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11.10.2010
Hustle & Flow
Reversing the flow of Chicago's waterways once addressed 19th-century urban problems. Restoring the natural direction will require 21st-century thinking to cope with contemporary challenges and augment the city's water infrastructure.
Contained in a concrete channel, the Chicago River poses serious environmental and engineering challenges for the city.
Courtesy MWRD

The fear and furor that has surrounded the intrepid advance of hordes of Asian carp up the Mississippi River Basin has found its focal point in the Chicago waterways. The final battle to keep this dominating aquatic invader out of the Great Lakes—where, if infiltration occurs, they are expected to decimate the fisheries—will happen here. While many strategies are being bandied about the table at the moment, the most provocative by far, and most ambitious in terms of scale of work and repercussions to business and the environment, is a plan to re-separate the Mississippi and Great Lakes basins by re-reversing the flows of the Chicago and Calumet rivers.

While it’s too soon to tell if this would be a feasible approach, the idea has been gaining support. Even now, outgoing Mayor Richard M. Daley has thrown himself behind it. “That’s a great project,” he recently told The Chicago Tribune. “That could be the salvation, maybe, of the Great Lakes.” Studies are currently underway to determine exactly how best to implement this plan—one by the Army Corps of Engineers, another by The Great Lakes and St. Lawrence Cities Initiative (GLSLCI) and The Great Lakes Commission (GLC)—and experts on the matter seem to have a pretty good handle on the necessary basic steps.


One of the control locks that helps move sewage downstream.

The Chicago and Calumet rivers were originally reversed from flowing into Lake Michigan to flowing into the Des Planes River and from there, eventually, into the Mississippi in the late 19th and early 20th centuries. Before that time, Chicago’s sewage went straight into the rivers and the lake, the city’s source of drinking water. Fear of a cholera epidemic spurred the massive civil engineering project, which included construction of control locks at the mouths of the rivers and at Lockport, and the digging of two major canals, the Chicago Sanitary and Ship Canal and the Cal-Sag Channel. Completed in 1922, the project had the desired effect of moving sewage downstream instead of into the drinking water supply, and also opened up a commercial shipping corridor that remains an enormous economic driver for the region to this day.

The reversal also had some less laudatory effects. Relieved from the danger of poisoning itself on its own effluent, and relying on nature to do the job, Chicago never bothered to disinfect its sewage before releasing it on the world, making it the only metropolis in the United States with that dubious distinction. Today, the city’s sewage receives only the most minimal treatment before being discharged. Rife as they are with fecal coliform colonies, the city’s waterways are peppered with signs warning “Not Fit For Any Human Body Contact.” Chicago is also the only city on the Great Lakes that uses lake water, but does not return it to the source. Instead, it consumes roughly two billion gallons per day and then flushes it into the Gulf of Mexico, contributing massively to the Mississippi Delta’s infamous dead region and at the same time depleting the Great Lakes, which happen to be the world’s largest reserve of fresh water.


A diagram of the Deep Tunnel and watershed systems (click to zoom).
 
River recreation takes place in polluted waterways.
 
 

So the rational for re-reversing Chicago’s waterways appears to be larger than the cause of ecological separation. “We have a moral obligation to deal with pollution issues locally, rather than sending them downstream,” said Margaret Frisbie, executive director of Friends of the Chicago River and a member of the advisory committee for GLSLCI and GLC’s re-reversal study. “And if we’re diminishing the Great Lakes, what the hell are we doing? We have the technology to change that.” The GLSLCI is calling its plan—which is still in its formative stages (an RFP has lured proposals from six engineering firms, and the organization hopes to have three possible implementation schemes ready by 2012)—a 21st-century system, but there is nothing 21st-century about the technology needed to pull it off. The crux of the issue is two-fold: The first requires keeping the commercial shipping corridor open, whether through barge-moving systems, overland transfers, or other methods. The second requires keeping storm water out of the sewers. At the time being, as little as 1/4 inch of rain will cause sewage to overflow untreated into the waterways.

As far as the latter is concerned, much work is already underway. Since the 1970s, the Metropolitan Water Reclamation District of Greater Chicago (MWRD) has been constructing its $4 billion Tunnel and Reservoir Plan (TARP, not to be confused with the federal financial industry bailout), better known as “The Deep Tunnel.” When completed—in 2015 if everything goes according to schedule—the Deep Tunnel will include 109 miles of tunnels 9 to 33 feet in diameter that will collect combined sanitary and storm sewer flows and convey them to surface reservoirs for storage until the area’s water reclamation plants can treat and safely discharge the effluent. TARP does have its critics, however. “All of the city’s drainage pipes would have to be upgraded and sized bigger for the system to work and not have bottlenecks,” explained Martin Felsen of UrbanLab, a Chicago research-based architecture and design practice that has worked on proposals for the region’s water issues. “Most people’s homes only have 4-inch pipes. Having a deep tunnel a mile away is not going to relieve the pressure.”

Another answer to storm water management is replacing the city’s vast tracts of impermeable surfaces with surfaces that either retain water or allow it to infiltrate directly into the ground. One way of accomplishing this is through green roofs, and Chicago has been aggressive in promoting this solution. While City Hall’s green roof may be the most high-profile of these projects, Chicago now has approximately 500 green roofs that are either finished or under way, covering 7 million square feet—roughly double the amount of floor space in the Willis Tower. An even more significant measure would be to institute a porous paving system for the city’s streets and parking lots. Chicago has already taken a step in this direction with its Permeable Alleys initiative, a pilot project that installed rigid grid pavers over gravel in the alleyways of a Northside neighborhood. Eventually more than 2,000 miles of alleys could be resurfaced with permeable materials. The MWRD is also in the midst of developing the Cook County Watershed Management Ordinance, a new county-wide storm water plan (currently each municipality is responsible for its own). In its present draft, now up for review, the ordinance recommends mandating permeable paving surfaces for all new development.


The Deep Tunnel will carry sewage to container reservoirs.

Keeping the commercial shipping corridor functioning in the midst of ecological separation and re-reversal is at once a more daunting undertaking and a locus of potential progress. The ship canals—where the new infrastructure would most likely need to be installed—flow through rust-belt Chicago, areas of economic depression and abandoned industry, communities that are hungry for something new. Building new transfer sites, where goods and people would be forced to pause before moving on, could create a de facto financial stimulus. “It would be the equivalent of putting in a station on a railroad, or a CTA stop,” said Felsen. “All of a sudden, you get a lot more development.”

All in all, re-reversing Chicago’s waterways seems possible, especially considering they were reversed in the first place a century ago. And while it may be too late to turn back the Asian carp invasion (the species’ DNA has already been found in the Chicago river, and one of the fish was reportedly caught in Lake Calumet) there appear to be plenty of other urgent reasons to see the project through. The GLSLCI and GLC’s study will be out in 2012, but it would be rash to expect to see any real movement on the plan anytime soon. “We are two nonprofit organizations,” said Dave Ulrich, executive director of the GLSLCI. “What we say does not have the force of law. If we come up with good ideas, they would have to be folded into the legislative process and Corps of Engineers process.” Still, momentum is building. The Environmental Protection Agency recently stated it would like the Chicago River to be clean enough for swimming in coming decades.

Aaron Seward

Aaron Seward writes about architecture, engineering, and construction and is a frequent contributor to AN.