Often suitable to larger sites, or phased developments, relocation of the Japanese knotweed can prove both a cost-effective and sustainable remediation solution.
Excavation and Relocation
Current Legislation and Environment Agency (EA) guidelines permit for Japanese knotweed to be dug up and relocated to another area of the same site, as long as it doesn't cause risk of contamination spreading off-site. This activity can be used as a remediation method to instantly remove (eradicate) knotweed from one area of a site (i.e. that proposed for a new building) and relocate to another (i.e. Public Open Space) where it can be subjected to long term chemical treatment in-situ.
We undertake the excavation of Japanese knotweed either fully or to a reduced level (see 'Dig n Cap' page). The excavated knotweed material is then carefully transported (to avoid any loss in transit) over the site to an agreed relocation area. At the agreed relocation area the knotweed waste is received and consolidated to form a stockpile, bund or even cut into the ground so it resides at ground level.
Stockpile, Bund or Cutting
How the relocated knotweed contaminated ground is stored is at your discretion. There are usually three options:
- STOCKPILE: Usually used so that it can then be treated with herbicide, with the eventual aim of re-using this material on-site ( this material will always remain classed as controlled waste if removed from site). The stockpile should therefore be less than 1m in height so that herbicide treatment can be as effective as possible (i.e. buried knotweed rhizome that does not produce surface growth cannot be treated with herbicide).
- BUND: The knotweed spoil can be used to form a landscape bund. It will be accepted that there may be buried dormant knotweed material within the bund. It will also be accepted that the bund will be subject to long term chemical treatment of emergent knotweed (which may impact on plants and grass grown upon the bund).
- CUT AND FILL: It may be desirable to relocate the knotweed contaminated spoil so it resides at ground level. This is done by forming a cutting into which the knotweed is deposited. The arising clean spoil from the cutting formation can be re-used on site or removed from site as clean material or even as-dug topsoil with a commercial value!
The Knotweed Management Plan (KMP) should be used to record the position of the relocated knotweed with this being marked upon an as-built site drawing. This will help prevent potential future disturbance of these locations. If these works are part of a site development project the KMP should then be included in the Operations and Maintenance (O&M) Manuals.
The relocated Japanese knotweed should be subjected a structured programme of monitoring and herbicide treatment. Please see our 'Chemical Treatment' page for more information.
Land Remediation Tax Relief
Disposing of the excavated knotweed on-site is sustainable option for which Land Remediation Tax Relief (LRTR) can be claimed. A system of LRTR has been in place for several years, but the complexities of it, along with the lack of suitable publicity, have ensured LRTR has rarely been applied for.
In the 2007 Budget, the Chancellor announced a consultation into improving the tax relief system and to help redress this situation, which suggested any savings gained from scrapping Landfill Tax Exemption (1st April 2010) will be transferred into LRTR instead. However, LRTR cannot be applied for if any material is to be disposed of off-site.