Disruption to the power grid at Pierce County’s wastewater treatment plant in University Place caused the final step of sewage disinfection to go offline for a time Friday morning. The result was approximately 159,000 gallons of partially treated sewage discharged into Puget Sound.
The water was expected to be fine by Saturday.
The power outage affected the treatment plant’s ultraviolet light disinfection, which is the final step in the treatment process, killing any remaining pathogens, said Pierce County Public Works director Brian Zeigler.
That means the 159,000 gallons were still “highly treated,” he said. It was also “highly diluted” he said because the wastewater is discharged hundreds of feet offshore into Puget Sound.
The county is required to report the malfunction to the Tacoma-Pierce County Health Department, Zeigler said.
That resulted in the Health Department posting warnings at the Bridge to the Beach in the Chambers Creek Regional Park, telling people to stay out of the water.
“Depending on the tidal and wind influences, there’s the potential that partially treated effluent could wind up on the beach,” Zielger said, although he added it’s not likely.