The King County Wastewater Treatment Division and Seattle City Light are working together to hire an independent consultant to evaluate the quality and reliability of electrical systems at and running into the West Point Treatment Plant following a power sag that required an emergency bypass on July 19.

Seattle City Light reported 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 told Queen Anne News in July that 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.

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 2.1 million gallons of discharge into Puget Sound was stormwater while the other 20 percent was sewage.

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

Wastewater Treatment Division director Mark Isaacson told the King County Regional Water Quality Committee about plans for an independent study of electrical reliability at West Point during its Sept. 4 meeting.

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 244 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. Damages sustained in the flood event amounted to $23 million.

Following the 2017 plant failure, the wastewater treatment division (WTD) engaged consulting firm AECOM to develop an independent assessment of the West Point Treatment Plant. AECOM generated 98 potential mitigation strategies, of which WTD has completed 63 and is working on completing 26 more.

“We are committed to fully implementing AECOM’s recommendations in the oversight report. In fact, we have already acted on 75 percent of the capital recommendations, making more than $800,000 in upgrades to West Point to address the root causes of the flooding,” according to a WTD news release. “We identified more than $200 million in long-term capital projects that would to improve capacity and system redundancy at West Point. These projects are included in future budgets that will need [King County] Council approval. We have made improvements to employee training efforts that strengthen our culture of safety at West Point.”

Those $200 million in long-term projects to increase capacity and redundancies at West Point are anticipated to be completed by 2027, “which means some risks will not be fully mitigated for many years,” according to a staff report submitted to the water quality committee. The $800,000 in improvements were not part of the insurance coverage for the $23 million in damages the facility sustained in 2017, said Michael Bowers, capital projects oversight analyst for the county auditor’s office, and did require deferring other WTD projects.

WTD has requested a $13.8 million grant from the Federal Emergency Management Agency (FEMA) to continue improving redundancies at the facility.

AECOM completed an evaluation of mitigation strategies in March, which Isaacson shared with the King County Regional Water Quality Committee on Sept. 4.

A large mitigation project still in the works is the replacement of four raw sewage pumps to increase capacity at West Point. WTD spokesperson Norm Mah tells Queen Anne News the pumps can only be replaced during dry summer months, as the facility must remain operational 24/7. The cost of the project is estimated at $177 million and projected to be completed between 2019 and 2027.

WTD has also completed an evaluation to construct a passive weir that would be used to alleviate future flooding events with Ecology approval. The project is included in WTD’s Six-Year Capital Improvement Plan. The $5 million project is scheduled for completion in 2019-25.

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