The city just reached a legal settlement with the feds and the state on Deep Tunnel, now nearly four decades and three billion dollars in creation, that forces the Water District to meet time guidelines on the project’s completion, scheduled for 2029. There’s still a lot to be done, such as completing the Thornton Composite Reservoir (PDF):
When completed, the Thornton Composite Reservoir, for the Calumet TARP System, will measure approximately 2,500 by 1,600 feet with a maximum water depth of 292 feet. The amount of limestone expected to be mined for the Thornton Composite Reservoir is approximately 76 million tons. Mining began in 1997 and is approximately 92 percent complete, with the remaining 7 million tons scheduled to be removed by the end of 2013.
The road to the settlement began in March, when the federal government began looking into the uncompleted system’s ineffectiveness in the wake of massive 2008 and 2010 rainstorms, which led to larger sewage discharges than the system faced before the tunnel system was operational:
Between 2007 and 2010, records show, the agency in charge of Deep Tunnel dumped nearly 19 billion gallons of storm water teeming with disease-causing and fish-killing waste into the Great Lake, the source of drinking water for 7 million people in Chicago and its suburbs. By contrast, 12 billion gallons poured out between 1985 and 2006.
Most of the recent overflows into the lake came during two monsoon-like storms in 2008 and 2010 that were among the most intense downpours in Chicago history. Yet even a rainfall as small as two-thirds of an inch can force sewage-tainted runoff into the Chicago River and other waterways.
This isn’t to say that Deep Tunnel has been ineffective. Quite the opposite. One advantage of the reversal of the Chicago River and its use as a giant sewer was that it created a barrier of poison (PDF):
Initially, Chicago’s wastes were so anoxic or toxic that “clean water” organisms could not survive in the toxic zone they created in the canals and their connecting channels. This toxic zone effectively served as a barrier, preventing the exchange of organisms between the two [Great Lakes and Mississippi River] ecosystems.
Ramifications of the Clean Water Act and the construction of Deep Tunnel have made the river somewhat able to support aquatic life again… like the Asian carp. The CWA was established in 1972; the next year, an Arkansas fish farmer introduced the infamous carp to America, and it’s been a unidirectional race between clean water and the carp ever since.
Deep Tunnel is also in its own race against nature: stormwater capacity versus climate-change-driven stormwater. The great University of Illinois climatologist Stanley Changnon, who’s in his fourth decade with the Illinois State Water Survey, suggests that Deep Tunnel has been outpaced by the climate it was designed to handle in a 2010 paper (PDF):
An issue relevant to the 2008 storm relates to climate shifts that lead to more rainstorms over time. Studies of historic floods and flood-producing rain events in the Midwest revealed a temporal increase since 1930 (Kunkel et al. 1993). Assessment of heavy rainstorms in the Midwest since 1930 found increasing frequencies. The three 2008 storms, plus the eight in 2001 and one in 2007 at Chicago, reflect this climate-related increase in storm frequency, an important issue for water management planning and operations. Studies of global warming and its effects on climate concluded that heavier rainfalls would continue to increase in the 21st century (National Assessment Synthesis Team 2000).
Changnon concludes that Deep Tunnel can’t handle rainstorms of 50-year or greater frequencies. But if climate change causes more frequent and heavier storms, what was once a 50-year storm could become a more frequent occurence.
Back in 2006, after the bulk of the tunnel drilling had been completed, North Town News Magazine took a half-hour tour of Deep Tunnel. The video quality is a bit lacking, but it’s still an amazing look inside Deep Tunnel:
In 2002, the Reader’s Mike Lenehan took us underground with John Cooper, a Deep Tunnel employee:
This particular tunnel, we’re 340 feet down. When I first went down there I thought I was in outer space, because of the lights rotating on the mining machines and stuff like that. You have to have fans to pump the air in, and meters for your oxygen. You have some occasions when you have to come out of the hole. Like electrical fires–you can’t stay down there because the smoke is too intense. You don’t have any room for error down there, because you can get killed in an instant. You got the big machines, the big tools, and the heights you have to work at–you’re swinging off rebar and off these machines and sometimes you have to lean out. You have your harnesses on, but you still have accidents. Matter of fact there was a guy got killed in December. Three days before Christmas. They were in this drift, which is an off-ramp to the tunnel itself. And they were pouring concrete in this form. They have this thing they call shooting the rabbit, which is kicking out the excess concrete to clear the slick line. And for some reason this guy walked in front of this thing just before they shot, and it just kicked the back of his skull off. You have to keep your mind on what you’re doing at all times. The pay sounds good, but it’s very dangerous.
What you call a push is seven feet. Which takes about 45 minutes. In one shift we can get about a hundred feet. You got about 20, 25 guys on a shift, and you’re running 24-hour shifts.Edit Module