Finding Earth-friendly answers to urban runoff

Anne Arundel Co. using office park to experiment with storm-water control

August 25, 2002|By Jackie Powder | Jackie Powder,SUN STAFF

Four islands of lush, disheveled, green vegetation - and a smattering of black-eyed Susans - sprout from the hot, tarred parking lot of Anne Arundel County's office complex on Riva Road in Annapolis. Not there for aesthetic reasons, the plantings are part of a county experiment to better control the flow of oil- and grease-laden storm-water that runs across the pavement and eventually settles in area waterways.

Called "bioretention areas," the gardens are among a variety of innovative storm-water management methods being tested at the county's 6.5-acre office park. With the installation of a roof garden, sand filters and other "Earth-friendly" techniques, the site has become a demonstration area for practices being promoted by the state to more effectively clean and control runoff.

These techniques are intended to slow gushing water with rocks, plants or sand and capture harmful pollutants from urban runoff before they make their way to streams and tributaries.

"It's a way to better mimic nature's hydrologic cycle by putting water back in the ground and having it slowly infiltrate, rather than piping it to a pond with an outfall," said Ginger Ellis, the county's environmental planning administrator. "This is much more of a vegetative uptake of the rainwater, and the plants themselves process the nutrients for growing and stop them from going into the bay."

Boy Scouts and environmental groups have come to see the county's new runoff-control facilities, and a major hotel chain and a state landscaping association have called county officials with inquiries.

"I think the government can lead by example, and now we've got private industry showing a lot of interest, too," said Greg Stewart, the county's chief of facility engineering.

Such storm-water management facilities have been appearing more frequently around the country over the past decade, mainly at demonstration projects at commercial sites. Proponents say their growth comes from an increasing awareness that conventional storm-water retention ponds are inadequate at trapping pollutants and preventing stream erosion.

"We've become much more sensitive to the impact of urban runoff and have begun looking at better ways to manage it," said Ellis, who pointed out that Prince George's County has been at the forefront of efforts to develop bioretention facilities.

State grants totaling $115,000 helped finance the demonstration storm-water control facilities at the Riva Road complex in Annapolis. The county contributed about $95,000.

The county moved to explore the new techniques at the suggestion of Anne Pearson, director of the Alliance for Sustainable Communities, a nonprofit environmental group based in Edgewater. She got excited about rain gardens - bioretention areas on a smaller scale - at a conference five years ago.

Pearson said it was worth the wait.

In sunken 20-foot-by-20-foot beds, the all-native plantings in the bioretention areas appear to be thriving despite drought conditions. Within a perimeter of debris-catching stones are smartweed, bayberry, river birch and pin oak trees, broome and Joepye weed.

Runoff flows into the bed, where it collects temporarily, then seeps down through layers of mulch, gravel, soil and sand. The gradual absorption allows the ground water and aquifers to recharge, while preventing excessive volumes of untreated water from flowing across the parking lot.

"To me it's a joy because they are blowsy and wild-looking and undisciplined; they look like natural areas," Pearson said.

The areas offer a sharp contrast to rain-starved trees on the parking lot, planted on raised mounds that prevent water from penetrating the soil.

Taking its runoff-control project above ground, the county last month completed the installation of plantings on its "living roof," on top of a small building at the Riva Road complex that houses the county's emergency generators.

The plants will soak up rainwater, reducing the amount that ends up on the parking lot. The roof's insulation properties also provide energy savings that help to offset its additional costs, county officials said.

Creating the living roof involved tearing down the pitched roof and replacing it with a flat one. The drainage system includes sheeting, rubberized asphalt, filter cloth, 3 inches of soil and a woven fabric called a "wind blanket" to keep the soil in place when plants are establishing themselves.

The roof contains about 660 small sedums, low-growing plants that don't require a lot of water. Stewart said the plants have done well.

"We've had record heat and very little rain," he said, "and we're intentionally not watering it to see how it does, and really it's thriving."

The county is proceeding with plans to install similar roofs on three new county buildings - the Southern District police station, the Brooklyn Fire Department and the West County library.

Supporters of the environmentally friendly storm-water management methods hope to see the practices making their way to private homes. But they acknowledge that property owners may need to modify their ideas about landscaping.

"We sculpture the landscape in our own image instead of understanding ... its own natural way of being," Pearson said.

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