Chicago’s giant tunnels

In another post I have mentioned Chicago’s TARP system.  Like many other cities – including Vancouver – Chicago is drained by so-called combined sewers, that serve the dual purpose of conveying sanitary sewage and storm water.  When all goes well the combined flow gets treated at the wastewater plant.  But heavy storms can overcome the sewers, which then overflow into neighbouring creeks and bays.

To solve this, Vancouver has decided to separate its sewers.  This reduces the overflows, but leaves the storm waters untreated.  That’s a shame, because the so-called first flush pushes cigarette butts, waste oil, goose poo, plastic bags, and what-have-you into fish habitat.

Chicago, in contrast, decided to create a system of deep, wide tunnels to receive the excess waters, which are later pumped back to the treatment plants.  These are enormous; some of the tunnels are over 10 metres in diameter, and the system, called TARP, can store 8.7 million cubic metres.

TARP, which is what the system is called, has so far saved $180 million worth of flood damage, and the number of CSOs have been reduced by half.  Great, but not enough.  The city has not only launched an aggressive program of green roofs (to limit runoff) but has also decided to connect the deep tunnels with three large reservoirs.  These reservoirs, refitted quarries, increase the storage capacity of the system ten-fold.  Two of the reservoirs are now on-line; there has been no CSO since.

Remarkable.  But I snickered when I read a sentence from their documentation, one I wish Vancouver would be aware of.  It reads:

The most obvious solution, replacing combined sewers with storm and sanitary pipes, was determined to be too costly, disruptive to communities, and unable to provide flood relief.

Ah well.  Anyways, take a look:


No fatbergs in Chicago

I had the pleasure of visiting the Stickney waste water treatment plant in Chicago, supposedly the largest in the world.  I’ll write more about the visit later (There’s so much that’s col there!).  For now, I want to focus on a little fact that surprised me.

I asked our guides, Tracey and Matthew, whether there are ever blockages in the system caused by congealed fat.  They looked a bit puzzled; Tracey answered that it never seems to come up.  That intrigued me; I thought “fatbergs” were a common feature of all sewage systems.

Here’s a possible answer in a piece by Julie Unruh of WGN9 in Chicago:

“With reference to this plant and my colleagues we really have not seen any issues,” said Reed Dring, operations manager at the Stickney Water Reclamation Plant.

While he doesn’t know why Chicago seems to be doing things right, Dring says there are a lot of variables to consider: Temperature of the sewers, velocity of the waste water, size of the tunnels and yes, what people are likely to do at the loo.

Dring goes on to say it is likely the good habits of cook county citizens coupled with the ginormous size of our tunnels that help keep our waste moving.

The ginormous size of our tunnels.  Maybe not the most technical of descriptions, but it is apt.  The TARP system in Chicago uses indeed very large tunnels (up to 10 metres in diameter) to convey and store combined sanitary and sewage and storm drainage.  These tunnels can store up to 2.3 billion gallons (8.7 million cubic metres) of excess sewage and have been remarkably effective at preventing combined sewage overflows.

Meanwhile, Vancouver has embarked on a long and costly program of separating its sewers.  This, in my opinion, is foolish: storm water is often polluted, and building storage to prevent CSO would likely be cheaper and smarter.  Now here’s one more concern: are we likely to see more sewer blockages in the future?

Bacterial flora, childhood obesity, and cleaners

In case you missed it, a study published last week has made the rounds of the internet, once again highlighting the importance of the gut microflora.  Dr. Brian Goldman reports for CBC

Overeating and not enough exercise are two risk factors behind the increase [in obesity]. But a study published earlier today in the Canadian Medical Association Journal zeroes in on a strange new culprit that lurks inside your house. And no, it’s not the fridge.

The risk factor is exposure to everyday household cleansers. Researchers from across Canada looked at data from the Canadian Healthy Infant Longitudinal Development (CHILD) study. It’s a long-term study of 3,500 children that aims to predict, prevent and treat chronic diseases. The researchers compared infants three to four months of age who lived in households where consumer disinfectants were used once a week to infants who lived in houses where disinfectants were used far less often. Then, they took another look at these kids at the age of three.

What they found is that kids who lived in households where disinfectants were used once a week had a higher body mass index (BMI). In other words, they were more likely to be overweight or obese.

Infants age three to four months who lived in houses where multi-surface cleaners were used had lower levels of Haemophilus and Clostridium bacteria, and higher levels of a germ called Lachnospiraceae. The more often the household used cleansers, the higher the level of Lachnospiraceae.

We now know that gut flora and obesity are connected.  This new finding is not a smoking gun, not quite, but it’s getting closer.

The Taoyuan wastewater treatment plant

Shouldn’t a wastewater treatment plant double up as an education facility and a public amenity?  That seems to be thinking of the creators of the new plant in Taoyuan in Taiwan.  Reports Kimberley Mok in Treehugger:

Too often, infrastructure is built in a rather unsexy, utilitarian way. But we know that they can be designed as symbols of civic pride, as they are in a lot of places around the world.

In Taiwan, Habitech Architects lent a poetic bent to this sewage treatment plant in Taoyuan, in the northwestern part of the country. Doubling as an environmental education centre, the project is enveloped in a double skin that’s formed with an amorphous-looking steel framework, which references the mountainous landscape found in “Peach Blossom Spring,” a tale written by Chinese poet Tao Yuanming in 421 CE, about a hidden mountain utopia where people live in harmony with nature.

The purification pond featuring the treated wastewater is designed to be the focal point of the ecological education centre. The curved louvered facade forms a mountain dome space that accommodates flower, birds, sunshine, water, breeze, and rain to interact with each other, making it a perfect environment for an ecological educational experience.

An example to be followed widely, I hope!

Florence and the pigs

Tropical storms and hurricanes cause a lot of damage.  But where people think of the wind downing trees and power lines and taring off roofs, most the damage comes from the flood waters.  Water, of itself, promotes mold growth.  But the key problem is what the water carries with it.

North Carolina happens to have some of the most concentrated hog farms anywhere in the world.  Reports EWG:

North Carolina’s CAFOs [hog barns] produce almost 10 billion gallons of fecal waste, enough to fill more than 15,000 Olympic-size swimming pools. Much of this waste is stored in open-air pits, then sprayed on farm fields as fertilizer. Manure pits foul the air and water with bacteria, ammonia, hydrogen sulfide, particulate matter and volatile organic compounds.

[A Duke University] study adds a striking level of detail to prior reports of higher frequency of asthma, bacterial infections, high blood pressure, and various respiratory and neurological disorders for workers and residents in the vicinity of large concentrated animal feeding operations, or CAFOs.

And this is under normal circumstances.  Now, after Florence, much of this is floating around the countryside. Information is starting to trickle in – witness this picture, below (the original article has before and after, for comparison).

An interview with Captain FOG

Captain FOG, aka Barry Orr, next to a small fatberg recovered from the sewers

The Current, one of CBC radio flagship shows, aired a segment this morning about sewers – specifically, the blockages in sewers caused by various fats, oils, and greases (aka FOG) thoughtlessly dumped there.

This included an interview with Barry Orr of London, Ontario, known as Captain FOG.  Here’s an excerpt:

In 2008, the sewers in London, Ont., suffered a 40 per cent blockage related to fat and grease.  Orr, also known as Captain FOG (an acronym for fat, oil and grease) helped to implement the Your Turn program, which provides households with biodegradable cups to properly dispose of their own FOG.

“We’re saving hundreds of thousands of dollars a year here in London and we haven’t had a blockage related to fats, oils and grease in over four years,” Orr said.

What is remarkable about this initiative is that is works through a combination of tools and policies provided by the city, and citizen participation.

You can hear the whole interview here, along with a discussion of fatbergs, an interview with entrepreneur Scott Lewis on turning FOG into biodiesel fuel, and – icing on the cake – a song about working in the sewers by Art Carney as Ed Norton of the Honeymooners.

The toilet over the Emscher River

Between the Waters, Emscher Valley, Germany

One particular toilet from the Lonely Planet guide (reviewed in this blog, here and here) really intrigued me.  It turns out that the toilet introduced as “Emscherkunst” is just the most visible part of a whole self-contained wastewater treatment educational complex – and if that wasn’t enough, that is set in the context of a complete river rehabilitation, one that aims at returning the river Emscher from an open sewer to a wild fish-bearing stream.

In this art installation (one amongst several), you can make your contribution in the yellow outhouse suspended above the Rhine-Herne canal. Gravity takes it down to a series of treatment steps, described by architect Marjetica Potrc as

  a pump that draws water from the river into a septic tank, a constructed wetland (a helophyte filter), a rainwater-harvesting roof, water storage bags (“pillow tanks”), and a fountain located above the Rhine-Herne Canal that offers visitors water of drinkable quality. In addition, the system provides water for irrigating the Community Garden. The project teaches visitors about the various stages of the water supply system – usually hidden underground in their everyday environment – and engages them in such issues as the conservation, treatment and use of water.

How the project works

This is part of a project to rehab the Emscher.  Why would the Emscher still be so polluted, in 21st century Germany? As described in Der Speigel by Matthias Schultz,

 It’s a gigantic open sewer — the largest in Europe. Slaughterhouses and steel mills discharge their offal and refuse here, and the river is a depository for heavy metals and feces.  The reason behind this unfortunate and somewhat pre-modern situation is that the ground is sinking in many parts of the Ruhr Valley. Mine shafts honeycomb the substrata, making it impossible to build conventional underground sewers. Clay pipes would burst, and masonry ducts would crack.

Not only that, but the river was originally turned an open sewer – literally – on purpose.  As described by project consultants Salian and Anton:

  In response to the heavy burden on water resources caused by rapid industrialisation in the region, a strategic decision was taken in 1904 to allocate specific purposes to the Ruhr, Lippe and Emscher Rivers.The Ruhr was allocated for drinking water supply, the Lippe for water supply to industry and the Emscher exclusively for wastewater discharge. Thus, the Emscher (81km) and its creeks (250km) were systematically transformed into open wastewater canals. The Emscher was straightened and lined with impervious concrete beds to convey wastewater from cities as well as industrial areas along the river’s course, resulting in the river becoming ecologically dead.

The whole project is fascinating in its scope and size – more info can be found here; and a summary of the park installations, meant for tourists, is here.