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Liquid Batch Release Happening Tomorrow at San Onofre Nuclear Plant

Image by Swan Dive Media

Southern California Edison has announced that a liquid batch release will take place on Thursday, December 19, 2019, 1.1 miles offshore of the San Onofre Nuclear Generating Station (SONGS) and the popular surf beach at San Onofre State Park.

The batch will include 19,200 gallons of treated wastewater and radiological effluent diffused through offshore conduits.

This notification was made thanks to the urging of Surfrider Foundation staff at the March 26 2019 California State Lands Commission hearing where Edison committed to providing batch release notifications and enhanced radiological and environmental monitoring. The goal is to keep the local beach-going and surf community informed about what effluent and potential hazards are posed by actions at the local nuclear plant.

Now atleast you can know before you go.

Edison explains that the effluent has been treated to a radiological dose level of just 0.00183 mrem, which is 0.0321% of the annual whole body dose limit. Surprisingly, this is well within their legal allowance set by the Nuclear Regulatory Commission (NRC), which has a maximum annual dose limit from liquid effluent of 3 mrem per unit. While batch releases have occured since the plant first became operational, this is the first time the public has been notified in advance, consistent with our effort to have Edison increase transparency and public knowledge of the plant’s actions. The notice was posted on Edison’s website on December 17, 2019, and just shared with Surfrider staff today.

The following is an excerpt from Edison’s public Liquid Batch Release Notification page:

The non-radiological releases, such as sewage, meet the stringent criteria of our National Discharge Pollutant Elimination System permit, as implemented by the State Water Resources Control Board. SCE's license with the Nuclear Regulatory Commission governs radiological releases. In both cases, the wastewater is cleaned-up and highly diluted before release to the ocean via discharge ports that are more than a mile offshore from San Onofre.   

Liquid Batch Releases

Liquid batch releases comprise a set volume of water from a specific tank, as opposed to continuous industrial wastewater releases. The water is placed in the tank; circulated through ion exchangers and filters to remove impurities; and then sampled prior to release to ensure it meets regulatory requirements.

48-hour Notice

SCE is providing the public with an approximate 48-hour notice prior to commencing an operational batch release. This notification is posted on this page in the box at right and characterizes the volume, duration, content, and the start date for each release.

SCE has been safely cleaning and discharging these liquids for more than 50 years with no measurable impact on the environment. When San Onofre was operating, these were done frequently, sometimes daily. With the shutdown of the plant, they have dropped dramatically. 

What You Should Know: Consistent with our core decommissioning principles, and as part of the approval of SCE’s lease for the off-shore facilities with the California State Lands Commission, we committed to notifying the public 48 hours in advance of future releases. Importantly, this notice is for general awareness only. These releases are similar to those performed in the past and continue to meet all regulatory requirements.

These liquid releases will continue throughout the dismantlement of the plant and will vary in size over the years, depending on the decommissioning activity. On average, the initial set of releases will be approximately 20,000-25,000 gallons in volume and last approximately 4-6 hours. Future releases may be higher in volume but will still meet regulatory limits.  

The releases are conducted through the Unit 2 conduit, which extends more than 8,000 feet into the ocean. The actual discharge occurs in the diffuser section, which begins at approximately 6,000 feet (approximately 1.1 miles) from shore.

Discharge image


SCE files an annual report with the NRC entitled, “The Radioactive Effluent Release Report,” which covers the operation of the facility during the previous calendar year. The report includes a summary of the quantities of radioactive liquid and gaseous effluents released from the facility, as well as a summary of the quantities of solid radioactive waste shipped from the facility directly to a disposal site.

To learn more about Surfrider's effort to protect the ocean, waves and beaches near San Onofre and get the waste off the beach, click here