South Bend Mayor Steve Luecke estimated in his 2008 State of the City address that the city would need to spend $200 million to $400 million over 20 years to meet EPA guidelines -- and that's in addition to the $120 million now being spent on South Bend's long-term sewer plan.
However, the city could save $110 million to $150 million of that mandate with the use of CSOnet, Luecke said.
Though many newer areas of South Bend have segregated sewer systems, the water and sewage is inevitably combined upon entering the city's older sewer network.
In normal circumstances, the mix is treated at a wastewater treatment plant before its release. But wet weather can put the plant at full capacity. Even dry weather can cause overflows when storm debris plugs sewer lines, thereby flooding other pipes, Gilot said. The resulting EPA fine is $27,500 for each incident. With the monitoring system in place, Gilot said the city has already detected and corrected many potential dry weather overflows.
He said public works estimates that 2 billion gallons of sewage per year empties into South Bend's waterways, which includes the St. Joseph and Wabash rivers. Cities like South Bend drain the sewage mix into natural waterways to prevent it from backing up into homes and businesses.
The EPA estimates that reducing CSO events by 85 percent nationwide would cost $50 billion using traditional technology, Montestruque said. Traditional fixes include building new separated sewer systems, expanding wastewater treatment plants and building large reservoirs, or holding tanks, to temporarily hold sewage, as was done in Chicago.
"These solutions are highly unpopular because this is taxpayer money," Montestruque said. Taxpayers can't use or see sewer improvements, so it's hard to justify spending money on them, he said.
A 2005 estimate for totally segregating South Bend's sewage and storm water was $650 million, Gilot said. Water rates would have to rise 80 percent to amass the necessary capital.
Research and Development
CSOnet originated when Lemmon and Jeffrey Talley, an associate professor of civil and environmental engineering at Notre Dame, began discussing South Bend's water management needs with city officials.
In 2004, Talley led a research and development team to create a sensor and control prototype for stopping the city's sewer overflow problem. After he landed a $1 million grant from the Indiana 21st Century Research and Technology Fund, Purdue University and environmental engineering firm Greeley and Hansen joined the project. Granger, Ind.-based EmNet was founded in 2004 to commercialize the research from Notre Dame and Purdue.
Successful test runs at St. Mary's Lake near Notre Dame paved the way for a pilot in November 2005. The pilot, a small retention basin deployment with six sensors and one controller, prevented an estimated 6 million gallons of sewage from entering the St. Joseph River that month and increased the basin's capacity by 110 percent for about 1 cent per gallon, Montestruque said.
A subsequent study conducted by environmental engineering firm Malcolm Pirnie determined that a citywide installation would reduce CSOs up to 30 percent, Montestruque said.
Although there's been an occasional node malfunction, Gilot said, the system is robust because there's no single point of failure.
"We could see this had potential early," Gilot said. "[The pilot] showed that real-time control logic and communications worked and that the system was robust under tough, real-world conditions."
Battery-operated nodes and wireless communication make for fast implementation and less up-front cost. "It's very unique in that it doesn't require any structure to be in place beforehand," Montestruque said, "It's usable the moment it is installed."
Node-to-node communication that's linked to a hierarchical information structure lets the electronically simple system consume less power. The nodes also rely on highly efficient hardware and middleware to synchronize sleep and awake cycles, extending battery life to two