Residential Japanese Knotweed Excavation

Japanese Knotweed Excavation

Excavating Japanese knotweed provides an instant eradication solution backed by guarantee.  Excavating knotweed is the alternative method to herbicide treatment, which is a long-term programme to control knotweed but will not completely eradicate it.

Japanese Knotweed is an invasive and extremely resilient plant which has an underground rhizome system. The extent of the underground rhizome spread, and therefore the knotweed contaminated ground is considerably greater than it appears from the aerial growth (shoots, stems and leaves).

Our experience and expertise ensures accurate identification of the rhizome in the ground, which ensures complete removal with minimal arising waste volumes.

Japanese Knotweed Removal

The appropriate excavation and waste disposal method will depend on access (restrictions, or presence of trees and services), development timescales and the proposed development plan. For example on-site sustainable methods such as burial may be appropriate where there is space to bury waste, such as public open space (soft landscaping areas).

We will survey the site and advise you of the most appropriate remedial method (or methods). A Knotweed Management (Remediation) Plan document will be produced to detail the survey findings, proposed remedial works and works quotation.

We can undertake the following methods of knotweed remediation to resolve a problem that, if handled the wrong way, can end up being a long-term problem for the developer and land owner:

Japanese knotweed dig & dumpJapanese Knotweed Dig and Dump

This provides instant eradication of knotweed, although it’s the least sustainable method of knotweed eradication as the arising waste is transferred to landfill. Our approach and ethos puts emphasis firmly on reducing quantities of waste removed to landfill. We accurately identify the location and full extent of the underground knotweed rhizome system. This ensures that we only remove knotweed material and soils containing knotweed and not just clean soils (reducing the client’s costs).

All knotweed material and knotweed contaminated arising from these works is removed from site as ‘controlled waste’. This requires removal via registered waste carriers to a landfill site fully licensed to receive and dispose of Japanese knotweed. There will be a full waste tracking record on completion.

Japanese Knotweed Dig and Cap

Japanese knotweed dig & capOn construction sites the ground levels often need to be reduced before construction (installation of structural backfill and structures) can begin, this level of often referred to as the formation level. Where the formation level depth is less than the anticipated depth of knotweed rhizome there is an opportunity to carry out a reduced level dig of the knotweed. The knotweed is excavated to construction formation levels and then capped with suitable knotweed root barriers.

This reduces the volume of knotweed waste to be removed from site and hence cost to the client. The knotweed waste can either be removed off-site (as above for Dig and Dump) or disposed on-site via burial or relocation (see ‘Cell Burial’ and ‘Dig and Relocation’, below).

Land Remediation Tax Relief (LRTR) can be claimed for disposing of the excavated knotweed on-site. See more on this, below.

Japanese knotweed dig & cell burialJapanese Knotweed Dig and Cell Burial

This provides instant eradication of knotweed, and a sustainable remediation approach, where there is space on-site to accommodate a deep burial pit (i.e. in areas proposed for public open space). On-site disposal of the waste is often more cost effective than disposal of waste to landfill.

The excavated knotweed is buried deep on-site, with the waste encapsulated in root barrier (the cell) with the top of the cell residing at least 2 metres below finished ground levels as a precaution against future accidental human disturbance or burrowing animals.

The dimensions, depth and location of the burial are recorded with the Knotweed Management Plan (KMP) for the site. The KMP should be included in the Operations and Maintenance Manuals for any development site.

Land Remediation Tax Relief (LRTR) can be claimed for disposing of the excavated knotweed on-site. See more on this, below.

Japanese knotweed dig & siftJapanese Knotweed Dig and Sift

This will provide instant eradication of knotweed from its source location and a sustainable remediation approach, where there is space on-site to accommodate a burial or relocation of the treated (sifted) soils.

Sifting and Crushing techniques can be used to lessen the volume of knotweed material (or regeneration of knotweed) within excavated soils containing knotweed.

They cannot however guarantee to remove all knotweed material and therefore the treated soils will need to be buried on-site or relocated on-site so that they can be monitored. If they are removed from site they will still be classed as controlled waste.

Land Remediation Tax Relief (LRTR) can be claimed for disposing of the excavated knotweed on-site. See more on this, below.

Japanese knotweed dig & relocateJapanese Knotweed Dig and Relocation

Where there is sufficient space on site the knotweed can be excavated (and eradicated) from its source location and relocated to a more desirable (lower risk) location on site. Often suitable to larger sites, or phased developments, relocation of Japanese knotweed can prove both cost-effective and provide a sustainable remediation solution.

Excavated Japanese knotweed is carefully relocated over site (along designated and controlled haul routes) to another area of the same site. In its new location it is monitored and treated under a longer term herbicide treatment programme.

The dimensions and location of the relocation are recorded with the Knotweed Management Plan (KMP) for the site. The KMP should be included in the Operations and Maintenance Manuals for any development site.

Land Remediation Tax Relief (LRTR) can be claimed for disposing of the excavated knotweed on-site. See more on this, below.

Land Remediation Tax Relief

Disposing of the excavated knotweed on-site is a sustainable option for which Land Remediation Tax Relief (LRTR) can be claimed. Land Remediation Tax Relief (LRTR) can provide a 150% tax relief to help fund remediation costs. Relief on up to 10% of eligible costs for a developer and 30% for capital expenditure assuming a 20% tax rate.

If you don’t currently apply for LRTR on your projects please contact us for information on how you can claim for this on knotweed remediation works and any other applicable remediation works on site.

Contaminated or Hazardous Ground

Prior to removal of the knotweed waste from the site, the soil will need to be tested for the presence of any contaminates (other than knotweed). This verification is normally achieved via provision of laboratory soil analysis results from the site.

Certain thresholds of other contaminates such as heavy metals, petrochemicals or asbestos can class the waste as either ‘contaminated’ or ‘hazardous’. If high levels of contaminates are found (which classify the waste as ‘contaminated’ or ‘hazardous’) it may have a restriction on which landfills can take it and increase disposal costs.

If hazardous levels of contamination are found (such as asbestos) this will require further Waste Acceptance Criteria (WAC) testing, before it can be accepted by a licensed landfill for disposal.

Landfill Tax

Landfill Tax has been rising annually each year on the 1st April, and it is set to continue to rise for the foreseeable future.

The Government launched a Strategy for Sustainable Construction in 2008, containing several proposed waste disposal targets for the construction industry to achieve through a series of voluntary agreements and initiatives. A target of a 50% reduction in the amount of construction, demolition and excavation waste (including Japanese knotweed) going to landfill by 2012 was proposed, with an eventual target of zero landfill disposals for 2020.

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