Underwater acoustics - Measurement of radiated underwater sound from percussive pile driving
|Publication Date:||1 April 2017|
|ICS Code (Noise emitted by means of transport):||17.140.30|
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 vibropiling 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.