The Credits Explorer app lets commercial property owners virtually design green infrastructure. Implementing green roofs, rain gardens and permeable pavement reduces runoff and their stormwater fee.


In Philadelphia, a new app is helping commercial property owners reduce stormwater runoff — and save money. 

Last summer, the city launched the Credits Explorer app, which lets property owners virtually add green stormwater infrastructure and calculate fee-based savings. The Philadelphia Water Department, which is trying to reduce stormwater runoff citywide, is hoping property owners then install similar green infrastructure on their properties. If so, a credit will appear on a customer's monthly stormwater bill.

“Our hope is that it raises awareness,” says Erin Williams, an engineer and stormwater initiatives manager for the Philadelphia Water Department. “It’s extending our outreach, allowing us to be more visible and teaching people about stormwater in Philadelphia. It's also getting people on board to manage stormwater to help us meet water quality goals and regulations.”

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Philadelphia’s Green City, Clean Waters program is a 25-year, $2.5 billion plan. The city spends $110 million each year managing stormwater, and it retrieves all that money from stormwater fees.

Commercial property owners interested in trying the Credits Explorer app can visit the city’s website to find their parcel on a map. After selecting the parcel, site users receive a stormwater analysis. The app shows the gross area and impervious areas of the parcel, as well as estimated monthly fees for stormwater runoff. By clicking on “Explore Stormwater Tools,” users can add a virtual green roof, rain garden or permeable pavement. Once a specific upgrade is selected and sized, the app shows the square footage of green infrastructure, and calculates a new stormwater fee based on a reduction in the percentage of impervious area.

“I think it’s such a valuable tool to let folks actually experience what a designer would look at — just try to think how these projects really impact their property,” says Tiffany Ledesma, a member of the city’s stormwater management outreach team. “It’s not like a game, but it almost feels that way, because you’re playing around with your property. It just adds an element of fun and just brings people in and brings them back. We’re really excited about pushing it and promoting it right now.”

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Williams encourages owners to play around with the app, draw a rain garden and see how their monthly bill drops.

“If they like what they see, they like the savings, they like how the rain garden looks and they like what they learned about it, then I’d love for them to call us up and say, ‘Hey, what’s my next step? I want to do this,'” says Williams, who calls the app very user-friendly.

Designing the app was a multiyear process. In 2010, the Philadelphia Water Department moved to a property-based fee for stormwater, which was a service charge on each commercial property owner’s monthly bill.

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“We wanted to make it more visible to our customers and really put value to stormwater, which is really critical for us with our Green City, Clean Waters plan, and all the other work we’re doing in terms of stormwater management,” Williams says.

The Philadelphia Water Department began itemizing stormwater fees on its bills and also started charging companies based on property characteristics. Owners pay stormwater fees based on property size and how much impervious area they have. With the hike in fees, property owners were informed they could reduce stormwater fees by adding green infrastructure.

The Philadelphia Water Department came up with the idea for an app and implemented it in 2010-11.

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“That’s a very baseline application where customers can go and type in their address or water account number and literally look up their property on the map and see what their stormwater fees are, which is extremely helpful,” Williams says. “But a lot of our customers were asking for more information. What about your credits program? I see my property on your app here, but what if I were to put in a green roof or rain garden? What would that do for my property in terms of how it works, how it takes the stormwater and how would that impact my bill with a credit?”

The Credits Explorer app was born, and it has helped alleviate a lot of extra legwork in the water department. When commercial property owners had questions on how much savings they could get by going green, they would call the department. An employee would then have to manually figure out the calculations.

With the app, owners can dabble with green infrastructure and calculate their savings within minutes.

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Williams says the city doesn’t currently track how many users have used the app. However, within the city’s Green City, Clean Waters plan, the city has established five-year incremental benchmarks. The city measures its achievements by green acres — 1 inch of stormwater over an acre of impervious land. The city’s five-year benchmark for stormwater runoff is 744 green acres. In 10 years, that figure jumps to about 2,100 acres.

It’s also too early for the city to gauge how effective the app has been in reducing stormwater runoff.

The Philadelphia Water Department has received extremely positive feedback thus far from owners who have tried Credits Explorer.

“I have probably worked with hundreds of commercial property owners since 2010, and it’s been an interesting experience,” Williams says. “I’ll say some business owners, they’re in this strictly to save money. If they see the credit at the end of the day, they see money they can save on a monthly basis. If that’s the only reason they want to participate in this program, it is what it is. We’ll take it. When we work with those businesses that not only do it for the credits but also do it for the green aspect, I’ll say that there’s been a good number of business owners that have told me firsthand, ‘I don’t see why you’d say no. My property’s getting beautified, I’m helping to make the water better in Philadelphia and I can save money.’”


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