Environmental Services works with private property owners in targeted areas to manage stormwater and keep runoff out the combined sewers. Rain gardens, stormwater planters, swales, ecoroofs, and pervious pavement collect runoff from roof and paved areas and allow it to soak into the ground instead of flowing into the sewer system. Using natural processes to manage stormwater at its source helps control combined sewer overflows to the Willamette River and reduces the risk of sewers filling to capacity and backing up into basements during heavy rains. These kinds of stormwater management facilities also reduce sewage treatment costs, replenish groundwater supplies and beautify neighborhoods. The city provides substantial financial and technical assistance with project construction and the facilities remain private property and are privately maintained.
This new rain garden at Thanh Thao on SE Hawthorne Boulevard is a great example. In addition to the asphalt removed to make space for the facility, the building’s roof and the western parking lot now drain to the rain garden. The result is 4,840 sf of impervious area managed through this project. In an average water year of 37”, this project will keep approximately 106,000 gallons of stormwater out of the combined sewer. With over 56” of rainfall in 2017 so far, it’s already managed over 160,000 gallons of runoff!
Thanh Thao parking lot, before construction
Thanh Thao parking lot concrete getting removed
Thanh Thao rain garden prior to planting
Thanh Thao parking lot rain garden complete