Sampling of annual pollution loads in a combined sewer and a stormwater sewer during rainy weather

Stormwater runoff at sewer overflows (combined sewer overflows and stormwater outlets) can be the dominant path of entry into natural water bodies for some micropollutants from urban areas. Within the scope of an Austrian research project, two annual mixed samples proportional to the annual runoff of an entire sampled year were generated at a stormwater outlet and a combined sewer overflow in order to determine the resulting annual micropollutant loads by measurements and to compare them with theoretically determined potentials for the micropollutant loads from the literature after a detailed analysis of the surface conditions in the catchment areas and corresponding material flow analysis. The chosen sampling strategy, the experience gained during sampling and the results obtained from the sampling are described and discussed in the article.