New Noise Monitoring Requirements

The EPA recently published new noise monitoring guidance, termed NG4. On the face of it, this is only of interest to holders of IPPC and Waste Licenses. However, many local authorities when requesting noise monitoring, or setting limits, will often refer to EPA guidelines and, therefore, this new publication should be of interest to all organisations, including local authorities, where noise is an issue.

This article attempts to explain what is important in the new document and how it will impact stakeholders.

The EPA's two previous publications are withdrawn. These were the Environmental Noise Survey Guidance Document published in 2003 and the Guidance Note For Noise In Relation To Scheduled Activities 2nd Edition published in 2006.

It is, therefore, important that local authorities recognise that many of their existing permits are written around withdrawn guidance and steps should be taken to update permits and new planning conditions.

Much of the new guidance document is an amalgamation of the two withdrawn documents, but there are new requirements and clarification of areas where there has been ambiguity. The two most important changes are the introduction of an evening noise limit and the minimum duration for noise surveys.

Up until now, EPA noise limits and those set by many local authorities have been a general daytime limit of 55 dBA and a general night-time limit of 45 dBA.

The times of the start and end of daytime and night-time have now been changed and a new evening period has been introduced with a general limit of 50 dBA.

For sites in 'Quiet Areas' and 'Low Background Noise Areas', lower limits will apply - but these will be in the minority and for all other licensed sites the general limits will apply.

Regardless of the area, the definition of daytime, evening and night-time are the same.

The new rules are summarised in the graphic - see right - (the limits quoted are those for all sites except 'Quiet Areas' and 'Low Background Noise').

On the positive side, for industry, the start of daytime start has been brought back to 07:00 from 08:00. Thus, the limit for this one-hour period will change from 45 dBA to 55 dBA. This will benefit sites where morning operations start before 08:00 - for example, where air compressors and other equipment is needed to start up before production.

However, the lower limit of 50 dBA for a four-hour period in the evening (19:00 to 23:00) will impact many sites with second shifts. To reduce noise levels from 55 dBA to 50 dBA will require considerable effort. Many sites will have daytime noise levels in the range 50 dBA to 55 dBA and, thus, whilst previously compliant, will now have problems if they operate in the evening period.

Fortunately, the evening limit will not come in to effect for existing licensees until their licence is reviewed. However, any new licences issued will have this requirement. It is also likely that the local authority will include these periods and limits in new permits and planning conditions. The question is what can be done to comply with the new limits when they come into force. The experience of Environmental Efficiency is that a systematic approach is required and this is more effective and cheaper than a 'hit-and-miss' approach.

The first requirement is to understand where the noise is coming from and its contribution to the noise level at the noise sensitive locations (NSLs). The noise limits apply to the NSLs, so this has to be the focus of the study. The tool for gaining this understanding is the Noise Prediction Model. This model will predict noise levels at any NSL, based on the noise level of each piece of equipment at a standardised distance, the presence of barriers and the intervening ground type.

Once the model has been created, the effect of barriers or noise attenuation measures can be investigated. For example, if an air compressor in an open shed is a significant noise source, then the options available are re-location further away from the NSL, new air compressor, installation of noise absorbent material, doors to the shed or a barrier. These options can be investigated at negligible cost and the most effective one chosen.

One of Environmental Efficiency's clients was a large sawmill and their noise limits were being breached at the NSLs. Processes on site included mobile equipment, log grading lines, kilns, log chippers, saws and a boiler. The model found that a combination of barriers and reduction in fan speed on the kilns would reduce the noise levels at the NSLs to below the limits. Post implementation noise monitoring confirmed that the predicted noise reduction had been achieved.

While the duration of the monitoring run at each noise location is specified in the licence or permit (usually either 15 or 30 minutes), the number of runs at each location was not specified in the old guidance. This would usually mean that the licensee would only ask for one run per point to be measured in order to keep costs down. The new guidance now specifies the number of runs and survey duration as illustrated in the following table -

Runs per location
Minimum Survey Duration
3 runs per location
4 hours
1 runs per location
2 hours
2 runs per location
3 hours

Of course, the EPA guidance contains much more than this - however, for most users these are the main points. If further information is required, the reader should consult the EPA Guidance document or contact Environmental Efficiency as follows -

  • Republic of Ireland - Tel: 01 276 1428
  • Northern Ireland - Tel: 028 9262 6733

The author of this article - Bob Sutcliffe - is a director with Environmental Efficiency, an environmental consultancy focusing on the industrial and commercial sector with offices in Bray. Co. Wicklow and Lisburn, Co. Antrim.
Bob is a Chartered Engineer (CEng, IEI) and has over 40 years experience in manufacturing industry. Follow Bob on Twitter and on his blog


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