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Archive for May 2020

Chicago, part three: an interesting comment

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After I wrote this blog post on Chicago’s waters, I posted it on facebook.  That generated some interesting comments – including this one, reproduced below, from landscape architect Domenico D’Alessandro.

Domenico says that my article is pretty generic – of course it is.  I’m happy that he didn’t notice glaring mistakes; it isn’t an article, it is a mere post of things I come across.  I post things for myself (it makes it easier to remember stuff) but also for the benefit of readers who may want to hear that some aspects of the environment are quite resilient, and that not all news about the environment are by definition bad.  Chicago is a case in point: Chicago River used to be dead.  Now it is alive.

Does that mean that it was revived in the best possible way – best for the environment, best for society? Of course not.  Chicago is amazing, Chicago is bewildering, but an exemplar of a fair, serene and enlightened society it is not.  The cruelty of the stockyards, the manipulative exploitation of the immigrants, the redlining of Bronzeville, it’s still all there in Chicago.

But I like the Chicago River.  I like that it is no longer polluted and stinky.  I even like the cafes along its Riverwalk – though I do question whether it is a smart development.  Indeed, as you’ll read in D’Alessandro’s comments, a better and more resilient design would have been a public space, green – and without commercial shops that get flooded.

Because flooding has already happened, and will happen again, even as TARP gets completed.  Climate change is daunting.  Some urban development designs do not face that fact, no question.  This is why I am reproducing D’Alessandro’s comments in full: we get to benefit from the perspective of a designer, and an insider: someone who knows both the place and the subject well. (His comments were quickly jotted down – I took the liberty of correcting a few typos). I have also added part of D’Alessandro’s LinkedIn biography, below, for context.


This article is pretty generic; when I presented my concept for the Chicago River Fish Hotel in Zaragoza, Spain in 2005 at a SER conference, I had an extensive account of the history of the river I thought the international community were not totally aware of. The TARP project is still the hope the city is clinging [to] to calm the waters. Now we know that climate change will bring about heavier and more frequent storms [and] it may not be enough. I also think that the whole river walk was a gift from Mayor Daley to his supporters. In 2003 while beginning to design the fish hotel, I also proposed a way to redevelop the stretch of the downtown river as a publicly owned and operated space where a variety of activities and shops [that] would rotate to allow many businesses, artists and other enterprises to benefit equally from the river walk. However the solution chosen was to privatize certain areas and lo and behold the first to have a permit was an Irish Pub. In fact, the river walk is no different than any street up above. The city fathers preferred to emulate [the] San Antonio river walk rather than truly service what the downtown core needed.

My vision was to have, the length of the river at water level, a connected ecosystem of floating wetlands that would provide [an] uninterrupted corridor for the aquatic life and form a green belt for canoeing and kayaking. The people would [have been] at the medium level with booths that hosted different vendors on a seasonal basis. This would allow [for high fluctuations] in the river to occur without impinging on the activities and not creat[ing] damages. More recent concepts proposed try to turn the river into an entertainment venue, whereas my concepts try to turn it into a cultural and educational venue.

It seems that private interests still run the show and the riverbanks are just an extension of the streets above. I don’t know if this will change in the future but most of the downtown corridor has been developed and only outlying stretches are actually dedicated to aquatic ecosystems. Now with the flooding the restaurant areas are off limits as are the connections at water level. During the recent storms MWRD was forced to release sewage into the river and lake. So the problems still afflict the city and thus far the solutions proposed and built are only marginally successful. Of course, Chicago being the windy city, everything is painted with boast and pride. There is even a macabre pride in describing the rampant corruption ‘”the Chicago way”. I am still hoping that the new administration can somehow free itself of such a past and truly begin a process of transparency and open access to projects and ideas. Thus far though the old ways prevail; and for people such as myself that are not part of the donor class and not politically connected and do not shy away from voicing their opinions and criticism, participation in city projects remains elusive. If you list the projects you will notice a recurrence of the same firms exercising control of city contracts. I am not against everything the city has done, there are some very good projects among the many mediocre questionable ones.


Domenico D’Alessandro is a regenerative design consultant (MLA in landscape Architecture- University of Guelph) and artist (Fine Arts – Accademia di Belle Arti, Firenze, Italy). He is principal of D’Alessandro & Associates, Inc. based in Algonquin, Illinois. His landscape environmental designs have received US Environmental Protection Agency, Chicago Wilderness, the 2007 Mayor Dailey Greenworks Award and an Integrative Habitat Design Competition 2012 (international)award. He has been a member of Chicago Wilderness Sustainability Team for many years.

Specialties: Integrative Habitat Design – originator of the vertical watershedTM concept and the bioshaft design process(R) for water quality and management, and habitat creation in the urban core.

Written by enviropaul

May 26, 2020 at 4:42 pm

Chicago, part two: all cleaned up, almost

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Tourists in Chicago now flock to the Chicago River.  It is rimmed on both sides by famous skyscrapers and the architecture tours on river boats are one of the “must” attractions of the city.  On the south side of the downtown portion of the river is the Chicago Riverwalk, a new amenity designed by the Sasaki group.  It is a continuous walkway that stretches along twelve blocks from the lake to the river fork, linking waterfront cafes and restaurants, kayak and paddleboat rentals, and a small museum along a new landscape of trees and aquatic plants lining the waterfront.  It’s lovely, and very popular.  You see people fishing from it; there are now seventy species of fish who call the river home.  What a change from the dead, stinking industrial river that caught fire every so often (see part one here). How did that happen?

Fishing along the floating gardens of the Chicago riverwalk

The whole story of how Chicago cleaned its waterways is remarkable.  At the mouth of the Chicago River is the Jardine waterworks plant (the biggest in the world!) that treats Lake Michigan water for its drinking water supply, using chlorination, activated charcoal, and flocculation.  Downstream (though away from the mouth, since the direction of the current has been reversed) is the Stickney wastewater treatment plant (the biggest in the world!) that now captures and treats sewage before it reaches the river.

I was lucky enough to be invited to visit Stickney (not all tourists do).  It’s a remarkable plant, and not just for its sheer size.  But it is indeed immense; as far as the eye can see, along the old Ship and Sanitary Canal, rows after rows of rectangular and circular tanks, looking like a never-ending array of swimming pools (with brownish water, mind).  At 1.65 square kilometer, it is the size of a village, and it treats nearly one trillion litres of sewage per year (by comparison, Annacis Island, BC’s largest plant, treats 175 billion litres, still a considerable amount). But the treatment level is in a class of its own: as at Annacis, solids and BOD are removed, but so are the fertilizer elements nitrogen and phosphorus.  This is crucial to prevent the growth of nuisance algae downstream.  Both nitrogen and phosphorus are removed using a clever process that relies on subjecting the bacteria to a sequence of on-again/off-again aeration, which shocks the bacteria into removing the excess nutrients (a process technically called nitrification-denitrification for the nitrogen, and Bio-P luxury uptake for phosphorus).  Unfortunately, concentrated phosphorus has a tendency to precipitate as struvite, clogging the pipes; Stickney is piloting a new process (developed in Vancouver) to prevent the problem and produce valuable fertilizer instead. I love the fact that such a large plant is not afraid to experiment (hey, it’s Chicago; they may be a lot of things, but timid they are not).

But, of course, the Stickney plant can only treat whatever sewage flows to it.  That is most of it; but Chicago, like many other cities, has an issue with combined sewer overflows (CSOs).  During heavy storms, the sewers, tasked with carrying away sanitary sewage and draining storm waters both, cannot keep up.  In this case they overflow into the Chicago River.  So even after Stickney was built, as early as 1930, the waters of Chicago River remained of questionable quality, especially after a downpour.  TARP, the solution that Chicago decided on, measures up to Chicago’s reputation.

It may have started with a rumor: the story that a huge flood in 1885 resulted in 90,000 cholera deaths started in the 1970s.  It is totally false, but maybe it prepared the ground to get the Chicagoans to accept the idea that a giant storm control system is needed. The Tunnel And Reservoir Plan, TARP, started construction in 1980.

The basic idea is simple: create storage space for storm water.  During a downpour, allow the mixed waters to flow into the storage space; then, once the storm is over, pump everything back up to the sewage treatment plant.

Sounds easy.  But Chicago’s storms, like everything else about the city, are enormous, and so is the need for storage.  The system started with four large tunnels (if you dig deep enough, there is good rock under the city); with a diameter between 3 to 10 meters, the tunnels which are 175 km long and as much as 100 meters deep in place can store 8.6 million cubic meters.  This is a huge volume, one that really helps with preventing the polluting CSOs.  But it is still not enough.  The reservoirs, located in former quarries, will supply nearly ten times as much storage when completed in 2026: 69 million cubic meters.  The tunnels, by themselves, have reduced the number of CSO events by half.  And since the Thornton Reservoir, the first of the three in the plan, has come on-line in 2015, CSOs have been nearly eliminated.

How TARP works

Add to that other runoff-control measures such as an aggressive program of green roofs, and it is clear that the city is well on its way to solve the problem. (You can see an impressive number of green roofs from the observatory on top of the Willis Tower, the biggest in the world!  Well, used to be, anyways.)  And there is good public awareness of the CSO problem; whereas in most other cities it is drought that leads to conservation measures, the Friends of Chicago River ask that you shorten your shower, hold off on doing the dishes when it’s stormy out – to minimize the amount of sewage produced.

And even Bubbly Creek is finally getting cleaned-up, another complex and expensive project.  There is an estimated 3 meters of organic muck at the bottom of the creek; the current plan is for capping the sediment with sand and rock in order to isolate the muck from the water above (this is seen as simpler than dredging the sediment; I have to admit to some skepticism; fermentation gas has a knack for making its way through anything).

But a full clean-up of the Chicago and Des Plaines Rivers may bring a new set of problems; it seems that it is the pollution still found in these rivers that is preventing the invasive Asian carp from entering the Great Lakes.  If the clean-up is complete, all bets are off.

And it’s not as if Chicago has completely solved its flooding issues.  As recently as May 2020, the Riverwalk was completely submerged.  The new storms of the climate change era are becoming more frequent and more intense.  The last one, on May 17, caused the flow of the Chicago River to be reversed, flowing back into Lake Michigan as it naturally did more than a century ago.

The riverwalk, flooded in May 2020

But if any city can tackle this kind of challenge, it’s gotta be Chicago.

Post-Script: This post has generated an interesting comment, from a landscape architect who has a different view of what the Riverwalk should have been (and may well be right given the recent flooding).  This response can be found in part three here.


Written by enviropaul

May 25, 2020 at 4:45 pm

Chicago, part one: descent into environmental hell

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Why would you create a city there? Chicago started on a swamp – a lowland, with nowhere for water to go. Not a promising place.

But it was a convenient gathering spot for the Pottawatomie who harvested the wild garlic that grew there (the native name of the plant is the origin of the name Chicago). And it’s located where the Mississippi-Missouri watershed meets the Great Lakes; this was a great hub of commerce for the first nations, way before the first French explorers ever set foot there.  Eventually, Chicago grew into a giant hub of commerce: waterways and then railways moved move much of the goods from the west through Chicago to New York and other big Eastern cities.

Colonists started gathering around where Jean Baptiste Pont du Sable built a farm in 1780.  And then the city took off in a runaway growth: from a population of 4000 in 1840, it had reached 90,000 twenty years later, topping 1.7 million by 1900, the fastest growing city ever (Greater Chicago has a population of about 11 million today).  But the city remained a swamp.  The streets were a quagmire, constantly mired in mud. In a swamp, there’s nowhere for water to drain to.  Ditches or storm drain would have had nowhere to flow to.  Hardly a promising situation for a fast-growing city.

The solution was one of the first instances illustrating that Chicago does things differently; the city is now called the City of Big Shoulders (by its boosters) or the Windy City (by its detractors, for being such a braggart).  Sure enough, the city’s next move, Chesbrough’s 1856 sanitation plan, was a mixture of hubris and vision.  If storm drains can’t be buried under the streets, then they will be laid above ground, with new streets built on top of them.  That meant that every building’s front door was now at the basement level; city hall told the owners to either open a door on the second floor, or raise their buildings. Most decided to jack up their building. The most famous may have been Briggs house, a fancy five-story brick hotel that was slowly raised, manually, using an army of workers cranking jacks at a synchronized signal – while its 450 guests continued to stay and sleep.  Raising the whole city took twenty years.

Raising Briggs House

(Building over a swamp created another difficulty: masonry buildings would settle awkwardly.  Deep pilings supporting a steel armature solved the problem; that was the origin of the first skyscrapers, something else Chicago brags about.)

The new sewers, located above ground, could all empty into the small Chicago River.  The streets, now also above the natural ground elevation, drained well and the mud was a thing of the past.  Problem solved.

Except that the Chicago River emptied, sewage and all, into Lake Michigan, which is where Chicago took its drinking water.  Unsurprisingly, water-borne diseases became common.  Cholera had already appeared in 1854, but it came back in 1859, and 1866.  Typhoid and dysentery were a chronic problem well into the twentieth century. The rapidly increasing population (as well as the livestock in the stockyards) increased the epidemic risks.

Chicago’s response was just as gutsy as with its sewers: if the Chicago river flowing into Lake Michigan is the problem, just make it flow elsewhere. Just east of the city is a barely noticeable slope in the flat land, enough that waters west of it flow into the Des Plaines river, which flows into the Mississippi watershed.  City Hall decided to simply punch a canal between the two rivers.  As it happens, the Des Plaines river has an elevation slightly lower than the Chicago river.  There was already a small canal (with locks) between the river; all that was needed was to broaden it and deepen it.

But it’s not just the Chicago River that is higher than the Des Plaines River; Lake Michigan, that the Chicago River lazily flowed into, also is.  When the Ship and Sanitary Canal, as it was called, was completed, in 1900, the lake waters started rushing through the Chicago River backwards, at a rate of 140 cubic meters per second (that is like the flow of the Alouette river when it’s in flood mode).  By the time the new locks and flow control structures were completed, the level of lakes Michigan and Huron had dropped by 6 centimeters.

Typical of Chicago, they acted first, asked for permission later.  They were rushing to complete the work, because permission was indeed denied, in the form of a federal court injunction on behalf of the downstream city of St-Louis, which was none too pleased to be receiving Chicago’s sewage.  But the canal was completed by the time the wheels of justice had slowly turned.    This was far from the only lawsuit; a famous one was a joint action by the governments of both the US and Canada, concerned for the navigation channels (see here for a summary).  Chicago just shrugged its broad shoulders.

That may have solved the drinking water problem, but Chicago River went from bad to worse.  Soon it was biologically dead, with enough oil and grease floating on it that the river often caught fire – often enough that it became a local entertainment.

But if the Chicago River was bad, one of its small tributaries, Bubbly Creek, was even worse.  The small creek drained a wetland that was purchased by a consortium of railway and meat packer interests.  A giant consolidated stockyard was created; the Yards, at became known, turned Chicago into “the hog butcher for the world”.  By 1890, 9,000,000 animals (beef, hog, sheep) were butchered yearly.  Manure, bedding, offal and slaughtering waste was discharged into the small creek, with predictable results.  Upton Sinclair, in his 1906 book The Jungle, wrote about the creek:

all the drainage of the square mile of packing-houses empties into it, so that it is really a great open sewer a hundred or two feet wide. The grease and chemicals that are poured into it undergo all sorts of strange transformations, which are the cause of its name; it is constantly in motion, as if huge fish were feeding in it, or great leviathans disporting themselves in its depths. Bubbles of carbonic gas will rise to the surface and burst, and make rings two or three feet wide. Here and there the grease and filth have caked solid, and the creek looks like a bed of lava; chickens walk about on it, feeding, and many times an unwary stranger has started to stroll across, and vanished temporarily. The packers used to leave the creek that way, till every now and then the surface would catch on fire and burn furiously.

To this day, the creek still emits bubbles from the decomposition of the animal waste still present in the sediment.  The short video below gives an interesting view of it.

Nowadays Chicago River is clean – it’s a city amenity – and a clean-up program has started on Bubbly Creek.  This remarkable turn-around is told in part two.

Written by enviropaul

May 25, 2020 at 4:22 pm

Flood control strategies: Hamburg as a case study

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I have mentioned before that the city of Hamburg is vulnerable to flooding, and that it has developed some interesting approaches to manage floods.  There is public education. There are initiatives to increase infiltration, turn the city into more of a sponge during downpours, create storage; I have described some of the flood control strategies for the Alster watershed.  But what about the big monster at the door: the Elbe river?

The Elbe is why Hamburg exists (it is, above all, a merchant port) but also why the city is so vulnerable to flooding, as the above map shows.  The river conveys downstream the impacts of storms that may originate in Saxony or even further upstream, past the mountains, in the Czech Republic. It also funnels storm surges from the North Sea downstream.  What is unique about Hamburg’s approach is its acceptance of the idea that floods are unavoidable – that allowing the water in and minimizing the damage is far more sustainable than higher dikes and storm barriers.  Some of this comes from the early work of Erik Pasche (1955-2010).

Pasche developed the concept of cascading flood compartments and adaptive response (yes, a bit of a mouthful).  What this translates into is the development of a hierarchy of where flood waters should go, and in what sequence; identify and protect what is vulnerable within that.  This can be seen in this diagram below:

The idea is that the flood is routed to pre-selected areas, and only to those if the flood waters can be managed this way; a worse flood may cause other areas to be inundated, in sequence, always with the idea that the more vulnerable areas are the last to be flooded.  This way the expected damage resulting from any given flood is minimized, as showed on the right side of the diagram.

But what does that look like in practice?  The concept applies best to the low-lying island of Wilhelmsburg.  This was the part of Hamburg worst hit by the 1962 flood, which killed 315 and left over 60,000 homeless.  The island is now home to a large part of the city’s harbour, heavy industry facilities, but also a sizeable residential sector (including the new development of the 2013 IBA), as well as farm fields.  The diagram of the island below shows the areas that would be flooded with and without compartments; the vulnerable residential areas are indicated with two dotted perimeters.  Without the compartment approach, which prioritizes flooding farm fields, it is clear that much of the flooding (in darker blue, right diagram) would occur in the residential sectors.

There are other innovations – in particular, for asset protection.  If you are going to decree that a particular place is where flood waters will be let in, it will be easier to accept if the various buildings found there can be somehow protected.  At the same time, the strategy needs to expand to areas that are not designed to be flooded; prudent design always assumes system failure.  This is expressed in the diagram below.

But how can one design buildings to withstand a flood?  In rural areas, houses and barns may be built on an artificial mound (these are called terpen, and the Dutch have been building them as well).  But in built up areas, buildings with stilt foundations, floodable ground floors (such as garages), or reinforced doors and windows may work well.  This is actually the strategy followed in HafenCity and the Fishmarket area, and it has been shown to be successful.  For instance, on November 9 2007, urban developer Thorsten Gödtel had taken a seat inside a café in HafenCity just as a North Sea gale had sent a 5- meter high storm surge of water up the river.  He recounts that

as he sipped a cappuccino, the turbid river rose outside, creeping up the establishment’s extra-thick windows, and temporarily turning the cafe into an aquarium. Later, he’d exited the building onto the street through a door one flight up, without even wetting the soles of his feet.

I like to imagine what such as strategy would mean for us.  How would Richmond fare with a flood managed using a Pasche cascade? Where would the inner dikes be installed?  And could the approach of HafenCity be used for False Creek or Coal Harbour?

Written by enviropaul

May 2, 2020 at 8:39 pm