Sweden's new environment law is one of the most stringent in the world and over the course of the next year, the Environmental Court in Växjö will address an exhaustive environmental impact assessment during and after the implementation of the construction of the Malmø City tunnel. COWI and SWECO are working together in a joint venture as consultants on the entire tunnel project and are responsible for part of the environmental study that will ensure there is no environmental disaster and contribute to public acceptance of the project. The application makes an attempt to predict every kind of environmental consequence of the tunnel and railway line through the densely populated centre of Malmø.

"The owners of the City tunnel have elected to place great demands on themselves and have applied for environmental approval as a polluting company, which was not at all necessary," explains COWI Head of Department Torsten Mølgaard. As a result, the City tunnel project will be subject to a more exhaustive environmental assessment than the law prescribes.

Prior to the application to the Environmental Court there are two years of analysis of the environmental consequences during and after construction of the tunnel and proposals to reduce them. The material consists of some 30 technical reports on noise, settlements, vibrations, groundwater and tunnelling techniques.

Experience from the Copenhagen Metro

The City tunnel project has many things in common with the Copenhagen Metro project. Both involve construction work under large cities, with the requirement for as little noise and vibration as possible. And both have similar underground conditions. COWI has therefore been able to make use of its experience from the Copenhagen Metro, where one of the demands was for the groundwater table not to be lowered. This is a problem that has occupied the Swedes greatly since the disaster with the tunnel at Hallandsåsen, where the discharged water was heavily polluted with a chemical grout and the groundwater table lowered by 50 metres.

"There are methods today of avoiding groundwater pollution," says Torsten Mølgaard. "In Malmø, we have proposed the introduction of a series of routines where chemicals are thoroughly evaluated before they are taken into use. A scenario for the groundwater to be lowered during the construction period is also prepared, especially at stations; where at least 80 per cent of the groundwater will be pumped back again. It is also possible to use techniques that minimise noise and vibration and thereby cause less disturbance to the people of Malmø during the five years of construction work."

Environmental management throughout the project As consultants for the entire project, COWI and SWECO have not only assisted with the environment application but also implemented environmental management during the design stages, from the first line on the drawing board more than two years ago, to the tendering of the tunnel that will take place this year. That process also includes the assurance of a healthy working environment during the construction phase.

"We have set up two multi-disciplinary project teams where engineers, who understand the constructional aspects, and environmentalists, who can evaluate their acceptable impact, work closely together. We are collaborating with our Swedish colleagues in the same way we did during the building of the link across the Sound, but this time with Swedish legislation as our reference point. In environmental terms, this is something of a pioneering venture that could pave the way for similar projects in Europe, where increasing demands for environmental correctness are being made. In Holland, for example, we are assisting with the planning of a tunnel on the high-speed railway line between Amsterdam and Brussels, and in Ireland we are consultants on an immersed tunnel under a river estuary. The project in Ireland began with an environmental constraints study that showed what consequences were acceptable."

Public acceptance is crucial

Torsten Mølgaard emphasises that public acceptance of a project is becoming increasingly crucial to its success. With this in mind, the owners of Malmø City tunnel have decided to spend two years on an environmental analysis that goes far beyond legal requirements.

The work with the tender documents is now ongoing, and the compliance with the application will be ensured during the process. Documentation will be delivered to the contractors in the autumn for their pricing. Actual construction will begin in late 2003.

The tunnel

The City tunnel will be a 17-km rail link between Malmø Central Station, the Sound Link and the southerly part of the Swedish district of Skåne. One third of this will run through a bored tunnel and two underground stations are constructed. Two 7.9 metre tunnel tubes will be built, cross-linked with 13 smaller tunnels for technical installations. The cross-passages will also function as escape routes and provide access for emergency situations. The tunnels will have a capacity of 450 trains per day.

Published 03.04.2002