Guidance

Landfill operations: pollution inventory reporting

Updated 21 August 2024

Applies to England

• Publication for Northern Ireland
• Publication for Scotland
• Publication for Wales

You must report to the pollution inventory if you operate a landfill, and the Environment Agency has sent you a notice requesting this information.

The ‘general guidance’ available in the pollution inventory reporting guidance gives information that applies to all business and industries. It explains what the pollution inventory is and how to report.

This guidance gives information specific to landfill activities.

Releases to air (landfill gas releases)

Emissions to air from landfill installations are separated into two categories:

• fugitive emissions of landfill gas from the landfill
• point source emissions from the combustion of landfill gas on site – for example, engines or flares

Relevant pollutants

The most common air emissions from landfill and the associated combustion activities are:

• benzene
• carbon dioxide (CO₂)
• carbon monoxide (CO)
• chlorofluorocarbons (CFCs)
• chloroform (trichloromethane)
• hydrofluorocarbons (HFCs)
• hydrochlorofluorocarbons (HCFCs)
• methane (NH₄)
• methyl chloroform (1,1,1-trichloroethane)
• non-methane volatile organic compounds (NMVOCs)
• oxides of nitrogen (NOx)
• particulates (including PM10)
• sulfur oxides (SO₂ and SO₃) as SO₂
• vinyl chloride

Using GasSim to calculate predicted emissions

You need to calculate an accurate prediction of methane generated at your site. You must use GasSim v2.5 where site-specific gas release data are unavailable. You must update GasSim models every year to make sure it properly reflects the amount of waste you received at your landfill.

Your model needs to reflect what happens at the landfill. To do this, you will need to know:

• gas generation
• collection efficiency
• utilisation

By updating your model, you can ensure that estimates of emissions are as accurate as they can be.

You can use the resulting annual mass releases to complete the air releases section of the pollution inventory reporting form.

How to report carbon dioxide releases

You should report the sum of the GasSim outputs ‘CO₂ thermal’ and ‘CO₂ chemical’ as ‘carbon dioxide’ – this is total release of carbon dioxide (CO₂) from the installation.

If most of the landfill gas collected in the reporting year was combusted in engines as a fuel, you should report the GasSim output ‘CO₂ thermal’ as ‘Carbon dioxide from qualifying renewable sources’. This is a subset of the total CO₂ release, so you still need to report the full figure in the total CO₂.

If most of the landfill gas collected was combusted in flares, then you should report no value under ‘Carbon dioxide from qualifying renewable sources’.

While these definitions are not strictly accurate, this is the best way to ensure that data is reported consistently.

We are aware that GasSim applies a reporting threshold to both ‘CO₂ thermal’ and ‘CO₂ chemical’, so it may report either or both as ‘brt’. In this situation:

• if GasSim reports ‘brt’ for ‘CO₂ thermal’, report no value under ‘Carbon dioxide from qualifying renewable sources’
• if GasSim reports ‘brt’ from ‘CO₂ chemical’ and a value for ‘CO₂ thermal’, you should report the ‘CO₂ thermal’ value under both ‘Carbon dioxide’ and ‘Carbon dioxide from qualifying renewable sources’
• if GasSim reports ‘brt’ for both values you should enter ‘brt’ for ‘Carbon dioxide’ and no value under ‘Carbon dioxide from qualifying renewable sources’

Releases to controlled waters and off-site transfers of wastewater

The most common releases to controlled waters and off-site transfers of wastewater from landfill activities include:

• all permitted releases of surface water and treated leachate from a landfill to controlled waters (surface and groundwater)
• off-site transfers of landfill leachate and contaminated water for treatment at a wastewater plant

Calculating releases to controlled waters and off-site transfers

Your permit requires periodic monitoring of discharges to surface water and leachate quality. You record treated leachate effluent release rates under the requirements of your permit or trade effluent consent. These are issued by the local sewerage undertaker. You also record the volumes of untreated leachate that is removed for off-site disposal. These data can be used to make an accurate estimate of annual releases and transfers of leachate.

You should calculate releases to controlled waters and off-site transfers of leachate by using real monitoring data where it is available for a reportable substance.

Where no monitoring data exists for a substance, and there is good reason to believe that the substance has been released, we expect you to make an estimate of the mass release using another reasonable ‘release estimation technique’ (RET). For more information about RETs, check the ‘general guidance’ available in the pollution inventory reporting guidance.

You should describe the technique used in the ‘Qualification Notes’ box in the Summary section of your pollution inventory return. If you leave this blank, we may later ask you for more information.

Reporting releases to controlled waters and off-site transfers

For each pollution inventory substance, you should add together the quantities in each individual release to controlled waters from the site.

If the total release for a substance exceeds the reporting threshold, you must report that release on the reporting form. Reporting thresholds are given next to each substance on the reporting form. If you have released a substance but the quantity is less than the reporting threshold, you can either give the actual value, or report it as ‘brt’ (below reporting threshold). We encourage you to still report the actual release on the form, even if it is brt. This helps us to build a more complete dataset.

You need to report substances in leachate transferred off-site (for example, in a road tanker) in the same way. There are various ways in which treated and un-treated landfill leachate is disposed. How these data should be reported to the pollution inventory is different dependent on the disposal method. The requirements are:

• for leachate treated on site and released to controlled water – use Part 4 Releases to controlled waters
• for leachate treated on site and released to public sewer – use Part 5 Off-site transfers in wastewater
• for leachate transferred by any other means to an urban wastewater treatment plant (that is, a sewage works serving the public sewerage network) – use Part 5
• for leachate transferred by any means to an industrial wastewater treatment plant (that is, a specialist plant not treating urban or public sewage) – use Part 6 Off-site waste transfers

We use this classification so that the pollution inventory report captures information on the destination of the pollutants. The reporting guidelines do not affect the controls applied to waste under the Waste Framework Directive.