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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

Learn more about facility operation

October 31, 2016 -- What you can’t see makes all the difference at North Beach (KCWTD blog)


October 10, 2016

Drainage upgrades

King County has hired a contractor to install curbs and some protective rock to better control stormwater coming from the ditch along Neptune during storms. The County is in the final stages of permitting the project and expects to begin work in mid-October.

Reducing noise from the facility's new mechanical/electrical building

Based on recently completed noise assessments resulting from community inquiries, King County is working to further reduce noise from the mechanical/electrical building. Initial efforts will include wrapping duct work with sound muffling material and capping specific pieces of equipment more likely to generate noise. The County is working on final plans and hiring a contractor for this work.

If you have concerns about the facility's operations

Should you notice issues you believe to be related to the facility's operation (noise or exhaust concerns, lights left on at site, safety or security concerns, open gate, etc.), please contact King County WTD at 206-263-3801 as soon as possible at any time. This number is answered 24-hours a day.

Call 911 in case of emergency.

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 has completed construction of an underground storage tank in the right-of-way in N.W. Blue Ridge Drive and Triton Drive N.W. This facility can store up to 380,000 gallons of untreated water 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. 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 at each of King County’s combined sewer overflow (CSO) control facilities.

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.  

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.

Project contact

Project updates, news releases, photos

Find out if a CSO is occurring in North Beach

Related information