SECTOR SPOTLIGHT Ӏ CRANE MATS
GROUND SUPPORT SYSTEM FOR 90 TONNE CABLE REELS FROM CADMAN CRANES
Galloper Offshore Wind Farm is a 353MW renewable energy project located 30km off the coast of Suffolk, generating enough green electricity to power 440,000 homes. The site’s Operations and Maintenance Facility at Harwich International Port, UK, stores six large cable reels that can be deployed in the event of offshore cable failures. However, these cable reels had been stored on timber mats for several years and the harsh marine environment had degraded the timbers, which needed replacement and a long-term solution installed in their place. UK lifting solutions provider Cadman
Cranes was appointed as Principal Contractor by global energy company RWE to design and install a new support system. The project involved managing several contractors and diverse trades to successfully deliver the contract in less than four weeks. The reels, weighing up to 90 tonnes, required the use of a very large crane positioned as close as possible. Due to the ongoing responsibility for the support system and the £1 million replacement value of each drum, an increase in insurance cover was required.
Project scope and execution As Principal Contractor, Cadman Cranes was subject to the Construction Design Management (CDM) Regulations, overseeing multiple contractors and trades while ensuring the safe and effi cient delivery of key tasks. The scope of work included lifting and storing the reels, removing and disposing
of the degraded timber mats, preparing the ground, and designing and installing a new support system. This new system was required to be fi t-for-purpose and provide structural stability for many years to come. The contract was fi xed-price and demanded rigorous levels of planning and project management to mitigate the higher levels of commercial risk compared to standard ‘daywork’ contracts typically used for lifting requirements. The existing timber supports required a more considered approach to disposal due to their age and wear. The team faced challenges in specifying how the mats could be safely removed to prepare the ground for the new system. The ground below the crane position
was uneven and required a groundworks contract before the main works could begin. Even after reconstruction, the area had such low ground bearing capacity that a massive system of timber mats was needed to support the crane. Ground preparation was essential to ensure the safety and stability of the lifting operations.
Resources and equipment To achieve successful delivery Cadman Cranes implemented a range of specialised resources and equipment including:
The cable reels on their new steel and neoprene supports next to the old, rotted ones
• Groundwork crews using type 1 material, rollers, and excavators to prepare the ground below the new support system.
• Delivery and installation of 52 galvanised steel plates (2m x 1m x 25mm) and 12 neoprene bridge-wearing pads.
• Structural analysis and certifi cation of the proposed support system.
• Design and installation of a crane support mat comprising 72 hardwood crane pads (5m x 1m x 150mm).
• An electric counterbalance forklift, magnetic lifting device, lorry loader, and pick-up vehicles.
• A dedicated team including six crane operatives, a project supervisor, and a project manager.
• Inspection and certifi cation of the client’s bespoke cable reel lifting system.
• A six-day Contract Lift with a 60-tonne mobile crane and a four-day Contract Lift with a 500-tonne mobile crane.
Through planning, engineering, and project management, Cadman says it delivered a robust solution for the Galloper Offshore Wind Farm’s cable storage needs. It says the new support system ensures the stability of the reels for many years, safeguarding this critical infrastructure and supporting the continued operation of one of the UK’s key renewable energy projects.
The crane used to lift the cable reels to
replace their supports was, itself, supported by hardwood mats
The harsh marine environment contributed to the degradation of the timber mats
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