Japanese Knotweed Removal & Disposal
The excavation of Japanese Knotweed offers a solution where other options are not practical.
Excavation provides a practical alternative to herbicide treatment for the removal of Japanese Knotweed, though it must always be carried out in strict accordance with legislation. Landtech (UK) Limited has extensive expertise in the legal requirements surrounding excavation and disposal, giving clients confidence that every stage of the process is managed correctly and in full compliance with the law.
Excavation Methods
Japanese Knotweed Burial
- Burial provides an immediate solution for removing Japanese Knotweed from active areas of a site.
- Excavated Knotweed can be securely buried either in a proprietary root barrier cell at a depth of 2 metres, or directly at a depth of 5 metres where no barrier is required. Of the two approaches, burial at 5 metres is generally the most cost-effective option.
- Before any burial takes place, the local environment agency must be notified at least seven days in advance.
- The exact location of the burial pit should be clearly marked on site plans to ensure it is not disturbed by future groundworks.
- Burial pits must not be located beneath proposed buildings, and must be compacted in line with the site engineer’s design.
Japanese Knotweed Stockpiling
- Excavated Japanese Knotweed is placed on a specially designed root barrier to prevent regrowth or spread.
- The material is stockpiled on level ground, well away from watercourses, to avoid the risk of contaminated runoff.
- Stockpiles are usually built to a height of around one metre and must remain in place for at least five years – this allows three years of herbicide treatment followed by a two-year verification period.
- During this time, the stockpile is regularly treated with herbicide until it is declared free of Knotweed.
- Once confirmed clear, the treated material can be reused on-site as fill, but never for landscaping or removal off-site.
Japanese Knotweed Removal to Landfill
- An immediate Japanese Knotweed removal solution but by far the most expensive.
- This may be the only solution where there is no suitable location for a burial pit or stockpile.
- Under the Environmental Protection Act; Duty of Care Regulations 1991, cut Knotweed material and soil containing rhizomes must be disposed of as controlled waste. Furthermore, allowing the plant to spread onto neighbouring land can result in litigation for damages.
If you are considering removing to landfill, please read the following very carefully: Landfill sites require soils analysis before accepting the material. Obtaining the correct waste classification is essential. This is a specialised area which Landtech (UK) Limited has great expertise. Most landfills will not accept material based solely on a WAC (Waste Acceptance Criteria) test. Failure to carry out the correct tests can potentially make some sites uneconomic to develop. The way in which sampling is planned and the samples analysed needs careful consideration.
Landfill Tax is also a very important consideration. All green and organic waste must be separated and in some cases topsoil handled separately. Failure to do this will attract the high rate of landfill tax.
Example Sites We Have Worked On
SITE A: Where we obtained four different waste classifications in order to send it to four different tips to produce the most economical solutions.
SITE B: Where the Japanese Knotweed was contaminated with asbestos. By using the correct analysis methodology and on-site monitoring during the works, we reduced the cost of the remediation of the site by £550,000. We worked in conjunction with the Environment Agency (EA) and the Health and Safety Executive (HSE) to obtain prior approval, as this was the first time these waste combinations had been managed.
Development Site Management
We create tailored removal and management programmess to suit the specific needs of each site, taking into account budgets, timescales, and development plans where necessary. Our professional service is supported by a 10-year insurance backed guarantee, ensuring both effective removal and long-term peace of mind.
Japanese Knotweed can cause costly delays on large development sites, particularly when work is in progress. However, it is possible to relocate the Knotweed to a quarantined area of the site for treatment later, or remove it to a landfill site. Commercial clients who need a Japanese Knotweed removal program, can request a survey to establish the problem and risk, and from there be guided through the options to determine the best solution.
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