Seattle wastewater treatment plant working to resume operations following massive sewage spill

aerial view of west point wastewater treatment plant
West Point wastewater treatment plant in Seattle, Washington. Photo:

Crews are working to restore normal operations at King County’s West Point wastewater treatment plant in Seattle, following an early morning equipment failure on February 9, 2017, that led to the plant’s shutdown.

West Point has a secondary treatment capacity of 300 million gallons (113,5623 m3) per day, and primary treatment and disinfection capacity for flows between 300 to 440 million gallons (113,5623 m3 – 166,5581 m3) per day.

According to King County, an effluent pump station went offline at a time when the plant was receiving high levels of stormwater and wastewater and dealing with very high tides. It was operating at maximum capacity and was threatened with being flooded.

Approximately 260 million gallons (984,200 m3) of combined stormwater and wastewater was diverted to an emergency bypass outlet in Puget Sound. The County said the bypass discharge lasted 19 hours and consisted of 85-90% stormwater and 10-15% sewage. During this time, up to 200 million gallons (757,082 m3) of wastewater was diverted to other treatment facilities in the regional system.

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As a result of the emergency, King County warned people to avoid contact with the water and posted warning signs on nearby beach areas. In addition, Kitsap Public Health District issued a no-contact advisory and shellfish harvesting closure for nearby shorelines on February 9.

Chris Wilke, executive director of Puget Soundkeeper, an environmental watchdog group, told the Seattle Times that the amount of untreated sewage dumped so far comprises about one-fifth of the typical overflow amount for the area’s sewers annually.

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