Hyperion Investigation Shows Breakdown Worse than Reported: Catastrophe Barely Avoided: Sewage Sent to the Ocean

Not only did sewage spill into the ocean, closing several beaches, some buildings at the Hyperion Water Plant were also flooded with sewage.

(Editor’s note: Published by permission by the Westside Current.)

On July 11, the Hyperion Water Plant began to receive a “very high volume of trash pieces” even though it was a typical summer day with no rain.

Trash started to overwhelm the intake screens that are used to rake and remove debris. As clearing the waste became more and more difficult, workers called plant executives to the site.

By late afternoon the debris flow had wholly overwhelmed the building, requiring the evacuation of personnel due to what it called “life-threatening” circumstances.

According to a City Gate report, that’s when about 6% of a daily load, 17 million gallons of untreated wastewater was discharged as an emergency measure through the one-mile outfall to prevent the Plant from going offline and discharging more raw sewage into nearby beaches.

The sewage also flooded some of the buildings at the Hyperion.

When that happened, the Plant filed its first hazardous material spill release with the 24-hour duty officer at the California Office of Emergency Services.

In the following hours, numerous emails would be sent to different departments, alerting them of their actions. However, at one point during the night, the report shows that while emails and communications were taking place, some staff was out sick–and in one department, new management didn’t grasp the gravity of the situation.

It wasn’t until July 12, that Executive Management at Environmental Health (EH) understood what took place and to what magnitude. That’s when the EH program began posting closure signs at the beach on Lifeguard Towers without alerting lifeguards per longstanding practice, nor was there any adequate public information until mid to late afternoon, 16 hours after the spill took place.

Eventually, numerous were closed including Dockweiler State Beach at Water Way Extension and Dockweiler State Beach at Hyperion Plant.

There are still unanswered questions about the cause and impact of a 17-million-gallon sewage spill that was discharged through the one-mile outfall into the Santa Monica Bay off the coast of Dockweiler State Beach last week – and threatened to derail the plant.

Supervisor Janice Hahn and L.A. City Controller Ron Galperin are calling for an investigation about the 16-hour lag in reporting the spill that put the public in harm’s way.  Galperin said he called for the inquiry on Wednesday because of the lack of information from Los Angeles Sanitation and Environment (LASAN) in the aftermath.  Galperin is also asking how much the event will cost taxpayers.

Hahn called for an immediate investigation after the spill for safety reasons. Hahn said the public should have been made aware of the leak 15 minutes after it happened, not hours. “What happened … was unacceptable and dangerous,” Hahn said. “Not only did the Hyperion Plant release seventeen million gallons of sewage into our ocean — the public had little to no information about it for hours.”

A foul odor has sickened some El Segundo residents and is likely to persist for weeks while repairs are made to the treatment plant. (Hyperion says repairs could take months. Flooding significantly reduced the amount of digester gas available to generate power, resulting in a temporary shutdown of the Hyperion Bioenergy Facility. Unused gas is being burned off. Hyperion says the odor and burn off meet levels set by the South Coast Air Quality Management District.)

LASAN told Dockweiler residents they will reimburse households for hotel stays, up to $182 per day, or up to $600 for an air conditioning unit.

The nine-page City Gate Preliminary Investigation report noted that the EH program relies too heavily on email and lacks policies to separate the small “FYI” events from the significant occurrences that require “all hands on deck.”

What wasn’t mentioned in the report–and what both Circling the News and Westside Current continue to ask is–why did the system overload?

This happened during a dry season. What are the consequences if it occurs during a rainy season? CTN and WC also want to know if the increased load of debris is linked, in any way, to the growing amount of RV’s and encampments on the westside and the illegal dumping of garbage that occurs in the sewers.

City Gate, the same firm used to investigate the aftermath of the Woolsey fire, is expected to finalize a detailed after-action and final recommendation report by August 27.


The Hyperion headworks is the first stop for sewage treatment.


At the Hyperion headworks, the largest solids are removed –  things as big as branches, plastics and rags – as well as smaller solids like sand and other gritty solids. This is called Preliminary Treatment, the first step in wastewater treatment.

Preliminary Treatment consists of a screening process and sand/grit removal. The screening process involves the use of eight bar screens (large metal racks of steel bars spaced 3/4 inches apart) to remove large objects from entering wastewater.

A large mechanical rake removes unwanted materials from the bar screen and deposits the various items into a water trough where they are then dewatered and stored in large silos. Once dewatered, the materials (consisting mostly of rags, wood, and other non-recyclable/non-beneficial materials) are then loaded onto a hauling truck and taken to a landfill for disposal.

HWRP has recovered a number of unusual objects over the course of the years such as golf balls, wooden 2x4s, a bowling ball, a 17-foot long telephone pole and a motorcycle.

After the screening process, wastewater flows to aerated grit chambers for sand/grit removal. Sand can enter sewer lines through the washing of dirt in sinks, showers and washing machines. The sand, if left in wastewater as it is being treated, would act as an abrasive in eroding the various downstream pumps, valves, and pipes.

Air is pumped into aeration tanks to keep the light organic material suspended while the heavy sand settles to the bottom of the tank. The sand is removed by a pump and the pump sends the sand to the materials handling tower where it is dewatered, washed, stored in a hopper and loaded into trucks and disposed of in a landfill (similar to the process for the bar screen material). More than 885,000 pounds of solids and organic materials flow into the Hyperion Water Reclamation Plant in a 24-hour period.


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