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Offshore foundation works: as silent as we can be

The facts. Underwater sound propagates over large distances under water. The exact distance depends on the source level, frequency spectrum of the source and the environmental conditions. Since underwater sound can lead to adverse effects on the ecosystem, mitigation measures are often applied to reduce the impact zone around construction areas.

Until now, the most common way to install or remove offshore wind farms is by the use of pile driving. This technique generates impulsive noise underwater at very high levels. Noise pollution has negative effects on sea life. Since vibratory technique generate continuous noise instead of impulsive noise, it is expected that produced sound levels are considerably lower compared to pile driving techniques.

Independent measurement
At Dieseko Group, we care about the environment. That is why we constantly work on solutions that have as less impact on the environment as possible. To proof that our vibratory technique causes less underwater sound than legally allowed, we decided to carry out an independent measurement. 

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During the dismantling of offshore wind farm Lely, we invited an independent expert to carry out underwater measurements. The objective of this measurement was to assess if the sound levels produced by our largest vibratory hammer, the PVE 500M, are below pre-defined threshold levels at a distance of 750m from the source.

German threshold
The threshold is based on German criteria. As wind energy was pointed to become one of the most important energy sources in the country, the German government decided to focus more on this energy source. Offshore wind farms were developed in a fast pace and so the need for regulations arose.

According to these German criteria a maximum Sound Exposure Level (SEL) of 160 dB re 1μPa²s and a maximum peak Sound Pressure Level 190 dB re 1μPa as (SPLpeak-peak) both at 750m from the source are allowed.

The results
It appeared that the measured sound levels of both the SEL and the SPL are substantially lower than the threshold levels. Based on the given circumstances it is expected that more or less similar results can be expected from comparable foundations and vibratory hammer intensities in offshore conditions.

We are proud to claim that the application of our vibratory hammer technique does significantly contribute to underwater noise reductions at offshore piling projects. And we sincerely hope that in the near future vibratory technique will be a serious alternative for other foundation techniques for various offshore projects.

Do you want to have more information about the results of the sound measurement, please contact me or Herald Wattenberg, our offshore expert. 

This blog post is established in cooperation with Herald Wattenberg. 

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Topics: Corporate

Posted by Rob Eijkens on Feb 9, 2017 9:48:08 AM

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