Japanese Knotweed Excavation East Midlands

Technician: Daniel Pellowe
Author: Elle Walton
Location: East Midlands
Size covered: 60 m2
Techniques: Excavation, Membrane barrier
Costs: Approximately £28,000

BACKGROUND

Knotweed Services (UK) Ltd were contacted by North Warwickshire Borough Council to organise a site survey on a piece of land they own on the side of the A5. The council have recently taken down a wall approx. 100metres long and within meters of where the wall was taken down, JKW had been found and identified. The plan was to excavate the area as soon as possible as they had fencing contactors scheduled to erect a new acoustic fence to reduce the noise of the traffic from the A5. Due to immediate plans, the only option was to excavate. We aimed to eradicate the knotweed from the site within 2 days, minimising disruption.

SITE SURVEYS

At time of survey, I identified 60m2 of Japanese Knotweed on the side of the A5.
The infestation was mature and showed visible dead canes which were identified along a new installed fence line. I could see new growth around and beneath the new erected fence. The infestation was approximately 5 meters distance to the nearest habitable space. My plan was to conduct a full site excavation to remove all traits of the infestation so that work could commence as scheduled.

I informed our client at time of survey that to enable works, Highways would need to be notified due to close proximity of public footpath and barrier fencing would need to be installed to create a footpath on the road for members of the public. A tree that was approximately 10metred tall would need to be cut down, which again, permission would need to be sought to cut down prior to our arrival. All fence panels and the line of bricks (wall) would also have to be taken away prior or during the excavation. Due to a public footpath running along both sides of the infestation, permission would have to be sought to dig into the areas which hopefully (I informed) would not cause any issues. Due to the area being next to a main road, the hole once we excavated would need to be back filled due to Health and Safety.

A quotation was prepared informing of our plans to excavate highlighting that works would take approximately 2 days to conduct by our team at Knotweed Services.

MAPPING

The mapping stage of our plans is crucial to identify the location of the infestation. This not only helps to indicate the proximity to boundaries/habitable space & outbuildings and the associated RICS classification, but also identifying the possible migration (7m buffer zone).

See Site Map below:

TREATMENT

The next key step was to discuss plans with our client regards to proposals and timelines as this dictated the time we had to undertake and was able to deduce that a full site excavation and off-site removal was the most appropriate treatment option. All site operations (e.g. excavation & tree felling) occurring in the fenced zones were supervised by one of our trained operatives.

We then proceeded to excavate the infested soil. The soil were picked up by grabs that had retractable covers to pre-vent spreading to clear areas. Before leaving site all wagon tyres were treated with herbicide to create a chemical barrier. The waste was carted to a specialist contaminate waste landfill site. All working areas and plant used for the excavation were also treated after completion. This method provided a quick solution to Knotweed eradication which is why it was the most suitable for the client.

The harass fencing, skip and 8t plant an operative arrived at 8:30am on 31st October and 1st November ready for works to commence at 9am. Approximately 72 tonnes of contaminated soils were removed from site and approx. 120 tones of type 1 stone was backfilled into the hole covering 14x4sqm. The excavation took two days to complete and is now ready for the fencing contractors to attend and erect the new fence as scheduled.

INSURANCE BACKED GUARANTEES (IBG’S)

The customer was provided with information regarding the IBG and went ahead with Knotweed Express Policy. A booklet was also provided to the customer regarding what the Express IBG covers.

WHAT IS GPI’S KNOTWEED EXPRESS IBG?

The general principle of our Knotweed Express IBG is simple. It will honour the terms of the written guarantee, originally issued to you by your contractor, where that contractor has ceased to trade and is, therefore, unable to meet their guarantee obligations by carrying out or meeting the costs of any re-treatment works that may be required during their written guarantee.