Deconstructing Green Infrastructure
By Janice Kaspersen
Although it’s common, even fashionable, to use the word green to apply to almost anything that’s good for—or that isn’t actively harmful to—the environment, the term often has a more specific meaning. Green infrastructure is an approach to managing stormwater that relies on natural processes rather than engineered systems. It’s becoming more widely used in many cities, and, a new report claims, if used in the right way it can save lots of money as well.
We see green infrastructure most often in the form of bioswales or rain gardens, reduction of impervious cover through such means as pervious pavement, green roofs, and sometimes rainwater harvesting systems. The infiltration, evapotranspiration, and reuse that these techniques promote reduces the volume of stormwater runoff and, along with it, the amount of pollutants that need to be treated.
Grey infrastructure, in contrast, is the built system of handling stormwater: the curbs and gutters that direct its flow, the pipes and storm sewers that carry it away, and the treatment plants (for those areas that have combined storm and sanitary sewers) that clean it up.
The report, titled “Banking On Green: A Look At How Green Infrastructure Can Save Municipalities Money And Provide Economic Benefits Community-Wide,” was released in April by American Rivers, the Water Environment Federation, the American Society of Landscape Architects, and ECONorthwest. (You can download it for free at www.americanrivers.org.) Using many examples and data from EPA, FEMA, and the American Society of Landscape Architects, among others, the report shows that green infrastructure saves money in several ways, including avoiding energy expenditures and the costs of flood damage. It can also be much cheaper to rely on green infrastructure to supplement traditional grey infrastructure than to upgrade or replace grey systems. Finally, the report argues, maintaining green may be less expensive than maintaining grey: “Properly functioning green infrastructure practices are premised on using natural processes rather than built systems, which requires a shift away from capital intensive, infrequent maintenance to less-invasive tasks that may be more frequent but less expensive overall.”
The report provides a useful overview of how green infrastructure works and what some of the economic considerations are in implementing it. For those of you who are already doing so, more detailed information will be useful as well. Three of the authors of this report—Jeffrey Odefey of American Rivers, Seth Brown of the Water Environment Federation, and Mark Buckley of ECONorthwest—will be presenting at StormCon in August on the economic benefits of green infrastructure. Several other StormCon presentations will show how green infrastructure has been used in specific locations, either on a small scale—a community park or an auto dismantling operation, for example—or a large one, as in Edmonton, AB, or Gwinnett County, GA. There are also presentations dealing with barriers to accepting and implementing green infrastructure and how those can be overcome, and on modeling the effectiveness of green infrastructure practices. You can find the complete StormCon program at http://www.stormcon.com. Registration for the conference is now open; I hope to see you there this summer.
Janice Kaspersen is the editor of Erosion Control Magazine.