El Segundo

Residents Sue Los Angeles Over 2021 Hyperion Sewage Spill

Hyperion's bar screens had failed once before in April and the agency's managers should have known a catastrophe was inevitable, the suit states.

Multiple plaintiffs living near El Segundo sued the city of Los Angeles Tuesday for allegedly exposing people to toxic hydrogen sulfide gas and other dangerous toxins during and after the Hyperion Treatment Plant's 2021 sewage spill.

The city's LA Sanitation and Environment plant suffered a failure on July 11, when all debris filtering machines, also known as bar screens, became clogged and inoperable, causing some 72 acres to be flooded with raw sewage, according to the suit.

The Los Angeles Superior Court complaint alleges the bar screens were in fact unreliable and were designed to be run through an automatic control system that proved to be unreliable. The plaintiffs further allege that LASAN knew the automatic control system was suspect in 2019, but chose to operate the bar screens in manual mode on fast-forward with no additional oversight added for these faster speed operations.

"We will review the complaint and have no further comment at this time," Rob Wilcox, a spokesman for the City Attorney's Office, said in response to the suit.

To contain the flooding, LASAN released 17 million gallons of untreated wastewater into the Santa Monica Bay, which later caused the California Water Board to issue 47 citations between July 17 and Aug. 31, according to the lawsuit.

In reports to the state Water Board and the U.S. Environmental Protection Agency, LASAN claimed the sewage overflow was a result of excessive trash in the sewer system from an unknown source, but responsible monitoring would have identified both the volume and source of any debris before it reached Hyperion, according to the suit.

Hyperion's bar screens had failed once before in April and the agency's managers should have known a catastrophe was inevitable, the suit states.


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"This is a massive raw sewage spill from one of the world's largest water treatment facilities," plaintiffs' attorney Alexander Wheeler said.

"The warning signs were glaring leading up to the spill, and now El Segundo residents are paying the price for LASAN's disregard for public safety."

Hydrogen sulfide is one of many gases created during the decomposition of organic materials in sewage and even at low levels it irritates the nose, throat and eyes and causes headaches, nausea, vomiting and fatigue, the suit states.

"L.A. Sanitation knows how dangerous hydrogen sulfide gas can be, and yet they did nothing to protect people from the exposure," said another plaintiffs' attorney, Mark Bloom. "Even with all of the warning signs, LASAN failed to invest in meaningful repairs after the bar screens clogged not once, but twice."

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