The contract to build the cloudburst tunnels in Valby and Frederiksber has been granted to a consortium of the Danish company MT Højgaard Denmark and the French company Eiffage. Contract amount is DKK 490 million and the length of the tunnel is 2380 meters.

HOFOR A/S which is the one granting the contract is Denmark's largest local supply providing water, heat, city gas, remote cooling and drainage of wastewater for more than 1 million people in the metropolitan area of Copenhagen. Below is a translation of HOFOR A/S' (original in Danish) release.

Tunnel must remove rainwater from streets in Valby and at Frederiksberg

A new cloudburst tunnel will help keep Valby and Frederiksberg West free of floods in the event of a cloudburst and massive rain The tunnel will also significantly reduce sewer overflow to the veal stalls, which is a natural area. HOFOR and Frederiksberg Forsyning have now chosen the partnership MT Højgaard Denmark and Eiffage Infra-Spezialtiefbau as the main contractor on the 2.4 km long Valby cloudburst tunnel.

Valby cloudburst tunnel is becoming an important part of the fight against the rising rainfall that come with climate change. It should run deep down in the lime from F.L. Smidth area in Valby and under Grønttorvet, Valby Sports Park and Valbyparken to the music city in Sydhavnen. Work begins in the summer of 2024, and the tunnel with associated pumping station will be completely finished in 2028.

The tunnel will primarily act as a basin, ie. An underground basin that can store large quantities of overflow water from the sewer system until the water can be pumped to the wastewater treatment plant. In extreme rainfall, the water can also be led directly into the veal stalls via outlet points in the Gåsebækrenden and Enghave Canal. Discharges will only happen very rarely and to prevent the same water from pushing up the streets and creating flooding.

One of the largest cloudburst projects -

A tunnel like the one we are to build here will have a great impact on the city's citizens and users, especially people in Frederiksberg and in Valby. It protects values and creates increased security because it helps to make the areas more robust to cloudbursts and massive rain, says Lone Loklindt, chair of the board of directors of Frederiksberg Forsyning and co -signer on the contract.

The tunnel is among the largest of the hundreds of cloudburst protection projects included in the overall cloudburst plans for Frederiksberg and Copenhagen.

- Each project makes a difference, and no parts can be avoided, but the large main waterways such as Valby cloudburst tunnel is crucial for the rainwater to be quickly led away from the city's surfaces in connection with cloudbursts and massive rain, says Henrik Bay, CEO of Frederiksberg Forsyning.

The experience is in place

Now the utilities have signed with the partnership MT Højgaard Denmark/Eiffage Infra-Spezialtiefbau. The contract is DKK 490 million. The task is to drill the tunnel all the way from Valby to Sydhavnen. The partnership must also make connections to the sewer system in several places and build a pumping station at Enghave Kanal.

- Such a big task places great demands on the contractor, and here MT Højgaard has Denmark together with our partner Eiffage Infra-Spezialtiefbau both the experience and the competencies of similar tasks over time. We are very much looking forward to solving the task, says Carsten Lund, CEO of MT Højgaard Denmark.

Finding space in town for the massive rainfall Although the tunnel can accommodate large amounts of water, much more is needed to prepare the city for the rainfall that the climate of the future brings.

- The finished tunnel will play with the many hundreds of cloudbursting projects that have already been completed or underway at Frederiksberg and in Copenhagen. We need to secure billions for billions in citizens and businesses against the effects of the climate of the future. We can only do this if we can continue to find space in the city for our projects both above and underground, so that we can lead the water to where it does not damage the city, says Henrik Plougmann Olsen, CEO of HOFOR.

Far fewer sewer overflow Valby cloudburst tunnel gets an interior diameter of 3.4 meters and can in itself contain approx. 30,000 cubic meters of water, which is a quantity that is equivalent to filling the 3 km long Valby Langgade with 1 meter of water. The tunnel will reduce the number of sewer overflows to the veal stalls from 4-5 times a year to less than once a year, which is good for water quality and can give several days with green bathing flags at Valbyparkens Strand.

Read more about the tunnel project at: http://HOFOR.DK/VALBYSKYBRAPH OR http://frb-forsyning.dk/valbyskybrudtunnel

Facts

• Valby cloudburst tunnel becomes 2.4 km long and has an inner diameter of 3.4 meters.
• The tunnel is expected to be ready for use in 2028.
• During the construction period, four construction sites are established on the tunnel section for drilling and establishing shafts underground. The shafts are established at:  Ramsingsvej/Høffdingsvej (at F.L. Smidth-Ground) Blushøjvej (by McDonalds) The music city (Sydhavnen) Enghave Canal (Sydhavnen)
• At all four construction sites, the Sekant Piles of Works are drilled down, giving rise to noise
• The tunnel can in itself store approx. 30,000 m3 of water, which is equivalent to filling the 3 km long Valby Langgade with 1 meter of water, which can wait in the tunnel until there is room to pump it for the wastewater treatment plant.
• The tunnel will reduce the number of overflows from the sewer to the calf run by 80 per cent - from 5 times a year to less than once a year. It will prepare the aquatic environment in the veal, and give several days with green bathing flags at the beach in the Valby Park. 

Drawing and information from HOFOR A/S press information.