2.6 GW reversible hydro plant carved into Norwegian gneiss — a battery the size of a fjord.
What we did
Hextal served as the lead civil engineering contractor, responsible for all structural design, ground engineering, materials procurement and on-site construction management. Our scope encompassed full lifecycle delivery from mobilisation through commissioning, with integrated environmental monitoring and stakeholder coordination throughout.
Every project begins with a problem no one has solved before.
The challenge
Installing 280 gravity-base foundations on the North Sea seabed, 64 km offshore, demanded year-round operations in sea states that regularly exceed 2.5 metres significant wave height. Each 15 MW turbine foundation weighs 8,400 tonnes and must be placed within a 50mm tolerance envelope on a prepared seabed. The programme required coordination with three national grid operators, two cable-laying contractors and the Dutch Ministry of Defence due to proximity to naval exercise zones.
The solution
Hextal designed a modular gravity-base system that could be cast in a purpose-built dry dock in Rotterdam, towed to site on a semi-submersible barge and ballasted down in a single tidal cycle. Seabed preparation used a custom dredging head that achieved the required flatness tolerance without over-excavation. A digital twin of the entire wind farm was maintained in real time, coordinating vessel movements, weather windows and grid connection sequencing across a 48-month installation programme.
Mobilisation
Design
Procurement
Construction
Commissioning
Led by Ir. Pieter van den Berg
The project team comprises 340 engineers, site supervisors and specialist subcontractors drawn from across the Hextal Group. Core disciplines include structural engineering, geotechnics, materials science, environmental management and digital delivery. The team operates from a dedicated site office with full BIM coordination capability.
Programme oversight is provided by the Group Executive Committee through quarterly stage-gate reviews. Health and safety performance is reported weekly to the Chief Operating Officer.
Meet the leadership teamMore from the portfolio.
11.392°E
Brenner Base — North Approach, Tube T-3
22.4 km twin-bore alpine tunnel beneath the Stubai range. Hextal led the TBM consortium and the cross-passage civils. Excavated material reused as aggregate within a 40 km radius — net-positive on embedded carbon vs. EN 16627 baseline.
13.369°E
Berlin Hauptbahnhof — Southern Concourse
14,800 m² extension, glass-and-steel canopy spanning four ICE platforms. Built without interrupting service.
4.487°E
Maasvlakte III — Caisson Dry Dock
A 1.2 km automated container quay built on a man-made polder.