Deep Tunnel’s Deep Problems

Despite its tremendous length and cost, Chicago’s incomplete Deep Tunnel remains inadequate to prevent flooding. The answer may be in our swampy past.

Deep Tunnel

Photo: Nancy Stone/Chicago Tribune

Recently the Trib’s Michael Hawthorne had a good piece on Deep Tunnel, the massive, world-historic underground drainage ditch that’s supposed to drain all of Chicago. When completed it will rank among the world’s great engineering feats, but for now it doesn’t actually suffice to do the job it’s intended for.

Of course, that would be nothing new. As I’ve written about before at length, the city’s great engineering achievements, greater arguably than its rebuilding after the fire, have been for the purpose of dealing with runoff and sewage, lifting the city out of the swamp it was built on. And none of it’s ever quite worked, or at least kept up with the pace of development.

You see this a lot. One of the first really involved research projects I ever did was on the Florida Everglades, which are a massive swamp-like river that flows very, very slowly through South Florida. Development stopped the flow of the river, which caused all sorts of problems. So the Army Corps of Engineers built canals and huge pumping stations, along with computer modeling to figure out how much and where water would be in a natural system, to fake the flows that had been cut off.

Now people are starting to come around to the idea that, rather than (or at least in addition to) building expensive simulacra out of concrete and machines, something more like the original natural systems can play a critical role in civic infrastructure. Locally, architect Jeanne Gang is a big proponent of this.

And that’s part of what Hawthorne’s piece is about, the subhed reading “experts say massive stormwater system inadequate, fixing flooding requires green projects to cut runoff":

With climate scientists projecting that Chicago faces more intense rainstorms in the not-so-distant future, city and regional leaders increasingly say that fixing the problem requires a new way of thinking and more spending on green projects that allow runoff to soak into the ground before it reaches sewers.

Cities from Philadelphia to Seattle already are moving aggressively to prevent basement backups and sewage overflows without the expensive work of laying pipes and boring tunnels. Milwaukee is the first city in the nation with a federal stormwater permit that legally requires “green infrastructure,” such as streets and parking lots with permeable pavement and neighborhood rain gardens designed to capture the first flush of stormwater.

Milwaukee is actually going well beyond that; as Dan Weissman of WBEZ reported in 2011, the city is trying to position itself as a water-technology hub; its Global Water Center is opening this summer.

Another good part of Hawthorne’s post is about the costs—to the federal government and insurers—of flooding in Chicago: “from 2007 to 2011, the federal government and private insurers paid at least $660 million for residential flooding and sewage backup claims in Chicago and Cook County alone.” That data comes from a Center for Neighborhood Technology report, which notes that flood damage doesn’t correlate to flood plains in Cook County. As Emily Badger writes, the city is flooding itself:

Chicago – and plenty of other cities just like it – has artificially created flood-prone places simply by paving over the region’s natural ability to manage excess water. And, as Festing points out, most people are entirely unaware that the city has done this. In urban areas anywhere, when we focus instead on the risks posed by flood plains, we may be ignoring the even greater threat created by how we’ve designed cities to crowd out their essential green space.

The city has a plan for this: the Green Alley program, designed to replace impermeable surfaces with permeable pavements to take some of the burden off the sewer system. But it has only replaced one percent of the city’s alleys.

Then again, it could be worse. Chicago sits next to one of the world’s great sources of fresh water, which is part of the reasoning behind Milwaukee’s water-technology initative. It’s a problem, but it’s also a resource. And it doesn’t sit by an ocean—the sort of location that has the mayor of New York proposing a $19.5 billion program of “flood walls, levees, and bulkheads” to protect Lower Manhattan from rising tides.

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