Wednesday, February 14, 2007

Chicago's Deep Tunnel

How could I live in Chicago at one point and not know that there were 109 miles of tunnels being built under it? Not just small tunnels, but big ones, 9 to 33 feet in diameter. It’s all part of the Tunnel and Reservoir Plan (TARP) also known as “The Deep Tunnel”. It is pretty deep, as much as 350 feet below the surface, excavated through limestone since the 1970’s using similar equipment to the machines that drilled the Chunnel between the UK and France. But this tunnel system does not transport people. It carries and stores sewage and storm water overflow from the area to reservoir sites until water treatment plants can catch up with the peak flow during big storms.

It’s curious to me to read different descriptions of the project. The Metropolitan Water Reclamation District of Greater Chicago who runs the Deep Tunnel thinks it’s the best thing ever, and touts all the engineering awards it has won. Most of the $4 billion in funding has come from the EPA, and the project has helped improve the water quality of Lake Michigan and the Chicago River by keeping storm runoff from going directly into those bodies of water. Chicago has a mixed sewage and storm water system (like many cities) so that means sewage isn’t overflowing into the river or lake as well.

What I don’t like about the project is that it’s such an energy intensive/ engineering intensive solution. That’s such a 1950’s way of thinking to me (although I guess this did start in the 1970’s). Not only do you have to build and maintain all of the tunnels and reservoirs, but there must be some huge pumps to pull the water back up from 350 feet down and treat it. Hopefully future projects to deal with runoff in Chicago incorporate more greenroofs, bio-swales, reduced permeability of surfaces, etc. You know, Portland stuff.

Then we’ll have to think of some NEW use for the Deep Tunnel. Fresh water storage for drought? Future “L” routes? Underground linear museum? What else?


Levi said...

Bob and I have been Deep Tunnel fans for a long, long time. I agree with your criticisms, but the sheer scale of it, bordering on ridiculous, and the very name combine to make me a fan. I think there's a permanent staff that lives down there and never sees the sun.

Anonymous said...

Wow even suggesting a portland solution is a joke the idea with the deep tunnel is not just storage of waste water it is an alternative to running an all new isolated sanitary system in the city. There is no room in those streets for more or new pipes and the cost would be huge because of existing utilities. Also Portland is tiny when compared to Chicago with different soils and geology. The amount os population density is much greater and a tree hugger green system would be unreliable and wouldn't work with such huge volumes of waste per square mile. Add to that that the tunnels help divert water away from streams and rivers like the Desplains which would flood more often with out it and your dealing with forces far beyond a green answer. The deep tunnel is a green answer it keeps waste out of the rivers many of which move slow through the mostly flat saturated chicago landscape.