Hydraulic Transient Study of Narragansett Bay Commission Tunnel System

The purpose of this study is to evaluate the hydraulic transient status in the proposed Narragansett Bay Commission (NBC) Tunnel System in north central Rhode Island. The tunnel system is designed as an off-line storage facility. As shown in Fig. 1, the tunnel system consists of Main Spine Tunnel and Seekonk Tunnel, as well as 18 dropshafts. For a larger storm, the inflow must be controlled to prevent overfilling. At a circumstance of inflow control gate failure at some dropshafts, the flows exceeding the storage capacity of the tunnel may overflow into the Mosshasuck River through an "extreme event overflow". This structure is proposed to be located in the vicinity of OF 009/010.