I read a border-line ridiculous story the other day about a team of highly-specialized scuba divers who were trying to fix a growing leak in a giant water pipe 1,200 ft below the streets of a huge city. The seemingly desperate repair attempt was motivated by the increasing frequency of local flooding and leakage of up to 36 million gallons a day from a pipe supplying half the city’s water.
The basic premise: our team of elite divers uses a diving bell to descend a tunnel all 700 feet (thank god the leak was in a shallow section) to the pipe where they work 12-hour shifts and are kept alive by hoses pumping heated water into their special dive suits as they chip away concrete with their hands in order to expose a broken valve. Then, in their spare time these divers return to the “surface” which for them is a 24-foot tubular pressurized tank containing 97.5% helium and 2.5% oxygen where they relax, watch television, and play nerf-ball. One of the people involved in the operation is an “interpreter” who is highly accomplished at understanding the helium induced squeaks that are these divers’ voices. Seriously? I could have just described a give-me-a-break scene out of an over the top Hollywood Sci-Fi.
Except it wasn’t Sci Fi. This story is a very real in-progress construction project going on in New York City, and the article was run by the New York Times (and it can be found here). It is definite proof that urban infrastructure, particularly the parts you don’t see, is one of the most interesting things we humans have done. I, for one, am fascinated. I enjoyed some militantly back-to-the-earth years during my childhood, when I disdainfully eschewed comfort inducing amenities and, among other things, fought angsty winter climate wars with my parents by placing textbooks and atlases over all our house’s floor heating vents. But even then I was always hopelessly awed by the machines and systems that distribute public utilities. And I still have to stop and watch every time I see crews working on exposed water mains or repairing overhead-wire storm damage.
Unfortunately it can be difficult to run into this stuff in our daily lives. The infrastructure supporting American cities is very tragically behind the scenes. Enter Carleton College, the happy counter to seemingly all real-world glitches. For better or worse there are no 1,200 ft tunnels below Sayles but the Facilities Plant, the large building directly behind the campus center that students hardly ever enter, is an incredible example of what kinds of machines, systems, and thinking go into disseminating to a large group of people most of the amenities that for them have become unconsciously available.
I took my second tour of the plant this afternoon and an overview of its basic operations is enough to make your head whirl. Take temperature control. Carleton has 3 boilers with 3 output capacities: 20,000 lbs steam/hr, 35,000 lbs steam/hr, and 55,000 lbs steam/hr. A boiler runs most efficiently close to its full capacity, so as temperatures fall and rise going in and out of winter facilities switches campus heating between larger and smaller boilers to match required loads. Additionally, during stretches of high demand Xcel Energy occasionally asks Carleton to take its boilers off natural gas heating and transfer to on-site No. 2 fuel. Xcel can ask the same thing for our electric use, for which we do something I’m still a bit fuzzy on, but involves ramping up our production until we reverse flow into Xcel’s grid before quickly switching over to diesel and cutting connection to the incoming Xcel line. Facilities makes all these switches with zero interruption to service. Important? Imagine the general confusion, lost computer data, and subsequent uproar/whining that would result from 5 seconds of campus electricity failure.
Supplying such a large amount of utilities in such eventually small portions, desk lamps, one-room heaters, evening showers, present some of the problems that I find most compelling. There is hot water in both the pipes feeding your shower and your room heating unit but they are, thankfully, not the same temperature. Not only do both temperatures change independently throughout the year, but they are influenced by different factors, including the outdoor temperature, the number of people using your building, and whether or not you are enjoying winter break. These two hot water units have to be individually controlled while, it should be mentioned, never passing through the main boilers. Intensely heating and distributing steam from one very large boiler is far more efficient and cost effective than using many small boilers, but unit heaters using steam are harder to control than those using water. So the steam from the boilers is distributed around campus where it uses coils to heat, to different temperatures, water bound for facets, and room-heaters.
The Facilities Plant contains some machines and piping mazes that no normal person will ever find in their residential house. Like taking little kids to a farm, a walk in there is a great way to demystify where our lighting, and water, and heating, and refrigeration come from and how it gets to us. It disappoints me then that even with people as perpetually interested and “engaged,” as Rob Oden likes to say of Carleton students, so many people here are still so ignorant of what goes on in one of our campus’s own buildings. And it’s fascinating. Facilities is expanding an “Energy Management System” that allows them to take campus schedules and control, from one computer, the temperature of rooms based on when people are in them.
Carleton students tend to be well versed in their disciplines of choice and there have been more than a few times I’ve been overwhelmed while attempting to converse with someone about their major, be it chemistry, physics, philosophy, or economics. But it is another thing all together to stand in the chiller room with loud motors humming through the walls, and listen to Carleton’s Director of Energy Management and Senior Climate Control Manager attempt to explain how they most efficiently run the campus air-conditioning. While they went on and on about 2 and 3-way valves and pressure balancing between buildings, and the cascade of events that happens when someone closes a lab hood, I kept having to ask every 5 minutes “wait, how does an air-conditioner work again?”
If you’ve never looked through the lower windows of the Facilities Plant along Hwy 19 late on a weekday night, I suggest you take a peek next term. And then stay on the lookout for a guided tour of the plant, something that happens on occasion. Because being an educated citizen means more than staying up to date on world politics, and in my opinion the New York Times doesn’t run enough stories about their water mains. Try an exercise, imagine what happens if a steam pipe sprouts a leak while outside temperatures are -5° F, school is in session, and the leak is below the basement of Davis. I’m willing to bet the answer is more interesting than a lot of things you might dream up.