Asphalted land, noted Everett, a Rowan professor of civil and environmental engineering, is typically just drained by a storm sewer at a low corner of a lot.
The water from a rainstorm collects there and is moved underground through pipes into a stream or river - in this case Chestnut Creek, then onward to Mantua Creek, and eventually to the Delaware River.
The problems with that, Everett said, are myriad.
The water contains pollutants from cars - oil drippings, chemicals off tires - and the surge that comes from the pipes during a rainstorm can cause "flash," as in flash flooding, suddenly accelerating the stream flow.
"If you are an organism or a fish in that stream, that means you can get a load of sludge on you or be pushed along too swiftly and could die," he said. "It is just not ecologically sound."
For students such as senior Brett Hoffmann of Colonia, N.J., the project has been a semester-long hands-on class. They have been helping Princeton Hydro measure water tables, determine proper gradings for drainage ditches, and plant vegetation that includes switch grasses, purple-cone flowers, hibiscus, black-eyed Susans, and asters.
"All these plants are suited for the environment," Hoffmann said.
It is not quite what a student of civil engineering, who might prefer building highways or skyscrapers, expects in a practicum, he said, "but it is really beneficial to getting the environment healthy."
The plantings are primarily inside newly created medians in the parking lots. These rain gardens' job is to intercept rainwater and let it slowly percolate into the ground rather than flood and run off into storm sewers.
The sides of the medians bank into a ditch in the middle that, Everett said, has to be about two feet above groundwater level.
While storm sewers remain, the gardens also receive some of the flow off the paved surfaces via curb cuts.
"That just mitigates the chance for flash in the eventual streams," said Craig McGee, watershed project director for the Camden County Soil Conservation District.
With its counterpart in Gloucester County, McGee's outfit is working with a $330,000 grant from the state Department of Environmental Protection for the half-acre project in the lots just west of Wacker Stadium and smaller ones near flood-prone sidewalks around campus.
McGee said the project next will convert a 12-acre field near Twin Ponds, along Cross Keys Road in Washington Township, into something both functional and beautiful.
"Instead of turf grass, you will have natural grasses and wildflowers. It will take the pressure off the flooding of the roads there. You won't have to mow it every two weeks. And it will be beautiful scenery in an otherwise rapidly developing area."
McGee said he hopes to get more state grants for these types of rain gardens as well as to encourage businesses and office parks to retrofit, as Rowan is doing.
"It is inexpensive, it looks good, and it helps the water environment all at once - a win-win-win, I like to say," McGee said.
Adds Emerson: "You'll think we did this just for the looks, but in reality it is both a learning experience for future civil engineers that creating something 'green' doesn't have to be huge, and will have an important impact on water, a valuable resource, for a long time."