As management consultants to the construction industry, and therefore with clients investment interests at heart, Birmingham based Wakemans Limited, when carrying out site surveys, ensures that investigations are carried out to check for a little known scourge of the property industry. Like a huge blanket, it scrambles and tumbles on its daily quest to cover every inch of virgin soil it can find. It is also able to grow through walls, tarmac and concrete.
Japanese knotweed, scientific name, Fallopia Japonica was introduced to Europe as an ornamental and fodder plant in the early 19th century. It is the most invasive piece of greenery in Britain and can add as much as £50,000 per hectare to project costs for complete eradication. Site surveys do not always detect its triffid like presence, and indeed its rapid rate of growth means it may not even be present until after an initial site survey.
The Japanese knotweed is classed as U2 unacceptable material. Other Class U2 material includes poisonous wastes, asbestos and other contaminants. This weed establishes dense tall strands, that can be impenetrable and taller than head height. Spraying with the highest permissible dose of an effective pesticide such as Monsanto Roundup, will, say the company, only guarantee an 80% clearance per application. Therefore, a contaminated site has to be inspected each June and following September, with particular attention being paid to areas of soft landscaping, block paving and any porous paving.
Many consultants are totally unaware of the existence of the Japanese Knotweed. It grows so quickly that it can appear on a site and completely cover it within a very short time. Some parts of North America actually have signs up on the State border, asking people to be careful not to bring in Japanese Knotweed, as once settled it's growth rate is prolific. In 1981, the Wildlife and Countryside Act made it illegal to spread Knotweed.
So next time you are considering a new development, stop and think, is there a Japanese knotweed fragment on your site or even a neighbouring site?
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