Strategy Overview: Mechanical Remediation Strategy – Excavation (via vacuum excavation) and off-site disposal, with provision of membrane barrier.
JKSL were instructed to assess the extents of Japanese knotweed on the A44, Wolvercote, and to provide an appropriate remediation strategy to facilitate development which included the construction of a bus lane and cycle lane.
During JKSL’s initial inspection, horsetail was also recorded within the footprint of the development. Although horsetail is native, it is still considered to be invasive, with it causing potential defects to hardstanding areas (such as tarmacadam pavement, driveways, cycleways etc) when present in high plant numbers.
Due to the proposed development directly affecting the Japanese knotweed (and horsetail), a mechanical remediation strategy option was required to be implemented whereby the associated impacted material is excavated/removed, to ensure the problem was not exacerbated further by spreading propagules (i.e. a vegetative structure that can become detached from the main plant and give rise to a new plant) around site and off-site, and to minimise the risk of future defects on the proposed hardstanding areas.
Due to limited space on site, the excavated impacted material was disposed off-site at an appropriate licenced facility (i.e. could not be retained on site).
Excavation extents were restricted due to the presence of services in the proposed dig (included BT, other communications, gas, water and electric). JKSL completed the works in accordance with HSG47 and safe digging practices.