Frequently asked questions about the construction of the Esplanade sewer tunnel

On this page, we have provided answers to questions concerning the Esplanade sewer tunnel. We will add to the list as new, recurring questions arise.

Why build a sewer tunnel?

The new sewer tunnel will eliminate the current problems related to the condition of sewerage and improve the management of wastewater overflows caused by heavy rainfall, thereby reducing the burden on the Baltic Sea. In addition, it will create an opportunity to separate the existing poorly-functioning mixed sewers, which are currently causing frequent maintenance requirements, odour nuisances and an increased risk of damage.

HSY's General Meeting has decided on the development of water supply in the Esplanade area in November 2021. The project, which was approved by the General Meeting, includes significant water supply renovation measures for Pohjoisesplanadi and South Eteläesplanadi and the surrounding streets. The water mains and main sewers in the Eteläranta area will be renovated and a stormwater network will be built in the area. The central first part of the plan is the construction of a new sewer tunnel from the Esplanade to the Munkkisaari-Mäntymäki sewer tunnel. It is only after the construction of the sewer tunnel that the above-ground network arrangements will begin in the late 2020s.

What kind of noise will the construction of the tunnel make?

Received noise permit limits apply to excavation and construction work. There are so many different sounds in the city centre area that the sounds of tunnel construction are not as clear as, for example, in a small-house area. The sounds of blasting are the loudest in tunnel construction. Drilling noises can be heard when the area to be excavated is nearby. However, it is very case-by-case how well the sounds of blasting and drilling can be heard. If the building is founded directly on rock, the sound carries better. In the case of buildings built on thick layers of soil, the sounds are less audible.

What impact will the work have on traffic?

The tunnel will be constructed underground, with the exception of the construction of a vertical shaft and sewer network in the Esplanade Park area. This means that there will be no major exceptional arrangements with regard to traffic in the area except for the sewer connection works on Pohjoisesplanadi and Fabianinkatu in the winter of 2026–27. The impact of these works will be short-term. Every effort is being made to plan all above-ground work in such a way that it will cause as little harm as possible to people moving around in the area.

Why are the streets being torn open?

No streets will be excavated during the construction of the sewer tunnel except for the sewer connection works on Pohjoisesplanadi and Fabianinkatu in the winter of 2026–27.

It is only after the construction of the sewer tunnel that the above-ground network arrangements will start in the late 2020s. This means that the water mains and main sewers in the Pohjoisesplanadi, Eteläesplanadi and Eteläranta areas will be renovated and a stormwater network will be built in the area. This will bring the area’s water supply to a new level while also separating the existing poorly-functioning mixed sewers, which currently cause frequent maintenance requirements, odour nuisances and an increased risk of damage.

What is happening in the Esplanade Park in the summer of 2024?

In the summer of 2024, soil and bedrock studies will be conducted in and around the Esplanade Park area for the planning of the tunnel. The studies will be carried out by Taratest Oy.

What will happen later in the Esplanade Park?

In the Esplanade Park area, we are renovating the wastewater sewer and building a vertical shaft through which the wastewater will be led into the wastewater tunnel to be built. If possible, the construction will be carried out during the winter season of 2026–27 at a time when it will cause as little harm as possible to the Park’s users.