Is it essential to have knotweed removed from construction and development sites?
A common question asked by construction clients is; must knotweed be removed from site? In this article we look at why the construction industry’s default response to knotweed is to have it removed from site and transported to landfill (licensed to receive knotweed waste) and explore why more sustainable on-site options such as cell-burial should be considered.
For years, the default response to discovering Japanese knotweed on a construction site was straightforward: excavate and remove. Known in the industry as ‘dig-and-dump’ it involves taking all excavated knotweed plant material and contaminated soils offsite, transporting it to a landfill site licensed to receive this type of waste. But with mounting pressure on project budgets, environmental targets, and landfill capacity, other methods are often explored.
As specialists in knotweed survey, treatment and removal, we always recommend the best removal method(s) to suit the site and the project, and this often includes looking to more sustainable on-site management strategies.
The pro’s and con’s of dig-and-dump
Excavating and removing knotweed-contaminated soil is a permanent option to eradicate knotweed. This is especially important if the land is being developed as it leaves a clean site fit for purpose. And whilst it may sound straightforward, this process must be expertly managed under strict biosecurity protocols. You’re paying for licensed haulage and specialist disposal and on larger sites, this can be a significant volume of waste.
There’s also growing pressure from an environmental standpoint. Reliance on herbicide-based treatments and unnecessarily sending contaminated material to landfill generates emissions that directly contradict the net zero and ESG commitments most contractors and developers now report against and as those expectations tighten, that tension is only going to increase.
A more sustainable approach
Contractors getting this right are thinking about knotweed the same way they think about any other contamination risk: early, and with a plan. On-site solutions, when properly scoped and delivered by qualified specialists, can remove much of the project cost and disruption from the equation. Though please note – not all sites are suitable for on-site solutions (if in doubt ask us for advice).
In practice, that means considering options such as creating containment cells – an engineered solution that keeps material on site (buried in a dedicated cell) rather than transporting to landfill. It’s important to note that this must be controlled excavation with full validation – where any earthworks are properly documented and compliant from start to finish.
Done properly, on-site approaches cut haulage costs, reduce landfill reliance, and keep projects moving. Done badly, or attempted without the right expertise, they can make things significantly worse, as knotweed will regenerate from any fragment of plant material not contained.
Jennifer Holmes (of Japanese Knotweed Ltd) states: “The industry has come a long way in how it thinks about knotweed. It’s no longer a surprise problem that gets dealt with reactively, but it’s a known project risk that needs to be planned for. The good news is that when you engage the right specialists early, there are now more flexible, cost-effective, and environmentally sound options available than ever before. But these solutions only work when they’re delivered by qualified professionals with the right compliance framework in place. Knotweed must not be ignored but it’s equally not to be feared when you get the right help.”
Knotweed is not for DIY
Japanese knotweed is recognised as controlled waste under the Environmental Protection Act 1990, which means managing it on-site isn’t a workaround, it’s a legitimate, increasingly preferred approach, but only when it’s delivered by qualified specialists with the correct risk assessments, biosecurity protocols, and compliance measures in place.
The plant spreads easily and a poorly managed on-site operation without the correct expertise, can extend an infestation rather than contain it, with all the legal and financial consequences that follow. Getting the right advice about dealing with knotweed can be a game-changer for project success. Get it wrong and you’ll never get rid of the problem!
More information on the impact of knotweed on construction projects
Conclusion
There are a range of knotweed removal options to manage or eradicate knotweed – the right solution will depend on the site, its intended planned usage and any other considerations such as environmental sensitivity, underground infrastructure and project restrictions. Removing knotweed to landfill is a permanent solution, but if the site is suitable, then looking at on-site options may be preferrable.
Our team are here to help – ask any questions about knotweed, book a survey to find out if you have knotweed, or get a quote to have it dealt with.