Idaho site marks 30 years of cleanup

December 9, 2021, 7:01AMRadwaste Solutions
The underlying Snake River Plain Aquifer is considerably safer today following three decades of cleanup activities at the DOE’s Idaho National Laboratory Site. (Graphic: DOE)

When the Department of Energy, the state of Idaho, and the Environmental Protection Agency signed a federal facility agreement and consent order in December 1991, the agencies outlined a plan to investigate and clean up, if necessary, more than 500 individual waste areas within the 890-square-mile Idaho National Laboratory (INL) Site, which was established in 1949 to design, build, and test nuclear reactors.

In the 30 years since the agreement was signed, waste sites, consisting of unlined wastewater disposal ponds, debris piles, radioactive groundwater plumes, buried barrels and boxes of radioactive and hazardous wastes, and unexploded ordnance, have all been evaluated—and most of the cleanup is complete, according to the DOE.

“This agreement has stood the test of time,” said Connie Flohr, the DOE's Office of Environmental Management manager for the Idaho Cleanup Project. “It provides the regulatory framework that we still use today to complete our cleanup work.”

The work: As a recent example, crews will finish a project about 18 months ahead of schedule that has removed more than 10,250 cubic meters, or more than 49,000 drums, of radioactive and hazardous waste from an unlined Cold War landfill known as the Subsurface Disposal Area.

Three vacuum-extraction units that removed more than 258,000 pounds of solvent vapors from beneath the landfill and destroyed them with catalytic oxidation technology were turned off in August 2020 to determine if vapor concentrations would meet remediation goals under natural conditions. Sampling and analysis of thousands of vapor samples has shown that performance goals and remedy objectives were achieved early, according to the DOE.

Both of those projects—removing waste from the landfill and use of the vacuum-extraction units—were designed to protect the Snake River Plain Aquifer, which lies 585 feet below the landfill surface.

Water treatment: At the north end of the site, more than 825 million gallons of water have been treated with a pump-and-treat system during the past 20 years. In addition, bioremediation is in progress and consists of injecting sodium lactate or a similar product into a contaminant plume in the aquifer to create conditions favorable for naturally occurring microorganisms to “feed” on the waste. An additional well was completed this past summer to help target a residual trichloroethylene source zone in the aquifer that was inaccessible using existing wells.

“The amount of environmental cleanup work that crews have completed is impressive,” said Fred Hughes, program manager for the DOE’s INL Site contractor Fluor Idaho. “The progress is visible, and the aquifer is benefitting from a host of waste remediation projects.”

CERCLA facility: Construction of the 510,000-cubic-yard Idaho Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) disposal facility in the early 2000s has allowed the DOE to consolidate waste material from many areas of the site into a single, managed landfill that includes several feet of impermeable liners as well as a leachate collection system and lined disposal ponds.

More work: In coming weeks, crews are scheduled to complete targeted buried waste exhumation of the 5.69 acres of the landfill that posed the greatest risk to people and the environment. This completion, coupled with the successful vacuum extraction of solvent vapors from it, protects Idaho residents, wildlife, and the environment by safeguarding the aquifer, according to the DOE.

The environmental remediations have occurred in parallel with efforts to treat radioactive liquid wastes from a tank farm at the INL Site and to ship stored waste of the state for permanent disposal.

Watch now: Click here to watch DOE videos on the agency’s site missions.

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