JOLIET – Joliet is the middle of an $82.5-million program aimed at reducing sewage overflow into the Des Plaines River and, hopefully, reducing sewer backups in homes in older parts of the city.
City officials on Tuesday gave an update on the Combined Sewer Overflow program designed to meet Environmental Protection Agency mandates for reducing overflow sewage primarily into the Des Plaines River.
"CSO is not optional," Allison Swisher, civil engineer for Joliet, said. "If we do not continue with this work, we would be subject to a consent decree."
That, she said, would likely increase costs far beyond what Joliet is spending now on a program designed by the city with EPA approval.
The city last year completed one of the bigger projects in the CSO program, which was boring a tunnel beneath the Des Plaines River to get overflow to the East Side Waste Water Treatment Plant.
The tunnel cost $24 million.
Joliet in recent weeks has started an even bigger project, construction of a $38 million Wet Weather Treatment Facility designed to treat overflow water created during heavy rains so it is clean before going into the river.
The program started in 2013 and could run as long as 2025 before completed.
"Joliet is not unique in that we have combined sewers," Swisher said, citing EPA numbers that 772 communities have combined sewers. "Most older towns that were constructing sewers at the turn of the century have combined sewers."
The city's combined sewers are in the older East Side. Combined sewers were standard in the early 1900s. Storm water and sanitary systems are separated in newer sections of the city.
Combined sewers basically take sanitary sewage and storm water into the same sewer line. But in times of heavy rain the system cannot handle all the water, and the overflow goes into the river.
Swisher said the city in the 1980s began reducing the number of combined sewers in Joliet, which is down from 26 to 8.
"We have a long-term control plan initiated to control overflows," Swisher said. "Once that'e completed, we're allowed to have no more than than four overflows on average per year."
Utilities Director James Eggen said that at the peak in the 1970s the city had up to 40 overflows a year.
The goal, Eggen said, is not only to reduce overflow into the Des Plaines River but also backups in the streets and people's basements – all of which must be reported to the EPA.
"EPA considers whether it's spilling into the road, backing up into the basement, or going into the river to be an overflow," Eggen said.