
Naue’s Bentofix® X2 NSP 4900 GCL was used to remediate a former industrial site in Sighthill, north of Glasgow. The site is being redeveloped into a major urban area with around 800 homes, infrastructure, green spaces, retail and community facilities.

Naue’s Bentofix® X2 NSP 4900 Geosynthetic Clay Liner (GCL) played a key role in the remediation of a former industrial site in Sighthill, north of Glasgow. The site is being redeveloped for a major urban project including around 800 new homes, infrastructure, green space, retail and community facilities.

The site was home to St. Rollox Chemical Works for 167 years, once Europe’s largest chemical works. When it closed in 1964, the land was heavily contaminated, especially with galligu – a waste product from the Leblanc process used to manufacture soda ash. For every 8 tonnes of product, 7 tonnes of calcium sulphide waste were produced and left in heaps, emitting toxic hydrogen sulphide gas.
Around 700,000 m³ of galligu and hydrocarbon waste needed to be safely contained and capped across the 50-hectare site.
The remediation design required a low-permeability capping barrier meeting several criteria:
Based on site-specific chemical analysis, Naue confirmed the long-term compatibility for Bentofix® X2 NSP 4900. Naue also recommended using Naue Secutex® R 501 as a protective and filtering layer above the GCL.
Naue Bentofix® X2 is a needle-punched composite with a uniform core of natural sodium bentonite between a woven and a nonwoven geotextile. A 0.2 mm polyethylene coating is extruded onto the woven side during manufacturing, providing for immediate gas impermeability and additional protection of the bentonite.
The product provides a reliable moisture and gas barrier, resists delamination and delivers hydraulic performance equal to or better than compacted clay. Edge impregnation with bentonite and printed alignment marks ensures watertight overlaps.
To protect the GCL during cover soil installation and to ensure filtration and separation, Naue’s nonwoven needle-punched Secutex® R 501 was installed above the Bentofix® layer.
In total, 140,000 m² of Bentofix® X2 NSP 4900 and Secutex® R 501 were installed. The system provided a safe, cost-effective and high-performance solution for this challenging brownfield remediation – supporting the regeneration of Sighthill into a modern, future-ready neighbourhood.
The PE-coated GCL offered chemical resistance, watertight overlaps and reliable hydraulic performance.
The thin geosynthetic capping system delivered high sealing performance with less material and simpler installation.
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