New Trend In Urban Development: Clean Up Water Pollution
By ROBERT McCLURE
The fastest-growing water pollution threat in my region – and probably in yours, too – is stormwater, that filthy mixture that results when rain or melting snow washes away oil, antifreeze, dog poop, fertilizer, pesticide and anything else on the ground. It is truly foul stuff.
All that ends up somewhere. Usually, that's your nearest stream, wetland or bay. And the rainwater running off streets and other hard surfaces tends to come in big surges that gouge out stream bottoms.
It doesn't have to be that way, a growing number of scientists are saying. But are their ideas for "low impact development" being held back by your local building official? It's more common that you might think, and could make for a good story almost anywhere.
It might not be the sexiest topic – but low-impact development is one of the top ways, if not the top way, officials could control water pollution in your area.
"Everybody likes the idea in principle. It's like motherhood – who could object?" said Bruce K. Ferguson, Franklin professor of landscape architecture at the University of Georgia. "Getting specific new technologies accepted by the people who have to pass off on these things is another story. There's some guy sitting at a desk in the bureaucracy who has to give approval to this thing from a technical viewpoint."
The techniques are proven, say Ferguson and other LID experts – they're just not the way we've always done things. Ferguson said the Pacific Northwest is a national leader in employing low-impact development techniques, although you can find examples in any region.
You will have an opportunity to write about this when a National Academy of Sciences panel currently studying the situation issues its report. The report, "Reducing Stormwater Discharge Contributions to Water Pollution," is due out in the late fall. For more information go to http://tinyurl.com/2tw2jk.
The basic principle is to catch as much rain as possible before it hits the ground, in the tree canopy, then get as much as possible of what does hit the ground to percolate rather than run off toward the nearest stream or bay.
But that's not the way our cities have been built. Nor is it the way the suburbs spreading across the countryside are being constructed. Stormwater experts say solving the problem is going to mean employing LID techniques both in new subdivisions as they sprout and in already-built areas when properties are redeveloped.
Here in the Pacific Northwest, I've been amazed at the lack of progress in this direction when I see sites that employ LID – because, what's not to like? You get lush vegetation in swales at the side of a shady yard.
You can still have your patio or deck and other so-called "impervious" surfaces that don't let water soak in. You can still have a driveway. You just build the driveway out of porous pavement – Ferguson's specialty – and direct the runoff from the patio toward a "rain garden," what Curtis Hinman calls the "workhorse of the low-impact development approach. " "These techniques can add to the aesthetics of individual yards . . . add to an urban landscape vegetation and all the pleasing things that come along with vegetation in a built environment," said Hinman, a watershed ecologist with Washington State University.
Environmentalists are pushing a legal case in Washington to force the state to require developers to use these methods, citing Clean Water Act requirements to use "all known, available and reasonable technology" to the "maximum extent practicable." If they succeed, similar requirements could pass elsewhere.
The big ding on LID is cost. But evidence presented in the Washington case showed that with LID, developers can actually save money in some instances.
Here's how: Many current building codes contemplate funneling stormwater at a new development into big detention ponds. Those ponds supposedly gulp up a torrent of stormwater during the rainstorm, let pollutants settle out, and then trickle out clean water on the lower end in the days to come. But, increasingly, it's apparent this doesn't work very well.
If each property instead employed lowimpact techniques sufficient to catch all the rain falling on that property, there would be no need for ponds. That leaves room for more houses – and more profit.
In any case, it's not uniformly true the LID has to cost more, says the Low Impact Development Center, Inc., in Beltsville, MD: "This may or may not be true, depending on the experience of the project consultants and contractors with these new techniques and the receptiveness of local government officials to innovative practices. These potential cost increases are not indictments of the concept of LID but of inexperienced institutions, individuals, and bureaucracies that remain unaware of the great necessity for and benefits of a new approach."
Features of low-impact development:
Porous pavement. It soaks up the rain. See http://www.toolbase.org/Technology-Inventory/Sitework/ permeable-pavement and http://www.stormcon.com/sw_0305_porous.html
Maximum retention of native vegetation. Also, rain gardens and other forms of biorention. See http://www.dof.virginia.gov/rfb/rain-gardens.shtml and http://www.fhwa.dot.gov/environment/ ultraurb/3fs3.htm
Green roofs: Vegetation on the rooftop soaks up runoff. See http://www.greenroofs.org/
Soil amendments. To ensure water can soak in. Many lawns are just about as bad for generating runoff as paved areas. See http://www.lid-stormwater.net/soilamend_construct.htm
Resources on stormwater and low-impact development:
"New stormwater rules can produce a flood of stories," Summer 2002 SEJournal, http://www.sejarchive.org/site/sejournal/past/ sej_su02.pdf (see page 14).
Low Impact Development Center, Beltsville, MD: http://www.lid-stormwater.net/background. htm . Phone 301-982-5559
U.S. Environmental Protection Agency: http://www.epa.gov/nps/lid/
LID for big box retailers: http://lowimpactdevelopment. org/bigbox/
Robert McClure covers environmental news in the Pacific Northwest, where it rains a lot, for the Seattle Post-Intelligencer. His blog is www.datelineearth.com.
** From SEJ's quarterly newsletter SEJournal, Summer 2008