The New Explorers. Series III; No. 303; The Great Chicago Flood

<v Bill Kurtis>You won't find many cities without a river. <v Bill Kurtis>Chicago is prettier than most. <v Bill Kurtis>We take it for granted. Cross it without thinking. <v Bill Kurtis>Throw things into it. It'll always be there. <v Bill Kurtis>Always has. <v Bill Kurtis>But in a few hours, this river, this beauty will take a sharp turn <v Bill Kurtis>and make the city on its banks promise never to take the river for granted <v Bill Kurtis>again. <v Speaker>[intro theme music plays] <v TV Announcer>Major funding for The New Explorers is provided by Amoco: celebrating

<v TV Announcer>the adventure of scientific discovery for the year 2000 and beyond. <v TV Announcer>Additional funding is made possible by Waste Management Inc., providing recycling <v TV Announcer>and other waste services around the world. <v TV Announcer>And by Duracell embracing the power of science education, <v TV Announcer>the source of future technology and innovative growth. <v TV Announcer>Duracell, the copper top battery. <v Bill Kurtis>Hello, I'm Bill Kurtis. This old tunnel plays a major role in this episode <v Bill Kurtis>of The New Explorers and so does mathematics. <v Bill Kurtis>Math is the language of engineers. <v Bill Kurtis>It's the perfect tool to explore nature. <v Bill Kurtis>It's the measurement of space and quantity. <v Bill Kurtis>We don't think of it like that to most of us. <v Bill Kurtis>It's something you get through in school. <v Bill Kurtis>That's why it may come as a shock that in this recreation of a major disaster, <v Bill Kurtis>math is the hero. <v Bill Kurtis>We do want to caution our more sensitive young viewers. <v Bill Kurtis>What you're about to see is a real-life application of algebra

<v Bill Kurtis>and geometry that works. <v Bill Kurtis>The city's just waking up. <v Bill Kurtis>Like a great stadium waiting for the games to begin. <v Bill Kurtis>It's the calm before the storm. <v Bill Kurtis>Giant department stores prepare for the rush. <v Bill Kurtis>This is the miracle of the industrial age. <v Bill Kurtis>In just a few hours, 1 million workers will fill 12 square blocks <v Bill Kurtis>and empty them 8 hours later.

<v Bill Kurtis>Like a huge organism coming to life, the river of workers will need <v Bill Kurtis>flowers. Magazines. <v Bill Kurtis>Coffee - ehm make that coffee and donuts. <v Bill Kurtis>A shine for the meeting. <v Bill Kurtis>Light on the signs. <v Bill Kurtis>Candy for the boss. <v Bill Kurtis>Gonna buy low today, sell high. <v Speaker>[yelling in background] <v Bill Kurtis>Ehm - scratch the candy. <v Bill Kurtis>A million jobs. <v Bill Kurtis>A million chores. Walking. <v Bill Kurtis>Riding. <v Bill Kurtis>Talking. [phone rings] Calling. <v Bill Kurtis>Hitting. <v Bill Kurtis>Not knowing that this morning, April 13th, 1992, <v Bill Kurtis>something is different.

<v Speaker>[fire truck honks and blares siren] <v Bill Kurtis>The Chicago Fire Department gets the first call. <v Bill Kurtis>Merchandise Mart. Water is pouring into a sub basement. <v Bill Kurtis>Several blocks away, another basement. More water. <v Bill Kurtis>There's been no rain. Where's it coming from? <v Bill Kurtis>There is a clue. <v Bill Kurtis>Under an old bridge, city workers see a small whirlpool in the river. <v Bill Kurtis>What could it mean? <v Bill Kurtis>By 9:30, city engineers are on the bridge. <v Bill Kurtis>Only the old-timers can guess what happened. <v Bill Kurtis>They know about the catacombs of freight tunnels that burrow beneath the buildings built <v Bill Kurtis>to carry coal on small railways. <v Bill Kurtis>They were abandoned 35 years ago. <v Bill Kurtis>But if something punctured 1 directly beneath the river. <v Bill Kurtis>Right now, that's only a nightmarish scenario.

<v Bill Kurtis>The only thing the giant businesses know for sure is that the water is rising dangerously <v Bill Kurtis>fast. <v Bill Kurtis>Marshall Fields. <v Daniel Skoda>There's 3 subbasements, okay? 1 of 'em's totally underwater, the second one is partially <v Daniel Skoda>underwater. <v Bill Kurtis>The county building. <v County Building Spokesperson>So the second basement of the county building, as well as the third basement, are totally <v County Building Spokesperson>underwater. <v Bill Kurtis>Similar reports are coming in throughout the 12 square blocks. <v Bill Kurtis>The loop is flooding. <v Bill Kurtis>City hall. <v Speaker>[background chatter] <v Bill Kurtis>The media wants answers. What's happening to the city? <v Mayor>Well, we are working with the gas company, uh the Bell Telephone Commonwealth <v Mayor>Edison working with the CTA, everybody involved in it. <v Mayor>And we're still working with them now. <v Bill Kurtis>Without even knowing the precise cause yet, the mayor must take action. <v Bill Kurtis>It will be 1 of the most difficult decisions he will ever make. <v Bill Kurtis>The mayor's fire superintendent.

<v Superintendent>Our recommendation is that anybody who would have a problem walking down the stairs <v Superintendent>be immediately evacuated via an elevator. <v Mayor>Within the hour. <v Reporter>They said they have an hour-. <v Superintendent>They've got approximately an hour to do that. <v Bill Kurtis>So it began. <v Bill Kurtis>A disaster no one ever imagined. <v Police Officer>?inaudible? You've got Madison. <v Bill Kurtis>It was closing 1 of the world's great workplaces. <v Man>Jefferson Park will be in the center there, ma'am. <v Bill Kurtis>It was systematically shutting down.

<v Bill Kurtis>The tunnels are filling up. <v Bill Kurtis>There's no end in sight. In fact, no one is quite sure yet just what happened, <v Bill Kurtis>but they have to start somewhere to try to stop it. <v Bill Kurtis>The whirlpool is the best clue they have. <v Bill Kurtis>5 months earlier, pilings were placed around a support structure of the bridge to protect <v Bill Kurtis>it from boats coming up and down the river. <v Bill Kurtis>1 of the pilings had apparently penetrated an old freight tunnel running underneath the <v Bill Kurtis>river. A team of cable television installers had even seen it and <v Bill Kurtis>videotaped it sticking right through the concrete. <v Bill Kurtis>Apparently, pressure from the river had gradually eaten away the mud and blasted through <v Bill Kurtis>the hole. From that point, it was 40 miles of open tunnels leading <v Bill Kurtis>right into the heart of the loop. <v Bill Kurtis>Knowing the problem was just the first step.

<v Bill Kurtis>How do you stop it? <v Bill Kurtis>All kinds of suggestions were coming in. <v Bill Kurtis>Throw mattresses in like they did in submarines during World War 2 to stop leaks, but <v Bill Kurtis>they probably wouldn't seal well. <v Bill Kurtis>Push stones over it, but it was soon clear it would take too long. <v Bill Kurtis>65 truckloads of material would be dumped, but the flooding continued. <v Bill Kurtis>It was a war zone. Heavy equipment, sandbags at the ready. <v Speaker>[background chatter] <v Bill Kurtis>A chaotic scene. And in the middle of it all, a need for answers quick <v Bill Kurtis>and accurate. <v Reporter>What's your main concern right now, Mr. Mayor? <v Mayor>The flow of water going in. <v Bill Kurtis>The Army Corps of Engineers worked quietly through the night at a temporary command post <v Bill Kurtis>near the site of the breach. <v Speaker>[background chatter] <v Bill Kurtis>The engineers knew they would be asked for the answers. <v Bill Kurtis>Everything they had learned would be needed with no mistakes.

<v Bill Kurtis>A city was at stake. <v Engineer 1>Work out the options [fade out] <v Bill Kurtis>As minds focused for answers, it became clear that an unlikely hero would emerge. <v Bill Kurtis>The answer needed to save the city was an algebra equation. <v Engineer 2>So what's the surface elevation? <v Bill Kurtis>First problem, stop the leak. <v Bill Kurtis>Chester Szmurlo is the structural engineer assigned the task of designing a plug of some <v Bill Kurtis>kind that will hold back the Chicago River. <v Bill Kurtis>First, he has to calculate the amount of force that's coming through the leak. <v Bill Kurtis>That's what his plug will have to resist. <v Bill Kurtis>But before he can find that force, Chester must first calculate the hydrostatic pressure <v Bill Kurtis>with the pressure water exerts at the site of the proposed plug. <v Chester Szmurlo>To calculate that is just a simple formula here. <v Chester Szmurlo>P equals Gamma D where P is hydrostatic pressure. <v Chester Szmurlo>Gamma is just the constant for water at 62 pounds per <v Chester Szmurlo>cubic foot and D the depth at which the pressure is.

<v Chester Szmurlo>We've got the top of the tunnel here and we can see - that's 28 feet below <v Chester Szmurlo>the river- the river height. <v Chester Szmurlo>So that corresponds to a uh water pressure of 1740 <v Chester Szmurlo>pounds per square foot. <v Bill Kurtis>Now- <v Chester Szmurlo>That's simply the 62 pounds per cubic foot of water times the 28 foot <v Chester Szmurlo>depth. <v Bill Kurtis>I see you performed the same calculation for the 35 foot depth, <v Bill Kurtis>which is 2200 pounds. <v Chester Szmurlo>Exactly. <v Bill Kurtis>And I presume that you take an average of those. <v Chester Szmurlo>You got it. So that's about a ton for every square foot of concrete area. <v Bill Kurtis>1 ton. That's a lot. Suddenly you have a problem on your hands. <v Chester Szmurlo>We- we- we knew we had a problem, yeah. <v Bill Kurtis>Applied to the flood it works like this. <v Bill Kurtis>Water weighs 62 pounds per cubic foot. <v Bill Kurtis>We know it's 28 feet from the surface of the river to the top of the tunnel and 35 <v Bill Kurtis>feet to the tunnel floor. <v Bill Kurtis>By multiplying each depth by 62 pounds and then averaging those <v Bill Kurtis>2 numbers, we can determine the pressure that will apply to every square foot

<v Bill Kurtis>of a plug. <v Bill Kurtis>So how many square feet do we have? <v Chester Szmurlo>We've got plans and drawings and that tells us we have this sort of a cross section. <v Chester Szmurlo>This is what it actually is. <v Chester Szmurlo>We can approximate it, just make it a rectangle. <v Bill Kurtis>About 7 feet higher by 6 and a half feet wide. <v Chester Szmurlo>Yeah. And we just multiply the width times the height. <v Bill Kurtis>7 and a half times 6 and a half. <v Chester Szmurlo>That's right. And we got 48 square feet, say 50 square feet. <v Bill Kurtis>Okay. <v Chester Szmurlo>So to find out what the force is now, we know how much pressure there is against every <v Chester Szmurlo>square foot. We know how many square feet we have. <v Chester Szmurlo>So to get the total force that the hydrostatic pressure is pushing up against with the <v Chester Szmurlo>plug, we just multiply it out and we get just <v Chester Szmurlo>about 100000 pounds of force against our plug. <v Bill Kurtis>That seems incredible to me. <v Bill Kurtis>Now, all we have to do is find something that could hold back 100000 <v Bill Kurtis>pounds of force. <v Bill Kurtis>Hours seem to rush by like seconds.

<v Bill Kurtis>Days pass. <v Bill Kurtis>The mayor breaks the news to businessmen. <v Bill Kurtis>There is progress, but it's slow and it's not what they want to hear. <v Reporter>Do you feel better after this meeting about what's going on out there? <v Businessman>I feel warm and fuzzy, but I still- I'm still not in business. <v Bill Kurtis>The city's beginning to worry about disease from the dirty river water. <v Bill Kurtis>Workers line up for hepatitis and tetanus shots. <v Patient>I hate shots. <v Doctor>Me too. [laughs] <v Bill Kurtis>The subways are closed. <v Bill Kurtis>Many businesses already struggling in a weak economy are told they must remain <v Bill Kurtis>closed during the flood repair and cleanup operations. <v Bill Kurtis>Some will never reopen. <v Bill Kurtis>The Board of Trade is where the real pressure is. <v Bill Kurtis>It's still closed.

<v Bill Kurtis>If the rest of the world can't trade here, they'll go somewhere else. <v Bill Kurtis>But deep beneath the trading pits, there are unseen problems, when water <v Bill Kurtis>meets electricity, the power that drives the city. <v Businessman>Uh the second basement has a transformer in it that's partially underwater. <v Businessman>And that's what's steaming. That's what Commonwealth Edison has to shut off before it <v Businessman>blows. <v Bill Kurtis>That's the fear. Commonwealth Edison crews must work round the clock to preempt <v Bill Kurtis>the danger. <v Commonwealth Edison Representative>Currents flowing between the bars, boiling the water. <v Commonwealth Edison Representative>Uh and our fear is if failures begin occurring, <v Commonwealth Edison Representative>we may have failure of the electric equipment that's submersed in the water, and these <v Commonwealth Edison Representative>customers that we're taking out of service now intentionally will be knocked out of <v Commonwealth Edison Representative>service with no warning. <v Bill Kurtis>Fish are showing up in the state office building. <v Bill Kurtis>Everyone wants to get back to normal, but it takes time. <v Woman Outside Building>I need to see IDs! <v Bill Kurtis>There is one more fear that makes the sound of a clock [bell tolls] seem like it's moving

<v Bill Kurtis>the city toward an approaching waterfall. <v Bill Kurtis>Engineers know the river water is leaking out of the tunnels, saturating the foundations <v Bill Kurtis>of buildings throughout the loop. <v Engineer 1>Our deep spots right now are really adjacent to the uh canal system linked to <v Engineer 1>um the Chicago River here. <v Speaker>[background chatter] <v Bill Kurtis>If it continues, or if the engineers drain the water out of the tunnels too fast, <v Bill Kurtis>well, it's another worry for Army Corps of Engineers chief hydraulic engineer Tom <v Bill Kurtis>Fogarty. <v Bill Kurtis>What's the problem that you're facing? <v Bill Kurtis>What do you have to worry about? <v Tom Fogerty>When you flood the basements like it's shown in this diagram, you also <v Tom Fogerty>will have water in the ground area behind the basement. <v Tom Fogerty>So if you draw the basements down very quickly, you'll cause a lot of hydrostatic <v Tom Fogerty>pressure against the walls. <v Bill Kurtis>So the pressure is coming this way and you- <v Tom Fogerty>Right. <v Bill Kurtis>Collapse the basement walls. <v Tom Fogerty>Right. As a matter of fact, we went out and we surveyed 20 or so <v Tom Fogerty>the more important buildings in downtown Chicago, for example, the Monadnock and the Art

<v Tom Fogerty>Institute. And we surveyed those buildings to make sure that the foundations weren't <v Tom Fogerty>shifting and there wouldn't be cracking in the foundations. <v Bill Kurtis>Foundations of some of the tallest buildings in the world. <v Bill Kurtis>Tom Fogarty will work on that problem while construction crews try to make Chet's algebra <v Bill Kurtis>equation a reality. <v Bill Kurtis>They're drilling shafts down to the freight tunnel on either side of the leak. <v Speaker>[construction noises] <v Bill Kurtis>The crews are working 24-hour shifts. <v Bill Kurtis>Before they can build a plug, they've got to slow the water rushing in. <v Bill Kurtis>They'll do that with sandbags and small stones.

<v Bill Kurtis>Divers become the eyes of the engineers, checking the tunnels for further damage <v Bill Kurtis>and seeing that the sandbags and gravel have succeeded in slowing the flow through the <v Bill Kurtis>tunnels. <v Bill Kurtis>1 diver comes up and another goes down. <v Diver>Okay, I'm going down. Ah you can go ahead and turn the light on. <v Diver Guide>Light's coming on. <v Diver>Okay, I'm going down. Can kind of see the wall there but- Okay, I'm on the bottom <v Diver>uh ?inaudible? down here and check it out. See what we got. <v Diver Guide>Right now you're at 31 feet, roger that? <v Diver>Roger that. It <v Diver>actually feels pretty good. <v Diver>Right, the water's real murky 'cause it's river water. <v Diver>It's all muddy. It's stirred up a lot because they're pumping all the time.

<v Diver>It doesn't have a chance to settle. So you have to grope in the dark with your fingers. <v Bill Kurtis>Team plug is working around the clock, too. <v Bill Kurtis>And finally, they think they have the answer. <v Chester Szmurlo>So what's going to happen is we've got a concrete plug here. <v Chester Szmurlo>Now, if this concrete plug is going to fail from the hydrostatic force, what'll happen is <v Chester Szmurlo>this concrete would crack at this- between the stem and the plug itself. <v Chester Szmurlo>And this plug would try and slide. <v Bill Kurtis>Right. But it would push it- <v Chester Szmurlo>The hydrostatic force. Exactly, right. We don't want it to crack and have the plug slide <v Chester Szmurlo>on us. <v Bill Kurtis>So in reality, it's this circular shaft of concrete that must hold against the water <v Bill Kurtis>pressure. And that calls for more math. <v Chester Szmurlo>This shaft is round. It was a 5 foot diameter hole that was drilled through <v Chester Szmurlo>the street 50 feet down into the tunnel roof. <v Bill Kurtis> So the shaft area equals pi times-. <v Chester Szmurlo>R squared. <v Bill Kurtis>The radius squared. <v Chester Szmurlo>The radius squared. Exactly. We've got a 5 foot diameter, so it's a 2 and a half foot

<v Chester Szmurlo>radius. <v Bill Kurtis>Working through our equation, multiplying pi or 3.14 times <v Bill Kurtis>2 and a half feet squared gives us the cross-sectional area of the shaft. <v Bill Kurtis>Which is 2826 square inches. <v Chester Szmurlo>Right. That's how many little square inches we've got in this circular cross-section. <v Chester Szmurlo>Now we have to find out what the capacity of the concrete is or how much resistance <v Chester Szmurlo>we can get out of each square inch of concrete that we have available to us. <v Bill Kurtis>That textbook gives us that answer: a constant for the compressive strength of this <v Bill Kurtis>concrete. <v Bill Kurtis>You don't want to make this too easy. <v Chester Szmurlo>That's right. <v Bill Kurtis>So your sheer resistance as you plug that in, trying to find it, <v Bill Kurtis>again, a mathematical equation that you simply go back to your <v Bill Kurtis>grade school math. <v Chester Szmurlo>That's right. That's right. We know how much force, how much resistance each square inch <v Chester Szmurlo>of concrete has. We know how many square inches of concrete-. <v Bill Kurtis>We have. <v Bill Kurtis>Are available. So you multiply them together and we come up with 107000 <v Bill Kurtis>pounds of resistance.

<v Chester Szmurlo>Terrific. So that's more than 100000 pounds per square foot. <v Chester Szmurlo>You just saved the city. <v Bill Kurtis>Of hydrostatic pressure. That's great. I just saved it. <v Bill Kurtis>[both laugh] <v Bill Kurtis>Well, not quite. They've still got to get the concrete to hold in the rushing water. <v Bill Kurtis>With police escort, the new concrete is rushed to the bridge. <v Bill Kurtis>For good measure, they'll include a steel bearing pile to double the resistance strength <v Bill Kurtis>of the plug. <v Bill Kurtis>It seemed as if the whole world was watching and hoping, <v Bill Kurtis>as the crews once again worked into the night. <v Bill Kurtis>Slowly the whirlpool shrank until it was hardly a ripple in <v Bill Kurtis>the river. <v Mayor>Today, I'm very pleased to report that we appear to have passed in the first major <v Mayor>technical hurdle in this complex situation.

<v Mayor>The tunnel appears to have been plugged on both sides of the leak, and <v Mayor>hopefully we can now turn our attention to the process of draining the <v Mayor>water from the system. <v Bill Kurtis>But it raises another question. Where do you put 131 million gallons <v Bill Kurtis>of water? <v Bill Kurtis>Fortunately, the answer was just a few feet away in the form of giant underground <v Bill Kurtis>tunnels dug originally to handle the excess water from rains so it wouldn't pollute <v Bill Kurtis>Lake Michigan, an incredibly valuable source of freshwater. <v Bill Kurtis>So here are the freight tunnels that are running underneath the skyscrapers, all the <v Bill Kurtis>buildings here in the loop. Here is the flooded basement. <v Bill Kurtis>So the water would come down into the tunnel, be pumped <v Bill Kurtis>up onto the street level and then over to where you can have access down <v Bill Kurtis>into the deep tunnel to carry it away. <v Tom Fogerty>Right. And then all of this water is carried to a water reclamation plant for treatment. <v Bill Kurtis>To maintain the safe speed of dewatering, the Corps, working with the Chicago Fire <v Bill Kurtis>Department, sets up monitoring units throughout the flooded business area.

<v Tom Fogerty>Adams, Monroe, Madison, LaSalle. <v Bill Kurtis>You're able to see just exactly where that water is going and how fast it's going <v Bill Kurtis>down at all these locations. <v Tom Fogerty>Right. <v Bill Kurtis>Then they begin to slowly pump the water out of the tunnels, past the monitoring <v Bill Kurtis>points and into the deep tunnel. <v Bill Kurtis>The monitors in turn relay data back to the Corps officers. <v Bill Kurtis>Tom Fogarty will interpret the data and adjust the pumps to reach the agreed safe rate of <v Bill Kurtis>pumping. <v Tom Fogerty>The rate that we wanted to dewater that was about 3 inches an hour, <v Tom Fogerty>and we decided pretty much that we wanted to keep within that limit. <v Bill Kurtis>It is agonizingly slow. <v Bill Kurtis>For over a month, they match the level of water in the system to their pumps, speeding up <v Bill Kurtis>or slowing down in response to the conditions in the tunnels. <v Bill Kurtis>When enough water was pumped out, they could see that the tunnels were undamaged

<v Bill Kurtis>and Chet's plug was holding solid, exactly as calculated on paper. <v Bill Kurtis>It was a big victory for engineers, contractors, <v Bill Kurtis>divers, concrete, and steel and basic algebra. <v Bill Kurtis>Math worked. <v Bill Kurtis>No one died, then no one was injured. <v Bill Kurtis>But the great Chicago Flood wreaked havoc on one of the great cities of the world. <v Bill Kurtis>The financial losses from damage, construction, repairs, and lost revenues <v Bill Kurtis>are estimated to have exceeded a billion dollars. <v Bill Kurtis>The city of Chicago constructed a system of permanent concrete bulkheads to assure that <v Bill Kurtis>it won't happen again here. <v Bill Kurtis>But... <v Mayor>If you don't rebuild the infrastructure, this is going to happen all over the country. <v Mayor>It is inevit- in every city. <v Mayor>Whether it's tunnels, whether it's bridges, whether it's roads.

<v Mayor>It's happening every day. Our infrastructure is getting older and older. <v Bill Kurtis>A million people came back on their commuter trains. <v Bill Kurtis>Merchandise was moving again. <v Bill Kurtis>The financial traders were shouting with their old gusto. <v Bill Kurtis>Their computers glowed beneath the shower of paper. <v Bill Kurtis>The disaster had passed. <v Bill Kurtis>Whoever would have thought that algebra does have life after high school. <v TV Announcer>Major funding for the new explorers is provided by Amoco, celebrating

<v TV Announcer>the adventure of scientific discovery for the year 2000 and beyond. <v TV Announcer>Additional funding is made possible by Waste Management Inc., providing <v TV Announcer>recycling and other waste services around the world, and by Duracell, <v TV Announcer>embracing the power of science education, the source of future technology and <v TV Announcer>innovative growth. Duracell, the copper top battery. <v TV Announcer 2>A videocassette and accompanying teacher's guide are available for each episode of The <v TV Announcer 2>New Explorers. To Order, call 1 800 621 0660, or write The <v TV Announcer 2>New Explorers, 1 5 1 8 1, Route 58, South, Oberlin, Ohio, <v TV Announcer 2>4 4 0 7 4. <v PBS Announcer>This is PBS.