CitiesGoGreen - December 2008 - (Page 21)

Green Infrastructure for Stormwater Management The traditional approach to stormwater is being turned on its head. The new “green infrastructure” approach is to slow down, retain, filter and let water infiltrate as much as possible. Advantages range from healthier streams, rivers, lakes and oceans to fewer overflows, less flooding and lower cost, and more beautiful communities. by Carol Brzozowski A rizona green builder John Wesley Miller is fond of saying most people don’t care about stormwater until they get flooded. Municipalities do care, and are trying to learn how to manage stormwater in sustainable, low-energy, effective ways as they attempt to comply with National Pollutant Discharge Elimination System (NPDES) requirements. In 1972, the Clean Water Act established NPDES, which controls water pollution by regulating point sources that discharge pollutants into United States waters. Phase 1 (1990) addresses municipalities with populations of more than 100,000. Phase 2 (1999) addresses smaller communities and construction activity on one to five acres. “[Stormwater] is the major site issue we are confronted with all over the country,” said Ann Archino Howe, a civil engineer specializing in sustainable site design. “We are looking much more carefully at the long-term effects of development on a particular site, in a particular watershed. What are the watershed’s wide effects on streams, lakes, erosion issues and of sediment being carried from one place to another?” Low Impact Development (LID) According to Larry Coffman, a former regulator and current president of Stormwater Services in Chesapeake Beach, December 2008 Maryland, variance in storm behavior in different regions makes it difficult to apply any single approach everywhere for NPDES Phase II compliance. One commonly applied low-energy approach, however, is Low Impact Development (LID). “[Low Impact Development] boils down to being more aware of how to work with the landscape, to make it work for us instead of against us,” Coffman said. “If you want sustainability, you have to have technology that in some ways mimics natural ecological processes and serves receiving waters and their aquatic resources.” With few exceptions, LID costs are lower than conventional approaches, Coffman says. Howe says sustainable site design is vitally important as more building creates more impervious surfaces, resulting in more flooding events. She strongly favors preserving existing vegetation, which absorbs stormwater through leaves and roots. For example, in one office building project she designed, Howe reduced impervious areas by using grass for the shoulders and reducing the width of the entrance, the parking lot isle and parking space length. Establishing good drainage with grading and enabling water to stay on site for as long as possible before burdening the municipal storm sewer system is key, say builders such as Miller. Green roofs—a tech- Core question How can communities use green infrastructure to manage stormwater and respond to the National Pollutant Discharge Elimination System (NPDES)? Information base The problem Rain from storms (stormwater) runs off impervious surfaces (roofs and pavement) in large volumes and at high speed as it is collected in channels and pipes, causing damage and ultimately polluting surface waters. Many existing municipal systems are unable to handle existing flows, and as developed areas spread, the problem spreads. The National Pollutant Discharge Elimination System is an attempt to respond to this problem. What is the NPDES? The National Pollutant Discharge Elimination System (NPDES) is a US Federal law that grew out of the Clean Water Act of 1972. Its purpose is to decrease water pollution by regulating point sources that discharge pollutants into United States waters. 21 http://citiesgogreen.com/issues/december-2008/features/green-infrastructure-stormwater-management http://citiesgogreen.com/issues/december-2008/features/green-infrastructure-stormwater-management http://cfpub.epa.gov/npdes/ http://citiesgogreen.com

Table of Contents Feed for the Digital Edition of CitiesGoGreen - December 2008

Citites Go Green Contents In Motion We’re Taking Steps 10,000 Rain Gardens in Kansas City Chicago Center for Green Technology Connecticut’s ‘One Thing’ Green Infrastructure for Stormwater Management Philadelphia The Economics of What Matters New Context: New Possibility

CitiesGoGreen - December 2008

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