Groundwater protection for roads describes the engineering practice of sealing road structures - including embankments, cut slopes and drainage zones - to prevent road runoff, fuel spills and de-icing salts from contaminating subsoil and groundwater. Roads generate pollutants such as hydrocarbons, heavy metals and chlorides that can penetrate unprotected ground. Carbofol® geomembranes and Bentofix® geosynthetic clay liners (GCLs) create a compliant, durable barrier system that contains these pollutants and protects water resources.
Naue geosynthetic sealing systems are used wherever road infrastructure must comply with groundwater protection regulations and resist long-term chemical exposure.
Sealing embankments and cut slopes on high-traffic roads to meet WHG and RiStWaS requirements.
Lining roadside drainage ditches and infiltration basins to contain polluted road runoff.
Waterproofing drainage structures at tunnel portals and cut-and-cover sections in sensitive zones.
Sealing forecourts and containment basins at motorway service areas to prevent the infiltration of fuel spills.
Protecting shallow aquifers beneath urban dual carriageways and arterial routes from saline runoff.
Road embankment sealing operates in demanding conditions: steep slopes, heavy compaction equipment and aggressive road runoff. Carbofol® geomembranes and Bentofix® GCLs are engineered to withstand these installation loads and provide long-term chemical resistance.
Practical advantages:
Note: For water protection zones (WHZ I–II), a composite system is required: Bentofix® GCL as the primary barrier plus Carbofol® geomembrane as the secondary barrier, with a leak detection layer between them.
Effective road groundwater protection requires both the containment of pollutants and the controlled removal of road runoff. Understanding which function dominates in each part of the road structure determines the correct product specification.
Sealing contains pollutants - drainage removes them safely. Both functions are required in compliant road sections.
Technical benefit: single layer, rapid installation, proven chemical resistance.
Technical benefit: A self-healing GCL plus a chemical-resistant geomembrane provide maximum protection.
The choice of sealing product depends on the regulatory zone, slope geometry, pollutant type and long-term maintenance requirements. Use the table below to identify the right system for your project.
| Criterion | WHZ III / Standard road | WHZ I–II / High-risk zone | Karst / Permeable subsoil | Steep slope (> 1:3) | Chemical resistance required |
|---|---|---|---|---|---|
| Recommended product | Carbofol® HDPE + Secutex® | Bentofix® GCL + Carbofol® (composite) | Composite system + LAGA-verified GCL | Carbofol® textured (friction-verified to EN ISO 12957) | Carbofol® HDPE (hydrocarbon, salt, metal resistant) |
| Permeability class | GBR-P per EN 13361 | GBR-C + GBR-P composite | GBR-C + GBR-P, LAGA verified | GBR-P, friction angle verified | GBR-P, HDPE 406/612 types |
Regulatory compliance without compromise
Carbofol® and Bentofix® meet the requirements of RiStWaG, WHG, LAGA and international standards. Naue provides full documentation for regulatory submissions, including CE marking, BAM approvals and country-specific certifications.
Lower whole-life cost compared with clay liners
Geosynthetic sealing layers are thinner, lighter and faster to install than compacted clay liners. Reduced earthworks volume and shorter installation time lower total project cost. Service life exceeding 100 years minimise maintenance expenditure.
Fast and safe installation
Bentofix® GCL rolls are installed using light equipment with self-sealing overlaps - no specialist welding at every joint. Carbofol® geomembranes are welded by certified operators using extrusion or hot-wedge welding. Installation progress is faster than with clay liner placement.
Road groundwater protection describes the sealing of road structures - embankments, drainage zones and service areas - to prevent pollutants from reaching groundwater. It is required in Water Protection Zones (WHZ I–III) and wherever roads cross karst terrain or highly permeable ground. In Germany, the legal basis is the Wasserhaushaltsgesetz (WHG) and the technical standard RiStWaG. UK requirements are set out by EA Pollution Prevention Guideline PPG3.
Naue offers two primary product families: Carbofol® HDPE geomembranes and Bentofix® geosynthetic clay liners (GCLs). For standard WHZ III roads, a single Carbofol® geomembrane with Secutex® protection geotextile is sufficient. For WHZ I–II or karst terrain, a composite system is required: Bentofix® GCL as the primary barrier combined with Carbofol® as the secondary barrier.
Key standards include RiStWaG (Germany), WHG Section 62 (Germany), EA PPG3 (UK), EPA SWPPP regulations (US), and LAGA verification for substitute construction materials (Mantelverordnung, Germany, has been in force since August 2023). Geomembranes must comply with EN 13361 (GBR-P class) and geosynthetic clay liners with EN 13362 (GBR-C class). Friction performance on slopes is verified to EN ISO 12957.
Geosynthetic sealing systems are typically more cost-effective than compacted clay liners. Clay liners require 300–500 mm of carefully graded and compacted material, significant earthworks and extensive quality control. Carbofol® or Bentofix® systems are installed in layers as thin as 5–10 mm, substantially reducing excavation and transport costs. Service lives exceeding 100 years reduce whole-life costs further.
Carbofol® geomembranes are welded on site by certified operators using extrusion or hot-wedge welding equipment. Seam integrity is tested using vacuum box or air pressure testing. Bentofix® GCLs are unrolled and overlapped; bentonite swells upon hydration to seal the overlaps without additional welding. Secutex® protection layers are placed above and below the sealing element before earthfill placement.
Yes. Carbofol® geomembranes hold CE marking under EN 13361 and general type approvals (Allgemeine bauaufsichtliche Zulassung) from the German Institute for Building Technology (DIBt). Bentofix® GCLs are LAGA-verified for use under the German Mantelverordnung. BAM approval documents are available for specific product types. Naue can provide full product documentation for inclusion in contract specifications and regulatory submissions.
A geosynthetic clay liner (GCL) is a manufactured product consisting of a layer of sodium bentonite encapsulated between two geotextile layers. When the bentonite comes into contact with water, it swells and creates a low-permeability barrier with a hydraulic conductivity below 5 x 10-11 m/s. Bentofix® GCLs are classified as GBR-C (clay barriers) under EN 13362 and self-seal at overlaps, eliminating the need for welded joints between rolls.
Yes. Carbofol® geomembrane seams welded by hot-wedge or extrusion welding are tested using vacuum box testing, air-pressure channel testing or electrical spark testing. Seam strength is confirmed by peel and shear tests in accordance with EN ISO 13426-2. Bentofix® GCL overlaps are verified visually for minimum lap width and bentonite coverage. Naue provides quality assurance documentation and on-site support for all seam verification procedures.
Sealing systems for road groundwater protection are designed in accordance with national and international standards. Key input parameters include the water protection zone classification, slope geometry, pollutant type and anticipated service life.
The following system benefits come directly from how the Naue products work within the layer structure:
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 Secutex® is a mechanically bonded nonwoven geotextile for separation, filtration and protection in roads, railways and hydraulic engineering projects.
