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Japanese Knotweed Excavation

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Japanese knotweed (Fallopia japonica) has become a major problem in urban areas across Europe. This invasive species causes serious damage to infrastructure such as roads and buildings. How does it spread and why is it so problematic?

The plant was introduced into Britain from Japan in 1878. Today, it grows throughout England, Wales and Scotland. In recent years, its range has expanded northwards through Scandinavia and eastwards along the Atlantic coast.

A Japanese Knotweed infestation spreads via Japanese knotweed rhizomes or underground stems. These roots send out new shoots every year, which can grow rapidly per day. Once established, knotweed forms dense clumps that can block drainage systems and cause structural problems.

Want to develop on land contaminated with knotweed? Excavation might be your only hope

It is necessary to get rid of a Japanese knotweed infestation from any lands (or larger sites) affected by Japanese knotweed that are going to be used for construction or as development sites. If the weed is severe enough, it may be necessary to remove it before construction can begin.

Japanese knotweed has rhizomes that can grow up to 7 meters long from where they emerge above ground, meaning large-scale infestations may have gone undetected for some time. Plants can grow rapidly and become quite large, making it difficult to remove them without damaging the structure.

There are a number laws that control the removal and safe disposal of Japanese knotweed contaminated waste and contaminated material. Construction companies are subject to additional regulations that private landowners aren’t, no one wants cross – contamination.

Developers should ensure that they assign a registered waste disposal company to remove any contaminated soil. You should never attempt to remove any contaminated soils or wastes by yourself. If you’re caught doing this, you could face prosecution for breaking UK law.

Is Excavation just suitable for developers?

The short answer is no. Excavation and removal is the best option when herbicide treatments are not viable.

We will issue a certificate confirming that the site is free from Japanese Knotweed once the excavation has been completed.

If you have limited time and no other options, then using this treatment method is ideal. Instant eradication isn’t possible but this is the closest option available and will cut the time needed for Japanese Knotweed eradication from years to days or weeks.

Quickly removing all traces of the pest from your commercial project allows for a rapid solution to your issue and allows your business to get back to work almost immediately. If time is of the essence and you need to get rid of Japanese Knotweed quickly, then there is no faster Japanese Knotweed removal/ treatment method.

Waste taken off-site will always be done so by a licensed waste carrier to an appropriately-authorised landfill site.


Fill in the form below, attach your pictures and we’ll let you know if the plant in your picture is Japanese Knotweed.

Japanese knotweed excavation methods

For new build schemes and construction sites, excavation provides the fastest way of removing Japanese knotweed.

Excavation is a process that involves removing contaminated soil using plant equipment. We will either dispose of the knotweed or infected soil on-site in a controlled manner or move it to a licensed landfill site.

Once the knotweed survey has been completed, a surveyor will examine the site and determine the best course of action. Two main options exist for disposing of waste: on-site disposal or off-site disposal.

1. On-site disposal - Excavation & Screening

We are committed to excellence and environmental responsibility, so this excavation method has our ‘Zero to Landfill’ approach. Using our Environment Agency-approved method, we ensure efficiency and sustainability from start to finish.

A tried and tested methodology used on hundreds of sites across the UK. Using the screening method, the Japanese knotweed rhizome material is separated from the soil material. The Japanese knotweed material is then either transported to licensed landfill at a much lower disposal rate or incinerated on site using a D6 exemption from the Environment Agency or Natural Resources Wales.

The cleaned soils can then be reused in locations away from any construction, normally in soft landscaping areas.

This can reduce the landfill & backfill requirement costs significantly and can also help to reduce the carbon footprint on site due to reduced vehicle movements to landfill.

The time taken to process the material depends on its composition and density. Once screened, the Knotweed rhizomes and vegetation are transported to a dedicated waste transfer station for incineration. This kills the invasive species and is environmentally friendly.

Zero to Landfill benefits:

  • Cost-effective: There is no need for expensive imported backfill. The cost savings can be enormous in comparison to a standard dig and dump to landfill – in some instances, as much as 65%.
  • Immediate results: As quick as traditional excavation methods, there is no delay to your project.
  • Year-round: No seasonal restrictions; can be completed at any time of the year.
  • Environmental responsibility: At the heart of everything we do.
  • Compliance: We are fully compliant with the law, so you have peace of mind.

This treatment may qualify for Land Tax Remediation Relief. Click here to find out more about potential monetary relief.

2. Cell Burial & Excavation

Cell burial comprises of moving Knotweed contaminated soil from one location on site, burying it in an excavated pit which is lined with a root barrier membrane, in a different position on the site. The excavated knotweed is encapsulated in a heat sealed, triple ply polyethylene impermeable sheet – with no access to sunlight, water or nutrients. The knotweed essentially rots away under the ground.

The burial requirements for Japanese Knotweed are as follows:

  • The Environment Agency recommends that the top of the burial cell should be a minimum of 2 metres below ground level.
  • The overall depth of the burial pit should be in excess of 5 metres deep. All root barrier seams are welded together forming an encapsulated cell from which the Japanese Knotweed cannot escape. Clean soil is then used to backfill on top of the cell.
  • To prevent accidental disturbance of the burial site, it is recorded on all site plans and future land owners should be made aware of the location.

This option once again has significant cost savings over traditional excavation or ‘dig and dump’ methods, with up-to 70% savings!

This treatment may qualify for Land Tax Remediation Relief. Click here to find out more about potential monetary relief.

3. Off-site removal and disposal of Japanese Knotweed Waste

The dug Japanese knotweed can be disposed of at a permitted landfill if there isn’t enough room on site. This method of Japanese knotweed excavation, on the other hand, is one of the more expensive methods but incredibly effective at allowing contractors to get to work.

We will manage the biosecurity on site and comply with EPA 1990 Duty of care guidelines
for the disposal of controlled waste.

This treatment will NOT qualify for Land Tax Remediation Relief.

Timetable for excavation of Japanese knotweed

Excavating Japanese knotweed is a quick job and once it’s done the site can be redeveloped. A typical Japanese knotweed excavation will usually take between two and five days, depending on the size of your site. If the site is huge, naturally the time frame will increase.

This is by far the quickest solution to completely eradicating this dreaded weed.

When it comes to Japanese knotweed, sometimes the only way to get rid of it is to dig it up and take it away

You might want to build something on a piece of land or as a property owner, just get your garden back. No matter what the reason is, Knotweed Services has years of experience digging up and getting rid of Japanese knotweed. Our expertise lets us make sure that only knotweed-affected materials are thrown away. This saves you time and money and gives you the confidence to move on.

Standard excavation procedure:

  • Conduct a Japanese Knotweed survey of the site for accurate identification and create a knotweed management plan.
  • Make sure the land isn’t contaminated in any other way and obtain landfill authorisation.
  • Hire a licensed waste hauler and make arrangements for excavation with the right equipment.
  • Undertake the excavation.
  • Provide and issue guarantees and\or provide an insurance backed guarantee.

The eradication of knotweed and Japanese knotweed waste, which is sometimes called “dig and dump,” it’s easy to make a mistake. Because all knotweed materials are considered controlled waste, everyone involved in the process has a duty of care. This includes the landowner, the specialist, the person who hauls the waste, and the place where the waste will be dumped. 

At Knotweed Services we handle everything for you with a professional touch, removing the stress of dealing with controlled waste and making sure you follow the law.

We may cooperate with the main contractor for them to provide machinery and manpower so that one of our certified Japanese Knotweed specialists can supervise the process, which can significantly decrease expenses.

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