The 1.5 GW Mona Offshore Wind Project off the coast of North Wales has cleared an early but significant hurdle on its path to construction, with the completion of a complex, four-phase ground investigation survey campaign along its onshore cable corridor. The milestone marks the conclusion of the final survey phase under the project’s Early Contractor Involvement (ECI) works, clearing the way for detailed onshore design to progress.
The surveys were delivered by civil engineering firm Jones Bros Civil Engineering UK, appointed as principal contractor for the ECI phase. Beyond the ground investigation itself, the firm’s scope has included monitoring of the surveys — covering noise and vibration — and ongoing liaison with key stakeholders as preparation for the main onshore works continues. With the surveys now complete, detailed design work is underway, informed by the data gathered along the proposed cable route.
A nationally significant project for North Wales
Located entirely in Welsh waters in the east Irish Sea, Mona has the potential to generate up to 1.5 GW of electricity — enough to power the equivalent of around 1.5 million UK homes each year. The project will consist of up to 96 turbines, with a cable landfall between Llanddulas and Pensarn Beach on the North Wales coast and a proposed grid connection to the existing National Grid substation at Bodelwyddan, Denbighshire. At their closest, the turbines will sit nearly 29 km from the North Wales coast.
The scheme is being developed by JERA Nex bp, which took full ownership of Mona in January 2026 after its joint-venture partner EnBW exited the project; the partners simultaneously decided not to proceed with the neighbouring 1.5 GW Morgan project. Mona was granted its Development Consent Order by the UK Secretary of State in July 2025 and has since entered into a seabed lease with The Crown Estate, moving the project closer to a final investment decision. Onshore, preparation is also advancing elsewhere in the supply chain, with turbine assembly and marshalling earmarked for Belfast Harbour from 2028.
Mona is one of a growing number of renewable energy schemes advancing across Wales, both offshore and on land — a build-out that also includes onshore projects such as Bute Energy’s plans for 192 MW of Welsh wind farms, underscoring the country’s growing role in the UK’s clean energy transition.
Local delivery and the ECI approach
The ECI model brings the contractor in early to feed practical construction knowledge into the design, smoothing the later stages of delivery. Senior Contracts Manager Rhys Roberts is overseeing a team of around 10 as that preparation continues, with the completed surveys providing the detailed ground knowledge needed to inform further design with confidence.
Jones Bros is drawing heavily on local expertise. Headquartered in Ruthin, just over 20 miles from the wind farm’s landfall location, the firm is deploying staff and apprentices from the region and engaging the Welsh supply chain where possible. Established in the 1950s, the company owns one of the largest plant fleets in the UK, employs around 550 people, and works across highways, flood and marine defence, reservoirs, waste management and renewable energy.
“It’s wonderful to have been appointed to work on such a significant renewables project,” said Jones Bros Contracts Director Eryl Roberts. “We have played a vital role on several offshore wind farms in the UK, so to add this development to our impressive portfolio is fantastic. Our highly skilled team will relish being part of this important scheme, especially with it being in North Wales and close to home.”
Richard Haydock, Mona Project Director, said the milestone represents an important step in progressing Mona towards construction and future power generation. “Jones Bros has brought valuable expertise, local insight and a collaborative approach throughout the ECI phase, helping to build a strong foundation for the next stages of the project,” he said.
Project Factsheet: Mona Offshore Wind Project
Location: East Irish Sea, entirely within Welsh waters (closest point ~28.8 km from the North Wales coast)
Developer: JERA Nex bp (full owner since January 2026)
Capacity: Up to 1.5 GW
Turbines: Up to 96
Homes powered: Equivalent of around 1.5 million UK homes a year
Cable landfall: Between Llanddulas and Pensarn Beach, North Wales coast
Grid connection: National Grid substation at Bodelwyddan, Denbighshire
Development consent: Granted by the UK Secretary of State, July 2025
ECI principal contractor: Jones Bros Civil Engineering UK
ECI scope: Four-phase ground investigation surveys (now complete), survey monitoring (noise and vibration), stakeholder liaison; detailed design underway
Component marshalling: Belfast Harbour, from 2028
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