Seattle Public Utilities sends out survey to study rainwater and sewage overflow issues in Ballard

Seattle Public Utilities (SPU) is asking some Ballard residents to take a survey about rainwater and sewage overflow. The survey will help the city investigate a natural drainage system to prevent sewage overflow in Salmon Bay.

The survey was sent to residents who live in what’s called the combined sewage overflow area (CSO), between NW 65th St and NW 85th St, and 16th Ave NW and 30th Ave NW. Shanti Colwell from SPU explains that when it rains, rainwater from this area flows into a pipe that carries it to a wastewater treatment plant. However, in heavy rain, the wastewater treatment pipe often overflows, sending the remaining rainwater straight into Salmon Bay. Colwell says in 2009, the pipe overflowed 73 times, sending a total of 43 million gallons of untreated wastewater into the bay.

The survey will allow SPU to get a better idea of what areas are overwhelmed with rainwater so they can build roadside rain gardens. The idea, Colwell says, is to capture rainwater and send into the ground and not into the pipe. They’ll use the results to look at locations for the rain gardens, possibly in areas that could use one to relieve some traffic issues, or to improve the aesthetics of a street or neighborhood block.

There will be an open house from 6 to 8 p.m. on Feb. 12 at the Sunset Hill Community Center to show the results of the survey and some upcoming soil testing results. Learn more about the project here (PDF) or on the SPU webpage about the Ballard Basin.