The Midgard Snake in Oslo

Stikkord: Klimatilpasning, Oslo, nedbør, flom

According to Norse mythology the Midgard Snake lies on the bottom of the sea. It has eaten so much, and grown so long, that it surrounds every country in the world. The Midgard Snake of Oslo Water and Wastewater Department will swallow water to protect the public in Oslo against the consequences of increased precipitation.

According to Norse mythology the Midgard Snake lies on the bottom of the sea. It has eaten so much, and grown so long, that it surrounds every country in the world. The Midgard Snake of Oslo Water and Wastewater Department will swallow water to protect the public in Oslo against the consequences of increased precipitation.

The Water and Wastewater Department’s project «The Midgard Snake» covers the area from the Kuba Park in Grünerløkka, down the Aker River to Grønland, through Gamlebyen, and ends in Bekkelaget Purifying Plant. «The Midgard Snake» will function as an interruptive drainage system, preventing polluted water to reach the Oslo Fjord.

Improved Water Quality

By preventing wastewater getting into The Aker River and Bjørvika, the water quality in the inner parts of the Oslo Fjord will improve. This is the project’s intention. The project will also be an important adaptation to climate change and increased precipitation. Today, a lot of surface water exceeds the capacity of the drainage systems.

City Surface Water

Today’s cities have big challenges when it comes to surface water. When it rains on covered surfaces, like concrete and tarmac, the water will flow off the premises instead of down into the ground. This way the water reaches the streams and drains more easily.

With increased development and covering roads in tarmac, more surface water is created. There will also be an increase in episodes with heavy rain in future years. Increased development, together with the increasing precipitation, will lead to more pressure on the water mains and will increase chances of flooding and water damage.

The Snake that Swallows Everything

The bottom part of the Aker River has a shared drainage system made in the 1890’s. This drainage system is not designed to manage vast amounts of water. In these cases, the water is led into a spillway leading wastewater and sewage and polluted surface water into the Oslo Fjord.

«The Midgard Snake» will function as an interruptive drainage system, preventing polluted water from reaching the Oslo Fjord. A part of this snake includes a two kilometre long tunnel from Gamlebyen to Bekkelaget Sewage Plant.

This tunnel will have a capacity of 50 000 cubic metres that will function as both a transport route and a retention reservoir, where the water can be stored if the Purifying Plant lacks capacity. This project will improve the water quality in the Fjord and address consequences of climate change.

This system will also reduce energy consumption, because the water is not being transported as far as before (VEAS in Asker). The project, estimated at one billion NOK, will be finished in 2013–2014.