Tuesday, June 28, 2011

Canal Ecologies: Toxicity

[a fitting tip of the cap]

Today’s excerpt from the Field Guide to Urban Industrial Canals is on the subject of toxicity.  For the first installment on hydrology see yesterday’s post, or check out the entire guide here.  We suppose it’s only right to acknowledge an obvious debt of gratitude to Reyner Banham’s seminal Architecture of Four Ecologies.  This chronicle of Los Angeles was an obvious inspiration, and is a great read if you have a chance on a lazy summer day.  Though we can’t compare with the lucid prose or critical analysis of Banham’s work, it is in a similar sense that we use the term “ecology”.

Toxicity:  Eccentric Substances
Toxicity is a tricky theme regarding the subject of canals, and industrial cities in general.  There are many ambiguous terms such as pollution, contamination, degradation, sewage, and landfills as well as a number of euphemisms such as brownfields or “post-industrial landscapes”.  For the most part these leave people confused, with vague sentiments resembling “that doesn’t sound too bad, but I don’t want to live near it” or “it’s fine as long as it stays over there”.  By being specific about certain substances, we may however be able to avoid this conundrum.

Toxicity relates to any substance which impedes the normal biological functioning of an organism.  One key to remember about toxicity is that it is almost always in relation to exposure.  That is, most substances considered toxic are not harmful until exposure reaches a certain amount, be it nuclear radiation or road salt.  Toxicity in urban industrial canals comes from two main sources:  the stormwater and sewage from the surrounding city, and industrial sources such as factories and storage yards along the banks of the canal.  The first is directly a result of the hydrological patterns of the canal and the city; as the canal is usually in a low point, all of the brake dust and motor oil and estrogen and caffeine that is contained in our sewers or lining our streets dumps into the canals during a storm.  This is because the canals are usually the output for sewer overflows, which become taxed by the extra water flower through the system during a storm.  The toxic inputs from these sources are usually ongoing.  In fact, one of the primary uses of canals after their industrial life was to turn them over to waste transport systems.  In the case of the Chicago River, the urban section of the larger Chicago Sanitary and Ship Canal it was said to “run black” on the day that industrial operations ceased because the canal began carrying barely treated sewage from the city.
[the US Army Corps map of the Chicago River, an urban canal part of the larger Chicago Sanitary and Ship Canal; this canal is one of the reasons Chicago became an important city, offering a logistical shipping connection between the Great Lakes region with the Mississippi basin waterways]

The second source of toxicity- the historical industrial uses along its banks- is a bit more insidious.  The list of industries is long and remarkably consistent from city to city:  manufactured gas plants, tanneries, chemical manufacturers, liquid gas storage, concrete plants, slaughterhouses, grain storage, steel production, glue factories, tobacco warehouses, road salt storage, ship building, and junkyards.  There are several more but I highlight a few of the common ones that appear in most American cities.  The reason for this remarkable consistency has to do with the technologies of the time period, and the role of the canal in industrialization.  The most important use of the canal was the transport of bulk materials that were fundamental to the industrial processes of modernizing American cities.  Massive quantities of grain, building stone, coal, cow hides, and road salt from the hinterlands as well as other cities was vital to these expanding economies, and industrial canals became widespread in the Americas at a time when the only overland option for transport were horse carts.  The railroad did not come into widespread use until several decades after the canal boom had commenced. 
[a diagram of a combined sewer system; this is the prevalent system in most American industrial towns; the term "combined" signifies that both stormwater and sewage from domestic, commercial, and industrial applications pour into the same pipes; during rain events overflows are frequent; often the release valve is into a canal]

Many of the burgeoning industries, including the manufacturing gasworks and tanneries, located themselves along the canals where they could receive their large daily shipments of coal and carcasses.  In addition to using the canals to receive shipments, it was also common to use the canals to dump the wastes and byproducts resulting from the tanning of hides, the drawing of candles, or the stamping of rivets.  In the case of the Riachuelo in Buenos Aires, newspaper reports of the river “running red with blood” from the livestock warehouses were reported right from the start.  Writer Thomas Wolfe, writing in the 1920’s in Brooklyn, notes of the Gowanus in Brooklyn:
    And what is that you smell?
    Oh, that!  Well, you see, he shares impartially with his neighbors a piece of public property in the vicinity; it belongs to all of them in common, and it gives to South Brooklyn its own distinctive atmosphere.  It is the old Gowanus Canal, and that aroma you speak of is nothing but the huge symphonic stink of it, cunningly compacted of unnumbered separate putrefactions.  It is interesting sometimes to try to count them.  There is in it not only the noisome stenches of a stagnant sewer, but also the smells of melted glue, burned rubber, and smoldering rages, the odors of a boneyard horse, long dead, the incence of putrefying offal, the fragrance of deceased, decaying cats, old tomatoes, rotten cabbage, and prehistoric eggs.
    And how does he stand it?
    Well, one gets used to it.  One can get used to anything, just as all these people do.  They never think of the smell, they never speak of it, they'd probably miss it if they moved away.

Many of the toxic substances in these places such as the polycyclic aromatic hydrocarbons (PAH’s) and polycholorinated biphenyls (PCB’s) from the manufactured gasworks still persist in the canal sediments.  High concentrations of solvents and oils are often leaked into the canals from the surrounding bus depots, and heavy metals including cadmium and lead from industrial processes and car exhaust tend to concentrate in the sediments and along the banks.  Sometimes, when the currents change, releases of oil from the soil can cause large slicks on the surface.  In addition, sewage overflow and stormwater runoff into these canals from the adjacent combined sewer outlets and city streets continually add to the nitrogen and phosphate loads in the water as well as oil and dust from the city streets.  Lastly the innocuous-seeming domestic chemicals, from cleaners and solvents we use to wash dishes to the estrogen and caffeine we use in our bodies, can become concentrated here and have huge detrimental effects to amphibious or aquatic life in the canal.

[the molecular structure of PCB's, just one of the toxic residuals often associated with urban industrial canals]

The presence of toxic substances and perceptions and assumptions that come along with those substances are also responsible for creating so many of the opportunities that we find today literally lining these canals.  Because canals are so often spurned, considered outside of the normal urban geography, different people, plants and animals are able to find purchase here.  With regard to the folks hanging out here, one can imagine easily that it is the homeless, the prostitutes, the teenagers skipping school that spend time here.  And they do sometimes.  But you also have many people from surrounding neighborhoods who filter down here looking for a quiet place.  Canoe clubs set up shop in small shacks along their banks, birders come to watch the nighthawks, and rogue gardeners starved for a patch of land come here to find a place of experimentation.  The key in these ongoing activities and the new possibilities the canal creates is limiting and monitoring exposure to the toxic substances.


  1. Following up on my question from the last post, regarding remediation/regularizing.

    It seems that you could de-toxicify a canal and thus allow for other uses/ecologies while not re-mediating to the point where the canal is no longer useful as a canal for shipping/navigation etc...

    Although as this posts makes clear some of the toxicity issues come from the very nature of the canal as a tool of industry. So you would have to create a plan for dealing with canal adjacent built environment/sources.

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