10.4122/1.1000001710 Meguro, T. Yamazaki, T. Study on effects for improvement of wet-weather overflow taking account of the behavior of pollutant load in pumping stations in combined sewer systems DTU Library, Technical University of Denmark (DTU) 2005 combined sewer overflow pumping station accumulated load discharge characteristic grit chambers drying traction/settlement load model-building Environment Planning Bureau, Environment Improvement Department Yokohama Public Architecture Preservation Fundation en Conference full text 10.4122/1.1000001709 application/pdf 1 In pumping stations in combined sewer systems, pollutants accumulate in stormwater grit chambers and wet wells. They can be stirred up and discharged when stormwater pumps are started, and consequently cause pollution in public water areas. An analysis of the behavior of pollutant load in pumping stations is required for accurate assessment of the pollution situation in receiving water areas and measures for improvement of such systems. The study team proposed a simulation (box) model for analysis of the behavior of load accumulated in pumping stations. Besides checking this model against actual data, they also made a quantitative assessment of the (load-reducing) effect of installation of stormwater tanks and drying of pumping station grit chambers and wet wells. The simulation results showed a good correspondence between the calculated and actual values for water quality. As for accumulation quantity, the model also made a good reproduction of the traction of deposits upon activation of pumps. Simulation for a year found that, relative to the case of no action, the yearly direct discharge SS load could be reduced by 26 percent by drying the grit chambers and wet wells and 85 percent by the combination of drying and stormwater tank installation.