Supervision of the refurbishment of the worlds’ longest rock tunnel that carries water to the capital of Finland
Finland’s Päijänne Water Tunnel (constructed in 1972) is the world’s longest continuous rock tunnel and provides Helsinki and surrounding cities with pure water from Lake Päijänne in central Finland.
Ramboll has been involved in several maintenance projects on the 120 kilometre long tunnel where an amazing amount of water (3m3/sec) flows by gravity to over a million consumers in the big cities.
Reinforced with shotcrete
In 2009, we completed the supervision of an extensive renovation project of the southern part of the tunnel. This section has been reinforced with 215,000m2 of shotcrete and 7,000 new rock bolts to prevent cave-ins and secure future operational reliability.
Païjänne water’s high degree of purity means that only a simple process of purification is needed, whereas waste water, in comparison, requires complex and costly purification processes. As the water flows by natural gravity, energy to ensure flow is not necessary.
Value added for the customer
The water tunnel ensures clean drinking water without extensive purification systems and pumping. Many households receive their water supply from this tunnel.