West Point Treatment Plant

Welcome to the West Point Treatment Plant, located about four miles northwest of downtown Seattle on the shores of Puget Sound.

The plant is part of King County's regional system that treats wastewater for about 1.4 million people and covers 420 square miles in the Puget Sound region. Every day, the West Point Plant cost-effectively treats wastewater and stormwater from homes, offices, schools, agencies, businesses and industries in Seattle, north King County, south Snohomish County, and some areas of Lake Washington.

History

• In 1958, voters in Seattle and King County created Metro, an agency charged with developing and operating a regional wastewater treatment system.
• In 1966, construction of a primary treatment plant is completed at West Point.
• In 1991, to comply with the 1972 federal Clean Water Act (external link), Metro begins an expansion of the plant to provide secondary treatment.
• In 1994, resulting from a voter approved proposal to merge Metro with King County, King County assumes responsibility for West Point Plant.
• Expansion and upgrading to secondary treatment is completed in 1996.
• West Point celebrated its 40 year anniversary on Saturday, April 22, 2006 (Earth Day).

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The Plant

The 32-acre treatment plant is on the shores of Puget Sound next to Discovery Park, Seattle's largest and most natural park. The average capacity of the plant is 133 million gallons per day.

The plant is designed to address concerns from environmental groups and the neighboring community. The new facilities include the following:

• walls and berms to hide the plant and provide security
• extensive landscaping with native trees, shrubs and ground cover
• partial covering of some facilities
• a freshwater wetland
• improvements to the trails, roads and facilities in Discovery Park.

Learn more about the innovative design of West Point.

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The treatment plant located next to Discovery Park on Puget Sound.
(Click image for larger view.)

West Point has been recognized
by the National Association of Clean Water Agencies for excellence in wastewater treatment.

The Archaeology of
Seattle's West Point
This award-winning Web exhibit by the Burke Museum tells the story of a remarkable archaeological find and the people who lived in Seattle's Discovery Park 4,000 years ago. (External Link)

The entry to the plant. The walking and biking trail is on the overhead bridge, which keeps people away from traffic.

The Process

For nearly forty years, the West Point Plant has provided wastewater treatment for our region. The average capacity for wet weather flow is 133 million gallons per day. The maximum capacity is 440 million gallons per day during peak storms.

Wastewater coming into the plant undergoes a series of treatments, including the following:

• Preliminary treatment: where large debris like rags, paper, and leaves are removed
• Primary treatment: skimming and settling to remove sludge (heavy materials) and scum (lighter materials), which are sent onto the solids handling process
• Secondary treatment: a biological process that consumes suspended and dissolved organic material, leaving the remaining water or secondary effluent at least 85 percent cleaner than when it entered the plant
• Disinfection destroys most remaining pathogens, or disease-causing bacteria before the final effluent is released through an outfall pipe and diffuser into Puget Sound.

West Point's wastewater treatment process produces valuable byproducts that can be reused within the plant and throughout the region, including:

• Biosolids, the nutrient-rich organic matter produced by treating wastewater solids, are used as a soil amendment for dryland and irrigated agriculture, forest fertilization and is composted for landscaping and gardening.
• Reclaimed Water – after disinfection, some secondary effluent undergoes advanced treatment and is reused on site for cleaning and in-plant processes.
• Energy recovery – digester gas, or methane is a byproduct of the biosolids digestion process and is collected and used on-site in generators that produce electricity and for powering pumps.

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Take an animated tour of the liquid treatment process at West Point.

Wastewater Treatment Process
How is wastewater treated at King County's West Point Treatment Plant?
(PDF, 203 KB)

The West Point Plant discharges treated wastewater under permits issued by the Washington State Department of Ecology.

King County contracts with a local private company (GroCo, Inc.) to make a biosolids compost which is marketed in the Greater Seattle area as GroCo . More about Biosolids Compost.

The People

Thanks to about 150 dedicated employees, the West Point treatment system runs 24 hours a day, seven days a week. Trained professionals – operators, lab technicians, maintenance crew members, process control personnel and administrative staff – ensure the West Point Plant and the pipelines and pump stations that supply it with wastewater operate effectively.

At the plant, state-licensed operators are responsible for the daily operations; lab staff perform analysis on internal processes and products; process control staff strive to optimize the plant's operations; and crews of mechanics and electrical and instrumentation staff maintain and repair equipment.

Our goal is to provide the region with the best wastewater treatment service available while operating as efficiently and effectively as possible.

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Some of the team at the plant.

Address and Contacts

Administration: 206-263-3800
     Monday through Friday, during business hours
Odor Control Hotline: 206-263-3840
     24 hours a day

1400 Utah St. W.
Seattle, WA 98199
Fax: 206-263-3850

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More about West Point:

Links to .pdf files require the free Adobe Acrobat Reader to view.

  Plant Tours

  Predictive/Preventive Maintenance Program

A Web page that describes maintenance activities performed by the team that keeps the West Point Plant working.

  The Maintenance Team Report (PDF, 1.1 MB)

This report describes the roles, responsibilities and recent accomplishments of the maintenance teams at both the West Point plant and South plant in Renton.

   You can also find out about:

• The South Treatment Plant in Renton
• Biosolids recycling and application
• Odor control in wastewater facilities
• Brightwater, a third regional treatment plant under construction
• Public involvement and community relations
• King County Wastewater (NPDES) Permits
• Speaker's Bureau

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Updated: April 15, 2008