Given the recent rain and flooding in the Chicago region, this seemed apropos: one journalist describes a recent tour of the Thornton Quarry and Deep Tunnel complex south of the city.

On Saturday, I joined the Southeast Environmental Task Force (SETF) on one of its tours of Chicago’s goliath infrastructure. The tour featured the future site of the Thornton Composite Reservoir, the largest such reservoir in the world, and a Deep Tunnel pumping station 350′ below ground at the Calumet Water Reclamation Plant. Both are part of the Metropolitan Water Reclamation District (MWRD)’s gargantuan Tunnel and Reservoir Plan, the multi-decade, multi-billion dollar project designed to protect the Chicago region from the flooding and pollution caused by overflowing sewer and stormwater infrastructure…

After this brief greeting, we drove to the former Thornton Quarry in the south suburban city of Thornton. The quarry, which is one of the largest aggregate quarries in the world, is still being actively mined nearby; however, the MWRD has acquired two significant portions of the area for the Deep Tunnel project. The resulting reservoir will hold 7.9 billion gallons of water, which MWRD Principal Civil Engineer Lou Storino estimated is the equivalent of 36 Soldier Fields. While on site, staff mentioned that we would be one of the last tours to descend to the base of the quarry, which will enter into operation shortly.

Tourists may find man-made sights like Hoover Dam impressive but Chicago area residents don’t have to go far to see similarly impressive projects. Not that the public could simply walk into the Deep Tunnel complex but you can glance at the quarry from the I-80/94 corridor. The Deep Tunnel project was quite costly and time-consuming but represents an effort to more effectively drain water away from Chicago, an on-going concern that even one of the largest civil engineering projects can’t solve on its own. This is what you get when you build a 9+ million metropolitan region centered on a swampy area near Lake Michigan…