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DOT&PF was alerted in late July 2018 to concentrations of Per- and Polyfluoroalkyl Substances (PFAS) in the groundwater at Gustavus Airport. The presumed source of PFAS in groundwater at the Gustavus Airport is the Federal Aviation Administration-mandated use of fire-fighting foams at Aircraft Rescue and Firefighting (ARFF) testing areas.
Since then, DOT&PF has worked with an environmental consulting firm, Shannon & Wilson, Inc., and the Alaska Department of Environmental Conservation (DEC) to identify and sample private water wells around the airport. Water sampling was conducted in August, late September / early October, and late October / early November 2018.
Based on those samples, PFAS in 19 wells are reported in concentrations above DEC action levels. Of these, one well serves the Alaska Airlines and Alaska Seaplanes terminals, six wells are used for airplane washing or other non-drinking water uses, and 12 are private or business wells used for drinking water. One of these well results is due to city fire fighting foam use. Concentrations at many private wells and the well which serves the National Park Service water system are below DEC action levels. Many sampled wells show negligible PFAS levels. Based on sample results, the airport-generated plume boundaries appear to be identified within the shallow drinking water zone but further site characterization will confirm this.
To date, DOT&PF’s priority in Gustavus has been to identify and provide safe drinking water to those who need it. DOT&PF is providing alternative drinking water impacted properties.
Together with DEC and engineering consultants, DOT&PF has begun to assess options for long-term solution to provide clean drinking water. DOT&PF is also beginning site characterization, to determine the specific characteristics of the plume, spread, and influencing hydrology.
In order to track PFAS movement in groundwater, DEC requires continued quarterly monitoring of wells with sample results above 35 parts per trillion (ppt) (in yellow on map) and annual monitoring of wells with sample results above 17.5 ppt (in light green on map). In addition to concentration, wells within 500 feet of impacted wells with PFAS concentrations greater than 17.5 ppt qualify for monitoring.
In June 2019 Shannon & Wilson, Inc. conducted quarterly monitoring. During this event, Shannon & Wilson, Inc. also made contact with property owners with drinking water wells located in the previously established sampling area that they had not been able to obtain samples from. Of these new samples, one well located on the same property as a previous exceedance, sampled above the EPA’s LHA level.
In November 2019 Shannon & Wilson, Inc conducted a quarterly sampling event. Approximately 12 samples were collected during this event. Of the sampled wells, one new well serving four structures exceeded the EPA’s LHA level. A total of 20 wells have been reported to have PFAS concentrations above the actionable levels that the department is responsible for.
In August and September 2020 Shannon & Wilson conducted annual sampling of private wells whose PFAS concentrations exceeded 17.5 ppt of PFOS and PFOA combined or wells within 500 feet of those meeting that criteria. Wells that are considered affected were not resampled. Samples were also collected from monitoring wells that were installed in October 2019. Work to begin installing cisterns at impacted properties began. Three wells were drilled and sampled to assist in identifying a possible location for a community well to supplement rain catchment systems. The POET system installed as part of a pilot study was also sampled. Results from this event were similar to historical results excluding one monitoring well. The result will be investigated further with more sampling and sampling of the surrounding area which will be conducted by Alaska DEC.
Shannon & Wilson went to Gustavus in December 2020 quarterly sampling event that includes private wells, monitoring wells, the POET system, and the exploratory wells. Results from this sampling event were similar to historical results, the POET system didn’t see any breakthrough of PFAS, and the exploratory wells ranged from low detections to no detections of PFAS. The department will continue to work with Shannon & Wilson to identify the best option for a community well. Additional sampling took place due to the flooding event. Private wells sampled that are included in quarterly events and additional wells that were in the area in which flooding took place were similar to historical results. Samples taken on airport saw an increase in detections and will continue to be monitored to understand if this was due flooding or seasonal variations.
During the March 2021 sampling event approximately 16 wells were sampled and results indicated similar results to the various trends we have seen in the past. On airport results that were elevated after the flooding event dropped. Further sampling will determine if this was due to seasonal variations or the flooding event.
In June 2021 approximately 20 samples were collected during the quarterly monitoring event. There was one new exceedance. This well was located on a property that was previously sampled but needed to be relocated. All other results were similar to historical data. The site characterization addendum was put out for a public comment period.
In August 2021 an annual and quarterly monitoring event took place. All quarterly and annual monitoring wells will be sampled in addition to those wells within 500 feet, monitoring wells, the POET system and exploratory wells. All samplers were similar to historical data with the exception of one new exceedance. The new exceedance was on a property that had previously been sampled which is located within the impacted area. The POET system remains non-detect for PFAS and isn’t seeing any breakthrough.
Site characterization is planned to begin Oct. 18, 2021 and will consist of increasing DOT&PF’s monitoring well network, sampling of the ditches and will also include private well monitoring. Results will be received 3-4 weeks after the event with a report to follow approximately 60 days after the event.
Additional sampling was conducted in relation to the Runway Resurfacing project. To view those results visit the project website here.
Those who participated in the sampling event will receive a copy of their results at the mailing address they provided. If you have questions regarding sample results please email firstname.lastname@example.org.
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For more information, please contact us.
Shannon & Wilson, Inc.
Kristen Freiburger, Project Manager
Alaska Department of Environmental Conservation,
Contaminated Site Program
Bill O’Connell, Environmental Program Manager
Erin Gleason, Environmental Program Specialist III
Division of Spill Prevention and Response website:
Alaska DEC Gustavus PFAS Database
Alaska Department of Health & Social Services
Sarah Yoder, Public Health Scientist
Andrew Cyr, Toxicologist
Division of Public Health Website:
Alaska Department of Administration
Division of Risk Management
Ken Simpson, Claims Administrator
PO Box 110218
Juneau, AK 99811-0218
Alaska Department of Transportation and Public Facilities
Sammy Cummings, PFAS Program Manager