How Philadelphia’s Water Pollution Problems Shaped the City

TTF Admin
Jan 29, 2020

Tacony Creek

How Philadelphia’s Water Pollution Problems Shaped the City

Below is an adapted transcript of the January 27, 2020 interview for Distillations from the Science History Institute with host Lisa Berry Drago and reporters Rigo Hernandez and Sebastian Echeverri. TTF Watershed Partnership’s Executive Director Julie Slavet was interviewed. Rigo came along the Trails Through Time: Discovering Frankford Creek tour in November 2019.

The way the city tackled its water pollution problems has made it an unexpected pioneer.

Philadelphia just had its wettest decade on record, and all that precipitation has wreaked havoc on the city’s waterways. Like most old cities, Philadelphia has a combined sewer system—that is, one pipe is used to carry both sewage and stormwater. When it rains a lot, the system gets overwhelmed, forcing the water department to send raw sewage into rivers and creeks. City officials and engineers knew this was going to be a problem when they built the sewer system in the 1800s. The reason they used a combined system anyway can be best explained by two forces: knowledge ceilings and path dependency. In this episode we explore how the city got to this point and how, in an interesting twist, it led to Philadelphia having one of the most innovative water systems in the country.

Lisa: Hello and welcome to Distillations, a podcast that explores the hilarious, strange, and serious stories at the intersection of science, culture, and history, all powered by the Science History Institute. I’m one of your hosts, Lisa Berry Drago.

Philadelphia is the home of the Distillations podcast. And today our episode is all about the history of water pollution here in Philadelphia. This story is in our backyard, but it also has lessons other cities can learn from—specifically, how to manage your sewers with the threat of climate change looming.

It’s a collaboration with the Philadelphia Inquirer for their “From the Source: Stories of the Delaware River” series.

For this episode we worked with reporter Sebastian Echeverri. Over the summer, he was a AAAS [American Association for the Advancement of Science] fellow at the Philadelphia Inquirer, and he’s going to help us tell the story.

Sebastian: If you’re from Philadelphia, we hope this story will resonate with you because the city was shaped by water, figuratively and literally. So sit tight as we break down three centuries of water pollution history.

So the neighborhood we’re in is Juniata Park. We are sort of above, we’re in the Northeast.

Lisa: In a neighborhood just above Kensington, there’s a creek called Frankford Creek. It runs through a park and golf course. And just at the edge of it there is a giant gate that looks like the entrance to a castle. But it’s more of an exit, and it’s operated by the water department.

Julie: There’s a gate that opens when it overflows. And you know, you can drive a truck through that.

Rigo: You can drive a train through it.

Julie: Yeah. It is really, it is really big.

Sebastian: Julie Slavet is the executive director for the nonprofit Tookany/Tacony-Frankford Watershed Partnership. She works on ways to manage storm overflows in the city. She is worried about what comes out of that gate: raw sewage. There are 164 of those sewage overflows in the city, and this one is one of the biggest.

Julie: What basically goes into this little creek system is like the volume of the Schuylkill River. It’s enormous. I mean, you can see how eroded it is. I wouldn’t want to be standing here. If we were standing here when the combined sewage overflow gate opened, there’s no doubt in my mind that it’s not coming up this high.

Lisa: The Schuylkill River is a 2,000-square-mile river on the west side of the city. It’s pretty big. So when it rains a lot, this area fills with 43 million gallons of foul-smelling sewage, plastic bags, and other debris.

Sebastian: This creek is one of the only recreational spaces for a part of the city that’s very poor. And it might surprise people, even the residents nearby, that this is totally legal and normal.

Julie: It is very likely that when it rains in Philadelphia, there’s combined sewage going into the creek. On average, there’s one combined sewage overflow into this creek once a week. So that’s a lot.

Lisa: What makes it more alarming is that during the last decade, Philadelphia has had the most rain ever on record.

Julie: It’s a really tragic human use of a natural asset. I mean, this is a creek that people should be able to enjoy. And because of the way we’ve developed the city, it is, you know, it’s polluted.

Sebastian: Philadelphia, like most old cities, has what’s known as a combined sewer system. It means that just one pipe carries both stormwater and sewage. So when it rains a lot, that rain can overwhelm the system, and this forces the city to send all that untreated sewage straight to the two rivers that surround it—the Schuylkill on the west and the Delaware on the east.

Lisa: This is somewhat unusual. Many cities get their drinking water from distant places—away from their sewage. New York, for example, gets most of its water from the Catskill Mountains.

Sebastian: The combined sewer was built around the 1860s as a response to typhoid fever. And the interesting thing is that the city knew back then this was going to be a problem, but they did it anyways. They simply didn’t have a better solution.

Alexis Schulman: They truly believed that the diluting powers of the rivers would be adequate to clean, basically still have clean water, be able to use it for the city’s drainage and sewage but not overwhelm their cleansing capacities.

Lisa: That’s Alexis Schulman, she is a fellow at the Academy of Natural Sciences in Philadelphia, and she wrote her dissertation on the history of stormwater management.

Alexis Schulman: You hear about these decisions that were made in the past, like creating a combined sewer, like dumping your sewage into the river, and you think, “God, how stupid.” But in having to go through this full history and understanding what was kind of structuring these decisions made me have a lot more empathy for the decisions. I can see, you know, I could see how that seems totally reasonable.

Sebastian: Why was the city built this way? It’s explained by two hidden forces we are going to talk about in this episode. One is that when anyone, including a city like Philadelphia, is responding to crisis, they have knowledge ceilings. You can only act with the information you have at that moment. And number two is this thing called path dependency. The most eloquent definition we’ve heard of this is, “History matters; what has occurred in the past persists because of resistance to change.”

Alexis Schulman: That’s the idea that preceding steps that we take in a certain direction, well, they incite more movement in that same direction. And it becomes more difficult to change course. So why does that happen? There are lots of different reasons, but one is you have sunk costs. And there’s a lot of uncertainty around that because people have now organized their expectations and their learning and their technologies around that original decision that they made.

Lisa: Probably the most familiar example of this phenomenon is your keyboard. The way it’s laid out,  Q-W-E-R-T-Y. It’s because typewriter makers put distance between the most-used keys so you wouldn’t press them all at once and jam it. There is no reason why we need it on a smartphone, but we still have it. This configuration became the standard. And once it’s locked in, it is extremely difficult, if not impossible, to get out of that path dependency.

Sebastian: We know that having a combined sewer system is a bad idea. And basically the city stuck with it because in time it became almost impossible to break away from it. But in an interesting twist, path dependency is also the reason why Philadelphia was able to build one of the most innovative water systems in the country.

Lisa: Those are not words we are used to hearing: Philadelphia as an innovator in infrastructure. Over the course of this episode we are going to find out just how Philadelphia got to where it is now.

Sebastian: And to see how we started on this path, we need to go back to a time before there even were any sewers. And like most Philadelphia stories from colonial times, it begins with the city’s favorite son, Benjamin Franklin.

Climate Change

Lisa: Philadelphia just had the wettest decade ever. And this only makes the combined sewer problems worse.

Sullivan: If you have a drizzle that happens over eight hours, that’s very different than getting that same volume that happens in half an hour. So it’s really about the intensity of these storms.

Sebastian: That’s Abby Sullivan, with the city’s climate change office.

Sullivan: Climate change is changing the extremes. We already get these intense thunderstorms here in Philadelphia, and it’s making those storms more intense. That has implications for our wastewater treatment plants; it has implications for our entire drainage system; it has implications for flooding, surface flooding.

Lisa: So is the green infrastructure, our sponge, going to be enough to keep up?

Sebastian: The city is currently on year eight of a 25-year agreement with the EPA to reduce these combined sewer overflows. To get there, they are partnering with developers and nonprofits to create rain gardens and other greenery. The nonprofit where Julie, who we talked to at the beginning of this episode, works at is in charge of building some of them.

Julie: We’ve installed, as I said, planted, you know, a couple of thousand trees and shrubs; installed something like seven rain gardens; restored wetlands.

Lisa: Distillations toured a couple of the rain gardens next to Juniata Park. On the surface the rain gardens are basically the size of two parking spots. Our producer Rigo Hernandez actually missed it the first time he visited the park. Each green acre, as they call them, is able to absorb about one million gallons of rainwater a year. The program also takes existing park amenities and gives them a facelift, like a baseball field in Juniata Park.

Rain Garden Tour: Basically, they took this entire baseball field and dug it up. And now underneath that baseball field is the equivalent of about 11 SEPTA buses’ worth of stormwater storage. That rainwater that’s coming from the neighborhood, it now has a place to go before it ever has a chance to go into the stormwater sewer.

Sebastian: Homeowners in Philadelphia can work with the city to build some of this green infrastructure on their property. The city finished more than 150 publicly funded projects, with another 300 in the works. But it can be hard to believe that a few rain gardens here and there are really going to have an impact on this climate change threat.

Alexis Schulman: There’s going to be probably a period of reckoning where they’re going to have to look—and that might be around year 15 just based on saturation level—whether they can look and say, “Okay, our model says this should be working, but are we seeing the on-the-ground reality of that.” And that is coming.

Lisa: What we have learned while doing this story is that the green infrastructure projects will eventually cost more than their original $2.4 billion price tag. And that’s because those rain gardens and green projects have to be maintained in perpetuity. Here’s Julie Slavet again.

Julie: So that’s a challenge for us. We have not yet, I think, gotten to the point where we have felt like the owners have taken a hundred percent responsibility for maintenance. And I don’t think we expected that to happen really quickly. So we visit all our sites; we continue to provide support for them. We make sure that they’re working, and we do as much as we can to get the owners involved in maintenance.

Sebastian: Green infrastructure projects are also controversial within the department. Some engineers want to go back to creating a gray system, basically building those eight-billion-dollar tunnels we were talking about. But that is not a guarantee either.

Lisa: Remember how Chicago was one of the cities that opted to go for the gray system? Their Deep Tunnel, as the project is known, is mostly done. Well, it’s not going according to plan.

Sebastian: Chicago is also dealing with intense storms, and, as it turns out, these storms are way too much to handle by the city’s Deep Tunnel. Once again, officials had to discharge storm runoff and sewage into Lake Michigan.

Lisa: The tunnel isn’t as big as they wanted it to be because they ran out of money. And the city planners didn’t account for these intensifying storms.

Sebastian: What Philadelphia is doing right now is very much an experiment. The city could pivot away from the green infrastructure. Or it could keep going down this new path because of sunk costs; being stuck on paths is kind of what the story is all about.

Julie: I’m from Boston and I’m 61. So I remember a time when the federal government invested in things like this. And I think this is at that level. This is big enough that it deserves federal investment. It’s crazy to me. How else can you do stuff like this?

Lisa: The federal government is not helping Philadelphia pay for these green infrastructure projects. So our city relies on incentivizing developers to build green infrastructure into their projects or to partner with nonprofits like Julie’s.

Sebastian: More than likely the solution for Philadelphia might be to do something that Milwaukee is doing. They built the giant tunnels, but they also built the green infrastructure.

Lisa: Milwaukee now has on average 2.4 sewer overflows a year—compared to Philadelphia’s current once-a-week problem.

Julie: It took a couple a hundred years to make the mess that we made. This is what makes me feel better. So, I think it’s going to take a while to really solve this problem.

Lisa: When it comes to our combined sewer, which is one of the biggest sources of our water pollution now, it’s funny to think that this problem was actually predicted by Benjamin Franklin. He described the situation. He said, when you cover a ground plot with buildings and pavements, it actually will carry off most of the rain and prevent it from soaking into the earth and renewing and purifying the springs. Well, purifying the springs is exactly what Philadelphia is trying to do with those rain gardens.

Sebastian: One of the things that I thought was really interesting is that all the problems that we look back and are like, how did they make that choice? That was ridiculous. We want to think that that’s because we, you know, now are so much smarter than people who were dealing with those problems at the time, but in many of the cases, they kind of knew that there was still a problem. I mean, think of the sewer overflows and the fact that there was a tidal river, the idea of connecting the sewer system to the river, people were talking about at the time saying, “Hey, this doesn’t work. We just don’t have the technology to come up with a better solution.”

So people knew that things were going wrong. It’s just like it is today. We can easily point out how many systems in our lives are broken, but designing something that works is a lot harder than complaining

Lisa: I think we forget that one of the places that innovation can come from is practicality and desperation. Necessity really is the mother of invention in Philadelphia’s case. A lot of the times our problems are, you know, sometimes they’re made worse by the same thing. That eventually helps us find a solution to them.

And in this case, it’s that Philadelphia was such a poor city that we didn’t have the money to throw into a giant infrastructure project. We had to try something like a rain garden, and if that ends up being the best solution that helps us, you know, survive and thrive in climate change. Wow. That’s, we can take the chip on our shoulder and turn it into a crown.

Distillations is more than a podcast. We’re also a multimedia magazine. You can find our podcasts, videos, and stories at, and you can follow the Science History Institute on Facebook, Twitter, and Instagram.

This story was reported by Rigoberto Hernandez and produced by Mariel Carr, Rigoberto Hernandez and myself. The episode was mixed by James Morrison. We want to give a special shout out to the Science History Institute’s Oral History department and the museum team for doing a lot of the research that went into this episode. This includes Rebecca Ortenberg, Christy Schneider, Samantha Blatt, Zack Biro, and Grey Pierce.

For Distillations, I’m Lisa Berry-Drago. Thanks for listening.

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