The north lobe of the Thornton Quarry, looking up from the floor to Interstate 80, which crosses 300 feet above the north and the south sections of the quarry. The Metropolitan Water Reclamation District will use the north section for a flood-control reservoir. | Mike Nolan~Sun-Times Media
Updated: August 7, 2014 6:18AM
The Southeast Environmental Task Force will hold a Brown Bag Eco-Tour, the “Deep Tunnel Tour and Thornton Quarry,” on July 12, according to a press release from the task force.
“It’s a rare opportunity and a thrill to descend down into one of the largest quarries in the world,” task force president Tom Shepherd said in the release.
The tour bus will depart at 10 a.m. from the Chicago Cultural Center at Randolph Street and Michigan Avenue in Chicago’s Loop and is to return by 2 p.m.
The first stop will be the Thornton Quarry, one of the tunnel’s temporary holding reservoirs for stormwater.
“The Deep Tunnel is quite an engineering feat,” task force executive director Peggy Salazar said in the release. “Back at the pumping station, we take an elevator down and that’s when you realize just how deep the Deep Tunnel is. This may be the last time we can go into the intended reservoir before it is filled with water.”
Sometimes called the “Grand Canyon of the Midwest,” according to the release, the quarry also is the site of a 450 million-year-old coral reef, and tour participants are provided samplings of crinoid, brachiopod and trilobite fossil treasures.
From there, the tour will go to the Metropolitan Water Reclamation District’s site, where officials will take the group deep below ground level to see what goes on at the pumping station.
The Deep Tunnel Project, aka Tunnel and Reservoir Plan, is a large civil engineering project that aims to reduce flooding in the metropolitan Chicago area and to reduce the harmful effects of flushing raw sewage into Lake Michigan by diverting stormwater and sewage into several reservoirs around the city. It has been under construction for more than 30 years and will not be complete until 2029.
The guides at both venues are experts who know the business of quarrying as well as the history of the quarry, which dates to the 1830s, and how stormwater is treated in Chicago, according to the press release.
Tickets are $25 and space is limited.
Other upcoming tours are “Down in the Dumps” (Aug. 9) and the “Industrial Evolution Tour” (Oct. 4).
For more information or to register, call (773) 646-0436 or visit setaskforce.blogspot.com.