The sound of silence
Steve Fraser, principal environmental consultant at the Edinburgh office of RPS Consultants, examines how the IPPC regulations have involved the Environment Agency and SEPA in regulating environmental noise at industrial and waste management sites.
One important difference between the regulation of noise and other pollutants is that the draft IPPC Noise Guidance favours an effects based approach, where the existing or predicted noise levels are assessed against baseline conditions, whereas for air or water pollution the determination of BAT is compared against sector or industry benchmarks. The UK Environment Agencies, published draft Noise Guidance in two parts last year, Horizontal Guidance Note IPPC H3. This Guidance has been out for consultation and is due for publication, apparently largely unchanged, later on this year.
The main assessment tool proposed by the Guidance is the flawed BS 4142 1997. The emphasis in the Guidance is on loss of amenity, rather than sleep disturbance. Apart from this glaring omission, in general, part 1 of H3 is a useful introduction to the subject, and is full of sensible advice on the practical difficulties and pitfalls of drafting conditions and enforcement. Part 2 – Noise Assessment & Control provides a useful introduction to the more technical aspects of the subject. <
For organisations with no track record in the subject, the Guidance augurs well. The Agencies recognise that most enforcement staff have little practical experience in the subject and have appointed topic specialists to evaluate new IPPC Applications. There is talk of a specialist centre of excellence similar to the team set up to validate air dispersion modelling. One concern for process operators is that this can cause logjams in determining applications where noise is a significant issue.
In England and Wales, part B processes will continue to be enforced by EHOs, who have a long track record in environmental noise enforcement. One potential double whammy for process operators is that IPPC may duplicate existing planning conditions, and could lead to local disputes between local Councils and Agencies.
In the long run new IPPC processes will only be controlled by authorisation conditions, in line with UK planning Guidance which warns against using planning conditions to control environmental pollution where there are other more effective statutory controls. Similarly IPPC processes will be exempt from the nuisance provisions of EPA 1990. For most IPPC applications, where the process is up and running, compiling the noise information for an application can be relatively straight forward. In most cases, health and safety managers will have information about noise levels within the works.
This can be used as a starting point to compile an inventory of noisy plant and equipment, for different process areas. Obviously the purpose of occupational noise assessment is to measure exposure of the workforce and is usually not concerned with impacts beyond the boundary fence. It is important to consider noise from roofs and other elevated areas, as well as noise from externally located plant or operations such as loading yards.
Occupational noise surveys usually ignore areas where the noise level is less than 80dBA. Noise at this sort of level can be of crucial importance in environmental terms, particularly if conducted in the open air or at night.
Noise radiating out through the walls and roofs can also be a significant source of noise. More usually the problem is ducts, fans, and cooling plant, doors left open or transport of materials outside using a fork lift truck with a really annoying reversing alarm. Beware of seasonal factors – noise can escape through open doors – especially in hot weather, when local residents will use their gardens more, as well as sleep with their windows open.
The person conducting the assessment must be able to tap into the knowledge at the works: detailed and practical experience of operations, including any variations in production activities and through put. It is always worth putting in the effort early on in the design of the survey. Don’t forget to check the complaint log (if there is one). Once the source inventory has been compiled, measure the noise for each item of plant, ideally close to source. Measurements should include octave or third octave band analysis and record observations about tonal, impulsive or intermittent characteristics.
Instrumentation must be calibrated. In many cases noise levels from specific items can’t be measured separately without access to specialist kit, in which case it is advisable to measure by process areas. The location of measurement points at the boundary fence and representative sensitive receptors should be chosen with care and always in consultation with the Regulator.
Weather conditions affect the propagation of noise and the careful logging of cloud cover, temperature, wind speed and direction, throughout the survey are essential. British Standards 7445:1991 and 4142:1997 provide further guidance on the meteorological effects of weather. All survey reports must record relevant process conditions which can help with interpretation of the results.
In many cases it can be useful to conduct computer modelling of noise sources to help assess the relative importance and contribution from each item of plant and the benefit arising from any proposed abatement works. Where noise from a building is concerned, the model will require building dimensions, the form of construction, surface areas as well as high quality noise source data.
The model can be used to predict noise at fixed point receptors that can help validate predictions against measured levels, as well as noise contours in pretty colours. However, the computer model selected must be appropriate for the task.
Most proprietary models are based on particular protocols or Standards, e.g. computer models based on BS 5228:1997 are suitable for modelling most external operations, but can’t be used to consider noise escaping from buildings. Use of a computer model based on CONCAWE 1981 is probably suitable for predicting noise from stationary sources, but the complexity of the weather effects may render it useless as a planning tool.
The real fun will begin where operators are applying for a new permit or propose substantial change. For industry the concern remains that the Regulators will lack the experience to exercise professional judgement whether the noise is a significant impact or not and will tend to ask for a high level of detail where a simple assessment should suffice.
For some, this is just another layer of euro-bureau, with unknown costs, and replacing perfectly satisfactory domestic legislation. If applied wisely, the incorporation of noise within the authorisation process may, in the longer term, help improve quality of life.