Matlock Sewage Treatment Works

03 July 2026 by Elise Phoenix

Noise impact assessment for a heritage-sensitive process plant upgrade

Tilbury Douglas commissioned Spectrum Acoustic Consultants to assess the noise impact of a major modification to the Sewage Treatment Works at Matlock in Derbyshire. The upgrade increased capacity, reduced storm spills and lower phosphate levels to improve the health of the River Derwent. The works have been carried out on a constrained site surrounded by sensitive receptors and significant heritage constraints.

For a main contractor delivering a process-plant upgrade in this kind of setting, the acoustic position has to be clear, defensible and agreed with the relevant authorities before the work can proceed with confidence. That was the remit Spectrum was appointed to deliver.

This is the kind of work Spectrum is regularly engaged to deliver. Where a project carries acoustic risk, whether from new plant, a sensitive location or competing regulatory expectations, involving an acoustic consultant early gives the project team a clear position to design and build against.

Contractors and consultants facing similar demands can talk to Spectrum about the acoustic requirements on their own scheme before those risks reach site.

The challenge

The site at Matlock sits in a noise-sensitive location, close to a number of heritage assets including scheduled monuments and Grade II listed buildings, as well as nearby rail infrastructure. This combination created several constraints that had to be addressed together rather than in isolation.

The first was the sensitivity of the surrounding receptors. Residential properties and protected buildings nearby meant that any new or modified plant had to be assessed against realistic, defensible noise limits rather than broad assumptions. Getting this wrong at assessment stage risks objections or costly redesign later in the programme.

The second was the technology itself. This involves new processes for UK sewage treatment works, which means there is less established noise data to draw on than for conventional plant. The acoustic behaviour of the new equipment, including blowers, pumps and associated mechanical services, had to be characterised carefully rather than taken just from generic sources.

Third, the heritage setting limited how mitigation could be applied. Visible barriers, enclosures or large structural interventions close to scheduled monuments and listed buildings would attract scrutiny. Any noise control measures needed to be effective while remaining proportionate and sympathetic to the surroundings.

Finally, the site fell across the boundaries of two separate local planning authorities: Derbyshire Dales District Council and Amber Valley Borough Council. Each had its own expectations and its own environmental health input, so the assessment had to satisfy both without contradiction.

Spectrum’s approach

Spectrum drew on extensive experience in noise monitoring and assessment for industrial and water treatment sites to establish a clear, evidence-based picture of the acoustic conditions at Matlock.

The work began with a baseline noise survey to establish the existing sound environment at the relevant receptor locations. This data, including the prevailing background sound levels, formed the foundation for the assessment in line with BS 4142:2014+A1:2019, the standard used to rate and assess sound of an industrial and commercial nature.

With the baseline established, Spectrum predicted the noise impact of the modified works using iNoise, the 3D noise modelling software developed by DGMR. Building a detailed model allowed the team to represent the new plant, its position and the surrounding terrain and structures, then test the predicted noise levels at each sensitive receptor.

Modelling at this stage means potential exceedances can be identified and resolved on paper, before they become problems on site.

The model also allowed mitigation options to be tested and refined. Rather than applying blanket measures, Spectrum could show where control was actually needed and what level of attenuation would achieve compliance. This supports practical, buildable solutions that the contractor can deliver within the project timeline and budget.

Spectrum Acoustic Consultants liaised directly with Derbyshire Dales District Council and Amber Valley Borough Council throughout to ensure the methodology, assumptions and conclusions were understood and accepted by both authorities.

Early engagement of this kind reduces the risk of late objections and gives the contractor and the wider design team confidence that the acoustic position will stand up to scrutiny.

“Sites like Matlock combine several pressures at once – a sensitive setting, heritage constraints and relatively new treatment technology with limited reference data,” said Andrew Corkill, Principal Consultant at Spectrum Acoustic Consultants. “Our role was to cut through that with a robust baseline and a detailed 3D model, so we could show exactly what the noise impact would be and where, if anywhere, mitigation was needed. That gives the contractor a clear, defensible position to work from.”

Bala Sharma, Acoustic Consultant at Spectrum, who also supported the project, comments, “Modelling the modified works in iNoise let us test the design before anything was built, which is far more efficient than reacting to issues on site. It also gave us a clear, shared basis of evidence for our conversations with both councils, so everyone was working from the same numbers.”

How Spectrum works with clients

The Matlock project reflects how Spectrum approaches complex industrial and process-plant acoustics. The process is consistent – understand the site and its constraints, measure the existing conditions, model the proposed changes in detail, then use that model to develop mitigation that is both compliant and practical to build.

What ties this together is regulatory engagement. Technical work only delivers value if it satisfies the authorities who control consent.

By engaging with environmental health officers and planning authorities early, and presenting clear, defensible evidence, Spectrum helps clients avoid the delays and added cost that come from objections raised late in a programme.

For main contractors, civil engineers, environmental consultants and local authorities, this combination of detailed modelling, regulatory engagement and practical mitigation is what turns an acoustic challenge into a resolved part of the project.

Outcome

Spectrum delivered a baseline noise survey and a 3D noise model of the modified works using DGMR’s iNoise, having liaised with both Derbyshire Dales District Council and Amber Valley Borough Council.

The result was a clear, evidence-based assessment of the noise impact of the upgrade, giving Tilbury Douglas a defensible acoustic position and a sound basis for the next stages of the project.

The project demonstrates Spectrum’s capability in complex industrial and process-plant acoustics, combining detailed modelling, regulatory engagement and practical mitigation to deliver compliant, buildable solutions.

Working with Spectrum

If you are delivering a water treatment, industrial or process-plant project and need a clear, defensible acoustic position, Spectrum Acoustic Consultants can help.

At the assessment, planning or design stage, our team can establish the baseline, model the impact and engage with the relevant authorities on your behalf.

Contact our team by telephone 01767 318871, by email, or fill out our contact form and we will contact you as soon as we can.

Please note, the image below is a stock image and does not represent the site at Matlock. This is to protect the client’s site work.