Utility reduces CSO volume by 80%, saving $400 million in CapEx spending using “smart sewer” technology
This short article concisely and factually sets out the challenge, solution and outcome of the City of South Bend sewerage system failure during heavy rainfalls, resulting in up to 2 billion gallons of sewerage overflowing into theSt Joseph River each year.
In 2012, the City entered into a consent decree, agreeing to a long-term control plan (LTCP) of their sewer overflow estimated at $713 million in capital improvements plus financing costs. A significant burden given theCity has a population of 100,000 with average annual income of $32,000.
Xylem’s real-time SCADA screen system of sensors and actuators enabled the waste network to react to sudden wet weather events to avoid sewer overflows by manually moving flows to under-utilized parts of the network.
Since 2012, the monitoring sites (currently 165) and 13 automated gates and valves have reduced combined sewer overflow (CSO) into the St. Joseph River by 80 percent. In 2021, the City of South Bend’s updated long-term control plan was approved with 60% less infrastructure investment than originally estimated, saving the City approximately $400 million in capital expenditure spending. South Bend has also enjoyed approximately $1.5 million in annual operating and maintenance cost savings. In addition, E.coli concentrations in the St. JosephRiver have dropped by more than 50 percent on average, improving the water quality.
Why it’s relevant to Nextspace
Whilst the Xylem solution is a SCADA system with sensors and actuators, this article is relevant to Nextspace Partners as it conveys a lot of the benefits a digital twin would bring to the challenge. It also raises the conversation about SCADA control of utilities versus a digital twin.
The main difference between SCADA and digital twin is the closed loop nature of the SCADA system.
- SCADA systems are generally offline, closed loops, with a finite physical system of sensors and controls. The data generated is made accessible to expert teams in a control room, manually operating the actuators. Digital twins tend to be open (permission-based) systems – with virtual representations of data being used to convey actionable information to both experts and non-experts.
- Whilst the SCADA monitors real time data, a digital twin of this nature would likely include broader datasets such as hyper-local rain forecasts (predictive feedback recommending pre-emptive action, rather than real-time reactive troubleshooting) and downstream environmental impact.
- A digital twin could also be made public, or partially public, providing data feeds and visual alerts regarding no-swim and no-fishing zones.
- Finally, a digital twin could also federate (connect with) similar twins in other locations, accelerating learning and broader adoption of new innovations.