The reservoir is actually a tunnel measuring 3.4 kilometres and 3 diameters. It is located below Vigerslev Park in Valby, a district of Copenhagen. It is Denmark’s longest wastewater reservoir to date and it will manage the district’s rain and wastewater

It can contain 29,000 cubic metres of water, which is equivalent to twelve Olympic swimming pools.

It will act as an efficient safeguard against pollution in Damehus Lake, which runs through the middle of Vigerslev Park.

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The purpose of the tunnel is to purify the water at the end of Vigerslev Park and establish a bathing beach. Simultaneously, the tunnel will reduce the risk of flooding when heavy rain or cloudbursts occur in the area

- With the new tunnel, we take a significant step towards cleaner water in the lake. This benefits both residents and guests in the park that may otherwise be bothered by the smell from the many sewer outlets. At the same time, the capacity of the entire sewer system out here is increased which reduces the risk of flooding when cloudbursts occur, says the Managing Director at HOFOR, Lars Therkildsen in a press release.

The layout for the tunnel began back in 2013 and has amounted to a total of half a million DKK – including expenses for a new pumping station.

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Facts about the new tunnel

• Length: 3.4 kilometres
• Diameter: 3 metres
• Layout period: 2013-2017
• Developer: HOFOR
• Consultants: Niras
• Contractor: Aarsleff Pipe Technologies

- Download white paper: Unlocking the Potential of Wastewater