- Project Hornsea Offshore Windfarm Two
- Principal Contractor VolkerInfra
- Project Lead Cameron Swan, Technical Sales
- Key Benefit Bespoke structural equipment to suit the 25m open excavation
Introduction
Located 89km off the Yorkshire coast, Hornsea Two will support Hornsea One and provide power to an additional 1.3 million homes spanning an incredible 462km² making it the world’s largest offshore wind farm once complete in 2022, 6 years after the project got the go-ahead.
Employing the use of the 165 Siemens Gamesa 8MW SG 8.0-167 DD turbines, the project will deliver almost 20% more power than the site at Hornsea One.
VolkerInfra were awarded the work by Ørsted Wind Power to complete the onshore cabling route and associated infrastructure from the windfarm’s landfall point at Horseshoe point to North Killingholme.
MGF were invited to meet with VolkerInfra early in 2019 but it wasn’t until later in the year that there was a progression with the designs for the three parallel excavations that would house the transition joints, directing the energy from the turbines to the substation 39km inland.
Despite the challenges we faced it was a great experience to work with a structural steel frame with a site team that we’ve developed strong relationships with. The early engagement of MGF by VolkerInfra was a real benefit to the scheme and meant that we were able to design, manufacture and deliver equipment that suited the progression of the works.
Cameron Swan, Technical Sales
The Solution
Following submission of the conceptual design and multiple revisions in the brief from site paired with the
6-month+ time frame the customer requested the excavation be open for, it became apparent that hydraulic, modular components would not be suitable. With the request to increase the length of the excavation but without the use of knee braces or bracing struts, MGF’s design team explored the use of a structural frame to support the requirements.
To allow the excavation works to progress to formation level, we supplied 254UC Walers with three 200 Series cross struts to support the piled wall of 8.5m and 9.5m GU13 sheet piles to allow the water pumps to fully drain inside of the excavations whilst the bespoke structural frames were being manufactured.
Once the piling works were complete, an extensive survey was required to detail the exact measurements required for the structural frame. The collaboration across multiple departments and businesses throughout were critical to the success of the steel frame. To suit the length of the excavation, MGF supplied the structural frame in manageable, interconnecting bolted sections to provide a practical installation for the site team.
Once VolkerInfra’s site team were able to access the drained excavations, the hydraulic frames were lowered before being removed once the structural frame was installed – an impressive 762 x 267 x 97 UB Waler designed and manufactured wholly in house: combining the knowledge and expertise of our Engineering Team with our Manufacturing Team at our dedicated facility in Wigan.
Whilst the principle of using structural steel to support excavations isn’t anything new, it is something that MGF doesn’t often get asked for – so to showcase our capabilities on such a prestigious site with huge success was a great experience for all involved! Working closely with MGF’s CAD Manager from an early stage of this project not only allowed us to use clash detection software for the excavations themselves, but to produce detailed 3D installation sequences through the use of Autodesk Revit for both the sheet piles and MGF’s modular equipment as well as the bespoke steel frame too.
MGF Design Team
The Verdict
The structural steel frames gave VolkerInfra the capabilities to keep a fully open excavation for over 6 months, with the engineered knowledge that the site was completely safe.
Our latest manufacturing progression up to Execution Class 3 will continue to meet bespoke, unusual and complex customer requirements.
The VolkerInfra and MGF teams worked excellently together in testing conditions to provide a robust, bespoke solution which can be used on all future projects. Constant assistance throughout the design, manufacture and installation phases resulted in a faultless execution of the project.
Nick Winfield, Site Manager, VolkerInfra
