All this heavy rain lately is making us think about the Glencoe Rain Garden in SE Portland. In 2013, we celebrated the 10th anniversary of its installation, and 10 years since fixing a difficult problem.
In the 1990's and early 2000's, residents of the Mount Tabor neighborhood along SE 53rd Avenue were experiencing frequent sewage flooding in their basements. Environmental Services studied the problems with the sewer system in that area and found that the pipes, built in 1937, were not large enough. Too much stormwater was running off area streets and parking lots and into the pipes, causing sewage to backup in the basements of homes along the block.
Pre- construction photos, 2002
There were two solutions to the problem - replace and enlarge the pipes in the area, or construct facilities on the surface to slow and retain the runoff so it doesn't reach the sewer pipes. After extensive analysis, the City partnered with Portland Public Schools and Glencoe Elementary School to design an innovative bioswale and rain garden that captures runoff, slows it down, and keeps it from entering the sewer and contributing to back up.. (See the project fact sheet here). The project was completed in 2003.
Post-construction photos, 2004
Now, 10 years later, the facility continues to do its job! Here’s what we know:
- No basement backups in the area have been reported in 10 years
- The plants and soils in the facility are soaking up 85% of the annual volume of runoff, and reducing the annual peak flow by 80% (it's doing very well)
- The native soil and plants used in the facility are performing well
- By design, any pollutants from the street runoff are concentrated at the forebay of the facility (where the water first enters). This is keeping these pollutants out of our sewer system and rivers, and we closely monitor the levels in the soil to make sure it stays safe
In addition to providing residents and students with access to a pleasant, park-like setting, the rain garden serves as an extension of the school's outdoor classroom and butterfly garden.