Environment Agency management system document: uncontrolled when printed [21/08/06]
Guidance Frequently Asked Questions on Landfill Gas Management
Number: 370_05 Status: Version 2 Issue Date: Post: Post: Post: Post: 20/12/05 Review Due: 20/12/06
Document Owner: Document Author: Primary Contact: Approved by:
(as set out in Schedule B of the NFSoD)
Joe Field Mark Bourn/Jim Shaughnessy David Browell Phil Lodge Liz Parkes
Technical Manager –Waste Process landfill Technical Advisor – Waste Process landfill Technical Advisor – Waste Process landfill Waste Process Manager (acting) Head of Waste Regulation
Purpose:
To provide answers to frequently asked questions on landfill gas management and the landfill gas guidance documents we have produced. To assist in the consistent implementation of our guidance on landfill gas management. This FAQ document has been produced for internal Environment Agency use to assist officers in dealing with queries relating to the guidance on landfill gas management. The answers may be subject to change in the light of regulatory changes, or experience of applying the Landfill Regulations and guidance. However, in the interests of transparency, this explanatory note has been made available outside the Agency. It must be stressed that these FAQs have no status other than as internal Agency guidance to staff, and that it remains the responsibility of operators and producers to comply with any obligations placed upon them under Regulations. This version of FAQs is likely to be expanded as more issues are brought forward. To date the questions have been posed via the Landfill Gas Guidance Implementation Group. Further potential questions can be proposed for inclusion in a later version of FAQs by contacting Waste Process (Landfill team). The landfill gas guidance documents, referred to below, are due for review in September 2006. We will seek to include the answers given within this FAQ guidance where possible.
Scope:
Related Documents:
Document History
Work Instruction 43_05 Implementation of Landfill Gas Guidance (Internal Document only) Guidance on the management of landfill gas LFTGN 03 Guidance on gas treatment technologies for landfill gas engines LFTGN 06 Guidance on landfill gas flaring Guidance for monitoring landfill gas engine emissions LFTGN 08 Guidance for monitoring trace components in landfill gas LFTGN 04 Guidance for monitoring enclosed landfill gas flares LFTGN 05 Guidance for monitoring landfill gas surface emissions LFTGN 07 Version AMS Date Main Changes Number Reference 1.0 370_05 05/09/05 First version of FAQ 1 - 6. 2.0 370_05 December Added two more questions: 2005 FAQ 7 What action should be taken if annual monitoring identifies a breach in the emission limit for a landfill gas engine? FAQ 8 Should the trace components in the emissions from engines and flares be monitored?
If you have any queries on the content of this document or suggestions for improvement, refer to the Primary Contact named above. If any term or acronym used in this document is unfamiliar you might find the definition in the Glossary on Easinet: Information Resources > Glossary of Terms and Acronyms. New text since the last version is highlighted in yellow [example].
Title No. Guidance: Frequently asked questions on landfill gas management Status: Version 2 Issue Date: 370_05
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Questions covered in this FAQ
1. How do we deal with PPC permits issued with standards which reflect those in the consultation version of the guidance and not the standards in the published version? 2. How many samples should be taken for trace gas analysis and from where? 3. Is the guidance just relevant to PPC permitted sites or is it applicable to waste management licensed sites? 4. For landfill gas engines, when would an emission standard different from those in the guidance be applicable? 5. If an operator can demonstrate that an emission greater than those in the guidance would not have unacceptable impact on local air quality would this be acceptable? 6. What are the requirements for flares acting as back up for gas utilisation? 7. What action should be taken if annual monitoring identifies a breach in the emission limit for a landfill gas engine? 8. Should the trace components in the emissions from engines and flares be monitored?
Questions and Answers 1 How do we deal with PPC permits issued with standards which reflect those in the consultation version of the guidance and not the standards in the published version?
This is most likely to be the case for the timing of the change to engine emission standards (January 2006 in the published guidance) and the requirement to only monitor standby flares which are used more than 10% of the time. Note that in determining compliance with emission standards account must be taken of the measurement uncertainty (sections 5.7.2 of ‘Guidance for monitoring landfill gas engine emissions’ and of 9.6.2 ‘Guidance on monitoring enclosed landfill gas flares’). The permit conditions need to be varied by the Agency to reflect the published guidance. The timing of the variation should be programmed into the Area’s work plan as soon as reasonably practicable. If a variation is required for any other reason the opportunity should be taken to reflect the published guidance in the permit. The issue should be discussed with the operator and the relevant condition not enforced where it does not correspond to the published guidance. This position should be confirmed with the operator in writing. We should not require a variation application from the operator (for this issue only). We should not charge the operator for this variation.
2
How many samples should be taken for trace gas analysis and from where?
The guidance for monitoring trace gas components sets out the requirements in sections 2.2 and 2.3. Section 2.3 states that the frequency for monitoring should be annual at a minimum. The frequency should be greater when site-specific circumstances alter, e.g. if significant changes to the gas management system or waste composition occur. To illustrate this, here are some examples of significant changes where we believe additional trace component analysis may be required: • • • • A change of 20% in the putrescible content of the waste from which the gas is drawn (e.g. connecting to a significant new cell) A change of 10%v/v in the methane concentration (e.g. from 50% to 40%). A change in gas flow of more than 20%. A change in leachate head of 5 metres.
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• •
Extinguishing a large sub-surface fire. Redrilling 25% of the gas wells on site.
For sites with a gas composition containing unusually high trace components, for instance hydrogen sulphide or halogenated hydrocarbons a higher frequency of sampling an analysis would be justified. The annual minimum is a starting point, where the site specific circumstances dictate, a higher frequency can be justified. The guidance is largely written to reflect the situation at the majority of sites, for those that pose more challenges than the norm a site specific decision needs to be made. Section 2.3 describes the selection of the sampling point. It is important to consider the purpose of the sampling. The guidance states that where there is a central utilisation plant, a sampling point in the main gas line will typically provide the only samples needed to characterise the raw gas at the site. If the purpose of the sampling is to characterise the source gas for the site, then the most convenient point to take a sample representative of the whole gas field is where gas from the various gas wells has been combined. Hence, sampling the main line prior to the combustion plant will be the most appropriate point. When a cell contains atypical waste, it may be necessary to sample from a manifold where the gas is representative of this particular source in order to provide information for a specific risk assessment. This will be particularly relevant at sites that may have a problem with inadequate collection efficiencies and due to this an odour problem. The understanding of the trace composition of the gas from a particular cell will therefore be necessary to understand the odour or potential health impact. It should be noted that this should not distract from resolving the odour problem through improved gas collection.
3
Is the guidance just relevant to PPC permitted sites or is it applicable to waste management licensed sites?
This guidance has been developed for sites that are subject to PPC permitting. It is also relevant to sites that remain subject to the Waste Management Licensing regime (WML). To determine how and when it should be applied to WML sites, reference should be made to Work Instruction 43_05 Implementation of Landfill Gas Guidance. The Work Instruction sets out a simple risk based approach to determining when an emissions review of each landfill should be undertaken. This emissions review will provide the basis for determining which best practice landfill gas management measures are relevant to the site and when they should be applied. The timetable for improvements to each landfill should be based on the risk posed by the site. It is not however directly applicable to sites which are not regulated by the Agency. Where a PPC permit is required for gas utilisation on an unlicensed sites (e.g. a site where the COPA licence was handed back prior to waste management licensing) then the guidance will be relevant for the combustion installation. The guidance represents what we consider best practice for managing landfill gas. It is therefore relevant whether being used to indicate BAT for a landfill installation or for preventing pollution of the environment or harm to human health.
4
For landfill gas engines, when would an emission standard different from those in the guidance be applicable?
The guidance represents best practice and what we believe can be achieved by a well designed, operated and maintained spark ignition engine. For a PPC installation the guidance represents indicative BAT – note that BAT is site specific. The reasons for requiring a higher standard (lower emissions) would normally be on the basis of local air quality impact. This could be either due to Local Air Quality Objectives (AQO) or European Limit Values (EU LV) – most likely to be an issue for NOx -, or a site specific exceedance of
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an EAL (see H1 guidance Environmental Assessment and Appraisal of BAT). If there is a problem with AQO or EU LV (applicable anywhere outside the boundary) then advice should be sought on this issue via Waste Process.
5
If an operator can demonstrate that a higher emission than those in the guidance would not have unacceptable impact on air quality would this be acceptable?
No. The guidance represents best practice and what we believe can be achieved by a well designed, operated and maintained spark ignition engine. Emissions should be prevented or, if that is not possible, reduced. Emission standards must not be determined simply on the basis of the maximum releases that the receiving environment can sustain. Engines operating on non-spark ignition principles (e.g. turbines) will need to be assessed and agreed with the Agency on a site specific basis, due the currently limited information available to provide a general benchmark.
6
What are the requirements for flares acting as back up for gas utilisation?
An enclosed flare that has a stand-by role for utilisation plant, does not need to be subject to an annual monitoring exercise provided that: it is required to burn landfill gas for less than 10 per cent of the time (on an annual basis); the flare can be shown to be operating within the Agency’s operational standard (e.g. temperature and residence time, not impeded by cowls etc) and routine monitoring is not identified as necessary within the site-specific risk assessment (section 4.4.2 of the guidance on the management of landfill gas). Essentially the only criterion that a standby flare need not meet is the requirement to be monitored annually, all other criteria must be complied with. Stand-by flares for utilisation plant must be enclosed flares. Open flares can only be employed in the case of an emergency.
7
What action should be taken if annual monitoring identifies a breach in the emission limit for a landfill gas engine?
Compliance testing for landfill gas engines consists of an annual emissions test using four determinands. These standards have been based on research into what can be achieved by a well run and maintained engine (i.e. operated according to best practice). The emission levels that can be achieved in practice will also depend on the age of the engine, hence the standards reflect the engine installation date. Data from an annual emissions test will be assessed taking into account the compliance allowance described Guidance for monitoring landfill gas engine emissions LFTGN 08. Comparison of emissions against the standard will result in one of three outcomes; compliance, approach to limit or non-compliance. Non-compliance (i.e. emissions above the standard after adding the compliance allowance) must be reported to the Environment Agency in accordance with the permit. The permit holder will need to develop an Action Plan to establish the reasons for the non-compliance, assess the environmental consequences and identify appropriate action within defined timescales. Once the Action Plan has been agreed, the permit condition has been complied with and ‘scored’ accordingly. Action Plans will be site specific and should include the following: a. Review of maintenance schedules. This should include an assessment of engine oil analysis with the aim of identifying potential problems with the operation of engine that may affect the emissions.
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b. Review of inlet gas composition. It may be necessary to undertake additional sampling to characterise the trace gas components in accordance Guidance for monitoring
trace components in landfill gas LFTGN 04.
c.
Review of the condition of the engine e.g. internal visual inspection.
d. Assessment of the related landfill gas management system. This should cover issues such as condensate management and review any problems with air ingress. Operational failures in the gas management system (e.g. damage / blockage of transmission lines) can result in a significant deterioration in engine emissions. e. Review of the current air quality risk assessment. This should use site specific data on actual emissions and inlet gas composition to validate assumptions made in the modelling. Note that a 10% increase in release rate equates simply to a 10% increase in maximum ground level concentrations from the plant. The revised concentrations should be compared to the relevant air quality standards and this analysis used to prioritise actions. NOx is typically the most critical engine emission standard to impact local air quality. In comparison non-compliance with the Non-methane VOC's standard is unlikely to result in a local air quality impact. Where there is a predicted impact then this will require prompt remedial action f. Identification of proposed actions. following options: ▪ ▪ ▪ ▪ These should include consideration of the
Replacement of plant or elements of plant and elements of the extraction system Refurbishment of plant and or extraction systems Revised maintenance schedules Operational changes both in the gas extraction system and engine management systems
In coming to a conclusion on the way forward the costs and environmental benefits of the proposed actions should be considered and a timetable of should be drawn up. g. Additional emissions monitoring. Within six months of the Environment Agency being notified of a non-compliance with an emission standard, an additional monitoring exercise should be undertaken to confirm the performance of the engine. If this additional emissions monitoring demonstrates compliance, then the engine will be considered compliant and revert to a programme of emissions testing on annual basis from that date. h. Submission of Report to Waste Process. After following the above steps if the operator is unable to identify the reason for non-compliance and it is agreed that there is no unacceptable risk to the environment, a Summary Report should be forwarded to Waste Process. The Environment Agency/Industry Landfill Gas Group will undertake a review of existing guidance including engine emission standards in 2006. Any such Summary Reports will help to inform this review and where such a report has been produced no further action is required prior to completion of the review of guidance and standards. For new engines, the operator should confirm that the specification and installation and operation of the engine represents best practice. If subsequent monitoring demonstrates non-compliance against the new emission standard for non-methane and total VOC's but demonstrates compliance with the existing emission standard for these determinands, the current air quality risk assessment should be reviewed. Where this review confirms no environmental impact or risk to human health from the increased emissions, then the results can be considered as 'approach to limit'. No additional action is required until completion of the review of guidance and standards.
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Guidance: Frequently asked questions on landfill gas management Status: Version 2 Issue Date: 370_05
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8. Should the trace components in the emissions from engines and flares be monitored?
Under normal circumstances the individual trace components in the emissions from landfill gas combustion do not need to be monitored. The Guidance requires the total VOCs and non-methane VOCs to be monitored during emissions testing but does not require speciation of these. Methods for measuring the VOCs in emissions are provided within the Guidance on monitoring flares (LFTGN05) and monitoring engines (LFTGN08). Speciation and quantification of the trace components in the raw landfill gas is required on an annual basis. A method for making representative measurements of the 25 priority trace components in raw landfill gas is provided in LFTGN04 Guidance on monitoring trace components in landfill gas.
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