Moss Landing Vistra Battery Fire Response: Frequently Asked Questions
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EPA’s Role
Under what authority is EPA overseeing this project?
We have an emergency response and “removal” (cleanup) program under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA).
By law, EPA can require property owners and operators to act to protect the public and the environment when there is/are releases or potential releases of hazardous substances.
We determined that the damaged batteries on Vistra’s property posed a threat to human health and the environment. Damaged batteries are unstable and can re-ignite.
What does the battery removal process involve?
Our oversight will ensure the batteries are properly handled and removed.
- remove batteries from the building for inspection and testing on site,
- de-energize and treat batteries for shipment, and
- safe disposal off-site.
Why are you only overseeing battery removal on-site?
The State of California requested EPA support for oversight of the battery removal under our CERCLA legal authority. We are also bound by our legal authority. We have been asked by the state to:
- oversee the battery removal;
- oversee the assessment, preparation, and packaging of the batteries for disposal; and
- ensure a smooth transition of our oversight duties to state and local authorities once batteries are removed and disposed of.
What is battery delinking and what does it do?
Battery “delinking” is when cables connecting different batteries are disconnected.
At Moss Landing, batteries were disconnected from one another. They were also disconnected from the rack holding the batteries in the energy storage system.
Disconnecting the batteries from one another lowers the risk of fire.
Air
What air monitoring activities did you do during the January fire response?
During the Fire
At the request of local agencies, EPA conducted perimeter and community air monitoring beginning the morning January 17.
- We had nine air monitors set up at and around the property.
- The monitors looked for mineral acid gases like hydrogen fluoride and particulates.
- After smoke subsided, EPA consulted with Monterey County and transferred air monitoring stations to Vistra to continue monitoring.
- We shared our air monitoring data with state and local officials.
- Please visit Monterey County’s “Moss Landing Vistra Battery Fire” dashboard for more information about their response to the fire.
EPA's air monitoring data was provided to local agencies for analysis to inform public health decisions.
What were the results of EPA's air monitoring from January 17 to 20?
- Particulate matter (PM2.5 and PM10)
EPA’s monitoring showed concentrations of particulate matter to be consistent with the air quality index throughout the Monterey Bay and San Francisco Bay regions, with no measurements exceeding the moderate air quality level. - Hydrogen fluoride gas
Hydrogen fluoride gas was measured at one second intervals and there were no exceedances of California’s human health standards.
Post-Fire
- The initial fire subsided on January 18, 2025.
- On January 20, after smoke subsided, EPA consulted with Monterey County and transferred air monitoring stations to Vistra.
- Vistra continued air monitoring at the property and in the community. The data is being provided to the county.
What did you test for during the fire?
We looked for contaminants likely found in a battery fire. The two main contaminants were: hydrogen fluoride and particulate matter.
What air monitoring technology did you use?
To monitor particulate matter, we used TSI DustTrak Monitors. We used the Honeywell SPM Flex (with the mineral acid chemistry cassette) to monitor for hydrogen fluoride.
Are you requiring any air monitoring or sampling during Vistra’s battery removal work?
EPA is requiring air monitoring and air sampling to protect nearby residents and workers during the battery removal process.
Vistra is required to implement air monitoring and air sampling during the demolition and battery handling activities. In the event of a fire, in addition to continuing to have a private firefighting company on-site 24/7, Vistra will implement an EPA-approved emergency response plan and EPA may direct Vistra to conduct additional air monitoring and air sampling.
Is there a difference between air monitoring and air sampling?
Yes. Monitoring and sampling are used to accomplish different goals. Air monitoring is often used for emergencies because you get results immediately. Air sampling collects a sample over a longer period of time. The air sampling results show the average concentration over many hours, but air monitoring shows patterns and changes in real time.
Miscellaneous
Is Moss Landing a Superfund site?
No. "Superfund Site" typically refers to a long term, complex cleanup, (i.e. decades). The Moss Landing response is a short-term action referred to as a "Time Critical Removal Action" to address the potential threat from the impacted batteries to human health and the environment.