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This publication is available at https://www.gov.uk/government/publications/sr2021-no-6-anaerobic-digestion-facility-including-use-of-the-resultant-biogas-installations/sr2021-no-6-generic-risk-assessment-for-anaerobic-digestion-facility-including-use-of-the-resultant-biogas-installations
The anaerobic digestion (treatment) facility must have the capacity to treat more than 100 tonnes of waste, or a combination of waste and non-waste in any one day.
The Environment Agency produces the generic risk assessments for all standard rules permits. These list the potential risks and how to manage them.
Check this generic risk assessment to understand:
Risk management involves breaking or limiting the source-pathway-receptor linkage to reduce the risk. If we set minimum distances we explain the basis of the distance, for example by modelling.
We will control the residual risk (after risk management) when we assess compliance.
If you need to check the meaning of any terms we have used (in the context of this risk assessment), see the explanation of terms.
This generic risk assessment is based on the following parameters.
Permitted activities s5.4 A(1)(b)(i) are:
The permitted wastes are biodegradable wastes suitable for digestion.
The maximum quantity of waste received each day shall not exceed the designed storage capacity of the site.
Except for the auxiliary flare, the aggregate rated thermal input of all appliances used to burn biogas must be less than 5 megawatts.
The maximum quantity of animal waste, including animal carcasses, shall be limited to 10 tonnes per day, this excludes manures and slurries.
These rules do not allow any point source emission into land, surface waters or groundwater under control of the permit.
The activities shall not be carried out within:
200 metres of the nearest receptor as measured from any combustion stack or stacks, unless the stacks are at least 7 metres high and the effective stack height of each stack is greater than 3 metres
250 metres of the nearest sensitive receptor where any further treatment takes place by composting digestate fibre in the open
500 metres of a European site (within the meaning of Regulation 8 of the Conservation of Habitats and Species Regulations 2017) or a Site of Special Scientific Interest, including candidate or proposed sites
a groundwater source protection zone 1 or 2, or if a source protection zone has not been defined then within 50 metres of any well, spring or borehole used for the supply of water for human consumption (including private water supplies)
250 metres of the presence of great crested newts, where it is linked to the breeding ponds of the newts by good habitat
50 metres of a Local Nature Reserve, Local Wildlife Site, Ancient Woodland or Scheduled Monument
50 metres of a site that has species or of principle importance (as listed in Section 41 of the Natural Environment and Rural Communities Act 2006) that the Environment Agency considers at risk to this activity, these are also often referred to as priority habitats and species
a specified Air Quality Management Area (AQMA)
NOx, SOx, CO and other gases travel through the air and can be inhaled.
We have assessed the potential harm to human health as follows:
The reasons for giving the activity this rating is because there is potential for exposure to:
The following manages the risk:
Taking these actions will control the risk and rate it as ‘low’.
Bioaerosols travel through the air and can be inhaled.
We have assessed the potential harm to human health as follows:
The reasons for giving the activity this rating is because there is potential for release:
The following manages the risk:
Taking these actions will control the risk and rate it as ‘low’.
Odour travels through the air and can be inhaled.
We have assessed the potential risk to the local population as:
The reasons for giving the activity this rating is because local residents are sensitive to odour. Odour can result from:
The following manages the risk:
Taking these actions will control the risk and rate it as ‘low’.
Noise travels through the air and vibration through the ground.
We have assessed the potential risk to the local population as:
The reasons for giving the activity this rating is because local residents can be sensitive to noise and vibration. However, there is low potential for exposure.
The following manages the risk:
Taking these actions will control the risk and rate it as ‘low’.
There is a risk of direct physical contact with all on-site hazards such as wastes, machinery and vehicles.
There is a risk of causing injury to humans or livestock.
The reasons for giving the activity this rating is because it is carried out within enclosed digesters so physical contact is minimised.
The following manages the risk:
Taking this action will control the risk and rate it as ‘low’.
Arson and vandalism risk causing the release of polluting materials to the air (smoke or fumes), water or land.
Arson and vandalism can cause:
We have assessed the potential harm as:
The reasons for giving the activity this rating is because:
As risk 2.1 plus the following manages the risk:
Taking these actions will control the risk and rate it as ‘low’.
An explosion of biogas risks causing fire and smoke to travel through the air.
We have assessed the potential harm as:
The reasons for giving the activity this rating is because the risk is reduced by an effective management system being in place, as required by the permit.
However, biogas is flammable, and the consequences are likely to be serious, including risk to:
The following manages the risk:
This risk is managed in the same way as risks 2.1 and 3.1 and these additional measures:
Taking these actions will control the risk and rate it as ‘low’.
Fire can cause polluting materials (smoke or fumes) to travel through the air, water or land. We have assessed the potential harm as:
The reasons for giving the activity this rating is because the risk is reduced by an effective management system.
This risk is managed in the same way as risks 2.1, 3.1 and 3.2 along with:
Taking these actions will control the risk and rate it as ‘low’.
There is a risk of:
The reasons for giving the activity this rating is because there is a risk of:
The following manages the risk, there is a requirement to:
Taking these actions will control the risk and rate it as ‘low’.
We have assessed the acute effects as:
We have assessed the harm as:
The reasons for giving the activity this rating is because of the potential for spillage from digestion tanks and storage vessels.
The following manages the risk:
Taking these actions will control the risk and rate it as ‘low’.
We have assessed the chronic effects as deterioration of water quality.
We have assessed the harm as:
The reasons for giving the activity this rating is because of the potential for spillage from digestion tanks and storage vessels.
The following manages the risk:
Taking these actions will control the risk and rate it as ‘low’.
These risks relate to watercourses downstream of a facility and to water for agricultural or potable use.
This receptor is at risk from spillage of digestate liquids due to tank failure.
There is a risk of contaminants travelling through direct run-off from the site across ground surface, via surface water drains and ditches and finally through abstraction. This could have acute effects and cause the closure of abstraction intakes.
The reasons for giving the activity this rating is because of the potential for spillage from digestion tanks and storage vessels.
Risk management is as set out in risks 5.1 and 5.2 along with:
Taking these actions will control the risk and rate it as ‘low’.
Groundwater is at risk from spillage from digestate tanks and storage vessels.
There is a risk of contaminants travelling through soil to groundwater which can then be abstracted from a borehole. This could have a chronic effect resulting in the groundwater requiring treatment or causing closure of a borehole.
The reasons for giving the activity this rating is because of the potential for spillage from digestion tanks and storage vessels.
Risk management is as set out in risks 5.1, 5.2 and 6.1 and:
Taking these actions will control the risk and rate it as ‘low’.
There is a risk of fugitive releases of volatile organic compounds such as methane from storage of gas bags, lagoons, tanks, vents and pipe work.
We have assessed the harm as:
The reasons for giving the activity this rating is because:
The following manages the risk:
Taking these actions will control the risk and rate it as ‘low’.
Protected sites can be at risk from any source and by any pathway. However, the main risk is from ammonia and NOx.
The risk of harm to protected sites include (but are not limited to) the following:
The reasons for giving the activity this rating is because waste composting operations may cause harm to and deterioration of nature conservation sites.
The following manages the risk:
Taking this action will control the risk and rate it as ‘low’.
The things at risk and that need protecting.
Receptors considered include: atmosphere, land, surface waters, groundwater, humans, wildlife and their habitats.
A single receptor may be at risk from several different sources and all must be addressed.
The agent or process that has the potential to cause harm.
A contaminant or pollutant (a hazard) that has the potential to cause harm. For example, the activity or operation taking place for which a particular hazard may arise.
The harmful consequence to the receptor if the hazard is realised.
The route or means by which a defined hazard may affect a receptor.
There has to be a link between the source, pathway and receptor for there to be a risk.
This is the likelihood of the receptors being exposed to the hazard. The meaning of the definitions are:
This is the severity of the consequence if the hazard is realised and may cause actual or potential harm.
This will have a high, medium, low or very low rating using attributes and scaling to consider ‘harm’.
We work out the risk rating by combining the likelihood of exposure with the magnitude of the potential consequences.
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