As offshore wind turbines increase in size, the installation of larger monopile foundations requires more powerful hammers than ever. This can generate significant noise both offshore and near the coastline. Understanding this early in the project enables developers to proactively manage environmental risks, avoid delays and optimise installation strategies.

The developer of a new offshore wind farm in East Asia needed to predict airborne and underwater noise levels during monopile installation to assess compliance with local regulations and support their environmental impact assessment. Having already completed a detailed monopile drivability and installation risk assessment for the project, 2H was subsequently contracted to carry out the nearfield noise study.

Project Overview

The proposed wind farm is located less than 2.5 km from the shoreline, placing increased scrutiny on installation noise levels and its potential impact on coastal communities and marine life.

The development includes monopiles ranging from 7.5 m to 10.5 m in diameter and up to 82 m in length. Installation is planned to be conducted using a Menck 3500 kJ hydraulic hammer, one of the most powerful hammers used in offshore wind construction today.

To mitigate airborne and underwater noise during installation, the hammer will operate alongside a Menck Noise Reduction Unit (MNRU).

To ensure that the assessment captured a realistic range of installation conditions, 2H analysed three representative monopiles covering different pile sizes, penetration depths and soil conditions.

2H’s study was designed to provide clear, actionable insights by:

• Predicting near-field airborne and underwater noise levels generated during monopile installation using the project-specific soil conditions, hammer system and monopile design.

• Quantifying how installation parameters such as pile diameter, penetration depth and hammer energy influence noise emissions.

Acoustic Modelling Approach

2H developed a robust 2D axisymmetric acoustic model to simulate how the pile driving noise generated propagates through the surrounding air and ground.

The model incorporated the monopile geometry, hammer characteristics, soil conditions and environmental parameters to accurately represent real installation behaviour. Careful model design ensured that acoustic waves travelling through different materials were accurately represented while preventing artificial reflections from model boundaries.

Results & Insights

The study provided clear, quantitative predictions of expected installation noise during monopile installation giving the client a strong basis for decision-making.

Key outputs included:

• Sound pressure level (SPL): Maximum instantaneous noise experienced

• Sound exposure level (SEL): Total noise per hammer blow

• A-weighted SPL and SEL: Noise levels adjusted to reflect human hearing

• LAeq: Equivalent continuous noise level over the installation time of one monopile

These results enabled the client to assess whether the planned installation approach complied with local noise regulations and whether additional mitigation measures would be required well before installation was to begin.

By combining industry-leading drivability expertise with advanced acoustic modelling, the 2H project team was able to support the client in managing installation risk and optimising their overall construction strategy.

2H’s Noise Modelling Capabilities

As offshore wind projects continue to scale up, managing installation noise is becoming increasingly important.

Building on decades of experience in pile drivability and foundation engineering, 2H offers advanced acoustic modelling services to support developers across all project lifecycle phases.

These include:

• Near-field noise assessment

• Far-field noise assessment

• Airborne noise assessment

• Underwater noise assessment

Beyond prediction, 2H also assesses the effectiveness noise mitigation strategies, allowing clients to compare options and select the most practical and cost-effective solutions.