The county in April filed a lawsuit in state court against dozens of companies, including DuPont and 3M, accusing them of making and selling products for decades despite knowing the contents were toxic and would not break down once released to the environment.

Last month Chemguard, which operates a foam manufacturing plant in Marinette, and its parent company, Tyco Fire Products, had the case transferred to federal court, where it has been consolidated with hundreds of other cases from around the country, including one filed by the city of La Crosse.

Assistant Corporation Counsel Amy Tutwiler said the change of venue doesn’t change the county’s position and will simply streamline procedures.

“The case will proceed in the same manner as any other lawsuit,” Tutwiler said.

According to the complaint, the defendants began selling a water-based foam in the 1960s known as AFFF made with PFOA and PFOS, two of thousands of fluorinated compounds generally known as PFAS.

Highly effective for extinguishing liquid fuel fires, the foam continues to be used at airports and military bases, though the complaint claims AFFF can be made with different PFAS compounds.

The suit claims the defendants knew — or should have known — since the early 1980s that using AFFF according to their instructions would release PFAS to the air, soil and groundwater and that the chemicals could damage the liver, kidneys and nervous system, among other negative health effects.

Because of the manufacturers’ failures, the suit alleges the airport continues to be contaminated, creating an environmental hazard and forcing the county to investigate, monitor and clean up the damage “at significant expense.”

Tyco says because it was a government contractor making products to meet specifications set by the Department of Defense it is immune from such liability claims. The company also notes that since 2006 commercial airports like Madison’s have been required to stock firefighting foam that meets those military specifications.

Tyco argues it can’t be held responsible under state law for design choices dictated by the military.

Tutwiler declined to comment on Tyco’s claims but said “we are confident in our legal right to proceed despite raised defenses.”

In 2018, the Department of Natural Resources informed the county, Wisconsin National Guard and the city of Madison that they were responsible for PFAS contamination at and around the airport, including several “burn pits” where firefighters trained with the toxic foam.

The National Guard Bureau is heading the remediation effort using a federal process under which actual cleanup may not begin for at least a decade.

Earlier this year a Waukesha County judge said the DNR lacks authority to enforce the state’s spills law without first going through the Legislature, though that ruling is on hold while a state appeals court reviews the decision.