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The city of Philadelphia has one of the nation's oldest sewage systems; and like many cities around the country, Philadelphia's sewerage can fill up pretty quickly in a rainstorm, leading to flooding and other problems. The city's water department is working on an ambitious plan to change the way water flows through Philadelphia streets.
Brad Linder reports.
BRAD LINDER: Howard Neukrug is standing on an asphalt basketball court in West Philadelphia, but Neukrug isn't here to play. The director of Philadelphia's Office of Watersheds is holding a one-gallon jug of water, which he proceeds to pour onto the middle of the court. At first it puddles, as you'd expect a normal pavement but then...
Mr. HOWARD NEUKRUG (Director, Office of Watersheds, Philadelphia Water Department): You can see in the middle there it's starting to sink in like a sponge into the ground. So it removes the water rather than letting the water puddle and sit there for hours and hours or days and days. The water is going down into a gravel bed underneath here and then eventually infiltrating into the ground water for West Philadelphia.
LINDER: What Neukrug is looking at is porous pavement. Watershed's Program Manager Joanne Dahme says it starts out like any other pavement material. But manufacture doesn't add in the fine particles and binders that make normal pavement waterproof.
Ms. JOANNE DAHME (Program Manager, Office of Watersheds, Philadelphia Water Department): Although looking at it they look like regular asphalt or regular concrete, when you see the rainfall settle on it, you see it quickly disappear. So it's almost like a sand covering that's taking the rain into it and allowing it to go back into the earth.
LINDER: It should cost about the same to produce porous pavement as regular asphalt, but since there's not much demand for the porous surfacing factories have to shut down and reset their machines, which adds to the price. Still, Philadelphia officials think it's worth the money because porous pavement helps with the annoying byproduct of urban life - flooding.
As cities like Philadelphia grows, so do their problems with flooding. Temple University Professor Jeff Featherstone says that's because there aren't enough natural areas to slowly absorb rainwater into the ground.
Professor JEFF FEATHERSTONE (Director, Center for Sustainable Communities, Temple University): You're short-circuiting that natural process. And water hits an impervious surface like a roof or a street or a parking lot and immediately gets discharged off to either a water body or some sort of a storm water facility.
LINDER: That means when it rains, a massive amount of water flows directly into the Schuylkill and Delaware Rivers and their tributaries, causing them to flood more frequently. But even when they don't flood, that runoff picks up a lot of pollutants on its way to the city's drinking water supply.
Ms. DAHME: (Unintelligible) is like fecal bacteria from animal waste.
LINDER: The Philadelphia Water Department's Joanne Dahme.
Ms. DAHME: You know, when have storm water runoff, it's picking up with the animals or doing their business on the ground. Periodically, you might have some problems in our sewer systems; they might be what we call like a choke, where you might have some sewage come periodically. So mostly it's that sort of bacteria, the fecal bacterias, what we're looking at.
LINDER: The city has tools besides porous pavement. One neighborhood school, for example, has a rain garden which collects water dropping from the school's roof in a natural setting. In another neighborhood, the city helps establish an urban farm to accomplish a similar goal. Of course, city-owned property is just a drop in a bucket.
Back at the refinished basketball court, Watershed's Director Howard Neukrug says in the next year the city will only be able to reduce about one percent of Philadelphia's runoff. The city is also offering private developer's incentives to use environmentally friendly design. Neukrug says the larger goal is to use city construction projects to show developers how to better manage storm water.
Mr. NEUKRUG: If you change one basketball court or two basketball courts, it's nice and it does something good for the community but it doesn't change the world, it doesn't change the environment. By demonstrating that this works on a basketball court, and we can do that all over Philadelphia, then you start to make a change.
LINDER: Neukrug says in another 10 to 20 years the city will have environmentally friendly storm water systems at all its rec centers, basketball courts and other public properties. And there's another benefit - the local kids who play on the court said that as soon as it stops raining, the new pavement's drying up to allow them to shoot hoops. Last year they would have had to sweep the water off the court before they could play.
For NPR News, I'm Brad Linder.
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