Power outage causes 11 million gallons of stormwater, sewage to spill into Puget Sound

An “extensive” overnight power outage inadvertently allowed 11 million gallons of untreated wastewater to flow into Puget Sound on Wednesday.

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The overflows — composed of 80% stormwater and 20% sewage — come from the West Point Treatment Plant in Seattle, the Richmond Beach pump station in Shoreline, and another pump station in Medina.

According to King County officials, “voltage fluctuations” occurring between 12 a.m. and 2 a.m. Wednesday caused pump stations to shut down repeatedly and overflow. Meanwhile, heavy rain and subsequent power outages exacerbated the situation.

“Large volumes of rainfall throughout the day and into the night exceeded the capacity of the Richmond Beach pump station, and the volume of flow through the Medina Pump Station overwhelmed the station as it transitioned from line power to generator power and back to utility power,” the county described in a news release.

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Outages had 17 of King County’s 48 pump stations running on generator power before they were able to fully return to their primary utility power sources.

Health and regulatory agencies have been notified of the overflows, and will soon test water quality and close down beaches at Discovery Park, Carkeek Park, Golden Gardens, Richmond Beach, and Medina Park. People in those areas are advised to “avoid contact with the water over the next several days as a precaution to protect public health.”

Overnight rain and wind also saw hundreds of thousands of Puget Sound residents lose power in their homes, while downed trees landed on roads, vehicles, and houses. As of Wednesday afternoon, providers were still working to restore power to tens of thousands of people.

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