Japanese Knotweed Removal Guidance: Expert Advice

Japanese knotweed eradication is a huge issue facing the development and construction industries, and it is one where relatively little is known for such an important issue, and the advice given can be confusing. However, the problem of Japanese knotweed removal is a clear one.

The weed is now thought to affect an area roughly the size of London and DEFRA has placed a conservative total cost of Japanese knotweed removal at £1.56bn. Its tall height with soft green smooth heart-shaped leaves, pleasant bamboo-like stems with purple streaks, and small creamy white flowers in late summer, made its introduction to the UK entirely understandable. However, developers must now be cursing botanical enthusiasts who introduced this invasive weed as an ornamental plant in the mid nineteenth century. This knotweed’s original habitat in the harsh volcanic areas around Mount Fuji in Japan means that in the UK it outcompetes native vegetation. It grows very quickly, is very hardy, growing in harsh disturbed conditions, and can regenerate from very small amounts of material. This makes removal very difficult and the spread of this invasive weed can be very fast. However, the real problem with the plant’s impacts is because it damages drains, walls, and can even grow through concrete floors; thus meaning the removal of the weed is essential before development begins.

It is important to understand that any Japanese knotweed eradication solution must take account of applicable legislation and relevant guidance. The main UK legislation to be aware of includes:
• The Wildlife and Countryside Act 1981, makes it an offense to spread Japanese knotweed in the wild.
• The Environmental protection act 1990, and Duty of care regulations, 1991, make any Japanese knotweed contaminated soil controlled waste.
• Third party litigation is also important, where you can be sued for costs and damages if you allow Japanese knotweed to spread from your property.
The Environment Agency also provides useful advice on Japanese knotweed removal in their code of practice. However, the Environment Agency still only gives general advice. For example, they state when excavating Japanese knotweed that the soil around it should be excavated to a 3 metre depth and a 7 metre radius. This would result in a huge amount of material removed and is very costly. Expert advice and professionally experienced Japanese knotweed removal services can deal with the infested material and take a much smaller amount of soil offsite, resulting in huge cost savings.

If you find Japanese knotweed on site it is vital to take action quickly as the problem of Japanese knotweed removal will not go away and will only get worse. Firstly, it is essential that any contaminated areas are marked out. These areas should be disturbed as little as possible, and a buffer around them marked out too to take account of the extensive roots. All site operatives should be made aware of the requirements of the weed and their responsibilities to not spread it. Any machinery that leaves areas with Japanese knotweed should be thoroughly cleaned within a designated area. The solution to Japanese knotweed removal is not a simple fixed strategy. The solution should be sought from experienced professionals who can advise and provide a bespoke solution tailored for the site requirements and client’s needs. This solution will be one that best fits all requirements, is cost effective, and efficient whilst taking account of all parties involved and applicable legislation.