Airports and airlines across Minnesota have to find a new way to put out fires, as the firefighting foams they rely on to snuff dangerous fuel blazes are being phased out.

For decades, airfields, oil refineries and military sites have used chemical foams to extinguish fires. But these products contain PFAS — a class of chemicals that have been linked to some cancers and that have widely polluted the environment. They have seeped into groundwater in many places where they have been used, including under Minneapolis St. Paul International Airport.

A new state law makes State Fire Marshal Daniel Krier responsible for setting the deadline when airports have to switch to a safer fire suppressant. But MSP's largest carrier — Delta Air Lines — has already warned that it may need extra time.

Even as lawmakers in 2023 ordered the replacement of PFAS foams, it was clear Delta would face a unique challenge in its extensive maintenance hangars, said Rep. Matt Norris, DFL-Blaine, who authored the original bill. This year, lawmakers amended the language to specify that hangars can't be ordered to switch until July 1, 2025.

If the airline were held to the law as it was originally written, "it would require basically shutting down all of the maintenance activities at MSP for Delta for an extended period of time," Norris said.

Delta operates eight hangars at MSP, a maintenance operation second only to its headquarters in Atlanta. Some 15 miles of pipe snake through Delta's fire suppression system, and the company said that moving away from PFAS will not be as easy as simply taking out one product and putting in a new one.

"Providing a safe, secure and compliant operation is Delta's top priority," the company said in an email. "We continue to work alongside state officials and community stakeholders to ensure our emergency fire-suppression systems in our MSP maintenance facilities meets regulatory requirements."

The Minnesota Pollution Control Agency (MPCA) will also deliver a report on airport hangars to the Legislature in January, and that will help lawmakers set the actual deadline for hangars, Norris said.

Some in the industry aren't waiting. MSP has already spent millions to switch to fluorine-free foam, also known as F3. Other airlines, including Minneapolis-based Sun Country, have already made progress toward an eventual deadline.

"We have removed all the foam containing PFAS from our buildings," a Sun Country spokesperson wrote in an email.

Mounting liability

For years, PFAS foams were mandated by the military and the Federal Aviation Administration for their efficacy in smothering fuel fires. But scientific research has slowly uncovered the harms of these per- and polyfluoroalkyl substances.

Firefighters have seen higher incidences of cancer linked to PFAS exposure, both from the foam and from their protective gear that is laden with PFAS. The chemicals leached into soil and groundwater after being repeatedly sprayed in training exercises and on actual fires.

The foams have already proved one of the biggest sources of liability for the companies that made the chemicals, which are used in thousands of products. Maplewood-based 3M, which pioneered PFAS in the last century, agreed to pay as much as $12.5 billion to settle claims from cities and water systems across the country where these foams tainted drinking water. A continuing flood of personal injury lawsuits over the use of the firefighting foam won't head to trial until next fall, though a settlement could be reached before then.

Advocates in Minnesota pushed for the foam ban to stop it from potentially harming more people. Beyond firefighters, any use of the foams "threatens soil and water contamination, which risks human exposure," the MPCA said in an email.

The chemicals are extremely efficient in forming a film that cuts off oxygen, part of why they have been used so long. The military only published its standards for new firefighting foams at the beginning of 2023, and FAA announced in May of that year that products that meet those new specifications can be used in airports.

Krier said he expects high demand from both the military and other civilian airports as these new foams hit the market — and it's not clear when there will be enough available for him to order airports to make the switch.

The authority that runs MSP is not waiting for the mandate to come down.

"While a transition deadline is not yet imminent, the Metropolitan Airports Commission (MAC) began a proactive transition two years ago pre-ordering more than $8 million in new aircraft rescue and firefighting vehicles to accommodate the new F3 alternative," the commission said.

The first vehicle, a 3,000-gallon Oshkosh Global Striker, is already part of the airport's fleet. Three more trucks are expected next spring. Other fire-suppression upgrades to the airport's fuel storage area are planned for this year, and a storage tank will soon be removed.

Firefighters will likely need to be retrained. The FAA noted in a transition plan that firefighters will have to take special care because new formulations of foam do not congeal as well to close up gaps where oxygen might sneak in and feed an ongoing inferno.

Nuts and bolts

While FAA no longer requires PFAS foams, it hasn't mandated their removal. The agency is offering some assistance, though — a federal law that passed this year provides grants and rebates to airports to replace or clean old equipment, dispose of old foams and buy new ones.

"Removing PFAS foams from our airports will eliminate a dangerous exposure point to the deadly toxin," said Edward Kelly, head of the International Association of Fire Fighters, in a statement this spring. "These funds will help make our dangerous jobs safer and will protect the communities we serve. It was long overdue."

There is no similar assistance for airline hangars, which are not under FAA's authority. And in Delta's case, it's not clear how much the transition would cost. A spokesperson said they could not yet estimate the final cost to transform the airline's MSP maintenance facility.

Norris was convinced that Delta's challenges, though, were not about money.

"I see this as a, like, practical challenge of, how do you actually do the nuts and bolts work of transitioning the system over in the midst of an active maintenance facility?" he said.

Delta will likely need to replace significant infrastructure contaminated by PFAS foams. The company is assessing different technologies for each of the eight hangars, to see which would work best in each building. And there's the question of what to do with the old foams — right now, the EPA is recommending "safe storage" as the best option. MPCA warned the foams should be "managed equivalent to hazardous waste."

Ironically, Delta may eventually employ a technology in its hangars with far fewer environmental consequences: water.

The Air Force has also determined it can use water in many of its hangars, according to a recent Government Accountability Office report. A group that sets the regulations for fire sprinklers has also recently approved a water-only sprinkler for hangars, Krier said, though not every building will be able to meet those standards.

But if it does work out, he said, "Then we don't have to worry about 50 years from now that we find out that F3 foam causes a different type of problem. We can say it's just water in the system."