Walnut Acoustics conducted detailed noise monitoring at an existing site and used noise modelling to assess the proposed new site with BS 4142:2014+A1:2019 methodology.
Mitigation strategies were developed to satisfy local authority environmental health noise criteria, and to help in securing planning approval for the change of use.
Project Overview
Walnut Acoustics were engaged to provide noise consultancy services for the conversion of a commercial building into an auto-repair centre. The site was located near residential noise-sensitive receptors (NSRs), raising concerns over the potential impact of vehicle repairs, car washing, and external mechanical plant noise.
Our objective was to conduct a detailed Noise Impact Assessment (NIA) to evaluate how these operations would affect the surrounding environment and to develop mitigation strategies to satisfy local planning requirements.
Challenges & Requirements
Assessment of Key Noise Sources – Evaluate potential noise from:
- Internal repair workshop operations.
- Car park and car wash areas.
- Repair centre ventilation and extraction systems.
- BS 4142 assessment – Ensure noise emissions meet acceptable criteria for new commercial and industrial noise sources.
- Background Noise Monitoring – Establish existing background noise levels to provide a reference for assessing the potential noise impacts from the new site.
- SoundPLAN Noise Modelling – predicting plant and site noise levels at the nearest residential NSRs – modelling plant noise sources, buildings and mitigation solutions (including an acoustic grade boundary fence).
Our Approach
1. On-Site Noise Survey & Background Data Collection
A detailed noise survey was conducted to capture existing background noise levels, ensuring an accurate reference point for assessing potential noise impacts from the proposed new auto repair centre noise sources. Data for these sources was measured at an existing repair centre.
2. Noise Modelling & Impact Assessment
Using SoundPLAN, we modelled noise levels from multiple sources across the site, including:
- Workshop activities – Noise generated from tools, machinery, and plant from within the proposed repair centre.
- Car wash and car park.
- External mechanical plant – HVAC, extract ventilation systems, and compressor plant.
- We then assessed how the predicted noise levels would impact upon the nearest residential NSRs under different operational scenarios and considered mitigation measures where adverse impacts were expected.
3. Noise Mitigation Strategy Development
To ensure compliance with the required noise criteria, we worked with the client’s design and planning team to implement effective noise control measures, including:
- Acoustic design of mechanical systems to reduce external noise – acoustic enclosures around external elements where required.
- Operational noise limits – Implementing restrictions on certain activities during late hours – ensuring workshop doors are closed at night.
- Revised site layout – Adjusting the positioning of external noise sources away from residential boundaries.
- Sound insulation upgrades – Enhancing building fabric to reduce noise breakout from internal workshop operations.
4. Planning Submission & Local Authority Engagement
Our Noise Impact Assessment (NIA) provided:
- Clear evidence that the mitigation measures would effectively reduce noise exposure at residential properties.
- A detailed response to planning authority queries, ensuring all concerns were addressed.
- An approved acoustic strategy, enabling the project to proceed without additional delays or objections.
Results & Project Impact
- Planning Permission Secured – Noise impact concerns were fully addressed, allowing the development to proceed.
- Minimal Noise Disturbance for Residents – Effective mitigation ensured compliance with local authority EHO noise criteria.
- Smooth Approval Process – The comprehensive noise assessment report streamlined discussions with the local authority.
- Long-Term Compliance – Recommendations provided a future-proofed acoustic strategy for the business.
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