A project to passively remove nonradioactive contaminants from the soil and groundwater at the Department of Energy’s Savannah River Site in South Carolina is coming to an end, as workers prepare to remove solar-power “plugs” from 19 soil remediation locations at the site.
According to the DOE’s Office of Environmental Management, completion of the project, conducted at an earthen pit developed in the 1950s to dispose of construction debris, ash, and liquid cleaning products, will result in an annual cost savings of $90,000 to the department.
The 19 solar-powered microblower systems, which generate a natural vacuum to exhaust chemical vapors from belowground, were installed to remove low concentrations of commonly used degreasing solvents from the soil. Recent soil sampling demonstrated that the site no longer poses a potential threat to the environment, said Will Jolin, engineer with DOE contractor Savannah River Nuclear Solutions (SRNS).
Active vs. passive: “Early cleanup at this location concentrated on using aggressive methods to remove the contaminants from the subsurface and prevent them from migrating to the groundwater,” said Joao Cardoso-Neto, SRNS project manager.
Cardoso-Neto noted that those cleanup technologies required use of large electric pumps, support facilities, and monitoring equipment. Over the years, the highly mechanized and costly active systems removed the majority of solvent from the soil, leading the DOE to transition to the more environmentally friendly passive microblower units, which were able to remove the remaining trace amounts of solvent to within limits set by the South Carolina Department of Health and Environmental Control and the U.S. Environmental Protection Agency.
Each microblower unit requires only 20 to 40 watts of solar power to run a primary component: a compact, high-speed fan. During a 10-month test, a single unit removed 234 pounds of solvent compounds from the subsurface, the DOE said.
Approximately 1.5 acres were impacted by the cleanup and closure project near a part of the site designated as A Area.
“With the closure of this project, we can shift the resources, such as solar panels, to other areas at SRS that still require remediation,” said John Bradley, SRNS engineer.