GEOTEXTILE MANUFACTURER Geofabrics supplied 228,000m2 of a recently developed geotextile as part of a landfill capping system at the new Bran Sands waste treatment plant on Teesside.
Northumbrian Water's facility for treating sewage sludge and wastewater on the south bank of the Tees estuary near Middlesbrough is due to be fully operational by next year.
It is being built on a landfill previously used by chemical manufacturer ICI for chemical waste. The old landfill had to be capped before construction could start, but there was a possibility that methane gas would be trapped by a conventional capping material.
Another solution came in the form of a new product from Geofabrics, GPT1, which was developed with GSE Lining Installers and main contractor for the treatment plant Harbour and General.
GPT1 is made from two layers of non-woven geotextile, sandwiching strip drains running the length of the roll. The strip drains consist of an extruded core material wrapped in a light heat-bonded non-woven fabric.
Under the supervision of consultant Entec, the 21ha site was first covered with a layer of Terram 1300 geotextile and a granular drainage blanket.
This was covered with GPT1, which intercepts any gas and allows it to be drawn off. It also protects the GSE ultraflex gas membrane above.
A Pozidrain drainage geocomposite was then laid to allow water flowing down through the fill to flow to an outfall. This was protected by a layer of Geofabrics HP5 geotextile. The whole arrangement was then covered by another layer of crushed slag and vent stacks built to allow controlled release of residual methane.
As site buildings extend below the level of the membrane, both the GPT1 and the HP5 were jointed into the foundations of the gas drainage systems.
Geofabrics says that fast installation of GPT1 is possible because it is supplied in rolls of up to 75m by 6m, which also keeps overlaps to a minimum. GSE was able to lay up to 13,000m2 a day on the Bran Sands site.