https://penntoday.upenn.edu/news/keeping-rain-out-drain

Shoemaker Green, three acres of green space on Penn’s campus, is more than just a nice place to have lunch. Formerly home to tennis courts, the space was revamped in 2012 and now includes garden beds with native plantings, benches, and shaded walkways.

But all that conceals what is perhaps the most unusual facet of the Green—an underground cistern capable of holding 20,000 gallons of water.

The site represents one example of how the University is increasingly incorporating design features into campus buildings and landscapes to manage stormwater. From green roofs and rain gardens to buried storage tanks and water-reuse systems, Penn is playing a leading role in the city’s efforts to keep runoff from overwhelming the sewer system. All significant new building projects at Penn are designed to meet the Philadelphia Water Department goal of managing the first inch and a half of rain that falls on impervious surfaces. 

“That means that the first inch and a half of water that falls from the sky literally can’t go down the drain as runoff,” says Bob Lundgren, Penn’s landscape architect. “That regulation dictates how we do a lot of projects here. We do green roofs, we do cisterns, we do permeable paving, so the rain can soak into Mother Earth or sit somewhere and then drain slowly or be reused.”