Editor's Note: This article has been updated with more information regarding the power disturbance at West Point Treatment Plant provided by Seattle City Light.

The King County Wastewater Treatment Division has submitted its overflow report to the Washington Department of Ecology, which provides more detail about a July 19 power disruption at the West Point Treatment Plant that resulted in the bypassing of millions of gallons of stormwater and sewage into Puget Sound.

Seattle City Light reports a storm event early that morning caused a surge and resulting fire to break out on a power pole adjacent to the Canal Street Substation. The pole broke off and struck additional power lines, cutting power to more than 10,000 City Light customers. City Light spokesperson Julie Moore tells Queen Anne News West Point has a dedicated underground feeder from the Canal Substation and a backup source at the Broad Street Substation.

The dedicated feeder experienced a 0.75-second voltage sag, where it dipped to 64.5 percent of nominal voltage, according to Moore, which resulted in pumps turning off, including an intermediate pump station and an effluent pump station. The county's report states the plant was taking in around 300 million gallons per day.

"Both City Light feeders to the plant remained in service during this event and West Point did not actually lose power," Moore writes in an email to Queen Anne News. "The voltage fluctuation was small enough that it did not cause an automatic switchover to the backup feeder. However, the sag was enough to trip sensitive equipment at the plant. King County reported that four out of five pumps dropped off due to measures it has put in place to protect the large motors. Because of their size, the motors cannot easily or quickly be restarted."

An emergency bypass gate opened for 27 minutes due to high wastewater levels in the raw sewage pumps and influent control structure. King County reports about 80 percent of the discharge into Puget Sound was stormwater while the other 20 percent was sewage.

A standby effluent pump station did activate, according to the report, “only to fall offline due to high vibration. Staff are investigating the cause of the vibration trip.”

All pumps were restarted and resumed pumping after the motor drives were reset.

King County initially reported 3 million gallons of wastewater had been discharged through an outfall into Puget Sound, but has since updated the figure to 2.1 million gallons.

“Although a bypass and secondary diversion resulted from the power disturbance, the plant’s safety interlocks operated as designed to prevent a potential flooding of the plant,” Robert Waddle, operations and maintenance section manager, wrote in the overflow report. “In addition, staff responded quickly and competently to the event. It should be noted that their training was instrumental in their quick and capable response.”

King County notified Ecology about the bypass, and sent in its overflow report within the five-day deadline established in its National Pollution Discharge Elimination System permit. Ecology spokesperson Larry Altose said the department’s investigation will take several weeks — maybe months — to complete.

Ecology fined King County $361,000 and ordered that improvements be made at West Point following a plant failure on Feb. 9, 2017 that resulted in 235 million gallons of untreated wastewater entering Puget Sound. It was the largest fine Ecology had imposed on a publicly owned wastewater treatment plant at the time.

“Many improvements were made since then,” King County Wastewater Division spokesperson Marie Fiore told Queen Anne News following the outage, “and as a result that’s why the response time in order to get [the plant] back online was only 27 minutes.”

King County Councilmember Jeanne Kohl-Welles agrees the 27-minute outage was better than the plant’s 2017 failure, adding months of work and upgrades were made to ensure it never happened again.

“Unfortunately, it has, but at a much more minor scale,” Kohl-Welles said. “A lot is being looked into it, I know.”

In her capacity as chair for the county’s board of health, Kohl-Welles has requested a briefing on the incident, which is scheduled for Thursday, Sept. 19.

Controlling power outages is outside the county’s purview, she said, but she would like to know why the treatment plant’s backup generators didn’t immediately kick in.

Fiore said water enters the system at a high velocity and volume.

“You can’t just put the brakes on that high volume of water and go to a backup power source,” she said, adding that’s why the emergency bypass occurred. “Once it’s in the bypass, it has to be discharged.”

Kohl-Welles said she’s also concerned about the health of sea life and the impacts of wastewater being released into Puget Sound.

The councilmember secured funding in the county’s 2019-20 budget to study the effects of wastewater effluent on marine life. She said that funding should become available this fall.

“I’m really looking forward to that study being completed, and this isn’t helping with that,” Kohl-Welles said.

North Beach and South Beach at Discovery Park were closed following the July 19 discharge of untreated wastewater, and water testing was conducted there for four days. Beaches at Golden Gardens and Carkeek Park were also tested.

Enterococci bacteria are indicators of fecal material in water, and 104 enterococci per 100 milliliters is the threshold for closing a beach, Fiore said.

The outflow report shows water enterococcus levels at all sampling locations well under the threshold, with a 64 score at North Beach on July 19 and 68 at the south end of the beach at Carkeek Park on July 21.

“It shows that they never exceeded the state’s thresholds for anything,” Fiore said. “All the tests came back negative.”

Altose said Ecology generally uses the initial overflow report from an agency to craft follow-up questions as it proceeds with its investigation.

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