Commercial Japanese knotweed removal on development sites

• Chemical treatment
• Physical Removal
  • Xtract™
  • Stockpile & treat (Bund method)
  • Supervised Dig & Dump

There are legal, technical and financial issues that must be addressed.

Japanese knotweed is simply one of the things in life that should not be brushed under the carpet with a botched attempt at removal, unless of course you want to incur delays and major expense at a later stage. While it may seem like a large task to remove Japanese knotweed, you are better off sorting the problem out at the beginning, before any works start. We have a number of Japanese knotweed removal methods that can be used to ensure complete removal.

Many attempts at “controlling” Japanese knotweed are counterproductive. They kill off some of the plant, leaving the majority of the rhizome system below ground in a state of temporary dormancy, ready to resurface when you least expect it. There may be no obvious evidence of the knotweed above ground, but you can be pretty sure that viable rhizome remains. This is what we see in a lot of DIY attempts. The plant looks dead, but it is in fact dormant.

Imagine a development site where viable knotweed rhizome remains hidden in the ground, possibly to a depth of 2m or more, having laterally spread into areas you might think are unaffected. Once you disturb these soils whether by ignorance, accident or intentionally, you would almost certainly fragment and spread the knotweed rhizomes to other areas of your site. This would significantly increase the scale of the problem, and hence the cost of remediation.

All too frequently we are called in to help with removing Japanese knotweed, because other less experienced operators have failed to completely kill off the knotweed.

Make sure you understand the law before tackling Japanese knotweed. If you caused the knotweed to be spread off-site, you could find yourself at the wrong end of criminal proceedings under either the Wildlife and Countryside Act 1981, or the Environmental Protection Act 1990 “duty of care”. Offences under these Acts can result in custodial sentences. If you consign knotweed infested soils off site other than strictly in accordance with these legislative requirements, whether intentionally or not, you will run the risk of prosecution.

Botched attempts at treatment or removal make it considerably more difficult for professionals to completely remove the knotweed for you. Trying to find and remove every piece of viable rhizome is akin, albeit with a difference, to finding and removing all fragments of asbestos that may or may not be in the ground. The big difference being that asbestos does not grow, so usually stays buried out of sight, whereas viable Japanese knotweed rhizomes are living and will grow to the surface, pretty much irrespective of what is put in its way. Imagine it growing through your asphalt driveways/roads just as you are nearing completion of the build – it would have pretty dire consequences on the saleability of the property and in many cases financing.

Where knotweed exists, either within the curtilage of a property or on adjoining land, virtually all UK banks and building societies will refuse lending until it is removed and insurance-backed guarantees (IBGs) “from a reputable company” are in place. We know because we receive lots of calls from distressed vendors of properties who have usually just lost a buyer due to funding being refused. Please don’t think that funding will never be granted – once an insurance-backed guarantee is in place, the lending should be granted.

Not surprisingly, the financial consequences can be pretty steep. It is not just the cost of remediation you should consider. Many main contractors/developers will be reluctant to take on the risk associated with a site infested with Japanese knotweed. Those prepared to take the risk inevitably price the risk, which of course gets reflected in the purchase/tender price.

If the risk remains with the client and knotweed is subsequently found, then additional costs during the construction stage are almost inevitable to cover professional fees, considerable management time, additional site precautions and delays to the contract, plus of course the cost of remediation. The cost of remediation in these circumstances escalates due to the urgency, as the more cost-effective alternatives to dig & dump may not be available.

Removing the problem prior to letting the main contract is the best solution all round.

It’s possible that your company will be eligible for Land Remediation Tax Relief.

Land Remediation Tax Relief, known as LRTR, was introduced under the Finance Act 2001 for all companies involved in the remediation of contaminated land, whether for commercial or residential purposes. For corporate bodies LRTR is available at 50% for developers (ie those trading in property), whilst property investors or owner occupiers can benefit from 150% relief against their qualifying expenditure. If you are not a corporate body the tax relief is not available.

The legislation currently permits any expenditure that prevents, minimises, remedies or mitigates the risk of any harm being done to people, property or the wider environment. The harm, or potential to cause harm, must be as a result of a substance or substances in, on or under the land to be applicable. “Substances” include for example heavy metals, hydrocarbon contamination and, arguably Japanese knotweed.

Environet works with specialist Tax Consultants to claim the tax that is rightfully yours.

Landfill Tax is now charged generally at the standard (higher) Landfill Tax rate for disposal of contaminated soils following the removal of the exemption in 2008, significantly increasing the cost of the Dig & Dump solution.

Environet have various Japanese knotweed removal methods, such as Xtract™. This provides on-site remediation of land infested with Japanese knotweed that not only avoids the punitive costs of Landfill Tax but is also eligible for relief under LRTR.

Contact us today on 01932 868 700 for further information.