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The decommission of Lely offshore wind farm: how vibratory pile extraction reduced time and costs

When existing foundations need to be decommissioned, you are looking for the best pile extraction equipment that’s available, whether it is for offshore or onshore projects. But it is also your responsibility to reduce uptime and costs. Have you ever considered applying  vibratory pile extraction instead of using the conventional hydraulic hammer? Looking at one of our recent projects — the decommission of Lely offshore wind farm — the benefits of the first method compared to the second are obvious.

Decommissioning Lely offshore wind farm

This month, Dieseko Group worked together with specialised companies to decommission Lely offshore wind farm in the IJsselmeer, Netherlands. It was decided to decommission the wind farm as it was approaching the end of its operating life and was becoming less profitable. Dieseko Group was the supplier of the PVE 500M vibratory hammer to extract the piles on which the foundation was built.

The Lely project was a special project for Dieseko Group because it was a prestigious project and we were part of decommissioning an offshore wind farm with monopiles. The use of our PVE 500M vibratory hammer to extract the piles made it even more special, because it does not appear on stage that often.

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Four 26m piles weighing 70 to 80 ton each with a diameter of 3,2 m to 3,7 m each were extracted by our giant PVE 500M. Because the pile is set in motion by the vibratory equipment, less force is needed to extract the pile. 

We used the PVE 500M because of the weight and size of the piles and the density of the soil. The heavier and bigger the piles are, the more centrifugal force the vibratory hammer needs to have. Also, soil research pointed out soil conditions were too dense to use a PVE 300M, for example.

Fast extracting times

During the Lely project, extracting times varied from 30 to 45 minutes, which is a significant time improvement compared to a conventional hammer, especially when you consider the weight and size of the pile. The PVE 500M is a unique vibratory hammer and specially developed to drive or extract the heaviest and biggest piles in order to complete driving or extraction projects faster.

Because a vibratory hammer works much faster, it saves on additional hours, efforts and equipment. This has a positive impact on the costs of offshore or onshore projects. 

 The PVE 500M in action during the decommissioning of Lely offshore wind farm

Low noise levels

In this project low noise levels were conducted during the removal of a wind turbine foundation. Underwater noise measurements were carried out with multiple recorders, directly at the source and over various transects up to distances of 750m. Results are currently under analyses and we will inform you soon.

A vibratory hammer — compared to more conventional methods — reduces driving and extraction time, sound polution and costs. Therefore, the vibratory extraction method offers an economic solution.

Do you want to know more about vibratory hammers and specifically the PVE 500M and its specifications?

Click here for more information about vibratory hammers
Click here for more information about the PVE 500M

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Topics: Piling and vibratory equipment

Posted by Herald Wattenberg on Nov 3, 2016 11:48:55 AM

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