When I was a kid one of my favorite museum tours in Paris was the Musée des égouts de Paris – the sewer museum. Paris’ sewers go back a long way; they were semi-open rivers of effluent, like the Thames in London or the Cloaca Maxima in Rome; often these were rivers that were thoroughly ruined then built over and forgotten as long as the nasty stuff flowed the right direction.

[I seem to be interested in mountains of poo: stderr and “4 stories of shit” stderr let’s just say it’s a metaphor, shall we?]

My posting about The Great Poop of London must have perturbed the artificial intelligences that feed me news because I’ve gotten a rush of references to poop. At least that’s better than when I start fact-checking the torture program, or researching nuclear weapons.

Anyway, here’s a fascinating article that came up in Slate, about the Chicago river, and the sewers under that great city. [slate]

The sewer engineer’s riddle: What do you get when you mix a gallon of sewage and a gallon of rainwater? Two gallons of sewage.

Naturally, sewer engineers have their own culture, and their own jokes. It must be a fascinating fraternity, who know where everything is and who go down into the secret city below the city. And, every city’s different. For example, did you know that San Francisco has parts of the city that are built over the skeletons of ships that gold rushers arrived in? They sank into the mud and became infrastructure.

One of the most fascinating things I learned about sewers, when I was a kid, was “pigging” the lines. Basically, you have a round sewer, and sometimes it might need to be cleaned out. Let’s say the sewer goes under the Seine River – it’s way too dangerous for a person to go down there under any circumstances (would you trust “OK, we have it shut off, you run down there and shovel out the shit and if you hear us yell “run!” you hightail it out of there!”) so you force a gigantic fairly well-fitting cork ball in one side and let the suction pull it through, pushing a mountain of stuff into a gigantic stuff volcano on the other side, like some sort of champagne cork from hell. The museum even mentions the notable time that the cork got stuck and they let the water build up so they could put some dynamite on a long pole and blow it clear. Poop plus dynamite plus water as a tamper! I am sure that the ancient Roman sewer engineers would have immediately understood the whole thing, and been green with envy.

That’s because Chicago built a second river, an infernal reflection of the first, tracing its course hundreds of feet below ground. On rainy days, this subterranean passage, a conduit that can hold more than 1 billion gallons of wastewater, welcomes a roaring torrent of shit, piss, and oily runoff from the downtown streets. This megasewer, a filthy hidden portrait to the Chicago River;s Dorian Gray, is dynamic enough to create its own wave action if not properly supervised. That’s what happened on Oct. 3, 1986, when a geyser blasted through a downtown street, lifting a 61-year-old woman’s Pontiac Bonneville into the air like a toy, nearly drowning the driver in dirty water

It may be full of poop and whatnot, but water’s still very heavy and obeys physical law. What goes up, comes down, etc. Most importantly, about water is that it’s not compressible. If a million gallons of water falls on a city the size of Chicago, all that water’s got to have someplace to go. Hint: it’s great for diluting the mess in the sewers.

The whole article is framed around the question of “what happens if there is too much rain?” Well, that is a problem. I loved the illustrations that show, basically, that no matter how you slice it the water’s got to have somewhere to go because once it finds its level, that level had better not be your basement.

When Lori Burns was growing up on the South Side of Chicago in the 1980s, she always kept an eye on the dip Stony Island Avenue took under the freight tracks on 95^th Street. “We knew that if it was flooded, we’d have water.” Her parents’ basement, once a cozy retreat with a radiant-heating floor, was transformed into a semiannual biohazard zone. The house flooded while Burns’ mother was in treatment for breast cancer, in 2004 and 2007. It flooded again in 2008, 2011, and 2013, ruining the washing machine, boiler, and hot-water heater. After she inherited the house, Burns spent more than $10,000 on flood-proofing. “For most African Americans, that house is the biggest asset you have,” says Burns, who is black. “And if it’s being ruined from the bottom up, that’s not OK.”

[Included that as a reminder that ‘infrastructure’ spending in the US is also horribly racist]

Overall, my take-away lesson is that when you build big sewers, they handle normal problems just fine but there’s always a failure-point which results in catastrophic blowback. The trick is to build that failure-point with vision and foresight.

The article also has some deep thinking about the fundamentals of engineering:

“It’s a marvel,” Hobbs adds. “But we have this tendency in this country to think we can build our way out of stuff. And we can’t always build our way out.”

There are amazing sewers under Tokyo, which must have inspired the Moria scene.

I want to observe a Senkai Juku performance there. Gods, please make this happen.

A guy I used to hang out with was an “urban explorer” whose hobby was going into places where you’re not supposed to go. His greatest accomplishment was getting into some of the spillways around Niagra Falls. He had some amazing pictures. Not my idea of fun, fast-roping around in the dark, with your ear cocked for the sound of a great big toilet flushing.