Knotweed excavation & burial methods
1. Excavation & licenced transfer to Landfill
Excavation & Licenced transfer to Landfill if the site has no space or facilities for on-site remediation (screening, burial, incineration see below) and/or the client wants a simple off-site solution, removal of waste soils to landfill may be the only available option.
2. Excavation & on-site cell burial
One way to avoid landfills is on-site burial and this is often done on larger sites. Burial to depths of 5m+ do not need encapsulation but shallower burial cells (minimum 2m depth capping) can be formed using root resistant barrier membranes.
3. Excavation & Soil Screening
In both the above cases the volume of soil can be reduced using soil screening techniques (which removes, via sieving, most larger rhizome fragments) but the screened soil will still contain smaller fragments so the ‘Controlled waste’ soil classification doesn’t change. Despite this, the Government’s Regulatory Position Statement RPS 178 states that screened soil can be used for landscaping as long as locations are defined and accessible for monitoring and/or future treatment.