DAGA 2020 Hannover
Conclusion from pile driving noise and
abatement system application during German
OWF constructions
From 2013 onwards pile installations in the German EEZ
took place at two to five OWF*‘s per year on average. Due to
Ihe increase in megawatt capacity of wind turbines, which
approximately doubled within this period, the number of
wind turbines per windfarm, and hereby the number of pile
driving events decreased. However, pile diameter have
reached values of up to 8 meters at the pile basis. Despite
increasing pile diameters and water depths of up to 40
meters, a compliance with the mandatory threshold could
has been achieved reliably since 2014.
The effectiveness of technical noise abatement systems
applied is evaluated according to standards given by [4] and
[5]. Efforts by the industry have significantly advanced
technical noise mitigation systems in the past years. In the
last eight years, three basic noise abatement systems have
been applied successfully in German waters under real
offshore conditions:
Big Bubble Curtain systems (BBC), far field noise
abatement at distances >= 60 m around the piling
location,
isolating casing systems from IHC noise mitigation
screen (NMS) at near field with multiple functions
fsuch as holding and positioning the piles and
allowing for controlling verticality) and
Hydro Sound Damper (HSD) at near field around
the pile, mostly operated from the pile gripper
system.
Data from the monitoring of these three noise abatement
systems in the German EEZ of the North and Baltic Sea
available in MarinEARS have been analyzed in the
framework of a R&D project funded by the Federal Ministry
of the Environment and Nuclear Safety (BMU). The results
including current knowledge and field experiences are
published in the final report of the project [61
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” mitigated (HSD+DBBC} *
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100 1000 10000
Central Frequency (Hz)
Figure 4: Example of an analysis with MarinEARS:
comparison of the SELos measured for pile driving events in the
German EEZ with and without the application of technical sound
abatement systems.
Figure 4 shows an analysis from MarinEARS regarding the
comparison of the SELos obtained for a pile driving event
with and without the application of technical sound
abatement systems. In addition to a temporal signature of a
sound source. its spectral characteristic 1s a very important
factor for the assessment of noise for marine life. Technical
noise mitigation systems (singular or combined) are efficient
as they are able to reduce the broadband SEL value by more
than 20 dB. The noise reduction is however frequency
dependent. Bubble curtain systems may provide an
especially efficient mitigation of high frequency components
of the piling noise, which is relevant for e.g. harbour
porpoises.
Lessons learnt and Outlook
The noise generated by pile-driving can be significantly
reduced by technical noise abatement systems. Level
reductions (insertion loss) of up to 24 dB can be achieved
compared to unmitigated pile-driving under the premise that
technical sound mitigation concepts are applied successfully.
Three different noise abatement systems were applied during
the majority of the OWF construction in the German EEZ
under real offshore conditions during the previous years. To
date, technical developments regarding noise abatement
systems by the industry have led to a reliable compliance
with the threshold since 2014, despite increasing pile
diameters and water depths at project sites. Cross-project
evaluations regarding noise emissions and the application of
technical solutions are facilitated by the comprehensive data
basis of MarinEARS and provide a valuable knowledge base
for future OWP projects.
Literature
[1] Lucke K., Lepper P.A., Blanchet M.A. & Siebert U.:
Temporary shift in masked hearing thresholds in a
harbor porpoise (Phocoena phocoena) after exposure to
seismic airgun stimuli. Journal of the Acoustical
Society of America 125(6) (2009): 4060-4070
BSH Offshore wind farms: Measuring instruction for
underwater sound monitoring. Current approach with
annotations , Application instructions (2011).
ISO 18406:2017-04: Underwater acoustics —
Measurement of radiated underwater sound from
percussive pile driving (2017).
DIN SPEC 45653:2017-04, Offshore wind farms - In-
situ determination of the insertion loss of control
measures underwater (2017).
BSH Offshore wind farms: Measuring Specification for
the Quantitative Determination of the Effectiveness of
Noise Control Systems. Current approach with
annotations. Application instructions processed by
Müller A. & Zerbs, C. (2013).
Bellmann, M., Brinkmann, J., May, A., Wendt, T.,
Gerlach, S., & Remmers, P.: Underwater noise during
impact pile-driving: Factors influencing impulsive noise
and technical options for complying with thresholds at
activity level. Lessons learned report on the application
of noise abatement systems. Technical Report (2020),
R&D project UM16 881500 funded by the German
Federal Ministry of the Environment on behalf of the
Federal Maritime and Hydrographic Agency (BSH).
[2]
[6]
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