skip to main content

Wastewater Treatment

King County, Washington

For questions about the Wastewater Treatment Division website, please send an e-mail message or contact us at:

King Street Center
201 S. Jackson St., Suite 500
Seattle, WA 98104-3855
Phone: 206-477-5371
Fax: 206-684-1741
Telecommunication device for the deaf (TTY): 711

Get Directions to our office location in Seattle, Washington.

Staff Contacts

North Beach CSO Control Project

Project Construction

July 30, 2015 Update 
Crews continue working to connect wastewater infrastructure elements on-site and to install new manholes.

Crews will be working this Saturday, August 1. Thanks for your continued patience and understanding with all of the activity on site.

Activities on site this week
-- Connecting new wastewater infrastructure elements this week.
-- Forming and pouring the drain vault lid. Concrete pouring trucks will be on-site during this work.
-- Working on the mechanical/electrical building interior, including ventilation equipment.

Street work and repaving
-- The contractor continues finalizing utility restoration in the right-of-way, including finishing a water main, natural gas line, and restoring the street light that was removed to construct the tank.
-- In late August, the contractor will pave the entire roadway area and complete final roadway restoration (striping, curbs, permanent signage, etc.). This activity is expected to take one week.

What to expect from upcoming activities
-- During utility work, utility agencies and companies may have vehicles, crews, and equipment on or near the site. While they are on-site, King County is not able to direct their work, where they park, or if their trucks are idling.
-- Some utility work may require temporary outages. Utility agencies should inform impacted residents of any upcoming outages. We will do our best to inform you of planned outages when we can.

View construction update (July 30, 2015) and construction photos.

Questions? Comments? Concerns?

24/7 Construction Hotline: 206-296-7372
Leave a message, and a project team member will return your call.
Project Contact: Monica Van der Vieren,

Keep up to date on construction plans and activities
• Work in the right-of-way
• Work on King County’s property
• Traffic control

Project vicinity map
Project vicinity

North Beach Pump Station
North Beach Pump Station, located on King County property next to Blue Ridge Park, is built on the footprint of the former City of Seattle treatment plant.

Project description

King County is building an underground storage tank in the right-of-way in N.W. Blue Ridge Drive and Triton Drive N.W. This facility will be able to store to 380,000 gallons of untreated water during peak flows when the North Beach Pump Station reaches maximum capacity.

Learn more about the project area and elements.

Why does King County need to do this project?

In 2008, King County reported that the North Beach combined sewer overflow facility had 10 overflows per year on long-term average that discharge a total of 2.2 million gallons into Puget Sound off North Beach. At North Beach, King County is working to meet current regulations set by the Washington Department of Ecology require no more than one untreated discharge per year on a long term average.

23 untreated discharges of stormwater and sewage at North Beach by the end of October 2014.
King County appreciates your patience as we continue building this mandated project.  

Construction schedule

View construction update (in yellow box at top of page) for latest schedule.

Understanding the sewer system in North Beach

The North Beach Pump Station has provided wastewater service for the area since 1962 by collecting flows from the City of Seattle’s local sewer system. These flows are conveyed to the Carkeek Wet Weather Facility where they are either pumped to the county’s West Point Treatment Plant or, in large storm events, treated on site. The North Beach Pump Station is built on the footprint of what was once a City of Seattle treatment plant. The walls and foundation are from the original treatment plant.

Learn more: download Understanding the sewer system in North Beach, Winter 2014

Did you know?

  • The North Beach Pump Station is built on the footprint of what was once a City of Seattle treatment plant. The walls and foundation are from the original treatment plant.
  • When Metro was created by voters in 1958 to provide regional wastewater conveyance and treatment, local treatment facilities like the one in North Beach were considered for conversion to pump stations to bring flows to regional treatment facilities.
  • The current service area for the North Beach Pump Station is 633 acres. Wastewater from additional areas within Blue Ridge are conveyed by gravity to the North Beach force main, where they combine with pumped flows to the Carkeek Wet Weather Facility.
  • The North Beach Pump Station is largely built underground with access hatches and ventilation equipment above ground. Four pumps are used to convey up to 3 million gallons per day (mgd) of wastewater to Carkeek.
  • The CSO facilities include a deepwater outfall upgraded in the 1970’s from the outfall that served the original treatment facility. Discharge to a second outfall, which usually conveys stormwater, helps to prevent backups into homes in large storms.
  • The new CSO facility will introduce odor control at the North Beach site. Currently there is no odor control associated with the North Beach Pump Station. King County has not received odor complaints about this facility.

Construction photos
View construction photos.

North Beach CSO Control Project construction hotline

24/7 Construction Hotline: 206-296-7372
Leave a message, and a project team member will return your call.
Project contact: Monica Van der Vieren, 206-477-5502, or via feedback form.

Project updates and news releases

Find out if a CSO is occurring in North Beach

Related information