Flood Defence Mjondalen Breeam Good

Flood defence work in Norway gets BREEAM Infrastructure rating of Good

Designed to reduce the flood risk in Mjøndalen, Norway, this work was recognised for its sustainable practices with a BREEAM Infrastructure rating of Good.


Flomsikring Mjøndalen – Vassenga is part of the flood defence project in Mjøndalen, aiming to reduce the flood risk in the city. The project consisted of the expansion of an existing creek, Mjøndalsbekken and some green field works in the adjacent areas. The work undertaken earned a BREEAM Infrastructure (formerly CEEQUAL) rating of Good.


The Norwegian Energy Regulatory Authority is the national regulatory authority for the electricity and natural gas markets in Norway.


From the design phase, the project had an extensive focus on reducing carbon emissions and increasing the resilience in the area. After the contractor was chosen by the client, the project parties together had a look at how to promote the environmental and social aspects of the project.

The client and contractor had no previous experience with a BREEAM Infrastructure assessment. Determined to make a success of it, the parties saw this as a suitable project to promote sustainability.


The project team put forward an extensive plan and targets to promote sustainability for the project. To implement, monitor and document the conduction of the plan, the plan was reviewed regularly as a follow-up for the weekly environmental site inspections, making sure corrective actions were done when needed.

The project consisted of an increase in the steam width and depth of the steam Mjøndalsbekken. This increase did reduce the flood risk of the city of Mjøndalen. At two places the steam crosses a road and the team had to construct crossings are made of pipes. To reduce the risk of these pipes overflowing, the size was increased and a waterway for overrunning water in case of flooding was established.

The relationship with neighbours was important for both the client and the contractor. Hence, the project had a person working with the relation with neighbours. This person regularly walked from door to door to inform and consult with the neighbours regarding the construction works and how they would be affected. The input from the consultation resulted in several successful actions such as the retention of rhubarb plants, the retention of hedges and the management of road and parking areas to avoid reduced access during construction. Responses from neighbours at the end of construction showed that neighbours were satisfied with the feedback from the project.

The topsoil in the area consisted of contaminated soil infected by invasive species. The client evaluated reuse of this material was not appropriate. Hence, the soil was removed and replaced by new soil before a grass mixture was seeded.

At end of construction, the project used deconstructed formwork and surplus wood to make bird boxes. Children from a local kindergarten were invited to decorate the boxes before they were installed in the area.

The gravel in the area mostly consisted of clay, making vibration damage to adjacent structures a significant risk. The excavation works and movement of construction machines were planned and conducted to reduce vibrations. The project succeeded to carry out the project without causing any damage to adjacent structures.

Monitoring results of dust emission and water quality showed no unacceptable or permanent adverse effects caused by the construction works.

The project was carried out without the use of fossil energy or fuel, reducing the carbon emissions from construction machinery by 95%. To reduce energy consumption locally sourced materials were prioritised, e.g. the size of stones used for the complementary works in the steam was changed to facilitate for the use of locally sourced stones.


The assessment forced the project to implement a comprehensive system to take care of environmental and social aspects. An extensive plan including risk assessments was put forward and reviewed on a regular basis. This resulted in a more systematic and quality-focused follow-up of the sustainability aspects.

Traditionally, the scope of the project would not require an environmental adviser to work on the project daily. Due to the requirements of the BREEAM Infrastructure assessment, an environmental adviser was assigned to work on the project. This resulted in lowering the risk of causing any adverse effects on the surroundings. Additionally, the adviser did extensive work in staff training that will be beneficial for future projects.

Commenting on the overall success of the project and working with BREEAM, Tore Leirvik, project manager, shared “This was our first project to complete a BREEAM Infrastructure assessment. The assessment did put forward several new questions and challenges, which we had to take action to handle. The BREEAM Infrastructure certificate confirms that we have succeeded to carry out the project in a way that did not cause unacceptable adverse effects on the environment or the surroundings. We will use the experiences from the project to facilitate even more sustainable projects in the future”

By using BREEAM Infrastructure in this project, I learned more about implementing environmental issues into project management including both the physical works as well as economics. Our lessons will strengthen us as an organisation for future projects.
– Tommy Skoglund, Project manager, Marthinsen og Duvholt AS

Summary for Case Studies


Norges Vassdrags- og energi direktorat
Marthinsen & Duvholt AS
Anders Gorrissen, Marthinsen & Duvholt ASElise Roalkvam/Simen Kjollmoen, Skanska Norge AS
Catherine Taggart, Aecom Ltd
6, 2023 | Norway
BREEAM Infrastructure rating:

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