Pollution reduction in receivers: stormwater tanks

Urban runoff discharges in receiving water are a significant source of pollution. Storm-water tanks are one of the most effective facilities used for reducing the impact of first-flush pollution. Nevertheless, because the system performance depends on many parameters, design criteria for storm-water tanks are not completely consolidated in the literature. To assess the influence of the rainfall regime on the system performance, extensive numerical simulations from 45 rain gauges in Campania, Italy, were calculated. A typical Italian urban catchment was considered in simulations. Hydrographs and pollutographs were generated to analyze the operation of different sewer and tank configurations. All simulations showed a negligible influence of the rainfall regime on the phenomenon, thus suggesting a simplified approach to estimate the average pollution reduction by using storm-water tanks. The analysis shows good agreement between the values estimated from the proposed approach and the results provided by continuous simulations.