State Will Require Rain Gardens for Healthier Water
New Washington State Department of Ecology rules released yesterday will require that new development and redevelopment projects include Low Impact Development (LID) practices to manage stormwater runoff – including the use of rain gardens and pervious pavement.
The requirements are aimed at reducing and managing pollution, and will include a monitoring component. These LID practices deal with stormwater where it lands, reducing the pollution that runs off into Puget Sound waters, and reducing the burden on the (aging) stormwater management system. In the long-run these practices should be cheaper and simpler than trying to increase capacity and treatment further down the line.
The state Stormwater Management Manual for Western Washington (SWMMWW) was last updated in 2005. 2012 updates reflect more recent scientific learning and new Best Management Practices, as well as changes in permit requirements at the federal level.
The new rules will take effect in Tacoma, Seattle, and surrounding areas by June 2015, lower density communities in 2016, and Eastern Washington in 2017.
These changes come as Tacoma prepares to kick off work on the Pacific Avenue Streetscape project, which will include rain gardens; and not that long after Clay Huntington Way at Cheney Stadium received Green Roads Certification in recognition of the project’s use of pervious pavement, among other environmentally friendly practices.
So, are you ready for more rain gardens?
Read more from the Department of Ecology (pdf).
Filed under: green-tacoma, legislation
1 comments
M Michael Mirra August 5, 2012
A requirement for “rain gardens” can make a lot of sense. At the Tacoma Housing Authority, we learned about rain gardens when we designed and built New Salisan starting more than 10 years ago. An important part of its design are its “bioinfiltration swales”. (Rain gardens, the new term, does seem more friendly.) They are a reason for many of the design awards that New Salishan won.
They are designed to keep 91% of the rain water that falls onto Salishan on site soaking into the ground so it never gets to the City’s storm water system and therefore never gets to Commencement Bay, or if the rain water does get there it is cleansed by the filtering action of the ground soil. This is important because an important environmental challenge around here is Commencement Bay and Puget Sound. A main problem is urban and agricultural run off. Rain gardens can help to reduce urban run off.
At Salishan I had some initial worries about rain gardens. My first concern was that I thought of them as experimental. Our engineers assured us, however, that it was a well understood technology. I must note though that when we got it built all these other engineers from around the country visited to see how it was done. That makes me wonder how well understood it was at the time. (I think it was understood well enough but Salishan was noteable mainly because of its scale. Nearly 200 urban acres may have been one of the largest uses of rain gardens.) My second concern arose from my imagination of seeing white water washing two year olds down the street. Yet, I have been at Salishan during the heaviest rain and the design really does work to capture, direct, slow and absorb the water. My last concern pertains to maintenance. Rain gardens are essentially engineered ditches with carefully layered soils, native vegetation and rocks. You have to teach people, especially children, to keep out of the rain gardens. This can be hard. There is not a 10 year old on the face of the earth who is satisfied with the arrangement of rocks he finds.
All in all, rain gardens have been a very good experience for us at New Salishan. We are pleased to model the technology starting 10 years ago. I also note that the rain gardens have become an attractive part of the landscape adding a lushness that we think is very appealling.
Michael Mirra
Executive Director
Tacoma Housing Authority