More than 3 million gallons of the foam and related waste have been retrieved from U.S. Navy, Marine Corps, National Guard, Army, and Air Force bases around the world. Now the question is what to do with them. Known as aqueous film-forming foam, or AFFF, it was originally created to put out jet fuel fires. AFFF is flame-resistant by design and contains PFAS chemicals, such as PFOA and PFOS, which cause a wide range of health problems and last indefinitely in the environment.

For decades, the military has been using AFFF to put out fires and to train military firefighters; that training involved spraying the foam onto blazes that were purposefully set in pits, many of which were unlined. From there, PFOS, PFOA, and other chemicals in their class seeped into groundwater in and around U.S. military bases at home and abroad.

Because of environmental concerns about the chemicals, which are associated with kidney cancer, testicular cancer, immune dysfunction, and many other health problems, the Air Force decided in 2016 to stop using foam that contained PFOA and PFOS, and began replacing the foam at installations worldwide. Unfortunately, as The Intercept reported last year, the new foam contains only slightly tweaked versions of the same problematic compounds, so it is likely to present many of the same health and environmental risks.

For the Air Force, the question of how best to dispose of the old foam comes too late. In January 2017, a waste disposal company hired by the Defense Department began incinerating more than 1 million gallons of the foam and AFFF-contaminated water that had been collected from Air Force bases around the country. According to the contract, the incineration was to be complete by this month.

But that leaves more than 2 million gallons of foam and contaminated water from other branches of the military, as well as unknown quantities possessed by nonmilitary airports and firefighters, which some states have recently begun to collect.