Is Philadelphia’s new sewer plan the solution to America’s storm water problem? The federal government is giving Engineering Professor Arthur McGarity’s team $1 million to find out.
McGarity, who heard the news when camping in East Texas, is leading an Environmental Protection Agency (EPA)-financed team of researchers that will try to assess the effectiveness of a new “green” approach to water management.
Since 1972’s Clean Water Act, the federal government has put increasing pressure on states to update their inefficient sewer systems. Many cities, like Washington D.C., have responded with so-called “grey” infrastructure to deal with the surplus water. “Grey” infrastructure involves putting elaborate tunnels and pipes underground to redirect excess water. Implementing “grey” infrastructure, however, is expensive and disruptive to cities.
So the City of Philadelphia has come up with what it believes is a more efficient plan: the “green” approach. It involves catching rainfall before it enters the sewers, relieving some of the burden on the underground sewers and lowering the risk of overflow. Though the technology has existed for a while, nobody has tried implementing it in an entire city.
“It’s cutting-edge, [which is] unusual to come out of Pennsylvania,” McGarity said.
The “GreenPhilly” research team is composed of Environmental Studies Professor Megan Heckert, faculty from other universities, and Swarthmore students. The team will examine both the technical and community effects of the plan. If they find Philadelphia’s plan to be workable, it might inspire the “green” approach’s nationwide adoption.
“A significant amount hinges on its success because [Philadelphia is] really the first city that’s trying to take this approach,” Heckert said.
Until now, Philly’s sewer system has been concerned with absorbing as much water as possible and getting it out of the city, re-using only a fraction of it. The current combined-sewer system does not differentiate between rainfall and human-produced wastewater. Heavy rainfall overwhelms it, and it is often forced to spill its contents into rivers and creeks, causing pollution. Much of this system is outdated and inefficient.
“Infrastructure underground tends to not be seen, and so it can easily become out of date. Out of sight, out of mind,” McGarity said.
One of the reasons no city has tried the green approach, even though it is cheaper than the “grey” approach, is that its effectiveness has yet to be determined.
“The EPA sort of went out on a limb, I think, to accept this. Because it’s not been proven,” McGarity said.
The purely technical aspect of the green approach is relatively well-understood: storm water, once contained, can go either up or down. “Up” means it is evapo-transpired through vegetation, while “down” means it is seeped into the ground. McGarity has dealt with these technologies before, right here at Swarthmore. So the question becomes how well this technology will fare on a massive, urban scale.
“It’s definitely not clear whether these projects are going to prevent overflow,” student researcher Laura Laderman ‘14 said. Laderman is working with Heckert, who focuses on the community aspect of the research.
Studying the communities the project will impact is vital, as much of the technology’s implementation will have to be done by private landowners. Though an engineer himself, McGarity understands that there is more to the project than engineering.
“The engineering alone is not gonna be enough to make something like this work. You need to understand the people and the communities that they come from, and not all communities are the same. […] The more you get to know Philadelphia the more you realize that it’s a consortium of neighborhoods rather than a city,” McGarity said.
Featured image taken by LoriHorwedel//Flickr.