Published: 2026-07-14

Project completed – E02 Centralen, West Link project

The time has come to decommission the last water treatment facility serving E02 Centralen, part of the West Link project in Gothenburg, Sweden. For us at Swedish Hydro Solutions, this marks a special milestone. Since 2018, we have been providing water treatment services within this section of the project. As one of our first major infrastructure projects, E02 Centralen has been an important part of our company’s journey and of our development into the established company we are today. At the same time, the project contributed to the development of guidelines and discharge requirements for water treatment in Swedish construction and infrastructure projects.

The West Link is one of Sweden’s largest infrastructure projects, connecting Gothenburg’s rail network through a new commuter rail tunnel and three new underground stations. The extensive excavation and construction work involved in the project came with a significant responsibility to protect the surrounding environment. As a result, water management was always a key priority.

Whenever soil and rock are excavated or blasted, large volumes of contaminated water are generated and must be managed properly. Without effective treatment measures, water containing heavy metals, sediment, and other pollutants could have entered nearby waterways and negatively impacted surrounding ecosystems.

Stringent requirements

Developing a framework of guidelines and discharge limits for a project of the West Link’s scale was no simple task. The Swedish Transport Administration worked with a total of 33 permit conditions and three separate monitoring programs covering dewatering and surface water, noise, air quality and vibration, and groundwater management.

Condition 18, which regulated surplus water discharged to receiving waters during construction, established clear requirements for how process water from tunneling, concrete works, and infiltrating groundwater and surface water was to be treated and sampled. In addition to suspended solids, parameters such as chromium concentrations and pH levels were regulated.

Condition 19, which regulated surplus water discharged to the municipal wastewater system, included strict limits for oil content, suspended solids, dissolved contaminants such as heavy metals, and many other parameters. Sampling results had to comply with the specified limits on an instantaneous, monthly, and annual basis. Nothing was left to chance.

New technology reaches a broader stage

In 2017, Swedish Hydro Solutions carried out the Planskildhet Olskroken feasibility study together with Peab. As a newly established company, the project gave us the opportunity to demonstrate that our patented and environmentally friendly technology could deliver strong treatment performance while remaining efficient, scalable, and easy to operate in the field.

The technology addressed many of the challenges identified ahead of the West Link project, including:

  • Clay excavations becoming waterlogged
  • Dramatic increases in stormwater volumes during heavy rainfall
  • Bottlenecks or operational interruptions with significant production impacts
  • The need to remove contaminants such as arsenic, lead, mercury, and pollutants from former industrial activities
  • The need to control elevated pH levels

The feasibility study allowed us to demonstrate our technology on a larger scale, generating considerable interest among project stakeholders. Among others, NCC visited the site to evaluate whether the solution could be used in its upcoming work at Gothenburg Central Station.

A unique environment with unique challenges

E02 Centralen was a massive project and, at the time, NCC’s largest contract. The project area stretched more than two kilometers through central Gothenburg, crossed major roads, was surrounded by urban development, and was located directly adjacent to the river.

The ground conditions were not only dominated by clay but were also affected by more than a century of industrial activity. Historical contamination included oil spills, multiple layers of treated railway ties, and fill materials containing heavy metals and tar-related compounds. All work had to be carried out without lowering groundwater levels or causing settlement in surrounding buildings.

Throughout the project, Swedish Hydro Solutions operated several water treatment facilities within the section. In recent years alone, four facilities were deployed and relocated repeatedly to adapt to changing work areas and project phases. At its peak, we had a total of 23 water treatment facilities operating across the West Link project.

Large volumes of water

Over the years, we have treated significant volumes of water. In just one of our facilities, we treated 130 million liters of water between March 2021 and February 2023.

Week after week, year after year, the facilities kept operating. In clay, in rock, in rain-filled excavations, and in tunnels where there was little room for error.

A lasting legacy

The final chapter has now been written for E02 Centralen. Yet the significance of the project extends far beyond Gothenburg. The discharge limits and guidelines developed within the West Link project continue to be referenced today—for better and for worse—as new infrastructure projects are planned across Sweden.

We are proud to have contributed tangible environmental benefits throughout the construction phase. For us, E02 Centralen has also been an important part of our company’s development and of the journey that helped make Swedish Hydro Solutions the established company we are today.

A sincere thank you to NCC for their trust and excellent cooperation throughout the project.

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