Understanding Tunnel Operation: Transient Analysis in the Planning and Design of the Northern Kentucky Western Regional Tunnel

The Sanitation District No. 1 of Northern Kentucky (District) is planning to construct the Western Regional Conveyance Tunnel (WRCT) to provide conveyance and storage for the Western Regional Water Reclamation Facility (WRWRF) upon its completion. The hydraulic operation of the tunnel was examined for the potential for surge wave formation. Surge wave formation is typically examined as part of the design process for tunnels due to the large range of flows that tunnels convey and store. The objective was to perform transient wave analysis to investigate the tunnel design parameters, including the impacts of a downstream overflow weir as well as predicted peak inflow rates. The analysis found significant transient formation during the tunnel filling process but the magnitude of the wave formation was not a factor in the overall design decisions.