Vistra Fights PFAS Testing After Battery Fire

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Grey smoke billows from the black hole gaping in the roof of Vistra’s battery storage facility. Next to it, a pool of water on unpaved gravel. This photo, published by Monterey County Now, and showing a fire at the Vistra facility, was included in regulatory filings published by the Central Coast Regional Water Quality Control Board, which has ordered that Vistra test the surrounding area for a range of toxic chemicals. 

On May 15, the Water Board ordered Vistra to investigate whether the water pools surrounding its facility contained contaminants that could seep into groundwater. This is one of three investigative orders the Board issued to the company. The Water Board had already sent two other orders on April 25. One ordered the company to test the firefighting water used during the January fire that Vistra is storing in an onsite pond. Link

The other required Vistra to assess whether surface water bodies nearby, including the Elkhorn Slough estuary and Moss Landing Harbor, have been impacted by flying soot and ash. Link

Among the testing requirements are lab tests for per- and polyfluoroalkyl substances (PFAS), so-called forever chemicals, which have been linked to an “increased risk of some cancers, including prostate, kidney, and testicular cancers,” according to the EPA.

Vistra has been pushing back. 

In a May 5 letter to the Water Board, the company said that other than the chemical polyvinylidene fluoride (PVDF), PFAS “are not associated with the battery modules and no firefighting foam or other potential PFAS sources were used during or after the fire.” Because PFAS are already “ubiquitous in the environment,” the company argued that even if they were detected in testing samples, they could not be definitively linked to the Moss Landing fire. 

Vistra also said there is no “direct method to analyze PVDF in environmental samples,” and that this type of forever chemical has limited impact on human health and the environment, anyway. The company therefore deems testing for PVDF “neither necessary nor feasible.” Vistra excluded PFAS analysis altogether from the work plan for testing firefighting water stored in an onsite retention pond it submitted to the Water Board. 

Asked by Hunterbrook whether it had reviewed academic studies linking PFAS to battery fires, Vistra did not respond. The company had previously told Monterey County it would not answer Hunterbrook questions at county press briefings. 

Studies Suggest Link Between Battery Fires and PFAS Contamination 

In a recent study, scientists at the RISE Research Institutes of Sweden, an independent, state-owned research institute, started eight lithium-ion battery fires in a lab environment and tested emitted soot and particulates for 22 types of PFAS. 

They found forever chemicals in every sample. 

One of the substances that was present after all battery fires was perfluorooctanoic acid (PFOA), which was phased out of production in the U.S. at the end of 2015. The National Toxicology Program considers PFOA to be “an immune hazard to humans,” and several scientific studies suggest the substance might increase the risk of testicular cancer or kidney cancer, according to the American Cancer Society. 

The RISE researchers said the PFOA formed during combustion could potentially originate from PVDF used as an “electrode binder and separator material in lithium-ion batteries.” PVDF is also part of the batteries used at the Moss Landing facility; one of the study’s authors confirmed to Hunterbrook that Vistra’s batteries are similar to those used in their lab tests. 

Tove Mallin, a senior researcher at RISE and PFAS expert, said that even though PFAS are indeed ubiquitous in the environment, it would still be possible to link heightened levels of specific PFAS types found in test samples to the battery fire. 

“I would distinguish between point sources, where you have a higher concentration and a more diffuse contamination in the environment,” said Mallin. “You don’t see all PFAS everywhere in the environment. After you extinguished a fire, for example, you will find the fingerprint from the specific PFAS that were used there.” 

Her colleague Maria Quant, a researcher on the Fire and Safety battery team at RISE and one of the co-authors of the battery fire study, agreed. “The company can take reference samples somewhere close by, in a similar area that hasn’t been impacted by the fire,” she said. “If they have some of the extinguishing water, they should definitely test it. And if it’s contaminated, someone should clean it up.”  

The Water Board similarly dismissed Vistra’s argument for omitting PFAS testing, citing the RISE study. In a May 15 letter, it rejected Vistra’s work plan for pond water testing as “incomplete” and “inadequate.” The Water Board said that it doesn’t matter whether PFAS are explicitly listed in the product safety data sheet of the batteries used at Vistra’s facility, since the forever chemicals could also have been generated during the fire or they could have been present in coating on wires and cables elsewhere in the building. 

In its letter, the Water Board reminded Vistra that “any person who fails to submit reports in accordance with the [Investigative] Order is guilty of a misdemeanor” and that it may fine the company up to $1,000 per day if the necessary documents aren’t submitted on time. To comply with the order, the company needs to submit a new plan that meets the Board’s requirements “as soon as practical.” Alternatively, Vistra can submit a full technical report with the completed tests the Water Board had ordered by May 29. 

Monterey County Allows Vistra to Skip PFAS Testing

While the Water Board is enforcing its standards despite Vistra’s protests, the Monterey County Environmental Health Bureau appears to have dropped the PFAS testing requirement.

In a March 13 letter, it had outlined requirements for additional community soil sampling to assess potential health risks from the fire and ordered Vistra to submit a work plan that met those conditions. While the Bureau rejected Vistra’s first sampling plan submitted on March 26, it approved a reworked version from April 17, according to regulatory filings.

This finalized work plan does not include PFAS testing, even though the County’s original letter had specifically listed it as a requirement. Among other substances of concern that were dropped from the work plan between the County’s letter and Vistra’s final version are asbestos and several metals like arsenic, barium, and chromium.

The final plan indicates that the County did ask the company to make several changes after it had submitted the first version: The document states that lead and pH were added as analytes “at the request of” the Environmental Health Bureau. The Bureau also required Vistra to add analysis for “polycyclic aromatic hydrocarbons (PAHs), dioxins, and furans” at locations that were within the fire’s soot plume and testing sites where ash or debris are visible during sampling. The County’s March letter had required tests for PAHs, dioxins, and furans for all collected samples. 

“The preliminary list of contaminants of concern identified by the Environmental Health Branch (EHB) was developed in consultation with a multi-agency group, including the State Water Resources Control Board (SWRCB),” a County spokesperson told Hunterbrook in an email. “The SWRCB has elected to address sampling requirements directly with Vistra. The revised list focuses on potential soil contaminants associated with the footprint of a battery fire and acknowledges that further analyses may be required based on sampling results.” 

The Central Coast Water Board is one of nine regional water boards in California and works in coordination with the State Water Resources Control Board.

County community soil testing started on May 8. Vistra consultant Terraphase Engineering is conducting sampling, overseen by the Environmental Health Bureau and Department of Toxic Substances Control. Twenty-seven testing sites around the Vistra facility have been selected and results are expected within three to four weeks after sampling. The DTSC will obtain one duplicate soil sample at each site to conduct its own lab tests and confirm Terraphase’s results. According to the County, it is also currently developing a separate plan for surface water testing.

“We need to get more information on the impact of the incident. And the community plan was carefully thought out with input from, again, our state regulatory partners,“ Ricardo Encarnacion, the County’s Director of Environmental Health, said at the May 7 County news briefing. “Information is what will help drive our further actions, and also working with the responsible party to address any issues.” 

But that information, for now, will not include PFAS test results.

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