Protecting groundwater at E4 highway expansion with geomembranes

Overview

The E4 highway between Helsingborg and Stockholm is one of Sweden’s most critical traffic and transport routes. It carries heavy volumes of vehicles daily and is central to the country’s economic and logistical infrastructure. A 30 km stretch of this highway at Ljungby required major upgrades by Trafikverket, the Swedish Transportation Administration. The expansion project included widening the roadway, adding new bridges and intersections, and strengthening protective measures for nearby natural resources.

This section of the E4 passes through a designated protected area that serves as the groundwater source for the drinking water supply of 70,000 residents in the Växjö and Alvesta municipalities. The proximity of the highway to this aquifer presented a clear risk: runoff from the road could contaminate the groundwater and jeopardize public health. Protecting this water source became a primary priority of the highway upgrade.

Challenge

In groundwater areas, measures are usually needed at roadsides to reduce the harmful effects of road salting and to prevent the spread of hazardous substances that may enter the soil in the event of an accident.

In Ljungby, uncontrolled infiltration of such runoff could directly threaten the groundwater feeding the drinking water supply. The expansion of the E4 through this sensitive area required a robust barrier system to intercept and contain runoff before it reached the aquifer.

The challenge was twofold. First, the scale of the project was significant, with 30 km of roadway expansion passing directly over the protected zone. Second, the barrier system needed to be engineered for long-term durability under constant hydraulic load from runoff and potential mechanical stresses from construction activities. Trafikverket required a solution that would provide long-term groundwater protection without compromising the efficiency of the road expansion.

Solution

To safeguard the groundwater, Solmax geomembranes were selected and installed by Svenska Geotech AB, the project partner. A ditch was formed alongside the E4 prior to road expansion, and this ditch was lined with geomembrane to create a continuous containment system for runoff water.

Solmax’s manufacturing plant in Rechlin, Germany, supplied 185,000 m² of smooth, 1.5 mm GSE^® HD geomembrane over a two-year period. This material was chosen for its impermeability, chemical resistance, and proven performance in water protection applications. By lining the ditch, the geomembrane ensured that runoff could not infiltrate into the soil and reach the groundwater. Instead, runoff was securely contained and directed for controlled management.

To enhance the performance and durability of the barrier, the geomembrane was integrated into a multi-layer geosynthetic system. A protective geotextile was placed both under and over the GSE^® HD geomembrane to prevent puncturing during installation and throughout the operational life of the system. On top of the geomembrane assembly, a protective sand layer was placed, followed by a drainage layer of aggregate. These layers further shielded the geomembrane while providing efficient drainage of collected runoff.

The combined system provided multiple functions: containment, protection, and drainage. By intercepting and securely channeling roadway runoff, the system eliminated the risk of contaminants entering the groundwater. At the same time, the protective geotextile and sand layers extended the service life of the geomembrane by preventing mechanical damage and distributing loads evenly.

The installation demonstrated the capacity of engineered geosynthetic systems to address complex infrastructure challenges in environmentally sensitive areas. Solmax’s geomembrane solution integrated seamlessly into the highway expansion works, providing reliable groundwater protection while enabling Trafikverket to complete the required upgrades.

The Ljungby project highlights how geosynthetic barrier systems can be applied at scale to protect critical natural resources. By delivering 185,000 m² of GSE HD geomembrane, Solmax helped secure the drinking water supply of 70,000 residents, meeting strict regulatory requirements and ensuring sustainable development of one of Sweden’s most important transportation corridors.