Pollutant removal efficiency in two stormwater ponds in Sweden

Paper in proceeding, 1999

Open stormwater ponds have been frequently addressed as a method for treatment of stormwater since measurements show a considerable pollutant removal effect. Pollutant removal efficiency in two stormwater ponds in Sweden is studied where field measurements of inflow and outflow pollutant loads for several successive storm events are described. Cumulative effects of inflow and outflow pollutant discharges are studied and for the outflow a strong correlation to constant outflow pollutant discharges appears that indicate an independence of inflow pollutant load for the two ponds. Hereby, it becomes possible to extrapolate the annual loads from the ponds to the receiving waters of studied pollutants. The specific pond area (m2/ha) is 20 times larger in one of the ponds, which affect the pollutant removal efficiencies. A comparison between specific pond area and pollutant removal efficiency gave that the removal efficiency increases up to a certain level of surface/impervious area, 250 m2/ha, and above this level the increase is not as significant as below. Another factor that has an impact on the removal efficiency is the pond geometry.