An employee who turned the wrong valve accidentally released 952,000 gallons of partially treated sewage into the San Francisco Bay, but it did not cause any harm to public health or the environment, officials said.
The employee at San Jose’s Alviso wastewater treatment plant turned the wrong valve Wednesday, releasing the partially treated water, the San Jose Mercury News reported Saturday.
Normally water from the toilets, showers, dishwashers, washing machines and other appliances of 1.4 million residents in eight South Bay cities flows into the plant, where it goes through three levels of treatment, said San Jose’s director of environmental services Kerrie Romanow.
Romanow said the spilled wastewater had gone through two of the three levels and that most of the impurities had been removed.
“It’s not raw sewage into the bay,” Romanow said. “We are thankful for that.”
The wastewater was heading to a building for the last treatment, but workers were in the process replacing them and a staff member turned a manual valve.
That valve did not have a label resulting in the partially treated wastewater flowing into Artesian Slough, which flows into the bay, she said.
Workers quickly discovered the error, she said, and they were able to close the valve 10 minutes later.
Plant officials took water quality samples near the outflow pipe, and the results showed the wastewater did not exceed state or federal health limits, Romanow said.
Environmentalists said they are monitoring the situation.
“It’s disappointing,” said Sejal Choksi-Chugh, executive director of San Francisco Baykeeper, an environmental group based in Oakland. “When you have human error, it’s really unfortunate. Ten minutes is a long time, and 950,000 gallons is a lot. But luckily it was secondarily treated, so it could have been worse.”