JOINT BASE SAN ANTONIO-LACKLAND, Texas -- The Air Force Installation and Mission Support Center recently launched the service’s first large-scale soil washing effort to remove per- and polyfluoroalkyl, or PFAS, pollutants at Eielson Air Force Base, Alaska.
The $27.6 million military construction-funded project is led by a joint team from the Air Force Civil Engineer Center and the U.S. Army Corps of Engineers, Alaska District, and supports the Department of the Air Force’s effort to address PFAS at the close air support training installation. AFCEC is a primary subordinate unit of AFIMSC.
Soil washing is a closed-loop, water-based process that separates soil fractions and captures PFAS substances in granular activated carbon and ion-exchange resin filters, said Guy Warren, Project Manager at USACE’s Alaska District who manages contract execution.
This remediation technology has been on the market for the past three decades, but the restoration team at Eielson has expanded its applicability to treat highly challenging fluorinated chemicals.
“This is the first-time a full-scale soil washing operation will be used in North America to treat PFAS-impacted soil,” said Michael Boese AFCEC’s Restoration Project Manager at Joint Base Elmendorf-Richardson (JBER), Alaska.
AFCEC awarded the contract through USACE in November 2022 to treat and dispose of 130,000 cubic yards of PFAS-impacted soil that had been excavated during a MILCON project to build infrastructure to house F-35A fighter squadrons.
The cleanup effort began in August 2023 and is projected to be complete in summer 2025.
“Both AFCEC and USACE teams bring deep technical, engineering and environmental knowledge and have played a key role in determining a viable and cost-effective technology to treat Eielson’s soil piles,” said Roy Willis, a Restoration Project Manager for Eielson at JBER.
Prior to selecting soil washing for the Eielson project, AFCEC environmental restoration experts participated in two PFAS pilot studies at Eielson AFB funded by the Department of Defense’s Environmental Security Technology Certification Program. The pilot program provided a site-specific comparison of the cost and performance for two viable technologies – soil washing and thermal desorption.
Additionally, with the support of USACE, the Air Force conducted a similar soil washing study at Colorado’s Peterson AFB.
According to the ESTCP report, the treatability study at the Alaskan installation achieved approximately 70% reduction of PFAS-impacted soil. The data obtained from the AFCEC’s treatability project in Colorado showed high efficiency rates achieving close to 99% PFAS reduction in the coarse soil fraction.
“We determined soil washing to be the most effective technology for the scale and scope of the Eielson project,” Willis said. “The team feels confident this technology will bring successful results.”
Since the project’s kick-off, Eielson’s treatment plant is fully operational and approximately 1,500 cubic yards of soil have been processed. Due to the weather, the field season will resume in May and run through September when the operation is expected to be in full swing and treating 30 cubic yards of soil per hour.
“Once the soil has been cleaned and deemed safe with no PFAS detection or levels below the Alaska state standards, it can then be repurposed for other projects,” Boese said. “However, if there are detections above the state standards, we will dispose it within PFAS guidance.”
The restoration work follows the Alaska Department of Environmental Conservation PFAS soil disposal standards.
Since 2017, AFCEC’s environmental team has been coordinating project requirements with the state and federal regulatory agents ensuring the selected remediation technology is fully approved.
Use of this technology at other Air Force sites will require a significant volume of impacted soil to make it cost-effective and similar soil type, Warren said. For example, PFAS soils with high clay content may not be suitable for this technology.
“We are excited to see the effort is already providing results,” Boese said. “The efficacy of soil washing technology will produce cost and performance data that will help DAF and our regulatory partners program and approve future remediation projects.”