Groundwater Protection

Our Partner


Synergy, along with German partner Naue, offer several premium solutions for groundwater protection.

Single component sealing systems

Single component sealing systems

Single component sealing systems featuring Synergy’s geomembranes are used in industrial facilities for storage, filling, and transferring and for production, treatment, and utilization – where there is a danger of groundwater contamination by hazardous materials.


When used in the construction of collection basins, Carbofol® high-density polyethylene (HDPE) geomembranes effectively protect groundwater and soil resources from pollution by potentially harmful contaminants.

With a minimum thickness of 1.5 mm, Carbofol® HDPE geomembranes fulfil a wide range of chemical resistance as well as physical durability requirements. In addition to their long-term chemical resistance, Carbofol® HDPE geomembranes have long-term UV resistance and are resistant to rodents as well as root growth when manufactured with a minimum thickness of 1.0 mm.

By virtue of Carbofol’s® high flexibility, more complicated connections are feasible without sacrificing quality or performance. Due to their advantageous melt index properties, Carbofol® geomembranes can be welded under a wider range of conditions, producing gas and watertight overlaps.

Quality control tests are conducted continuously on every project in addition to the standard manufacturing quality control practices.


To ensure the performance and quality of a single component sealing system, mechanically bonded Secutex® or Depotex® protection nonwovens should be used above and below the Carbofol® geomembrane, the selection of which should be based upon project specific conditions.

With a low gravel content sandy subsoil (< 30 % gravel portion), a 400 g/m² mechanically bonded polypropylene (PP) Secutex® protection nonwoven is sufficient. However, with coarser grained soils, mechanically bonded Secutex® protection nonwovens with a mass per unit area of up to 1,200 g/m² should be considered. With Secutex® and Depotex® nonwoven geotextiles, the long-term performance and integrity of the Carbofol® sealing element can be preserved both during the installation as well as against subsequent construction loads.

Performance Monitoring

After completion of the single component sealing system, an independent expert must approve the quality of the installation. To enable permanent monitoring and documentation of the sealing system performance, a drain and control tube system or an electro-resistivity leak detection system, may be installed directly below the Carbofol® geomembrane. With a photo-ionization-detector (PID), leakage from the liner can be observed as contamination in the control tube system and measured via special soil air investigations. In principle, it is best if the sealing system performance is measured twice a year during the first two years. In the following years, the frequency of system checks may be reduced to once a year unless the defined performance standards are exceeded.


With a properly specified mechanically bonded polypropylene Secutex® or high-density polyethylene Depotex® geotextile protection system, Carbofol® geomembrane offer high quality long-term single component sealing systems.

In chemical storage depots, petrol stations, collection basins, liquid depots, container areas, chemical plants, scrap yards as well as many other applications where measures for groundwater protection are necessary, Synergy’s high quality, single component geosynthetic sealing systems can be effectively and economically employed.

Double liner sealing systems

Double liner sealing systems

Double liner sealing systems are installed in industrial facilities where liquids are “stored, filled and transferred” or “produced, treated and used” and where aggressive hazardous liquids could lead to a groundwater contamination if released into the environment.

If the requirements of the local water authority are more demanding with respect to the installation quality, monitoring capabilities and overall performance of the single lined system, a double lined sealing system may be used to reduce the risks associated with the containment of large amounts of potentially harmful liquids. In double lined sealing system, a monitoring or control layer is installed between two Carbofol® geomembranes.


Double lined seals are selected where there are the highest safety requirements. A typical double lined sealing system consists of two – 2 mm thick HDPE Carbofol® geomembranes and an HDPE drainage Secudrän® XX geonet lying between the two lining components, to act as the monitoring zone. UV-resistant Carbofol® HDPE geomembranes are an excellent choice to fulfill these stringent requirements and offer the added benefits of being resistant to rodents and roots.

Performance Monitoring

The two-layered sealing system offers the flexibility to be monitored either continuously or periodically.

To enable the location of damage or faults within the liner system, the monitoring zone is typically divided into individual control fields. Each control field has two monitoring modes (one for vacuum checks and a wire for electrical monitoring). The division of the monitoring zones into individual control fields can also help limit the spread of contaminants in the entire monitoring zone by allowing quick and precise damage location.

After completion of the project, the entire monitoring zone is put under a negative pressure of 0.3 to 0.6 bar.
The vacuum pump is located in a measuring cabinet that also contains the leakage indicator. A sudden drop in the negative pressure indicates a faulty control field in the system. Repair measures can then be initiated selectively and quickly.

Another monitoring tool is based on electro-resistivity measuring principles, where a unique conductive geotextile is installed in the monitoring zone between two geomembranes. The geotextile, along with a measuring and evaluating matrix-like structure are connected with the local data unit, which collects the resistance distribution within the special nonwoven geotextile.

If the conductive geotextile becomes hydrated due to damage in the overlying geomembrane, the electrical resistance of the geotextile in this area changes. This change in resistance releases an alarm, so that corrective actions can be performed in the specific area of the damage.


To ensure the long-term quality of the double lined sealing system, mechanically bonded protection nonwovens are recommended above the upper Carbofol® geomembrane. With less than ideal subsoil conditions, it may also be necessary to install a mechanically bonded protection nonwoven beneath the lower Carbofol® geomembrane.

If the cover layer for the double lined sealing system is a sand with gravel (gravel portion

Due to the aggressive nature of the chemicals above the two-layered Carbofol® sealing system, mechanically bonded HDPE Depotex® protection nonwovens are recommended.


In industrial sites, where higher safety and monitoring standards are common, double lined Carbofol® HDPE geomembranes are typically required. The long-term performance and protection of the sealing system is enhanced by using Secutex® (PP) or Depotex® (HDPE) protection nonwovens to prevent mechanical damage during the installation and subsequent operation in the facility. For extremely sensitive environmental protection projects, high quality double lined geosynthetic systems with Secudrän® XX geonets as a monitoring layer from Naue Fasertechnik ensure economical, long term containment.

Groundwater protection in transport infrastructure

Synergy - Groundwater protection in transport infrastructure

Various national guidelines for road construction in environmentally sensitive areas require the subsoil be sealed and effective construction measures be taken to protect the groundwater in transport infastructure near to water catchment areas. In numerous projects, Bentofix® geosynthetic clay liners and Carbofol® geomembranes have proven to be effective, economical sealing systems. They are used under roads, railways and for retention basins.


As an alternative to a 60cm thick compacted cohesive soil, the approximately 10 mm thick Bentofix® geosynthetic clay liner, manufactured with high swelling natural sodium bentonite, is used. The robust cover and carrier geotextiles used in the construction of Bentofix® are designed to withstand rough installation loads. Bentofix® is uniformly manufactured with direction-independent needlepunching (fibre reinforcement) over its entire surface area, with more than 2 million fibres per square metre. Depending on the existing soil conditions and slope lengths, slope inclinations of 2.5h:1v or greater are possible, due to the surface structure of the needlepunched cover and carrier geotextiles and the large internal friction angle. In poor soil conditions or on steeper slopes, Secugrid® geogrid can be used to further ensure slope stability.

Due to their thin profile, Bentofix® geosynthetic clay liners consume less airspace than compacted clay, and can require less soil excavation and removal. The Bentofix® BFG 5000 features a cover geotextile that has been uniformly impregnated with bentonite powder over it entire surface area. This bentonite treatment in the cover geotextile can make the installation more efficient as the field application of bentonite paste to the overlaps is not required.

The Bentofix® encapsulating geotextiles are typically made from polypropylene (PP) resin and therefore sufficiently resistant to a wide range of conventional chemicals, such as diesel fuel, oil and benzene. In cases where aggressive chemicals may be encountered, the Bentofix® geotextiles can be manufactured with high density polyethylene (HDPE). Alternatively, 2.0 mm thick Carbofol® HDPE geomembranes can be installed. Carbofol® HDPE geomembranes are best suited to aggressive conditions due to their wide range of chemical and natural element resistance (e. g. to UV-radiation, rodents, chemicals). Not only is placement easy, it is also easy to weld Carbofol® HDPE geomembranes due to the favorable Melt Flow Index of the base resin.

Structured and Friction Carbofol® geomembranes are available to effectively transfer shear forces on the most challenging slope locations. Regardless, project specific direct shear tests should be performed to verify the required shear strength parameters are being met by the components selected for use.


The encapsulating geotextiles of Bentofix® geosynthetic clay liners protect the bentonite, as well as providing sufficient robustness for on site handling. When high normal installation loads are anticipated, Bentofix® manufactured with nonwoven geotextiles with a minimum mass per unit area of 270 g/m² should be used. Performance of the Carbofol® HDPE geomembrane is assured when the installation is performed by industry experts. Depending on the regulatory requirements as well as site conditions, needlepunched protection nonwoven geotextiles, such as Secutex® (from PP) or Depotex® (from HDPE) may be installed both above and below the Carbofol® geomembrane.

For slightly gravelly sand (gravel portion < 30 %), the Secutex® or Depotex® protection nonwovens with a mass per unit area of 400 g/m² should be used to protect the Carbofol® geomembrane. Coarser grained soils may require heavier styles of Secutex® protection nonwovens, exhibiting a mass per unit area of 1,200 g/m². In cases where high chemical concentrations are expected, Depotex® protection nonwovens are recommended.

Erosion Control

In steep slope areas, heavy rainfall may cause erosion ruts or wash away the young grass seed. Secumat® erosion control mats prevent surface erosion and rutting by retaining the soil and seed in a convoluting threedimensional structure. Secumat® is installed directly on the slope and filled with soil. Roots of the vegetation gradually enclose the convoluting layer of Secumat®, efficiently interlocking it with the surrounding soil.


When constructing roads, railways or retention basins in groundwater protection areas, Bentofix® geosynthetic clay liners and Carbofol® geomembranes can be effectively used. Needlepunched Secutex® protection nonwoven geotextiles ensure a long-term protection of the Carbofol® geomembranes. Secugrid® geogrids can ensure the stability of steep slopes while Secumat® helps to prevent surface erosion. Complete geosynthetic system solutions from Naue are economical as well as ecologically superior alternatives for groundwater protection applications.

Tunnel construction

Tunnel construction

Modern traffic tunnels are increasingly planned for a functional service life of more than 100 years. For this reason they must be protected extensively against the effects of groundwater and water penetrating through rock fissures. The construction and sealing specifications are correspondingly strict, especially with respect to the required service life.

The level of hydrostatic pressure and the agressiveness of the water determine the scope of the protection required for the construction of underground structure measures. Also, for ecological reasons, there is an increasing desire to limit the drainage of mountain water. There are a broad range of opportunities, technical as well as economic, for selecting the most suitable protection system. Each tunnel requires a specific solution; depending on construction details, such as cut and cover construction projects, varying water agressiveness, transition sections of in-situ water under pressure and seepage water.

Sealing does more than just protect important structures against corrosion. The tunnel suitability (e. g. prevention of icing) as well as the stability itself requires a protection against moisture. In comparison to the total costs of constructing a tunnel, the costs of providing a functional waterproofing is minor – but the advantage to be gained is major. Sealing protects and safeguards the structure. It reduces maintenance costs and repairs. Therefore waterproofing is an indispensable part of any tunnel construction.

A long-term, trouble-free tunnel operation with low operating and maintenance costs can be achieved with a professionally installed sealing system. In addition, a tunnel’s sealing system will actively contribute to environmental protection, despite the need for the construction of the tunnel, by avoiding interference with the mountain’s hydrological water balance. The sealing system will also prevent environmental damage from oils or chemicals which may occur due to traffic accidents.

These important requirements are satisfied reliably and economically with the NAUE waterproof sealing system. NAUE offers complete single-source systems for tunnel construction, from manufacturing to installation including full quality assurance.


Synergy worker rolling waterproof lining for groundwater protection

A well cast reinforced concrete element should be able to resist the penetration of water even under high water pressure, protecting its integral steel from corrosion. In reality, it is very difficult (even with most modern production plants) to produce such a perfect reinforced concrete mass, since the smallest inconsistency (such as aggregation of gravel) can cause imperfections in the concrete. Often, the water which penetrates into reinforced concrete is acidic and hence has an aggressive effect on the basic chemical elements of the concrete, as well as the steel reinforcement. This ultimately leads to the decay of the composite element. Small cracks can easily occur in the outer sections of a cast concrete mass during the curing period due to shrinkage. Concrete structures are also susceptible to cracking due to oscillations caused by traffic, as well as settlement of the underlying soil and natural phenomena such as earthquakes. The steel reinforcement, especially on the side adjacent to the outer surface, is particularly at risk from corrosion caused by the ingress of water via these cracks and via micro-cracks by flexure of the element during its service life.

BENTOFIX® BFG 5000 is a concrete sealing system which efficiently protects reinforced concrete structures, preventing the penetration of water and providing protection to the structure from attack by aggressive chemical substances present in the local surrounding soil.