The Albany Park Storm Water Diversion Tunnel is being constructed to avoid a repeat of flooding that occurred in 2013, when the Chicago River jumped its banks and caused residents to evacuate their homes. View Full Caption DNAinfo/Patty Wetli

ALBANY PARK — Construction of the Albany Park Storm Water Diversion Tunnel, initially slated to begin at the end of summer, won't start until 2016, officials said.

City Council passed an ordinance Wednesday authorizing intergovernmental financing of the tunnel, estimated to cost $45 million to $55 million.

According to a statement released by the mayor's office, the Chicago Department of Transportation "is handling the bidding process for the project and expects to award the contract this fall and to begin construction this winter."

CDOT spokesman Michael Claffey confirmed that "winter" translates into a 2016 start.

The tunnel was announced in 2013 after the North Branch of the Chicago River topped flood level for the third time since 2008, forcing some residents in Albany Park to be evacuated from their homes via boat.

Originally expected to be complete by 2017, the tunnel now won't be operational until 2018.

The tunnel is designed as a passive system that makes use of gravity to divert storm water from the river, bypassing Albany Park, and moving it downstream to an outlet shaft that will spit the water into the North Shore Channel.

Eighteen feet in diameter and a mile long, the tunnel will run nearly parallel to Foster Avenue 150 feet underground.

The most visible elements will be the tunnel's inlet and outlet shafts.

The inlet, where water will enter the tunnel, will be built on unimproved Park District land on the north side of Foster Avenue at approximately Springfield Avenue. The outlet shaft will be built in River Park, just east of the North Shore Channel and south of Foster Avenue.

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