Water, Wastewater & Stormwater
394950 - You Can Dig It, But Can You Operate It? Proactive CSO Tunnel Operational Planning
Thursday, June 7
8:30 AM - 10:00 AM
Location: Greenway EF
Jessica Bastin, Indianapolis, IN – Citizens Energy Group; Emily Damian, Indianapolis, IN – Citizens Energy Group; John Trypus, Indianapolis, IN – Citizens Energy Group; Jeff Hansen, Indianapolis, IN – Citizens Energy Group
Our presentation will summarize the operational planning for the Dig Indy tunnel system, which includes 29 miles of tunnels with a finished internal diameter of 18 feet. This system is the critical part of Citizens’ combined sewer overflow (CSO) consent decree, which is required to be fully operational by the end of 2025. The tunnel system, is required to store 250 million gallons during normal storm events as well as high intensity storms that may exceed the overall tunnel capacity.
Citizens initiated proactive operational planning to ensure that there are no loose ends between multiple design contracts and construction phases. The operational planning included development of strategies for SCADA connectivity of shaft sites, instrumentation, tunnel dewatering, ventilation, odor mitigation, and geyser mitigation. The process included a combination of focused numerical and physical modeling as well as networking with utilities currently operating tunnels and economic evaluations. For Citizens, the non-modeling evaluations were equally important to establishing the operational plan as the modeling evaluations. The four focused modeling evaluations included:
1. Transient modeling of the entire tunnel system using the Transient Analysis Program (TAP) model;
2. Two-phase modeling of the downstream reaches of the tunnel system using Auburn University’s Hydraulic Analysis of Stormwater Tunnels (HAST2) model;
3. Odor dispersion modeling using EPA’s AERMOD model; and
4. Physical modeling of a drop and vent shaft at the Iowa Institute of Hydraulic Research.
Each element of the plan has helped to minimize Citizens’ long-term risk in operating the tunnel system.