Racine Wastewater Utility adopts real-time control to reduce treatment bypassing
The Racine Wastewater Utility (Utility) provides wastewater collection and treatment to 10 communities in the greater Racine area and serves approximately 140,000 residents in southeastern Wisconsin. The Utility is responsible for operating and maintaining a conventional gravity flow interceptor system with 14 lift stations and two off-line storage facilities. The system has been very susceptible to inflow and infiltration problems, with peaking factors in excess of 10 during large wet weather events.

This overloading of the collection system has resulted system wide basement backups and bypassing of the treatment plant. In response to these problems, the Utility developed a System Optimization Plan to mitigate these issues. System optimization was achieved by modeling the Utility’s interceptor system using the collection system model MIKE URBAN, and then using the calibrated model to develop a real-time control strategy to optimize system performance, minimize treatment bypassing, and eliminate basement backups.  The optimized solution consisted of a combination of storage and conveyance measures which best met the evaluation criteria:

1. The lowest unit cost for total bypass elimination ($/gallon removed);
2. The lowest unit cost for system-wide surcharge reduction (expressed as a system-wide average surcharge); and
3. The lowest total cost to meet a flow threshold at the WWTP