The presence of Japanese Knotweed at a property can lead to severe land contamination and legal liabilities. When clearing Japanese knotweed from a location, the problem lies with the rhizomes of the plant, which spread rapidly and can require significant remediation efforts. Effective Japanese Knotweed removal methods are essential for residential property owners, commercial property owners, and commercial contractors who need to immediately use the land or develop it. Here, we define the methods available: Japanese Knotweed excavation, cell burial, and relocation. Average costs to remove Japanese Knotweed via the various methods, and the legal and environmental considerations of disposing of controlled waste can be found below.
Clearing Japanese Knotweed
The process of clearing Japanese Knotweed from a site starts with the consideration of the most appropriate method. Considerations here include the size and nature of the site (residential/commercial) and the budget available.
This most famous of UK invasive plant species, unlike some other plants, cannot be simply cut back to halt its growth. This invasive plant spreads through its extensive underground rhizome system, which can cause structural damage but will significantly impact the land. The rhizomes enable the plant to spread rapidly and create contaminated waste that is more expensive to dispose of.
Effective removal of Knotweed involves excavating soils impacted by Japanese knotweed rhizomes. The costs involved include labour, transportation, and the disposal of controlled waste, which must comply with legal requirements across the UK. Proper waste management procedures are essential to avoid severe environmental impacts and potential legal penalties.
Removal Methods:
Do You Need a License to Remove Japanese Knotweed?
The act of removing Japanese Knotweed from the ground does not require a license. However, handling and disposing of Knotweed plant material are highly regulated due to its classification as ‘controlled waste’. Improper disposal can lead to new infestations and legal issues. Given these complexities and the potential legal ramifications, it is highly recommended to seek professional assistance rather than attempting to remove Knotweed yourself.
Controlled Waste
All Japanese Knotweed plant material, including canes, stems, and rhizomes, can be classified as ‘controlled waste’ under the Environmental Protection Act 1990. This type of waste must be disposed of at licensed facilities. Additionally, the waste carrier must be registered, as transporting controlled waste without adhering to regulations can result in legal penalties.
Note: Careless disposal methods, such as binning, composting, or dumping Knotweed, can lead to further infestations and severe legal consequences.
Legal and Environmental Considerations
The management and disposal of Japanese Knotweed are regulated under several key pieces of legislation:
- Wildlife and Countryside Act 1981: It is an offence to plant or cause Japanese Knotweed to grow in the wild. This includes actions that may lead to its spread, such as improper disposal of contaminated soil or plant material.
- Environmental Protection Act 1990: This act classifies Japanese Knotweed waste as ‘controlled waste’, which must be handled and disposed of in accordance with regulations to prevent environmental contamination.
- Anti-social Behaviour, Crime and Policing Act 2014: Community Protection Notices can be issued to individuals or organisations to control Japanese Knotweed if it is having a detrimental effect on the quality of life of others.
Failure to comply with these laws can result in significant fines and legal action. It is essential to use professional services that are well-versed in these legal requirements to manage and dispose of Japanese Knotweed properly.
Japanese Knotweed Removal Methods
There are several methods for removing Japanese Knotweed, each with its own advantages and costs. The three primary options are excavation, burial, and relocation. Each method is designed to effectively manage and dispose of Knotweed while complying with environmental regulations.
Japanese Knotweed Excavation
Japanese Knotweed excavation is a thorough and effective method for the removal of this invasive plant. This process, often referred to as ‘dig and dump,’ involves the mechanical removal of Knotweed plants along with the surrounding soil to ensure all rhizomes are extracted. Excavated material must be transported to a licensed landfill.
Typical Excavation Process:
- Site Survey and Management Plan: Conduct a detailed site survey and develop a Knotweed Management Plan (KMP) to outline the excavation strategy.
- Landfill Authorization and Waste Carrier Registration: Ensure there are no other forms of land contamination and secure landfill authorization. Use a licensed waste carrier for transporting the excavated material.
- Excavation and Site Hygiene: Use appropriate machinery for excavation, overseen by a qualified Japanese Knotweed Clerk of Works to maintain site hygiene and prevent cross-contamination.
- Post-Excavation Treatment and Monitoring: After excavation, conduct treatment and monitoring of the site and neighboring lands to ensure complete removal and prevent regrowth.
- Insurance Backed Guarantees: Provide insurance-backed guarantees for up to 10 years, ensuring long-term protection against Knotweed regrowth.
Advantages:
- Immediate and Thorough Removal: Excavation and removal eliminates knotweed immediately whereas herbicide treatment controls the problem over a longer period of time.
- Suitability for Development Sites: This method is ideal for construction sites or areas where Knotweed poses a significant threat to structures.
Considerations:
- High Cost: Excavation is generally more expensive due to the need for specialized disposal and the extensive labour involved.
- Compliance: All Knotweed material must be disposed of at licensed facilities to comply with environmental regulations.
Japanese Knotweed Burial
Japanese Knotweed on-site burial is a technique that diverts waste from landfill and is sustainable, quick, and cost-effective. This method involves burying the Knotweed at a depth of at least 5 metres, unless you encapsulate it with a root barrier membrane to prevent regrowth, in which case it can be buried to two metres. This method is often used when excavation and off-site disposal are not feasible.
Method:
The Knotweed is buried in a cell lined with a root barrier to prevent the rhizomes from growing through the containment. The top of the cell must sit at a minimum of 2 metres below the finished level.
Advantages:
- Cost-Effective: Burial is typically 30% cheaper than using off-site disposal, as it avoids the need for licensed transportation.
- Sustainability: This method is sustainable as it keeps the Knotweed-impacted waste on-site.
- Low Residual Risk: There is a very low residual risk of future Japanese Knotweed issues.
Considerations:
- Site Suitability: The location for burial must be identified before starting the Knotweed remediation programme – 7M from an adjacent landowner’s site.
- Compliance: Adherence to RPS 178 – a regulatory position statement requiring a management plan and compliance with specific conditions when burying invasive non-native plant material on site.
Japanese Knotweed Relocation
On-site relocation, sometimes known as creating a stockpile or bund, involves moving the Knotweed to a designated area on the same site. The Knotweed is then managed in this contained area to prevent its spread. This method can mean a smaller environmental footprint when compared to off-site disposal and can often be quicker to implement. However, it does require the long-term use of herbicides.
N.B. Relocation is only suitable for specific projects that have space for relocation of removed plant material elsewhere on site.
Method:
Knotweed material is relocated to a controlled area within the same site. This area is isolated with barriers to prevent spread and is monitored regularly. Over time, the Knotweed waste is treated with herbicides, leading to the eventual death of the infestation. It is recommended bund shape and size is designed to maximise herbicide efficacy. Soils should be turned periodically using and excavator to expose further new growth to herbicide treatment.
Advantages:
- Environmentally Friendly: Relocation is a more sustainable option as it keeps the knotweed waste on-site.
- Cost Savings: Often less expensive than off-site disposal and burial as there are no off-site transportation or root barrier costs.
- Quick Implementation: Can be quicker to implement compared to other methods.
Considerations:
- Space Availability: There must be sufficient and suitable space on-site for the relocation.
- Planning: Requires more planning than off-site removal and needs to be considered early in the remediation programme.
- Hygiene Systems: Strict hygiene systems must be adopted to handle the controlled waste properly.
Average Cost to Remove Japanese Knotweed
The cost to remove Japanese Knotweed can vary widely based on the chosen method, the size of the infestation, and the specific site conditions. Here is a brief overview of typical costs:
- Excavation and Disposal: £8,500 – £20,000+
- Cell Burial: £6,000 – £15,000+
- On-site Relocation: £4,000 – £10,000+
Note: While these costs provide a general range, actual costs can vary based on factors such as accessibility of the site, the extent of the Knotweed infestation, and local disposal fees. It’s advisable to get quotes from professional Knotweed removal services to understand the specific costs for your situation.
DIY vs. Professional Services
While small, isolated infestations of Japanese Knotweed appear to be manageable acting yourself isn’t advised. Most cases require professional intervention to ensure complete and safe removal.
Factors to consider:
- Improper treatment risks: DIY treatments can cause Knotweed to go into hibernation, making future professional treatment more difficult and costly. Knotweed in hibernation may seem inactive but can regrow vigorously once conditions improve.
- On-site biosecurity: Professionals ensure that Knotweed or any other invasive species on-site do not spread further within the location or to neighbouring properties. Even a small fragment of Japanese Knotweed rhizome can start a new infestation, highlighting the need for stringent biosecurity measures.
- Disposal of plant material: Japanese Knotweed material removed from the ground cannot be disposed of in garden waste. Proper disposal methods must be followed to prevent the spread of this invasive species.
- Documentation and legal compliance: On sites where Japanese Knotweed has been present, having proper documentation is crucial. At the time of sale, buyers or their solicitors will want to see the Knotweed management plan and any related guarantees. Failure to provide this documentation could impact the sale, reduce the property value, or make it difficult for the buyer to obtain a mortgage.
Using professional invasive weed services for consultancy and removal ensures compliance with legal and environmental regulations while avoiding unnecessary costs from over-removal or the risk of knotweed regrowth due to inadequate removal. Specialists also provide insurance-backed guarantees for long-term management.
PBA Solutions offers a consultancy-led approach, advising on early-stage solutions, developing customised knotweed management plans, and creating templated knotweed specifications for clients. We collaborate flexibly with developers and builders, offering cost-effective knotweed remediation services with guarantees, quantifying works and providing detailed methodologies. Our flexible approach allows clients to manage their own excavation and landfill, whilst still obtaining a guarantee on the work undertaken.
Contact Us Today
For professional assistance with the identification, treatment, and removal of Japanese Knotweed, contact PBA Solutions. As accredited PCA invasive weed specialists and experts in the supply and fitting of root barriers, we offer cost-effective solutions to protect boundaries and encapsulate waste material on-site. Call our experienced team at 0203 174 2187 or 01202 816134 for tailored advice, site surveys, comprehensive management plans, and insurance-backed guarantees.