Project Overview
CuTex is a permeable copper geocomposite root barrier manufactured by GEOfabrics. This product has been used to line burial cells for the safe containment of Japanese knotweed on a large brownfield residential development. The process avoided the offsite transportation to landfill.
The remediation of brownfield sites is critical in the drive to provide more housing in the UK. Often located on the edge of, or within, existing urban areas, these sites are well placed for access to local amenities and work places.
Previously home to industrial activity from the 1880’s, the land has laid dormant for decades before plans were revealed to bring the site back to life as a residential development. Prior to the land being suitable for construction the widespread presence of invasive plants had to be remediated.
Commencing in 2017, Japanese Knotweed Eradication administered herbicide treatment to clear the area for access purposes. The following year, surveys were carried out to define and demarcate the areas. From these drawings the developer could consider costs for alternative remediation strategies.
A cost estimate of £2.5m was established for the excavation of the contaminated soils, transportation offsite and disposal at a registered landfill site.
This cost was inflated by the content of Japanese Knotweed and heavy metals within the soil. Whilst soil with Japanese Knotweed Rhyzomes may cost £600 - £700/ load the same loads with heavy metals would cost around £1,300.
By burying the waste onsite safely within a cell the costs were reduced by approximately 50%. Four cells were excavated in areas that would later become public open space. The cells were lined with CuTex a copper geocomposite, safely encapsulating the contaminated excavated material. Preventing the spread of this environmental hazard was critical to establishing an attractive and safe residential site.
There was a deficit of fill material to achieve the desired levels. If more earth had been taken off site an estimated 28,000m3 of additional earth/fill would need to have been imported, requiring more than 2,000 truck loads.
Additional vehicle movements on this scale clearly would not only have generated additional expense, but also drastically increases the risk of potential cross site contamination. Keeping material onsite mitigates this expense and risk, and also reduces the environmental impacts of transport and associated earthworks.
Early planning was required in order for the burial cells to be feasible. The cells couldn’t be loaded by residential property, and therefore followed the footprint of a green
corridor. An area that would contribute to increased biodiversity of the project whilst providing valuable green space for the residents of all ages to enjoy.
Whilst some traditional burial cells are created using impermeable liners, here CuTex was used allowing two way water movement whilst separating the contents from surrounding soils by presenting a physical and chemical barrier. This permeability is key to delivering free draining greenspace above, that is not affected by waterlogging and ponding.
Moisture and oxygen in contact with copper release copper ions which act to form a localized warning layer we term the ‘zone of inhibition’. The zone does not extend far from the barrier’s surface and therefore allows the barrier to be used in areas where nearby plants and vegetation may continue to thrive unimpacted.
Several research projects have been undertaken by the Plant Science Department at the University of Leeds. The findings provide independent, academic evidence on the
effectiveness of the copper geocomposite as a barrier to invasive species such as Field Horsetail, Japanese Knotweed and Bamboo. Each project has been documented with findings published in the public domain. Copies of the reports can be down loaded from the Geofabrics website www.geofabrics.com/product/
geocomposites/cutex/
CuTex has been installed in a wide range of applications around the world to control the harmful impact of root damage. Applications include remedial subsidence work,
pavement protection, fibre optic and power cable protection, pipework protection, the management of boundaries, the capping of land affected by invasive plants along with burial cells covered by this case study.
Summary of benefits:
CuTex is Safe – independently tested by University of Leeds Plant Science Department
CuTex is Permeable – maintaining natural hydrology and not hindering movement of waterborne nutrients
CuTex Inhibits Root Growth – CuTex acts as both a physical and a chemical barrier to assist with the control of tree and plant roots
CuTex is Proven – supplied globally into applications within rail, residential, brownfield remediation and amenity sectors.
CuTex is Tested – PD CEN/TS 14416:2014 Resistance to roots with Lupin & Japanese Knotweed
