ISO 18406:2017

Underwater acoustics — Measurement of radiated underwater sound from percussive pile driving

ISO 18407:2017 describes the methodologies, procedures, and measurement systems to be used for the measurement of the radiated underwater acoustic sound generated during pile driving using percussive blows with a hammer. A major motivation for undertaking measurements of the sound radiated during percussive pile driving is as part of an assessment of impact on aquatic fauna required by regulatory frameworks. This document describes a generic approach to measurements that can be applied to different regulatory requirements. ISO 18407:2017 is suitable for measurement of percussive pile driving undertaken for offshore installation of foundations (monopiles, jackets, tripods, etc.) used in construction of offshore wind farms, oil and gas platforms, and other inshore structures such as bridge foundations and aquatic renewable energy devices. This document does not cover measurement of the sound radiated by vibro-piling or sheet piling. This document does not cover piling in water of depth less than 4 m or greater than 100 m. The procedures described herein provide guidance on making measurements to satisfy the following objectives: - to monitor source output during piling, for example, for regulatory purposes; - to provide consistency in comparison of piling noise from different construction projects; - for validation of modelling or predictions. ISO 18407:2017 covers only the measurement of the sound field radiated during percussive pile driving. The scope of this document does not include the assessment of exposure metrics, or the use of exposure criteria. No attempt is made to prescribe a methodology for generating maps of the acoustic field in the vicinity of the source. In the normative part of this document, requirements and procedures are described for measurement of the sound field at specific ranges from the pile being driven. In this part of the document, no procedure is provided for determination of an acoustic output metric that is independent of the propagation path between source and receiver (such as a source level). Ideally, such a metric would have some predictive utility (for example, in calculating noise impact zones and noise maps). However, some information on the determination of a possible acoustic output metric is provided in Annex A. ISO 18407:2017 covers only the measurement of sound pressure in the water column. The scope does not include measurement of sound particle velocity in the water column due to the propagating sound wave, or seabed vibration caused by waves propagating across the sea-floor. This exclusion does not imply that such measures are unimportant; indeed, their importance in assessing the impact on aquatic life is recognized. However, at the time of drafting, measurement of these quantities is not yet mature enough for standardization.

Acoustique sous-marine — Mesurage du son sous-marin émis lors de l'enfoncement de pieux marins

General Information

• Status: Published
• Publication Date: 24-Apr-2017
• ICS: 17.140.30 - Noise emitted by means of transport
• Technical Committee: ISO/TC 43/SC 3 - Underwater acoustics
• Drafting Committee: ISO/TC 43/SC 3/WG 3 - Measurement of radiated noise from marine pile driving
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 07-Nov-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 18406
First edition
2017-04
Underwater acoustics — Measurement
of radiated underwater sound from
percussive pile driving
Acoustique sous-marine — Mesurage du son sous-marin émis lors de
l’enfoncement de pieux marins
Reference number
ISO 18406:2017(E)
©
ISO 2017

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ISO 18406:2017(E)

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© ISO 2017, Published in Switzerland
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ISO 18406:2017(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Instrumentation . 5
4.1 General . 5
4.2 Performance of the measuring system . 5
4.2.1 Sensitivity . . . 5
4.2.2 Frequency range and sampling rate . 6
4.2.3 Directivity . 7
4.2.4 Signal-to-noise ratio requirements . 7
4.2.5 System self-noise . 7
4.2.6 Dynamic range . 7
4.3 Calibration . 8
4.3.1 Full system calibration . . 8
4.3.2 Field calibration checks . 9
4.4 Data storage . 9
4.4.1 Data quality . 9
4.4.2 Auxiliary calibration data . 9
4.4.3 Longevity . 9
5 Deployment for measurement . 9
5.1 Deployment methodology . 9
5.1.1 General. 9
5.1.2 Vessel based deployments . 9
5.1.3 Static deployments (moored systems) .10
5.1.4 Drifting systems .11
5.2 Hydrophone deployment .11
5.2.1 Hydrophone deployment depth in offshore waters .11
5.2.2 Hydrophone deployment depth in inshore waters .11
5.2.3 Number of hydrophones .11
5.3 Minimization of platform-related deployment self-noise.12
5.3.1 General.12
5.3.2 Flow noise .12
5.3.3 Cable strum.12
5.3.4 Surface heave .12
5.3.5 Vessel noise.13
5.3.6 Mechanical noise.13
5.3.7 Electrical noise .13
6 Acoustic measurement configuration .14
6.1 Spatial sampling (choosing measurement locations) .14
6.1.1 Criteria for measurement locations .14
6.1.2 Recommended locations for offshore measurements .14
6.1.3 Recommended locations for inshore measurements .15
6.1.4 Measurements of background noise for the purposes of SNR determination.16
6.1.5 Measurements of piles driven at a slant angle to the seabed .16
6.2 Temporal sampling — Measurement duration .16
6.3 Distance measurement .16
6.4 Data processing and calculation of acoustic metrics .17
6.4.1 Data processing steps .17
6.4.2 Acoustic metrics to be calculated .18
7 Measurement uncertainty .21
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ISO 18406:2017(E)

7.1 General .21
7.2 Sources of uncertainty .22
7.2.1 Uncertainty in the calibration of instrumentation .22
7.2.2 Uncertainty in the position of source and receiver .22
7.2.3 Spurious signals introduced by the deployment . .22
7.3 Evaluating uncertainty .22
8 Reporting of results .22
8.1 Auxiliary data and metadata .22
8.1.1 General .22
8.1.2 Mandatory .23
8.1.3 Optional .23
8.2 Pile characteristics .23
8.3 Deployment configuration .24
8.3.1 Mandatory .24
8.3.2 Optional .24
8.4 Reporting of measurement results .25
8.4.1 Mandatory .25
8.4.2 Optional .25
Annex A (informative) Consideration of source output metrics .27
Annex B (informative) Guidance on the use of hydrophones .29
Bibliography .31
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ISO 18406:2017(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 3,
Underwater acoustics.
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ISO 18406:2017(E)

Introduction
This document was written to provide a standardized measurement method for the measurement of
the radiated underwater sound during percussive pile driving.
Sound is often an unintended by-product of man-made activities, and the increasing number of sound-
producing human activities in oceans, seas, lakes, rivers and harbours have led to concern over noise
pollution from unwanted sound and its potential effect on aquatic life. In some countries, there is
already incipient regulation with regard to the impact of the radiated underwater sound, requiring
acoustic monitoring for environmental impact assessment during construction projects.
Percussive pile driving can be a significant source of low-frequency impulsive underwater sound.
During the process, a pile is driven into the seabed (or river-bed, etc.) using a hammer, which is typically
driven hydraulically. Such a technique is commonly used to position piles in shallow water construction
applications. Examples of such applications include the following:
— construction of offshore wind farms;
— construction and mooring of platforms for the offshore oil and gas industry;
— construction of bridge supports and foundations in rivers, estuaries, harbours and quays (and close
proximity to them);
— mooring and positioning of aquatic renewable energy devices.
In the scientific literature, a number of attempts to measure the water-borne noise levels have been
[1]-[13]
reported . Often, these are difficult to compare because different acoustic metrics are used, and
[14]-[16]
this has led to guidance being provided to address the need within individual countries . The
measurement of piling noise is made difficult by a number of factors.
— The source extends from the water surface to the seabed (or river-bed, etc.), generating sound waves
in water, air and seabed, and vibrating the seabed surface.
— The environment is often shallow water which gives rise to substantial reverberation, and
bathymetric features and seabed (or river-bed, etc.) interaction can strongly influence the
propagation of the sound.
Often, simple assumptions about equivalent point sources have been used in measurements and for
propagation modelling without sufficient validation. Progress with modelling the source has been
[17]-[22]
reported in the scientific literature, but a complete understanding has not yet been achieved .
The aim of this document is to provide procedures and methodologies for measurement of sound
radiation into the water, and recommend acoustic metrics to describe the sound field. The assessment
of impact of the radiated sound on marine life is not part of the scope of this document.
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INTERNATIONAL STANDARD ISO 18406:2017(E)
Underwater acoustics — Measurement of radiated
underwater sound from percussive pile driving
1 Scope
This document describes the methodologies, procedures, and measurement systems to be used for the
measurement of the radiated underwater acoustic sound generated during pile driving using percussive
blows with a hammer.
A major motivation for undertaking measurements of the sound radiated during percussive pile
driving is as part of an assessment of impact on aquatic fauna required by regulatory frameworks. This
document describes a generic approach to measurements that can be applied to different regulatory
requirements.
This document is suitable for measurement of percussive pile driving undertaken for offshore
installation of foundations (monopiles, jackets, tripods, etc.) used in construction of offshore wind
farms, oil and gas platforms, and other inshore structures such as bridge foundations and aquatic
renewable energy devices. This document does not cover measurement of the sound radiated by vibro-
piling or sheet piling. This document does not cover piling in water of depth less than 4 m or greater
than 100 m.
The procedures described herein provide guidance on making measurements to satisfy the following
objectives:
— to monitor source output during piling, for example, for regulatory purposes;
— to provide consistency in comparison of piling noise from different construction projects;
— for validation of modelling or predictions.
This document covers only the measurement of the sound field radiated during percussive pile driving.
The scope of this document does not include the assessment of exposure metrics, or the use of exposure
criteria. No attempt is made to prescribe a methodology for generating maps of the acoustic field in the
vicinity of the source.
In the normative part of this document, requirements and procedures are described for measurement of
the sound field at specific ranges from the pile being driven. In this part of the document, no procedure
is provided for determination of an acoustic output metric that is independent of the propagation path
between source and receiver (such as a source level). Ideally, such a metric would have some predictive
utility (for example, in calculating noise impact zones and noise maps). However, some information on
the determination of a possible acoustic output metric is provided in Annex A.
This document covers only the measurement of sound pressure in the water column. The scope does
not include measurement of sound particle velocity in the water column due to the propagating sound
wave, or seabed vibration caused by waves propagating across the sea-floor. This exclusion does not
imply that such measures are unimportant; indeed, their importance in assessing the impact on aquatic
life is recognized. However, at the time of drafting, measurement of these quantities is not yet mature
enough for standardization.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
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ISO 18406:2017(E)

ISO 18405, Underwater acoustics — Terminology
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 18405 (especially: sound
pressure, sound pressure level, mean-square sound pressure level, sound exposure, sound exposure
level, peak sound pressure, peak sound pressure level) and the following apply.
NOTE Although the definitions of sound exposure and sound exposure level are taken from ISO 18405,
specific nomenclature is used in this document for sound exposure level calculated over the duration of one
acoustic pulse, and over the duration of multiple acoustic pulses; this nomenclature is described in 3.2.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
pulse duration
percentage energy signal duration over the acoustic pulse
Note 1 to entry: The percentage energy signal duration is defined in ISO 18405.
Note 2 to entry: The energy percentage over which the pulse duration has been calculated should be stated with
the result. For the purposes of this document, the energy percentage for the pulse duration is 90 %.
Note 3 to entry: In general, in shallow water, the acoustic pulse includes multiple arrivals of the outgoing
acoustic waves, including multi-path signal arrivals from surface and seabed. In reverberant environments such
as harbours, where sound waves may be reflected by boundaries such as harbour walls, it may be difficult to
identify individual outgoing acoustic pulses.
3.2
sound exposure level
SEL
level of the sound exposure, for a specified reference value
Note 1 to entry: The sound exposure level is as defined in ISO 18405.
Note 2 to entry: The sound exposure level for an individual acoustic pulse (corresponding to a single hammer
strike) is calculated over the pulse duration on the basis of 100 % of the pulse energy. For the purposes of this
document, this is termed the single strike sound exposure level (abbreviated as SEL ). It is recognized that in the
ss
scientific literature, this parameter is sometimes called the single pulse sound exposure level.
Note 3 to entry: The sound exposure level over a defined period of time, which includes multiple acoustic pulses,
is, for the purposes of this document, termed the cumulative sound exposure level (abbreviated as SEL ). When
cum
reporting the cumulative sound exposure level, the number of pulses and the time duration over which the
cumulative sound exposure level has been calculated are stated.
Note 4 to entry: In the acoustic near field, sound exposure is not related to the sound intensity or energy in the
straightforward manner that applies for the acoustic far field. Therefore, care should be taken when interpreting
measurements of SEL made in the acoustic near field.
3.3
pulse repetition frequency
pulse repetition rate
number of hammer strikes per unit time
Note 1 to entry: Typically stated as the number of strikes (or acoustic pulses) per second.
Note 2 to entry: It is common for the pulse repetition frequency to be less than 1 per second.
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ISO 18406:2017(E)

3.4
background noise
all sound recorded by the hydrophone in the absence of the pile driving signal for a specified pile driving
acoustic signal being measured
3.5
measurement system
data acquisition system consisting of, but not limited to, one or more hydrophone(s), conditioning
preamplifier(s), analogue-to-digital converter(s), computer and ancillary peripherals
3.6
frequency range
span from the lowest frequency to the highest frequency over which the measurement system is able to
measure, for a given uncertainty
Note 1 to entry: The frequency range is expressed as the lowest frequency to the highest frequency.
3.7
dynamic range
amplitude range over which a measurement system is able to measure, for a given tolerance of
distortion, expressed as a range from the lowest to the highest amplitude
Note 1 to entry: Dynamic range can also be expressed in decibels representing the difference between the level of
the noise floor created by the system self-noise and the maximum level which can be measured with a specified
maximum allowable distortion. It can be expressed for a single frequency or at a range of frequencies.
3.8
field calibration
method of using known inputs, possibly using physical stimuli (such as a known and calibrated/traceable
acoustic or vibration source) or electrical input (charge or voltage signal injection) at the input (or other
stage) of a measurement system in order to ascertain that the system is, in fact, responding properly
(i.e. within the system’s stated uncertainty) to the known stimulus
[23]
[SOURCE: ISO 17208-1:2016, 3.9]
3.9
measurement uncertainty
estimate of the range (or dispersion) of values within which the true value is considered to lie to a
specified degree of confidence (for example, for a confidence level of 95 %)
[SOURCE: ISO/IEC Guide 98-3:2008]
3.10
hydrophone
underwater sound transducer that provides an electrical signal in response to fluctuations in pressure,
and is designed to respond to the pressure of a sound wave
Note 1 to entry: If the electrical signal is proportional to the incident sound pressure, the hydrophone is said to
have a linear response.
3.11
hammer energy
kinetic energy of the hammer used for the pile driving for a specific blow
Note 1 to entry: This is equal to the kinetic energy with which the hammer mass strikes the pile.
Note 2 to entry: The hammer energy is expressed in kJ.
3.12
pile dimensions
dimensions of the pile in terms of the overall length, diameter and wall thickness (if hollow)
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ISO 18406:2017(E)

3.13
offshore
marine area, including coastal areas, regional seas and continental shelf, but excluding harbours,
coastal inlets, inland waterways, river estuaries, and rivers
3.14
inshore
marine or aquatic region, including harbours, coastal inlets, inland waterways, river estuaries, and
rivers, but excluding regional seas, continental shelf and coastal areas
3.15
equivalent bandwidth noise pressure
p
w
ratio of the root-mean-square noise voltage at a specified central frequency in the relevant frequency
band present at the electrical terminals of the hydrophone, in the absence of pressure fluctuations at the
hydrophone input, to its free-field open-circuit hydrophone voltage sensitivity at a specified frequency
Note 1 to entry: Equivalent bandwidth noise pressure is expressed in pascals, Pa.
[24]
[SOURCE: IEC 60500:—]
3.16
equivalent bandwidth noise pressure level
ten times the logarithm to the base 10 of the ratio of the square of the value of equivalent bandwidth
noise pressure, p , of a hydrophone to the square of a reference pressure, p , in decibels
w 0
Note 1 to entry: Equivalent bandwidth noise pressure level is expressed in decibels, dB.
Note 2 to entry: The value of the reference pressure, p , is 1 μPa.
0
[24]
[SOURCE: IEC 6050
...