ER31 Final Report January 2013

Odour monitoring and control on landfill sites

EXECUTIVE SUMMARY Objectives Responding to odour complaints consumes a lot of agency resources. Sometimes, the odour that is the source of the complaint is very slight (of borderline intensity) and is generated by a facility that may be operating within the conditions of its permit (e.g. not exceeding odour limits). Given that perception of odour by complainants – particularly weak odours – is subjective, the agencies’ assessments are also subjective and, therefore not always consistent. The aim of this project is to help the agencies develop more effective and transparent methods of subjective assessment so that there is a more consistent approach between facilities and devolved administrations. Research project ER31 - Best practice for odour monitoring and control and community engagement at landfill sites was commissioned by Sniffer on behalf of the four environment agencies of the UK and the Republic of Ireland to provide up-to-date information on best practice for the management of odour at landfill sites, best practice for engagement and communication with local communities regarding odour, and legal cases/decisions involving odour (with emphasis on those related to landfill activities). The objectives of this research project were to: 1. Identify best practice for site management of landfill activities with respect to controlling and monitoring odour emissions; 2. Identify best practice for engaging and communicating (for both the regulator and the facility) with local communities affected by malodorous emissions; and 3. Identify and summarise legal rulings related to odour (with emphasis on those associated with waste (landfill) activities), including the arguments/reasons behind these rulings and, where appropriate, the penalty/award amounts). The results of this project are presented in two separate reports. The results of the research undertaken to satisfy the second objective are presented in ER31 report Review of legal decisions regarding odour (Sniffer, 2012). This report covers objectives 1 and 3.

Key findings and recommendations This report is a review of existing research and guidance from the past 10 to 15 years, and it seeks to draw this together into an overarching summary of best practice for monitoring and controlling landfill odour in the UK and the Republic of Ireland. It is neither a detailed description of best landfill practice nor odour science, as these subjects are far too large to be encompassed within the scope of this research project. Where further information is considered beneficial to the reader in relation to specific issues, reference has been made to specific literature which is considered to provide a comprehensive account of this subject. The principal limitation to this portion of the research project was the scarcity of publically available measurement data available in relation to odour emission rates from landfill sites, which would have allowed for robust scientific quantification of the effectiveness of mitigation measures. The limited measurement data available has been presented. From the research synthesis, best practice for monitoring and controlling landfill odour falls into (and is provided using) the following categories:     

Odour impacts: background, science and quantification; Regulation and guidance at landfill sites; Odour sources and characteristics; Causes of odour emission from landfills and measures for control of odorous emissions; Impact assessment and monitoring;

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 

Odour management plans (aims and content); and Engagement and communication.

As part of undertaking this research, parties (operators, regulators, and community groups) associated with 19 various landfills in the UK and Republic of Ireland were surveyed (26 surveys were completed and returned) so that case studies regarding operations management and community engagement could be developed to illustrate best practice. The aim of these case studies is to highlight ‘best practice’ which can be adopted by other sites. These sites were nominated by the representatives of the four environment agencies of the UK and Republic of Ireland participating in and guiding this project. They were nominated because they historically have been sources of odour complaints, have a good odour management plan (OMP), or have practices in place that work well. From the surveys, three issues dominated the responses related to existing challenges/problems: (1) lack of communication, (2) timing / length of communication chain, and (3) lack of co-operation (all parties). There is strong evidence to suggest that optimal communication will reduce the operator’s (and the regulator’s) time and financial commitments as many issues can be resolved promptly (or even avoided altogether in the case of foreseen odour events, such as gas field management) and transparently. In all cases, proper timing is critical. Operators should seek to be proactive where possible, and react promptly to any unforeseen events. Various communication tools are provided in the report.

Project context Landfill facilities account for a large proportion of all complaints received by the environment agencies from members of the public. Addressing these complaints consumes substantial agency resources. The public expects the agencies to deal effectively with odour levels they find unacceptable – treating these odours as pollution and taking appropriate enforcement action to ensure that operators deal with the sources of odour in a timely fashion (or temporarily or permanently shutting down these facilities if they are either unwilling or incapable of bringing the impact of odour emissions to a level that is considered acceptable). This is fairly straightforward when a facility operator is violating the conditions of his permit. However, this is not the case when odour emissions are slight and perhaps emanating from multiple sources, and the facility is operating within its permit. Odour problems involve three “stakeholders”: the regulator, the facility operator, and the impacted public. Compliance violations involve the regulator taking some sort of action against the facility operator – frequently in response to a complaint from the public. When odour releases are slight or negligible and the facility operator is in compliance, then more effective engagement with the impacted public by both the regulator and the facility operator may be the most appropriate strategy. The primary end users for this research are the inspectors working in the waste sector. Operators of waste facilities, as well as their consultants or equipment suppliers, will also benefit from this research as it will provide clarity on what is expected to meet best available techniques (BAT) and ensure that the impact of odour emissions is acceptable. This information will also be of use to agency staff with responsibility for drafting policy, guidance, and establishing permit conditions. Finally, the information will also be very useful for reviews of BREFs of the landfill sector.

Recommendations for further research Two areas for further, complementary research have been identified. 

There is a clear lack of quantitative emissions data for landfill operations, particularly in relation to modern operations and current ‘fresh’ waste and landfill gas compositions. It is

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

suggested that a study should be commissioned that involves sampling at landfill sites and deriving indicative data (or date ranges) for the purposes of landfill planning. This report discusses impact criteria for other waste management (composting) facilities. There are currently no criteria against which the ‘acceptability’ of the odour impact should be judged for landfill sites. The development (and appropriateness) of such criteria should be discussed with the waste management sector as this would represent a more transparent approach to odour regulation.

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CONTENTS 1. INTRODUCTION........................................................................................ 1 2. ODOUR IMPACTS: BACKGROUND AND SCIENCE ....................................... 4 3. QUANTIFICATION ................................................................................... 10 4. REGULATION AND GUIDANCE AT LANDFILL SITES .................................. 13 5. ODOUR SOURCES AND CHARACTERISTICS .............................................. 21 6. CAUSES OF ODOUR EMISSION FROM LANDFILLS .................................... 31 7. MEASURES FOR CONTROL OF ODOROUS EMISSIONS ............................. 37 8. IMPACT ASSESSMENT ............................................................................ 54 9. MONITORING......................................................................................... 56 10. ODOUR MANAGEMENT PLANS: AIMS AND CONTENT ............................ 67 11. ENGAGEMENT & COMMUNICATION ...................................................... 72 12. RECOMMENDATIONS FOR FURTHER RESEARCH ..................................... 82 13. REFERENCES ........................................................................................... 83

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1.

INTRODUCTION

Research project (ER31 - Best practice for odour monitoring and control and community engagement at landfill sites) has been commissioned by Sniffer on behalf of the four environment agencies of the UK and the Republic of Ireland to provide up-to-date information on best practice for the management of odour at landfill sites, best practice for engagement and communication with local communities regarding odour, and legal cases/decisions involving odour (with emphasis on those related to landfill activities). The four environment agencies of the UK and Republic of Ireland who commissioned and contributed to this project are:    

Environment Agency (EA), England and Wales; Scottish Environment Protection Agency (SEPA), Scotland; Northern Ireland Environment Agency (NIEA), Northern Ireland; and Environmental Protection Agency (EPA), Republic of Ireland.

The purpose of this research project is to provide up-to-date and relevant best practice for odour control and monitoring at landfill sites, as well as proactive engagement with impacted communities. The output from this research project will aim to benefit both regulators and facility operators. This report represents the first output (of two) of the project which comprises a review of best practice for odour control at landfill sites and methods for effective communication with affected communities.

Background to study Odour from waste facilities (including landfill sites) is regulated by the four environment agencies in their respective jurisdictions. Although the majority of waste facilities in the UK and Republic of Ireland are well run, landfill sites account for a large proportion of all odour complaints received by the environment agencies from members of the public. The public expects the environment agencies to deal effectively with unacceptable odour levels. Whilst this can be fairly straightforward when a facility operator is clearly violating the conditions of their permit (or licence), this is not the case when odour emissions are emanating from multiple sources, and the facility is operating within its permit, which may have a clause requiring that ‘appropriate measures’ are taken to avoid unacceptable impacts. What constitutes an appropriate measure is sometimes not clear.

Scope of this report The objectives of this report are to: 1. Identify best practice for site management of landfill activities with respect to controlling and monitoring odour emissions; and 2. Identify best practice for engaging and communicating (for both the regulator and the facility) with local communities affected by malodorous emissions.

Approach This report is essentially a literature review. There are a number of similar reports, research papers and guidance documents that have been published over the past 10 to 15 years and this report seeks to draw these together into an overarching summary of best practice for monitoring and control of landfill odour in the UK and the Republic of Ireland.

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In addition, a survey of landfill operators was undertaken to compile case studies regarding operations management and community engagement. Case studies Throughout this document, case studies are presented. Although anonymous, these are based on real sites in the UK and the Republic of Ireland. Information has been gathered from surveys issued to operators, regulators and community groups representing 19 sites nominated by the Sniffer ER31 Technical Advisory Group. In most cases, they are sites where there were historically odour complaints and the case studies illustrate the methods by which these were overcome. In all cases therefore, they represent ‘success stories’ in relation to the information presented. The aim of these case studies is to highlight ‘best practice’ which can be adopted by other sites. It must be noted that several landfill operators chose not to participate in the survey as a result of perceived risk of repercussions. The information received from those operators who chose to participate was extremely useful in that it has allowed a balanced view to be presented and some success stories to be passed on to other operators. Engagement and communication The results of the surveys have also been used as the basis for chapter 10 of this report. In each of the returned surveys (totalling 26 from the regulators, operators and community groups relevant to the 19 sites), the participant was asked to describe the existing methods of engagement, rate their effectiveness, and suggest an alternative method (where appropriate). The ‘best practice methods’ and optimal communication pathways described in this report are the result of this feedback.

Report structure Environmental impacts result from a defined impact pathway:

source

control

pathway

receptor

The initial chapters of this report provide a background to the science and regulation of odour from landfills in the UK and worldwide. The impact pathway as it related to landfill is then addressed progressively:    

Chapter 5: Potential odour sources associated with landfilling; Chapter 6: A description of how odours may be released from a landfill and dispersed (i.e. the pathway); Chapter 7: How they may be controlled (i.e. to disrupt the pathway); and Chapters 8 and 9: How the effectiveness of the control may be assessed / predicted and monitored in the field (i.e. whether a pathway to the receptor remains).

Limitations This report is not a detailed description of either best landfill practice or odour science as these subjects are far too large to be encompassed within a document such as this. Where further

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information is considered beneficial to the reader in relation to specific issues, reference has been made to specific literature which is considered to provide a comprehensive account of this subject. The main limitation to this study was the scarcity of publically available measurement data available in relation to odour emission rates from landfill sites, thereby allowing robust scientific quantification of the effectiveness of mitigation measures. Available data has been presented however it must be recognised that this only provides a ‘snapshot’ of measured emissions from limited sites and the potential margins of error will therefore be significant in relation to specific landfill sites.

References Sources are referenced throughout this report in an abbreviated manner, in addition to a full list of references included as Chapter 13 of this report.

Health and safety The methane in landfill gas is explosive and trace compounds may be toxic at sufficiently high levels. Landfill sites are covered by both generic and site specific health and safety legislation. In all cases, health and safety must take priority over all other considerations. The advice in this report is not intended to overrule site rules or risk assessments. No responsibility will be accepted by Sniffer, the ER31 technical advisory group, or the author for damage or injury which results from persons engaging in potentially hazardous activities as a result of this literature review document. In all cases, site specific risk assessments should be in place before any activities are undertaken.

Acknowledgements Sniffer, the ER31 Technical Advisory Group (TAG), and the author of this report would like to express our thanks for the survey participants, including operators, regulators and liaison groups. The information gathered from the survey has been extremely valuable when assessing the effectiveness of control options and also optimal communication routes.

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2.

ODOUR IMPACTS: BACKGROUND AND SCIENCE

The sensory perception of odorants can be characterised by four major attributes or ‘dimensions’1:    

Detectability; Intensity; Hedonic tone; and Odour quality.

The science of odour impact assessment is therefore complex and more than just a function of odour strength (concentration). In order to understand the relative contribution of odour sources from a landfill and their potential to cause an unacceptable impact, a basic understanding of odour concentration and emission is required. It is not within the scope of this document to provide a comprehensive review of the science of the perception of and response to a stimulus, such as odour (known as ‘psychophysics’). There is however a large body of literature which describes these factors in detail, including:   

Environment Agency (2002) Assessment of Community Responses to Odorous Emissions. R&D Technical Report P4-095/TR, July 2002; DEFRA (2010) Odour Guidance for Local Authorities, March 2010; and SEPA & Natural Scotland Scottish Government (2010). Odour Guidance 2010. Version 1, January 2010.

A summary of the key issues is provided in this chapter.

Terminology: Nuisance vs. annoyance ‘Annoyance’ is the negative reaction that occurs as a result of an immediate exposure to an ambient stressor (e.g. odour)2. ‘Annoyance potential’ is a measure of the likelihood of a specific odour to cause a negative reaction. ‘Nuisance’ is the cumulative effect, caused by repeated events of annoyance resulting from exposure to an odour over an extended period of time, that leads to modified or altered behaviour, such as complaining, closing windows, keeping ‘odour diaries’ or avoiding use of the garden. It has been reported1 that nuisance occurs when people are affected by an odour they can perceive in their living environment (home, work environment, recreation environment) and:    

The appraisal of the odour is negative; The perception occurs repeatedly; It is difficult to avoid perception of the odour; and The odour is considered a negative effect on their well-being.

‘Nuisance potential’ is the characteristic of an exposure situation, which describes the magnitude of the nuisance that can be expected in a human population when exposed in their living environment to an odour intermittently, but over an extended period of time.

1

Environment Agency (2002) Assessment of Community Responses to Odorous Emissions. R&D Technical Report P4-095/TR, July 2002 2 Aatamila, M., Verkasalo, P.K., Korhonen, M.J., Suominen, A.L., Hirvonen, M., Viluksela, M.K., Nevalainen, A. 2011. Odour annoyance and physical symptoms among residents living near waste treatment centres. Environmental Research 111 (2011) pp164-170

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What happens between odorant formation and submission of a complaint can be summarised below:

formation of odorant

transfer to atmosphere

atmospheric dispersion

exposure

perception

appraisal

annoyance

nuisance

complaint

Figure 1 – Steps from odorant formation to complaint [Adapted from: Environment Agency (2002) Assessment of Community Responses to Odorous Emissions. R&D Technical Report P4-095/TR, July 2002]

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FIDOL It has been extensively reported that the acceptability of an odour perception event (i.e. an ‘impact’) is directly related to a combination of interacting factors, often referred to by the acronym FIDOL3,4,5,6:     

Frequency; Intensity; Duration; Offensiveness; and Location.

All five FIDOL factors will need to be considered when assessing the seriousness of an odour event. Frequency Even an odour which would generally be perceived as ‘pleasant’ can generate complaints if exposure is very frequent. Examples include residences close to factories involved in the manufacture of household cleaning products and even air fresheners. It is generally recognised that, at low concentrations, a rapidly fluctuating odour is more noticeable than a steady background. Odour assessments should consider whether the odour discharge is likely to cause chronic effects (low-intensity odour occurring frequently over a long period), or acute effects (high-intensity odour occurring infrequently), or both. Intensity Odour concentration is a measure of the detectability of an odour as assessed by a panel of people. Odour intensity is defined as the perceived magnitude of a stimulus7. Intensity increases as a function of concentration. The relationship between perceived intensity and the logarithm of odour concentration is linear. A standard method exists for ranking intensity on a scale from faint to strong by a panel of trained observers which is derived from the German Standard VDI 38828. This scale is used by regulators in the UK and the Republic of Ireland. This method is shown in Box 1. As described above, although intensity increases with concentration, the relationship between odour intensity and concentration is logarithmic and therefore an increase or decrease in concentration will not always produce a corresponding proportional change in odour strength as perceived by the human nose9. 3

BOX 1. VDI 3882, Part 1: Intensity descriptors 0 1 2 3 4 5 6

No odour Very faint odour Faint odour Distinct odour Strong odour Very strong odour Extremely strong odour

Nicell, J.A. 2009. Assessment and regulation of odour impacts. Atmospheric Environment 43 (2009) pp196206. 4 SEPA Odour guidance 2010. Version 1, January 2010. 5 Environmental Protection Agency Office of Environmental Enforcement (OEE) Air Guidance Note 5 (AG5). Odour Impact Assessment Guidance for EPA Licensed Site. Environmental Protection Agency. 6 Environment Agency Technical Guidance Note H4 – Odour management 7 Sarkar, U and Hobbs, S.E. (2002) Odour from municipal solid waste (MSW) landfills: A study on the analysis of perception. Environment International. Volume 27, Issue 8, March 2002, Pages 655–662. 8 VDI 3882: 1997, Part 1: Determination of Odour Intensity, Beuth Verlag, Dusseldorf, Germany. 9 Stevens, S.S., The Surprising Simplicity of Sensory Metrics, American Psychologist, 17:29-39. 1962.

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For example, increasing the concentration of an odorous chemical or mixture by a factor of 10 may only increase its perceived intensity by a factor of 2. Conversely, if a site is causing odour pollution in a community, abatement equipment may have to reduce odour concentrations at the sensitive receptors by 90% in order to halve the intensity of odour they perceive10. An ‘intensity description’ score may be plotted against the logarithm of the odour concentration (or the dilution factor). The regression line characterises the relationship between perceived intensity and odour concentration. The point where the regression line intersects with the horizontal axis is equivalent to the detection threshold. This relationship between landfill gas concentration and landfill odour intensity has been defined in published research11. The Odour Intensity Referencing Scale (OIRS), similar to the VDI 3882 method already described, is a tool used mainly in the US; but it is of relevance to the UK and the Republic of Ireland when compared with European reference standards,12 as summarised in the table below13. Table 1 – n-butanol intensity scale reference

8-point n-butanol scale in air (ppm)

n-butanol intensities (ppm) in air

Theoretical concentration ouE/m3

1

12

0.06

2

2

24

0.14

4

3

48

0.34

9

4

96

0.82

21

5

194

2.02

51

6

388

4.91

123

7

775

11.9

298

8

1550

29.0

724

The odour ‘recognition threshold’ is usually regarded as being a factor of 5 or more higher than the detection threshold, meaning that an OIRS reference score of 3 would normally be regarded as a ‘distinct’ odour14 and is used as the basis for derivation of ‘level of distinct odour awareness’ (LOA) used in the derivation of Acute Exposure Guideline Levels (AEGL) for hazardous substances in the US15. 10

Planning Policy Statement (PPS) 23, Planning and Pollution Control, Office of Deputy Prime Minister, 2004. Sarkar, U and Hobbs, S.E. (2002) Odour from municipal solid waste (MSW) landfills: A study on the analysis of perception. Environment International. Volume 27, Issue 8, March 2002, Pages 655–662. 12 n-butanol is used the reference odorant for the European Reference Odour Mass (EROM) as described in BS 3 en 13725. One EROM evaporated in 1 m of neutral air is the standard olfactory stimulus, equivalent to 1 3 3 European odour unit: 1 ouE/m . Therefore: 1 ouE/m = 40 ppb/v n-butanol 13 Adapted from: Segura,J & Feddes, J (2005) Relationship Between Odour Intensity and Concentration of nButanol. Written for presentation at the CSAE/SCGR 2005 Meeting Winnipeg, Manitoba June 26 - 29, 2005. 14 These concentrations must not be confused with benchmarks described in Chapter 3, which are based on a th 98 percentile impact of hours in the year. 15 US EPA Interim Acute Exposure Guideline Levels (AEGLs) Methyl Mercaptan (CAS Reg. No. 74-93-1). Interim 2: 10/2008. 11

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This data can be graphically presented as follows:

Figure 2 – Intensity scale n-butanol [Source: Segura, J. & Feddes, J., (2005) Relationship Between Odour Intensity and Concentration of n-Butanol.] This approach demonstrates that simple site monitoring (‘sniff testing’, as described in Chapter 9) can be linked to more objective measures of assessment and quantification. Duration The length of any particular odour event or length of time exposed to the odour. Nuisance is not caused by short-term exposure, and is not alleviated by relatively short periods (months) of absence of the odour. Nuisance typically appears to be caused by long-term, intermittent exposure to odours16,17. Offensiveness The ‘hedonic tone’ of an odour is a measure of its relative pleasantness at a given odour intensity. The measurement scale for hedonic tones (as shown in Box 2) ranges from +4 for very pleasant odours to -4 for offensive odour at the same measured concentration. BOX 2. VDI 3882 Part 2 – Hedonic tone descriptors +4

very pleasant

-1

mildly unpleasant

+3

pleasant

-2

moderately unpleasant

+2

moderately pleasant

-3

unpleasant

+1

mildly pleasant

-4

offensive

0

neutral odour / no odour

16

Cavalini, P.M., (1992), It´s an ill wind that brings no good: studies on odour annoyance and the dispersion of odorant concentrations from industries, dissertation, University of Groningen. 17 Winneke, G., Kastka, J., (1987) Comparison of odour annoyance data from different industrial sources: Problems and implications., In: Koelega, H.S. (ed.); Environmental annoyance: characterisation, measurement and control, p.129-141

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Location The type of receptors will be key, e.g. housing and hotels will be of particular sensitivity, whereas primary industry will be less sensitive (as described in Box 3) BOX 3. ‘Sensitive receptors’ and frequency of exposure Sensitive receptors for purposes of odour regulation will typically be defined as residential locations as it is here that impact limits (based on a percentile of hourly averages over a year) should be applied. This will typically include the gardens of these residences. Other locations where there is the potential to cause a loss of amenity may include workplaces (offices in particular), hospitals, car showrooms, recreational areas such as sports pitches, play parks and golf courses, hotel, restaurants and retail establishments. It is important to recognise that the same quantitative annual odour exposure criteria (such as the C98 1-hour XouE/m3 benchmarks) should not be applied at these locations as for residential receptors due to the lower frequency of exposure.

Summary Most regulators require that odour assessments should consider whether the odour discharge is of low-intensity odour occurring frequently over a long period, or high-intensity odour occurring infrequently, or both18. In fact, the FIDOL principle demonstrates that there are several factors that may be ‘influenced’ in order to mitigate odour impacts at a particular site. Employing one (or more) methods to influence these factors, where appropriate, may significantly decrease the likelihood of causing a serious odour event.

18

The Ministry for the Environment (June 2003). Good Practice Guide for Assessing and Managing Odour in New Zealand. Air Quality Report 36. ISBN: 0-478-24090-2

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3.

QUANTIFICATION

This chapter provides a brief introduction to the terminology and units used when quantifying odours, including those from landfill sites.

The European odour unit (ouE) Predicted (or measured) emissions and impacts presented in quantitative odour assessments in the UK and the Republic of Ireland are typically based on the use of the European Odour Unit (ouE), as defined in the British Standard BS EN 13725. This approach allows impact assessment of any odorous gas as it is independent of chemical constituents and centres instead on multiples of the detection threshold (i.e. the physiological response of a human) to the gas in question. As the odour unit is a Standard Unit (in the same way as gram or milligram) the notation used in odour assessment follows the conventions of any mass emission unit as follows: • • •

Concentration: ouE/m3; Emission: ouE/s; and Specific emission (emission per unit area): ouE/m2/s.

These are described in more detail below. Concentration An odour threshold is determined by diluting an odour to the point where 50% of the test population (or odour panel) can no longer detect the odour. The original odour concentration of an odour sample can be characterised by the number of dilutions to reach this detection threshold. At the detection threshold the odour concentration is 1 odour unit per metre cubed (1 ouE/m3). BOX 4. Example: Odour concentration (ouE/m3) A sample of LFG is taken from the gas collection system of a landfill site. This sample is analysed in a UKAS accredited laboratory where an olfactometer is used to dilute the sample to the ‘odour threshold’. If the olfactometer has diluted the sample by a factor of 100,000 and 50% of the odour panel can detect the odour, the concentration of the original LFG sample is reported as 100,000 ouE/m3. The process of dilution to threshold is known as ‘olfactometry’ and is undertaken using an ‘olfactometer’ (as shown in Photo 1). All laboratory analysis should be undertaken in accordance with the European CEN standard method EN13725 Air quality – Determination of odour concentration by dynamic olfactometry. Landfill gas has been measured extensively and the concentration reported to be in the range 40,000 – 2.2 million ouE/m3 (refer to Chapter 5) at these sites. Emission and specific emission Knowing the concentration of an odour does not tell you how much of that odour is released. A landfill site with highly odorous LFG may be of lower risk of emission than one with much less odorous LFG where the containment system is less effective. Emission rates may be calculated for odours released from a ‘point’ source with an outward flow, as follows: Odour emission (ouE/s) = odour concentration (ouE/m3) * volume flow (m3/s)

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Photo 1 – Olfactometry (photo courtesy of Odournet UK). Landfill sources where this calculation may be required include:   

Passive vents on sites with no active gas control; Engines and flares (unburned LFG); and Vents on covered leachate storage tanks (particularly when filling).

Sampling is undertaken using an extractive technique, such as the ‘lung method’. This method relies on applying a vacuum on a sample drum in order that air is drawn directly into a sample bag without passing through a pump (for further details refer to Chapter 9). BOX 5. Example: Odour emission (ouE/s) A sample of LFG is taken from a passive vent on a landfill site. This sample is analysed in a UKAS accredited laboratory and the concentration of the LFG is given as 100,000 ouE/m3. The volume flow is measured at 0.2m3/s. The odour emission from this point source is therefore reported as 20,000 ouE/s.

Odorous point sources are unusual on landfill sites as the highest potential for odour release is typically from area sources such as open landfill cells and the tipping area (‘working face’). However, they can be common on small sites / cells, for example where there is insufficient LFG for effective

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treatment or utilisation. Emission rates per unit area, known as ‘specific emission rates,’ may be calculated for odours released from area sources as follows: Specific odour emission (ouE/m2/s) = odour emission (ouE/s) * area (m2) Landfill sources where this calculation may be required include:    

Open leachate storage; Active cells of landfill sites; Capped areas of landfill sites; and Biofilters (treating low calorific LFG).

To establish specific emission rates from liquid and solid surfaces, use of a sampling hood (such as a ‘Lindvall Hood’) is the preferred method (for further details refer to Chapter 9). BOX 6. Example: Specific odour emission (ouE/m2/s) An odour sample is collected from the surface of a leachate lagoon using a (floating) Lindvall Hood. The concentration of the sample is given as 1,000 ouE/m3. A ‘hood factor’ H must then be applied which is dependent upon the dimensions of the flow path of that specific hood and the speed of the air flow (typically around 0.2m/s). H is calculated from the ‘contact area’ under the hood and the cross section of the flow path (and will typically be around 0.01 although must be calculated for each hood). This calculation will provide a specific odour emission rate in units of X ouE/m2/s, in this example the result being 2.0 ouE/m2/s (equivalent to 7200 ouE/m2/hour).

Indicator determinants An alternative approach to the assessment of odour emission and impact is through use of indicator determinants. These are often used where one gas is dominant in the emission, even if this gas is itself not odorous. In the case of LFG, methane is sometimes used for this purpose. By pinpointing releases of methane, the main sources of LFG can be identified19. However, this is typically used as one of many tools for assessment as:  

19

Other landfill operations (such as the tipping) may lead to the release of odour without a significant contribution of methane; and The concentration of trace constituents (which may be highly odorous at very low concentrations) may be largely independent of the methane concentration.

Environment Agency, Guidance on monitoring landfill gas surface emissions. LFTGN07 v2 2010

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4.

REGULATION AND GUIDANCE AT LANDFILL SITES

Irrespective of the site (and country), odour issues may arise from release of odorants from waste which is being tipped at a site (i.e. at the tipping area) and / or from landfill gas (LFG). Despite these common issues, the regulation of landfills is as diverse as the methods of impact assessment. A detailed description of the regulatory framework in the UK and the Republic of Ireland is provided in the second report published under Sniffer project ER31: Sniffer (2012) ER31 - Best practice for odour monitoring and control and community engagement at landfill sites. Final Report: Review of legal decisions regarding odour. This chapter provides a brief summary of the scale of landfilling and regulatory drivers in Europe and selected countries of the world. It also provides some detail relating to methods of assessment, where available.

Landfills in the UK and the Republic of Ireland The EU Waste Framework Directive20 provides the overarching legislative framework for the collection, transport, recovery and disposal of waste. The Directive requires all Member States (including those in the UK and the Republic of Ireland) to take the necessary measures to ensure waste is recovered or disposed of without endangering human health or causing harm to the environment. BOX 7. Directive 2008/98/EC. Chapter II General Requirements: Article 13 Protection of human health and the environment Member States shall take the necessary measures to ensure that waste management is carried out without endangering human health, without harming the environment and, in particular: (a) without risk to water, air, soil, plants or animals; (b) without causing a nuisance through noise or odours; and (c) without adversely affecting the countryside or places of special interest.

As a result of this legislation, the share of landfilling in the 27 EU Member States dropped from 68% in 1995 to 38% in 200821. Switzerland, Germany, the Netherlands, Sweden, Austria, Denmark and Belgium have reported landfill rates below 5%, in part due to national legislation, such as in Sweden which introduced a landfill ban on organic material in 2005. Despite the requirement to reduce reliance in landfilling in Europe, there remain a large number of regulated sites (active and non-active) in the UK and the Republic of Ireland. Landfill rates in 2008 were 63% in the Republic of Ireland which compare with the landfill rates of the southern European nations of Portugal (62%) and Spain (52%). But this rate is notably better than Greece (81%) and Bulgaria, which landfilled 100% of its municipal waste in 2008. Data provided by the regulatory authorities of the UK and the Republic of Ireland is as follows: 

At the end of 2010 in England and Wales, there were 497 operational, permitted landfills either meeting the requirements of the Landfill Directive, operating subject to an appeal

20

DIRECTIVE 2008/98/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 19 November 2008 on waste and repealing certain Directives 21 http://epp.eurostat.ec.europa.eu/statistics_explained/index.php/Municipal_waste_statistics

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

 

against refusal, or to an agreed landfill extension22. During 2010, regulated waste facilities in England and Wales managed nearly 140 million tonnes of waste. Of this, 45.9 million tonnes were landfilled; SEPA23 report that, at the end of 2010, there were 72 landfills still authorised (active and non-active). Further information supplied directly by SEPA indicates that as of 2012, they regulate 81 landfill sites with PPC permits and approximately 350 closed landfill sites under waste management licences; As of the end of 2008, there were 10 permitted landfill sites in Northern Ireland24; and As of 2010, there were 32 operational landfill sites in the Republic of Ireland25. In 2011 this number dropped to 21 operational landfill sites.

The continued operation of these sites means that they remain a potential source of odour emissions and impacts if not optimally located and / or operated. Countries within the UK and Republic of Ireland have approached to landfill diversion in different ways. Scotland, for example, has promoted the ‘Zero Waste’ approach. This includes commitments such as: 



The Scottish Government will introduce a long term target of 70% recycling for all waste arising in Scotland by 2025, regardless of its source, based on improved data and supported by sector-specific programmes of work; and The Scottish Government will introduce progressive bans on the types of materials that may be disposed of in landfill, and associated support measures, to ensure that no resources with a value for reuse or recycling are sent to landfill by 2020.

Regulation The overall objective of the European Community (EC) Directive 1999/31/EC on the landfill of waste (the ‘Landfill Directive’) is to supplement the requirements of the Waste Framework Directive and prevent or reduce as far as possible the negative effects of landfilling on the environment as well as any resultant risk to human health. The Landfill Directive (Annex 1, Point 5) states that ‘Measures shall be taken to minimise nuisances and hazards arising from the landfill through…emissions of odours…’. This requirement has been transposed through national guidance for all EU member states. These requirements are imposed on an individual site through Conditions set out in the relevant Licence / Permit (as appropriate). Common Conditions are shown in Box 8. The Environment Agency, EPA, NIEA, and SEPA are the primary regulatory bodies for waste operations requiring a permit / licence (or a registered exemption) in the UK and the Republic of Ireland. Where a local authority detects a statutory nuisance from a waste site or receives a complaint of statutory nuisance arising from a waste site, it may need to discharge its duties. For example, in England, local authorities will need to consider the provisions of section 79(10)6 when discharging its duties under the Environmental Protection Act 1990. Section 79(10), EPA 1990, as amended and relevant to England and Wales, states:

22

Directive 2008/98/EC of the European Parliament and of the Council of 19 November 2008 on waste and repealing certain Directives Text with EEA relevance 23 http://www.sepa.org.uk/waste/waste_data/waste_site_information/landfill_sites__capacity.aspx 24 http://www.doeni.gov.uk/niea/websiteppcaug08.pdf 25 http://www.epa.ie/downloads/pubs/waste/stats/name,31964,en.html

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“A local authority shall not without the consent of the Secretary of State institute summary proceedings under this Part in respect of a nuisance falling within paragraph (b), (d), (e), (f) or (g) of subsection (1) above if proceedings in respect thereof might be instituted under Part I or under regulations under section 2 of the Pollution Prevention and Control Act 1999.” BOX 8. Common permit / license conditions: ’The licensee shall ensure that all operations on-site shall be carried out in a manner such that air emissions and/or odours do not result in significant impairment of, or significant interference with amenities or the environment beyond the site boundary.’ – EPA ‘Emissions from the activities shall be free from odour at levels likely to cause pollution outside the site, as perceived by an authorised officer of the Agency, unless the operator has used appropriate measures, including, but not limited to, those specified in an approved odour management plan, to prevent or where that is not practicable to minimise the odour.’ – Environment Agency ’All emissions to air from the permitted installation shall be free from offensive odour, as perceived by an authorised person, outside the site boundary.’ – SEPA ’All emissions to air from operations on the site shall be free from odour at levels as are likely to cause pollution of the environment or harm to human health or serious detriment to the amenity of the locality outside the site boundary, as perceived by an authorised officer of the Department.’ – NIEA

There are examples in the UK waste sector where a FIDOL approach has been used26. In relation to the New Earth composting facility at Sharpness, the Environment Agency approach states that relevant factors (to determine what further action to take) include:      

Six minutes of odour monitoring is statistically equivalent to one odour hour; Odour pollution identified at more than one receptor on one visit only counts as one overall exceedence in terms of the number of monitoring visits; We will conduct odour monitoring at weekends if we consider that to be necessary; We will be fair and reasonable with respect to essential works that could result in odour pollution; We will consider if an event is due to factors beyond the site's control; and Our position takes into account that sniff testing is subjective.

At that site, the following quantitative approach has been taken in relation to odour pollution: ‘Based on the evidence base we have built-up at this location, odour pollution is, in our view, an odour rated, by an "authorised officer", during a monitoring visit, that is 3 or above on the odour sniff scale of 1-5.’ ‘If we are satisfied that odour pollution has occurred then this will be treated as a permit breach and will be scored using our Compliance Classification Scheme (CCS). Repeated breaches will result in more formal regulatory action against NES.’ ‘We may suspend a permit if we consider site operation involves a risk of serious pollution. As a guide, at this stage we consider that four continuous days of odour pollution or six days in any 30 day period could be viewed as serious pollution at this location.’. 26

Environment Agency, Position statement: New Earth Solutions (NES) Sharpness 7 July 2011

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This approach has not been adopted at any landfill sites in the UK or the Republic of Ireland at the time of writing and it is not a recommendation of this guidance that it should be. The approach adopted at Sharpness is site specific and should not necessarily be considered applicable to other sites. The threshold for pollution and unacceptable odour will vary depending on many factors, including the character of the odour, how the odour is perceived and the sensitivity of the population. All FIDOL indicators should be considered (refer to Chapter 2 of this report). In addition, the actions taken by communities and their views should also be considered when assessing the impact of odours. It is therefore essential to gather this information. It may be possible to influence community views through effective engagement (refer to Chapter 11 of this report).

Limits Currently, in the UK there are no statutory numerical standards for assessing the acceptability of predicted odour impacts from quantitative odour impact assessments. On this basis, odour impact criteria are typically based upon guidance documents and research. The exposure criteria most accepted in the UK and the Republic of Ireland at present is given in terms of (concentration) European Odour Units as a 98th percentile (C98) of hourly averages. This allows 2% of the year when the impact may be above the limit criterion (175 hours). The notation for impact is therefore: C98, 1 hour X ouE/m3. It is generally recognised that odour from landfill sites is either ‘moderately offensive’ or ‘highly offensive’ and an impact criterion of C98, 1 hour 3 ouE/m3 or less is usually applied in the UK and the Republic of Ireland for purposes of assessment and regulation. As the impact criterion is based on the 98th percentile of predicted of hourly average concentrations over a year, such criteria apply only to locations where an individual’s exposure is likely to occur for prolonged periods of time i.e. residential properties. Where exposure is more transient i.e. roads, footpaths etc. the direct application of such criteria should be treated with caution and further consideration should be given to how the duration and frequency of exposure of the individual will influence the acceptability of the predicted impact.

Best available techniques / technologies Best available techniques (BAT) are required to be considered (under EC Directive 96/61) in order to avoid or reduce emissions resulting from certain installations (including landfill sites) and to reduce the impact on the environment as a whole. BAT takes into account the balance between the costs and environmental benefits of a particular activity.

Enforcement Where the regulator considers that permit / licence conditions have been breached, and initial investigations fail to achieve the required outcome (i.e. mitigation of the odour), or as a result of other considerations (i.e. where the environment agencies of the UK and the Republic of Ireland do not consider that the operator is being cooperative or a there is a high level of public interest), then more formal enforcement actions will be considered. A detailed description of Enforcement Options in the UK and the Republic of Ireland is provided in the second report published under Sniffer project ER31: Sniffer (2012) ER31 - Best practice for odour monitoring and control and community engagement at landfill sites. Final Report: Review of legal decisions regarding odour.

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An international perspective Despite progress made in diverting waste from landfill27, landfills remain the dominant method of municipal solid waste disposal worldwide. Figure 3 shows approximate figures for the methods of municipal solid waste disposal worldwide. ‘Dump’ refers to low technology open rubbish dumps rather than controlled, engineered landfill sites. ‘WTE’ refers to Waste to Energy, or Incineration of waste (with energy recovery).

Figure 3 – Total municipal solid waste disposed of worldwide (Source: World Bank Group28)

International legislative frameworks (i.e. outside the EU) will each be governed by their own national and / or regional guidance. Increasingly this is being driven by a requirement to address issues of Global Warming, with methane being a potent greenhouse gas (i.e. with a high global warming potential). Many non-EU countries have robust and mature regulatory regimes, including Australia, New Zealand, Japan, and the USA. Others are rapidly developing such as those in South Africa29, for example, as the benefits of collecting the (potentially valuable) landfill gas become apparent. Useful overviews of the regulatory framework outside the UK and the Republic of Ireland are provided in the following sources:  

Mahin T.D. (2001). Comparison of Different Approaches Used to Regulate Odors Around the World, Water Science and Technology, 44 (9), 87-102. Environment Agency (2002) Assessment of Community Responses to Odorous Emissions. R&D Technical Report P4-095/TR, July 2002;

27

http://epp.eurostat.ec.europa.eu/statistics_explained/index.php/Municipal_waste_statistics World Bank (March 2012). Urban Development Series – Knowledge Papers. What A Waste: A Global Review Of Solid Waste Management. Report 68135. 29 Petzer, G.H., Liebenberg-Enslin, H. Assessment and management of odour in South Africa using odour performance criteria. Airshed Planning Professionals (Pty) Ltd. 28

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

RWDI AIR Inc. (2005) Final Report Odour Management In British Columbia: Review And Recommendations. Report Ref: W05-1108, March 31, 2005

Some examples of guidance and research produced in countries outside the UK and the Republic of Ireland are shown in Table 2 below. Table 2 – Landfill odour: International examples Country

Guidance, research and standards

Australia

Environment agencies in Australian jurisdictions have established policy and regulatory requirements for sustainable waste management and landfill performance. These requirements are published as landfill management guidelines prepared by Australian States and Territories. Six of the eight Australian jurisdictions have adopted a classification scheme based on the type of waste permitted to be accepted at the landfill. However, the Northern Territory classification is based on landfill size, while South Australia has adopted a hybrid scheme which includes both size and leachate production potential. New South Wales (NSW) in particular has a very comprehensive policy for assessing and managing odour from stationary sources An example of jurisdictional guidance is: Environment Protection Authority South Australia. Environment Management of Landfill Facilities (municipal solid waste, and commercial and industrial general waste) 2007.

Germany

A part of the EU, Germany falls under the requirements of European policy and directives. Germany has a unique approach to managing odours that incorporates all of the FIDOL factors (frequency, intensity, duration, offensiveness, location; see Chapter 2 of this report). The frequency, duration and intensity are measured using the concept of ‘odour-hours’. VDI 3940 Part 2, 2006. Examples of relevant guidance are: Kommission Reinhaltung der Luft im VDI und DIN, 2000. Environmental meteorology, Emissions of gases, odors and dusts from diffuse sources, Landfills. 2000. VDI 3790, Part 2. VDI 3940 Part 2: Measurement of Odour Impact by Field Inspection Measurement of the Impact Frequency of Recognizable Odours Plume Measurement.

Japan

Japan has a strict policy on odour nuisance, regulated in accordance with The Offensive Odor Control Law (1972). This law regulates the emission of odour from industry.

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Table 3 – Landfill odour: International examples (cont.) Country

Guidance, research and standards

Malaysia

Landfill remains the primary method for wastes disposal by local authorities in Malaysia. Like the UK and the Republic of Ireland, there are many sites which are in local proximity to residential neighbourhoods for reasons of encroachment and limited land availability. Research has been completed in relation to landfill odours specific to the Malaysian situation on sites such as Ampar Tenang landfill site30.

New Zealand

New Zealand has a mature system for assessment and regulation of odorous facilities, including landfill sites. Typically odours are managed under the Resource Management Act 1991 (RMA)31. The key odour guidance document is: The Ministry for the Environment (June 2003). Good Practice Guide for Assessing and Managing Odour in New Zealand. Air Quality Report 36. ISBN: 0-478-24090-2

USA

The US EPA reports32 that each state must submit an application to EPA (a federal government agency) in order to receive approval for its program for the design and operation of disposal facilities. EPA assesses whether a state’s program is sufficient to ensure each landfill’s compliance with federal requirements. States may impose requirements that are more stringent than the federal requirements. EPA's technical design and operating criteria (regulations) for landfills include specific requirements for location, operation, design (liner, leachate collection, run off controls, etc.), groundwater monitoring, corrective action in the event of an environmental release, closing the landfill and post-closure care. Emissions to air (including a requirement for gas collection and control) are regulated under the Clean Air Act New Source Performance Standards and Emission Guidelines for municipal solid waste landfills. In relation to odour, as each state is free to legislate, there are very different standards although all must comply with the general requirements of the National Environmental Policy Act (1969). ASTM International (formerly known as the American Society for Testing and Materials , or ASTM) also provides International ‘voluntary consensus’ standards for odour, which provide an ‘odour intensity reference scale’33 and also methods for analysis and assessment34.

30

Sakawi Z., Mastura S., Jaafar, O & Mahmud, M (2011) Sensitive Receivers` Responses On Odour Annoyance Of A Neighbourhood Open Landfill Site. Journal of Applied Sciences in Environmental Sanitation, 6 (2): 191-199. 31 http://www.mfe.govt.nz/rma/index.html 32 http://www.epa.gov/region7/waste/solidwaste/waste_disposal.htm 33 ASTM E544 - 10 Standard Practices for Referencing Suprathreshold Odor Intensity 34 ASTM E679 - 04(2011) Standard Practice for Determination of Odor and Taste Thresholds By a Forced-Choice Ascending Concentration Series Method of Limits.

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Where this literature is also relevant to the UK and the Republic of Ireland, it has been referenced in the appropriate section. There are also reviews of current international standardisation elsewhere35 which provide a more detailed account of worldwide odour regulation.

35

Loriato A., Salvador N., Santos J., Moreira D., Neyval C (2012) Odour - A Vision On The Existing Regulation. Chemical Engineering Transactions VOL. 30, pp25-30

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5.

ODOUR SOURCES AND CHARACTERISTICS

source

control

pathway

receptor

The landfilling of non-hazardous putrescible wastes will result in the production of LFG which is generally produced through the breakdown of organic compounds in anaerobic conditions (in oxygen deprived conditions). LFG composition changes over the life of a landfill site as different stages in the degradation process are reached, however it is typically highly odorous36 (refer to Chapter 5 of this report). Data collected from seventy-nine sites37 identified 557 trace components that are emitted in bulk gases from UK landfills, some of which are highly odorous and detectable at the low part-per-billion (ppb) level. An example is methyl mercaptan (otherwise known as Methanethiol) which has a Level of distinct Odour Awareness (LOA) of 1.9ppb and a laboratory detection level significantly below this38. In addition to release of LFG from uncapped areas, faults in the landfill cap or event driven accidental releases, other potential sources of fugitive odour emission include:    

‘Fresh’ waste (waste tipping, compaction and fugitive emissions through daily cover); Leachate treatment and storage; Unburned gas from engines and flares; and Release beyond boundary from unlined waste body (i.e. migration).

Importantly with regard to the FIDOL factors, emissions will differ in terms of frequency of release, character and concentration / intensity.

Character and composition of odours from landfills The character and chemical composition of landfill odours vary due to a number of factors. The character and composition of odours is affected by the nature of the waste material received at the landfill, this affects initial waste odours and also the constituents of the landfill gas and leachate odours. The progression of the biodegradation process within the waste mass leads to changes in the composition of the landfill gas generated, for this reason the chemical composition of gases generated in parts of the landfill of different ages may vary significantly. The same principal applies to leachate odours. The table below provides a summary of the chemical composition and characteristics of different odour sources at landfills39.

36

Landfill Gas Industry Code of Practice: The Management of Landfill Gas (March 2012) Environment Agency (2002) Investigation of the Composition and Emissions of Trace Components in Landfill Gas. R&D Technical Report P1-438/TR. 38 Van Doorn, R., M. Ruijten and T. Van Harreveld. 2002. Guidance for the application of odor in chemical emergency response. Version 2.1, August 29, 2002. RIVM, The Netherlands. 39 Reproduced from: Applied Environmental Research Centre Ltd (October 2000) Guidance Manual for Landfill Managers on the Assessment and Control of Landfill Odours. 37

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Table 4 – Composition and characteristics of odour sources Odour source

Descriptors

Typical primary chemical odorants

Bottom of dustbin, rotten General domestic waste cabbage, fruity/citrus, acrid, sour, rotten, putrid. Sewage derivatives (faecal, sulphurous, rotten eggs) Other wastes

Food wastes (putrid, sour, fishy, rotten vegetables, rotten meat) Oils and fuels (oily acrid petrol like) Green wastes (woody, ammonia, earthy)

Esters (e.g. Butanoates), odours directly from volatilisation of chemicals from foods e.g. organic acids. Sewage derivatives (indoles, skatole, hydrogen sulphide, organic sulphides, ammonia) Food wastes (putrecine, cadaverine, amines, sulphides, ammonia) Oils and Fuels (aromatics, toluene, xylene) Green waste (terpenes, amines, aromatics, ammonia. Typified by esters (e.g. butanoates) and organosulphurs (e.g. methanethiol, DMS, DMDS), hydrocarbons, alcohols and turpenes (e.g. alkyl benzenes, butanols, limonene. Acetegenic wastes may be characterised by organic acids (e.g. butyric/butanoic acid)

Landfill gas (from freshly tipped wastes)

Sweet, sulphurous, fruity, citrusy, gassy, sickly, pungent

Landfill gas (from older methanogenic wastes)

Fruity, citrusy, gassy, sickly, pungent (less sweet and sulphurous than above)

Typified by limonene and hydrocarbons (e.g. alkyl benzenes etc) and less sulphurous compounds.

Leachate (young, poorly decomposed leachate)

Extremely sweet, sugary, pungent food, like, sulphurous.

Organic acids (e.g. butyric/butanoic acid), aromatics, alcohols, hydrocarbons and sulphur compounds.

Leachate (mature well decomposed leachate)

Mild, fuel like, oily, ammonia (if pH is high). Farm yard like.

Aromatics and hydrocarbons

Combustion system exhausts (from inefficient burning)

Burnt odour. Very sweet, burnt, toffee like smell.

Unburned hydrocarbons and nitrogen oxides

Sources Table 5 below details the typical sources of odours found at landfills40. Not all of these sources have the potential to cause problems, as they may be localised or infrequent. Similarly management and operational measures at well run sites provide effective tools for mitigation (refer to Chapter 7).

40

Environmental Protection Agency 2003. Landfill Manuals: Landfill Monitoring. 2nd Edition.

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Table 5 – Landfill odour sources Source

Mechanism of release

Waste reception

Fugitive release from refuse collection vehicles during delivery or from bulking stations.

Tipping area / working face

Fugitive release from waste tipped and fugitive release from tipping face (uncovered areas)

Daily cover

Fugitive release through daily cover.

Intermediate cover

Fugitive release through intermediate cover (a thicker layer of daily cover where tipping will not occur for seven days of more).

Temporarily capped areas

Fugitive release through surface caused by capping not Construction Quality Assured (CQA), insufficient depth, cracks, and/or insufficient gas extraction rate.

Permanently capped areas

Fugitive release through surface cracks/tears as a result of settlement and/or insufficient gas extraction rate.

Leachate wells

Fugitive release as a result of cracks around well/liner interface and/or insufficient gas extraction rate

Gas collection / monitoring infrastructure

Fugitive release as a result of cracks around well/liner interface and/or insufficient gas extraction rate

Leachate treatment plant

Release from surface of treatment/storage lagoons and fugitive release from enclosed treatment facilities.

Historic landfills and unlined cells

These so called ‘dilute and disperse’ landfill sites will have no gas collection and any generated LFG will therefore be released directly from the surface.

In the sections below, detail on these primary sources, likely variation, and potential release (emission) points is provided. Waste reception Odour emissions can occur prior to the delivery of waste to the site by the collection vehicle. Waste collection schemes in the UK may occur either once a week or once a fortnight. Prior to the waste being collected for disposal, the waste may already be seven to 14 days old and microbiological breakdown of materials (and the production of odorous compounds) may already be occurring, particularly in warm weather conditions. Once collected from residential and commercial properties, putrescible wastes may be delivered to transfer stations for bulking up and onward movement to a landfill for disposal. The waste may be stored at the waste transfer station for some days before final despatch to landfill, e.g. Bank Holiday period. Under these conditions the microbiological decomposition processes already commenced in the collection receptacle (i.e. bin) will develop further and ensure that odorous degradation products will be present during subsequent transport to landfill.

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Transport of odorous decaying wastes through residential areas on route to the landfill will create an odour but it is more likely that parked vehicles (for example waiting for a site to open or queuing at the site weighbridge) will have the potential to cause odour issues dependent upon site layout. Tipping areas The specific odour emission rate (i.e. ouE/m2/s) from tipping areas has been found to be the highest of all sources on the landfill41. This is a result of:  

Uncontained release; and Agitation of the waste.

The odorous compounds released from this area also differs from that of landfill gas in that it typically contains less sulphurous compounds and may even contain trace compounds which would be regarded as ‘pleasant’ when experienced outside the odorous mix, such as limonene (with a characteristic lemon smell) and pinene (smelling of pine)42, 43. This is of relevance when considering FIDOL factors.

Photo 2 – Compaction in the Tipping Area (photo courtesy of The Environment Agency)

Although the tipping areas may be areas of high emission, their area is typically small and therefore will be more significant sources on smaller landfill sites where their contribution is relatively higher.

41

Stretch, D., Laister, G., Strachan, L., Saner, M., (2001). Odour trails from landfill sites. Sardinia 2001, Cagliari, Italy. 42 Chiriac, R., Carre, J., Perrodin, Y., Fine, L., Letoffe, J. 2007. Characterisation of VOCs emitted by open cells receiving municipal solid waste. Journal of Hazardous Materials 149 (2007) pp249-263. 43 Allen, Braithwaite & Hills (1997) Trace Organic Compounds in Landfill Gas at Seven U.K. Waste Disposal Sites. Environ. Sci. Technol. 1997, 31, 1054-1061

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Landfill gas (capped areas) Twelve trace components have been found to have the greatest potential to contribute significantly to the odour of landfill gas and these are listed below44:            

Hydrogen sulphide; Methanethiol (methyl mercaptan); Butyric acid; Ethanal; Carbon disulphide; Ethyl butyrate; 1-propanethiol; Dimethyl disulphide; Ethanethiol (ethyl mercaptan); 1-butanethiol; 1-pentene; and Dimethyl sulphide.

The odour concentration of raw landfill gas can vary considerably dependent on source. However, it is typically very high. A range of published values for the concentration of landfill gas are presented below: Table 6 – LFG concentration (ouE/m3) Publication

Reported value

Frechen, F.B., (1995), A New Model for Estimation of Odour Emissions from Landfill and Composting Facilities, Proceedings of the Fifth International Landfill Symposium, Sardinia

200,000

Dr P Longhurst (March 2007) Principles of Landfill Odour Emission and Control Understanding, prioritising and controlling emissions. AWE International 10th Edition. Dr Phil Longhurst (March 2007)

400,000 - 1,200,000

T. Pagè, A. Narjoux, C. Guy, R. F. Caron, B. Fècil, (2008) Odours & Voc impact Evaluation Of Three Categories of Landfills, Chemical Engineering Transactions.

41,000 - 2,151,000

GasSim v2 (Golder Associates). Default Odour Concentrations. Cranfield University - Brogborough Landfill Report (1998) Applied Environmental Research Centre Ltd (October 2000) Guidance Manual for Landfill Managers on the Assessment and Control of Landfill Odours.

50,000 - 250,000 107,648 - 1,367,680 125,864

What is most notable about these data sets is that the variability in reported values is very large. There is at least an order of magnitude within most of the available studies and even greater

44

Environment Agency (2002) Investigation of the Composition and Emissions of Trace Components in Landfill Gas. R&D Technical Report P1-438/TR.

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variation between studies. However, this is to be expected given the measured variability of trace concentrations within landfill gas45. Under normal operation, a permanently capped area of a site with effective extraction is not expected to be a source of significant fugitive emission. However, settlement and activity may result in the localised failure of this containment. It has been broadly reported46,47 that the concentration of trace compounds within landfill gas is changing through time. This is thought to result from changes in the waste breakdown and composition, particularly diversion of materials (such as metals) destined for recycling. In particular, it is reported that the average concentration of hydrogen sulphide is increasing48, and this may have implications for odour control in the UK and the Republic of Ireland. Leachate treatment and LFG combustion systems Leachate is formed by the hydrolysis of large molecules. Under the action of anaerobic processes within the waste mass, the degradation products from hydrolysis undergo further breakdown by acetogenesis. Acetogenesis produces volatile fatty acids (VFAs). Under the anaerobic conditions existing at this stage, oxidised materials present as, for example sulphates, will be reduced to sulphides, producing another series of odorous compounds. The odour characteristics of leachate therefore vary with its age. Notwithstanding the above, leachate treatment and LFG combustion sources are unlikely to be significant in terms of offsite odour impacts on a licensed / permitted landfill site in the UK and the Republic of Ireland unless they are:    

In close proximity to receptors; In open lagoons (of large area); Aerated (thus promoting transfer of volatile compounds to air); or Stagnant.

LFG combustion systems Odour emissions from a correctly maintained LFG combustion system are likely to be negligible given the combustion temperatures involved. Regular testing of landfill gas engines and flares is a requirement of all permits / licences and this will highlight any sources of incomplete combustion.

45

Environment Agency (2002) Investigation of the Composition and Emissions of Trace Components in Landfill Gas. R&D Technical Report P1-438/TR. 46 Landfill Gas Industry Code of Practice: The Management of Landfill Gas (March 2012) 47 Parker, T and Pointer, P (2008) Trends and Assessment of Priority Trace Components. Proceedings Waste 2008. 48 Parker and Pointer reported an increase in average concentration of hydrogen sulphide in LFG from 3 3 85mg/m to 160mg/m in the period between 2002 and 2007.

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CASE STUDY 1: CONTAINMENT → EXTRACTION → TREATMENT → COMMUNICATION Country: England Annual waste imports: 500,000 – 700,000 tonnes non-hazardous wastes (including municipal and commercial) Approximate age of landfill: c 20 years Distance to closest residential receptors: within 250m Landfill gas utilisation: c 6MWe installed capacity. Odour constraints The location of this site and quantity of wastes received means that it has a high potential for odour issues. This has been exacerbated by the high concentration of odorous trace gasses in the generated landfill gas. Solutions adopted The operator has put in place a multitude of procedures for mitigation of existing issues and prevention of issues in the future. These are encompassed in the Odour Management Plan for the site, which has been agreed by the Environment Agency. The measures have been reported by the Environment Agency and operator as being highly successful. Mitigation put in place includes:     

A commitment to cap any phases within 6 months of completion; Installation of between 50 and 100 additional temporary and permanent wells; Additional capping of flanks with geomembrane; Odour neutralisers (boundary sprays); and Removal of hydrogen sulphide prior to utilisation.

These solutions have resulted in an optimal containment → extraction → treatment solution which has significantly reduced complaints. Importantly, the operator has been transparent in relation to the problems and solutions at the site and has a very strong commitment towards communication and community involvement. This includes an operator web page to update the local community. Summary: Lessons learned This site is an example of where, even under the most difficult conditions (i.e. large site, close to receptors and odorous LFG), mitigation can be effective when the operator is committed to addressing existing issues (and preventing future ones). The EA has used this example as best practice to work with industry; inform local communities and improve the local amenity. ‘The implementation of a robust OMP has brought real benefit in reducing the number of complaints. We would strongly recommend that other operators adopted such measures’. – Site operator ‘Site operators must engage with local communities to improve understanding and promote effective communications.’  Environment Agency

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Library emissions data The LFG concentration data presented in Table 6 provides no indication of emissions from the landfill, other than that they will be significant if LFG is released in any significant quantity. Published, peer reviewed literature presenting specific odour emission rates from landfill sites as currently operated in the UK and the Republic of Ireland (for example within the last 3 years) is not available. Such data would reflect current operational management techniques as well as the changing composition of LFG. Indeed, there is currently little published data available of any age in relation to specific emission rates from landfill sites anywhere in the world. The values presented in Table 7 below related to uncovered wastes (i.e. those on the active cell). Table 7 – Specific emission rates from landfill sites: Uncovered wastes Area of landfill

Specific emission rate (ouE/m2/h) Lower value

Upper value

Deposition area A

2000

15000

Deposition area B

14400

43200

Deposition area C

---

117720 (measured)

Deposition area D

---

1800 (measured)

Deposition area H

3600

90000

Deposition area F

468

18432

Exposed / uncovered waste B

3600

14400

Exposed / uncovered waste F

9360

19440

A

Frechen, F.B., (1995), A New Model for Estimation of Odour Emissions from Landfill and Composting Facilities, Proceedings of the Fifth International Landfill Symposium, Sardinia49 B

Dr P Longhurst (March 2007) Principles of Landfill Odour Emission and Control Understanding, prioritising and controlling emissions. AWE International 10th Edition. Dr Phil Longhurst (March 2007) C

Li, X.Z., (2004). Odour impact and control at a landfill site in Hong Kong. East Asia Workshop on Odor Measurement and Control Review. Office of Odor, Noise and Vibration, Environmental Management Bureau, Ministry of the Environment, Government of Japan. D

Romain, A., Delva, J., Nicolas, J. 2008. Complementary approaches to measure environmental odours emitted by landfill areas. Sensors and Actuators B 131 (2008) pp18-23. F

Odotech, (2001). Caracterisation des emissions atmospheriques et evaluation de l impact-odeur du lieu d’enfouissement sanitaire de la re´gie intermunicipale Argenteuil Deux Montagnes (Atmospheric emissions characterization and odour impact assessment of Argenteuil Deux Montagnes landfill area). Montreal, Canada, Odotech Inc.

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2

Specific Emission rates for the work published by Frechen (1995) have been converted from the ou/m /h 2 presented in the original research to the EN13725 compliant ou E/m /h using a factor of 2:1.

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The values presented in Table 8 below relate to covered wastes (i.e. those on the active cell under daily cover or capped areas). Table 8 – Specific emission rates from landfill sites: Covered wastes Area of landfill

Specific emission rate (ouE/m2/h) Lower value

Upper value

Daily cover A

1000

3000

Capped A

300

1250

Capped B

0

10800

Capped H

216

6840

Capped G

0

0

A

Frechen, F.B., (1995), A New Model for Estimation of Odour Emissions from Landfill and Composting Facilities, Proceedings of the Fifth International Landfill Symposium, Sardinia50 B

Dr P Longhurst (March 2007) Principles of Landfill Odour Emission and Control Understanding, prioritising and controlling emissions. AWE International 10th Edition. Dr Phil Longhurst (March 2007) G

Kommission Reinhaltung der Luft im VDI und DIN, 2000. Environmental meteorology, Emissions of gases, odors and dusts from diffuse sources, Landfills. 2000. VDI 3790, Part 2. H

Page, Lagier & Chereau (2005) Comparisons of French and Canadian Landfill Odour Impact Results. Proceedings of the Tenth International Landfill Symposium, Sardinia

A more generic landfill emission rate was found in relation to Italian landfill sites by researchers in Milan51. The research resulted in an ‘average’ landfill odour emission factor of 5.5 ± 3.4 ouE/m2/s (7560 – 32040 ouE/m2/h). It must be noted that information regarding the operational management at these Italian landfills is not available, although the author states that ‘it may be considered that the average LFG collection and extraction efficiency in the monitored landfills is around 50%’. This collection efficiency is significantly below that typically found at regulated landfill sites in the UK and the Republic of Ireland. As with the concentration data for LFG, what is most notable about the data set is that the variability is very large, particularly for freshly tipped wastes. There is at least an order of magnitude within most of the available studies and even greater variation between studies.

50

2

Specific Emission rates for the work published by Frechen (1995) have been converted from the ou/m /h 2 presented in the original research to the EN13725 compliant ouE/m /h using a factor of 2:1. 51 Sironi, S., Capelli, L., Centola, P., Del Rosso, R., Il Grande, M. 2005. Odour emission factors for assessment and prediction of Italian landfills odour impact. Atmospheric Environment 39 (2005) pp5387-5394.

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CASE STUDY 2: EFFECTIVE CAPPING Country: England Annual waste imports: 300,000 – 400,000 tonnes non-hazardous wastes (including municipal and commercial) Approximate age of landfill: c 15 years Distance to closest residential receptors: within 300m Landfill gas utilisation: c 5MWe installed capacity. Odour constraints Although this site has no obvious characteristics which would indicate that the risk of potential odour emissions is higher than any other site, complaints were received. The Environment Agency considered that the causes of the issue were related to the progression of capping and also the integrity of the capped areas. Solutions adopted The operator has put in place more robust systems of defect identification and progressive capping. The site operates in accordance with an Odour Management Plan, which has been agreed by the Environment Agency. Mitigation measures put in place include:     

Installation of large numbers of additional landfill gas extraction wells; Landfill gas wells now installed, either new or re-drills, on a more regular basis; Sealing of leachate wells; Temporary capping (geomembrane) all areas of landfill waste which are not to be tipped over for a few months; Regular FID survey, with (at least) annual formal testing in accordance with EA LFTGN07.

These solutions have resulted in effective containment which has significantly reduced complaints and also allowed more effective gas management. Summary: Lessons learned This was a site where it was considered that best practice was being applied. However, more regular re-assessment of the containment systems (i.e. whether capping should be progressed and whether the integrity of the existing cap was optimal) has resulted in a significant reduction in complaints over time. Staged improvement was balanced against resident expectation. ‘Be clear with them [residents] what timescale you are looking at to resolve the odour issues – they need to know it will not be an immediate resolution.’  Environment Agency ‘Installation of temporary capping over parts of the site which will not be tipped on for a number of months really works in reducing / eliminating landfill gas odour off site.’  Environment Agency

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6.

CAUSES OF ODOUR EMISSION FROM LANDFILLS

source

control

pathway

receptor

Despite knowing the sources of odorous emissions on landfill sites (as discussed in Chapter 5), emissions will vary through time for the reasons described below.

Accepted wastes The potential for odour emissions throughout the landfilling cycle will begin with the waste itself, particularly:   

Hedonic tone of the received waste (odours during tipping); State of decomposition (odours during tipping and in active cell); and Breakdown and composition of waste deposited (i.e. potential to generate LFG, and how quickly).

Emission variation: Timescales The potential for odorous releases during standard operation will not remain constant, but will vary both throughout the operational life of the landfill and also on a much shorter timescale. Long-term variation A landfill is a dynamic system, subject to changes over the duration of filling which have the potential to lead to variation in odour emission, such as:    

Filling progression; Tonnage of waste deposited; Breakdown and composition of waste deposited; and Capping and gas collection system development.

These long-term variables will result in a change to the gas production and collection profile as well as the distance from the working areas of any landfill to receptors. Strategies such as the Scotland ‘Zero Waste’ policy, for example, will both reduce the tonnage of waste deposited and its breakdown and composition. This in turn will change the requirements for capping and gas collection. Seasonal variation Odour emissions due to seasonal variation are likely to be a result of the ambient temperature and its effect on the degradation rate of the tipped waste. Research has been completed in Sweden in relation to the rate of methane oxidation in cover soils and this has been shown to reduce markedly (by 85%) in the winter. Although this is likely to be more marked due to the Scandinavian climate, similar effects are likely to be of relevance in the UK and the Republic of Ireland during frosty conditions. The Met Office reports that ground frost occurs on average:

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 

In northern Scotland: approximately 80 days per year on the coast and over 135 days on high ground; to In southwest England: Most coastal locations have between 35 and 60 days per year, but in some eastern inland districts this rises to over 100 days per year.

The importance of seasonal variation in relation to odour complaints is more likely to be masked in the UK and the Republic of Ireland by receptor behaviour patterns (i.e. people are more likely to be outdoors in the summer).

Figure 4 – UK seasonal temperature profile52 Diurnal variation Landfill sites in the UK and the Republic of Ireland are not filled on a continuous basis and this will lead to diurnal fluctuations in odour emission. Typically the first wastes will be received in the morning and are added to over the course of the working day, with ‘daily cover’ progressively applied and completed prior to closure of the site for the day53. The diurnal emission profile (described above) may be further complicated by the fact that the most stable atmospheric conditions (i.e. those which inhibit dispersion) in the UK and the Republic of Ireland are experienced during the morning and evening periods (see below)

Landfill configuration Effective management of odour emissions may be challenged by the configuration of the landfill. For example, in deep-quarry landfills there may be a requirement for a system of filling where progression over time is vertical (rather than lateral). This is to prevent the need for high and steep 52

UK Meteorological Office statistics, 1951 – 2011. Svensson, B (1997) Seasonal and Diurnal Methane Emissions from a Landfill and Their Regulation By Methane Oxidation. Waste Management Resource. January 1997 15: 33-54. 53

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banks between the filled and unfilled parts of the site as these may develop stability problems. In order to prevent problems of perched leachate, this may mean that the majority of the site cannot be permanently capped. It would be normal to apply intermediate cover to areas which are not due to be filled immediately, with a proportion of this cover removed before tipping takes place. More exaggerated settlement will also result in additional strain on the gas collection system pipe work. If horizontal wells become buried under many lifts of waste, then they are subject to failure due to blockage or crushing, and will need to be replaced with a new well at a shallower depth. This makes them of limited use in controlling migration from deep parts of the site.

Atmospheric factors The emission and subsequent impact of odours from landfills is influenced by the following meteorological parameters54:        

Wind speed; Wind direction; Turbulence; Air pressure, including changes in air pressure (especially for covered landfills); Air temperature; Atmospheric humidity; Precipitation; and Solar radiation.

Of these, changes in atmospheric pressure will be of most relevance to the release of LFG from the waste body55, and temperature / humidity will determine the volatilisation from tipped wastes (and the degree of degradation of these wastes prior to tipping).

BOX 9. ‘When the barometric pressure is falling or is below the norm for that area, methane fluxes can be higher than normal, and vice versa. Ideally, surveys should be conducted when barometric pressure is at neither extreme. Meteorological effects can be self-cancelling because low barometric pressure is usually accompanied by rainfall, which reduces the permeability of the soil and can reduce surface emissions.’ – Environment Agency LFTGN07

The wind speed and direction will determine the potential for exposure of receptors to an emission of a given concentration (i.e. whether it has been diluted and dispersed prior to reaching the receptor). Air temperature and rainfall will also affect receptor behaviour, particularly in relation to the use of recreational areas such as gardens and parks.

54

VDI 3790 (December 2000) Environmental meteorology: Emissions of gases, odors and dusts from diffuse sources Landfills 55 Czepiel, P.M., Shorter, J.H., Mosher, B., Allwine, E., McManus, J.B., Harriss, R.C., Kolb, C.E., Lamb, B.K. 2003. The influence of atmospheric pressure on landfill methane emissions. Waste Management 23 (2003) pp593-598

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Accidents and consequences In a dynamic working environment such as a landfill site there will be events which are unforeseen and unintentional. Some of these events have the potential to lead to odorous releases. Damage to engineered containment (cap and liner) Causes of accidental damage to engineered containment include the following56:    

Differential settlement of the waste mass; Fire (discussed in the following section); Operator / engineer error; and Stone puncture resulting from traffic movement over empty cells57.

Appropriate installation methods, particularly for plastic caps58 including Construction Quality Assurance (CQA), will minimise the risk of defects at the installation stage. It could be argued that differential settlement of the waste mass is something which could be foreseen (and planned for in any ongoing maintenance regime), however there will always be circumstances where waste settles more (or less than expected) and it is this uncertainty which can result in damage on occasion. Fire Subsurface landfill fires are caused when a source of ignition (such as a lit cigarette, chemical or biological activity) gets buried within the waste mass and oxygen is present. The landfill subsurface fire Industry Code of Practice59 describes that potential causes of oxygen ingress are a result of the following:  



  

Over abstraction is often used to control gas migration or for odour control. This can cause an excess of oxygen to be drawn into a landfill; As the waste settles, seals around penetrations into the landfill, pipe connections, and the landfill cap itself can all potentially warp and crack. These are all potential sources of oxygen ingress into the waste; Anecdotally, the ingress of oxygen into a landfill can be associated with the leachate drainage system. If leachate collection pipes and drainage systems are not fully under the leachate, then air can travel along the leachate system back into the waste; Lowering the leachate levels can provide an additional suction pressure into capped waste, while a cycle of rising and lowering leachate levels can act as a bellows to the waste mass; The use of shredded wood cover has been suggested as a pathway for oxygen to migrate along and therefore subsurface fires to spread; and The presence of water can be important in reducing pathways for oxygen ingress because dry waste is more permeable than wet waste.

In the short term, the presence of a subsurface fire may result in a requirement to isolate an area from the gas collection system. The cap may also be damaged, either through the heat 56

McQuade, S.J. and Needham, A.D. (1999). Geomembrane liner defects – causes, frequency and avoidance. Geotechnical Engineering, Proc. Inst. Civ. Eng., 137, 203-213. 57 Brachman, R.W.I. and Sabir, A. (2010) Geomembrane puncture and strains from stones in an underlying clay layer. Geotextiles and Geomembranes. Volume 28, Issue 4, August 2010, pp 335–343. 58 Environment Agency (2009) LFE5 - Using geomembranes in landfill engineering. Ref: GEHO0409BPNH-E-E 59 C&P Environmental Ltd (June 2008) Management and Prevention of Sub-Surface fires - Industry Code of Practice. Edition 1.

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(temperatures of 200○C have been recorded at the landfill surface) or through deliberate excavation in an attempt to extinguish the fire (with leachate, nitrogen or similar). Damage to gas collection system Gas extraction wells are often a key ‘risk’ feature with regard to potential fugitive emissions of LFG. Key factors include60:   

Poor sealing around the vertical well head; Poor condensate removal; and Inadequate extraction vacuum.

Condensate has the potential to block the passage of gas and cause ‘slugging’. Slugging is caused by differential pressure building across a liquid blockage, allowing gas to pass through only intermittently (causing variable suction and flow on the gas system) or preventing extraction. Condensate traps and good design practices will prevent condensate drainage issues. The causes of accidental damage to the Gas Collection System (including pipes and manifolds) are similar to those responsible for damage to engineered containment, and include the following61:   

Differential settlement of the waste mass; Fire (discussed in the following section); and Damage from traffic collisions.

Damage to the gas collection system can be extremely important with regards to odour emissions, not only because gas will be able to escape fugitively, but also because parts of the system may need to be disconnected whilst the damage is repaired (see below).

Planned operations As landfilling operations progress across a site, filled areas will be capped and gas collection installed. Dependent upon the layout of the system, it is likely that it will be necessary to disconnect part (or all) of the gas collection system and interrupt extraction. This may be necessary to allow the drilling of collection wells or connection to manifolds and mains for example. This has the potential to increase the chances of fugitive release of LFG from the site. Several operators have found it useful to inform the regulator and community prior to such events. This proactive communication has been found to prevent complaints (see Chapter 10).

60

Casey, J.W., Sheridan, B.A., Henry, M., Reynolds, K. 2008. Effective tools for Managing odours from landfill facilities in Ireland. International Conference on Environmental Odour Monitoring and Control, July 2008 61 McQuade, S.J. and Needham, A.D. (1999). Geomembrane liner defects – causes, frequency and avoidance. Geotechnical Engineering, Proc. Inst. Civ. Eng., 137, 203-213.

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CASE STUDY 3: EVENT RESPONSE Country: England Annual waste imports: 400,000 – 500,000 tonnes non-hazardous wastes (including municipal and commercial) Approximate age of landfill: c 15 years Distance to closest residential receptors: within 200m Landfill gas utilisation: c 5MWe installed capacity. Odour constraints This site had operated without significant odour incident for 8 years before a significant and rapid elevation in levels of H2S (localised results of >1g/m3) resulted in a significant elevation in the potential for odour impacts. Isolated events on site which would have previously been innocuous were now a potential concern for both the health of on-site personnel and amenity of local receptors. The issue was investigated and found to be isolated to one cell in particular and attributed to a particular (high sulphur) waste stream. Solutions adopted The rapid actions of the operator significantly reduced the number of complaints that would have been received if there had been less willingness to dedicate all available resources to containing and then mitigating the issue. The measures were completed within 8 weeks. The measures put in place by the operator included:   

Immediate capping of the worst affected cell; Installation of pin wells, with spacings 2 years

Temporary (sacrificial) gas wells. Installed in areas where they may be prone to damage or expected to be made redundant within a short period, typically of smaller diameter than permanent wells.

LFG is produced at different rates through the waste mass because waste is not homogeneous. LFG abstraction wells within the landfill site must be individually set up and operated (balanced) to maximise the sustainable quantity of gas abstracted from the site. Excessive suction applied to a gas well can draw excessive air in through the cap, infrastructure or sides of the site. The oxygen from this air is then used by aerobic microbes to produce carbon dioxide in preference to methane therefore reducing the calorific value of the gas and potentially turning the waste aerobic which can lead to subterranean landfill fires. Low calorific (Lo Cal) value flares allow the safe and efficient degassing of old landfill sites or sites with low quality gas. Lo Cal high temperature flares can provide greater gas control during the latter phases of a site, while the high temperature prevents pollution issues. Lo Cal high temperature combustion is necessary on more and more sites due to higher standards of aftercare being required, falling gas volumes and lower gas concentration83. This will increasingly become the case as governments adopt strategies such as Zero Waste.

82

Landfill Gas Industry Code of Practice: The Management of Landfill Gas (March 2012). Table 7-3 Selection of Temporary LFG Control Measures 83 Landfill Gas Industry Code of Practice: The Management of Landfill Gas (March 2012)

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Photo 3 – Gas collection system wellhead (image by SLR Consulting)

Leachate management Sector guidance is available for landfill leachate treatment84 which describes best practice (Best available techniques / technologies (BAT)) which should be used by a permitted site. This guidance is summarised in Box 14. In general, a site with covered leachate storage is unlikely to have a significant emission from this source. Even open lagoons may not be a notable source of offsite odour if quiescent and a sufficient distance from receptors (this distance will depend on the size of lagoon and emission rate of the leachate). There have been examples lagoons have stagnated and sediments become anaerobic and this should be avoided.

84

EHSNI / SEPA / Environment Agency (2007) Guidance for the Treatment of Landfill Leachate. Sector Guidance Note IPPC S5.03

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BOX 14. Indicative BAT requirements for odour control (Sector Guidance Note IPPC S5.03) 1. The requirements for odour control will be installation specific and depend on the sources and nature of the potential odour. 2. Odour emission from contained and fugitive sources shall be free from offensive odour at any location at or beyond the site boundary. 3. Any odour abatement equipment shall be maintained to ensure that adequate odour removal efficiency is retained throughout its operational life. 4. Where odour can be contained, for example within buildings, the operator should maintain the containment and manage the operations to prevent its release at all times. 5. Where odour releases are expected to be acknowledged in the permit (i.e. contained and treated prior to discharge or discharged for atmospheric dispersion). 6. Where odour generating activities take place in the open, (or potentially odorous materials are stored outside) a high level of management control and use of best practice will be expected. 7. Where an installation releases odours but has a low environmental impact by virtue of its remoteness from sensitive receptors, it is expected that the operator will work towards achieving the standards described in this note, but the timescales allowed to achieve this might be adjusted according to the perceived risk. 8. The objective is to prevent emissions of odorous releases that are offensive and detectable beyond the site boundary. This may be judged by the likelihood of complaints. However, the lack of complaints should not necessarily imply the absence of an odour problem. 9. Assessment of odour impact should cover a range of reasonably foreseeable odour generation and receptor exposure scenarios, including emergency events and the effect of different mitigation options. 10. The significance of releases from leachates from relatively-recently emplaced wastes should be assessed by use of pilot-scale stripping trials, involving collection of gas samples for formal testing using odour panels. Where such odour effects occur, biofilter,s e.g. brushwood or heather filters, or equivalent, should be employed. 11. Confined spaces in leachate treatment plants shall be constructed and equipped in such a way as to prevent the formation of an explosive atmosphere. If it is not possible to prevent the formation of an explosive atmosphere, the ignition of explosive atmospheres shall be prevented by additional protective means, e.g. ventilation or permanent installation of gas warning devices to initiate emergency procedures. Maintenance (LFG collection and cap): Identification of defects A defect is defined as a failure or weakness in the containment or extraction systems that allow the passage of volumes of gas, air or water into or out of the system and therefore affects the systems performance. Defects can occur during the build process, through design issues (these should be picked up during the commissioning stage), through unplanned or differential settlement or through post-installation impact damage. Good design, installation, CQA and operational practice will minimise the potential for defects to occur.

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Defect identification can occur through the following activities:    

visual observation; odour identification; measurement of gas escape with appropriate equipment; and identification from balancing data analysis.

Defects can occur at any time during the operation of the site, therefore defect identification and repair is a continual and on-going process. The more frequent the defect sweeps and more rapid the defect repairs, then the better will be the gas management and therefore gas collection. It is good practice to have a Defect Management System and this should be considered BAT for odour control. BOX 15. Environment Agency LFTGN03 The minimum requirements for the validation of collection and treatment systems in order to demonstrate the integrity of the installed measures at the time of installation (i.e. not to demonstrate on-going performance) are as follows:  

  

 

Visual inspection of pipework prior to covering; Functional testing of the integrity of pipework (e.g. pressure testing) to an appropriate standard (and commensurate with the function of the pipework as required by the design) to verify competence of the pipework and joints; Supervising and recording the installation of collection wells; Surveying the location of pipework, collection wells and other installed control measures; Establishing that collection pipework and wells have been constructed in accordance with the design, e.g. verifying the correct pipe diameters/well size, well depth, pipe gradients and locations; Checking that all elements of the collection systems and treatment plant meet the design and the objectives set out in the CQA plan; and Details of plant commissioning and trials.

Provided that defects are sought, detected and repaired on an on-going basis, significant losses of LFG through the cap are unlikely. The same application of good gas management should enable a similar process to apply for most instances of lateral migration. It is possible to use methane entrained in the leachate to calculate losses in that route and in a similar manner the slippage through utilisation. Using all this easily measured and calculated data, under the auspices of good gas management, should enable a good assessment of total gas capture to be generated for each site. Restoration soils Once a landfill cell has been capped and the permanent gas collection system is in place, the operator will have a responsibility (typically through the requirements of the planning permission for a site) to restore the filled area. The restoration of a site will first require application of restoration soils over the cap. These restoration soils will then be vegetated as appropriate. However, the depth of soils and type of vegetation must be considered to prevent future damage to the cap. Although this may not present an immediate risk in relation to odour release, it could have the potential to alter the balancing of the gas collection system through reducing cap integrity.

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The results of a 1997 study conducted by Forest Research85 of woodland planted on the Waterford landfill site showed that: 1. The incidence of roots reaching the soil / cap interface was greatest where the soil cover was thin (less than 0.6 metres); 2. No roots were observed at the soil / cap interface in 1997 where the soil cover was at its maximum of 1.3 m thick; and 3. Alder, the fastest growing species, had the highest root density at the soil / cap interface than the other species and exhibited the maximum depth of root penetration into the cap of 0.3m (at the time of publication). Odour masking and counteractants Masking agents and counteractants are gas phase odour treatment methods, in which an odour treatment agent is mixed directly with the foul airflow. This is usually done by atomising and then spraying a liquid treatment agent. At landfills such systems are typically installed at the site boundary, with the product misted via atomisers. The products available can be classified as follows86. 

  

Masking agents are mixtures of aromatic oils that cover up an objectionable odour with a more desirable one. The resultant odour is inherently more intense than the original odour, but arguably the character of the odour becomes less offensive; Chemical counteractants are mixtures of aromatic oils that cancel or neutralise odour and reduce the intensity; Digestive deodorants contain bacteria or enzymes that eliminate odour through biochemical digestive processes; and Chemical scavengers are chemicals that can be added to materials to react with the potentially odorous substances. Use includes removal of sulphur from spills of crude oil.

Masking agents may have a public relations benefit in the short-term, communicating that some short-term action has been undertaken in acute conflict situations. In the long-term they may be counterproductive, however, as the masking odour becomes associated with the cause of the annoyance. As the intensity of the masking odour is higher than that of the original odour, it may increase the magnitude of the problem, rather than reduce it. Box 16 provides guidance from each of the regulators in relation to the use of masking agents. The examples are taken from guidance not specific to solid waste disposal. For the reasons the previous box, there should be no BAT requirement for the use of odour counteractants / masking agents.

85

Reported in: Department for Communities and Local Government (May 2008) Woodland Establishment on Landfill Sites - Ten Years of Research. 86 SEPA. Odour guidance 2010 (Version 1, January 2010)

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BOX 16. Masking Agents: Regulator Views ‘Masking agents may have a public relations benefit in the short-term, communicating that some short-term action has been undertaken in acute conflict situations. In the long-term they may be counterproductive, however, as the masking odour becomes associated with the cause of the annoyance. As the intensity of the masking odour is higher than that of the original odour, it will increase the magnitude of the problem, rather than reduce it.’ - Environmental Protection Agency (2001) Environmental Research R&D Report Series No. 14. Odour Impacts and Odour Emission Control Measures for Intensive Agriculture. ‘Masking agents are generally only suitable for assisting in the control of odours from large area sources, such as landfills. Even in these cases they should not be relied upon for odour control, but should act as a ‘last line of defence’ after stringent management practices and adequate buffer distances. Agents are often more suited to process failure or abnormal emissions than routine control. In these cases they should be seen as a temporary rather than a permanent solution.’ - SEPA. Odour guidance 2010 (Version 1, January 2010) ‘Masking agents which inhibit the recipients sense of smell should not be used. Perfumes are often perceived as offensive as the original odour and are simply adding another pollutant to the air’ - Environment Agency (March 2011) Additional guidance for: H4 Odour Management How to comply with your environmental permit ‘The use of additives to mask, counteract or neutralise odour are only generally suitable for short term operations, such as transfer of material or for addition to a particularly odorous batch of slurry. They should not be regarded as a long term approach and, indeed, would not generally be cost effective in the long term. The smell of masking agents can often attract as many complaints as the smell they are trying to cover‘ - NIEA (2009) Guidance for Operators on Odour Management at Intensive Livestock IPPC Installations. Version 3, June 2009.

Summary: Emission control Priority actions for emission control at landfill sites are therefore: Forward planning (proactive) Design of the facility, including its location and filling progression (on at least an annual basis) will ensure that the site is able to be operated in a way which will not cause unacceptable odour impacts. Landfills should be designed with cells which can be filled (and permanently capped) on an annual basis, where the landform allows, thereby facilitating the capture and utilisation of LFG. Waste reception If an abnormally odorous waste delivery is considered likely to cause unacceptable odour impacts either immediately (i.e. when tipping) or over a longer term (e.g. high sulphur wastes), then due consideration should be given to how it should be handled to minimise odour or whether the load should be rejected altogether. Tipping areas The priority for tipping must be to tip the waste, and progressively cover it, as soon as possible. There must be consideration of the balance between maintaining a small tipping area (thus reducing fugitive emissions) whilst also ensuring that all wastes are appropriately tipped, compacted and covered in a safe and rapid manner.

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The balance between operational safety and odour control is likely to lead to a typical open tipping area of around 800m2 – 1200m2 at most sites. Intermediate cover (a thicker layer of daily cover) should be applied in areas where tipping will not occur for seven days or more). Permanent capping and collecting LFG The rapid installation of a cap with high integrity and low conductivity will allow for effective LFG capture and will minimise fugitive emissions from decomposing waste.

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CASE STUDY 5: UPGRADES TO OLDER SITES Country: England Annual waste imports: 350,000 – 500,000 tpa non-hazardous wastes, including municipal and commercial Approximate age of landfill: c 30 years total Landfill gas utilisation: c 6MWe installed capacity. Odour constraints The first waste was tipped in the engineered site 20 years ago, although parts of the site (‘dilute and disperse’) were operational over 10 years before this. The current operator inherited the site (and the constraints) from the previous operator. During the time the current operator has owned the site, it has been continually improved in line with regulatory requirements. However, a number of potential issues have arisen which are common on a landfill site of this age, including:    

Traditional methods of leachate storage / treatment; Outdated gas collection system (pipe materials, diameters and well spacing); Possible degradation of cap; and Low calorific gas.

Solutions adopted The operator has been very proactive in terms of addressing the issues inherited at this site, despite very significant constraints. Improvements have included: 1. Open leachate lagoons have been removed from site and have been replaced with contained tanks and additional forms of leachate treatment; 2. The operator has replaced the synthetic material previously used for daily cover with traditional soil cover; and 3. The gas collection system has been significantly improved. The operator has also invested significant resources in relation to monitoring the site using traditional and novel techniques (such as LIDAR). Summary: Lessons learned This is an example of an older site where improvements have been made which brings it in line with newer facilities and, in the case of gas management, improvements have been made which means that it surpasses many existing facilities. ‘‘Substantial investment in gas management by [the operator], often in excess of standard industry practice, resulted in considerable reduction in complaints’. – Environment Agency

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8.

IMPACT ASSESSMENT

source

control

pathway

receptor

It is not within the scope of this document to provide a comprehensive review of procedures for odour impact assessment. There is however a large body of literature which describes procedures for odour impact assessment, including:  

DEFRA (2010) Odour Guidance for Local Authorities, March 2010; and SEPA & Natural Scotland Scottish Government (2010). Odour Guidance 2010. Version 1, January 2010.

A summary of the key issues is provided in this chapter.

LFG generation models LFG generation models are useful predictive tools, particularly when designing a gas collection system. Effective gas system design will take into consideration peak production rates so that equipment such as pipe work, process plant and flares can be sized accordingly for future requirements. Effective design will ensure that LFG collection efficiency is optimised and the requirement for retrospective fitting of additional systems, wells or replacement of mains can be avoided. Basic gas modelling for the purpose of forecasting production rates will consider the following inputs87:   

Waste input rates expressed in tonnes per annum (tpa); Waste composition divided into fractions (for example, domestic, civic, industrial, commercial, inert); and Waste moisture content and degradation rate.

BOX 17. ‘It is important that the risk associated with the placement of certain waste types into a specific landfill environment is assessed in terms of immediate or local risk (i.e. migration or odour) as well as consideration of the wider global impact for example, the contribution of greenhouse gases to atmosphere. If the risk is understood, then appropriate control measures can be identified and implemented and gas capture optimised to manage risks.’ – Landfill ICoP 2012

87

Landfill Gas Industry Code of Practice: The Management of Landfill Gas (March 2012)

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H1 screening (fugitive sources) The Environment Agency has published guidance for the screening of emissions to air from landfill sources88. This guidance includes a method for screening of landfill area sources, primarily as a method of determining whether detailed assessment (such as dispersion modelling) is required to assess the risk of impact at sensitive receptors.

Detailed dispersion modelling The most common advanced impact assessment method used in the UK and the Republic of Ireland is dispersion modelling. Using measured site emissions data and meteorological data appropriate for the site, the extent of odour impact may be predicted89. This is of most use when assessing the relative impacts associated with the development of a landfill site through time and should be used at the landfill design stage.

Computational fluid dynamics (CFD) modelling Computational fluid dynamics (CFD) models have advantages over dispersion models when used to quantify odour dispersion over complex terrain or buildings, particularly over short distances (less than 100m)90. CFD is also used for modelling underground gas migration.

88

The Environment Agency (18th June, 2004) Screening method for emissions to air from landfill sites (typical gas engines, flare stacks and area sources). The Air Quality Modelling and Assessment Unit. 89 Sarkar, U., Hobbs, S.E., Longhurst, P. 2003. Dispersion of odour: a case study with a municipal solid waste landfill site in North London, United Kingdom. Journal of Environmental Management 68 (2003) pp153-160. 90 Ruby, Michael; McAlpine, J.D. (2004) ESTIMATING ODOR IMPACT WITH COMPUTATIONAL FLUID DYNAMICS. WEF/A&WMA Odors and Air Emissions 2004 , pp. 200-224(25)

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9.

MONITORING

Landfill monitoring may be either proactive (i.e. control mechanisms) or reactive (i.e. measuring emissions and impact). In general, proactive monitoring will be undertaken by the operator and reactive monitoring undertaken for purposes of compliance by the operator or regulator. Monitoring guidance exists in all regions of the UK and the Republic of Ireland. Key publications include:    

Environment Agency Technical Guidance Note H4 – Odour management. Chapter 5; Landfill Gas Industry Code of Practice: The Management of Landfill Gas (March 2012). Chapter 9; Jacobs J, Sauer, N. and Gilbert, J. (2007) An industry guide for the prevention and control of odours at biowaste processing facilities. The Composting Association. Chapter 4; and Environmental Protection Agency Office of Environmental Enforcement (OEE). Air Guidance Note 5 (AG5) Odour Impact Assessment Guidance for EPA Licensed Sites.

The effectiveness of the varied suite of approaches has also been evaluated in published research91,92,93.

Health and safety The methane in landfill gas is explosive and trace compounds may be toxic at sufficiently high levels. Landfill sites are covered by both generic and site specific health and safety legislation. In all cases, health and safety must take priority over all other considerations. No monitoring should be undertaken without a risk assessment completed in accordance with the protocols described in the health and safety policy of the landfill operator and that of the company undertaking the monitoring (if different).

Monitoring: Control mechanisms (proactive) The effectiveness of the control mechanisms described in Chapter 0 will require regular (and in some cases, continuous) verification as part of the day-to-day operation of any permitted or licensed landfill site. Waste acceptance Waste acceptance monitoring is likely to be based on the experience of the site staff (particularly the weighbridge operator) who will review the waste transfer documentation in addition to (potentially) inspecting the waste. Those with commercial responsibility in the operating company must also recognise and consider the potential for odour issues associated with certain waste streams when doing business with particular commercial and / or industrial clients (for example, if very large shipments of high sulphur waste are proposed at sensitive sites).

91

Romain A., Delva J. & Nicolas J. (2008) Complementary approaches to measure environmental odours emitted by landfill areas. Sensors and Actuators B: Chemical. Volume 131, Issue 1, 14 April 2008, Pages 18–23. Special Issue: Selected Papers from the 12th International Symposium on Olfaction and Electronic Noses — ISOEN 2007 International Symposium on Olfaction and Electronic Noses 92 Capelli, L., Sironi, S., Del Rosso, R., Centola, P., Il Grande, M.I. 2008. A comparative and critical evaluation of odour assessment methods on a landfill site. Atmospheric Environment 42 (2008) pp7050-7058 93 ARMSTRONG, K.S. and GREGORY, R.G. (2008) Review Of Optical And Other Techniques For Quantifying Landfill Methane Emissions. In: Waste 2008.

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Meteorological monitoring It is a requirement of the Landfill Directive to monitor meteorological conditions. This may be undertaken by a dedicated system on the landfill site or an appropriate surrogate system (i.e. one for which the monitoring results can reasonably be assumed to be consistent with the conditions at the site). Central control systems (e.g. LFG collection) The efficient collection and utilisation of LFG has economic as well as environmental benefits. For this reason, most sites with gas utilisation capability rely on close and effective monitoring of their gas collection systems to ensure optimal operation. The parameters monitored are described in detail in Chapter 9 of Landfill Gas Industry Code of Practice: The Management of Landfill Gas (March 2012).

Monitoring: Compliance (reactive) There are nine different monitoring methods available for landfill sites94, some of which are quantitative and based on the landfill, whilst other rely on interaction with affected communities and are related to compliance. These are:         

Point-source sampling; Surface sampling; Operator monitoring (onsite); Random monitoring (regulator); Scheduled monitoring (offsite); Field inspection; ‘STQ’ studies (‘citizen jury’); Community monitoring; and Complaint response.

These nine methods are described below. Point-source sampling This involves collection of odour samples from a point source, such as passive vent. Analysis of odour concentration (ouE/m3) and / or trace gas concentration may be completed. For further details, refer to Chapter 3 of this report. Surface sampling Surface sampling for odour involves collection of odour samples from an area source, such as a landfill surface, using a Lindvall Hood (or equivalent). Analysis of odour concentration (ouE/m3) and / or trace gas concentration may be completed. For further details refer to Chapter 3 of this report. There may be a requirement for a landfill operator to ensure that the engineered containment (i.e. landfill cap) is sufficient to prevent the release of LFG, either as a flux through the cap or egress via preferential pathways such as well seals. Methane is typically used as an indicator of LFG. Direct monitoring is typically undertaken using a flux box or Lindvall Hood95. Guidance on direct monitoring exists in all regions of the UK96 and Ireland97. 94

McGinley C.M,(1998) Odor Quantification Methods & Practices at MSW Landfills. Air and Waste Management Association. 91st Annual Meeting and Exhibition San Diego, CA: 14-18 June 1998.

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Operator monitoring (onsite) A requirement for site operatives to undertake regular odour inspections of their site is often included in OMPs for waste handling and disposal facilities. It is considered that this may be a useful practice since the operator will be most familiar with the ‘typical’ odour levels at their site. However, there are limitations to this method and it should therefore not be used in isolation. Furthermore, regulatory agencies should continue to undertake odour assessments at the sites as required (i.e. the findings of the operator should be verified as appropriate). The following limitations are taken from EPA guidance98: 1. Perceived self-interest bias: The public may perceive an inherent bias on the part of the licensee in undertaking this form of self-assessment odour monitoring. 2. Odour adaption: This is a common and entirely normal desensitisation to certain odours that may affect individuals. Staff working at a site will get used to, and therefore adapt to, specific odours from the site. This adaption means that even if they try to assess the site objectively, they may not be able to do so. Due to the odour adaption possibility of site staff, licensees may consider the use of external contractors/consultants or the use of office staff or other offsite staff who have not recently been working on the site to carry out odour assessments. 3. Odour fatigue: This differs from odour adaption in that it is believed to be exclusively associated with exposure to hydrogen sulphide (H2S)99. H2S causes olfactory paralysis at concentrations of around 140 mg/Nm3. This is a concentration which is typical in raw landfill gas, however significantly above the level which is attributed to ‘Fatigue, loss of appetite, headache, irritability, poor memory and dizziness’ (28 mg/Nm3) and over 30,000 times higher than the odour detection threshold of 3ppb. 4. Hours of operation: Many sites are not staffed during the late evening and night-time when local residents are more likely to be in/at their homes or at their property in some manner. Compounding this is the fact that dispersion conditions can be especially poor at night. Random monitoring (regulator) Unannounced inspection by regulators may be required if there is a poor history of site compliance or the regulator is concerned that the site are not reporting activities which are either outside their permit / licence or based on poor judgement by the operator. Scheduled monitoring (offsite) This may be undertaken either by the operator or regulator and consists of surveying the site boundary and any nearby receptor locations on a regular (e.g. daily) basis. This method is typically too labour intensive for regulators, but it can be very useful when a site is perceived as having a particular odour problem.

95

Sarkar, U., Hobbs, S.E. 2003. Landfill odour: assessment of emissions by the flux footprint method. Environmental Modelling and Software 18 (2003) pp155-163 96 Such as LFTGN07, for example 97 Environmental Protection Agency Office of Environmental Enforcement (OEE). Air Guidance Note 6 (AG6) Surface VOC Emissions Monitoring on Landfill Facilities 98 Environmental Protection Agency Office of Environmental Enforcement (OEE). Air Guidance Note 5 (AG5) Odour Impact Assessment Guidance for EPA Licensed Sites. 99 Health Protection Agency (2011) Hydrogen Sulphide - Toxicological overview

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Field inspection This method consists of using a panel of examiners for determining the absence or presence of odour downwind relative to the source, in order to determine the plume extent. The panel may zigzag and traverse the plume (dynamic approach) or be located in specific points on perpendicular axes (static approach), as shown in Figure 6a and 6b.

Figure 6a – Plume survey methods (dynamic) [Source: Capelli L. et al (2012)100]

Figure 6b – Plume survey methods (static) [Source: Capelli L. et al (2012)] 100

Capelli L., Dentoni L., Sironi S., & Guillot, J. (2012) Experimental Approach for the Validation of Odour Dispersion Modelling. Chemical Engineering Transactions VOL. 30, 2012

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The method is described in VDI 3940101 and will become a European Standard in the near future. As with the STQ, there are methods in development for simplification of the method based on the use of web technology102. Standardised Telephone Survey of the Living Environment (‘STQ’ studies) This method has been used primarily for research purposes. A community is contacted and a ‘Standardised Telephone Survey of the Living Environment’103 (also known as an ‘STQ’ or the Dutch acronym ‘TLO’) is administered. The STQ is a population survey method that uses a standardised list of questions to determine whether individuals are annoyed by odour from a site. Odour annoyance is only one of a range of issues covered by the questionnaire that is applied in telephone interviews104. An abbreviated list is specifically aimed at odour annoyance, and optimised for use by telephone, which requires a limited list of questions so as to ensure cooperation of those that are interviewed. In order to obtain a sufficient sample population to allow robust statistical testing, the STQ should be applied to sufficiently large samples of the exposed population in at least four study areas, with different exposure levels. It has been stated that between 100 and 200 responses are required for each exposure level test area (400-800 responses in total) for a dose-effect relationship to be established. There are methods in development, based on the use of web technology105, for simplifying the community interaction methods. These future developments will enable communities, operators and regulators to engage more effectively in the field inspection / annoyance quantification process. Community monitoring There are a number of sites where local receptors have been encouraged to maintain odour diaries, either by the regulator or the operator. This, in combination with a direct line of communication to the operator (and regulator) may be a useful way of ensuring that the local community feel empowered in relation to odours (see Chapter 10 of this report). Complaint response Complaint monitoring and complaint response is discussed in detail in Chapter 10 of this report.

Boundary testing: Olfactometry Determination of odour concentration by dynamic olfactometry as prescribed in EN 13725:2003 is not a suitable boundary monitoring approach as this would not allow long term compliance to be assessed and the detection threshold of the measurement technique is too low to provide meaningful results. Representative sampling for olfactometry analysis of air may be suitable for point source emissions or at times ambient assessments on a site (i.e. within a site’s boundary), but sampling air beyond a site boundary for olfactometry purposes is highly unlikely to be representative of odour impact.

101

VDI 3940: Measurement of Odour Impact by Field Inspection. Mannebeck. C (2012) Online Field Inspection Manager (OFIM) Grid inspection web service. Chemical Engineering Transactions. VOL. 30, 2012 103 Environment Agency (2002) Assessment of Community Responses to Odorous Emissions. R&D Technical Report P4-095/TR, July 2002; 104 It is important that the interviewed individuals must not be aware that the survey is aimed specifically at odour to avoid bias. 105 van Harreveld, A (2012) Odourmap, an Online Web Based Tool for Field Observation, Resident Participation, and Odour Community Relations. Chemical Engineering Transactions VOL. 30, 2012 102

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Also, the sampling and analytical requirements as prescribed in EN 13725:2003 may be considered unsuitable for frequent and routine odour assessments. For these reasons it is not considered a suitable assessment approach in the context of this guidance note’s objective.

Olfactory (‘sniff’) testing This requires one or more human assessor(s) to use their own sense of smell to assess odours. To carry out the assessment, the odour investigator uses his sense of smell to assess whether odours are present or not at a number of locations. This method is particularly common in Germany. Here, olfactory testing is used to assess ‘immission’ (i.e. the odour impact at a receptor location) in accordance with, for example, VDI 3940. The estimation of odour emission rate from landfills using this method has been demonstrated to be reliable in comparison with other methods of assessment106. Less formal survey methods are often used on landfill sites in the UK and the Republic of Ireland by both operators and regulators, frequently including:   

A walk of the downwind site boundary to verify if odours can be detected; An assessment of particular areas or activities on site to verify if odours can be detected (such an assessment shall cover all possible odour sources on the site); and An examination of site operations to: o Identify practices that might give rise to odours, and o Assess the effectiveness of any abatement equipment used at the site.

Following this survey, it may be necessary to visit other local potential sources of odour to eliminate them as sources of the observed odour. This will be dependent on access permissions. There are measurement tools on the market which can assist the offsite odour surveyor, such as the ‘nasal ranger’. The ‘nasal ranger’ is a portable odour detecting and measuring device developed by St. Croix Sensory, which uses the principle of “Dilution-to-Threshold” ratios (similar to a laboratory olfactometer). The use of ‘nasal rangers’ and other devices for purposes of regulation is not well established in the UK and the Republic of Ireland at the time of writing this report. The ’nasal ranger’ could, for example, be used in conjunction with the OIRS approach described in Chapter 2.

106

Nicolas, J., Craffe, F., Romain, A.C., 2006. Estimation of odor emission rate from landfill areas using the sniffing team method. Waste Management 26 (2006) pp1259-1269..

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Location Record date, time commenced odour assessment, length of time the odour remained, time odour ceased and returned. Location (street name, house number or place). If properties are occupied, if residents are at home, windows open on the property, washing out in the garden, reaction of members of te public as they walk through any odorous and potentially offensive plume, if caravans/ tents present, etc. Description of the odour and how it makes you feel. Are odorous activities or permitted sites visible, what can you see, waste being delivered/ turned, emissions from fans units, etc.

Intensity (detectability) 0.No odour 1. Very faint odour 2. Faint odour 3. Distinct odour 4. Strong odour 5. Very strong odour 6. Extremely strong odour

Extent and persistence 1. Local and transient (only detected on installation or at boundary when wind drops or blows) 2. Transient (as above, but away from installation) 3. Persistent but fairly localised 4. Persistent and pervasive (up to 50m from boundary) 5. Persistent and widespread (50m+ from boundary)

Location  sensitivity where odour is detected 1. Low sensitivity (e.g. footpath, road) 2. Medium sensitivity (e.g. industrial or commercial workplaces) 3. High sensitivity (e.g. housing, pub/ hotel, etc.)

Offensiveness 1. Less/ potentially offensive 2. Moderately offensive 3. Most/ highly offensive

Figure 7 – Odour assessment considerations [Source: NIEA (August 2012) Odour Impact Assessment Guidance For Permitted and Licensed Sites.]

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CASE STUDY 7: MONITORING Country: Northern Ireland Annual waste imports: