Landfill capping (surface sealing) systems close completed waste cells and must do two things at once: shed precipitation so that no hydraulic head builds up on the sealing element, and stay stable on the increasingly steep slopes used to minimise the closure footprint. Naue delivers the functional layers of the capping system - Secudrain® drainage geocomposites, Secutex® protection and filter geotextiles, Carbofol® HDPE geomembranes, GCLs and geogrids - for long-term drainage, barrier protection and slope stability, approved under German, European and international standards.
Geosynthetic capping systems are specified wherever a completed landfill or contaminated site must be closed, drained and kept stable for the long term.
Full geosynthetic capping systems - drainage, protection and sealing element - for the permanent closure of completed waste cells.
Textured Carbofol® and Secugrid® geogrids provide interface friction and reinforcement for stable, space-saving steep caps.
Capping and encapsulation of contaminated ground with drainage and barrier geosynthetics to protect soil and groundwater.
Temporary intermediate sealing of active cells to control infiltration and gas during phased landfill operation.
A capping system must shed precipitation directly so that no hydraulic head builds up on the sealing element - a drainage layer is required for all major landfill classes (I, II and III). The drainage layer must be permanently protected against clogging by particles from the cover soil. Secudrain drainage geocomposites combine a three-dimensional polymeric drainage core with filter geotextile layers to control seepage and prevent clogging, and are robust enough to withstand the stresses of cover-soil installation - so the long-term drainage function is assured.
Landfill cap dimensioning - drainage capacity, protection requirements and slope stability - is carried out in accordance with applicable national and international standards. Naue engineers provide design support, drainage sizing, slope stability analyses and interface shear box testing to ensure the selected capping system satisfies all regulatory requirements for the specific site and landfill class.
Closure caps for tailings storage facilities and heaps, with long-term drainage and slope stability.
Practical advantages:
The sealing element of a cap must be protected from mechanical damage during cover-soil placement and throughout its service life, while the interfaces between layers control the movement of water and soil particles. Secutex® nonwoven geotextiles provide protection, filtration and separation in one proven product family.
Key principle: In Germany the minimum mass per unit area is 800 g/m² for a protection geotextile and 300 g/m² for a separation or filtration geotextile. A needle-punched nonwoven above the geomembrane can replace the otherwise necessary sand protection layer.
Core benefit: the barrier is protected without an extra sand layer.
Core benefit: durable seepage control and clean layer separation.
The right capping configuration depends on the slope steepness, the landfill class and the required drainage, protection and reinforcement functions. Use the selection matrix below to identify the appropriate system. It maps Naue capping configurations to slope steepness and the required drainage, barrier, protection and reinforcement functions - structured guidance for specifying a stable, compliant cap.
| Criterion | Standard cap (gentle slope) | Steep closure slope | Reinforced steep slope |
|---|---|---|---|
| Slope angle | up to approx. 1 in 3 | approx. 1 in 3 to 1 in 2.5 | steeper than 1 in 2.5 |
| Drainage | Secudrain® drainage geocomposite | Secudrain® with slope anchorage | Secudrain® with slope anchorage |
| Interface / barrier | Smooth Carbofol® or Bentofix® GCL | Textured Carbofol® F/F for friction | Textured Carbofol® F/F for friction |
| Reinforcement required? | No | Consider Secugrid® geogrid | Yes - Secugrid® to redistribute loads and enable the slope |
| Protection geotextile | Secutex® ≥ 800 g/m² | Secutex® ≥ 800 g/m² | Secutex® ≥ 800 g/m² |
| Design support (Naue EDD) | Standard detailing | Interface shear box testing | Interface shear testing plus slope stability analysis |
The sealing element protected without a sand layer
A needle-punched Secutex® nonwoven replaces the otherwise necessary sand protection layer above the geomembrane, cutting earthworks and haulage.
Permanent drainage function - no hydraulic head on the cap
Secudrain® geocomposites shed precipitation and resist clogging and installation damage, maintaining flow capacity for the cap's full service life.
Stable, space-saving steep slopes
Textured Carbofol® and Secugrid® geogrids provide interface friction and reinforcement, enabling steeper closure slopes and a smaller footprint.
Procurement and regulatory compliance as standard
Naue provides system design, geotechnical stability assessment, product supply and installation - a single point of accountability. Components are approved under EU Directive 1999/31/EC, German DepV and BAM; documentation is traceable and certified for regulators and owners.
A landfill capping (surface sealing) system is the multi-layer geosynthetic and mineral cover placed over a completed waste cell to control infiltration, manage landfill gas and accommodate settlement while protecting the environment. It is required for the closure of regulated landfills under EU Council Directive 1999/31/EC and national regulations such as the German DepV, with the configuration depending on the landfill class.
Precipitation that infiltrates the cap must be shed so that no hydraulic head builds up on the sealing element, which would threaten stability and barrier integrity. A drainage layer is required for all major landfill classes (I, II and III). Secudrain® drainage geocomposites provide this function and are protected against clogging by an integral filter geotextile.
Yes. Secudrain® drainage geocomposites with a three-dimensional core and filter geotextiles replace thick granular drainage layers, reducing earthworks, haulage and installation time while delivering a defined, verifiable flow capacity. Installed on the geomembrane, the geotextile side also acts as a protection layer.
In Germany the Deponieverordnung (DepV) governs capping; geomembranes require BAM approval and Secudrain® is BAM-approved for Landfill Directive-guided systems. Bentofix® GCLs fulfil LAGA suitability requirements. Across Europe, EN 13493 (geomembranes), EN 13257 (geotextiles) and EN 13252 (drainage) apply, alongside EU Directive 1999/31/EC.
In Germany the minimum mass per unit area is 800 g/m² for a protection geotextile and 300 g/m² for a separation or filtration geotextile. Secutex® needle-punched nonwovens are available across this range; a nonwoven above the geomembrane can replace the otherwise necessary sand protection layer.
Steeper slopes minimise the closure footprint but stress the interfaces of the multi-layer cap. Textured Carbofol® F/F geomembranes provide enhanced interface friction, and Secugrid® geogrids redistribute loads and enable cost-effective, safe engineering of steeper slopes. Naue conducts interface shear box testing and slope stability analysis.
The waste body continues to settle after closure. Secugrid® geogrids minimise or eliminate the effects of differential settlement and redistribute loads, protecting the drainage and barrier layers, while the flexible geosynthetic system tolerates deformation without loss of function.
Yes. Carbofol®, Bentofix®, Secudrain®, Secutex® and Secugrid® have been used in landfill closure and capping projects worldwide over decades. Case studies are available on this page.
Naue's Engineering and Design Department (EDD) provides drainage design, interface shear box testing to Eurocode 7, EN ISO 12957-1 and ASTM D6243, slope stability analysis and full specification support to ensure the cap satisfies the regulatory requirements for the site and landfill class.
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 Secugrid® geogrid stabilises and reinforces roads, embankments, working platforms, slopes and walls.
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.
