Stories

If building power plants had been a sports discipline, Offervann would have qualified as an extreme sport. Injury prevention has therefore been a top priority.

MapOffervann small-scale power plant

> Began in 2012, due for completion in autumn 2015

> Located in Adamselv regulated water area in Finnmark, Norway

> Uses the waterfall between Offervann dam and Store Måsevann Lake

> Water drop: Varies between 7.9 and 12 metres, with an average of 10 metres

> Installed capacity: 2.2 MW

> Annual production: 7 GWh

> The turbine is positioned 15 metres below ground level

> Statkraft's northernmost hydropower plant, along with Adamselv

> Offervann dam has also been rehabilitated during the development project, and a channel has been constructed in Store Måsevann River

The weather is calm, and the sunset bathes the mountain plateau with a golden glow. A tourist with a kayak mounted on the car roof waves and smiles to the workers as he passes by. It all seems so utterly peaceful.

However, the strong ropes mooring the portable site cabins to enormous boulders tell a different story.

Dark and cold

"This has been a challenging project," says Vidar Bolle, Statkraft's project manager for Offervann. "The distances are vast, the roads narrow, and the climate really tough."

Statkraft's northernmost hydropower plant is located at 70.4 degrees north in the county of Finnmark in Norway.

Although the late summer evenings are bright and mild, the winter is correspondingly dark, cold and demanding. There is barely half an hour of daylight at the darkest point during the winter half-year. In 2012 and 2013, work had to be suspended during October due to massive snowfalls. After three arduous construction seasons, the power plant is finally ready for commission.

The fact that it has taken so long to build does not mean that the plant is big. In fact, it is barely visible from its location between the Offervann dam and Store Måsevann River in the Adamselv regulated water area.

"In a Norwegian context, the power plant is unusually small," says Bolle. He turns to Ivar Johannes Hågensen from the Sweco company and asks, "In fact, have we developed any other 10-metre water drops in Norway?"

Hågensen is a contract construction manager, but has been following Offervann for many years. He previously worked in Statkraft and was involved in planning the project.

Watertight

"I doubt it," says Hågensen. "The reason why developing it is profitable at all is that we make use of existing infrastructure. Previously, the water passed through a lock gate between the two reservoirs down to Adamselv power plant. Now we use the water twice. In addition, the power line was already there, so all we had to do was connect to it."

Having such a small water drop meant that a powerful turbine was needed.

"Andritz Hydro has built a low-pressure turbine that measures almost four metres in diameter," says Bolle. "Hauling it up here was no joke."

The turbine is positioned 15 metres below ground in a shaft cast in watertight concrete.

"The concrete was transported by road from Alta, which is 300 kilometres and three mountain passes away. During the first castings, we had to hire extra vehicles to provide a 24-hour shuttle service."

We are now into our third construction season without one single lost-time injury. That's something I'm proud of.

Injury prevention

The challenges related to transport and winter road conditions are two of the reasons for the heavy investment in safety in the project. Throughout the construction period, Statkraft has had one or two safety health and working environment coordinators on site to ensure continual focus on health and safety.

"So far we haven't had one single losttime injury," says Bolle. "That's something I'm proud of." He gives much of the credit for that to the vigilant coordinators Even Walseth and Jan Olav Olsen. "They've done a brilliant job!"

However, they had a close call one ice-cold night in December last year.

"The weather conditions were bad, with winds and blizzard," says Olsen. "We were in a convoy, driving behind a tipper truck, and had come quite high up when the truck suddenly slid off the road and plunged down towards the lake. Those of us sitting in the vehicle behind rushed out, fearing the worst. We had some nerve-racking seconds before the tipper truck stopped and the driver climbed out. We considered turning back, but the road had already snowed over behind us, so we just had to start walking the final hundred metres or so in the dark and in blizzard conditions. There were strong winds and the temperature was 14 degrees below zero."

Once they arrived at the site cabin, they gave the driver a thorough medical examination and reported the incident according to procedures.

"The driver was fine, but he was probably in shock," Olsen explains. "He wandered around in his T-shirt in sub-zero temperatures before we managed to get him indoors. A helicopter was put on standby in Lakselv in case we needed to fly him down, but fortunately he was fine. He was back on the job the next working day."

Inside the power plant
The weather shifts incredibly fast up here. We often had to clear snow several times daily due to steep drifts and blizzards.

Risk analysis

However, this incident had implications for security levels.

"Since the road has been a continual challenge in winter conditions, we hired a scooter and sleigh so that we had some form of emergency preparedness on site, and we hired a contractor to clear the snow instead of doing it ourselves," says Walseth.

He says that they often had to clear snow several times daily due to steep drifts and blizzards, and adds, "The weather shifts incredibly fast up here. We had a German engineer with us the day the tripper truck went off the road. By the time we got back that evening, we had starry skies. In addition to the moon, the northern lights lit up the magical landscape. He was ecstatic, and took loads of pictures. He said he'd experienced more in one day up here than a whole year at home."

The two safety health and working environment coordinators are both happy and a little sad that the project is now completed.

"It's been incredibly exciting and instructive," says Olsen. Both he and Walseth started as trainees in Statkraft, in 2008 and 2012 respectively. Health and safety has been a fixed item on the agenda at all project meetings, and they've had good and close dialogue with the contractor.

"The fact that we as the client have been on site with dedicated personnel all the time has been extremely important," says project manager Bolle. "They have carried out ongoing risk analyses and identified potential safety risks along the way."

Tough as nails

It is unlikely that the focus on health and safety was as strong when Store Måsvann Lake was developed in the 1970s. Everyone knows the story about the son of the site manager whose upper body was perforated by a reinforcement bar.

"He was working there during the summer when he fell from a height and was impaled," says Bolle. "Incredibly, no vital organs were hit. His colleagues managed to cut the bar and transport him to the nearest village and phone connection. The distances were long, and he wasn't seen by a doctor until the next day. Fortunately it ended well, and he was back on the job the following summer."

The Offervann lake

Ole Christian PoveniusPower plant manager Ole Christian Povenius is ready for a new and long polar night at Offervann.

Sacrificial site

The project has not only placed emphasis on safety, but also on the environmental aspect.

The Offervann dam is situated in the midst of reindeer grazing district No. 13, an area of natural beauty that is also used for grouse hunting and fishing when weather permits.

The mythical mountain Offerfjellet (Vadasbak'ti), which towers over the Offervann dam, is an ancient Sami sacrificial site.

"The Sami reindeer herders were involved at an early state in the project, long before construction began," says Bolle. "Together, we agreed on periods when no blasting work should be carried out, namely during the reindeer mating season in the autumn and during calving time in the spring. For the rest of the year we have given good notice of blasting work via text messaging. The fact that we have taken them seriously has meant that we have avoided conflicts."

The visible signs of environmental intervention are minimal because the power station lies below ground level and the infrastructure was already in place.

Glowing

Pushak, a firm of architects, has transformed the roof of the power station into a viewing point across the lakes, equipped with a table and benches.

The concrete structures will be clad with a timber picket. Integrated lighting will make Offervann glow in the dark and show that here, in the middle of the plateau, pure energy is being produced.

Text: Jenny Bull Tuhus
Photo: Jannecke Sanne Normann
The article is also published in Statkraft's magazine People & Power no. 3/2015