Residential Japanese Knotweed Excavation

Japanese Knotweed Excavation

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Our Five Japanese Knotweed Excavation Methods

Excavation is an ideal solution to permanently remove knotweed, enabling change of land use plans and avoiding costly delays to building projects.

The appropriate excavation and waste disposal method will depend on on-site access, development timescales and the proposed development plan. We will advise you of the most appropriate remedial method(s) specific to your site. A Knotweed Management Plan (KMP) will be produced to detail the survey findings, proposed remedial works and quotation.

Japanese knotweed dig & dump

Full Excavation and Removal to Landfill

This provides an instant and impressive rectification method to the problem of Japanese knotweed. On completion the knotweed has been completely removed, allowing for unimpeded development of the area. Although the least sustainable of our methods, our approach and ethos puts the emphasis firmly on reducing quantities of waste removed to landfills, and hence cost to the customer. This is done via expert accurate identification of rhizome extent in the soils, ensuring complete removal while only removing those soils that possess the rhizome.

Reduced Level Excavation and Root Barrier Capping

To reduce the cost of excavation it may be feasible in some situations only to excavate to a set depth, and then use root barriers to cap and retain any further deeper knotweed contaminated ground. This is particularly cost-effective when the development formation level (the depth ground levels need to be reduced to allow for construction) is less than 1m deep. The proprietary root barriers are installed to fully contain the remaining knotweed contaminated ground and prevent its re-emergence. Expert installation and bonding ensure the complete integrity of the barrier. The contained non-excavated knotweed is therefore sustainably remediated on-site.

Japanese knotweed dig & cell burialDisposal of Excavated Knotweed Waste On-Site as a Cell Burial

As well as providing instant eradication of the knotweed, it allows fully sustainable disposal of the excavated waste on-site in accordance with Government RPS 178. The method requires a suitable size and location where the waste can be buried. The area can be sizable due to the logistics and specifications for burial, with soft landscaped public open space (POS) being among the desirable areas to place a burial. A deep receival pit is excavated, deep enough so that at least 2m of clean fill can be placed above the deposited buried knotweed waste. The knotweed waste is deposited within the pit, encapsulated in a root barrier, which is referred to as the cell. By residing 2m below finished ground levels it helps protect the cell against future accidental human disturbance or burrowing animals.

Sifting of Excavated Contaminated Waste

Sifting of the excavated knotweed waste soils can be used to lessen the volume of knotweed material within them. This method however cannot be guaranteed to remove all knotweed rhizomes and therefore the treated sifted soils will still need to be handled as potentially knotweed contaminated. The reduction in the growth potential following sifting makes these soils more re-useable on site, either in burial or relocation for monitoring. If they are removed from the site they will still be classed as controlled waste due to potential or known knotweed contamination.

Japanese knotweed dig & relocateRelocation of Excavated Matter

In some situations, it may be possible to relocate knotweed from an undesirable location to another location on-site where it can be treated long term with herbicides. This provides the instant eradication of the knotweed from its current location (to enable development for example), while sustainably retaining and treating the knotweed on site. The excavated waste is carefully double-handled over site along designated haul routes between the locations. Often only suitable for larger sites, the knotweed is relocated as a formed stockpile or landscape bund where any re-growth of knotweed is treated with herbicide. Once the knotweed growth has been controlled the relocated area can be carefully seeded or planted.

Land Remediation Tax Relief (LRR)

What is LRR?

Originally LRR was designed to encourage investment in land that was previously derelict or contaminated so it can be made purposeful again. It is a generous tax incentive intended to promote the remediation and development of land and buildings affected by Japanese knotweed or chemical contaminants such as Asbestos. It helps offset some of the cost of remediation services (which can include man-hours on the project, such as the Project Manager) through capital gains tax relief.

Who Can Claim?

with Japanese knotweed or contaminated grounds. The claimant must be the owner (adopter) at the time of the works and pay capital gains tax. Successful claims can result in capital gains tax refunds on qualifying work values of up to:

  • 150% for the land owners
  • 50% for developers

However, many property owners are either not aware of the scheme, or not clear of the qualifying criteria for making a claim, and could be missing out on this valuable cash-back incentive. Given that claims can be made that continue year-on-year for ongoing treatments, and can be claimed retrospectively for up to 3 years.

LRR is NOT to be ignored!

How Do I Make a Claim?

We can provide you with the best and most up to date industry information and advice on whether you can claim, and if so how to kickstart the process. Get in touch via

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