk and generated a remarkable £2.5 million in cost savings. Optioneering solutions like this one is why Tier 1 partners trust us with the UK’s most sensitive coastlines.
for outstanding work
All this outstanding work couldn’t go unnoticed. The Southsea Coastal Scheme has set a new industry benchmark, earning:
– The Sir John Armitt Prize (2025 British Construction and Infrastructure Awards)
– Best Infrastructure Project – Large (2025 ICE South-East Awards)
– The Flood & Coast Excellence Award (2024)
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