Site Capping is a fast way to eradicate Japanese Knotweed while keeping volumes of waste to a minimum.
Minimised excavation
Site Capping removes knotweed to the construction foundation level*, minimising the depth of excavation and the resulting volume of waste. The waste can either be sent to landfill or buried on site.
*The construction foundation level is the maximum depth of excavation required before construction begins.
Root barrier
To prevent any regrowth of the knotweed, contaminated ground is capped after excavation with a special root barrier. The root barrier used will usually be porous to allow the site to drain freely.
The root barrier will either overlie the area or be bonded to adjacent structures. Sometimes, sand-blinding layers are installed above or below the root barrier to prevent it puncturing through construction activity.
To prevent future accidental damage, the root barrier cap will be recorded on the site’s Knotweed Management Plan, recording the depth and location of the barrier.
Disposal
Japanese Knotweed waste is classed as “controlled waste” and must be disposed of in line with the Duty of Care Regulations 1991 under the Environmental Protection Act 1990.
There are two options for disposing of knotweed waste under the Site Capping method: removal to landfill or on-site disposal.
Landfill disposal
By minimising the amount of controlled waste, we’re actively helping to reduce landfill levels. This is better for the environment and conforms to the Environment Agency’s ‘Knotweed Code of Practice 2013’, which requires quantities of knotweed waste removed to landfill to be substantially reduced. The Government is also seeking to reduce landfill levels, with a target of zero landfill disposals by 2020.
Less waste also means fewer loads to transport to landfill and therefore fewer transportation and landfill tax fees, saving you money.
On-site disposal
This is a more sustainable method of disposal, as no waste is sent to landfill. The waste is either buried or relocated and Land Remediation Tax Relief can be claimed. On-site disposal is only possible if there is sufficient space on site for burial or relocation of the waste. See the Dig and Cell Burial page for more information on burial methods.
