Project description

West Point Treatment Plant is undergoing upgrades to make the facility more resilient in the event of an earthquake. We are improving large enclosed sedimentation tanks that play a key role in the wastewater treatment process. A seismic evaluation performed in 2010 showed that the roof above the tanks did not meet minimum seismic safety standards.

In order to improve resilience of the facility, this project will include:

• Removing a series of large, concrete beams above the tanks
• Improving the odor control system
• Increasing the wall thickness between the two tanks
• Upgrading the walkways on the tank walls so staff can access the facility safely and efficiently

These tanks not only clean wastewater in order to protect public health but also allow King County to recycle valuable resources for the Puget Sound region. The sedimentation tanks are where about 60 percent of organic solids in the flows from our homes, schools and businesses are removed. Wastewater sits in sedimentation tanks for about six hours so that heavy materials sink and light materials float. These organic materials are then skimmed from the top and scraped off the bottoms of the tanks and further treated, recycled and used in products such as Loop, a nutrient-rich biosolids product sold to farms and forests as an alternative to chemical fertilizers.

Located in Discovery Park, West Point cleans wastewater from homes, schools and businesses in a large area that includes Seattle, Shoreline, north Lake Washington, north King County and south Snohomish County.

Project schedule

Construction is beginning April 2021 and will take approximately two years.