Composting leachate
What you must do
You may need an authorisation to carry out composting activities in Northern Ireland and Scotland.
In Northern Ireland, to make compost under an exemption you must:
- only produce the compost at the site where the waste is produced
- apply the compost only on the ground where it is produced
- not keep livestock on the site
In Scotland, some composting activities are considered low-risk waste activities (LRWA) and do not require authorisation from SEPA, if conditions are followed. These activities are:
- LRWA 16 - Composting biodegradable waste or manure in open systems, and use of the compost, at the place the waste or manure was produced, e.g., at farms, liveries, schools, parks, golf courses, nature reserves.
- LRWA 17 - Composting less than, or equal to, 1 tonne of waste, including Animal By-Product food waste (i.e., mixed food waste) per day in an enclosed system. For example, at a hotel, hospital, college campus, or market.
You must also meet your requirements under the Duty of Care.
If you compost catering waste, you must also comply with Animal by-products regulations.
You must ensure that leachate or contaminated run-off does not cause any pollution to land, surface, or groundwater pollution.
You must locate all compost treatment areas on waterproof, weatherproof surfaces with sealed drainage.
In Northern Ireland, you must have a discharge consent, groundwater authorisation or a pollution prevention and control (PPC) permit before you discharge anything other than clean uncontaminated water to the environment. This includes sewage, trade effluent or contaminated surface run-off.
In Scotland, if you discharge anything to the water environment you may require an authorisation from SEPA. Some discharges are authorised if you comply with the general binding rules (GBR). In such cases, you do not need to apply for authorisation from SEPA if you comply with the rules.
You must comply with all the conditions of your authorisation.
You must ensure that any contaminated water or leachate is only taken off-site by a business that holds an appropriate authorisation for the activity carried out.
You must keep all leachate separate from treated compost. This prevents contamination.
Good practice
Set up a system to hold and manage leachate. This could consist of a containment tank or a lagoon.
You must measure and detect when storage systems are nearly full. Plan collections or treatment in advance to minimise the risk of pollution from overflowing storage systems.
Locate your composting facilities inside and under cover. This will prevent rainwater accessing your facilities and will reduce the volumes of leachate you have to deal with. If you cannot locate your facilities inside, cover your compost with sheeting to protect it from rainwater.
Minimise the time you store leachate on your site. This will reduce the risk of odours.
In certain situations, you may be able to recirculate the leachate into your compost to maintain the correct moisture balance.
Store all chemicals in an area where spills can be contained. This should be within a secondary containment system (SCS), such as a bund. The SCS should be able to contain at least 110% of the volume of the largest tank or 25% of the total volume likely to be stored, whichever is greater.