In circumstances where time or location are limiting factors for achieving effective control of plant infestations then traditional techniques can be unsuitable. In such circumstances there are a number of “engineered” solutions that can be deployed which all involve the controlled mechanical removal of the plant and rhizome material and the remediation of the soil. On sites where there is sufficient space then the contaminated soil and plant material should be carefully relocated to a designated section of the site, away from any risk of future disturbance, and a monitoring programme deployed for the new location to ensure no regrowth occurs over the following years. If regrowth does occur then a traditional control programme can be employed in the new location.
Another option involves removing the main above ground plant material, the on-
In the case of off-site remediation the intention is to remove all plant material and contaminated soil off site after separation, for safe and controlled disposal. This option may be necessary in situations where development is taking place on a small or difficult sites, where there is going to be full site coverage, or where ground conditions and substructure design cannot be adapted to accommodate the residual spoil. In the case of Japanese Knotweed, for example, to ensure that all viable plant material is removed it is generally necessary to excavate a minimum of 7m in all directions horizontally from the perimeter of the infestation, and to a minimum depth of 3 to 5m. Having to draw this volume of soil off site, with the attendant transport costs, biosecurity risks and the limited number of licenced contaminated soil repositories in Ireland, means that this is probably the least favourable solution to deploy. Nonetheless there are many cases where it remains the only viable option.