KING COUNTY, Wash. — Around 1:00 am on July 19, an unusual summer storm led to a power outage in Seattle.
At the West Point Treatment Plant, which has backup electricity, King County officials say the power level dipped for less than a second, just long enough for an emergency bypass to open to keep the plant from flooding.
Over 27 minutes, 3 million gallons of untreated sewage and stormwater spilled into Puget Sound.
"We are very sorry, and we very much regret the fact that that happened," Wastewater Treatment Division Director Mark Isaacson told the King County Regional Water Quality Committee on Wednesday.
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Isaacson said a consultant will look at how steady and reliable the power is coming into the plant.
"What we want to look at here is an independent analysis, both of the power coming into the plant from City Light, as well as how we are receiving it," Isaacson said.
The county sent a letter to Seattle City Light identifying 104 power failures at the plant between 2001 and 2017.
The most serious power failure was in February 2017 when the plant flooded and 244 million gallons of untreated or partially treated sewage flowed into the sound.
King County auditors said while officials are making progress improving the plant, eliminating the risk of another emergency will require spending more than $200 million on improvements like replacing pumps.
Because that's complicated and expensive, auditors say the work could take until 2027 or beyond, making the plant vulnerable to more failures.
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