Case

New main water supply to connect cities in Norway

Ringsaker municipality has approximately 33,500 inhabitants and covers an area of 1.281,1 km2. The municipality is growing and thus the need for water is growing. To meet the demands, a water main running from the city of moelv to the city of rudshøgda is renewed with manholes and service points. The long-term goal is to connect the entire municipality from moelv to the city of brumunddal with public water.

The reason for Ringsaker municipalicity’s upgrade of the water supply is among other things the increase of industrial companies in Rudshøgda, and growth along the lake Mjøsa also adds to the increasing demand for water. In addition to the need for potable water and water for industrial use, high demands are also placed on the waterline’s capacity in connection with irrigation and fire protection.

DN400/500 connection

“We renew pipelines and basins based on points of distribution. To begin with, this will increase the capacity up to Rudshøgda.

The connection towards Brumunddal is also of societal significance in the long term which is why we use dimensions that, if necessary, can supply the entire region from one of the water works. This holds both safety and practical advantages,” explains Fahle Karlsen, Project Manager in Ringsaker municipality.

The existing pipeline is from the 1970s. Now the connections will be 400/500 mm throughout the entire distance, and all minor pipelines will be connected to eight new manholes with new fittings.

Two stages

The work is divided into two stages and also includes renewal of main pipelines for wastewater and rainwater. New pipes will be installed from the pumping station for wastewater to the wastewater treatment plant in Moelv, and new connection pipes are installed for rainwater, which is separated and sent to trenches and further out in the terrain.

The work takes place in a junction where roughly 10,000 cars pass every day, which put great demands on the contractor, Maskinanlegg AS in Brumunddal.

“To work in high-density housing areas pose challenges. We have to adapt to traffic and the existing infrastructure. Among other things, we have to drill our way under the main road to make room for a wastewater pipeline. It was also our intention to install water pipelines below Moelva. We tried with 120 meters controlled drilling mainly due to environmental considerations. Now we will have to dig,” says Jon Ola Eid from Maskinanlegg AS, Brumunddal. 

Eight manholes

Eight manholes with valves are installed as part of the overall renovation of the water pipeline in order to ensure smooth operations and provide access to minor branches of the pipeline. A flexible AVK combi cross DN400 is installed in each of the manholes in a distance of approximately 160 meter from each other. The manholes are connecting the existing water distribution with the new water pipeline.

“This combi cross is an advanced and user-friendly fitting. An example is the full bore centre part and a centre cap with standard flanges for DN100 fire hydrants, which can easily be connected with optional valves in sizes 150, 200, 250, 300 or 400 mm,” says Martin Rud, Market Manager at AVK Norge AS.

The advantage of this solution is that it is possible to mount a blind cover on one or more of the outlets. It has a threadless connection output which can be used for different purposes. The cover can be rotated so the location of this output can be either on the top or bottom of the line, or in any other position that the client may want depending on the application.

Also for fire protection

The assembly between the centre part and the valves is based on a thoroughly tested system which is also used within fire protection.

“This is tested according to the EN 1074-2 requirements, both for strength and tightness testing of pipes with operating pressure up to PN16,” says Martin Rud. The centre cap can be removed for easy access to pigging or for inspection and maintenance of pipelines.

“This is the only combi cross on the market that has a DN400 centre part and DN400 valves. Just like the AVK combi cross in DN100-300, the anchoring points are placed on the centre part independent from the valves or flanges. The anchor is therefore 100% intact even if a coupling or valve is demounted on one or more outlets,” says Martin Rud. All the valves have a full bore corresponding with the flange size.

“Whether you choose a DN150 or DN400 valve, they have the same overall face-to-face length and a common centre line throughout the installation,” explains Martin Rud. The valves are moulded with a lifting eye ensuring that the valve is automatically centered when mounted in connection with renovation or expansion. 

Service and three-way 

Service connection valves are mounted vertically behind the flange on all the valves. Passage through the ductile valve bodies is smooth and without internal thread, with an epoxy coating according to GSK.

“The combi cross comes with AVK’s three-way ball valve that ensures water circulation in the ball when it is in closed position. This is particularly advantageous when service valves can be exposed to frost,” explains Martin Rud.

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