A self-sealing, high-strength geotextile sandwich has provided capping for Wapsey's Wood Landfill in Buckinghamshire.
Naue Geosynthetics' Bentofix Geosynthetic Clay Liner NSP 4300-1 is a composite of two geotextiles sandwiching a layer of sodium bentonite clay.
The upper geotextile is non-woven and the lower a woven polypropylene. Needle punching pushes fibres from the non-woven geotextile through the clay and into the geotextile. This gives the liner high strength, preventing it from bursting when the sodium bentonite swells during hydration - which expands the original 6mm thick membrane by between 4mm and 5mm.
The process also seals the longitudinal overlap joints, speeding up installation. At Wapsey's Wood, 10,000m 2of Bentofix was laid each week during a 12-week contract by a single excavator. Hydration sealed the joints, creating a single 120,000m 2capping layer.