Silos, Skyways, and a Damn Fine Skyline
I found a slice of Minnesota in Chicago, and it is 120 feet over the polluted urban landscape,atop the former Santa Fe grain elevator on the Chicago River.
Although the view of the skyline is what enchants me, I doubt that’s what the engineers had in mind in 1905 when the facility became operational.
Chances are, they were just trying to keep the damn thing from blowing up.
In September of that year, the original Santa Fe elevator experienced a fiery chain reaction explosion that led to an inextinguishable conflagration and company loss of half a million dollars. Months later, across a ship loading slip a few hundred feet from the ruins of its predecessor; a new concrete elevator was being built with the most modern fireproofing equipment available.
Knowing how grain particles react to heat, they’d need to take every precaution.
Grain explosions are as old as the invention of mechanical grain processing, the fine particles being relatively inert in a pile, but volatile if suspended in air. If heat causes a cloud of grain dust to combust, flames will leap from particle to particle in an extremely fast and destructive way, often resulting in loss of life. Santa Fe’s 7 inch thick reinforced concrete walls would do little to contain or even muffle such a powerful combustion. Although they’ve gotten their fair share of facelifts in the 105 years since they were molded.
The original 35 concrete grain silos are still standing as they were built: 80 feet high with an inside diameter of 23 feet. Multiply-out those statistics and you get a respectable 1,000,000 bushels of grain storage. The concrete was poured into giant wooden molds laced with three-quarter and half inch reinforcing rods, each giant wire not shorter than 12 feet; a recipe for strength and durability. After the silos were molded to the specified height, a cupola was added on top with a feature that surprised me–one that I will return to later.
Two steel skyways still link this cluster of crumbling concrete bins to the working house on the edge of the Chicago River and its active barge channel, for which the working house has been outfitted with a steel straw, attached to a winch and conveyor belt to load ships and barges alongside the elevator. Skyways were one of the strategies Santa Fe used to fireproof the site, the hope being that if the grain elevator caught on fire, it wouldn’t spread to the working house or vice versa.
However, this elevator’s skyways boast another feature to isolate potential blazes: heat-activated metal guillotines that would crash down on the conveyor belt transporting product from the grain dryer (the most common place for fires to start) and the silos. These devices and its big brother, the counterweighted sliding fire door, still extant and in many cases appear to be operational, even today!
Unfortunately the powerhouse and its 165 foot-tall smokestack are no longer with us, with its 1,500 horsepower engines and twin 750 gallon-per-minute fire pumps. With the help of that plant, the original 225 foot-long wooden working house could load and unload 10 ships at a time; over 75,000 bushes hourly. This wooden working house was built as a temporary solution because a steel shortage at the time stalled construction of a more fireproof, concrete counterpart. After the steel arrived, however, what a magnificent grain elevator they built–and I like to consider myself a sort of aficionado, having toured more than thirty of them.
I have to say, this one surprised me from the beginning by its unique design.
Perhaps the most distinctive feature was one that I alluded to before, in the cupola house over the 1905 silo cluster: open-top silos. I had encountered a similar layout in Minneapolis’ Spencer Kellogg & Sons Elevator in which a single concrete catwalk traces the insides of the silos about ten feet below the rim of the tube, but that functionality was missing in this Chicago complex. At Santa Fe, a mesmerizing pattern of four crisscrossing walkways are suspended above the rims of the silos like an afterthought. There are no caps on the open bins and heavy steel ladders grant access to the bottom for those afflicted with daredevil syndrome, which I am not, so I contented myself with documenting the boundaries of the various walkways.
Chicago’s Goodbye Wave: A Shifting Pile of Bricks
My newfound friend, “The Windy City,” was blowing hard when I left Santa Fe’s embrace, history, and amazing skyline view. What an explosion hasn’t done, nature is accomplishing in its slow, wet green way. Until some other century, or some enterprising developer, ultimately levels this unofficial historical site, it will remind us that the city of glass and steel beyond itself would never have developed if it wasn’t for wood and concrete.