A chain reaction that started with one old pipe revealed the dilapidation of Helsinki’s water supply network.
Helsinki the cause of broken pipes is pipes that are too old.
The probability of a pipe failing increases as it ages, estimates the director of water supply at the Helsinki region’s environmental services (HSY) Mari Heinonen. He is responsible for the water supply network.
On Sunday, the rupture of a large trunk line running through Fleminginkatu caused a series of broken pipes, which left hundreds of residents without drinking water at worst.
New pipe breaks appeared on Monday morning in the city center’s Kaivokatu and Vaakatie in Haaga.
The joints and bends of old pipes may not withstand exceptional water pressure.
For example, the trunk line running through Vallila was built in 1940. The pipe, where the chain reaction of broken pipes originally started, was also built in 1940.
Water management technology professor Riku Vahala says that the chain reaction of broken pipes starts when the first leak point is isolated.
“When there is a large water leak, you want to plug the leak quickly, so that the leak does not continue until the end of the world and drain the entire water supply network.”
According to Vahala, the leak point is typically such that the valves around it must be closed. This leads to the fact that the water coming into the leak collides with the valve and tends to bounce in the opposite direction. In a collision, the kinetic energy of the water suddenly turns into pressure energy and a pressure shock situation occurs in the pipeline.
“When huge masses of water start colliding with each other in the pipeline, mechanical forces in different directions are created, which break the pipeline at its weakest point.”
It is difficult to prepare for sudden pipe breaks. For example, air valves have been designed into some trunk water lines to manage pressure shocks, but not all pipelines have them.
According to Vahala, in the event of a broken pipe, the only way to prevent damage is to close the valves slowly.
“The closing speed of the valve is important. If the water can be slowed down in a controlled manner, it is possible to prevent the situation from getting worse.”
In old pipelines, even this may not help.
Mere however, age does not tell everything about the condition of the network. Heinonen says that the water supply network built before the wars may be in better condition than the network built in the middle of the last century.
“At the time of intense urbanization, there was a shortage of better quality material,” says Heinonen.
Read more: At least seven pipe breaks in Helsinki – This is what is known about the cases
All right however, the fact is that under the streets of Helsinki there is a large network of water pipes in need of repair.
There are approximately 3,200 kilometers of water supply network in HSY’s operating area.
Its age varies: New networks are constantly being built in new residential areas, while water pipes from the very early years of the system are located in the core. The oldest are from the end of the 19th century.
The most water pipes were built between the 1960s and 1980s. The condition and remaining service life of the pipelines varies.
According to HSY’s estimate, these approximately 1,500 kilometers of pipelines should be renewed approximately 60–70 years after commissioning, i.e. within the next 20 years.
The service life of the water pipes being installed now is estimated to be up to 100 years.
Bridge at the moment, the water supply network is being renovated at a rate of 20–25 kilometers per year in the capital region.
“The amount is too small considering the history of restructuring and the future, and it should be increased,” states Heinonen.
HSY’s 2021 evaluation report states that there is a total of approximately 530 kilometers of repair debt in the water supply, wastewater and mixed sewer network.
For the next ten years, 500 million euros have been reserved for network renovations. However, according to Heinonen, that is not enough, because the “big age groups” of the network are entering the restructuring period.
Even now, a significant part of the investments have to be financed with debt, which, according to Heinonen, is not a healthy solution. Heinonen says that this will lead to an increase in water taxis in the future.
On Sunday the series of events that started turned out to be exceptionally extensive, but it did not surprise Heino.
Sometimes pipe breaks are caused by external causes, such as a digger being hit. This time, however, the reason was technical.
The root cause of the pipe breaks that started on Fleminginkatu, or the triggering factor, will probably be found out during this week, but we can already say that the leaks that followed the first pipe break are related to the failure of the material.
Until the repair debt is settled, more pipe breaks can be expected.
“The probability of pipe leaks increases as the network ages,” says Heinonen.
Read more: Politician Osmo Soininvaara: Helsinki’s pipes are in shameful condition
Helsinki technical director of the urban environment industry Kari Pudas says the responsibility lies with HSY.
According to him, the city does not have an accurate picture of the condition of the pipes running under the streets.
“The risks and an overview of the network’s condition are for HSY to evaluate,” states Pudas.
Pudas emphasizes that the statutory task of the municipal corporation is to take care of water supply in its area of operation. It also means implementing renovations at HSY’s own expense.
HSY’s renovations are often implemented as joint projects with the city. When the infrastructure under the street needs repair, it makes sense in every way to carry out all possible repairs at once. At the same time, for example, a new tramway network or bikeway network may be built on top of the street.
Otherwise, all street work would always require a new trench, which would be bad not only for the wallet, but also for the nerves of the townspeople.
Despite the joint projects, the city cannot influence HSY’s renovation schedules, says Pudas.
However, as the owner, HSY always has the right to open the street and start work, whether it’s about cables or the water supply network, Pudas points out.
“The city is of course concerned about the matter and is responsible for making sure that the street is available, but the operational responsibility lies with HSY”, Pudas repeats.
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