Jeff Loster, village engineer, estimated it would cost between $9,000 and $12,000 to have Christopher B. Burke Engineering Ltd. of Rosemont update a study the firm conducted in 2016 and explore other possible solutions. Palm said he expects to bring the matter back to the village board in 30 to 60 days.
Five alternatives offered by Burke Engineering in 2016 ranged in price from $1 million to $3.8 million. The firm will be asked to concentrate on two of those alternatives. One alternative would be installation of a 36-inch storm sewer from Keystone to Park Avenue. The other would be installation of a 36-inch storm sewer from Keystone to Thatcher Avenue. Palm said he expected the village would need to seek grant funding or sell bonds to finance the project.
Although flooding of Keystone and backyards of approximately 25 residences on the block has been ongoing for years, the flooding was seen for an extended period of time following the historic rainfalls of near eight inches of rain in four days in mid-May. Keystone was reportedly still flooded the morning following the final deluge.
Loster said the village did not receive any reports of sewer backup but several residents reported seepage in their basements.
Trustee Bob O’Connell, who lives nearby, estimated that the flooding has occurred four times in the past seven or eight years but the May flooding was “the worst.”
In response to a question from Trustee Katie Brennan, Loster said similar street flooding has not been reported in any other locations in the village.
John Anderson, director of public works, said in a memo to Palm that “flooding challenges” in that area include the topographical layout of the area which contributes to poor overland drainage. At the June 8 meeting, Palm said simply, “That area is a bowl.”
Anderson said another challenge is the configuration of the existing sewer system. North of Thomas Street, the sewer system is separated so storm water and sanitary feed into different pipes. South of Thomas, the sewer system is combined so storm water and sanitary feed into the same pipe.
Another contributing factor is the installation of restrictors on the combined sewer pipe, which is designed to limit the amount of water that enters the system so that it does not back into basements of residents on that system.
Although a major project will be needed to eliminate the flooding., Palm reported two lesser steps that are expected to ease the flooding. Since the May flooding, the Public Works Department has removed several root infiltrations from the sewer line during a cleaning and televising procedure that is conducted every five years. Later this summer, the Keystone sewer will be relined as part of an ongoing village program, having been added recently to the list of sewers to be relined.