December 17, 2009 — Biofiltration is cleansing runoff in the University of Virginia's award-winning stormwater management system.
The system is designed to slow stormwater surges in Meadow Creek as it flows into the Dell Pond, and along the way it filters the water, traps sediment and reduces the amount of runoff that goes into the Rivanna River system. Students monitoring the stream have found reduced levels of phosphates and sediment and low levels of nitrates, all indicators of improved water quality.
The University's Office of Environmental Health and Safety, and later environmental science students, have been testing the water quality in Meadow Creek and the Dell Pond since 2006. In the beginning the monitoring was done quarterly, and then students began monitoring during storms.
"We had more than 20 storms over an 18-month period," environmental sciences professor Janet Herman said. "The students were out there when it was cold, dark and wet."
The spring-fed Meadow Creek starts atop Observatory Hill and flows into the Rivanna River near the Meadowcreek Golf Course. Since the 1950s, a large section of the creek on Grounds had run underground in a pipe. It channeled storm runoff from a large area of west Grounds. In 2004, sections of the creek were brought to the surface and the Dell Pond was constructed as part of the U.Va. stormwater management master plan.
"Daylighting the creek allows the water to run slower," said Jeff Sitler, a hydrogeologist and the environmental compliance manager with the Office of Environmental Health and Safety. "It meanders in a more natural channel, with vegetation along the edges to capture the sediment."
Mary Hughes, the University's landscape architect and an early proponent of bringing the stream to the surface, said that, at the time, the University was doing something new.
"The techniques used were innovative," she said. "There was not a lot of documentation on something like this, but the idea was that taking the water and putting it back on the surface, exposing it to light and air, would improve the quality."
She said between the Office of Environmental Health and Safety and the work of the students, a sizeable database of information has been established on the system.
The site of the Dell Pond, near the tennis courts by Ruffner Hall on Emmet Street, had been a marshy area, but now is a biofilter with native plantings. The pond receives storm runoff and retains it, allowing the water level to rise up its natural slopes, then slowly releasing the water once it reaches a certain level. This prevents rapid runoff and allows sediment to settle.
"It looks like normal landscaping, but it cleanses runoff," Hughes said.
She said has seen fish in the pond and the stream, which she called "evidence of a thriving natural system."
The students have also benefited from their work with the pond and stream.
"A lot of research takes place far away," Herman said. "This is the only environmental science research being conducted on Grounds, so it is possible to involve students to do things in between classes. They have relatively easy access to a research opportunity."
Michael Downey, a third-year student majoring in environmental thought and practice and anthropology, has applied for a Harrison Undergraduate Research Award based on some of the work he has been doing with the Dell Pond.
The research also shapes student attitudes toward the pond.
"For most of our peers it's a nice little pond," said Kate Abshire, a fourth-year environmental science student. "A lot of them are surprised when I tell them that it serves a purpose."
Both environmental science and engineering students work at the water monitoring.
"There is not much opportunity for environmental science students to interact with engineers, and vice versa," Herman said. "They can appreciate each other's perspective."
"I have developed relationships with professors that would not have otherwise happened," said Nathan Farrar, a third-year environmental science student.
The undergraduates have also had chances to present their research at professional conferences, Herman said.
"We have never before made a presentation with only undergraduate researchers," Herman said. "This is a notable accomplishment for them."
Working with the pond helps the students appreciate it more.
"I feel a greater sense of ownership," said Abshire, who added that she enjoys watching ducks that land on the pond. "I explain to the other student that the pond and the ducks are a community resource."