A fault in an electric module likely caused Maine’s largest reported spill of toxic firefighting foam, a new report on the spill’s root cause has concluded.

A lengthy and long-anticipated report from Poole Fire Protection released on Oct. 3 found a fault in a module card — a component of the fire alarm system — likely triggered the discharge of 1,450 gallons of aqueous film-forming foam (AFFF) concentrate mixed with 50,000 gallons of water into Brunswick Executive Airport’s Hangar 4 on Aug. 19, 2024.

The Poole Root Cause Analysis was ordered in January by the Midcoast Regional Redevelopment Authority — the quasi-state entity that oversees the airport and Brunswick Landing — and was partially funded by the Brunswick Town Council.

The foam released in August 2024 contains a toxic PFAS compound, one of several so-called “forever chemicals” that have been linked to serious health problems.

Firefighting foam is the most common source of forever chemical contamination in the U.S., according to the Environmental Protection Agency, but PFAS (perfluoroalkyl and polyfluoroalkyl substances) have shown up in trace amounts almost everywhere, from Arctic polar bears to Maine dairy farmers.

The environmental disaster in Brunswick prompted outcry from members of the community and beyond and led to new laws aimed at ensuring a similar spill never happens again in Maine.

Because AFFF systems are no longer in use at Brunswick Executive Airport, there is no risk of the same malfunction occurring again, MRRA said in an Oct. 3 news release.

MRRA in recent months has gotten rid of its remaining stock of toxic foam, something that was required by a new law Gov. Janet Mills signed in May. The U.S. Army Corps of Engineers trucked away 975 gallons of concentrate from the airport’s Hangar 6 in April and is using it to study foam disposal methods, and in July, the authority closed a $250,000 deal with American Airlines to sell the company 5,925 gallons of AFFF concentrate for use at John F. Kennedy International Airport.

“The Report’s conclusions do not identify any possible causes that have not already been addressed, and validate MRRA’s approach in that effort, and the MRRA board is satisfied that there are no further risk-mitigation efforts relative to AFFF that it needs to target at this time,” the release read.

Last month, the EPA gave MRRA until 2027 to clean or replace its fire suppression systems, but did not fine the authority or hold it responsible for off-campus pollution caused by the spill.

MRRA Executive Director Dan Stevenson asked those with questions on the root cause analysis report to email them to Executive Assistant Katherine Robinson, who is compiling a list for Poole representatives to answer at MRRA’s Oct. 29 board meeting, at [email protected].