‘It all happened so fast’

On 21 June, a storm hit the Misox valley in the canton of Graubünden hard. Six Axpo power plants were also affected. Not all of them have yet returned to operation.

Walter Zala, Deputy Head of the Misox Power Plant Group, still can't quite believe it today, around three months later: ‘80 litres of rain per square metre in two hours, 120 litres in a whole day, unbelievable.’ The storm that hit the Misox valley in the canton of Graubünden on 21 June 2024 was extraordinary. And even worse: it was not foreseeable to this extent. ‘Normally, we receive warnings when severe storms are imminent,’ he says. But before that day, there were no special weather warnings. The consequences were catastrophic: three deaths, houses completely washed away or damaged, parts of the A13 motorway destroyed – and the Axpo power plants were partially severely damaged and had to be shut down.

‘However, the plants were always in a safe condition.’ According to Walter Zala, this was one of the few pieces of good news in these difficult days. In some cases, the damage was enormous – and some of it has not yet been repaired. “The biggest challenge was to get an initial overview of all the damage, it all happened so quickly.” In addition, the mobile phone networks were temporarily down, which made communication between employees extremely difficult. The army quickly provided helicopters for the emergency teams. ‘But we only got an accurate picture during the next day.’ 

Of the six Axpo power plants in Misox, the ELIN (Elettricità Industriale SA) plants were hit hardest: the Grono plant has been out of operation since 21 June and will not be back online any time soon. The reason: the storm washed huge amounts of sediment and debris into the Roggiasca reservoir. As a result, a lot of mud entered the approximately three-kilometre-long tunnel to the pressure pipe that carries the water to the Grono plant. The consequence: a viscous, approximately half-metre-high layer of mud still blocks a large part of the tunnel. Workers have been clearing the mud since July  (see here the report on the RSI television). It's painstaking work, as the tunnel is barely two metres high and not much wider. The mud has to be removed shovelful by shovelful using a small excavator. ‘We're only making progress of around 15 metres a day.’ Since July, around 400 metres of mud have been cleared. It's easy to do the maths: it will take many months before the area is completely cleared. What's more, five of ELIN's water catchments were buried and partially destroyed. Here, too, it will take some time before they can be fully restored to working order. 

The OIM (Officine Idroelettriche di Mesolcina SA) plants were more fortunate. The storm damaged two water catchments, which are now back in operation. In addition, water, mud and debris dislodged a penstock at the Lostallo power plant, causing an interruption in operations of around five weeks. Fortunately, the Calancasca SA power plants were largely spared, and were able to resume electricity production after a few days' interruption. The two small power plants Tecnicama and Ogreda were also affected, with the latter still at a standstill.

What will all this cost? ‘It's difficult to say, as we still don't know exactly how long the production outage at ELIN will last,’ says Walter Zala. However, the cumulative costs for maintenance and the production outages are likely to run into the millions. At least the majority of the repair work is covered by the insurance, except for a deductible. But Axpo will have to bear most of the production outages itself.

So much for the material impact. The human and emotional consequences of the storm are probably more serious. Many people know each other in the southern Grisons valley. The shock and grief over what they have experienced are still deeply felt. And there are stories that will not be forgotten quickly. One example is Aurelio Troger, a technical employee in the control room at the Soazza control centre, who suddenly found himself saving lives (see video statement): ‘I had actually already finished work on Friday evening, but I sensed that something was wrong,’ he says. ‘It was extremely loud outside, and you could hear falling debris and rushing water everywhere.’ So he decided to stay in the control room. Luckily so – because a few minutes later he received a phone call from a neighbouring residential area. A mudslide had taken the eleven residents by surprise and they were unable to escape from the danger zone on their own. So it was Aurelio who rescued the severely shocked people from the damaged houses and brought them to safety at the Soazza centre. ‘Fortunately, it was still light,’ he reflects, ‘at night the rescue would have been impossible.’

Nevertheless, there were also positive moments in these difficult days. ‘The storm brought us even closer together as a team,’ Walter Zala is convinced. ‘Everyone volunteered immediately, everyone wanted to help, everyone pitched in, and some even came back from holiday.’ And valuable support also came from the Axpo headquarters in Baden, for example from Hans-Peter Zehnder, Head of Hydraulic Production at Axpo. Walter Zala: ‘I am personally very grateful to him, because he was always there for us in these difficult moments and gave us his full support’.

Now, about three months later, it is time to look ahead again. What does it mean for Axpo as a power plant operator when storms become more frequent and intense? Should the power plants be shut down as a precaution during every thunderstorm? ‘No, that would lead to significant production losses and would affect the security of supply,’ says Walter Zala. ‘But we need even more accurate weather forecasts in order to be able to react in time in an emergency.’ He is also thinking of technical solutions, such as systems that constantly measure water turbidity and automatically shut down the plants when limit values are exceeded. However, the employees on site remain crucial: ‘They have made a decisive contribution to minimising the consequences of the storm, and that will continue to be the case in the future.’