Update 14: Maine DEP Commits Extensive Resources to Environmental Testing in the Brunswick Area

January 17, 2025

Over the past several months, the Maine Department of Environmental Protection (DEP) has dedicated significant resources to conduct comprehensive testing of surface water, air, fish, shellfish and residential private drinking water wells as a result of the August aqueous film-forming foam (AFFF) spill in Brunswick.

This extensive effort involved a total of approximately 50 DEP personnel from three of the four DEP bureaus, including the Bureau of Remediation and Waste Management, Bureau of Water Quality and Bureau of Air Quality. Through collaboration across DEP, and with other state and federal agencies, the DEP aims to ensure that all environmental impacts from the spill in the Brunswick Landing area are met.

Surface Water Testing

The DEP continues to monitor the five established sample locations for PFAS in Merriconeag Stream and concentrations continue to decrease. The Department has received 17 sets of sample results since the August 19th AFFF release with the most recent data collected on December 12, 2024.

Recent data shows attenuation of PFAS is slowing as the concentrations between sample events show less variation. The data suggests the August 19th AFFF release continues to discharge residual contamination into the stormwater system and is establishing a new baseline of PFAS concentrations entering the uppermost impoundment in the Merriconeag watershed (Pond A). Overall, the decrease in PFAS concentrations since monitoring began in August are a positive sign, indicating that the PFAS is gradually moving through the watershed and most of the contaminant mass has already passed through the system. Variation of concentrations observed in surface water from one sample event to another is typical given the influence of rain events on flow and stormwater discharge to this watershed.

Sample location SW-66 is the farthest downstream sample location that the DEP has been monitoring and is collected in the tidally influenced portion of Merriconeag Stream. With winter conditions making access to this sample location more difficult, SW-66 will not be sampled moving forward in the upcoming sample events. The need to include this sample location in additional sample events will be evaluated once the area is deemed safe for DEP staff to resume collection. Time sequenced data collection continues to be a priority to monitor site conditions at the remaining four surface water sample locations.

Second Round of Residential Private Well Sampling

The second round of residential samples were collected on December 11 and 12, 2024 from private wells along Coombs Road to assess for PFAS impacts associated with the August 19th AFFF spill. Results of these samples were generally consistent with the samples collected in September with minor fluctuations both increasing and decreasing in wells tested. Two water supply wells reported PFAS concentrations over the Maine Interim Drinking Water Standard, and these wells were resampled on January 8th to confirm the results. Results of the January re-sampling event reported PFAS concentrations below the Maine Interim Drinking Water Standard, and the Department is not recommending filtration for PFAS at this time. The Department does not recommend expanding or altering the residential well sampling plan, and will continue to monitor the private wells identified along Coombs Road with the next sampling event planned for March 2025.

Fish and Shellfish Sampling in Harpswell Cove, Mare Brook, Merriconeag Stream, and Androscoggin River

DEP has received the results of the PFAS study of shellfish tissue samples from Harpswell Cove that were taken three and five weeks after firefighting foam spilled. Fish and shellfish tissue samples inherently take longer to process than water samples. Processing tissue samples requires additional challenging steps, including homogenizing, subsampling, and extracting PFAS from tissue and putting the PFAS in a liquid. In addition, there are fewer labs capable of analyzing fish and shellfish samples compared to the number of labs capable of analyzing water samples. The combination of a more complicated laboratory protocol for tissue samples and a shortage of labs capable of analyzing fish and shellfish samples has resulted in a turn-around time of several months for processing fish and shellfish samples.

Following the spill, as a precautionary measure, the Maine Department of Marine Resources (MDMR) established an emergency closure area which has been closed to shellfish harvesting. The primary PFAS of concern in fish and shellfish is perfluorooctane sulfonic acid (PFOS). Maine's fish tissue action level (FTAL) for PFOS is 3.5 nanograms per gram (ng/g wet weight), which is equivalent to parts per billion. Concentrations of PFOS in softshell clam, blue mussel, and American oyster tissues were higher than the FTAL in the samples collected three weeks after the spill. Concentrations of PFOS markedly decreased in samples collected five weeks after the spill, but were still slightly above the FTAL. DEP, in collaboration with the Town of Brunswick, the Maine Center for Disease Control and Prevention (Maine CDC), and MDMR, reviewed PFOS concentration results. Since concentrations at five weeks post-spill were slightly higher than the FTAL, DEP has submitted samples of softshell clam, quahog, and blue mussel tissues that were acquired in November by Brunswick and DEP staff for laboratory analysis to ascertain whether PFOS concentrations dropped below the FTAL. Lab results from the November samples are expected to be returned by March 2025.

In August 2024, the Maine CDC issued a fish consumption advisory for Mare Brook and Merriconeag Stream based on concentrations of PFOS in brook trout, black crappies, and American eels collected in 2023 by the Navy. The public was advised "do not eat" fish collected from Merriconeag Stream, Picnic Pond, and parts of Mare Brook that are east of the airport runway. The samples collected before the spill ranged from 28 to 298 ng/g PFOS. DEP collected brook trout, black crappies, and American Eels from Mare Brook and Merriconeag Stream following the spill. Concentrations of PFOS in Merriconeag Stream fish ranged from 528 to 4,687 ng/g. Further downstream, concentrations of PFOS in Mare Brook fish ranged from 226 to 893 ng/g. DEP also found low concentrations of PFOS (1.5 ng/g) in brook trout collected upstream of the airport. In summary, the release of firefighting foam greatly increased the concentration of PFOS in fish from the affected parts of Merriconeag Stream and Mare Brook, but as there was already a do not eat advisory in place, there is no change for fish consumption advice given these latest data.

The Department collected and analyzed fish from the Androscoggin River before the spill (2022 & 2023) and after the spill. Due to the spill, firefighting foam made its way to the Brunswick Sewer District (BSD) wastewater treatment facility, and ultimately PFAS from the spill was discharged to the Androscoggin River. Before the spill, concentrations of PFOS in smallmouth bass ranged from 10 to 17 ng/g. After the spill, samples of smallmouth bass collected downstream of the BSD wastewater treatment facility ranged from 9 to 17 ng/g. Samples of smallmouth bass collected upstream of the wastewater treatment plant and the Fort Andros dam had 6 to 8 ng/g PFOS. Overall, the amount of PFOS in downstream fish was comparable before and after the spill. MCDC has a fish consumption advisory (6-12 meals per year) for the lower Androscoggin River due to historic PCB contamination. This advisory remains sufficiently protective.

Brunswick Sewer District (BSD) effluent sampling

The Brunswick Sewer District (BSD) is continuing to analyze effluent samples for PFAS. Results for samples collected in December and January are pending.

Ambient Air Sampling

In response to community concerns about the potential for ongoing air exposures following the AFFF spill, the Department investigated potential ambient air sampling methods for the per-and polyfluoroalkyl substances (PFAS) compounds found in AFFF. This type of sampling had not been previously conducted by DEP. A method used by another state was selected for use in our study. DEP staff collected three 72-hour ambient air samples for PFAS analysis, along with two blank samples used for quality control checks. Using high-volume air samplers, over 390,000 liters of air were sampled by each instrument during the sampling period. Laboratory analysis results indicated low ambient air concentrations of many PFAS compounds found in AFFF. Nearly all PFAS compounds detected in the samples were found at concentrations well below provisional health-based air screening levels. One compound, PFOA, was detected at concentrations above the provisional cancer screening level. However, this screening level simply indicates an increased risk from long-term exposure to PFOA in ambient air above the threshold and does not necessarily indicate increased risk from short-term exposure. Based on separate calculations, analysis of PFOA data suggests that exposure at the level found in ambient air at BNAS is not likely to result in any measurable increase in blood levels over expected current background blood levels in the U.S. population. To better understand the results of this first round of sampling, specifically whether levels are increasing, decreasing, or remaining constant, additional sampling is planned in Brunswick. In addition, sampling will be performed at an identified location in Acadia National Park to better understand background ambient air levels of PFAS in ambient air without a known PFAS source.

Results from Additional Soil Sampling

Additional soil samples were collected from an area north of the second impoundment in the watershed (Pond B) to provide delineation of PFAS concentrations detected in the incremental sampling methodology results from October 22, 2024 that exceeded the Maine Department of Environmental Protections Remedial Action Guideline (RAG) for the Park User Exposure Scenario. A series of six discrete soil samples were collected in a transect moving away from the pond and results showed that PFAS concentrations only exceed RAGs regulatory criteria at the location sampled closest to the pond. This sample is located on Navy owned property and is posted no trespassing. Six composite soil samples were collected from small, raised garden beds that are used by a nearby business and all results received had concentrations at or below the DEP published background soil concentrations for urban developed soils. One additional incremental soil sample was collected around the nearest building which houses two local businesses. Results of this sample are also at or below the DEP background soil concentrations for urban developed soils for compounds with published values. All these results indicate impacts to soil around Pond B from the August 19th spill are confined to Navy owned property and are isolated from public exposure. The Bureau of Remediation and Waste Management does not plan to collect additional soil samples around Pond B at this time.

All DEP sampling results and locations are posted on the DEP Site Map. The DEP will continue to provide updates as new data becomes available.

For additional information, contact: David R. Madore, Deputy Commissioner [email protected]

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