- California approves pilot groundwater treatment study.
- DOE to test biological and chemical methods at ETEC site.
- Interim cleanup continues while long-term plan develops.
Monday, September 15, 2025 — On September 11, 2025, the U.S. Department of Energy (DOE)
confirmed that a groundwater remediation pilot study had received approval to proceed. The California State Water Resources Control Board granted a permit in July for the study at the Hazardous Materials Storage Area within Area IV of the 2,850-acre Santa Susana Field Laboratory (SSFL). The site, once home to rocket engine testing and nuclear research, includes the Energy Technology Engineering Center (ETEC), operated by DOE in previous decades.
How the Study Will Work.
The in-situ, or in-place, approach involves injecting both biological and chemical amendments into separate wells to create a reductive environment. According to Dr. Josh Mengers, DOE’s federal project director for ETEC, this process is designed to stimulate natural degradation of groundwater contaminants. By testing both types of amendments, the Department hopes to compare effectiveness and possibly achieve a stronger combined treatment.
“This pilot is being conducted on a small scale because we want to understand the sphere of influence these amendments will have on the contaminants,” Mengers explained. “We’re not proposing that this is going to be the solution, but we’re testing it out to see how well it works.”
Public Education and Oversight.
The pilot design was first demonstrated during an April 2024 workshop series called Groundwater University. The series, organized by the California Department of Toxic Substances Control in cooperation with DOE, Boeing, and NASA, allowed the public to learn about groundwater conditions at SSFL and prepare to review future site decisions.
Other Interim Actions at Area IV.
The pilot is one of several interim steps taken while DOE works toward a comprehensive cleanup plan. A record of decision for groundwater cleanup was published in November 2020, outlining long-term monitoring and treatment methods as well as interim measures.
In May 2024, DOE installed a solar-powered, automated pump system at the Former Sodium Disposal Facility, replacing much of the manual pumping that had been ongoing since 2017. Combined efforts from both systems have removed more than 67,000 gallons of contaminated groundwater to date.
Long History of Monitoring.
Groundwater oversight at the site dates back to the late 1980s when the department first installed monitoring wells to track contaminants. Today, approximately 100 wells are located in Area IV, many of which are sampled quarterly to evaluate conditions and track progress.
DOE emphasized that the pilot study represents one piece of a broader strategy to manage contamination and safeguard surrounding communities while permanent cleanup solutions are being pursued.
