Sustainable urban drainage systems (SUDS) can significantly reduce runoff from urban areas. However, their potential to mitigate acute river impacts of combined sewer overflows (CSO) is largely unknown. To close this gap, a novel coupled model approach was deployed that simulates the effect of realistic SUDS strategies, developed for an established city quarter, on acute oxygen depressions in the receiving river. Results show that for an average rainfall year the SUDS strategies reduce total runoff by 28% - 39% and peak runoff by 31% - 48%. Resulting relative reduction in total CSO volume ranges from 45% - 58%, exceeding annual runoff reduction from SUDS by a factor of 1.5. Negative impacts in the form of fish-critical dissolved oxygen (DO) conditions in the receiving river (<2 mg DO/L) can be completely prevented with the SUDS strategies for an average rainfall year. The realistic SUDS strategies were compared with a simpler simulation approach which consists in globally downscaling runoff from all impervious areas. It indicates that such a simple approach does not completely account for the positive effect of SUDS, underestimating CSO volumes for specific rain events by up to 13%. Accordingly, global downscaling is only recommended for preliminary planning purposes.

Odours emerging from sewage networks are unpleasant, can cause health impacts on sewer workers and impair public perception of the operator companies. Corrosion is one of the causes for the cost of repairs for damages to wastewater systems in the public sewage network, which are rising extremely [DWA, 2004]. Both phenomena can have their origin in biogenic acid corrosion that is illustrated in this report. The Kompetenzzentrum Wasser Berlin (KWB) commissioned the Technical University Berlin and the Material Testing Institute of Berlin-Brandenburg to give a report on: • State of the art on control systems for odours and corrosion problems in sewer networks, (i) State of the art on sensor technologies for water, gas and corrosion parameters to follow corrosion and H2S production, (ii) Investigation on the feasibility to develop a three-phase model to predict the mass transfer of H2S from water to the gas phase and to the wall of the pipe through the biofilm and (iii) Elaboration of a draft of the functional and technical specifications for a sewer network pilot plant.