“Hallandsåstunnelns sydportal vid Förslöv” 2006-07-08 – CC BY-SA 3.0

The development of water treatment in construction and civil engineering

Twenty years ago, water management on construction sites was limited to diverting oil and sludge using simpler oil and sludge separators. Environmental requirements were low, and the technology was basic. Today, the situation is completely different. Stricter legislation and extensive emission regulations, such as the City of Gothenburg’s guidelines from 2008, have changed the playing field. Construction projects must manage a wider range of pollutants while environmental requirements specify which technical solutions should be used to achieve the goals.

This development has been driven by technological advancements and lessons learned from previous environmental incidents, resulting in today’s water treatment equipment being significantly more advanced. Modern technology enables efficient water purification and real-time monitoring of the process, ensuring that the industry can meet the increased environmental requirements in a sustainable and responsible way.

Key wake-up calls that drove the change – some examples

Environmental scandal at Hallandsåsen, 1997

One of the most notable incidents was the environmental scandal at Hallandsåsen in 1997. Water leakage during the tunnel construction turned out to be greater than anticipated, and cement injection was insufficient to seal the cracks. Instead, a sealant called Rhoca-Gil, containing acrylamide and methacrylamide—substances that are both toxic and carcinogenic—was used. Despite the manufacturer downplaying the risks, the sealant spread into the groundwater, causing sick cattle and fish deaths in Vadbäcken.

The scandal delayed the project by 18 years and served as a wake-up call for the importance of managing water quality in infrastructure projects. It led to increased focus on environmental and workplace safety issues and stricter water treatment requirements.

Botniabanan, 2004

During the construction of the Botniabanan in 2004, extensive turbidity was caused in rivers and lakes, especially in ‘Skrikesjön’, where a railway embankment was being built. Despite safety measures such as dams, contaminated water leaked out, damaging the bottom organisms of the lakes. The turbidity was long-lasting and demonstrated how sensitive ecosystems are to the impact of construction projects.

The incident became a lesson that prompted stronger actions against turbidity in water during similar projects and tightened requirements for protective measures.

Remediation of contaminated areas

Since the 1990s, a large number of contaminated areas in Sweden have been remediated, including industrial areas, mines, gas stations, and ports. Of the identified sites, 1,200 were considered so heavily contaminated that they posed a direct risk to both human health and the environment.

These remediation projects placed higher demands on water treatment technology than what was available at the time and became a driving force for the development of more advanced solutions.

The northern portal of the Hallandsås Tunnel near Båstad in Sweden.
Photo: Karrok, License :CC BY-SA 3.0

Countries that were ahead of Sweden

The USA, particularly the state of Washington, and the UK have long been ahead of Sweden when it comes to the development of mobile water treatment in the construction industry. In the USA, extensive requirements for construction projects were introduced early, primarily through the Clean Water Act in the 1970s. This federal law, one of the most influential environmental laws in the USA, regulates water pollution and aims to restore and preserve the chemical, physical, and biological integrity of the country’s waters. The Clean Water Act can be compared to the EU’s Water Framework Directive, which came into force almost 30 years later, in the 2000s.

The law paved the way for high standards in the construction and civil engineering sector, where certified treatment facilities and trained personnel are essential to ensure that water treatment maintains high quality and meets environmental requirements. This type of certification requirement is still lacking in Sweden, where water treatment in construction projects is often managed without clear guidelines for competence and equipment.

One of the most groundbreaking innovations in mobile water treatment in the USA was the development of chitosan, an effective flocculation technique that enables particle separation without the need for harmful chemicals. This is a technology that we at Swedish Hydro Solutions brought to Sweden, further developed, and refined to make it even more effective and sustainable.

The UK, on the other hand, was quick to introduce strict fine models for violations of limit values, which has contributed to driving the development of advanced treatment technology in the construction and civil engineering sector. The country has long had a high technical level in its treatment equipment, creating the conditions for more efficient and sustainable solutions.

Kitosan - ett mycket effektivt ofarligt flockningsmedel

Chitosan – a highly effective, environmentally friendly flocculant.

How is the situation today?

Today’s water treatment in the construction industry is far more advanced than it was 20 years ago, thanks to technological advancements and lessons learned from previous environmental issues. A clear example is the ‘Västlänken’ project, where modern requirements have set a new standard for water treatment that is often replicated in other projects. Västlänken is one of Sweden’s most extensive infrastructure projects, where Gothenburg’s railway network is connected through a new commuter train tunnel and three new stations under the city. When Västlänken is completed, around 100,000 residents and 130,000 workers will have walking and cycling distance to a commuter train station in central Gothenburg.

Swedish Hydro Solutions’ water treatment technology has been the most widely used in the Västlänken project, with up to 23 separate treatment facilities operating simultaneously across the project’s various phases. The project uses advanced water treatment facilities, all equipped with technologies for:

Common water treatment equipment

Pre-sedimentation, pH lowering with CO₂
Addition of precipitation and flocculation chemicals
Lamella clarifiers or sedimentation tanks
Filter

Online Monitoring

Flow
Turbidity
pH

Sampling

Usually flow-proportional

This combination of technology and careful monitoring ensures that water treatment meets today’s strict discharge requirements and minimizes environmental impact.

The future – a forecast

Increased focus on the status of the recipient

The Water Framework Directive has already had, and will continue to have, a significant impact on how we view the status of the recipient. Regulations play a crucial role, both in terms of requirements for contracts and the demands placed on technology and its development.

Better written tenders

Even today, tenders are written where only a sedimentation container is requested – an important part of the treatment process, but often insufficient to handle all types of contaminants or to meet the strict threshold values that may apply. We therefore see a need for increased knowledge about water management and water treatment, both within municipalities, county administrative boards, and contractors.

As part of our work to strengthen this knowledge, we have launched the industry event SweWater Summit in Sweden. Here, we gather the entire industry – municipalities, county administrative boards, contractors, and consultants – to discuss challenges, exchange knowledge, and gain new insights on how we can work together for better water management.

Development of monitoring and safety

The ability to monitor water treatment facilities exists today, but the systems need to be continuously developed and improved to ensure safe and effective treatment processes.

Increased requirements for environmentally friendly chemicals

We see a clear trend toward stricter requirements for more environmentally friendly water treatment chemicals. We believe that similar regulations will be introduced in the future.

Focus on technology and competence

Water treatment facilities need to continue developing with technology tailored to specific needs. We also see an increased emphasis on the competence of staff for the operation of these facilities, where knowledge and training are becoming increasingly important.

The article was published on: 2025-02-19

Mobile water treatment

Stricter discharge limits and larger projects have made mobile water treatment essential — and a key factor in avoiding costly delays on construction sites.

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