Matthews Park Pump Station

King County, 
Washington

Matthews Park Pump Station

Service Type: 
Project Highlights: 
  • 120-mgd pump station with dry pit/wet pit configuration.
  • 2,200 kW of diesel standby power.
  • All new electrical, VFDs, and I&C systems.
  • Detailed construction sequencing plan to maintain critical operations during construction.
  • Community relations and permitting services.
King County’s Matthews Park Pump Station
Carollo provided a comprehensive program for future design and operational changes and designed a capacity upgrade of King County’s Matthews Park Pump Station.

As part of an on-call services contract to King County, Carollo developed a comprehensive program for future operational changes to this mgd pump station, which was originally constructed in 1966. The age of the facility, projected changes to influent flows, and various independent projects in various stages of completion drove the need to consider the following:

  • The impact of various new pumping strategies at the North Creek and York pump stations to serve the new treatment plant.
  • The energy savings and impacts of using VFDs as replacements for existing electromagnetic clutches.
  • The impact of changing the size of pumps on wet well and force main hydraulics.
  • The level of urgency with which each project should be completed.

Carollo evaluated six alternative scenarios to accommodate the pump station’s projected 15:1 flow range and designed replacement systems that include: two 500-hp pumps and two 700-hp pumps; pump motors; 18-pulse VFDs for all pumps; 4,160-volt and 480-volt electrical service, feeders, conduit and wire to major equipment; a 2,000-kW standby generator and fuel system; a 2,000-square-foot electrical building to house switchgear and drives; pump headers, discharge check valves, and isolation valves; air/vacuum valves
for surge control; odor control system modifications; and modifications to the seal water system.

Because keeping the existing pump station in operation during construction is an important consideration, Carollo developed a detailed construction sequencing plan and schedule. Central to the plan was the need to construct a new electrical room without disrupting existing equipment.

Carollo also assisted King County with permitting and public involvement during detailed design. This included research, community meetings, and submittals to the permitting agency, the City of Seattle. The site’s location adjacent to a critical urban stream, required extra attention to storm water control. Carollo met these challenges by confining the footprint of the new electrical building to the allowable space without impacting the stream or flood plain setback requirements. This also simplified permitting approval by the city.

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