Transport of solid material in sewer pipe - the sample catchment of Cesarina (Rome)

Problems related to the impact of storm waters in the final outlet for urban sewer pipes have been studied thanks to the analysis conducted in an experimental sample basin drained by a combined sewer network, located in the city of Rome (S = 2015 ha); the chosen basin is the Cesarina - San Basilio catchment, situated in an area east of the centre of Rome, on the right side of the river Aniene. The aim of these measurements is the qualitative and quantitative characterisation of load waves occurring in the main sewer pipe during a storm event, as well as the analysis of erosion and transport of deposited solid material and the location of sewer trunks with high probability of temporary solid deposits between two consecutive storm waves. The complexity of solid transport phenomena implied the need for simplified analysis schemes and simulative models appropriately calibrated with experimental data, suitable for a technical solution of such problems. In particular, the validity of experimental records allows the calibration of a hydrodynamic model whose implementation facilitates the extension of data from a sewer trunk of the network to another. In the hydraulic model, a flow simulation engine has been used to solve the complete De Saint Venant equation under the hypothesis of mono-dimensional flow, and to represent full-section flow, pipe storage capacity, gushing-back phenomena, inlet and outlet energy losses and flow inversion. The paper reports on the main criteria on which the project and the realisation of the monitoring system are based, as well as the first experimental data collected. These records allowed a first calibration of a model for the sewer system created to favour the extrapolation of such data to the main network trunks.