Hydraulic Transient Study of Narragansett Bay Commission CSO Storage Tunnel

Abstract

One concern of the tunnel system is the potential for hydraulic transients during the tunnel filling process. Under some conditions, strong storm inflow to a tunnel may generate severe hydraulic surge in the tunnel, and consequently water may shoot up from the dropshaft like a geyser, which may result in structural damage to surface facilities and other environmental problems. For example, in Minneapolis, USA, a severe storm in 1997 caused a geyser 17 m above the ground from the storm water tunnel. The purpose of this study is to examine the possibility of any geysering and other hydraulic transient problems during the tunnel filling process based on the proposed tunnel configuration design and inflow under different tunnel operating conditions using our wellestablished hydraulic transient computer simulation model (MXTRANS).