The Flossmoor village board has taken a step toward addressing a major flooding issue downtown by approving a study that will look at possible improvements to the Flossmoor Road viaduct.
Board members gave a green light to the study at the remotely-held meeting on June 15. The study, which will be completed by Baxter & Woodman Consulting Engineers, aims to figure out solutions for mitigating the flooding in the viaduct and upstream tributary areas by studying the whole drainage basin.
At previous board meetings, Flossmoor residents have voiced concerns about flooding in areas surrounding the viaduct. According to a memo from Public Works Director John Brunke, flooding in these areas “has been going on for decades, and has only become worse with the increase in rainfall that our region has been experiencing.”
Last Sept. 27, more than six inches of rain fell in about 24 hours in the village, flooding the downtown area, Dartmouth Road near Butterfield Creek and parts of the Heather Hill neighborhood.
Though a 2005 study resulted in a recommendation for a relief storm sewer and the consideration of adding detention storage near the viaduct, it did not address flooding issues that are upsteam in areas that include the north end of Heather Hill and the south half of the Old Flossmoor neighborhood, Brunke said in the memo.
The study is expected to cost an estimated $40,000. It will include project management, data collection and review and a preliminary design of drainage improvements. To cover the cost of the study, the village is looking to use REBUILD Illinois Bond Funds, bonds from the state managed through the Illinois Department of Transportation.
The study is projected to be finished by Aug. 30. Construction on the viaduct could be implemented as early as 2021 with the use of grant funding.
“I’m really excited that we have a concrete step with a concrete timeline for this particular aspect of the project,” Trustee Diane Williams said during the meeting. “Then, we can have an initiative where we know what we have to do, exactly what it’s going to cost and what time frame we can do that, so I’m excited about where we are.”
Following last September’s storm, Brunke said it appears that rain events have become more intense in recent years and there is evidence that more rain is falling. In the past, one defining factor of a 100-year storm was that seven inches of rain had fallen. Now that number is set at eight inches, he said.
Part of the flooding problem in downtown Flossmoor is due to an undersized storm sewer under the Metra viaduct, Brunke said last year. That pipe, which is likely part of the viaduct’s original infrastructure, is about two feet in diameter. Plans have been discussed to replace that storm sewer with a four-foot pipe that would extend east on Flossmoor Road all the way to Butterfield Creek.
Such a project would probably cost about $3 million, and the money is currently not available. Flossmoor has applied for grants that might possibly finance the improvement, he said.