Landfill cell trial assesses new geocomposite material

UK geosynthetic manufacturer GEOfabrics has combined with consulting engineer Wardell Armstrong and waste management operator Viridor Waste Management to undertake a large scale trial of an innovative geocomposite material in the construction of a landfill cell at Viridor's landfill site at Pilsworth, Bury. Detailed design and analysis, supported by laboratory testing and field trials, has been undertaken by Wardell Armstrong and GEOfabrics over the last 12 months in support of the proposal.

The geocomposite material consists of an extruded high density polyethylene, three layer geonet core with a flat tape woven filter geotextile bonded on both sides and a needle punched, staple fibre, non-woven protector geotextile on the underside. The four individual layers are heat bonded together to form the geocomposite. The geocomposite operates with the protector geotextile as the geomembrane protection layer and the geonet drainage core forming part of the leachate drainage layer (together with overlying stone drainage and piped drains). The filter geotextile acts to prevent clogging of the geonet drainage layer.

The geocomposite is installed directly on top of the geomembrane liner and replaces the usual geomembrane protector geotextile. It is then overlain by a stone leachate drainage blanket that, due to the hydraulic properties of the geocomposite, can be reduced in thickness from the 500mm required by the Landfill Directive to 150mm. The geocomposite is produced in rolls 5m wide and up to 50m in length. It is deployed in the same way as a traditional geotextile material using a hydraulic backacter fitted with a spreader bar.

An extensive programme of in service performance monitoring will be undertaken by Wardell Armstrong and GEOfabrics in order to verify the design assumptions and material properties. Regular reports will be submitted to the Environment Agency for review and discussion.

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