Liquid Batch Releases

Like any industrial site, San Onofre has permits to discharge operational wastewater into the ocean. These discharges include non-radiological and radiological releases.

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. 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.

(Click on the image for larger view)

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.

Learn more about Liquid Batch Releases. Watch the brief video below.