Principal: Professor Robert Jackson* Forensic Experts in Water, Construction & the Environment

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1 Independent Expert Opinion in Water, Construction & the Environment SEPA Draft Odour Guidance Document A Review on behalf of the Leith Links Residents Association, Edinburgh - August 2008 JACKSON Consulting Principal: Professor Robert Jackson* Forensic Experts in Water, Construction & the Environment Association of Personal Injury Lawyers Approved 7 th Floor UK Register of Expert Witnesses Approved Silkhouse Court Institution of Civil Engineers Listed Expert Tithebarn Street Member of the Academy of Experts Liverpool L2 2LZ Law Society Checked Expert Tel +44(0) Fax+44(0) Mob jackson@jexperts.fsbusiness.co.uk *Member of Council - Chartered Institution of Water & Environmental Management *Accredited Mediator for Civil & Commercial Disputes (ADR Group) *Member of Council - The Academy of Experts

2 Air Policy Unit SEPA Corporate Office Erskine Court Castle Business Park Stirling FK9 4TR 25 th August 2008 For the attention of Mr Ian Halliday Dear Mr Halliday, SEPA Draft Odour Guidance Document The Leith Links Residents Association (LLRA) in Edinburgh has requested that I write to you, on their behalf, regarding the above with particular emphasis to Odour Exposure Criterion for Private Nuisance; the relevant sections of the SEPA proposed guidance are referred to below in normal text with corresponding comments given in italics. INTRODUCTION The Scottish Environment Protection Agency (SEPA) is Scotland s environmental regulator. Its aim is to..contribute to the Government s goal of sustainable development. The UK Government defines sustainable development as meeting four objectives at the same time, nationally and globally which include: Social progress which recognises the needs of everyone Effective protection of the environment Prudent use of natural resources Maintenance of high and stable levels of economic growth and employment In order to meet these objectives, the government has developed a set of principles and approaches which capture key sustainable development themes and combine legal principles with decision making tools. These include Putting people at the centre Respecting environmental limits The precautionary principle Transparency, information participation and access to justice Making the polluter pay PART 1: GENERAL FUNDAMENTALS OF ODOUR 1.3 Why assess odour? The effects of odour emissions are assessed for a wide range of reasons, including complaint investigation. The amount and type of information required for an assessment depends on the circumstances of the odour discharge and the reason for undertaking the assessment. Usually the aim of the assessment is to determine the source and whether the odour is offensive and objectionable, therefore causing adverse effects on the local community. However, major effects on affected residents may be anxiety and stress rather than any particular odour occurrence. How are these effects to be assessed?

3 1.4 What is an offensive odour? The key to understanding the principle of an offensive odour is that the mere presence of an odour does not necessarily mean that it is offensive. The characteristics of an odour that are taken into account when assessing its offensiveness are frequency, intensity, duration, odour unpleasantness, and location. There is no clear benchmark for assessing an odour for offensiveness. The H4 Guidance document provides a benchmark criterion of no reasonable cause for annoyance to establish the point at which an odour impact becomes unacceptable. For modelled releases, this point was established where odour in the air was estimated on a 1 hour average for 98% of the time. This provides a reasonable basis to inform.the required upgrading of existing facilities, it does not address the issue of that proportion of an affected community which may be more sensitive to odour than the normal population. It is often stated that A concentration of 1 OU/m3 corresponds to the threshold of detection of the odour by about 50% of the populace. That is, on average, half the people will detect an odour and half will not. Additionally it implies that a fraction smaller than one half will detect even smaller odour concentrations. A protocol is often developed by which the exposure of each (and every) complainant may be determined. A model can then be calibrated by comparing the results, concentration and time, with community response in terms of complaints made by residents of the local area. However, the two principal inputs to any odour modelling process are the emissions inventory and the choice of appropriate meteorological data, both of which may often be subject to major uncertainties; these uncertainties will have a major influence on the estimates of odour concentration contours and related statistics. For modelled releases, the odour concentrations can be calculated with dispersion models; the odour emission rates are usually based on monthly averages and the meteorology based on hourly averages. However, when estimated emission rates are based on monthly averages it is important to note that for around half the days the emission rate for that day will be larger than this value and for half the days it will be smaller. Eventually the emission rates will be transformed into various concentrations impacting on the neighbourhoods around the plant. As the concern with odours is based upon their exceeding critical levels, the use of monthly rather than daily averages will lead to an underestimate of the impact on the public. Similarly the use of daily averages of emission rates rather than hourly averages of emission rates will lead to a further underestimation to the impact of the odours on the public. The simplest approach would be to decide upon a particular simple and appropriate criterion of nuisance. As in the draft guidance document it is sometimes argued that four factors must be considered: Sole source Duration of exposure (minutes or prolonged) Frequency (daily, weekly, or monthly) Strength of offensiveness of odour but very often this information is simply unavailable.

4 There are, however, other matters of importance which should be taken into account including the linking of the number or frequency of complaints directly to the magnitude of the emissions since there are many reasons that will lead people to making a complaint i.e. the scale or degree of the nuisance being taken as proportional to the frequency at which complaints are made; odour fatigue; the variation of odour, possibly over a matter of only a few seconds leads to awareness of an odour; the knowledge that odours could occur in the near or distant future may cause anxiety or stress and lead to a restriction on activities; resident anxiety about the future worth of their property because of emissions of the nearby plant may need to be considered; and the annual recurrence of a problem that had been thought to have been resolved is likely to produce further concerns. The PPC Horizontal Guidance Note for Odours Parts 1&2 (H4) provides a benchmark criterion of no reasonable cause for annoyance to establish the point at which an odour impact becomes unacceptable. Hence, is it not reasonable that odours having a significant and distracting effect on humans, which are persistent and widespread and which are at an intensity, offensiveness and extent that leads to a change in behaviour of those exposed including nausea or sickness, always be defined as a nuisance? Such odours could reasonably include those within the offensive category of Appendix 1: Table A Monitoring Odours In general, the available techniques can be broken down into two different approaches; sensory and chemical techniques. The technique which will be appropriate essentially depends on the objective of the exercise as well as the likely chemical cause of the odour. For the most part, members of the public will not complain about a specific compound but of a generally foul odour Sensory Techniques:Field Testing/Investigation It will often be the case when dealing with potential offensive odour complaints that a SEPA officer will receive a communication from a member of the public which will require an immediate response in order to investigate and/or verify the justification for the complaint. Assuming the officer can identify the likely source of the odour (from local knowledge, information gleaned from the complainant etc) the officer should then identify a number of testing locations.. At each location, the officer should use their olfactory sense to assign a scaled numerical attribute to any odour encountered, typically a description of the odour, its intensity and persistence. In addition, a number of basic meteorological conditions should be noted (e.g. air temperature, wind speed and direction, pressure, precipitation etc). It would be appropriate that a visiting officer should also record details of the topography. Topography may produce a topography induced uphill flow on warm/hot days with light winds. Under such circumstances, days of light winds would produce the largest odour concentrations and on these days a topography induced flow, possibly aided by a sea-

5 breeze would be particularly problematic. Indeed, a distinctive feature of the east coast of Scotland s weather is the 'haar' - a dense sea mist created by the movement of warm air over cold water that often blows in from the North Sea when the wind is in the east. People are able to escape the haar by heading just a few miles inland, which suggests that it lingers near the coast, but it can strike throughout the summer months and gives rise to an unusual set of climatic conditions. Indeed, conditions such as periods of dead calm or episodes of fog or mist can result in the gradual build up of odour local to its source, possibly to high levels, with a potential risk of a mass of odorous air slowly drifting off in an unpredictable direction. PART 3: REGULATING OPERATIONAL FACILITIES 3.2 Routine Inspections and Compliance Assessment A general theme for inspection will be local management practices, as experience indicates that poor management practices such as supervision, maintenance and training tends to lead to repeated and extended releases of odour. There are clear expectations that sites which may give rise to offensive odour are operated to a consistently high and robust standard such that the likelihood of a release is minimized, and where a release does occur it is effectively managed to mitigate any potential impact. Meteorological conditions are of prime importance since the majority of odour control techniques ultimately rely on dispersion for minimization of odour effects. If conditions prevail that are disadvantageous for dispersion, then odours may be detected even though the best available control methods are in use. PART 4: INCIDENT AND COMPLAINT RESPONSE INCLUDING INVESTIGATION AND ENFORCEMENT 4.1 Introduction The release of odorous substances may, if the odour is offensive or causes a nuisance, be a breach of an environmental licence. Further, in all circumstances the presence of offensive odour will need to be corroborated by other witnesses, preferably another authorized SEPA officer. It is advised that the SEPA officer investigating and/or monitoring any prolonged or repeated offensive odour events should seek to confirm if any health symptoms have been reported by members of the public. An often-used hypothesis is that: the absence of complaints is an indicator that there is no nuisance, independently of the time/history or space context of the public. For the case where there is a long history of complaints regarding odour emissions from a particular area of a site, which is commonly responsible for offensive odour releases, would it not be appropriate, and wholly reasonable, for a nuisance to have occurred when overwhelming numbers within the affected community lodge formal complaints? How many repeated problems warrant the withdrawal of a licence?

6 4.2 Categorising an incident and suggested enforcement options A Major Odour Incident is one in which the release: A) would involve a significant and distracting effect on humans. A significant and distracting effect on humans means odour that is persistent and widespread. The odour is at an intensity, offensiveness and extent that it leads to a change in behaviour of those exposed e.g..causes nausea or sickness. OR B) could have a major adverse effect on amenity value or economic impact. The cause of the odorous release would normally be as a result of an incident at an installation, resulting in a release of odour which is sufficiently strong, offensive and persistent that it interferes with activities or causes disruption at sensitive receptors. Examples include private dwellings. which are impacted for a prolonged period of time. It is likely that a number of people are affected by the odour and that the impact extends beyond daytime disturbance e.g. weekends, evenings and public holidays. Ignoring concentration fluctuations from day to day and from hour to hour and lastly, on times shorter than 1 hour i.e. timescales that are very important for odour detection, will reduce the calculated impact of odours on the public. In the case of a major odour incident, as described above, would it not be appropriate, and wholly reasonable, for a nuisance to have occurred when overwhelming numbers within the affected community lodge formal complaints, without the need for the presence of offensive odour(s) to be corroborated by a single Local Authority/SEPA official? PART 5: WORKING WITH COMMUNITIES Statutory Guidance to SEPA.directs SEPA to address human health under its duties and to ensure it upholds the principles of environmental justice. Due regard must be made to environmental justice considerations to ensure the quality of life of communities is not degraded and, where possible, is enhanced. One of the reasons for a local community s concerns regarding odour impact is often the length of time from identification of a problem to its resolution; even though SEPA may have taken appropriate action to prevent further incidents. Although care has to be taken to ensure that complaint rates have not been influenced by other factors such as local politics, in some instances local politics may be the only effective route for the public to use to ensure notice of a nuisance is taken. If complaints are being made and no solution is appearing, the setting up of community groups is a very appropriate way to proceed. For the case where there is a long history of complaints regarding odour emissions from a particular area of a site, which is commonly responsible for offensive odour releases, what would SEPA s response be to the following questions: what is appropriate action by SEPA? and given the above scenario, what is a reasonable length of time from identification of a problem to its resolution?

7 We look forward to your responses to the comments raised and to the questions posed. Many thanks. Yours sincerely, Professor Robert Jackson cc Robert Kirkwood (Chairman LLRA) John Telfer (Scottish Water)