Ravenna Creek pipe extension
Completed Fall 2011
Need for project
King County is responsible for conveying and treating wastewater from 17 sewer districts and 17 cities including Seattle. Wastewater from residences and businesses collected by the City of Seattle is transported to the county’s West Point Treatment Plant in Magnolia through pipes owned by the county. This project protects public health and the environment by preventing sewer overflows into University Slough on the University of Washington campus.
Project vicinity map (PDF), updated March 2010.
New box culvert with pipe extension (PDF)
To prevent sewer overflows into University Slough, the Ravenna Creek Pipeline Extension will isolate Ravenna Creek flows within a pipe installed in an underground box culvert that now conveys creek flows. Although the box culvert was believed to be abandoned, the county learned that the box culvert does receive sewer overflows during heavy rains. Extending the pipe carrying creek flow through the box culvert will allow normal creek flows to travel through the system to University Slough without risk of sewage contamination. Sewer flows in the box culvert will continue downstream to the county’s Laurelhurst Trunk and for treatment at the West Point Treatment Plant in Magnolia.
Work hours will typically be weekdays 7:00 a.m. to 5:00 p.m. Excavation activities in the park will last at least six weeks. To allow for construction activities in the box culvert (see map at right) below grade creek flows will be diverted to the county sewer. Surface creek flows in the park will not be affected. Pumps and generators will operate every day around the clock to control ground water and allow for work to occur below grade. Mitigation projects in the park will continue throughout the fall.
What can you expect?
- Heavy machinery, construction materials and excavation equipment in the outfield of the Ravenna Park ball field (see map at right)
- Increased noise, dust and activity coming from the construction site