King County is working closely with Seattle Public Utilities to coordinate our projects and complement our community engagement efforts. To learn more about Seattle Public Utilities drainage projects in South Park, visit:
March 2016 Update
King County has formed a design team to develop a solution to reduce overflows of stormwater and sewage into the Duwamish River. These overflows come from pipes in the Highland Park and South Park neighborhoods of Seattle.
Be RainWise! RainWise, the rebate program that pays property owners to install rain gardens and cisterns on private property, has been available in South Park and Highland Park since 2013. It is available to eligible property owners through 2016. To learn more and check your availability visit www.kingcounty.gov/rainwise.
Like many cities around the country, the older parts of King County’s sewer system use a single set of pipes to carry sewage and stormwater to a treatment plant. During storms, the pipes can fill up with stormwater, leading to overflows of polluted runoff and raw sewage into nearby rivers, streams, and Puget Sound. When sewer pipes in the Highland Park and South Park neighborhoods fill with too much stormwater, the polluted water overflows into the Duwamish River. Although these combined sewer overflows (CSOs) prevent sewage backups into homes and streets, they also pose public health concerns.
King County is working with a technical team to explore several alternatives for reducing CSOs at the Terminal 115 and West Michigan outfalls. There are several options: a 100% “green” solution that could include roadside rain gardens and/or permeable pavement that lets water soak through it, a traditional “gray” infrastructure solution such as an underground storage tank or pipe, or a mix of green and gray.
King County will select an alternative based on which one does the best job reducing CSOs. Considerations include constructability, operation and maintenance requirements, community impacts and benefits, and cost. During the spring and summer of 2016, the project team will be consulting with community members to learn more about important considerations, such as parking, existing trees, concerns about street or basement flooding, and other issues that will help inform our decision-making.