Waste management, radiation protection and lifting support for recovery of North Sea’s Largest Subsea Isolation Valve
Contracted by DeepOcean, we delivered full waste management, radiation protection and lifting support for the recovery of a 30-inch diameter Subsea Isolation Valve (SSIV) from the Miller field. At almost 30m x 20m x 6m and weighing approximately 400 tonnes, it was one of the largest SSIVs in the North Sea and, at the time, the largest structure transferred to Aberdeen South Harbour. Its recovery marked the completion of the bp Don & Miller decommissioning project.
The project scope extended beyond receipt. We provided offshore radiation monitoring as the structure was recovered to deck, managed waste services across two preparatory port calls, coordinated the safe offload of the SSIV to the quayside, and oversaw its subsequent downsizing - while protecting port infrastructure and ensuring full regulatory compliance.
Client
DeepOcean
Scope
Decommissioning, Waste Management, NORM Services, Lifting Assurance
Location
Miller field/Aberdeen South Harbour
Duration
June - August 2025 (3 port calls: Peterhead - South Base, Peterhead - North Breakwater, Aberdeen South Harbour)
At a glance
- Supported DeepOcean in the recovery and onshore management of the North Sea’s largest SSIV (~400 tonnes) from the Miller field as part of the bp Don & Miller decommissioning project, across three UK port calls.
- Delivered integrated waste management, offshore radiation (NORM) assurance, lifting support, and engineered quayside protection, including a bespoke load-spread solution at Aberdeen South Harbour.
- Achieved 99% recycling, zero NORM contamination, and zero port infrastructure damage through safe, fully compliant execution from offshore recovery to final downsizing.
Approach
Working in close partnership with DeepOcean, we embedded a Radiation Protection Supervisor (RPS) onboard the recovery vessel to assess the structure immediately upon arrival to deck. This ensured any Naturally Occurring Radioactive Material (NORM) risks were identified and controlled from the outset.
Ahead of final recovery to Aberdeen South Harbour, we supported two earlier port calls at South Base and the North Breakwater in Peterhead, managing the removal of materials and subsea components too large for road transport. These required controlled downsizing before onward movement.
The scale and weight of the SSIV introduced a further challenge. The Port of Aberdeen required protective measures to prevent potential quayside damage. When the appointed downsizing contractor confirmed they could not provide suitable protection, our environmental and lifting assurance teams collaborated to engineer a practical solution. Heavy-duty concrete blocks were sourced and a detailed placement configuration was designed by our lifting specialists to distribute the load evenly, safeguard the quay surface and stabilise the structure during cutting operations.
Impact
The recovery and handling of one of the North Sea’s largest SSIVs was completed safely, efficiently and without environmental incident.
- 416.59 tonnes handled
- 406.73 tonnes recycled (99%)
- 9.86 tonnes to landfill (marine growth only)
- Zero NORM contamination identified
- Zero damage to port infrastructure
The engineered load-spread solution protected Aberdeen South Harbour while keeping the structure secure for dismantling. Early radiation verification eliminated contamination risk, and careful contractor selection ensured the structure was downsized efficiently with maximum material recovery.
Crucially, the project demonstrated the strength of our integrated approach, with environmental, NORM, and lifting assurance teams coming together as one coordinated team to deliver a safe, controlled, and fully compliant outcome.
Testimonial
“ASCO worked closely with DeepOcean to successfully manage and dispose of all subsea waste from the Don and Miller fields, achieving an impressive recycling rate and setting a strong benchmark for environmental performance. The project was delivered through excellent collaboration, on schedule, and with every operation completed safely — demonstrating a shared commitment to efficiency, sustainability, and operational excellence.”
- Matthew Coull, Project Technical Manager, DeepOcean