Where soil or building materials containing environmentally relevant substances are reused during earthworks, a sealing layer is applied over them to protect the groundwater from leaching. In Germany, the FGSV guideline M TS E “Merkblatt über Bauweisen für Technische Sicherungsmaßnahmen beim Einsatz von Böden und Baustoffen mit umweltrelevanten Inhaltsstoffen im Erdbau” requires the material to be sealed and defines three construction methods (A, B and C). Naue supplies the sealing element and the associated layers: Bentofix® and Bentofix® X geosynthetic clay liners (GCLs), Carbofol® HDPE geomembranes, Secudrain® drainage mats and Secugrid® geogrids. Outside Germany, equivalent national regulations apply so that the same engineering principle and products are used internationally.
These sealing systems are used wherever soils or construction materials with environmentally relevant substances are reused in earthworks and groundwater must be protected.
Sealing reused materials in transport earthworks
Sealed fills built from secondary/recycled materials
Reprofiling and greening with environmentally relevant materials
Barriers beneath reused industrial by-products or soils
M TS E requires the reused material to be sealed and defines three construction methods. The sealing element can be a mineral seal or a geosynthetic clay liner (GCL); for the weather-insensitive method, a geomembrane. Naue supplies the sealing element and the associated drainage, protection and stabilisation layers. As an alternative to the usual compacted 0.5 m clay seal, the approx. 10 mm fully needle-punched Bentofix® GCL with highly swellable sodium bentonite is used; its robust cover and carrier geotextiles are dimensioned to resist installation damage.
The weather-sensitive sealing layer is covered with initially 1.5 m of embankment fill (product-specifically reducible to ≥ 1 m for bentonite mats) plus a topsoil layer. The cover fill must be at least 1,000 times more permeable than the sealing element (k ≤ 5 × 10⁻¹⁰ m/s). The sealing component is either a 0.5 m mineral seal with k ≤ 5 × 10⁻¹⁰ m/s or a bentonite mat (GCL) such as Bentofix®. Because of the tightness requirement, Naue recommends the Bentofix® X type (with PE coating): its uniformly and firmly extruded polyethylene coating ensures protection against drying out and root penetration. Adequate frost protection is provided, depending on the frost zone, by a soil cover of ≥ 1 m.
A drainage/seepage layer (e.g. Secudrain®) is placed above the sealing layer. Because of this drainage layer, the requirements are lower than for Method A: the sealing layer and the drainage mat are covered with 1.5 m of embankment fill (reducible to ≥ 1 m for bentonite mats) plus topsoil, and the 0.5 m mineral seal needs a permeability of only k ≤ 5 × 10⁻⁹ m/s or a bentonite mat (GCL) such as Bentofix®. This allows a Bentofix® GCL to be used as the sole sealing element, with a Secudrain® drainage mat arranged above it.
The sealing component is weather-insensitive, and the cover thickness is set project-specifically according to the planned planting or greening. The primary sealing element is a 2.5 mm structured HDPE geomembrane such as Carbofol® (≥ 2.5 mm). Alternatively, a coated bentonite mat as in Method A (e.g. Bentofix® X) can be used; a soil cover of at least 1 m is recommended over the bentonite mat.
Selection depends on whether the seal is weather-sensitive, whether a drainage layer is present, and on slope and site conditions.
| Method | Sealing element & requirements |
|---|---|
| Method A (no drainage) | Bentofix® X (PE-coated) or a 0.5 m mineral seal with k ≤ 5 × 10⁻¹⁰ m/s; cover 1.5 m fill (≥ 1 m for GCL) + topsoil; frost cover ≥ 1 m. |
| Method B (with drainage) | Bentofix® GCL as the sole sealing element with a Secudrain® drainage mat above; mineral-seal option k ≤ 5 × 10⁻⁹ m/s; cover 1.5 m fill (≥ 1 m for GCL) + topsoil. |
| Method C (weather-insensitive) | Carbofol® structured HDPE ≥ 2.5 mm, or Bentofix® X; cover set project-specifically (≥ 1 m soil cover over a bentonite mat). |
| Steep slopes/poor ground | Add a Secugrid® geogrid for slope stability (slopes steeper than 1:2.5). |
Practical benefits:
Compliant sealing element
Bentofix®/Bentofix® X and Carbofol® provide the sealing element for M TS E construction methods A, B and C.
Thin, fast barrier
An approx. 10 mm GCL replaces a 0.5 m compacted clay seal, reducing material and installation effort.
Built-in protection
Bentofix® X PE coating protects against drying out and root penetration; robust geotextiles resist installation damage.
Slope capability
Suits slopes steeper than 1:2.5; a Secugrid® geogrid adds stability where needed.
Single source
Bentofix®, Carbofol®, Secudrain®, Secugrid® and Secutex® from one supplier, specified together.
M TS E is a German FGSV guideline “Merkblatt über Bauweisen für Technische Sicherungsmaßnahmen beim Einsatz von Böden und Baustoffen mit umweltrelevanten Inhaltsstoffen im Erdbau”. When soils or construction materials with environmentally relevant substances are reused in earthworks, it requires the material to be sealed and defines three construction methods (A, B and C) to protect groundwater. Outside Germany, equivalent national regulations apply.
Bentofix® and Bentofix® X geosynthetic clay liners as the sealing element, Carbofol® HDPE geomembrane (≥ 2.5 mm, Method C), Secudrain® drainage mats (Method B), Secugrid® geogrids for slope stability, and Secutex® protective nonwovens.
Yes. M TS E names bentonite mats (GCLs) alongside the mineral seal. The approx. 10 mm Bentofix® GCL replaces the conventional 0.5 m compacted clay seal.
Its uniformly and firmly extruded PE coating provides the required tightness and protects against drying out and root penetration. It is recommended for Method A and as an alternative in Method C.
Typically 1.5 m of embankment fill plus a topsoil layer over the sealing layer, product-specifically reducible to ≥ 1 m for bentonite mats. Frost protection depends on the frost zone (≥ 1 m soil cover). For Method C, the cover is set project-specifically.
Yes. Bentofix® suits slope inclinations steeper than 1:2.5 depending on soil conditions and slope length; a Secugrid® geogrid can ensure stability on steeper slopes or poor ground.
M TS E is a German framework, but the engineering principle of sealing reused materials with environmentally relevant substances to protect groundwater, applies internationally. Naue aligns designs with the applicable national regulations and supplies the appropriate barrier products.
For a mineral seal: k ≤ 5 × 10⁻¹⁰ m/s (Method A) or k ≤ 5 × 10⁻⁹ m/s (Method B). A Bentofix® GCL is accepted as an equivalent sealing element.
Yes. Naue provides engineering support, product selection for Methods A, B and C. A related digital selection guide and calculation tools are available in the Naue Portal. In Germany, Naue is a certified WHG specialist installation company.
The M TS E construction methods define the sealing requirement; Naue supplies the sealing element and associated layers. Outside Germany, equivalent national regulations for reusing materials with environmentally relevant substances apply.
Frameworks:
Products:
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 Carbofol® is a HDPE liner for landfill sealing, mining containment, and groundwater protection.
Naue Secudrain® is a geosynthetic drainage geocomposite for landfill, groundwater protection and building structures.
Naue Secugrid® geogrid stabilises and reinforces roads, embankments, working platforms, slopes and walls.
Naue Secutex® is a mechanically bonded nonwoven geotextile for separation, filtration and protection in roads, railways and hydraulic engineering projects.
