When knotweed is dug out rather than treated in place, the soil is the bulk of the waste. Rhizome spreads sideways and downwards from the visible stems, and any soil that may contain a fragment of it has to be handled as knotweed waste. This page explains how that soil is assessed and disposed of. It is one part of our Japanese knotweed disposal service.
Excavated soil assessment
Before we quote, we need to understand the material. We ask for:
- the site address and what the land was used for previously
- the estimated quantity, in tonnes or cubic metres
- what the soil is like: topsoil, clay, made ground, rubble or a mixture
- whether the knotweed has been treated with herbicide, and with what
- any soil analysis, site investigation or remediation report you already hold
- photographs of the excavation or the stockpile
The extent of the dig is a matter for your knotweed specialist or remediation contractor. We work from the quantity they expect to remove.
Waste classification
Soil containing knotweed is normally classified as non-hazardous waste. It is not inert, so it cannot go to an inert landfill, be used as fill on another site or be sold as topsoil. Knotweed does not make soil hazardous by itself. Other things can: hydrocarbons, asbestos, heavy metals and similar contaminants found in made ground, or residues of some persistent herbicides. If any of these are present the soil is classified on that basis and its disposal route changes.
Soil testing where required
For soil from a garden or greenfield site, the description of the waste and its origin may be all a facility needs. For soil from brownfield or made ground, or where there is doubt, the facility will usually ask for chemical analysis to classify the waste, and sometimes for further testing against its acceptance criteria. If you already have results from a site investigation, send them. If not, we will tell you what the receiving facility requires so that sampling can be arranged before the dig rather than during it.
Segregation of affected material
Knotweed-contaminated soil must not be mixed with other surplus soil. Keeping it apart protects clean material from contamination and, because disposal is charged by weight, keeps the quantity sent for specialist disposal to what is actually affected. On site that means:
- marking out the infested area before work starts
- stockpiling affected soil on a membrane or hardstanding, away from drains and watercourses
- keeping roots, crowns and stems with the knotweed waste, not with green waste
- cleaning plant and tools before they move to clean ground
Bulk quantities
A knotweed dig on a development plot can produce a great deal of soil in a few days. For bulk quantities we agree a programme of loads with your site team and book the tonnage in with the receiving facility, so that material leaves at the rate it is excavated.
Receiving-facility acceptance
Only a facility whose permit or authorisation covers material containing invasive plants can take this soil, and it must be told in advance what is coming. Facilities set their own conditions on analysis, daily tonnage and delivery times. We confirm acceptance in writing before collection. Suitable disposal arrangements must be in place before waste leaves the site, and we will say so plainly if a route cannot be found for a particular material.
Containment and transport
Soil is carried in covered or enclosed vehicles by a registered waste carrier, direct from your site to the facility. See Japanese knotweed haulage for vehicles, loading and biosecurity.
Documentation
Each load is covered by a waste transfer note describing the soil and stating that it contains Japanese knotweed, or by a consignment note if it is classified as hazardous. After disposal we collect the facility’s records for you. The legal background is set out in our guide to Japanese knotweed disposal regulations, and the things that drive the price are covered in Japanese knotweed disposal costs.