Author(s): Giuseppe Del Giudice; Corrado Gisonni
Linked Author(s): Corrado Gisonni
Keywords: No Keywords
Abstract: The city of Naples (Italy) is well known for its hilly landscape, along with a peculiar geology characterized by volcanic soils (i. e. tuf and pyroclastic rocks). The development of the sewer system serving the urban area has been strongly constrained by these factors. In particular, several drop structures were realized in order to connect the modern urban drainage system (realized in during the last decades) to the early sewer mains realized at the beginning of the nineteenth century and serving the downtown districts located at the sea level. The purpose of these drop structures is twofold: (i) to convey the storm runoff toward the sea through the existing sewer system located at lower elevations, and (ii) to by-pass insufficient sewer channels. Most of the drop structures were realized according to the‘vortex drop shaft’scheme, mainly for drop heights larger than 10 meters, up to 80 meters. The proper operation of these structures is crucial to prevent flooding and guarantee the urban safety. The paper aims to describe the most crucial aspects of the hydraulic behavior of the vortex shafts along with some examples of malfunction of these structures. Laboratory experiments were conducted to test existing vortex dropshafts and improve their hydraulic capacity; some relevant results are finally presented, along with pertinent practical issues.