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Kaid Benfield’s Blog

Green infrastructure in smart growth, beautifully illustrated

Kaid Benfield

Posted July 13, 2009

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My NRDC colleague Rachel Sohmer has produced a wonderful slide show illustrating how low-impact-development techniques for reducing stormwater runoff (sometimes called "green infrastructure") can successfully be integrated into the kinds of smart, urban environments that we need to revive cities and enable walkable, transit-oriented transportation patterns.  (Rachel last appeared on this site writing about a related topic, the importance of neighborhood streets that connect with each other.)  The slide show is below, but first let me set the context.

Sometimes well-intentioned bureaucrats do all the wrong things while trying to protect watersheds.  As I've written before, the biggest mistake is to look at the problem on a site-by-site basis, on the assumption that reducing runoff on each site, (photo of polluted runoff from roadway)generally by reducing on-site impervious surface, will collectively add up to reduced runoff in the watershed as a whole.  (This may be what the Commonwealth of Virginia, for example, is now attempting to do with new regulatory guidance.)

Unfortunately, it doesn't work that way: if builders respond to regulatory initiatives by reducing the development footprint on each site, the effect is to reduce average per-acre density, which has the unintended effect of spreading more, not less, impervious surface (generally in the form of pavement for public roads, for driveways, and for parking lots) around the watershed.  EPA research demonstrates that density - even though it may increase imperviousness on local sites - actually reduces runoff in the watershed as a whole.

So we absolutely need compact development, not large lots, to protect our waterways.  But how do we do our best to soften the localized impacts of density and deal with the stormwater that runs off of dense urban sites?  Pictures are worth thousands of words, and that's where the slideshow comes in.  Enjoy:


For more on low-impact development, see this introduction prepared by NRDC's water program.

Kaid Benfield writes (almost) daily about community, development, and the environment.  For more posts, see his blog's home page. 


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Kaid @ NRDCJul 13 2009 03:16 PM

A brief follow-up on High Point, which is featured in the slideshow: SvR Design Company, an integrated services firm that specializes in innovative and sustainable solutions, was a major player in that neighborhood's success.

Tony Dollar of SvR reports that his firm served as the landscape architects and civil engineers for the planning and design of the natural drainage/low impact development/site green infrastructure features at High Point. The majority of this work was accomplished for the City of Seattle’s Seattle Public Utilities. SvR worked, and continues to work, at High Point executing these technologies and proving to the world that you can do both—density and environmental responsibility. Nice work, guys.

Dan StaleyJul 13 2009 08:43 PM

Me, someone from SvR, and some other folks hope to expand on this and other GI topics in Seattle this coming February [ 9th Annual New Partners for Smart Growth Conference ] in a panel discussion entitled "Increasing Green Infrastructure in Compact Development: Techniques and Experience for Effective Implementation".


Kaid @ NRDCJul 13 2009 11:52 PM

That's terrific, Dan - the topic certainly is due.

On a different note, I want to clarify a point that was misunderstood by at least one person who contacted me offline. I am not opposed to all site-by-site regulation of stormwater runoff. My beef is with regulation that does not differentiate between the sorts of dense, urban sites that on a per capita basis are preferable for the watershed and sprawling sites that are horrible for it. I also have a problem with regulation that focuses on residential and commercial sites while ignoring the infrastructure necessary to serve them.

My correspondent was absolutely corrent in pointing out that our regulatory tools are imperfect but we need to work with them. A way that we desperately need to improve them is to ask more in the way of stormwater control from sprawl than we do from smart growth. A number of states, including West Virginia and Tennessee, seem to be moving in that direction. Environmentalists should support that trend, while asking that all sites do their fair share in contributing to the health of the watershed.

Dan StaleyJul 14 2009 12:27 PM

Regulation is a tool, not the be-all and end-all. I despair when I speak to well-meaning folk who think that if only there could be a crafting of the perfect policy, all would be solved...if only...

Nonetheless, it is a long row to hoe. Relaying the wide range of benefits of GI - psychosocial, economic, environmental, public health, etc in my view is the way to approach it.


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