The Hyperion Water Reclamation Plant (Hyperion) is a sewage treatment plant operated by City of Los Angeles Sanitation & Environment located at 12000 Vista Del Mar, Playa Del Rey, CA 90293.
Wastewater treatment plants process water from homes and businesses, which contains human waste, food, and certain soaps and detergents. As such, odors may occur due to different factors. Common odors lingering in and around treatment plants smell like rotten eggs, ammonia, or garlic, among other things. Generally, they result from the decomposition of organic compounds, of which hydrogen sulfide (a gas that smells like rotten eggs) is a natural by-product. Other organic compounds at treatment plants contain sulfur or nitrogen, producing odors that are detectable by the human nose at extremely low concentrations. Plant operation and maintenance activities, either planned or unplanned, and/or upgrades to treatment processes are other factors that can affect the nature and severity of odors. Odors may be most noticeable on hot days and when the levels of bioactivities are high and the percentage of humidity in the air is higher. The first step in solving any odor problem is identifying the source, which may be a combination of different things. The next step involves preventing the odor from being released to the air by installing covers and building containment around the odorous treatment processes. And finally, the odorous air should be properly treated before it is released.
On July 11, 2021, Hyperion experienced a malfunction at its headworks facility when a series of bar screens were overwhelmed and unable to remove large quantities of trash and debris causing a system failure and raw sewage to flood the plant. As a result, elevated hydrogen sulfide levels produced odors that impacted residents' quality of life until the flood was cleared. In recent months, odors have continued to intermittently impact the surrounding community. Odors are expected to decrease with the installation of new Primary Battery Tank Covers. This activity is underway. In-service covers will be replaced by December 2023, with additional interim measures expected to reduce odors. All other tank covers are anticipated for replacement by June 2024.
LA Sanitation & Environment provides hourly data on levels of hydrogen sulfide in the air at Hyperion. The levels can be found on Hyperion Air Monitoring page.
They also provide updates and air monitoring data on Hyperion 2021 Recovery.
The South Coast Air Quality Management District (SCAQMD) additionally provides updates on the investigation on their Hyperion Water Reclamation Plant website.
Hydrogen Sulfide (H2S) is a gas that smells like rotten eggs. Industrial facilities such as sewage treatment plants can produce hydrogen sulfide.
People can generally smell hydrogen sulfide odors at around 3-5 parts per billion (ppb), although some people can smell hydrogen sulfide at even lower concentrations. This can be stressful and impact health and quality of life.
The health effects of hydrogen sulfide depend on how much you breathe and for how long. Hydrogen sulfide in low concentrations can cause symptoms such as:
The California Environmental Protection Agency's Office of Environmental Health Hazard Assessment (OEHHA) reviews information about chemicals. OEHHA has determined that no adverse health effects are anticipated at hydrogen sulfide at levels below 7 ppb in the air, even for chronic (long-term) exposures. Hyperion operates 3 continuous hydrogen sulfide monitors at their fenceline. The majority of the time the hydrogen sulfide is measured at less than 3 ppb, historically, there have been 2 to 3 times a week that hydrogen sulfide is measured between 7 and 30 ppb and those elevations are generally short lived and go back down with an hour or two.
The California Ambient Air Quality Standard for hydrogen sulfide is 30 parts per billion (ppb), averaged over one hour, and was adopted for the purpose of odor control.
Hydrogen sulfide in air is regulated by the South Coast Air Quality Management District.
If you are experience odors, you can:
If you notice "rotten egg" or "sulfur" odors, you can report them.
Residents experiencing health symptoms are encouraged to contact their healthcare provider.
Last Updated: March 22, 2023
