Monopile decommissioning on amalia offshore wind farm

MONOPILE DECOMMISSIONING ON AMALIA OFFSHORE WIND FARM

In 2018, the CAPE VLT-320 Tandem was used to upend and install a 4 meter diameter monopile with a length of 56.6 meter at the Amalia Offshore Wind Farm off the Dutch coast. In October 2021, the CAPE VLT-320 Tandem was used again to decommission the monopile as part of the DOT FOX project.

With the extraction in 2021, it was shown that even after being subjected to the harsh North Sea environment for three years, the CAPE VLT was able to loosen and extract the pile without any trouble. After the extraction the pile was installed again and extracted whilst performing a series of tests to assess soil response and gain further knowledge of the offshore vibro lifting technology, like controlling verticality within the required tolerances.

Application details

Application

Decommissioning

Pile type

Monopiles

Water depth

22-24m

Extraction

19m

PILE DETAILS

Pile type

Monopiles

Pile model

Tapered

Pile length

56.6

Pile weight

300t

Pile wall thickness

40-60mm

Pile diameter

3.26-4m

No. of piles

1

PROJECT DETAILS

Period

October 2021

Sea

North Sea

Country

The Netherlands

Location

Amalia Offshore Wind Farm

Market

Offshore Renewables

System/end usage

Offshore Wind Turbine

Operator or end customer

DOT

Installation contractor

Heerema Marine Contractors

Type of vessel

Semi-Submersible Crane Vessel

Name of vessel and owner

Sleipnir, Heerema Marine Contractors

Main Reasons for solution choice

EXTRACTING, LIFTING, DOWNENDING IN SINGLE OPERATION

IN COMBINATION WITH DP OPERATED VESSEL THE FASTEST WAY OF INSTALLING MONOPILES

CONTROLLED INSTALLATION

SELECTED EQUIPMENT

CAPE VLT-320

Equipment configuration

CAPE VLT-320 Tandem

Eccentric moment

640kgm

Max. line pull

1,000t

vibro
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