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Completed – Fall 2006

King County protects public health and the environment by conveying and treating the region's wastewater. To ensure safe and reliable operations in the future, the King County Wastewater Treatment Division has completed three projects in the Matthews Beach area to upgrade aging infrastructure. These facilities carry wastewater from the north end of Lake Washington and the City of Seattle to the West Point Treatment Plant in Discovery Park.

What we've accomplished

Since 2002, King County has completed three projects in the Matthews Beach area to upgrade aging infrastructure:

  • Upgraded the pump station
  • Repaired corroded concrete inside the North Portal (entrance) to the Lake City Tunnel in 2002
  • In 2003, repaired the Matthews Park force main by slip lining the existing 42-inch pipe with a new plastic pipe. Slip lining the force main minimized construction-related disruption and extended the life of the pipe.

Construction updates 

Force main rehabilitation

Completed – Spring 2004

In 2004, King County completed repairs on an existing sewer pipe to ensure safe and reliable operations. A county contractor installed a smaller plastic pipe inside the existing 42-inch Matthews Park force main sewer.

Our contractor has successfully relined nearly 1,100 ft of the Matthews Park force main sewer. Most of the work occurred along Matthews Ave NE and then shifted to the North Portal of the Lake City Tunnel, where the sewer ends.

Benefits of relining versus replacing a force main

  • Less community and environmental impacts (dig access pits instead of trenches along entire length of force main; less trail and traffic impacts along Burke Gilman Trail, Matthews Ave NE and Sand Point Way)
  • Saves time and money

Pump station upgrade

Completed – Fall 2006

To keep our system operating reliably, the King County recently upgraded the Matthews Park Pump Station, which is nearly 40 years old.

The upgrades included:

  • Constructing a new electrical building to house upgraded equipment
  • Installing a new emergency generator and underground fuel tank to provide power during outages
  • Installing new and upgraded pumps, motors and other equipment
  • Landscaping the site with native plants, to enhance the Thornton Creek riparian corridor.

This newly upgraded facility will serve customers in the north portion of our service area for at least the next 50 years.

In 2007, the county will also upgrade the odor control system to improve air quality at the pump station and along the sewer line extending north of the facility.

24-hour emergency and odor reporting:

Contact West Point Treatment Plant at  206-263-3801.

 damaged force mainForce main damage due to erosion by sand and grit in the wastewater. Click images for larger view.

New pumps help ensure reliable future operation.

Operator checks new pump station controls

The new emergency generator will provide backup power during outages.