Japanese Knotweed Treatment & Disposal
King’s College Hospital Development Site
The Fetal Medicine Foundation, via their Project Manager Buro Four appointed ATG Group as a specialist contractor with responsibility for the eradication of Japanese Knotweed present on their site at Windsor Walk, London SE5. This prestigious project (valued at £20,000,000) was to develop a Fetal Medicine Centre of Excellence, to be occupied by King’s College Hospital and involved the partial demolition and refurbishment of the existing terrace houses on the Windsor Walk site.
ATG Group comprehensively surveyed the site, ascertaining estimated volumes of all Japanese Knotweed stands present and their coverage over the site. From this initial survey, a remedial methodology was designed, with all prospective works supported by ATG’s comprehensive indemnity insurances and warranty cover.
During the site survey and inspection of the canes, the colour and composition of the rhizomes indicated that the Knotweed was still highly active, critical as Japanese Knotweed propagates via its root (rhizome.) In order to fully eradicate Knotweed, one must ensure the rhizomes are no longer active, irrespective of the condition of the surface growth. Furthermore, the proximity of the Knotweed to the existing terraced structures was of concern as Japanese Knotweed can compromise the structural integrity of buildings, as a result of strong rhizome growth.
Over the last decade ATG have project managed numerous sites impacted by invasive species and understand the critical importance of ensuring that any treatments are site specific, methodical and comprehensive. This experience has informed the production of our remedial method design, which underpins the overall remedial process, supports our client’s legal obligation to remain compliant with all statutory legislation, whilst adhering to sustainable environmental practices.
At ATG we pride ourselves on delivering innovative remedial designs that are responsive to the specific commercial and environmental pressures and challenges faced by our clients.
Japanese Knotweed Contamination is often seen as a time consuming hurdle to the redevelopment of such sites, and Japanese Knotweed cannot simply be ‘Digged and Dumped.’
The works incorporated the clearance and careful removal of surface Knotweed and disposal off site at a licensed facility. This was followed by the thorough excavation of contaminated soils, where the area was ‘over-dug’ to ensure complete exposure of rhizome.
All plant tissue was removed and contaminated soils were processed and screened through an Allu Bucket to remove any large fragments of rhizomes and the remaining soil mass was treated with the Eraginate herbicidal formula which would render any remaining knotweed fragments unable to sustain growth. The herbicidal formula would also act to sterilise the soils.
Knotweed vegetation and root matter was disposed of off site and a Root Barrier membrane installed along the excavated area to prevent potential future regrowth – safeguarding the retained structures on site. All treated soils were backfilled and the site was left in excellent condition, allowing the construction timetable to progress.
ATG’s experience in the remediation of Japanese Knotweed impacted areas informed our specialised remedial methodology. The treatment of the soils with ATG's ‘Eraginate’ herbicide and the removal of the rhizome material allowed the disposal of materials from site to a licenced recycling facility at a significantly lower cost to the client, realising significant savings.
Based on the treatment process on this site, we are confident that all conditions have been met and no treated knotweed rhizome material remains viable in the soil. The operation to remove, treat and prevent further spreading of the Knotweed in this site area has been executed with the greatest of care and with the best method for this site, under these project circumstances.
The Client also benefits from peace of mind with ATG’s high level of warranty for all on site works.