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The EPA's two previous publications are withdrawn.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many of their existing permits are written around withdrawn guidance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of the two withdrawn documents, but there are new requirements and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
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
Efficiency is that a systematic approach is required and
this is more effective and cheaper than a 'hit-and-miss'
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
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
1 runs per location
2 runs per location
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
- 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