Update on Wastewater Release from San Onofre Sewage Treatment Plant

Southern California Edison received a Notice of Violation and Investigative Order on April 16 from the San Diego Regional Water Quality Control Board regarding the March 25 wastewater release from the sewage treatment plant at San Onofre. The letter identifies potential violations of waste discharge requirements and directs SCE to submit additional technical information addressing the incident. We are currently reviewing the incident and will respond to the board with the requested information. The board has asked for our response by June 15.

Immediately following the release, SCE launched a thorough review of the event. That evaluation continues, and we will use the information we gather to inform our response to the board. Additionally, we will conduct an assessment with supporting analysis of any impacts on the ocean waters that received the discharge.

Discharge Location
The partially treated wastewater release took place more than a mile off-shore through the Unit 2 conduit.

The non-radiological release, while only partially treated, had a dilution level of approximately 200:1 (SCE’s NPDES permit for San Onofre calls for a dilution ratio of at least 10:1), before discharge to the ocean at a point more than a mile off-shore. The San Diego Department of Environmental Health determined the release was of low impact and did not require a beach closure. A day after the release occurred, Ron Pontes, SCE Environmental Decommissioning manager, discussed it at the March 26 Community Engagement Panel meeting, which was conducted via Skype due to the COVID-19 pandemic.

What You Should Know

SCE views the wastewater release as unacceptable. We promptly launched an evaluation and made the proper notifications to local, state and federal agencies. SCE also implemented equipment changes and bolstered response actions at the plant prior to re-starting.

In his response to questions from Rep. Mike Levin (CA-49), SCE Vice President and Chief Nuclear Officer Doug Bauder outlined part of the ongoing evaluation's scope. Bauder wrote, “(W)e are looking at whether our actions following that event were sufficient to prevent or minimize the discharge, and to what extent human performance was a factor. An early conclusion is that it would be beneficial to revise procedures for operators and staff, in addition to making certain equipment and system upgrades or modifications, to specifically address our response and the overall performance of the plant.”

We look forward to sharing our conclusions with the Water Quality Control Board, our stakeholders, and the public, including our actions to prevent reoccurrence of an unplanned wastewater release.

(Posted April 23, 2020)