The installation of a 3,4 km DN1000 steel pipe was not straightforward, due to the dimensions of the tunnel. In areas where the pipe changes direction, either vertically or horizontally, the pipe is supported by 11 massive concrete foundations that been casted in place. The narrow profile of the tunnel posed challenges for the team lifting and placing the pipe in the correct position, but the careful and thorough execution of the works was successful.

Not one but two thorough inspections of the pipes was carried out by Marti and the client, to ensure the correct quality. After inspection, connection to the water distribution network was executed within only a 10 day period, minimizing any disturbances to the water supply of Oslo.

Another challenging milestone was the installation of the vertical 18,9m long flanged DN1000 stainless steel pipe in a narrow shaft close to the Skullerud water treatment plant, shortly after the shaft was blasted by Marti.

Meanwhile, careful filling of 15.000m3 rock masses for the road level in the tunnel and filling around the pipe was executed.

Thanks to good collaboration and coordination between Marti Tunnel, our subcontractors Marthinsen & Duvholt and Augestad Maskin,  the works have been executed in time and with highest quality and the satisfaction of our client Oslo Kommune (VAV).