WaterTreatment Park

The Viimsi municipality with around 23,000 inhabitants at the Estonian Baltic Sea coast is located on a peninsula – and on 70 meters of blue clay that water cannot penetrate. This means that the stormwater runoff from rain and melting snow, carrying nutrients and pollutants, almost directly discharges into the Baltic Sea.

In a range of projects, the municipality has improved its stormwater system in recent years, unsealing urban surface area so stormwater can seep away and be filtered before it runs off into the sea, and increasing water retention, while also installing a meticulous monitoring system . The goal of this project is a nature-based stormwater treatment system by modifying two ponds in Viimsi’s manor park, which is the confluence point of stormwater from a 75 ha catchment area. 

Broadly speaking, the measures consist of reshaping the ponds, including their in- and outlets, to act as a buffer and slow down water flow, as well as planting vegetation that has a filtering effect. Our partner expects to be able to filter out 250 kg of total nitrogen and 5.4 tons of suspended solids per year, the latter one acting as a proxy for phosphorus and harmful substances. A monitoring system will be put into place to evaluate the efficacy of the project afterwards.