Wikinger wind farm

For five months, working in continuous shifts with dive crews, we removed segregated grout from wind turbine foundations at a depth of 40 meters in the Baltic Sea.

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Duration

5 months

Segment

Offshore

Energy sector

Solutions

Grout removal

The challenge

SEGREGATED GROUT AT GREAT DEPTH, IN OPEN SEA

Commissioned by Boskalis, ADS was tasked with removing grout from the transition pieces of wind turbine foundations at the Wikinger wind farm in the Baltic Sea, off the coast of Sweden. Due to the influence of seawater during installation, the grout had segregated and failed to achieve the required compressive strength of 170 N/mm². Replacing the entire grout layer was the only option, at a depth of 40 meters, working in continuous shifts under conditions where weather, swell, and limited accessibility presented a new challenge every day.

The process

FIVE MONTHS OF CONTINUOUS SHIFTS WITH DIVE CREWS

ADS deployed two coupled hydrodemolition units, specifically developed for this project into a demolition method operating at 1,600 bar and 330 liters per minute. The work was carried out in continuous shifts, in close cooperation with dive crews who positioned the equipment underwater and monitored progress. The team worked from the Boskalis vessel, with the full equipment set up and operational on board daily for five months, until all foundations had been treated.

The solution

GROUT SELECTIVELY REMOVED, FOUNDATION COMPLETELY INTACT

By removing the grout using hydrodemolition instead of mechanical methods, the steel profiles and anchors of the foundations remained completely intact. This made it possible to re-grout the transition pieces to the required compressive strength without damaging the existing structure. This project demonstrates that ADS can deploy customized hydrodemolition solutions even far out at sea, at great depths, and under the most demanding conditions.