Mayor Brandon Scott took advantage of Baltimore’s strong mayor system to prevent a shipment of toxic waste from an Ohio train derailment headed for a private contractor, accomplishing what public officials across the local, state and federal levels said was impossible after learning of the deal last week.

The contractor, Clean Harbors, planned to treat 675,000 gallons of water contaminated with vinyl chloride and other chemicals following the February derailment and fire. But the company announced Tuesday that they were halting those plans after the city denied Clean Harbors permission to discharge the treated water in Baltimore’s Back River Wastewater Treatment Plant, which empties into a tributary of the Chesapeake Bay.

It’s possible Scott was the only person who could stop the deal between Clean Harbors and Norfolk Southern, which had the approval of the U.S. Environmental Protection Agency. It’s a clear political win for Scott — even his City Hall rivals conceded the point — but it’s not clear how much danger the treated waste posed.

Public officials at the local, state and federal levels spent the weekend bemoaning their limited say on a business deal between two private companies and calling on the EPA to intervene. Scott went from begrudgingly telling The Baltimore Banner on Friday that that “ultimately the waste will come here” to flexing his authority to find a workaround by Monday with the help of city attorneys.

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The law department’s review “determined that the Department of Public Works has the authority to modify discharge permits in an effort to ‘safeguard Publicly Owned Treatment Works (POTW) from interference, pass-through, or contamination of treatment by-products,’” the mayor’s office said in a press release Monday.

“I extend my deepest sympathy to the East Palestine, Ohio community as they grapple with the effects of this devastating derailment on their community, but I must remain steadfast in my commitment to protect our residents — at all costs,” Scott said in a Monday statement. The mayor’s office did not respond to a request for comment Tuesday.

Clean Harbors spokesman Jim Buckley confirmed Tuesday morning that the company will look to treat the wastewater elsewhere, citing the mayor’s action.

“While we are confident that our Baltimore facility is safe to handle and process that waste, as we have made clear from the beginning of this process, we would only be moving forward with the approval of all federal, state and local regulators,” Buckley said in a statement.

Upal Ghosh, a professor of chemical engineering at the University of Maryland, Baltimore County, compared the mesh re-agglomerated carbon nets that Clean Harbors planned to use to a large industrial Brita filter or a gas mask.

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“If it’s done right, it’s a good solution,” Ghosh said. “The key is to be able to monitor to be sure that the treatment process actually works.”

Such technology works to concentrate small amounts of toxic chemicals in a high volume of water into small amounts of solid volume that are easier to contain. Ghosh estimates that the Clean Harbors would have pulled tens or hundreds of gallons of solid toxic waste out of the 675,000 gallons they were slated to receive, and that the company would have sent that product to a hazardous waste landfill.

Clean Harbors told the Department of Public Works that the amount of vinyl chloride detected in samples of the Ohio water ranged from none detected to 62 mg/L or parts per billion (ppb). EPA’s standard for safe levels of vinyl chloride in drinking water is 2 ppb.

“If you want to release that into the bay or the ocean, it has to be treated at least to below that level,” Ghosh said.

The letter also noted reported samples of PFOA and PFOS chemicals at 9.4 parts per trillion (ppt) and 8.7 ppt, respectively, which exceeds EPA’s proposed drinking water standard of 4 ppt.

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Unlike standards for vinyl chloride, the federal agency’s proposal is not yet finalized. PFOA and PFOS — part of a group of chemicals known as PFAS — are man-made chemicals that for decades have been found in everything from nonstick cookware to shampoos.

Because of how long PFAS take to break down, the “forever chemicals” can build up in animals and humans; exposure is linked to some types of cancer and developmental problems. The EPA is still studying the impacts of a few specific PFAS on human and environmental health though long, in-depth evaluations. The city sued a group of chemical companies last year, accusing them of “knowingly” allowing PFAS chemicals to contaminate Baltimore’s water system.

Clean Harbors’ letter proposed filtering the East Palestine wastewater to combined PFOA and PFOS levels of 4 parts per trillion. According to a 2021 report from DPW, a study of Baltimore’s drinking water showed a combined PFOA and PFOS concentration of 4.93 parts per trillion.

“Ideally, I would like none of these chemicals in my water, right?” Gosh said. “But the reality is that they exist, and the way to think about them is to consider what additional harm or lack of harm would come from the treated water being released.”

Dr. Carsten Prasse, an assistant professor of environmental health and engineering at Johns Hopkins, noted that the EPA’s proposed regulations for PFAS include four other chemicals, in addition to PFOA and PFOS.

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“There could be more PFAS present in that wastewater, and if we know for certain there are any amount of PFAS in water, I definitely think it is important to minimize the release,” he added.

He also noted the absence of other chemical samples on Clean Harbors’ letter.

“We know the water contains other contaminants,” Prasse said, “probably present in the wastewater as a result of the combustion during the controlled burning” in East Palestine.

And while Back River would have received the treated water and not the hazardous materials extracted from the original shipment, he still had reservations about sending it to the troubled facility.

“I was very surprised that Baltimore, with all its wastewater infrastructure issues, was even in the discussion” of where Norfolk Southern should send derailment waste, even if Clean Harbors would bring it to EPA standards before it enters Back River, he said. “The Chesapeake Bay is such a fragile ecosystem. It all seems very haphazard.”

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EPA spokeswoman Terri White said last week that the federal agency would have made arrangements to observe the disposal of the hazardous waste. She noted that EPA conducts offsite compliance records review for all facilities that Norfolk Southern is considering for disposal. The company has shipped hazardous waste to facilities across several states, including Texas and Michigan.

In his letter to Clean Harbors Monday, Scott said he could not accept the risk.

“I stand against any efforts that could compromise the health and safety of our residents, and the environment,” he wrote.

Scott’s move led to props from a variety of bipartisan leaders, from county Republican Dels. Kathy Szeliga and Ryan Nawrocki, who framed it as pushback “against the EPA’s attempt to override state and local control,” to Democratic Councilman Zeke Cohen, who called it “bold and decisive action.”

Praise also came from those who were part of a fountain of criticism toward Scott after he approved a controversial agreement with BGE, including city Sen. Mary Washington, who applauded the mayor on Twitter for proving “we are not powerless to take a stand against further degrading our waterways and ecosystems.”