98% recycling rate achieved in complex decommissioning project
A subsea energy services provider required a fully managed solution to receive and process waste recovered from the decommissioning of the Chestnut field. The project involved a variety of materials, including 163 concrete mattresses, over 1,500 metres of product pipe, and several subsea structures. The sheer size and weight of the materials created logistical challenges for handling, downsizing, and road transport.
In addition, some items had the potential for NORM contamination, requiring careful monitoring throughout recovery and transfer operations. The client needed a flexible, end-to-end service that could manage the full lifecycle of materials - from receipt at port to final disposal - without relying on multiple suppliers.
Client
Subsea energy services provider
Scope
Decommissioning, NORM, Environmental Services
Location
Aberdeen South Harbour & Peterhead North Breakwater, UK
Duration
May - November
At a glance
- Delivered an integrated logistics and waste management solution for complex subsea decommissioning materials, ensuring safe handling, segregation and compliant processing from port receipt to final disposal.
- Managed multi-site operations across Aberdeen and Peterhead ports, coordinating offloading, laydown and transport while maintaining full regulatory compliance and NORM monitoring.
- Achieved high recycling performance across 1,401.92 tonnes of material, including safe treatment of concrete mattresses, pipelines and subsea structures with efficient recovery and disposal routes.
Approach
We developed a comprehensive logistics and waste management plan detailing how materials would be received, stored, segregated, and transported to disposal sites. Radiation Protection Supervisors were onboard to monitor for NORM contamination, ensuring compliance and safety at every stage. Coordination with Port of Aberdeen and Peterhead Port Authority ensured suitable offload conditions and solidified plans for onward transportation.
Offloading was managed using our cranes and specialist squads, placing items in lay-down areas ready for transfer to disposal sites. Subsea baskets containing mixed waste were carefully inspected and cleaned as necessary to meet road transport requirements before being returned to the supplier.
Impact
Across four port calls, ASCO received a total of 1,401.92 tonnes of material, achieving a 98% recycling rate:
- 1,381.43 tonnes sent for recycling
- 14.35 tonnes sent to landfill
- 6.14 tonnes sent to energy recovery
Concrete mattresses and subsea structures were handled safely at multiple locations, with offloading, transport, and disposal coordinated seamlessly. Subsea baskets were cleaned to road-ready standards, exceeding the original project scope. The project demonstrated our ability to respond to changing client requirements, manage diverse and challenging materials, and provide a fully integrated solution spanning transport, operations, waste management, and NORM monitoring.