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All systems go at West Point Treatment Plant as essential repairs completed


King County’s West Point Treatment Plant is back online following successful restoration of critical mechanical and electrical systems that were damaged by severe flooding on Feb. 9. The plant’s secondary treatment system is now treating 100 percent of the wastewater entering the plant as plans for longer-term repairs get underway this spring.


Less than three months after severe flooding at King County’s West Point Treatment Plant badly damaged vital mechanical and electrical systems, repairs of essential equipment are complete and the facility has regained the ability to treat 100 percent of the wastewater entering the plant, marking a major milestone in the restoration of critical system capacity and capabilities. 

“Thanks to the dedicated employees and contractors who worked day and night, often in very challenging conditions, the West Point plant has been rebuilt in record time,” said King County Executive Dow Constantine. "From this incident, we will learn, make adjustments, and share our insights and experiences with peers nationally and internationally. We will continue to hold ourselves to the highest standards for wastewater treatment, professionalism, and continuous improvement.”

Since Feb. 9, workers at West Point have restored or rehabilitated:

  • One mile of tunnel
  • 151 electric motors
  • 2 miles of insulation
  • 40 new or temporary motor control centers
  • 125 electrical panels
  • 25 electrical transformers
  • Over 1,000 temporary light fixtures
  • 200 flooded solenoids
  • 1,200 outlets and switches
  • 10 Ovation system controls
  • Primary sedimentation tanks the size of three football fields
  • Six digester tanks

With permanent and temporary equipment needed to bring West Point up to full wastewater treatment capability now operating, the remaining restoration work will center on long-term equipment repair and rehabilitation projects to be carried out by the end of the year.

Over the coming weeks, plant staff will continue fine-tuning the biological processes that are essential to secondary treatment at the facility. As of today, 
100 percent of the wastewater coming into the facility each day is now going through full secondary treatment.

West Point’s secondary treatment process units were not damaged in the flooding that occurred at the plant on Feb. 9. But the secondary process relies on beneficial microorganisms to break down organic solids and remove pollutants from water that is disinfected and returned to Puget Sound. The loss of power and heat essentially put this biological process into hibernation, temporarily limiting capacity at the plant.

Now solids are again being separated and pumped to large heated tanks called digesters, which operate much like a human digestive system to break down organic matter. To avoid overfeeding the digesters as the delicate biological system is still in recovery, up to 20 trucks each day will transport solids from West Point to King County’s South Treatment Plant in Renton. 

With drier spring weather on the horizon, plant operators expect to be able to continue secondary treatment at full capacity, with a stormwater-sewage bypass extremely unlikely except in the event of a true operational emergency. No stormwater-sewage bypasses have occurred since Feb. 16 and beaches have been open since Feb. 21.

In response to the bypasses and the temporarily limited treatment, King County has committed to increasing its water quality monitoring in Puget Sound. 

Additional information on West Point’s restoration is online. For ongoing updates on water quality, please visit the West Point Marine Water Quality Monitoring information page.