How to Measure – Boundary Noise

Introduction

‘Boundary noise’ is a relatively widely used term but is only a part of Environmental Noise Monitoring and is not specific to any one regulation or standard.

There may be many reasons to measure noise levels at the boundary of an industrial premises, construction site, quarry or even an airport and it will often be done through an agreement between the Local Authority or the various national environment agencies and the site operator.

Section 61 Consent

Section 61 of the Control of Pollution Act 1974 applies to construction or demolition sites where there may be significant impact on the neighbourhood due to the generation of noise and vibration.

Companies can apply for consent to operate under section 61, which means that there will be an agreement as to the maximum levels of noise and vibration that are generated, usually with a monitoring plan and actions where limits are exceeded.

As part of the application, an assessment would normally be required according to BS5228-1:2009 Code of practice for noise and vibration control on construction and open sites – Noise.

If a company chooses not to apply for section 61 consent, the local authority may issue a section 60 notice, which can lead to work being stopped due to complaints of excessive noise or vibration levels.

The preferred location for monitoring sound is always at the receiving property, and certainly for a BS5228 assessment, this would be the case. When it comes to a monitoring plan, however, it is more usual to measure at a site boundary as this is far simpler to affect and is withing the control of the operator. Agreed levels in this case are calculated back from the receiver location.

Monitoring for section 61 application, using BS5228 would normally be carried out at a noise sensitive receptor property if possible. Once consent is granted the monitoring plan will probably state that fixed monitoring equipment should be placed at or near the site boundary, which will often monitor relatively simple parameters every hour. Modern equipment, such as the dBAngel can send that data to a cloud server, which will then send on alerts to management if noise levels are exceeded.

Complaint Remedy (BS 4142)

Complaints about industrial and commercial operations from residents, will normally be assessed according to BS 4142:2014, Methods for rating and assessing industrial and commercial sound. This standard does not go as far as to say what happens if a complaint is found to be reasonable, so one solution may be to agree on maximum boundary levels, that can be monitored with equipment in very much the same way as for Section 61 consent.

Environmental Permits

Any operation that involves potential pollution of the land, air, or water, must apply for an environmental permit and this includes noise and vibration, where it is not part of a section 61 consent.

Environmental permits are managed by the Environment Agency, Scottish Environment Protection Agency (SEPA), Natural Resources Wales and Northern Ireland Environment Agency.

Applying for a permit will often entail an environmental impact assessment (EIA), or environmental risk assessment, which should include noise and vibration and there are specific requirements for such an assessment, which we will deal with in a separate application note.

While the impact assessment will usually involve measurements at the noise sensitive receptor, a permit will often be granted with specific conditions for noise and vibration, which is monitored at the boundary of a site, with a fixed monitoring station.

What is measured?

The conditions put on a section 61 consent, an environmental permit, or those issued by a Local Authority can be almost anything but mostly end up in the form of hourly L_Aeq levels that must not be exceeded, occasionally with L_AMAX added in for good measure and sometimes there might be the need to record any exceedances as audio files, so that the nature of that sound can be determined. The conditions may be based on monitoring at a noise receptor, or on the boundary of the business premises.

The equipment for doing this can be quite simple if all you need is hourly measurements of basic parameters. The complexity comes in the way the data is collected, which in modern equipment, such as the Castle dBAngel may be via the internet, where triggers are set for any number of conditions and alerts sent by email or SMS.

Collecting audio files can also be slightly more challenging as they need someone to listen to them to identify whether the noise trigger event is caused by the site or by something else. We once saw significant exceedances every morning, which turned out to be the dawn chorus!

Equipment

It may be possible to comply with a permit or Local Authority condition manually, whereby a person would take a hand-held sound meter out to various points at intervals throughout the day to monitor for the maximum permitted levels. This would have to be within the agreement of the licencing authority!

More commonly, a noise monitor or monitors, with weatherproofing would be placed at the relevant point(s) around the boundary. This might be a sound level meter in a box, such as the Castle E-box, or a more permanent solution in a cabinet, like the dBAngel, which would be mounted to a pole or boundary fence.

Powering these systems can come in the form of mains power run from the site, a 12V supply from an external battery box, a solar panel, or a combination of them. There is a separate article on powering environmental sound meters on the Castle Group website.