As of 1 April 2012, 37½ of the 111 monopiles that make up Anholt Offshore Wind Farm are installed, and as such one third of the driving is complete.
As expected, there are great challenges associated with the seabed where both very soft areas and very hard areas are present.
The driving of monopile number 38 takes place in an area where the seabed is very hard, and when the pile was 6 metres from the desired depth the work had to be stopped due to a technical defect in the hydraulics. As the pile is standing stably and strong winds for the area was forecasted, it was decided that Svanen should stop the driving and make for port in Grenaa to repair the hydraulics.
When the wind goes down, Svanen will continue with the driving, but experience shows that it can be difficult to get the pile into motion again. Expectations are that it is only hard underground deposits and not rocks which have made the driving difficult; but if it turns out to be impossible to drive the pile further into the seabed, drilling equipment is standing by to drill the last 6 metres into the seabed.
[mappress] Subsea World News Staff , April 05, 2012; Image: DONG Energy