Pease Air Force Base
Investigation and cleanup of PFAS releases at the former air force base in New Hampshire.
The former Pease Air Force Base (AFB) site is located in the towns of Newington and Greenland and the City of Portsmouth. Construction of the Strategic Air Command base was completed in 1956 and on March 31, 1991, Pease AFB was officially closed under the Base Realignment and Closure Act (BRAC). Today the former Pease AFB is one of the most successful redeveloped BRAC bases in the nation, home to over 250 businesses employing more than 10,000 workers on the Pease Tradeport.
Pease AFB was officially listed as a National Priority List (NPL) Superfund Site on February 21, 1990. The environmental cleanup of the former Pease AFB is currently divided into two programs:
- Investigations and cleanup activities focused on per- and poly-fluorinated alkyl substances (PFAS) primarily associated with the Air Force’s historical use of AFFF fire-fighting foam.
- Installation Restoration Program (IRP) for the investigation and cleanup of hazardous waste and petroleum releases.
The Air Force maintains the official Administrative Record for Pease. Reports summarizing investigations and other site-specific documents are public record and are accessible on the U.S. Air Force Civil Engineering Center (AFCEC) Administrative Record website. To find PFAS-related records, go to the Administrative Record website and select BRAC>Pease AFB>OU-9 PFC Operable Unit then click “Search” to view the document listing. IRP records can be searched under the other Operable Unit (OU) tabs. The Air Force also maintains a physical document repository at their offices located at the former base. File reviews can be requested through the Contacts listed on the AFCEC website for Pease. PFAS-related documents are also posted on the NHDES Onestop database under the main NHDES Site # for Pease:198404025, Hazardous Waste Project #34346.
Sampling, Testing and Treating
The Air Force began work under the PFAS Program in 2013 with groundwater sampling at the former Fire Department Training Area-2 (IRP designated “Site 8”), which discovered the presence of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) at concentrations above the EPA Provisional Health Advisory (PHA) that was in place at that time. Subsequent sampling of the three Pease Tradeport public water supply wells in April 2014 documented PFOS in the Haven Well sample above the PHA. The Haven Well was immediately shut down and the Air Force began response actions to investigate the magnitude and extent of PFAS in site groundwater and off-site neighboring private water supply wells. In 2015 the Air Force was issued an Administrative Order (AO) by EPA under the Safe Drinking Water Act to investigate and remediate PFAS sources, restore the Pease aquifer, provide treatment of the Pease municipal water supply system (including the Haven well), and monitor and protect residential and municipal water supply wells. The three main areas of work under the AO are:
- The water supply treatment system operated by the City of Portsmouth.
- Investigation and remediation at Site 8.
- The airfield where AFFF was also released and where the Haven Well aquifer is located.
Site 8-related PFAS work has included residential well inventory and monitoring program, site investigations, pump tests and computer modeling to evaluate contamination migration and to support the design of a groundwater containment and treatment system. The groundwater containment system is designed to prevent further offsite PFAS groundwater contamination migration into the town of Newington. Construction of the groundwater pump and treat system began in 2017, and the system started operation in 2018. Performance monitoring is ongoing.
Concurrent with initial response actions and completion of a CERCLA Preliminary Assessment for PFAS to identify areas where fluorinated Aqueous Film-Forming Foam (AFFF) was released, the source of the widespread PFAS at Pease, the Air Force conducted a base-wide PFAS site investigation (SI) to better understand the nature and extent of PFAS in soil and overburden and bedrock groundwater. The SI was completed in 2016. This information was used to develop a conceptual site model of PFAS contamination and to develop a groundwater remediation plan called the Airfield Interim Mitigation System (AIMS).
A groundwater pump and treat system designated Airfield Interim Mitigation System (AIMS) was constructed to restore the Haven aquifer. The system is designed to capture contaminated groundwater in the northern portion of the aquifer, treat the groundwater and then discharge the treated water up- and downgradient of the Haven well. These actions will help restore the aquifer over time and prevent higher levels of PFAS contamination from flowing towards the Haven Well and further impacting groundwater quality.
A supplemental PFAS investigation, designated as Expanded Site Inspection (ESI), was conducted in 2018 and 2019 to further evaluate the relationship between overburden and bedrock groundwater and surface waters, both base-wide and with particular focus in Newington, north of Site 8. The ESI also included PFAS characterization and an exposure assessment of other media (soil, sediment, surface water and shellfish). Results of the ESI were shared with the public at the 2019 Pease Restoration Advisory Board (RAB) meetings. Key conclusions of the ESI include: 1) additional investigation and risk assessment was warranted as part of the next CERCLA phase, a Remedial Investigation (RI); 2) though PFAS were detected in shellfish collected from various locations, the detected concentrations did not exceed the Screening Levels (SLs) established for three PFAS by EPA. NHDES’ Environmental Health Program conducted a site-specific evaluation of PFAS in shellfish and concluded that a shellfish consumption advisory for PFAS was not warranted. The Final ESI report was published in March 2020.
The Air Force began the Pease PFAS Remedial Investigation (RI) in 2020. The primary objectives of the RI include determining the nature and extent of PFAS in various media by filling in the data gaps identified in the investigations and to identify preliminary remedial options (including evaluation of the existing PFAS treatment systems) to inform the next steps in the CERCLA process. A comprehensive outreach effort to property owners in the vicinity of Pease was conducted in fall 2020 to gather additional information about the presence of surface waters, springs, seeps and non-potable wells on off-base properties as well as agricultural practices in the community to better inform the development of the Human Health Risk Assessment and Ecological Risk Assessment being conducted as part of the RI. Several technical sessions were held in early 2021 to seek input from Pease stakeholders including concerned community members as well as the City of Portsmouth and Pease Development Authority. This information was considered during the development of the RI Work Plan. The first phase of field work to refine the nature and extent of PFAS began in spring 2021. Evaluation of the phase I results was used to support a follow-on investigation phase in fall 2022 and the risk assessments required under the RI. The Air Force anticipates the RI will be completed in 2023.