Periodic variations in stormwater quality in the roadside ponds system and its possible uses

Abstract

Abstract In connection with the growing deficit of water and problems in satisfying certain needs, stormwater ponds collecting runoff from impervious surfaces are increasingly often considered a potential water source. This paper evaluates the pollution level and variations in the quality of stormwater stored and pre-treated in reservoirs located next to new roads in the metropolitan area of Lublin (south-eastern Poland). Possibilities of water reuse were also assessed. The studies took into account changes in weather conditions and traffic intensity. Quality tests were carried out seasonally (16 measurement dates in total). Selected physical, oxygen, nutrient and salinity indicators were analysed. High variations in the concentration of total suspended solids, NH4+, NO2−, TP, PO43− and Cl− were observed (74–216%). On some measurement dates alarming conductivity, pH, suspended solids, COD, TP and Cl− values were recorded. Variations in stormwater quality are greater at the first stage of using the system of ponds, and the mean level of pollution stabilises several years after its construction. Changes in traffic intensity have no significant effect on the degree of pollution of the stored water. The highly variable water pollution level makes it difficult to precisely identify periods in which the use of ponds poses the lowest risk. Stormwater management should be accompanied by thorough analyses of water quality (constant monitoring) and the evaluation of possible risks to the environment.