Video: Deep Tunnel Construction Continues With Thornton Quarry Project

By Chuck Sudo in News on Sep 26, 2013 2:00PM

Earlier this week work began on transforming an old limestone quarry in Thornton into the largest reservoir in the world by the time it’s completed in 2015. The Thornton Reservoir Project is part of the ongoing Tunnel and Reservoir project, known colloquially as the “Deep Tunnel” project intended to reduce the backflow of sewage and stormwater of Chicago area rivers into Lake Michigan.

By the time the reservoir goes online in 2015 it’s expected to hold 7.9 billion gallons of stormwater and sanitary sewage from a dozen south suburban towns and will be the largest reservoir of its kind in the world, at least until work is completed on a reservoir in McCook in 2017 that will hold an estimated 10 billion gallons.

The Tunnel and Reservoir Plan was commissioned in the 1970s and over $3 billion has been spent so far and construction of the largest public works project in Chicago’s history will continue through 2029.