2021

High water in 2021

Joyce Nelissen (WML) about the impact of the high water in 2021

In July 2021, Limburg was afflicted by extreme high waters. Heavy rainfall in the river basin caused water levels to rise significantly in the Meuse, its tributaries, and the streams in Limburg resulting in severe flooding. How did WML ensure that consumers could continue to have good drinking water available during the crisis?

"It was very tense," says WML director Joyce Nelissen. As chair of the drinking water policy team in Limburg, she was the final decision-maker during the flood in 2021. "The high-water levels were very unexpected. We know of course that the climate is changing. But in each of the three years prior to 2021, we were confronted with hot and dry summers. But that it could swing round in one year to extreme rainfall, and in the middle of the summer period at that, was something new. We were indeed prepared for high water, but not in the summer."

The flow rate of the Meuse rose to 3000 m3 per second. What were the consequences? "Because the high water was so extreme, it wouldn’t have taken much more for our head office to end up underwater. The provincial government buildings were flooded. If the water had risen to the car park, this would have happened to us too. It was within three centimetres.

It would have had major consequences for our ICT facilities. Drinking water production is automated after all – ICT is crucial to this. We therefore immediately decided to evacuate and moved all our ICT facilities to a safe place."

Consequences for primary production process

What were the further consequences for WML's primary production process? "We had trouble with the high water at a couple of sites, but the most serious problem was that the production site of Roosteren was flooded. The consequences were major because our clean water reservoirs were contaminated with water from the Meuse. This was able to happen because our drinking water reservoirs were indeed designed to allow excess produced water to be discharged into the Meuse, but not to keep out Meuse water from outside.

Since Meuse water ran inside, our drinking water stock became unusable due to contamination. We then diverted the supply route via some other sites in the vicinity of Roosteren. This was possible because our network has a cluster structure. We can guarantee the continuity of the water supply thanks to transport pipes between the production sites (within the clusters). I am proud and relieved to be able to say that the supply to our customers fortunately was never in danger."

Difficult decisions

"The fact that our production site was flooded is one thing, but that it happened during the summer holiday did make it extra troublesome. Due to the holiday period, we of course had to cope with lower staffing levels. On top of this, the flood also affected our staff personally, because they live and work in Limburg.

A crisis organisation was again initiated at the WML head office. In the second phase of the high-water crisis, bacterial contamination arose in the pipe network. Normally speaking, we then clean out the pipes by flushing and draining. But the contamination persisted, and on top of this it was summer.

We became concerned in case we were confronted with a high drinking water demand and high temperatures. If it became too hot, we would not be able to keep supplying all our customers. We then had to opt for chlorination in order to make the transport pipework bacteriologically reliable. After this, we could put the pipe back into use.

This was the tensest decision. Chlorination isn’t something you do just like that. Our colleagues at Evides were of great help to us at that time. They moved a mobile chlorination plant to Limburg. We were able to sort it all out together, but the Roosteren site was out of operation for no less than 10 weeks."

Future-proofness

The fact that WML could continue to supply drinking water to all its customers under these circumstances is quite an achievement. Can we therefore conclude that WML is ready for the future? "After everything was finished, we had an external evaluation done by the Berenschot bureau, and it concluded that we had indeed done very well. We had only just started with our crisis organisation on 1 July 2021, and the high-water emergency happened as early as 15 July. Big compliments to the organisation; I’m a proud director of WML.

But whether we can now conclude that we’re ready for the future? Naturally, we don't know that. We do know in any case that many climate developments are turning out to be more complex than was expected and happening at a faster rate. The extreme high water was a confirmation that we must continue to exercise with situations whose extremity we cannot envisage, but for which we nonetheless must be prepared. We must also consider other themes, such as cybersecurity. We therefore continue to train for all possible crisis incidents. In this way, we manage our primary drinking water process for now and for the future.