Closure of Grønmo landfill site

In the period from 1969 to 2007, some 5 million tonnes of waste were dumped at Grønmo landfill site, over an area of 600 hectares. This is an area 1.5 times the size of the whole of Frognerparken in Oslo. The site was shut down in 2007. Now the area is earmarked for outdoor areas, planting, sporting activities and recreation.

COWI has conducted a pre-project and detailed project planning of measures to close Grønmo landfill site. The work included project planning surface water systems, establishing new drainage ditches and dams to give the area a ‘blue and green’ structure.

Key actions included reducing the amount of polluted water and upgrading the extraction of landfill gas to reduce greenhouse gas emissions from the site. The areas have also been covered with soil and vegetation, with landscape design and planting to ensure that surface water runs off, reduce infiltration of water down into the waste and enable alternative uses of the area. All polluted water is collected and treated in a local plant before being released into the municipal system.