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KEEPING POLLUTION OUT OF RIVERS, BAY

March 11, 2007 12:36 am

By RUSTY DENNEN

As land in the Fredericksburg area is draped with asphalt and rooftops, less water is seeping into the ground.

When it rains, ever-increasing amounts of pollution-laden water and soil wind up in storm drains, running into the Rappahannock and Potomac rivers.

What if more of that water went back into the ground? What if engineers could reinvent the natural process by which a forest sucks up vast amounts of water while filtering out contaminants that harm the rivers and the Chesapeake Bay?

That's the aim of a growing movement called low-impact development that is changing the face of some of the largest commercial building projects in the Fredericksburg area.

"The whole idea is to distribute stormwater across a site at its source," says John Tippett, executive director of Friends of the Rappahannock. The Fredericksburg-based group has been instrumental in getting developers and localities to use LID methods.

Ponds and pipes used to be the way stormwater was handled on most commercial development sites.

That's a problem for the Rappahannock and the Potomac, because the water is laden with petroleum byproducts toxic to marine life, and nutrients such as phosphorus and potassium, considered the most serious threats to the bay.

The new approach leaves or creates green areas and adds bioretention cells--layers of mulch, soil and gravel--beneath them so that water soaks in rather than running off.

"You can remove up to 95 percent of the [fuel byproducts] coming off parking lots, and they are far better than conventional [holding] ponds at removing pollution," Tippett said, because the water filters into--not across--the landscape.

The improvements also address sediment piling up in the Rappahannock.

"These biofilters get at that problem because they function as giant sponges. With less erosion you have clearer water, and you help restore underwater grasses. "

The concept was first tested here in Central Park, the Silver Cos.' megadevelopment off State Route 3 on the western edge of Fredericksburg, in the late 1990s.

Chuck E. Cheese's, for example, has a bioretention cell lined with trees to catch runoff from the parking lot.

Tippett knows it's working.

"The trees there must be twice the size" of others planted around parking lots elsewhere in the development, he said. Their roots take up excess nutrients and water that would have gone into streams.

"That's what LID is all about."

Stafford County is on the cutting edge of low-impact development.

The county worked with Friends of the Rappahannock, the U.S. Army Corps of Engineers and developers to rewrite its ordinances to require LID components for parking lots and encourage them in most other developments.

Stafford is the only area locality, and one of only a handful in Virginia, with such environment-friendly provisions in force.

Stafford started looking at LID in 2000, and added suggested guidelines on water quality, nutrients and runoff three years later, said Steven Hubble, environmental division manager in Stafford's Department of Code Administration.

"In 2004, we took it a step further and changed the code to require that LID be evaluated for new development projects," he said. It doesn't mean developers must incorporate LID strategies in their plans, but that they must consider them.

The process begins with site design, Hubble said.

With a subdivision, for example, "You try to look at reducing the amount of impervious area, keeping native vegetation in place, reducing the amount of land cleared, and leaving good soils [that drain well] in place rather than building on them."

After the site design, "It gives us a baseline for what additional facilities need to be put in place to comply with stormwater requirements," Hubble said.

According to a recent article in Stormwater, the journal for water-quality professionals, Stafford "is a great example of the public and private sectors working together toward a common goal."

"Developers nationwide are often interested in using LID techniques but quickly become turned off by the increased delays imposed on them for trying to do something good for the environment," Rich Dooley, a member of the National Association of Homebuilders' Research Center in Maryland, wrote.

Planners, he added, "have the chance to play a key role in creating the flexibility needed" to encourage the use of LID.

Meanwhile, Friends of the Rappahannock has been working to institutionalize LID planning in local ordinances. The town of Warsaw in the Northern Neck now has it, and Fredericksburg has asked for assistance in adding code provisions. Spotsylvania encourages, but does not require, developers to incorporate the techniques in their projects.

"We've had a lot more step up to volunteer to do LID," said Richard Street, a Spotsylvania environmental engineer. "I would say a good 80 [percent] to 90 percent are doing some form of it," he said--three to four times as many as just a few years ago.

Friends of the Rappahannock developed a LID tutorial and tool-kit CD, which has been distributed nationally. In 2004, it pioneered an approach to prioritizing sites for LID projects using computer mapping.

It's not just a state and local issue. The Environmental Protection Agency mandates that impacts of stormwater on wetlands and streams be reduced in projects requiring federal permits.

The Corps of Engineers recently held four public workshops in Virginia on proposed new regulations that would require consideration of LID practices in the agency's review of development projects.

"We can seek less-damaging alternatives, and LID is one of those tools," said Hal Wiggins, field biologist for the Corps' Fredericksburg office.

Rusty Dennen: 540/374-5431
Email: rdennen@freelancestar.com