New permit requirements for Naperville's wastewater treatment plant could lead to cleaner water in nearby rivers and higher costs for city utility customers.
The city is seeking a permit from the Illinois Environmental Protection Agency to govern operations at the Springbrook Water Reclamation Center, which treats wastewater from Naperville and Warrenville before releasing it into the Lower DuPage River.
The five-year permit will bring stricter regulations, said Jim Holzapfel, water and wastewater utility director -- mainly a requirement to decrease the amount of the mineral phosphorus in treated water to 1 milligram per liter within about the next 10 years.
A 2008 report released by the U.S. Environmental Protection Agency mandated the 12 states that feed water into the Mississippi River to decrease phosphorus and nitrogen output because the nutrients are contributing to an oxygen-deficient "dead zone" in the Gulf of Mexico.
"There's nothing living in it other than maybe some worms," Holzapfel said about the dead zone, which is roughly the size of DuPage County.
Since one river flows into another, the amount of phosphorus in Naperville water matters to plants, animals and people trying to use waterways all the way to the Gulf.
After treatment, water from the Springbrook facility at 3712 Plainfield/Naperville Road contains about 3 milligrams or 3.5 milligrams of phosphorus per liter. Holzapfel said wastewater flowing into the facility typically contains 7 milligrams of phosphorus per liter because the mineral naturally occurs in human urine.
Developing the capacity to remove more phosphorus by adding a chemical or altering the biological environment within the plant takes money -- an estimated $40 million to $60 million.
But with provisions negotiated into a draft version of the new permit, Naperville has bought time to find the money to make the changes -- be it by increasing customer rates, taking on a loan or both.
Instead of making changes solely to the treatment plant, the city has proposed downstream work that Holzapfel says will improve water quality, natural habitats and diversity of plants and animals more quickly than decreasing phosphorus output alone.
The improvements, including removal of a low-flow dam in Shorewood and restoration of the stream bank south of 119th Street in Plainfield, would help more types of fish be able to survive further upstream and could have "immediate" positive effects.
These projects would be taken on by the Lower DuPage River Watershed Coalition, of which the city is a member. Member communities would split the price, with Naperville's portion estimated to be $3.19 million during the next eight years.
Since in-stream improvements show quicker results than treatment facility upgrades, the city's deadline to meet the new phosphorus requirement has been extended to about 10 years instead of three, city spokeswoman Kate Schultz said.
Next steps in the permit approval process include a city council discussion at 7 p.m. Tuesday at 400 S. Eagle St. and a public comment period until Nov. 21, during which people can submit thoughts to the EPA at 1021 North Grand Avenue East, P.O. Box 19276, Springfield, 62794-9276.
Then the city plans to complete a water rate study to set customer charges that will generate enough revenue to pay for phosphorus removal upgrades and other maintenance work.