Methods and Personnel
Best Practicable Means
Charlie usually carries out this work himself. He will arrange, with the environmental health officer, to visit the house of the complainant and measure the noise therein. He will then calculate by how much it has to be reduced to get it down to the level which will satisfy the environmental health officer. If he thinks that the level is too strict, he will contest this with the officer. Details of how Charlie solves particular noise nuisance cases follow.
If the offending noise is music emanating from a night-club, pub, etc, Charlie will firstly cast an experienced eye around the building. This initial appraisal will lead him to conclude as to which sound transmission paths out of the various elements of the building are likely to be significant. The elements of the building which are usually significant are the roof, doors, ventilation outlets and inlets, and sometimes the walls. He will then measure the noise in the building close to these elements. The distance from the complainant’s house to the elements of the building, together with their dimensions, will also be measured. The materials of which the various elements of the building are made will also be noted. The noise levels measured inside, together with this other information, can then be used to calculate the relative significance of the elements of the building. This is essential in providing cost effective advice, as it shows exactly by how much the sound emanating from each element of the building must be reduced, and the noise control measures required can be specified precisely.
Most local authorities stipulate that the noise must be controlled so that it is inaudible. Whilst Charlie does not agree with this criterion, it is well established now and contesting it is not advised. Notwithstanding, what level environmental health officers consider will, or will not be audible, varies and there is sometimes scope for discussion on this.
The noise control measures might involve re-designing the sound system, modifying the construction of the building, or erecting an acoustic barrier between it and the complainant’s house. There are also a number of other ways of solving this type of noise nuisance.
If the noise is emanating from a factory building, the approach to the problem is exactly the same as that outlined above under Music Noise. There is, however, no set level to which the noise must be reduced, and Charlie usually works to those published by the World Health Organisation and in British Standard 8233: 1999 Sound insulation and noise reduction for buildings- Code of practice. Some environmental health officers stipulate that the noise be assessed to British Standard 4142: 1997 Method for Rating industrial noise affecting mixed residential and industrial areas (BS4142). This document is very punitive against the party making the noise, and Charlie has a long list of reasons which he presents to the environmental health officer to contest its use.
Mechanical Services Plant Noise
If the source of the complaint is mechanical services plant, the measurement exercise will involve switching various items on and off to establish which one, or ones, are causing the problem. A detailed investigation close to the offending item(s) will then be made to determine how it is radiating the noise. Again, this means that the noise control measures can be specified precisely.
Most environmental health officers impose a noise level limit of noise rating, abbreviated to NR, 25 to this type of noise at night, and NR35 to it during the day. To reduce the noise to these levels might involve, for example, fitting an in-duct attenuator, installation acoustic louvres, lagging ductwork, re-orientation of the duct termination, constructing an acoustic enclosure around the plant, or building a acoustic barrier between it and the receiver.
Chemical Petrochemical and Food Processing Plants
In these types of installations, the noise may be emanating from a building, in which case it is dealt with as described earlier under Industrial Noise. There may also be many items of plant located outside. These are often dealt with in the much same way as described under Mechanical Services Plant. Whilst the items of plant are mechanical services, environmental health officers sometimes try to have them considered under BS4142, which for reasons given earlier, Charlie will contest.
Heavy Goods Vehicles and Mobile Plant
If the source of the complaint is heavy goods vehicle movements, fork-lift trucks or other mobile plant, the noise will be measured to establish which one, or ones, are causing the problem.
There is no set level to which the noise must be reduced, and Charlie usually works to those published by the World Health Organisation and given in BS8233.
To control the noise, quieter plant can sometimes be brought in, working practices changed, loading bays modified, acoustic enclosures built, bunds or acoustic barriers erected.
Distribution Depots, Quarrying, Landfill and Waste Transfer
The sources of noise in these premises can be a mixture of that emanating from buildings, which are then considered as described earlier under Industrial Noise, and that from mobile plant, which is dealt with as discussed under Heavy Goods Vehicles and Mobile Plant.
Construction Site Noise
This does not cause problems very often, as environmental health officers generally adopt a pragmatic view that it is temporary. Furthermore, applying noise control measures will tend to prolong the construction programme, so the complainant gets lower levels of noise, but for longer. When dealing with this kind of complaint, the noise of the various items of plant, and activities, is measured. The offending items are then identified and the reduction in noise required calculated.
Some local authorities have developed their own limits for this type of noise, and these are usually quite easy to achieve. We can advise on whether these limits will be achievable, as they are sometimes contained in what is called a Notice of Prior Consent, issued by a local authority before work commences. If exceeding the limits, and Charlie considers them to be fair, noise control can then be applied in the form of acoustic enclosures, using quieter items of plant, applying silencers or “hush-kits” to plant, erecting acoustic barriers and so on. Charlie will also consider the methods and procedures suggested in British Standard 5228: 1997 Noise and vibration control on construction and open sites. This document might well be referred to in correspondence from the environmental health officer.
As with many other sources of noise, there is no set level to which that from sports pitches must be reduced, and Charlie usually works to those published by the World Health Organisation and given in BS8233. Methods of reducing the noise are limited, but acoustic barriers can be designed, and the boards and fencing used modified to reduce the noise of the ball hitting them.
If Charlie considers that the environmental health officer’s target is unreasonable, as they sometimes are, he will contest it. He may also suggest that you use the defence of best practicable means
. The essence of this is that you state that you have done everything you can reasonably be expected to do to reduce the noise. It may also be the case that further expenditure on noise control would compromise the continuing success of your business.
When measuring the noise Charlie will use a Brüel & Kjær Modular Precision Analyzer Type 2260, loaded with the Enhanced Sound Analysis Software Type BZ7202. Brüel & Kjær is the “Rolls Royce” of acoustical instrumentation, and the 2260 is the most accurate and reliable hand-held sound level meter available on the market.