Analisi sperimentale degli impatti sanitari-ambientali di scaricatori di fognatura mista e possibili misure di mitigazione

This study has been done to evaluate the environmental impact of the CSO (Combined Sewer Overflows) regarding Vallescura canal and to understand their responsibility on deterioration of the coastal water quality. The aim has been pursued through the implementation of dynamic rainfall-runoff simulation model called SWMM (Storm Water Management Model) provided by the Environmental Protection Agency of United States. As a first step, the main requirement defined by European, national and regional legislation about the quality measure established for CSO, were analyzed. The implementation of the model was done in two steps: primarily was realized the hydraulic pattern and then the quality properties were applied. During this phase various difficulties were encountered due to the lack of in-depth data relating to the sewage network. At the end several simulations were launched in order to analyze different scenarios. In terms of precipitation both events with a specific return time and a typical year were analyzed, while, in terms of quality was considered the impact of the first rainwater and of the utilities not connected to the sewage network. The pollutant considered are TKN, COD, TSS, BOD5 and Excerichia Coli. In the end it was found that for all the simulations, spillways that release the largest quantities, both in terms of flow rate and pollutant load, are located in the valley area. Specifically, the parameter that most impacts on the environment is the Excerichia Coli for which percentages of impact even greater than 30% has been obtained.