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Earth & Sky :More Info About Natural Drainage Page 4 of 9 slowly. But they've found that these are very ineffective just because of the size of [the ponds], the fact that they're rarely maintained, and It's a very centralized way to manage the storm water. So we pretty much took an idea that we've seen applied in very suburban areas on the east coast, and we just decided to try It In a very urban setting, which of course, came with a large degree of design issues to work out. But it was Just so successful In the monitoring and the protection of water quality, and the reduction of flow that it just became a no-bralner to use in more residential areas. Now they're very urban areas but they're still single-family residential areas. You have a lot of room to utilize the right-of-way. Now we may have to go in an area that gets a lot denser, like downtown areas or industrial areas, where we may have to go to different techniques, alternate storm water techniques, such as rooftop gardens or something, to be able to apply the same science. SG: How much maintenance Is required for these swales? DA: The first 3 years is very critical. The Flrst 3 years, you want to establish the plants by getting them watered, and picking the weeds out. And so far, we have great homeowner participation. The folks who live on the street are asked to do the watering and to do the maintenance which Is extensive those first 3 years, and I mean extensive.... It's Ilke anyone who puts In a new garden, you want to water it and keep the weeds out until the plants get established so they don't need so much watering, so they fill out across the soil, which makes it hard for weeds to come In. We've had great participation by citizens. The SEA Street, I believe, I[ only had about a 2-3% plant failure, which is pretty remarkable for the amount of plants that went in. So It's very participatory. It's not something the city alone can do, we can't Just pay for that kind of maintenance so citizens have to participate and the design actually helps because It's so Integrated with their front yards, It Is Ilke an extension of their front yards. So people have a tendency to want to make it look nice. It very much blurs the Ilne between private and the public space. SG: These swales actually hold the water until It slowly percolates Into the ground? DA: Right. Except when the storm level gets too high, then they can overflow to the next Swale, and ultimately, the whole system has the ability to overflow into the street right-of-way exit when the storm is much too high for the ability of [the swales] to hold all the water. So there are cases in very large storm where it will overflow.... SG: so it will use the old storm water access? DA: Once [storm water] leaves the area it's like, you know, small wetlands filling up and spilling over Into the next one, and to the next one, so they follow a course until the whole system can no longer absorb the storm water, and then it will flow off this area Into the areas that were existing [before, with no swales], and those usually have areas of improved ditches along the right-of-way. SG: How do you go about selecting the vegetation, do you test them out, do you use native plants? DA: We use a lot of natives, but not exclusively. We have a really great landscape architect who works for the city, and she's been doing the SEA street program and right-of way program for a long time so she has a lot of experience with these plants. We also, on the streets, In order to have folks http://earthsky.com/shows/showsmore.php`?t=20041103 11 /8/2004