PFAS Around Brunswick Naval Air Station

Map showing the location of the PFAS spill

On Aug. 19, 2024, an accidental release of approximately 1,450 gallons of PFAS-based Aqueous Film Forming Foam (AFFF) concentrate mixed with 50,000 gallons of water occurred in Hangar 4 on the former Brunswick Naval Air Station. See below for more information about this spill. Based on data from the Department of Environmental Protection, perfluorooctane sulfonate (PFOS) was the primary PFAS compound of the released foam, making up 77% of the measured PFAS compounds.

Based on current information, the foam/water mixture released in Hangar 4 entered the stormwater system, which connected to a series of ponds (“Pond A,” “Pond B,” “Picnic Pond”) into Mere Brook. Mere Brook drains into the upper Harpswell Cove. Due to the historic contamination of the Air Station superfund site, this area of Harpswell Cove has been closed for shellfish harvesting since 2016 (see DMR webpage).

This webpage is up to date as of Sept. 18, 2024. Data collection is ongoing and future results will be shared periodically below.

Bigelow Laboratory’s PFAS Monitoring Program

Bigelow Laboratory has been monitoring PFAS in areas around BNAS through a Casco Bay-wide project since 2023 in collaboration with Friends of Casco Bay FOCB; (funded by Maine SeaGrant). Bigelow Laboratory and FOCB will follow up with three bay-wide monitoring campaigns in 2024 and 2025 through an EPA/National Estuaries Program-funded project (see map below). In addition, Bigelow Laboratory started a weekly sampling at selected monitoring stations immediately after the spill to complement DEP sampling. For all monitoring activities, samples are analyzed in the institute's PFAS Facility using EPA Method 1633 (40 PFAS). Bigelow Laboratory is state-accredited for PFAS analysis (www.bigelow.org/pfas).

Pre-Spill Concentrations around Harpswell/Brunswick

The map below shows the concentrations of PFOS across Casco Bay in 2023. The numbers show the concentration in nanograms per liter (ng/L) or parts per trillion (ppt).

• Across Casco Bay, low levels of PFOS were detected at most sites (as compared to the new EPA drinking water standards of 4 ng/L or 4 ppt). These concentrations correspond to background levels that can be found in most marine environments along Maine’s coast.
• Slightly higher values — but still relatively low — were observed along the Kennebec Estuary and in the Androscoggin River. Rivers can be impacted by agricultural runoff from sites that have historically been treated with PFAS-containing biosolids or by discharge of storm- or wastewater.
• At Harpswell Cove, low tide PFOS levels were approximately 5 to 10 times the EPA drinking water limits in the mouth of Mere Brook. However, these concentrations were diluted within a short distance; all other Harpswell stations showed background levels of PFOS.

Post-Spill Measurements, August 2024

The figure below shows PFOS concentrations (in ng/L or ppt) for two Bigelow Laboratory sampling events (8/20/24 and 8/26/24) and two DEP sampling events (8/22/24 and 8/25/24; data from DEP website). The data show that PFOS entered Mere Brook via the retention Ponds (Pond A/B/Picnic Pond). A few days after the spill, PFOS concentrations larger than 8,000 ng/L were observed close to Harpswell Cove.

More Information

Information about the spill and response can be obtained from these websites:

• DEP
• Town of Brunswick
• Midcoast Region Redevelopment Authority
• Brunswick Area Citizens for a Safe Environment

Background and remediation information about BNAS Superfund Site can be found here:

• Brunswick Naval Air Station Superfund
• Brunswick Naval Air Station Administrative Records
• US Navy Defense Base Closure and Realignment Act

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