WaterTreatmentPark

Summary

The municipality of Viimsi, close to Estonia's capital Tallinn, is situated at a peninsula - and on 70 meters of blue clay, with only a thin layer of soil on top. Therefore, the ability of the ground to retain water is very limited. Especially during heavy rain events, the stormwater drains very quickly into the Baltic Sea, taking nutrients and hazardous substances with it.

Viimsi municipality has conducted multiple projects by now to retain and treat stormwater. The WaterTreatmentPark project is one element of these efforts. Two ponds in the city's Manor Park, from which stormwater eventually drains into the sea, are going to be reconstructed to slow down the waterflow, allowing nutrients (nitrogen and phosphorous) and hazardous substances (heavy metals, chemicals, pesticides and other) to settle down. The nutrients are consumed by plants put into the reconstructed ponds for this specific purpose.

As a result, the city plans to retain around 250 kg of nitrogen and 5.4 tonnes of suspended solids per year. The latter are a carrier of phosphorus and hazardous substances and thus a proxy measure of the efficacy of the project. A monitoring system will evaluate how effective the project really has been.