City fined for massive wastewater spill

Ruptured steel pipe caused second-largest Bay Area spill from a sewage treatment plant in past six years

State water pollution officials have hit Sunnyvale with a $187,000 penalty after the city’s wastewater treatment plant spilled more than a quarter million gallons of partially treated sewage into San Francisco Bay last summer.

The spill occurred on July 29 when a 36-inch welded steel pipeline ruptured, releasing 292,600 gallons — the equivalent of about 12 backyard swimming pools — of partially treated sewage that had not been disinfected into channels that flow into the bay near Moffett Field.

“These types of discharges pose a threat to the environment and to human health,” said Thomas Mumley, assistant executive officer of the San Francisco Bay Regional Water Quality Control Board. “This enforcement action will be recognized by the wastewater treatment industry, and will become a deterrent, hopefully.”

The spill was one of the two largest illegal discharges from a Bay Area sewage treatment plant into San Francisco Bay over the past six years, Mumley said. It was eclipsed only by a 2.2 million gallon spill from the Sonoma Valley County Sanitation Agency plant on Jan. 11 and 12, 2019. That discharge of partially treated sewage, which resulted in a $427,000 penalty, went into Sonoma Creek, which flows to San Pablo Bay.

The Sunnyvale case was settled Monday.

Sunnyvale officials said the pipe that failed is buried 10 feet underground and was built in 1975. They said it had not failed before and was scheduled to be replaced in the next few years as part of a massive, $1 billion project to modernize the wastewater treatment plant, which was built in 1956, over a 20-year period. The plant serves about 160,000 residents in Sunnyvale.

“It is something that was unexpected,” said Ramana Chinnakotla, Sunnyvale’s Environmental Services Director. “But we know our plant is aging. That’s the reason why the city council has committed to upgrade the plant. This pipe was going to be replaced. It’s unfortunate it failed before we had a chance to replace it.”

Chinnakotla said that no dead fish or other wildlife were ob