Regulatory Decision 058: Treating and disposing of invasive non-native plants

This Regulatory Decision (RD) is valid until 29 February 2026 by which time it will be reviewed. You should check back at that time to ensure the RD is still valid.

NRW can withdraw or amend this RD before the review date if we consider it necessary. This includes where the activities that this RD relates to have not changed.

Regulatory Decision

This Regulatory Decision (RD) relates to freshwater and terrestrial invasive non-native plants and plant material.

This RD applies if you want to dispose of invasive non-native plant material and/or the substrate in which it is rooted into or onto land within a site, without a waste permit from NRW.

If you follow the conditions in this RD, you do not need to apply for a waste permit to treat or bury invasive non-native plant material.

If the plant is listed as a species of concern you may also need to apply for a licence from Natural Resources Wales (NRW) under the Invasive Alien Species (Enforcement and Permitting) Order 2019.

You may need to apply for a herbicide agreement from NRW for the treatment of invasive non-native plants under certain circumstances.

If you cannot comply with the conditions in this RD and you want to dispose of any invasive non-native plant material by burial on site, or re-use sieved or screened soils containing Japanese knotweed on site, you must apply for a waste permit from NRW. 

Conditions you must comply with 

You must meet certain conditions to follow this RD.

Treat or bury all types of invasive non-native plant material on-site

You must:

• Have a management plan which sets out how you’ll dig up, treat or bury the material to prevent further growth or spread beyond the site
• Undertake a biosecurity risk assessment of the site and of the planned treatment and/or disposal activities that identifies the risk of spreading invasive non-native plant species and the measures to mitigate those risks; put in place measures to prevent the spread of INNS within the site and to and from the site (for example ensure that all vehicles, equipment and clothing are checked, cleaned and dried before they arrive on site and before they leave)
• Make sure that the material does not contain pollutants that will pose a threat to groundwater quality
• Bury the material on land that is of low-habitat value in an area that is likely to be undisturbed and more than 7 metres away from an adjacent landowner’s site. Low-habitat value land comprises of land that is without, for example, conservation designations, protected species, Environment (Wales) Act 2016 Section 7 habitats or Habitats Directive Annex I habitats
• Keep records for two years to show that you have complied with this RD and make these records available to the NRW on request

You must not store the material for more than 12 months before treating or burying it.

The treatment of invasive non-native plants with herbicide should be undertaken following best practice.

Bury plant material that is not Japanese knotweed on-site

You must:

• Only bury material after you’ve ruled out other options that present no risk to the environment such as composting with no risk of regrowth or spread
• Bury soils containing plants or viable plant material (for example plants, seeds, rhizomes, corms or fragments of plant that could regrow) at a minimum depth of 2 metres on the site they came from. New Zealand pigmyweed (Crassula helmsii) should be buried at a depth of 2 metres sealed with a geotextile membrane
• You must make sure that any geotextile membranes used for burial are
  - undamaged
  - large enough to minimise the need for seals
  - sealed securely
  - able to remain intact for at least 50 years
  - UV resistant

You must not bury a total volume of more than 1,000 tonnes.

Bury Japanese knotweed on-site

You can dispose of the dead brown canes of Japanese knotweed by composting on-site, as long as they are cut (not pulled) a minimum of 10cm above the crown.

You must bury Japanese knotweed plant material

• On the site it came from - including ash and soils containing potential Japanese knotweed
• At a depth of at least 5 metres if you have not sealed it with a geotextile membrane
• At a depth of at least 2 metres if you have sealed it with a geotextile membrane
• You must make sure that any geotextile membranes used for burial are
  - undamaged
  - large enough to minimise the need for seals
  - sealed securely
  - able to remain intact for at least 50 years
  - UV resistant

You must not bury a total volume of more than 1,000 tonnes.

We recommend that you use a contractor experienced in burying Japanese knotweed, preferably backed by an assurance scheme such as those offered by a relevant trade body.

You must notify NRW at least one week before you bury the Japanese knotweed material using this RD.

Reusing sieved or screened soils containing Japanese knotweed on-site

You can reduce the quantity of Japanese knotweed in soil by screening or sieving, but it is unlikely to remove all propagules (a piece of material that can develop into a new plant).

You must not take screened or sieved soils offsite, except for disposal to a landfill or incinerator that has the correct type of permit. You must remove any unused screened or sieved soils for disposal to a landfill or incineration facility.

You can reuse screened or sieved soils on the site of production, but only in a restricted area - not spread across the site. Their use must also be away from:

• watercourses, ditches or protected areas – not within 50 metres
• boundaries with neighbouring properties
• existing amenity areas, lawns and gardens
• places that may be used by people or livestock
  
  

Disposal of materials containing invasive non-native plant material off-site

If you cannot dispose of materials containing invasive non-native plant material including Japanese knotweed suitably on-site you must send it to a landfill site or incineration facility that has the correct type of permit to accept the waste.

This also applies if you excavate material previously buried using this RD, and then move it off site.

To find out where you can send it you can find details of permitted waste sites or contact your local waste disposal site. For the disposal of Japanese knotweed, you must tell NRW that you have done this and where you have sent it.

Enforcement

This RD does not change your legal requirement to have an environmental permit for a waste operation when treating and disposing of invasive non-native plants.

However, NRW will not normally take enforcement action if you do not comply with the need for an environmental permit if you meet the requirements in this RD.

In addition, your activity must not cause (or be likely to cause) pollution of the environment or harm to human health, and must not:

• cause a risk to water, air, soil, plants or animals
• cause a nuisance through noise or odours
• adversely affect the countryside or places of special interest