A well-known housing developer local to Ebsford’s headquarters, was due to commence the build of a brand-new housing development before spotting the presence of an invasive species on site. Ebsford were called in to identify any potential risks and the most effective methods of eradication.
The site covered 13 acres of completely bare land which had been formerly used for industrial work, before undergoing demolition works years later. As the site had remained un-developed for a long period of time, this gave the land the opportunity to self-seed with saplings and native shrubs.
Our surveyor was greeted with dense Japanese knotweed stands approximately 3 metres tall, located on the north-western boundary. Its height and dense thickets indicated multiple crowns were present and its large canes, approximately 40-60mm in diameter, were clear characteristics that the infestation had been there for a number of growing seasons and was well established. Using historical satellite imagery, we were able to pinpoint the year it had taken hold and could see it had encroachedover the site boundary from an extensive infestation issue on adjoining land.
Japanese knotweed is legislatively complex and is the highest profile Schedule 9 species in the UK. It is a significant barrier for development, and it is paramount that the species is controlled or removed to prevent further spread that could affect and structures on a developed site.
A mechanical solution was advised as the best course of action to remove the species and surrounding contaminated soils, to prevent any regrowth where eight plots and subsequent gardens had been proposed.
The works began in August 2020, taking an initial scrape of the area to determine the extent of the Japanese knotweed rhizomes before excavating the area. The material was then transferred to a stockpile area, ready for disposal later on in the project. Layers of 200mm were removed and visually inspected by the site manager. Ebsford endeavour to reduce the amount of waste through careful excavation rather than assuming large buffer zones however in this instance it was deemed necessary to extend excavations slight beyond the boundary due to loose material to ensure it wouldn’t collapse.
As excavations deepened, the sides were battered to an angle of repose and made safe utilising site won material to form a gradient. Over 150m of root barrier membrane was installed which is is crucial in protecting the site from any re-infestation from the adjacent land. Approximately 100 wagon loads were removed to licensed landfill within a week reducing the delays to our clients schedule.
The project was undertaken during the COVID-19 lockdown bringing us many challenges, the team were able to deliver the project to a high standard within less than 1 week.
