VALPARAISO | The seemingly incessant rain last week provided the first test of Valparaiso's combined sewer overflow disinfection facility.
The facility passed.
Utility Director Steve Poulos told the city's Utilities Board a total of 3.2 inches of rain fell from April 15 to 18. Valparaiso's many stormwater projects, including several sewer separations, enabled the city to manage the flows until the last day when about 3.1 million gallons of water was discharged into Salt Creek.
It was the first such incident since December 2011. The city completed construction of its CSO disinfection facility April 2012, and has waited for a storm with sufficient rain to test its ability to disinfect a flow of up to 100 million gallons a day.
The $2.5 million facility screens out some of the materials and allows for some settling before the water is disinfected with bleach and the bleach is removed with sodium bisulphate.
The U.S. Environmental Protection Agency allows up to 235 colonies of E. coli bacteria per 100 milliliters of water, but tests showed the city's overflow had fewer than one colony per 100 milliliters.
While it was good to know the disinfection facility passed the test, Poulos also noted how the projects to separate the storm and sanitary sewers in several areas, especially Valparaiso Street and Evans Avenue, have reduced the amount of stormwater going through the treatment plant.
About a decade ago, the city averaged 12 to 15 combined sewer overflows annually. The low rainfall in 2012 helped eliminate them for over a year, but Poulos said completion of the Chautauqua Park separation project underway now and continuing through next year, will leave only the downtown area with combined sewers and should eliminate almost all overflow events.
"I would never say we would eliminate them entirely, but we're a lot better off today than we were," he said.