The story of water—a functioning water infrastructure enables the modern world

YIT Corporation News April 17, 2019 at 07:30 a.m. 

Hiekkaharju water tower YIT
Hiekkaharju water tower YIT

Where does clean water come from? Where does dirty water end up? How is rain water removed from the streets? Water is not just our lifeline, but also an important part of our cities’ infrastructure. YIT is part of water’s entire journey from the clouds to the oceans.

There is no water coming out of the tap. Dirty water has flowed to the water systems untreated. The streets are overflowing with meltwater from the snow. You would notice the significance of a functioning infrastructure only if it no longer functioned. Infrastructure enables smooth urban living, but in reality, it is a relatively new phenomenon.

“The easiest way to think about a functioning water-related infrastructure today is to transport yourself back in time approximately 100 years. Where did water come from then, how did water supply work and what difficulties might there have been?” says Anne Piiparinen, Senior Vice President of YIT’s Industrial and Structural Engineering division.  

In the beginning of the last century, water was still drawn from a well, laundry was washed in natural waters around the year and most of the time, people had to rely on water carried from the well. As waste management was far from what it currently is, disease epidemics spread quickly in urban surroundings. A functioning infrastructure enables the modern world, and is the basis of our well-being.

YIT is part of constructing a functioning water supply infrastructure, all the way from the original source of water to clean water treatment and from booster plants and water towers to wastewater treatment plants and stormwater solutions.

Water treatment plants and water towers guarantee clean water

YIT’s entire history started with water supply. In 1912, the company’s first building contract was developing Porvoo’s water supply and constructing a water tower. In more than one hundred years, 119 water towers have been built and a few renovated. Water towers are an important part of our cities’ infrastructure now and in the future, as their task is to stabilise the network pressure and to function as a water storage that helps level off consumption peaks and ensure water supply, for example, during power cuts.

YIT’s more than one hundred years of experience from water supply construction is visible in the expertise in planning and realising projects as well as utilising comprehensive partner networks when developing new innovations. The construction of water supply plants, i.e. water towers and water treatment plants also demands expertise in job planning and concrete technology, process understanding as well as the ability to manage different specialised work methods.

“We have an understanding of how, for example, a water tower is connected to the water supply network and what can be done at each point without cutting off the water distribution and yet keeping the water clean,” Piiparinen explains.

YIT currently builds approximately 1–2 water towers annually. The number of residents and increased water consumption is also considered when planning new towers. Water towers are still famous landmarks: many towns and cities are known for their water towers. They are part of cities’ facades, and their architecture is often used to highlight the identity of local water services. At the moment, YIT has a particularly large water tower project in Hiekkaharju, Vantaa. The new Hiekkaharju water tower will safeguard Eastern Vantaa’s water distribution in the future as the area’s population grows.

Wastewater treatment plants are an important part of water supply

The water supply network is continuously renewed and expanded. In Finland, YIT currently is building the Blominmäki wastewater treatment plant in Espoo and renovating a sludge drying plant in Riihimäki. Excavation work is ongoing in Sulkavuori, Tampere for a large centralised wastewater treatment plant. In Sweden, YIT is expanding the Henriksdal centralised wastewater treatment plant.

Large projects, such as Blominmäki, respond to future needs by growing the water treatment capacity as the number of residents increases. New projects pay even closer attention to the needs of urbanisation and stricter environmental laws. As wastewater treatment plants are placed underground, more areas are available for construction and wastewater lagoons do not cause unpleasant odours for the nearby environment.

The basic process of the plants has not changed much during the last decades, as the treatment is mainly based on an activated sludge process. The biggest change is the third, i.e. tertiary treatment that has been added to the basic process. This treatment significantly reduces the amount of total phosphorus. The latest renewal is the purification of waste water with UV equipment.

“New treatment methods have landed in Finland during the last five years, but they have been implemented on a small scale and in an experimental sense,” Piiparinen explains.

Test plants and processes are being planned, and they will be an important development target in the future. The premises of the new plants are already prepared for future expansions required by new technologies. The primarily best solution for waste water treatment would, however, be that people consider the use of harmful substances and keep the amount of, for example, disinfecting cleaners to a minimum.

Green roofs benefit our environment

All water does not go through the water distribution and sewage system. Instead, it falls as rain or snow and ends up directly in the soil as stormwater. The changing climate causes challenges as rainstorms and floods become more common. In order to keep water from taking over the streets in our cities, YIT has developed and taken in use solutions for stormwater treatment. Among others, these include various water-permeating asphalts and green roofs. In a few locations, YIT has realised green roofs. Their size varies from the roofs of backyard buildings to wider complexes. Often, the requirement to use them comes from the local detailed plan or the area’s building code.

“Their number is increasing. However, building green roofs is more expensive compared to regular roofs, and they demand more maintenance,” explains Marko Oinas, Senior Vice President, YIT Business Development.

Green roofs not only make the urban environment greener, but they also slow down the flow of rain water naturally, without separate collection tanks. In addition, green roofs have been shown, at least in a calculated manner, to improve energy efficiency, sound proofing and air quality.

The realisation method of green roofs depends on the space below the roof as well as the pitch, area and planned vegetation of the roof. The organic part will usually hide the substrate, underdrainage and the solutions needed for the directing of the water, as well as the water and root insulation layers. Thus, the green roof and its load demand good planning, the right materials and regular maintenance. For example, the shopping centre Lauttis in Lauttasaari, Helsinki has a deck yard built on the roof of the shopping centre as the yard of the residential apartment buildings. The rain water flowing to the stormwater network is slowed down by the approximately 800 m2 of grass and bush areas planted on the yard decks, where water flows approximately half as slow as on a street paved with asphalt. In Tripla, approximately one hectare will also be green roofs in the future.

Pavement has a significant role in directing or stopping stormwaters

Continuous research and development of asphalt materials has always been a strategic priority of YIT’s operations. YIT has gathered a good understanding of masonry materials used nation-wide during its more than 100 years of operations. The pavement used on a road can have a significant role in either leading stormwater into soil or stopping its access.

“The pavement solutions we implement are always planned on a case-by-case basis. There is no ready-made, off-the-shelf recipe, as materials change and masonry elements are local,” says Vesa Laitinen, head of YIT’s asphalt laboratory in Finland.

YIT is constantly developing new specialised products that consider, for example, the permeability or impermeability of water. When asphalt that permeates water is used as a stormwater solution, the area’s rain water is steered through the pavement directly into the soil, from where the water is steered to the sewer with underdrainage. For example, the foundations of sports fields have for a long time been made of asphalt that permeates water, which means the artificial turf on the top dries quickly and the rain water is not left in puddles.

On the other hand, asphalt that is impermeable to water has significant environmental benefits as it is used to protect soil and groundwater from harmful substances. For example, roads that pass through groundwater areas, the bottoms of waste storage areas, refuelling areas and chemical tanker shielding pools are often made of dense asphalt. Denmark even has its own product for agricultural needs, YIT Farmfalt, which stops the nutrients used in animal feed from absorbing into the soil.

The next time you pour yourself a glass of water, take a shower or get your socks wet in a puddle on the street, remember just how long of a journey water has from a freely-flowing river to a water withdrawal plant, water tower and water treatment plant before being released back into the water system.

For further information, please contact:
Anne Piiparinen, Senior Vice President, YIT Finland Ltd, tel. +358 (0)40 823 2808,
Hanna Malmivaara, Senior Vice President, Group Communications, YIT Corporation, tel. +358 (0)40 561 6568,

YIT is the largest Finnish and significant North European construction company. We develop and build apartments and living services, business premises and entire areas. We are also specialised in demanding infrastructure construction and paving. Together with our customers, our nearly 10,000 professionals are creating more functional, more attractive and more sustainable cities and environments. We work in 11 countries: Finland, Russia, Scandinavia, the Baltic Countries, the Czech Republic, Slovakia and Poland. The new YIT was born when over 100-year-old YIT Corporation and Lemminkäinen Corporation merged on February 1, 2018. Our pro forma revenue for 2018 was approximately EUR 3.8 billion. YIT Corporation's share is listed on Nasdaq Helsinki Oy.