Jóhann Örn discussed the grouting in rock in the Fljótsdalur powerstation

Jóhann Örn Friðsteinsson, geoengineer at Verkís Transport and Environment Division, delivered the talk PU grouting in cold environment at fully operating Fljótsdalur Powerplant at the Nordic Rock Meeting conference last week. He also wrote a paper on the same topic that was published in the conference journal as well as participated in the organization of the conference.

The conference was held at Grand Hotel Reykjavík on the 24th-26th of last May. Four of Verkís employees attended the conference.

In the paper and the talk, Jóhann Örn discussed a project that Verkís carried out for Landsvirkjun.

The hydroelectric power plant Fljótsdalur Powerstation is Landsvirkjun’s largest power station with an installed capacity of 690 MW, and is able to produce 4,800 GWh of electricity annually. The water flows through a 40 km headrace tunnel from Hálslón reservoir to the power station, leading to a max gross head of 600 m.

Verkís investigated leakage in rock in the valve chamber of Fljótsdalur Powerstation, where water leaks into the chamber from the headrace tunnel from Hálslón reservoir. Two-thirds of the water drop height is in the 400 meter high and almost vertical pressure shafts leading to six power generating units located in the underground powerhouse, so the water pressure at the valve chamber is about 200 mVs.

During inspections, it had become apparent that there was an increased leakage from the rock in the valve chamber, which needed to be investigated more closely to ensure the safety of the power station. Verkís subsequently carried out detailed investigation on the rock, and in an attempt to prevent potential problems in the future, it was decided to grout the rock with polyurethane. Verkís was Landsvirkjun’s main consultant on the grouting design, and supervised the work carried out at the site.

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