The $70 million Albany Park Stormwater Diversion Tunnel is an 18-foot-diameter bypass tube designed to end flooding where the river straddles Foster Avenue.
"One of the really cool innovations about this project is it's putting the water into the same place it'd be going," said WSP Project Consultant and Engineer Frank Jaramilla.
Flooding in the area has increased in severity and frequency because of increased development further north along the river.
From now on, when the water level in the river rises, the flood waters will spill into an inlet and land in the tunnel. Gravity will then push the water 5,800 feet along the tunnel, which runs directly below Foster Avenue.
The tunnel empties into the North Shore channel.
"There happens to be an elevation change from the inlet to the outlet, and the water, just by gravity, flows down there," said Chicago Department of Transportation Civil Engineer Vasile Jurco. "So this will solve the problem."
A 250 ton boring machine had to be lowered in pieces and reassembled to drill the tunnel.
A concrete lining has been completed, and the tunnel will soon be ready to carry over a million gallons of floodwater. The tunnel is due to be operational by April.