City partners to build a "rain garden" at NE 40th & 172nd Ave. By John Reinke

Installation Site on NE 40th and 172nd Ave.

This report and photographs are contributed by John Reinke of Education Hill, Redmond.

With great excitement, two weeks ago I joined three staff members from Stewardship Partners and two local citizen volunteers, in constructing a "rain garden" on city land near a busy intersection at NE 40th Street and 172nd Avenue.

The purpose of a "rain garden" is to divert rainwater runoff into a temporary "holding pond" where it can be absorbed and retained in the soil, rather than ending up in Puget Sound via the stormwater runoff system. This benefits the land by replenishing groundwater and it benefits the Sound by keeping out heavy metals.

Plants and gravel outflow area positioned on site

The idea for the rain garden came from Stewardship Partners, which obtained funding for it from the King Conservation District. Stewardship Partners is a local nonprofit that specializes in helping landowners to preserve the environment. The City of Redmond partnered on the project, and provided the necessary permits, as well as scooping out a depression in the ground for the rain garden and modifying the curb to permit rainwater to enter from the road. Planning for the garden was done by Zsofia Pasztor of Innovative Landscape Technologies. See the slide show of the installation. 

Stacey Gianas of Stewardship Partners oversaw our planting efforts. She explained how different species of plants were chosen, depending upon which of 3 levels they would occupy in the garden. Plants at the bottom level have to tolerate having their roots wet for extended periods of time. On the other hand, plants at the top level should be somewhat drought resistant. Plants in the middle level need to be somewhere in between in their water requirements.

READ MORE >> about the installation

 We planted a variety of sedges, shrubs and other plants. I was surprised to see a number of strawberry plants in the top layer. These will bear edible fruit, Stacey said. Dogwoods and others were placed in the bottom level.

Once all of the plants had been placed in the soil, we proceeded to shovel a layer of humus around all of them. This was followed by a second layer of compost, about 3 or 4 inches thick. We then watered all of the plants copiously. The whole effort took about two and a half hours.
The only task that remained was for the city to open the curb in two places. A few days later, an opening was made near the intersection to permit rainwater runoff to flow into the garden to fill it up. Another opening was created downhill from the intersection, so that any excess rainwater could run back out and into the stormwater runoff system.

Marilyn said the garden needs to be watered twice a week for the first two years during dry periods, while it is getting established. After that, she says it's time for "tough love" and the garden has to make it on its own.

View the complete set of photos of the installation.

If you are a landowner who would be interested to explore rain garden possibilities for your property, please contact Stewardship Partners.

By John Reinke
Education Hill neighbor
more stories and photos by John Reinke

City "rain garden" web page

Install is complete - note  overflow graval areas.