Landfill capping describes the construction of an engineered barrier system placed over a completed waste body. It prevents leachate generation, controls gas migration and enables safe site restoration. Infiltrating rainwater, steep slopes and long-term settlement create significant engineering challenges. Carbofol® geomembranes, Bentofix® geosynthetic clay liners (GCLs) and drainage geocomposites provide a proven, compliant and cost-efficient capping solution.
Naue geosynthetic systems are applied wherever compliant containment, long-term sealing and cost-efficient site closure are required.
Compliant engineered capping with sealing, drainage and gas venting.
Robust barrier against hazardous leachate and contaminant migration
Geosynthetic sealing layer for brownfield and contaminated land closure.
High-performance barrier systems for hazardous and special waste bodies.
Geosynthetic landfill capping systems must comply with national and European regulatory frameworks. Naue engineers provide slope stability analysis, shear box testing and product specifications tailored to your project.
Landfill capping projects present extreme installation conditions: steep slopes, soft or irregular waste surfaces and time-pressured programmes. Carbofol® geomembranes and Bentofix® GCLs are engineered for these conditions. Both products are certified under relevant European and international standards and have been installed on slopes up to 1V:2.5H with full regulatory acceptance.
Practical advantages:
A functioning landfill cap integrates multiple technical layers, each serving a defined purpose. Selecting the correct combination depends on the waste type, slope, regulatory requirements and site conditions.
Key principle: The sealing layer prevents leachate formation and groundwater contamination. The drainage layer removes surface water before it loads the barrier. Gas venting protects structural integrity. All three functions must be addressed in the cap design.
Technical benefit: GM + GCL combination reduces permeation to 2.59 x 10⁻¹³ m³/s/hole compared with 4.57 x 10⁻⁶ m³/s/hole for a geomembrane alone.
The choice of the correct product or combination depends on waste class, regulatory requirements, site geometry and long-term performance targets. Use the decision table below as an engineering guide.
| Criterion | Site condition | Carbofol® only | Bentofix® only | Combined system |
|---|---|---|---|---|
| Waste class | Non-hazardous MSW | Yes | Yes | Preferred |
| Waste class | Hazardous / industrial waste | Possible | Not sufficient alone | Required |
| Slope gradient | < 1V:3H (gentle) | Yes | Yes | Yes |
| Slope gradient | 1V:3H to 1V:2.5H (steep) | Yes - use textured/MegaFriction | Yes - needle-punched | Yes |
| Drainage required | Drainage layer needed above cap | Add Secudrain® | Add Secudrain® | Add Secudrain® |
| Regulatory class | German Landfill Class I/II (LAGA) | BAM-approved | LAGA-certified | Full compliance |
| Installation | Where no on-site welding is preferred | Requires qualified welding | No welding required | Combination of GCL and welded GM |
Regulatory compliance without compromise
Carbofol® and Bentofix® products meet European and international standards, including Eurocode 7, EN 13257 (geotextiles for solid waste), EN 13493:2005+A1:2016 (geomembranes for solid waste), GRI GM-13 and German BAM/LAGA (DepV) requirements. Full slope stability analysis and shear box testing are available. This ensures permit-ready designs from the outset.
Lower whole-life cost for the landfill operator
Geosynthetic capping systems avoid the cost of importing large volumes of compacted clay. They shorten the construction programme. Material savings of up to 40% compared with conventional clay capping are achievable on suitable sites.
Faster and simpler installation for the site team
Carbofol® rolls are supplied in widths of up to 7.5 m for rapid deployment. Bentofix® GCL panels require no specialist welding equipment. Secudrain® geocomposites are thermally bonded and ready to install.
Single-source supply with engineering backup
Naue provides design support, product supply and installation guidance from a single source. This reduces interfaces between suppliers and simplifies project management.
A landfill capping system is an engineered barrier placed over a completed waste body. It prevents rainwater infiltration, limits leachate generation and controls gas migration. Geosynthetic capping systems use Carbofol® geomembranes, Bentofix® GCLs and Secudrain® geocomposites to deliver compliant, long-term containment. The capped surface can be restored to grassland or another end use once works are complete.
The choice depends on waste class, slope angle and regulatory requirements. For non-hazardous municipal solid waste sites, either product may be used as the primary barrier. For hazardous or industrial waste, a combined Carbofol® geomembrane and Bentofix® GCL system is required to achieve the necessary containment performance. Naue engineers can advise on the optimum specification for your project.
Landfill capping design in Europe is governed by the Landfill Directive (EU 1999/31/EC), Eurocode 7 for geotechnical design, EN 13361 (geomembranes in landfill) and EN 13257 (geotextiles in solid waste). In Germany, BAM certification and LAGA requirements apply. In the UK, Environment Agency guidelines are applicable. Naue products are tested and approved under these frameworks.
Geosynthetic capping systems avoid the cost of sourcing, transporting and compacting large volumes of clay. Shorter installation time further reduces site operating costs and accelerates permit closure milestones.
Bentofix® GCLs require no on-site welding and can be installed by site teams using standard equipment. Carbofol® HDPE geomembranes require hot-wedge or extrusion welding by qualified lining installers. Secudrain® geocomposites are factory-bonded and ready to deploy. Naue provides installation guidelines and technical support throughout the project programme.
Yes. Carbofol® geomembranes are BAM-approved for landfill use. Bentofix® GCLs hold LAGA certification for German Landfill Classes I and II. Products conform to European standards, including EN 13361 and EN 13257. Project-specific approvals and test certificates are available upon request from Naue.
Both Carbofol® geomembranes and Bentofix® GCLs accommodate differential settlement better than rigid clay layers. The flexible nature of HDPE and the sodium bentonite in GCLs allow minor movement without loss of barrier integrity. Secudrain® geocomposites maintain drainage function even under compressive loads from the cover soil. Naue design engineers verify settlement compatibility during the design phase.
Yes. A gas drainage or venting layer can be incorporated below the sealing element using e.g. geocomposite products. This layer collects landfill gas and directs it to gas extraction points, preventing pressure build-up beneath the sealing layer, which could compromise cap integrity. Naue engineers design gas management layers as part of the complete capping system specification. Contact Naue for project-specific gas control design.
Interface friction between Carbofol® geomembrane and Bentofix® GCL is verified by site-specific shear box testing in accordance with Eurocode 7 and GRI GM-13 parameters. Carbofol® MF (MegaFriction) geomembrane, with 31,500 friction anchors per m² at a height of 900 microns, significantly increases interface friction compared with smooth geomembrane variants. Naue engineers provide slope stability calculations and shear box test data for project-specific cap designs on slopes up to 1V:2.5H.
Naue Carbofol® is a HDPE liner for landfill sealing, mining containment, and groundwater protection.
Naue Bentofix® is a geosynthetic clay liner (GCL) for waterproofing in landfill engineering, groundwater protection and hydraulic applications.
Naue Bentofix® X geosynthetic clay liner is a multicomponent PE-coated GCL for landfill, waterproofing and slope sealing.
Naue Secudrain® is a geosynthetic drainage geocomposite for landfill, groundwater protection and building structures.
Naue Secutex® is a mechanically bonded nonwoven geotextile for separation, filtration and protection in roads, railways and hydraulic engineering projects.
