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Knotweed eradication


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Please browse through some of our case studies.
Case Study 1 - An englishman, welshman & irishman went into...
...a site in Scotland to eradicate some stands of Japanese Knotweed. In this 'international' project the english and welsh were represented by staff from knotweed specialists GroundCoverDBM, working on behalf of irish civil engineering contractors Wills Bros for scottish client Highland Council. The project, in Inverness, was GroundCover's most northerly yet. Knotweed eradication using our Klaro on-site process will facilitate a new road junction being built as part of the University development.

GroundCoverDBM works throughout the UK, because knotweed is found throughout the UK, but unlike knotweed we do not shut down for the winter - just the rugby internationals!

Case Study 2 - Knotweed eradication clears way for school
GroundCoverDBM's on-site eradication services proved invaluable to main contractor Balfour Beatty when they found knotweed on the site of a secondary school renewal project in Southwark, south London. Our survey identified 425m³ of infested material which would have been removed to landfill at great expense, but using Klaro gave a significant cost saving AND avoided HGV movements in central London during the Olympic period.

GroundCoverDBM moved its specialist equipment into the site in the middle of the night to avoid the lorry ban. The work was then completed on schedule, allowing construction to proceed to plan. Our site report and eradication plan were used by the main contractor in support of his BREEAM assessment.

Case Study 3 - Knotweed in the way
Widening the narrow A487 trunk road meant removing stands of Japanese Knotweed from a very narrow project corridor, squeezed between houses, a railway line and protected wildlife sites. Removing the infested material to landfill meant haulage across Wales at huge cost. Main contractor Carillion came to GroundCover for help.

Using our Klaro process, we excavated the knotweed stands and processed the infested material which Carillion could then re-use. The work was carried out alongside the road without further disruption to the traffic or to the railway, and the site was handed back to Carillion for the next phase of work.

Case Study 4 - Knotweed removal clears way for new Health Centre
Japanese Knotweed was growing in a number of locations on a small site alongside main road into the town.  The architects contacted GroundCoverDBM for help, as  there was no space to reposition the building.  Adjacent houses, an electricity main and roads on three sides meant that there was no room to relocate the knotweed or construct a disposal cell.  The cost of removing approximately 800m³ of knotweed-infested soils to a licensed landfill was prohibitive.
GroundCover DBM excavated the infested material and processed it using our Klaro process. The processed material was used to backfill the voids.  Where the electricity main prevented excavation, a root barrier was inserted to protect the cable and the site.

By solving the problem in two weeks, at less than half the cost of landfilling, GroundCover DBM helped keep the project on programme and budget.  800m³ of waste generation was avoided, and over 2 ½ tonnes of CO2 saved.
Case Study 5 - Fast turn around enables business park development
The area of land earmarked for development into a Business Park has suffered from years of neglect. Surveys identified 10 stands of Japanese Knotweed, 3 in the Phase 1 area. The cost of disposing of the Japanese Knotweed-infested soil to the nearest licensed landfill, some 100 miles away, was calculated as £300,000. Contractor Alfred McAlpine approached GroundCoverDBM for a solution.
Using our Klaro process, we cleared the first phase in 5 weeks, allowing the development to proceed on schedule. The mobility of the processing unit allowed GroundCoverDBM to reschedule and relocate work to accommodate the main contractor’s changing programme, without additional cost. A 3 year herbicide treatment programme for stands on later phases will achieve eradication at modest cost.

Our solution avoided some 650 lorry movements through the town, saved some 65 tonnes of CO2 emissions, and cost less than half as much as the ‘dig and dump’ option.
Case Study 6 - Athletes Village development, Stratford
When Japanese Knotweed-infested soils from the Channel Tunnel Rail Link project were placed in containment cells as part of the Stratford land-raising works, it was expected that development of the land would not take place for years. The Athletes Village development changed that completely. The developers of the Athletes Village were concerned that knotweed rhizome in soils disturbed by piling operations could regenerate and spread knotweed around the site.
Developer Bovis LendLease has a company target to reduce overall carbon emissions by 20% (based on 2008 baseline) and waste by 70% (based on 2007 baseline) by the end of 2010. Taking the material to landfill would work against both of these targets and so an on-site, rapid solution was needed. Bovis LendLease turned to GroundCoverDBM and its Klaro process.

Working within our EA Licence and BLL’s site working procedures, GroundCover has treated over 5000 m³ of excavated soils. Following third-party testing the soils have been moved to a designated fill area within the works site.

GroundCoverDBM carefully recorded the transport of plant and personnel, fuel use and outputs as part of BLL’s SMART environmental recording. The figures showed an overall saving of 51.32 tonnes CO2 - a reduction of 75% from the landfill alternative. ‘Your work really assists us in achieving our overall objective as well as reducing nuisance to the local community by removing unnecessary vehicles from the road.’ Senior Sustainability Manager, Bovis LendLease.

Our work also assisted with the Code for Sustainable Homes assessment, forming part of the presentation to the Considerate Constructors Scheme monitoring assessment. The monitor was very impressed with efforts made to reduce emissions and nuisance, such as the Klaro process. ‘Overall we are very pleased with the process and the resulting reduction in cost and environmental damage achieved and would be keen to promote its use on other sites where Japanese Knotweed requires treatment.’
Case Study 7 - East end of London, social housing development
Our client had two brownfield sites that were infested with Japanese Knotweed. Our site study identified 15,000 m³ of material contaminated with the weed. Whilst the least expensive solution would have been an extended programme of herbicide treatment, the construction programme required an immediate solution.
Concerned at the environmental and traffic impact of such a solution the local authority raised objections to the 1500 separate lorry movements to and from the site required to implement such an operation.

GroundCoverDBM were asked to find a solution. We liaised with the Environment Agency and local authority to agree and implement a contract to excavate the affected material, process and destroy the viable Japanese Knotweed within the contaminated material, rendering it inert. The processed material was then utilised as suitable fill within the construction site.

The solution reduced the lorry movements and off-site tipping volumes by 96%. The works were completed in 10 weeks, taking no longer than the dig and dump proposal at less than 20% of the cost.

GroundCoverDBM monitored the site and other sites within the redevelopment programme to confirm the effectiveness of the process.
Case Study 8 - South Wales Supermarket development
GroundCoverDBM tendered for, and was awarded, the contract to excavate and remove soils contaminated with Japanese Knotweed from a brownfield site in Pontypool, South Wales. This operation was essential to facilitate the development of a new supermaket for a national food retailer.
The tender documentation identified that approximately 5000 tonnes of material was contaminated, and in order to meet the contract programme the Client required this material to be excavated and disposed of off-site.

Not only did our unique eradication process provide the most cost effective solution, we were also able to implement the works within the desired time scale and find a positive use for the inert processed material, avoiding the use of scarce landfill capacity.
Case Study 9 - Student accommodation development
GroundCoverDBM were asked to survey the knotweed on a derelict site in Cardiff, destined for development as student accommodation. Many small but established stands of knotweed were found, indicating a total of 5200m³ of infested fill material. Calculations quickly showed that removing this to a licensed landfill would cost over £300,000 (2004 prices) and require 520 lorry loads on a busy route into the city.
Our unique processing method was used to deal effectively with the problem on site, avoiding the cost and disruption of landfilling. The site was handed back at the end of the 8-week contract period, allowing the project to continue on schedule with a saving of over £100,000. By avoiding bulk transport to landfill, we also reduced the project’s carbon footprint by 20t of CO2.
Case Study 10 - Feasibility study on Birmingham brownfield site
GroundCoverDBM were instructed by a major development company to complete a feasibility study on a 12ha brownfield site in Birmingham. Our site survey identified 24 distinct areas on site where Japanese Knotweed was present, covering a combined area of some 2500m².
Having considered the options available within the client’s project programme, we liaised with the Environment Agency to develop a solution whereby the stands of Japanese Knotweed and any soils containing fragments of viable root were excavated and placed in selected areas of the site to allow the building programme to commence. The knotweed was then treated by an economical herbicide regime. Once the Japanese Knotweed was dead we were able to reuse the material as inert fill on site.
Case Study 11 - Cardiff brownfield gets EA agreement
GroundCoverDBM were instructed by a developer to consider a solution for dealing with the Japanese Knotweed present on a brownfield site in Cardiff.
The developer had obtained planning approval for the scheme and fixed the position of the buildings on site. Using this information, GroundCover’s engineers were able to determine the minimum volume of contaminated material that required removal to enable the development to proceed. GroundCoverDBM then installed root control barriers to protect the new development, and implemented a programme of selective cultivation and herbicide applications to eradicate the remaining Japanese Knotweed.

GroundCoverDBM obtained pre-works agreement from the Environment Agency for this solution, and then carried out post-completion monitoring before giving the final project sign-off.
Case Study 12 - Disposal cell opens the door
The developer and designer of a trade sales warehouse in west Wales were looking for an economical solution to deal with the stands of Japanese Knotweed on their site, but did not have time to implement a herbicide treatment programme. GroundCoverDBM prepared a disposal area in which we placed the knotweed-infested material excavated from each stand. The material was compacted to specification, and covered with a root barrier membrane over which the developer constructed a concrete service yard. The project required careful collaboration between the design team and our technical specialists, to ensure that all the design parameters were achieved.
Because GroundCoverDBM offers the full range of knotweed management solutions, we are able to work creatively and flexibly to provide the best possible service on any site.

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