Last year’s heavy rainfall and intense storms caused problems in many places across the country. In Heby Municipality, activity was frantic when the heavy downpours that followed the persistent summer rains of 2023 caused the rivers around the sewage treatment plant to overflow.

The prolonged rainfall, combined with the storms, led to the rivers overflowing and flooding the area around the treatment plant. It was after this event that Heby Municipality got in touch with Aqua Robur.

Initially, they were interested in digital rain gauges, but after a presentation of Aqua Robur’s products, Heby decided on a solution that combined both level meters and rain gauges, which were placed at strategic locations along the system. The data from the sensors and meters are visualized in Aqua Robur’s IoT portal, making the analysis work significantly easier. Various types of alarm functions can also be configured for the flow or level limits of your choice.

Complementary Rain Gauges Show Correlation 
Heby Municipality has a total of six sewage treatment plants. As a complement to the level meters, rain gauges were also placed around the four largest towns: Heby, Östervåla, Morgongåva, and Tärnsjö.

– Sure, you can get data from SMHI’s stations, but it’s not always accurate enough for our needs. During the heavy rains in September 2023, for example, Morgongåva received almost no rain – while we experienced flooding in Heby, 60 km away. Now we’ve placed rain gauges in the locations we know we need to monitor, says Niclas Lind.

– The rain gauges help us detect the correlation between rainfall and inflow. Now we can see it in a completely different way, Niclas continues.

– We constantly receive too much water at the treatment plants. It could be from misconnected pipes or from the ground entering through joints. This is a great tool to help us improve. We have several treatment plants and communities, and this can help us prioritize the right actions in the right place when it rains heavily, says Niclas Lind.

Level Meters Solved Inflow Problems 
In 2023, disproportionately large amounts of additional water were noted flowing into Heby’s sewage treatment plant during rainstorms. It was suspected that some of this was coming from a nearby sewage association connected to the municipal network, but there was no hard data to support such a claim. It was clear that something needed to be done.

To start, a level meter was installed in a strategic location where the nearby sewage association’s system connects to the municipal network. It immediately became clear that every rainstorm resulted in disproportionately large inflows.

– The association pays a fee based on their water flow. Thanks to the level meter, we could confirm that they were having inflow problems, and it was a relief to be able to show concrete figures for this, says Niclas Lind, water and sewage engineer at Heby Municipality.

– Thanks to our concrete data, we were able to help the association locate the problem, which turned out to be a damaged pipe at a forest ditch where water was leaking in through a joint, Niclas continues.

Monitoring Rivers, Dams, and Lakes 
After the 2023 floods, it became important to monitor the water levels in the rivers. Two rivers converge in the middle of Heby, and exactly at this point, where the two rivers meet upstream from the treatment plant, level meters were installed.

At the height of the treatment plant, where the rivers join, a level meter with an SMS alert was installed, sending notifications to the person responsible for water and sewage if the water rises above a critical level. There are also level meters in the river in Östervåla.

The dam at the outlet of the swimming lake Myran in Huddunge has also been equipped with a level meter. The dam has so-called fixed weirs, a basic self-regulating system with spillways of 25 x 100 cm, where water can overflow when the water levels rise in the dam. But during persistent periods of rain, the flows become so high that the spillways are insufficient, and the dam gates must be opened manually. The meter in the dam now automatically sends SMS alerts when a preset level is reached. All data is displayed as clear graphs in the IoT portal.

– Monitoring the river levels is important. If they rise too much, some stormwater outlets can end up submerged and push water back into the pipe, potentially causing floods and damage. With the level meters, we can stay ahead, Niclas explains.

There are also level meters in the dam and its gates at the outlet of Ramsjön in Morgongåva, where the water continues to flow down toward Örsundsbro and eventually into Mälaren.

– Next year, we’re going to renovate another dam, and I want to have level meters there too, says Niclas decisively.

Great Benefit from Aqua Robur
All overflows from the treatment plants must be reported to the supervisory authority, which in this case is the Environmental Unit of Heby Municipality. Environmental reports are also submitted annually for the three largest sewage treatment plants.

– The level sensors and rain gauges give us a much better basis for decision-making when it comes to the water and sewage system. And if the authorities question why we’re overflowing, we now have the data, black on white, instead of just saying, “it rained,” Niclas jokes.

– We’ve gained a lot from Aqua Robur’s solutions, and the more we work with them, the better we understand how the rivers and rainfall affect the treatment plants, he says.

– I particularly like “Insights”, where we’ve combined the graphs from the level meters and the rain gauge at the Heby treatment plant into the same view. We can clearly see how they follow each other, and we can observe the correlation between rainfall, inflow, and levels, says Niclas.

– We’re very satisfied so far. I just wish we had this in place last year when it rained so much. There were enormous amounts of water, concludes Niclas Lind.