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Project update

December 29, 2021

In Spring 2021, the project team identified a long-term solution to minimize and ultimately eliminate the unauthorized release of wastewater into Puget Sound due to electrical power disruptions, or voltage sags, at West Point. The County will install a battery technology system that will prevent critical electrical systems from protectively shutting down in response to voltage sags. Compared with the other potential solutions we looked at; this one has a short timeline. It is estimated that it can be installed by 2024.

Our team is designing a new building that will replace an existing building at West Point to house the batteries; one that will be strong enough to support their significant weight— and have the capacity for the accompanying transformers, switchgear and electronics. Constructing the replacement building also gives us the opportunity to design for the future, incorporating sustainability features and energy-efficient design.

In December, the Seattle City Council approved legislation related to land use and permitting that supports the next steps for the County to put this solution in place. Read about this process .

Read our latest blog post, frequently asked questions and an article about this project in the County’s June West Point capital projects newsletter and October newsletter for more detail about power quality issues and how this technology addresses them.

English closed caption version.

Project description

Power disruptions at the West Point Treatment Plant can cause electrical equipment to protectively shutdown, and when this happens during heavy rain, the facility is overwhelmed with untreated wastewater and stormwater. To prevent the plant from flooding, flow is diverted to Puget Sound in an emergency bypass.

The objective of the project is to eliminate the emergency bypasses of wastewater that are caused by power disruptions. This project has identified a solution and is rapidly implementing it to improve the reliability of the plant’s electrical power supply.

The project team analyzed numerous potential solutions and chose the solution that is the most effective and quickest to implement. The County will install a battery-based system to condition power as it is fed to critical systems in the plant so that they continue to operate during power disruptions, preventing the emergency bypasses of wastewater to the Puget Sound. The project team is currently developing a design, working on project permitting, and beginning to plan for construction.

Project background

Significant disruptions in electrical power negatively impact the operation of West Point six times a year, on average. When the power is disrupted, expensive equipment protects itself to prevent long-term damage by shutting down.

Plant operators must restart the equipment after a protective shutdown. Most of the time, the plant can store incoming wastewater and stormwater until the power returns. However, when power disruptions occur during heavy rain, there isn’t always enough room to store incoming flow. When this happens, the plant is designed to direct wastewater through an emergency bypass pipe and discharge it directly to the Puget Sound. This is a necessary measure to protect the staff working within the plant and the expensive plant equipment from flooding.

As a result of continued emergency bypasses to the Puget Sound caused by power disruptions, the Washington State Department of Ecology issued an Administrative Order requiring King County to stop unpermitted discharges of wastewater caused by electrical power disruptions.

In February 2021, King County Executive Dow Constantine signed an emergency declaration to provide West Point with more reliable power. In response to the emergency declaration, the County initiated the Wastewater Treatment Division’s (WTD) West Point Treatment Plant Power Quality Improvement Project.

Project milestone schedule

Because of the urgent nature of this project, the overall process of planning, design and construction is occurring quickly.

  • Emergency declared by King County Executive and project initiated: February, 2021
  • Solution selected: May, 2021
  • Estimated start of construction: 1st Quarter, 2022
  • System online, protecting plant from power disruptions: By end of 2024

Contact us

For more information about this project contact Doug Marsano at:
206-477-5549 or TTY: 711

If you’d like to receive email or text updates on the power quality improvement project and other current projects at the West Point Treatment Plant:

Project location

location of worksite at the West Point Treatment PlantView larger version .