Stormwater

Stormwater is rainwater or melted snow that runs off from roofs, roads, and other impervious surfaces. When heavy rain or rapid snowmelt occurs, stormwater can collect pollutants from these surfaces, such as oil, heavy metals, chemicals, and debris, before flowing downstream and eventually reaching rivers, lakes, or even groundwater. Since stormwater has specific characteristics that influence both treatment and management, it is important to understand these in order to plan and implement the correct treatment processes.

Irregular flow rates

Stormwater flow varies depending on weather conditions such as rainfall and snowmelt. Large amounts of precipitation can result in high flow rates, while prolonged dry periods may lead to low or even negligible flows. These variations impact both the treatment process and the capacity of the treatment system.

Diffuse pollution and varying concentrations

Stormwater collects pollutants from many different sources, such as oil, heavy metals, chemicals, and debris on roads, roofs, and other impervious surfaces. Since the water runs off from large areas and is mixed from multiple sources, pollutant concentrations vary depending on where the water is collected and how much time has passed since the last rainfall. During heavy rain, large amounts of dirt and particles may be washed away, while breaks in precipitation can lead to more concentrated pollutants.

Read about the Stena Recycling project, where we installed a stormwater system to manage large volumes of water from their stormwater pond.