MUSTBE

Pilot Site in Spotlight: Riga’s Sediment Pond and Treatment Wetland with a Park Area

A river named Šmerļupīte in Riga, Latvia has been heavily affected by the surrounding urban area. Environmental challenges are being addressed with a nature-based solution for stormwater management.

The Šmerļupīte river is 7 kilometres long, with a catchment area of 27 km². In the 20th century, the construction of railways and various residential areas affected the river’s ecological characteristics and increased the need to improve stormwater management in the future.
Photo: City of Riga

“Sustainability at its deepest level” – this is how Environment Management Expert Māra Reča from the City of Riga describes the nature-based solution (later in the text: NBS) developed for Riga’s pilot site. The site is located around the Šmerļupīte river, where environmental protection is a primary objective of the NBS.

– Some natural habitats will be restored. The area has huge recreational potential, Reča explains.

Stormwater from the surrounding, densely populated residential areas enters the river. Currently, 69,000 people work and live there, and the City of Riga has plans for further residential development. Various economic activities in the catchment area also affect the river’s water quality. For instance, there are active construction areas and a semiconductor factory. Some areas remain polluted due to Soviet-era industrial activity. As a result, water quality analyses of Šmerļupīte reveal high nitrogen and phosphorus levels, failing to meet both Latvia’s national stormwater standards and the MUSTBE project’s goals.

Mutual Learning and Valuable Experience

The pilot site is owned by the City of Riga. Co-operation has had a big role in the project, both on local and cross-border scale. Riga City Council City Development Department and Riga Technical University are working alongside MUSTBE project partners from Finland, Sweden and Estonia. Project Manager Marija Balabka from Riga Local Government emphasized the value of collaboration:

– Working together improves the city and increases our knowledge capacity. Many new things have been learnt, and the mutual knowledge gained from this experience will also be useful in the future, says Balabka about the importance of the partnership.

– We are educating our colleagues, just as we started by educating ourselves, Reča adds.

Developing innovative solutions is not always easy and can be compared to travelling on an unknown route. Challenges have been faced with the procurement for Riga’s NBS. According to Reča and Balabka, it has turned out that there are not many companies with the necessary expertise in multi-benefit NBSs. The reasons are probably related to the novelty of the expertise required and the relatively small population of Latvia – there are not many specialised experts. Despite these challenges, the procurement process is currently underway. In the current round, technical explanations have been refined, and more attention has been paid to the way things are expressed.

The primary goal of the NBS is environmental protection. Secondary benefits include flood risk management and the promotion of public health and well-being. Photo: Hanna Kajander

Smart Technology Will Be Used in Directing Stormwater

The NBS is developed to handle runoffs from intense street areas and to improve runoff water quality from areas with high concentration of hazardous substances. The water quality of both the river and its inlet at a lake indicates that some municipal urban wastewater is entering the stream. The lake has a high flood risk and a connection with the river Daugava and the Baltic Sea.

Runoff will be directed through a cascade of NBS treatment features, equipped with sensors to monitor water quality and flow rates. Based on the level of pollution, the NBS directs stormwater to either open features, such as detention basins or bioswales, or closed features, such as artificial wetlands that flow below the surface. Stormwater will be treated through filtration, retention, and evaporation. The benefits of stormwater detention include improved water quality, increased soil moisture and reduced demand for municipal water supplies.

In addition to stormwater management, the NBS also contributes to public health, well-being and social use. Once construction is completed, the area will provide recreational opportunities for the community.

The main beneficiaries of Riga pilot site will be residents of the neighboring areas of the river Šmerļupīte. The residential environment will be cleaner, as floods of polluted stormwater will be avoided. The city of Riga and other municipalities in Latvia and the Baltic Sea region will also benefit, as the results of the project will be public, and the replication of solutions will be encouraged. Photo: City of Riga

Facts about the Project

  • The MUSTBE project is led by Estonian municipality Viimsi.
  • In addition to Viimsi, other project partners are City of Tallinn (Estonia), municipality of Söderhamn (Sweden), City of Riga (Latvia), Tallinn University of Technology (Estonia), Satakunta University of Applied Sciences (Finland), and Riga Technical University (Latvia).
  • The project has seven pilot sites in total: two in Pori, one in Tallinn, one in Viimsi, one in Riga, and two in Söderhamn.
  • MUSTBE project (Multidimensional stormwater treatment in urban areas for cleaner Baltic Sea) is co-funded by the Interreg Central Baltic programme
  • Project duration: 1.5.2023–30.4.2026.
  • Project budget: 3,980,476.00 €.

Writers and editors: Krista Valkonen, Meri-Maaria Salo and Hanna Kajander