
Chicago’s Deep Tunnel: The solution to urban flooding, or a cautionary tale? - lisper
https://slate.com/business/2019/01/chicagos-deep-tunnel-is-it-the-solution-to-urban-flooding-or-a-cautionary-tale.html?via=homepage_taps_top
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danjayh
The crazy thing about this article is that it presents Chicago's solution
(make the combined sewer bigger), then solutions that are being tried in other
cities (increase permeability), and then completely ignores the entirely
successful solution that's been used by Grand Rapids (and soon Lansing) on the
other side of the lake: Separate the storm and wastewater sewers. Grand Rapids
used to regularly have sewer overflows into the local river (not flooding,
though - there was enough capacity to actually get the crap and water into the
river). Over the last few decades, a separate storm sewer has been built, and
this water can be treated more quickly. The storm sewer skims off things like
oil, etc. and then returns the rainwater to the river and lake. No impact on
the shit sewer. No shit and piss in the river, no shit and piss in the lake.
It works, and it's what should be done in other cities that have this problem
(and maybe a little bit of permeability on the side).

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bigpicture
> The crazy thing about this article is that it presents Chicago's solution
> (make the combined sewer bigger)

Except that Chicago's publicly stated position is that the Deep Tunnel system
is not the solution. This is not a new thing, either. It's been that way for
more than 2 decades.

For more than 10 years, they've had a stormwater management building ordinance
and (with few exceptions) any project (new construction or renovation) that
changes the amount of stormwater exiting a piece of property is subject to it.
It limits the flow rate of stormwater leaving, the volume of stormwater
leaving, and the amount of sediment that can leave a piece of property. It is
entirely math-based, with published formulas and coefficients and makes
determining compliance straightforward, objective and fast.

They've received international recognition for their incremental approach to
stormwater management, which recognizes that the vast majority of property in
the city is private property built long ago. As for public property, whenever
the city rebuilds an alleyway, it is done with permeable pavement and is
disconnected from the sewer. Whenever the city rebuilds a road, it is
disconnected from the sewer to the extent that surrounding private property
allows. Last year an entire block of a road near me was rebuilt and the side
that was adjacent to a railroad embankment was built with swales every 50 feet
or so to manage stormwater. It was actually visually attractive as well.

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vermontdevil
Indy is undergoing a similar project - DigIndy - but it’ll be separate from
the sewer system. I think it’s halfway through now.

[https://www.citizensenergygroup.com/Our-Company/Our-
Projects...](https://www.citizensenergygroup.com/Our-Company/Our-Projects/Dig-
Indy)

~~~
toomuchtodo
Wow, I had no idea this was in progress. Thanks for sharing!

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stevep001
Minneapolis and St Paul separated their sewers. Took 55 years and $330 million
investment.

[http://www.minneapolismn.gov/publicworks/stormwater/cso/cso_...](http://www.minneapolismn.gov/publicworks/stormwater/cso/cso_history)

[https://metrocouncil.org/News-Events/Wastewater-
Water/Newsle...](https://metrocouncil.org/News-Events/Wastewater-
Water/Newsletters/Sewer-separation,-inflow-and-infiltration-reductio.aspx)

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mnw21cam
[https://outline.com/URJEBs](https://outline.com/URJEBs) \- because of
obnoxious illegal click-past "I agree" page.

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hinkley
It seems to be taken as a given that it’s too late to segregate the storm
water system from the sewers.

~~~
hermitdev
I think it basically is a given. To segregate storm water from sewer would
require a rebuild of the system. Pretty impractical at this point. It can be
done in some cases. I live in the west suburbs of Chicago, and the storm water
from my (less than 5 year old) complex drains into the Salt Creek. I don't
think my city is connected to the big dig, but we do have the capability to
dump into a local quarry. The quarry has also been used to dump snow into for
large winter storms. We've also been through a large expansion in recent years
of green areas and detention drainage areas to alleviate flooding. Living
right on the Salt Creek, I routinely see the water level fluctuate by around
10 feet or so after even a decent storm. We're probably about 5-6 feet above
normal right now after recent storms.

~~~
Retric
You don’t need to fix this in a weekend. Chicago is likely to be around in 300
years. So, solve 3% of the problem every decade and it gets fixed. Meanwhile
runoff becomes a 3% smaller problem every decade.

~~~
ryanmarsh
Grand Rapids is proof you can do it faster than 3% per decade.

~~~
jessriedel
I agree it's useful evidence, but Grand Rapids is an order of magnitude
smaller than Chicago. Geology could be very different too for all I know.
Being able to do it in one place does not necessarily make it feasible in the
other.

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chiefalchemist
Ironic. The project makes Chicago more livable, which increases development /
population which...is not sustainable.

Cities close to water used to be a necessity. Now such locations are a
liability. It's difficult to imagine politicians and local leaders coming
clean on such things.

Side note: I wonder if Amazon factored such things into its decision(s) for
picking its new HQ city(s).

~~~
ocschwar
A growing population in CHicago proper is not a problem. It's the solution.
The problem is the growing population in the Chicago suburbs, getting more and
more land paved, and thus worsening the stormwater problem.

~~~
toomuchtodo
It’s a hard sell to tell someone to pay ~$100k-$500k more for a home, and
spend $8k-15k/year more in property taxes to live in Chicago (or Cook County
in general) out of land development concerns. Chicago’s population is
decreasing for a reason, and it isn’t stormwater management.

Sprawl is not unsustainable. More costly, yes. But people will pay to not live
densely and should have the freedom to do so if urban development and building
techniques that prioritize mitigating environmental harm are practiced.

~~~
ocschwar
Chicago's population isn't sprawling out because of stomrwater problemns.

But the stormwater problems are because of Chicago sprawling out.

