The Great Chicago Flood of April, 1992

Among the oddest disasters recorded is The Great Chicago Flood (a/k/a Great Chicago Leak) of 1992 which nearly inundated and brought the Windy City to a virtual stop by an onrushing tide which most Chicagoans never actually saw.

First, a Little Background Music

Lurking approximately 40 feet under Chicago's surface is a complex system of freight tunnels built by the Illinois Tunnel Company between 1899 and 1906, designed to connect the deep sub-basements of Loop buildings. The tunnels measure 6 feet wide x 7-1/2 feet high and originally housed not only telephone cables but also two-foot gauge mine type electric railways, 149 four-wheeled electric locomotives and over 3,000 freight cars used to transport coal and ashes to and from various buildings. This underground network alleviated traffic flow in the streets above so successfully and economically that ultimately 62 miles of tunnels were extended to buildings on almost every Loop block and even under the Chicago River in places. After trucking companies took over deliveries and coal-burning furnaces were replaced with oil heat, what was then known as the Chicago Tunnel Company went bankrupt in 1956 and was formally abandoned in 1959. In most cases, the tunnels were left as they were - spooky subterranean reminders of the past but now mostly used to house television cables and other equipment.

In September of 1991, contractors from the Great Lakes Dredge & Dock Company installing new wooden pilings into the river bed next to the Kinzie Street drawbridge unwittingly drove one into the wrong place, puncturing the ceiling of a freight tunnel below and creating a slow leak which became readily apparent a few months later when cable television employees discovered and videotaped mud and water oozing in. Though this was brought to the attention of the City, some powers-that-be were reluctant to foot the bill for necessary repairs which could have been achieved with relative ease at that point. Weeks went by as, unbeknownst to Mayor Daley, bureaucratic apathy set in and the underground tunnels filled up with river water.

April 13th, 1992

At 5:57 a.m., a building engineer at the Merchandise Mart discovered water flooding the third sub-basement of the building, an onrushing tide gaining speed and momentum which spilled into other Loop basements, filling them rapidly sometimes to a depth of 40 feet. No one was spared as harassed employees at Marshall Field's and the Art Institute scrambled to rescue couturier bridal gowns and priceless paintings. At least 230 buildings lost power as water threatened their underground power sources. Trials were postponed at the Daley Center, City and County buildings as valuable government records were threatened by water running amuck. Loop banks, the Chicago Mercantile Exchange, and the Chicago Board of Trade were forced to close, at a staggering cost which included the loss of an estimated $25 billion in trading on products handled by the C.B.O.T.

At first, diehard Midwestern optimism carried the day as it was assumed that the worst problem to be dealt with was a broken water main. The sight of bewildered fish swimming around in flooded basements soon marked "Paid" to that feeble hope but it would take a while for anyone to realize that the passage of time and ongoing neglect had transformed the original freight tunnel leak into a hole the size of a large automobile formed in the bottom of the river and through the tunnel ceiling ... a rupture admitting 250 million gallons of water which had filled not only the tunnels but were now gaining rapidly on the basements the tunnels were still connected to.

The self-proclaimed "City that Works" staggered a bit as some businesses switched over to disaster recovery plans and temporary bases of operations in other parts of the state and 200,000 Loop employees had to be evacuated sometimes for weeks, some without pay. Those able to report to work the next day in buildings relatively unaffected by the flood had all they could do to commute to and from their jobs because the subways and CTA underground lines had been closed down by the water. A general state of confusion and uncertainly took over for a while and Kurt Kamin, Chairman of Rodman & Renshaw Capital Group, probably spoke for a lot of Chicagoans when he said: "What contingency plan? We had no plan. We had to work from the seat of our pants."

Usually in a flood, the tide crests at a certain level and begins to recede, allowing repairs and restorations to begin but the Great Chicago Flood was like a vast overflowing bathtub with a tap that could not be turned off. The river itself was feeding the disaster and the end was not in sight as the water rose higher and higher. Before anything constructive could be done, the leak had to be repaired or at least plugged. Panicky desperation accounts for early measures taken to achieve this, employing materials such as sandbags, broken concrete, mattresses, and 3-inch gravel all dumped into the yawning riverbed hole to no lasting effect. By early afternoon, cooler heads had prevailed as the Army Corps of Engineers lowered the level of the river to curb the pressure of the water while other crews constructed a circular dike to protect the site as contractors pumped quick-drying, non-shrinking, hydraulic concrete into the hole.

Even then, the battle was only half won because the flooded basements had to be drained with care and in an orderly manner so that water descending too rapidly wouldn't drag along vital substructure parts with it. Where to PUT all that water and how to handle it efficiently was another problem. The successful resolution of all this was a stroke of genius borne of desperation -- deep under the city and its freight tunnels was the Deep Tunnel, a vast conduit extending 250 feet down which had been dug a decade before in a forward-thinking move for the express purpose of managing the disposal of flood water. Now Chicago Water Reclamation District officials located a place where a flooded freight tunnel crossed over the Deep Tunnel and a drop shaft was dug to allow several workers to descend about 100 feet down and begin drilling small holes about (four to six inches wide) that would allow water to slowly drain from the freight tunnel system into the Deep Tunnel. Sump pumps syphoned off the rest through canvas hoses dragged over pavement and curbs into a separate city sewer system.

Nothing quite like it had ever happened before. In a matter of hours, a virtual tidal wave had run amuck, largely unseen by most Chicagoans, through their major metropolis at the cost of billions of dollars worth of damage but without inflicting a single injury or loss of human life. It all brought to mind the famous Chinese curse: "May you live in interesting times." Before the Windy City had returned to normal, one thing a lot of damp, exhausted people could agree on was that the Great Chicago Flood had been really interesting.

Sources:

Flooding Fiasco in Downtown Chicago ... -- Ray Hanania, Houston Chronicle
Underground Flood Hits Chicago's Loop ... -- Disaster Recovery Journal
Instrumentation Related to Tunnel Flooding -- WJE Company Report
Odd Disaster Turns Loop into a Soggy Ghost Town -- Patrick T. Reardon, Chgo. Trib., Apr. 13, 1992
Chicago Tunnel Company, Wikipedia
That 'Wet Street' Goes with the Flow -- William Gruber, Chgo. Trib., Apr. 15, 1992
Court Limits Chicago's Liability in 1992 Downtown Flood -- Andrew Fegelman, Chgo. Trib., Dec. 30, 1995