$1B flood-control Illinois reservoir gets swamped by storm

CHICAGO (AP) - Records show that despite a new $1 billion flood-control reservoir in Illinois, rain and melting snow swamped the largest section of the project in less than a day last month.

Records obtained by the Chicago Tribune reveal that on Feb. 20 more than 2 inches of rain flushed a torrent of mixed sewage into the Deep Tunnel system stretching from the Chicago suburb of Wilmette to Westchester, about 25 miles (40 kilometers) to the southwest.

The system filled the McCook Reservoir to capacity, which was built to hold 3.5 billion gallons of wastewater until it can be treated.

Metropolitan Water Reclamation District officials were alarmed by the rate of sewage and runoff that rushed into the Deep Tunnel. But they said the system worked as planned.

Frank Pajak, director of the Central Stickney Sanitary District in the southwest suburb, said his constituents were frequently assured that the project would solve their chronic flooding problems.

"I've been hearing about Deep Tunnel forever," said Pajak. "I was at the ribbon-cutting (for the reservoir), and it looked great. So why am I still getting calls about people standing in ankle-deep sewage in their basement?"

But David St. Pierre, the district's executive director, said that without the reservoir the district likely would have been forced to release sewage and runoff into Lake Michigan, a last resort outlet when streets and basements are flooded.

"Before McCook came online, we would start seeing (sewage overflows) almost as soon as it started raining," St. Pierre said. "This time the system held on for 20 hours, which makes me fairly optimistic that what we saw last month will be relatively rare."

A nearby quarry is expected to be mined by 2029, which would expand the reservoir's capacity to 10 billion gallons.

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Information from: Chicago Tribune, http://www.chicagotribune.com