Pumps seal the cracks in the norwegian granite

2018/07/12

Norway

In one of Norway’s biggest ever tunnel construction projects, the Follo Line, a risk of gas leaks is threatening workers as they cut their way into the raw mountainsides. SCALA2 pumps have been brought in to take care of this problem.

Deep in the Norwegian bedrock by the harbour in Oslo, ten SCALA2 pumps have been put to work. They maintain a constant pressure of 3 bars. Water is pumped into the bedrock, so gas won’t leak. In here, the air is filled with humidity and dust but the scent is clean thanks to the pumps.

Condotte construction company is overseeing construction of the Follo Line – the longest railway tunnel in the Nordic countries. In 2016 they discovered a potential danger. Old storage fuel tanks for ships were leaking gas, which could seep into the tunnel through cracks in the bedrock. Condotte therefore asked Elmodan, the supplier of construction equipment, to find a solution to the problem.

The solution was ten SCALA2 pumps connected to 1,500 litre water tanks. The cracks are covered and the constant water pressure keeps the gas away.

“We have several years of experience from an earlier partnership with Grundfos, who are always ready to come up with custom-made solutions. To make this system work, we needed a constant pressure of 3 bars. The unique electronics of the pumps made it possible to sustain the necessary pressure,” says CEO of Elmodan, Lars Ingemann.

Resists tough environment
Exploding, digging, drilling and blasting are necessary to get through the solid granite. Since Spring 2017 the pumps have withstood the tough environment – and they continue to do so.

”We are working with giant machines, and in a difficult and sometimes dangerous environment, especially when considering stationary equipment which is exposed to continuous dust and humidity. Therefore, it is an absolute necessity that we have a system, which is stable, and which does not fail under the circumstances we experience in the tunnel,” says André Pas, Project Manager for Condotte.

The SCALA2 pumps will be used until the drilling of the tunnel has been completed. Then the sides of the tunnel will be covered with concrete so the gas has no way of getting in. Originally, the pumps were designed for providing perfect water pressure in residential buildings.

“When Elmodan called we were just about to send SCALA2 on the market. Even though the pumps were made for households we saw an opportunity to use their intelligent control because it is very reliable and stable – exactly what Elmodan requested,” says Lars Würtz Jensen, Sales Technician for Grundfos.

The trains are expected to be running on the tracks by the end of 2018. Then it will be possible to use the 20-kilometre Follo Line from Oslo to Ski. The tunnel is designed for trains to travel at up to 250 km/h.