Industrial heritage in Montreal: it’s about sewers

Montreal may get a new small museum: the old Craig sewage pump station, initially set to be demolished, is to be partially preserved. It would be turned into an industrial heritage museum and interpretation centre.

For those who know Montreal, this is the intriguing boarded-up structure at the foot of the Jacques-Cartier bridge. The structure itself is beyond repairs, but not what lies in its basement: four enormous steam-powered pumps that date from the 1800s, and the now-unused brick sewers that were filled by these pumps.

Heritage Montreal, the group that has been lobbying for the restoration of the site, is hoping that 150 metres worth of these sewers may eventually be opened to visitors, as part of an interpretation centre of the sewers.  

Under the Craig pumping station

Montreal has lost quite a bit of its industrial heritage, so this is a very welcome initiative. But sewers? Indeed, this would make the interpretation centre unique in North America, but it would join an elite group of European cities where a sewer visit is a sought-after tourist attraction: Paris, Vienna, Brussels, or Prague, to name the best-known ones.  

It is already possible to take a few steps into Montreal’s very first storm sewer at the Archaeology Museum of Pointe-à-Callière, which is great.  But this would be the first museum fully dedicated to sewers. I’d love to see schoolkids visit a place where they can learn more about what happens when you flush.

More info here, here, and here.

Below Old Montreal, in the archaeology museum

The see-through public toilets of Tokyo

The picture shows it: the walls may be tinted, but you can see everything inside the new public toilets in a park in Shibuya, Tokyo. But it’s not meant to encourage risqué behaviour; quite the opposite, in fact. The walls turn opaque when the toilet is in use.

According to [project organizer the Nippon Foundation], the toilets serve a practical purpose. “There are two concerns with public toilets, especially those located in parks. The first is whether it is clean inside, and the second is that no one is secretly waiting inside. At night they light up the parks like a beautiful lantern.”

Attractive, safe, and convenient; these are the brainchild of Pritzker-winning Shigeru Ban. As with many Japanese toilets, these are high-tech: seat warming, washlet-style wash and dry modes, lids that open or close automatically. But the real breakthrough is the wall: it is made of polymer that includes a type of liquid crystal that responds to an electrical voltage. The crystals align to the electrical field when the voltage is applied, allowing light to go through. When the current is interrupted, which is what happens when the door is locked, each crystal adopts a random position and the wall becomes opaque as a result.

I wish I knew more about the material. I found an article in that may or may not be about this material. If someone knows, please share!

As for architect Ban: the award-winner now focuses on simple, inexpensive structures that can be quickly put up to house disaster victims; these may be prefabricated and use material such as waste carboard.  I’m impressed by this guy!

I certainly would welcome these public washrooms in Vancouver. Hey, any kind of public washroom, especially near transit, would be nice!

Electric Oranges

The city of Seville, in southern Spain, has an unusual problem: orange trees.

Except in the narrowest lanes of the historic sector, some 50,000 orange trees line the streets, providing needed shade, intercepting rainfall, and perfuming everything with an enchanting aroma when in bloom. But they also produce oranges.

The trees are ornamentals, and the oranges are not edible; the famous bitter marmalade oranges grow in farms nearby, but these city oranges have no use. The city picks up fallen ones from the sidewalks in the more chic and touristy neighborhoods, but in most of the municipal area, they stay on the ground, rot, and become as slippery as banana peels. To say nothing of the contamination that the smelly, sticky rotting juice contributes to the sewers and drains.

The city has about 200 employees whose main task is to remove the fallen fruit. These used to be sent to a landfill, but a new project has been making use of them, starting last year. In this pilot, created by Emasesa, the local water utility, the oranges are fermented in an anaerobic digester (a sealed tank to you and me). The oranges may be bitter but they still contain a lot of simple sugars, perfect food for the bacteria that produce biogas.  And the yield is high: the 50 tonnes of oranges that were used in this year’s pilot project produced enough biogas to generate electricity for 250 households. Considering that between 4,500 and 5,000 tonnes of orange waste are generated annually, a full scale project would generate a substantial amount of electricity (50 kWhr per tonne, to be specific).

The peel, pulp, and pips do not fully degrade in the digestors, though. What remains is then composted into a stable organic soil amendment (something quite welcome, considering the low levels of organic matters of the tired soils around the Mediterranean Sea). All organic waste has the potential to generate biogas like this, and many utilities are considering expanding the feed of their digestors beyond sewage sludge. Aside from the cost of bigger tanks, it is free energy.

Seville’s problem – orange trees – is rather unusual. But it something to remember when city hall opposes planting fruit trees on city land because of “the mess of the fallen fruit”.  There is always a solution; fresh fruit to the neighbours or the food bank; rotting ones, well, make energy out of them. It’s just solar energy. Via a tree detour.

More info here:,,  and

Pipe Dreams: a book review

I just finished Chelsea Wald’s new book, Pipe Dreams.  It’s great fun – and a must read for all water nerds, anyone interested in technology development, or public health, or…I think everyone should read it.

I know a fair bit about the field, but Wald still surprised me with specific cases I hadn’t heard about: for instance, the vacuum sewer system of Sneek, in the Netherlands (details here and here); the smart system used in South Bend, Indiana, to reduce combined sewer overflows (details here and here); or, to my shame, I wasn’t aware of the hydrothermal system that Genifuel is pioneering in Metro Vancouver to convert sewage sludge into crude oil that can be refined (by the Burnaby refinery).  It was also the first that I heard about Ludwig Brieger, a German chemist who isolated the various components of malodors, including skatole (shit just doesn’t smell like shit without skatole, but the compound is also essential for jasmine fragrance). 

There’s a mine of facts and figures, of anecdotes about assorted projects, including the always enlightening failures. The book feels a times a bit disorganized, jumping across continents and development projects, but that is also part of its charm – it never dwells on anything too long, even if it comes back to a topic several times in different chapters.  But I would have preferred that a key paragraph found towards the end of the book had been featured earlier and more prominently, because it is key to the whole topic: how the taboo around the topic is detrimental. Here is the quote:

Most people don’t ask – until our produce gets recalled – whether the people who pick our vegetables should really have to be squatting in the fields to relieve themselves. We don’t worry about how people who are incontinent manage their toilet needs when out of the house – until we find ourselves in desperate need of a public toilet ourselves. We don’t contemplate the resilience of our wastewater treatment plants until a storm overwhelms them, coating our cities in fecal matter. And we don’t think to ask why the toilet hasn’t changed in the past 150 years even as we absorb, adapt to, and sometimes fight transformative technological change in almost every other segment of our lives.    

Wald, Chelsea 2021.Pipe dreams: the urgent global quest to transform the toilet. New York: Avid Reader.

Poo-powered funicular

Funiculars are neat, efficient ways to get passengers to climb hills. Water-powered ones are even better: they produce no emissions whatever. They work in pairs, connected to a cable. The descending car simply collects water that is flowing near the top station, enough to create a counterweight that is sufficient to bring a bunch of passengers in the companion car up, even if the trip downhill is empty.

But the funicular of Fribourg in Switzerland does one better – why disturb a fresh water stream when there is wastewater available? It’s the same principle, except that the bottom car empties its load into the local sewer, to be treated at the plant downstream.

The Fortifications of the City of Friborg (Fribourg) : 2022 Ce qu'il faut  savoir pour votre visite - Tripadvisor

Bloomberg reporter Mimi Kirk writes that

Fribourg’s funicular first came into existence because of a brewery. The Brasserie du Cardinal built the conveyance to ease its workers’ commute and managed it until 1965, when the city took it over. Commuters still use the funicular, and tourists enjoy its quirky appeal and views. One TripAdvisor reviewer reported only a “bit of a funky odor,” while another exclaimed, “Boy does it smell like a toilet!”

Clever, isn’t it? Flowing water at elevation contains a lot of embedded energy. Fribourg has come up with another, more recent innovation, this time with its water supply system. Water that flows (like sewage) from the upper to the lower town develops quite a bit of pressure at the bottom of the hill, which may result in substantial leaks (force main sewers have the same issue). To alleviate the problem, instead of using pressure valves, propellers are inserted into some of the pipes, generating electric power. Pretty smart – but not as much fun as a sewage powered funicular. Below is a little video that gives an idea.

Northside Park: recycling a sewage treatment plant

Wastewater treatment plants are massive, with enormous concrete structures all over. What do you with a site once a plant has outlived its usefulness?

This is what Denver, Colorado, was confronted with in the case of the former Northside WWTP which had been decommissioned since the early 1980s. The cost of demolition was prohibitive, and developers reacted poorly to the stigma attached to human waste, treated or not. The site became vandalized and covered in graffiti.

The city decided to turn the site into a park, but the cost of removing all the concrete remained a problem. An alternate design, by the landscape architects at Wenk Associates won the day. The result is a park that incorporates some of the concrete structures and actually makes the park more interesting – a sort of a modern Stonehenge, with some imagination. Take a look at these before-and-after pictures.

Early Covid detection: check the sewer

Des personnes munies d'équipements de recherches.

Authorities have been “flying blind”, to use The Tyee’s headline, since the appearance of Omicron. The new Covid variant is so contagious that testing facilities cannot keep up, and too few at-home test kits are available. Modelers complain that they cannot predict the number of cases to be expected in a week or two, because of the lack of data. This makes it hard for policy makers, of course: what is effective? More restrictions? New mask regulations? Without data, this is little better than guess work; and even counter-productive measures cannot be identified.

This is where systematic wastewater testing could help. Experience so far show that detecting Covid in sewage often gives the earliest indications of a coming trend; a new peak will be detected before it materializes in declared cases or hospital admissions.

Sarah Dorner, of Ecole Polytechnique in Montreal, compares it to having a second engine in a plane: “When the first engine – testing kits – fails, then sewage can become very useful.” (my translation)

But specialists who sample for the presence of Covid in wastewater don’t understand why this approach isn’t used to better follow the evolution of the peaks, especially now that detection centres are overwhelmed, adds the article. Dorner shows that the peaks in Covid concentration in sewage and that of declared cases follow each other almost perfectly – except that the sewage data shows up a few days earlier. This is key for better planning.

The detection can be as general or as fine as needed, another advantage. Sampling at a receiving wastewater treatment plant gives the broad outlines of its presence in the population; sampling from a smaller line can give the same information for a particular neighborhood, or even for a school or a large workplace. CBC has a good pair of videos about the technique.

Wastewater sampling is done in most Canadian cities, but it is piecemeal and so results are incomplete and difficult to interpret. One can only hope that this becomes more generalized and systematic.

A poo book by Boucar Diouf

Here’s a post for those who can read French: a review of a book about poop by Quebec writer Boucar Diouf, titled Apprendre sur le Tas (learning on the spot).  I have no idea why there’s no English translation to be found – and it’s really too bad, because the slim book is both very informative and very funny.

To give you an idea, I’ve translated the blurb from the back:

The relationship between people and their excrement is fascinating.  Mix shame, disgust and fascination and you’ll get the emotions of an average person confronted with their digestion remains. Scatological humor finds a public ready to burst out laughing – and, incidentally, facilitate the movement of the topic discussed, since laughing is known to ease bowel movements.

When one looks at excrement as a biologist, one discovers a fascinating universe. Feces and urine are used by animals to mark territory, fool predators, trap prey, cool off, signal one’s sexual availability, and so on. Between humor and information, this book should make you laugh while stimulating your mind. An ideal book for people of all ages who like to read while sitting on the throne – while becoming smarter about a topic that is anything but boring.

Even though it’s a topic that I blog about, I learned many things in the book. Yes, I already knew that wombats make square poo, or that Australia had to import dung beetles in order not to be submerged under cow patties. But I didn’t know that eiders use poop hoping to discourage egg harvesters. Or that termites use the fiber from their poop to strengthen their giant nests.  Or that an Australian spider, Cyclosa Ginnaga, looks like bird shit – a good way to deter birds.  And I’m happy that a number of the short entries are about whales – in particular, the role that whale poop plays in fighting climate change.

Illustrations by Philippe Béha

The second section of the book is about human dejections – our attitudes, our use of them (or not), including (it’s Christmas, after all!) a mention of the Catalan Caganer figure (a little shitting character added to nativity scenes).  Then he moves on to farting – and I learned that farting in public, among the Sénégal farmers where Diouf is from, is a big no-no.  There is very little mention of sewage and sewage treatment, unfortunately – but hey, Diouf book aims to be entertaining, not technical.

Who is the author, anyways? Well, he is a beloved humorist, well known in Québec.  But he is also a trained biologist, so he has all the needed creds to tackle this topic.  He is mostly unknown in English Canada, but at least the Canadian Encyclopedia has an entry for him.

But why, oh why, is he not translated?  The book would make such a good Christmas gift…

Merritt’s sewage

What happened to the people in Merritt has to be one of the saddest situations. First the fires, then the flood; as I write (Nov 23, a week after the floods) residents are still unable to return home. And there is still a boil water advisory.

Merritt is not the only place where this happened, of course, but it got hit particularly hard. And here the news mentioned that the sewage treatment plant was out of commission; any use of water, any flushing would just add more flood water. But why Merritt, in particular?

I looked up info on the wastewater treatment plant. It is a smallish secondary treatment plant. For the non-technical reader, this means that solids are taken out, as is the material that can rot (and deprive the receiving waters of oxygen, hence the name: Biochemical Oxygen Demand, or BOD). Annual reports show an effective treatment, over 90% of both solids and BOD normally removed.

But the problem is that the water, treated or not, needs somewhere to go. As CBC put it:

[Greg] Lowis [Merritt information officer] said it was too early to tell if any sewage had escaped and caused contamination outside of the treatment system. “If anyone flushes a toilet or has a shower that does anything in Merritt, that water has nowhere to go. We have no treatment capacity, it will simply back up in the system.”

This highlights one key vulnerability of wastewater treatment plants anywhere: they are always located in the lowest elevation of the city, to get sewage flowing downhill with as few pumps as possible. But because they are so low, they are sitting ducks when it comes to flooding.

But Merritt has it even worse. Treated waters are normally discharged into a large infiltration basin. This can be seen on the Google Earth map below; the treatment plant is on the right side (they kinda look like a series of swimming pools), while the infiltration basins, across the river, middle left, look like large lakes.

This is normally a great design solution. Merritt is located in a very dry area, and even with treatment the local stream (Coldwater River) would have a hard time dealing with sewage during low flow periods. A much better approach is to use the effluent to recharge the local groundwater; an added benefit is the filtration provided by the soil.

Except, of course, when the whole thing is underwater. This brings home how vulnerable our infrastructure is to climate extremes. Meanwhile, I hope people in Merritt get to go home as soon as possible. Climate change is not an abstract thing.

Waiting for the toilet

A row about toilets reveals a lot about women’s place in China (the Economist)

World Toilet Day, last week, was a reminder of just how important toilets are.  This year the campaign draws attention to the fact that toilets (and sanitation in general) are underfunded, poorly managed or neglected in many parts of the world. This has been shown to have serious consequences for the health of poor and marginalized communities.

But the availability of toilets has interesting political impacts as well. Last month The Economist reported on such a situation in China, reminding the readers that

In 2012 a group of feminists protested against a shortage of public toilets for women by using men’s lavatories instead (see picture). State-security police responded by harassing and threatening them. But the government took up their cause. Cities started building more toilets for women. Last year, at the UN, China cited this as a big achievement of its efforts in the past five years to improve the lot of women. It did not mention the people who had pushed for such change.

In its headnote editorial, the magazine noted that

there has been some progress. The party has taken steps to remedy a humdrum but non-trivial grievance: that there are not enough public toilets for women. In 2016 it decreed that, when building them, there should be at least three places where women can relieve themselves for every two for men.

[But] most of the toilet-reform activists have been forced to give up their campaigning. Some are subject to intense surveillance by the state. [But] feminist causes are not dead. The country’s media are not allowed to report on the #MeToo movement. But the same grievances have bubbled up in China. A growing number of women are suing powerful men for sexual assault. #MeToo has fuelled an “unprecedented interest” in women’s rights, says Lu Pin, a Chinese feminist who went into self-exile in America in 2015.

In fact, much of the authorities attacks on sexual harassment has been used as a way to curb sectors that seemed to slip beyond government control: independent businesses, or the entertainment sector.

This was all from last month, and now seems remarkably prescient: last week, tennis star Peng Shuai disappeared shortly after denouncing a high official of sexual harassment. This has become a huge embarrassment for China and fuels a campaign to boycott the upcoming Olympics in China.

But let’s remember what’s behind the original spark: a lack of availability of public toilets, and a willingness on the part of Chinese women to get organised and protest.